WorldWideScience

Sample records for cathode sputtering

  1. Sputter deposition of BSCCO films from a hollow cathode

    International Nuclear Information System (INIS)

    High-Tc superconducting thin films were deposited onto MgO single crystal substrates from a hollow cathode onto ceramic targets with the nominal composition of Bi2Sr2CaCu2Ox. Films similar in composition to those used for the targets were deposited on MgO substrates by rf sputtering. The effects of sputtering time, rf power, and post-annealing on film microstructure and properties were studied in detail. Substrate temperature was found to have a significant influence on the film characteristics. Initial results show that deposition rates from a hollow cathode are an order of magnitude higher than those of a planar magnetron source at equivalent power levels. Large deposition rates allow for the coating of long lengths of wire

  2. Contribution to crystallographical and mechanical analysis of molybdenum coatings prepared by magnetron cathode sputtering

    International Nuclear Information System (INIS)

    Molybdenum coatings with different compression stresses are obtained by magnetron cathode sputtering by varying negative voltage applied to the substrate during deposition. Stress evolution, crystal texture and argon content are studied

  3. Mass distribution of sputtered cathode material in the reflex discharge along the magnetic field mirror configuration

    International Nuclear Information System (INIS)

    he paper is concerned with the distribution of cathode material sputtered under the action of the pulsed reflex discharge plasma and deposited on the anode surface (vacuum chamber) by means of a set of discrete receiving plates. Correlative relationship has been found between the weight gain increase of the receiving plates due to the deposition of cathode material (Ti) particles on them and the increasing magnetic field regions. The maximum possible sputtering yield Ycurr has been evaluated. The authors have deduced parametric dependences of the sputtering ratio on the power function exponent that determines the shape of the radial plasma-density profile, and also, on the magnetic field induction value

  4. Deposition of SiC thin films using pulsed sputtering of a hollow cathode

    Czech Academy of Sciences Publication Activity Database

    Soukup, R. J.; Ianno, N.J.; Huguenin-Love, J.L.; Lauer, N.T.; Hubička, Zdeněk

    2009-01-01

    Roč. 3, č. 8 (2009), s. 1-4. ISSN 1934-8959 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : hollow cathode * pulsed sputtering * 4H SiC Subject RIV: BH - Optics, Masers, Lasers

  5. A cathodic arc enhanced middle-frequency magnetron sputter system for deposition of hard protective coatings

    International Nuclear Information System (INIS)

    A new cathode arc enhanced magnetron sputter system for deposition of hard protective coatings is reported in this article. This system consists of eight targets: four outer targets are mounted on the wall of the chamber and four inner targets are placed around the center of the chamber. The outer and inner targets form four pair targets and are powered by four middle frequency power supplies. One of the outer targets can run either in the cathode arc mode or in the magnetron sputter mode. The Ti-containing diamond-like carbon nanocomposite coatings were deposited by using this system. The prepared coating exhibits high hardness (∼20 GPa), good adhesion (critical load is 50 N), very low friction coefficient (∼0.07); and excellent tribological performance with a wear rate of 1.4 x 10-16 m3·N-l·m-1. (authors)

  6. Contribution to mechanical and crystallographic analysis of molyledenum layers prepared by magnetron cathode sputtering

    International Nuclear Information System (INIS)

    Molybdenum coatings presenting different compression stresses are elaborated by magnetron cathode sputtering by varying the negative voltage of the substrate during deposition. Stress evolution is accompanied by crystal texture evolution and argon content incorporated in the layers. Crystallite orientation is explained by a phenomenon similar to canalisation observed in ion implantation. In a same deposit each component presents its own deformations different from neighbouring components

  7. Surface analysis by glow discharge spectrometry: cathode zone and sputtering yield

    International Nuclear Information System (INIS)

    Applications of the glow discharge optical spectroscopy for surface analysis are numerous. Moreover, this method enables to get qualitative and semi-quantitative results which are already significant. However, we should improve our knowledge of the physical parameters involved in the glow discharge lamp mechanisms and learn to handle such phenomena. The problems can be divided into two categories: sputtering of the target under argon ions accelerated in the cathode dark space, and luminous emission of torn away species which reach the negative glow region. Our aim was to take stock of the present theoretical knowledge which can be applied to the specific self-maintained glow discharge plasma. Moreover, we tried to link together (often roughly) the basic discharge parameters, i.e. current intensity I, voltage of the lamp Vg, pressure of the gas p. Specially a comparison between theoretical and experimental results was established concerning the pure target sputtering yields. The contribution of the argon ions striking the cathode is estimated taking into account their energetic distribution. The role of the fast argon neutrals produced by charge exchange with the ions is important; we evaluated their energetic distribution and their contribution to sputtering. The total theoretical sputtering yield is inferred: the comparison with experimental results is presented. The role of the gas temperature is emphasized

  8. Study of some structural properties of hydrogenated amorphous silicon thin films prepared by radiofrequency cathodic sputtering

    International Nuclear Information System (INIS)

    In this work, we have used the grazing X-rays reflectometry technique to characterise hydrogenated amorphous silicon thin films deposited by radio-frequency cathodic sputtering. Relfectometry measurements are taken immediately after films deposition as well as after having naturally oxidised their surfaces during a more or less prolonged stay in the ambient. For the films examined just after deposition, the role of hydrogen appears in the increase of their density. For those analysed after a short stay in the ambient, hydrogen plays a protective role against the oxidation of their surfaces. This role disappears when the stay in the ambient is so long. (author)

  9. Fabrication and characterization of lithium manganese nickel oxide sputtered thin film cathodes for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Baggetto, Loic [ORNL; Unocic, Raymond R [ORNL; Dudney, Nancy J [ORNL; Veith, Gabriel M [ORNL

    2012-01-01

    Li-rich and stoichiometric Li1Mn1.5Ni0.5O4 (LMNO) cathode films have been prepared by magnetron sputtering. Sputtering from a Li stoichiometric target yields Li-rich films composed of spinel, layered and monoclinic phases. Films obtained from a Li deficient target are mostly made of a spinel phase and little layered material. The resulting cathode thin films have good capacity retention and very high rate capability. The reaction mechanism has been investigated by XRD and HRTEM and evidences the reversible formation of a spinel phase, as is also found for the powder samples. The film geometry enables to understand the effect of coatings (ZnO or LiPON). Coating high voltage cathodes reduces the coulombic losses but at the price of rate performance. Nonetheless, these coated sputtered electrode thin films offer a higher rate capability than other LMNO thin films obtained by other physical vapor deposition techniques.

  10. Structure and optical properties of CdS:O films by cathode sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Masahiro; Asaba, Ryo; Suzuki, Akinori; Wakita, Kazuki [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 (Japan); Shim, Yong-Gu [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531 (Japan); Khalilova, Kh.; Mamedov, Nazim; Bayramov, Ayaz; Huseynov, Emil [Institute of Physics, Azerbaijan National Academy of Science, H. Javid ave. 33, Baku 1143 (Azerbaijan)

    2015-06-15

    We have studied the structure and optical properties of CdS:O films deposited on SLG (soda lime glass) substrates by cathode sputtering in the atmosphere of oxygen/argon gases. According to X-ray diffraction (XRD) and confocal Raman scattering data, the films annealed in vacuum at temperatures above 300 C exhibited crystalline structure of CdS. On the other hand, XRD, confocal Raman scattering, AFM (atomic force microscopy) and TEM (transmission electron microscopy) data indicated amorphous structure nano-crystallization in CdS:O films annealed in vacuum at 400 C. For the films, the emissions located at 3.35 eV were evident from photoluminescence measurements. The origin of this energy gap is discussed by taking into account redistribution of electronic density of states in the amorphous phase and quantum-size effect. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Development of the ion source with cathode sputtering of working material for the JINR cyclotrons

    International Nuclear Information System (INIS)

    Experience of design and operation of a multicharged ion source (MIS) with cathode sputtering of the working substance for the U-300 and U-400 cyclotrons is described. The MIS sputtering electrode is placed into the discharge chamber through the side wall and it is not subjected to back-beam bombardment. Using the U-300 cyclotron with natural metallic magnesium (an auxiliary gas is xenon) extracted ion beams of 24Mg4+ and 26Mg4+ at 4.2 μA and 0.6 μA, respectively, are obtained. Prliminary tests on magnesium ion acceleration are carried out on the U-400 accelerator. Magnesium three-charged ion beams (of a natural isotope mixture) have the 10.5 μA maximum intensity (for magnesium-24) and 1.6 μA (for magnesium-26) at the 170 cm radius. The emission window dimensions of the ion source are the following: 2x8 mm and 3x15 mm for U-400 and U-300, respectively. The metallic magnesium flow rate is 25 mg/h and 15 mg/h on U-300 and U-400, respectively

  12. Radioactive sputter cathodes for {sup 32}P plasma-based ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Fortin, M.A. [INRS-EMT (Universite du Quebec), 1650 boul. Lionel Boulet, Varennes, Quebec, J3X 1S2 (Canada)]. E-mail: fortin@bms.uu.se; Paynter, R.W. [INRS-EMT (Universite du Quebec), 1650 boul. Lionel Boulet, Varennes, Quebec, J3X 1S2 (Canada); Sarkissian, A. [Plasmionique Inc., 1650 boul. Lionel Boulet, Varennes, Quebec, J3X 1S2 (Canada); Stansfield, B.L. [INRS-EMT (Universite du Quebec), 1650 boul. Lionel Boulet, Varennes, Quebec, J3X 1S2 (Canada)

    2006-05-15

    The development of clinical treatments involving the use of beta-emitting millimetric and sub-millimetric devices has been a continuing trend in nuclear medicine. Implanted a few nanometers below the surface of endovascular implants, seeds or beads, beta-emitting radioisotopes can be used in a variety of biomedical applications. Recently, new technologies have emerged to enable the rapid and efficient activation of such devices. A pulsed, coaxial electron cyclotron resonance plasma reactor was designed and tested to demonstrate the feasibility of plasma-based radioactive ion implantation (PBRII). It has been shown that such plasma reactors allow for the implantation of radioisotopes ({sup 32}P) into biomedical devices with higher efficiencies than those obtained with conventional ion beams. Fragments containing radioactive atoms are produced in the implanter by means of a negatively biased solid sputter cathode that is inserted into an argon plasma. Dilute orthophosphoric acid solutions (H{sub 3} {sup 32}PO{sub 4}) are used for the fabrication of flat sputter targets, since they offer a high radioisotope content. However, the aggregation of the radioactive solute into highly hygroscopic ring-like deposits rather than flat, thin radioactive films is observed on certain substrates. This article describes the effect of this nonuniform distribution of the radioisotopes on the efficiency of PBRII, and presents a technique which enables a better distribution of {sup 32}P by coating the substrates with iron. The iron coating is shown to enable optimal radioisotope sputtering rates, which are essential in {sup 32}P-PBRII for the efficient activation of millimetric biomedical devices such as stents or coils.

  13. Radioactive sputter cathodes for 32P plasma-based ion implantation

    International Nuclear Information System (INIS)

    The development of clinical treatments involving the use of beta-emitting millimetric and sub-millimetric devices has been a continuing trend in nuclear medicine. Implanted a few nanometers below the surface of endovascular implants, seeds or beads, beta-emitting radioisotopes can be used in a variety of biomedical applications. Recently, new technologies have emerged to enable the rapid and efficient activation of such devices. A pulsed, coaxial electron cyclotron resonance plasma reactor was designed and tested to demonstrate the feasibility of plasma-based radioactive ion implantation (PBRII). It has been shown that such plasma reactors allow for the implantation of radioisotopes (32P) into biomedical devices with higher efficiencies than those obtained with conventional ion beams. Fragments containing radioactive atoms are produced in the implanter by means of a negatively biased solid sputter cathode that is inserted into an argon plasma. Dilute orthophosphoric acid solutions (H332PO4) are used for the fabrication of flat sputter targets, since they offer a high radioisotope content. However, the aggregation of the radioactive solute into highly hygroscopic ring-like deposits rather than flat, thin radioactive films is observed on certain substrates. This article describes the effect of this nonuniform distribution of the radioisotopes on the efficiency of PBRII, and presents a technique which enables a better distribution of 32P by coating the substrates with iron. The iron coating is shown to enable optimal radioisotope sputtering rates, which are essential in 32P-PBRII for the efficient activation of millimetric biomedical devices such as stents or coils

  14. Growth of microscopic cones on titanium cathodes of sputter-ion pumps driven by sorption of large argon quantities

    Energy Technology Data Exchange (ETDEWEB)

    Porcelli, Tommaso, E-mail: tommaso-porcelli@saes-group.com [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16, 20133 Milano, Italy and SAES Getters S.p.A., viale Italia, 77, 20020 Lainate, Milan (Italy); Siviero, Fabrizio; Bongiorno, Gero A. [SAES Getters S.p.A., viale Italia, 77, 20020 Lainate, Milan (Italy); Michelato, Paolo [INFN-LASA, via fratelli Cervi, 201, 20090 Segrate, Milan (Italy); Pagani, Carlo [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16, 20133 Milano, Italy and INFN-LASA, via fratelli Cervi, 201, 20090 Segrate, Milan (Italy)

    2015-09-15

    Microscopic cones have been observed on titanium cathodes of sputter-ion pumps (SIPs) after pump operation. The cones were studied by means of scanning electron microscopy and energy dispersive x-ray analysis. Size and morphology of these cones are clearly correlated with the nature and the relative amount of each gas species pumped by each SIP during its working life. In particular, their growth was found to be fed by sputtering mechanisms, mostly during Ar pumping, and to be driven by the electromagnetic field applied to the Penning cells of each SIP. Experimental findings suggest that the formation and extent of such conic structures on cathode surfaces might play a leading role in the onset of phenomena typically related to the functioning of SIPs, e.g., the so-called argon instability.

  15. Growth of microscopic cones on titanium cathodes of sputter-ion pumps driven by sorption of large argon quantities

    International Nuclear Information System (INIS)

    Microscopic cones have been observed on titanium cathodes of sputter-ion pumps (SIPs) after pump operation. The cones were studied by means of scanning electron microscopy and energy dispersive x-ray analysis. Size and morphology of these cones are clearly correlated with the nature and the relative amount of each gas species pumped by each SIP during its working life. In particular, their growth was found to be fed by sputtering mechanisms, mostly during Ar pumping, and to be driven by the electromagnetic field applied to the Penning cells of each SIP. Experimental findings suggest that the formation and extent of such conic structures on cathode surfaces might play a leading role in the onset of phenomena typically related to the functioning of SIPs, e.g., the so-called argon instability

  16. Effect of the thickness of sputtered gadolinia-doped ceria as a cathodic interlayer in solid oxide fuel cells

    International Nuclear Information System (INIS)

    Sputtered gadolinia-doped ceria (GDC) film was introduced as the cathodic interlayer between an yttria-stabilized zirconia (YSZ) pellet and a Pt cathode in solid oxide fuel cells (SOFCs). The fuel cells with none, 50, 100 and 150 nm thick GDC interlayers were fabricated to investigate the effect of the thickness of the GDC interlayer. The performances of the SOFCs with the 100 and 150 nm thick GDC interlayers operated at 450 °C showed the highest performance. Through electrochemical impedance analysis, it was visualized that the GDC interlayer significantly reduced the faradaic resistance of the SOFC. The degradation of the performance from the increased ohmic resistance by adding the GDC interlayer was negligible. From the topographical images scanned by atomic force microscope, it was observed that the 50 nm thick GDC interlayer did not perfectly cover the surface of the YSZ pellet, resulting in incomplete performance enhancement by the sputtered GDC. - Highlights: • Gadolinia-doped ceria was used as a cathodic interlayer in solid oxide fuel cells. • Sputter was used to deposit gadolinia-doped ceria. • Gadolinia-doped ceria interlayer improved the electrochemical performance. • 100 nm or thicker gadolinia-doped ceria showed a full functionality as interlayer

  17. Effect of the thickness of sputtered gadolinia-doped ceria as a cathodic interlayer in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Taehyun; Lee, Yoon Ho; Cho, Gu Young [School of Mechanical and Aerospace Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Ji, Sanghoon [Graduate School of Convergence Science and Technology, Seoul National University, 864-1 Iui-dong, Yeongtong-gu, Suwon 443-270 (Korea, Republic of); Park, Joonho [School of Mechanical and Aerospace Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Chang, Ikwhang [Graduate School of Convergence Science and Technology, Seoul National University, 864-1 Iui-dong, Yeongtong-gu, Suwon 443-270 (Korea, Republic of); Cha, Suk Won, E-mail: swcha@snu.ac.kr [School of Mechanical and Aerospace Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Graduate School of Convergence Science and Technology, Seoul National University, 864-1 Iui-dong, Yeongtong-gu, Suwon 443-270 (Korea, Republic of)

    2015-06-01

    Sputtered gadolinia-doped ceria (GDC) film was introduced as the cathodic interlayer between an yttria-stabilized zirconia (YSZ) pellet and a Pt cathode in solid oxide fuel cells (SOFCs). The fuel cells with none, 50, 100 and 150 nm thick GDC interlayers were fabricated to investigate the effect of the thickness of the GDC interlayer. The performances of the SOFCs with the 100 and 150 nm thick GDC interlayers operated at 450 °C showed the highest performance. Through electrochemical impedance analysis, it was visualized that the GDC interlayer significantly reduced the faradaic resistance of the SOFC. The degradation of the performance from the increased ohmic resistance by adding the GDC interlayer was negligible. From the topographical images scanned by atomic force microscope, it was observed that the 50 nm thick GDC interlayer did not perfectly cover the surface of the YSZ pellet, resulting in incomplete performance enhancement by the sputtered GDC. - Highlights: • Gadolinia-doped ceria was used as a cathodic interlayer in solid oxide fuel cells. • Sputter was used to deposit gadolinia-doped ceria. • Gadolinia-doped ceria interlayer improved the electrochemical performance. • 100 nm or thicker gadolinia-doped ceria showed a full functionality as interlayer.

  18. Epitaxy of Pb(Zr, Ti)O3 films on Ir/YSZ/Si under conditions of cathode sputtering: The effect of reactive gas composition

    Science.gov (United States)

    Beshenkov, V. G.; Burlakov, A. A.; Znamenskii, A. G.; Marchenko, V. A.

    2014-08-01

    The peculiarities of the growth of PZT films on heteroepitaxial Ir/YSZ/Si structures under conditions of cathode radio-frequency sputtering of a ceramic target in argon-oxygen mixtures have been studied. It is shown that sputtering in a gas mixture with a high partial pressure of oxygen results in crystallization of the PZT films in a metastable pyrochlore structure, while sputtering in argon or the use of argon in the initial phase of the sputtering yields PZT films with an equilibrium perovskite structure.

  19. Synthesis of Ti-Si-N nanocomposite coatings by a novel cathodic arc assisted middle-frequency magnetron sputtering

    International Nuclear Information System (INIS)

    Ti-Si-N nanocomposite coatings were synthesized by using a cathodic arc assisted middle-frequency magnetron sputtering system in an industrial scale. X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy were employed to investigate the chemical bonding and microstructure of the coatings. Atomic force microscope and scanning electron microscope were used to characterize the surface and cross-sectional morphologies of the samples. The coating was found to be nc-TiN/a-Si3N4 structure and exhibit a high hardness of 40 GPa when the Si content was 6.3 at.%.

  20. Structure and mechanical properties of Ti-Al-N coatings deposited by combined cathodic arc middle frequency magnetron sputtering

    International Nuclear Information System (INIS)

    Research highlights: → Ti-Al-N coatings were deposited on Si and WC substrates by combined cathodic arc middle-frequency magnetron (MF) sputtering under a Ti arc power of 10 kW with different Al MF targets currents. The hardness of the Ti-Al-N coatings was in the range of 23-32 GPa, whereas the Young modulus values were in the range of 420-540 GPa. - Abstract: Ti-Al-N coatings were deposited on Si (1 1 1) and WC substrates by combined cathodic arc middle-frequency magnetron (MF) sputtering under a Ti arc power of 10 kW and with different Al MF targets currents. X-ray diffraction patterns (XRD) showed that the Ti-Al-N coatings were polycrystallize with a preferred (1 1 1) orientation at 2θ = 43.7o. The (1 1 1) diffraction showed a decrease in peak intensity but a increase in FWHM values with the increasing of Al contents. Nano-meter sized TiN crystal grains distinguished by the lattice fringe contrast were verified by plan-view transmission electron (TEM) and selected area electron diffraction (SAED) images. With the increasing of MF sputter currents from 5 to 20 A, the Al contents in the Ti-Al-N coatings monotonically increased from 4.8 to 10.8 at.%, whereas the N and O contents were nearly constant. The hardness of the Ti-Al-N coatings was in the range of 23-32 GPa, and the Young modulus values were in the range of 420-540 GPa.

  1. Estimation of the Efficiency of Material Injection into the Reflex Discharge by Sputtering the Cathode Material

    CERN Document Server

    Kovtun, Yu V; Skibenko, A I; Yuferov, V B

    2012-01-01

    The processes of injection of a sputtered-and-ionized working material into the pulsed reflex discharge plasma have been considered at the initial stage of dense gas-metal plasma formation. A calculation model has been proposed to estimate the parameters of the sputtering mechanism for the required working material to be injected into the discharge. The data obtained are in good accordance with experimental results.

  2. Radio frequency magnetron sputter-deposited indium tin oxide for use as a cathode in transparent organic light-emitting diode

    International Nuclear Information System (INIS)

    Indium tin oxide (ITO) films were prepared by radio frequency magnetron sputtering at room temperature, for use as a cathode in a transparent organic light-emitting diode (TOLED). To minimize damage to the TOLED by the ITO sputtering process, the target-to-substrate distance was increased to 20 cm. An ITO film deposited at the optimum oxygen partial pressure exhibited an electrical resistivity as low as 4.06 x 10-4 Ω cm and a high optical transmittance of 91% in the visible range. The film was used as a transparent cathode for a TOLED with structure of an ITO coated glass substrate / Naphthylphenyldiamide (60 nm) / Tris-(8-hydroxyquinoline) aluminum (60 nm) / LiF (1 nm) / Al (2 nm) / Ag (8 nm) / ITO cathode (100 nm). A maximum luminance of 37,000 cd/m2 was obtained. The device performance was comparable to a conventional OLED

  3. Structure and Properties of Ti-Si-N Coatings Synthesized by Combining Cathode Arc and Middle-frequency Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    YANG Zhongtian; ZHU Liya; YANG Bing; GUO Liping; FU Dejun

    2009-01-01

    Ti-Si-N composite coatings were synthesized on a novel combining cathode and middle-frequency magnetron sputtering system,designed on an industrial scale.Ti was produced from the arc target and Si from magnetron target during deposition.The influences of negative bias voltage and Si content on the hardness and microstructure of the coatings were investigated.The composite coatings prepared under optimized conditions were characterized to be nc-TiN/a-Si_3N_4 structure with grain sizes of TiN ranging from 8-15 nm and exhibited a high hardness of 40 GPa.The enhancement of the hardness is suggested to be caused by the nanograin-amorphous structure effects.

  4. Microstructural and electrochemical properties of rf-sputtered LiMn2O4 thin film cathodes

    Science.gov (United States)

    Jayanth Babu, K.; Jeevan Kumar, P.; Hussain, O. M.

    2012-12-01

    Lithium transition metal oxides have received considerable attention in recent years as high voltage positive electrode materials in the fabrication of all solid state microbatteries. Among various lithium-based cathode materials, LiMn2O4 is one of the most promising cathode materials as it offers high energy density, high cell voltage, low cost, and low toxicity over the other electrode materials. Thin films of LiMn2O4 were prepared by radio frequency magnetron sputtering on gold-coated silicon substrates under various substrate temperatures ranging from 373 to 673 K in a partial pressure of 3 × 10-3 mbar with rf power 100 Watts. In the present investigation, the influence of substrate temperature on the growth and microstructural properties was studied. The films deposited at a substrate temperature less than 473 K was found to be X-ray amorphous. The initial crystallization has been observed at a substrate temperature of 523 K. The X-ray diffraction patterns of the films deposited in the substrate temperature range 523-673 K exhibited predominant (111) orientation representing cubic spinel structure with Fd3m symmetry. The grain size was found to be increased with the increase of substrate temperature as evidenced from SEM studies. However, additional impurity phases like Mn3O4 were observed for the films deposited at higher substrate temperatures (>673 K) because of re-evaporation of Li+ ions in the films. The electrochemical (EC) studies were carried for the films deposited at T s = 673 K in aqueous media in the potential window of 0.0-1.2 V exhibited better electrochemical performance suggesting that the films are well suited as binder free thin film cathode material for commercially viable Li-ion secondary batteries.

  5. Electrochemical performance and thermal stability of LiCoO{sub 2} cathodes surface-modified with a sputtered thin film of lithium phosphorus oxynitride

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwan-Ho; Jeon, Jun-Hong; Lee, Sung-Man [Department of Advanced Materials Science and Engineering, Kangwon National University, Chunchon, Kangwon-Do 200-701 (Korea); Park, Hong-Kyu [Battery Research Institute, LG Chemical Limited, Taejon 305-380 (Korea)

    2010-12-15

    A lithium phosphorus oxynitride (LiPON) glass-electrolyte thin film is coated on a lithium cobalt oxide (LiCoO{sub 2}) composite cathode by means of a radio frequency (RF) magnetron sputtering method. The effect of the LiPON coating layer on the electrochemical performance and thermal stability of the LiCoO{sub 2} cathode is investigated. The thermal stability of the delithiated LiCoO{sub 2} cathode in the presence of liquid electrolyte is examined by differential scanning calorimetry (DSC). It is found that the LiPON coating, improves the rate capability and the thermal stability of the charged LiCoO{sub 2} cathode. The LiPON film appears to suppress impedance growth during cycling and inhibits side-reactions between delithiated LiCoO{sub 2} and the electrolyte. (author)

  6. Monte Carlo simulation of a sputtering hollow-cathode discharge for laser applications

    International Nuclear Information System (INIS)

    We report on a kinetic model that computes the electron behaviour in a hollow cathode discharge. It is a part of the PLASIMO toolkit and is based on a Monte-Carlo technique. The model is tested by varying the input parameters and by comparing the output with the output obtained by the freeware Boltzmann equation solver BOLSIG+. The results show that the Monte-Carlo model gives reliable information about the behavior of the electrons in the discharge. The Monte-Carlo module is applied to the case of a hollow cathode discharge for laser applications. Analysis of the output data and its adequateness is done. Future developments of the model are discussed.

  7. Tantalum (oxy)nitrides prepared using reactive sputtering for new nonplatinum cathodes of polymer electrolyte fuel cell

    International Nuclear Information System (INIS)

    Tantalum (oxy)nitrides (TaOxNy) have been investigated as new cathodes for polymer electrolyte fuel cells without platinum. TaOxNy films were prepared using a radio frequency magnetron sputtering under Ar + O2 + N2 atmosphere at substrate temperatures from 50 to 800 deg. C. The effect of the substrate temperature on the catalytic activity for the oxygen reduction reaction (ORR) and properties of the TaOxNy films were examined. The catalytic activity of the TaOxNy for the ORR increased with the increasing substrate temperature. The ORR current density at 0.4 V vs. RHE on TaOxNy prepared at 800 deg. C was approximately 20 times larger than that on TaOxNy prepared at 50 deg. C. The onset potential of the TaOxNy for the ORR was obtained at the ORR current density of -0.2 μA cm-2. The onset potential of the TaOxNy prepared at 800 deg. C was ca. 0.75 V vs. RHE. The X-ray diffraction patterns revealed that Ta3N5 structure grew as the substrate temperature increased. While, the ionization potentials of all specimens were lower than that of Ta3N5, and decreased with the increasing substrate temperature. The TaOxNy which had Ta3N5 structure and lower ionization potential might have a definite catalytic activity for the ORR

  8. Friction properties of amorphous carbon ultrathin films deposited by filtered cathodic vacuum arc and radio-frequency sputtering

    International Nuclear Information System (INIS)

    The friction properties of ultrathin films of amorphous carbon (a-C) deposited on Si(100) substrates by filtered cathodic vacuum arc and radio-frequency sputtering were investigated by surface force microscopy. Deposition parameters yielding a-C films with high sp3 content were used to deposit films of thickness between 5 and 35 nm. The coefficient of friction of both types of a-C films was measured with a 1-μm-radius conical diamond tip and normal loads in the range of 20–640 μN. The results show a strong dependence of the friction properties on the surface roughness, thickness, and structure of the a-C films, which are influenced by the intricacies of the deposition method. The dependence of the coefficient of friction on normal load and the dominance of adhesion and plowing friction mechanisms are interpreted in terms of the through-thickness variation of carbon atom hybridization of the a-C films. - Highlights: • Comparison of nanoscale friction properties of ultrathin amorphous carbon films. • Friction dependence on film roughness, thickness, and structure (hybridization). • Effect of through-thickness changes in carbon atom hybridization on film friction. • Explanation of film friction trends in terms of competing friction mechanisms

  9. Friction properties of amorphous carbon ultrathin films deposited by filtered cathodic vacuum arc and radio-frequency sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Matlak, J.; Komvopoulos, K., E-mail: kyriakos@me.berkeley.edu

    2015-03-31

    The friction properties of ultrathin films of amorphous carbon (a-C) deposited on Si(100) substrates by filtered cathodic vacuum arc and radio-frequency sputtering were investigated by surface force microscopy. Deposition parameters yielding a-C films with high sp{sup 3} content were used to deposit films of thickness between 5 and 35 nm. The coefficient of friction of both types of a-C films was measured with a 1-μm-radius conical diamond tip and normal loads in the range of 20–640 μN. The results show a strong dependence of the friction properties on the surface roughness, thickness, and structure of the a-C films, which are influenced by the intricacies of the deposition method. The dependence of the coefficient of friction on normal load and the dominance of adhesion and plowing friction mechanisms are interpreted in terms of the through-thickness variation of carbon atom hybridization of the a-C films. - Highlights: • Comparison of nanoscale friction properties of ultrathin amorphous carbon films. • Friction dependence on film roughness, thickness, and structure (hybridization). • Effect of through-thickness changes in carbon atom hybridization on film friction. • Explanation of film friction trends in terms of competing friction mechanisms.

  10. The electronic structure of tungsten oxide thin films prepared by pulsed cathodic arc deposition and plasma-assisted pulsed magnetron sputtering

    International Nuclear Information System (INIS)

    Pulsed cathodic arc and pulsed magnetron sputtered WO3 thin films were investigated using electron microscopy. It was found that the cathodic arc deposited material consisted of the α-WO3 phase with a high degree of crystallinity. In contrast, the magnetron sputtered material was highly disordered making it difficult to determine its phase. Electron energy-loss spectroscopy was used to study the oxygen K edge of the films and it was found that the near-edge fine structures of films produced by the two deposition methods differed. The oxygen K-edge near-edge structures for various phases of WO3 were calculated using two different self-consistent methods. Each phase was found to exhibit a unique oxygen K edge, which would allow different phases of WO3 to be identified using x-ray absorption spectroscopy or electron energy-loss spectroscopy. Both calculation methods predicted an oxygen K edge for the γ-WO3 phase which compared well to previous x-ray absorption spectra. In addition, a close match was found between the oxygen K edges obtained experimentally from the cathodic arc deposited material and that calculated for the α-WO3 phase

  11. Development of thin film cathodes for lithium-ion batteries in the material system Li–Mn–O by r.f. magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J., E-mail: julian.fischer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Adelhelm, C.; Bergfeldt, T. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chang, K. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 46 52074 Aachen (Germany); Ziebert, C.; Leiste, H.; Stüber, M.; Ulrich, S. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Music, D.; Hallstedt, B. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 46 52074 Aachen (Germany); Seifert, H.J. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2013-01-01

    Today most commercially available lithium ion batteries are still based on the toxic and expensive LiCoO{sub 2} as a standard cathode material. However, lithium manganese based cathode materials are cheaper and environmentally friendlier. In this work cubic-LiMn{sub 2}O{sub 4} spinel, monoclinic-Li{sub 2}MnO{sub 3} and orthorhombic-LiMnO{sub 2} thin films have been synthesized by non-reactive r.f. magnetron sputtering from two ceramic targets (LiMn{sub 2}O{sub 4}, LiMnO{sub 2}) in a pure argon discharge. The deposition parameters, namely target power and working gas pressure, were optimized in a combination with a post deposition heat treatment with respect to microstructure and electrochemical behavior. The chemical composition was determined using inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The films' crystal structure, phase evolution and morphology were investigated by X-ray diffraction, micro Raman spectroscopy and scanning electron microscopy. Due to the fact that these thin films consist of the pure active material without any impurities, such as binders or conductive additives like carbon black, they are particularly well suited for measurements of the intrinsic physical properties, which is essential for fundamental understanding. The electrochemical behavior of the cubic and the orthorhombic films was investigated by galvanostatic cycling in half cells against metallic lithium. The cubic spinel films exhibit a maximum specific capacity of ∼ 82 mAh/g, while a specific capacity of nearly 150 mAh/g can be reached for the orthorhombic counterparts. These films are promising candidates for future all solid state battery applications. - Highlights: ► Synthesis of 3 Li–Mn–O structures by one up-scalable thin film deposition method ► Formation of o-LiMnO{sub 2} by r.f. magnetron sputtering in combination with post-annealing ► Discharge capacity with o-LiMnO{sub 2} cathodes twice as high as for c

  12. Development of thin film cathodes for lithium-ion batteries in the material system Li–Mn–O by r.f. magnetron sputtering

    International Nuclear Information System (INIS)

    Today most commercially available lithium ion batteries are still based on the toxic and expensive LiCoO2 as a standard cathode material. However, lithium manganese based cathode materials are cheaper and environmentally friendlier. In this work cubic-LiMn2O4 spinel, monoclinic-Li2MnO3 and orthorhombic-LiMnO2 thin films have been synthesized by non-reactive r.f. magnetron sputtering from two ceramic targets (LiMn2O4, LiMnO2) in a pure argon discharge. The deposition parameters, namely target power and working gas pressure, were optimized in a combination with a post deposition heat treatment with respect to microstructure and electrochemical behavior. The chemical composition was determined using inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The films' crystal structure, phase evolution and morphology were investigated by X-ray diffraction, micro Raman spectroscopy and scanning electron microscopy. Due to the fact that these thin films consist of the pure active material without any impurities, such as binders or conductive additives like carbon black, they are particularly well suited for measurements of the intrinsic physical properties, which is essential for fundamental understanding. The electrochemical behavior of the cubic and the orthorhombic films was investigated by galvanostatic cycling in half cells against metallic lithium. The cubic spinel films exhibit a maximum specific capacity of ∼ 82 mAh/g, while a specific capacity of nearly 150 mAh/g can be reached for the orthorhombic counterparts. These films are promising candidates for future all solid state battery applications. - Highlights: ► Synthesis of 3 Li–Mn–O structures by one up-scalable thin film deposition method ► Formation of o-LiMnO2 by r.f. magnetron sputtering in combination with post-annealing ► Discharge capacity with o-LiMnO2 cathodes twice as high as for c-LiMn2O4 ► Thin film deposition of m-Li2MnO3 and o-LiMnO2

  13. Natural and gamma radiation-induced conduction of silica and metaphosphate glass layers deposed by radiofrequency cathode sputtering

    International Nuclear Information System (INIS)

    We present a study of natural and 60Co induced conductions in radiofrequency sputtering deposed layers. Capacimetry and electronic microscopy observations permit a knowledge of the physical characteristics, mainly: homogeneity and thickness of these layers. A study of the natural current permit to characterise electrically the deposited films, the electrode and bulk insulator effects. In induced conduction, the behaviour of currents as a function of dose rate is interpreted in terms of ROSE'S and FOWLER'S photoconductivity theories. Induced currents versus applied fields are observed and compared with these obtained in the case of dielectric liquids and glasses. (author)

  14. Structural transformation of sputtered o-LiMnO2 thin-film cathodes induced by electrochemical cycling

    International Nuclear Information System (INIS)

    Orthorhombic LiMnO2 (o-LiMnO2) thin films were produced by non-reactive r.f. magnetron sputtering in combination with thermal post-annealing. Oxide phase formation was investigated by X-ray diffraction and Raman spectroscopy. In order to assign the X-ray signals and estimate the grain size, a simulation of the diffraction pattern was performed and compared with experimental data. The density of the films was determined to be 3.39 g/cm3 using X-ray reflectivity. Electrochemical characterization was carried out by galvanostatic cycling and cyclic voltammetry of Li/o-LiMnO2 half cells. There are distinct redox reactions at approx. 3 V and 4 V, whereas the latter splits into multiple peaks. Using ab initio calculations and thermodynamic models, Gibbs energies of o-LiMnO2 and c-LiMn2O4 were determined. The relation between these energies explains the irreversible phase transformation that has been observed during the cycling of the Li/o-LiMnO2 half cell. - Highlights: • Quantitative, thermodynamic modeling of the o-LiMnO2/c-LiMn2O4 phase transformation • First CV-investigations on magnetron sputtered nanocrystalline o-LiMnO2 thin films • Synthesis of o-LiMnO2 planar model systems for protective coating and SEI development

  15. Preparation and characterization of magnetic nanostructures based on FeCo / IrMn deposited by cathode sputtering

    International Nuclear Information System (INIS)

    Spintronic devices based in the transport of spin polarized current, spin's torque and other related phenomena represent big promises in the scenery of the technological miniaturization of current electronic devices. Magnetic materials of great technological relevance for different areas deal with, despite some exceptions, films and multilayered structures with high complexity. Advances on these fields require the control of those structures in atomic scale, in order to be able to tailor their physical properties. The purpose of this work is the preparation of multilayered structures by sputtering, as well the study of magnetic phenomena involved in this structures. The aim is to produce a spin valve. This is a multilayer structure composed of two ferromagnetic layers, separated by a non magnetic spacer. The magnetisation of one of the ferromagnetic layers is free to rotate under the effect of small external fields, whilst the magnetisation of the other ferromagnetic layer remains fixed by means exchange coupling to a antiferromagnetic layer. The structure is tailored to allow the small applied magnetic fields to switch the magnetisation of the ferromagnetic layers from antiparallel state to a parallel state resulting in the variation of the electrical resistivity of the structure (GMR effect). Optimization of deposition conditions was required to obtain structures with exchange bias coupling, and antiferromagnetic coupling through a non magnetic spacer. The correlation between the deposition conditions and the magnetic properties of the films was studied. The work presented in this dissertation has contributed to the characterisation of both magnetic thin films, which can be used on the production of magnetic sensors, and the new sputtering system assembled in the Applied Physics Laboratory of CDTN. (author)

  16. Structural transformation of sputtered o-LiMnO{sub 2} thin-film cathodes induced by electrochemical cycling

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J., E-mail: Julian.Fischer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chang, K. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 52074 Aachen (Germany); Ye, J.; Ulrich, S.; Ziebert, C. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Music, D.; Hallstedt, B. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 52074 Aachen (Germany); Seifert, H.J. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2013-12-31

    Orthorhombic LiMnO{sub 2} (o-LiMnO{sub 2}) thin films were produced by non-reactive r.f. magnetron sputtering in combination with thermal post-annealing. Oxide phase formation was investigated by X-ray diffraction and Raman spectroscopy. In order to assign the X-ray signals and estimate the grain size, a simulation of the diffraction pattern was performed and compared with experimental data. The density of the films was determined to be 3.39 g/cm{sup 3} using X-ray reflectivity. Electrochemical characterization was carried out by galvanostatic cycling and cyclic voltammetry of Li/o-LiMnO{sub 2} half cells. There are distinct redox reactions at approx. 3 V and 4 V, whereas the latter splits into multiple peaks. Using ab initio calculations and thermodynamic models, Gibbs energies of o-LiMnO{sub 2} and c-LiMn{sub 2}O{sub 4} were determined. The relation between these energies explains the irreversible phase transformation that has been observed during the cycling of the Li/o-LiMnO{sub 2} half cell. - Highlights: • Quantitative, thermodynamic modeling of the o-LiMnO{sub 2}/c-LiMn{sub 2}O{sub 4} phase transformation • First CV-investigations on magnetron sputtered nanocrystalline o-LiMnO{sub 2} thin films • Synthesis of o-LiMnO{sub 2} planar model systems for protective coating and SEI development.

  17. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hans, M., E-mail: hans@mch.rwth-aachen.de; Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Primetzhofer, D. [Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, S-75120 Uppsala (Sweden); Kurapov, D.; Arndt, M.; Rudigier, H. [Oerlikon Balzers Coating AG, Iramali 18, LI-9496 Balzers, Principality of Liechtenstein (Liechtenstein)

    2014-09-07

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

  18. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    International Nuclear Information System (INIS)

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds

  19. Growth of cerium oxide thin layers for the manufacture of dosemeters and/or irradiation detectors by magnetron RF cathodic sputtering

    International Nuclear Information System (INIS)

    Oxide thin films deposited on silicon substrate are interesting for the manufacture of dosemeters and detectors of gas, humidity, temperature and irradiation. The irradiation dose measurement is required for assessing the risks and advantages of the use of ionizing radiations in fields such as biology, medicine and more generally in all the civil and military nuclear applications. According to literature, cerium oxide seems to be potentially interesting for the manufacture of dosemeters and/or irradiation detectors. The influence of the deposition parameters, such as the inter-electrodes distance, the temperature, the RF power, the work pressure, on the crystalline quality of the CeO2 layers deposited on a silicon (111) substrate by magnetron RF cathodic sputtering has been studied. All these thin films have been characterized by X-ray diffraction and by Raman spectroscopy. At the present time, studies are carried out on 'flash' annealing in order to improve the crystalline state of the thin layers. The aim is to study the influence of gamma and neutrons irradiations on the electric properties of capacities made of CeO2 thin films. (O.M.)

  20. The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

    Science.gov (United States)

    Poolcharuansin, Phitsanu; Estrin, Francis Lockwood; Bradley, James W.

    2015-04-01

    The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes, the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies Ep velocities between 6.5 and 10 km s-1 and mode numbers m = 3 or above. At Ep > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target.

  1. The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Poolcharuansin, Phitsanu [Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ (United Kingdom); The Technological Plasma Research Unit, Department of Physics, Mahasarakham University, Maha Sarakham 44150 (Thailand); Estrin, Francis Lockwood; Bradley, James W., E-mail: j.w.bradley@liverpool.ac.uk [Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ (United Kingdom)

    2015-04-28

    The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes, the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies E{sub p} < 0.8 J, spokes appear to be chaotic in nature (with random arrival times), however as E{sub p} increases, coherent spokes are observed with velocities between 6.5 and 10 km s{sup −1} and mode numbers m = 3 or above. At E{sub p} > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target.

  2. The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

    International Nuclear Information System (INIS)

    The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes, the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies Ep < 0.8 J, spokes appear to be chaotic in nature (with random arrival times), however as Ep increases, coherent spokes are observed with velocities between 6.5 and 10 km s−1 and mode numbers m = 3 or above. At Ep > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target

  3. Effect of the energy transfer collision between noble gas and sputtered metal atom on the voltage-current curve of a hollow-cathode discharge

    International Nuclear Information System (INIS)

    The voltage-current curves and the optogalvanic signals of hollow-cathode discharge tubes were measured. Attention was focused on the existence of negative dynamic resistance properties for argon and neon discharges. Three hollow-cathodes, each was made of gadolinium, uranium, and copper, were used with both the noble gases. The negative dynamic resistance regions were observed only in Ar/U, Ar/Gd, and Ne/Cu discharges. These results suggest that resonant Penning ionization is one of the main reactions producing the negative dynamic resistance characteristics in hollow cathode discharges

  4. In-situ sputtering apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, Mark R.; Poole, Henry J.; Custer, III, Arthur W.; Hershcovitch, Ady

    2015-06-09

    A sputtering apparatus that includes at least a target presented as an inner surface of a confinement structure, the inner surface of the confinement structure is preferably an internal wall of a circular tube. A cathode is disposed adjacent the internal wall of the circular tube. The cathode preferably provides a hollow core, within which a magnetron is disposed. Preferably, an actuator is attached to the magnetron, wherein a position of the magnetron within the hollow core is altered upon activation of the actuator. Additionally, a carriage supporting the cathode and communicating with the target is preferably provided, and a cable bundle interacting with the cathode and linked to a cable bundle take up mechanism provided power and coolant to the cathode, magnetron, actuator and an anode of the sputtering apparatus.

  5. The deposition of 3C-SiC thin films onto the (111) and (110) faces of Si using pulsed sputtering of a hollow cathode

    Czech Academy of Sciences Publication Activity Database

    Huguenin-Love, J.L.; Lauer, N.T.; Soukup, R. J.; Ianno, N.J.; Kment, Štěpán; Hubička, Zdeněk

    645-648, 1-2 (2010), s. 131-134. ISSN 0255-5476. [International Conference on Silicon Carbide and Related Materials Location /13./. Nurnberg, 11.10.2009-16.10.2009] Institutional research plan: CEZ:AV0Z10100522 Keywords : sputtering * pulse * germanium * 3C Subject RIV: BM - Solid Matter Physics ; Magnetism

  6. Deposition of hematite Fe.sub.2./sub.O.sub.3./sub. thin film by DC pulsed magnetron and DC pulsed hollow cathode sputtering system

    Czech Academy of Sciences Publication Activity Database

    Hubička, Zdeněk; Kment, Štěpán; Olejníček, Jiří; Čada, Martin; Kubart, T.; Brunclíková, Michaela; Kšírová, Petra; Adámek, Petr; Remeš, Zdeněk

    2013-01-01

    Roč. 549, Dec (2013), s. 184-191. ISSN 0040-6090 R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Grant ostatní: AVČR(CZ) M100101215 Institutional support: RVO:68378271 Keywords : HIPIMS * thin films * hollow cathode Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.867, year: 2013

  7. Improved high-voltage and high-temperature electrochemical performances of LiCoO2 cathode by electrode sputter-coating with Li3PO4

    Science.gov (United States)

    Zhou, Aijun; Xu, Jin; Dai, Xinyi; Yang, Bin; Lu, Yanting; Wang, Liping; Fan, Cong; Li, Jingze

    2016-08-01

    Surface coating has long been an important strategy to improve the electrochemical performances of electrode materials for Li-ion batteries. In this work, an amorphous Li3PO4 (LPO) layer, which is a poor electronic conductor but good ionic conductor, is coated directly on LiCoO2 composite electrodes by magnetron sputtering. The battery performances of the electrodes are studied at both room temperature (RT) and 50 °C. The LPO sputter-coating allows significant improvement of the electrode's cycling stability at both temperatures. With an optimum coating thickness of ∼60 nm, the electrode's capacity after 100 cycles at 1 C can reach 146 mAh g-1 (79.3% retention) and 140 mAh g-1 (78.2% retention) at RT and 50 °C, which are improved by 30% and 200%, respectively, compared to those of the bare LCO electrode. More impressively, the rate capability is also greatly enhanced by LPO-coating, and the observed high-temperature rate capability is even superior to the room-temperature one. The remarkable improvement of the LPO-coated electrodes is mainly attributed to the high chemical stability and temperature-enhanced electrochemical activity of the LPO coating layer, which synergistically serves as a physiochemical protection layer and an efficient pathway for Li+ transport.

  8. Chemical sputtering

    International Nuclear Information System (INIS)

    In this thesis, the author focuses on chemical sputtering by keV ions, treating two specific examples: the chemical effects occurring when bombarding simple condensed gases and the mechanisms of the ion-assisted etching process. First, however, the mechanism of sputtering of condensed gases in general is discussed. These mechanisms have been investigated using condensed noble gases as target material. The thesis is a compilation of articles published elsewhere. Contents: sputtering of condensed noble gases by keV heavy ions; surface distribution as an observable factor in the energy distribution of sputtered particles; reactive sputtering of simple condensed gases by keV heavy ion bombardment; mass spectra of nozzle-produced small molecular clusters of H2O, NH3, CO and CH4; mass and energy distribution of particles sputter-etched from Si in a XeF2 environment; argon-ion assisted etching of silicon by molecular chlorine; energy distribution of sputtered poly-atomic molecules. (Auth.)

  9. Sputter target

    Science.gov (United States)

    Gates, Willard G.; Hale, Gerald J.

    1980-01-01

    The disclosure relates to an improved sputter target for use in the deposition of hard coatings. An exemplary target is given wherein titanium diboride is brazed to a tantalum backing plate using a gold-palladium-nickel braze alloy.

