WorldWideScience

Sample records for rotating cathode arc

  1. Cathodic arcs

    OpenAIRE

    Anders, Andre

    2003-01-01

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas stand out due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bia...

  2. Cathodic arcs

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2003-10-29

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

  3. Filtered cathodic arc source

    Science.gov (United States)

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  4. Thermal conductivity of titanium aluminum silicon nitride coatings deposited by lateral rotating cathode arc

    Energy Technology Data Exchange (ETDEWEB)

    Samani, M.K., E-mail: majid1@e.ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Ding, X.Z. [Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Amini, S. [School of Materials Science and Engineering. Nanyang Technological University, 50 Nanyang Avenue, Singapore (Singapore); Khosravian, N.; Cheong, J.Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Chen, G. [BC Photonics Technological Company, 5255 Woodwards Rd., Richmond, BC V7E 1G9 (Canada); Tay, B.K. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore)

    2013-06-30

    A series of physical vapour deposition titanium aluminum silicon nitride nanocomposite coating with a different (Al + Si)/Ti atomic ratio, with a thickness of around 2.5 μm were deposited on stainless steel substrate by a lateral rotating cathode arc process in a flowing nitrogen atmosphere. The composition and microstructure of the as-deposited coatings were analyzed by energy dispersive X-ray spectroscopy, and X-ray diffraction, and cross-sectional scanning electron microscopy observation. The titanium nitride (TiN) coating shows a clear columnar structure with a predominant (111) preferential orientation. With the incorporation of Al and Si, the crystallite size in the coatings decreased gradually, and the columnar structure and (111) preferred orientation disappeared. Thermal conductivity of the as-deposited coating samples at room temperature was measured by using pulsed photothermal reflectance technique. Thermal conductivity of the pure TiN coating is about 11.9 W/mK. With increasing the (Al + Si)/Ti atomic ratio, the coatings' thermal conductivity decreased monotonously. This reduction of thermal conductivity could be ascribed to the variation of coatings' microstructure, including the decrease of grain size and the resultant increase of grain boundaries, the disruption of columnar structure, and the reduced preferential orientation. - Highlights: • A series of titanium aluminum silicon nitride with different (Al + Si)/Ti atomic ratio were deposited on Fe304. • The composition and microstructure of the as-deposited coatings were analyzed. • Thermal conductivity of the samples was measured by pulsed photothermal reflectance. • With increasing the (Al + Si)/Ti atomic ratio, thermal conductivity decreased. • Reduction of thermal conductivity is ascribed to the variation of its microstructure.

  5. Miniaturized cathodic arc plasma source

    Science.gov (United States)

    Anders, Andre; MacGill, Robert A.

    2003-04-15

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

  6. Thermal conductivity of titanium nitride/titanium aluminum nitride multilayer coatings deposited by lateral rotating cathode arc

    Energy Technology Data Exchange (ETDEWEB)

    Samani, M.K., E-mail: majid1@e.ntu.edu.sg [Novitas, Nanoelectronics Centre of Excellence, School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Ding, X.Z. [Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Khosravian, N. [Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Amin-Ahmadi, B. [Electron Microscopy for materials Science (EMAT), Department of Physics, University of Antwerpen, Groenenborgerlan 171, B-2020 Antwerpen (Belgium); Yi, Yang [Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 117608 (Singapore); Chen, G. [BC Photonics Technological Company, 5255 Woodwards Rd., Richmond, BC V7E 1G9 (Canada); Neyts, E.C.; Bogaerts, A. [Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Tay, B.K. [Novitas, Nanoelectronics Centre of Excellence, School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2015-03-02

    A series of [TiN/TiAlN]{sub n} multilayer coatings with different bilayer numbers n = 5, 10, 25, 50, and 100 were deposited on stainless steel substrate AISI 304 by a lateral rotating cathode arc technique in a flowing nitrogen atmosphere. The composition and microstructure of the coatings have been analyzed by using energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and conventional and high-resolution transmission electron microscopy (HRTEM). XRD analysis shows that the preferential orientation growth along the (111) direction is reduced in the multilayer coatings. TEM analysis reveals that the grain size of the coatings decreases with increasing bilayer number. HRTEM imaging of the multilayer coatings shows a high density misfit dislocation between the TiN and TiAlN layers. The cross-plane thermal conductivity of the coatings was measured by a pulsed photothermal reflectance technique. With increasing bilayer number, the multilayer coatings' thermal conductivity decreases gradually. This reduction of thermal conductivity can be ascribed to increased phonon scattering due to the disruption of columnar structure, reduced preferential orientation, decreased grain size of the coatings and present misfit dislocations at the interfaces. - Highlights: • TiN/TiAlN multilayer coatings with different bilayer number were deposited on SS. • The composition and microstructure of the as-deposited coatings were analyzed. • Thermal conductivity of the coatings was measured by pulsed photothermal reflectance. • Thermal conductivity depends on the coatings' microstructure and number of layers. • With increasing the bilayer number, thermal conductivity decreased.

  7. Characteristics of CrAlSiN + DLC coating deposited by lateral rotating cathode arc PVD and PACVD process

    Science.gov (United States)

    Lukaszkowicz, Krzysztof; Sondor, Jozef; Balin, Katarzyna; Kubacki, Jerzy

    2014-09-01

    Coating system composed of CrAlSiN film covered by diamond-like carbon (DLC)-based lubricant, deposited on hot work tool steel substrate was the subject of the research. The CrAlSiN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. HRTEM investigation shows an amorphous character of DLC layer. It was found that the tested CrAlSiN layer has a nanostructural character with fine crystallites while their average size is less than 10 nm. Based on the XRD pattern of the CrAlSiN, the occurrence of fcc phase was only observed in the coating, the texture direction is perpendicular to the sample surface. Combined SEM, AES and ToF-SIMS studies confirmed assumed chemical composition and layered structure of the coating. The chemical distribution of the elements inside the layers and at the interfaces was analyzed by SEM and AES methods. It was shown that additional CrN layer is present between substrate and CrAlSiN coating. The atomic concentration of the particular elements of DLC and CrAlSiN layer was calculated from the XPS measurements. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.05 and 0.07. The investigated coating reveals high wear resistance. The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate.

  8. A pulsed cathodic arc spacecraft propulsion system

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, P R C; Bilek, M M M; Tarrant, R N; McKenzie, D R [School of Physics, University of Sydney, NSW 2006 Australia (Australia)

    2009-11-15

    We investigate the use of a centre-triggered cathodic arc as a spacecraft propulsion system that uses an inert solid as a source of plasma. The cathodic vacuum arc produces almost fully ionized plasma with a high exhaust velocity (>10{sup 4} m s{sup -1}), giving a specific impulse competitive with other plasma or ion thrusters. A centre trigger design is employed that enables efficient use of cathode material and a high pulse-to-pulse repeatability. We compare three anode geometries, two pulse current profiles and two pulse durations for their effects on impulse generation, energy and cathode material usage efficiency. Impulse measurement is achieved through the use of a free-swinging pendulum target constructed from a polymer material. Measurements show that impulse is accurately controlled by varying cathode current. The cylindrical anode gave the highest energy efficiency. Cathode usage is optimized by choosing a sawtooth current profile. There is no requirement for an exhaust charge neutralization system.

  9. Metrology in arc plasmas - A new cathode

    Science.gov (United States)

    Croche, R.

    1980-02-01

    A new radiating source consisting of an electric arc under argon pressure is described, with power varying between about 0.2 and 1.5 kW, and with the plasma furnishing a continuous spectrum between 115 and 350 nm. The arc functions from 5 to 50 A, with a voltage varying between 30 and 35 V. The cathode of the transfer arc is described in detail, including such advantages as easy igniting of the arc and the possibility of re-sharpening the tip of the cathode. Most important, the new 'knife-shaped' form of the tungsten cathode has improved the stability and reproducibility of the ultraviolet continuum emitted by the plasma of the arc, which is used at the French National Institute of Metrology as a transfer standard of spectral radiance in the vacuum ultraviolet.

  10. 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.

  11. Vacuum arc on the polycrystalline silica cathode

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

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

  12. Cathodic Vacuum Arc Plasma of Thallium

    OpenAIRE

    Yushkov, Georgy Yu.; Anders, Andre

    2006-01-01

    Thallium arc plasma was investigated in a vacuum arc ion source. As expected from previous consideration of cathode materials in the Periodic Table of the Elements, thallium plasma shows lead-like behavior. Its mean ion charge state exceeds 2.0 immediately after arc triggering, reaches the predicted 1.60 and 1.45 after about 100 microsec and 150 microsec, respectively. The most likely ion velocity is initially 8000 m/s and decays to 6500 m/s and 6200 m/s after 100 microsec and 150 micros...

  13. Filtered cathodic arc deposition apparatus and method

    Science.gov (United States)

    Krauss, Alan R.

    1999-01-01

    A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

  14. Effect of cathode model on arc attachment for short high-intensity arc on a refractory cathode

    Science.gov (United States)

    Javidi Shirvan, Alireza; Choquet, Isabelle; Nilsson, Håkan

    2016-12-01

    Various models coupling the refractory cathode, the cathode sheath and the arc at atmospheric pressure exist. They assume a homogeneous cathode with a uniform physical state, and differ by the cathode layer and the plasma arc model. However even the most advanced of these models still fail in predicting the extent of the arc attachment when applied to short high-intensity arcs such as gas tungsten arcs. Cathodes operating in these conditions present a non-uniform physical state. A model taking into account the first level of this non-homogeneity is proposed based on physical criteria. Calculations are done for 5 mm argon arcs with a thoriated tungsten cathode. The results obtained show that radiative heating and cooling of the cathode surface are of the same order. They also show that cathode inhomogeneity has a significant effect on the arc attachment, the arc temperature and pressure. When changing the arc current (100 A, 200 A) the proposed model allows predicting trends observed experimentally that cannot be captured by the homogeneous cathode model unless restricting a priori the size of the arc attachment. The cathode physics is thus an important element to include to obtain a comprehensive and predictive arc model.

  15. Assistant Anode in a Cathodic Arc Plasma Source

    Institute of Scientific and Technical Information of China (English)

    张涛; Paul K. Chu; 张荟星; Ian G. Brown

    2001-01-01

    The performance and characteristics of a cathodic arc plasma source, consisting of a titanium cathode, an anode with and without a tungsten mesh, and a coil producing a focusing magnetic field between the anode and cathode,are investigated. The high transparency and large area of the mesh allow a high plasma flux to penetrate the anode from the cathodic arc. The mesh helps to decrease the arc resistance and the ignition voltage of the cathodic arc in the focusing magnetic field, and to increase the life of the source, which means that the source makes the cathodic arc easily and greatly stabilized during the operation when a focusing magnetic field exists in the source.

  16. Cathodic ARC surface cleaning prior to brazing

    Energy Technology Data Exchange (ETDEWEB)

    Dave, V. R. (Vivek R.); Hollis, K. J. (Kendall J.); Castro, R. G. (Richard G.); Smith, F. M. (Frank M.); Javernick, D. A. (Daniel A.)

    2002-01-01

    Surface cleanliness is one the critical process variables in vacuum furnace brazing operations. For a large number of metallic components, cleaning is usually accomplished either by water-based alkali cleaning, but may also involve acid etching or solvent cleaning / rinsing. Nickel plating may also be necessary to ensure proper wetting. All of these cleaning or plating technologies have associated waste disposal issues, and this article explores an alternative cleaning process that generates minimal waste. Cathodic arc, or reserve polarity, is well known for welding of materials with tenacious oxide layers such as aluminum alloys. In this work the reverse polarity effect is used to clean austenitic stainless steel substrates prior to brazing with Ag-28%Cu. This cleaning process is compared to acid pickling and is shown to produce similar wetting behavior as measured by dynamic contact angle experiments. Additionally, dynamic contact angle measurements with water drops are conducted to show that cathodic arc cleaning can remove organic contaminants as well. The process does have its limitations however, and alloys with high titanium and aluminum content such as nickel-based superalloys may still require plating to ensure adequate wetting.

  17. Rotating Drive for Electrical-Arc Machining

    Science.gov (United States)

    Fransen, C. D.

    1986-01-01

    Rotating drive improves quality of holes made by electrical-arc machining. Mechanism (Uni-tek, rotary head, or equivalent) attached to electrical-arc system. Drive rotates electrode as though it were mechanical drill, while an arc disintegrates metal in workpiece, thereby creating hole. Rotating electrode method often used in electric-discharge machining. NASA innovation is application of technique to electrical-arc machining.

  18. Probabilistic modelling of the high-pressure arc cathode spot displacement dynamic

    CERN Document Server

    Coulombe, S

    2003-01-01

    A probabilistic modelling approach for the study of the cathode spot displacement dynamic in high-pressure arc systems is developed in an attempt to interpret the observed voltage fluctuations. The general framework of the model allows to define simple, probabilistic displacement rules, the so-called cathode spot dynamic rules, for various possible surface states (un-arced metal, arced, contaminated) and to study the resulting dynamic of the cathode spot displacements over one or several arc passages. The displacements of the type-A cathode spot (macro-spot) in a magnetically rotating arc using concentric electrodes made up of either clean or contaminated metal surfaces is considered. Experimental observations for this system revealed a 1/f sup - sup t sup i sup l sup d sup e sup 1 signature in the frequency power spectrum (FPS) of the arc voltage for anchoring arc conditions on the cathode (e.g. clean metal surface), while it shows a 'white noise' signature for conditions favouring a smooth movement (e.g. ox...

  19. Unusual Cathode Erosion Patterns Observed for Steered Arc Sources

    CERN Document Server

    Kolbeck, Jonathan

    2014-01-01

    A cathodic arc source with a magnetron-type magnetic field was investigated for stability, erosion, and compatibility with a linear macroparticle filter. Here we report about unusual arc spot erosion patterns, which were narrow (~ 2 mm) with periodic pits when operating in argon, and broad (~ 10 mm) with periodic groves and ridges when operating in an argon and oxygen mixtures. These observations can be correlated with the ignition probability for type 2 and type 1 arc spots, respectively.

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

    CERN Document Server

    Nemchinsky, V A

    2003-01-01

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

  1. Cathodic Arcs From Fractal Spots to Energetic Condensation

    CERN Document Server

    Anders, Andre

    2009-01-01

    Emphasizes the fractal character of cathode spots, and describes strongly fluctuating plasma properties such as the presence of multiply charged ions that move with supersonic velocity. This book also deals with issues, such as arc source construction, and macroparticle removal. It is intended for scientists, practitioners, and students alike

  2. The fractal nature of vacuum arc cathode spots

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2005-05-27

    Cathode spot phenomena show many features of fractals, for example self-similar patterns in the emitted light and arc erosion traces. Although there have been hints on the fractal nature of cathode spots in the literature, the fractal approach to spot interpretation is underutilized. In this work, a brief review of spot properties is given, touching the differences between spot type 1 (on cathodes surfaces with dielectric layers) and spot type 2 (on metallic, clean surfaces) as well as the known spot fragment or cell structure. The basic properties of self-similarity, power laws, random colored noise, and fractals are introduced. Several points of evidence for the fractal nature of spots are provided. Specifically power laws are identified as signature of fractal properties, such as spectral power of noisy arc parameters (ion current, arc voltage, etc) obtained by fast Fourier transform. It is shown that fractal properties can be observed down to the cutoff by measurement resolution or occurrence of elementary steps in physical processes. Random walk models of cathode spot motion are well established: they go asymptotically to Brownian motion for infinitesimal step width. The power spectrum of the arc voltage noise falls as 1/f {sup 2}, where f is frequency, supporting a fractal spot model associated with Brownian motion.

  3. Ion source based on the cathodic arc

    Science.gov (United States)

    Sanders, David M.; Falabella, Steven

    1994-01-01

    A cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated. An array of electrically isolated rings positioned in the source serves the dual purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles.

  4. Macroparticle generation in DC arc discharge from a WC cathode

    Science.gov (United States)

    Zhirkov, Igor; Polcik, Peter; Kolozsvári, Szilard; Rosen, Johanna

    2017-03-01

    We have studied macroparticle generation from a tungsten carbide cathode used in a dc vacuum arc discharge. Despite a relatively high decomposition/melting point (˜3100 K), there is an intensive generation of visible particles with sizes in the range 20-35 μm. Visual observations during the discharge and scanning electron microscopy of the cathode surface and of collected macroparticles indicate a new mechanism for particle formation and acceleration. Based on the W-C phase diagram, there is an intensive sublimation of carbon from the melt resulting from the cathode spot. The sublimation supports the formation of a sphere, which is accelerated upon an explosion initiated by Joule heating at the critical contact area between the sphere and the cathode body. The explosive nature of the particle acceleration is confirmed by surface features resembling the remains of a splash on the droplet surface.

  5. INFLUENCE OF VACUUM ARC PLASMA EVAPORATOR CATHODE GEOMETRY OF ON VALUE OF ADMISSIBLE ARC DISCHARGE CURRENT

    Directory of Open Access Journals (Sweden)

    I. A. Ivanou

    2015-01-01

    Full Text Available An analysis of main design parameters that determine a level of droplet formation intensity at the generating stage of plasma flow has been given in the paper. The paper considers the most widely used designs of water cooled consumable cathodes. Ti or Ti–Si and Fe–Cr alloys have been taken as a material for cathodes. The following calculated data: average ionic charge Zi for titanium plasma +1.6; for «titanium–silicon plasma» +1.2, an electronic discharge 1.6022 ⋅ 10–19 C, an ion velocity vi = 2 ⋅ 104 m/s, an effective volt energy equivalent of heat flow diverted in the cathode Uк = 12 V, temperature of erosion cathode surface Тп = 550 К; temperature of the cooled cathode surface То = 350 К have been accepted in order to determine dependence of a maximum admissible arc discharge current on cathode height. The calculations have been carried out for various values of the cathode heights hк (from 0.02 to 0.05 m. Diameter of a target cathode is equal to 0.08 m for a majority of technological plasma devices, therefore, the area of the erosion surface is S = 0.005 m2.A thickness selection for a consumable target cathode part in the vacuum arc plasma source has been justified in the paper. The thickness ensures formation of minimum drop phase in the plasma flow during arc cathode material evaporation. It has been shown that a maximum admissible current of an arc discharge is practically equal to the minimum current of stable arcing when thickness of the consumable cathode part is equal to 0.05 m. The admissible discharge current can be rather significant and ensure high productivity during coating process with formation of relatively low amount of droplet phase in the coating at small values of hк.

  6. Thermal analysis of an arc heater electrode with a rotating arc foot

    Science.gov (United States)

    Milos, Frank S.; Shepard, Charles E.

    1993-01-01

    A smoothly rotating arc foot and an arc foot that jumps between multiple sticking points were analyzed using analytic formulations and numerical solution procedures. For each case the temperature distribution for a copper electrode was obtained for the plausible range of operating conditions. It is shown that the smoothly rotating arc foot is an extremely safe mode of operation, whereas the jumping arc foot produces excessively high electrode surface temperatures which are not greatly alleviated by increasing the average rotational frequency of the arc foot. It is suggested to eliminate arc-foot rotation and rely on the distribution of fixed electrodes with stationary arc attachment to avoid electrode failure at high current.

  7. Formation of metal oxides by cathodic arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S.; Anders, A.; Rubin, M.; Wang, Z.; Raoux, S.; Kong, F.; Brown, I.G.

    1995-03-01

    Metal oxide thin films are of interest for a number of applications. Cathodic arc deposition, an established, industrially applied technique for formation of nitrides (e.g. TiN), can also be used for metal oxide thin film formation. A cathodic arc plasma source with desired cathode material is operated in an oxygen atmosphere, and metal oxides of various stoichiometric composition can be formed on different substrates. We report here on a series of experiments on metal oxide formation by cathodic arc deposition for different applications. Black copper oxide has been deposited on ALS components to increase the radiative heat transfer between the parts. Various metal oxides such as tungsten oxide, niobium oxide, nickel oxide and vanadium oxide have been deposited on ITO glass to form electrochromic films for window applications. Tantalum oxide films are of interest for replacing polymer electrolytes. Optical waveguide structures can be formed by refractive index variation using oxide multilayers. We have synthesized multilayers of Al{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/AI{sub 2}O{sub 3}/Si as possible basic structures for passive optoelectronic integrated circuits, and Al{sub 2-x}Er{sub x}O{sub 3} thin films with a variable Er concentration which is a potential component layer for the production of active optoelectronic integrated devices such as amplifiers or lasers at a wavelength of 1.53 {mu}m. Aluminum and chromium oxide films have been deposited on a number of substrates to impart improved corrosion resistance at high temperature. Titanium sub-oxides which are electrically conductive and corrosion resistant and stable in a number of aggressive environments have been deposited on various substrates. These sub-oxides are of great interest for use in electrochemical cells.

  8. Prediction of the cathodic arc root behaviour in a hollow cathode thermal plasma torch

    Energy Technology Data Exchange (ETDEWEB)

    Freton, Pierre; Gonzalez, Jean-Jacques; Escalier, Gaelle, E-mail: pierre.freton@laplace.univ-tlse.f [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, F-31062 Toulouse cedex 9 (France)

    2009-10-07

    The upper part of a well type cathode (WTC) plasma torch is modelled for several conditions in an air medium in the presence of an electric arc. The plasma flow created by the electric arc is described and the results compared with the data from the literature. Special attention is paid to the description of arc root attachment and to its movement due to the balance of forces. A fine description of the magnetic field produced by the external solenoid is reported. The model is based on the Fluent software implemented with specific developments to be adapted to the thermal plasma domain. The paper shows the necessity to provide an accurate description of the external magnetic field due to the strong influence of the radial magnetic field component. Overall, we propose an original approach for arc root movement description which contributes to the understanding of the flow behaviour in the WTC torch.

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

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

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

  10. Characteristics of Single Cathode Cascaded Bias Voltage Arc Plasma

    Science.gov (United States)

    Ou, Wei; Deng, Baiquan; Zeng, Xianjun; Gou, Fujun; Xue, Xiaoyan; Zhang, Weiwei; Cao, Xiaogang; Yang, Dangxiao; Cao, Zhi

    2016-06-01

    A single cathode with a cascaded bias voltage arc plasma source has been developed with a new quartz cathode chamber, instead of the previous copper chambers, to provide better diagnostic observation and access to the plasma optical emission. The cathode chamber cooling scheme is also modified to be naturally cooled only by light emission without cooling water to improve the optical thin performance in the optical path. A single-parameter physical model has been developed to describe the power dissipated in the cascaded bias voltage arc discharge argon plasmas, which have been investigated by utilizing optical emission spectroscopy (OES) and Langmuir probe. In the experiments, discharge currents from 50 A to 100 A, argon flow rates from 800 sccm to 2000 sccm and magnetic fields of 0.1 T and 0.2 T were chosen. The results show: (a) the relationship between the averaged resistivity and the averaged current density exhibits an empirical scaling law as \\barη \\propto \\bar {j}-0.63369 and the power dissipated in the arc has a strong relation with the filling factor; (b) through the quartz, the argon ions optical emission lines have been easily observed and are dominating with wavelengths between 340 nm and 520 nm, which are the emissions of Ar+-434.81 nm and Ar+-442.60 nm line, and the intensities are increasing with the arc current and decreasing with the inlet argon flow rate; and (c) the electron density and temperature can reach 2.0 × 1019 m-3 and 0.48 eV, respectively, under the conditions of an arc current of 90 A and a magnetic field of 0.2 T. The half-width of the ne radial profile is approximatively equal to a few Larmor radii of electrons and can be regarded as the diameter of the plasma jet in the experiments. supported by the International Thermonuclear Experimental Reactor (ITER) Program Special of Ministry of Science and Technology (No. 2013GB114003), and National Natural Science Foundation of China (Nos. 11275135, 11475122)

  11. Composition demixing effect on cathodic arc ion plating

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The composition demixing effect has been found often in alloy coatings deposited by cathodic arc ion plating using various alloy cathode targets.The characteristics of composition demixing phenomena were summarized.Beginning with the ionization zone near the surface of the cathode target, a physical model in terms of the ions generated in the ionization zone and their movement in the plating room modified by bias electric field was proposed.Based on the concept of electric charge state, the simulation calculation of the composition demixing effect was carried out.The percentage of atoms of an element in coating and from the alloy target was demonstrated by direct comparison.The influences of the composition change of the alloy target and the bias electric field on the composition demixing effect were discussed in detail.It is also proposed that the average charge states of the elements may be used to calculate the composition demixing effect and to design the composition of the alloy target.

  12. 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.

  13. Filtered cathodic arc deposition with ion-species-selectivebias

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre; Pasaja, Nitisak; Sansongsiri, Sakon; Lim, SunnieH.N.

    2006-10-05

    A dual-cathode arc plasma source was combined with acomputer-controlled bias amplifier such as to synchronize substrate biaswith the pulsed production of plasma. In this way, bias can be applied ina material-selective way. The principle has been applied to the synthesismetal-doped diamond-like carbon films, where the bias was applied andadjusted when the carbon plasma was condensing, and the substrate was atground when the metal was incorporated. In doing so, excessive sputteringby too-energetic metal ions can be avoided while the sp3/sp2 ratio can beadjusted. It is shown that the resistivity of the film can be tuned bythis species-selective bias. The principle can be extended tomultiple-material plasma sources and complex materials

  14. Transition characteristics from radio-frequency discharge to arc in hollow cathode configuration

    Institute of Scientific and Technical Information of China (English)

    许建平; 巩春志; 吴明忠; 田修波

    2014-01-01

    The technique ofglow discharges in radio frequency configuration was applied to ignite hollow cathode vacuum arc discharge.The effect of discharge parameters on the building up of hollow cathode arc discharge was investigated.The emission spectrum during the vacuum arc ignition process was measured to disclose the discharge dynamics.There exists a threshold radio frequency power (300 W),beyond which hollow cathode is in γmode discharge status while radio frequency discharge changes into the arc discharge.With the increase of the radio frequency power,the plasma temperature and electronic density increase,and the discharge mode transits more rapidly.The ignition time ofhollow cathode vacuum arc discharge is less than 4 s with a radio frequency power of700 W.

  15. Neutral beam dump with cathodic arc titanium gettering.

    Science.gov (United States)

    Smirnov, A; Krivenko, A S; Murakhtin, S V; Savkin, V Ya; Korepanov, S A; Putvinski, S

    2011-03-01

    An incomplete neutral beam capture can degrade the plasma performance in neutral beam driven plasma machines. The beam dumps mitigating the shine-through beam recycling must entrap and retain large particle loads while maintaining the beam-exposed surfaces clean of the residual impurities. The cathodic arc gettering, which provides high evaporation rate coupled with a fast time response, is a powerful and versatile technique for depositing clean getter films in vacuum. A compact neutral beam dump utilizing the titanium arc gettering was developed for a field-reversed configuration plasma sustained by 1 MW, 20-40 keV neutral hydrogen beams. The titanium evaporator features a new improved design. The beam dump is capable of handling large pulsed gas loads, has a high sorption capacity, and is robust and reliable. With the beam particle flux density of 5 × 10(17) H∕(cm(2) s) sustained for 3-10 ms, the beam recycling coefficient, defined as twice the ratio of the hydrogen molecular flux leaving the beam dump to the incident flux of high-energy neutral atoms, is ∼0.7. The use of the beam dump allows us to significantly reduce the recycling of the shine-through neutral beam as well as to improve the vacuum conditions in the machine.

  16. Macroparticles Reduction Using Filter Free Cathodic Vacuum Arc Deposition Method in ZnO Thin Films.

    Science.gov (United States)

    Yuvakkumar, R; Peranantham, P; Nathanael, A Joseph; Nataraj, D; Mangalaraj, D; Hong, Sun Ig

    2015-03-01

    We report a new method to reduce macroparticles in ZnO thin films using filter free cathodic vacuum arc deposition without using any cooling arrangements operated at low arc current. The detailed mechanism has been proposed to reduce macroparticles during thin film deposition. The successful reduction of macroparticles was confirmed employing FESEM-EDX studies. FESEM images of ZnO thin films deposited with cathode spot to substrate distance from 10 to 20 cm revealed that the population of the macroparticles were reduced with the increase of cathode spot to substrate distances at low arc current. The prepared ZnO films were characterised and showed good structural and optical properties.

  17. Modeling of mixing and interaction of multi-cathode spot vacuum arc jets

    Science.gov (United States)

    Wang, Lijun; Qin, Kang; Deng, Jie; Jia, Shenli

    2016-12-01

    Vacuum arc consists of cathode spot and mixing zone, arc column and anode zone. The separate jets and the mixing zone should be considered in the model of diffuse arc. Moreover, the interaction between the plasma jets in multi-cathode spot vacuum arc also is very important. In this paper, mixing and interaction of multi-cathode spot vacuum arc jets were studied through simulation. To completely investigate the mixing and interaction of vacuum arc jets, a steady 3D Magneto-Hydro-Dynamic (MHD) modeling was established. In order to find out the influence of different parameters on mixing and interaction of vacuum arc jets, simulations with different parameters such as currents, angel of vacuum arc jets, with or without electromagnetic equations, tilted jets and different height of mixing zone were conducted. The simulation results show that the densities of ion number and plasma pressure as well as ion temperature increase with the increase of arc current, while the plasma velocity decreases. The jet center is more deviated from the cathode center with the increase of angle of tilted jets.

  18. Characterization of plasma chemistry and ion energy in cathodic arc plasma from Ti-Si cathodes of different compositions

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, A. O.; Zhirkov, I.; Dahlqvist, M.; Jensen, J.; Hultman, L.; Rosen, J. [Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping (Sweden)

    2013-04-28

    Arc plasma from Ti-Si compound cathodes with up to 25 at. % Si was characterized in a DC arc system with respect to chemistry and charge-state-resolved ion energy. The plasma ion composition showed a lower Si content, diverging up to 12 at. % compared to the cathode composition, yet concurrently deposited films were in accordance with the cathode stoichiometry. Significant contribution to film growth from neutrals is inferred besides ions, since the contribution from macroparticles, estimated by scanning electron microscopy, cannot alone account for the compositional difference between cathode, plasma, and film. The average ion charge states for Ti and Si were higher than reference data for elemental cathodes. This result is likely related to TiSi{sub x} phases of higher cohesive energies in the compound cathodes and higher effective electron temperature in plasma formation. The ion energy distributions extended up to {approx}200 and {approx}130 eV for Ti and Si, respectively, with corresponding average energies of {approx}60 and {approx}30 eV. These averages were, however, not dependent on Si content in the cathode, except for 25 at. % Si where the average energies were increased up to 72 eV for Ti and 47 eV for Si.

  19. Hydrodynamics of the molten metal in a vacuum arc cathode spot at near-threshold currents

    Science.gov (United States)

    Mesyats, G. A.; Zubarev, N. M.

    2013-05-01

    The extrusion of the molten metal from a microcrater formed on a metal cathode during the operation of a vacuum arc is considered. The problem is thought to be similar to the classical hydrodynamic problem of a liquid drop impact on a solid surface. Based on this analogy, the conditions are analyzed under which the liquid will change its regular behavior (spreading over the cathode surface) into a singular behavior (formation of microjets and droplets). It is shown that the conditions realized in vacuum arc cathode spots at near-threshold currents are close to the threshold conditions for splashing of the molten metal. This points to a considerable contribution of hydrodynamic processes to the self-sustained operation of a vacuum arc and, in particular, gives grounds to relate the existence of a threshold arc current to the existence of a splashing threshold for liquid metal.

  20. 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.

  1. Joule heat generation in thermionic cathodes of high-pressure arc discharges

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M. S.; Cunha, M. D. [Departamento de Fisica, CCCEE, Universidade da Madeira, Largo do Municipio, 9000 Funchal (Portugal)

    2013-02-14

    The nonlinear surface heating model of plasma-cathode interaction in high-pressure arcs is extended to take into account the Joule effect inside the cathode body. Calculation results are given for different modes of current transfer to tungsten cathodes of different configurations in argon plasmas of atmospheric or higher pressures. Special attention is paid to analysis of energy balances of the cathode and the near-cathode plasma layer. In all the cases, the variation of potential inside the cathode is much smaller than the near-cathode voltage drop. However, this variation can be comparable to the volt equivalent of the energy flux from the plasma to the cathode and then the Joule effect is essential. Such is the case of the diffuse and mixed modes on rod cathodes at high currents, where the Joule heating causes a dramatic change of thermal and electrical regimes of the cathode. The Joule heating has virtually no effect over characteristics of spots on rod and infinite planar cathodes.

  2. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hao; ZHU Fengsen; TU Xin; BO Zheng; CEN Kefa; LI Xiaodong

    2016-01-01

    In this work,a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions.The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals,high speed photography,and optical emission spectroscopic diagnostics.Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g.,10-20 L/min) to maintain a long arc length and reasonable plasma discharge zone,in this RGA system,a lower gas flow rate (e.g.,2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions.Two different motion patterns can be clearly observed in the N2 and air RGA plasmas.The time-resolved arc voltage signals show that three different arc dynamic modes,the arc restrike mode,takeover mode,and combined modes,can be clearly identified in the RGA plasmas.The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate.

  3. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Science.gov (United States)

    Zhang, Hao; Zhu, Fengsen; Tu, Xin; Bo, Zheng; Cen, Kefa; Li, Xiaodong

    2016-05-01

    In this work, a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions. The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals, high speed photography, and optical emission spectroscopic diagnostics. Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g., 10-20 L/min) to maintain a long arc length and reasonable plasma discharge zone, in this RGA system, a lower gas flow rate (e.g., 2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions. Two different motion patterns can be clearly observed in the N2 and air RGA plasmas. The time-resolved arc voltage signals show that three different arc dynamic modes, the arc restrike mode, takeover mode, and combined modes, can be clearly identified in the RGA plasmas. The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate. supported by National Natural Science Foundation of China (No. 51576174), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120101110099) and the Fundamental Research Funds for the Central Universities (No. 2015FZA4011)

  4. Vacuum arc cathode spot motion in oblique magnetic fields: An interpretation of the Robson experiment

    Science.gov (United States)

    Beilis, I. I.

    2016-09-01

    A model was developed of vacuum arc cathode spot motion in a magnetic field that obliquely intercepts the cathode surface. The model takes into account a force under an electric field caused by retrograde spot motion across the normal component of the magnetic field, producing a drift velocity component in the direction of the acute angle between the magnetic field and the cathode surface. The relationship between velocity of the retrograde direction and drift velocity of the cathode spot motion to the acute angle was developed. The dependencies of the drift angle θ on the acute angle φ, magnetic field strength B, and arc current I were calculated. It was found that the calculated θ increased with φ, B, and I in accordance with Robson's measurements.

  5. Morphology and microstructure evolution of Ti-50 at.% Al cathodes during cathodic arc deposition of Ti-Al-N coatings

    Science.gov (United States)

    Syed, Bilal; Zhu, Jianqiang; Polcik, Peter; Kolozsvari, Szilard; Hâkansson, Greger; Johnson, Lars; Ahlgren, Mats; Jöesaar, Mats; Odén, Magnus

    2017-06-01

    Today's research on the cathodic arc deposition technique and coatings therefrom primarily focuses on the effects of, e.g., nitrogen partial pressure, growth temperature, and substrate bias. Detailed studies on the morphology and structure of the starting material—the cathode—during film growth and its influence on coating properties at different process conditions are rare. This work aims to study the evolution of the converted layer, its morphology, and microstructure, as a function of the cathode material grain size during deposition of Ti-Al-N coatings. The coatings were reactively grown in pure N2 discharges from powder metallurgically manufactured Ti-50 at.% Al cathodes with grain size distribution averages close to 1800, 100, 50, and 10 μm, respectively, and characterized with respect to microstructure, composition, and mechanical properties. The results indicate that for the cathode of 1800 μm grain size the disparity in the work function among parent phases plays a dominant role in the pronounced erosion of Al, which yields the coatings rich in macro-particles and of high Al content. We further observed that a reduction in the grain size of Ti-50 at.% Al cathodes to 10 μm provides favorable conditions for self-sustaining reactions between Ti and Al phases upon arcing to form γ phase. The combination of self-sustaining reaction and the arc process not only result in the formation of hole-like and sub-hole features on the converted layer but also generate coatings of high Al content and laden with macro-particles.

  6. Cathodic arc sputtering of functional titanium oxide thin films, demonstrating resistive switching

    Science.gov (United States)

    Shvets, Petr; Maksimova, Ksenia; Demin, Maxim; Dikaya, Olga; Goikhman, Alexander

    2017-05-01

    The formation of thin films of the different stable and metastable titanium oxide phases is demonstrated by cathode arc sputtering of a titanium target in an oxygen atmosphere. We also show that sputtering of titanium in vacuum yields the formation of titanium silicides on the silicon substrate. The crystal structure of the produced samples was investigated using Raman spectroscopy and X-ray diffraction. We conclude that cathode arc sputtering is a flexible method suitable for producing the functional films for electronic applications. The functionality is verified by the memory effect demonstration, based on the resistive switching in the titanium oxide thin film structure.

  7. Cathodic arc sputtering of functional titanium oxide thin films, demonstrating resistive switching

    Energy Technology Data Exchange (ETDEWEB)

    Shvets, Petr, E-mail: pshvets@innopark.kantiana.ru; Maksimova, Ksenia; Demin, Maxim; Dikaya, Olga; Goikhman, Alexander

    2017-05-15

    The formation of thin films of the different stable and metastable titanium oxide phases is demonstrated by cathode arc sputtering of a titanium target in an oxygen atmosphere. We also show that sputtering of titanium in vacuum yields the formation of titanium silicides on the silicon substrate. The crystal structure of the produced samples was investigated using Raman spectroscopy and X-ray diffraction. We conclude that cathode arc sputtering is a flexible method suitable for producing the functional films for electronic applications. The functionality is verified by the memory effect demonstration, based on the resistive switching in the titanium oxide thin film structure.

  8. Dynamics of cathode spots in low-pressure arc plasma removing oxide layer on steel surfaces

    Science.gov (United States)

    Tang, Z. L.; Yang, K.; Liu, H. X.; Zhang, Y. C.; Li, H.; Zhu, X. D.

    2016-03-01

    The dynamics of cathode spots has been investigated in low-pressure arc plasma for removing oxide layer on low carbon steel surfaces. The motion of cathode spots was observed with a high speed camera, and the arc voltage was analyzed by fast Fourier transform. The spots move on clean steel surface as a random walk, and the low-frequency components dominated the voltage waveform. However, the spots on steel surfaces with oxide layer tend to burn on the rim of the eroded area formed in the previous arcing, and the low-frequency components decrease correspondingly. The "color" of the colored random noise for arc voltage varies from the approximate brown noise for clean steel surface to pink noise for thick oxide layer, where the edge effect of boundary is considered to play a significant role.

  9. The evolution of ion charge states in cathodic vacuum arc plasmas: a review

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2011-12-18

    Cathodic vacuum arc plasmas are known to contain multiply charged ions. 20 years after “Pressure Ionization: its role in metal vapour vacuum arc plasmas and ion sources” appeared in vol. 1 of Plasma Sources Science and Technology, it is a great opportunity to re-visit the issue of pressure ionization, a non-ideal plasma effect, and put it in perspective to the many other factors that influence observable charge state distributions, such as the role of the cathode material, the path in the density-temperature phase diagram, the “noise” in vacuum arc plasma as described by a fractal model approach, the effects of external magnetic fields and charge exchange collisions with neutrals. A much more complex image of the vacuum arc plasma emerges putting decades of experimentation and modeling in perspective.

  10. Influence of Jet Angle and Ion Density of Cathode Side on Low Current Vacuum Arc Characteristics

    Institute of Scientific and Technical Information of China (English)

    WANG Lijun; JIA Shenli; SHI Zongqian

    2008-01-01

    In this study, the influence of the initial jet angles (IJAs) and ion number densities (INDs) at the cathode side on the low current vacuum arc (LCVA) characteristics is simulated and analysed. The results show that the ion temperature, electron temperature, ion number density, axial current density and plasma pressure all decrease with the increase of the cathode IJAs. It is also shown that LCVA can cause a current constriction for lower cathode IND, and the anode sheath potential is more nonuniform, which is mainly related to the nonuniform distribution of the axial current density at the anode side.

  11. Lifetime of hydrogenated composite cathodes in a vacuum arc ion source

    Energy Technology Data Exchange (ETDEWEB)

    Savkin, K. P., E-mail: savkin@opee.hcei.tsc.ru; Frolova, V. P.; Nikolaev, A. G.; Yushkov, G. Yu. [Institute of High Current Electronics SB RAS, Tomsk 634055 (Russian Federation); Oks, E. M. [Institute of High Current Electronics SB RAS, Tomsk 634055 (Russian Federation); Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation); Barengolts, S. A. [Prokhorov General Physics Institute RAS, Moscow 119991 (Russian Federation)

    2016-02-15

    The paper reports on a study of the mass-charge state of the plasma produced in a vacuum arc discharge with composite cathodes which were copper-disk coated with a hydrogenated Zr film of thicknesses 9, 22, and 35 μm. The cathodes allow the generation of multicomponent gas and metal ion beams with a hydrogen ion content from several to several tens of percent. Also investigated is the dependence of the H ion fraction in a beam on the Zr film thickness during erosion to the point of disappearance of Zr peaks in mass-charge spectra. The ability of the vacuum arc system to produce H ions is analyzed by analyzing the cathode lifetime as a function of the film thickness and pulse repetition frequency.

  12. Distribution of Cathode Spots in Vacuum Arc Under Nonuniform Axial Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    SHI Zong-qian; JIA Shen-li; WANG Li-jun; LI Xing-wen; WANG Zheng

    2007-01-01

    Recent results on the distribution of vacuum arc cathode spots (CSs) in nonuniform axial magnetic field (AMF) are presented.Based on previous studies,we deem that two contrary influences of AMF,inward effect and outward effect,are attributed to CSs distribution.With this notion,we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes.Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device (CCD) camera. Experimental results agreed well with the theoretical analysis.

  13. Silicon etch with chromium ions generated by a filtered or non-filtered cathodic arc discharge.

    Science.gov (United States)

    Scopece, Daniele; Döbeli, Max; Passerone, Daniele; Maeder, Xavier; Neels, Antonia; Widrig, Beno; Dommann, Alex; Müller, Ulrich; Ramm, Jürgen

    2016-01-01

    The pre-treatment of substrate surfaces prior to deposition is important for the adhesion of physical vapour deposition coatings. This work investigates Si surfaces after the bombardment by energetic Cr ions which are created in cathodic arc discharges. The effect of the pre-treatment is analysed by X-ray diffraction, Rutherford backscattering spectroscopy, scanning electron microscopy and in-depth X-ray photoemission spectroscopy and compared for Cr vapour produced from a filtered and non-filtered cathodic arc discharge. Cr coverage as a function of ion energy was also predicted by TRIDYN Monte Carlo calculations. Discrepancies between measured and simulated values in the transition regime between layer growth and surface removal can be explained by the chemical reactions between Cr ions and the Si substrate or between the substrate surface and the residual gases. Simulations help to find optimum and more stable parameters for specific film and substrate combinations faster than trial-and-error procedure.

  14. Composition Control of Alloy Coatings and Composition Designof Cathode Targets in Multi-Arc Ion Plating

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The composition from alloy cathode target to alloy coating generally changes to some extentin multi-arc ion plating. This demixing effect leads to the difficulties in the control of alloycomposition of coating and in the design of composition of alloy cathode target. A new simple formula,is proposed in present work to deal with the problem. According to this formula, the composition of alloy coating can be calculated bymeans of the degrees of ionization of alloy elements. The results of calculation agree with theexperimental ones within very limited error range. Modifying the formula into another form,the design for alloy composition of cathode target can be conveniently carried out, and the ideal composition of alloy coating can be obtained.

  15. Account of near-cathode sheath in numerical models of high-pressure arc discharges

    Science.gov (United States)

    Benilov, M. S.; Almeida, N. A.; Baeva, M.; Cunha, M. D.; Benilova, L. G.; Uhrlandt, D.

    2016-06-01

    Three approaches to describing the separation of charges in near-cathode regions of high-pressure arc discharges are compared. The first approach employs a single set of equations, including the Poisson equation, in the whole interelectrode gap. The second approach employs a fully non-equilibrium description of the quasi-neutral bulk plasma, complemented with a newly developed description of the space-charge sheaths. The third, and the simplest, approach exploits the fact that significant power is deposited by the arc power supply into the near-cathode plasma layer, which allows one to simulate the plasma-cathode interaction to the first approximation independently of processes in the bulk plasma. It is found that results given by the different models are generally in good agreement, and in some cases the agreement is even surprisingly good. It follows that the predicted integral characteristics of the plasma-cathode interaction are not strongly affected by details of the model provided that the basic physics is right.

  16. Charge state, angular distribution, and kinetic energy of ions from multicomponent-cathodes in vacuum arc devices

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaev, A. G., E-mail: nik@opee.hcei.tsc.ru; Savkin, K. P.; Yushkov, G. Yu.; Frolova, V. P. [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Ave., Tomsk 634055 (Russian Federation); Oks, E. M. [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Ave., Tomsk 634055 (Russian Federation); Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Ave., Tomsk 634050 (Russian Federation); Barengolts, S. A. [Prokhorov General Physics Institute RAS, 38 Vavilov St., Moscow 119991 (Russian Federation)

    2014-12-07

    We present research results on vacuum arc plasma produced with multicomponent cathode made of several different elements. The ion mass-to-charge-state spectra of the plasmas were studied by time-of-flight spectrometry. The angular distributions of different ion species were measured, and the kinetic energy of their directed (streaming) motion was determined. It is shown that the fractional composition of ions of different cathode components in the plasma flow from the cathode spot closely matches the fractional content of these components in the composite cathode. The charge states of ions of the various cathode components are determined by the average electron temperature in the cathode spot plasma. The angular distribution of lower mass ions in the plasma from a multicomponent cathode is less isotropic and broader than for the plasma from a single-component cathode of the same light element. The directed kinetic energies of the ions of the different components for plasma from a multicomponent cathode are lower for lighter elements and greater for heavier elements compared to the ion directed energy for plasmas from single-component cathodes made of the same materials. The physical processes responsible for these changes in the ion charge states in multicomponent-cathode vacuum arc plasma are discussed.

  17. Paleomagnetic rotations and the kinematics of the Gibraltar arc

    Science.gov (United States)

    Platzman, E. S.

    1992-04-01

    Paleomagnetic investigations of a Mesozoic limestone sequence around the Gibraltar arc show that there have been large systematic rotations about a vertical axis and imply that there must have been a significant component of westward motion within the Betic-Rif orogenic belt. Rotations of the Late Jurassic and Late Cretaceous limestones in the Betic Cordillera of southern Spain are clockwise, with the exception of the unrotated Sierra Gorda, whereas the Jurassic sites in the Rif Mountains of Morocco are rotated counterclockwise, except in the area around Tetuan. These data are generally consistent with formation of the arc either by a westward-moving Alboran microplate or by extensional collapse of a collisional mountain chain. The former model, however, fails to recognize the nonrigid, nonplate-like character of the Alboran domain and lacks a definable driving mechanism. A model of a collapsing east-west-elongated ridge that takes into account the obliquity of the convergence along the active margin may provide mechanisms both for the observed rotations and for the large westward component of motion, and therefore can explain the geometry of the Gibraltar are.

  18. Study on weld formation in a novel rotating arc horizontal GMAW

    Institute of Scientific and Technical Information of China (English)

    Guo Ning; Lin Sanbao; Fan Chenglei; Zhang Yaqi; Yang Chunli

    2009-01-01

    A novel rotating arc horizontal welding process was developed for solving the sagging of the molten pool which bottlenecks the application and the development of the horizontal welding. The principle of the effect of the rotating arc on the molten pool is that the rotating arc process not only can reduce the welding heat input by prolonging the welding path in the same welding distance caused by the arc rotation, but also disperse the arc force to affect the sidewall periodically to support the molten metal near the upper sidewall. The effects of the rotating speed and arc voltage on the weld formation were studied.The results indicate that there is an appropriate range of the rotating speed and the arc voltage to obtain the defect free horizontal welding.

  19. A centre-triggered magnesium fuelled cathodic arc thruster uses sublimation to deliver a record high specific impulse

    Science.gov (United States)

    Neumann, Patrick R. C.; Bilek, Marcela; McKenzie, David R.

    2016-08-01

    The cathodic arc is a high current, low voltage discharge that operates in vacuum and provides a stream of highly ionised plasma from a solid conducting cathode. The high ion velocities, together with the high ionisation fraction and the quasineutrality of the exhaust stream, make the cathodic arc an attractive plasma source for spacecraft propulsion applications. The specific impulse of the cathodic arc thruster is substantially increased when the emission of neutral species is reduced. Here, we demonstrate a reduction of neutral emission by exploiting sublimation in cathode spots and enhanced ionisation of the plasma in short, high-current pulses. This, combined with the enhanced directionality due to the efficient erosion profiles created by centre-triggering, substantially increases the specific impulse. We present experimentally measured specific impulses and jet power efficiencies for titanium and magnesium fuels. Our Mg fuelled source provides the highest reported specific impulse for a gridless ion thruster and is competitive with all flight rated ion thrusters. We present a model based on cathode sublimation and melting at the cathodic arc spot explaining the outstanding performance of the Mg fuelled source. A further significant advantage of an Mg-fuelled thruster is the abundance of Mg in asteroidal material and in space junk, providing an opportunity for utilising these resources in space.

  20. 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%.

  1. ZrN coatings deposited by high power impulse magnetron sputtering and cathodic arc techniques

    Energy Technology Data Exchange (ETDEWEB)

    Purandare, Yashodhan, E-mail: Y.Purandare@shu.ac.uk; Ehiasarian, Arutiun; Hovsepian, Papken [Nanotechnology Centre for PVD Research, Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom); Santana, Antonio [Ionbond AG Olten, Industriestrasse 211, CH-4600 Olten (Switzerland)

    2014-05-15

    Zirconium nitride (ZrN) coatings were deposited on 1 μm finish high speed steel and 316L stainless steel test coupons. Cathodic Arc (CA) and High Power Impulse Magnetron Sputtering (HIPIMS) + Unbalanced Magnetron Sputtering (UBM) techniques were utilized to deposit coatings. CA plasmas are known to be rich in metal and gas ions of the depositing species as well as macroparticles (droplets) emitted from the arc sports. Combining HIPIMS technique with UBM in the same deposition process facilitated increased ion bombardment on the depositing species during coating growth maintaining high deposition rate. Prior to coating deposition, substrates were pretreated with Zr{sup +} rich plasma, for both arc deposited and HIPIMS deposited coatings, which led to a very high scratch adhesion value (L{sub C2}) of 100 N. Characterization results revealed the overall thickness of the coatings in the range of 2.5 μm with hardness in the range of 30–40 GPa depending on the deposition technique. Cross-sectional transmission electron microscopy and tribological experiments such as dry sliding wear tests and corrosion studies have been utilized to study the effects of ion bombardment on the structure and properties of these coatings. In all the cases, HIPIMS assisted UBM deposited coating fared equal or better than the arc deposited coatings, the reasons being discussed in this paper. Thus H+U coatings provide a good alternative to arc deposited where smooth, dense coatings are required and macrodroplets cannot be tolerated.

  2. Preparation and investigation of diamond-like carbon stripper foils by filtered cathodic vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Qiwen, E-mail: fanqiwen0926@163.com [Department of Nuclear Physics, China Institute of Atomic Energy, P.O. Box 275(62), Beijing 102413 (China); Du, Yinghui; Zhang, Rong; Xu, Guoji [Department of Nuclear Physics, China Institute of Atomic Energy, P.O. Box 275(62), Beijing 102413 (China)

    2013-04-21

    Thin diamond-like carbon (DLC) stripper foils ∼5μg/cm{sup 2} in thickness were produced and evaluated as heavy-ion strippers for the Beijing HI-13 Tandem Accelerator. The DLC layers ∼4μg/cm{sup 2} in thickness were produced by the filtered cathodic vacuum arc technology onto glass slides coated with betaine–saccharose as releasing agent, which were previously covered with evaporated carbon layers ∼1μg/cm{sup 2} in thickness by the controlled ac arc-discharge method. Irradiation lifetimes of the DLC stripper foils were tested using the heavy-ion beams at the terminal of the Beijing HI-13 Tandem Accelerator, and compared with those of the standard carbon stripper foils made by the combined dc and ac arc-discharge method. The measurements indicate that the DLC stripper foils outlast the standard combined dc and ac arc-discharge carbon stripper foils by a factor of at least 13 and 4 for the {sup 197}Au{sup −} (∼9MeV, ∼1μA) and {sup 63}Cu{sup −} (∼9MeV, ∼1μA) ion beams, respectively. The structure and properties of the DLC foils deposited onto silicon substrates by the filtered cathodic vacuum arc technology were also evaluated and analyzed by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The scanning electron microscopy images show that the DLC foils contain hardly droplets through the double 90° filters. The X-ray photoelectron spectrum indicates that sp{sup 3} bonds of the DLC foils exceed 70%. The integral intensity ratio of the D peak to the G peak (I{sub D}/I{sub G}) measured by the Raman spectroscopy is 0.78.

  3. Effects of incidence angle on the structure and properties of cathodic vacuum arc deposition MgO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, D.Y., E-mail: zhudy@gdut.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Experiment Teaching Department, Guangdong University of Technology, Guangzhou 510006 (China); Liu, Y. [College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Zheng, C.X.; Wang, M.D.; Chen, D.H. [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); He, Z.H., E-mail: stshzh@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2012-06-15

    MgO thin films, as the protective layers for plasma display panels (PDP), were prepared by using cathodic vacuum arc deposition technique. The influences of deposition angle between -60 Degree-Sign and 60 Degree-Sign on film structure and properties were investigated. X-ray diffraction (XRD), ellipsometer, thermal field emission environment scanning electron microscopy (SEM) and UV-Visible spectrophotometry were used to study the properties of MgO thin films like crystallization, surface structures, thicknesses and refraction indices. Our results show that the thickness of MgO thin film decreases with the increase of incidence angle. This is confirmed by the transmittance spectra as well. The film deposited at 0 Degree-Sign shows sharper diffraction peaks and smaller FWHMs (full width at half maximum) of both MgO (200) and (220), which means better crystallization quality of the film. The higher packing density is achieved on the 0 Degree-Sign deposited film as well. - Highlights: Black-Right-Pointing-Pointer The thickness of MgO thin film decreases with the increase of incidence angle. Black-Right-Pointing-Pointer Low-angle deposition can increase film deposition rate and improve its crystallinity. Black-Right-Pointing-Pointer Multi-arc setting or rotating substrate is necessary for uniform deposition.

  4. Arc Deflection Length Affected by Transverse Rotating Magnetic Field with Lateral Gas

    Science.gov (United States)

    Shiino, Toru; Ishii, Yoko; Yamamoto, Shinji; Iwao, Toru; High Current Energy Laboratory (HiCEL) Team

    2016-10-01

    Gas metal arc welding using shielding gas is often used in the welding industry. However, the arc deflection affected by lateral gas is problem because of inappropriate heat transfer. Shielding gas is used in order to prevent the instability affected by the arc deflection. However, the shielding gas causes turbulence, then blowhole of weld defect occurs because the arc affected by the instability is contaminated by the air. Thus, the magnetic field is applied to the arc in order to stabilize the arc using low amount of shielding gas. The method of applying the transverse rotating magnetic field (RMF) to the arc is one of the methods to prevent the arc instability. The RMF drives the arc because of electromagnetic force. The driven arc is considered to be prevented to arc deflection of lateral gas because the arc is restrained by the magnetic field because of the driven arc. In addition, it is assume the RMF prevented to the arc deflection of lateral gas from the multiple directions. In this paper, the arc deflection length affected by the RMF with lateral gas was elucidated in order to know the effect of the RMF for arc stabilization. Specifically, the arc deflection length affected by the magnetic frequency and the magnetic flux density is measured by high speed video camera. As a result, the arc deflection length decreases with increasing magnetic frequency, and the arc deflection length increases with increasing the magnetic flux density.

  5. Cell adhesion property of cathodic arc plasma deposited CrN thin film

    Science.gov (United States)

    Kim, Sun Kyu; Pham, Vuong Hung

    2009-09-01

    The interaction between human osteoblast cells and CrN thin film was studied in vitro. CrN thin films were produced by cathodic arc plasma deposition. The surface was characterized by atomic force microscopy. Cell adhesion on the coatings was assessed by MTT assay and visualization. Cell cytoskeleton organization was studied by analyzing microtubule and actin cytoskeleton organization. Focal contact adhesion was monitored by analyzing vinculin density. The study found that the CrN thin film is a potential candidate as a protective coating on implantable devices that require minimal cellular adhesion.

  6. Transparent and conductive indium doped cadmium oxide thin films prepared by pulsed filtered cathodic arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Yuankun, E-mail: yuan.kun.zhu@gmail.com [Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080 (China); Plasma Applications Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Mendelsberg, Rueben J. [Plasma Applications Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Zhu Jiaqi, E-mail: zhujq@hit.edu.cn [Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080 (China); Han Jiecai [Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080 (China); Anders, Andre [Plasma Applications Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer High quality CdO:In films were prepared on glass by pulsed filtered cathodic arc. Black-Right-Pointing-Pointer 230 nm thick films show low resistivity of 7.23 Multiplication-Sign 10{sup -5} {Omega} cm and mobility of 142 cm{sup 2}/Vs. Black-Right-Pointing-Pointer In-doping significantly improves the conductivity and extends the transparent range. Black-Right-Pointing-Pointer Film crystalline quality is maintained with increasing In concentration. Black-Right-Pointing-Pointer The pulsed arc-grown CdO:In show excellent reproducibility of film properties. - Abstract: Indium doped cadmium oxide (CdO:In) films with different In concentrations were prepared on low-cost glass substrates by pulsed filtered cathodic arc deposition (PFCAD). It is shown that polycrystalline CdO:In films with smooth surface and dense structure are obtained. In-doping introduces extra electrons leading to remarkable improvements of electron mobility and conductivity, as well as improvement in the optical transmittance due to the Burstein-Moss effect. CdO:In films on glass substrates with thickness near 230 nm show low resistivity of 7.23 Multiplication-Sign 10{sup -5} {Omega} cm, high electron mobility of 142 cm{sup 2}/Vs, and mean transmittance over 80% from 500 to 1250 nm (including the glass substrate). These high quality pulsed arc-grown CdO:In films are potentially suitable for high efficiency multi-junction solar cells that harvest a broad range of the solar spectrum.

  7. Experimental study and modeling of the deuterium releasing quantity in a pulsed vacuum arc discharge with a metal deuteride cathode

    Science.gov (United States)

    Liu, Fei-Xiang; Long, Ji-Dong; Zheng, Le; Dong, Pan; Li, Chen; Chen, Wei

    2017-04-01

    The pulsed vacuum arc discharge using a metal deuteride cathode is widely applied as a deuterium ion source, where the upper limit of the deuterium ion yield is largely determined by the deuterium releasing quantity (DRQ) from the cathode. This work aims to measure the DRQ at various discharge conditions, and meanwhile develop a simple thermoelectric model to evaluate the deuterium liberation from different sources, such as the crater vicinity during the arc power-on phase and the hot crater in the afterglow. The calculated DRQ are in accordance with the experimental results obtained by measuring the D2 pressure evolution in the early afterglow using a quadrupole mass spectrometer. Furthermore, the model reveals that at low arc current (<10 A), the DRQ orginates dominantly from the crater vicinity, leading to a low conversion efficiency of the released deuterium to ions and a high D:Ti elemental ratio in the released cathode vapor.

  8. Bioactivity and cytocompatibility of zirconia (ZrO(2)) films fabricated by cathodic arc deposition.

    Science.gov (United States)

    Liu, Xuanyong; Huang, Anping; Ding, Chuanxian; Chu, Paul K

    2006-07-01

    Zirconium oxide thin films were fabricated on silicon wafers using a filtered cathodic arc system in concert with oxygen plasma. The structure and phase composition of the zirconium oxide thin films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), and transmission electron microscopy (TEM). The bioactivity was assessed by investigating the formation of apatite on the film surface after soaking in simulated body fluids. Bone marrow mesenchymal stem cells (BMMSC) were used to further evaluate the cytocompatibility of the materials. The results indicate that the films are composed of stoichiometric ZrO(2) and the composition is quite uniform throughout the thickness. Bone-like apatite can be formed on the surface of the ZrO(2) thin film in our SBF immersion experiments, suggesting that the surface is bioactive. The outermost layer of the ZrO(2) thin film comprises nano-sized particles that can be identified by AFM images taken on the thin film surface and TEM micrographs obtained from the interface between the ZrO(2) thin film and apatite layer. The nanostructured surface is believed to be the key factor that apatite is induced to precipitate on the surface. Bone marrow mesenchymal stem cells are observed to grow and proliferate in good states on the film surface. Our results show that ZrO(2) thin films fabricated by cathodic arc deposition exhibit favorable bioactivity and cytocompatibility.

  9. Thick CrN/NbN multilayer coating deposited by cathodic arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Juliano Avelar; Tschiptschin, Andre Paulo; Souza, Roberto Martins, E-mail: antschip@usp.br [Universidade de Sao Paulo (USP), SP (Brazil); Lima, Nelson Batista de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-01-15

    The production of tribological nanoscale multilayer CrN/NbN coatings up to 6 μm thick by Sputtering/HIPIMS has been reported in literature. However, high demanding applications, such as internal combustion engine parts, need thicker coatings (>30 μm). The production of such parts by sputtering would be economically restrictive due to low deposition rates. In this work, nanoscale multilayer CrN/NbN coatings were produced in a high-deposition rate, industrial-size, Cathodic Arc Physical Vapor Deposition (ARC-PVD) chamber, containing three cathodes in alternate positions (Cr/ Nb/Cr). Four 30 μm thick NbN/CrN multilayer coatings with different periodicities (20, 10, 7.5 and 4 nm) were produced. The coatings were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The multilayer coating system was composed of alternate cubic rock salt CrN and NbN layers, coherently strained due to lattice mismatch. The film grew with columnar morphology through the entire stratified structure. The periodicities adopted were maintained throughout the entire coating. The 20 nm periodicity coating showed separate NbN and CrN peaks in the XRD patterns, while for the lower periodicity (≤10nm) coatings, just one intermediate lattice (d-spacing) was detected. An almost linear increase of hardness with decreasing bilayer period indicates that interfacial effects can dominate the hardening mechanisms. (author)

  10. Influence of thermal heating on diamond-like carbon film properties prepared by filtered cathodic arc

    Energy Technology Data Exchange (ETDEWEB)

    Khamnualthong, N., E-mail: nattapornkh@gmail.com [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok, 10140 (Thailand); Western Digital Thailand Co. Ltd, Ayutthaya, 13160 (Thailand); Siangchaew, K. [Western Digital Thailand Co. Ltd, Ayutthaya, 13160 (Thailand); Limsuwan, P. [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok, 10140 (Thailand); Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400 (Thailand)

    2013-10-01

    Tetrahedral amorphous diamond-like carbon (ta-DLC) films were deposited on magnetic recording heads using the filtered cathodic arc method. The deposited film thickness was on the order of several nanometers. The DLC films were then annealed to 100 °C–300 °C for 30 and 60 min, and the structure of the ta-DLC films was investigated using Raman spectroscopy, where the gross changes were observed in the Raman D and G peaks. Detailed interpretation concluded that there was sp{sup 2} clustering as a function of temperature, and there was no sp{sup 3}-to-sp{sup 2} conversion after heating up to 300 °C. Furthermore, X-ray photoelectron spectroscopy suggested that oxidation of both the ta-DLC film and the adhesion layer occurs at 300 °C. Additionally, more film wear was observed with heating as measured by a nanoindenter. - Highlights: • Tetrahedral-amorphous diamond-like carbon (ta-DLC) by filtered cathodic arc • ta-DLC used in magnetic recording head as head overcoat • ta-DLC thickness range of less than 2 nm • ta-DLC property dependence on heating • Temperature effect range of up to 300 °C.

  11. Structure of MoCN films deposited by cathodic arc evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Gilewicz, A., E-mail: adam.gilewicz@tu.koszalin.pl [Koszalin University of Technology, Faculty of Technology and Education, Sniadeckich 2, 75-453 Koszalin (Poland); Jedrzejewski, R.; Kochmanska, A.E. [West Pomeranian University of Technology Szczecin, Faculty of Mechanical Engineering and Mechatronics, 19 Piastów Ave., 70-313 Szczecin (Poland); Warcholinski, B. [Koszalin University of Technology, Faculty of Technology and Education, Sniadeckich 2, 75-453 Koszalin (Poland)

    2015-02-27

    Molybdenum carbonitride (MoCN) coatings were deposited onto HS6-5-2 steel substrate using pure Mo targets in mixed acetylene and nitrogen atmosphere by cathodic arc evaporation. The structural properties of MoCN coatings with different carbon contents (as an effect of the C{sub 2}H{sub 2} flow rate) were investigated systematically. Phase and chemical composition evolution of the coatings were characterized both by the glancing angle of X-ray diffraction (XRD) and wavelength dispersive spectrometry, respectively. These analyses have been supplemented by estimates of grain sizes and stress in the coatings. The XRD results show that the increase in acetylene flow rate causes the formation of molybdenum carbide (MoC) hexagonal phase in the coatings, a reduction of grain size and an increase in internal stress. - Highlights: • MoN and MoCN coatings were deposited by cathodic arc evaporation in nitrogen atmosphere. • MoCN coatings were formed using different acetylene flow rates. • Phase composition evolution was observed. • Crystallite size and stress were calculated.

  12. Low pressure arc discharges with hollow cathodes and their using in plasma generators and charged particle sources

    CERN Document Server

    Vintizenko, L G; Koval, N N; Tolkachev, V S; Lopatin, I V; Shchanin, P M

    2001-01-01

    Paper presents the results of investigation into arc discharges with a hollow cathode generating 10 sup 1 sup 0 -10 sup 1 sup 2 concentration gas-discharge plasma in essential (approx 1 m sup 3) volumes at low (10 sup - sup 2 -1 Pa) pressures and up to 200 A discharge currents. One studied design of discharge systems with heated and cold cathodes their peculiar features, presented the parameters of plasma generators and of charged particle sources based on arc discharges and discussed, as well, the problems of more rational application of those systems in the processes for surface modification of solids

  13. Effect of Surface Treatment by Cathode Spot of Low Pressure Arc on Bonding Strength of Spraying Film by APPS

    Science.gov (United States)

    Hara, Masayuki; Ogura, Hirosi; Maezono, Satoru; Kubo, Yuya; Iwao, Toru; Tobe, Shogo; Inaba, Tsuginori

    Cathode spots of a low pressure arc can remove the oxide layer and evaporate impurities on the metal surface. The removal of the oxide layer by using the cathode spots in the low pressure is expected to solve the serious problems of the chemical and mechanical cleaning methods. The phenomena of the cathode spots in the low pressure for pre-treatment of Atmospheric Pressure Plasma Spray (APPS) have been investigated. In this paper, the surface shape of oxide work pieces was treated by using the cathode spots in the low pressure arc then compared with the grit-blasted surface. As a result, it is possible to improve the bonding strength of the spray deposit by making arithmetical mean height Ra large and average length of outline curve element Rsm small. Cathode spots of a low-pressure arc can be used for pre-treatment of APPS as the alternative technology of the blast. it is possible to obtain Ra larger an Rsm smaller than the blast only by cathode spots after the blast. But the treatment must be restricted not to destroy projection ones which were formed with melting.

  14. Growth of single and bilayer graphene by filtered cathodic vacuum arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Kesarwani, A. K.; Panwar, O. S., E-mail: ospanwar@mail.nplindia.ernet.in; Bisht, Atul [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012, India and Academy of Scientific and Innovative Research (AcSIR), CSIR Campus, New Delhi 110012 (India); Dhakate, S. R. [Physics and Engineering of Carbon Materials, Division of Materials Physics and Engineering, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012, India and Academy of Scientific and Innovative Research (AcSIR), CSIR Campus, New Delhi 110012 (India); Rakshit, R. K. [Quantum Phenomena and Applications Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012, India and Academy of Scientific and Innovative Research (AcSIR), CSIR Campus, New Delhi 110012 (India); Singh, V. N. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012, India and Academy of Scientific and Innovative Research (AcSIR), CSIR Campus, New Delhi 110012 (India); Kumar, Ashish [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2016-03-15

    The authors present a viable process to grow the high quality graphene films with control over number of layers by the filtered cathodic vacuum arc (FCVA) technique. In the FCVA process, the different carbon concentrations can be controlled by precisely tuning the arc time (1–4 s). The arc generated carbon was deposited on the nickel catalyst at 800 °C, annealed for 10 min, and cooled down to room temperature in the presence of hydrogen gas, resulting in the graphene films with control over number of layers. Prior to arcing, hydrogen etching of nickel was carried out to clean the surface of the substrate. A growth model to prepare the high quality graphene has also been proposed. The as-grown graphene films were transferred to different substrates and are characterized by Raman spectroscopy, optical microscopy, high resolution transmission electron microscopy, and atomic force microscopy to determine the number of layers present in these films. Raman spectra of the prepared graphene films exhibit change in the G peak position from 1582.4 to 1578.1 cm{sup −1}, two-dimensional (2D) peak shifts from 2688.5 to 2703.8 cm{sup −1}, the value of I{sub 2D}/I{sub G} increased from 0.38 to 3.82, and the full width at half maxima of 2D peak changed from 41 to 70 cm{sup −1}, for different layers of graphene films. The high resolution transmission electron microscopy image revealed that the graphene films prepared for 1 and 2 s arc times have single and bi- or trilayered structures, respectively.