  10. Barium-Dispenser Thermionic Cathode

    Science.gov (United States)

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

    1989-01-01

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

  11. Micro-hollow cathode dischargers

    International Nuclear Information System (INIS)

    In order to develop a hollow cathode discharge (HCD) with its increased current over planar electrode glow discharges, the cathode fall, which is on the order of the mean free path for ionization, must be comparable in length to the hole diameter. This indicates that the discharge parameters vary with pressure, p, times hole diameter, D. The pD product for stable operation of a hollow cathosde discharge was quoted to be on the order of one to ten Torr cm for noble gases, less for molecular gases. White (1959) observed the hollow cathode effect in a neon discharge at a pressure of 100 Torr when the hole dimensions were less than 1 mm. The cathode hole in his experiments changed from a cylindrical into a spherical cavity due to sputtering. The anode consisted in White's experiment of a pin on the axis of the discharge geometry. We have studied micro-hollow (submillimeter) cathode discharges between two electrodes with aligned cylindrical holes by determining the current-voltage characteristics and the visual appearance of the discharge in argon over a wide range of pressure and voltage. The cross-section of the discharge geometry. The cathode is made of molybdenum or barium oxide inserted into a tungsten matrix (dispenser-cathode), the anode of molybdenum, and the dielectric spacer is mica. The discharge was operated under dc conditions, with half-wave rectified ac voltage applied, and pulsed with a 400 μs rectangular voltage pulse. The lower limit in pressure was determined by the maximum voltage which could be applied to the discharge geometry without breakdown along insulators. The upper limit, in this study, is determined by the transition from cathode electrode emission due to ion-impact to thermal emission of electrons, which causes a dramatic increase in current and a drop in forward voltage to values on the order of 20 V

  12. Development and testing of large-area insulating and superconducting multilayer systems for H.F. applications. Sub-project: High-vacuum hollow cathode sputtering device for large-area high-Tc/insulator systems and their application in microelectronic devices and microwave systems

    International Nuclear Information System (INIS)

    The aim of the research is the deposition of large-area YBa2Cu3O7-x/insulator multilayer systems for microelectronic devices and microwave applications. The sputtering device with the linear hollow cathode and the substrate movement for the deposition of 3''-wafers are described. We've found out that our method is suitable for the deposition of such large area YBa2Cu3O7-x films. Due to in- or out-diffusion of oxygen within the target by using a great ratio of length to width of the linear hollow cathode, the discharge may take place not over the whole slot length. This results in a decreased homogenity of the large area deposition. For a carefully directed annealing procedure in order to decrease the oxygen content of the films from 7 to 6.4, we've done in-situ measurements of the resistivity. Persistent photoconductivity at films with an oxygen content nearby 6.4 was clearly observable. The excess conductivity yields an increase of the critical temperature of about 4K. The relaxation times, which are at room temperature in the order of hours can be reduced through heating. The contactless characterization of the films could be extended to the determination of the critical current density after calculating the magnetic field above the film. (orig.)

  13. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Causa, Federica [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Universita degli studi di Messina, 98122 Messina (Italy); Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dellasega, David [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dipartimento di Energia, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (Italy)

    2012-12-15

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  14. Understanding deposition rate loss in high power impulse magnetron sputtering: I. Ionization-driven electric fields

    OpenAIRE

    Brenning, N; C. Huo; Lundin, Daniel; Raadu, M.A.; Vitelaru, C; Stancu, G. D.; Minea, T.; Helmersson, Ulf

    2012-01-01

    The lower deposition rate for high power impulse magnetron sputtering (HiPIMS) compared with direct current magnetron sputtering for the same average power is often reported as a drawback. The often invoked reason is back-attraction of ionized sputtered material to the target due to a substantial negative potential profile, sometimes called an extended presheath, from the location of ionization toward the cathode. Recent studies in HiPIMS devices, using floating-emitting and swept-Langmuir pr...

  15. Calculated and measured emittance of sputter-type negative-ion source

    International Nuclear Information System (INIS)

    A method for calculating the beam current and emittance of a negative ion beam from a sputter-type source is described. Calculations are compared to measured emittance. The dependence of the emittance on ion source parameters such as cathode shape, exit aperture diameter, and cathode voltage is discussed

  16. Reactive sputtering of titanium in Ar/CH4 gas mixture: Target poisoning and film characteristics

    International Nuclear Information System (INIS)

    Reactive sputtering of titanium target in the presence of Ar/CH4 gas mixture has been investigated. With the addition of methane gas to above 1.5% of the process gas a transition from the metallic sputtering mode to the poison mode was observed as indicated by the change in cathode current. As the methane gas flow concentration increased up to 10%, the target was gradually poisoned. The hysteresis in the cathode current could be plotted by first increasing and then subsequently decreasing the methane concentration. X-ray diffraction and X-ray photoelectron spectroscopy analyses of the deposited films confirmed the formation of carbide phases and the transition of the process from the metallic to compound sputtering mode as the methane concentration in the sputtering gas is increased. The paper discusses a sputtering model that gives a rational explanation of the target poisoning phenomenon and shows an agreement between the experimental observations and calculated results.

  17. Solar system sputtering

    Science.gov (United States)

    Tombrello, T. A.

    1982-01-01

    The sites and materials involved in solar system sputtering of planetary surfaces are reviewed, together with existing models for the processes of sputtering. Attention is given to the interaction of the solar wind with planetary atmospheres in terms of the role played by the solar wind in affecting the He-4 budget in the Venus atmosphere, and the erosion and differentiation of the Mars atmosphere by solar wind sputtering. The study is extended to the production of isotopic fractionation and anomalies in interplanetary grains by irradiation, and to erosion effects on planetary satellites with frozen volatile surfaces, such as with Io, Europa, and Ganymede. Further measurements are recommended of the molecular form of the ejected material, the yields and energy spectra of the sputtered products, the iosotopic fractionation sputtering causes, and the possibility of electronic sputtering enhancement with materials such as silicates.

  18. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  19. Three-electrode current-voltage measurements on erbia-stabilized bismuth oxide with sputtered noble metal electrodes

    NARCIS (Netherlands)

    Vinke, I.C.; Boukamp, B.A.; Vries, de K.J.; Burggraaf, A.J.

    1992-01-01

    The anodic and cathodic polarization behaviour of sputtered porous gold electrodes on (Bi2O3)0.75(Er2O3)0.25 (abbreviated BE25) was studied as function of temperature and oxygen partial pressure using a three-electrode cell. The anodic polarization is smaller than the cathodic polarization, allowing

  20. Denton Vacuum Discovery-550 Sputterer

    Data.gov (United States)

    Federal Laboratory Consortium — Description: CORAL Name: Sputter 2 Similar to the existing 4-Gun Denton Discovery 22 Sputter system, with the following enhancements: Specifications / Capabilities:...

  1. Self-sputtering and reflection

    International Nuclear Information System (INIS)

    Self-sputtering and reflection are investigated with the Monte Carlo program TRIMSP. The results include particle and energy reflection coefficients, sputtering yields and sputtered energy versus incident angle and energy. Angular and energy distributions of reflected and sputtered particles are also given. Reflection and sputtering values are compared to show their contributions to selfsputtering. A comparison of calculated sputtering yields and sputtering efficiencies (sputtering energy) with experimental data is carried out. The systems investigated are mainly the bombardment of C, Ni, and W with self-ions. (orig.)

  2. Sputtering of water ice

    DEFF Research Database (Denmark)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.;

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from...

  3. Fundamentals of surfactant sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hofsaess, Hans [Second Institute of Physics, Georg-August University Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)], E-mail: hans.hofsaess@phys.uni-goettingen.de; Zhang Kun [Second Institute of Physics, Georg-August University Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2009-08-15

    We introduce a new sputter technique, utilizing the steady-state coverage of a substrate surface with up to 10{sup 16} cm{sup -2} of foreign atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These atoms strongly modify the substrate sputter yield on atomic to macroscopic length scales and therefore act as surfactant atoms (a blend of 'surface active agent'). Depending on the surfactant-substrate combination, the novel technique allows enhanced surface smoothing, generation of novel surface patterns, shaping of surfaces and formation of ultra-thin films. Sputter yield attenuation is demonstrated for sputtering of Si and Fe substrates and different surfactant species using 5 keV Xe ions at different incidence angles and fluences up to 10{sup 17} cm{sup -2}. Analytical approaches and Monte Carlo simulations are used to predict the sputtering yield attenuation as function of surfactant coverage. For sputtering of Si with Au surfactants we observe high sputter yields despite a steady-state surfactant coverage, which can be explained by strong ion-induced interdiffusion of substrate and surfactant atoms and the formation of a buried Au{sub x}Si surfactant layer in dynamic equilibrium.

  4. Fundamentals of surfactant sputtering

    International Nuclear Information System (INIS)

    We introduce a new sputter technique, utilizing the steady-state coverage of a substrate surface with up to 1016 cm-2 of foreign atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These atoms strongly modify the substrate sputter yield on atomic to macroscopic length scales and therefore act as surfactant atoms (a blend of 'surface active agent'). Depending on the surfactant-substrate combination, the novel technique allows enhanced surface smoothing, generation of novel surface patterns, shaping of surfaces and formation of ultra-thin films. Sputter yield attenuation is demonstrated for sputtering of Si and Fe substrates and different surfactant species using 5 keV Xe ions at different incidence angles and fluences up to 1017 cm-2. Analytical approaches and Monte Carlo simulations are used to predict the sputtering yield attenuation as function of surfactant coverage. For sputtering of Si with Au surfactants we observe high sputter yields despite a steady-state surfactant coverage, which can be explained by strong ion-induced interdiffusion of substrate and surfactant atoms and the formation of a buried AuxSi surfactant layer in dynamic equilibrium.

  5. Cathodic arc grown niobium films for RF superconducting cavity applications

    Science.gov (United States)

    Catani, L.; Cianchi, A.; Lorkiewicz, J.; Tazzari, S.; Langner, J.; Strzyzewski, P.; Sadowski, M.; Andreone, A.; Cifariello, G.; Di Gennaro, E.; Lamura, G.; Russo, R.

    2006-07-01

    Experimental results on the characterization of the linear and non-linear microwave properties of niobium film produced by UHV cathodic arc deposition are presented. Surface impedance Zs as a function of RF field and intermodulation distortion (IMD) measurement have been carried out by using a dielectrically loaded resonant cavity operating at 7 GHz. The experimental data show that these samples have a lower level of intrinsic non-linearities at low temperature and low circulating power in comparison with Nb samples grown by sputtering. These results make UHV cathodic arc deposition a promising technique for the improvement of RF superconducting cavities for particle accelerators.

  6. Cathodic arc grown niobium films for RF superconducting cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Catani, L. [INFN-Roma2, Rome (Italy); Cianchi, A. [INFN-Roma2, Rome (Italy); Lorkiewicz, J. [INFN-Roma2, Rome (Italy); Tazzari, S. [Universita di Roma ' Tor Vergata' and INFN-Roma2, Rome (Italy); Langner, J. [Soltan Institute for Nuclear Studies, Swierk (Poland); Strzyzewski, P. [Soltan Institute for Nuclear Studies, Swierk (Poland); Sadowski, M. [Soltan Institute for Nuclear Studies, Swierk (Poland); Andreone, A. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Cifariello, G. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Di Gennaro, E. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Lamura, G. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Russo, R. [Seconda Universita di Napoli, INFN-NA, Naples (Italy)

    2006-07-15

    Experimental results on the characterization of the linear and non-linear microwave properties of niobium film produced by UHV cathodic arc deposition are presented. Surface impedance Z {sub s} as a function of RF field and intermodulation distortion (IMD) measurement have been carried out by using a dielectrically loaded resonant cavity operating at 7 GHz. The experimental data show that these samples have a lower level of intrinsic non-linearities at low temperature and low circulating power in comparison with Nb samples grown by sputtering. These results make UHV cathodic arc deposition a promising technique for the improvement of RF superconducting cavities for particle accelerators.

  7. Research and Development of a New Field Enhanced Low Temperature Thermionic Cathode that Enables Fluorescent Dimming and Loan Shedding without Auxiliary Cathode Heating

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jin

    2009-01-07

    This is the final report for project entitled 'Research and development of a new field enhanced low temperature thermionic cathode that enables fluorescent dimming and load shedding without auxiliary cathode heating', under Agreement Number: DE-FC26-04NT-42329. Under this project, a highly efficient CNT based thermionic cathode was demonstrated. This cathode is capable of emitting electron at a current density two order of magnitude stronger then a typical fluorescent cathode at same temperatures, or capable of emitting at same current density but at temperature about 300 C lower than that of a fluorescent cathode. Detailed fabrication techniques were developed including CVD growth of CNTs and sputter deposition of oxide thin films on CNTs. These are mature technologies that have been widely used in industry for large scale materials processing and device fabrications, thus, with further development work, the techniques developed in this project can be scaled-up in manufacturing environment. The prototype cathodes developed in this project were tested in lighting plasma discharge environment. In many cases, they not only lit and sustain the plasma, but also out perform the fluorescent cathodes in key parameters such like cathode fall voltages. More work will be needed to further evaluate more detailed and longer term performance of the prototype cathode in lighting plasma.

  8. Experimental study of the discharge in the low pressure plasma jet sputtering system

    Czech Academy of Sciences Publication Activity Database

    Klusoň, J.; Kudrna, P.; Kolpaková, A.; Picková, I.; Hubička, Zdeněk; Tichý, M.

    2013-01-01

    Roč. 53, č. 1 (2013), s. 10-15. ISSN 0863-1042 Institutional support: RVO:68378271 Keywords : hollow cathode * plasma jet sputtering system * Langmuir probe Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.983, year: 2013

  9. Nitrogen dissociation during RF sputtering of Lipon electrolyte for all-solid-states batteries

    DEFF Research Database (Denmark)

    Stamate, Eugen; Christiansen, Ane Sælland; Holtappels, Peter

    2013-01-01

    phosphorus oxynitride (Lipon), that can be compacted with the anode and cathode electrodes in an all-solid-states structure where the nitrogen incorporation is considered one of the key parameters for controlling the ionic conductivity. In this work the nitrogen dissociation during RF sputtering of Lipon...

  10. Cathodic Protection Model Facility

    Data.gov (United States)

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

  11. Study of the plasma parameters in a high-current pulsed magnetron sputtering system

    International Nuclear Information System (INIS)

    Results are presented from experimental studies of the current-voltage characteristics and spatial and temporal parameters of the plasma in a high-current pulsed magnetron sputtering system with a 10-cm-diameter plane disk cathode. It is shown that the plasma density in such a system is three orders of magnitude higher than that in conventional dc magnetron discharges and reaches 1013 cm−3 at a distance of 250 mm from the cathode at a peak discharge current of 500 A. The plasma propagates from the cathode region at a velocity of 1 cm/μs in the axial direction and 0.25 cm/μs in the radial direction. Optical emission spectroscopy shows that the degree of plasma ionization increases severalfold with increasing discharge current, mainly at the expense of the sputtered material.

  12. Improved Dispenser Cathodes

    Science.gov (United States)

    Ives, R. Lawrence; Falce, Lou

    2006-01-01

    Variations in emission current from dispenser cathodes can be caused by variations in temperature and work function over the surface. This paper described research to reduce these variations using improved mechanical designs and controlled porosity cathodes made from sintered tungsten wires. The program goal is to reduce current emission variations to less than 5% over the surface of magnetron injection guns operating temperature limited.

  13. Dynamic behavior of thermionic dispenser cathodes under ion bombardment

    Science.gov (United States)

    Cortenraad, R.; van der Gon, A. W. Denier; Brongersma, H. H.; Gärtner, G.; Raasch, D.; Manenschijn, A.

    2001-04-01

    We have investigated the surface coverage and electron emission of thermionic dispenser cathodes during 3 keV Ar+ ion bombardment, thereby simulating the bombardment of the cathodes by residual gases that takes place in cathode-ray tubes as used in television sets. During the ion bombardment at the operating temperature of 1030 °C, a dynamic equilibrium is established between the sputter removal and resupply mechanisms of the Ba and O atoms that form the dipole layer on the cathode substrate. We demonstrated that the performance of the cathodes under ion bombardment is governed by the O removal and resupply rates. It was found that the Ba resupply rate is almost an order of magnitude higher than the O resupply rate, but that the Ba can only be present on the surface bound to O atoms. Therefore, the Ba/O ratio is approximately equal to unity during the ion bombardment. Based on the investigations of the removal and resupply processes, we proposed a model that accurately describes the surface coverage and electron emission during the ion bombardment, including the dependence of the ion flux and cathode temperature.

  14. Multilayer optical coating fabrication by dc magnetron reactive sputtering

    International Nuclear Information System (INIS)

    A conventional box coating chamber has been equipped with three dc magnetron sputtering cathodes, reactive gas (O2, N2, H2) pressure and flow control, planetary substrate holder, and optical monitoring to produce a low-temperature batch coating system for multilayer optical coating fabrication using oxides, nitrides, semiconductors and semitransparent metals. The system realizes the benefits traditionally derived from this geometry: maximum area of uniform coating thickness, spatially-averaged coating flux impingement angles, and precise thickness monitoring. The use of sputtering cathodes adds the benefits of increased flexibility in choice of materials deposited, increased adatom energy at the substrate, and increased chemical reactivity in a gas discharge. Dense, durable, fully-reacted dielectric coatings are achieved at low processing temperatures. Metal targets (sources) are used for ease of fabrication, and dc power avoids radio-frequency impedance matching requirements. The chamber and components are described and operation of the cathodes explained. Thickness uniformity profiles, deposition rates, and substrate temperature data are related. A list of materials investigated to date is presented with pertinent optical properties and intrinsic mechanical stress values. Illustrative performance examples for multilayer coatings on glasses and plastics are included

  15. Ion and neutral energy flux distributions to the cathode in glow discharges in Ar/Ne and Xe/Ne mixtures

    Science.gov (United States)

    Capdeville, H.; Pédoussat, C.; Pitchford, L. C.

    2002-02-01

    The work presented in the article is a study of the heavy particle (ion and neutral) energy flux distributions to the cathode in conditions typical of discharges used for luminous signs for advertising ("neon" signs). The purpose of this work is to evaluate the effect of the gas mixture on the sputtering of the cathode. We have combined two models for this study: a hybrid model of the electrical properties of the cathode region of a glow discharge and a Monte Carlo simulation of the heavy particle trajectories. Using known sputtering yields for Ne, Ar, and Xe on iron cathodes, we estimate the sputtered atom flux for mixtures of Ar/Ne and Xe/Ne as a function of the percent neon in the mixture.

  16. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

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

  17. Cathodes - Technological review

    International Nuclear Information System (INIS)

    Lithium cobalt oxide (LiCoO2) was already used in the first commercialized Li-ion battery by SONY in 1990. Still, it is the most frequently used cathode material nowadays. However, LiCoO2 is intrinsically unstable in the charged state, especially at elevated temperatures and in the overcharged state causing volume changes and transport limitation for high power batteries. In this paper, some technological aspects with large impact on cell performance from the cathode material point of view will be reviewed. At first it will be focused on the degradation processes and life-time mechanisms of the cathode material LiCoO2. Electrochemical and structural results on commercial Li-ion batteries recorded during the cycling will be discussed. Thereafter, advanced nanomaterials for new cathode materials will be presented

  18. Role of cathode identity in liquid chromatography particle beam glow discharge mass spectrometry

    International Nuclear Information System (INIS)

    A detailed evaluation of the role of cathode identity on the analytical and spectral characteristics of various organic, organometallic and metal analytes using liquid chromatography-particle beam/glow discharge mass spectrometry (LC-PB/GDMS) has been carried out. A d.c. discharge, operating with argon as the support gas, was used throughout this work. In this study, Cu which has a relatively high sputtering rate, Ni which has moderate sputtering rate and Ta which has very low sputtering rate, are taken as cathode materials to study the ionization, fragmentation, and analytical characteristics of organic (caffeine, epigallocatechin gallate, peptide as representative compounds), organometallic (selenomethionine, triethyl lead chloride as representative compounds) and metal (Fe, La, Cs and Pb) species. A range of discharge gas pressures (26.6-106.4 Pa) and currents (0.2-1.5 mA) were investigated with the test cathodes to determine their influence on the spectral composition and overall analytical response for the various test species. Calibration plots were obtained for all of the species for each of the three cathodes to determine the respective limits of detection. Relative detection limits in the range of 0.02 to 15 ng mL-1 (0.002-1.5 ng, absolute) for the test species were found to be in the order of Cu > Ni > Ta; which follows the order of the sputtering characteristics of the respective cathodes. These studies rendered information about the respective discharge parameters' role in choosing the most appropriate cathode identity in PB-GDMS for application in the areas of organic, organometallic and inorganic species analysis

  19. Novel matching lens and spherical ionizer for a cesium sputter ion source

    International Nuclear Information System (INIS)

    The beam optics of a multi-sample sputter ion source, based on the NEC MCSNICS, has been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing the acceleration of beam particles from eV to keV energy, minimizing space charge effects and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are these contributions to the emittance growth. The higher cathode voltage also raises the Child's law limit on the Cs current resulting in substantially increased output. The incidental focusing role of the extractor is reallocated to a deceleration Einzel lens and the velocity change needed to match to the pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to ensure that the beam fills less than 30% of the aperture to minimize aberrations. The improvements are applicable to sputter sources generally. (author)

  20. Novel matching lens and spherical ionizer for a cesium sputter ion source

    Indian Academy of Sciences (India)

    D C Weisser; N R Lobanov; P A Hausladen; L K Fifield; H J Wallace; S G Tims; E G Apushkinsky

    2002-12-01

    The beam optics of a multi-sample sputter ion source, based on the NEC MCSNICS, has been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing the acceleration of beam particles from eV to keV energy, minimizing space charge effects and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are these contributions to the emittance growth. The higher cathode voltage also raises the Child’s law limit on the Cs current resulting in substantially increased output. The incidental focusing role of the extractor is reallocated to a deceleration Einzel lens and the velocity change needed to match to the pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to ensure that the beam fills less than 30% of the aperture to minimize aberrations. The improvements are applicable to sputter sources generally.

  1. Novel matching lens and spherical ionizer for a cesium sputter ion source

    Science.gov (United States)

    Weisser, D. C.; Lobanov, N. R.; Hausladen, P. A.; Fifield, L. K.; Wallace, H. J.; Tims, S. G.; Apushkinsky, E. G.

    2002-12-01

    The beam optics of a multi-sample sputter ion source, based on the NEC MCSNICS, has been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing the acceleration of beam particles from eV to keV energy, minimizing space charge effects and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are these contributions to the emittance growth. The higher cathode voltage also raises the Child's law limit on the Cs current resulting in substantially increased output. The incidental focusing role of the extractor is reallocated to a deceleration Einzel lens and the velocity change needed to match to the pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to ensure that the beam fills less than 30% of the aperture to minimize aberrations. The improvements are applicable to sputter sources generally.

  2. Beam optics optimization of a negative-ion sputter source

    Indian Academy of Sciences (India)

    F Osswald; R Rebmeister

    2002-11-01

    A negative-ion sputter source has been studied in order to increase the beam intensity delivered by the Vivitron tandem injector. The aim was to characterize the influence on the beam intensity of some factors related to the configuration of the source such as the shape of the target holder, the target surface topography and the anode/cathode voltage. The paper reports the results carried out by experimentation on a test facility and on the injector itself as well as the investigations performed with computer simulations.

  3. Application of Magnetron Sputtering in Fabricating MEMS Microbatteries

    Institute of Scientific and Technical Information of China (English)

    SHEN Wan; YANG Zhi-min; XING Guang-jian; MAO Chang-hui; DU Jun

    2004-01-01

    With the development of MEMS and the electronic devices's miniaturization and integration, a new kind of power sources that can satisfy the need for high energy density is required. Microbatteries are being researched abroad for their advantages of extreme thinness and long-term power supply. The development of MEMS microbatteries are reviewed and suggestedmagnetron sputtering in fabricating a high-performance microbattery. The technics as annealing are analyzed. The microbattery with a LiNi1-x Cox O2 cathode exhibited stable cycle ability and a high specific discharge capacity, which was attributed to the alloying effect of the LiNiO2and LiCoO2.

  4. Color center laser optogalvanic spectroscopy of lithium, barium, neon and argon Rydberg states in hollow cathode discharges

    International Nuclear Information System (INIS)

    Numerous infrared transitions between Rydberg states of neon and argon have been measured by optogalvanic spectroscopy in commercial hollow cathode lamps using a color center laser operating in the range 3600-4100 cm-1. Transitions in lithium and barium atoms sputtered from the cathodes were also detected. The generality and high sensitivity of this technique indicates potential applications for frequency calibration in the infrared, atomic and molecular spectroscopy, and plasma diagnostics. (orig.)

  5. Noble gas sputtering calculations using TRIM

    International Nuclear Information System (INIS)

    In conjunction with our experimental work on saddle field ion sputtering, we have attempted to apply the Monte Carlo program TRIM (Transport of Ions in Matter) to calculate the sputter yields for a variety of noble gas sputtering applications. Comparison with experiments are shown. Information extracted from these analyses have proved useful in optimizing the experimental sputtering parameters. Calculated sputter yields obtained utilizing TRIM are presented for noble gas sputtering of a variety of materials common to nuclear target production

  6. Cathode materials review

    International Nuclear Information System (INIS)

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research

  7. Application of a multi-pass absorption cell for measurement of sputtered tungsten atoms' density

    International Nuclear Information System (INIS)

    A dedicated gas discharge tube equipped with a hollow cathode made of tungsten is setup for sputtering of W atoms. A multi-pass White type absorption cell is designed to increase the sensitivity of the absorption method. The optical system consists of three externally mounted aluminium-coated spherical mirrors with 70 cm radius of curvature. Measurements of the cell relative transmittance in the UV and visible spectral regions are carried out. Time-resolved measurements of sputtered ground-state tungsten atoms' density in 2-pass configuration, as well as assessment of the diffusion coefficient of these atoms in argon at 350 K temperature are made.

  8. Laser spectroscopy of sputtered atoms

    International Nuclear Information System (INIS)

    The use of laser radiation to study the sputtering process is of relatively recent origin. Much has been learned from this work about the basic physics of the sputtering process itself through measurements of velocity and excited state distributions of sputtered atoms and the effects of adsorbates on substrate sputtering yields. Furthermore, the identification, characterization, and sensitive detection of sputtered atoms by laser spectroscopy has led to the development of in situ diagnostics for impurity fluxes in the plasma edge regions of tokamaks and of ultrasensitive methods (ppB Fe in Si) for surface analysis with ultralow (picocoulomb) ion fluences. The techniques involved in this work, laser fluorescence and multiphoton resonance ionization spectroscopy, will be described and illustrations given of results achieved up to now. 55 refs., 5 figs., 1 tab

  9. Highly Efficient Micro Cathode Project

    Data.gov (United States)

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

  10. Advanced Cathode Electrolyzer (ACE) Project

    Data.gov (United States)

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

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

    International Nuclear Information System (INIS)

    of electrons (we will call this a hollow cathode arc or HCA). The accepted explanation for the HCD phenomenon involves the existence of high-energy “pendulum” electrons, which are reflected from the sheaths on either side of the cathode; the long trajectory of this electron is understood to produce a large number of secondary electrons, with this resulting in the high plasma density and plasma current. We describe the structure of a parallel-plate discharge, particularly the gas phase and cathode surface excitation and ionization collision processes. Using this description, we discuss some of the problems associated with the conventional hollow cathode model and we propose a new explanation that has important implications for the physics and applications of hollow cathodes. In the last section of this review, we describe how hollow cathodes have and can be used to deposit thin films and nanostructured coatings. We provide an extensive and approximately chronological listing of how hollow cathodes have been successfully used to deposit materials, mainly by sputtering and plasma enhanced chemical vapour deposition based techniques. - Highlights: • We describe the discrepancies of the pendulum model of the hollow cathode plasma. • We present a model of the hollow cathode discharge based on doubly-charged ions. • The secondary electron yield of Ar++ from the cathode is about 4 times that of Ar+. • Plasma generation of Ar++ and the secondary electron emission are quasi-resonant. • A very high density hollow cathode discharge in pure hydrogen is not possible

  12. Cathode material for lithium batteries

    Science.gov (United States)

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

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

  13. Sputtering of a silicon surface: Preferential sputtering of surface impurities

    Czech Academy of Sciences Publication Activity Database

    Nietiadi, M.L.; Rosandi, Y.; Lorinčík, Jan; Urbassek, H.M.

    -, č. 303 (2013), s. 205-208. ISSN 0168-583X Institutional support: RVO:67985882 Keywords : Sputtering * Molecular dynamics * SIMS Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.186, year: 2013

  14. Sputtering. [as deposition technique in mechanical engineering

    Science.gov (United States)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  15. Smart cathodic protection systems

    NARCIS (Netherlands)

    Polder, R.B.; Leggedoor, J.; Schuten, G.; Sajna, S.; Kranjc, A.

    2010-01-01

    Cathodic protection delivers corrosion protection in concrete structures exposed to aggressive environments, e.g. in de-icing salt and marine climates. Working lives of a large number of CP systems are at least more than 13 years and probably more than 25 years, provided a minimum level of maintenan

  16. Video analysis of inclusion induced macroparticle emission from aluminum sputtering targets

    International Nuclear Information System (INIS)

    Molten metal macroparticles emitted from the surface of aluminum sputtering targets during arcing events is an important source of particulate contamination in sputtering. We used high-speed video analysis of arcing from sputtering targets purposefully doped with aluminum oxide inclusions to determine the velocity, trajectory, and relative size of the emitted macroparticles. The results of these analyses show that the molten droplets of aluminum are emitted from the target with velocities ranging from 5 to over 500 m/s. Ejection angles for the observed macroparticles were concentrated at angles of around 30 deg. from the target plane. We also found that only certain arcing events generated video detectable macroparticle emission (∼18% of the arc events). Macroparticle size and velocity did not appear to be related. An estimate of macroparticle temperature based upon the sensitivity of the charge coupled device camera and the observed lack of macroparticle cooling yields an aluminum macroparticle temperature between 1750 and 4000 K. One cathode arc spot was observed on the target surface and the decay in intensity of this spot was used to estimate the cathode arc spot temperature. The cooling rate of a cathode arc spot on the target surface indicated that the arc spot cools by radiation and diffusion and has an initial temperature of 3000 K. This value is consistent with the macroparticle-estimated temperature of 3000±1000 K

  17. CdS Film Thickness Characterization By R. F. Magnetron Sputtering

    International Nuclear Information System (INIS)

    In this work, cadmium sulphide (CdS) target with 99.999% purity was used as a target in RF magnetron sputtering. The sputtering experiment was conducted onto silicon oxide substrates at different temperatures ranging from 200 deg. C to 400 deg. C in 50 deg. C steps, using a capacitive coupled magnetron cathode with 13.65 MHz that at higher magnetron power. After all investigations, it was concluded that 300 deg. C substrate temperature is suitable for producing CdS films on silicon wafer with RF magnetron sputtering and the examined properties (good crystallinity and low resistivity) of this film show its feasibility for technological purposes, especially for light sensor cells.

  18. Pipeline integrity through cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N. [Gas Authority India Ltd., New Delhi (India); Khanna, A.S. [Indian Inst. of Technology, Bombay (India)

    2008-07-01

    Pipeline integrity management is defined as a process for assessing and mitigating pipeline risks in an effort to reduce both the likelihood and consequences of incidents. Defects on pipelines result in production losses, environmental losses, as well as loss of goodwill and subsequent financial losses. This presentation addressed pipeline integrity through cathodic protection. It noted that pipeline integrity can be strengthened by successfully controlling, monitoring and mitigating corrosion strategies. It can also be achieved by avoiding external and internal corrosion failures. A good coating offers the advantages of low current density; lower power consumption; low wear of anodes; larger spacing between cathodic protection stations; and minimization of interference problems. The presentation reviewed cathodic protection of cross-country pipelines; a sacrificial cathodic protection system; and an impressed current cathodic protection system. The efficiency of a cathodic system was shown to depend on the use of reliable power sources; proper protection criterion; efficient and effective monitoring of cathodic protection; proper maintenance of the cathodic protection system; and effective remedial measures. Selection criteria, power sources, and a comparison of cathodic protection sources were also presented. Last, the presentation addressed protection criteria; current interruption circuits; monitoring of the cathodic protection system; use of corrosion coupons; advantages of weightless coupons; checking the insulating flanges for shorted bolts; insulated/short casings; anodic and cathodic interference; common corridor problems; and intelligent pigging. tabs., figs.

  19. Study of the three-step photoionization of uranium using a hollow cathode discharge tube

    International Nuclear Information System (INIS)

    The hollow cathode discharge (HCD) tube as a spectral light source has been developed. Because any element including refractory metals can be atomized by the cathode sputtering effect in HCD, a simple and reliable atomic vapor source produced by HCD has been widely used in laser spectroscopy. To the authors' knowledge, there is no previous work on the photoionization processes of metal atoms using an HCD tube. Here the authors report their study of the resonant three-step ionization of U in a homemade HCD tube

  20. Crystal Structure and Optical Properties of Al-Doped ZnO Large-Area Thin Films Using 1500 mm Dual Cylindrical Cathodes.

    Science.gov (United States)

    Lee, JinJu; Ha, Jong-Yoon; Yim, Haena; Choi, Won-Kook; Choi, Ji-Won

    2015-11-01

    The large-area Al-doped ZnO thin films are successfully deposited at room temperature on polycarbonate substrate using a 1500 mm dual cylindrical cathodes sputtering system. Those thin films have smooth surfaces (RMS: 9.6 nm) and lower thicknesses deviation (Uniformity: 98.6%) despite of high RF power. The optical transmittance properties of 3.13 wt% Al doped ZnO thin films have above 85% in visible region. A dual cylindrical cathodes sputtering system can fabricate transparent electrode on flexible electronic devices at room temperature for mass production of 6th generation solar cell and display industry. PMID:26726519

  1. A cross-corner effect in a rectangular sputtering magnetron

    International Nuclear Information System (INIS)

    Electron trajectories, ionization distribution, and magnetic field in a conventional rectangular sputtering magnetron cathode are simulated in order to understand the mechanism of a cross-corner effect, which is a common phenomenon associated with rectangular magnetron cathodes and which limits the target utilization. It is found that once the magnetic field in end region of the cathode is different from that in straightway, the cross-corner effect exists. Using a fourth-order Runge-Kutta method, the electron trajectories are simulated, showing that the electrons may drift much faster in the end region than in the straightway and pass quickly to cross-corner region. A Monte-Carlo method is employed to simulate ionization distribution and to quantitatively predict target erosion. The results show denser ionization in the cross-corner region, causing more intensive erosion in that area. We demonstrate that by properly modifying the magnet field in the end region, the electron drift velocity and ionization distribution can be controlled and the cross-corner effect may be significantly reduced

  2. Arc cathode spots

    International Nuclear Information System (INIS)

    Arc spots are usually highly unstable and jump statistically over the cathode surface. In a magnetic field parallel to the surface, preferably they move in the retrograde direction; i.e., opposite to the Lorentzian rule. If the field is inclined with respect to the surface, the spots drift away at a certain angle with respect to the proper retrograde direction (Robson drift motion). These well-known phenomena are explained by one stability theory

  3. Process-structure-property correlations in pulsed dc reactive magnetron sputtered vanadium oxide thin films

    International Nuclear Information System (INIS)

    Cathode hysteresis in the reactive pulsed dc sputtering of a vanadium metal target was investigated to correlate the structural and electrical properties of the resultant vanadium oxide thin films within the framework of Berg's model [Berg et al., J. Vac. Sci. Technol. A 5, 202 (1987)]. The process hysteresis during reactive pulsed dc sputtering of a vanadium metal target was monitored by measuring the cathode (target) current under different total gas flow rates and oxygen-to-argon ratios for a power density of ∼6.6.W/cm2. Approximately 20%-25% hysteretic change in the cathode current was noticed between the metallic and oxidized states of the V-metal target. The extent of the hysteresis varied with changes in the mass flow of oxygen as predicted by Berg's model. The corresponding microstructure of the films changed from columnar to equiaxed grain structure with increased oxygen flow rates. Micro-Raman spectroscopy indicates subtle changes in the film structure as a function of processing conditions. The resistivity, temperature coefficient of resistance, and charge transport mechanism, obeying the Meyer-Neldel relation [Meyer and Neldel, Z. Tech. Phys. (Leipzig) 12, 588 (1937)], were correlated with the cathode current hysteric behavior.

  4. On the argon and oxygen incorporation into SiOx through ion implantation during reactive plasma magnetron sputter deposition

    OpenAIRE

    van Hattum, E.D.; Boltje, D. B.; Palmero Acebedo, A.; Arnoldbik, W.M.; Rudolph, H.; Habraken, F.H.P.M.

    2008-01-01

    The incorporation of argon in SiOx (0 x 2) during reactive plasma magnetron sputter deposition using a O2/Ar plasma and a silicon sputter cathode has been investigated and related to the flux of argon ions created in the plasma afterglowregion on the growth surface. The argon concentration in the grown films appears to be mainly a function of the x-value, independent of the extent of ion bombardment on the growing surface, and only slightly dependent on the substrate temperature during the gr...

  5. Characterization of Ag-doped vanadium oxide (AgxV2O5) thin film for cathode of thin film battery

    International Nuclear Information System (INIS)

    The effect of silver co-sputtering on the characteristics of amorphous V2O5 films, grown by dc reactive sputtering, is investigated. The co-sputtering process influences the growth mechanism as well as the characteristics of the V2O5 films. X-ray diffraction (XRD), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectrometry (XPS) results indicate that the microstructure of the V2O5 films is affected by the rf power of the co-sputtered silver. In addition, an all-solid-state thin film battery with full cell structure of Li/LiPON/AgxV2O5/Pt has been fabricated. It is found that the silver co-sputtered V2O5 cathode film exhibits better cycle performance than an undoped one

  6. Laser sputter neutral mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    King, B.V.; Clarke, M.; Hu, H.; Betz [Newcastle Univ., NSW (Australia). Dept. of Physics

    1993-12-31

    Laser sputter neutral mass spectrometry (LSNMS) is an emerging technique for highly sensitive surface analysis. In this technique a target is bombarded with a pulsed beam of keV ions. The sputtered particles are intercepted by a high intensity pulsed laser beam above the surface and ionised with almost 100% efficiency. The photions may then be mass analysed using a quadrupole or, more commonly, using time of flight (TOF) techniques. In this method photoions are extracted from the ionisation region, accelerated to a known energy E{sub o} and strike a channelplate detector a distance `d` away. The flight time `t` of the photoions is then related to their mass by `d` {radical}m / {radical} 2E{sub o} so measurement of `t` allows mass spectra to be obtained. It is found that LSNMS is an emerging technique of great sensitivity and flexibility, useful for both applied analysis and to investigate basic sputtering processes. 4 refs., 3 figs.

  7. Sputtered metal source for rate coefficient measurements of asymmetric charge transfer reactions

    International Nuclear Information System (INIS)

    Complete text of publication follows. Asymmetric charge transfer (ACT) reactions between noble gas ions and metal atoms play an important role in numerous glow discharge applications. Due to the sputtering effect of ions impinging on the cathode surface significant metal density can be created in the cathode area of dc noble gas discharges. These metal atoms are then ionized and excited in the negative glow region, which is utilized in glow discharge spectroscopy (GDS) applications. ACT represents an important source of excited metal ions in the negative glow. Numerical modeling of the cathode region of a sputtering discharge requires rate coefficient values of ACT reactions as input data [Bogaerts et al. J. Anal. Atom. Spectrom. 11 (1996) 841]. There are rate coefficient values available in the literature only for volatile metals - in combination with different noble gas ions - that can be evaporated at relatively low temperatures (e.g. Hg, Zn, Cd etc.). However, data for other metals (Cu, Fe, Ag, etc.) have not been measured yet. The aim of this work is to build a metal source that can be applied for rate coefficient measurements of ACT reactions. The new sputtered metal source operates at room temperature creating homogeneous spatial distribution of metal atoms in a 9 cm3 region. Four hollow-cathode discharges - placed symmetrically around the central region - provide the needed metal density in the order of 5 x 1011 cm-3 as determined by atomic absorption spectroscopy. The future work focuses on the ACT rate coefficient measurements. The authors kindly acknowledge the support by the MRTN-CT-035459.

  8. Emission from ferroelectric cathodes

    International Nuclear Information System (INIS)

    The authors have recently initiated an investigation of electron emission from ferroelectric cathodes. The experimental apparatus consisted of an electron diode and a 250 kV, 12 ohm, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable of delivering two high voltage pulses within 50 μs of each other and is capable of operating at a sustained repetition rate of 5 Hz. The initial measurements indicate that emission current densities above the Child-Langmuir Space Charge Limit, JCL, are possible. They explain this effect to be based on a non-zero initial energy of the emitted electrons. They also determined that this effect is strongly coupled to relative timing between the inversion pulse and application of the main anode-cathode pulse. They also have initiated brightness measurements of the emitted beam and estimate a preliminary lower bound to be on the order of 109 A/m2-rad2 for currents close to JCL and factor of two less at currents over 4JCL. As in previous measurements at this Laboratory, they performed the measurement using a pepper pot technique. Beamlet profiles are recorded with a fast phosphor and gated cameras. They describe their apparatus and preliminary measurements

  9. Nanostructured lanthanum manganate composite cathode

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  10. Virtual cathode microwave devices -- Basics

    Energy Technology Data Exchange (ETDEWEB)

    Thode, L.E.; Snell, C.M.

    1991-01-01

    Unlike a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential can cause electron reflection. The region associated with this electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and through the bunching of electrons trapped in a potential well between the real and virtual cathodes. These two mechanisms are competitive. There are three basic classes of virtual cathode devices: (1) reflex triode; (2) reditron and side-shoot vircator; and (3) reflex diode or vircator. The reflex diode is the highest power virtual-cathode device. For the reflex diode the energy exchange between the beam and electromagnetic wave occurs in both the axial and radial directions. In some designs the oscillating-virtual-cathode frequency exceeds the reflexing-electron frequency exceeds the oscillating-virtual-cathode frequency. For the flex diode a periodic disruption in magnetic insulation can modulate the high- frequency microwave power. Overall, particle-in-cell simulation predictions and axial reflex diode experiments are in good agreement. Although frequency stability and phase locking of the reflex diode have been demonstrated, little progress has been made in efficiency enhancement. 58 refs., 11 figs.

  11. Virtual cathode microwave devices: Basics

    Science.gov (United States)

    Thode, L. E.; Snell, C. M.

    Unlike a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential can cause electron reflection. The region associated with this electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and through the bunching of electrons trapped in a potential well between the real and virtual cathodes. These two mechanisms are competitive. There are three basic classes of virtual cathode devices: (1) reflex triode; (2) reditron and side-shoot vircator; and (3) reflex diode or vircator. The reflex diode is the highest power virtual-cathode device. For the reflex diode the energy exchange between the beam and electromagnetic wave occurs in both the axial and radial directions. In some designs the oscillating virtual-cathode frequency exceeds the reflexing-electron frequency while in other designs the reflexing-electron frequency exceeds the oscillating virtual-cathode frequency. For the flex diode, a periodic disruption in magnetic insulation can modulate the high-frequency microwave power. Overall, particle-in-cell simulation predictions and axial reflex diode experiments are in good agreement. Although frequency stability and phase locking of the reflex diode have been demonstrated, little progress has been made in efficiency enhancement.

  12. A 10B-based neutron detector with stacked Multiwire Proportional Counters and macrostructured cathodes

    CERN Document Server

    Stefanescu, I; Birch, J; Defendi, I; Hall-Wilton, R; Hoglund, C; Hultman, L; Zee, M; Zeitelhack, K

    2013-01-01

    We present the results of the measurements of the detection efficiency for a 4.7 \\r{A} neutron beam incident upon a detector incorporating a stack of up to five MultiWire Proportional Counters (MWPC) with Boron-coated cathodes. The cathodes were made of Aluminum and had a surface exhibiting millimeter-deep V-shaped grooves of 45{\\deg}, upon which the thin Boron film was deposited by DC magnetron sputtering. The incident neutrons interacting with the converter layer deposited on the sidewalls of the grooves have a higher capture probability, owing to the larger effective absorption film thickness. This leads to a higher overall detection efficiency for the grooved cathode when compared to a cathode with a flat surface. Both the experimental results and the predictions of the GEANT4 model suggests that a 5-counter detector stack with coated grooved cathodes has the same efficiency as a 7-counter stack with flat cathodes. The reduction in the number of counters in the stack without altering the detection efficie...

  13. Patterning of dispenser cathode surfaces to a controlled porosity

    Science.gov (United States)

    Garner, Charles E.; Deininger, William D.; Gibson, John; Thomas, Richard

    1989-01-01

    A process to pattern slots approximately 1.25 microns in width into 25-micron-thick W films that have been deposited onto flat or concave surfaces is discussed. A 25-micron-thick W film with a high degree of (100) orientation is chemically vapor deposited (CVD) onto a flat or concave Mo mandrel. A 5-micron-thick Al film is deposited onto the CVD W, followed by 2 microns of photoresist. On concave cathodes, XeCl2 laser ablation or X-ray lithography is used to pattern the photoresist, whereas on flat cathodes deep UV lithography can be used. The patterned photoresist serves as the mask in a Cl ion-beam-assisted etching (IBAE) process to pattern the Al. An alternative process is to deposit Al2O3 films onto the W and pattern the Al2O3 using laser ablation. The W film is then patterned to 3-6-micron slot widths using IBAE + ClF3 with the patterned Al or Al2O3 as the mask. Finally, a sputter deposition step is required to close up the slots to approximately 1 micron. The process described is capable of patterning concave dispenser cathodes to a controlled and precise porosity.

  14. An hollow cathode ion source as an EBIS injector for metallic elements

    International Nuclear Information System (INIS)

    A Hollow Cathode Ion Source (HCIS) has been developed in our Laboratory to produce, by cathodic sputtering in a glow discharge, an one charge metallic ion beam. This source is used as an injector for the Electron Beam Ion Source (EBIS) Dione that produce, after ion stripping, a highly charged heavy ion beam for acceleration in Mimas - Saturne synchrotrons. On account of the good pulse to pulse repeatability of the HCIS, the very long lifetime of the cathode (several months), as well as the very good value of the normalized emittance (εnorm = 4.10-9 πmrad), this source appears as an ideal EBIS injector for metallic and gaseous elements. In this paper we report the description of the HCIS and the experimental results achieved, after injection in the EBIS, by the production of heavy ion beams like Fe20+, Au50+, and U55+ (from 4.107 to 9.106 ions/cycle). (author)

  15. Miniature Reservoir Cathode: An Update

    Science.gov (United States)

    Vancil, Bernard K.; Wintucky, Edwin G.

    2002-01-01

    We report on recent work to produce a small low power, low cost reservoir cathode capable of long life (more than 100,000 hours) at high loading (> 5 A/sq cm). Our objective is a highly manufacturable, commercial device costing less than $30. Small highly loaded cathodes are needed, especially for millimeter wave tubes, where focusing becomes difficult when area convergence ratios are too high. We currently have 3 models ranging from .060-inch diameter to. 125-inch diameter. Reservoir type barium dispenser cathodes have a demonstrated capability for simultaneous high emission density and long life. Seven reservoir cathodes continue to operate on the cathode life test facility at NSWC, Crane, Indiana at 2 and 4 amps/sq cm. They have accumulated nearly 100,000 hours with practically no change in emission levels or knee temperature.

  16. Formation and stability of sputtered clusters

    International Nuclear Information System (INIS)

    Current theory for the formation of sputtered clusters states that either atoms are sputtered individually and aggregate after having left the surface or they are sputtered as complete clusters. There is no totally sharp boundary between the two interpretations, but experimental evidence is mainly thought to favour the latter model. Both theories demand a criterion for the stability of the clusters. In computer simulations of sputtering, the idea has been to use the same interaction potential as in the lattice computations to judge the stability. More qualitatively, simple geometrical shapes have also been looked for. It is found here, that evidence for 'magic numbers' and electron parity effects in clusters have existed in the sputtering literature for a long time, making more sophisticated stability criteria necessary. The breakdown of originally sputtered metastable clusters into stable clusters gives strong support to the 'sputtered as clusters' hypothesis. (author)

  17. Sputtering technology in solid film lubrication

    Science.gov (United States)

    Spalvins, T.

    1978-01-01

    Potential and present sputtering technology is discussed as it applies to the deposition of solid film lubricants particularly MoS2, WS2, and PTFE. Since the sputtered films are very thin, the selection of the sputtering parameters and substrate condition is very critical as reflected by the lubricating properties. It was shown with sputtered MoS2 films that the lubricating characteristics are directly affected by the selected sputtering parameters (power density, pressure, sputter etching, dc-biasing, etc.) and the substrate temperature, chemistry, topography and the environmental conditions during the friction tests. Electron microscopy and other surface sensitive analytical techniques illustrate the resulting changes in sputtered MoS2 film morphology and chemistry which directly influence the film adherence and frictional properties.