  15. Vacuum arc with a distributed cathode spot as a plasma source for plasma separation of spent nuclear fuel and radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Amirov, R. Kh., E-mail: ravus46@yandex.ru; Vorona, N. A.; Gavrikov, A. V.; Lizyakin, G. D.; Polishchuk, V. P.; Samoilov, I. S.; Smirnov, V. P.; Usmanov, R. A.; Yartsev, I. M. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2015-10-15

    Results from experimental studies of a vacuum arc with a distributed cathode spot on the heated cathode are presented. Such an arc can be used as a plasma source for plasma separation of spent nuclear fuel and radioactive waste. The experiments were performed with a gadolinium cathode, the properties of which are similar to those of an uranium arc cathode. The heat flux from the plasma to the cathode (and its volt equivalent) at discharge voltages of 4-15 V and discharge currents of 44-81 A, the radial distribution of the emission intensity of gadolinium atoms and singly charged ions in the arc channel at a voltage of 4.3 V, and the plasma electron temperature behind the anode were measured. The average charge of plasma ions at arc voltages of 3.5-8 V and a discharge current of 52 A and the average rate of gadolinium evaporation in the discharge were also determined.

  16. Filtered pulsed cathodic arc deposition of fullerene-like carbon and carbon nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Mark D., E-mail: martu@ifm.liu.se; Broitman, Esteban; Näslund, Lars-Åke; Hultman, Lars; Rosen, Johanna [Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Czigány, Zsolt [Institute for Technical Physics and Materials Science, RCNS, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary)

    2014-04-14

    Carbon and carbon nitride films (CN{sub x}, 0 ≤ x ≤ 0.26) were deposited by filtered pulsed cathodic arc and were investigated using transmission electron microscopy and X-ray photoelectron spectroscopy. A “fullerene-like” (FL) structure of ordered graphitic planes, similar to that of magnetron sputtered FL-CN{sub x} films, was observed in films deposited at 175 °C and above, with N{sub 2} pressures of 0 and 0.5 mTorr. Higher substrate temperatures and significant nitrogen incorporation are required to produce similar FL structure by sputtering, which may, at least in part, be explained by the high ion charge states and ion energies characteristic of arc deposition. A gradual transition from majority sp{sup 3}-hybridized films to sp{sup 2} films was observed with increasing substrate temperature. High elastic recovery, an attractive characteristic mechanical property of FL-CN{sub x} films, is evident in arc-deposited films both with and without nitrogen content, and both with and without FL structure.

  17. Filtered pulsed cathodic arc deposition of fullerene-like carbon and carbon nitride films

    Science.gov (United States)

    Tucker, Mark D.; Czigány, Zsolt; Broitman, Esteban; Näslund, Lars-Åke; Hultman, Lars; Rosen, Johanna

    2014-04-01

    Carbon and carbon nitride films (CNx, 0 ≤ x ≤ 0.26) were deposited by filtered pulsed cathodic arc and were investigated using transmission electron microscopy and X-ray photoelectron spectroscopy. A "fullerene-like" (FL) structure of ordered graphitic planes, similar to that of magnetron sputtered FL-CNx films, was observed in films deposited at 175 °C and above, with N2 pressures of 0 and 0.5 mTorr. Higher substrate temperatures and significant nitrogen incorporation are required to produce similar FL structure by sputtering, which may, at least in part, be explained by the high ion charge states and ion energies characteristic of arc deposition. A gradual transition from majority sp3-hybridized films to sp2 films was observed with increasing substrate temperature. High elastic recovery, an attractive characteristic mechanical property of FL-CNx films, is evident in arc-deposited films both with and without nitrogen content, and both with and without FL structure.

  18. Antibacterial efficacy of advanced silver-amorphous carbon coatings deposited using the pulsed dual cathodic arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Endrino, J L; Anders, A; Albella, J M; Horton, J A; Horton, T H; Ayyalasomayajula, P R; Allen, M, E-mail: jlendrino@icmm.csic.es

    2010-11-01

    Amorphous carbon (a-C) also referred as diamond-like carbon (DLC) films are well known to be a biocompatible material with good chemical in ertness; this makes it a strong candidate to be used as a matrix that embeds metallic elements with an antimicrobial effect. We have deposited as et of a-C:Ag films using a dual-cathode pulsed filtered cathodic arc source, the arc pulse frequency of the silver and graphite cathodes was controlled in order to obtain samples with various silver contents. In this study, we show the deposition of silver and carbon ions using this technique and analyze the advantages of incorporating silver into a-C by studying the antimicrobial properties against staphylococcus of samples deposited on Ti{sub 6}Al{sub 4}V coupons and evaluated using 24-well tissue culture plates.

  19. The mechanism of liquid metal jet formation in the cathode spot of vacuum arc discharge

    Science.gov (United States)

    Gashkov, M. A.; Zubarev, N. M.; Mesyats, G. A.; Uimanov, I. V.

    2016-08-01

    We have theoretically studied the dynamics of molten metal during crater formation in the cathode spot of vacuum arc discharge. At the initial stage, a liquid-metal ridge is formed around the crater. This process has been numerically simulated in the framework of the two-dimensional axisymmetric heat and mass transfer problem in the approximation of viscous incompressible liquid. At a more developed stage, the motion of liquid metal loses axial symmetry, which corresponds to a tendency toward jet formation. The development of azimuthal instabilities of the ridge is analyzed in terms of dispersion relations for surface waves. It is shown that maximum increments correspond to instability of the Rayleigh-Plateau type. Estimations of the time of formation of liquid metal jets and their probable number are obtained.

  20. Synthesis and characterization of zirconium nitride coatings by cathodic arc sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Sarwar, M.N.; Awan, M.S.; Akbar, S. [ISIT, Islamabad (Pakistan)

    2014-11-15

    Polycrystalline zirconium nitride films (560 nm) were deposited on stainless steel (SS-316) substrates using the multi-target cathodic arc sputtering technique. Deposition was carried out under N{sub 2} reactive atmosphere (4 x 10{sup -3} mbar) at two different temperatures, 150 and 200 C. X-ray diffraction studies show that reflections from planes changed from (111) to (200) for deposition temperatures of 150 C and 200 C, respectively. Films deposited at 150 C and 200 C bear a critical load of 6.4 N and 6.8 N respectively, showing better adherence at higher temperature. This may be the result of film-substrate diffusion at the interface.

  1. Device quality ZnO grown using a Filtered Cathodic Vacuum Arc

    Energy Technology Data Exchange (ETDEWEB)

    Elzwawi, Salim, E-mail: salim.elzwawi@pg.canterbury.ac.nz [Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, Canterbury (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Kim, Hyung Suk, E-mail: david.kim@pg.canterbury.ac.nz [Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, Canterbury (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Heinhold, Robert, E-mail: robert.heinhold@pg.canterbury.ac.nz [Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, Canterbury (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Lynam, Max, E-mail: mfl38@uclive.ac.nz [Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, Canterbury (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Turner, Gary, E-mail: gary.turner@canterbury.ac.nz [Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, Canterbury (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Partridge, Jim G., E-mail: jim.partridge@canterbury.ac.nz [Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, Canterbury (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); McCulloch, Dougal G., E-mail: dougal.mcculloch@rmit.edu.au [Applied Sciences, RMIT University, GPO Box 2476 V, Melbourne, VIC 3001 (Australia)

    2012-08-01

    In this paper we report on the structural, electrical and optical characteristics of unintentionally doped ZnO films grown on a-plane sapphire substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. The resulting films showed considerable promise for device applications with properties including high transparency, moderate intrinsic carrier concentrations (10{sup 17}-10{sup 19} cm{sup -3}), electron mobilities up to 30 cm{sup 2}/Vs, low surface roughness (typically <2% of film thickness) and well-structured photoluminescence. Post-annealing in oxygen at temperatures up to 800 Degree-Sign C produced significant improvements in the properties of these films. Silver oxide Schottky diodes fabricated on FCVA ZnO showed ideality factors as low as 1.20 and good sensitivity to ultraviolet light.

  2. CrAlN coatings deposited by cathodic arc evaporation at different substrate bias

    Energy Technology Data Exchange (ETDEWEB)

    Romero, J. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya (Spain); Gomez, M.A. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya (Spain); Grupo de Corrosion y Proteccion, Universidad de Antioquia, A.A. 1226 Medellin (Colombia); Esteve, J. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya (Spain); Montala, F. [Tratamientos Termicos Carreras, TTC S.A., C/Doctor Almera 85, E-08205 Sabadell, Catalunya (Spain); Carreras, L. [Tratamientos Termicos Carreras, TTC S.A., C/Doctor Almera 85, E-08205 Sabadell, Catalunya (Spain); Grifol, M. [Tratamientos Termicos Carreras, TTC S.A., C/Doctor Almera 85, E-08205 Sabadell, Catalunya (Spain); Lousa, A. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya (Spain)]. E-mail: alousa@ub.edu

    2006-09-25

    CrAlN is a good candidate as an alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on hardened steel substrates by cathodic arc evaporation (CAE) from chromium-aluminum targets in a reactive nitrogen atmosphere at negative substrate bias between - 50 and - 400 V. The negative substrate bias has important effects on the deposition growth rate and crystalline structure. All our coatings presented hardness higher than conventional CrN coatings. The friction coefficient against alumina and tungsten carbide balls was around 0.6. The sliding wear coefficient of the CrAlN coatings was very low while an important wear was observed in the balls before a measurable wear were produced in the coatings. This effect was more pronounced as the negative substrate bias was increased.

  3. Review of cathodic arc deposition technology at the start of the new millennium

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, D M; Anders, A

    2000-02-24

    The vacuum cathodic arc has been known to provide a means of producing coatings since the second half of the 19th century. This makes it one of the oldest known means for making coatings in a vacuum. In the last century it has been recognized that the copious quantities of ions produced by the process offers certain advantages in terms of coating properties. Specifically, ions can be steered and/or accelerated toward the parts to be coated. This, in turn, can provide enhanced adhesion, film density, and composition stoichiometry in the case of compound coatings. The ions generated by the cathodic arc have high ''natural'' kinetic energy values in the range 20-200 eV, leading to enhanced surface mobility during the deposition process and even ion subplantation. In many cases, dense coatings are achieved even when non-normal arrival angles are involved. The ion energy can further manipulated by the plasma immersion biasing technique. The issue of macroparticle contamination has been addressed by a variety of novel plasma filters. In spite of all of these advantages, this deposition technique has not been widely adopted in the western nations for commercial coating except in the case of enhancing the performance of cutting tools. The purpose of the this review is to explore reasons for this lack of general use of the technology and to point out some encouraging recent developments which may lead to its accelerated adoption for a much wider variety of applications in the near future.

  4. Cathodic micro-arc electrodeposition of yttrium stabilized zirconia (YSZ) coatings on FeCrAl alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The formation of ceramic coatings on metal substrate by cathodic electrolytic deposition (CELD) has received more attention in recent years. But only thin films can be prepared via CELD. Yttrium stabilized zirconia (YSZ) ceramic coatings were deposited on FeCrAl alloy by a novel technique--cathodic micro-arc electrodeposition (CMED). The result shows that, when a high pulse electric field is applied to the cathode which was pre-deposited with a thin YSZ film, dielectric breakdown occurs and micro-arc discharges appear. Coatings with reasonably thickness of ~300μm and crystalline structure can be deposited on the cathode by utilizing the energy of the micro-arc. The thickness of the as-deposited coating is dominated by the voltage and the frequency. Y2O3 is co-deposited with ZrO2 when Y(NO3)3 was added to the electrolyte, which stabilize t-phase, t′- phase and c-phase of ZrO2 at room temperature. The amount of the m-ZrO2 in the coating is diminished by increasing the concentration of Y(NO3)3 in the electrolyte. This report describes the processing of CMED and studies the microstructure of the deposited YSZ coatings.

  5. Translational, rotational and vibrational temperatures of a gliding arc discharge at atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2014-01-01

    Gliding arc discharges have generally been used to generate non-equilibrium plasma at atmospheric pressure. Temperature distributions of a gliding arc are of great interest both for fundamental plasma research and for practical applications. In the presented studies, translational, rotational...... and vibrational temperatures of a gliding arc generated at atmospheric pressure air are investigated. Translational temperatures (about 1100 K) were measured by laser-induced Rayleigh scattering, and two-dimensional temperature imaging was performed. Rotational and vibrational temperatures (about 3600 K and 6700...

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

    Science.gov (United States)

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

    2014-02-01

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

  7. Charge-state and element-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    CERN Document Server

    Franz, Robert; Anders, André

    2014-01-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al$^{+}$ regardless of the background gas species, whereas Cr$^{2+}$ ions were dominating in Ar and N$_2$ and Cr$^{+}$ in O$_2$ atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were mainly thermalised. In addition to the positively charged metal and gas ions, negatively charged oxygen an...

  8. Inorganic-solid-state electrolyte layer deposited by cathodic arc plasma for rapidly switching electrochromic device

    Science.gov (United States)

    Chen, Po-Wen; Chang, Chen-Te; Wu, Jin-Yu; Jan, Der-Jun; Li, Yu-Chen; Hsieh, Cheng-Chang; Tsai, Wen-Fa

    2017-08-01

    This work focuses on fabricating a solid electrolyte Ta2O5 thin film deposited by cathodic arc plasm (CAP) deposition through three different ratio of oxygen and argon. In our experiments, refractive index of Ta2O5 films are taken as 2.25, 1.96, 1.9 with various O2/Ar= 1.5, O2/Ar= 2, O2/Ar= 2.4, respectively. Our results show that the refractive index mostly decreased as we increase the oxygen flow rate, in which the minimum is found at 240 sccm. It provides good conduction pathways for ions through smaller thin-film's refractive index that exhibits more porosity voids. This property enhances ion's mobility for electrochromic device causing rapid coloring/bleaching phenomenon. Ta2O5 thin film is suitable as a solid electrolyte layer in center of electrochromic device (ECD) using CAP deposition. As a result, rapid response times were observed in fabricated device with an area of 5 cm×5 cm, exhibiting transmittance optical modulation ΔT = 61.5% (@550 nm) with the bleaching time τ = 8 s and transmittance optical modulation ΔT = 50% (@550 nm) with the coloring time τ = 10 s.

  9. The multilayered structure of ultrathin amorphous carbon films synthesized by filtered cathodic vacuum arc deposition

    KAUST Repository

    Wang, Na

    2013-08-01

    The structure of ultrathin amorphous carbon (a-C) films synthesized by filtered cathodic vacuum arc (FCVA) deposition was investigated by high-resolution transmission electron microscopy, electron energy loss spectroscopy, and x-ray photoelectron spectroscopy. Results of the plasmon excitation energy shift and through-thickness elemental concentration show a multilayered a-C film structure comprising an interface layer consisting of C, Si, and, possibly, SiC, a buffer layer with continuously increasing sp 3 fraction, a relatively thicker layer (bulk film) of constant sp 3 content, and an ultrathin surface layer rich in sp 2 hybridization. A detailed study of the C K-edge spectrum indicates that the buffer layer between the interface layer and the bulk film is due to the partial backscattering of C+ ions interacting with the heavy atoms of the silicon substrate. The results of this study provide insight into the minimum thickness of a-C films deposited by FCVA under optimum substrate bias conditions. Copyright © 2013 Materials Research Society.

  10. Energetic deposition of carbon in a cathodic vacuum arc with a biased mesh

    Science.gov (United States)

    Moafi, A.; Lau, D. W. M.; Sadek, A. Z.; Partridge, J. G.; McKenzie, D. R.; McCulloch, D. G.

    2011-04-01

    Carbon films were deposited in a filtered cathodic vacuum arc with a bias potential applied to a conducting mesh mounted in the plasma stream between the source and the substrate. We determined the stress and microstructural properties of the resulting carbon films and compared the results with those obtained using direct substrate bias with no mesh. Since the relationship between deposition energy and the stress, sp2 fraction and density of carbon are well known, measuring these film properties enabled us to investigate the effect of the mesh on the energy and composition of the depositing flux. When a mesh was used, the film stress showed a monotonic decrease for negative mesh bias voltages greater than 400V, even though the floating potential of the substrate did not vary. We explain this result by the neutralization of some ions when they are near to or passing through the negatively biased mesh. The microstructure of the films showed a change from amorphous to glassy carbonlike with increasing bias. Potential applications for this method include the deposition of carbon films with controlled stress on low conductivity substrates to form rectifying or ohmic contacts.

  11. Raman Spectroscopy of DLC/a-Si Bilayer Film Prepared by Pulsed Filtered Cathodic Arc

    Directory of Open Access Journals (Sweden)

    C. Srisang

    2012-01-01

    Full Text Available DLC/a-Si bilayer film was deposited on germanium substrate. The a-Si layer, a seed layer, was firstly deposited on the substrate using DC magnetron sputtering and DLC layer was then deposited on the a-Si layer using pulsed filtered cathodic arc method. The bilayer films were deposited with different DLC/a-Si thickness ratios, including 2/2, 2/6, 4/4, 6/2, and 9/6. The effect of DLC/a-Si thickness ratios on the sp3 content of DLC was analyzed by Raman spectroscopy. The results show that a-Si layer has no effect on the structure of DLC film. Furthermore, the upper shift in G wavenumber and the decrease in ID/IG inform that sp3 content of the film is directly proportional to DLC thickness. The plot modified from the three-stage model informed that the structural characteristics of DLC/a-Si bilayer films are located close to the tetrahedral amorphous carbon. This information may be important for analyzing and developing bilayer protective films for future hard disk drive.

  12. Langmuir probe study of a titanium pulsed filtered cathodic arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Andruczyk, D [School of Physics, University of Sydney, NSW 2006 (Australia); Tarrant, R N [School of Physics, University of Sydney, NSW 2006 (Australia); James, B W [School of Physics, University of Sydney, NSW 2006 (Australia); Bilek, M M M [School of Physics, University of Sydney, NSW 2006 (Australia); Warr, G B [School of Physics, University of Sydney, NSW 2006 (Australia)

    2006-08-01

    A Langmuir probe has been used to make measurements of plasma parameters as a function of time at the substrate position in a magnetically-filtered pulsed cathodic arc discharge. Electron density, n{sub e}, and effective electron temperature, T{sub eff}, were calculated as a function of time from the I-V curves. The Druyvesteyn method was used to determine the electron energy distribution. Ion density was calculated using the assumption of plasma quasi-neutrality and an average ion charge state. Results show that over the plateau region (350-600 {mu}s) of the pulse, the electron energy distribution is Maxwellian with T{sub eff} = T{sub e} = (10 {+-} 1) eV. During the rise and fall times of the pulse, the electron energy distribution is non-Maxwellian with an effective temperature of up to 15 to 20 eV during the rise time and {approx}7 eV during the fall time. The electron density during the plateau is n{sub e} = (3.0-6.0 {+-} 0.5) x 10{sup 17} m{sup -3}.

  13. Microstructure Changes of Ti-Al-C Films Deposited by Filtered Cathodic Vacuum Arc

    Directory of Open Access Journals (Sweden)

    Xianjuan Pang

    2014-01-01

    Full Text Available Nanocomposite Ti-Al-C films were deposited by filtered cathodic vacuum arc (FCVA at different CH4 flows. The deposited films were characterized in terms of elemental and phase compositions, chemical bonds, and texture as a function of CH4 flow rate by XRD, XPS, HRTEM, Raman spectroscopy, and IR spectroscopy. The results show that the TiC grain size decreases from 4.2 to 2.9 nm as the CH4 flow rate increases from 30 to 80 sccm. The analysis of XPS, HRTEM, and Raman spectroscopy shows that the microstructure of deposited films turns from a TiC dominant TiC-C film to a carbon network dominant TiAl-doped a-C film structure as the CH4 flow increases from 30 sccm to 80 sccm. IR spectroscopy shows that most of the hydrogen atoms in the deposited films are bonded to the sp3-hybridized C atoms. All the composition and microstructure change can be explained by considering the plasma conditions and the effect of CH4 flow.

  14. Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium.

    Science.gov (United States)

    Zhu, Wei; Teel, George; O'Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium's osseointegration involves inducing bio-mimetic nanotopography to enhance cell-implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications.

  15. Time-varying Entry Heating Profile Replication with a Rotating Arc Jet Test Article

    Science.gov (United States)

    Grinstead, Jay Henderson; Venkatapathy, Ethiraj; Noyes, Eric A.; Mach, Jeffrey J.; Empey, Daniel M.; White, Todd R.

    2014-01-01

    A new approach for arc jet testing of thermal protection materials at conditions approximating the time-varying conditions of atmospheric entry was developed and demonstrated. The approach relies upon the spatial variation of heat flux and pressure over a cylindrical test model. By slowly rotating a cylindrical arc jet test model during exposure to an arc jet stream, each point on the test model will experience constantly changing applied heat flux. The predicted temporal profile of heat flux at a point on a vehicle can be replicated by rotating the cylinder at a prescribed speed and direction. An electromechanical test model mechanism was designed, built, and operated during an arc jet test to demonstrate the technique.

  16. Rotating arc horizontal narrow gap welding of high strength quenched and tempered steel

    Institute of Scientific and Technical Information of China (English)

    Guo Ning; Yang Chunli; Han Yanfei; Jia Chuanbao; Du Yongpeng; Zhang Linlin

    2010-01-01

    Rotating arc horizontal narrow gap welding of quenched & tempered ( Q&T) steel was innovatively performed for solving the bottleneck that the molten pool sagged due to the gravity. The shapely multilayer single pass horizontal joint could be obtained by using the rotating arc welding process. The cold crack was not observed in the joint without controlling the heat input and selecting the consumables intentionally. Mkrostructure of the joint could be divided into three zones:base metal zone ( BMZ) , heat-affected zone (HAZ) and weld zone ( WZ). Because of the characteristic of the rotating arc horizontal welding process, the defects in the joints were slag inclusion formed at the inUrlayer of lower side wall. The tensile strength and hardness of HAZ and WZ were larger than those of BMZ. The impact toughness in WZ, HAZ and BM at 0℃ is equal to 115, 212 and 236 J, respectively.

  17. Properties of TiAlCrN coatings prepared by vacuum cathodic arc ion plating

    Institute of Scientific and Technical Information of China (English)

    RU Qiang; HU Shejun; HUANG Nacan; ZHAO Lingzhi; QIU Xiuli; HU Xianqi

    2008-01-01

    TiAlCrN coatings were deposited by means of vacuum cathodic arc ion plating technique on TC11 (Ti-6.5 Al-3.5 Mo-1.5 Zr-0.3Si) titanium alloy substrates. The composition, phase structure, mechanical performance, and oxidation-resistance of the nitride coatings were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), auger electron spectroscopy (AES), and X-ray photoelectron microscopy (XPS). A new process for preparing protective coatings of the titanium alloy is successfully acquired. The experimental results indicate that the added element chromium in the TiAlN coatings make a contribution to form the (220) preferred direction. The phases of the coatings are composed of (Ti, Al)N and (Ti, Cr)N. After 700℃ and 800℃ oxidation, AES analysis shows that the diffusion distribution of the TiAlCrN coatings emerges a step shape. From the outside to the inner, the concentrations of O, Al, and Cr reduce, but those of Ti and N increase. The Al-rich oxide is formed on the surface of the coatings, and the mixed structure of Ti-rich and Cr-rich oxides is formed in the internal layer. The oxidation resistance of the TiAlCrN coatings is excellent at the range of 700 to 800℃. Adhesion wear is the dominant mechanical characteristic for the titanium alloy at room temperature, and the protective coatings with high hardness can improve the mechanical properties of the titanium alloy. The wear resistance of the TC11 alloy is considerably improved by the TiAlCrN coatings.

  18. Magnesium substituted hydroxyapatite formation on (Ti,Mg)N coatings produced by cathodic arc PVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Onder, Sakip [Department of Metallurgical and Materials Engineering, Istanbul Technical University, 34469, Maslak, Istanbul (Turkey); Molecular Biology-Genetics and Biotechnology Program (MOBGAM), Istanbul Technical University, 34469, Maslak, Istanbul (Turkey); Kok, Fatma Nese [Molecular Biology-Genetics and Biotechnology Program (MOBGAM), Istanbul Technical University, 34469, Maslak, Istanbul (Turkey); Department of Molecular Biology and Genetics, Istanbul Technical University, 34469, Maslak, Istanbul (Turkey); Kazmanli, Kursat, E-mail: kursat@itu.edu.tr [Department of Metallurgical and Materials Engineering, Istanbul Technical University, 34469, Maslak, Istanbul (Turkey); Urgen, Mustafa [Department of Metallurgical and Materials Engineering, Istanbul Technical University, 34469, Maslak, Istanbul (Turkey)

    2013-10-15

    In this study, formation of magnesium substituted hydroxyapatite (Ca{sub 10−x}Mg{sub x}(PO{sub 4}){sub 6}(OH){sub 2}) on (Ti,Mg)N and TiN coating surfaces were investigated. The (Ti{sub 1−x},Mg{sub x})N (x = 0.064) coatings were deposited on titanium substrates by using cathodic arc physical vapor deposition technique. TiN coated grade 2 titanium substrates were used as reference to understand the role of magnesium on hydroxyapatite (HA) formation. The HA formation experiments was carried out in simulated body fluids (SBF) with three different concentrations (1X SBF, 5X SBF and 5X SBF without magnesium ions) at 37 °C. The coatings and hydroxyapatite films formed were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and FTIR Spectroscopy techniques. The energy dispersive X-ray spectroscopy (EDS) analyses and XRD investigations of the coatings indicated that magnesium was incorporated in the TiN structure rather than forming a separate phase. The comparison between the TiN and (Ti, Mg)N coatings showed that the presence of magnesium in TiN structure facilitated magnesium substituted HA formation on the surface. The (Ti,Mg)N coatings can potentially be used to accelerate the HA formation in vivo conditions without any prior hydroxyapatite coating procedure. - Highlights: • Mg incorporated in (Ti,Mg)N coating structure and did not form a separate phase • Mg dissolution in SBF solution facilitated Mg-substituted hydroxyapatite formation • (Ti,Mg)N acted as Mg-source for Mg-substituted hydroxyapatite formation in SBF.

  19. Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium

    Directory of Open Access Journals (Sweden)

    Zhu W

    2015-12-01

    Full Text Available Wei Zhu,1 George Teel,1 Christopher M O’Brien,1 Taisen Zhuang,1 Michael Keidar,1 Lijie Grace Zhang1–3 1Department of Mechanical and Aerospace Engineering, 2Department of Biomedical Engineering, 3Department of Medicine, The George Washington University, Washington, DC, USA Abstract: Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing biomimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications

  20. Microstructure and mechanical properties of nanocomposite coatings deposited by cathodic arc evaporation

    Directory of Open Access Journals (Sweden)

    K. Lukaszkowicz

    2010-09-01

    Full Text Available Purpose: The main aim of the this research was the investigation of the structure and the mechanical properties of the nanocomposite TiAlSiN, CrAlSiN, AlTiCrN coatings deposited by cathodic arc evaporation method onto hot work tool steel substrate.Design/methodology/approach: The surfaces’ topography and the structure of the PVD coatings were observed on the scanning electron microscopy. Diffraction and thin film structure were tested with the use of the transmission electron microscopy. The microhardness tests were made on the dynamic ultra-microhardness tester. Tests of the coatings’ adhesion to the substrate material were made using the scratch test.Findings: It was found that the structure of the PVD coatings consisted of fine crystallites, while their average size fitted within the range of 11-25 nm, depending on the coating type. The coatings demonstrated columnar structure and dense cross-section morphology as well as good adhesion to the substrate. The critical load LC2 lies within the range of 46-54 N, depending on the coating and substrate type. The coatings demonstrate a high hardness (~40 GPa.Practical implications: In order to evaluate with more detail the possibility of applying these surface layers in tools, further investigations should be concentrated on the determination of the thermal fatigue resistance of the coatings. The very good mechanical properties of the nanocomposite coatings make them suitable in industrial applications.Originality/value: The investigation results will provide useful information to applying the nanocomposite coatings for the improvement of mechanical properties of the hot work tool steels.

  1. Synthesis and characterization of CrCN–DLC composite coatings by cathodic arc ion-plating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.Y. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Wang, L.L. [Key Laboratory of Artificial Nanomaterials and Nanostructure of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Liu, H.D. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Yan, S.J. [Key Laboratory of Artificial Nanomaterials and Nanostructure of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Chen, Y.M. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Fu, D.J. [Key Laboratory of Artificial Nanomaterials and Nanostructure of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yang, B., E-mail: toyangbing@163.com [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China)

    2013-07-15

    CrCN–DLC composite coatings were deposited onto silicon (1 0 0) and cemented carbides substrates using pure Cr targets under C{sub 2}H{sub 2} ambient by cathodic arc ion plating system. The influence of C{sub 2}H{sub 2} flow rate on the structure and mechanical properties of the coatings was investigated systemically. The coatings structure and bonding state were characterized by XRD, Raman and X-ray photoelectron spectroscopy. The chemical composition was measured by EDS. The mechanical performance and tribological behaviour of the coatings were studied by a hardness tester and ball-on-disc wear tester. The results showed that with increasing C{sub 2}H{sub 2} flow rate from 50 to 100 sccm, the corresponding hardness of coatings increased firstly and then decreased with further addition of C{sub 2}H{sub 2} flow rate. The coatings deposited at lower C{sub 2}H{sub 2} flow rate (less than 200 sccm) exhibited a relatively higher hardness value (more than HV{sub 0.025}2000) and then the hardness decrease with increasing C{sub 2}H{sub 2} flow rate. The friction coefficient also exhibited similar variation trend, when the C{sub 2}H{sub 2} flow rate was higher than 100 sccm, the friction coefficient decreased and then maintained in a relatively lower value from 0.18 to 0.24, which may be attribute to the increasing carbon content and the coating exhibited more diamond-like structure.

  2. Cathodoluminescence of Cr-doped diamond-like carbon film by filtered cathodic vacuum arc plasma

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Meng-Wen; Jao, Jui-Yun [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Lin, Chun-Chun; Hsieh, Wei-Jen; Yang, Yu-Hsiang [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 300, Taiwan (China); Cheng, Li-Shin; Shieu, F.S. [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Shih, Han C., E-mail: hcshih@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 300, Taiwan (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, 55 Hwa Kang Road, Yang Ming Shan, Taipei 111, Taiwan (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The formation of the DLC:Cr films dependent on the flow rates of C{sub 2}H{sub 2}/Ar have been achieved in our FCVA plasma. Black-Right-Pointing-Pointer The amorphous DLC:Cr have high sp{sup 2} content can be completely converted to nanocrystalline Cr{sub 3}C{sub 2}. Black-Right-Pointing-Pointer The effect of doping with Cr is apparently to change the band structure of the DLC and its consequent cathodoluminescence property. - Abstract: Cr doped diamond-like carbon (DLC:Cr) film was synthesized in various flow rates of C{sub 2}H{sub 2}/Ar under a substrate voltage of -50 V at 500 Degree-Sign C by a filtered cathodic vacuum arc plasma. This work has found that the structure of the films was correlated to the flow rate of C{sub 2}H{sub 2}/Ar but the luminescence properties are similar. The cathodoluminescence spectra of DLC:Cr films obtained at 1.9-2.4 eV verifies that the luminescence from the films is in the visible region. The incorporation of Cr into the carbon network results in red emission shifted to 1.99 eV and the orange emission (2.03 eV) also appeared due to the transitions between chromium-related electron levels and {sigma}* states. The peak at 2.10 eV may result from the defects of the structures in DLC:Cr films.

  3. Reforming of biogas to synthesis gas by a rotating arc plasma at atmospheric pressure

    Science.gov (United States)

    Chung, Woo-Jae; Park, Hyun-Woo; Liu, Jing-Lin; Park, Dong-Wha

    2015-09-01

    In order to produce synthesis gas, reforming of biogas composed with 60 percent for CH4 and 40 percent for CO2 was performed by a novel rotating arc plasma process. The effect of O2/CH4 ratio on the conversion, syngas composition and energy cost was investigated to evaluate the performance of proposed system compared with conventional gliding arc plasma process. When the O2/CH4 ratio was increased from 0.4 to 0.9, the conversions of CH4 and O2 increased up to 97.5 percent and 98.8 percent, respectively, while CO2 conversion was almost constant to be 38.6 percent. This is due to more enhance the partial oxidation of CH4 to CO and H2 than that of dry reforming by increasing the O2/CH4 ratio. In this work, energy cost of 32 kJ/mol was achieved with high syngas composition of 71 percent using pure O2 as oxidant reactant. These are lower than those of different arc plasma processes (energy cost of 122 - 1870 kJ/mol) such as spark, spark-shade and gliding arc plasma. Because, this rotating arc plasma can remain in a long arc length and a large volume of plasma with constant arc length mode.

  4. New ion-assisted filtered cathodic arc deposition (IFCAD) technology for producing advanced thin films on temperature-sensitive substrates

    Science.gov (United States)

    Fulton, Michael L.

    1999-10-01

    An innovative Ion-Assisted Filtered Cathodic Arc Deposition (IFCAD) system has been developed for low temperature production of thin-film coatings. The IFCAD system employs electro-magnetic and mechanical filtering techniques to remove unwanted macroparticles and neutral atoms from the plasma stream. Therefore, only ions within a defined energy range arrive at the substrate surface, depositing thin-films with excellent mechanical and optical properties. Ion- Assisted-Deposition is coupled with Filtered Cathodic Arc technology to enhance and modify the arc deposited thin- films. Using an advanced computer controlled plasma beam scanning system, high quality, large area, uniform IFCAD multi-layer film structures are attained. Amorphous Diamond- Like-Carbon films (up to 85% sp3 bonded carbon; and micro- hardness greater than 50 GPa) have been deposited in multi- layer thin-film combinations with other IFCAD source materials (such as: Al2O3) for optical and tribological applications. Rutile TiO2 (refractive index of 2.8 at 500 nm) has been deposited with this technology for advanced optical filter applications. The new IFCAD technology has been included in development programs, such as: plastic and glass lens coatings for optical systems; wear resistant coatings on various metal substrates, ultra smooth, durable, surface hydrophobic coatings for aircraft windows; EUV coatings for space instrumentation; transparent conductive coatings; and UV protective coatings for solar cell concentrator plastic Fresnel lens elements for space power.

  5. Simulation of the atomic and ionic densities in the ionization layer of a plasma arc with a binary cathode

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, D; Marin, J A Sillero; Munoz-Serrano, E; Casado, E, E-mail: f92orhed@uco.e [Departamento de Fisica, Universidad de Cordoba, 14071 Cordoba (Spain)

    2009-04-21

    A physical model was developed to study the behaviour of the cathode material evaporated from a thoriated tungsten cathode of an atmospheric-pressure argon plasma arc. The densities of tungsten and thorium atoms and ions in the ionization layer were obtained, and the influence of the different physical processes on the evaporated cathode material was established. It was found that almost all of the neutral atoms evaporated from the cathode are ionized near the beginning of the ionization layer, i.e. near the boundary between the sheath and the ionization layer. Thorium ions are concentrated in a 4 {mu}m region near the beginning of this layer, while tungsten ions are found in a region of 9 {mu}m. The contribution of the electric force to the velocity of ions is the dominant contribution only near the beginning of the ionization layer. At a distance from the interface between the sheath and the ionization layer greater than 3.8 {mu}m in the case of thorium ions, and greater than 5 {mu}m in the case of tungsten ions, the contributions of the density gradient forces and the frictional forces are more important than the electric force contribution.

  6. Translational, rotational, vibrational and electron temperatures of a gliding arc discharge

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Ehn, Andreas; Gao, Jinlong

    2017-01-01

    the instantaneous length of the plasma column, the discharge voltage and the translational temperature, from which the electron temperature (Te) of the gliding arc discharge was estimated. The uncertainties of the translational, rotational, vibrational and electron temperatures were analyzed. The relations......, 0) band was used to simulate the rotational temperature (Tr) of the gliding arc discharge whereas the NO A–X (1, 0) and (0, 1) bands were used to determine its vibrational temperature (Tv). The instantaneous reduced electric field strength E/N was obtained by simultaneously measuring...... of these four different temperatures (Te>Tv>Tr >Tt) suggest a high-degree non-equilibrium state of the gliding arc discharge....

  7. Micro Cathode Arc Thruster for PhoneSat: Development and Potential Applications

    Science.gov (United States)

    Gazulla, Oriol Tintore; Perez, Andres Dono; Agasid, Elwood; Uribe, Eddie; Trinh, Greenfield; Keidar, Michael; Teel, George; Haque, Samudra; Lukas, Joseph; Salas, Alberto Guillen; hide

    2014-01-01

    NASA Ames Research Center and the George Washington University are developing an electric propulsion subsystem that will be integrated into the PhoneSat bus. Experimental tests have shown a reliable performance by firing three different thrusters at various frequencies in vacuum conditions. The interface consists of a microcontroller that sends a trigger pulse to the Pulsed Plasma Unit that is responsible for the thruster operation. A Smartphone is utilized as the main user interface for the selection of commands that control the entire system. The propellant, which is the cathode itself, is a solid cylinder made of Titanium. This simplicity in the design avoids miniaturization and manufacturing problems. The characteristics of this thruster allow an array of µCATs to perform attitude control and orbital correction maneuvers that will open the door for the implementation of an extensive collection of new mission concepts and space applications for CubeSats. NASA Ames is currently working on the integration of the system to fit the thrusters and the PPU inside a 1.5U CubeSat together with the PhoneSat bus. This satellite is intended to be deployed from the ISS in 2015 and test the functionality of the thrusters by spinning the satellite around its long axis and measure the rotational speed with the phone gyros. This test flight will raise the TRL of the propulsion system from 5 to 7 and will be a first test for further CubeSats with propulsion systems, a key subsystem for long duration or interplanetary small satellite missions.

  8. Investigations of the cathode region of an argon arc plasma by degenerate four-wave mixing laser spectroscopy and optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dzierzega, K [Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Cracow (Poland); Pokrzywka, B [Mt. Suhora Observatory, Cracow Pedagogical University, ul. Podchorazych 2, 30-083 Cracow (Poland); Pellerin, S [LASEP, Universite d' Orleans-Centre Universitaire de Bourges, Rue Gaston Berger BP 4043, 18028 Bourges (France)

    2004-07-07

    Degenerate four-wave mixing (DFWM) laser spectroscopy was used in local studies of atmospheric pressure argon plasma generated in a free-burning arc. The results of plasma diagnostics using the DFWM method were compared to the results obtained with optical emission measurements. In the cathode region of the arc the maxima of both the DFWM signal and the emission coefficient for the 696.5 nm Ar I line depend on the distance from the cathode tip. This effect proves the departure of the plasma state from local thermal equilibrium (LTE) as it has been reported by many authors. On the other hand the Stark shifts of the 696.5 nm Ar I line determined by the DFWM method in relation to plasma diagnostic results show no deviations from LTE on the arc axis down to 1.0 mm from the cathode tip.

  9. Ion sources with arc-discharge plasma box driven by directly heated LaB(6) electron emitter or cold cathode.

    Science.gov (United States)

    Ivanov, Alexander A; Davydenko, Vladimir I; Deichuli, Petr P; Shulzhenko, Grigori I; Stupishin, Nikolay V

    2008-02-01

    In the Budker Institute, Novosibirsk, an ion source with arc-discharge plasma box has been developed in the recent years for application in thermonuclear devices for plasma diagnostics. Several modifications of the ion source were provided with extracted current ranging from 1 to 7 A and pulse duration of up to 4 s. Initially, the arc-discharge plasma box with cold cathode was used, with which pulse duration is limited to 2 s by the cathode overheating and sputtering in local arc spots. Recently, a directly heated LaB(6) electron emitter was employed instead, which has extended lifetime compared to the cold cathode. In the paper, characteristics of the beam produced with both arrangements of the plasma box are presented.

  10. Suppression of Cross Contamination in Multi-Layer Thin Film Prepared by Using Rotating Hexagonal Sputtering Cathode.

    Science.gov (United States)

    Park, Se Yeon; Choi, Bum Ho; Lee, Jong Ho

    2015-01-01

    In this study, single- and multi-layered thin films were prepared on a glass substrate using a newly developed rotating hexagonal sputtering cathode in a single chamber. The rotatinghexagonal sputtering cathode can install up to six different sputtering targets or six single targets in a cathode. Using the rotating hexagonal cathode, we prepared a single-layered AZO film and a multi-layer film to evaluate the performance of hexagonal gun. Cross-contamination, which is often observed in multi-layer thin film preparation, was suppressed to nearly zero by controlling process parameters and revising hardware. Energy-saving effects of five-layered glass were also verified by measuring the temperature.

  11. Influence of gas pressure on electron beam emission current of pulsed cathodic-arc-based forevacuum plasma electron source

    Science.gov (United States)

    Burdovitsin, Victor A.; Kazakov, Andrey V.; Medovnik, Alexander V.; Oks, Efim M.

    2017-09-01

    We describe our experimental investigation of the effect of background gas pressure on the emission parameters of a pulsed cathodic-arc-based forevacuum-pressure plasma-cathode electron source. We find that increased gas pressure over the range 4-16 Pa significantly reduces the beam current rise-time and significantly increases the emission current amplitude. For example, at a discharge current of 20 A, increasing the working gas pressure from 4 Pa to 16 Pa increases the emission current from 8 A to 18 A and shortens the beam rise-time from 50 μs to 20 μs. This influence of gas pressure on the electron beam parameters can be explained by the effect of arc discharge current switching from the anode to emission. In our case, the current switching effect is caused by increased working gas pressure. In the forevacuum pressure range, the increase of the electron emission current with the growth of gas pressure is due to a rise in the emission plasma potential which is caused by ion back-streaming from the plasma formed in the electron beam transport region. A model describing the influence of gas pressure on the electron emission from the plasma is presented.

  12. The determination of micro-arc plasma composition and properties of nanoparticles formed during cathodic plasma electrolysis of 304 stainless steel

    Science.gov (United States)

    Jovović, Jovica; Stojadinović, Stevan; Vasilić, Rastko; Tadić, Nenad; Šišović, Nikola M.

    2017-05-01

    This paper presents the research focused on the determination of micro-arc plasma composition during cathodic plasma electrolysis of AISI304 stainless steel in water solution of sodium hydroxide. The complex line shape of several Fe I spectral lines was observed and, by means of a dedicated fitting procedure based on the spectral line broadening theory and H2O thermal decomposition data, the mole fraction of micro-arc plasma constituents (H2, Fe, O, H, H2O, and OH) was determined. Subsequent characterization of the cathodic plasma electrolysis product formed during the process revealed that it consists of Fe-nanoparticles with median diameter of approximately 60 nm.

  13. Mathematical modeling of the temperature distribution under the cathode spot of the vacuum arc

    Science.gov (United States)

    Kuznetsov, V. G.; Babushkina, E. S.

    2016-07-01

    We present a solution to the problem of the temperature distribution under the cathode spot of taking into account melting and spare deposits of metal, brought to boiling temperature on the surface of the cathode spot. The process of heat transfer in the metal is described by the unsteady three dimensional heat conduction equation in Cartesian coordinate system. Similarly, we present a solution to the problem of the temperature distribution in the presence of the pores in the surface layer of the metal. To solve this task we used a numerical method to finite differences and variable directions. We present the calculated data on the distribution of temperature under the cathode spot for different values of spot diameters and speeds its movement.

  14. Synthesis of aluminium nanoparticles by arc evaporation of an aluminium cathode surface

    Indian Academy of Sciences (India)

    M Gazanfari; M Karimzadeh; S Ghorbani; M R Sadeghi; G Azizi; H Karimi; N Fattahi; Z Karimzadeh

    2014-06-01

    Aluminium nanoparticles (Al Nps) are synthesized using arc discharge method by applying direct current between aluminium electrodes in liquid environment without any use of vacuum equipment, heat exchangers, high temperatures furnaces and inert gases. After synthesis of Al Nps, in situ coating process on the nanoparticles was performed immediately. The effects of media on the yield and morphology of aluminium nanoparticles were investigated. Analysis result of the samples indicated that particle size was less than 30 nm, when 120 A/cm2 arc current was used. In addition, coating agent can affect arc velocity, arc stability, morphology and composition of the nanoparticles. Resultant nanoparticles were identified using X-ray powder diffraction (XRD), also their surface morphology was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and finally the accuracy of coating was assessed with infrared (IR) spectroscopy.

  15. Preparation of TiOx Films by Cathode Multi Arc Ion and Its Performance%TiO薄膜的多弧离子制备及表征

    Institute of Scientific and Technical Information of China (English)

    范多进; 范多旺; 王成龙; 刘红忠

    2007-01-01

    @@ Experimental Procedure Fig. 1 shows the custom-made Cathode Multi Arc Ion equipment, which is made up of three pars:CCS(computer contral system, Fig. 1's left part), Vacuum Chamber (Fig. 1's middle part) and Air Pump parts(Fig. 1's right part).

  16. Clues for a Tortonian reconstruction of the Gibraltar Arc: Structural pattern, deformation diachronism and block rotations

    Science.gov (United States)

    Crespo-Blanc, Ana; Comas, Menchu; Balanyá, Juan Carlos

    2016-06-01

    We proposed a reconstruction of one of the tightest orogenic arcs on Earth: the Gibraltar Arc System. This reconstruction, which includes onshore and offshore data, is completed for approximately 9 Ma. The clues that lead us to draw it are based on a review in terms of structures and age of the superposed deformational events that took place during Miocene, with special attention to the external zones. This review and new structural data presented in this paper permit us to constrain the timing of vertical axis-rotations evidenced by previously published paleomagnetic data, and to identify homogeneous domains in terms of relationships between timing of deformation events, (re)magnetization and rotations. In particular, remagnetization in the Betics took place after the main shortening which produced the external fold-and-thrust belts (pre-upper Miocene), but was mostly previous to a contractive reorganization that affected the whole area; it should have occurred during lower Tortonian (between 9.9 and 11 Ma). From Tortonian to Present, block-rotations as high as 53° took place. Together with plate convergence, they accommodated a tightening and lengthening of the Gibraltar Arc System and drastically altered its geometry. As the orientation and position of any pre-9 Ma kinematic indicator or structural element is also modified, our reconstruction should be used as starting point for any pre-Tortonian model of the westernmost orogenic segment of the Alpine-Mediterranean system.

  17. Low-temperature deposited ZnO thin films on the flexible substrate by cathodic vacuum arc technology

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ru-Yuan, E-mail: ryyang@mail.npust.edu.tw [Department of Materials Engineering, National Ping-Tung University of Science and Technology, Taiwan (China); Weng, Min-Hang [Medical Devices and Opto-electronics Equipment Department, Metal Industries Research and Development Center, Taiwan (China); Pan, Cheng-Tang [Department of Mechanical and Electron-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung County 804, Taiwan (China); Hsiung, Chin-Min; Huang, Chun-Chih [Department of Mechanical Engineering, National Ping-Tung University of Science and Technology, Taiwan (China)

    2011-06-01

    In this paper, un-doped zinc oxide (ZnO) films with various thicknesses (150, 250, 350, 450 and 550 nm) were successfully prepared onto PET substrates using cathodic vacuum arc technique at low-temperature (<40 deg. C). Their microstructure, optical and electrical properties were investigated and discussed. The films showed (0 0 2) peaks, an average transmittance over 80% in the visible region. Calculated values of the band gap are around 3.29-3.33 eV when the film thickness increased, indicating a slight blue shift of optical transmission spectra. The lowest resistivity about 5.26 x 10{sup -3} {Omega} cm could be achieved for the un-doped ZnO film with thickness of 550 nm.

  18. The effect of substrate bias on titanium carbide/amorphous carbon nanocomposite films deposited by filtered cathodic vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xu, E-mail: zhangxu@bnu.edu.cn [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University (China); Liang, Hong [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University (China); Wu, Zhenglong [Analytical and Testing Center, Beijing Normal University (China); Wu, Xiangying; Zhang, Huixing [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University (China)

    2013-07-15

    The titanium carbide/amorphous carbon nanocomposite films have been deposited on silicon substrate by filtered cathodic vacuum arc (FCVA) technology, the effects of substrate bias on composition, structures and mechanical properties of the films are studied by scanning electron spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy and nano-indentation. The results show that the Ti content, deposition rate and hardness at first increase and then decrease with increasing the substrate bias. Maximum hardness of the titanium carbide/amorphous carbon nanocomposite film is 51 Gpa prepared at −400 V. The hardness enhancement may be attributed to the compressive stress and the fraction of crystalline TiC phase due to ion bombardment.

  19. Cathodic micro-arc electro-deposition of ZrO2 coatings in an aqueous solution containing colloidal particles

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By a novel technique-cathodic micro-arc electro-deposition (CMED), ZrO2 coatings were deposited on an FeCrAl alloy. Experimental results show that the necessary conditions for obtaining ZrO2 coatings are to apply a pulse peak voltage over a critical value and add moderate amounts of ZrO2 colloidal particles and Zr(NO3)4 in the aqueous solution. The as-deposited coatings are porous because hydrogen, water, and other vapors are generated and released from the coatings to the solution during the spark reaction. The coatings contain monoclinic and tetragonal crystalline ZrO2with certain degree of amorphous structure. The processing parameters and mechanism of CMED were discussed.

  20. Effect of high substrate bias and hydrogen and nitrogen incorporation on filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India)], E-mail: ospanwar@mail.nplindia.ernet.in; Khan, Mohd. Alim [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Kumar, Mahesh; Shivaprasad, S.M. [Surface Physics and Nanostructures Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Satyanarayana, B.S. [MIT Innovation Centre and Electronics and Communication Department, Manipal Institute of Technology, Manipal-579104 (India); Dixit, P.N. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Bhattacharyya, R. [Emeritus Scientist, National Physical Laboratory, New Delhi-110012 (India); Khan, M.Y. [Department of Physics, Jamia Millia Islamia, Central University, New Delhi-110025 (India)

    2008-02-29

    The application of a sufficiently high negative substrate bias, during the growth of tetrahedral amorphous carbon (ta-C), is usually associated with low sp{sup 3} bonding configuration and stressed films. However, in an effort to understand and utilize the higher pseudo thermo dynamical conditions during the film growth, at high negative substrate bias (- 300 V), reported here is a study on ta-C films grown under different hydrogen and nitrogen concentration. As grown ta-C films were studied under different negative substrate bias conditions. The variation of the sp{sup 3} content and sp{sup 3}/sp{sup 2} ratio in the ta-C films exhibits a trend similar to those reported in literature, with a subtle variation in this report being the substrate bias voltage, which was observed to be around - 200 V, for obtaining the highest sp{sup 3} (80%) bonding and sp{sup 3}/sp{sup 2} (3.95) ratio. The hydrogen and nitrogen incorporated ta-C films studied, at a bias of - 300 V, show an increase in sp{sup 3} (87-91%) bonding and sp{sup 3}/sp{sup 2} (7-10) ratio in the range of studies reported. The inference is drawn on the basis of the set of data obtained from measurements carried out using X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy and Raman spectroscopy of as grown and hydrogen and nitrogen incorporated ta-C films deposited using an S bend filtered cathodic vacuum arc system. The study indicates the possibility of further tailoring ta-C film properties and also extending capabilities of the cathodic arc system for developing carbon based films for electronics and tribological applications.

  1. Continuous calibration of a vacuum ultraviolet system from 65 to 125 nm by a cascade arc and comparison with the calibrated line radiation of a hollow cathode.

    Science.gov (United States)

    Frost, R M; Awakowicz, P

    1997-03-20

    A high-power stationary helium cascade arc has been developed as a standard source for continuum radiation in the VUV spectral range from 65 to 125 nm. The calibration of the VUV system response was based on the calculated and measured continuum radiation of a 2-mmphi pure He arc. Diagnostics of the arc plasma in partial thermal equilibrium yielded the electron density and the temperature that were inserted in the calculations of the continuous radiation. The results were compared with the helium, argon, and krypton radiation lines of a high-current hollow cathode lamp. This lamp was built according to the construction drawings of a hollow cathode, which was calibrated by means of the electron synchrotron radiation at the Physikalisch Technische Bundesanstalt Berlin.

  2. Achieving high mobility ZnO : Al at very high growth rates by dc filtered cathodic arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsberg, R J; Lim, S H N; Wallig, J; Anders, A [Lawrence Berkeley National Laboratory, Plasma Applications Group, Berkeley, CA (United States); Zhu, Y K [Harbin Institute of Technology, Harbin (China); Milliron, D J, E-mail: aanders@lbl.gov [Lawrence Berkeley National Laboratory, Molecular Foundry, Berkeley, CA (United States)

    2011-06-15

    Achieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500-1300 nm thick and highly transparent ZnO : Al films were grown on glass at rates exceeding 250 nm min{sup -1} while maintaining resistivity below 5 x 10{sup -4} {Omega} cm with electron mobility as high as 60 cm{sup 2} V{sup -1} s{sup -1}. (fast track communication)

  3. Particle-in-cell and Monte Carlo collision simulations of the cathode sheath in an atmospheric direct-current arc discharge

    Science.gov (United States)

    Zhou, Wen; Guo, Heng; Jiang, Wei; Li, He-Ping; Li, Zeng-Yao; Lapenta, Giovanni

    2016-10-01

    A sheath is the transition region from plasma to a solid surface, which also plays a critical role in determining the behaviors of many lab and industrial plasmas. However, the cathode sheath properties in arc discharges are not well understood yet due to its multi-scale and kinetic features. In this letter, we have adopted an implicit particle-in-cell Monte Carlo collision (PIC-MCC) method to study the cathode sheath in an atmospheric arc discharge plasma. The cathode sheath thickness, number densities and averaged energies of electrons and ions, the electric field distribution, as well as the spatially averaged electron energy probability function (EEPF), are predicted self-consistently by using this newly developed kinetic model. It is also shown that the thermionic emission at the hot cathode surface is the dominant electron emission process to sustain the arc discharges, while the effects from secondary and field electron emissions are negligible. The present results verify the previous conjectures and experimental observations.

  4. Study of the feasibility of distributed cathodic arc as a plasma source for development of the technology for plasma separation of SNF and radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Amirov, R. Kh.; Vorona, N. A.; Gavrikov, A. V.; Liziakin, G. D.; Polistchook, V. P.; Samoylov, I. S.; Smirnov, V. P.; Usmanov, R. A., E-mail: ravus46@yandex.ru; Yartsev, I. M. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2015-12-15

    One of the key problems in the development of plasma separation technology is designing a plasma source which uses condensed spent nuclear fuel (SNF) or nuclear wastes as a raw material. This paper covers the experimental study of the evaporation and ionization of model materials (gadolinium, niobium oxide, and titanium oxide). For these purposes, a vacuum arc with a heated cathode on the studied material was initiated and its parameters in different regimes were studied. During the experiment, the cathode temperature, arc current, arc voltage, and plasma radiation spectra were measured, and also probe measurements were carried out. It was found that the increase in the cathode heating power leads to the decrease in the arc voltage (to 3 V). This fact makes it possible to reduce the electron energy and achieve singly ionized plasma with a high degree of ionization to fulfill one of the requirements for plasma separation of SNF. This finding is supported by the analysis of the plasma radiation spectrum and the results of the probe diagnostics.

  5. SU-E-T-592: Comparison of Low Dose Volume and Integral Dose in Rotational Arc Radiation Therapy Modalities.

    Science.gov (United States)

    Lian, J; Song, H; Liu, R; Qi, S; Hu, A

    2012-06-01

    To compare low dose volume and integral dose of various rotational arc radiation therapy modalities, including helical tomotherapy (HT) and other volumetric modulated arc therapies (VMAT). A digital cylindrical phantom and an anthropomorphic pelvic phantom were used in the study. HT treatment was planned on TomoTherapy Planning Station (Accuray) and VMAT plans were generated on Pinnacle (Philips) and Eclipse (Varian). Same objectives and criteria were used for all the planning tasks. Tomotherapy plans were made with both 1cm jaw and 2.5cm jaw. Pinnacle SmartArc and Eclipse RapidArc plans used 1 arc and 2 arcs. Plan quality was evaluated by dose-volume histograms, conformity index (CI), and heterogeneity index (HI). V10% and V20% of body were used in quantifying low dose volume. Integral doses were computed for each plan and compared. Dose profiles across the target center were retrieved to show the rate of dose falls off. All arc TPS generated clinically acceptable plan with comparable target CI and HI. The V20% of body of the cylindrical phantom case were 3551cc, 4054cc, 3375cc, 3438cc, 3714cc and 3679cc for tomotherapy 1 cm and 2 cm jaw, SmartArc 1 arc and 2 arc, and RapidArc 1 arc and 2 arc plans, respectively. The integral doses were 19.67, 22.78, 18.68, 18.50, 19.78 and 19.73 Joule, respectively. For the anthropomorphic phantom, the integral doses were 81.69, 102.77, 84.5 and 82.5 Joule for tomotherapy 1cm, 2cm, SmartArc 1arc and RapidArc 1arc, respectively. Dose profiles showed tomotherapy 1cm plan had similar longitudinal penumbra as SmartArc and RapidArc, while tomotherapy 2.5cm plan produced significant broader penumbra. Similar low dose volume and integral dose are found in SmartArc, Rapid Arc, and as well as helical tomotherapy plan of 1cm jaw. Tomotherapy plans of 2.5cm jaw, however, shows higher low dose volume and integral dose. © 2012 American Association of Physicists in Medicine.

  6. Rotational and Vibrational Temperatures of Atmospheric Double Arc Argon-Nitrogen Plasma

    Institute of Scientific and Technical Information of China (English)

    YAN Jian-Hua; TU Xin; MA Zeng-Yi; CEN Ke-Fa; B.G.Chéron

    2007-01-01

    The spectroscopic technique is employed to study the emission of atmospheric argon-nitrogen plasma jet generated by an original dc double anode plasma torch. The molecular bands of the N(+2) first negative system are observed at the torch exit and chosen to evaluate the rotational and vibrational temperatures in comparison with the simulated spectra. The excitation temperature (Texc≈9600 K) is determined from the Boltzmann plot method. The results show that the rotational, vibrational, electron and kinetic temperatures are in good agreement with one another, which indicates that the core region of atmospheric double arc argon-nitrogen plasma jet at the torch exit is close to the local thermodynamic equilibrium state under our experimental conditions.

  7. Pyrolysis of Polyolefins Using Rotating Arc Plasma Technology for Production of Acetylene

    Directory of Open Access Journals (Sweden)

    Ming Zhang

    2017-04-01

    Full Text Available Polyolefin, as one of the most widely used macromolecule materials, has been one of the most serious threats to the environment. Current treatment methods of waste polyolefin including landfill, incineration, and thermal degradation have suffered from severe problems such as secondary pollution and the generation of other toxic substances. In this article, we report for the first time a high-efficiency method to produce high-value C2H2 from polyolefins using a rotating direct current arc plasma reactor, using polyethylene and polypropylene as feedstocks. The essence of this method is that a reductive atmosphere of pyrolysis enables a thermodynamic preference to C2H2 over other carbon-containing gas and the rotating direct current arc plasma reactor allows for a uniform distribution of high temperature to ensure high conversion of polymers. Thermodynamic simulation of product composition was performed, and the effect of plasma input power, polyolefin feed rate, and working gas flow rate on the pyrolysis results was experimentally investigated. It was found that, with proper parameter control, approximately complete conversion of carbon in polyolefin could be obtained, with a C2H2 selectivity higher than 80% and a C2H2 yield higher than 70%. These results not only create new opportunities for the reuse of polymer waste, but are also instructive for the green production of C2H2.

  8. Facile electrochemical polymerization of polypyrrole film applied as cathode material in dual rotating disk photo fuel cell

    Science.gov (United States)

    Li, Kan; Zhang, Hongbo; Tang, Tiantian; Tang, Yanping; Wang, Yalin; Jia, Jinping

    2016-08-01

    Polypyrrole (PPy) film is synthesized on Ti substrate through electrochemical polymerization method and is applied as cathode material in a TiO2 NTs-PPy dual rotating disk photo fuel cell (PFC). The optimized PPy electrochemical polymerization is carried out using linear sweep voltammetry from 0 V to 1.2 V (vs. SCE) with scan rate of 0.1 V s-1, 100 circles. Sixty milliliter real textile wastewater with the initial COD and conductivity of 408 ± 6 mgO2 L-1 and 20180 μS cm-1 is treated in this PFC under UV irradiation. About 0.46 V open-circuit voltage (VOC) and 1.8-2.2 mA short-circuit current (JSC) are obtained. Due to the effective electron-hole separation effect, the COD removal rate is as high as 0.0055 min-1. Stable current and COD removal can be obtained at different output voltage. Two influence factors including rotating speed and pH are investigated. Better electricity generation performance and COD removal activity are achieved at high rotating speed and in acidic condition. In comparison with platinized cathode, though VOC is lower, similar JSC is measured. Considering the high cost of Pt, PPy is a promising alternative cathode material in PFC that can also generate electricity efficiently and stably.

  9. Deposition of TiN Films by Novel Filter Cathodic Arc Technique

    Institute of Scientific and Technical Information of China (English)

    NIU Er-Wu; FAN Song-Hua; LI Li; L(U) Guo-Hua; FENG Wen-Ran; ZHANG Gu-Ling; YANG Si-Ze

    2006-01-01

    A straight magnetic filtering arc source is used to deposit thin films of titanium nitride.The properties of thefilms depend strongly on the deposition process.TiN films can be deposited directly onto heated substrates in anitrogen atmosphere or onto unbiased substrates by condensing the Ti+ ion beam in about 300 eV N2+ nitrogen ionbombardment.In the latter case.the film stoichiometry is varied from an N:Ti ratio of 0.6-1.1 by controlling thearrival rates of Ti and nitrogen ions.Meanwhile,simple models are used to describe the evolution of compressivestress as function of the arrival ratio and the composition of the ion-assisted TiN films.

  10. Fabricating Aluminum Bronze Rotating Band for Large-Caliber Projectiles by High Velocity Arc Spraying

    Science.gov (United States)

    Wu, Bin; Fang, Ling-hui; Chen, Xiao-lei; Zou, Zhi-qiang; Yu, Xu-hua; Chen, Gang

    2014-02-01

    The necessity of finding new rotating band materials and developing corresponding joining technologies for large-caliber projectiles has been revealed by the recent increase in the ballistic performance of high loads. In this paper, aluminum bronze coatings were fabricated by the high velocity arc spraying (HVAS) technique. Microstructure and microhardness of the prepared coatings were investigated. Ring-on-disk dry sliding wear tests were conducted in an ambient condition to examine the tribological behavior of the coatings. Quasi-static engraving processes of rotating bands made of as-sprayed aluminum bronze coating and bulk copper were studied using rate-controlled push test methodology on an MTS 810 Material Testing System. The results show that the as-sprayed aluminum bronze coatings have a dense microstructure with porosity of about 1.6%. Meanwhile, the as-sprayed coating presents a higher microhardness than pure copper. The friction coefficient of coatings is about 0.2-0.3 in the steady state. Tribological mechanisms of the as-sprayed coatings were discussed. The engraving test results show that the aluminum bronze rotating band presents high bonding strength and good plasticity. The HVAS aluminum bronze coating should be a possible substitute for the state-of-the-art copper rotating band.

  11. The improvement of all-solid-state electrochromic devices fabricated with the reactive sputter and cathodic arc technology

    Directory of Open Access Journals (Sweden)

    Min-Chuan Wang

    2016-11-01

    Full Text Available The all-solid-state electrochromic device (ECD with the one substrate structure fabricated by the reactive dc magnetron sputtering (DCMS and cathodic vacuum arc plasma (CVAP technology has been developed for smart electrochromic (EC glass application. The EC layer and ion conductor layer were deposited by reactive DCMS and CVAP technology, respectively. The ion conductor layer Ta2O5 deposited by the CVAP technology has provided the better porous material structure for ion transportation and showed 1.76 times ion conductivity than devices with all sputtering process. At the same time, the EC layer WO3 and NiO deposited by the reactive DCMS have also provided the high quality and uniform characteristic to overcome the surface roughness effect of the CVAP ion conductor layer in multilayer device structure. The all-solid-state ECD with the CVAP ion conductor layer has demonstrated a maximum transmittance variation (ΔT of 55% at 550nm and a faster-switching speed. Furthermore, the lower equipment cost and higher deposition rate could be achieved by the application of CVAP technology.

  12. The improvement of all-solid-state electrochromic devices fabricated with the reactive sputter and cathodic arc technology

    Science.gov (United States)

    Wang, Min-Chuan; Chen, Yung-Chih; Hsieh, Ming-Hao; Li, Yu-Chen; Wang, Jen-Yuan; Wu, Jin-Yu; Tsai, Wen-Fa; Jan, Der-Jun

    2016-11-01

    The all-solid-state electrochromic device (ECD) with the one substrate structure fabricated by the reactive dc magnetron sputtering (DCMS) and cathodic vacuum arc plasma (CVAP) technology has been developed for smart electrochromic (EC) glass application. The EC layer and ion conductor layer were deposited by reactive DCMS and CVAP technology, respectively. The ion conductor layer Ta2O5 deposited by the CVAP technology has provided the better porous material structure for ion transportation and showed 1.76 times ion conductivity than devices with all sputtering process. At the same time, the EC layer WO3 and NiO deposited by the reactive DCMS have also provided the high quality and uniform characteristic to overcome the surface roughness effect of the CVAP ion conductor layer in multilayer device structure. The all-solid-state ECD with the CVAP ion conductor layer has demonstrated a maximum transmittance variation (Δ T ) of 55% at 550nm and a faster-switching speed. Furthermore, the lower equipment cost and higher deposition rate could be achieved by the application of CVAP technology.

  13. Properties of boron and phosphorous incorporated tetrahedral amorphous carbon films grown using filtered cathodic vacuum arc process

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Khan, Mohd Alim [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Satyanarayana, B.S. [40, Sreeniketan, NDSE 24, New Delhi 110096 (India); Kumar, Sushil; Ishpal [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2010-04-15

    This paper reports the electrical, mechanical, structural and field emission properties of as grown and also boron and phosphorous incorporated tetrahedral amorphous carbon (ta-C) films, deposited using a filtered cathodic vacuum arc process. The effect of varying boron and phosphorous content (up to 2.0 at.% in to ta-C) on the conductivity ({sigma}{sub D}), activation energy ({Delta}E{sub 1}), hardness, microstructure, emission threshold (E{sub turn-ON}) and emission current density (J) at 12.5 V/{mu}m of ta-C: B and ta-C: P films deposited at a high negative substrate bias of -300 V are reported. It is observed that both boron and phosphorous incorporation leads to a nearly an order increase in {sigma}{sub D} and corresponding decrease in {Delta}E{sub 1} and a slight increase in hardness as compared to as grown ta-C films. In the case of field assisted electron emission, it is observed that E{sub turn-ON} increases and J decreases. The changes are attributed to the changes in the sp{sup 3}/sp{sup 2} ratio of the films due to boron and phosphorous incorporation. The effect of boron on ta-C is to give a p-type effect whereas the effect of phosphorous gives n-type doping effect.

  14. Density changes with substrate negative bias for ta-C films deposited by filter cathode vacuum arc

    Institute of Scientific and Technical Information of China (English)

    TAN Man-lin; ZHU Jia-qi; HAN Jie-cai; MENG Song-he

    2004-01-01

    Specular X-ray reflectivity (XRR) measurements were used to study the density and cross-section information of tetrahedral amorphous carbon (ta-C) films deposited by filter cathode vacuum arc(FCVA) system at different substrate bias. According to the correlation between density and substrate negative bias, it is found that the value of density reaches a maximum at -80 V bias. As the substrate bias increases or decreases, the density tends to lower gradually. Based on the density of diamond and graphite, sp3 bonding ratio of ta-C films was obtained from their corresponding density according to a simple equation between the two. And a similar parabolic variation was observed for ta-C films with the sp3 content changes with substrate negative bias. The mechanical properties such as hardness and elastic modulus were also measured and compared with the corresponding density for ta-C films. From the distribution of data points, a linear proportional correlation between them was found, which shows that the density is a critical parameter to characterize the structure variation for ta-C films.