  18. Microstructure and properties of sputtered thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    Yang Gao; Lun Xie; Feng Pan; Mengcheng Chen

    2004-01-01

    A 3 kW radio frequency (RF) magnetron-sputtering unit was used to produce zirconia ceramic coatings on hollow turbine blades and vanes, which had been deposited a NiCrAlY bond coat layer by cathodic arc deposition. The NiCrAlY coating surface was shot-peened, and the residual stress in the bond coat layer and the effects of heat treatment on the residual stress are presented.After shot peening porosities and microgaps disappear in the NiCrAlY bond coat, the whole depth profile is residual compressive stress. Coarseness tests show that the roughness value (Rz) decreases from 16.4 to 3.3 μm. The microstructure and phase composition of the coatings were investigated using electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The results show that the NiCrAlY bond coat is composed of γ' and Cr phases, and the Al2O3 scales are formed near the interface between the ZrO2 ceramic layer and the NiCrAlY bond coat. No degradation occurred to RF sputtered ceramic coatings after oxidating at 1150℃ for 100 h,heating at 1150℃ for 5 min and then air-cooling for 500 thermal cycles.

  19. Deposition of chromium nitrides, oxy-nitrides and titanium carbides on steel substrates by DC magnetron sputtering

    International Nuclear Information System (INIS)

    The present paper deals with the deposition of chromium and titanium nitrides, oxynitrides, carbides and carbonitrides onto low carbon steel by reactive magnetron sputtering. The films were obtained by using different reactive gases (02, N2, CH4,). The process advancement and the corresponding film composition variations were investigated as a function of the specific reactivity of each gas. In addition, the cathode poisoning phenomena were studied. (author). 4 refs., 6 figs

  20. Optical diagnostics of sputtering in magnetically enhanced high-current discharges

    Science.gov (United States)

    Smith, David; Aceto, Steven; Trotter, Jason; Sommerer, Timothy; Lawler, James

    2014-10-01

    We have investigated a gallium-based liquid cathode for use in a high-voltage, high-power gas switch for grid-scale electric power conversion. The cathode requirements include conduction of high current density (1--10 A cm-2) , preferably at low voltage, along with minimal loss by evaporation and/or sputtering. The approach to satisfy these criteria has been to operate with a modified commercial magnetron system at high pressure where the choice of working comprises the light elements, such as hydrogen or helium. A separate anode is used to form a plane-parallel geometry. We have demonstrated pulsed operation with current densities exceeding 2 A cm-2 and voltages below 200 V, over a pressure range of 50--800 mTorr. The sputtering rate on gallium and other cathode materials has been estimated for various plasma conditions using a line ratio emission spectroscopy diagnostic based on analysis of the radiation trapping. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

  1. Microstructure and work function of dispenser cathode coatings: Effects on thermionic emission

    Science.gov (United States)

    Swartzentruber, Phillip

    Dispenser cathodes emit electrons through thermionic emission and are a critical component of space-based and telecommunication devices. The emission of electrons is enhanced when coated with a refractory metal such as osmium (Os), osmium-ruthenium (Os-Ru), or iridium (Ir). In this work the microstructure, thermionic emission, and work function of thin film Os-Ru coatings were studied in order to relate microstructural properties and thermionic emission. Os-Ru thin film coatings were prepared through magnetron sputtering and substrate biasing to produce films with an array of preferred orientations, or texture. The effect of texture on thermionic emission was studied in detail through closely-spaced diode testing, SEM imaging, and x-ray diffraction. Results indicated that there was a strong correlation with emission behavior and specific preferred orientations. An ultra-high vacuum compatible Kelvin Probe was used to measure the work function of W-Os-Ru ternary alloy films to determine the effect W interdiffusion has on work function. The results indicated that a high work function alloy coating corresponded to low work function cathodes, as expected. It was inferred that a high work function alloy coating results in a low work function cathode because it aligns more closely with ionization energy of Ba. The results also proved that this method of evaluating dispenser cathode coatings can distinguish small variations in microstructure and composition and may be a beneficial tool in the development of improved dispenser cathode coatings. A novel experimental apparatus was constructed to measure the work function of dispenser cathode coatings in-vacuo using the ultra-high vacuum Kelvin Probe. The apparatus is capable of activating cathodes at high temperature and measuring the work function at elevated temperature. The design of this apparatus allows for more rapid evaluation of dispenser cathode coatings.

  2. Semi-empirical formulas for sputtering yield

    International Nuclear Information System (INIS)

    When charged particles, electrons, light and so on are irradiated on solid surfaces, the materials are lost from the surfaces, and this phenomenon is called sputtering. In order to understand sputtering phenomenon, the bond energy of atoms on surfaces, the energy given to the vicinity of surfaces and the process of converting the given energy to the energy for releasing atoms must be known. The theories of sputtering and the semi-empirical formulas for evaluating the dependence of sputtering yield on incident energy are explained. The mechanisms of sputtering are that due to collision cascade in the case of heavy ion incidence and that due to surface atom recoil in the case of light ion incidence. The formulas for the sputtering yield of low energy heavy ion sputtering, high energy light ion sputtering and the general case between these extreme cases, and the Matsunami formula are shown. At the stage of the publication of Atomic Data and Nuclear Data Tables in 1984, the data up to 1983 were collected, and about 30 papers published thereafter were added. The experimental data for low Z materials, for example Be, B and C and light ion sputtering data were reported. The combination of ions and target atoms in the collected sputtering data is shown. The new semi-empirical formula by slightly adjusting the Matsunami formula was decided. (K.I.)

  3. Hollow Cathode With Multiple Radial Orifices

    Science.gov (United States)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  4. Hollow cathode hydrogen ion source

    International Nuclear Information System (INIS)

    High current density ion sources have been used to heat plasmas in controlled thermonuclear reaction experiments. High beam currents imply relatively high emission currents from cathodes which have generally taken the form of tungsten filaments. This paper describes a hydrogen ion source which was primarily developed to assess the emission current capability and design requirements for hollow cathodes for application in neutral injection devices. The hydrogen source produced ions by electron bombardment via a single hollow cathode. Source design followed mercury ion thruster technology, using a weak magnetic field to enhance ionization efficiency. A 1.3-cm diameter hollow cathode using a low work function material dispenser performed satisfactorily over a discharge current range of 10 to 90 A. Cylindrical probe measurements taken without ion extraction indicate maximum ion number densities on the order of 1012 cm-3. Discharge durations ranged from 30 seconds to continuous operation. Tests with beam extraction at 2.5 keV and 30 A discharge current yield average ion beam current densities of 0.1 A cm-2 over a 5-cm extraction diameter. Results of this study can be used to supply the baseline information needed to scale hollow cathodes for operation at discharge currents of hundreds of amperes using distributed cathodes

  5. Particle visualization in high-power impulse magnetron sputtering. I. 2D density mapping

    Energy Technology Data Exchange (ETDEWEB)

    Britun, Nikolay, E-mail: nikolay.britun@umons.ac.be; Palmucci, Maria; Konstantinidis, Stephanos [Chimie des Interactions Plasma-Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons (Belgium); Snyders, Rony [Chimie des Interactions Plasma-Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons (Belgium); Materia Nova Research Center, Parc Initialis, B-7000 Mons (Belgium)

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti{sup +}), and Ar metastable atoms (Ar{sup met}) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to their spatial density distributions, are discussed.

  6. STUDY ON THE TANTALIZING ON THE SURFACE OF TITANIUM ALLOY BY NET-SHAPE CATHODE GLOW DISCHARGING

    Institute of Scientific and Technical Information of China (English)

    F. Chen; H. Zhou; Y.F. Zhang; J.D. Pan

    2005-01-01

    A new net-shape cathode sputtering target which has a simple structure and a high sputtering was put forward. The multiple-structure made of alloying and coating layers of tantalum was achieved on the surface of TC4 (Ti6Al4V) using this method in double glow surface alloying process. The tantalized samples were investigated by SEM, XRD and electrochemical corrosion method .Results show the complicated tissue of pure tantalizing layer and diffusion layer was successfully formed on the surface of TC4 with the method of net-shape cathode glow discharge, which further improved the corrosion-resistance of TC4 and formed good corrosion-resistant alloys.

  7. Laser fluorescence spectroscopy of sputtered uranium atoms

    International Nuclear Information System (INIS)

    Laser induced fluorescence (LIF) spectroscopy was used to study the sputtering of 99.8% 238U metal foil when bombarded by normally incident 500 to 3000 eV Ne+, Ar+, Kr+, and O2+. A three-level atom model of the LIF processes is developed to interpret the observed fluorescent emission from the sputtered species. The model shows that close attention must be paid to the conditions under which the experiment is carried out as well as to the details of the collision cascade theory of sputtering. Rigorous analysis shows that when properly applied, LIF can be used to investigate the predictions of sputtering theory as regards energy distributions of sputtered particles and for the determination of sputtering yields. The possibility that thermal emission may occur during sputtering can also be tested using the proposed model. It is shown that the velocity distribution (either the number density or flux density distribution, depending upon the experimental conditions) of the sputtered particles can be determined using the LIF technique and that this information can be used to obtain a description of the basic sputtering mechanisms. These matters are discussed using the U-atom fluorescence measurements as a basis. The relative sputtering yields for various incident ions on uranium were also measured for the first time using the LIF technique. A surprisingly high fraction of the sputtered uranium atoms were found to occupy the low lying metastable energy levels of U(I). The population of the sputtered metastable atoms were found approximately to obey a Boltzman distribution with an effective temperature of 920 +- 1000K. 41 references

  8. Account of cascade formation depth during sputtering

    International Nuclear Information System (INIS)

    Cascade theory of sputtering is considered. It is suggested to take account of the fact that cascade in a solid forms at a certain depth. This results in decreasing a sputtered particle yield and in changing the form of angular distributions. Angular distributions of sputtered particles were calculated for plane and spherical potential barriers. It was demonstrated that account of cascade formation depth enabled to describe the experiment much better as compared to standard cascade theories. 9 refs.; 13 figs.; 2 tabs

  9. Disorder-free sputtering method on graphene

    Directory of Open Access Journals (Sweden)

    Xue Peng Qiu

    2012-09-01

    Full Text Available Deposition of various materials onto graphene without causing any disorder is highly desirable for graphene applications. Especially, sputtering is a versatile technique to deposit various metals and insulators for spintronics, and indium tin oxide to make transparent devices. However, the sputtering process causes damage to graphene because of high energy sputtered atoms. By flipping the substrate and using a high Ar pressure, we demonstrate that the level of damage to graphene can be reduced or eliminated in dc, rf, and reactive sputtering processes.

  10. Kinetic Behavior of LiFePO4/C Thin Film Cathode Material for Lithium-Ion Batteries

    OpenAIRE

    Kucinskis, G; Bajārs, G; Kleperis, J.; Smits, J.

    2010-01-01

    LiFePO4 was prepared in a solid state synthesis with various levels of carbon content. LiFePO4/C thin films were obtained via magnetron sputtering. The surface morphology and structure was examined. Electrochemical properties of LiFePO4/C were studied, by using cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. Thin films acquired show a potential use as a cathode in lithium ion batteries, displaying charge capacity up to 34 mAh g-1.

  11. Characterization of magnetron co-sputtered W-doped C-based films

    OpenAIRE

    Silva, C. W. Moura e; Branco, J. R. T.; Cavaleiro, A

    2006-01-01

    In this paper, W-doped C-based coatings were deposited on steel and silicon substrates by RF magnetron sputtering, using W and C targets, varying the cathode power applied to the W target and the substrate bias. The chemical composition was varied by placing the substrates in a row facing the C and W targets. W content in the films increased from 1 to 2 at.% over the C target to ~ 73 at.% over the W target. The coatings with W content lower than ~ 12 at.% and ~ 23 at.%, for biased and unbiase...

  12. Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaev, A. G.; Vizir, A. V.; Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Frolova, V. P. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Oks, E. M. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation)

    2016-02-15

    Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereas for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%.

  13. Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

    International Nuclear Information System (INIS)

    Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereas for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%

  14. Graphene: the ultimately thin sputtering shield

    Science.gov (United States)

    Herbig, Charlotte; Michely, Thomas

    2016-06-01

    Scanning tunneling microscopy methods are applied to investigate the potential of monolayer graphene as a sputtering shield for the underlying metal substrate. To visualize the effect, a bare and a graphene protected Ir(111) surface are irradiated with 500 eV Xe+, as well as 200 eV Xe+ and Ar+ ions, all at 1000 K. By quantitatively evaluating the sputtered material from the surface vacancy island area, we find a drastic decrease in metal sputtering for the graphene protected surface. It is demonstrated that efficient sputter protection relies on self-repair of the ion damage in graphene, which takes place efficiently in the temperature range of chemical vapor deposition growth. Based on the generality of the underlying principles of ion damage, graphene self-repair, and graphene growth, we speculate that efficient sputter protection is possible for a broad range of metals and alloys.

  15. Hydrogen-ion sputtering of borated graphite

    International Nuclear Information System (INIS)

    The development and choice of material for the first wall and other energy-stressed parts of the discharge chamber are an important aspect of fusion reactor construction. In particular, carbon-graphite materials are proposed for making limiters and protective shields of the first wall and receiving plates of diverter devices. Sputtering under ion bombardment is one of the main mechanisms of material erosion; in addition, in the case of carbon-graphite materials chemical sputtering also occurs as a result of the formation of highly volatile hydrocarbon compounds during the reaction with ions of hydrogen isotopes. Sputtering MPG carbon-graphite materials and USB-15 carbon-fiber-reinforced glass ceramic has been well studied and experimental data have been obtained on the coefficients of physical and chemical sputtering. It has been determined that hydrogen-ion sputtering of USB-15 in the range from room temperature to 1070 K is less than that of MPG-8 graphite a factor of 2-10. Bulk doping of graphite with boron substantially reduces chemical sputtering. Since processes in the surface layers are crucially important in sputtering, the possibility of reducing chemical sputtering by surface boration of carbon-graphite materials has been explored. The objective of this work was to continue the experimental investigation to determine the physical processes of sputtering of surface-borated graphite under hydrogen-ion bombardment in the temperature range corresponding to maximum chemical sputtering. Surface boration of MPG-8 and USB-15 samples was carried out by vapor-phase isothermal deposition mediated by gaseous iodine at 1223 K for 4 h (the sample was placed in a pure boron stock). The mass transfer during the vapor-phase deposition is based on the difference of the chemical potentials of iodine and carbon under isothermal conditions. The samples of the initial and borated carbon-graphite materials irradiated with a poly-energetic beam of hydrogen ions

  16. Understanding deposition rate loss in high power impulse magnetron sputtering: I. Ionization-driven electric fields

    International Nuclear Information System (INIS)

    The lower deposition rate for high power impulse magnetron sputtering (HiPIMS) compared with direct current magnetron sputtering for the same average power is often reported as a drawback. The often invoked reason is back-attraction of ionized sputtered material to the target due to a substantial negative potential profile, sometimes called an extended presheath, from the location of ionization toward the cathode. Recent studies in HiPIMS devices, using floating-emitting and swept-Langmuir probes, show that such extended potential profiles do exist, and that the electric fields Ez directed toward the target can be strong enough to seriously reduce ion transport to the substrate. However, they also show that the potential drops involved can vary by up to an order of magnitude from case to case. There is a clear need to understand the underlying mechanisms and identify the key discharge variables that can be used for minimizing the back-attraction. We here present a combined theoretical and experimental analysis of the problem of electric fields Ez in the ionization region part of HiPIMS discharges, and their effect on the transport of ionized sputtered material. In particular, we have investigated the possibility of a ‘sweet spot’ in parameter space in which the back-attraction of ionized sputtered material is low. It is concluded that a sweet spot might possibly exist for some carefully optimized discharges, but probably in a rather narrow window of parameters. As a measure of how far a discharge is from such a window, a Townsend product ΠTownsend is proposed. A parametric analysis of ΠTownsend shows that the search for a sweet spot is complicated by the fact that contradictory demands appear for several of the externally controllable parameters such as high/low working gas pressure, short/long pulse length, high/low pulse power and high/low magnetic field strength. (paper)

  17. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

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

  18. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

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

  19. Modeling of life deterioration by ion bombardment of a dispenser cathode coated with an Ir/W film

    Science.gov (United States)

    Higuchi, Toshiharu; Yamamoto, Shigehiko; Kudo, Hiroshi; Murata, Hirotaka

    2002-11-01

    We have developed the calculation method for ion bombardment traces. When an M type dispenser cathode is operated in a cathode ray tube (CRT), the surface coating film is subjected to ion bombardment due to ionized residual gas. With long-time use, the coating film is dissipated and a change to an S type occurs. This occurrence of an S type causes a deterioration of emission and focus characteristics. A method for calculating the life time dependency of the shape of ion bombardment traces using the degree of vacuum in the tube, the grid voltage, and the cathode current was studied. The calculated results and measured results were in close agreement. As a result, it was confirmed that modeling is possible using (1) an electron and ion beam trajectory calculation program, and (2) formulas for calculating the ionization cross-section and sputtering yield.

  20. Hollow cathode arc: effect of the cathode material on the internal plasma

    International Nuclear Information System (INIS)

    In discharges with hollow cathodes functioning in the arc regime, the cathode emits thermionic electrons which ionize the gas. To reduce the electrical power consumed by these discharges, cathodes made of thoriated tungsten and lathanum hexaboride have been used. The parameters of the plasma generated into the cathode have been measured with electrostatic probes. (Auth.)

  1. Mechanistic Enhancement of SOFC Cathode Durability

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-01

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

  2. He-CuII hollow cathode laser in buffer gas pressures in the range of 6 to 100 mBar

    International Nuclear Information System (INIS)

    We report measurements of the discharge and laser output from a quadrupolar He-CuII hollow cathode laser excited with a quasi continuous discharge. Operating voltages of about 150 V and threshold currents of 8.5 A in a 20 cm length discharge produced lasing on the 780.8 nm line on a pressure range from 6 mBar to 100 mBar of pure He. The quadrupolar geometry gives the combined effects of a transversal discharge while producing the metal ion vapor through the hollow cathode sputtering, producing laser action on a wider range of pressures than other previous hollow cathode designs. The laser output is found to depend linearly with the cathode current. (Author)

  3. Carbon Nanotube Bundle Array Cold Cathodes for THz Vacuum Tube Sources

    Science.gov (United States)

    Manohara, Harish M.; Toda, Risaku; Lin, Robert H.; Liao, Anna; Bronikowski, Michael J.; Siegel, Peter H.

    2009-12-01

    We present high performance cold cathodes composed of arrays of carbon nanotube bundles that routinely produce > 15 A/cm2 at applied fields of 5 to 8 V/µm without any beam focusing. They have exhibited robust operation in poor vacuums of 10-6 to 10-4 Torr- a typically achievable range inside hermetically sealed microcavities. A new double-SOI process was developed to monolithically integrate a gate and additional beam tailoring electrodes. The ability to design the electrodes for specific requirements makes carbon nanotube field emission sources extremely flexible. The lifetime of these cathodes is found to be affected by two effects: a gradual decay of emission due to anode sputtering, and catastrophic failure because of dislodging of CNT bundles at high fields ( > 10 V/µm).

  4. Sputtering erosion in ion and plasma thrusters

    Science.gov (United States)

    Ray, Pradosh K.

    1995-08-01

    An experimental set-up to measure low-energy (below 1 keV) sputtering of materials is described. The materials to be bombarded represent ion thruster components as well as insulators used in the stationary plasma thruster. The sputtering takes place in a 9 inch diameter spherical vacuum chamber. Ions of argon, krypton and xenon are used to bombard the target materials. The sputtered neutral atoms are detected by a secondary neutral mass spectrometer (SNMS). Samples of copper, nickel, aluminum, silver and molybdenum are being sputtered initially to calibrate the spectrometer. The base pressure of the chamber is approximately 2 x 10(exp -9) Torr. the primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a size approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and at 90 deg angle to the primary ion beam direction. The ion beam impinges on the target at 45 deg. For sputtering of insulators, charge neutralization is performed by flooding the sample with electrons generated from an electron gun. Preliminary sputtering results, methods of calculating the instrument response function of the spectrometer and the relative sensitivity factors of the sputtered elements will be discussed.

  5. Sputtering properties of redeposited graphite surfaces

    International Nuclear Information System (INIS)

    Sputtering yields for carbon redeposited films, put down in the presence of high neutral hydrogen and helium background concentrations, have been measured. The data were obtained using the ion-surface interaction system (ISIS) which is an ion beam sputtering system capable of creating redeposited films and measuring sputtering yields. Yields were determined by calibrated collection of a portion of the sputtered material onto a quartz-crystal-microbalance. Incident ion beam energies ranged from 100 eV up to 10 keV. Sputtering yields for hydrogen and helium bombardment of redeposited films created in ISIS from targets of Union Carbide ATJ graphite are reported. In addition, yields obtained from ISIS proton and deuteron bombardment of Poco AXF-5Q graphite surfaces previously modified in PISCES are also presented. Measurements of sputtering yields from pristine, bulk samples are reported for comparison. Hydrogen sputtering yields from redeposited films generated in ISIS are 2.5 times higher than those of pristine ATJ at an incident energy of 100 eV. Above 200 eV, the hydrogen yields are a factor of 1.4 higher for the redeposited material. Helium yields are 34 times greater for redeposited films at 100 eV and remain as much as 10 times greater above 500 eV. Curve-fits to the data, obtained by incorporating an effective surface binding energy for the redeposited film into a semi-empirical yield expression, are also presented. (orig.)

  6. Sputtering of indium under polyatomic ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Samartsev, A.V.

    2004-10-01

    The main goal of the present study is the investigation of the sputtering of neutral particles from a metal surface under atomic and polyatomic ion bombardment using secondary neutral time-of-flight mass spectrometry (ToF SNMS). For postionization of neutral species, UV laser irradiation with wavelength 193 nm was utilized. For generation of polyatomic projectiles, a negatives sputter cesium ion source suitable for To F SNMS setup was developed and built. The ion source delivers negatively charged Au{sub m}{sup -} (m=1/5) and AuCs{sub 2} polyatomic ions produced from a gold sputter target bombarded by positive Cs{sup +} ions. Mass separation of primary projectiles in the ion source is performed by a built-in compact Wien filter allowing to separate heavy ions in the energy range of several keV. In the experiment, an indium surface was bombarded by Au{sub m}{sup -} (m=1/5) projectiles with total impact energy of 5 and 10 keV. The obtained mass distributions of sputtered indium species reveal that the partial yields of sputtered clusters increase under polyatomic ion bombardment. It is shown that the enhancement in total sputtering yield per constituent atom of the projectile ion is non-additively enhanced in the case of diatomic ion bombardment in comparison with monoatomic projectile ions impinging at the same velocity. The enhancement of partial yields observed for sputtered clusters is found to increase with increasing cluster size, reaching a factor fo several ten for the largest detected cluster. Apart from sputtering yields, kinetic energy distributions (KED) of sputtered neutral indium atoms ejected under mono- and polyatomic projectile ion bombardment were measured. (orig.)

  7. Ion beam sputter implantation method

    International Nuclear Information System (INIS)

    By means of ion beam atomizing or sputtering an integrally composed coating, the composition of which continuously changes from 100% of the substrate to 100% of the coating, can be surfaced on a substrate (e.g. molten quartz on plastic lenses). In order to do this in the facility there is directed a primary beam of accelerated noble gas ions on a target from the group of the following materials: SiO2, Al2O3, Corning Glass 7070, Corning Glass 7740 or borosilicate glass. The particles leaving the target are directed on the substrate by means of an acceleration potential of up to 10 KV. There may, however, be coated also metal layers (Ni, Co) on a mylar film resulting in a semireflecting metal film. (RW)

  8. Modeling and analysis of surface roughness effects on sputtering, reflection, and sputtered particle transport

    International Nuclear Information System (INIS)

    The microstructure of the redeposited surface in tokamaks may affect sputtering and reflection properties and subsequent particle transport. This subject has been studied numerically using coupled models/codes for near-surface plasma particle kinetic transport (WBC code) and rough surface sputtering (fractal-TRIM). The coupled codes provide an overall Monte Carlo calculation of the sputtering cascade resulting from an initial flux of hydrogen ions. Beryllium, carbon, and tungsten surfaces are analyzed for typical high recycling, oblique magnetic field, divertor conditions. Significant variations in computed sputtering rates are found with surface roughness. Beryllium exhibits high D-T and self-sputtering coefficients for the plasma regime studied (Te = 30-75 eV). Carbon and tungsten sputtering is significantly lower. 9 refs., 6 figs., 1 tab

  9. Composition of sputtered material from CuNi alloy during Xe + ion sputtering at elevated temperatures

    Science.gov (United States)

    Sekine, Shigeyuki; Shimizu, Hazime; Ichimura, Singo

    1995-04-01

    Polycrystalline CuNi alloys were sputtered by 3 kV Xe + ions at elevated temperatures to analyze the ion-beam-induced diffusion. The time evolution of the composition of the sputtered materials from the start of the sputtering was measured by TOF-SNMS (time-of-flight sputtered neutral mass spectrometry). During removal of the Gibbsian segregation layer of copper, the sputtered flux consisted of almost only copper atoms. Then, the copper content gradually decreased due to the formation of a sputter-induced copper-depleted surface layer, and reached an almost steady state with still higher copper content than the bulk composition. From the temperature dependence of the composition at the quasi-steady state the activation energy of copper transportation through a high diffusivity path was derived to be 54 kJ mol -1 (0.56 eV). The high diffusivity path was assigned to copper diffusion through grain boundaries.

  10. Cathodic protection to control microbiologically influenced corrosion

    International Nuclear Information System (INIS)

    Information about the cathodic protection performance in environments with microbiologically influenced corrosion (MIC) effects is very fragmented and often contradictory. Not enough is known about the microbial effects on cathodic protection effectiveness, criteria, calcareous deposits, corrosion rates and possible hydrogen embrittlement of titanium and some stainless steel condenser tubes. This paper presents a review of cathodic protection systems, describes several examples of cathodic protection in environments with MIC effects and provides preliminary conclusions about cathodic protection design parameters, criteria and effectiveness in MIC environments. 30 refs

  11. Synopsis of Cathode No.4 Activation

    International Nuclear Information System (INIS)

    The purpose of this report is to describe the activation of the fourth cathode installed in the DARHT-II Injector. Appendices have been used so that an extensive amount of data could be included without danger of obscuring important information contained in the body of the report. The cathode was a 612 M type cathode purchased from Spectra-Mat. Section II describes the handling and installation of the cathode. Section III is a narrative of the activation based on information located in the Control Room Log Book supplemented with time plots of pertinent operating parameters. Activation of the cathode was performed in accordance with the procedure listed in Appendix A. The following sections provide more details on the total pressure and constituent partial pressures in the vacuum vessel, cathode heater power/filament current, and cathode temperature

  12. Hybrid microwave oscillators with a virtual cathode

    International Nuclear Information System (INIS)

    A review is given of the developments and theoretical investigations of a fundamentally new class of microwave devices, namely, hybrid microwave oscillators with a virtual cathode, which combine the useful properties of virtual cathodes with the advantages of those traditional microwave oscillators that operate with subcritical-current beams and have a high efficiency in generating ultrarelativistic electron beams. Among such devices are the following: a hybrid diffractional microwave oscillator with a virtual cathode, a hybrid gyro-device with a virtual cathode, a hybrid beam-plasma vircator, a hybrid gyrocon with a virtual cathode, a hybrid Cherenkov oscillator with a virtual cathode, a hybrid microwave oscillator of the 'vircator + traveling-wave tube' type, an original two-beam tube with a virtual cathode, and a klystron-like vircator

  13. MoO3 Cathodes for High-Temperature Lithium Thin-Film Cells

    Science.gov (United States)

    West, William; Whitacre, Jay

    2007-01-01

    MoO3 has shown promise as a cathode material that can extend the upper limit of operating temperature of rechargeable lithium thin-film electrochemical cells. Cells of this type are undergoing development for use as energy sources in cellular telephones, wireless medical sensors, and other, similarly sized portable electronic products. The LiCoO2 and LiMn2O4 cathodes heretofore used in these cells exhibit outstanding cycle lives (of the order of hundreds of thousands of cycles) at room temperature, but operation at higher temperatures reduces their cycle lives substantially: for example, at a temperature of 150 C, cells containing LiCoO2 cathodes lose half their capacities in 100 charge/discharge cycles. The superiority of MoO3 as a cathode material was demonstrated in experiments on lithium thin-film cells fabricated on glass slides. Each cell included a layer of Ti (for adhesion to the glass slide), a patterned layer of Pt that served as a cathode current collector, a cathode layer of MoO3, a solid electrolyte layer of Li3.3 PO3.8 N0.22 ("LiPON"), and an anode layer of Li. All the layers were deposited by magnetron sputtering except for the Li layer, which was deposited by thermal evaporation. These cells, along with similar ones containing LiCoO2 cathodes, were subjected to several tests, including measurements of specific capacity in charge/discharge cycling at a temperature of 150 C. The results of these measurements, plotted in the figure, showed that whereas specific capacity of the cells containing LiCoO2 cathodes faded to about half its initial value after only 100 cycles, the specific capacity of the cells containing the MoO3 cathodes faded only slightly during the first few hundred cycles and thereafter not only recovered to its initial value but continued to increase up to at least 5,500 cycles.

  14. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2002-03-31

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

  15. Large Area Sputter Coating on Glass

    Science.gov (United States)

    Katayama, Yoshihito

    Large glass has been used for commercial buildings, housings and vehicles for many years. Glass size for flat displays is getting larger and larger. The glass for the 8th generation is more than 5 m2 in area. Demand of the large glass is increasing not only in these markets but also in a solar cell market growing drastically. Therefore, large area coating is demanded to plus something else on glass more than ever. Sputtering and pyrolysis are the major coating methods on large glass today. Sputtering process is particularly popular because it can deposit a wide variety of materials in good coating uniformity on the glass. This paper describes typical industrial sputtering system and recent progress in sputtering technology. It also shows typical coated glass products in architectural, automotive and display fields and comments on their functions, film stacks and so on.

  16. Physical sputtering code for fusion applications

    International Nuclear Information System (INIS)

    A computer code, DSPUT, has been developed to compute the physical sputtering yields for various plasma particles incident on candidate fusion-reactor first-wall materials. The code, which incorporates the energy and angular-dependence of the sputtering yield, treats both high- and low-Z incident particles bombarding high- and low-Z wall materials. The physical sputtering yield is expressed in terms of the atomic and mass numbers of the incident and target atoms, the surface binding energy of the wall materials, and the incident angle and energy of the particle. An auxiliary code has been written to provide sputtering yields for a Maxwellian-averaged incident particle flux. The code DSPUT has been used as part of a Monte Carlo code for analyzing plasma-wall interactions

  17. Chemically enhanced self-sputtering of carbon

    International Nuclear Information System (INIS)

    New results obtained for graphite self-sputtering, in the presence of thermal atomic hydrogen, show that Chemically Enhanced Self-Sputtering (CES) can exceed unity erosion yield even at normal angles of incidence. CES yields were found to depend on the ΦC+/ΦHo flux ratio and graphite temperature, with peak erosion occurring at about 800K. No dependence on angle of incidence was observed

  18. Sputtering yield measurements on single crystal cobalt

    International Nuclear Information System (INIS)

    Single crystals of cobalt have been bombarded with 80 keV A+ ions in the direction of the h.c.p. structure and in the direction of the f.c.c. structure. The sputtering yields, measured by the weight loss method, depend on the crystal structure, and damage, introduced by the ion bombardment, is shown to play a significant role in the explanation of the measured sputtering yields. (Auth.)

  19. Heavy particle transport in sputtering systems

    Science.gov (United States)

    Trieschmann, Jan

    2015-09-01

    This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

  20. Sputtering of sodium on the planet Mercury

    Science.gov (United States)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  1. Laser-induced fluorescence monitoring of the gas phase in a glow discharge during reactive sputtering of vanadium

    Science.gov (United States)

    Khvostikov, V. A.; Grazhulene, S. S.; Burmii, Zh. P.; Marchenko, V. A.

    2011-11-01

    Processes in the gas phase of a glow discharge during diode and magnetron reactive sputtering of vanadium in an Ar-O2 atmosphere have been investigated by laser-induced fluorescence (LIF) as a function of the parameters of the glow discharge and the composition of the atmosphere. The intensity of the fluorescence spectra increased by 1.5-2.0 orders of magnitude in the magnetron sputtering process compared with that of diode sputtering. Under continuous sputtering conditions, the dependences of the intensities and relative compositions of the fluorescence spectra on the discharge parameters (discharge voltage and current) have been investigated. In pulsed mode of the glow discharge, the dynamics of changes in the spectra have been studied versus variations in the discharge duration and the lag time for recording the fluorescence signal. The dependence of the spectral line intensities on the partial pressure of oxygen has been found for vanadium and its oxide. The cathode surface at pressures of 0.03-0.04 Pa was shown to convert to the oxidized state.

  2. Energetic deposition of metal ions: Observation of self-sputtering and limited sticking for off-normal angles of incidence

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hongchen; Anders, Andre

    2009-09-15

    The deposition of films under normal and off-normal angle of incidence has been investigated to show the relevance of non-sticking of and self-sputtering by energetic ions, leading to the formation of neutral atoms. The flow of energetic ions was obtained using a filtered cathodic arc system in high vacuum and therefore the ion flux had a broad energy distribution of typically 50-100 eV per ion. The range of materials included Cu, Ag, Au, Ti, and Ni. Consistent with molecular dynamics simulations published in the literature, the experiments show, for all materials, that the combined effects of non-sticking and self-sputtering are very significant, especially for large off-normal angles. Modest heating and intentional introduction of oxygen background affect the results.

  3. Lithium phosphorus oxynitride solid-state thin-film electrolyte deposited and modified by bias sputtering and low temperature annealing

    International Nuclear Information System (INIS)

    Amorphous lithium phosphorus oxynitride (LiPON) solid-state thin-film electrolyte has been deposited and characterized. The thin films were prepared by rf magnetron sputtering under various substrate biases. By fabricating under different substrate biases and applying low temperature annealing (473 K), the properties of the LiPON thin-film electrolytes and the electrolyte/cathode interfaces were modified. The ionic conductivity as high as 9.4x10-4 S m-1 can be obtained by depositing at optimal bias. The performances of the consequently fabricated SnO2/LiPON/LiMn2O4 all-solid-state lithium ion thin-film batteries were improved using the bias sputtering technique, due to the enhanced the ionic conductivity and uniform interface.

  4. Lithium phosphorus oxynitride solid-state thin-film electrolyte deposited and modified by bias sputtering and low temperature annealing

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, K.-F.; Chen, C. C.; Lin, K. M.; Lo, C. C.; Lin, H. C.; Ho, W.-H.; Jiang, C. S. [Department of Materials Science and Engineering, Feng Chia University, 100 Wen Hua Road, Taichung, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Taiwan Textile Research Institute, Taipei County, Taiwan (China)

    2010-07-15

    Amorphous lithium phosphorus oxynitride (LiPON) solid-state thin-film electrolyte has been deposited and characterized. The thin films were prepared by rf magnetron sputtering under various substrate biases. By fabricating under different substrate biases and applying low temperature annealing (473 K), the properties of the LiPON thin-film electrolytes and the electrolyte/cathode interfaces were modified. The ionic conductivity as high as 9.4x10{sup -4} S m{sup -1} can be obtained by depositing at optimal bias. The performances of the consequently fabricated SnO{sub 2}/LiPON/LiMn{sub 2}O{sub 4} all-solid-state lithium ion thin-film batteries were improved using the bias sputtering technique, due to the enhanced the ionic conductivity and uniform interface.

  5. Radio frequency plasma processing effects on the emission characteristics of a MeV electron beam cathode

    International Nuclear Information System (INIS)

    Experiments have proven that surface contaminants on the cathode of an electron beam diode influence electron emission current and impedance collapse. This letter reports on an investigation to reduce parasitic cathode current loss and to increase high voltage hold off capabilities by reactive sputter cleaning of contaminants. Experiments have characterized effective radio frequency (rf) plasma processing protocols for high voltage anode endash cathode (A endash K) gaps using a two-stage argon/oxygen and argon rf plasma discharge. Time-resolved optical emission spectroscopy measures contaminant (hydrogen) and bulk cathode (aluminum) plasma emission versus transported axial electron beam current turn on. Experiments were performed at accelerator parameters: V=-0.7 to -1.1 ampersand hthinsp;MV, I(diode)=3 endash 30 ampersand hthinsp;kA, and pulse length=0.4 endash 1.0 ampersand hthinsp;μs. Experiments using a two-stage low power (100 W) argon/oxygen rf discharge followed by a higher power (200 W) pure argon rf discharge yielded an increase in cathode turn-on voltage required for axial current emission from 662±174 ampersand hthinsp;kV to 981±97 ampersand hthinsp;kV. The turn-on time of axial current was increased from 100±22 to 175±42 ampersand hthinsp;ns. copyright 1999 American Institute of Physics

  6. Sputtered coatings for microfluidic applications

    International Nuclear Information System (INIS)

    Magnetron sputter-deposited features and coatings are finding a broad range of uses in microfluidic devices being developed at the Pacific Northwest National Laboratory. Such features are routinely incorporated into multilayer laminated microfluidic components where specific functionality is required, and where other methods for producing these features have been deemed unacceptable. Applications include electrochemical sensors, heaters and temperature probes, electrical leads and insulation layers, piezoelectric actuators and transducers, and chemical modification of surfaces. Small features, such as those required for the production of microsensor electrodes or miniature resistive heaters on microfluidic chips, were patterned using standard lithographic methods, or with masks produced by laser micromachining processes. Thin-film piezoelectric materials such as aluminum nitride have been deposited at low temperatures for use with temperature sensitive materials. Use of the coating technology and its application in the fabrication of specific microfluidic devices, including a groundwater sensor, miniature piezoelectric ultrasonic transducers and actuators, a polymerase chain reaction thermal cycler, and a microchannel flow diagnostic device, are discussed. Technical issues associated with these coatings, such as adhesion, chemical resistance, and surface defects are also addressed. (c) 2000 American Vacuum Society

  7. Measuring the energy flux at the substrate position during magnetron sputter deposition processes

    Energy Technology Data Exchange (ETDEWEB)

    Cormier, P.-A.; Thomann, A.-L.; Dussart, R.; Semmar, N.; Mathias, J. [GREMI, Universite d' Orleans, 14 rue d' Issoudun, B.P. 6744, 45067 Orleans Cedex 2 (France); Balhamri, A. [Laboratoire de Chimie des Interactions Plasma-Surface, Universite de Mons, 23 Place du Parc, 7000 Mons (Belgium); Laboratoire Rayonnement and Matiere: Laboratoire d' Optique Appliquee et Transfert d' Energie (LOPATE), Faculte des Sciences et Techniques de Settat, Universite Hassan 1, B.P. 461 Settat (Morocco); Snyders, R. [Laboratoire de Chimie des Interactions Plasma-Surface, Universite de Mons, 23 Place du Parc, 7000 Mons (Belgium); Materia Nova R and D Center, Avenue Copernic 1, Mons (Belgium); Konstantinidis, S. [Laboratoire de Chimie des Interactions Plasma-Surface, Universite de Mons, 23 Place du Parc, 7000 Mons (Belgium)

    2013-01-07

    In this work, the energetic conditions at the substrate were investigated in dc magnetron sputtering (DCMS), pulsed dc magnetron sputtering (pDCMS), and high power impulse magnetron sputtering (HiPIMS) discharges by means of an energy flux diagnostic based on a thermopile sensor, the probe being set at the substrate position. Measurements were performed in front of a titanium target for a highly unbalanced magnetic field configuration. The average power was always kept to 400 W and the probe was at the floating potential. Variation of the energy flux against the pulse peak power in HiPIMS was first investigated. It was demonstrated that the energy per deposited titanium atom is the highest for short pulses (5 {mu}s) high pulse peak power (39 kW), as in this case, the ion production is efficient and the deposition rate is reduced by self-sputtering. As the argon pressure is increased, the energy deposition is reduced as the probability of scattering in the gas phase is increased. In the case of the HiPIMS discharge run at moderate peak power density (10 kW), the energy per deposited atom was found to be lower than the one measured for DCMS and pDCMS discharges. In these conditions, the HiPIMS discharge could be characterized as soft and close to a pulsed DCMS discharge run at very low duty cycle. For the sake of comparison, measurements were also carried out in DCMS mode with a balanced magnetron cathode, in the same working conditions of pressure and power. The energy flux at the substrate is significantly increased as the discharge is generated in an unbalanced field.

  8. Low platinum, high limiting current density of the PEMFC (proton exchange membrane fuel cell) based on multilayer cathode catalyst approach

    International Nuclear Information System (INIS)

    Novel multilayer cathode electrodes structures for PEMFC (proton exchange membrane fuel cell) based on sputtering technique were developed to provide high performance with low loading Pt of 0.05 mg/cm² compared to the standard MEA (membrane electrode assembly) cathode (∼0.2–0.3 mg/cm²). Different configurations of cathode catalyst layer were made by altering Pt and CN (Carbon–Nafion) ink carefully prepared on gas diffusion layer containing MPL (micro porous layer). The performances of PEMFC containing the multilayer electrodes were compared based on their measured polarization curves. Higher limiting current densities were achieved compared to standard MEA with platinum loading of 0.2 mg/cm² both at the cathode and the anode sides. Limiting current densities over 1.1 A/cm2, 1.2 A/cm2 and 1.4 A/cm2 were reached whereas maximum powers were in the range of 500 mW/cm² at 600 mW/cm². The good performances obtained can be due to the structural improvement which has contributed to a better catalyst utilization compared to conventional methods. A CN loading inferior to 0.24 mg/cm² between each layer is preferred for multilayer electrode. - Highlights: • Multilayer cathode of PEM fuel cell. • Enhanced performances with carbon–Nafion layer of PEM fuel cell. • Effect of the number of Pt sputtered layers on cell performance. • Increased power densities achieved. • Increased limiting current densities achieved

  9. Computer simulation of sputtering of graphite target in magnetron sputtering device with two zones of erosion

    Directory of Open Access Journals (Sweden)

    Bogdanov R.V.

    2015-03-01

    Full Text Available A computer simulation program for discharge in a magnetron sputtering device with two erosion zones was developed. Basic laws of the graphite target sputtering process and transport of sputtered material to the substrate were taken into account in the Monte Carlo code. The results of computer simulation for radial distributions of density and energy flux of carbon atoms on the substrate (at different values of discharge current and pressure of the working gas confirmed the possibility of obtaining qualitative homogeneous films using this magnetron sputtering device. Also the discharge modes were determined for this magnetron sputtering device, in which it was possible to obtain such energy and density of carbon atoms fluxes, which were suitable for deposition of carbon films containing carbon nanotubes and other nanoparticles.

  10. Optical properties of diamond like carbon films containing copper, grown by high power pulsed magnetron sputtering and direct current magnetron sputtering: Structure and composition effects

    Energy Technology Data Exchange (ETDEWEB)

    Meškinis, Š., E-mail: sarunas.meskinis@ktu.lt; Čiegis, A.; Vasiliauskas, A.; Šlapikas, K.; Tamulevičius, T.; Tamulevičienė, A.; Tamulevičius, S.

    2015-04-30

    In the present study chemical composition, structure and optical properties of hydrogenated diamond like carbon films containing copper (DLC:Cu films) deposited by reactive magnetron sputtering were studied. Different modes of deposition — direct current (DC) sputtering and high power pulsed magnetron sputtering (HIPIMS) as well as two configurations of the magnetron magnetic field (balanced and unbalanced) were applied. X-ray diffractometry, Raman scattering spectroscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy were used to study the structure and composition of the films. It was shown that by using HIPIMS mode contamination of the cathode during the deposition of DLC:Cu films can be suppressed. In all cases oxygen atomic concentration in the films was in 5–10 at.% range and it increased with the copper atomic concentration. The highest oxygen content was observed in the films deposited employing low ion/neutral ratio balanced DC magnetron sputtering process. According to the analysis of the parameters of Raman scattering spectra, sp{sup 3}/sp{sup 2} bond ratio decreased with the increase of Cu atomic concentration in the DLC films. Clear dependence of the extinction, absorbance and reflectance spectra on copper atomic concentration in the films was observed independently of the method of deposition. Surface plasmon resonance effect was observed only when Cu atomic concentration in DLC:Cu film was at least 15 at.%. The maximum of the surface plasmon resonance peak of the absorbance spectra of DLC:Cu films was in 600–700 nm range and redshifted with the increase of Cu amount. The ratio between the intensities of the plasmonic peak and hydrogenated amorphous carbon related peak at ~ 220 nm both in the extinction and absorbance spectra as well as peak to background ratio of DLC:Cu films increased linearly with Cu amount in the investigated 0–40 at.% range. Reflectance of the plasmonic DLC:Cu films was in 30–50% range that could be

  11. Optical properties of diamond like carbon films containing copper, grown by high power pulsed magnetron sputtering and direct current magnetron sputtering: Structure and composition effects

    International Nuclear Information System (INIS)

    In the present study chemical composition, structure and optical properties of hydrogenated diamond like carbon films containing copper (DLC:Cu films) deposited by reactive magnetron sputtering were studied. Different modes of deposition — direct current (DC) sputtering and high power pulsed magnetron sputtering (HIPIMS) as well as two configurations of the magnetron magnetic field (balanced and unbalanced) were applied. X-ray diffractometry, Raman scattering spectroscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy were used to study the structure and composition of the films. It was shown that by using HIPIMS mode contamination of the cathode during the deposition of DLC:Cu films can be suppressed. In all cases oxygen atomic concentration in the films was in 5–10 at.% range and it increased with the copper atomic concentration. The highest oxygen content was observed in the films deposited employing low ion/neutral ratio balanced DC magnetron sputtering process. According to the analysis of the parameters of Raman scattering spectra, sp3/sp2 bond ratio decreased with the increase of Cu atomic concentration in the DLC films. Clear dependence of the extinction, absorbance and reflectance spectra on copper atomic concentration in the films was observed independently of the method of deposition. Surface plasmon resonance effect was observed only when Cu atomic concentration in DLC:Cu film was at least 15 at.%. The maximum of the surface plasmon resonance peak of the absorbance spectra of DLC:Cu films was in 600–700 nm range and redshifted with the increase of Cu amount. The ratio between the intensities of the plasmonic peak and hydrogenated amorphous carbon related peak at ~ 220 nm both in the extinction and absorbance spectra as well as peak to background ratio of DLC:Cu films increased linearly with Cu amount in the investigated 0–40 at.% range. Reflectance of the plasmonic DLC:Cu films was in 30–50% range that could be important in

  12. Hollow cathode startup using a microplasma discharge

    Science.gov (United States)

    Aston, G.

    1981-01-01

    Attention is given to a microplasma discharge to initiate a hollow cathode discharge for such applications as plasma flow experiments, the electric propulsion of space vehicles, and as a replacement for filament cathodes in neutral beam injector ion sources. The technique results in a cathode that is easy to start, simple in design, and which does not require external RF exciters, inserts or heating elements. Future applications may include ion beam milling and ion implantation.

  13. Oxidation studies of impregnated dispenser cathodes

    International Nuclear Information System (INIS)

    We report on surface studies of the type M and type S impregnated dispenser cathode using synchrotron radiation photoemission spectroscopy. The results indicate the presence of two barium configurations on the room temperature type S surface, probably barium metal and BaO. The room-temperature type M cathode has about a monolayer of barium metal and about a monolayer of tungsten, apparently alloyed to the Os/Ru coating, on the surface. The barium-related features of the type S cathode are extremely sensitive to small oxygen exposures, while the tungsten-related features are more sensitive to oxygen in the type M cathode

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

    Science.gov (United States)

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

    2015-02-01

    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 0 at the target edge. At B 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 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.

  15. Sputtering of Lunar Regolith by Solar Wind Protons and Heavy Ions, and General Aspects of Potential Sputtering

    Science.gov (United States)

    Alnussirat, S. T.; Sabra, M. S.; Barghouty, A. F.; Rickman, Douglas L.; Meyer, F.

    2014-01-01

    New simulation results for the sputtering of lunar soil surface by solar-wind protons and heavy ions will be presented. Previous simulation results showed that the sputtering process has significant effects and plays an important role in changing the surface chemical composition, setting the erosion rate and the sputtering process timescale. In this new work and in light of recent data, we briefly present some theoretical models which have been developed to describe the sputtering process and compare their results with recent calculation to investigate and differentiate the roles and the contributions of potential (or electrodynamic) sputtering from the standard (or kinetic) sputtering.

  16. Magnetron sputtered lithium niobate films

    International Nuclear Information System (INIS)

    The preparation of lithium niobate films on Corning 7059 glass by rf planar magnetron sputtering in an Ar + 40% 02 mixture has been studied at 2 mtorr. Films deposited on unheated substrates became crazed by release of a tensile stress arising from the difference between the expansion coefficient of the glass and the coating. Improvement of surface cleanliness by discharge cleaning or solvent degreasing using iso-propyl alcohol in a Soxhlet extractor enhanced the film/substrate adhesion. This prevented crazing, but the transparent films produced were still under stress. Glass surfaces cleaned sufficiently for high film adhesion had a coefficient of static friction, glass on glass, of greater than of the order of 0.8. A lithium niobate powder target was used because the uneven heating arising from magnetron discharge localization resulted in fracture of single crystal material. Care was taken to remove all water vapour from the discharge atmosphere using liquid nitrogen traps, for without these the coatings produced were optically absorbing, due to oxide reduction, presumably formed by an active hydrogen reaction. The refractive index of the films, as determined from their waveguiding characteristics, was in the region of 2.10-2.20. Trial coatings grown at 380degC and above had indices in the region of 2.19; these high temperature films were also transparent but under tensile stress. The growth rates ranged from 9.5 A min-1 for a substrate temperature of 3800C to 11.5 A min-1 for a substrate temperature of 4700C. (author)

  17. Computer simulation of sputtering: A review

    International Nuclear Information System (INIS)

    In 1986, H. H. Andersen reviewed attempts to understand sputtering by computer simulation and identified several areas where further research was needed: potential energy functions for molecular dynamics (MD) modelling; the role of inelastic effects on sputtering, especially near the target surface; the modelling of surface binding in models based on the binary collision approximation (BCA); aspects of cluster emission in MD models; and angular distributions of sputtered particles. To these may be added kinetic energy distributions of sputtered particles and the relationships between MD and BCA models, as well as the development of intermediate models. Many of these topics are discussed. Recent advances in BCA modelling include the explicit evaluation of the time in strict BCA codes and the development of intermediate codes able to simulate certain many-particle problems realistically. Developments in MD modelling include the wide-spread use of many-body potentials in sputtering calculations, inclusion of realistic electron excitation and electron-phonon interactions, and several studies of cluster ion impacts on solid surfaces

  18. Sputtering of amorphous silicon nitride irradiated with energetic C60 ions: Preferential sputtering and synergy effect between electronic and collisional sputtering

    Science.gov (United States)

    Kitayama, T.; Morita, Y.; Nakajima, K.; Narumi, K.; Saitoh, Y.; Matsuda, M.; Sataka, M.; Toulemonde, M.; Kimura, K.

    2015-12-01

    Amorphous silicon nitride films (thickness 30 nm) deposited on Si(0 0 1) were irradiated with 30-1080 keV C60 and 100 MeV Xe ions to fluences ranging from 2 × 1011 to 1 × 1014 ions/cm2. The composition depth profiles of the irradiated samples were measured using high-resolution Rutherford backscattering spectrometry. The sputtering yields were estimated from the derived composition profiles. Pronounced preferential sputtering of nitrogen was observed in the electronic energy loss regime. In addition, a large synergy effect between the electronic and collisional sputtering was also observed. The sputtering yields were calculated using the unified thermal spike model to understand the observed results. Although the calculated results reproduced the observed total sputtering yields with a lowered sublimation energy, the observed preferential sputtering of nitrogen could not be explained. The present results suggest an additional sputtering mechanism related to the electronic energy loss.

  19. Cathode-follower power amplifier

    International Nuclear Information System (INIS)

    In circular accelerators and particularly in storage rings it is essential that the total impedance, as seen by the beam, be kept below some critical value. A model of the accelerating system was built using a single-ended cathode-follower amplifier driving a ferrite-loaded cavity. The system operated at 234.5 kHz with a peak output voltage of +-10 kV on the gap. The dynamic output impedance, as measured on the gap, was < 15 ohms

  20. Magnetron sputtering of transparent conductive zinc oxide: relation between the sputtering parameters and the electronic properties

    International Nuclear Information System (INIS)

    Magnetron sputtering of transparent conductive oxides (zinc oxide, indium tin oxide, tin oxide) is a promising technique which allows the deposition of films at low temperatures with good optical and electronic properties. A special advantage is the scalability to large areas. The principles underlying magnetron sputtering are reviewed in this paper. The growth process during magnetron sputtering is characterized by the bombardment of the growing film with species from the sputtering target and from the plasma. In addition to sputtered atoms with energies in the eV range, ions from the plasma (mostly argon) and neutral atoms (also argon) reflected at the target hit the growing film. Depending on the energy of these species and on the ion-to-neutral ratio the properties of the films vary. High energies (≥100 eV), which occur mainly at low sputtering pressures lead to damage of the growing film, connected with mechanical stress, small crystallites and bad electrical parameters. Ion assisted growth with low ion energies (below about 50 eV) is advantageous as is a high ion-to-neutral ratio. A compilation of resistivities of magnetron sputtered zinc oxide films yields a limiting resistivity of 2x10-4 Ω cm for polycrystalline films. Based on the correlation between plasma parameters and film properties new search fields are anticipated. (author)

  1. Numerical Study of Hall Thruster Plume and Sputtering Erosion

    Directory of Open Access Journals (Sweden)

    Li Yan

    2012-01-01

    Full Text Available Potential sputtering erosion caused by the interactions between spacecraft and plasma plume of Hall thrusters is a concern for electric propulsion. In this study, calculation model of Hall thruster’s plume and sputtering erosion is presented. The model is based on three dimensional hybrid particle-in-cell and direct simulation Monte Carlo method (PIC/DSMC method which is integrated with plume-wall sputtering yield model. For low-energy heavy-ion sputtering in Hall thruster plume, the Matsunami formula for the normal incidence sputtering yield and the Yamamura angular dependence of sputtering yield are used. The validation of the simulation model is realized through comparing plume results with the measured data. Then, SPT-70’s sputtering erosion on satellite surfaces is assessed and effect of mass flow rate on sputtering erosion is analyzed.

  2. Physical sputtering of metallic systems by charged-particle impact

    International Nuclear Information System (INIS)

    The present paper provides a brief overview of our current understanding of physical sputtering by charged-particle impact, with the emphasis on sputtering of metals and alloys under bombardment with particles that produce knock-on collisions. Fundamental aspects of ion-solid interactions, and recent developments in the study of sputtering of elemental targets and preferential sputtering in multicomponent materials are reviewed. We concentrate only on a few specific topics of sputter emission, including the various properties of the sputtered flux and depth of origin, and on connections between sputtering and other radiation-induced and -enhanced phenomena that modify the near-surface composition of the target. The synergistic effects of these diverse processes in changing the composition of the integrated sputtered-atom flux is described in simple physical terms, using selected examples of recent important progress. 325 refs., 27 figs

  3. Sputtering and mixing of supported nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jiménez-Sáez, J.C., E-mail: jc.jimenez@upm.es [Dept. Física y Química Aplicadas a la Técnica Aeronaútica, ETSIAE, Universidad Politécnica de Madrid (UPM), 28040 Madrid (Spain); Pérez-Martín, A.M.C.; Jiménez-Rodríguez, J.J. [Dept. Física Aplicada III (Electricidad y Electrónica), Facultad de Ciencias Físicas, Universidad Complutense de Madrid (UCM), 28040 Madrid (Spain)

    2013-12-01

    Sputtering and mixing of Co nanoparticles supported in Cu(0 0 1) under 1-keV argon bombardment are studied using molecular-dynamics simulations. Particles of different initial size have been considered. The cluster height decreases exponentially with increasing fluence. In nanoparticles, sputtering yield is significantly enhanced compared to bulk. In fact, the value of this magnitude depends on the cluster height. A theoretical model for sputtering is introduced with acceptable results compared to those obtained by simulation. Discrepancies happen mainly for very small particles. Mixing rate at the interface is quantified; and besides, the influence of border effects for clusters of different initial size is assessed. Mixing rate and border length–surface area ratio for the initial interface show a proportionality relation. The phenomenon of ion-induced burrowing of metallic nanoparticles is analysed.

  4. Electrochemical Behaviour of Sputtering Deposited DLC Films

    Institute of Scientific and Technical Information of China (English)

    LIUErjia; ZENGA; LIULX

    2003-01-01

    Diamondlike carbon (DLC) films were deposited via magnetron sputtering process. The energetic ion hombardment on the surface of growing film is one of the major parameters that control the atom mobility on the flirt1 surface and further the physical and chemical characteristics of the films. In this study, the energy of carbon ions was monitored by changing sputtering powerdensity, and its effect on the electrochemical performance of the films was investigated. For the deposition at a higher sputtering power density, a higher sp3 content in the DLC films was achieved with denser structure and increased film-substrate adhesion. The impedance at the interface of Si substrate/sulfufic acid solution was significantly enhanced, and at the same time higher film resistance, lower capacitance, higher breakdown potential and longer breakdown time were observed, which were related to the significant sp3 content of the DLC films.

  5. Electrochemical Behaviour of Sputtering Deposited DLC Films

    Institute of Scientific and Technical Information of China (English)

    LIU Erjia; ZENG A,LIU L X

    2003-01-01

    Diamondlike carbon (DLC) films were deposited via magnetron sputtering process. The energetic ion bombardment on the surface of growing film is one of the major parameters that control the atom mobility on the film surface and further the physical and chemical characteristics of the films. In this study, the energy of carbon ions was monitored by changing sputtering power density, and its effect on the electrochemical performance of the films was investigated. For the deposition at a higher sputtering power density, a higher sp3 content in the DLC films was achieved with denser structure and increased film-substrate adhesion. The impedance at the interface of Si substrate/sulfuric acid solution was significantly enhanced, and at the same time higher film resistance, lower capacitance, higher breakdown potential and longer breakdown time were observed, which were related to the significant sp3 content of the DLC films.

  6. CME impact on Mercury's sputtered exospheric environment

    Science.gov (United States)

    Pfleger, M.; Lichtenegger, H. I. M.; Lammer, H.; Mura, A.; Wurz, P.; Martin-Fernandez, J. A.

    2013-09-01

    Solar wind and magnetospheric plasma precipitation onto the surface of Mercury triggers the formation of exospheric particle populations by sputtering processes. Numerical modeling of Mercury's magnetosphere has shown that the weak intrinsic magnetic field of the planet is sufficient to prevent the equatorial regions from being impacted by solar wind ions during moderate solar wind conditions. However, intense fluxes of protons are expected to hit the auroral regions, giving rise to the release of surface elements at high latitudes by ion sputtering. During high solar wind dynamic pressure conditions in the case of CME events, the solar wind protons will have access to Mercury's entire dayside surface, which may result in a considerable filling of the exosphere by sputtered surface material.

  7. The sputter generation of negative ion beams

    International Nuclear Information System (INIS)

    A brief review is given of recent progress toward a quantitative understanding of negative ion formation by sputtering from surfaces covered with fractional layers of highly electropositive adsorbates. Practical models developed for estimating changes in work functions Δφ by electropositive adsorbates are described. The secondary negative ion generation process is examined through the use of composite energy/velocity dependent analytical models. These models are used to illustrate the effect of work function on the energy distributions of negative ions sputter ejected from a polycrystalline molybdenum surface covered with fractional layers of cesium. Predictions are also made of the functional dependence of the probability for negative ion formation on cesium coverage. The models predict energy distributions which are in basic disagreement with experimental observations, implying their inappropriateness for describing the sputter negative ion generation process. We have also developed a model for calculating sputter ratios based on the use of simple scaling procedures to bring Sigmund theory into close agreement with experimental observation accounting for the threshold effect. Scaling factors for projectile energies E > 1000 eV are found to be independent of energy while those for projectile energies Eth < E < 1000 eV were found to be energy dependent. In this study, the model and scaling techniques utilized to bring Sigmund theory into agreement with experiment are discussed in detail and several examples provided which illustrate the versatility, accuracy and utility of the model. In the present report, we describe the model and apply it to the case of sputtering a selected number of metals with energetic cesium ions. In particular, we present sputter ratio information for a number of Cs-projectile/metal-target combinations; the targets are bombarded at normal incidence to the surface

  8. Qualitative criterion for atom sputtering angle distributions

    International Nuclear Information System (INIS)

    A model is introduced to explain the shape of atom polar emission angle distributions for monocomponent targets sputtered by normally incident keV - energy ions. Analytical expressions are obtained from the model which make it possible to identify three known kinds of the angle distributions - subcosinus, isotropic and supracosinus, for given ion energies and target-ion pairs. Furthermore the fourth, hybrid false-isotropic distribution is found, which is superposition of supracosinus and subcosinus distributions. The theoretical predictions of the angle distributions shape agree with the numerical modeling for sputtering of carbon and platinum by 0.1-10 keV Ar+ ions

  9. Sputtering of indium using polyatomic projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Samartsev, A.V.; Wucher, A

    2004-06-15

    We have investigated the emission of neutral and charged particles from a polycrystalline indium surface under bombardment with Au, Au{sub 2}, Au{sub 3}, Au{sub 5} and AuCs{sub 2} projectiles with energies between 5 and 10 keV. Sputtered neutral species were postionized by means of saturated single photon ionization, thus characterizing the respective partial sputtering yields. The ionization probability of the emitted species was addressed by measuring the respective secondary ion signals under the same experimental conditions. It is seen that the relative cluster yields are enhanced under polyatomic projectile bombardment, while the ionization probability of In atoms seems to be largely unaffected.

  10. Magnetospheric Sputtering Source of the Moon's Exosphere

    Science.gov (United States)

    Moore, L. E.; Wilson, J. K.; Mendillo, M.

    2002-09-01

    Observations of lunar eclipses over the past decade have revealed that the Moon's transient sodium atmosphere at full Moon is both denser and more extended near equinox than it is near solstice. This fact suggests the presence of a variable magnetospheric source of sodium. An investigation of this source is carried out by modeling combinations of two sources: a constant source from micrometeor sputtering and photon-stimulated desorption, and a variable source (presumably plasma sputtering), which is higher during equinox conditions and lower during solstice conditions.

  11. Collimated Magnetron Sputter Deposition for Mirror Coatings

    DEFF Research Database (Denmark)

    Vickery, A.; Cooper-Jensen, Carsten P.; Christensen, Finn Erland;

    2008-01-01

    At the Danish National Space Center (DNSC), a planar magnetron sputtering chamber has been established as a research and production coating facility for curved X-ray mirrors for hard X-ray optics for astronomical X-ray telescopes. In the following, we present experimental evidence that a collimat......At the Danish National Space Center (DNSC), a planar magnetron sputtering chamber has been established as a research and production coating facility for curved X-ray mirrors for hard X-ray optics for astronomical X-ray telescopes. In the following, we present experimental evidence that a...

  12. Sputtering of dimers off a silicon surface

    Science.gov (United States)

    Nietiadi, Maureen L.; Rosandi, Yudi; Kopnarski, Michael; Urbassek, Herbert M.

    2012-10-01

    We present experimental and molecular-dynamics simulation results of the sputtering of a Si surface by 2 keV Ar ions. Results on both the monomer and dimer distributions are presented. In simulation, these distributions follow a generalized Thompson law with power exponent n=2 and n=3, respectively. The experimental data, obtained via plasma post-ionization in an SNMS (secondary neutral mass spectrometry) apparatus, show good agreement with respect to the dimer fraction, and the relative energy distributions of dimers and monomers. The consequences for the dimer sputtering mechanism are discussed.

  13. Sputtering of dimers off a silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Nietiadi, Maureen L. [Physics Department, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Research Center OPTIMAS, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Rosandi, Yudi [Physics Department, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Research Center OPTIMAS, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Department of Physics, Universitas Padjadjaran, Jatinangor, Sumedang 45363 (Indonesia); Kopnarski, Michael [Physics Department, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Research Center OPTIMAS, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Institut fuer Oberflaechen- und Schichtanalytik IFOS GmbH, Trippstadter Strasse 120, D-67663 Kaiserslautern (Germany); Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.de [Physics Department, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Research Center OPTIMAS, University Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

    2012-10-15

    We present experimental and molecular-dynamics simulation results of the sputtering of a Si surface by 2 keV Ar ions. Results on both the monomer and dimer distributions are presented. In simulation, these distributions follow a generalized Thompson law with power exponent n=2 and n=3, respectively. The experimental data, obtained via plasma post-ionization in an SNMS (secondary neutral mass spectrometry) apparatus, show good agreement with respect to the dimer fraction, and the relative energy distributions of dimers and monomers. The consequences for the dimer sputtering mechanism are discussed.

  14. Hollow cathode lamp-construction aspects

    International Nuclear Information System (INIS)

    The hollow cathode discharge is a source used for absorption and fluorescence atomic spectrophotometry. In this paper various aspect like construction, cleanliness and operation have been described. The life time of the hollow cathode discharge for specific current is about 500 hs. The range of current for the non significant self-absorption of the recommended wavelenght has been determinated. (Author)

  15. Field emission cathode for high power beams

    International Nuclear Information System (INIS)

    Field emission is identified as the mechanism responsible for high current emission (50 A/cm2 at 3000K) from a dispenser-type cathode. This cathode has advantages for high power operation, and should be suitable for practical applications. (author)

  16. Electrochemical properties of Atomic layer deposition processed CeO2 as a protective layer for the molten carbonate fuel cell cathode

    International Nuclear Information System (INIS)

    Highlights: • Nano-structured CeO2-coated Ni by Atomic Layer Deposition, crystalline as-deposited. • Progressive transformation into a complex surface stable in molten carbonates. • Lower Ni solubility with CeO2 protective coating. • Feasibility of CeO2 coating in Molten Carbonate Fuel Cell cathode conditions. - Abstract: In order to increase the lifetime and performance of the molten carbonate fuel cell, it is compulsory to control the corrosion and dissolution of the state of the art porous nickel oxide cathode. A protective coating constituted by more stable oxides appears to be the best approach. Previous research on CeO2 coatings obtained by DC reactive magnetron sputtering to protect the Molten carbonate fuel cell cathode gave promising results but it was necessary to improve the coating adhesion. In this paper Atomic Layer Deposition, producing high quality, homogeneous and conformal layers, was used to obtain thin layers of CeO2 (20 nm and 120 nm) deposited over porous nickel. CeO2-Ni coated samples were tested as cathodes in Li2CO3-K2CO3 (62-38 mol %) eutectic mixture under standard cathode atmosphere (CO2/air 30:70 vol. %). Structural and morphological characterizations of the nickel coated cathode before and after electrochemical tests in the molten carbonate melt are reported together with the Open Circuit Potential evolution all over 230 h for both the bare porous nickel and the CeO2-coated samples

  17. Effects of a low work function cathode on electron beam generation in a hollow cathode discharge

    International Nuclear Information System (INIS)

    Recent simulations reveal that a large contribution to the formation of the hollow cathode discharge comes from secondary electron emission due to ion bombardment of the hollow cathode surface. The simulations suggest that a decrease in work function of the hollow cathode surface will lead to enhanced plasma formation during the initial and latter phases of the discharge. The use of this enhanced plasma to more efficiently generate beams (both ion and electron) was studied. A pulsed hollow cathode discharge was constructed using low work function dispenser cathode material as the hollow cathode. The electron beam characteristics of the discharge were investigated. Other hollow cathodes constructed with various materials (molybdenum, copper) were constructed and the results will be compared. Applications of the new source are discussed

  18. Klystron Amplifier Utilizing Scandate Cathode and Electrostatic Focusing Project

    Data.gov (United States)

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

  19. Physics of thermionic dispenser cathode aging

    Science.gov (United States)

    Longo, R. T.

    2003-11-01

    A dispenser cathode life model (DCLM) was originally published in 1984. More recent life test data have substantiated the basic physics used in the DCLM. However, re-evaluation of the model with this latest data alters the numerical parameters used in the model. The most important modification is the incorporation of the shape factor, α, in the emission equation, so that accurate descriptions of the cathode activity curves (i.e., current versus temperature) can be made as a function of cathode age. The original model was fit only to the cathode current as a function of time for a fixed operating temperature. This revision fits the cathode activity curves as a function of both time and cathode temperature. Variation in cathode current as a function of temperature is quite dependent upon the underlying physics, and gives a better measure of how the internal parameters, such as work function and knee position and knee shape change with time. Knowing these details provides a more accurate measure of how the cathode current at the operating point will change over time. The modification made to the emission equation in this revision incorporates the shape factor, α, which is a single number that describes the shape of the cathode activity curves. The shape factor is found to be dependent on time: The knee softens and rounds with age. Even though the shape factor was originally introduced as an empirical factor, I will present a theoretical model for the shape factor that provides some insight into its physical interpretation. This theory will show that it can be related to the thermodynamics of the emitter surface. The re-evaluation of the DCLM, based on the latest life data, and including the theory for the shape factor yields a longer life expectancy for the M-type dispenser cathode then was predicted by the original more conservative life model. The DCLM matches the observed life data more accurately.

  20. Aluminum oxide sputtering: a new approach to understanding the sputtering process for binary targets

    International Nuclear Information System (INIS)

    The relative abundances of the products Al, Al2O, and AlO sputtered in 15- and 40-kV Ar+ and 15-kV H+ bombardments of aluminum oxide targets (anodized film, polycrystalline disk, sapphire) are functions of the target material and of the nature, flux, and fluence of the ion beam. This finding suggests that, in collisional sputtering, the material's sensitive parameters are the surface binding energies of the sputtered species. These energies are functions of the surface composition present at the moment of a particular sputtering event and should be identified with the partial molar enthalpy of vaporization of a particular species. The aluminum oxide species--Al, Al2O, AlO, Al2O2, AlO2, Al(O2)2, and AlO3--are characterized by matrix isolation spectroscopy aided by O18 isotopic substitution experiments. 12 figures, 4 tables

  1. Construction of superconducting bulk magnet magnetron sputtering apparatus for fabrication of highly reflective optical mirrors

    International Nuclear Information System (INIS)

    We have developed the two-cathode magnetron sputtering apparatus equipped with superconducting permanent magnet to produce Mo/Si multi-layer films, which would potentially serve as a high-quality optical mirror at extreme ultraviolet (EUV) wavelength of 13.5 nm. The best deposition condition was searched by analyzing the structure of the inter-diffusion layer formed in the Mo/Si bi-layer film prepared under different deposition conditions. It was found that (1) Xe gas should be used as inert gas species, (2) its pressure is lower than 4 x 10-2 Pa, (3) a throw distance is longer than 250 mm and (4) discharge voltage around 2 kV. By making full use of these data, we synthesized Mo/Si multi-layer films and analyzed the structure and its effect on the reflectivity. The highest EUV-reflectivity so far obtained is 67% in the normal incident condition

  2. Potential for reactive pulsed-dc magnetron sputtering of nanocomposite VOx microbolometer thin films

    International Nuclear Information System (INIS)

    Vanadium oxide (VOx) thin films were deposited by reactive pulsed-dc sputtering a metallic vanadium target in argon/oxygen mixtures with substrate bias. Hysteretic oxidation of the vanadium target surface was assessed by measuring the average cathode current during deposition. Nonuniform oxidization of the target surface was analyzed by Raman spectroscopy. The VOx film deposition rate, resistivity, and temperature coefficient of resistance were correlated to oxygen to argon ratio, processing pressure, target-to-substrate distance, and oxygen inlet positions. To deposit VOx in the resistivity range of 0.1–10 Ω-cm with good uniformity and process control, lower processing pressure, larger target-to-substrate distance, and oxygen inlet near the substrate are useful

  3. CrN films deposited by ion source-assisted magnetron sputtering

    International Nuclear Information System (INIS)

    CrN coatings were deposited on Si (100) and piston rings by ion source assisted 40 kHz magnetron sputtering. Structure and composition of the coatings were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Mechanical and tribological properties were assessed by microhardness and pin-on-disc testing. The ion source-assisted system has a deposition rate of 3.88 μm/h, against 2.2 μm/h without ion-source assistance. The CrN coatings prepared with ion source assistance exhibited an increase in microhardness (up to 16.3 GPa) and decrease in friction coefficient (down to 0.48) at the optimized cathode source-to-substrate distance. Under optimized conditions, CrN coatings were deposited on piston rings, with a thickness of 25 μm and hardness of 17.85 GPa. (authors)

  4. Analytical electron microscopy of interface layers between Ti(6% Al, 4% V) and a CrN cathodic arc coating

    International Nuclear Information System (INIS)

    This paper reports on the applications of analytical electron microscopy to the study of cathodic arc deposited CrN coating on a Ti(6% Al, 4% V) substrate. Particular attention is given to analysis of the coating/substrate interface. Electron energy loss spectroscopy is used to show that the Cr sputter cleaning of the Ti(6% Al, 4% V) results in penetration of Cr into the substrate giving a bcc alloy layer whose composition varies from Ti(6% Al, 4% V) at the substrate interface to almost pure Cr at the coating interface. Subsequent deposition of CrN results in an initial deposition of sub-stoichiometric Cr2N followed by sub-stoichiometric CrN with a } 022{ texture and a columnar structure. The degree of sub-stoichiometry of the nitrides depends on the substrate bias and the substrate orientation relative to the cathode. (author)

  5. Cross-field diode sputtering target assembly

    International Nuclear Information System (INIS)

    An improved cross-field diode sputtering target assembly adapted for sputtering a selected material having an ion target wherein a selected surface is formed of a selected material in a predetermined closed loop pattern having a central opening therein, and wherein the selected surface has spaced edges and is formed of a material adapted to be controllably eroded in a diode sputtering process, walls positioned contiguous or adjacent to each of the spaced edges of the selected surface wherein each of the walls extend substantially normal from and beyond each spaced edge of the selected surface of the ion target and a magnetic member having poles positioned in an opposed spaced relationship to each other and enclosing the walls and the ion target for providing a linear magnetic field through the walls, over the selected surface and through the ion target and wherein the magnetic member has a linear magnetic field of sufficient strength for plasma entrapment between the walls and over the selected surface wherein the selected surface is adapted to have an electric field applied thereacross at a direction substantially normal to the magnetic field to develop a BXE field and to entrap secondary electrons at the selected surface to control the erosion pattern thereof is shown. A method for utilizing the improved cross-field diode sputtering target assembly is also shown

  6. Lithium insertion in sputtered vanadium oxide film

    DEFF Research Database (Denmark)

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.;

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  7. Sputtering of Surfaces of the Solid Hydrogens

    DEFF Research Database (Denmark)

    Schou, Jørgen; Thestrup Nielsen, Birgitte; Svendsen, Winnie Edith; Stenum, Bjarne; Ellegaard, Ole; Pedrys, R.; Warczak, B.

    Sputtering of the solid hydrogens by electrons and ions exhibits features that may be related to quantum properties of these solids, i.e. a drastic enhancement of the yield for electron–bombarded thick deuterium films and a thermal peak at low ejection energies in the energy distribution of the...

  8. RF Sputtering of Gold Contacts On Niobium

    Science.gov (United States)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  9. Sputtering of ErD2: experiment and theory

    International Nuclear Information System (INIS)

    Experimental measurements were made of the sputtering yield of ErD2 targets bombarded by D and A ions in the energy range 50-400 keV. A semiempirical sputtering theory is presented that relates sputtering to the energy deposited into atomic collisions beneath the target surface as well as at the surface. The theory accurately predicts the sputtering yields for both D and A bombardment. Additional calculated sputtering yields for ErD2 targets are presented which should allow extrapolation to any ion in the range of Z = 1 to Z = 36 with an accuracy better than 50 percent

  10. Pulsed dc self-sustained magnetron sputtering

    International Nuclear Information System (INIS)

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm2. The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition

  11. Characterization of Ag-doped vanadium oxide (Ag{sub x}V{sub 2}O{sub 5}) thin film for cathode of thin film battery

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, H.S.; Lee, D.Y. [Korea Univ., Seoul (Korea). Div. of M.S.E.; Oh, S.H.; Kim, H.S.; Cho, W.I.; Cho, B.W. [Korea Inst. of Science and Technology, Seoul (Korea). Econ-nano Research Center

    2004-11-30

    The effect of silver co-sputtering on the characteristics of amorphous V{sub 2}O{sub 5} films, grown by dc reactive sputtering, is investigated. The co-sputtering process influences the growth mechanism as well as the characteristics of the V{sub 2}O{sub 5} films. X-ray diffraction (XRD), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectrometry (XPS) results indicate that the microstructure of the V{sub 2}O{sub 5} films is affected by the rf power of the co-sputtered silver. In addition, an all-solid-state thin film battery with full cell structure of Li/LiPON/Ag{sub x}V{sub 2}O{sub 5}/Pt has been fabricated. It is found that the silver co-sputtered V{sub 2}O{sub 5} cathode film exhibits better cycle performance than an undoped one.

  12. Batteries: Overview of Battery Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Doeff, Marca M

    2010-07-12

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

  13. News on sputter theory: Molecular targets, nanoparticle desorption, rough surfaces

    International Nuclear Information System (INIS)

    Sputtering theory has existed as a mature and well-understood field of physics since the theory of collision-cascade sputtering has been developed in the late 1960s. In this presentation we outline several directions, in which the basic understanding of sputter phenomena has been challenged and new insight has been obtained recently. Sputtering of molecular solids: after ion impact on a molecular solid, not all of the impact energy is available for inducing sputtering. Part of the energy is converted into internal (rotational and vibrational) excitation of the target molecules, and part is used for molecule dissociation. Furthermore, exothermic or endothermic chemical reactions may further change the energy balance in the irradiated target. Nanoparticle desorption: usually, the flux of sputtered particles is dominated by monatomics; in the case of a pronounced spike contribution to sputtering, the contribution of clusters in the sputtered flux may become considerable. Here, we discuss the situation that nanoparticles were present on the surface, and outline mechanisms of how these may be desorbed (more or less intact) by ion or cluster impact. Rough surfaces: real surfaces are rough and contain surface defects (adatoms, surface steps, etc.). For grazing ion incidence, these influence the energy input into the surface dramatically. For such incidence angles sputtering vanishes for a flat terrace; however, ion impact close to a defect may lead to sputter yields comparable to those at normal incidence. In such cases sputtering also exhibits a pronounced azimuth and temperature dependence.

  14. Cathodic behavior of zirconium in aqueous solutions

    International Nuclear Information System (INIS)

    The electrochemical behavior of Zr was studied by polarization measurements. The surface oxide and zirconium hydride formed by cathodic polarization of Zr have been examined by X-ray, SEM, and a hardness tester. Zirconium hydride would form on Zr cathode after the surface oxide is reduced at the potential, which is several hundred mV more noble than the predicted value shown by the Pourbaix diagram. The parameters for the hydrogen evolution reaction on the hydride formed Zr cathode differs from that on the oxide covered surface, which means that hydrogen evolution takes place on both surfaces under a different mechanism, while details are still veiled at present

  15. Plasma distribution of cathodic ARC deposition system

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S.; Raoux, S.; Krishnan, K.; MacGill, R.A.; Brown, I.G. [Lawrence Berkeley National Lab., CA (United States)

    1996-08-01

    The plasma distribution using a cathodic arc plasma source with and without magnetic macroparticle filter has been determined by depositing on a transparent plastic substrate and measuring the film absorption. It was found that the width of the distribution depends on the arc current, and it also depends on the cathode material which leads to a spatial separation of the elements when an alloy cathode is used. By applying a magnetic multicusp field near the exit of the magnetic filter, it was possible to modify the plasma distribution and obtain a flat plasma profile with a constant and homogeneous elemental distribution.

  16. Cyclotron resonance in a cathode ray tube

    International Nuclear Information System (INIS)

    Absorption of the RF energy by the electron beam in a cathode ray tube due to the cyclotron resonance is described. The cathode ray tube is placed within a Helmholtz coils system supplied by a sawtooth current generator. In order to generate RF field and to detect RF absorption a gate dip-meter equipped with a FET transistor is used. The bias voltage variations of the FET transistors as a function of the magnetic field are recorded. The operating point of the cathode ray tube has been chosen so that the relaxation oscillations of the detection system can be observed. (authors)

  17. Structure and electron emission characteristics of sputtered rare-earth hexaboride films

    International Nuclear Information System (INIS)

    Thermionic coatings based on the hexaborides of rare-earth elements were deposited onto molybdenum and tungsten substrates using dc magnetron sputtering from LaB6, CeB6, SmB6 and YB6 targets. Films were investigated by means of scanning electron microscopy and X-ray diffraction. The work function and electron emission characteristics of the coatings were studies by the thermionic emission method and by the contact potential method. After optimization of the sputtering parameters extremely fine-columnar coatings consisting of predominantly (100) oriented La-B, Ce-B and Sm-B crystals were obtained. The Y-b films showed nearly amorphous film growth. The work function was measured to be in the range of 2.6 to 3.3 eV. Coated cathodes worked with comparable electron emission current at temperatures approximately 1000 deg C below the operating temperature of uncoated tungsten filaments. (author). 9 refs., 2 figs., 1 tab., 4 photos

  18. Structure and electron emission characteristics of sputtered rare-earth hexaboride films

    Energy Technology Data Exchange (ETDEWEB)

    Waldhauser, W.; Mitterer, C. [Montanuniversitaet Leoben (Austria); Winkler, A. [Technische Univ., Graz (Austria)

    1996-12-31

    Thermionic coatings based on the hexaborides of rare-earth elements were deposited onto molybdenum and tungsten substrates using dc magnetron sputtering from LaB{sub 6}, CeB{sub 6}, SmB{sub 6} and YB{sub 6} targets. Films were investigated by means of scanning electron microscopy and X-ray diffraction. The work function and electron emission characteristics of the coatings were studies by the thermionic emission method and by the contact potential method. After optimization of the sputtering parameters extremely fine-columnar coatings consisting of predominantly (100) oriented La-B, Ce-B and Sm-B crystals were obtained. The Y-b films showed nearly amorphous film growth. The work function was measured to be in the range of 2.6 to 3.3 eV. Coated cathodes worked with comparable electron emission current at temperatures approximately 1000 deg C below the operating temperature of uncoated tungsten filaments. (author). 9 refs., 2 figs., 1 tab., 4 photos.

  19. A novel sputtered Pd mesh architecture as an advanced electrocatalyst for highly efficient hydrogen production

    Science.gov (United States)

    de Lucas-Consuegra, Antonio; de la Osa, Ana R.; Calcerrada, Ana B.; Linares, José J.; Horwat, David

    2016-07-01

    This study reports the preparation, characterization and testing of a sputtered Pd mesh-like anode as an advanced electrocatalyst for H2 production from alkaline ethanol solutions in an Alkaline Membrane Electrolyzer (AEM). Pd anodic catalyst is prepared by magnetron sputtering technique onto a microfiber carbon paper support. Scanning Electron Microscopy images reveal that the used preparation technique enables to cover the surface of the carbon microfibers exposed to the Pd target, leading to a continuous network that also maintains part of the original carbon paper macroporosity. Such novel anodic architecture (organic binder free) presents an excellent electro-chemical performance, with a maximum current density of 700 mA cm-2 at 1.3 V, and, concomitantly, a large H2 production rate with low energy requirement compared to water electrolysis. Potassium hydroxide emerges as the best electrolyte, whereas temperature exerts the expected promotional effect up to 90 °C. On the other hand, a 1 mol L-1 ethanol solution is enough to guarantee an efficient fuel supply without any mass transfer limitation. The proposed system also demonstrates to remain stable over 150 h of operation along five consecutives cycles, producing highly pure H2 (99.999%) at the cathode and potassium acetate as the main anodic product.

  20. Structural and electrical characterization of magnetron sputtered MoO3 thin films

    International Nuclear Information System (INIS)

    Thin films of molybdenum oxide were deposited on glass and crystalline silicon substrates using dc magnetron sputtering method by sputtering of molybdenum target in the presence of oxygen and argon gas mixture under various oxygen partial pressures in the range 8x10-5 - 8x10-4 mbar. The glow discharge characteristics of the molybdenum cathode under various oxygen partial pressures were studied. The effect of oxygen partial pressure on the core level binding energy, structure, mechanical and electrical properties of the films was systematically studied. The films formed at oxygen partial pressures -4 mbar contained the MoO3 and MoO3-x phases. The films deposited at oxygen partial pressures of 2x10-4 mbar were stoichiometric with single phase orthorhombic α- MoO3. The electrical conductivity of films decreased from 4x10-5 to 1.6x10-6 Ω-1cm-1 with increase of oxygen partial pressure from 8x10-5 to 8x10-4 mbar.

  1. Properties of All-Solid Lithium-Ion Rechargeable Batteries Deposited by RF Magnetron Sputtering

    Science.gov (United States)

    Zhu, R. J.; Ren, Y.; Geng, L. Q.; Chen, T.; Li, L. X.; Yuan, C. R.

    2013-08-01

    Amorphous V2O5, LiPON and Li2Mn2O4 thin films were fabricated by RF magnetron sputtering methods and the morphology of thin films were characterized by scanning electron microscopy. Then with these three materials deposited as the anode, solid electrolyte, cathode, and vanadium as current collector, a rocking-chair type of all-solid-state thin-film-type Lithium-ion rechargeable battery was prepared by using the same sputtering parameters on stainless steel substrates. Electrochemical studies show that the thin film battery has a good charge-discharge characteristic in the voltage range of 0.3-3.5 V, and after 30 cycles the cell performance turned to become stabilized with the charge capacity of 9 μAh/cm2, and capacity loss of single-cycle of about 0.2%. At the same time, due to electronic conductivity of the electrolyte film, self-discharge may exist, resulting in approximately 96.6% Coulombic efficiency.

  2. High power microwave generation from coaxial virtual cathode oscillator using graphite and velvet cathodes

    Science.gov (United States)

    Menon, Rakhee; Roy, Amitava; Singh, S. K.; Mitra, S.; Sharma, Vishnu; Kumar, Senthil; Sharma, Archana; Nagesh, K. V.; Mittal, K. C.; Chakravarthy, D. P.

    2010-05-01

    High power microwave (HPM) generation studies were carried out in KALI-5000 pulse power system. The intense relativistic electron beam was utilized to generate HPMs using a coaxial virtual cathode oscillator. The typical electron beam parameters were 350 kV, 25 kA, and 100 ns, with a few hundreds of ampere per centimeter square current density. Microwaves were generated with graphite and polymer velvet cathode at various diode voltage, current, and accelerating gaps. A horn antenna setup with diode detector and attenuators was used to measure the microwave power. It was observed that the microwave power increases with the diode voltage and current and reduces with the accelerating gap. It was found that both the peak power and width of the microwave pulse is larger for the velvet cathode compared to the graphite cathode. In a coaxial vircator, velvet cathode is superior to the graphite cathode due to its shorter turn on time and better electron beam uniformity.

  3. A comparative research on magnetron sputtering and arc evaporation deposition of Ti-Al-N coatings

    International Nuclear Information System (INIS)

    Ti-Al-N coating has been proven to be an effective protective coating for machining applications. Here, the differences of cubic Ti-Al-N coatings with a similar Ti/Al atomic ratio of 1 deposited by magnetron sputtering and cathodic arc evaporation have been studied in detail. Main emphasis was laid on the characterization of thermal stability and cutting performance. Both coatings during annealing exhibit a structural transformation into stable phases c-TiN and h-AlN via an intermediate step of spiondal decomposition with the precipitation of c-AlN, however, a difference in decomposition process. Compared to sputtered coating inserts, an increase of tool life-time by 42% is obtained by evaporated coating inserts at the higher speed of 200 m/min, whereas the similar cutting life is observed at the speed of 160 m/min. It is attributed to the better stability of evaporated coating due to its later structural transformation at elevated temperature. A post-deposition vacuum annealing of both coated inserts in their corresponding temperature range of spiondal decomposition improves their cutting performance due to an increase in hardness arising from the precipitation of coherent cubic-phase nanometer-size c-AlN domains. Additionally, the sputtered coating behaves in worse oxidation resistance due to its more open structure. These behaviors can be understood considering the difference in microstructure and morphology of as deposited coatings originating from adatom mobility of deposited particles, where arc evaporation technique with higher ion to neutral ratio shows higher adatom mobility.

  4. Construction of cathode thermometry and emission test system

    International Nuclear Information System (INIS)

    A thermal cathode (Eimac Y-845) is used for an electron gun at the SPring-8 1-GeV linac. The gun can eject a 180 keV beam of 3 A from the cathode operated at a nominal heater voltage. As the discharge rate between the cathode and the grid becomes high along with the cathode driving time, we replace a cathode with a new one once a year. Before the cathode installation, we have definitely inspected new cathodes by means of a microscope to find defects in their cathodes and grids. However, the emission currents have been sometimes insufficient, or the cathode planes have contacted with the grids due to the heat distortion of the grids. We have suspected that the inadequate cathode temperature may have caused these cathode failures. To monitor the accurate cathode temperature and to reduce the cathode failures, we have constructed a measuring system of the cathode temperatures and the cathode emission currents at the test stand. We redesigned the whenelt and the anode to achieve a space-charge-limited current of 3 A at an acceleration voltage less than -70 kV. The cathode temperature at the nominal heater voltage is expected to be 854degC according to the Richardson-Dushman equation, whereas the actual temperature measured by an infrared thermometer was 813±5degC. This large disagreement is under investigation. (author)

  5. Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings

    Science.gov (United States)

    Cuynet, S.; Caillard, A.; Kaya-Boussougou, S.; Lecas, T.; Semmar, N.; Bigarré, J.; Buvat, P.; Brault, P.

    2015-12-01

    Proton exchange membranes were nano- and micro-patterned on their cathode side by pressing them against stainless steel molds previously irradiated by a Ti:Sapphire femtosecond laser. The membranes were associated to ultra-low loaded thin catalytic layers (25 μgPt cm-2) prepared by plasma magnetron sputtering. The Pt catalyst was sputtered either on the membrane or on the porous electrode. The fuel cell performance in dry conditions were found to be highly dependent on the morphology of the membrane surface. When nanometric ripples covered by a Pt catalyst were introduced on the surface of the membrane, the fuel cell outperformed the conventional one with a flat membrane. By combining nano- and micro-patterns (nanometric ripples and 11-24 μm deep craters), the performance of the cells was clearly enhanced. The maximum power density achieved by the fuel cell was multiplied by a factor of 3.6 (at 50 °C and 3 bar): 438 mW cm-2 vs 122 mW cm-2. This improvement is due to high catalyst utilization with a high membrane conductivity. When Pt is sputtered on the porous electrode (and not on the membrane), the contribution of the patterned membrane to the fuel cell efficiency was less significant, except in the presence of nanometric ripples. This result suggests that the patterning of the membrane must be consistent with the way the catalyst is synthesized, on the membrane or on the porous electrode.

  6. Behavior of electrons in a dual-magnetron sputter deposition system: a Monte Carlo model

    International Nuclear Information System (INIS)

    A Monte Carlo model has been developed for investigating the electron behavior in a dual-magnetron sputter deposition system. To describe the three-dimensional (3D) geometry, different reference frames, i.e. a local and a global coordinate system, were used. In this study, the influence of both closed and mirror magnetic field configurations on the plasma properties is investigated. In the case of a closed magnetic field configuration, the calculated electron trajectories show that if an electron is emitted in (or near) the center of the cathode, where the influence of the magnetic field is low, it is able to travel from one magnetron to the other. On the other hand, when an electron is created at the race track area, it is more or less trapped in the strong magnetic field and cannot easily escape to the second magnetron region. In the case of a mirror magnetic field configuration, irrespective of where the electron is emitted from the cathode, it cannot travel from one magnetron to the other because the magnetic field lines guide the electron to the substrate. Moreover, the electron density and electron impact ionization rate have been calculated and studied in detail for both configurations.

  7. Characterization of the plasma in a radio-frequency magnetron sputtering system

    International Nuclear Information System (INIS)

    In order to understand the fundamental mechanisms in a radio-frequency magnetron sputtering system, the main properties of the argon plasma used in the process have been measured. A complete three-dimensional map of the ion density, electron temperature, and plasma potential has been obtained using a Langmuir probe. The electron temperature as well as the ion density have been found to increase in the region of the so called race track at the cathode. Furthermore, from the plasma potential map, the time-averaged local electric field has been obtained, pointing out the race track as the region where the most intense ion bombardment takes place. Besides, only the ions produced near the race track are accelerated towards the cathode, whereas those produced in the remaining volume move towards the anode. Finally, the dependence of the plasma quantities on the incident radio-frequency power and deposition pressure has been studied. The plasma potential measured using the Langmuir probe has been found to agree with that determined using an energy resolved mass spectrometer in all studied conditions

  8. Hollow cathode ion source without magnetic field

    International Nuclear Information System (INIS)

    On the base of the IBM-4 ion source a hollow cathode source operating in the continuous regime is developed. The gas discharge chamber diameter equals 100 mm, chamber height - 50 mm. A hollow cathode represents a molybdenum tube with an internal diameter 13 mm and wall thickness 0,7-0,8 mm. An emitter is manufactured from zirconium carbide and lanthanum hexaboride. The investigations of the source operation have shown both cathodes operated efficiency. Electron emission density consitutes 25 A/cm2. At the 50 A discharge current ion current density in a center of plasma emitter constitutes 120 mA/cm2. As a result of the investigations carried out the compatibility of the hollow cathode and the IBM-type source is shown

  9. Short pulse photoemission from a dispenser cathode

    Science.gov (United States)

    Bergeret, H.; Boussoukaya, M.; Chehab, R.; Leblond, B.; Le Duff, J.

    1991-03-01

    Pulsed photoemission in the picosecond regime has been obtained from a standard thermionic dispenser cathode (WBaCa) at temperatures below the measurable thermoemission threshold. A picosecond Nd : YAG mode locked laser has been used at both green and UV light. Micropulse charges up to 0.5 nC have been measured on a wideband coaxial pickup located behind the anode. They correspond to an electron saturation limit from an approximately 20 mm 2 illuminated cathode area with a surface field of 3 MV/m. The effective cathode efficiency at small laser energies, defined as the number of electrons impinging on the coaxial pickup divided by the number of photons impinging on the cathode, is about 2 × 10 -5.

  10. Ion bombardment investigations of impregnated cathodes

    Science.gov (United States)

    Zhang, Xiaobing; Gaertner, Georg

    2003-06-01

    Ion bombardment is one of the important factors limiting the performance of impregnated cathodes (=Ba dispenser cathodes) in high end television tubes or in colour monitor tubes. Hence, when designing a new gun with, e.g. higher electron beam current density, it is important also to model the influence of ion bombardment. Therefore, relations between basic parameters as a function of temperature need to be known quantitatively. In this paper, the emission slump of impregnated cathodes has been analyzed in a diode configuration in UHV with a differentially pumped Ar ion gun. The emission degeneration during and regeneration periods after ion bombardment have been investigated as function of cathode temperature, ion current and ion energy. One of the important results is, that the degeneration time coefficient is only weakly dependent on ion energy. The data matrix obtained can be used to improve the ion bombardment model applied in new electron gun design.

  11. Short pulse photoemission from a dispenser cathode

    International Nuclear Information System (INIS)

    Pulsed photoemission in picosecond regime has been obtained from a standard thermionic dispenser cathode (W - Ba - Ca) at temperatures below measurable thermoemission threshold. A picosecond Nd: YAG mode locked laser has been used at both green and U.V. light. Micro-pulse charges up to 0.5 nC have been measured on a wideband coaxial pick up located behind the anode. They correspond to an electron saturation limit from an approximately 20 mm2 illuminated cathode area with a surface field of 3 MV/m. The effective cathode efficiency at small laser energies, defined as the number of electron impinging the coaxial pick up divided by the number of photons impinging the cathode, is about 2.10-5

  12. Ion bombardment investigations of impregnated cathodes

    International Nuclear Information System (INIS)

    Ion bombardment is one of the important factors limiting the performance of impregnated cathodes (=Ba dispenser cathodes) in high end television tubes or in colour monitor tubes. Hence, when designing a new gun with, e.g. higher electron beam current density, it is important also to model the influence of ion bombardment. Therefore, relations between basic parameters as a function of temperature need to be known quantitatively. In this paper, the emission slump of impregnated cathodes has been analyzed in a diode configuration in UHV with a differentially pumped Ar ion gun. The emission degeneration during and regeneration periods after ion bombardment have been investigated as function of cathode temperature, ion current and ion energy. One of the important results is, that the degeneration time coefficient is only weakly dependent on ion energy. The data matrix obtained can be used to improve the ion bombardment model applied in new electron gun design

  13. RF Electron Gun with Driven Plasma Cathode

    CERN Document Server

    Khodak, Igor

    2005-01-01

    It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

  14. Reservoir Scandate Cathode for Electric Propulsion Project

    Data.gov (United States)

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

  15. High current density cathode for electrorefining in molten electrolyte

    Science.gov (United States)

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  16. Sodium expansion and creep of cathode carbon

    OpenAIRE

    Hop, Jørund Gimmestad

    2003-01-01

    An apparatus to measure compressive creep in carbon materials has been developed. Using the final experimental set-up five material properties could be measured in each electrolysis experiment. Creep, sodium expansion, compressive strength and E-modulus were measured for 3 commercial cathode materials at 25 and 980 °C with and without electrolysis. The sodium diffusion coefficient (D) was calculated from the sodium expansion results.Filler materials for cathode blocks, i.e., certain anthracit...