  15. Microstructures and friction-wear behaviors of cathodic arc ion plated CrC coating at high temperatures

    Science.gov (United States)

    Dejun, Kong; Shouyu, Zhu

    2016-11-01

    A CrC coating was deposited on YT14 cemented carbide cutting tools by a CAIP (cathodic arc ion plating). The surface and interface morphologies, chemical composition, and phases of the obtained coating were analyzed with a field emission scanning electronic microscope (FESEM), energy dispersive spectroscope (EDS), and x-ray diffraction (XRD), respectively. The COFs (coefficient of frictions) and worn morphologies of the CrC coating at 300 °C, 400 °C, and 500 °C were investigated by using a high temperature tribometer, the effects of wear temperatures on the friction-wear properties of the CrC coating were discussed. The results show that the CrC coating exhibits fine dense structure, and the lattice constants of CrC coatings are dependent on processing parameters. The C and Cr elements in the coating are mutually diffused with the W, Co, and Ti in the substrate. The average COF of the coating at 300 °C, 400 °C, and 500 °C is 0.64, 0.63, and 0.40, respectively. The Cr2O3 layer formed on the CrC coating at 500 °C has excellent oxidation resistance, which improves lubrication and wear performance, the wear mechanism is abrasive wear and oxidation wear.

  16. 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.

  17. Effects of filtered cathodic vacuum arc deposition (FCVAD) conditions on photovoltaic TiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Aramwit, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Intarasiri, S. [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Bootkul, D. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Tippawan, U. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Supsermpol, B.; Seanphinit, N. [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Western Digital Thailand Co. Ltd., Ayutthaya 13160 (Thailand); Ruangkul, W. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2014-08-15

    Highlights: • Titanium dioxide films were synthesized using the FCVAD technique. • Various FCVAD conditions were tested. • The TiO{sub 2} films were characterized. • The FCVAD condition effects on the film characteristics were studied. • The O{sub 2} pressure had the most important effect on the film quality. - Abstract: Titanium dioxide (TiO{sub 2}) films for photovoltaic applications were synthesized using filtered cathodic vacuum arc deposition (FCVAD) technique. Various deposition conditions were tested for an optimal film formation. The conditions included the oxygen (O{sub 2}) pressure which was varied from a base pressure 10{sup −5} to 10{sup −4}, 10{sup −3}, 10{sup −2} and 10{sup −1} Torr, sample holder bias varied using 0 or −250 V, deposition time varied from 10, 20 to 30 min, and deposition distance varied from 1 to 3 cm. The deposited films were also annealed and compared with unannealed ones. The films under various conditions were characterized using optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy techniques. The film transparency increased and thickness decreased to a nanoscale with increasing of the O{sub 2} pressure. The transparent deposited films contained stoichiometric titanium and oxygen under the medium O{sub 2} pressure. The as-deposited films were TiO{sub 2} containing some rutile but no anatase which needed annealing to form.

  18. Influence of substrate bias on the structure and properties of ZrN films deposited by cathodic vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Niu, E.W. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China)], E-mail: new05@aphy.iphy.ac.cn; Li, L. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China); Lv, G.H. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China); Chen, H. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China); Feng, W.R. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China); Fan, S.H. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China); Yang, S.Z. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China); Yang, X.Z. [Beijing National Laboratory for Condensed Matter, Institute of Physics, Chinese Academy of Science, 100080 Beijing (China)

    2007-07-15

    ZrN films were deposited by cathodic vacuum arc (CVA) technique in N{sub 2} atmosphere at low temperature with different substrate bias. The ZrN films deposited are atomically smooth. The influence of substrate bias at the wide range (0 to -500 V) on the deposition rate, surface morphology, crystal structure, internal stress, and mechanical properties of the ZrN films were systematically investigated. Increasing substrate bias results in the decrease of deposition rate and the increase of surface roughness. It was found that there is a strong correlation between the substrate bias, film structure and properties. At the bias of 0 V, ZrN films characterize with random orientation, low surface roughness, small grain size. With the increase of bias, the structure changes from random orientation to (1 1 1) preferred orientation and then to (2 2 0) orientation. As substrate bias increases to about -150 V, the internal stress, hardness and Young's modulus increase to maximum. A further increase of bias results in the gradual decrease to lower level.

  19. Comparative study of titanium carbide and nitride coatings grown by cathodic vacuum arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Devia, D.M. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia); Universidad Tecnologica de Pereira, Pereira (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia); PCM Computational Applications, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia); Arango, P.J. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia)

    2011-11-15

    Titanium nitride (TiN), titanium carbide (TiC) thin films and TiC/TiN bilayers have been deposited on AISI 304 stainless steel substrates by plasma assisted physical vapor deposition technique - reactive pulsed vacuum arc method. The coatings were characterized in terms of crystalline structure, microstructure and chemical nature by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Tribological behavior was investigated using ball on disc technique. The average coefficient of friction was measured, showing lower values for the TiN/TiC bilayer. Dynamic wear curves were performed for each coating, observing a better wear resistance for TiN/TiC bilayers, compared to TiN and TiC monolayers. On the other hand, the TiCN formation in the TiN/TiC bilayer was observed, being attributed to the interdiffusion between TiN and TiC at the interface. Moreover, the substrate temperature influence was analysing observing a good behavior at T{sub S} = 115 Degree-Sign C.

  20. X-ray reflectivity analysis of titanium dioxide thin films grown by cathodic arc deposition.

    Science.gov (United States)

    Kleiman, A; Lamas, D G; Craievich, A F; Márquez, A

    2014-05-01

    TiO2 thin films deposited by a vacuum arc on a glass substrate were characterized by X-ray reflectivity (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Several thin films with different amounts of deposited TiO2 mass and different deposition and annealing temperatures were studied. A qualitative analysis of the XRD patterns indicated the presence of the anatase and/or rutile crystalline phases in most of the studied samples. From the analysis of the experimental XRR curves--which exhibited a wide angular range of oscillatory behavior--the thickness, mass density and interface roughness were determined. All XRR patterns were well fitted by modeled curves that assume the presence of a single and homogeneous TiO2 layer over which a very thin H2O layer is adsorbed. The thickest H2O adsorption layers were developed in films with the highest anatase content. Our overall results of the XRR analyses are consistent with those derived from the imaging techniques (SEM and AFM).

  1. Trajectory optimization for dynamic couch rotation during volumetric modulated arc radiotherapy

    Science.gov (United States)

    Smyth, Gregory; Bamber, Jeffrey C.; Evans, Philip M.; Bedford, James L.

    2013-11-01

    Non-coplanar radiation beams are often used in three-dimensional conformal and intensity modulated radiotherapy to reduce dose to organs at risk (OAR) by geometric avoidance. In volumetric modulated arc radiotherapy (VMAT) non-coplanar geometries are generally achieved by applying patient couch rotations to single or multiple full or partial arcs. This paper presents a trajectory optimization method for a non-coplanar technique, dynamic couch rotation during VMAT (DCR-VMAT), which combines ray tracing with a graph search algorithm. Four clinical test cases (partial breast, brain, prostate only, and prostate and pelvic nodes) were used to evaluate the potential OAR sparing for trajectory-optimized DCR-VMAT plans, compared with standard coplanar VMAT. In each case, ray tracing was performed and a cost map reflecting the number of OAR voxels intersected for each potential source position was generated. The least-cost path through the cost map, corresponding to an optimal DCR-VMAT trajectory, was determined using Dijkstra’s algorithm. Results show that trajectory optimization can reduce dose to specified OARs for plans otherwise comparable to conventional coplanar VMAT techniques. For the partial breast case, the mean heart dose was reduced by 53%. In the brain case, the maximum lens doses were reduced by 61% (left) and 77% (right) and the globes by 37% (left) and 40% (right). Bowel mean dose was reduced by 15% in the prostate only case. For the prostate and pelvic nodes case, the bowel V50 Gy and V60 Gy were reduced by 9% and 45% respectively. Future work will involve further development of the algorithm and assessment of its performance over a larger number of cases in site-specific cohorts.

  2. Interface control of atomic layer deposited oxide coatings by filtered cathodic arc deposited sublayers for improved corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Härkönen, Emma, E-mail: emma.harkonen@helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Tervakangas, Sanna; Kolehmainen, Jukka [DIARC-Technology Inc., Espoo (Finland); Díaz, Belén; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7075) – Chimie ParisTech (ENSCP), F-75005 Paris (France); Fenker, Martin [FEM Research Institute, Precious Metals and Metals Chemistry, D-73525 Schwäbisch Gmünd (Germany); Tóth, Lajos; Radnóczi, György [Research Centre for Natural Sciences HAS, (MTA TKK), Budapest (Hungary); Ritala, Mikko [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)

    2014-10-15

    Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al{sub 2}O{sub 3}–Ta{sub 2}O{sub 5} nanolaminate, Al{sub x}Ta{sub y}O{sub z} mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing. - Highlights: • Corrosion protection properties of ALD coatings were improved by FCAD sublayers. • The FCAD sublayer enabled control of the coating-substrate interface. • The duplex coatings offered improved sealing properties and durability in NSS. • The protective properties were maintained during immersion in a corrosive solution. • The improvements were due to a more ideal ALD growth on the homogeneous FCAD oxide.

  3. Annealing effect of thermal spike in MgO thin film prepared by cathodic vacuum arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Daoyun, E-mail: zhudy@gdut.edu.cn [Experiment Teaching Department, Guangdong University of Technology, Guangzhou 510006 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Zhao, Shoubai [School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510400 (China); Zheng, Changxi; Chen, Dihu [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); He, Zhenhui, E-mail: stshzh@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2013-12-16

    MgO films were prepared by using pulsed cathodic vacuum arc deposition technique. The substrate bias voltage was in the range of −150 to −750 V. Film structure was investigated by X-ray diffraction (XRD). The annealing effect of thermal spike produced by the impacting of energetic ions was analyzed. The calculated results showed that the lifetime of a thermal spike generated by an energetic ion with the energy of 150 eV was less than one picosecond and it was sufficient to allow Mg{sup 2+} or O{sup 2-} to move one bond length to satisfy the intrinsic stress relief in the affected volume. The MgO(200) lattice spacings of the films deposited at different bias voltages were all larger than the ideal value of 2.1056 Å. As the bias amplitude increased the lattice spacing decreased, which indicated that the compressive stress in the film was partially relieved with increasing impacting ion energy. The stress relief also could be reflected from the film orientation with bias voltage. The biaxial elastic modulus for MgO(100), MgO(110) and MgO(111) planes were calculated and they were M{sub (100)} = 199 GPa, M{sub (110)} = 335 GPa and M{sub (111)} = 340 GPa, respectively. The M values indicated that the preferred orientation will be MgO(200) due to the minimum energy configuration when the lattice strain was large. It was confirmed by the XRD results in our experiments. - Highlights: • MgO thin films with preferred orientation were obtained by CVAD technique. • Annealing effect of a thermal spike in MgO film was discussed. • Lattice spacing of MgO film decreased with the increase of bias voltage. • Film preferred orientation changed from (200) to (220) as the bias voltage increased.

  4. Study on general inverse kinematics of rotating/tilting positioner for robotic arc welding off-line programming

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Off-line programming provides an essential link between CAD and CAM, whose development will result in greater use of robotic arc welding. An arc welding system with a robot and a rotating/tilting positioner is one of the most typical workcells. The inverse kinematics of robot and positioner is the foundation of the off-line programming system. The previous researchers only focused on a special solution of the positioner inverse kinematics, which is the solution at down-hand welding position. In this paper, we introduce a method for representing welding position. Then a general algorithm of rotating/tilting positioner inverse kinematics is presented, and an approach to find the unique solution of the inverse kinematics is discussed. The simulation experiment results show that the general algorithm can improve the ability of robotic arc welding off-line programming system to program all types of welding positions.

  5. Light and short arc rubs in rotating machines: Experimental tests and modelling

    Science.gov (United States)

    Pennacchi, P.; Bachschmid, N.; Tanzi, E.

    2009-10-01

    Rotor-to-stator rub is a non-linear phenomenon which has been analyzed many times in rotordynamics literature, but very often these studies are devoted simply to highlight non-linearities, using very simple rotors, rather than to present reliable models. However, rotor-to-stator rub is actually one of the most common faults during the operation of rotating machinery. The frequency of its occurrence is increasing due to the trend of reducing the radial clearance between the seal and the rotor in modern turbine units, pumps and compressors in order to increase efficiency. Often the rub occurs between rotor and seals and the analysis of the phenomenon cannot set aside the consideration of the different relative stiffness. This paper presents some experimental results obtained by means of a test rig in which rub conditions of real machines are reproduced. In particular short arc rubs are considered and the shaft is stiffer than the obstacle. Then a model, suitable to be employed for real rotating machinery, is presented and the simulations obtained are compared with the experimental results. The model is able to reproduce the behaviour of the test rig.

  6. Investigation of micro-structure and micro-hardness properties of 304L stainless steel treated in a hot cathode arc discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Hitendra K., E-mail: hkmalik@physics.iitd.ac.in [Department of Physics, Indian Institute of Technology Delhi, New Delhi – 110016 (India); Singh, Omveer [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi – 110016 (India); Dahiya, Raj P. [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi – 110016 (India); Deenbandhu Chhotu Ram University of Science and Technology, Murthal–131039 (India)

    2015-08-28

    We have established a hot cathode arc discharge plasma system, where different stainless steel samples can be treated by monitoring the plasma parameters and nitriding parameters independently. In the present work, a mixture of 70% N{sub 2} and 30% H{sub 2} gases was fed into the plasma chamber and the treatment time and substrate temperature were optimized for treating 304L Stainless Steel samples. Various physical techniques such as x-ray diffraction, energy dispersive x-ray spectroscopy and micro-vickers hardness tester were employed to determine the structural, surface composition and surface hardness of the treated samples.

  7. Investigation of micro-structure and micro-hardness properties of 304L stainless steel treated in a hot cathode arc discharge plasma

    Science.gov (United States)

    Malik, Hitendra K.; Singh, Omveer; Dahiya, Raj P.

    2015-08-01

    We have established a hot cathode arc discharge plasma system, where different stainless steel samples can be treated by monitoring the plasma parameters and nitriding parameters independently. In the present work, a mixture of 70% N2 and 30% H2 gases was fed into the plasma chamber and the treatment time and substrate temperature were optimized for treating 304L Stainless Steel samples. Various physical techniques such as x-ray diffraction, energy dispersive x-ray spectroscopy and micro-vickers hardness tester were employed to determine the structural, surface composition and surface hardness of the treated samples.

  8. The GLAaS algorithm for portal dosimetry and quality assurance of RapidArc, an intensity modulated rotational therapy

    Directory of Open Access Journals (Sweden)

    Fogliata Antonella

    2008-09-01

    Full Text Available Abstract Background To expand and test the dosimetric procedure, known as GLAaS, for amorphous silicon detectors to the RapidArc intensity modulated arc delivery with Varian infrastructures and to test the RapidArc dosimetric reliability between calculation and delivery. Methods The GLAaS algorithm was applied and tested on a set of RapidArc fields at both low (6 MV and high (18 MV beam energies with a PV-aS1000 detector. Pilot tests for short arcs were performed on a 6 MV beam associated to a PV-aS500. RapidArc is a novel planning and delivery method in the category of intensity modulated arc therapies aiming to deliver highly modulated plans with variable MLC shapes, dose rate and gantry speed during rotation. Tests were repeated for entire (360 degrees gantry rotations on composite dose plans and for short partial arcs (of ~6 or 12 degrees to assess GLAaS and RapidArc mutual relationships on global and fine delivery scales. The gamma index concept of Low and the Modulation Index concept of Webb were applied to compare quantitatively TPS dose matrices and dose converted PV images. Results The Gamma Agreement Index computed for a Distance to Agreement of 3 mm and a Dose Difference (ΔD of 3% was, as mean ± 1 SD, 96.7 ± 1.2% at 6 MV and 94.9 ± 1.3% at 18 MV, over the field area. These findings deteriorated slightly is ΔD was reduced to 2% (93.4 ± 3.2% and 90.1 ± 3.1%, respectively and improved with ΔD = 4% (98.3 ± 0.8% and 97.3 ± 0.9%, respectively. For all tests a grid of 1 mm and the AAA photon dose calculation algorithm were applied. The spatial resolution of the PV-aS1000 is 0.392 mm/pxl. The Modulation Index for calculations resulted 17.0 ± 3.2 at 6 MV and 15.3 ± 2.7 at 18 MV while the corresponding data for measurements were: 18.5 ± 3.7 and 17.5 ± 3.7. Partial arcs findings were (for ΔD = 3%: GAI = 96.7 ± 0.9% for 6° rotations and 98.0 ± 1.1% for 12° rotations. Conclusion The GLAaS method can be considered as a valid

  9. Advanced plasma flow simulations of cathodic-arc and ferroelectric plasma sources for neutralized drift compression experiments

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2008-07-01

    Full Text Available Large-space-scale and long-time-scale plasma flow simulations are executed in order to study the spatial and temporal evolution of plasma parameters for two types of plasma sources used in the neutralized drift compression experiment (NDCX. The results help assess the charge neutralization conditions for ion beam compression experiments and can be employed in more sophisticated simulations, which previously neglected the dynamical evolution of the plasma. Three-dimensional simulations of a filtered cathodic-arc plasma source show the coupling efficiency of the plasma flow from the source to the drift region depends on geometrical factors. The nonuniform magnetic topology complicates the well-known general analytical considerations for evaluating guiding-center drifts, and particle-in-cell simulations provide a self-consistent evaluation of the physics in an otherwise challenging scenario. Plasma flow profiles of a ferroelectric plasma source demonstrate that the densities required for longitudinal compression experiments involving ion beams are provided over the drift length, and are in good agreement with measurements. Simulations involving azimuthally asymmetric plasma creation conditions show that symmetric profiles are nevertheless achieved at the time of peak on-axis plasma density. Also, the ferroelectric plasma expands upstream on the thermal expansion time scale, and therefore avoids the possibility of penetration into the acceleration gap and transport sections, where partial neutralization would increase the beam emittance. Future experiments on NDCX will investigate the transverse focusing of an axially compressing intense charge bunch to a sub-mm spot size with coincident focal planes using a strong final-focus solenoid. In order to fill a multi-tesla solenoid with the necessary high-density plasma for beam charge neutralization, the simulations predict that supersonically injected plasma from the low-field region will penetrate and

  10. Nitrogen doping for adhesion improvement of DLC film deposited on Si substrate by Filtered Cathodic Vacuum Arc (FCVA) technique

    Energy Technology Data Exchange (ETDEWEB)

    Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Supsermpol, B.; Saenphinit, N. [Western Digital Company, Ayutthaya 13160 (Thailand); Aramwit, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50202 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50202 (Thailand)

    2014-08-15

    Diamond-like carbon (DLC) films have been used in many applications due to their attractive combination of properties including chemical inertness, corrosion protection, biocompatibility, high hardness, and low wear rates. However, they still have some limitations such as high internal stresses and low toughness which lead to poor adhesion of films. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these limitations. In this study, DLC films, namely tetrahedral amorphous carbon (ta-C) and nitrogen doped tetrahedral amorphous carbon (ta-C:N) were deposited on single crystalline Si wafer substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. Film characterizations were carried out by Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), triboindenter tester and nano-scratch tester. Measurement results showed that intentionally doping with nitrogen reduced the carbon sp{sup 3} content and increased the surface roughness in comparison with that of pure ta-C films. The hardness measurement confirmed the Raman and AFM analyses that adding nitrogen in ta-C films decreased the hardness, especially with high nitrogen content. However, the nano-scratch test revealed the increasing of the critical load with nitrogen. This work, then, extended its scope to investigate the properties of double-layer ta-C films which were composed of ta-C:N interlayer of various thickness around 10–30 nm and ta-C top-layer with thickness of around 80 nm. Microstructure characterization demonstrated that a ta-C:N interlayer gradually decreased the sp{sup 3} fraction in the films and increased film roughness whenever the ta-C:N interlayer thickness increased. In this structure, the tribological property in terms of adhesion to the Si substrate was significantly improved by about 20–90%, but the mechanical property in terms of hardness was gradually degraded by about 2–10%, compared to pure ta-C film, when the ta

  11. A Rotating Arc Gap Switch and its Arc Velocity Characteristics%旋转电弧开关及其电弧运动速度特性

    Institute of Scientific and Technical Information of China (English)

    郭锐; 何俊佳; 赵纯; 陈立学; 潘坦

    2011-01-01

    为满足脉冲功率技术对闭合开关高电压、大电流、商电荷转移量、电极烧蚀小、寿命长的要求,设计了一种轴向磁场控制的旋转电弧开关.利用有限元软件分析开关间隙中驱弧磁场的位形及大小,得到间隙中磁感应强度与开关结构参数及电流大小的关系.采用B-dot探针测量电弧的旋转速度.实验电源为时序放电回路,在开关上得到近似梯形状的电流波形,实验中电流为18~72 kA,磁感应强度为0.104~0.628T.通过改变上下线圈的匝数,得到在不同驱弧磁场下电弧的运动速度,并与其他旋转电弧开关的运动速度进行比较.对实验数据进行拟合,可知电弧运动速度与间隙中的轴向磁感应强度大小成指数关系.该关系表明,所设计的开关中,电弧运动速度可以由间隙中的驱弧磁场惟一确定,这与外部磁场驱弧方式相比有很大的区别.%A rotating arc gap switch controlled by axial magnetic field was designed and built to meet the needs of high voltage, high current, large charge transfers, slight electrode erosion and long lifetime. The magnetic field distribution in the gap was analyzed by ANSYS. The relationship between magnetic flux density in the gap and switch geometry and arc current was obtained. B-dot probes were employed to measure the arc rotating velocity. The current was trapezoid-like waveform and generated by a time-sequence discharge power supply. The current was in the range of 18~72 kA and magnetic flux density was 0.104~0.628T. The arc velocity in different magnitude of magnetic flux density was obtained by changing the coil number and the results were compared with other rotating arc gap switches. The arc velocity has exponent relation to the axial magnetic field by fitting the experimental data. The results show that the arc velocity in this kind of switch is individually determined by axial magnetic field. It is significant different from other rotating arc

  12. Earth rotation and GNSS orbits from one-day and three-day arcs

    Science.gov (United States)

    Lutz, Simon; Schaer, Stefan; Dach, Rolf; Beutler, Gerhard; Steigenberger, Peter; Meindl, Michael; Jäggi, Adrian

    2014-05-01

    The Center for Orbit Determination in Europe (CODE) is one of the analysis centers of the International GNSS Service (IGS). It is estimating satellite orbits and consistent sets of Earth rotation parameters (ERPs) for the final, rapid, and ultra-rapid product lines of the IGS. The solutions are derived from a combined multi-system (GPS and GLONASS) analysis of the GNSS tracking data. Since September 2012 two series of final solutions are operationally generated and submitted to the IGS: the first is based on the observations from exactly one day (requirement of the IGS) and the second stacks the one-day normal equations of three consecutive days to get orbital arcs and piecewise linear Earth rotation parameters which are continuous at the boundaries of the middle day. The same two solution types were produced for the second reprocessing campaign of the IGS (covering the interval from 1994 to the end of 2013; GLONASS starts in 2002). The estimation of the polar motion rates reveals serious deficiencies in the case of the one-day solutions (probably due to interferences with the sub-daily ERPs). Suspicious signatures in the time series of the estimated parameters not visible in the three-day solutions are systematically disturbing the results of the one-day solutions. Artifacts with periods typical for the GLONASS constellation are clearly visible in the one-day solutions, but to a much lesser extent in the three-day solutions. This becomes even more evident in an alternative series generated as consistent (even regarding the station selection) GPS- and GLONASS-only products over four years (2007-2011).

  13. Properties of low-temperature deposited ZnO thin films prepared by cathodic vacuum arc technology on different flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Cheng-Tang [Department of Mechanical and Electron-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung City 804, Taiwan (China); Yang, Ru-Yuan, E-mail: ryyang@mail.npust.edu.tw [Graduate Institute of Materials Engineering, National Pingtung University of Science and Technology, Pingtung County 912, Taiwan (China); Weng, Min-Hang [Medical Devices and Opto-Electronics Equipment Department, Metal Industries Research and Development Center, Kaohsiung City 821, Taiwan (China); Huang, Chien-Wei [Department of Mechanical and Electron-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung City 804, Taiwan (China)

    2013-07-31

    Un-doped zinc oxide (ZnO) films were deposited on three different substrates (polyethylene terephthalate (PET), polyvinyl butyral (PVB) and polyimide (PI)) at a low temperature (< 75 °C) by cathode vacuum arc deposition. The microstructure, optical and electrical properties of the deposited films were investigated and discussed. All the deposited films reveal a preferred orientation with the c-axis perpendicular to the substrate, and an average transmittance of over 85% in the visible region. The calculated optical band gaps are around 2.6, 3.14 and 3.18 eV, respectively, for the ZnO films deposited on the PI, PVB and PET substrates. The lowest resistivity and the highest Hall mobility are 5.31 × 10{sup −3} Ω-cm and 15.16 cm{sup 2}/V-s for the ZnO film deposited on the PET substrate. - Highlights: • Polyethylene terephthalate, polyvinyl butyral and polyimide were used as substrates. • ZnO films were prepared by cathodic arc plasma deposition. • ZnO films have different properties due to different substrates. • The microstructure control of ZnO film on polymer substrate is important.

  14. Structure and properties of Mo-containing diamond-like carbon films produced by ion source assisted cathodic arc ion-plating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.L. [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 China (China); Wang, R.Y. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Yan, S.J.; Zhang, R. [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 China (China); Yang, B. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Zhang, Z.D.; Huang, Z.H. [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 China (China); Fu, D.J., E-mail: djfu@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 China (China)

    2013-12-01

    Ion source assisted cathodic arc ion-plating was used to synthesize molybdenum containing diamond-like carbon films. The element of molybdenum is uniformly distributed in our sample as analyzed by Rutherford backscattering spectroscopy. The surface morphology of the films was analyzed by scanning electron microscope and atomic force microscope. The structure and bond state of the molybdenum containing diamond-like carbon films were characterized by X-ray diffraction, high resolution transmission electron microscopy, Raman spectra, and X-ray photoelectron spectroscopy. The Mo content in the films was controlled by varying of the acetylene gas flow rates. The root-mean square roughness of the as-deposited sample was found in the range of 1.5 nm. The hardness of 35 GPa has been achieved at the optimum conditions of synthesis. This can be attributed to formation multilayer structure during deposition process and the formation of hard molybdenum carbide phase with C=Mo bonding. The results show that ion source assisted cathodic arc ion-plating is an effective technique to fabricate metal-containing carbon films with controlled metal contents.

  15. Effect of substrate bias in nitrogen incorporated amorphous carbon films with embedded nanoparticles deposited by filtered cathodic jet carbon arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Amorphous and Microcrystalline Silicon Solar Cell Group, Physics of Energy Harvesting Division, National Physical Laboratory (C.S.I.R.), Dr. K.S. Krishnan Road, New Delhi-110012 (India); Kumar, Sushil; Ishpal,; Srivastava, A.K.; Chouksey, Abhilasha; Tripathi, R.K.; Basu, A. [Amorphous and Microcrystalline Silicon Solar Cell Group, Physics of Energy Harvesting Division, National Physical Laboratory (C.S.I.R.), Dr. K.S. Krishnan Road, New Delhi-110012 (India)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer a-C: N films having nanoparticles were deposited by filtered cathodic jet carbon arc (FCJCA) technique. Black-Right-Pointing-Pointer The effect of negative substrate bias on the properties of a-C: N films embedded with nanoparticles have been studied. Black-Right-Pointing-Pointer The properties of a-C: N films deposited by FCJCA technique have been compared with ta-C: N films deposited by FCVA process. - Abstract: The properties of nitrogen incorporated amorphous carbon (a-C: N) films with embedded nanoparticles, deposited using a filtered cathodic jet carbon arc technique, are reported. X-ray diffraction, high resolution transmission electron microscope and Raman spectroscopy measurements reveal an amorphous structure, but on closer examination the presence of clusters of nanocarbon single crystals with d-spacing close to diamond cubic-phase have also been identified. The effect of substrate bias on the microstructure, conductivity, activation energy, optical band gap, optical constants, residual stress, hardness, elastic modulus, plastic index parameter, percentage elastic recovery and density of states of a-C: N films have been studied and the properties obtained are found to depend on the substrate bias.

  16. Unified model to the Tungsten inert Gas welding process including the cathode, the plasma and the anode; Modele couple cathode-plasma-piece en vue de la simulation du procede de soudage a l'arc TIG

    Energy Technology Data Exchange (ETDEWEB)

    Brochard, M.

    2009-06-15

    During this work, a 2D axially symmetric model of a TIG arc welding process had been developed in order to predict for given welding parameters, the needed variables for a designer of welded assembly: the heat input on the work piece, the weld pool geometry,... The developed model, using the Cast3M finite elements software, deals with the physical phenomena acting in each part of the process: the cathode, the plasma, the work piece with a weld pool, and the interfaces between these parts. To solve this model, the thermohydraulics equations are coupled with the electromagnetic equations that are calculated in part using the least squares finite element method. The beginning of the model validation consisted in comparing the results obtained with the ones available in the scientific literature. Thus, this step points out the action of each force in the weld pool, the contribution of each heat flux in the energy balance. Finally, to validate the model predictiveness, experimental and numerical sensitivity analyses were conducted using a design of experiments approach. The effects of the process current, the arc gap and the electrode tip angle on the weld pool geometry and the energy transferred to the work piece and the arc efficiency were studied. The good agreement obtained by the developed model for these outputs shows the good reproduction of the process physics. (author)

  17. Enhancing Micro-Cathode Arc Thruster (muCAT) Plasma Generation to Analyze Magnetic Field Angle Effects on Sheath Formation in Hall Thrusters

    Science.gov (United States)

    Lukas, Joseph Nicholas

    Using a Delta IV or Atlas V launch vehicle to send a payload into Low Earth Orbit can cost between 13,000 and 14,000 per kilogram. With payloads that utilize a propulsion system, maximizing the efficiency of that propulsion system would not only be financially beneficial, but could also increase the range of possible missions and allow for a longer mission lifetime. This dissertation looks into efficiency increases in the Micro-Cathode Arc Thruster (muCAT) and Hall Thruster. The muCAT is an electric propulsion device that ablates solid cathode material, through an electrical arc discharge, to create plasma and ultimately produce thrust. About 90% of the arc discharge current is conducted by electrons, which go toward heating the anode and contribute very little to thrust, with only the remaining 10% going toward thrust in the form of ion current. I will discuss the results of an experiment in which electron heating on a low melting point anode was shown to increase ion current, which theoretically should increase thrust levels at low frequencies. Another feature of the muCAT is the use of an external magnetic solenoid which increases thrust, ion current, and causes uniform cathode erosion. An experiment has shown that efficiency can also be increased by removing the external magnetic field power supply and, instead, utilizing the residual arc current to power the magnetic solenoid. A Hall Thruster is a type of electric propulsion device that accelerates ions across an electric potential between an anode and magnetically trapped electrons. The limiting factor in Hall Thruster operation is the lifetime of the wall material. During operation, a positively charged layer forms over the surface of the walls, known as a plasma sheath, which contributes to wall erosion. Therefore, by reducing or eliminating the sheath layer, Hall Thruster operational lifetime can increase. Computational modeling has shown that large magnetic field angles and large perpendicular electric

  18. Influence of deposition temperature and bias voltage on the crystalline phase of Er{sub 2}O{sub 3} thin films deposited by filtered cathodic arc

    Energy Technology Data Exchange (ETDEWEB)

    Adelhelm, Christoph, E-mail: christoph.adelhelm@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik, Materials Research, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany); Pickert, Thomas [Max-Planck-Institut fuer Plasmaphysik, Materials Research, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany); Koch, Freimut, E-mail: freimut.koch@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik, Materials Research, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany); Balden, Martin; Jahn, Stephan [Max-Planck-Institut fuer Plasmaphysik, Materials Research, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany); Rinke, Monika [Forschungszentrum Karlsruhe, Institute for Materials Research I, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Maier, Hans [Max-Planck-Institut fuer Plasmaphysik, Materials Research, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany)

    2011-10-01

    Er{sub 2}O{sub 3} thin films on Eurofer steel substrates were produced by a filtered cathodic arc device, varying the substrate temperature (RT - 700 deg. C) and sample bias (0 to -450 V). The crystallographic phase was analyzed by X-ray diffraction and Raman spectroscopy. Deposition at {>=}600 deg. C without bias lead to solely formation of the cubic Er{sub 2}O{sub 3} phase. Thin films of the uncommon, monoclinic B-phase were prepared with a negative bias voltage of {>=}100 V at RT, and at temperatures {<=}500 deg. C for -250 V bias. The B-phase films exhibit a strongly textured film structure. Residual stress measurements show high compressive stress for B-phase films deposited at RT.

  19. Characterization of SiC in DLC/a-Si films prepared by pulsed filtered cathodic arc using Raman spectroscopy and XPS

    Energy Technology Data Exchange (ETDEWEB)

    Srisang, C. [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Western Digital (Thailand) Company Limited, Ayuthaya 13160 (Thailand); Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400 (Thailand); Asanithi, P. [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Siangchaew, K. [Western Digital (Thailand) Company Limited, Ayuthaya 13160 (Thailand); Pokaipisit, A. [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400 (Thailand); Limsuwan, P., E-mail: opticslaser@yahoo.com [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400 (Thailand)

    2012-05-15

    DLC/a-Si films were deposited on germanium substrates. a-Si film was initially deposited as a seed layer on the substrate using DC magnetron sputtering. DLC film was then deposited on the a-Si layer via a pulsed filtered cathodic arc (PFCA) system. In situ ellipsometry was used to monitor the thicknesses of the growth films, allowing a precise control over the a-Si and DLC thicknesses of 6 and 9 nm, respectively. It was found that carbon atoms implanting on a-Si layer act not only as a carbon source for DLC formation, but also as a source for SiC formation. The Raman peak positions at 796 cm{sup -1} and 972 cm{sup -1} corresponded to the LO and TO phonon modes of SiC, respectively, were observed. The results were also confirmed using TEM, XPS binding energy and XPS depth profile analysis.

  20. An improved rotating disc cathode cell for electrodeposition of actinides. The case of plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Becerril, V.A.; Tejera, R.A. (Inst. Nacional de Investigaciones Nucleares, Mexico City (Mexico)); Meas, V.Y. (Univ. Autonoma Metropolitana Iztapalapa, Area de Electroquimica, Mexico City (Mexico) CIDETEQ, Queretaro (Mexico)); Ozil, P. (CREMGP, ENSEEG, 38 - Saint Martin d' Heres (France))

    1993-05-01

    An electrolytic rotating disc electrode cell for electrodeposition of very thin and uniform plutonium (Pu) films with consistently high recoveries, was designed. It was made emphasizing the hydrodynamic conditions to be fulfilled by the device in agreement with the rotating disc electrode (RDE) model. The system was characterized by hydrodynamical parameters. The electrodeposition technique will be discussed elsewhere. The deposition yield was 97.5[+-]2.5%. The high quality of the very thin and uniform Pu deposits allowed one to obtain very suitable Pu sources (FWHM=10.8 keV, LM=100 and uniformity =10%) for alpha spectroscopy and for alpha emission probabilities and isotopic ratios studies. (orig.).