  17. Salt taste inhibition by cathodal current

    OpenAIRE

    Hettinger, Thomas P.; Frank, Marion E.

    2009-01-01

    Effects of cathodal current, which draws cations away from the tongue and drives anions toward the tongue, depend on the ionic content of electrolytes through which the current is passed. To address the role of cations and anions in human salt tastes, cathodal currents of −40 to −80 µA were applied to human subjects’ tongues through supra-threshold salt solutions. The salts were sodium chloride, sodium bromide, potassium chloride, ammonium chloride, calcium chloride, sodium nitrate, sodium su...

  18. Co-Flow Hollow Cathode Technology

    Science.gov (United States)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

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

  19. Development of plasma cathode electron guns

    Science.gov (United States)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

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

  20. Influence of manufacturing process of indium tin oxide sputtering targets on sputtering behavior

    Energy Technology Data Exchange (ETDEWEB)

    Gehman, B.L. (Leybold Materials Inc., Morgan Hill, CA (United States)); Jonsson, S. (Degussa AG, Dept. FTM-S, Hanau (Germany)); Rudolph, T. (Degussa AG, Dept. FTM-S, Hanau (Germany)); Scherer, M. (Leybold AG, R and D Dept., Alzenau (Germany)); Werner, R. (Leybold AG, R and D Dept., Alzenau (Germany)); Weigert, M. (Leybold Materials GmbH, Hanau (Germany))

    1992-11-20

    Thin films of In[sub 2]O[sub 3]+SnO[sub 2] (indium tin oxide or ITO) have wide utility because they are electrically conductive and transparent at visible wavelengths. A preferred method for making highest quality ITO coatings is reactive sputtering from targets of mixed indium and tin oxides. The resulting film properties are highly dependent upon the deposition conditions, and upon post-deposition film treatments. Film data and sputtering efficiency are also effected deposition conditions, and upon post-deposition film treatments. Film data and sputtering efficiency are also effected by sputtering target characteristics. This study evaluated the influence of the targets on the electrical resistivity of deposited ITO films, and the effect of target properties on the sputtering rate. A matrix of 12 targets was tested; all had composition 90 wt.%In[sub 2]O[sub 3]+10 wt.%SnO[sub 2]. The effects of varying target density, degree of target oxide reduction from complete stoichiometry, and target purity were measured. The results are, in summary, (1) partial reduction of oxide targets from complete stoichiometry does not influence film resistivity, (2) the data indicate a small (perhaps negligible) dependence of film resistivity upon target density, (3) higher target density tends to promote enhanced deposition rate, and (4) purposeful addition of silicon, aluminum, magnesium, calcium, and sodium at high levels to ITO targets degrades film resistivity depending upon the total concentration of impurities added, but independently of the contaminating species. (orig.)

  1. Sputtering behavior of boron and boron carbide

    International Nuclear Information System (INIS)

    Sputtering yields of boron were measured with D+ and B+ ions for normal and oblique angles of incidence. Self-sputtering data of boron carbide were simulated in the experiment by using Ne+ ions. The energies of the impinging ions were between 20 eV and 10 keV. The measured data are compared with computer simulated values calculated with the TRIMSP program. The boron data for normal ion impact are higher than the calculated values, whereas those for oblique ion incidence are smaller than the calculation predicts. This discrepancy is explained by the surface roughness and supported by SEM micrographs. The comparison of the boron carbide data with TRIMSP calculations shows much better agreement than the boron data. In this case the target surface was much smoother. (orig.)

  2. Thermal conductivities of thin, sputtered optical films

    International Nuclear Information System (INIS)

    The normal component of thin-film thermal conductivity has been measured for the first time, to the best of our knowledge, for several advanced sputtered optical materials. Included are data for single layers of boron nitride, silicon aluminum nitride, silicon aluminum oxynitride, silicon carbide, and for dielectric-enhanced metal reflectors of the form Al(SiO2/Si3N4)n and Al(Al2O3/AlN)n. Sputtered films of more conventional materials such as SiO2, Al2O3, Ta2O5, Ti, and Si have also been measured. The data show that thin-film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film--substrate interface contribution is presented

  3. Sputter-initiated resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    A new technique, sputter-initiated resonance ionization spectroscopy (SIRIS), which provides an ultrasensitive analysis of solid samples for all elements except helium and neon is described in this paper. Sensitivities down to 1 part in 1012 should be available in routine SIRIS analysis, and greater sensitivities should be available for special cases. The basic concepts of this technology and early results in the development of the new SIRIS process and apparatus are presented. (Auth.)

  4. Magnetron sputtering of thin nitride films

    OpenAIRE

    Kola, Prashanthi V

    1995-01-01

    The objective in this investigation was to design and commission a magnetron sputter deposition system and investigate the properties of hard coatings for mechanical and biomedical applications. The deposition of titanium (Ti) and titanium nitride (TiN) was undertaken as part of the commissioning tests and further work was conducted on the effect of the deposition parameters on the properties of TiN, specifically for biocompatible applications. A thorough understanding of the deposition proce...

  5. Sputter coating of microspherical substrates by levitation

    Science.gov (United States)

    Lowe, A.T.; Hosford, C.D.

    Microspheres are substantially uniformly coated with metals or nonmetals by simltaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure comprising a parallel array of upwardly projecting individual gas outlets is machined out to form a dimple. Glass microballoons,, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  6. Niobium sputter deposition on quarter wave resonators

    CERN Document Server

    Viswanadham, C; Jayaprakash, D; Mishra, R L

    2003-01-01

    Niobium sputter deposition on quarter wave copper R.F resonators, have been taken up in our laboratory, An ultra high vacuum system was made for this purpose. Niobium exhibits superconducting properties at liquid Helium temperature. A uniform coating of about 1.5 mu m of niobium on the internal surfaces of the copper resonant cavities is desired. Power dissipation in the resonators can be greatly reduced by making the internal surfaces of the R.F cavity super conducting. (author)

  7. Plasma processes inside dispenser hollow cathodes

    Science.gov (United States)

    Mikellides, Ioannis G.; Katz, Ira; Goebel, Dan M.; Polk, James E.; Jameson, Kristina K.

    2006-06-01

    A two-dimensional fluid model of the plasma and neutral gas inside dispenser orificed hollow cathodes has been developed to quantify plasma processes that ultimately determine the life of the porous emitters inserted in these devices. The model self-consistently accounts for electron emission from the insert as well as for electron and ion flux losses from the plasma. Two cathodes, which are distinctively different in size and operating conditions, have been simulated numerically. It is found that the larger cathode, with outer tube diameter of 1.5cm and orifice diameter of 0.3cm, establishes an effective emission zone that spans approximately the full length of the emitter when operated at a discharge current of 25A and a flow rate of 5.5sccm. The net heating of the emitter is caused by ions that are produced by ionization of the neutral gas inside the tube and are then accelerated by the sheath along the emitter. The smaller cathode, with an outer diameter of 0.635cm and an orifice diameter of 0.1cm, does not exhibit the same operational characteristics. At a flow rate of 4.25sccm and discharge current of 12A, the smaller cathode requires 4.5 times the current density near the orifice and operates with more than 6 times the neutral particle density compared to the large cathode. As a result, the plasma particle density is almost one order of magnitude higher compared to the large cathode. The plasma density in this small cathode is high enough such that the Debye length is sufficiently small to allow "sheath funneling" into the pores of the emitter. By accessing areas deeper into the insert material, it is postulated that the overall emission of electrons is significantly enhanced. The maximum emission current density is found to be about 1A/mm2 in the small cathode, which is about one order of magnitude higher than attained in the large cathode. The effective emission zone in the small cathode extends to about 15% of the emitter length only, and the power

  8. Plasma processes inside dispenser hollow cathodes

    International Nuclear Information System (INIS)

    A two-dimensional fluid model of the plasma and neutral gas inside dispenser orificed hollow cathodes has been developed to quantify plasma processes that ultimately determine the life of the porous emitters inserted in these devices. The model self-consistently accounts for electron emission from the insert as well as for electron and ion flux losses from the plasma. Two cathodes, which are distinctively different in size and operating conditions, have been simulated numerically. It is found that the larger cathode, with outer tube diameter of 1.5 cm and orifice diameter of 0.3 cm, establishes an effective emission zone that spans approximately the full length of the emitter when operated at a discharge current of 25 A and a flow rate of 5.5 sccm. The net heating of the emitter is caused by ions that are produced by ionization of the neutral gas inside the tube and are then accelerated by the sheath along the emitter. The smaller cathode, with an outer diameter of 0.635 cm and an orifice diameter of 0.1 cm, does not exhibit the same operational characteristics. At a flow rate of 4.25 sccm and discharge current of 12 A, the smaller cathode requires 4.5 times the current density near the orifice and operates with more than 6 times the neutral particle density compared to the large cathode. As a result, the plasma particle density is almost one order of magnitude higher compared to the large cathode. The plasma density in this small cathode is high enough such that the Debye length is sufficiently small to allow 'sheath funneling' into the pores of the emitter. By accessing areas deeper into the insert material, it is postulated that the overall emission of electrons is significantly enhanced. The maximum emission current density is found to be about 1 A/mm2 in the small cathode, which is about one order of magnitude higher than attained in the large cathode. The effective emission zone in the small cathode extends to about 15% of the emitter length only, and the

  9. Effect of Colloidal Silica and Pre-Coating of Cathode on Copper Electrodeposited Film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S. B.; Kim, B. I. [Sunchon National University, Sunchon (Korea); Yoon, J. M. [Chonbuk National University, Chonju (Korea); Park, H. H.; Bae, I. S. [Korea Research Institute of Rare Metals, (Korea)

    2001-07-01

    The crystal structure, surface morphology and preferred orientation of the copper electrodeposit were investigated by the using sulfate bath with SiO{sub 2} suspensions and the cathode substrate Au sputtered. As by the addition of colloidal silica in copper electrolytic bath and Au pre-coating on substrate, the crystal particles of deposits was fined-down, made uniform and the account of particles were increased. Hardness of copper electrodeposits with colloidal silica increased about 15% in comparison with that of pure copper deposit film and (111), (200) and (311) plane of X-ray diffraction patterns were almost swept away, so preferred orientation of the copper deposits changed from (111) to (110) plane by codeposit SiO{sub 2} and precoating the substrate. (author). 5 refs., 9 figs., 2 tabs.

  10. Determination of Nd, Ho, Er, Tm and Y in solutions by hollow cathode discharge with copper cathodes

    International Nuclear Information System (INIS)

    A hollow cathode discharge has been applied to the determination of Nd, Ho, Er, Tm and Y in solutions using copper cathodes and argon as a carrier gas. The solutions were evaporated to dryness in the cathodes without a pretreatment. Absolute detection limit for the elements studied here were found to be lower in the copper cathode by about one order than those obtained in previous studies in graphite hollow cathodes

  11. Experimental Investigation of Thruster Cathode Physics

    Science.gov (United States)

    Crofton, Mark

    2004-11-01

    Advanced ion propulsion technologies are being developed under the Nuclear Electric Xenon Ion System (NEXIS) program for use in outer planet exploration. A revolutionary approach to thruster cathode design is dictated by the very high lifetime and propellant throughput requirements for nuclear electric applications. In conventional dispenser hollow cathodes used in thrusters, processes leading to depletion, inadequate transport, or insufficient production of barium are among those limiting the lifetime. A reservoir hollow cathode is being developed to address each of these failure mechanisms, exploiting four design variables - matrix material, source material, geometry, and thermal design - to essentially eliminate established failure modes. The very long anticipated lifetime necessitates new life validation methods to augment or replace the conventional lifetest approach. One important tool for quickly evaluating design changes is the ability to measure barium density inside a hollow cathode and/or in the plume. The dependence of barium density on temperature and other factors is an extremely important indicator of cathode health, particularly if the ratio Ba:BaO is also obtained. Comparison of barium production for reservoir and conventional cathodes will enable an assessment of the efficacy of reservoir designs and the goal of reducing barium consumption at a given emission current level. This study describes benchmark measurements made on a conventional cathode previously operated in a 20-kW NEXIS laboratory engine. Data on cathode operation and life-limiting processes were obtained through direct, real-time monitoring of atoms and molecules. A high-resolution, tunable laser system was employed to detect absorption of the low-density barium atoms inside the cathode. The plume was monitored also, using a quadrupole mass spectrometer to monitor multiple species and measure ion charge ratios. Data obtained with retarding potential analyzers or other means are

  12. Effect of the degree of high power impulse magnetron sputtering utilisation on the structure and properties of TiN films

    International Nuclear Information System (INIS)

    TiN films were deposited using high power impulse magnetron sputtering (HIPIMS) enabled four cathode industrial size coating system equipped with HIPIMS power supplies. The standard version of this system allows control over the ion bombardment during coating growth by varying the strength of the electromagnetic field of the unbalancing coils and bias voltage applied to the substrate. The coatings were produced in different coating growth conditions achieved in combined HIPIMS — direct current (dc) unbalanced magnetron sputtering (HIPIMS/UBM) processes where HIPIMS was used as an additional tool to manipulate the ionisation degree in the plasma. Four cathode combinations were explored with increasing contribution of HIPIMS namely 4UBM (pure UBM), 1HIPIMS + 3UBM, 2HIPIMS + 2UBM and 2HIPIMS (pure HIPIMS) to deposit TiN coatings. Optical emission spectroscopy (OES) measurements were carried out to examine the plasma generated by the various combinations of HIPIMS and UBM cathodes. The micro-structural study was done by scanning electron microscopy (SEM). X-ray diffraction (XRD) technique was used to calculate the residual stress and texture parameter. It has been revealed that the residual stress can be controlled in a wide range from − 0.22 GPa to − 11.67 GPa by intelligent selection of the degree of HIPIMS utilisation, strength of the electromagnetic field of the unbalancing coils and the bias voltage applied to the substrate while maintaining the stoichiometry of the coatings. The effect of the degree of HIPIMS utilisation on the microstructure, texture and residual stress is discussed. Combining HIPIMS with dc-UBM sputtering is also seen as an effective tool for improving the productivity of the deposition process. - Highlights: • High {Ti1+} in the plasma with increasing number of HIPIMS sources • Residual stress can be manipulated in a wide range. • Texture can be altered. • The 2HIPIMS + 2UBM combination appears to be the most advantageous

  13. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

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

  14. Reactive magnetron sputtering : from fundamentals to high deposition rate processes

    OpenAIRE

    Kubart, Tomas

    2013-01-01

    Reactive magnetron sputtering is widely used for synthesis of various compound thin films. The technique is very versatile and scalable. Especially in industry, high productivity is essential and there is a need for processes with high deposition rates. Achieving high deposition rate and true compound stoichiometry of the deposited film is, however, challenging in reactive sputtering. As a consequence of complex interaction between the reactive gas and the sputtered metal, the relation betwee...

  15. Contactless monitoring of cathodic protection

    International Nuclear Information System (INIS)

    Cathodic protection is a very efficient and economical way for protecting underground structures from electrolytic corrosion. The protection is maintained when the potential between the structure surface and the surrounding electrolyte keeps the material in an immune state from corrosion. This means, that the potential on every spot of the protected pipeline should be checked and maintained. Checking the potential can be on few way. The classical way, measuring the pipe to soil potential on the test post spaced 1 - 2 km apart only 'potential samples' can be obtained while 'hot spots' can be left between the test post. The so called 'intensive measurements', when potential is surveyed along the pipeline by a moving electrode connected to a test post. By checking the magnetic field of the returning current along the pipeline, the same anomalies can be found, as by checking the potential distribution along the pipeline, so the places with contacts with foreign structures or coating damages can be located. This measurements can be done by one person walking along the pipeline route. If the pipe route is without obstacles, the measurements can be performed from a vehicle moving along the pipe route. By using a computer based recording device in the vehicle, the measured values can be combined with the location of the anomalies and the printout will show directly the sort and location of the anomalies. Using a helicopter, when up to several hundreds of km pipeline route can be checked daily, makes further improvements. This paper presents current situation on this field, and equipment in FZC I I Oktomvri in Kumanovo. (Author)

  16. Sputtering materials for VLSI and thin film devices

    CERN Document Server

    Sarkar, Jaydeep

    2010-01-01

    An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall p

  17. Modeling and stability analysis of the nonlinear reactive sputtering process

    Directory of Open Access Journals (Sweden)

    György Katalin

    2011-12-01

    Full Text Available The model of the reactive sputtering process has been determined from the dynamic equilibrium of the reactive gas inside the chamber and the dynamic equilibrium of the sputtered metal atoms which form the compound with the reactive gas atoms on the surface of the substrate. The analytically obtained dynamical model is a system of nonlinear differential equations which can result in a histeresis-type input/output nonlinearity. The reactive sputtering process has been simulated by integrating these differential equations. Linearization has been applied for classical analysis of the sputtering process and control system design.

  18. Magnetron sputter deposition of boron and boron carbide

    International Nuclear Information System (INIS)

    The fabrication of X-ray optical coatings with greater reflectivity required the development of sputter deposition processes for boron and boron carbide. The use of high density boron and boron carbide (B4C) and a vacuum-brazed target design was required to achieve the required sputter process stability and resistance to the thermal stress created by high rate sputtering. Our results include a description of the target fabrication procedures and sputter process parameters necessary to fabricate B4C and boron modulated thin film structures. (orig.)

  19. Tribological and structural properties of titanium nitride and titanium aluminum nitride coatings deposited with modulated pulsed power magnetron sputtering

    Science.gov (United States)

    Ward, Logan

    The demand for economical high-performance materials has brought attention to the development of advanced coatings. Recent advances in high power magnetron sputtering (HPPMS) have shown to improve tribological properties of coatings. These coatings offer increased wear and oxidation resistance, which may facilitate the use of more economical materials in harsh applications. This study demonstrates the use of novel forms of HPPMS, namely modulated pulsed-power magnetron sputtering (MPPMS) and deep oscillation magnetron sputtering (DOMS), for depositing TiN and Ti1-xAlxN tribological coatings on commonly used alloys, such as Ti-6Al-4V and Inconel 718. Both technologies have been shown to offer unique plasma characteristics in the physical vapor deposition (PVD) process. High power pulses lead to a high degree of ionization compared to traditional direct-current magnetron sputtering (DCMS) and pulsed magnetron sputtering (PMS). Such a high degree of ionization was previously only achievable by cathodic arc deposition (CAD); however, CAD can lead to increased macroparticles that are unfavorable in high friction and corrosive environments. MPPMS, DOMS, and other HPPMS techniques offer unique plasma characteristics and have been shown to produce coatings with refined grain structure, improved density, hardness, adhesion, and wear resistance. Using DOMS and MPPMS, TiN and Ti1-xAlxN coatings were deposited using PMS to compare microstructures and tribological performance. For Ti1-xAlxN, two sputtering target compositions, Ti 0.5Al0.5 and Ti0.3Al0.7, were used to evaluate the effects of MPPMS on the coating's composition and tribological properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize microstructure and crystallographic texture. Several tribological properties were evaluated including: wear rate, coefficient of friction, adhesion, and nanohardness. Results show that substrate

  20. Laser modification and characterization of Li-Mn-O thin film cathodes for lithium-ion batteries

    Science.gov (United States)

    Pröll, J.; Kohler, R.; Adelhelm, C.; Bruns, M.; Torge, M.; Heißler, S.; Przybylski, M.; Ziebert, C.; Pfleging, W.

    2011-03-01

    The development of future battery systems is mainly focused on powerful rechargeable lithium-ion batteries. To satisfy this demand, current studies are focused on cathodes based on nano-composite materials which lead to an increase in power density of the LIB primarily due to large electrochemically active surface areas. Electrode materials made of lithium manganese oxides (Li-Mn-O) are assumed to replace commonly used cathode materials like LiCoO2 due to less toxicity and lower costs. Thin films in the Li-Mn-O system were synthesized by non-reactive r.f. magnetron sputtering of a LiMn2O4 target on silicon and stainless steel substrates. In order to enhance power density and cycle stability of the cathode material, direct laser structuring methods were investigated using a laser system operating at a wavelength of 248 nm. Therefore, high aspect ratio micro-structures were formed on the thin films. Laser annealing processes were investigated in order to achieve an appropriate crystalline phase for unstructured and structured thin films as well as for an increase in energy density and control of grain size. Laser annealing was realized via a high power diode laser system. The effects of post-thermal treatment on the thin films were studied with Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The formation of electrochemically active and inactive phases was discussed. Surface chemistry was investigated via X-ray photoelectron spectroscopy. Interaction between UV-laser radiation and the thin film material was analyzed through ablation experiments. Finally, to investigate the electrochemical properties, the manufactured thin film cathodes were cycled against a lithium anode. The formation of a solid electrolyte interphase on the cathode side was discussed.

  1. Synthesis and electrical properties of Ln2CuO4+ d (Ln: Nd or La) mixed conductor sputter deposited coatings

    OpenAIRE

    Briois, P.; de Oliveira, J.; Lapostolle, F.; Perry, F; Billard, A.; Cavaleiro, A

    2008-01-01

    Abstract Nd2CuO4 and La2CuO4 are potential candidates as cathode material for intermediate temperature-solid oxide fuel cells. Nd–Cu and La–Cu oxides were co-sputtered on rotating substrates from metallic La, Nd and Cu targets in the presence of a reactive argon–oxygen gas mixture. Structural and chemical features of these films have been determined by X-ray diffraction and energy-dispersive spectroscopy. Their electrical resistivity was measured using the four-point probe method. As-deposit...

  2. Preparation of nanocomposite thoriated tungsten cathode by swaging technique

    Institute of Scientific and Technical Information of China (English)

    王发展; 诸葛飞; 张晖; 丁秉钧

    2002-01-01

    By using the high energy ball milling method,the nanosized ThO2 powders were obtained.Through mixing powders,sintering and hot swaging processing,a nanocomposite thoriated tungsten cathode was fabricated.The relative density of the nanocomposite material is near 100%.The microstructure of nanocomposite cathode is quite different from that of conventional thoriated tungsten cathode.Most of thoria particles are less than 100 nm in diameter,and distribute on the boundaries of tungsten grains.The nanocomposite cathode shows a much lower arc starting field than that of conventional cathode,which will improve the performance of the cathode significantly.

  3. Close cathode chamber: Low material budget MWPC

    International Nuclear Information System (INIS)

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

  4. A model of dispenser cathode activity

    Science.gov (United States)

    Lamartine, B. C.; Eyink, K. G.; Czarnecki, J. V.; Lampert, W. V.; Haas, T. W.

    1985-12-01

    A semiquantitative model of dispenser cathode activity based on recent work on the co-adsorption of Ba and O onto W surfaces is presented. The co-adsorption studies have determined the shape of a three-dimensional surface of work function as a function of θO and θBa, the surface coverages of O and Ba, respectively. Compositions of a variety of pedigreed dispenser cathodes were fitted to this surface and their composition changes during lifetime were modeled. Changes of surface composition with temperature and of workfunction, φ, with temperature were also found to fit these curves. The concept of a patchy surface implied by the co-adsorption measurements was used to explain earlier results on the shape of the X-ray excited Ba MNN Auger feature. Finally, SIMS measurements under UHV conditions was found to provide an extremely sensitive measurement of surface composition in the region of surface coverages of interest in the study of cathode phenomena. Extensions of this work to other types of cathodes such as M-types, and rhenium substrate cathodes is also discussed.

  5. DUHOCAMIS: a dual hollow cathode ion source for metal ion beams.

    Science.gov (United States)

    Zhao, W J; Müller, M W O; Janik, J; Liu, K X; Ren, X T

    2008-02-01

    In this paper we describe a novel ion source named DUHOCAMIS for multiply charged metal ion beams. This ion source is derived from the hot cathode Penning ion gauge ion source (JINR, Dubna, 1957). A notable characteristic is the modified Penning geometry in the form of a hollow sputter electrode, coaxially positioned in a compact bottle-magnetic field along the central magnetic line of force. The interaction of the discharge geometry with the inhomogeneous but symmetrical magnetic field enables this device to be operated as hollow cathode discharge and Penning discharge as well. The main features of the ion source are the very high metal ion efficiency (up to 25%), good operational reproducibility, flexible and efficient operations for low charged as well as highly charged ions, compact setup, and easy maintenance. For light ions, e.g., up to titanium, well-collimated beams in the range of several tens of milliamperes of pulsed ion current (1 ms, 10/s) have been reliably performed in long time runs. PMID:18315181

  6. Sheet Plasma Produced by Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    张龙; 张厚先; 杨宣宗; 冯春华; 乔宾; 王龙

    2003-01-01

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field.The plasma is about 40cm in length,4 cm in width and 1cm in thickness.The electron density is about 108cm-3.The hollow cathode is made to be shallow with a large opening,which is different from the ordinary deep hollow cathode.A Langmuir probe is used to detect the plasma.The electron density and the spatial distribution of the plasma change when voltage,pressure and the magnetic field vary.A peak and a data fluctuation at about 200 G-300 G are observed in the variation of electron density(or thickness of the sheet plasma)with the magnetic field.Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable.

  7. Sheet plasma produced by hollow cathode discharge

    International Nuclear Information System (INIS)

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field. The plasma is about 40 cm in length, 4 cm in width and 1 cm in thickness. The electron density is about 108 cm-3. The hollow cathode is made to be shallow with a large opening, which is different from the ordinary deep hollow cathode. A Langmuir probe is used to detect the plasma. The electron density and the spatial distribution of the plasma change when voltage, pressure and the magnetic field vary. A peak and a data fluctuation at about 200 G - 300 G are observed in the variation of electron density (or thickness of the sheet plasma) with the magnetic field. Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable

  8. Advanced rechargeable sodium batteries with novel cathodes

    Science.gov (United States)

    Di Stefano, S.; Ratnakumar, B. V.; Bankston, C. P.

    1990-01-01

    Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 W h/kg theoretical). Energy densities in excess of 180 W h/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Various new cathode materials are presently being evaluated for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far, the studies have focussed on alternative metal chlorides such as CuCl2 and organic cathode materials such as TCNE.

  9. Cathodic protection in simulated geothermal environments

    Energy Technology Data Exchange (ETDEWEB)

    Bandy, R.; van Rooyen, D.

    1983-01-01

    The results of cathodic protection of carbon steel and AISI Type 316 stainless steel in simulated geothermal brines are described. Impressed current tests on carbon steel and stainless steel were conducted under controlled potential, and cathodic protection of carbon steel using zinc sacrificial anodes was studied by monitoring the galvanic current and potential of the couple with a zero-resistance ammeter. Weight-loss measurements and photomicrographs of test coupons were taken whenever necessary to determine the nature of attack and degree of protection. Tests were generally conducted at 90/sup 0/C. However, some tests on carbon steel were conducted up to 150/sup 0/C in a titanium autoclave. Results show that the weight loss of carbon steel can be reduced significantly and the pitting corrosion of the stainless steel can be prevented by shifting the potentials of the metals 60 to 80 mV cathodic to their respective open-circuit potentials.

  10. A porous metal cathode (a thermoemission converter)

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, V.I.; Avdeyev, V.Ye.

    1983-01-01

    The porous metallic cathode, which contains a body and the basic sponge attached to it with an active substance, made in the form of a base with an emitting projection, is distinguished by the fact that in order to increase the service life of the cathode, the based sponges on the side opposite the projection have a groove in which the replenishing chamber made of a difficulty fusible metal and filled with a mixture of tungsten and an active substance with a porosity of 35 to 80 percent which is open towards the projection is positioned, where the transverse cross section of the replenishing chamber intersects the transverse cross section of the projection, while the porosity of the basic sponge is 24 to 26 percent. The cathode is distinguished by the fact that a screen made of a difficultly fusible metal is installed on the facial surface with an opening for the projection and is connected with the body and with this surface.

  11. Improvements in cathodic protection using decoupling methods

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, Mauro [IEC - Instalacoes e Engenharia de Corrosao Ltda., Rio de Janeiro, RJ (Brazil); Tachick, Michael [Dairyland Electrical Industries, Inc., Stoughton, WI (United States)

    2005-07-01

    Proper cathodic protection on a structure requires electrical isolation in order to minimize the CP current required, and to shift the voltage of the structure to acceptable levels. This can be difficult to achieve when bonds or grounds connect the structure to other metallic structures of a different galvanic potential. Electrical decoupling methods are available that can provide the needed DC isolation while conducting any AC components to ground, and therefore address the cathodic protection effects while mitigating AC, if present. Substantial improvements in cathodic protection levels, and a reduction in required current, are common results. If the decoupling methods used are rated for the system conditions and are of a fail-safe design, the system can safely address user concerns about AC fault and lightning effects, and can be used in electrical grounding systems. (author)

  12. Why palladium cathodes can bear resistance to methanol but not platinum cathodes

    International Nuclear Information System (INIS)

    Methanol crossover on the cathodes causes significant performance loss in direct methanol fuel cells, and the parasitic current induced by the electrochemical oxidation of methanol on the cathodes is believed to be the cause. Palladium cathodes are known to bear resistance to methanol but not platinum cathodes. By means of the density functional theory (DFT), the distorted molecular structure of the adsorbed methanol on platinum was revealed, and this distorted molecular structure indicates that platinum makes methanol has a tendency toward the elimination of the first hydrogen (involved in the first step of electrochemical oxidation of methanol) in electric neutrality, and loss of an electron can reinforce this tendency. However, palladium cannot distort the molecular structure of the adsorbed methanol, even in the loss of electron condition. The activation energies and the reaction energies calculated by means of DFT also show that after losing an electron, the elimination of the first hydrogen on platinum is more kinetically and thermodynamically favourable than that on palladium. These computational results can explain the experimental findings that no parasitic current is induced at palladium cathodes, but not at platinum cathodes; therefore, palladium cathodes have a methanol-resistance property

  13. Reactive sputter deposition of boron nitride

    International Nuclear Information System (INIS)

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied -300 V dc bias

  14. Coating metals on micropowders by magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Magnetron sputtering was used to coat various metals on micropowder surfaces. By using this method, the fine particles are better dispersed and can therefore be coated more homogeneously. The micro-powders used include cenospheres from fly ash of coal-burning electric power plants (diameter 40-200 μm and particle density 0.7±0.1 g/cm3), as well as carborundum particles of different sizes. Aluminum, silver, copper, cobalt and nickel were used as the coating metals. Tests showed that the coated metal film was compact adhering tightly on the base powders, and the coated powders possess adequate flow properties.

  15. Niobium sputter-coated copper resonators

    CERN Document Server

    Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Durand, C; Peck, M A; Russo, R; Valente, A M

    1998-01-01

    Niobium sputter-coated copper resonators are successfully employed in operating particle accelerators, the most outstanding example being LEP2 at CERN. In this review we present recent progress in the understanding of the basic principles governing their behaviour, based on an extensive R&D programme carried out at CERN on 1.5 GHz resonators operated in the TM010 mode. At the present stage of the s tudy, no fundamental limitation has been found which would prevent the use of this technology for future high-field, high-Q accelerating cavities.

  16. Synchrotron Investigations of SOFC Cathode Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Idzerda, Yves

    2013-09-30

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

  17. DARHT 2 kA Cathode Development

    International Nuclear Information System (INIS)

    In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more than 10 A/cm2 of current density (corresponding to 2 kA of total beam current) at our operating conditions. Instead the measured emission (space charge limited) was 6 A/cm2. The result was similar even after we had revised the activation and handling procedures to adhere more closely to the recommend steps (taking longer time and nonstop to do the out-gassing). Vacuum was a major concern in considering the cathode's performance. Although the vacuum gauges at the injector vessel indicated 10-8 Torr, the actual vacuum condition near the cathode in the central region of the vessel, where there might be significant out-gassing from the heater region, was never determined. Poor vacuum at the surface of the cathode degraded the emission (by raising the work function value). We reexamined all

  18. Hollow-Cathode Source Generates Plasma

    Science.gov (United States)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  19. DARHT 2 kA Cathode Development

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-03-09

    In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more than 10 A/cm{sup 2} of current density (corresponding to 2 kA of total beam current) at our operating conditions. Instead the measured emission (space charge limited) was 6 A/cm{sup 2}. The result was similar even after we had revised the activation and handling procedures to adhere more closely to the recommend steps (taking longer time and nonstop to do the out-gassing). Vacuum was a major concern in considering the cathode's performance. Although the vacuum gauges at the injector vessel indicated 10{sup -8} Torr, the actual vacuum condition near the cathode in the central region of the vessel, where there might be significant out-gassing from the heater region, was never determined. Poor vacuum at the surface of the cathode degraded the emission (by raising the work function

  20. Cathode architectures for alkali metal / oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-13

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

  1. Ferroelectric Cathodes in Transverse Magnetic Fields

    International Nuclear Information System (INIS)

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

  2. Process For Patterning Dispenser-Cathode Surfaces

    Science.gov (United States)

    Garner, Charles E.; Deininger, William D.

    1989-01-01

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

  3. Gas poisoning investigations of scandate and M-type dispenser cathodes

    Science.gov (United States)

    Shao, Wensheng; Zhang, Ke; Li, Ji; Yan, Suqiu; Chen, Qilue

    2003-06-01

    Gas poisoning tests of cathode emission were carried out with four kinds of thermal cathodes: W+Sc 2O 3 mixed matrix cathode, impregnated scandate cathode, Ir-coated cathode, Os-coated cathode. As a result, M-type cathodes are more sensitive to O 2, but can recover absolutely in a short time; scandate-type cathodes react slowly and recover partly after a long time. Compared to O 2, ambient air leaked into the vacuum chamber has a smaller influence on the cathode emission; H 2 has a little effect of activation on the four cathodes, especially on the Os-coated cathode.

  4. Density effects in sputtering at normal and oblique ion bombardment

    International Nuclear Information System (INIS)

    The author's earlier work on computer simulation of density effects in sputtering is extended to higher energies and oblique incidence of bombarding ions. Sputtering of amorphous Ge with an artificially varied density by 0.05-100 keV Ar ions is considered in great detail and the influence of density on the yield, angular and energy distributions of sputtered atoms is analysed. It is shown that at normal incidence the sputtering yield increases with density as Np, where p=0.56, 0.43, 0.28 and 0.24 at E0=0.1, 1, 10 and 100 keV, respectively. At grazing incidence the sputtering yield is a decreasing function of N due to surface scattering of bombarding ions (the negative density effect). This finding lent impetus to a successful search for the density effects in sputtering of different elemental targets at grazing bombardment. Overall, the effects of density on the main sputtering characteristics turn out to be significant, which contrasts with the predictions of a number of analytical theories of sputtering

  5. Sputtering of solid nitrogen by keV helium ions

    DEFF Research Database (Denmark)

    Ellegaard, O.; Schou, Jørgen; Sørensen, H.; Pedrys, R.; Warczak, B.

    Solid nitrogen has become a standard material among the frozen molecular gases for electronic sputtering. We have combined measurements of sputtering yields and energy spectra from nitrogen bombarded by 4-10 keV helium ions. The data show that the erosion is electronic rather than knockon...

  6. Sputtering of solid nitrogen by keV helium ions

    DEFF Research Database (Denmark)

    Ellegaard, O.; Schou, Jørgen; Sørensen, H.;

    1993-01-01

    Solid nitrogen has become a standard material among the frozen molecular gases for electronic sputtering. We have combined measurements of sputtering yields and energy spectra from nitrogen bombarded by 4-10 keV helium ions. The data show that the erosion is electronic rather than knockon...

  7. Nano-Particle Scandate Cathode for Space Communications Project

    Data.gov (United States)

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

  8. Development of cathode material for lithium-ion batteries

    OpenAIRE

    Rustam Mukhtaruly Turganaly; Ivan Trussov; Andrey Petrovich Kurbatov

    2014-01-01

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

  9. Long Life Cold Cathodes for Hall effect Thrusters Project

    Data.gov (United States)

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

  10. A new dispenser cathode with dual-layer

    Science.gov (United States)

    Li, Yutao; Zhang, Honglai; Liu, Pukun; Zhang, Mingchen

    2005-09-01

    The emission and surface characteristics of the dispenser cathode coated with Os-W alloy and that coated with Os-W/Re are studied and compared. The dispenser cathode coated with Os-W/Re has been applied in electron gun measurement system for making measurement of higher emission current and life test. We called the cathode coated with Os-W/Re as the cathode with dual-layer. It is found that the dispenser cathode coated with dual-layer has higher current density than that coated only with Os-W alloy. After being activated, the cathode coated with dual-layer presents ternary composition on the surface of it. The W surface composition does not rise with time comparing with that of the cathode coated with Os-W alloy. In electron gun, the dispenser cathode coated with dual-layer has pulse current density of 30 A/cm 2 and life of more than 800 h.

  11. A new dispenser cathode with dual-layer

    International Nuclear Information System (INIS)

    The emission and surface characteristics of the dispenser cathode coated with Os-W alloy and that coated with Os-W/Re are studied and compared. The dispenser cathode coated with Os-W/Re has been applied in electron gun measurement system for making measurement of higher emission current and life test. We called the cathode coated with Os-W/Re as the cathode with dual-layer. It is found that the dispenser cathode coated with dual-layer has higher current density than that coated only with Os-W alloy. After being activated, the cathode coated with dual-layer presents ternary composition on the surface of it. The W surface composition does not rise with time comparing with that of the cathode coated with Os-W alloy. In electron gun, the dispenser cathode coated with dual-layer has pulse current density of 30 A/cm2 and life of more than 800 h

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

    Science.gov (United States)

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

    2014-02-01

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

  13. Sputtering at grazing ion incidence: Influence of adatom islands

    International Nuclear Information System (INIS)

    When energetic ions impinge at grazing incidence onto an atomically flat terrace, they will not sputter. However, when adatom islands (containing N atoms) are deposited on the surface, they induce sputtering. We investigate this effect for the specific case of 83 deg. -incident 5 keV Ar ions on a Pt (111) surface by means of molecular-dynamics simulation and experiment. We find that - for constant coverage Θ - the sputter yield has a maximum at island sizes of N congruent with 10-20. A detailed picture explaining the decline of the sputter yield toward larger and smaller island sizes is worked out. Our simulation results are compared with dedicated sputtering experiments, in which a coverage of Θ=0.09 of Pt adatoms are deposited onto the Pt (111) surface and form islands with a broad distribution around a most probable size of N congruent with 20.

  14. Optimized high-temperature cathode-heating unit

    International Nuclear Information System (INIS)

    Description of structure and test results of cathode-heating unit for electron accelerators are presented. In the given cathode unit LaB6 cathode area is enlarged, efficient heat isolations are used, heating element stiffness and strength are increased. Compact shild packets are used in a cathode unit. The heating element is made in the form of concentric rings. The unit heat efficiency is >80%, nonisothermality ΔT2 emitter area at T=2050 K constituted 700 h

  15. Feature of "Cold" Fusion Reaction in a Deuterated Complex Cathode

    OpenAIRE

    ARATA, Yoshiaki; ZHANG, Yue-Chang

    1992-01-01

    [Abstract] In order to corroborate the evidence of "cold" fusion reaction, a new-type, complex cathode was developed, consisting of a Ni rod with a Pd layer applied by plasma spraying. High reproducibility of a "cold" fusion reaction was confirmed, using a deuterated complex cathode. The Pd layer showed to have activated the surface functions of the deuterated cathode, and a reliable evidence was obtained that a new type of heat generation occurred in the complex cathode.

  16. Photothermal cathode measurements at the Advanced Photon Source

    International Nuclear Information System (INIS)

    The Advanced Photon Source (APS) ballistic bunch compression (BBC) gun in the Injector Test Stand (ITS) presently uses an M-type thermionic dispenser cathode as a photocathode. This photothermal cathode offers substantial advantages over conventional metal photocathodes, including easy replacement and easy cleaning via the cathode's built-in heater. We present the results of photoemission measurements as a function of cathode heater power, laser pulse energy, and applied rf field strength.

  17. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson

    2000-03-31

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

  18. On reactive high power impulse magnetron sputtering

    Science.gov (United States)

    Gudmundsson, J. T.

    2016-01-01

    High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition (IPVD) technique that is particularly promising for reactive sputtering applications. However, there are few issues that have to be resolved before the full potential of this technique can be realized. Here we give an overview of the key experimental findings for the reactive HiPIMS discharge. An increase in the discharge current is commonly observed with increased partial pressure of the reactive gas or decreased repetition pulse frequency. There are somewhat conflicting claims regarding the hysteresis effect in the reactive HiPIMS discharge as some report reduction or elimination of the hysteresis effect while others claim a feedback control is essential. The ion energy distribution of the metal ion and the atomic ion of the reactive gas are similar and extend to very high energies while the ion energy distribution of the working gas and the molecular ion of the reactive gas are similar and are much less energetic.

  19. Development of Magnetic Hollow Cold Cathode for Ion Source

    OpenAIRE

    Djamel Boubetra; Bouafia, M.

    2008-01-01

    The research presented in this study focuses on the development of ion source with hollow cold cathodes which supplies low-power and high ion-current density applications. The theoretical and experimental results were used to design a second-generation laboratory model, low-current hollow cathode. Present experiment is to design a hollow cold cathode with two application possibilities.

  20. High-voltage virtual-cathode microwave simulations

    Energy Technology Data Exchange (ETDEWEB)

    Thode, L.; Snell, C.M.

    1991-01-01

    In contrast to a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential is sufficiently large to cause electron reflection. The region associated with electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and by reflexing electrons trapped in the potential well formed between the real and virtual cathodes. A virtual-cathode device based on the first mechanism is a vircator while one based on latter mechanism is a reflex diode. A large number of low-voltage virtual-cathode microwave configurations have been investigated. Initial simulations of a high-voltage virtual-cathode device using a self-consistent particle-in-cell code indicated reasonable conversion efficiency with no frequency chirping. The nonchirping character of the high-voltage virtual-cathode device lead to the interesting possibility of locking four very-high-power microwave devices together using the four transmission lines available at Aurora. Subsequently, in support of two high-voltage experiments, simulations were used to investigate the effect of field-emission threshold and velvet position on the cathode; anode and cathode shape; anode-cathode gap spacing; output waveguide radius; diode voltage; a cathode-coaxial-cavity resonator; a high-frequency ac-voltage drive; anode foil scattering and energy loss; and ion emission on the microwave frequency and power. Microwave

  1. Radial profiles of electron density and current components at cathode surface in LaB6 hollow cathode arc

    International Nuclear Information System (INIS)

    Experimental studies on a hydrogen-fed LaB6 hollow cathode arc have been pursued. The plasma parameter in the cathode has been measured by a Langmuir probe. The radial variation in the electron density inside the cathode was calculated using the continuity and momentum equations, showing good agreement with the experimental results. The electron density at the cathode surface was estimated to be 15 % - 20 % of that at the cathode axis. It was also found from the current balance that the arc current components at the cathode surface consist of a thermionic current which takes into account the Schottky effect, the ion current and the secondary electron current induced by ion bombardment. The ion current and the cathode surface is larger than the electron current emitted from the cathode. (author)

  2. Sputtering effect of low-energy ions on biological target: The analysis of sputtering product of urea and capsaicin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lili [Key Laboratory of Ion Beam Bio-Engineering, Institute of Technical Biology and Agriculture Engineering of Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031 (China); Xu, Xue [Rice Research Institute, Anhui Academy of Agricultural Sciences, Nongke South Road 40, Hefei 230031 (China); Wu, Yuejin, E-mail: yjwu@ipp.ac.cn [Key Laboratory of Ion Beam Bio-Engineering, Institute of Technical Biology and Agriculture Engineering of Chinese Academy of Sciences, Shushanhu Road 350, Hefei 230031 (China)

    2013-08-01

    Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles. Recent years, ion implantation was successfully applied to biological research based on the fragments sputtering and form open paths in cell structure caused by ion sputtering. In this study, we focused on urea and chilli pepper pericarp samples implanted with N{sup +} and Ar{sup +} ions. To investigate the sputtering effect, we designed a collecting unit containing a disk sample and a glass pipe. The urea content and capsaicin content recovered from glass pipes were adopted to represent the sputtering product. The result of urea showed that the sputtering effect is positively correlated with the ion energy and dose, also affected by the ion type. The result of capsaicin was different from that of urea at 20 keV and possibly due to biological complex composition and structure. Therefore the sputtering yield depended on both the parameters of incident ions and the state of target materials. The sputtering yield of urea was also simulated by computational method achieved through the TRIM program. The trajectories of primary and recoiled atoms were calculated on the basis of the binary collision approximation using Monte Carlo method. The experimental results were much higher than the calculated results. The possible explanation is that in the physical model the target were assumed as a disordered lattice and independent atoms, which is much less complicated than that of the biological models.

  3. Sputtering effect of low-energy ions on biological target: The analysis of sputtering product of urea and capsaicin

    Science.gov (United States)

    Zhang, Lili; Xu, Xue; Wu, Yuejin

    2013-08-01

    Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles. Recent years, ion implantation was successfully applied to biological research based on the fragments sputtering and form open paths in cell structure caused by ion sputtering. In this study, we focused on urea and chilli pepper pericarp samples implanted with N+ and Ar+ ions. To investigate the sputtering effect, we designed a collecting unit containing a disk sample and a glass pipe. The urea content and capsaicin content recovered from glass pipes were adopted to represent the sputtering product. The result of urea showed that the sputtering effect is positively correlated with the ion energy and dose, also affected by the ion type. The result of capsaicin was different from that of urea at 20 keV and possibly due to biological complex composition and structure. Therefore the sputtering yield depended on both the parameters of incident ions and the state of target materials. The sputtering yield of urea was also simulated by computational method achieved through the TRIM program. The trajectories of primary and recoiled atoms were calculated on the basis of the binary collision approximation using Monte Carlo method. The experimental results were much higher than the calculated results. The possible explanation is that in the physical model the target were assumed as a disordered lattice and independent atoms, which is much less complicated than that of the biological models.

  4. Sputtering effect of low-energy ions on biological target: The analysis of sputtering product of urea and capsaicin

    International Nuclear Information System (INIS)

    Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles. Recent years, ion implantation was successfully applied to biological research based on the fragments sputtering and form open paths in cell structure caused by ion sputtering. In this study, we focused on urea and chilli pepper pericarp samples implanted with N+ and Ar+ ions. To investigate the sputtering effect, we designed a collecting unit containing a disk sample and a glass pipe. The urea content and capsaicin content recovered from glass pipes were adopted to represent the sputtering product. The result of urea showed that the sputtering effect is positively correlated with the ion energy and dose, also affected by the ion type. The result of capsaicin was different from that of urea at 20 keV and possibly due to biological complex composition and structure. Therefore the sputtering yield depended on both the parameters of incident ions and the state of target materials. The sputtering yield of urea was also simulated by computational method achieved through the TRIM program. The trajectories of primary and recoiled atoms were calculated on the basis of the binary collision approximation using Monte Carlo method. The experimental results were much higher than the calculated results. The possible explanation is that in the physical model the target were assumed as a disordered lattice and independent atoms, which is much less complicated than that of the biological models

  5. The double sheath on cathodes of discharges burning in cathode vapour

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M S; Benilova, L G [Departamento de Fisica, Universidade da Madeira, Largo do MunicIpio, 9000 Funchal (Portugal)

    2010-09-01

    The model of a collisionless near-cathode space-charge sheath with ionization of atoms emitted by the cathode surface is considered. Numerical calculations showed that the mathematical problem is solvable and its solution is unique. In the framework of this model, the sheath represents a double layer with a potential maximum, with the ions which are produced before the maximum returning to the cathode surface and those produced after the maximum escaping into the plasma. Numerical results are given in a form to be readily applicable in analysis of discharges burning in cathode vapour, such as vacuum arcs. In particular, the results indicate that the ion backflow coefficient in such discharges exceeds 0.5, in agreement with values extracted from the experiment.

  6. Barium depletion in hollow cathode emitters

    International Nuclear Information System (INIS)

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values

  7. Renovation of the cathodic protection system

    NARCIS (Netherlands)

    Schuten, G.; Leggedoor, J.; Polder, R.B.; Peelen, W.H.A.

    2003-01-01

    The first system for Cathodic Protection of concrete in the Netherlands was applied to a one bicycle lane of a bridge suffering corrosion due to de-icing salt penetration in 1986. This CP system was based on the Ferex 100S conducting polymer cable anode in a cementitious overlay. Its functioning was

  8. Barium depletion in hollow cathode emitters

    Energy Technology Data Exchange (ETDEWEB)

    Polk, James E., E-mail: james.e.polk@jpl.nasa.gov; Mikellides, Ioannis G.; Katz, Ira [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Capece, Angela M. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States)

    2016-01-14

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al{sub 2}O{sub 3} source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  9. Barium depletion in hollow cathode emitters

    Science.gov (United States)

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

    2016-01-01

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  10. Improved cathodes for a dense plasma focus

    International Nuclear Information System (INIS)

    A series of modified cathodes have been tested in our ultra-high vacuum dense plasma focus (DPF) device in an effort to improve both neutron output and shot-to-shot reproducibility. Inspiration for these modifications originated from time resolved photographs of the initial current sheet as it approaches the cathode. In particular, the current sheet develops a slight annular protrusion, or ''bump'', that contacts the inside wall of the cathode at a distance from the breach approximately coincident with the end of the insulator. In an attempt to take advantage of this protrusion, a series of modified cathodes was provided with a decreased waist diameter in the vicinity of the end of the insulator. As previously discussed, this DPF device is constructed from high vacuum components using metal-to-metal and ceramic (Al2O3)-to-metal seals; the entire assembly is given a vacuum bake at 2500C resulting in a pre-fill vacuum of approx. =5 x 10-9 Torr. The DPF is powered by a 7 μf capacitor bank. The short circuit ringing frequency is 412 kHz corresponding to a free circuit inductance of 21 nH. With the DPF in operation at 20 kV, a current peak of 200 kA occurs at 0.8 μs. Neutron output was measured side on with a silver activation counter, and end on with an arsenic activation counter

  11. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

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

  12. Production of rare-earth atomic negative ion beams in a cesium-sputter-type negative ion source

    International Nuclear Information System (INIS)

    The desire to study negative ion structure and negative ion-photon interactions has spurred the development of ion sources for use in research and industry. The many different types of negative ion sources available today differ in their characteristics and abilities to produce anions of various species. Thus the importance of choosing the correct type of negative ion source for a particular research or industrial application is clear. In this study, the results of an investigation on the production of beams composed of negatively-charged rare-earth ions from a cylindrical-cathode-geometry, cesium-sputter-type negative ion source are presented. Beams of atomic anions have been observed for most of the first-row rare-earth elements, with typical currents ranging from hundreds of picoamps to several nanoamps

  13. Preparation and characterization of SOFC cathode films

    International Nuclear Information System (INIS)

    Solid Oxide Fuel Cells (SOFC) are being widely studied due to their possible utilization to produce electrical energy in a wide power range (from 1 kW up to few hundreds of kW).The principle of operation of this kind of fuel cells involves reduction of O2 in the cathode oxygen ions (O2-) diffusion of oxygen through the electrolyte and fuel oxidation in the anode.Commercial SOFC must work at temperature higher than to 1000 degree C to enable the O2- diffusion.Therefore, it is necessary to investigate new materials that enable to decrease the operation temperature, improving SOFC performance and cost. La1-xSrxCo1-yFeyO3-δ (LSCF) perovskites are good candidates for SOFC cathodes because these materials present high ionic and electronic conductivity. LSCF cathodes are adequate to fabricate Ce1-xGdxO2-δ electrolyte SOFC due to its low chemical reactivity with this material and its similar thermal expansion coefficient. In this work we present a study of microstructural and electrochemical characteristics of films for SOFC cathodes. La0.4Sr0.6Co0.8Fe0.2O3-δ compounds were prepared by the acetate reaction method.Then, cathodes were deposited onto a Ce0.9Gd0.1O2-δ electrolyte disk by dip coating and spray techniques.Structural characterization is made by X-ray diffraction XRD and scanning electron microscopy (SEM).Electrochemical properties are characterized by complex impedance measurements.Finally, the relation between structural characteristics and electrical properties is discussed

  14. Explosive emission cathode on the base of carbon plastic fibre

    International Nuclear Information System (INIS)

    A fabrication process for explosive emission cathodes on the base of carbon plastic fibre of practically any geometrical shape and dimensions is developed. Experimental studies of electron beam current collection from cathodes, 2cm in diameter, at voltages across the diode of 10 and 150-250kV. It is shown that the ignition voltage for cathode plasma is ∼2kV at the interelectrode diode gap of 5mm and residual gas pressure of ∼5x10-5Torr. The carbon-fibre cathode, fabricated in this way, provides more stable current collection of an electron beam (without oscillations) than other cathodes

  15. Structure adhesion and corrosion resistance study of tungsten bisulfide doped with titanium deposited by DC magnetron co-sputtering

    International Nuclear Information System (INIS)

    Highlights: • Ti-doped WS2 films were grown via the magnetron co-sputtering technique. • At a high Ti percentage, the crystalline structure of WS2 coatings tends to be amorphous. • As the Ti percentage increases in WS2 coatings, nanocomposites tend to form. • Ti-doped WS2 films have elastic behavior compared with the plastic response of pure WS2 films. • A high Ti percentage increases the corrosion resistance of WS2 films. - Abstract: Titanium-doped tungsten bisulfide thin films (WS2-Ti) were grown using a DC magnetron co-sputtering technique on AISI 304 stainless steel and silicon substrates. The films were produced by varying the Ti cathode power from 0 to 25 W. Using energy dispersive spectroscopy (EDS), the concentration of Ti in the WS2 was determined, and a maximum of 10% was obtained for the sample grown at 25 W. Moreover, the S/W ratio was calculated and determined to increase as a function of the Ti cathode power. According to transmission electron microscopy (TEM) results, at high titanium concentrations (greater than 6%), nanocomposite formation was observed, with nanocrystals of Ti embedded in an amorphous matrix of WS2. Using the scratch test, the coatings’ adhesion was analyzed, and it was observed that as the Ti percentage was increased, the critical load (Lc) also increased. Furthermore, the failure type changed from plastic to elastic. Finally, the corrosion resistance was evaluated using the electrochemical impedance spectroscopy (EIS) technique, and it was observed that at high Ti concentrations, the corrosion resistance was improved, as Ti facilitates coating densification and generates a protective layer

  16. Near-threshold sputtering of MoSi2

    International Nuclear Information System (INIS)

    This paper presents a comprehensive experimental, theoretical and computer simulation study of very low-energy (3-35 eV) argon ion sputtering of β-MoSi2 (0 0 0 1). Modification of MoSi2 surface composition under low-energy ion bombardment was studied by Auger electron spectroscopy (AES) and X-ray photoelectronic spectroscopy (XPS). The detected changes of surface composition were attributed to preferential sputtering combined with threshold effects. To verify the interpretation, an analytical theory of near-threshold sputtering of compounds is developed which provides a general relation between the sputter threshold energy of target atoms on one side and their atomic masses, surface-binding energies as well with the ion atomic mass on the other side. Elementary mechanisms of near-threshold sputtering are found from the theory and molecular dynamics simulation for MoSi2. Threshold energies for various mechanisms of Mo and Si sputtering are calculated and used to explain the experimental evidence. From results of the work it is concluded that the experimental study of surface composition changes after near-threshold sputtering provides a radically new approach to investigate surface binding in compounds

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

    Science.gov (United States)

    Watson, Valerie J.; Saito, Tomonori; Hickner, Michael A.; Logan, Bruce E.

    2011-03-01

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

  18. Emission current control system for multiple hollow cathode devices

    Science.gov (United States)

    Beattie, John R. (Inventor); Hancock, Donald J. (Inventor)

    1988-01-01

    An emission current control system for balancing the individual emission currents from an array of hollow cathodes has current sensors for determining the current drawn by each cathode from a power supply. Each current sensor has an output signal which has a magnitude proportional to the current. The current sensor output signals are averaged, the average value so obtained being applied to a respective controller for controlling the flow of an ion source material through each cathode. Also applied to each controller are the respective sensor output signals for each cathode and a common reference signal. The flow of source material through each hollow cathode is thereby made proportional to the current drawn by that cathode, the average current drawn by all of the cathodes, and the reference signal. Thus, the emission current of each cathode is controlled such that each is made substantially equal to the emission current of each of the other cathodes. When utilized as a component of a multiple hollow cathode ion propulsion motor, the emission current control system of the invention provides for balancing the thrust of the motor about the thrust axis and also for preventing premature failure of a hollow cathode source due to operation above a maximum rated emission current.

  19. Scenario for Hollow Cathode End-Of-Life

    Science.gov (United States)

    Sarver-Verhey, Timothy R.

    2000-01-01

    Recent successful hollow cathode life tests have demonstrated that lifetimes can meet the requirements of several space applications. However, there are no methods for assessing cathode lifetime short of demonstrating the requirement. Previous attempts to estimate or predict cathode lifetime were based on relatively simple chemical depletion models derived from the dispenser cathode community. To address this lack of predicative capability, a scenario for hollow cathode lifetime under steady-state operating conditions is proposed. This scenario has been derived primarily from the operating behavior and post-test condition of a hollow cathode that was operated for 28,000 hours. In this scenario, the insert chemistry evolves through three relatively distinct phases over the course of the cathode lifetime. These phases are believed to correspond to demonstrable changes in cathode operation. The implications for cathode lifetime limits resulting from this scenario are examined, including methods to assess cathode lifetime without operating to End-of- Life and methods to extend the cathode lifetime.

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

    KAUST Repository

    Watson, Valerie J.

    2011-03-01

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

  1. Cathode scraper system and method of using the same for removing uranium

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-03

    Embodiments include a cathode scraper system and/or method of using the same for removing uranium. The cathode scraper system includes a plurality of cathode assemblies. Each cathode assembly includes a plurality of cathode rods. The cathode scraper system also includes a cathode scraper assembly configured to remove purified uranium deposited on the plurality of cathode rods. The cathode scraper assembly includes a plurality of scrapers arranged in a lattice, and each scraper of the plurality of scrapers is arranged to correspond to a different cathode rod.

  2. Design of ANSYS-based Cathode with Complex Groove

    Institute of Scientific and Technical Information of China (English)

    范植坚; 赵刚刚; 张丽娟

    2012-01-01

    The profile of cathode with complex groove needs to be modified time after time during design of electrochemical machining (ECM) cathode.A design scheme using finite element method (FEM) for cathode with complex profile is put forward to shorten the period of cathode design.Based on Laplace equation,the potential distribution on parameter-transformation model was calculated by using ANSYS,which is compared to the potential distribution calculated by substituting conductivity and current efficiency into Laplace equation.According to the difference between the results calculated and simulated by ANSYS,the cathode profile was modified by adjusting the cathode boundary.The experiments show that the dimensions and shape of workpiece machined by numerically simulated cathode conform well with the blueprint.

  3. Emission mechanism in high current hollow cathode arcs

    International Nuclear Information System (INIS)

    Large (2 cm-diameter) hollow cathodes have been operated in a magnetoplasmadynamic (MPD) arc over wide ranges of current (0.25 to 17 kA) and mass flow (10-3 to 8 g/sec), with orifice current densities and mass fluxes encompassing those encountered in low current steady-state hollow cathode arcs. Detailed cathode interior measurements of current and potential distributions show that maximum current penetration into the cathode is about one diameter axially upstream from the tip, with peak inner surface current attachment up to one cathode diameter upstream of the tip. The spontaneous attachment of peak current upstream of the cathode tip is suggested as a criterion for characteristic hollow cathode operation. This empirical criterion is verified by experiment

  4. Cathode R&D for Future Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, D.H.; /SLAC; Bazarov, I.; Dunham, B.; /Cornell U., CLASSE; Harkay, K.; /Argonne; Hernandez-Garcia; /Jefferson Lab; Legg, R.; /Wisconsin U., SRC; Padmore, H.; /LBL, Berkeley; Rao, T.; Smedley, J.; /Brookhaven; Wan, W.; /LBL, Berkeley

    2010-05-26

    This paper reviews the requirements and current status of cathodes for accelerator applications, and proposes a research and development plan for advancing cathode technology. Accelerator cathodes need to have long operational lifetimes and produce electron beams with a very low emittance. The two principal emission processes to be considered are thermionic and photoemission with the photocathodes being further subdivided into metal and semi-conductors. Field emission cathodes are not included in this analysis. The thermal emittance is derived and the formulas used to compare the various cathode materials. To date, there is no cathode which provides all the requirements needed for the proposed future light sources. Therefore a three part research plan is described to develop cathodes for these future light source applications.

  5. Intrinsic stress analysis of sputtered carbon film

    Institute of Scientific and Technical Information of China (English)

    Liqin Liu; Zhanshan Wang; Jingtao Zhu; Zhong Zhang; Moyan Tan; Qiushi Huang; Rui Chen; Jing Xu; Lingyan Chen

    2008-01-01

    Intrinsic stresses of carbon films deposited by direct current (DC) magnetron sputtering were investigated.The bombardments of energetic particles during the growth of films were considered to be the main reason for compressive intrinsic stresses.The values of intrinsic stresses were determined by measuring the radius of curvature of substrates before and after film deposition.By varying argon pressure and target-substrate distance,energies of neutral carbon atoms impinging on the growing films were optimized to control the intrinsic stresses level.The stress evolution in carbon films as a function of film thickness was investigated and a void-related stress relief mechanism was proposed to interpret this evolution.

  6. Magnetization relaxation in sputtered thin permalloy films

    Science.gov (United States)

    Oliveira, R. C.; Rodríguez-Suárez, R. L.; Aguiar, F. M. De; Rezende, S. M.; Fermin, J. R.; Azevedo, A.

    2004-05-01

    In order to understand the underlying phenomena of magnetization damping in metallic thin films, samples of permalloy films were grown by magnetron sputtering, and their 8.6-GHz ferromagnetic resonance linewidth ΔH has been measured as a function of the Permalloy (Py) film thickness t, at room temperature. We made samples of Py(t)/Si(001) and X/Py(t)/X/Si(001), with X=Pd (40Å), and Cr (25Å), with 20Å < t < 200Å. While ΔH scales with t-2 in the bare Py/Si series, it is shown that the damping behavior strongly depends on X in the sandwich samples.

  7. Analysis of magnetron sputtered boron oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Buc, Dalibor [Slovak University of Technology in Bratislava (Slovakia); Bello, Igor [City University of Hong Kong, Kowloon, Hong Kong (China); Caplovicova, Maria [Comenius University in Bratislava (Slovakia); Mikula, Milan; Kovac, Jaroslav; Hotovy, Ivan [Slovak University of Technology in Bratislava (Slovakia); Chong, Yat Min [City University of Hong Kong, Kowloon, Hong Kong (China); Siu, Guei Gu [City University of Hong Kong, Kowloon, Hong Kong (China)], E-mail: apggsiu@cityu.edu.hk

    2007-10-15

    Boron oxide films were grown on silicon substrates by radio-frequency (rf) unbalanced magnetron sputtering of a boron target in argon-oxygen gas mixtures with different compositions. Microscopic analyses show that overall boron oxide films are amorphous. The film prepared at oxygen/argon flow rate ratio > 0.05 developed large crystallites of boric acid in localize areas of amorphous boron oxide matrices. These crystallites were unstable and at electron microscopic analysis they continuously transformed to a cubic HBO{sub 2} phase and then completely vanished leaving an underlying amorphous boron oxide film behind. The analyses indicate the coexistence of B{sub 6}O, HBO{sub 2} crystallites and amorphous boron oxide matrices. Fourier transform infrared (FTIR) spectra revealed spectral bands of BOH, BO, BOB and BH groups. Nanohardness and elastic modulus of a film prepared at low oxygen concentration approach 30 and 300 GPa, respectively. These parameters however vary with deposition conditions.

  8. Laser micromachining of sputtered DLC films

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Y.Q. [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2, 1PZ (United Kingdom)]. E-mail: yf229@cam.ac.uk; Luo, J.K. [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2, 1PZ (United Kingdom); Flewitt, A.J. [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2, 1PZ (United Kingdom); Ong, S.E. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Zhang, S. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Milne, W.I. [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2, 1PZ (United Kingdom)

    2006-04-30

    DLC films with different thicknesses (from 100 nm to 1.9 {mu}m) were deposited using sputtering of graphite target in pure argon atmosphere without substrate heating. Film microstructures (sp{sup 2}/sp{sup 3} ratio) and mechanical properties (modulus, hardness, stress) were characterized as a function of film thickness. A thin layer of aluminum about 60 nm was deposited on the DLC film surface. Laser micromachining of Al/DLC layer was performed to form microcantilever structures, which were released using a reactive ion etching system with SF{sub 6} plasma. Due to the intrinsic stress in DLC films and bimorph Al/DLC structure, the microcantilevers bent up with different curvatures. For DLC film of 100 nm thick, the cantilever even formed microtubes. The relationship between the bimorph beam bending and DLC film properties (such as stress, modulus, etc.) were discussed in details.

  9. Laser micromachining of sputtered DLC films

    International Nuclear Information System (INIS)

    DLC films with different thicknesses (from 100 nm to 1.9 μm) were deposited using sputtering of graphite target in pure argon atmosphere without substrate heating. Film microstructures (sp2/sp3 ratio) and mechanical properties (modulus, hardness, stress) were characterized as a function of film thickness. A thin layer of aluminum about 60 nm was deposited on the DLC film surface. Laser micromachining of Al/DLC layer was performed to form microcantilever structures, which were released using a reactive ion etching system with SF6 plasma. Due to the intrinsic stress in DLC films and bimorph Al/DLC structure, the microcantilevers bent up with different curvatures. For DLC film of 100 nm thick, the cantilever even formed microtubes. The relationship between the bimorph beam bending and DLC film properties (such as stress, modulus, etc.) were discussed in details

  10. Performance evaluation of printed LiCoO2 cathodes with PVDF-HFP gel electrolyte for lithium ion microbatteries

    International Nuclear Information System (INIS)

    In order to improve the discharge capacity in lithium ion microbatteries, a thick-film cathode was fabricated by a screen printing using LiCoO2 pastes. The printed cathode showed a different discharge curves when the cell was tested using various (liquid, gel and solid-state) electrolytes. When a cell test was performed with organic liquid electrolyte, the maximum discharge capacity was 200 μAh cm-2, which corresponded to approximately 133 mAh g-1 when the loading weight of LiCoO2 was calculated. An all-solid-state microbattery could be assembled using sputtered LiPON electrolyte, an evaporated Li anode, and printed LiCoO2 cathode films without delamination or electrical problems. However, the highest discharge capacity showed a very small value (7 μAh cm-2). This problem could be improved using a poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) gel electrolyte, which enhanced the contact area and adhesion force between cathode and electrolyte. The discharge value of this cell was measured as approximately 164 μAh cm-2 (∼110 mAh g-1). As the PVDF-HFP electrolyte had a relatively soft contact property with higher ionic conductance, the cell performance was improved. In addition, the cell can be fabricated in a leakage-free process, which can resolve many safety problems. According to these results, there is a significant possibility that a film prepared using the aforementioned paste with screen printing and PVDF-HFP gel electrolyte is feasible for a microbattery

  11. Hydrogenated amorphous silicon deposited by ion-beam sputtering

    Science.gov (United States)

    Lowe, V. E.; Henin, N.; Tu, C.-W.; Tavakolian, H.; Sites, J. R.

    1981-01-01

    Hydrogenated amorphous silicon films 1/2 to 1 micron thick were deposited on metal and glass substrates using ion-beam sputtering techniques. The 800 eV, 2 mA/sq cm beam was a mixture of argon and hydrogen ions. The argon sputtered silicon from a pure (7.6 cm) single crystal wafer, while the hydrogen combined with the sputtered material during the deposition. Hydrogen to argon pressure ratios and substrate temperatures were varied to minimize the defect state density in the amorphous silicon. Characterization was done by electrical resistivity, index of refraction and optical absorption of the films.

  12. Lattice dynamics during electronic sputtering of solid Ne

    DEFF Research Database (Denmark)

    Dutkiewicz, L.; Pedrys, R.; Schou, Jørgen

    1997-01-01

    Electronic sputtering of solid neon has been studied with molecular dynamics. The cavity formation around an excited atom and particle migration in the surface region, as well as the sputtering process have been studied. A single atomic exciton has been observed to produce a desorption of up to...... five excited or ground state atoms. The ejection from the surface is induced by excitons formed in five outermost monolayers of the solid. Energy and angular distributions of sputtered excited and ground state atoms have been calculated and are compared with experimental data....

  13. Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

    Science.gov (United States)

    Diwan, Anubhav; Singh, Bhupinder; Roychowdhury, Tuhin; Yan, DanDan; Tedone, Laura; Nesterenko, Pavel N; Paull, Brett; Sevy, Eric T; Shellie, Robert A; Kaykhaii, Massoud; Linford, Matthew R

    2016-02-01

    We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested

  14. Preparation and characteristics of vanadium oxide thin films by controlling the sputtering voltage

    Science.gov (United States)

    Wei, Xiongbang; Li, Shibin; Gou, Jun; Dong, Xiang; Yang, Xiaohui; Li, Weizhi; Wang, Tao; Wu, Zhiming; Jiang, Yadong; Chen, Zhi

    2014-06-01

    Influence of sputtering voltage on the deposition process and characteristics of vanadium oxide thin films prepared by reactive DC magnetron sputtering is investigated. The target surface cleaning is controlled by adjusting the sputtering voltage. During the sputtering process, the sputtering voltage increases faster with larger O2 gas flow rate. The sputtering voltage is easy to be stable with larger sputtering voltage. The measured sputtering voltage is correlated to the ion induced secondary electron emission (ISEE) coefficient of the target material. The ISEE coefficient of the oxidized vanadium target surface is lower than the ISEE coefficient of the vanadium metal. The semiconductor to metal (S-M) phase transition temperature decreases with the sputtering voltage, leading to the lower the corresponding temperature of the maximum temperature coefficient of resistance (TCR). By this way, O/V ratio, R, and TCR of VOx films can be controlled by adjusting the sputtering voltage.

  15. Laser bonding characteristics of sputtered titanium on glass with polymeric films

    Science.gov (United States)

    Lubna, Nusrat J.

    For miniaturized biomedical devices, laser joining of dissimilar materials offer excellent potential to make precise joints. An important system for consideration is Ti coated glass joined with biocompatible polymers. It is known that thin film characteristics (such as Ti thin film on glass) are strongly influenced by surface morphology and film thickness. In this investigation we studied sputtered Ti coated glass and examine the bonding characteristics of two polymers, they are polyimide and Teflon fluorinated ethylene-propylene (FEP) Polymer. Comparison of sputtered method to that of cathodic arc physical vapor deposition (CA-PVD) are made and found that sputtered deposition technique provides better film quality and better bond strength over CA-PVD technique. We have clearly observed formation of macro-droplets for CA-PVD for the various film thicknesses of titanium (50˜400nm), which is undesirable for good bonding. It has been observed that higher thickness and roughness of film significantly improves bond quality. For stronger bond with higher thickness mixed mode failure are observed- cohesive failure of polymer, interface failure of Ti/glass and failure on the glass itself. On the other hand for weak bond with thinner film mostly interface failure observed for this system of Ti coated glass/imidex. For thicker film chemical bond of Ti-C and Ti-O are observed. Also presence of imidex on Ti surface is confirmed by the N spectrum of XPS. We investigated the role of both surface characteristics and chemical bonding for laser joints using advanced techniques such as Optical Microscopy, Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Auger Electron Spectroscopy (AES), Positron Annihilation Lifetime Spectroscopy (PALS). A comprehensive three dimensional (3D) transient model for thermal analysis using the finite element (FE) code ABAQUS has been used. A comparison

  16. The effect of cathode geometry on barium transport in hollow cathode plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Polk, James E., E-mail: james.e.polk@jpl.nasa.gov; Mikellides, Ioannis G.; Katz, Ira [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Capece, Angela M. [California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125 (United States)

    2014-05-14

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba{sup +} ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe{sup +} ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice

  17. The effect of cathode geometry on barium transport in hollow cathode plasmas

    International Nuclear Information System (INIS)

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba+ ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe+ ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice because the Xe

  18. The effect of cathode geometry on barium transport in hollow cathode plasmas

    Science.gov (United States)

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

    2014-05-01

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba+ ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe+ ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice because the Xe

  19. Erosion behaviour of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    CERN Document Server

    Franz, Robert; Hawranek, Gerhard; Polcik, Peter

    2015-01-01

    Al$_{x}$Cr$_{1-x}$ composite cathodes with Al contents of x = 0.75, 0.5 and 0.25 were exposed to cathodic arc plasmas in Ar, N$_2$ and O$_2$ atmospheres and their erosion behaviour was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by X-ray diffraction analysis. Cathode poisoning effects in the reactive N$_2$ and O$_2$ atmospheres were non-uniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded centre region of the cathodes.

  20. Erosion behavior of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    International Nuclear Information System (INIS)

    AlxCr1−x composite cathodes with Al contents of x = 0.75, 0.5, and 0.25 were exposed to cathodic arc plasmas in Ar, N2, and O2 atmospheres and their erosion behavior was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by x-ray diffraction analysis. Cathode poisoning effects in the reactive N2 and O2 atmospheres were nonuniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded center region of the cathodes

  1. Auger electron spectroscopy in sputtering measurements: Application to low-energy Ar+ sputtering of Ag and Nb

    International Nuclear Information System (INIS)

    The sputtering of Ag and Nb by Ar+ in the energy range from 0.5 to 1.5 keV has been measured. The agreement with extant data, where available, is good. The experimental technique is a new adaptation of certain earlier methods and employs Auger electron spectroscopy of a continuously sputtered area of a thin-film composite structure, produced by vapor deposition. This new method should permit very low sputter yields (Sapproximately-less-than10-3) to be measured in subsequent experiments

  2. The coated cathode conductive layer chamber

    International Nuclear Information System (INIS)

    We describe a gaseous detector consisting of thin anode strips vacuum-evaporated on one side of a 100 μ thick plastic layer, alternating on the back side of the same foil with wider parallel cathode strips. Ionizatin released in a drift space on the anode side is amplified and detected much in the same way as in the microstrip gas chamber; in our detector however spontaenous breakdown due to surface currents is completely avoided by the presence of the insulating layer between anodes and cathodes. To reduce surface and volume charging up, we have used polymer foils with a moderate volume resistivity. The first results show good efficiency, good plateaux and time resolution in detecting low-rate minimum ionizing electrons. Although not suited for high rate or good energy resolution applications, this kind of detector seems rather promising for realizing cheaply large active surfaces. (orig.)

  3. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

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

    2009-01-01

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

  4. Cathodic Cage Plasma Nitriding: An Innovative Technique

    OpenAIRE

    de Sousa, R. R. M.; de Araújo, F. O.; da Costa, J. A. P.; A. de S. Brandim; de Brito, R. A.; Alves, C

    2012-01-01

    Cylindrical samples of AISI 1020, AISI 316, and AISI 420 steels, with different heights, were simultaneously treated by a new technique of ionic nitriding, entitled cathodic cage plasma nitriding (CCPN), in order to evaluate the efficiency of this technique to produce nitrided layers with better properties compared with those obtained using conventional ionic nitriding technique. This method is able to eliminate the edge effect in the samples, promoting a better uniformity of temperature, and...

  5. Reduction of promethium on a mercury cathode

    International Nuclear Information System (INIS)

    The authors observed the separation of radioactive promethium on a mercury cathode with samarium, which showed that it can be reduced to a bivalent state. Using radiochemically-pure Pm147, the authors made a detailed study of the influence of a series of factors on the extent to which promethium passes into an amalgam. It was shown that radioactive promethium only passes into the mercury cathode if the current is relatively dense (above 50 mA/cm2) and when rare-earth elements such as ytterbium and samarium, which have a stable bivalent state, are present in the electrolyte. Electrolytic separation of the promethium is not observable until formation of the mixed potassium and samarium amalgam. The promethium then passes into the amalgam up to 85%. When the current is denser (100 mA/cm2), a notable difference may be observed in the transition speed of the promethium and samarium. The promethium separation is mainly affected by the nature of the alkali metal contained in the electrolyte. With lithium, the degree of promethium transition does not depend on the presence of another rare-earth element or the citrate ion concentration. This confirms the occurrence of electrolytic reduction of promethium in electrolysis with a mercury cathode at high current densities. Separation of the promethium into the mercury cathode goes through the stage of its reduction to a bivalent state with formation of the amalgam with the alkali metal. The authors also studied the behaviour of cerium and erbium. From the results of this study and all the published data, the authors conclude that promethium and other elements of the cerium group can be reduced to a bivalent state under certain conditions of electrolysis. (author)

  6. Field Emission Cathodes for Electron Microscopes

    Czech Academy of Sciences Publication Activity Database

    Delong, Armin; Kolařík, V.

    Brno: Institute of Scientific Instruments AS CR, 2004 - (Müllerová, I.), s. 23 - 24 ISBN 80-239-3246-2. [Recent Trends /9./ in Charged Particle Optics and Surface Physics Instrumentation. Skalský Dvůr (CZ), 12.07.2004-16.07.2004] Institutional research plan: CEZ:AV0Z2065902 Keywords : field emission cathodes * electron microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  7. Cathode Ion Bombardment in RF Photoguns

    Energy Technology Data Exchange (ETDEWEB)

    Pozdeyev,E.; Kayran, D.; Litvinenko, V.

    2008-09-01

    In this paper, we use the method of rapid oscillating field to solve the equation of ion motion in an RF gun. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper proposes a simple mitigation recipe that can reduce the rate of ion bombardment.

  8. Infrared photoelectron emission from Scandate dispenser cathodes

    Science.gov (United States)

    Jensen, Kevin L.; Feldman, Donald W.; Virgo, Matt; O'Shea, Patrick G.

    2003-08-01

    Nonlinear photoelectric emission from Scandate dispenser cathodes using 1.064-μm radiation in nanosecond-scale pulses has been observed. Unlike single-photon emission, the photocurrent is a strong function of both the initial lattice temperature and the applied electric field as well as laser intensity. The parametric data is compared to a theoretical model for the process, and the data is shown to be explicable in terms of laser heating of the electron gas and subsequent photoemission.

  9. Sputtering from spherical Au clusters by energetic atom bombardment

    International Nuclear Information System (INIS)

    Using molecular-dynamics simulation, we study the effect of 100 keV Au atom bombardment of spherical Au clusters (radius R=40 A), containing 15,784 atoms. Results range from projectile transmission with only few atoms sputtered to more or less complete cluster disintegration. During disintegration, besides major fragments of the original cluster, monatomics and a large number of clusters with sizes up to 100 atoms, and even beyond, are created. Angular and energy spectra of sputtered atoms show features of both collisional sputtering and evaporation: particle emission is isotropic with an additional contribution of preferential emission along [1 1 0] directions. Energy spectra show the high-energy E-2 fall-off typical of linear-cascade sputtering plus an additional low-energy thermal component

  10. Sputter-Resistant Materials for Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 2 project shall develop sputter-resistant materials for use in electric propulsion test facilities and for plume shields on spacecraft using...

  11. Investigations on the sputtering of copper/lithium alloys

    International Nuclear Information System (INIS)

    The sputtering behavior of a copper based alloy containing 17 at-% of lithium has been studied under fusion relevant ion bombardment by D+, He+, Ne+, and Ar+ with energies between 0.1 keV and 6 keV and flux densities of up to 1016 particles/cm2s. The main question was, whether surface segregation of the lithium component can balance the losses due to sputtering and evaporation, and whether this way a protective lithium surface layer can be maintained under high particle flux irradiation. To investigate time-dependent sputtering phenomena, laser-induced fluorescence spectroscopy (LIF) has been employed to detect atoms emitted from the multi-component material. With LIF, velocity distributions and absolute densities of Cu and Li have been measured, offering the possibility to calculate absolute partial sputtering yields. (orig.)

  12. Sputtering studies during lanthanum implantation in stainless steels

    International Nuclear Information System (INIS)

    Lanthanum ions of 100 keV have been implanted in AISI304 specimens at different doses. The erosion or sputtering of the surface atoms, either from the steel matrix or already implanted, during the implantation process imposes a limitation on the maximum implantable dose. Hoping to increase this dose, we deposited thin layers of aluminium and alumina (Al2O3) on top of steel samples of similar composition and sputtering behaviour (AISI302), as the sputtering effect is much weaker on such species and this layer could also prevent the steel atoms from being removed from the surface. The experimental determination of the sputtering coefficients, total or partial, and its comparison with theoretical values, when possible, is another aim of this work. (orig.)

  13. Sputtering studies during lanthanum implantation in stainless steels

    Science.gov (United States)

    Ager, F. J.; Respaldiza, M. A.; Soares, J. C.; da Silva, M. F.; Odriozola, J. A.

    1997-05-01

    Lanthanum ions of 100 keV have been implanted in AISI304 specimens at different doses. The erosion or sputtering of the surface atoms, either from the steel matrix or already implanted, during the implantation process imposes a limitation on the maximum implantable dose. Hoping to increase this dose, we deposited thin layers of aluminium and alumina (Al 2O 3) on top of steel samples of similar composition and sputtering behaviour (AISI302), as the sputtering effect is much weaker on such species and this layer could also prevent the steel atoms from being removed from the surface. The experimental determination of the sputtering coefficients, total or partial, and its comparison with theoretical values, when possible, is another aim of this work.

  14. Sputtering studies during lanthanum implantation in stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Ager, F.J. [Sevilla Univ. (Spain). Dept. de Fisica Atomica, Molecular y Nuclear; Respaldiza, M.A. [Sevilla Univ. (Spain). Dept. de Fisica Atomica, Molecular y Nuclear; Soares, J.C. [CFNUL, Avda. Prof. Gama Pinto 2, P-1699, Lisboa Codex (Portugal); Da Silva, M.F. [Instituto Tecnologico e Nuclear, Estrada Nacional 10, P-2685, Sacavem (Portugal); Odriozola, J.A. [ICMSE, Universidad de Sevilla-CSIC, PO Box 874, E-41071, Sevilla (Spain)

    1997-05-01

    Lanthanum ions of 100 keV have been implanted in AISI304 specimens at different doses. The erosion or sputtering of the surface atoms, either from the steel matrix or already implanted, during the implantation process imposes a limitation on the maximum implantable dose. Hoping to increase this dose, we deposited thin layers of aluminium and alumina (Al{sub 2}O{sub 3}) on top of steel samples of similar composition and sputtering behaviour (AISI302), as the sputtering effect is much weaker on such species and this layer could also prevent the steel atoms from being removed from the surface. The experimental determination of the sputtering coefficients, total or partial, and its comparison with theoretical values, when possible, is another aim of this work. (orig.).

  15. Sputtering of nano-grains by energetic ions

    CERN Document Server

    Bringa, E M

    2002-01-01

    Sputtering from grains with a size of tens of nanometers is important in a number of astrophysical environments having a variety of plasma properties and can have applications in nano-technology. Since energy deposition by incident ions or electrons can create 'hot' regions in a small grain, thermal spike (TS) models have been applied to estimate the sputtering. The excitations produced by a fast ion are often assumed to form a 'hot' cylindrical track. In this paper we use molecular dynamics (MD) calculations to describe the energy transport and sputtering due to the creation of a 'hot' track in a grain with one quarter million atoms. We show the enhancement due to grain size and find that TS models work over a limited range of excitation densities. Discrepancies of several orders of magnitude are found when comparing our MD results for sputtering of small dust grains to those obtained by the astrophysical community using spike models.

  16. Antibacterial properties of palladium nanostructures sputtered on polyethylene naphthalate

    Czech Academy of Sciences Publication Activity Database

    Polívková, M.; Válová, M.; Siegel, J.; Rimpelová, S.; Hubáček, Tomáš; Lyutakov, O.; Švorčík, V.

    2015-01-01

    Roč. 5, č. 90 (2015), s. 73767-73774. ISSN 2046-2069 Institutional support: RVO:60077344 Keywords : polymer * palladium sputtering * annealing * nanostructure * antibacterial effect Subject RIV: CA - Inorganic Chemistry Impact factor: 3.840, year: 2014

  17. Hydorgen sputtering of carbon thin films deposited on platinum

    International Nuclear Information System (INIS)

    Carbon has been suggested as a suitable low Z element for the lining of the first walls of controlled thermonuclear reactors in order to reduce radiative plasma losses due to sputtering. In this paper the measurement of sputtering of carbon thin films by protons in the energy range 0.6-10.0 keV, is described. H2+ or H3+ ions were used as bombarding ions to obtain equivalent H+ sputtering yields at energies below that at which the ion source provides sufficient proton current. The sputter yield was found to range from 7x10-3-1.5x10-2 atoms/proton with a broad maximum in the 2.0 keV region with the carbon film kept near ambient temperature. (B.D.)

  18. The dependence of vircator oscillation mode on cathode material

    Science.gov (United States)

    Li, Limin; Liu, Lie; Cheng, Guoxin; Xu, Qifu; Wan, Hong; Chang, Lei; Wen, Jianchun

    2009-06-01

    This paper presents the effects of cathode materials on the oscillation mode of a virtual cathode oscillator (vircator). In the case of the stainless steel cathode, an oscillation mode hopping appeared with two separate frequencies. Interestingly, the vircator using the carbon fiber cathode exhibited an almost unchanged microwave frequency throughout the microwave pulse. To understand this phenomenon, several parameters are compared, including the diode voltage, accelerating gap, emitting area, and beam uniformity. It was found that a flat-top voltage and a relatively stable gap will provide a possibility of generating a constant microwave frequency. Further, the cathode operated in a regime where the beam current was between the space-charge limited current determined by Child-Langmuir law and the bipolar flow. On the cathode surface, the electron emission is initiated from discrete plasma spots and next from a continuing area, while there is a liberation process of multilayer gases on the anode surface. The changes in the emitting area of carbon fiber cathode showed a self-quenching process, which is not observed in the case of stainless steel cathode. The two-dimensional effect of microwave frequency is introduced, and the obtained results supported the experimental observations on the oscillation mode. By examining the cross section of electron beam, the electron beam for carbon fiber cathode was significantly centralized, while the discrete beam spots appeared for stainless steel cathode. These results show that the slowed diode closure, high emission uniformity, and stable microwave frequency tend to be closely tied.

  19. Magnetospheric ion sputtering and water ice grain size at Europa

    Science.gov (United States)

    Cassidy, T. A.; Paranicas, C. P.; Shirley, J. H.; Dalton, J. B., III; Teolis, B. D.; Johnson, R. E.; Kamp, L.; Hendrix, A. R.

    2013-03-01

    We present the first calculation of Europa's sputtering (ion erosion) rate as a function of position on Europa's surface. We find a global sputtering rate of 2×1027 H2O s-1, some of which leaves the surface in the form of O2 and H2. The calculated O2 production rate is 1×1026 O2 s-1, H2 production is twice that value. The total sputtering rate (including all species) peaks at the trailing hemisphere apex and decreases to about 1/3rd of the peak value at the leading hemisphere apex. O2 and H2 sputtering, by contrast, is confined almost entirely to the trailing hemisphere. Most sputtering is done by energetic sulfur ions (100s of keV to MeV), but most of the O2 and H2 production is done by cold oxygen ions (temperature ∼ 100 eV, total energy ∼ 500 eV). As a part of the sputtering rate calculation we compared experimental sputtering yields with analytic estimates. We found that the experimental data are well approximated by the expressions of Famá et al. for ions with energies less than 100 keV (Famá, M., Shi, J., Baragiola, R.A., 2008. Sputtering of ice by low-energy ions. Surf. Sci. 602, 156-161), while the expressions from Johnson et al. fit the data best at higher energies (Johnson, R.E., Burger, M.H., Cassidy, T.A., Leblanc, F., Marconi, M., Smyth, W.H., 2009. Composition and Detection of Europa's Sputter-Induced Atmosphere, in: Pappalardo, R.T., McKinnon, W.B., Khurana, K.K. (Eds.), Europa. University of Arizona Press, Tucson.). We compare the calculated sputtering rate with estimates of water ice regolith grain size as estimated from Galileo Near-Infrared Mapping Spectrometer (NIMS) data, and find that they are strongly correlated as previously suggested by Clark et al. (Clark, R.N., Fanale, F.P., Zent, A.P., 1983. Frost grain size metamorphism: Implications for remote sensing of planetary surfaces. Icarus 56, 233-245.). The mechanism responsible for the sputtering rate/grain size link is uncertain. We also report a surface composition estimate using

  20. Sputter initiated RIS (SIRIS) for analysis of semiconductor impurities

    International Nuclear Information System (INIS)

    This paper describes the technique, Sputter Initiated Resonance Ionization Spectroscopy (SIRIS), being developed for commercial analysis by Atom Sciences, Inc. This technique uses Resonance Ionization Spectroscopy to selectively ionize atoms of a sample sputtered by an energetic ion beam. The efficiency and selectivity of the RIS process provides results which are ultrasensitive and unambiguous to interpret. The SIRIS instrument being developed by Atom Sciences and recent results showing the present sensitivity limit of 2 ppb will be discussed. (author)

  1. Preparation of Copper Nanoparticles in Liquid by Matrix Sputtering Process

    International Nuclear Information System (INIS)

    As a new method for nanoparticles preparation, magnetron sputtering of metal atoms and clusters into organic liquids has been intensively used recently. In this study, metallic copper nanoparticles dispersed in pentaerythritol ethoxylate were prepared by this process. Their size control was achieved by controlling the sputtering current. Specific absorption at ca. 580 nm was detected by UV-Vis measurement which is attributed to the specific plasmon absorption of metallic copper. TEM observation also revealed the formation of metallic nanoparticles.

  2. Sputtering of CaF2 Thin Films

    International Nuclear Information System (INIS)

    In the present work CaF2 thin films of different thicknesses deposited on Si substrate have been irradiated with 120 MeV Ag ions with equilibrium charge state and electronic sputtering yield as well as emission of smaller particles/nanoclusters has been studied through Elastic Recoil Detection Analysis (ERDA) and Transmission Electron Microscopy (TEM) respectively. The observed results show maximum sputtering yield at smallest thickness and also nanostructure formation for that thickness has been observed through TEM.

  3. Optical Properties of Magnetron sputtered Nickel Thin Films

    Science.gov (United States)

    Twagirayezu, Fidele; Geerts, Wilhelmus J.; Cui, Yubo

    2015-03-01

    The study of optical properties of Nickel (Ni) is important, given the pivotal role it plays in the semiconductor and nano-electronics technology. Ni films were made by DC and RF magnetron sputtering in an ATC Orion sputtering system of AJA on various substrates. The optical properties were studied ex situ by variable angle spectroscopic (220-1000 nm) ellipsometry at room temperature. The data were modeled and analyzed using the Woollam CompleteEase Software fitting ellipsometric and transmission data. Films sputtered at low pressure have optical properties similar to that of Palik. Films sputtered at higher pressure however have a lower refraction index and extinction coefficient. It is expected from our results that the density of the sputtered films can be determined from the ellipsometric quantities. Our experiments also revealed that Ni is susceptible to a slow oxidation changing its optical properties over the course of several weeks. The optical properties of the native oxide differ from those of reactive sputtered NiO similar as found by. Furthermore the oxidation process of our samples is characterized by at least two different time constants.

  4. Estimation of Sputtering Damages on a Magnetron H- Ion Source Induced by Cs+ and H+ Ions

    CERN Document Server

    Pereira, H; Alessi, J; Kalvas, t

    2013-01-01

    An H− ion source is being developed for CERN’s Linac4 accelerator. A beam current requirement of 80 mA and a reliability above 99% during 1 year with 3 month uninterrupted operation periods are mandatory. To design a low-maintenance long life-time source, it is important to investigate and understand the wear mechanisms. A cesiated plasma discharge ion source, such as the BNL magnetron source, is a good candidate for the Linac4 ion source. However, in the magnetron source operated at BNL, the removal of material from the molybdenum cathode and the stainless steel anode cover plate surfaces is visible after extended operation periods. The observed sputtering traces are shown to result from cesium vapors and hydrogen gas ionized in the extraction region and subsequently accelerated by the extraction field. This paper presents a quantitative estimate of the ionization of cesium and hydrogen by the electron and H− beams in the extraction region of BNL’s magnetron ion source. The respective contributions o...

  5. Innovative technique for tailoring intrinsic stress in reactively sputtered piezoelectric aluminum nitride films

    International Nuclear Information System (INIS)

    Novel technical and technological solutions enabling effective stress control in highly textured polycrystalline aluminum nitride (AlN) thin films deposited with ac (40 kHz) reactive sputtering processes are discussed. Residual stress in the AlN films deposited by a dual cathode S-Gun magnetron is well controlled by varying Ar gas pressure, however, since deposition rate and film thickness uniformity depend on gas pressure too, an independent stress control technique has been developed. The technique is based on regulation of the flux of the charged particles from ac plasma discharge to the substrate. In the ac powered S-Gun, a special stress adjustment unit (SAU) is employed for reducing compressive stress in the film by means of redistribution of discharge current between electrodes of the S-Gun leading to controllable suppression of bombardment of the growing film. This technique is complementary to AlN deposition with rf substrate bias which increases ion bombardment and shifts stress in the compressive direction, if required. Using SAU and rf bias functions ensures tailoring intrinsic stress in piezoelectric AlN films for a particular application from high compressive -700 MPa to high tensile +300 MPa and allows the gas pressure to be adjusted independently to fine control the film uniformity. The AlN films deposited on Si substrates and Mo electrodes have strong (002) texture with full width at half maximum ranging from 2 degree sign for 200 nm to 1 degree sign for 2000 nm thick films.

  6. Non-conventional photocathodes based on Cu thin films deposited on Y substrate by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Perrone, A. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); National Institute of Nuclear Physics and University of Salento, 73100 Lecce (Italy); D’Elia, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); Gontad, F., E-mail: francisco.gontad@le.infn.it [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); National Institute of Nuclear Physics and University of Salento, 73100 Lecce (Italy); Di Giulio, M.; Maruccio, G. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); Cola, A. [National Council Research, Institute for Microelectronics and Microsystems, 73100 Lecce (Italy); Stankova, N.E. [Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Kovacheva, D.G. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Broitman, E. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden)

    2014-07-01

    Copper (Cu) thin films were deposited on yttrium (Y) substrate by sputtering. During the deposition, a small central area of the Y substrate was shielded to avoid the film deposition and was successively used to study its photoemissive properties. This configuration has two advantages: the cathode presents (i) the quantum efficiency and the work function of Y and (ii) high electrical compatibility when inserted into the conventional radio-frequency gun built with Cu bulk. The photocathode was investigated by scanning electron microscopy to determine surface morphology. X-ray diffraction and atomic force microscopy studies were performed to compare the structure and surface properties of the deposited film. The measured electrical resistivity value of the Cu film was similar to that of high purity Cu bulk. Film to substrate adhesion was also evaluated using the Daimler–Benz Rockwell-C adhesion test method. Finally, the photoelectron performance in terms of quantum efficiency was obtained in a high vacuum photodiode cell before and after laser cleaning procedures. A comparison with the results obtained with a twin sample prepared by pulsed laser deposition is presented and discussed.

  7. Low friction coefficient coatings Ni-Cr by magnetron sputtering, DC

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Hernandez, J.; Mandujano-Ruiz, A.; Torres-Gonzalez, J.; Espinosa-Beltran, F. J.; Herrera-Hernandez, H.

    2015-07-01

    Magnetron Sputter Deposition technique with DC was used for the deposition of Ni-Cr coatings on AISI 316 SS like substrate. The cathode with a nominal composition Ni-22 at% Cr was prepared by Mechanical Alloying (MA) technique, with a maximum milling time of 16 hours and, with a high energy SPEX 8000 mill. The coatings were made under Argon atmosphere at room temperature with a power of 100 W at different times of growth. Chemical composition, microstructure, topography, nano hardness and wear of the coatings were evaluated using the techniques of microanalysis by energy dispersive X-ray analyzer (EDAX), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Nano-indentation and pin-on-Disk, respectively. After milling, was not detected contamination in the mixtures. XRD analysis revealed that the microstructure of the Ni-Cr alloy was maintained in the coatings with respect to MA powders, with some degree of recrystallization. Nano hardness values were in the order of 8.8 GPa with a Youngs modulus of 195 GPa. The adhesion of the films was evaluated according to their resistance to fracture when these were indented at different loads using Vickers microhardness. The wear test results showed a decrease in the friction coefficient with respect to the increase of thickness films, getting a minimum value of 0.08 with a thickness of 1 μm and which correspond with the maximum growing time. (Author)

  8. Texture and microstructure in co-sputtered Mg-M-O (M = Mg, Al, Cr, Ti, Zr, and Y) films

    International Nuclear Information System (INIS)

    Mg-M-O solid solution films (M = Mg, Al, Cr, Ti, Zr, and Y) with various M contents are grown employing reactive co-sputtering by varying the target-to-substrate distance. It is shown that all films are biaxially aligned. When the two cathodes are equipped with the same target material (Mg), the in-plane alignment is determined by the cathode closest to the substrate, i.e., by the largest material flux. In the case of nearly equal material fluxes from the two cathodes, double in-plane orientation is observed. This is also the case for the Mg-Al-O and Mg-Cr-O films, while the Mg-Ti-O, Mg-Zr-O and Mg-Y-O films exhibit single in-plane orientation. Pole figures indicate that the grains in Mg-M-O (M different than Mg) are titled; in the Mg-Al-O, Mg-Cr-O, and Mg-Ti-O films, the grains tilt towards the Al, Cr, and Ti metal flux, respectively, while the grain tilt of the Mg-Zr-O and Mg-Y-O films is found to be towards the Mg metal flux. Furthermore, SEM cross-sectional images of the Mg-M-O films reveal columnar microstructure with columns tilted to the same direction as the grains. A mechanism which is based on the cation radius change upon the incorporation of an M atom in the MgO lattice is proposed to explain the tilting.