  1. Dense and high-stability Ti2AlN MAX phase coatings prepared by the combined cathodic arc/sputter technique

    Science.gov (United States)

    Wang, Zhenyu; Liu, Jingzhou; Wang, Li; Li, Xiaowei; Ke, Peiling; Wang, Aiying

    2017-02-01

    Ti2AlN belongs to a family of ternary nano-laminate alloys known as the MAX phases, which exhibit a unique combination of metallic and ceramic properties. In the present work, the dense and high-stability Ti2AlN coating has been successfully prepared through the combined cathodic arc/sputter deposition, followed by heat post-treatment. It was found that the as-deposited Ti-Al-N coating behaved a multilayer structure, where (Ti, N)-rich layer and Al-rich layer grew alternately, with a mixed phase constitution of TiN and TiAlx. After annealing at 800 °C under vacuum condition for 1.5 h, although the multilayer structure still was found, part of multilayer interfaces became indistinct and disappeared. In particular, the thickness of the Al-rich layer decreased in contrast to that of as-deposited coating due to the inner diffusion of the Al element. Moreover, the Ti2AlN MAX phase emerged as the major phase in the annealed coatings and its formation mechanism was also discussed in this study. The vacuum thermal analysis indicated that the formed Ti2AlN MAX phase exhibited a high-stability, which was mainly benefited from the large thickness and the dense structure. This advanced technique based on the combined cathodic arc/sputter method could be extended to deposit other MAX phase coatings with tailored high performance like good thermal stability, high corrosion and oxidation resistance etc. for the next protective coating materials.

  2. Structural, nanomechanical and variable range hopping conduction behavior of nanocrystalline carbon thin films deposited by the ambient environment assisted filtered cathodic jet carbon arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Rawal, Ishpal; Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Kumar, Mahesh [Ultrafast Opto-Electronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India)

    2015-04-15

    Highlights: • Nanocrystalline carbon thin films are grown by filtered cathodic jet carbon arc process. • Effect of gaseous environment on the properties of carbon films has been studied. • The structural and nanomechanical properties of carbon thin films have been studied. • The VRH conduction behavior in nanocrystalline carbon thin films has been studied. - Abstract: This paper reports the deposition and characterization of nanocrystalline carbon thin films by filtered cathodic jet carbon arc technique assisted with three different gaseous environments of helium, nitrogen and hydrogen. All the films are nanocrystalline in nature as observed from the high resolution transmission electron microscopic (HRTEM) measurements, which suggests that the nanocrystallites of size ∼10–50 nm are embedded though out the amorphous matrix. X-ray photoelectron spectroscopic studies suggest that the film deposited under the nitrogen gaseous environment has the highest sp{sup 3}/sp{sup 2} ratio accompanied with the highest hardness of ∼18.34 GPa observed from the nanoindentation technique. The film deposited under the helium gaseous environment has the highest ratio of the area under the Raman D peak to G peak (A{sub D}/A{sub G}) and the highest conductivity (∼2.23 S/cm) at room temperature, whereas, the film deposited under the hydrogen environment has the lowest conductivity value (2.27 × 10{sup −7} S/cm). The temperature dependent dc conduction behavior of all the nanocrystalline carbon thin films has been analyzed in the light of Mott’s variable range hopping (VRH) conduction mechanism and observed that all the films obey three dimension VRH conduction mechanism for the charge transport.

  3. Seed layer stimulated growth of crystalline high Al containing (Al,Cr){sub 2}O{sub 3} coatings deposited by cathodic arc evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Pohler, M., E-mail: markus.pohler@stud.unileoben.ac.at [Christian Doppler Laboratory for Advanced Hard Coatings at the Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Straße 18, A-8700 Leoben (Austria); Franz, R. [Christian Doppler Laboratory for Advanced Hard Coatings at the Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Straße 18, A-8700 Leoben (Austria); Ramm, J. [OC Oerlikon Balzers AG, Iramali 18, 9469 Balzers (Liechtenstein); Polcik, P. [PLANSEE Composite Materials GmbH, Siebenbürgerstraße 23, 86983 Lechbruck am See (Germany); Mitterer, C. [Christian Doppler Laboratory for Advanced Hard Coatings at the Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Straße 18, A-8700 Leoben (Austria)

    2014-01-01

    Single layer and dual layer (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} coatings were synthesised by cathodic arc evaporation with different Al contents to study their growth characteristics. It was demonstrated that variations in the Al content, the energy of incident particles and the coating thickness control the crystallinity and the coating texture. Analysis by X-ray diffraction revealed a distinct (110) out of plane orientation after transition from a fine grained nucleation zone to a columnar growth mode. Furthermore, the impact of (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} seed layers with x = 0.25 and 0.5 on the growth of (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} top layers with x = 0.7 and 0.85 was evaluated in detail. According to X-ray diffraction and transmission electron microscopy, the development of the corundum-type crystal structure of the top layer was promoted by local epitaxy if the low Al containing seed layer exhibited a pronounced columnar structure. In this way, crystalline corundum-type coatings with an Al content up to x = 0.85 were obtained. - Highlights: • Industrial scale cathodic arc deposition of corundum type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} coatings • Discussion of the growth characteristics for different Al/Cr ratios • Characterisation of growth regimes in dual layer coatings • Template stimulated growth of crystalline corundum-type (Al{sub 0.85}Cr{sub 0.15}){sub 2}O{sub 3} coatings • Influence of bias voltage and seed layer thickness on the template effect.

  4. Experimental investigation and numerical simulation of triggered vacuum arc behavior under TMF/RMF-AMF contact

    Science.gov (United States)

    Wang, Lijun; Deng, Jie; Qin, Kang; Zhang, Xiao; Jia, Shenli

    2016-06-01

    A series of triggering experiments was carried out to investigate the characteristics of vacuum arc controlled by TMF/RMF-AMF contacts. During all the experiments, the current ranged from 5-20 kA (rms) and both the arc appearance and behavior of cathode spots were captured by high-speed camera with corresponding arc current and arc voltage. A 3D steady magnetohydrodynamics (MHD) model was built to simulate and analyze the vacuum arc behavior under TMF/RMF-AMF contacts, and arc plasma parameters were calculated based on the above model. The experimental results showed that arc deflection was visible under both low and high current. Under high current, arc core formed, which meant the arc contracted significantly. In addition, the anode became much more active under high current. The behavior of the cathode spots showed that they split themselves into other new cathode spots. Under high current, the bulk of the spots rotated along a clockwise direction on a transverse magnetic field (TMF) plate, which caused much noise and oscillation in the arc voltage. The simulation results show that ions are likely to gather on the branches of the TMF plate on the anode plane, as a result of the effects between the electromagnetic force and pressure gradient of the arc plasma. The current contracts in the center of the TMF plate on the cathode which was due to the thin connecting rod there. The anode contraction of the current is caused by the Hall effect. Ions move along a clockwise direction on the TMF plate, which is driven by Ampere force. The current contraction resulted in significant melting in the center of the cathode surface while the other region suffered from uniform melting. The melting caused by the anode contraction is more significant than that of the cathode.

  5. The optimization of molybdenum back contact films for Cu(In,Ga)Se{sub 2} solar cells by the cathodic arc ion plating method

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yong Ki, E-mail: choyk@kitech.re.kr [Heat Treatment and Surface Engineering R and D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Gang Sam; Song, Young Sik; Lim, Tae Hong [Heat Treatment and Surface Engineering R and D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Jung, Donggeun [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2013-12-02

    Molybdenum back contact films for Cu(In,Ga)Se{sub 2} (CIGS) solar cells have been deposited using DC magnetron sputtering methods. The electronic pathway properties of the molybdenum film have been highly dependent on the working gas pressure in magnetron sputtering, which should be carefully controlled to obtain high conductivity and adhesion. A coating method, cathodic arc ion plating, was used for molybdenum back contact electrode fabrication. The aim of this work was to find a metallization method for CIGS solar cells, which has less sensitivity on the working pressure. The resistivity, grain size, growth structures, stress, and efficiency of the films in CIGS solar cells were investigated. The results reveal that the growth structures of the molybdenum films mainly affect the conductivity. The lowest electrical resistivity of the ion-plated molybdenum films was 6.9 μΩ-cm at a pressure of 0.7 Pa. The electrical resistivity variation showed a gently increasing slope with linearity under a working gas pressure of 13.3 Pa. However, a high value of the residual stress of over 1.3 GPa was measured. In order to reduce stress, titanium film was selected as the buffer layer material, and the back contact films were optimized by double-layer coating of two kinds of hetero-materials with arc ion plating. CIGS solar cells prepared molybdenum films to measure the efficiency and to examine the effects of the back contact electrode. The resistivity, grain size, and surface morphology of molybdenum films were measured by four-point probe, X-ray diffraction, and a scanning electron microscope. The residual stress of the films was calculated from differences in bending curvatures measured using a laser beam. - Highlights: • Molybdenum back contact films for Cu(In,Ga)Se{sub 2} solar cells were prepared by the cathodic arc ion plating. • The lowest electrical resistivity of molybdenum film was 6.9 μΩ-cm. • Titanium buffer layer reduced the compressive residual stress

  6. Particle image velocimetry analysis of the flow around circular cylinder induced by arc discharge rotating in magnetic field

    Science.gov (United States)

    Munhoz, D. S.; Bityurin, V. A.; Klimov, A. I.; Moralev, I. A.

    2016-11-01

    An experimental study of the flow around a circular cylinder model with magnetohydrodynamic (MHD) actuator was carried out in subsonic wind tunnels (M high frequency and pulsed-periodic) electrical discharge was used in this MHD actuator. This intense pulsed-periodic discharge had the following characteristics: voltage amplitude up to 15 kV, current amplitude up to 16 A and frequency up to 1 kHz. Permanent magnets with an induction of B = 0.1 T on the model surface were placed inside the cylindrical model. Annular electrodes were situated on the surface of the cylindrical model. The Lorentz force causes the rotation of the electric arc on the model surface. In turn, the movement of the arc discharge induces the rotation of the gas near the surface of the model. In this experiment were carried out the measurement of the flow velocity profile near the surface of the model on the following operational modes: with plasma and without plasma. A parametric study of the aerodynamic performance of the model was fulfilled with respect to the discharge parameters and the flow velocity. To measure the velocity profile was used particle image velocimetry method.

  7. SOFC Cathode Mechanisms

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Zachau-Christiansen, Birgit; Bay, Lasse

    1996-01-01

    The transient response of SOFC oxygen cathodes shows a characteristic inductive hysteresis and correspondingly the impedance diagram combines one or two capacitive arcs with a low frequency inductive arc. These features are discussed on the basis of a three step reaction sequence taken from...

  8. High-rate and low-temperature growth of ZnO:Ga thin films by steered cathodic arc plasma evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chih-Hao [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China); Wang, Wei-Lin [Nano Materials Center, ITRI South, Industrial Technology Research Institute, Tainan, Taiwan (China); Hwang, Weng-Sing, E-mail: wshwang@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer ZnO:Ga (GZO) films are deposited on glass by steered cathodic arc plasma evaporation. Black-Right-Pointing-Pointer GZO films are grown at a high growth rate (220 nm/min) and low temperature (120 Degree-Sign C). Black-Right-Pointing-Pointer Films with low strain show low resistivity and high transparency. Black-Right-Pointing-Pointer Droplet size is reduced when a high-melting-point GZO ceramic target is adopted. Black-Right-Pointing-Pointer Metal-like conductivity indicates GZO films became degenerated semiconductors. - Abstract: Ga-doped ZnO (GZO) thin films with various thicknesses (120-520 nm) are deposited on the glass substrate at a high growth rate of 220 nm/min and a low temperature of 120 Degree-Sign C by a steered cathodic arc plasma evaporation (steered CAPE). The growth mechanism, microstructure, residual stress, surface morphology, electrical and optical properties, chemical states, electron transport behaviors and thickness effect of the GZO films are investigated. The film stress is gradually relaxed from -0.516 GPa to -0.090 GPa with thickness increasing. Transmission electron microscopy (TEM) images show that the GZO microstructure consists of c-axis textured columnar grains accompanied by some embedded nanodroplets. The droplet size is significantly reduced when a high-melting-point (1975 Degree-Sign C) GZO ceramic target is adopted. High-resolution TEM image shows the GZO crystallites nucleated directly onto the amorphous substrate. The electrical properties improve with increasing thickness. The lowest resistivity (4.72 Multiplication-Sign 10{sup -4} {Omega} cm) is achieved at the thickness of 520 nm, with a corresponding transmittance of 89% in the visible region. Temperature-dependent resistivity measurements show that metal-semiconductor transition temperature increases from 136 K to 225 K when decreasing the thickness, which is due to the increasing the localized states caused by the defects and

  9. Growth feature of ionic nitrogen doped CN{sub x} bilayer films with Ti and TiN interlayer by pulse cathode arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Bing, E-mail: zhoubing@tyut.edu.cn [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Zhubo [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Piliptsou, D.G., E-mail: pdg_@mail.ru [International Chinese–Belarusian Scientific Laboratory on Vacuum-Plasma Technology, Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Nanjing University of Science and Technology, Nanjing 210094 (China); Rogachev, A.V. [International Chinese–Belarusian Scientific Laboratory on Vacuum-Plasma Technology, Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Nanjing University of Science and Technology, Nanjing 210094 (China); Yu, Shengwang; Wu, Yanxia; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Rudenkov, A.S. [International Chinese–Belarusian Scientific Laboratory on Vacuum-Plasma Technology, Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Nanjing University of Science and Technology, Nanjing 210094 (China)

    2016-01-15

    Graphical abstract: - Highlights: • Ti/ and TiN/CN{sub x} (N{sup +}) bilayers are prepared at various frequencies by pulse cathode arc. • Ti interlayer facilitates the introduction of N atoms into the CN{sub x} (N{sup +}) films. • The most N-sp{sup 2}C bonds (mainly graphite-like N) present in the TiN/CN{sub x} (N{sup +}, 3 Hz) film. • Ti/CN{sub x} (N{sup +}, 3 Hz) bilayer possesses small size and disordering of Csp{sup 2} clusters. • The higher hardness and the lower stress presents in the TiN/CN{sub x} (N{sup +}, 10 Hz) bilayer. - Abstract: Using nano-scaled Ti and TiN as interlayer, ionic nitrogen doped carbon (CN{sub x} (N{sup +})) bilayer films were prepared at various pulse frequencies by cathode arc technique. Elemental distribution at the interface, bonding compositions, microstructure, and mechanical properties of CN{sub x} (N{sup +}) bilayer films were investigated in dependence of interlayer and pulse frequency by Auger electron spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, nanoindentation, and surface profilometer. The results showed that the diffusion extent of C atoms at the interface of CN{sub x} (N{sup +}) bilayers is higher than for the α-C and CN{sub x} (N{sub 2}) bilayers with the same interlayer. Nitrogen atoms could diffuse throughout the pre-deposited Ti and TiN layers into the Si substrate for all CN{sub x} (N{sup +}) bilayers. Ti interlayer facilitates the introduction of N atoms into the CN{sub x} (N{sup +}) films and exhibits a certain catalytic effect on the coordination of N atoms with sp{sup 2}- and sp{sup 3}-C binding. More nitrogenated and intense CN bonding configurations (mainly graphite-like N) form in the TiN/CN{sub x} (N{sup +}) bilayer. Ti/CN{sub x} (N{sup +}) bilayer prepared at low frequency possesses small size and disordering of Csp{sup 2} clusters but TiN interlayer weakens the formation of Csp{sup 2} bonding and increases the disordering of Csp{sup 2} clusters in the films. The residual

  10. Phase transitions of doped carbon in CrCN coatings with modified mechanical and tribological properties via filtered cathodic vacuum arc deposition

    Science.gov (United States)

    Guan, J. J.; Wang, H. Q.; Qin, L. Z.; Liao, B.; Liang, H.; Li, B.

    2017-04-01

    The CrCN coatings were fabricated onto Si (1 1 1) wafers and SUS304 stainless steel plates using filtered cathodic vacuum arc deposition (FCVAD) technique under different flow ratios of N2/C2H2 gas mixture. The morphology, crystalline structure and chemical composition of the coatings were characterized. It was found that the grain size reduce with increasing carbon content, which makes the CrCN coatings refined and smooth. The quasi-one-dimensional carbolite phase was also found in CrN host lattice with C2H2 content ranging from 5% to 20%, and it will be evolved into amorphous carbon and amorphous CNx phases as C2H2 content exceeds 20%. Moreover, we examined the mechanical and tribological properties of the CrCN coatings, and the experimental results confirmed that the friction coefficient of the coatings descend to the lowest value as 0.39 with 30% C2H2 content, due to the graphite (sp2 Csbnd C) phase embed in CrN host lattice; while the chromium carbon (Cr3C2) and diamond (sp3 Csbnd C) phases may give rise to the increase of the coating hardness with the highest value at 23.97 GPa under 20% C2H2 content.

  11. Effect of pulsed bias on the properties of ZrN/TiZrN films deposited by a cathodic vacuum arc

    Institute of Scientific and Technical Information of China (English)

    Zhang Guo-Ping; Wang Xing-Quan; Lü Guo-Hua; Zhou Lan; Huang Jun; Chen Wei; Yang Si-Ze

    2013-01-01

    .ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias (from 0 to-800 V),using Ti and Zr plasma flows in residual N2 atmosphere,combined with ion bombardment of sample surfaces.The effect of pulsed bias on the structure and properties of films is investigated.Microstructure of the coating is analyzed by X-ray diffraction (XRD),and scanning electron microscopy (SEM).In addition,nanohardness,Young's modulus,and scratch tests are performed.The experimental results show that the films exhibit a nanoscale multilayer structure consisting of TiZrN and ZrN phases.Solid solutions are formed for component TiZrN films.The dominant preferred orientation of TiZrN films is (111) and (220).At a pulsed bias of-200 V,the nanohardness and the adhesion strength of the ZrN/TiZrN multilayer reach a maximum of 38 GPa,and 78 N,respectively.The ZrN/TiZrN multilayer demonstrates an enhanced nanohardness compared with binary TiN and ZrN films deposited under equivalent conditions.

  12. Effect of modulation periods on the microstructure and mechanical properties of DLC/TiC multilayer films deposited by filtered cathodic vacuum arc method

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhaoying [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Pangang Group Research Institute Co., Ltd., Panzhihua 617000, Sichuan (China); Sun, H. [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Leng, Y.X., E-mail: yxleng@263.net [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Li, Xueyuan; Yang, Wenmao [Institute of Mechanical Manufacturing Technology, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Huang, N. [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China)

    2015-02-15

    Highlights: • DLC/TiC multilayer films with different modulation periods at same modulation ratio 1:1 were deposited by FCVA. • The residual stress of DLC/TiC multilayer films decreases with the modulation periods decrease. • The hardness of the multilayer DLC films decreases with modulation periods increasing. - Abstract: The high stress of diamond-like carbon (DLC) film limits its thickness and adhesion on substrate. Multilayer structure is one approach to overcome this disadvantage. In this paper, the DLC/TiC multilayer films with different modulation periods (80 nm, 106 nm or 160 nm) at same modulation ratio of 1:1 were deposited on Si(1 0 0) wafer and Ti-6Al-4V substrate by filtered cathodic vacuum arc (FCVA) technology. X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindention and wear test were employed to investigate the effect of modulation periods on the microstructure and mechanical properties of the multilayer films. The results showed that the residual stress of the DLC/TiC multilayer films could be effectively reduced and the residual stress decreased with the modulation periods decreasing. The hardness of the DLC/TiC multilayer films increased with modulation periods decreasing. The DLC/TiC multilayer film with modulation period of 106 nm had the best wear resistance due to the good combination of hardness, ductility and low compressive stress.

  13. The study of micro-arc discharges during cathodic plasma electrolysis of refractory metals using the spectral line shape of Na I lines

    Science.gov (United States)

    Jovović, Jovica; Stojadinović, Stevan; Tadić, Nenad; Vasilić, Rastko; Šišović, Nikola M.

    2016-03-01

    The micro-arc discharges during cathodic plasma electrolysis of refractory metals (Zr, Ti, Ta) are studied by means of optical emission spectroscopy. The fitting procedure based on three mutually shifted profiles is developed to analyze the complex line shape of Na I 568.64 nm and 615.86 nm doublets. Each profile includes effects of instrumental, Doppler, Stark, van der Waals and resonance broadening. The results show the existence of three discharge zones with electron number density values Ne1=7× 1014 \\text{cm}-3 , Ne2=(0.5\\text{--}1)× 1016 \\text{cm}-3 and Ne3= (1.5\\text{--}2.8)× 1016 \\text{cm}-3 while those of sodium ground-state atoms are Ng1=1.4×1017 \\text{cm}-3 , Ng2=3.6×1017 \\text{cm}-3 and Ng3=(1.7\\text{--}3.7)×1018 \\text{cm}-3 .

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

    Directory of Open Access Journals (Sweden)

    Chien-Wei Huang

    2016-01-01

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

  15. 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.

  16. Influence of pulsed substrate bias on the structure and properties of Ti-Al-N films deposited by cathodic vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, G.P., E-mail: princeterry@163.com [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Gao, G.J. [Changchun University of Science and Technology, College of Science, Changchun 130000 (China); Wang, X.Q.; Lv, G.H.; Zhou, L.; Chen, H.; Pang, H.; Yang, S.Z. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

    2012-07-15

    Ti-Al-N films were deposited by cathodic vacuum arc (CVA) technique in N{sub 2} atmosphere with different pulsed substrate bias. The influence of pulsed substrate bias (0 to -800 V) on the deposition rate, surface morphology, crystal structure, and mechanical properties of the Ti-Al-N films were systematically investigated. Increasing pulsed bias voltage resulted in the decrease of deposition rate but the increase of surface roughness. It was found that there was a strong correlation between the pulsed bias and film structure. All the films studied in this paper were composed of TiN, AlN, and Ti-Al-N ternary phases. The grains changed from equiaxial to columnar and exhibited preferred orientation when the pulsed bias increased. With the increase of pulsed bias voltage, the atomic ratio of Ti to Al element increased gradually, while the N to (Ti + Al) ratio decreased. The composite films present an enhanced nanohardness compared with binary TiN and ZrN films. The film deposited with pulsed bias of -200 V possessed the maximum scratch critical load and nanohardness. The minimum friction coefficient with pulsed bias of -300 V was obtained.

  17. Effect of Silane Flow Rate on Structure and Corrosion Resistance of Ti-Si-N Thin Films Deposited by a Hybrid Cathodic Arc and Chemical Vapour Process

    Institute of Scientific and Technical Information of China (English)

    YIN Long-Cheng; LUAN Sen; LV Guo-Hua; WANG Xing-Quan; HUANG Jun; JIN Hui; FENG Ke-Cheng; YANG Si-Ze

    2008-01-01

    Ti-Si-N thin films with different silicon contents are deposited by a cathodic arc technique in an Ar+N2+SiH4mixture atmosphere. With the increase of silane flow rate, the content of silicon in the Ti-Si-N films varies from2.0 at. % to 12.2 at.%. Meanwhile, the cross-sectional morphology of these films changes from an apparent columnar microstructure to a dense fine-grained structure. The x-ray diffractometer (XRD) and x-ray photoelectron spectroscopy (XPS) results show that the Ti-Si-N film consists of TiN crystallites and SiNx amorphous phase.The corrosion resistance is improved with the increase of silane flow rate. Growth defects in the films produced play a key role in the corrosion process, especially for the local corrosion. The porosity of the films decreases from 0.13% to 0.00032% by introducing silane at the flow rate of 14 sccm.

  18. Incidence Angle Effect of Energetic Carbon Ions on Deposition Rate, Topography, and Structure of Ultrathin Amorphous Carbon Films Deposited by Filtered Cathodic Vacuum Arc

    KAUST Repository

    Wang, N.

    2012-07-01

    The effect of the incidence angle of energetic carbon ions on the thickness, topography, and structure of ultrathin amorphous carbon (a-C) films synthesized by filtered cathodic vacuum arc (FCVA) was examined in the context of numerical and experimental results. The thickness of a-C films deposited at different incidence angles was investigated in the light of Monte Carlo simulations, and the calculated depth profiles were compared with those obtained from high-resolution transmission electron microscopy (TEM). The topography and structure of the a-C films were studied by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The film thickness decreased with the increase of the incidence angle, while the surface roughness increased and the content of tetrahedral carbon hybridization (sp 3) decreased significantly with the increase of the incidence angle above 45° , measured from the surface normal. TEM, AFM, and XPS results indicate that the smoothest and thinnest a-C films with the highest content of sp 3 carbon bonding were produced for an incidence angle of 45°. The findings of this study have direct implications in ultrahigh-density magnetic recording, where ultrathin and smooth a-C films with high sp 3 contents are of critical importance. © 2012 IEEE.

  19. Characterization of Zr-Si-N films deposited by cathodic vacuum arc with different N{sub 2}/SiH4 flow rates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, G.P., E-mail: princeterry@163.com [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Niu, E.W.; Wang, X.Q.; Lv, G.H.; Zhou, L.; Pang, H.; Huang, J.; Chen, W.; Yang, S.Z. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

    2012-02-01

    Zr-Si-N films were deposited on silicon and steel substrates by cathodic vacuum arc with different N{sub 2}/SiH{sub 4} flow rates. The N{sub 2}/SiH{sub 4} flow rates were adjusted at the range from 0 to 12 sccm. The films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), hardness and wear tests. The structure and the mechanical properties of Zr-Si-N films were compared to those of ZrN films. The results of XRD and XPS showed that Zr-Si-N films consisted of ZrN crystallites and SiN{sub x} amorphous phase. With increasing N{sub 2}/SiH{sub 4} flow rates, the orientation of Zr-Si-N films became to a mixture of (1 1 1) and (2 0 0). The column width became smaller, and then appeared to vanish with the increase in N{sub 2}/SiH{sub 4} flow rates. The hardness and Young's modulus of Zr-Si-N films increased with the N{sub 2}/SiH{sub 4} flow rates, reached a maximum value of 36 GPa and 320 GPa at 9 sccm, and then decreased 32 GPa and 305 GPa at 12 sccm, respectively. A low and stable of friction coefficient was obtained for the Zr-Si-N films. Friction coefficient was about 0.1.

  20. The creation of new rotation arc to the rat latissimus dorsi musculo-cutaneous flap with delay procedures

    Directory of Open Access Journals (Sweden)

    Aktas Alper

    2003-12-01

    Full Text Available Abstract Background Latissimus dorsi musculocutaneous flap is one of the most frequently performed reconstructive techniques in surgery. Latissimus dorsi muscle has two arcs of rotation. It is classified as type V muscle. This muscle can be elevated on the thoracodorsal artery to cover large defects in the anterior chest and also, the muscle can be elevated on the segmental vessels to cover midline defects posteriorly. The aim of this study was to create a new arc of rotation on a vertical axis for the muscle and investigate effectiveness of vascular and chemical delays on the latissimus dorsi muscle flap with an inferior pedicle in an experimental rat model. We hypothesized that the latissimus dorsi muscle would be based on inferior pedicle by delay procedures. Methods We tested two different types of delay: vascular and combination of vascular and chemical. We also tried to determine how many days of "delay" can elicit beneficial effects of vascular and combination delays in an inferior pedicled latissimus dorsi musculocutaneous flap. To accomplish this, 48 male Sprague-Dawley rats were randomly subjected to vascular or combination delay (vascular and chemical. In addition, one ear of each rat was assigned into a delay procedure and the other ear was used as a control. Results were evaluated macroscopically, and micro-angiography and histological examinations were also performed. As a result, there was a significant difference in viable flap areas between vascular delay alone and control groups (p Results The higher rate of flap viability was obtained in seven-day vascular delay alone. However, there was no significant difference in the viability between seven-day vascular delay and five-day vascular delay (p Conclusion The combination of vascular and chemical delays increased the rate of viability. Nevertheless, there was no significant difference between vascular delay alone and combination of vascular and chemical delays. Chemical delay did

  1. Corrosion Resistance Behavior of Single-Layer Cathodic Arc PVD Nitride-Base Coatings in 1M HCl and 3.5 pct NaCl Solutions

    Science.gov (United States)

    Adesina, Akeem Yusuf; Gasem, Zuhair M.; Madhan Kumar, Arumugam

    2017-04-01

    The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials ( E corr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance ( R ct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where R ct of TiN is lowest. While the pore resistance ( R po) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.

  2. Corrosion Resistance Behavior of Single-Layer Cathodic Arc PVD Nitride-Base Coatings in 1M HCl and 3.5 pct NaCl Solutions

    Science.gov (United States)

    Adesina, Akeem Yusuf; Gasem, Zuhair M.; Madhan Kumar, Arumugam

    2017-01-01

    The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials (E corr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance (R ct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where R ct of TiN is lowest. While the pore resistance (R po) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.

  3. Study on nanocomposite Ti-Al-Si-Cu-N films with various Si contents deposited by cathodic vacuum arc ion plating

    Energy Technology Data Exchange (ETDEWEB)

    Shi, J. [State Key Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Strasse 9-11, Siegen 57076 (Germany); Muders, C.M.; Kumar, A. [Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Strasse 9-11, Siegen 57076 (Germany); Jiang, X., E-mail: xin.jiang@uni-siegen.de [Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Strasse 9-11, Siegen 57076 (Germany); Pei, Z.L.; Gong, J. [State Key Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Sun, C., E-mail: csun@imr.ac.cn [State Key Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer XRD peaks show a tendency of decreasing intensity with increasing Si content. Black-Right-Pointing-Pointer Ti-Al-Si-Cu-N films present different microstructure with increasing Si content. Black-Right-Pointing-Pointer Films with 6 at.% Si content obtain the highest hardness, elastic modulus and H{sup 3}/E{sup 2}. Black-Right-Pointing-Pointer The wear rate decreases with an increase in hardness. - Abstract: In this study, nanocomposite Ti-Al-Si-Cu-N films were deposited on high speed steel substrates by the vacuum cathode arc ion plating (AIP) technique. By virtue of X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM), the influence of silicon content on the film microstructure and characteristics was investigated systematically, including the chemical composition, crystalline structure as well as cross-section morphologies. With increasing the silicon content, a deterioration of the preferred orientation and a dense globular structure were detected. In the meanwhile, atomic force microscopy (AFM), nano-indentation, Rockwell indenter and reciprocating test were also utilized to analyze the hardness, elastic modulus, H{sup 3}/E{sup 2}, friction coefficient, adhesive strength and wear rate of the Ti-Al-Si-Cu-N films. The results showed that an optimal silicon content correlated with the best mechanical and tribological properties of the presented Ti-Al-Si-Cu-N films existed. With increasing the silicon content, the hardness, elastic modulus and the ratio H{sup 3}/E{sup 2} first were improved gradually, and then were impaired sharply again. When the silicon content reached to 6 at.%, the film possessed the highest hardness, elastic modulus and ratio H{sup 3}/E{sup 2} of approximately 24 GPa, 218 GPa and 0.31, respectively. Besides, films containing both 6 at.% and 10 at.% Si contents obtained a relatively low friction coefficient and a good adhesive

  4. Large-scale block rotations from Late Tortonian to Present in the Gibraltar Arc System: input into the Messinian salinity crisis

    Science.gov (United States)

    Crespo-Blanc, Ana; Comas, Menchu; Balanyá, Juan Carlos

    2016-04-01

    We propose a reconstruction of one of the tightest orogenic arcs on Earth: the Gibraltar Arc System (GAS), which closes the Alpine-Mediterranean orogenic system to the west. This reconstruction, which includes onshore and offshore data, is completed for approximately 9 Ma, a few Ma before the Messinian Salinity Crisis (MSC). By that time a change in the direction of the Africa-Iberia convergence took place, the main shortening in the external wedge was accomplished, most of the low-angle normal fault systems that contribute to crustal-scale extension in the GAS ceased, and a significant emersion along the Africa and Iberia continental margins occurred, due to an overall contractive reorganization in the GAS. Our paleotectonic reconstruction is based on a review in terms of structures and age of the superposed deformational events that took place during the Miocene within the GAS, with special attention to the external zones of its northern branch. Our review and new structural data permit to constrain the timing of vertical axis-rotations evidenced by previously published paleomagnetic data, and to identify homogeneous domains in terms of relationships between timing of deformation events and block rotations. Block-rotations as high as 53° took place from 9 Ma to Present, which represents around 6°/Ma. The size of the rotated blocks reach 150 to 200 km long (measured along-strike). It implies that the rotations were accommodated by relatively rigid large-scale domains instead of smaller segments rotated progressively, which favors a model of vertical-axis block-rotations on top of crustal-scale decoupling levels. These rotations accommodated tightening and lengthening of the GAS and drastically altered its onshore and offshore geometry from 9 Ma onwards. In the back-arc Alboran Basin, this post-Miocene tightening produced inversion on Middle Miocene normal faults, wrench tectonics, the reactivation of shale diapirism and volcanism, and the uplift of the margins

  5. Impact of gantry rotation time on plan quality and dosimetric verification--volumetric modulated arc therapy (VMAT) vs. intensity modulated radiotherapy (IMRT).

    Science.gov (United States)

    Pasler, Marlies; Wirtz, Holger; Lutterbach, Johannes

    2011-12-01

    To compare plan quality criteria and dosimetric accuracy of step-and-shoot intensity-modulated radiotherapy (ss-IMRT) and volumetric modulated arc radiotherapy (VMAT) using two different gantry rotation times. This retrospective planning study based on 20 patients was comprised of 10 prostate cancer (PC) and 10 head and neck (HN) cancer cases. Each plan contained two target volumes: a primary planning target volume (PTV) and a boost volume. For each patient, one ss-IMRT plan and two VMAT plans at 90 s (VMAT90) and 120 s (VMAT120) per arc were generated with the Pinnacle© planning system. Two arcs were provided for the PTV plans and a single arc for boost volumes. Dosimetric verification of the plans was performed using a 2D ionization chamber array placed in a full scatter phantom. VMAT reduced delivery time and monitor units for both treatment sites compared to IMRT. VMAT120 vs. VMAT90 increased delivery time and monitor units in PC plans without improving plan quality. For HN cases, VMAT120 provided comparable organs at risk sparing and better target coverage and conformity than VMAT90. In the VMAT plan verification, an average of 97.1% of the detector points passed the 3 mm, 3% γ criterion, while in IMRT verification it was 98.8%. VMAT90, VMAT120, and IMRT achieved comparable treatment plans. Slower gantry movement in VMAT120 plans only improves dosimetric quality for highly complex targets.