  9. Transition between the discharge regimes of high power impulse magnetron sputtering and conventional direct current magnetron sputtering

    OpenAIRE

    Lundin, Daniel; Brenning, Nils; Jädernäs, Daniel; Larsson, Petter; Wallin, Erik; Lattemann, Martina; Raadu, Michael A.; Helmersson, Ulf

    2009-01-01

    Current and voltage have been measured in a pulsed high power impulse magnetron sputtering (HiPIMS) system for discharge pulses longer than 100 mu s. Two different current regimes could clearly be distinguished during the pulses: (1) a high-current transient followed by (2) a plateau at lower currents. These results provide a link between the HiPIMS and the direct current magnetron sputtering (DCMS) discharge regimes. At high applied negative voltages the high-current transient had the charac...

  10. Influence of sputtering pressure on the structural, optical and hydrophobic properties of sputtered deposited HfO2 coatings

    International Nuclear Information System (INIS)

    The aim of this work is to develop hydrophobic coatings for outdoor insulators using sputtering technique. Hafnium oxide is characterized by high dielectric constant, large band gap (5.6 eV), high refractive index (2.1) and good mechanical, thermal and chemical properties. Hence HfO2 is suitable as a protective coating for outdoor insulators used in the transmission line and transformers. Hafnium oxide coatings were deposited on glass substrates by DC magnetron sputtering technique at a sputtering pressure of 5 mTorr, 10 mTorr, 15 mTorr, 20 mTorr and 25 mTorr. The deposited films were characterized by techniques like X-ray diffraction (XRD), atomic force microscopy (AFM), water contact angle goniometry and UV–vis-NIR spectrophotometer. The average crystallite size calculated from XRD peaks shows that it increases with increase in sputtering pressure up to 15 mTorr and then it starts decreasing. The roughness calculated from AFM images shows the similar trend. The deposited films were found to be hydrophobic and transparent. The hydrophobicity of the films was correlated with the roughness calculated from AFM. The effect of sputtering pressure was also investigated on optical band gap and refractive index calculated from transmission and absorption data. The electrical resistivity was found to be high, thus ensuring insulating property of the deposited films. - Highlights: • Outdoor Insulators are suffering from environment pollution problem. • To mitigate problem, hydrophobic coating of HfO2 was synthesized by DC sputtering. • Effect of sputtering pressure was studied on structural, optical and hydrophobic properties of HfO2 • Optimum results were obtained at a sputtering pressure of 15 mTorr

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-11

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

  12. Scanning optical pyrometer for measuring temperatures in hollow cathodes

    International Nuclear Information System (INIS)

    Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to determine the axial temperature profile. Thermocouples on the orifice plate provide measurements of the external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. The diagnostic method and initial measurements of the temperature distribution in a hollow cathode are discussed

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

    International Nuclear Information System (INIS)

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

  14. Cathodic phosphate coating containing nano zinc particles on magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A technology for preparation of a cathodic phosphate coating mainly containing nano metallic zinc particles and phosphate compounds on magnesium alloy was developed.The influence of cathodic current density on the microstructure of the cathodic phosphate coating Was investigated.The results show that the crystals of the coating are finer and the microstructures of the outer surface of the coatings are zigzag at the cathodic density of 0.2-0.5 A/dm2.The content of nano metallic zinc particles in the coating decreases with the increase of the thickness of the coatings and tends to be zero when the coating thickness is 4.14 μm.The cathodic phosphate coating was applied to be a transition coating for improving the adhesion between the paints and the magnesium alloys.The formation mechanism of the cathodic phosphate coating was investigated as well.

  15. Effect of cathodic protection on the state of steel reinforcement

    International Nuclear Information System (INIS)

    Damage of reinforced concrete structures is mainly caused by chloride or carbonation induced corrosion of steel. Cathodic protection is a very effective measure for corrosion control of steel in concrete, especially in chloride contaminated concrete. In this paper, effect of cathodic protection on the state of steel reinforcement is presented. Cathodic polarization of reinforcements in concrete was done under different submerged conditions. Cyclic potentiodynamic tests were used to determine the effect of cathodic protection on the behavior of the steel. Pitting appeared on the non-protected steel, but was not observed on the cathodically protected steel. microscopic photographs show that a close film exists on the protected steel, while the non-protected steel's film is loose. Investigated results have proved the effect of cathodic protection in restoring or strengthening passive film on the steel reinforcement

  16. Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

    Science.gov (United States)

    Barghouty, Abdulmasser F.; Adams, James H., Jr.

    2008-01-01

    At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

  17. NiF2 Cathodes For Rechargeable Na Batteries

    Science.gov (United States)

    Bugga, Ratnakumar V.; Distefano, Salvador; Halpert, Gerald

    1992-01-01

    Use of NiF2 cathodes in medium-to-high-temperature rechargeable sodium batteries increases energy and power densities by 25 to 30 percent without detracting from potential advantage of safety this type of sodium battery offers over sodium batteries having sulfur cathodes. High-energy-density sodium batteries with metal fluoride cathodes used in electric vehicles and for leveling loads on powerlines.

  18. Lighting sources with a cold cathode electron tube

    International Nuclear Information System (INIS)

    Lighting sources with a cold cathode are widely used in electronics. The lamps with a cold cathode are used primarily as sources of white light in optical scanners, digital indicators, display panels and signalling devices. In the paper the advantages of carbonaceous materials as emitters of cold electrons and the possibilities of using them to create a cathode in an electron lamp are discussed. (authors)

  19. Molten carbonate fuel cell cathode with mixed oxide coating

    Science.gov (United States)

    Hilmi, Abdelkader; Yuh, Chao-Yi

    2013-05-07

    A molten carbonate fuel cell cathode having a cathode body and a coating of a mixed oxygen ion conductor materials. The mixed oxygen ion conductor materials are formed from ceria or doped ceria, such as gadolinium doped ceria or yttrium doped ceria. The coating is deposited on the cathode body using a sol-gel process, which utilizes as precursors organometallic compounds, organic and inorganic salts, hydroxides or alkoxides and which uses as the solvent water, organic solvent or a mixture of same.

  20. Work function measurements of dispenser cathodes by retarding potential method

    Science.gov (United States)

    Khairnar, Rajendra S.; Chopra, A. K.

    1992-11-01

    The work function of dispenser cathode pellets has been determined by means of the retarding potential technique. A low-energy electron gun was fabricated which delivers a collimated beam of electrons on the pellet surface at normal incidence. The set up is calibrated by employing samples of known work function such as gold and tungsten, prior to determining the work function of the cathode pellets. This set up provides a rapid determination of the work function of cathode pellets.

  1. Scanning optical pyrometer for measuring temperatures in hollow cathodes

    OpenAIRE

    Polk, J. E.; Marrese-Reading, C. M.; Thornber, B.; Dang, L.; Johnson, L. K.; Katz, I

    2007-01-01

    Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to determine the axial temperature profile. Thermocouples on the orifice plate provide measu...

  2. High current density pulsed cathode experiments at SLAC

    International Nuclear Information System (INIS)

    A 1.9 microperveance beam diode has been constructed to test high current density cathodes for use in klystrons. Several standard and specially coated dispenser cathodes are being tested. Results of tests to date show average cathode current densities in excess of 25 amps/cm, and maximum electric field gradients of more than 450 kV/cm for pulses of the order of 1μsec. 3 refs., 11 figs

  3. Contribution to modelling sputtering by ion beams

    International Nuclear Information System (INIS)

    From ion-matter interaction results, we have modelized sputtering by ion beams, for energies around 1 keV, in linear collisions regime, according to three approaches: analytic, semi-empiric and simulated. Some corrections to analytic approach have given better agreement to experiment. Semi-empiric approach predictions, compared to experiment, have given satisfactory results for mono-element target. Some input parameters, for used simulated program, have been proposed, for mono-elements, semi-conductives and binaries oxide targets. An iterative simulated model, validated by experiment, has deal with oxide steady targets. To predict deposited thickness profile on static then dynamic substrates, a simulated model, leaning on geometric considerations, has been brought into focus, compared to experiment and has given some satisfactories qualitative in truth quantitative results. With this proposed model, we can search for the best geometry to realize thin films deposition with very homogeneous thickness on large diameter substrates in I.B.S. and D.I.B.S. technics. (orig.)

  4. Annealing of gold nanostructures sputtered on polytetrafluoroethylene

    Science.gov (United States)

    Siegel, Jakub; Krajcar, Robert; Kolská, Zdeňka; Hnatowicz, Vladimír; Švorčík, Václav

    2011-11-01

    Gold nanolayers sputtered on polytetrafluoroethylene (PTFE) surface and their changes induced by post-deposition annealing at 100°C to 300°C are studied. Changes in surface morphology and roughness are examined by atomic force microscopy, electrical sheet resistance by two point technique, zeta potential by electrokinetic analysis and chemical composition by X-ray photoelectron spectroscopy (XPS) in dependence on the gold layer thickness. Transition from discontinuous to continuous gold coverage takes place at the layer thicknesses 10 to 15 nm and this threshold remains practically unchanged after the annealing at the temperatures below 200°C. The annealing at 300°C, however, leads to significant rearrangement of the gold layer and the transition threshold increases to 70 nm. Significant carbon contamination and the presence of oxidized structures on gold-coated samples are observed in XPS spectra. Gold coating leads to a decrease in the sample surface roughness. Annealing at 300°C of pristine PTFE and gold-coated PTFE results in significant increase of the sample surface roughness.

  5. Surface Characterization of the LCLS RF Gun Cathode

    Energy Technology Data Exchange (ETDEWEB)

    Brachmann, Axel; /SLAC; Decker, Franz-Josef; /SLAC; Ding, Yuantao; /SLAC; Dowell, David; /SLAC; Emma, Paul; /SLAC; Frisch, Josef; /SLAC; Gilevich, Sasha; /SLAC; Hays, Gregory; /SLAC; Hering, Philippe; /SLAC; Huang, Zhirong; /SLAC; Iverson, Richard; /SLAC; Loos, Henrik; /SLAC; Miahnahri, Alan; /SLAC; Nordlund, Dennis; /SLAC; Nuhn, Heinz-Dieter; /SLAC; Pianetta, Piero; /SLAC; Turner, James; /SLAC; Welch, James; /SLAC; White, William; /SLAC; Wu, Juhao; /SLAC; Xiang, Dao; /SLAC

    2012-06-25

    The first copper cathode installed in the LCLS RF gun was used during LCLS commissioning for more than a year. However, after high charge operation (> 500 pC), the cathode showed a decline of quantum efficiency within the area of drive laser illumination. They report results of SEM, XPS and XAS studies that were carried out on this cathode after it was removed from the gun. X-ray absorption and X-ray photoelectron spectroscopy reveal surface contamination by various hydrocarbon compounds. In addition they report on the performance of the second installed cathode with emphasis on the spatial distribution of electron emission.

  6. Apparatuses for making cathodes for high-temperature, rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    Meinhardt, Kerry D.; Sprenkle, Vincent L.; Coffey, Gregory W.

    2016-09-13

    The approaches and apparatuses for fabricating cathodes can be adapted to improve control over cathode composition and to better accommodate batteries of any shape and their assembly. For example, a first solid having an alkali metal halide, a second solid having a transition metal, and a third solid having an alkali metal aluminum halide are combined into a mixture. The mixture can be heated in a vacuum to a temperature that is greater than or equal to the melting point of the third solid. When the third solid is substantially molten liquid, the mixture is compressed into a desired cathode shape and then cooled to solidify the mixture in the desired cathode shape.

  7. Measuring current emission and work functions of large thermionic cathodes

    International Nuclear Information System (INIS)

    As one component of the nations Stockpile Stewardship program, Los Alamos National Laboratory is constructing a 20 MeV, 2 kA (with a 4 kA upgrade capability), 3ps induction linac for doing x-ray radiography of explosive devices. The linac is one leg of a facility called the Dual-Axis Radiography Hydrodynamic Test Facility (DARHT). The electron gun is designed to operate at 3.2 MV. The gun is a Pierce type design and uses a 6.5' cathode for 2 kA operation and an 8' cathode for 4 kA operation. We have constructed a small facility called the Cathode Test Stand (CTS) to investigate engineering and physics issues regarding large thermionic dispenser-cathodes. In particular, we have looked at the issues of temperature uniformity on the cathode surface and cathode quality as measured by its work function. We have done thermal imaging of both 8' and 6.5' cathodes. Here we report on measurements of the cathode work function, both the average value and how it vanes across the face of the cathode.

  8. Characterization of Hollow Cathode Performance and Thermal Behavior

    Science.gov (United States)

    Polk, James E.; Goebel, Dan M.; Watkins, Ron; Jameson, Kristina; Yoneshige, Lance; Przybylowski, JoHanna; Cho, Lauren

    2006-01-01

    Hollow cathodes are one of the main life-limiting components in ion engines and Hall thrusters. Although state-of-the-art hollow cathodes have demonstrated up to 30,352 hours of operation in ground tests with careful handling, future missions are likely to require longer life, more margin and greater resistance to reactive contaminant gases. Three alternate hollow cathode technologies that exploit different emitter materials or geometries to address some of the limitations of state-of-the-art cathodes are being investigated. Performance measurements of impregnated tungsten-iridium dispenser cathodes at discharge currents of 4 to 15 A demonstrated that they have the same operating range and ion production efficiency as conventional tungsten dispenser cathodes. Temperature measurements indicated that tungsten-iridium cathodes also operate at the same emitter temperatures. They did not exhibit the expected reduction in work function at the current densities tested. Hollow cathodes with lanthanum hexaboride emitters operated over a wide current range, but suffered from lower ion production efficiency at currents below about 12.4 A because of higher insert heating requirements. Differences in operating voltages and ion production rates are explained with a simple model of the effect of cathode parameters on discharge behavior.

  9. Large area dispenser cathode applied to high current linac

    International Nuclear Information System (INIS)

    The paper introduced a dispenser cathode (411 M) which was 55 mm in diameter. A 200 kV long pulsed power generator with 2 μs flattop based on Marx-PEN and system with heat and voltage insulation were built. A 52 A space charge limited current was gained, when the temperature was 1165 degree C and the filament current was 18 A on the cathode and the voltage of the pulse was 75 kV at the cathode test stand. Experimental results show that the current values are consistent with the numerical simulation. The experiment reveals that the deflated gas will influence the cathode emission ability. (authors)

  10. Characterization of the Be-Ag interfacial region of silver films deposited onto beryllium using a hot hollow cathode discharge

    International Nuclear Information System (INIS)

    Silver films are physically vapor deposited onto beryllium substrates using a hot hollow cathode discharge. To obtain high Be-Ag adhesion strengths, an atomically 'clean' surface is obtained by ion bombardment cleaning. In this investigation, the relationship of the ion cleaning parameters to contaminants in the Be-Ag interfacial region and their effect on adhesion strength were evaluated. Specimens were ion cleaned at various bombardment parameters and then flash coated with silver. In-depth film profiles were taken by sputter etching in argon and monitoring the Auger electron peak-to-peak heights. The interface was also analyzed by taking a complete spectrum at the edge of the sputter crater. Impurities found at the interface were tantalum, copper and oxygen. The results for adhesion strengths showed that a small amount of oxygen (about 2 at.%) left in the Be-Ag interface will reduce the adhesion strength of the coating. Silver films deposited in an air leak that was greater than a leak which is easily detectable by residual gas analysis contained only about 0.5 at.% O with no reduction in film adherence strengths. (Auth.)

  11. In situ plasma diagnostics study of a commercial high-power hollow cathode magnetron deposition tool

    International Nuclear Information System (INIS)

    Using a newly designed and built plasma diagnostic system, the plasma parameters were investigated on a commercial 200 mm high-power hollow cathode magnetron (HCM) physical vapor deposition tool using Ta target under argon plasma. A three dimensional (3D) scanning radio frequency (rf)-compensated Langmuir probe was constructed to measure the spatial distribution of the electron temperature (Te) and electron density (ne) in the substrate region of the HCM tool at various input powers (2-15 kW) and pressures (10-70 mTorr). The Te was in the range of 1-3 eV, scaling with decreasing power and decreasing pressure. Meanwhile, ne was in the range of 4x1010-1x1012 cm-3 scaling with increasing power and decreasing pressure. As metal deposits on the probe during the probe measurements, a self-cleaning plasma cup was designed and installed in the chamber to clean the tungsten probe tip. However, its effectiveness in recovering the measured plasma parameters was hindered by the metal layer deposited on the insulating probe tube which was accounted for the variation in the plasma measurements. Using a quartz crystal microbalance combined with electrostatic filters, the ionization fraction of the metal flux was measured at various input power of 2-16 kW and pressure of 5-40 mTorr. The metal ionization fraction reduced significantly with the increasing input power and decreasing gas pressure which were attributed to the corresponding variation in the ionization cross section and the residence time of the sputtered atoms in the plasma, respectively. Both the metal neutral and ion flux increased at higher power and lower pressure. The 3D measurements further showed that the ionization fraction decreased when moving up from the substrate to the cathode.

  12. ERDA characterization of carbon nitride films deposited by hollow cathode discharge process

    International Nuclear Information System (INIS)

    The interest in carbon nitride (CN) thin films stems from the theoretical work of Liu and Cohen predicting the extreme hardness of this material, comparable to or greater than that of diamond. The growth of CN thin films employing various deposition techniques such as plasma chemical vapor deposition, sputtering, laser ablation, ion assisted dynamic mixing and low energy ion implantation has been reported. This contribution presents some results about the characterization of CNx films using elastic recoil detection analysis (ERDA) technique. CN films were deposited on silicon substrates by electron beam evaporation of pure graphite in a nitrogen environment. A hollow cathode discharge in arc regime was used both for evaporating a graphite target and for generating a high density plasma in the vicinity of the substrate. The main deposition parameters were as follows: gas (N2) pressure, 10-2 - 5.10-2 mbar; hollow cathode discharge power, 2.5 - 5 kW; substrate negative bias voltage, 0-150 V; graphite evaporation rate, 0.08 - 0.2 g/min; deposition duration, 15-60 min. The ERDA measurements were carried out at the Tandem accelerator of IFIN-HH using a 63Cu10+ beam at 80 MeV. The samples were mounted in a scattering target chamber with a vacuum higher than 5 x 10-5 Torr. The detector consisted in a compact ΔE(gas)-E(solid) telescope, placed at 30 angle with respect to the beam. The elements of the main interests were C and N. The measured Δ E -E spectra for two samples prepared in different conditions are presented. A quantitative analysis of the C and N energy spectra using our program SURFAN have been carried out for the these samples. It shows that the nitrogen to carbon atomic concentration ratio is close to 0.3. The nitrogen content is lower than that expected for the ideal β - C3N4 solid. (authors)

  13. X-ray photoelectron spectroscopy of nano-multilayered Zr-O/Al-O coatings deposited by cathodic vacuum arc plasma

    International Nuclear Information System (INIS)

    Nano-multilayered Zr-O/Al-O coatings with alternating Zr-O and Al-O layers having a bi-layer period of 6-7 nm and total coating thickness of 1.0-1.2 μm were deposited using a cathodic vacuum arc plasma process on rotating Si substrates. Plasmas generated from two cathodes, Zr and Al, were deposited simultaneously in a mixture of Ar and O2 background gases. The Zr-O/Al-O coatings, as well as bulk ZrO2 and Al2O3 reference samples, were studied using X-ray photoelectron spectroscopy (XPS). The XPS spectra were analyzed on the surface and after sputtering with a 4 kV Ar+ ion gun. High resolution angle resolved spectra were obtained at three take-off angles: 15o, 45o and 75o relative to the sample surface. It was shown that preferential sputtering of oxygen took place during XPS of bulk reference ZrO2 samples, producing ZrO and free Zr along with ZrO2 in the XPS spectra. In contrast, no preferential sputtering was observed with Al2O3 reference samples. The Zr-O/Al-O coatings contained a large amount of free metals along with their oxides. Free Zr and Al were observed in the coating spectra both before and after sputtering, and thus cannot be due solely to preferential sputtering. Transmission electron microscopy revealed that the Zr-O/Al-O coatings had a nano-multilayered structure with well distinguished alternating layers. However, both of the alternating layers of the coating contained of a mixture of aluminum and zirconium oxides and free Al and Zr metals. The concentration of Zr and Al changed periodically with distance normal to the coating surface: the Zr maximum coincided with the Al minimum and vice versa. However the concentration of Zr in both alternating layers was significantly larger than that of Al. Despite the large free metal concentration, the Knoop hardness, 21.5 GPa, was relatively high, which might be attributed to super-lattice formation or formation of a metal-oxide nanocomposite within the layers.

  14. Effects of three-dimensional cathode microstructure on the performance of lithium-ion battery cathodes

    International Nuclear Information System (INIS)

    Highlights: ► Segments of Li-ion battery cathodes are reconstructed from FIB-SEM experiments. ► The three-dimensional reconstructed cathode is discretized using a cut-cell approach. ► A Three-dimensional model of cathode performance is developed. ► Three-dimensional simulations reveal significant spatial variations in concentrations and voltage. -- Abstract: This paper develops a computational model that resolves the complex three-dimensional microstructure of Li-ion battery cathodes. The microstructural geometry is reconstructed from focused-ion-beam–scanning-electron-microscopy (FIB-SEM) experiments. Raw data from FIB-SEM experiments are processed into finite-volume discretizations that are directly suited for three-dimensional computational simulation. The model represents transport and electrochemistry within the solid phase of the electrode structure. The results predict the temporally and spatially varying Li concentrations and electrostatic potentials within the solid-phase electrode material (e.g., LiCoO2) as functions of discharge rate. The models predict global discharge characteristics that are consistent with experiment. Moreover, the results reveal significant three-dimensional spatial variations within the actual electrode structure that cannot be predicted with models based on idealized microstructures such as spherical electrode particles

  15. Organic Cathode Materials for Rechargeable Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Ruiguo; Qian, Jiangfeng; Zhang, Jiguang; Xu, Wu

    2015-06-28

    This chapter will primarily focus on the advances made in recent years and specify the development of organic electrode materials for their applications in rechargeable lithium batteries, sodium batteries and redox flow batteries. Four various organic cathode materials, including conjugated carbonyl compounds, conducting polymers, organosulfides and free radical polymers, are introduced in terms of their electrochemical performances in these three battery systems. Fundamental issues related to the synthesis-structure-activity correlations, involved work principles in energy storage systems, and capacity fading mechanisms are also discussed.

  16. Projectile charge state dependent sputtering of solid surfaces

    CERN Document Server

    Hayderer, G

    2000-01-01

    dependence on the ion kinetic energy. This new type of potential sputtering not only requires electronic excitation of the target material, but also the formation of a collision cascade within the target in order to initiate the sputtering process and has therefore been termed kinetically assisted potential sputtering. In order to study defects induced by potential sputtering on the atomic scale we performed measurements of multiply charged Ar ion irradiated HOPG (highly oriented pyrolitic graphite) samples with scanning tunneling microscopy (STM). The only surface defects found in the STM images are protrusions. The mean diameter of the defects increases with projectile charge state while the height of the protrusions stays roughly the same indicating a possible pre-equilibrium effect of the stopping of slow multiply charged projectiles in HOPG. Total sputter yields for impact of slow singly and multiply charged ions on metal- (Au), oxide- (Al2O3, MgO) and alkali-halide surfaces (LiF) have been measured as a...

  17. EMI shielding using composite materials with two sources magnetron sputtering

    Science.gov (United States)

    Ziaja, J.; Jaroszewski, M.; Lewandowski, M.

    2016-02-01

    In this study, the preparation composite materials for electromagnetic shields using two sources magnetron sputtering DC-M is presented. A composite material was prepared by coating a nonwoven polypropylene metallic layer in sputtering process of targets Ti (purity 99%) and brass alloy MO58 (58%Cu, 40%Zn, 2%Pb) and ϕ diameter targets = 50 mm, under argon atmosphere. The system with magnetron sputtering sources was powered using switch-mode power supply DPS (Dora Power System) with a maximum power of 16 kW and a maximum voltage of 1.2 kV with group frequency from 50 Hz to 5 kHz. The influence of sputtering time of individual targets on the value of the EM field attenuation SE [dB] was investigated for the following supply conditions: pressure pp = 2x10-3 Torr, sputtering power P = 750 W, the time of applying a layer t = 5 min, group frequency fg = 2 kHz, the frequency of switching between targets fp = 1 Hz.

  18. Measurement of ion sputtering yields for depth profile analyses

    International Nuclear Information System (INIS)

    Results are reported of the second phase of joint research on ion sputtering that was conducted by the Iron and Steel Institute of Japan. Various effects on sputtering yields were studied in detail, and the yields for Ni and Zn were determined by analysing the depth profile of electrodeposited steel sheets with an Auger electron spectrometer, Ar+ ions were used as the bombarding species, and a Faraday cup, which was fitted with a front plate incorporating a small hole in the centre for the ions to pass through, was used to measure the electric current of the incident ions. To calculate the ion current density, a correction for the effective transmittance efficiency of the hole was made according to its cross-sectional shape. The sputtering yields determined in several laboratories by using this correction agreed with each other better than those obtained in the first phase of the work. The angular dependence and energy dependence of the sputtering yields for Ni and Zn were measured. A standard procedure is proposed for the measurement of ion sputtering yields to analyse depth profiles, including methods to measure the ion current, to calculate the ion current density, to optimize the sample position and to tune the lenses of the ion gun. (author)

  19. Sputtering of a metal nanofoam by Au ions

    International Nuclear Information System (INIS)

    Porous materials, such as nanofoams, may react differently to irradiation than compact targets. This is caused by the influence of the cavities on the evolution of collision cascades, but also by the differing heat conduction which affects the spike phase. Using molecular dynamics simulation we study the sputtering of a Au nanofoam by 10 keV Au projectiles, and compare to the sputtering of a compact Au target. These bombardment conditions lead to a strong contribution of spikes to the sputtering process. We find the foam to sputter considerably less than the compact target; the open structure of the foam prevents the build-up of strong collision spike regions at the surface, which are the major source of sputtering in the compact target. Also emission takes a longer time scale in the foam, as particles need to travel longer pathways to be emitted. On the other hand, the molten phase is more extended in the foam and also exists for a longer time; this is caused by the reduced heat conductivity in this material

  20. Radioimmunological determination and characterization of cathodal trypsin-like immunoreactivity in normal human plasma

    International Nuclear Information System (INIS)

    A radioimmunological method for determination of human cathodal trypsin-like immunoreactivity is described. DFP-treated human cathodal trypsin is used as standard and tracer. Freshly drawn normal human plasma contains about 25μg/l of cathodal trypsin-like immunoreactivity measured as DFP-treated cathodal trypsin. The normally circulating cathodal trypsin-like immunoreactivity is shown to consist mainly of cathodal trypsinogen. (Auth.)

  1. Oxide diffusion in innovative SOFC cathode materials.

    Science.gov (United States)

    Hu, Y; Thoréton, V; Pirovano, C; Capoen, E; Bogicevic, C; Nuns, N; Mamede, A-S; Dezanneau, G; Vannier, R N

    2014-01-01

    Oxide diffusion was studied in two innovative SOFC cathode materials, Ba(2)Co(9)O(14) and Ca(3)Co(4)O(9)+δ derivatives. Although oxygen diffusion was confirmed in the promising material Ba(2)Co(9)O(14), it was not possible to derive accurate transport parameters because of an oxidation process at the sample surface which has still to be clarified. In contrast, oxygen diffusion in the well-known Ca(3)Co(4)O(9)+δ thermoelectric material was improved when calcium was partly substituted with strontium, likely due to an increase of the volume of the rock salt layers in which the conduction process takes place. Although the diffusion coefficient remains low, interestingly, fast kinetics towards the oxygen molecule dissociation reaction were shown with surface exchange coefficients higher than those reported for the best cathode materials in the field. They increased with the strontium content; the Sr atoms potentially play a key role in the mechanism of oxygen molecule dissociation at the solid surface. PMID:25407246

  2. Development of cathode material for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Rustam Mukhtaruly Turganaly

    2014-08-01

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

  3. Temperature controlled cathode heating in the electron gun

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav

    Brno: CSMS, 2002 - (Frank, L.), s. 69 - 70 ISBN 80-238-8749-1. [CSEM. Vranovská Ves (CZ), 08.02.2002-09.02.2002] Institutional research plan: CEZ:AV0Z2065902 Keywords : directly heated tungsten cathode * electron gun * temperature controlled cathode heating Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  4. The Cathode Ramper: Application for the Duoplasmatron Ion Source

    CERN Document Server

    Sánchez-Conejo, J

    2003-01-01

    The purpose of the Cathode Ramper Application is to heat the Linac 2 duoplasmatron ion source cathode up to a desired temperature selected by the user. The application has been developed in Java, making use of the Java Development Kit 1.4 and the PS Java environment.

  5. Effects of Humidity on Solid Oxide Fuel Cell Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, John S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stevenson, Jeffry W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Singh, Prabhakar [Univ. of Connecticut, Storrs, CT (United States); Mahapatra, Manoj K. [Univ. of Connecticut, Storrs, CT (United States); Wachsman, E. D. [Univ. of Maryland, College Park, MD (United States); Liu, Meilin [Georgia Inst. of Technology, Atlanta, GA (United States); Gerdes, Kirk R. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2015-03-17

    This report summarizes results from experimental studies performed by a team of researchers assembled on behalf of the Solid-state Energy Conversion Alliance (SECA) Core Technology Program. Team participants employed a variety of techniques to evaluate and mitigate the effects of humidity in solid oxide fuel cell (SOFC) cathode air streams on cathode chemistry, microstructure, and electrochemical performance.

  6. Cathodic disbonding of organic coatings on submerged steel

    Energy Technology Data Exchange (ETDEWEB)

    Knudsen, Ole oeystein

    1998-12-31

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

  7. The Effect of Substrate Topography on Coating Cathodic Delamination

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  8. Tandem cathode for proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

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

    2013-01-01

    The efficiency of proton exchange membrane fuel cells is limited mainly by the oxygen reduction reaction at the cathode. The large cathodic overpotential is caused by correlations between binding energies of reaction intermediates in the reduction of oxygen to water. This work introduces a novel...

  9. Cathodic protection -- Addition of 6 anodes to existing rectifier 31

    International Nuclear Information System (INIS)

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system additions are installed, connected, and function as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive wastes

  10. Microbial Fuel Cell Performance with a Pressurized Cathode Chamber

    Science.gov (United States)

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

  11. High Performance Fe-Co Based SOFC Cathodes

    DEFF Research Database (Denmark)

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

    2010-01-01

    With the aim of reducing the temperature of the solid oxide fuel cell (SOFC), a new high-performance perovskite cathode has been developed. An area-specific resistance (ASR) as low as 0.12 Ωcm2 at 600 °C was measured by electrochemical impedance spectroscopy (EIS) on symmetrical cells. The cathode...

  12. Improving the performance of stainless-steel DC high voltage photoelectron gun cathode electrodes via gas conditioning with helium or krypton

    International Nuclear Information System (INIS)

    Gas conditioning was shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns, thus providing a reliable means to operate photoguns at higher voltages and field strengths. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. We have studied five stainless steel electrodes (304L and 316LN) that were polished to approximately 20 nm surface roughness using diamond grit, and evaluated inside a high voltage apparatus to determine the onset of field emission as a function of voltage and field strength. The field emission characteristics of each electrode varied significantly upon the initial application of voltage but improved to nearly the same level after gas conditioning using either helium or krypton, exhibiting less than 10 pA field emission at −225 kV bias voltage with a 50 mm cathode/anode gap, corresponding to a field strength of ∼13 MV/m. Field emission could be reduced with either gas, but there were conditions related to gas choice, voltage and field strength that were more favorable than others

  13. Oxygen Recovery in Hf Oxide Films Fabricated by Sputtering

    Institute of Scientific and Technical Information of China (English)

    JIANG Ran; LI Zi-Feng

    2009-01-01

    The chemical structure of ultrathin Hf oxide films (< 10 nm) fabricated by a standard sputtering method is investigated using x-ray spectroscopy and Rutherford backscattering spectroscopy. According to the experiments,oxygen species are impacted to the HfO2/Si interface during the initial sputtering, and then released back to the upper Hf02 region driven by the oxygen concentration grads. A vacuum annealing can greatly enhance this recovery process. Additionally, significant SiO2 reduction in the interface is observed after the vacuum annealing for the thick HfO2 films in our experiment. It might be an effective method to confine the interracial layer thickness by sputtering thick HfO2 in no-oxygen ambient.

  14. Anion formation in sputter ion sources by neutral resonant ionization

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, J. S., E-mail: johnsvogel@yahoo.com [University of California, 8300 Feliz Creek Dr., Ukiah, California 95482 (United States)

    2016-02-15

    Focused Cs{sup +} beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm{sup 2} C{sup −} current density compared to the 20 μA/mm{sup 2} from a 1 mm recess.

  15. Oxidation Behaviour of Sputtered Ni-3Cr-20Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation behavior of sputtered Ni-3Cr-20Al coating at 900°C in air was investigated. A dense Al2O3 layer was formed on the sputtered Ni-3Cr-20Al coating after 200 h oxidation.However, owing to the segregation of Ni3Al during oxidation Focess at high temperature, the spinel NiAl2O4 was also formed in the Al2O3 layer. It was found that the formation of NiAl2O4had no detrimental effect on the oxidation resistance of the sputtered Ni-3Cr-20Al coating due to the excellent adhesion shown by the Al2O3 and NiAl2O4 complex oxide scale.

  16. Energy dependence of sputtering yields of monatomic solids

    International Nuclear Information System (INIS)

    The experimental data on the sputtering of solids by ion bombardment have been accumulated. This paper presents the compilation of the experimental data on the energy dependence of the sputtering yield at normal incidence for all available combination of incident ions and target atoms. For each combination, the data are fitted to an empirical equation based on the modified Sigmund equation. The best fit values of two empirical parameters are tabulated. The elastic stopping cross section was obtained. The deviation of the experimental values from the best fit curves in remarkable for heavier incident ions and for heavier target atoms. The approximate sputtering yield of any combination as a function of energy is easily obtained. (Kato, T.)

  17. Anion formation in sputter ion sources by neutral resonant ionization

    Science.gov (United States)

    Vogel, J. S.

    2016-02-01

    Focused Cs+ beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm2 C- current density compared to the 20 μA/mm2 from a 1 mm recess.

  18. Anion formation in sputter ion sources by neutral resonant ionization

    International Nuclear Information System (INIS)

    Focused Cs+ beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm2 C− current density compared to the 20 μA/mm2 from a 1 mm recess

  19. CO2 gas sensitivity of sputtered zinc oxide thin films

    Indian Academy of Sciences (India)

    P Samarasekara; N U S Yapa; N T R N Kumara; M V K Perera

    2007-04-01

    For the first time, sputtered zinc oxide (ZnO) thin films have been used as a CO2 gas sensor. Zinc oxide thin films have been synthesized using reactive d.c. sputtering method for gas sensor applications, in the deposition temperature range from 130–153°C at a chamber pressure of 8.5 mbar for 18 h. Argon and oxygen gases were used as sputtering and reactive gases, respectively. ZnO phase could be crystallized using a pure metal target of zinc. The structure of the films determined by means of X-ray diffraction method indicates that the zinc oxide single phase can be fabricated in this substrate temperature range. The sensitivity of the film synthesized at substrate temperature of 130°C is 2.17 in the presence of CO2 gas at a measuring temperature of 100°C.

  20. Magnetron discharge sputtering for fabrication of nanogradient optical coatings

    Science.gov (United States)

    Volpian, O. D.; Kuzmichev, A. I.; Ermakov, G. F.; Krikunov, A. I.; Obod, Yu A.; Silin, N. V.; Shkatula, S. V.

    2015-11-01

    The technology of the middle frequency pulse reactive magnetron sputtering for fabrication of nanogradient optical coatings with smooth variation of refractive index was developed and studied. The technology is based on programmable motion of a substrate over two magnetrons with targets of different materials. The feature of the deposition process is a constant composition of reactive gas medium and an invariable magnetron operation mode. To realize this technology, an automatic computer-controlled sputtering system additionally comprising a gas discharge activator of reactive gas (oxygen) and an in situ optical monitor- spectrovisor has been built. The dielectric oxide-based nanogradient coatings of photon-barrier type were successfully fabricated. The obtained results confirm the high potential of the middle frequency pulse reactive magnetron sputtering of silicon and metal targets for fabrication of nanogradient dielectric optical coatings with excellent properties.

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

    DEFF Research Database (Denmark)

    Samson, Alfred Junio

    . High performance cathodes were obtained from strontium-doped lanthanum cobaltite (LSC) infiltrated - Ce0.9Gd0.1O1.95 (CGO) ionic conducting backbone. Systematic tuning of the CGO and LSC firing temperatures and LSC loading resulted in a cathode with low polarization resistance, Rp = 0.044 cm2 at 600......+delta/CGO 50 vol % composite cathode at 600degreeC. A 1-dimensional model has been developed in order to understand and predict the the performance of cathodes prepared by LSC infiltration. With the model, it was possible to extract an expression for the area specific resistance associated with oxygen...... surface exchange for the infiltrated LSC. The extracted values are significantly lower than literature values suggesting that the performance of LSC-infiltrated cathodes could not be explained by downscaled microstructure alone. A series of microstructural parameter variations are presented and discussed...

  2. Hollow cathode ion source for application to an implanter

    International Nuclear Information System (INIS)

    A hollow cathode ion source has been studied in order to improve the life-time of an ion source for an ion implanter. Both volatile and refractory elements are shown to be ionized using two types of discharge state of the hollow cathode namely hot and cold cathode discharge. The life-time of LaB6 as the hot cathode is more than 150 h and the ion beam currents reach more than 10 mA cm-2 at the extraction voltage of 10 kV. For the cold cathode operation, stable currents of approx. 40 to 70 μA are extracted of refractory metal ions such as W and Mo. (author)

  3. High Performance Infiltrated Backbones for Cathode-Supported SOFC's

    DEFF Research Database (Denmark)

    Gil, Vanesa; Kammer Hansen, Kent

    2014-01-01

    The concept of using highly ionic conducting backbones with subsequent infiltration of electronically conducting particles has widely been used to develop alternative anode-supported SOFC's. In this work, the idea was to develop infiltrated backbones as an alternative design based on cathode-supported...... printed symmetrical cells. Samples with LSM/YSZ composite and YSZ backbones made with graphite+PMMA as pore formers exhibited comparable Rp values to the screen printed LSM/YSZ cathode. This route was chosen as the best to fabricate the cathode supported cells. SEM micrograph of a cathode supported cell...... with infiltrated LSM nanoparticles is shown in Fig. 1. Figure 1. Cross section of LSM infiltrated cathode supported cell. [Formula]...

  4. Investigation of Endurance Performance of Carbon Nanotube Cathodes

    Science.gov (United States)

    Saito, Nanako; Yamagiwa, Yoshiki; Ohkawa, Yasushi; Nishida, Shin-Ichiro; Kitamura, Shoji

    The Aerospace Research and Development Directorate of the Japan Aerospace Exploration Agency (JAXA) is considering a demonstration of electrodynamic tether (EDT) systems in low Earth orbit (LEO). Carbon nanotubes (CNTs) have some advantages as electron sources compared to conventional Spindt type emitters, and so are expected to be useful in EDT systems. Experiments to investigate the durability of CNT cathodes in a space environment had been conducted in a diode mode, but it was found that electron extraction tests, in which the cathode with a gate electrode is used, are necessary to evaluate the endurance of CNTs more accurately. In this paper, we conducted long duration operating tests of a cathode with a gate. It was found that there was almost no change in cathode performance at current densities below 100 A/m2 even after the cathode was operated for over 500 hours in the high vacuum environment.

  5. Work function distribution for W Ir mixed metal matrix cathodes

    Science.gov (United States)

    Santhosh Kumar, K.; Durga Devi, P.; Ravi, M.; Bhat, K. S.

    2006-06-01

    Mixed metal matrix cathodes have inherent non-uniformity and patchiness of emission due to the presence of two-alloy phase structure on the surface. I- V characteristics of cathode studied in a close spaced diode configuration is one of the easy and cost effective methods to estimate the variation of work function on the cathode surface. Tungsten iridium mixed metal matrix dispenser cathodes of Ø1.4 mm (80 wt.% W-20 wt.% Ir) have been fabricated in the laboratory and their I- V characteristics have been investigated in diode configuration. In this paper the model suggested by Tonnerre et al. has been used to find out the work function distribution of W-Ir cathodes from I- V characteristics. An attempt has been made to correlate the microstructure with the work function values.

  6. Barium depletion study on impregnated cathodes and lifetime prediction

    Science.gov (United States)

    Roquais, J. M.; Poret, F.; le Doze, R.; Ricaud, J. L.; Monterrin, A.; Steinbrunn, A.

    2003-06-01

    In the thermionic cathodes used in cathode ray-tubes (CRTs), barium is the key element for the electronic emission. In the case of the dispenser cathodes made of a porous tungsten pellet impregnated with Ba, Ca aluminates, the evaporation of Ba determines the cathode lifetime with respect to emission performance in the CRT. The Ba evaporation results in progressive depletion of the impregnating material inside the pellet. In the present work, the Ba depletion with time has been extensively characterized over a large range of cathode temperature. Calculations using the depletion data allowed modeling of the depletion as a function of key parameters. The link between measured depletion and emission in tubes has been established, from which an end-of-life criterion was deduced. Taking modeling into account, predicting accelerated life-tests were performed using high-density maximum emission current (MIK).

  7. Barium depletion study on impregnated cathodes and lifetime prediction

    International Nuclear Information System (INIS)

    In the thermionic cathodes used in cathode ray-tubes (CRTs), barium is the key element for the electronic emission. In the case of the dispenser cathodes made of a porous tungsten pellet impregnated with Ba, Ca aluminates, the evaporation of Ba determines the cathode lifetime with respect to emission performance in the CRT. The Ba evaporation results in progressive depletion of the impregnating material inside the pellet. In the present work, the Ba depletion with time has been extensively characterized over a large range of cathode temperature. Calculations using the depletion data allowed modeling of the depletion as a function of key parameters. The link between measured depletion and emission in tubes has been established, from which an end-of-life criterion was deduced. Taking modeling into account, predicting accelerated life-tests were performed using high-density maximum emission current (MIK)

  8. Design of Cathode Heater Assembly for High Power Gyrotron

    Science.gov (United States)

    Bhattacharya, Ranajoy; Khatun, Hasina; Singh, Narendra Kr.; Singh, Udaybir; Sinha, A. K.

    2013-04-01

    A 3D model of dispenser cathode with toroid shape heater assembly is simulated using simulation software, ANSYS Multi-physics. The reported design study of cathode heater assembly of 1 MW 120 GHz gyrotron helps to optimize the input heater power with respect to cathode surface temperature. The simulation study shows that the input power depends strongly on the heater dimension as well as material properties including the potting material. The optimum input power helps to achieve desired current density (10 A/cm2) and cathode surface temperature (1000 °C). Further, the thermal and structural analyses are carried out to study the temperature distribution on the cathode assembly due to the heat dissipation and mechanical strength of the assembly.

  9. Focused cathode design to reduce anode heating during vircator operation

    Science.gov (United States)

    Lynn, Curtis F.; Dickens, James C.; Neuber, Andreas A.

    2013-10-01

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages.

  10. Focused cathode design to reduce anode heating during vircator operation

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, Curtis F.; Dickens, James C.; Neuber, Andreas A. [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

    2013-10-15

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages.

  11. Focused cathode design to reduce anode heating during vircator operation

    International Nuclear Information System (INIS)

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages

  12. New doped tungsten cathodes. Applications to power grid tubes

    International Nuclear Information System (INIS)

    Thermionic emission behavior of tungsten/tungsten carbide modified with rare earth (La, Ce, Y) oxides is examined on account of suitability to deliver important current densities in a thermo-emissive set up and for long lifetime. Work functions of potential cathodes have been determined from Richardson plots for La2O3 doped tungsten and for tungsten covered with variable compositions rare earth tungstates. The role of platinum layers covering the cathode was also examined. Given all cathodes containing mainly lanthanum oxides were good emitters, emphasis was put on service lifetime. Comparisons of lifetime in tungsten doped with rare earth oxides and with rare earth tungstates show that microstructure of the operating cathodes may play the major role in the research of very long lifetime cathodes. Based on these results, tests still running show lifetime compatible with power grid tubes applications. (author)

  13. Comparative simulation studies of plasma cathode electron (PCE) gun

    International Nuclear Information System (INIS)

    Pseudospark discharge based plasma cathode has capability to provide high current density electron beam during discharge process. In this paper an effort has been made to simulate the breakdown processes in the pseudospark discharge based plasma cathode electron gun. The two-dimensional plasma simulation codes VORPAL and OOPIC-Pro have been used and results are compared. The peak discharge current in the plasma cathode electron gun is found to be dependent on aperture size, hollow cathode dimensions, anode voltage and seed electrons energy. The effect of these design parameters on the peak anode current has been analysed by both the codes and results matches well within 10% variation. For the seed electron generation an electron beam trigger source is used to control the discharge process in the hollow cathode cavity. The time span of trigger source has been varied from 1-100 ns to analyze the effect on the peak anode current.

  14. Experimental and ab initio investigations on textured Li–Mn–O spinel thin film cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J., E-mail: Julian.Fischer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Music, D. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 52074 Aachen (Germany); Bergfeldt, T.; Ziebert, C.; Ulrich, S.; Seifert, H.J. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-01

    This paper describes the tailored preparation of nearly identical lithium–manganese–oxide thin film cathodes with different global grain orientations. The thin films were synthesized by rf magnetron sputtering from a LiMn{sub 2}O{sub 4}-target in a pure argon plasma. Under appropriate processing conditions, thin films with a cubic spinel structure and a nearly similar density and surface topography but different grain orientation, i.e. (111)- and (440)-textured films, were achieved. The chemical composition was determined by inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The constitution- and microstructure were evaluated by X-ray diffraction and Raman spectroscopy. The surface morphology and roughness were investigated by scanning electron and atomic force microscopy. The differently textured films represent an ideal model system for studying potential effects of grain orientation on the lithium ion diffusion and electrochemical behavior in LiMn{sub 2}O{sub 4}-based thin films. They are nearly identical in their chemical composition, atomic bonding behavior, surface-roughness, morphology and thickness. Our initial ab initio molecular dynamics data indicate that Li ion transport is faster in (111)-textured structure than in (440)-textured one. - Highlights: • Thin film model system of differently textured cubic Li–Mn–O spinels. • Investigation of the Li–Mn–O thin film mass density by X-ray reflectivity. • Ab initio molecular dynamics simulation on Li ion diffusion in LiMn{sub 2}O{sub 4}.

  15. Experimental and ab initio investigations on textured Li–Mn–O spinel thin film cathodes

    International Nuclear Information System (INIS)

    This paper describes the tailored preparation of nearly identical lithium–manganese–oxide thin film cathodes with different global grain orientations. The thin films were synthesized by rf magnetron sputtering from a LiMn2O4-target in a pure argon plasma. Under appropriate processing conditions, thin films with a cubic spinel structure and a nearly similar density and surface topography but different grain orientation, i.e. (111)- and (440)-textured films, were achieved. The chemical composition was determined by inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The constitution- and microstructure were evaluated by X-ray diffraction and Raman spectroscopy. The surface morphology and roughness were investigated by scanning electron and atomic force microscopy. The differently textured films represent an ideal model system for studying potential effects of grain orientation on the lithium ion diffusion and electrochemical behavior in LiMn2O4-based thin films. They are nearly identical in their chemical composition, atomic bonding behavior, surface-roughness, morphology and thickness. Our initial ab initio molecular dynamics data indicate that Li ion transport is faster in (111)-textured structure than in (440)-textured one. - Highlights: • Thin film model system of differently textured cubic Li–Mn–O spinels. • Investigation of the Li–Mn–O thin film mass density by X-ray reflectivity. • Ab initio molecular dynamics simulation on Li ion diffusion in LiMn2O4

  16. Arc generation from sputtering plasma-dielectric inclusion interactions

    International Nuclear Information System (INIS)

    Arcing during sputter deposition and etching is a significant cause of particle defect generation during device fabrication. In this article we report on the effect of aluminum oxide inclusion size, shape, and orientation on the propensity for arcing during sputtering of aluminum targets. The size, shape, and orientation of a dielectric inclusion plays a major role in determining the propensity for arcing and macroparticle emission. In previous studies we found that there is a critical inclusion size required for arcing to occur. In this article we used high-speed videos, electric arc detection, and measurements of particle defect density on wafers to study the effect of Al2O3 inclusion size, shape, and orientation on arc rate, intensity, and silicon wafer particle defect density. We found that the cross-sectional area of the inclusion exposed to the sputtering plasma is the critical parameter that determines the arc rate and rate of macroparticle emission. Analysis of the arc rate, particle defect density, and the intensity of the optical emission from the arcing plasma indicates that the critical aluminum oxide inclusion area for arcing is 0.22±0.1 mm2 when the sputtering plasma sheath dark-space λd, is 0.51 mm. Inclusions with areas greater than this critical value readily induce arcing and macroparticle ejection during sputtering. Inclusions below this critical size do not cause arcing or macroparticle ejection. When the inclusion major axis is longer than 2λd and lies perpendicular to the sputter erosion track tangent, the arcing activity increases significantly over the case where the inclusion major axis lies parallel to the erosion track tangent

  17. Study of the chemical sputtering in Tore-Supra

    International Nuclear Information System (INIS)

    The work presented in this thesis focuses on the interactions between energetic particles coming from thermonuclear plasma and the inner components of a fusion machine. This interaction induces two major problems: erosion of the wall, and tritium retention. This report treats the erosion of carbon based materials. The first part is devoted to chemical sputtering, that appears to be the principal erosion mechanism, compared to physical sputtering and radiation enhanced sublimation that both can be limited. Chemical sputtering has been studied in situ in the tokamak Tore-Supra for ohmic and lower hybrid (LH) heated discharges, by means of mass spectrometry and optical spectroscopy. We have shown that it is necessary to take into account both methane and heavier hydrocarbons (C2Dx and C3Dy) in the determination of the chemical sputtering yield. It is found that for the ohmic discharges, the sputtering yield of CD4 (YCD4) is highly flux (φ) dependent, showing a variation of the form: YCD4 ∝ φ-0.23. The experimental study also reveals that an increase of the surface temperature induces an augmentation of YCD4. The interpretation and the modelling of the experimental results have been performed with a Monte Carlo code (BBQ. In the second part of this work, we have developed and installed an infrared spectroscopy diagnostic in the 0.8-1.6, μm wavelength range dedicated to the measurement of surface temperature, and the identification of atomic and molecular lines emitted during plasma/wall interactions. In the third part, we present the feasibility study of an in situ tungsten deposition process at low temperature(<80 deg C) in order to suppress the chemical sputtering. This study shows that, with this method call Plasma Assisted Chemical Vapor Deposition (PACVD), we are able to coat the whole inner vessel of a tokamak with 1 μm of tungsten. (author)

  18. Effect of sputtering pressure on crystalline quality and residual stress of AlN films deposited at 823 K on nitrided sapphire substrates by pulsed DC reactive sputtering

    Science.gov (United States)

    Ohtsuka, Makoto; Takeuchi, Hiroto; Fukuyama, Hiroyuki

    2016-05-01

    Aluminum nitride (AlN) is a promising material for use in applications such as deep-ultraviolet light-emitting diodes (UV-LEDs) and surface acoustic wave (SAW) devices. In the present study, the effect of sputtering pressure on the surface morphology, crystalline quality, and residual stress of AlN films deposited at 823 K on nitrided a-plane sapphire substrates, which have high-crystalline-quality c-plane AlN thin layers, by pulsed DC reactive sputtering was investigated. The c-axis-oriented AlN films were homoepitaxially grown on nitrided sapphire substrates at sputtering pressures of 0.4–1.5 Pa. Surface damage of the AlN sputtered films increased with increasing sputtering pressure because of arcing (abnormal electrical discharge) during sputtering. The sputtering pressure affected the crystalline quality and residual stress of AlN sputtered films because of a change in the number and energy of Ar+ ions and Al sputtered atoms. The crystalline quality of AlN films was improved by deposition with lower sputtering pressure.

  19. Correlation of cathode parameters of high power grid tubes with material characteristics of cathode-grid units

    International Nuclear Information System (INIS)

    One way to increase the longevity of dispenser cathodes is based on reducing the Barium evaporation. This can be achieved by the decrease of the reaction 'activity' of the emitter impregnant with the porous tungsten (W) body, which supplies free Barium from the interior of the porous cathode to its surface

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

    KAUST Repository

    Ahn, Yongtae

    2014-02-01

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

  1. Correlation of cathode parameters of high power grid tubes with material characteristics of cathode-grid units

    Science.gov (United States)

    Melnikova, Irina P.; Polyakov, Igor V.; Usanov, Dmitry A.

    2005-09-01

    One way to increase the longevity of dispenser cathodes is based on reducing the Barium evaporation. This can be achieved by the decrease of the reaction "activity" of the emitter impregnant with the porous tungsten (W) body, which supplies free Barium from the interior of the porous cathode to its surface.

  2. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan; Jin, Ke; Du, Yingge; Neeway, James J.; Ryan, Joseph V.; Hu, Dehong; Zhang, Hongliang; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampillai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    For the first time, the use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass, SON68, and layered hole-perovskite oxide thin films were selected as model systems due to their fundamental and practical significance. Our study shows that if the size of analysis areas is same, the highest sputter rate of argon cluster sputtering can be 2-3 times faster than the highest sputter rates of oxygen or cesium sputtering. More importantly, high quality data and high sputter rates can be achieved simultaneously for argon cluster sputtering while this is not the case for cesium and oxygen sputtering. Therefore, for deep depth profiling of insulating samples, the measurement efficiency of argon cluster sputtering can be about 6-15 times better than traditional cesium and oxygen sputtering. Moreover, for a SrTiO3/SrCrO3 bi-layer thin film on a SrTiO3 substrate, the true 18O/16O isotopic distribution at the interface is better revealed when using the argon cluster sputtering source. Therefore, the implementation of an argon cluster sputtering source can significantly improve the measurement efficiency of insulating materials, and thus can expand the application of ToF-SIMS to the study of glass corrosion, perovskite oxide thin films, and many other potential systems.

  3. Extended incident-angle dependence formula of sputter yield

    International Nuclear Information System (INIS)

    We extend a new semi-empirical formula for incident-angle dependence of normalized sputter yield that includes the contribution to sputter yield from the direct knock-out process that was not considered in the previously proposed one. Three parameters included in the new one are estimated for data calculated with ACAT code for D+ ions incident obliquely on C, Fe and W materials in incident-energy regions from several tens of eV to 10 keV. Then, the parameters are expressed with functions of incident energy. The formula with the functions derived well reproduces that using the ACAT data in the whole energy range. (author)

  4. Heteroepitaxial Ge-on-Si by DC magnetron sputtering

    International Nuclear Information System (INIS)

    The growth of Ge on Si(100) by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C), films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.

  5. Advances in sputtered and ion plated solid film lubrication

    Science.gov (United States)

    Spalvins, T.

    1985-01-01

    The glow discharge or ion assisted vacuum deposition techniques, primarily sputtering and ion plating, have rapidly emerged and offer great potential to deposit solid lubricants. The increased energizing of these deposition processes lead to improved adherence and coherence, favorable morphological growth, higher density, and reduced residual stresses in the film. These techniques are of invaluable importance where high precision machines tribo-components require very thin, uniform lubricating films (0.2 m), which do not interface with component tolerances. The performance of sputtered MoS2 films and ion plated Au and Pb films are described in terms of film thickness, coefficient of friction, and wear lives.

  6. Inverted spherical ioniser sputter ion source (IS3)

    International Nuclear Information System (INIS)

    The reflected beam sputter ion source has been found to have an inherent need for frequent readjustment of several voltages during use. Its lack of cylindrical symmetry is reflected in the asymmetry of its beam, and the position and shape of the sputtering Cs+ beam have been shown to depend strongly on the Cs+ current because of space charge effects. There has been a tendency for ion source designs starting from a simple concept to be subjected to continual improvement a process which, while improving one feature, often complicates the originally simple concept, and makes operation more complex

  7. Mechanical and structural properties of sputtered Ni/Ti multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Senthil Kumar, M.; Boeni, P.; Tixier, S.; Clemens, D.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Ni/Ti bilayers have been prepared by dc-magnetron sputtering in order to study their mechanical and structural properties. A remarkable reduction of stress is observed when the Ni layers are sputtered reactively in argon with a high partial pressure of air. The high angle x-ray diffraction studies show a tendency towards amorphisation of the Ni layers with increasing air flow. The low angle measurements indicate a substantial reduction of interdiffusion resulting in smoother interfaces with increasing air content. (author) 2 figs., 2 refs.

  8. Low-Pressure Plane Plasma Discharge Sputtering System

    International Nuclear Information System (INIS)

    Ultra-thin semiconductors and metal films have gained high technological importance in recent years. Sputtering is considered to be the preferable way for industrial thin semiconductor systems preparation. The main goal of our work was to develop a sputtering based method suitable for fine electronic and opto-electronic applications. The basic idea behind the developed method was to create a plane of gas discharge placed between the sputtering target and the growing film in order to enable the sputtered atoms to reach the substrate without collisions. Thus, the shape of the created plasma is viewed as a thin wall. The work was devoted to the modeling and practical implementation of the novel sputtering method. The mean free path of the gas molecules in the vacuum chamber is chosen as the critical parameter that defines the type of the sputtered particle transport and the level of the gas pressure used in the vacuum chamber. The properties and behavior of the plane plasma are considered under the conditions of ballistics (collisionless) and boundary transfer of the sputtered atoms (taking into account the diffusion part as well). The basic properties of the plane plasma were experimentally studied with the Langmuir probe introduced in plasma. The evaluation of electron temperature and ion concentrations was done using the Bohm approximation for collisionless conditions, which were created in the designed system. The measurements were taken in a gas pressure range from 0.2 mTorr up to 5 mTorr in various points of the vacuum chamber: along the plasma plane and in its vicinity. It was found that the electrons with the maximum temperature of about 7-7.5 eV occur along the plasma plane. Positive argon ion concentration was found to vary in the range from 3.5x1011 cm-3 to 6x1011 cm-3 on the plasma axis, depending on the gas pressure. The substrate in the novel system is completely protected from the plasma and the electron irradiation. The substrate temperature does not

  9. Sputtering measurements on CTR materials using Auger electron spectroscopy

    International Nuclear Information System (INIS)

    The sputter yield of Nb, W, C, and Ag by Ar+ in the energy range from 0.5 to 1.5 keV was measured. In addition, the sputter yield for W, C and Ag by H+ at 11.0 keV has been determined. With the exception of carbon, the data are in general agreement with earlier work. For carbon, some discrepancies between the present work and earlier studies are found. It is suggested that major factors contributing to these discrepancies are structural and/or chemical in nature

  10. Cationic fluorinated polymer binders for microbial fuel cell cathodes

    KAUST Repository

    Chen, Guang

    2012-01-01

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

  11. Cathodic Cage Plasma Nitriding: An Innovative Technique

    Directory of Open Access Journals (Sweden)

    R. R. M. de Sousa

    2012-01-01

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

  12. Nanostructured cathode materials for rechargeable lithium batteries

    Science.gov (United States)

    Myung, Seung-Taek; Amine, Khalil; Sun, Yang-Kook

    2015-06-01

    The prospect of drastic climate change and the ceaseless fluctuation of fossil fuel prices provide motivation to reduce the use of fossil fuels and to find new energy conversion and storage systems that are able to limit carbon dioxide generation. Among known systems, lithium-ion batteries are recognized as the most appropriate energy storage system because of their high energy density and thus space saving in applications. Introduction of nanotechnology to electrode material is beneficial to improve the resulting electrode performances such as capacity, its retention, and rate capability. The nanostructure is highly available not only when used alone but also is more highlighted when harmonized in forms of core-shell structure and composites with carbon nanotubes, graphene or reduced graphene oxides. This review covers syntheses and electrochemical properties of nanoscale, nanosized, and nanostructured cathode materials for rechargeable lithium batteries.

  13. Catadioptric aberration correction in cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M. [IBM T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States); Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-04-15

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed.

  14. Catadioptric aberration correction in cathode lens microscopy

    International Nuclear Information System (INIS)

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed

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

    Science.gov (United States)

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

    2010-11-01

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

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

    KAUST Repository

    Yang, Qiao

    2012-04-01

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

  17. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information

    Science.gov (United States)

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan W.; Jin, Ke; Du, Yingge; Neeway, James J.; Ryan, Joseph V.; Hu, Dehong; Zhang, Kelvin H. L.; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampilai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    The use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass (SON68) and layered hole-perovskite oxide thin films were selected as model systems because of their fundamental and practical significance. Our results show that high sputter rates and accurate interfacial information can be achieved simultaneously for argon cluster sputtering, whereas this is not the case for cesium and oxygen sputtering. Therefore, the implementation of an argon cluster sputtering source can significantly improve the analysis efficiency of insulating materials and, thus, can expand its applications to the study of glass corrosion, perovskite oxide thin film characterization, and many other systems of interest.

  18. Simulation of Filament Heater for Uniform Emission from Dispenser Cathode

    Science.gov (United States)

    Singh, Narendra Kr.; Bhattacharya, Ranojoy; Khatun, Hasina; Singh, Udaybir; Sinha, A. K.

    2012-06-01

    This paper presents the design study of toroid shape filament heater for dispenser cathode.The filament heater will be used in cathode assembly of 200 kW 42 GHz gyrotron. A 3 D model of cathode assembly is designed using electromagnetic and thermal simulation software, ANSYS. The simulations are performed for optimizing the input filament heater power with respect to cathode surface temperature. The parametric study shows that the input power and cathode surface temperature depends strongly on the potting material, diameter of filament, number of turns, position and height of the filament heater with respect to cathode pellet. The design analyses are also carried out for two different filament heater materials i.e. tungsten and molybdenum. Further, the thermal, structural and transient analyses are also carried out to study the mechanical strength of the filament heater. It is concluded that the input heater power should be greater than 200 W to achieve cathode surface temperature greater than 1,000°C.

  19. High Performance Cathodes for Li-Air Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yangchuan

    2013-08-22

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

  20. Plasma characterization on carbon fiber cathode by spectroscopic diagnostics

    International Nuclear Information System (INIS)

    This paper mainly investigates plasma characterization on carbon fiber cathodes with and without cesium iodide (CsI) coating powered by a ∼300 ns, ∼200 kV accelerating pulse. It was found that the CsI layers can not only improve the diode voltage, but also maintain a stable perveance. This indicates a slowly changed diode gap or a low cathode plasma expansion velocity. By spectroscopic diagnostics, in the vicinity of the cathode surface the average plasma density and temperature were found to be ∼3 × 1014 cm−3 and ∼5 eV, respectively, for an electron current density of ∼40 A/cm2. Furthermore, there exists a multicomponent plasma expansion toward the anode. The plasma expansion velocity, corresponding to the carbon and hydrogen ions, is estimated to be ∼1.5 cm/μs. Most notably, Cs spectroscopic line was obtained only at the distance ≤ 0.5 mm from the cathode surface. Carbon and hydrogen ions are obtained up to the distance of 2.5 mm from the cathode surface. Cs ions almost remain at the vicinity of the cathode surface. These results show that the addition of CsI enables a slow cathode plasma expansion toward the anode, providing a positive prospect for developing long-pulse electron beam sources. (general)

  1. Cathodic oxygen reduction catalyzed by bacteria in microbial fuel cells.

    Science.gov (United States)

    Rabaey, Korneel; Read, Suzanne T; Clauwaert, Peter; Freguia, Stefano; Bond, Philip L; Blackall, Linda L; Keller, Jurg

    2008-05-01

    Microbial fuel cells (MFCs) have the potential to combine wastewater treatment efficiency with energetic efficiency. One of the major impediments to MFC implementation is the operation of the cathode compartment, as it employs environmentally unfriendly catalysts such as platinum. As recently shown, bacteria can facilitate sustainable and cost-effective cathode catalysis for nitrate and also oxygen. Here we describe a carbon cathode open to the air, on which attached bacteria catalyzed oxygen reduction. The bacteria present were able to reduce oxygen as the ultimate electron acceptor using electrons provided by the solid-phase cathode. Current densities of up to 2.2 A m(-2) cathode projected surface were obtained (0.303+/-0.017 W m(-2), 15 W m(-3) total reactor volume). The cathodic microbial community was dominated by Sphingobacterium, Acinetobacter and Acidovorax sp., according to 16S rRNA gene clone library analysis. Isolates of Sphingobacterium sp. and Acinetobacter sp. were obtained using H(2)/O(2) mixtures. Some of the pure culture isolates obtained from the cathode showed an increase in the power output of up to three-fold compared to a non-inoculated control, that is, from 0.015+/-0.001 to 0.049+/-0.025 W m(-2) cathode projected surface. The strong decrease in activation losses indicates that bacteria function as true catalysts for oxygen reduction. Owing to the high overpotential for non-catalyzed reduction, oxygen is only to a limited extent competitive toward the electron donor, that is, the cathode. Further research to refine the operational parameters and increase the current density by modifying the electrode surface and elucidating the bacterial metabolism is warranted. PMID:18288216

  2. Neutral hydrophilic cathode catalyst binders for microbial fuel cells

    KAUST Repository

    Saito, Tomonori

    2011-01-01

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

  3. Explosive emission cathode plasmas in intense relativistic electron beam diodes

    International Nuclear Information System (INIS)

    An experimental study of cathode plasmas in planar diodes driven by a Sandia Nereus accelerator (270 kV, 60 kA, 70 ns), with particular attention devoted to plasma uniformity and expansion velocity, has been carried out. This diode current density was varied over a factor of ten and the rate of rise of the applied field dE/dt was varied over a factor of six. Different cathode materials, coatings, and surface roughnesses were used and the effects of glow discharge cleaning and in situ heating of the cathode were examined. Framing photography, electron beam dosimetry, perveance measurements, optical interferometry, and (spatially and temporally resolved) spectroscopy were used to diagnose the plasma uniformity, electron beam uniformity, plasma front motion, electron density, plasma composition, motion of distinct species, electron temperature, and ion (and neutral) densities. Electron beam uniformity is seen to be related to cathode plasma uniformity; this uniformity is enhanced by a high value of (the microscopic) dE/dt, which is determined both by the rise time of the applied field and by the cathode surface roughness. The significance of dE/dt is believed to be related to the screening effect of emitted electrons. The motion of the plasma front is seen to be affected by two phenomena. To begin with, all species of the cathode plasma are seen to expand at the same rate. The ions are believed to be accelerated to velocities on the order of 2 to 3 cm/μs in dense cathode spot regions at the cathode surface. Plasma expansion is also influenced by electric pressure effects, which are determined by the shape of the driving power pulse. A simple cathode plasma model, which explains the similarity of plasmas in diodes with greatly differing parameters, is proposed. The relevance of these results to inductively driven diodes, repetitively pulsed diodes, and magnetically insulated transmission lines is also discussed

  4. Some New Views on the Principles of Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jia-xue; FANG Kai-ming; TONG Hong-hui

    2004-01-01

    In this paper, some common phenomena in magnetron sputtering are freshly analyzed and discussed on the basis of the motion of electrons in non-uniform orthogonal electric and magnetic fields. There exist magnetic confinements in three spatial dimensions on moving charged particles (including electrons) in this kind of non-uniform field. They are the longitudinal cycloidal motion, the horizontal simple harmonic-like motion (with varying amplitudes), and the vertical repelling action. The horizontal magnetic confinement in a mirror-like magnetic field keeps glow discharge lane completely parallel to the corridor of magnetic force lines, therefore only an effectively closed magnet array structure can form a relatively uniform and closed discharge lane. The main reasons for electrons' releasing from magnetic confinement are the vertical magnetic repelling force as well as a more and more weak confinement action in outer range etc. The dominant reasons for a comparatively low increase of substrate's temperature are that the density of bombarding electrons near the substrate is relatively low and their spatial distribution is relatively uniform (compared with that near the target surface). The erosion lane with an inverted Gauss's distribution shape on a magnetron sputtered target is due to that,with sputtering, the distribution width of the critical density of electrons shrinks continuously but the sputtering effect in the centerline of the corridor is always the most powerful.

  5. Sodium tungsten bronze thin films by rf sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Anderegg, J.W.

    1977-03-01

    Polycrystalline Na/sub x/WO/sub 3/ films were produced by rf sputtering. Films of low x-value resulted when co-sputtering WO/sub 3/ on a Na/sub 0.83/WO/sub 3/ target, and Na/sub 0/./sub 83/ on WO/sub 3/ target. Films of high x and of mixed phase were produced by sputtering a powder mixture of Na/sub 2/WO/sub 4/ and WO/sub 3/ on a tungsten target. Of the sputtering parameters studied, the substrate temperature is the most critical with temperatures above 500/sup 0/C producing films which were cubic in structure with only a small amount of Tetragonal I. The presence of oxygen up to 3 percent by volume had minimal effect on film quality or x-value. Auger, electron microprobe, SIMS, SEM, x-ray diffraction, and sheet resistivity techniques were used in characterizing these films. Resistivity of the films was a factor of 10 higher than the bulk crystalline data for Na/sub 0/./sub 83/WO/sub 3/.

  6. Nanomechanical characterization of bioglass films synthesized by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Popa, A.C. [National Institute of Materials Physics, 077125 Magurele (Romania); Army Centre for Medical Research, 020012 Bucharest (Romania); Department of Cellular and Molecular Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest (Romania); Marques, V.M.F. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Stan, G.E., E-mail: george_stan@infim.ro [National Institute of Materials Physics, 077125 Magurele (Romania); Husanu, M.A.; Galca, A.C.; Ghica, C. [National Institute of Materials Physics, 077125 Magurele (Romania); Tulyaganov, D.U. [Turin Polytechnic University in Tashkent, 100174 Tashkent (Uzbekistan); Lemos, A.F.; Ferreira, J.M.F. [Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

    2014-02-28

    Bioactive glasses are osteoproductive-type inorganic materials possessing the highest indices of bioactivity in both bulk and thin film forms. The prerequisites for reliable implant-type coatings are both their biological and mechanical performances. Whilst the bioglass films' structural, chemical and biological properties have been studied extensively, information about their mechanical performance is scarce. Here, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, nanoindentation and pull-out measurements were employed to assess the morphological, chemical, structural and mechanical properties of the bioglass films deposited onto Ti substrates by radio-frequency magnetron sputtering (RF-MS). The biological safety of the thin bioglass films was evaluated preliminarily in vitro by investigating the adherence, proliferation and cytotoxicity of fibroblast cells cultivated on their surface. Our study emphasize the versatility of RF-MS, showing how bioglass films' features such as composition, structure, bonding strength, hardness, elastic modulus and biological response can be conveniently adapted by tuning the RF-MS working conditions, and therefore demonstrating the unexplored potential of this deposition technique for preparing quality biomimetic glass coatings. - Highlights: • Adherent bioglass films were synthesized by RF-sputtering on titanium plates. • Different bonding configurations were obtained when tuning sputtering conditions. • Films' biological and mechanical responses vary with their structural arrangement. • Nanomechanical properties were enhanced by allowing O{sub 2} in the sputtering atmosphere.

  7. Plasma properties of RF magnetron sputtering system using Zn target

    International Nuclear Information System (INIS)

    In the present work, we investigate the fundamental properties of magnetron sputtering plasma using Zn target and its deposited Zn thin film. The magnetron sputtering plasma was produced using radio frequency (RF) power supply and Argon (Ar) as ambient gas. A Langmuir probe was used to collect the current from the plasma and from the current intensity, we calculate the electron density and electron temperature. The properties of Zn sputtering plasma at various discharge conditions were studied. At the RF power ranging from 20 to 100 W and gas pressure 5 mTorr, we found that the electron temperature was almost unchanged between 2-2.5 eV. On the other hand, the electron temperature increased drastically from 6×109 to 1×1010cm−3 when the discharge gas pressure increased from 5 to 10 mTorr. The electron microscope images show that the grain size of Zn thin film increase when the discharge power is increased. This may be due to the enhancement of plasma density and sputtered Zn density.

  8. High rate reactive magnetron sputtering of alumina coatings

    Czech Academy of Sciences Publication Activity Database

    Bulíř, Jiří; Novotný, Michal; Pokorný, Petr; Lančok, Ján; Musil, Jindřich

    Warrendale, PA: MRS , 2009. s. 27-28. ISBN N. [E- MRS 2009 Spring Meeting. 08.06.2009-12.06.2009, Strasbourg] Institutional research plan: CEZ:AV0Z10100522 Keywords : reactive pulsed magnetron sputtering * alumina * optical emission spectroscopy * mass spectroscopy Subject RIV: BH - Optics, Masers, Lasers

  9. Characterization of a nanometer-thick sputtered polytetrafluoroethylene film

    Science.gov (United States)

    Li, Lei; Jones, Paul M.; Hsia, Yiao-Tee

    2011-02-01

    Fast growth of nanotechnology, e.g. hard disk drive (HDD) and microelectromechanical system/nanoelectromechanical system (MEMS/NEMS), requires nanometer-thick protection films with high thermal stability and low surface energy. In this paper, we report the characterization results of a nanometer-thick sputtered polytetrafluoroethylene (PTFE) film prepared by radio frequency (RF) sputtering. Atomic force microscopy (AFM) and X-ray reflectivity (XRR) results show that the nanometer-thick sputtered PTFE film has good uniformity. Thermally programmed desorption (TPD) results show that the film is thermally stable up to 430 °C. Surface energy measurement via contact angle method shows that the film has low surface energy with the thickness as low as 1.5 nm. X-ray photoelectron spectroscopy (XPS) data suggests that the film has crosslinked molecular structure, which results in amorphous morphology as shown by X-ray diffraction (XRD) data. Nano-indentation testing shows that the sputtered film has higher hardness and modulus than bulk PTFE. The structure-property relationship has been discussed.

  10. Sputtering of solid neon by keV hydrogen ions

    DEFF Research Database (Denmark)

    Ellegaard, Ole; Schou, Jørgen; Sørensen, H.

    Sputtering of solid Ne with the hydrogen ions H+1, H+2 and H+3 in the energy range 1–10 keV/atom has been studied by means of a quartz microbalance technique. No enhancement in the yield per atom for molecular ions was found. The results for hydrogen ions are compared with data for keV electrons...

  11. Spatiotemporal synchronization of drift waves in a magnetron sputtering plasma

    Czech Academy of Sciences Publication Activity Database

    Martines, E.; Zuin, M.; Cavazzana, R.; Adámek, Jiří; Antoni, V.; Serianni, G.; Spolaore, M.; Vianello, N.

    2014-01-01

    Roč. 21, č. 10 (2014), s. 102309-102309. ISSN 1070-664X Institutional support: RVO:61389021 Keywords : Drift waves * Magnetron sputtering plasma * Spatiotemporal synchronization Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.142, year: 2014 http://dx.doi.org/10.1063/1.4898693

  12. Sputtering of Ag atoms into metastable excited states

    Czech Academy of Sciences Publication Activity Database

    Staudt, C.; Wucher, A.; Bastiaansen, J.; Philipsen, V.; Vervaecke, F.; Vandeweert, E.; Lievens, P.; Silverans, R. E.; Šroubek, Zdeněk

    2002-01-01

    Roč. 66, č. 8 (2002), s. 085415/1-085415/12. ISSN 0163-1829 R&D Projects: GA AV ČR IAA1067801 Institutional research plan: CEZ:AV0Z2067918 Keywords : sputtering * molecular electronic states Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.327, year: 2002

  13. RF Reactive Magnetron Sputter Deposition of Silicon Sub-Oxides

    NARCIS (Netherlands)

    Hattum, E.D. van

    2007-01-01

    RF reactive magnetron plasma sputter deposition of silicon sub oxide E.D. van Hattum Department of Physics and Astronomy, Faculty of Sciences, Utrecht University The work described in the thesis has been inspired and stimulated by the use of SiOx layers in the direct inductive printing technology, w

  14. Evaluation of residual stress in sputtered tantalum thin-film

    Science.gov (United States)

    Al-masha'al, Asa'ad; Bunting, Andrew; Cheung, Rebecca

    2016-05-01

    The influence of deposition conditions on the residual stress of sputtered tantalum thin-film has been evaluated in the present study. Films have been deposited by DC magnetron sputtering and curvature measurement method has been employed to calculate the residual stress of the films. Transitions of tantalum film stress from compressive to tensile state have been observed as the sputtering pressure increases. Also, the effect of annealing process at temperature range of 90-300 °C in oxygen ambient on the residual stress of the films has been studied. The results demonstrate that the residual stress of the films that have been deposited at lower sputtering pressure has become more compressive when annealed at 300 °C. Furthermore, the impact of exposure to atmospheric ambient on the tantalum film stress has been investigated by monitoring the variation of the residual stress of both annealed and unannealed films over time. The as-deposited films have been exposed to pure Argon energy bombardment and as result, a high compressive stress has been developed in the films.

  15. Elementary surface processes during reactive magnetron sputtering of chromium

    International Nuclear Information System (INIS)

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O2 of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidation sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals

  16. Sputtering of solid deuterium by He-ions

    DEFF Research Database (Denmark)

    Schou, Jørgen; Stenum, B.; Pedrys, R.

    2001-01-01

    Sputtering of solid deuterium by bombardment of 3He+ and 4He+ ions was studied. Some features are similar to hydrogen ion bombardment of solid deuterium, but for the He-ions a significant contribution of elastic processes to the total yield can be identified. The thin-film enhancement is more...

  17. Sputtering of Oxygen Ice by Low Energy Ions

    CERN Document Server

    Muntean, E A; Field, T A; Fitzsimmons, A; Hunniford, C A; McCullough, R W

    2015-01-01

    Naturally occurring ices lie on both interstellar dust grains and on celestial objects, such as those in the outer solar system. These ices are continu- ously subjected to irradiation by ions from the solar wind and/or cosmic rays, which modify their surfaces. As a result, new molecular species may form which can be sputtered off into space or planetary atmospheres. We determined the experimental values of sputtering yields for irradiation of oxygen ice at 10 K by singly (He+, C+, N+, O+ and Ar+) and doubly (C2+, N2+ and O2+) charged ions with 4 keV kinetic energy. In these laboratory experiments, oxygen ice was deposited and irradiated by ions in an ultra high vacuum chamber at low temperature to simulate the environment of space. The number of molecules removed by sputtering was observed by measurement of the ice thickness using laser interferometry. Preliminary mass spectra were taken of sputtered species and of molecules formed in the ice by temperature programmed desorption (TPD). We find that the experi...

  18. Effects of oxygen pressure in reactive ion beam sputter deposition of zirconium oxides

    International Nuclear Information System (INIS)

    The mechanism of reactive ion beam sputtering is investigated. The experimental results indicate that the pressure decrease during sputtering, the properties of Zr--O films, and the deposition rate are all strongly influenced by oxygen partial pressure. A new model which takes into account the gettering action of the deposition material and deals with the number of sputtered and gaseous particles is presented for reactive ion beam sputtering of metal. The theoretical values are compared with experimental results of the reactive ion beam sputtering. It is found that the calculated values agree extremely well with the oxygen partial pressure decrease and the deposition rate measured experimentally

  19. High rate bias sputtered LiCoO2 thinfilms as positive electrode for all-solid-state lithium microbatteries

    International Nuclear Information System (INIS)

    Highlights: • High performance all-solid-state Li microbatteries using bias sputtered LiCoO2 films. • High specific capacity of 50 μAh cm−2 μm−1 • Significant decrease in the annealing treatment of deposits from 700°C to 400-500°C. • High rate capability: only 12% capacity decrease in the C/2.5 to 30 C range • Excellent cycle life over 900 cycles (84% capacity retention at C/2.5). - Abstract: A LiCoO2 thin film with a crystalline structure and free of the cubic phase is obtained by adopting a two-step treatment with a combination of bias substrate during RF sputtering and a post-annealing treatment at moderate temperature of 500 °C or 400 °C. All-solid-state Li/LiPON/LiCoO2 lithium batteries are fabricated using such crystalline bias LiCoO2 thin films. The crack-free surface of the cathode thin film and the nanosized LiCoO2 particles ensure an efficient electrochemical behavior and high performance of the battery. The rate capability and the influence of the voltage range on the rechargeable capacity delivered by the battery are investigated as well as cycling properties. A high capacity close to 50 μAh cm−2 μm−1 is demonstrated at 10 μA. cm−2 with an excellent rate capability since 86% of this value is recovered at 30 C without any further damage of the cathode thin film. An excellent cycling behavior of the biased film is demonstrated since after a capacity decay of 12% over the first 100 cycles, the specific capacity practically does not decline over 800 additional cycles at 0.4 C rate. These results compare very well with the best all-solid-state Li microbatteries built with LiCoO2 heat-treated at 700 °C or more. It exemplifies the relevance of using biased LiCoO2 thin films heat-treated at moderate temperature (400 °C-500 °C)

  20. Iron phosphate materials as cathodes for lithium batteries

    CERN Document Server

    Prosini, Pier Paolo

    2011-01-01

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

  1. Rep-rate explosive whisker emission cathode investigations

    Science.gov (United States)

    Litz, Marc S.; Golden, Jeffry

    1994-05-01

    An experiment is underway to study the performance of several materials as field-emission cathodes for low voltage (EQ 100 kV), repetitive (coatings, niobium wire nanocomposite, and poly-crystalline tungsten. Surface emission is monitored by an array of Faraday cups. The `turn-on' time, uniformity of emission, and gap closure time are measured as a function of the spatially averaged, macroscopic electric field at the cathode. The carbon fiber cathode produces the largest current density and has the lowest threshold voltage for emission.

  2. Lanthanum hexaboride hollow cathode for dense plasma production

    International Nuclear Information System (INIS)

    A hollow tube cathode using lanthanum hexaboride as the electron emitter has been designed and constructed. Tests in both argon and hydrogen indicate that this cathode is capable of producing over 800 A of electron current continuously, corresponding to over 25 A/cm2 from the LaB6. The cathode has been operated for over 300 h and exposed to air more than 100 times with no deterioration in emission. Projected lifetime is in excess of 3500 h for the sintered LaB6 piece tested in this configuration. Construction details, performance characteristics, and discussions of space charge limits on emission are described

  3. Resonant cavity operation of a virtual cathode oscillator

    International Nuclear Information System (INIS)

    Gigawatt level virtual cathode sources have been proposed for several applications. These include microwave weapons and drivers for high-energy particle accelerators. Both of these require a microwave source with very high power output that is controllable in frequency and phase. A conventional virtual cathode oscillator will not meet these requirements. The addition of a resonant cavity surrounding the oscillating virtual cathode either alone or pumped with a low-power injection signal, causing it to operate as an amplifier, could greatly influence the performance of this type of source making it more practical for accelerator and weapon applications. The progress on an experiment to test these concepts will be discussed

  4. The approach curve method for large anode-cathode distances

    Energy Technology Data Exchange (ETDEWEB)

    Mammana, Victor P.; Monteiro, Othon R.; Fonseca, Leo R.C.

    2003-09-20

    An important technique used to characterize field emission is the measurement of the emitted current against electric field (IxE). In this work we discuss a procedure for obtaining IxE data based on multiple approach curves. We show that the simulated features obtained for an idealized uniform surface matches available experimental data for small anode-cathode distances, while for large distances the simulation predicts a departure from the linear regime. We also discuss the shape of the approach curves for large anode-cathode distances for a cathode made of carbon nanotubes.

  5. Development of artificial surface layers for thin film cathode materials

    OpenAIRE

    Carrillo Solano, Mercedes Alicia

    2016-01-01

    The present work was based on the investigation of different thin film components of Li ion batteries. A first part was dedicated to the deposition of cathodes in thin film form of a known material, LiCoO2, and an alternative one, Li(NiMnCo)O2 employing physical vapor deposition (PVD) and chemical vapor deposition (CVD), respectively. A second part was focused on the cathode-electrolyte interface for three case studies: 1) as deposited LiCoO2 cathode thin film, 2) ZrO2 coated LiCoO2 thin...

  6. Poisoning studies of an osmium-coated dispenser cathode

    International Nuclear Information System (INIS)

    The results of our studies on the reduction of the emission current from an osmium-alloy-coated dispenser cathode (derivative of the M cathode) due to exposure to various gases or vapors are reported. The primary interest of these studies is poisoning by chemical agents that might be encountered in the vacuum system of an induction linear accelerator. Of the constituents normally found in a tight unbaked vacuum chamber, the cathode is most sensitive to partial pressures of water vapor. Of the vapors studied which might be encountered in an induction accelerator, Freon was the most virulent poison

  7. The cathode test stand for the DARHT second-axis

    International Nuclear Information System (INIS)

    The injector for the DARHT second-axis injector will use an 8-in. thermionic dispenser cathode. Because the cathode is relatively large and requires a large amount of heat (5 kW) there are certain engineering issues that need to be addressed, before the DARHT injector reaches the final design stage. The Cathode Test Stand (CTS) will be used to address those concerns. The CTS is a new facility, presently under construction. The CTS will consist of a high-voltage pulse modulator, a high-vacuum diode test-chamber, and a short beam-transport section with diagnostics. This paper discusses the status of the project

  8. Performance evaluation of printed LiCoO{sub 2} cathodes with PVDF-HFP gel electrolyte for lithium ion microbatteries

    Energy Technology Data Exchange (ETDEWEB)

    Park, Moon-Soo [School of Advanced Materials Science and Engineering, College of Engineering, Yonsei University, Seoul 120-749 (Korea); Samsung Electro-Mechanics Maetan-3-dong, YeongTong-gu, Suwon City, Gyeonggi Province 442-743 (Korea); Hyun, Sang-Hoon [School of Advanced Materials Science and Engineering, College of Engineering, Yonsei University, Seoul 120-749 (Korea); Nam, Sang-Cheol [Nuricell Inc., 4F, GS Caltex New Energy Development Center, 453-2, Seongnae-dong, Gangdong-gu, Seoul 134-030 (Korea); Cho, Sung Back [Advanced Technology Research Center, Agency for Defense Development, Daejeon 305-600 (Korea)

    2008-07-01

    In order to improve the discharge capacity in lithium ion microbatteries, a thick-film cathode was fabricated by a screen printing using LiCoO{sub 2} pastes. The printed cathode showed a different discharge curves when the cell was tested using various (liquid, gel and solid-state) electrolytes. When a cell test was performed with organic liquid electrolyte, the maximum discharge capacity was 200 {mu}Ah cm{sup -2}, which corresponded to approximately 133 mAh g{sup -1} when the loading weight of LiCoO{sub 2} was calculated. An all-solid-state microbattery could be assembled using sputtered LiPON electrolyte, an evaporated Li anode, and printed LiCoO{sub 2} cathode films without delamination or electrical problems. However, the highest discharge capacity showed a very small value (7 {mu}Ah cm{sup -2}). This problem could be improved using a poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) gel electrolyte, which enhanced the contact area and adhesion force between cathode and electrolyte. The discharge value of this cell was measured as approximately 164 {mu}Ah cm{sup -2} ({approx}110 mAh g{sup -1}). As the PVDF-HFP electrolyte had a relatively soft contact property with higher ionic conductance, the cell performance was improved. In addition, the cell can be fabricated in a leakage-free process, which can resolve many safety problems. According to these results, there is a significant possibility that a film prepared using the aforementioned paste with screen printing and PVDF-HFP gel electrolyte is feasible for a microbattery. (author)

  9. Erosion behavior of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Franz, Robert, E-mail: robert.franz@unileoben.ac.at; Mendez Martin, Francisca; Hawranek, Gerhard [Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Polcik, Peter [Plansee Composite Materials GmbH, Siebenbürgerstrasse 23, 86983 Lechbruck am See (Germany)

    2016-03-15

    Al{sub x}Cr{sub 1−x} composite cathodes with Al contents of x = 0.75, 0.5, and 0.25 were exposed to cathodic arc plasmas in Ar, N{sub 2}, and O{sub 2} atmospheres and their erosion behavior was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by x-ray diffraction analysis. Cathode poisoning effects in the reactive N{sub 2} and O{sub 2} atmospheres were nonuniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded center region of the cathodes.

  10. Solar-wind protons and heavy ions sputtering of lunar surface materials

    International Nuclear Information System (INIS)

    Lunar surface materials are exposed to ∼1 keV/amu solar-wind protons and heavy ions on almost continuous basis. As the lunar surface consists of mostly oxides, these materials suffer, in principle, both kinetic and potential sputtering due to the actions of the solar-wind ions. Sputtering is an important mechanism affecting the composition of both the lunar surface and its tenuous exosphere. While the contribution of kinetic sputtering to the changes in the composition of the surface layer of these oxides is well understood and modeled, the role and implications of potential sputtering remain unclear. As new potential-sputtering data from multi-charged ions impacting lunar regolith simulants are becoming available from Oak Ridge National Laboratory's MIRF, we examine the role and possible implications of potential sputtering of Lunar KREEP soil. Using a non-equilibrium model we demonstrate that solar-wind heavy ions' induced sputtering is critical in establishing the timescale of the overall solar-wind sputtering process of the lunar surface. We also show that potential sputtering leads to a more pronounced and significant differentiation between depleted and enriched surface elements. We briefly discuss the impacts of enhanced sputtering on the composition of the regolith and the exosphere, as well as of solar-wind sputtering as a source of hydrogen and water on the moon.

  11. Sputtering and scattering by interaction of low energy noble gas ions with monocrystalline metal surfaces

    International Nuclear Information System (INIS)

    Sputtering and scattering processes in monocrystalline metal surfaces caused by low energy ion bombardment are described. Three aspects of the sputtering process have been studied: (i) the phenomenon of sputtering in preferential directions, (ii) the dependence of sputtering on the projectile target atom mass ratio, and (iii) the transition in sputtering with increasing projectile energy from being a process dominated by multiple collisions in the surface, at the threshold energy, to a process dominated by collision cascades below the surface, at higher energy. The experiments deal with sputtering in the low energy region (projectile energy from 20 to 1000 eV); the projectile ions Ne+, Ar+, Kr+, Xe+ were perpendicularly incident on fcc (100) and fcc (110) Cu, Ag and Au surfaces. Evidence is found for a sputtering process in which light ions reflecting from sub-surface atoms cause the ejection of surface atoms by hitting them from below. (Auth.)

  12. A series of tufted carbon fiber cathodes designed for different high power microwave sources

    Science.gov (United States)

    Liu, Lie; Li, Limin; Zhang, Jun; Zhang, Xiaoping; Wen, Jianchun; Liu, Yonggui

    2008-06-01

    We report the fabrication technique of tufted carbon fiber cathodes for different microwave sources. Three carbon fiber cathodes were constructed, including a planar cathode, an annular cathode, and a cylindrical cathode for radial emission. Experimental investigations on these cathodes were performed in a reflex triode virtual cathode oscillator (vircator), a backward wave oscillator (BWO), and a magnetically insulated transmission line oscillator (MILO), respectively. The pulse duration of microwave emission from the reflex triode vircator was lengthened by using the planar carbon fiber cathode. In the BWO with the annular carbon fiber cathode, the uniform electron beam with a kA /cm2 current density was observed. In addition, carbon fiber has great promise as field emitter for MILOs. These results show that the carbon fiber cathodes can be utilized for electron emission in high power diodes with different structures.

  13. Electrical properties of resistive switches based on Ba1-χSrχTiO3 thin films prepared by RF co-sputtering

    International Nuclear Information System (INIS)

    In this work, was proposed the use of Ba1-χSrχTiO3(0≤x≤1) thin films for the construction of metal-insulator-metal heterostructures; and their great potential for the development of non-volatile resistance memories (ReRAM) is shown. The deposition of Ba1-χSrχTiO3 thin films was done by the RF co-sputtering technique using two magnetron sputtering cathodes with BaTiO3 and SrTiO3 targets. The chemical composition (x parameter) in the deposited Ba1-χSrχTiO3 thin films was varied through the RF powder applied to the targets. The constructed metal-insulator-metal heterostructures were Al/Ba1-χSrχTiO3/nichrome. The I-V measurements of the heterostructures showed that their hysteretic characteristics change depending on the Ba/Sr ratio of the Ba1-χSrχTiO3 thin films; the Ba/Sr ratio was determined by employing the energy dispersive spectroscopy; Sem micrographs showed that Ba1-χSrχTiO3 thin films were uniform without cracks or pinholes. Additionally, the analysis of the X-ray diffraction results indicated the substitutional incorporation of Sr into the BaTiO3 lattice and the obtainment of crystalline films for the entire range of the x values. (Author)

  14. A High Performance Cathode Heater for Hall Thrusters Project

    Data.gov (United States)

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

  15. Intermetallics as cathode materials in the electrolytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-01-01

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

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

    DEFF Research Database (Denmark)

    Wang, W.G.; Mogensen, Mogens Bjerg

    2005-01-01

    LSCF/CGO on YSZ, the Rs was the same as that of our best LSM samples, which indicates good adhesion between LSCF/CGO cathode and YSZ electrolyte. Aging experiment at 800 'C for the cathode of LSCF/CGO on YSZ electrolyte shows a degradation rate of 5 x 10(-4) Omega CM2/h in R-p, while the R-s has no...... degreesC were achieved. These results are roughly six times better than our typical LSM cathodes. Slightly higher R-s was observed in the samples with LSCF/CGO cathode on the YSZ electrolyte with CGO coating due to extra contribution from the thin CGO layer and the CGO/YSZ interface. For the samples with...

  17. Extended area cathode for transverse discharge gas lasers

    International Nuclear Information System (INIS)

    Laser cathodes of extended emission area are disclosed having a plurality of substantially aligned electrically conductive plates spaced from one another and disposed in respective planes perpendicular to the longitudinal axis of the laser housing. Adjacent plates are spaced by a spacing s selected to achieve the ''hollow'' cathode effect and satisfying the relation s = k/p where p is the laser gas pressure and k is a constant determined by the laser gas and lying in the range of from about 5 to about 20 torr-cm. In one embodiment the cathode plates are supported by and attached to a pair of longitudinally extending electrically conductive rods. In another embodiment the cathode consists of a laminated array of alternatively disposed aligned taller and shorter electrically conductive plates. (U.S.)

  18. 12Cao-7Al2o3 Electride Hollow Cathode

    Science.gov (United States)

    Rand, Lauren P. (Inventor); Williams, John D. (Inventor); Martinez, Rafael A. (Inventor)

    2016-01-01

    The use of the electride form of 12CaO-7Al.sub.2O.sub.3, or C12A7, as a low work function electron emitter in a hollow cathode discharge apparatus is described. No heater is required to initiate operation of the present cathode, as is necessary for traditional hollow cathode devices. Because C12A7 has a fully oxidized lattice structure, exposure to oxygen does not degrade the electride. The electride was surrounded by a graphite liner since it was found that the C12A7 electride converts to it's eutectic (CA+C3A) form when heated (through natural hollow cathode operation) in a metal tube.

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

    Science.gov (United States)

    Abdel Reheem, A M; Ahmed, M M; Abdelhamid, M M; Ashour, A H

    2016-08-01

    An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperture is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition. PMID:27587108

  20. High current density nanofilament cathodes for microwave amplifiers

    NARCIS (Netherlands)

    Schnell, J-P.; Minoux, E.; Gangloff, L.; Vincent, P.; Legagneux, P.; Dieumegard, D.; David, J.-F.; Peauger, F.; Hudanski, L.; Teo, K.B.K.; Lacerda, R.; Chhowalla, M.; Hasko, D.G.; Ahmed, H.; Amaratunga, G.A.J.; Milne, W.I.; Vila, L.; Dauginet-De Pra, L.; Demoustier-Champagne, S.; Ferain, E.; Legras, R.; Piraux, L.; Gröening, O.; Raedt, H. De; Michielsen, K.

    2004-01-01

    We study high current density nanofilament cathodes for microwave amplifiers. Two different types of aligned nanofilament array have been studied: first, metallic nanowires grown by electrodeposition into nanoporous templates at very low temperature (T