  6. Effect of negative substrate bias on the microstructure and mechanical properties of Ti-Si-N films deposited by a hybrid filtered cathodic arc and ion beam sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yujuan, E-mail: cnzhangyujuan@yahoo.com.cn [Laboratory of Special Functional Materials, Henan University, Kaifeng 475004 (China); Yang Yingze; Zhai Yuhao; Zhang Pingyu [Laboratory of Special Functional Materials, Henan University, Kaifeng 475004 (China)

    2012-07-01

    A hybrid cathodic arc and ion beam sputtering method was employed to synthesize Ti-Si-N films. The influence of negative substrate bias on the structure and mechanical properties was investigated by using XRD, XPS, HRTEM, nanoindentor and so on. With the increasing of negative bias there is a decrease in the TiN crystallite size from 36 nm to 10 nm. Negative substrate bias promoted the conformation of nc-TiN/a-Si{sub 3}N{sub 4} nanocomposite structure with complete phase separation and uniform crystallite size. Superhard TiSiN films with a maximum hardness of 46 GPa were successfully synthesized under 100 V negative bias. Severe oxidation occurred in films deposited under 200 V and 300 V negative substrate bias due to the decreasing of deposition rate, which led to the hardness of films reduced to the value of 26 GPa and 22 GPa respectively.

  7. A late Tortonian paleotectonic restoration of the Gibraltar Arc System (GAS) based on the restoration of block rotations. Consequences on the GAS geodynamic evolution

    Science.gov (United States)

    Crespo-Blanc, Ana; Comas, Menchu; Balanyá, Juan Carlos

    2014-05-01

    The Gibraltar Arc System (GAS) closes the Alpine-Mediterranean orogenic system to the west and includes the Betic-Rif orogenic belt, the Alboran and Argelian-Balearic basins and the accretionary prism present in the Cadiz Gulf. Previous investigations on this orogenic system, both onshore and offshore have permit to establish the first order milestones of its Miocene to Recent geodynamic evolution. In most of the models of the geodynamic evolution of the GAS, the external boundary of the Betic-Rif orogenic wedge, initially N-S directed, sweeps from east to west the Gibraltar Arc area, acquiring his arcuate geometry during this westward movement. Nevertheless, most of these models are generally at scale equivalent to 1:10.000.000 or even smaller, and frequently based on 2D schematic cross-sections from which a model for the whole arc is deduced. This fact under evaluates not only the mass movements oblique to the selected cross-section plane, but also the diachronism of the deformation, in turn expected in a so closed arc. In this communication, we want to zoom on the Gibraltar Arc area, to draw a detailed Late Tortonian paleotectonic restoration and to highlight the consequence of this reconstruction on the final evolution of the westernmost Mediterranean. Our approach is based on: 1) the identification and characterization of structural domains of the Gibraltar Arc orogenic system and the transfer fault zones that separate them, 2) an accurate dating of the superposed events of deformations for each one of these domains, 3) the restoration of vertical axis-rotations of some of these structural domains (evidenced by paleomagnetic data previously published), and 4) the quantification of Miocene shortening in the External zones. This exercise makes us to put all together the results of twenty years of research of our teams on this natural case-study, mainly with field and marine geology techniques, and to test it through the revision of an extensive bibliography. It

  8. Neotectonic rotations in the Calabrian Arc; implications for a Pliocene-Recent geodynamic scenario for the Central Mediterranean

    NARCIS (Netherlands)

    Dijk, J.P. van; Scheepers, P.J.J.

    2007-01-01

    Recently, new data have been presented which imply that major block rotations took place in the Central Mediterranean during the Pleistocene, between 1.0 and 0.7 Ma. Kinematic solutions for the spatial and temporal distribution of rotational data in the Central Mediterranean such as oroclinal

  9. Effect of turbulent flow on the anodic and cathodic kinetics of API X52 steel corrosion in H{sub 2}S containing solutions. A rotating cylinder electrode study

    Energy Technology Data Exchange (ETDEWEB)

    Galvan-Martinez, R. [Grupo Anticorrosion-Instituto de Ingenieria, Universidad Veracruzana SS. Juan Pablo II, Veracruz (Mexico); Mendoza-Flores, J.; Duran-Romero, R. [Instituto Mexicano del Petroleo, Direccion Ejecutiva de Exploracion y Produccion, Mexico (Mexico); Genesca, J. [Universidad Nacional Autonoma Mexico, UNAM Ciudad Universitaria, Mexico (Mexico). Dept. Ingenieria Metalurgica, Facultad Quimica

    2007-07-15

    This work presents the electrochemical kinetics results measured during the corrosion of API X52 pipeline steel immersed in aqueous environments, containing dissolved hydrogen sulfide (H{sub 2}S) under turbulent flow conditions. In order to control the turbulent flow conditions, a rotating cylinder electrode (RCE) was used. Five different rotation rates were studied: 0 (or static conditions), 1000, 3000, 5000 and 7000 rpm. It was found that the turbulent flow increases the corrosion rate and the corrosion mechanism for X52 steel exhibits a significant dependence on mass transfer on the cathodic kinetics. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  10. Structural, optical and electrical properties of N-doped ZnO thin films prepared by thermal oxidation of pulsed filtered cathodic vacuum arc deposited Zn{sub x}N{sub y} films

    Energy Technology Data Exchange (ETDEWEB)

    Erdogan, N.H.; Kara, K.; Ozdamar, H. [Physics Department, Cukurova University, 01330 Adana (Turkey); Kavak, H., E-mail: hkavak@cu.edu.tr [Physics Department, Cukurova University, 01330 Adana (Turkey); Esen, R. [Physics Department, Cukurova University, 01330 Adana (Turkey); Karaagac, H. [Physics Department, Middle East Technical University, 06531 Ankara (Turkey)

    2011-09-08

    Graphical abstract: Highlights: > Thermal oxidation of Zn{sub x}N{sub y} method is used to obtain N doped ZnO. > N acceptors in ZnO is not sufficiently activated at oxidation temperature below 350 deg. C. > Oxidation treatment at 450 deg. C activates more N acceptors in ZnO. > Oxidation treatment at high temperatures above 550 deg. C reduces the N concentration in the ZnO thin film. - Abstract: In this study, N-doped ZnO thin films were fabricated by oxidation of Zn{sub x}N{sub y} films. The Zn{sub x}N{sub y} thin films were deposited on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) using metallic zinc wire (99.999%) as a cathode target in pure nitrogen plasma. The influence of oxidation temperature, on the electrical, structural and optical properties of N-doped ZnO films was investigated. P-type conduction was achieved for the N-doped ZnO obtained at 450 deg. C by oxidation of Zn{sub x}N{sub y}, with a resistivity of 16.1 {Omega} cm, hole concentration of 2.03 x 10{sup 16} cm{sup -3} and Hall mobility of 19 cm{sup 2}/V s. X-ray photoelectron spectroscopy (XPS) analysis confirmed the incorporation of N into the ZnO films. X-ray diffraction (XRD) pattern showed that the films as-deposited and oxidized at 350 deg. C were amorphous. However, the oxidized films in air atmosphere at 450-550 deg. C were polycrystalline without preferential orientation. In room temperature photoluminescence (PL) spectra, an ultraviolet (UV) peak was seen for all the samples. In addition, a broad deep level emission was observed.

  11. Comparative study of structural and electro-optical properties of ZnO:Ga films grown by steered cathodic arc plasma evaporation and sputtering on plastic and their application on polymer-based organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chih-Hao, E-mail: dataman888@hotmail.com [R& D Division, Walsin Technology Corporation, Kaohsiung, Taiwan (China); Hsiao, Yu-Jen [National Nano Device Laboratories, National Applied Research Laboratories, Tainan, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

    2016-08-01

    Ga-doped ZnO (GZO) films with various thicknesses (105–490 nm) were deposited on PET substrates at a low temperature of 90 °C by a steered cathodic arc plasma evaporation (steered CAPE), and a GZO film with a thickness of 400 nm was deposited at 90 °C by a magnetron sputtering (MS) for comparison. The comparative analysis of the microstructure, residual stress, surface morphology, electrical and optical properties, chemical states, and doping efficiency of the films produced by the steered CAPE and MS processes was performed, and the effect of thickness on the CAPE-grown GZO films was investigated in detail. The results showed that the GZO films grown by steered CAPE exhibited higher crystallinity and lower internal stress than those deposited by MS. The transmittance and electrical properties were also enhanced for the steered CAPE-grown films. The figure of merit (Φ = T{sup 10}/R{sub s}, where T is the transmittance and R{sub s} is the sheet resistance in Ω/□). was used to evaluate the performance of the electro-optical properties. The GZO films with a thickness of 400 nm deposited by CAPE had the highest Φ value, 1.94 × 10{sup −2} Ω{sup −1}, a corresponding average visible transmittance of 88.8% and resistivity of 6.29 × 10{sup −4} Ω·cm. In contrast, the Φ value of MS-deposited GZO film with a thickness of 400 nm is only 1.1 × 10{sup −3} Ω{sup −1}. This can be attributed to the increase in crystalline size, [0001] preferred orientation, decrease in stacking faults density and Ar contamination in steered CAPE-grown films, leading to increases in the Hall mobility and carrier density. In addition, the power conversion efficiency (PCE) of organic solar cells was significantly improved by using the CAPE-grown GZO electrode, and the PCE values were 1.2% and 1.7% for the devices with MS-grown and CAPE-grown GZO electrodes, respectively. - Highlights: • ZnO:Ga (GZO) films were grown on PET by steered cathodic arc plasma evaporation (CAPE

  12. A comparative study of the structural, mechanical and tribological characteristics of TiSiC-Cr coatings prepared in CH4 and C2H2 reactive atmosphere by cathodic vacuum arc

    Science.gov (United States)

    Braic, Mariana; Vladescu, Alina; Balaceanu, Mihai; Luculescu, Catalin; Padmanabhan, Sibu C.; Constantin, Lidia; Morris, Michael A.; Braic, Viorel; Ana Grigorescu, Cristiana Eugenia; Ionescu, Paul; Dracea, Maria Diana; Logofatu, Constantin

    2017-04-01

    TiSiC-Cr coatings, with Cr and Si as additional elements, were deposited on Si, C 45 and 316 L steel substrates via cathodic arc evaporation. Two series of coatings with thicknesses in the range of 3.6-3.9 μm were produced, using either CH4 or C2H2 as carbon containing gas. For each series, different coatings were prepared by varying the carbon rich gas flow rate between 90 and 130 sccm, while maintaining constant cathode currents (110 and 100 A at TiSi and Cr cathodes, respectively), substrate bias (-200 V) and substrate temperature (∼320 °C). The coatings were analyzed for their mechanical characteristics (hardness, adhesion) and tribological performance (friction, wear), along with their elemental and phase composition, chemical bonds, crystalline structure and cross-sectional morphology. The coatings were found to be formed with nano-scale composite structures consisting of carbide crystallites (grain size of 3.1-8.2 nm) and amorphous hydrogenated carbon. The experimental results showed significant differences between the two coating series, where the films formed from C2H2 exhibited markedly superior characteristics in terms of microstructure, morphology, hardness, friction behaviour and wear resistance. For the coatings prepared using CH4, the measured values of crystallite size, hardness, friction coefficient and wear rate were in the ranges of 7.2-8.2 nm, 26-30 GPa, 0.3-0.4 and 2.1-4.8 × 10-6 mm3 N-1 m-1, respectively, while for the coatings grown in C2H2, the values of these characteristics were found to be in the ranges of 3.1-3.7 nm, 41-45 GPa, 0.1-0.2 and 1.4-3.0 × 10-6 mm3 N-1 m-1, respectively. Among the investigated coatings, the one produced using C2H2 at the highest flow rate (130 sccm) exhibited the highest hardness (45.1 GPa), the lowest friction coefficient (0.10) and the best wear resistance (wear rate of 1.4 × 10-6 mm3 N-1 m-1).

  13. Regression Analysis of the Effect of Bias Voltage on Nano- and Macrotribological Properties of Diamond-Like Carbon Films Deposited by a Filtered Cathodic Vacuum Arc Ion-Plating Method

    Directory of Open Access Journals (Sweden)

    Shojiro Miyake

    2014-01-01

    Full Text Available Diamond-like carbon (DLC films are deposited by bend filtered cathodic vacuum arc (FCVA technique with DC and pulsed bias voltage. The effects of varying bias voltage on nanoindentation and nanowear properties were evaluated by atomic force microscopy. DLC films deposited with DC bias voltage of −50 V exhibited the greatest hardness at approximately 50 GPa, a low modulus of dissipation, low elastic modulus to nanoindentation hardness ratio, and high nanowear resistance. Nanoindentation hardness was positively correlated with the Raman peak ratio Id/Ig, whereas wear depth was negatively correlated with this ratio. These nanotribological properties highly depend on the films’ nanostructures. The tribological properties of the FCVA-DLC films were also investigated using a ball-on-disk test. The average friction coefficient of DLC films deposited with DC bias voltage was lower than that of DLC films deposited with pulse bias voltage. The friction coefficient calculated from the ball-on-disk test was correlated with the nanoindentation hardness in dry conditions. However, under boundary lubrication conditions, the friction coefficient and specific wear rate had little correlation with nanoindentation hardness, and wear behavior seemed to be influenced by other factors such as adhesion strength between the film and substrate.

  14. Effect of C{sub 2}H{sub 2} flow rate on microstructure and properties of nc–Cu/a–C:H nanocomposite films prepared by filtered cathodic vaccum arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haiqiang; Chen, Yiming; Liao, Bin; Wu, Xianying; Zhang, Huixing [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Zhang, Xu, E-mail: zhangxu@bnu.edu.cn [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China)

    2013-07-15

    Nc–Cu/a–C:H nanocomposite films are deposited by filtered cathodic vaccum arc (FCVA) technique using C{sub 2}H{sub 2} as the precursor. The effects of C{sub 2}H{sub 2} flow rate on the microstructure, composition and properties of nc–Cu/a–C:H films have been studied by Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nanoindentation test. In these films, copper nanoparticles (3.5–15 nm) are embedded in the amorphous carbon matrix, which could be confirmed by XRD analysis. Raman spectroscopy and XPS results confirm the decrease of sp{sup 3} content with the increasing copper fraction, which could be a result of more severe thermalization on carbon matrix owing to the presence of copper. The compressive stresses of these films, calculated by Stoney’s equation, are found to be as low as 0.5 Gpa, declining with the increasing copper content. Nanoindentation measurements reveal that the film hardness falls monotonically as the Cu content in the films increases.

  15. Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation.

    Science.gov (United States)

    Schroeder, J L; Thomson, W; Howard, B; Schell, N; Näslund, L-Å; Rogström, L; Johansson-Jõesaar, M P; Ghafoor, N; Odén, M; Nothnagel, E; Shepard, A; Greer, J; Birch, J

    2015-09-01

    We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (>50 keV), high photon flux (>10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (<1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (<11°), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument.

  16. 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.

  17. Three-dimensional model and simulation of vacuum arcs under axial magnetic fields

    Science.gov (United States)

    Wang, Lijun; Jia, Shenli; Zhou, Xin; Wang, Haijing; Shi, Zongqian

    2012-01-01

    In this paper, a three-dimensional (3d) magneto-hydro-dynamic (MHD) model of axial magnetic field vacuum arcs (AMFVAs) is established. Based on this model, AMFVAs are simulated and analyzed. Three-dimensional spatial distributions of many important plasma parameters and electric characteristics in AMFVAs can be obtained, such as ion number density, ion temperature, electron temperature, plasma pressure, current densities along different directions (x, y, and z), ion velocities along different directions, electric fields strength along different directions, and so on. Simulation results show that there exist significant spiral-shaped rotational phenomena in the AMFVAs, this kind of rotational phenomenon also can be verified by the many related experiments (AMFVAs photographs, especially for stronger AMF strength). For current simulation results of AMFVAs, the maximal rotational velocity at anode side is about 1100 m/s. Radial electric field is increased from arc center to arc edge; axial electric field is decreased from cathode side to anode side. Radial electric field at arc edge can be larger than axial electric field. Azimuthal electric field in most regions is much smaller than radial and axial electric field, but it can reach about 1.19 kV/m. Radial magnetic field is the smallest one compared with other components, it reaches to maximum value at the position near to anode, it can influence arc characteristics.

  18. Water-vortex stabilized electric arc: I. Numerical model

    Science.gov (United States)

    Jenista, Jirí

    1999-11-01

    A numerical model for an electric arc stabilized by a water vortex has been proposed. The two-dimensional axisymmetric model includes the discharge area between the cathode and the orifice of the arc chamber. The production of water plasma, i.e. the rate of evaporation of a water wall, is taken either from experiments or is determined numerically by fitting of the outlet plasma parameters to the experimental ones. The computer results concern thermal, fluid dynamic and electrical characteristics of such arcs for the currents 300, 400, 500 and 600 A. It is found, for example, that the role of thermal diffusion within the discharge increases with current. The power losses from the arc due to radial conduction and radiation represent around 50% of the input power. Rotation of the plasma column due to the induced tangential velocity component has negligible effect on the overall arc performance. The calculated velocities, pressure drops and electrical potentials are in good agreement with experiments carried out on the water plasma torch PAL-160 operating at our Institute.

  19. Plasma backflow phenomenon in high-current vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lijun [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Jia Shenli [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang Ling [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Shi Zongqian [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Yang Dingge [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Gentils, Francois [Schneider Electric SAS, 37 quai Paul-Louis Merlin, 38050 Grenoble Cedex 9 (France); Jusselin, BenoIt [Schneider Electric SAS, 37 quai Paul-Louis Merlin, 38050 Grenoble Cedex 9 (France)

    2007-10-07

    Based on the two-temperature magnetohydrodynamic model, a high-current vacuum arc (HCVA) in vacuum interrupters is simulated and analysed. The phenomenon of plasma backflow in arc column is found, which is ultimately ascribed to the strong magnetic pinch effect of HCVA. Due to plasma backflow, the maximal value of ion density at the cathode side is not located at the centre of the cathode side, but at the paraxial region of the cathode side, that is to say, ion density appears to sag at the centre of the cathode side (arc column seems to be divided into two parts). The sag of light intensity is also found by experiments.

  20. Arc Plasma Torch Modeling

    CERN Document Server

    Trelles, J P; Vardelle, A; Heberlein, J V R

    2013-01-01

    Arc plasma torches are the primary components of various industrial thermal plasma processes involving plasma spraying, metal cutting and welding, thermal plasma CVD, metal melting and remelting, waste treatment and gas production. They are relatively simple devices whose operation implies intricate thermal, chemical, electrical, and fluid dynamics phenomena. Modeling may be used as a means to better understand the physical processes involved in their operation. This paper presents an overview of the main aspects involved in the modeling of DC arc plasma torches: the mathematical models including thermodynamic and chemical non-equilibrium models, turbulent and radiative transport, thermodynamic and transport property calculation, boundary conditions and arc reattachment models. It focuses on the conventional plasma torches used for plasma spraying that include a hot-cathode and a nozzle anode.

  1. Atmospheric pressure arc discharge with ablating graphite anode

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, V. A. [Keiser University, Fort Lauderdale Campus, FL, 33309, USA; Raitses, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2015-05-18

    The anodic carbon arc discharge is used to produce carbon nanoparticles. Recent experiments with the carbon arc at atmospheric pressure helium demonstrated the enhanced ablation rate for narrow graphite anodes resulting in high deposition rates of carbonaceous products on the copper cathode (Fetterman et al 2008 Carbon 46 1322–6). The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes. When considering cathode functioning, the model predicts circulation of the particles in the near-cathode region: evaporation of the cathode material, ionization of evaporated atoms and molecules in the near-cathode plasma, return of the resulting ions to the cathode, surface recombination of ions and electrons followed again by cathode evaporation etc. In the case of the low anode ablation rate, the ion acceleration in the cathode sheath provides the major cathode heating mechanism. In the case of an intensive anode ablation, an additional cathode heating is due to latent fusion heat of the atomic species evaporated from the anode and depositing at the cathode. Using the experimental arc voltage as the only input discharge parameter, the model allows us to calculate the anode ablation rate. A comparison of the results of calculations with the available experimental data shows reasonable agreement.

  2. Ecton mechanism for the generation of ion flows in a vacuum arc

    CERN Document Server

    Mesyats, G A

    2001-01-01

    Physical substantiation of the parameters of the ion flow, generated by the vacuum arc cathode spots is given for the first time in this work. The main characteristics of the vacuum arc cathode plasma generation process (the ion erosion, the ions average charge) are considered within the frames, of the ecton model of the vacuum arc cathode spot. According to this model the vacuum arc cathode spot consists of separate cells, emitting ectons. The ions parameter evaluations, obtained within the frames of the ecton model, qualitatively and quantitatively agree with the experimental data

  3. Ecton mechanism of ion flow generation in vacuum arc

    CERN Document Server

    Mesyats, G A

    2001-01-01

    The basic characteristics of cathode plasma generation in vacuum arc (ion erosion, ion average charge) were studied from the point of an ecton model of a cathode spot in vacuum arc. The estimates of ion parameters obtained for a single cell of a cathode spot show qualitative conformity with the experimental data. One introduces the following mechanism of cathode plasma generation in vacuum arc. In case of explosion-like destruction of a cathode segment under the effect of the Joule heating the cathode matter changes sequentially its state: condensed one, nonideal and ideal plasma ones. During this change one observes formation of plasma charge composition and ion acceleration under the effect of plasma pressure gradient

  4. Microstructure and thermal stability of corundum-type (Al{sub 0.5}Cr{sub 0.5}){sub 2}O{sub 3} solid solution coatings grown by cathodic arc evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Edlmayr, V.; Pohler, M. [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria); Letofsky-Papst, I. [Institute for Electron Microscopy, University of Technology Graz, Steyrergasse 17, A-8010 Graz (Austria); Mitterer, C., E-mail: christian.mitterer@unileoben.ac.at [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria)

    2013-05-01

    Corundum-type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} coatings were grown by reactive cathodic arc evaporation in an oxygen atmosphere using AlCr targets with an Al/Cr atomic ratio of 1. Since the (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} solid solution shows a miscibility gap below 1300 °C, where spinodal decomposition is predicted, the microstructural changes upon annealing were investigated by a combination of transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. The as-deposited coating consists primarily of the corundum-type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} solid solution, with smaller fractions of cubic (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3}. An additional Al-rich amorphous phase and a Cr-rich crystalline phase stem from the droplets incorporated. The corundum-type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} solid solution is still present after vacuum annealing at 1050 °C for 2 h, whereas the cubic (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} phase has transformed to corundum-type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3}. Cr and Cr{sub 2}O{sub 3} have been detected in the annealed coating, the latter most probably originating from the partial oxidation of Cr-rich droplets. Upon crystallization of the amorphous phase fractions present, γ-Al{sub 2}O{sub 3} is formed, which then transforms into α-Al{sub 2}O{sub 3}. No evidence for decomposition of the corundum-type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} solid solution could be found within the temperature range up to 1400 °C. - Highlights: ► (Al{sub 0.5}Cr{sub 0.5}){sub 2}O{sub 3} hard coatings grown by reactive cathodic evaporation ► Corundum and minor fraction of cubic (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} in the as-deposited state ► No evidence for spinodal decomposition of corundum-type (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} up to 1400 °C ► Cubic (Al{sub x}Cr{sub 1−x}){sub 2}O{sub 3} transforms into corundum-type (Al{sub x}Cr{sub 1

  5. Multicomponent Thin Films Deposited by PVD ARC and LARC Technology

    Directory of Open Access Journals (Sweden)

    Dagmar JAKUBÉCZYOVÁ

    2014-04-01

    Full Text Available The paper is focused on a comparison of advanced layers deposited by two coating technologies – cathodic arc deposition (ARC and lateral rotating cathodes (LARC. For characterization standard analyses were selected: the determination of the layer wear resistance by Calotest method, specification of the depth concentration profiles of constituting elements from the coating surface down to the substrate, and measurement of the nanohardness at dynamic loading. The thickness of the CrTiN layer reached 1380 nm – 1740 nm and that of the multi/nanolayers AlXN3 was 2630 nm – 3160 nm. The coating nanohardness on the surface attained 39 GPa for AlXN3 (X = Cr, 33 GPa for CrTiN and 12.5 GPa for the substrate. Only at coating prepared by LARC-Technology it is possible to create the multilayers of nanometric dimensions. AlXN3 coating was formed by 48 layers with dimensions of 58 nm – 70 nm. These nanolayers lead to the increase of system toughness as they prevent the crack propagation. Their application on the tools and components promises to increase their durability under service conditions.DOI: http://dx.doi.org/10.5755/j01.ms.20.1.3716

  6. Gas tungsten arc welder

    Science.gov (United States)

    Christiansen, D.W.; Brown, W.F.

    A welder for automated closure of fuel pins by a gas tungsten arc process in which a rotating length of cladding is positioned adjacent a welding electrode in a sealed enclosure. An independently movable axial grinder is provided in the enclosure for refurbishing the used electrode between welds.

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

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Jacobsen, Torben; Wandel, Marie

    2011-01-01

    performing cathodes showed a slightly suppressed Gerischer impedance, while the impedance spectra of the well performing cathodes showed the presence of an arc due to oxygen gas diffusion. The overall impedance of the well performing cathodes could be described with a slightly suppressed Gerischer impedance...

  8. 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.

  9. SOFC LSM:YSZ cathode degradation induced by moisture: An impedance spectroscopy study

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Mogensen, Mogens Bjerg

    2011-01-01

    The cause of the degradation effect of moisture during operation of LSM cathode based SOFCs has been investigated by means of a detailed impedance characterization on LSM:YSZ composite cathode based SOFCs. Further the role of YSZ as cathode composite material was studied by measurements on SOFCs...... with a LSM:CGO composite cathode on a CGO interdiffusion barrier layer. It was found that both types of cathodes showed similar electrochemical characteristics towards the presence of moisture during operation. Upon addition and removal of moisture in the fed air the impedance study showed a change...... in the high frequency cathode arc, which is associated with the charge transport/transfer at the LSM/YSZ interface. On prolonged operation with the presence of moisture an ongoing increase in the high frequency cathode arc resulted in a permanent loss of cathode/electrolyte contact and thus increase...

  10. Palaeomagnetic constraints on the geodynamic evolution of the Gibraltar Arc

    NARCIS (Netherlands)

    Krijgsman, W.; Garces, M.

    2004-01-01

    Subduction zone roll-back was recently put forward as a convincing model to explain the geometry and evolution of the Gibraltar Arc. For other subduction-related arc systems of the Mediterranean, such as the Calabrian Arc and the Hellenic Arc, palaeomagnetic rotation data from Neogene extensional ba

  11. Cathode Erosion of Graphite and Cu/C Materials in Airarcs

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chengyu; QIAO Shengru; LIU Yiwen; YANG Zhimao; WANG Yaping; GUO Yong

    2012-01-01

    Cathode erosion of graphite and Cu/C was studied in direct current arcs,which were ignited between two electrodes comprised of two kinds of carbon materials and a tungsten anode in air.The arced zones on the cathode surface were investigated by a scanning electron microscope.Also,the cathode erosion rates of the investigated materials were measured.The results show that two distinct zone can be seen on both cathodes.The eroded area was located at the zone just opposite to the anode and surrounded by a white zone.The arced surface on the Cu/C containing 9.3 % Cu is rougher than that of the pure graphite.Many particles with various sizes distributed on the Cu/C.The vaporization of Cu can lower the surface temperature and reduce the cathode erosion.Therefore,the cathode erosion rate of the Cu/C is lower than that of the pure graphite.

  12. Study on Ceramic Cutting by Plasma Arc

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Engineering ceramics are typical difficult-to-machine materials because of high hardness and brittleness. PAC (Plasma Arc Cutting) is a very important thermal cutting process and has been successfully used in cutting stainless steel and other difficult-to-machine alloys. PAC's application in cutting ceramics, however, is still limited because the most ceramics are not good electronic conducts, and transferred plasma arc cannot be produced between cathode and work-piece. So we presented a method of plasma ...

  13. Driven Motion and Instability of an Atmospheric Pressure Arc

    Energy Technology Data Exchange (ETDEWEB)

    Max Karasik

    1999-12-01

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental arc furnace is constructed and operated in air with graphite cathode and steel anode at currents 100-250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes.

  14. 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.

  15. Thermal and electrical influences from bulk plasma in cathode heating modeling

    Science.gov (United States)

    Chen, Tang; Wang, Cheng; Zhang, Xiao-Ning; Zhang, Hao; Xia, Wei-Dong

    2017-02-01

    In this paper, a numerical calculation is performed for the purpose of estimating the thermal and electrical influences from bulk plasma in cathode heating modeling, in other words researching the necessity of a coupling bulk plasma in near-cathode layer modeling. The proposed model applied in the present work is an improved one from previous work. In this model, the near-cathode region is divided into two parts: the sheath and the ionization layer. The Schottky effect at the cathode surface is considered based on the analytic solution of a 1D sheath model. It is noted that the arc column is calculated simultaneously in the near-cathode region and the cathode bulk. An application is presented for an atmospheric free burning argon arc with arc currents of 50 A-600 A. The modeling results show three interesting points: (1) at the cathode surface, energy transport due to heat conduction of heavy particles and electrons is comparable to total heating flux, no matter whether the arc discharge is performed in a high (400 A) or low current (50 A) situation; (2) the electrical influence from bulk plasma on the cathode heating modeling becomes obvious in a high current situation (>400 A) for the spot mode; (3) the near-cathode layer voltage drop ({{U}\\text{tot}} ) is larger in the diffuse mode than in the spot mode for the same current, which is just the opposite to that for decoupled modeling.

  16. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-11-01

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

  17. Gliding arc triggered microwave plasma arc at atmospheric pressure for coal gasification application

    Science.gov (United States)

    Jain, Vishal; Visani, A.; Patil, C.; Patel, B. K.; Sharma, P. K.; John, P. I.; Nema, S. K.

    2014-08-01

    Plasma torch is device that efficiently converts electrical energy in to thermal energy for various high temperature applications. The conventional plasma torch comprises of consumable electrodes namely anode and cathode electrodes. The replacement of these electrodes is a complex process owing to its cooling and process shut down requirements. However, microwave plasma arc is electrode-less plasma arc system that is an alternative method to conventional arc technology for generating plasma arc. In this technique, microwave power is efficiently coupled to generate plasma arc by using the property of polar molecule to absorb microwave power. The absorption of microwave power is in form of losses due to intermolecular friction and high collisions between the molecules. This is an efficient method because all microwave power can be absorbed by plasma arc. The main feature of microwave plasma arc is its large uniform high temperature column which is not possible with conventional arc discharge methods. Such type of plasma discharge is very useful in applications where sufficient residence time for treat materials is required. Microwave arc does not require any consumable electrodes and hence, it can be operated continuously that makes it very useful for hazardous effluent treatment applications. Further, microwave cannot ionize neutral particles at atmospheric pressure and hence, a gliding arc is initiated between two thin electrodes in the cavity by applying very low power high voltage (3kV) AC source. In this report, the method for generating microwave arc of 1kW power using commercial microwave oven is elaborated.

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

    Directory of Open Access Journals (Sweden)

    Sevastyanov V. V.

    2009-02-01

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

  19. Arc Statistics

    CERN Document Server

    Meneghetti, M; Dahle, H; Limousin, M

    2013-01-01

    The existence of an arc statistics problem was at the center of a strong debate in the last fifteen years. With the aim to clarify if the optical depth for giant gravitational arcs by galaxy clusters in the so called concordance model is compatible with observations, several studies were carried out which helped to significantly improve our knowledge of strong lensing clusters, unveiling their extremely complex internal structure. In particular, the abundance and the frequency of strong lensing events like gravitational arcs turned out to be a potentially very powerful tool to trace the structure formation. However, given the limited size of observational and theoretical data-sets, the power of arc statistics as a cosmological tool has been only minimally exploited so far. On the other hand, the last years were characterized by significant advancements in the field, and several cluster surveys that are ongoing or planned for the near future seem to have the potential to make arc statistics a competitive cosmo...

  20. Electrode voltage fall and total voltage of a transient arc

    Science.gov (United States)

    Valensi, F.; Ratovoson, L.; Razafinimanana, M.; Masquère, M.; Freton, P.; Gleizes, A.

    2016-06-01

    This paper deals with an experimental study of the components of a transient arc total voltage with duration of a few tens of ms and a current peak close to 1000 A. The cathode tip is made of graphite whereas the flat anode is made either of copper or of graphite; the electrodes gap is a few mm. The analysis of the electrical parameters is supported and validated by fast imaging and by two models: the first one is a 2D physical model of the arc allowing to calculate both the plasma temperature field and the arc voltage; the second model is able to estimate the transient heating of the graphite electrode. The main aim of the study was to detect the possible change of the cathode voltage fall (CVF) during the first instants of the arc. Indeed it is expected that during the first ms the graphite cathode is rather cool and the main mechanism of the electron emission should be the field effect emission, whereas after several tens of ms the cathode is strongly heated and thermionic emission should be predominant. We have observed some change in the apparent CVF but we have shown that this apparent change can be attributed to the variation of the solid cathode resistance. On the other hand, the possible change of CVF corresponding to the transition between a ‘cold’ and a ‘hot’ cathode should be weak and could not be characterized considering our measurement uncertainty of about 2 V. The arc column voltage (ACV) was estimated by subtracting the electrode voltage fall from the total arc voltage. The experimental transient evolution of the ACV is in very good agreement with the theoretical variation predicted by the model, showing the good ability of the model to study this kind of transient arc.

  1. Modeling Arcs

    CERN Document Server

    Insepov, Zeke; Veitzer, Seth; Mahalingam, Sudhakar

    2011-01-01

    Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma initiation, plasma evolution, surface damage and gra- dient limits. We use simple PIC codes for modeling plasmas, molecular dynamics for modeling surface breakdown, and surface damage, and mesoscale surface thermodynamics and finite element electrostatic codes for to evaluate surface properties. Since any given experiment seems to have more variables than data points, we have tried to consider a wide variety of arcing (rf structures, e beam welding, laser ablation, etc.) to help constrain the problem, and concentrate on common mechanisms. While the mechanisms can be comparatively simple, modeling can be challenging.

  2. Discharge Characteristics of DC Arc Water Plasma for Environmental Applications

    Institute of Scientific and Technical Information of China (English)

    LI Tianming; Sooseok CHOI; Takayuki WATANABE

    2012-01-01

    A water plasma was generated by DC arc discharge with a hafnium embedded rodtype cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process.

  3. Arc tracks on nanostructured surfaces after microbreakdowns

    Science.gov (United States)

    Sinelnikov, D.; Bulgadaryan, D.; Hwangbo, D.; Kajita, S.; Kolodko, D.; Kurnaev, V.; Ohno, N.

    2016-09-01

    Studying of initial steps of unipolar arc ignition process is important for reduction of probability of arcing between the plasma and the wall in thermonuclear devices. Tungsten nano-fuzz surface formed by helium plasma irradiation at high fluences and temperatures is a perfect material for arc ignition. Snowflake-like craters were detected on the fuzzy surfaces after short micro-breakdowns. Such sort of craters have not been observed before on any other metallic surfaces. These specific traces are formed due to unique properties of the fuzz structure. The nano-fuzz could be easily melted and vaporized by micro-breakdown current, due to its porosity and bad thermal conductivity, and formation of low conducting metallic vapour under the cathode spot causes discharge movement to the nearest place. Thus, even low current arc can easily move and leave traces, which could be easily observed by a secondary electron microscope.

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

    Science.gov (United States)

    Huegel, H.; Kruelle, G.

    1984-01-01

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

  5. Treatment Measures for Empty Bearing of Arc Steel Box Girder with Cross Slope for Rotating Structure%旋转结构找横坡弧形钢箱梁支座托空处理措施

    Institute of Scientific and Technical Information of China (English)

    李粤东; 夏崇滔; 张翼; 巫正伟

    2014-01-01

    钢箱梁结构因其自身的特性在市政工程建设得到大量运用,钢箱梁吊装施工中空间就位及空形态的控制问题较为突出,其中带纵坡的弧形钢箱梁通过旋转结构找横坡就使得钢箱梁在施工过程中整体空间形态要有控制技术难度更高,极易造成钢箱梁支座托空。该文结合工程实例,就有纵坡且旋转结构找横坡弧形钢箱梁吊装后产生支座托空的处理措施进行论述。%Steel box girder structure is widely applied nowadays for its virtues, but the controlling problems in space location and spatial form in its con-struction are severe, and the finding of cross slope through rotating structure by arc steel box girder with longitudinal slope renders controlling technology of steel box girder over spatial form harder, easily causing empty bearing of steel box girder. The treatment measures for such problem are presented in de-tail.

  6. Stability of Neptune's ring arcs in question

    Science.gov (United States)

    Dumas, Christophe; Terrile, Richard J.; Smith, Bradford A.; Schneider, Glenn; Becklin, E. E.

    1999-08-01

    Although all four of the gas-giant planets in the Solar System have ring systems, only Neptune exhibits `ring arcs'-stable clumps of dust that are discontinuous from each other. Two basic mechanisms for confining the dust to these arcs have been proposed. The firstrelies on orbital resonances with two shepherding satellites, while the second invokes a single satellite (later suggested to be Galatea) to produce the observed ring arc structures. Here we report observations of the ring arcs and Galatea, which show that there isa mismatch between the locations of the arcs and the site of Galatea's co-rotation inclined resonance. This result calls into question Galatea's sole role in confining the arcs.

  7. Plasma arc cutting technology: simulation and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cantoro, G; Colombo, V; Concetti, A; Ghedini, E; Sanibondi, P; Zinzani, F; Rotundo, F [Department of Mechanical Engineering (D.I.E.M.) and Research Center for Applied Mathematics (C.I.R.A.M.), Alma Mater Studiorum-Universita di Bologna, Via Saragozza 8, 40123 Bologna (Italy); Dallavalle, S; Vancini, M, E-mail: emanuele.ghedini@unibo.it [Cebora S.p.A., Via Andrea Costa 24, 40057 Cadriano di Granarolo (Italy)

    2011-01-01

    Transferred arc plasma torches are widely used in industrial processes for cutting of metallic materials because of their ability to cut a wide range of metals with very high productivity. The process is characterized by a transferred electric arc established between an electrode inside the torch (the cathode) and another electrode, the metallic workpiece to be cut (the anode). In order to obtain a high quality cut and a high productivity, the plasma jet must be as collimated as possible and must have the higher achievable power density. Plasma modelling and numerical simulation can be very useful tools for the designing and optimizing these devices, but research is still in the making for finding a link between simulation of the plasma arc and a consistent prevision of cut quality. Numerical modelling of the behaviour of different types of transferred arc dual gas plasma torches can give an insight on the physical reasons for the industrial success of various design and process solutions that have appeared over the last years. Diagnostics based on high speed imaging and Schlieren photography can play an important role for investigating piercing, dross generation, pilot arcing and anode attachment location. Also, the behaviour of hafnium cathodes at high current levels at the beginning of their service life can been experimentally investigated, with the final aim of understanding the phenomena that take place during those initial piercing and cutting phases and optimizing the initial shape of the surface of the emissive insert exposed to plasma atmosphere.

  8. Nanoscratch technique for aligning multiwalled carbon nanotubes synthesized by the arc discharge method in open air

    Indian Academy of Sciences (India)

    A Joseph Berkmans; M Jagannatham; Prathap Haridoss

    2015-08-01

    Horizontally aligned and densely packed multiwalled carbon nanotubes (MWCNTs) were synthesized in an open air, without the need for a controlled atmosphere, using a rotating cathode arc discharge method with the help of a metal scraper. The physical force exerted by the scraper results in in-situ alignment of MWCNTs along the direction of scrape marks. This strategy, which enables the alignment of nanotubes in a controlled fashion to any length and direction of interest, was examined to determine the force required to align a nanotube. A model is developed to understand the alignment process. Using the nanoscratch technique to mimic this strategy, and incorporating the data obtained from the nanoscratch technique into the model developed, the minimum force required to align a MWCNT, as well as the energy required to align a gram of nanotubes, has been estimated. The method demonstrated represents an economical approach for large-scale synthesis of aligned MWCNTs at low costs.

  9. Planar-Focusing Cathodes

    CERN Document Server

    Lewellen, J W

    2005-01-01

    Conventional pi-mode rf photoinjectors typically use magnetic solenoids for emittance compensation. This provides independent focusing strength, but can complicate rf power feed placement, introduce asymmetries (due to coil crossovers), and greatly increase the cost of the photoinjector. Cathode-region focusing can also provide for a form of emittance compensation. Typically this method strongly couples focusing strength to the field gradient on the cathode, however, and also requires altering the longitudinal position of the cathode to change the focusing. We propose a new method for achieving cathode-region variable-strength focusing for emittance compensation. The new method reduces the coupling to the gradient on the cathode, and does not require a change in the longitudinal position of the cathode. Expected performance for an S-band system is similar to conventional solenoid-based designs. This paper presents the results of rf cavity and beam dynamics simulations of the new design.

  10. Dual arc penning ion source gas flow experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, E.D.; Lord, R.S.; Mallory, M.L.; Antaya, T.A.

    1984-01-01

    Support gas, when added directly to an arc or admitted to an auxiliary chamber of a two-arc chamber ion source, increases the beam intensity for multicharged ions such as /sup 16/O/sup 5 +/. To clarify the mechanism of this intensity increase, gas flow rates from the auxiliary chamber to the main chamber have been measured by using the ORIC cyclotron as a mass spectrometer. The results show that only about three percent of the gas admitted to the auxiliary chamber reaches the main chamber. One can then infer that the improved operation probably results from the stabilizing effect of heating the common cathodes with the auxiliary arc and/or the more favorable distribution of the support gas to the part of the main arc close to the cathodes.

  11. 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...

  12. Water-vortex-stabilized electric arc: III. Radial energy transport, determination of water-vapour-boundary and arc performance

    Science.gov (United States)

    Jenista, Jirí

    2003-12-01

    This paper is concerned with numerical modelling of an electric arc stabilized by a water vortex. The two-dimensional axisymmetric model presented includes the arc discharge area between the cathode and the outlet nozzle of the water plasma torch. The aims of the numerical simulations are: (1) to assess the influence of radial position of the water-vapour-boundary in the discharge chamber on arc performance and overall radial energy transport within the arc; (2) to determine the most probable mass flow rates and radii of the water-vapour-boundary in the discharge chamber for a prescribed current; (3) to demonstrate arc performance for two radiation models involved; and (4) to estimate validity of local thermodynamic equilibrium (LTE) conditions within the arc column. The rate of evaporation of water is calculated from the conduction and radiation heat fluxes at the water vapour surface for the specified mass flow rate. The behaviour of such an arc has been studied for a range of current 300-600 A. It is shown that changes of bulk magnitudes of different terms in the momentum and energy equations within the arc column as a function of arc radius enable us to reveal transitions of temperature and velocity fields from one steady state to a qualitatively different one. The best fit between experiment and numerical simulation for all currents exists for the mean arc radius ~3.3 mm. Deviations from LTE within the arc column are estimated with the criteria for kinetic equilibrium and spatial temperature gradients.

  13. Synthesis of branched, nano channeled, ultrafine and nano carbon tubes from PET wastes using the arc discharge method

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Berkmans, A.; Jagannatham, M. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu (India); Priyanka, S. [Department of Electrical and Electronics Engineering, MS Ramaiah Institute of Technology, Bangalore 560054, Karnataka (India); Haridoss, Prathap, E-mail: prathap@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu (India)

    2014-11-15

    Highlights: • Polymer wastes are converted into ultrafine and nano carbon tubes and spheres. • Simple process with a minimal processing time. • It is a catalyst free and solvent free approach. • This process forms branched ultrafine carbon tubules with nano channels. - Abstract: Upcycling polymer wastes into useful, and valuable carbon based materials, is a challenging process. We report a novel catalyst-free and solvent-free technique for the formation of nano channeled ultrafine carbon tubes (NCUFCTs) and multiwalled carbon nanotubes (MWCNTs) from polyethylene terephthalate (PET) wastes, using rotating cathode arc discharge technique. The soot obtain from the anode contains ultrafine and nano-sized solid carbon spheres (SCS) with a mean diameter of 221 nm and 100 nm, respectively, formed at the lower temperature region of the anode where the temperature is approximately 1700 °C. The carbon spheres are converted into long “Y” type branched and non-branched NCUFCTs and MWCNTs at higher temperature regions where the temperature is approximately 2600 °C, with mean diameters of 364 nm and 95 nm, respectively. Soot deposited on the cathode is composed of MWCNTs with a mean diameter of 20 nm and other nanoparticles. The tubular structures present in the anode are longer, bent and often coiled with lesser graphitization compared to the nanotubes in the soot on the cathode.

  14. Cesiated hollow cathodes in the multicusp ion source

    Science.gov (United States)

    Belchenko, Yu. I.; Oka, Y.; Hamabe, M.; Kaneko, O.; Krivenko, A.; Takeiri, Y.; Tsumori, K.; Osakabe, M.; Ikeda, K.; Asano, E.; Kawamoto, T.

    2002-02-01

    A cesiated hydrogen hollow cathode (CHC) was tested for plasma injection in the multicusp negative ion source (MS). The CHC arc with hydrogen feed and cesium seeding through the CHC volume was explored. One cathode unit (40 mm length, 19 mm in diameter, emission opening area 1-3 mm2) with no special cooling provided the MS discharge operation with direct current up to 30 A, and up to 60 A in the long-pulse mode. High efficiency of negative ion production in the MS discharge, driven by a CHC plasma injection was recorded.

  15. An improved reservoir oxide cathode

    Science.gov (United States)

    Wang, Xiaoxia; Liao, Xianheng; Luo, Jirun; Zhao, Qinglan

    2005-09-01

    A new type of reservoir oxide cathode has been developed in IECAS. The emission characteristics of the cathode are tested. The results show the new cathode has higher emission current density and better resistance to poisoning at same operating condition compared with those of conventional reservoir oxide cathode.

  16. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

    Directory of Open Access Journals (Sweden)

    Grzegorz Raniszewski

    2017-02-01

    Full Text Available One of the most common methods of carbon nanotubes (CNTs synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs. It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  17. 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.

  18. Cathodic hydrodimerization of nitroolefins

    OpenAIRE

    Michael Weßling; Hans J. Schäfer

    2015-01-01

    Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation...

  19. Note: Triggering behavior of a vacuum arc plasma source.

    Science.gov (United States)

    Lan, C H; Long, J D; Zheng, L; Dong, P; Yang, Z; Li, J; Wang, T; He, J L

    2016-08-01

    Axial symmetry of discharge is very important for application of vacuum arc plasma. It is discovered that the triggering method is a significant factor that would influence the symmetry of arc discharge at the final stable stage. Using high-speed multiframe photography, the transition processes from cathode-trigger discharge to cathode-anode discharge were observed. It is shown that the performances of the two triggering methods investigated are quite different. Arc discharge triggered by independent electric source can be stabilized at the center of anode grid, but it is difficult to achieve such good symmetry through resistance triggering. It is also found that the triggering process is highly correlated to the behavior of emitted electrons.

  20. Note: Triggering behavior of a vacuum arc plasma source

    Energy Technology Data Exchange (ETDEWEB)

    Lan, C. H., E-mail: lanchaohui@163.com; Long, J. D.; Zheng, L.; Dong, P.; Yang, Z.; Li, J.; Wang, T.; He, J. L. [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-08-15

    Axial symmetry of discharge is very important for application of vacuum arc plasma. It is discovered that the triggering method is a significant factor that would influence the symmetry of arc discharge at the final stable stage. Using high-speed multiframe photography, the transition processes from cathode-trigger discharge to cathode-anode discharge were observed. It is shown that the performances of the two triggering methods investigated are quite different. Arc discharge triggered by independent electric source can be stabilized at the center of anode grid, but it is difficult to achieve such good symmetry through resistance triggering. It is also found that the triggering process is highly correlated to the behavior of emitted electrons.

  1. Numerical and experimental study of transferred arcs in argon

    Energy Technology Data Exchange (ETDEWEB)

    Bini, R [Department of Mechanical Engineering, Politecnico di Milano, Via Bonardi 9, 20133 Milan (Italy); Monno, M [Department of Mechanical Engineering, Politecnico di Milano, Via Bonardi 9, 20133 Milan (Italy); Boulos, M I [Centre de Recherche en Energie, Plasma et Electrochimie (CREPE), Department de Genie Chimique Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, J1K1R2 (Canada)

    2006-08-07

    The bidimensional model of the electric arc is enhanced with the plasma-electrodes interaction to predict the properties and the energy distribution of an argon arc operating with current intensities between 100 and 200 A and electrode gaps of 10 and 20 mm. An adaptive numerical insulation is applied to the cathode, to properly simulate its thermionic emission mechanism and overcome the dependence on empirical distributions of the current density at its tip. The numerical results are quantitatively compared with the data obtained from calorimetric and spectroscopical measurements, performed on a device which generates a transferred arc between a water cooled copper anode and a thoriated tungsten cathode enclosed in a stainless steel chamber. The calculation of the heat fluxes towards the electrodes permits to determine the amount of power delivered to each component of the arc system (the anode, the cathode assembly and the chamber) and to evaluate the overall efficiency of the process for different configurations. The agreement between theory and data, over the range of parameters investigated, is sensible both in the temperature profiles and in the energy distributions. In such configurations, the conduction from the hot gas is the most relevant term in the overall heat transferred to the anode, but it is the electron transfer which rules the heat transfer in the arc attachment zone. The arc attachment radius is also dependent on the process parameters and increases with the arc current (from approximately 5 mm at 100 A to 7 mm at 200 A) and the arc length. However the maximum heat flux reached on the axis decreases increasing the gap between the electrodes, although more power is delivered to the anode due to the radial spreading of the plasma. A 10 mm 200 A argon arc releases to the anode about 2.6 kW, which corresponds to 75% of the total arc power available. If the arc is extended to 20 mm the power transferred rises by nearly 350 W, but the overall

  2. Cathode materials review

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Claus, E-mail: danielc@ornl.gov; Mohanty, Debasish, E-mail: danielc@ornl.gov; Li, Jianlin, E-mail: danielc@ornl.gov; Wood, David L., E-mail: danielc@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS6472 Oak Ridge, TN 37831-6472 (United States)

    2014-06-16

    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 LiCoO{sub 2} 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.

  3. Cathode materials review

    Science.gov (United States)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    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.

  4. Characteristics of Plasma Spraying Torch with a Hollow Cathode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A kind of plasma spraying torch with a hollow cathode is described in this paper.The plasma torch can be used for axial powder injection in plasma spray studies. The arc characteristics of the plasma torch with various gas flowrates, different gas media, are presented. The mathematical modeling and computational method are developed for predicting the temperature and velocity field inside the plasma torch.

  5. CHARACTERISTICS OF NEW CATHODE MATERIAL FOR LTSOFC INVESTIGATED BY IMPEDANCE SPECTROSCOPY

    Institute of Scientific and Technical Information of China (English)

    彭冉冉; 杨立寨; 毛宗强; 谢晓峰

    2004-01-01

    The characteristics of a new Li-NiO cathode were investigated. The crystal structure of Li-NiO was explored by XRD. Electrochemical behaviors of Li-NiO composite cathode were revealed by impedance spectroscopy from 400℃ to 650℃. The diameter of deformed arc increased with the decrease of temperature. Above the melting point of the eutectic salt in composite electrolyte, the Li-NiO curves are similar with two deformed semicircular arcs at high frequency which partially overlaps each other and corresponds...

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

    CERN Document Server

    Semenov, A P

    2001-01-01

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

  7. Gas arc constriction for plasma arc welding

    Science.gov (United States)

    McGee, William F. (Inventor); Rybicki, Daniel J. (Inventor)

    1994-01-01

    A welding torch for plasma arc welding apparatus has an inert gas applied circumferentially about the arc column externally of the constricting nozzle so as to apply a constricting force on the arc after it has exited the nozzle orifice and downstream of the auxiliary shielding gas. The constricting inert gas is supplied to a plenum chamber about the body of the torch and exits through a series of circumferentially disposed orifices in an annular wall forming a closure at the forward end of the constricting gas plenum chamber. The constricting force of the circumferential gas flow about the arc concentrates and focuses the arc column into a more narrow and dense column of energy after exiting the nozzle orifice so that the arc better retains its energy density prior to contacting the workpiece.

  8. An Arc in Saturn's G Ring

    Science.gov (United States)

    Burns, Joseph A.; Hedman, M.; Tiscareno, M.; Porco, C.; Jones, G.; Roussos, E.; Krupp, N.

    2006-09-01

    The G ring is a narrow, faint ring located between the orbits of Janus and Mimas. Approximately 4000 km wide, it has a strongly asymmetric brightness profile with a sharp inner edge between 167,000 km and 168,000 km from Saturn's center and a more diffuse outer part. In Cassini images, a portion of the ring contains a bright arc that abuts the G-ring's inner edge and extends over 30 degrees in longitude. By tracking this arc over the first two years of the Cassini Mission, we find its orbital period is 0.80813 day, corresponding to a semi-major axis of 167,496 km. Since this location places the arc within 6 km of the Mimas 7:6 Co-rotation Eccentricity Resonance and within 12 km of the Mimas 7:6 Inner Lindblad Resonance, the arc is likely confined in longitude by Mimas just as Neptune's ring arcs are held in place by Galatea. The arc's longitude relative to Mimas is consistent with this model. Cassini now has the opportunity to study the dynamics of this sort of system in detail over a period of years. The arc, which may be the debris of a fragmented moon, may also supply the particles found in the rest of the G ring; micron-sized grains drift outwards by non-gravitational processes in this region. The G-ring is responsible for a broad, relatively modest decrease in the fluxes of magnetospheric charged particles. When Cassini passed over the G ring in the vicinity of the arc, on September 5, 2005, the MIMI instrument detected a particularly sharp and deep charged particle absorption signature. Such a pronounced charged particle absorption was not seen in the other G-ring passages that occurred longitudinally far from the arc. The nature of this absorption provides constraints on the population of large particles in this arc.

  9. Gas tungsten arc welder with electrode grinder

    Science.gov (United States)

    Christiansen, David W.; Brown, William F.

    1984-01-01

    A welder for automated closure of fuel pins by a gas tungsten arc process in which a rotating length of cladding is positioned adjacent a welding electrode in a sealed enclosure. An independently movable axial grinder is provided in the enclosure for refurbishing the used electrode between welds.

  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. 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...

  12. 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...

  13. Simulation of Low-Voltage Arc Plasma During Contact Opening Progress

    Institute of Scientific and Technical Information of China (English)

    WU Yi; RONG Ming-zhe; SUN Zhi-qiang; WANG Xiao-hua; LI Jian; WANG Jian-hua

    2007-01-01

    This paper focuses on the simulation of the low-voltage arc with an opening contact.A controllable experiment setup with a rotating contact is designed to investigate the arc behaviour.Supported by the experiment,the phenomena of arc elongation and commutation in the case of rotating contact are simulated with the dynamic grid technique introduced.Under the given condition of the external magnetic field and the contact rotating velocity,the stagnation and rapid jump of two arc roots are observed by the calculated and experimental arc root displacement.The voltage of arc column can be divided into four phases and its sharp rising progress comes from the increase of the displacement difference between two arc roots in x direction.

  14. Plasma-chemical reactor based on a low-pressure pulsed arc discharge for synthesis of nanopowders

    Science.gov (United States)

    Karpov, I. V.; Ushakov, A. V.; Lepeshev, A. A.; Fedorov, L. Yu.

    2017-01-01

    A reactor for producing nanopowders in the plasma of a low-pressure arc discharge has been developed. As a plasma source, a pulsed cold-cathode arc evaporator has been applied. The design and operating principle of the reactor have been described. Experimental data on how the movement of a gaseous mixture in the reactor influences the properties of nanopowders have been presented.

  15. 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.

  16. Electrochemical cells and cathode materials

    Energy Technology Data Exchange (ETDEWEB)

    Skarstad, P.M.; Untereker, D.F.; Meritt, D.R.

    1988-08-02

    This patent describes an electrochemical cell comprising anode and cathode means in operative relationship. The cathode means comprising a cathode material comprised of, at least in part: a halogen component selected from the group consisting of iodine, bromine, iodine bromide and mixtures thereof, and poly(ethylene oxide), at least in part.

  17. Generation of low-temperature plasma by low-pressure arcs for synthesis of nitride coatings

    Science.gov (United States)

    Krysina, O. V.; Koval, N. N.; Lopatin, I. V.; Shugurov, V. V.; Kovalsky, S. S.

    2016-01-01

    Experiments were performed to study gas, metal, and mixed metal-gas plasmas. The plasmas were generated with the use of an arc evaporator and a gas-plasma source with a hot filament and hollow cathode that were operated independently or simultaneously. It has been revealed that the arc current of gas-plasma source affects the parameters of the metal-gas plasma and the element concentrations in the coatings. It has been demonstrated that the characteristics of the nitride coatings produced by plasma-assisted vacuum-arc deposition can be controlled by varying the parameters of the arc in the gas-plasma source.

  18. Effect of acoustic field parameters on arc acoustic binding during ultrasonic wave-assisted arc welding.

    Science.gov (United States)

    Xie, Weifeng; Fan, Chenglei; Yang, Chunli; Lin, Sanbao

    2016-03-01

    As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius.

  19. 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

  20. Investigation of firing properties of a vacuum arcs triggered by plasma injection

    Energy Technology Data Exchange (ETDEWEB)

    Bernardet, H.; Godechot, X.; Riviere, C. [SODERN, Limeil-Brevannes (France)

    1996-08-01

    The firing characteristic of a vacuum arc, by means of plasma injection, is described. In this method, a plasma, created from a trigger device, plumes away to the space between the cathode and anode. As the plasma is quasi-neutral, the electrostatic field is concentrated across the sheath at the surface of the cathode, thus, creating a high electrical field. As a result, a vacuum arc fires between the cathode and anode. The authors have investigated the firing rate as a function of the trigger cathode distance, trigger current, the anode-cathode distance and voltage. They found a firing rate between 90 to 100% for a trigger current in the range of 400-1200 A, the trigger pulse length was 4 ps, and the trigger-cathode distance was 1.6 to 3.6 cm. The anode cathode gap length changes the firing rate to a low extent for values between 2 to 5 cm. The anode cathode voltage do not change the firing rate. The effect of a magnetic field applied axially over the trigger have also been investigated. Using a version of a highly reliable trigger, the authors were able to deposit stainless steel, copper, carbon and molybdenum, thin films.

  1. Simple filtered repetitively pulsed vacuum arc plasma source

    Science.gov (United States)

    Chekh, Yu.; Zhirkov, I. S.; Delplancke-Ogletree, M. P.

    2010-02-01

    A very simple design of cathodic filtered vacuum arc plasma source is proposed. The source without filter has only four components and none of them require precise machining. The source operates in a repetitively pulsed regime, and for laboratory experiments it can be used without water cooling. Despite the simple construction, the source provides high ion current at the filter outlet reaching 2.5% of 400 A arc current, revealing stable operation in a wide pressure range from high vacuum to oxygen pressure up to more than 10-2 mbar. There is no need in complicated power supply system for this plasma source, only one power supply can be used to ignite the arc, to provide the current for the arc itself, to generate the magnetic field in the filter, and provide its positive electric biasing without any additional high power resistance.

  2. Determination of work functions near melting points of refractory metals by using a direct-current arc

    Science.gov (United States)

    Gordon, W. A.; Chapman, G. B., II

    1972-01-01

    Effective work functions of refractory metals at temperatures near their melting points were determined by using a direct-current arc. A metal wire connected as the cathode was melted by striking an arc discharge in an argon atmosphere. A melted sphere was formed with a definite emitting area which was calculated from the sphere diameter measured after terminating the arc. Effective work functions were calculated from the Richardson-Dushman equation by using this emission area. The procedure is experimentally advantageous because surface cleanliness of the specimen is not critical, high vacuum is not required, and the anode-cathode spacing is not critical.

  3. Identification by force modulation microscopy of nanoparticles generated in vacuum arcs Identification by force modulation microscopy of nanoparticles generated in vacuum arcs

    OpenAIRE

    M. Arroyave Franco

    2006-01-01

    An alternative method based on force modulation microscopy (FMM) for identification of nanoparticles produced in the plasma generated by the cathode spots of vacuum arcs is presented. FMM technique is enabled for the detection of variations in the mechanical properties of a surface with high sensitiveness. Titanium nitride (TiN) coatings deposited on oriented silicon by pulsed vacuum arc process have been analyzed. AFM (Atomic Force Microscopy) and FMM images were simultaneously obtained, and...

  4. Simulation and Experimental Study of Arc Column Expansion After Ignition in Low-Voltage Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    MA Qiang; RONG Mingzhe; WU Yi; XU Tiejun; SUN Zhiqiang

    2008-01-01

    The dynamicprocess of arc pressure and corresponding arc column expansion, which is the main feature after arc ignition and has a significant effect on the breaking behaviour of low -voltage circuit breakers, is studied. By constructing a three dimensional mathematical model of air arc plasma and adopting the Control Volume Method, the parameters of arc plasma including temperature and pressure axe obtained. The variations of pressure field and temperature field with time are simulated. The result indicates that there are six stages for the process of arc column expansion according to the variation of pressure in arc chamber. In the first stage, the maximal pressure locates in the region close to cathode, and in the second stage the maximal pressure shifts to the region close to the anode. In the third stage, the pressure difference between the middle of arc column and the ambient gas is very large, so the arc column begins to expand apparently. In the fourth stage, the pressure wave propagates towards both ends and the maximal pressure appears at the two ends when the pressure wave reaches both sidewalls. In the fifth stage, the pressure wave is reflected and collides in the middle of the arc chamber. In the last stage, the propagation and reflection of pressure wave will repeat several times until a steady burning state is reached. In addition, the experimental results of arc column expansion, corresponding to the arc pressure variation, are presented to verify the simulation results.

  5. Water-vortex-stabilized electric arc: III. Radial energy transport, determination of water-vapour-boundary and arc performance

    Energy Technology Data Exchange (ETDEWEB)

    Jenista, Jiri [Institute of Plasma Physics ASCR, Za Slovankou 3, PO Box 17, Prague 8, 182 21 (Czech Republic)

    2003-12-07

    This paper is concerned with numerical modelling of an electric arc stabilized by a water vortex. The two-dimensional axisymmetric model presented includes the arc discharge area between the cathode and the outlet nozzle of the water plasma torch. The aims of the numerical simulations are: (1) to assess the influence of radial position of the water-vapour-boundary in the discharge chamber on arc performance and overall radial energy transport within the arc; (2) to determine the most probable mass flow rates and radii of the water-vapour-boundary in the discharge chamber for a prescribed current; (3) to demonstrate arc performance for two radiation models involved; and (4) to estimate validity of local thermodynamic equilibrium (LTE) conditions within the arc column. The rate of evaporation of water is calculated from the conduction and radiation heat fluxes at the water vapour surface for the specified mass flow rate. The behaviour of such an arc has been studied for a range of current 300-600 A. It is shown that changes of bulk magnitudes of different terms in the momentum and energy equations within the arc column as a function of arc radius enable us to reveal transitions of temperature and velocity fields from one steady state to a qualitatively different one. The best fit between experiment and numerical simulation for all currents exists for the mean arc radius {approx} 3.3 mm. Deviations from LTE within the arc column are estimated with the criteria for kinetic equilibrium and spatial temperature gradients.

  6. Some features of horizontally oriented low-current electric arc in air

    Energy Technology Data Exchange (ETDEWEB)

    Tazmeev, Kh. K., E-mail: tazmeevh@mail.ru [Kazan (Volga Region) Federal University, Naberezhnye Chelny Institute (Russian Federation); Tazmeev, B. Kh., E-mail: tazmeevb@mail.ru [National Research Technical University, Naberezhnye Chelny Branch (Russian Federation)

    2016-01-15

    The properties of an electric arc operating in open air at currents of lower than 1 A were studied experimentally. The rod cathode was oriented horizontally. Cylindrical rods and plane plates either installed strictly vertically in front of the cathode end or tilted at a certain angle served as the anode. It is shown that, with such an electrode configuration, it is possible to form a discharge channel much longer than the electrode gap length. Regimes of regular oscillations are revealed, and conditions for their appearance are established. The electric field strength in the arc column and the electron temperature near the anode are calculated.

  7. Wire + Arc Additive Manufacturing

    OpenAIRE

    Williams, Stewart W.; Martina, Filomeno; Addison, Adrian C.; Ding, Jialuo; Pardal, Goncalo; Colegrove, Paul A.

    2016-01-01

    Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to ...

  8. Characterization of the behaviour of the electric arc during VAR of a Ti alloy

    Science.gov (United States)

    Chapelle, P.; Noël, C.; Risacher, A.; Jourdan, J.; Jourdan, J.; Jardy, A.

    2016-07-01

    In this paper, we report experimental results based on the direct observation of the electric arc behaviour during vacuum arc remelting of a Ti alloy. These results were obtained in a specifically instrumented industrial furnace using high speed framing camera and optical emission spectroscopy, for a current density level of the order of 10 A/cm2 and a gap length of a few centimetres. It was observed that the arc exhibits a similar operating regime to that described in the literature for the case of Inconel 718 and Zr alloy electrodes. The arc structure corresponds essentially to that of a diffuse metal vapor arc with separate and rapidly moving cathode spots. Several critical parameters of the cathode spots, including their current, size and velocity, and of the interelectrode plasma were evaluated. Also, the interactions between the arc operation and the transfer of metal drops in the interelectrode gap were investigated. Three modes of transfer of the liquid metal drops in the interelectrode gap have been identified depending on the gap length: drop falling, drip short and drop erosion induced by the cathode spots.

  9. Welding arc plasma physics

    Science.gov (United States)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  10. Effect of arc current on droplet ejection from tungsten-based electrode in multiphase AC arc

    Science.gov (United States)

    Hashizume, Taro; Tanaka, Manabu; Watanabe, Takayuki

    2017-05-01

    The dynamic behavior of droplet ejection from a tungsten electrode was successfully visualized using a high-speed camera and an appropriate band-pass filter. The effect of arc current on droplet ejection was investigated to understand the electrode erosion mechanism in the multiphase AC arc. The rate of erosion by droplet ejection increased with increasing current. This result was examined on the basis of the time variation in forces on a pending droplet at the electrode tip during the AC cycle. The relationship among electromagnetic force, surface tension, and ion pressure on the molten tip during the cathodic period is crucial for controling droplet ejection. The molten tip becomes hemispherical forming the pending droplet with an increase in the instantaneous value of arc current during the AC cycle. The pending droplet detaches from the electrode surface when electromagnetic force becomes the dominant force. Consequently, a higher rate of erosion by droplet ejection with a higher arc current resulted from a stronger electromagnetic force.

  11. WSTF electrical arc projects

    Science.gov (United States)

    Linley, Larry

    1994-09-01

    The objectives of these projects include the following: validate method used to screen wire insulation with arc tracking characteristics; determine damage resistance to arc as a function of source voltage and insulation thickness; investigate propagation characteristics of Kapton at low voltages; and investigate pyrolytic properties of polyimide insulated (Kapton) wire for low voltage (less than 35 VDC) applications. Supporting diagrams and tables are presented.

  12. Nanostructured lanthanum manganate composite cathode

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  13. Commissioning and first clinical application of mARC treatment

    Energy Technology Data Exchange (ETDEWEB)

    Dzierma, Yvonne; Nuesken, Frank G.; Kremp, Stephanie; Palm, Jan; Licht, Norbert P.; Ruebe, Christian [Universitaetsklinikum des Saarlandes, Klinik fuer Strahlentherapie und Radioonkologie, Homburg, Saarland (Germany)

    2014-11-15

    weniger als 1 % ab. In der 3D-Dosisverteilung erfuellen ueber 95 % der Punkte das 3D-Gamma-Kriterium (3 % lokale Dosis, 3 mm Abstand fuer alle Werte > 20 % der Maximaldosis). Die patienten-spezifische Verifikation der mARC-Dosisverteilung mit den Planberechnungen hat eine vergleichbare Uebereinstimmung. Die Behandlungszeiten liegen zwischen 2 und 5 Minuten fuer eine Rotation. Unseres Wissens ist dies der erste Bericht ueber eine klinische Anwendung der mARC-Technik. Der mARC ermoeglicht eine signifikante Zeitersparnis. Mit einer Rotation von wenigen Minuten Dauer kann eine mit der IMRT vergleichbare Dosisverteilung erzielt werden. (orig.)

  14. Cathodic hydrodimerization of nitroolefins

    Directory of Open Access Journals (Sweden)

    Michael Weßling

    2015-07-01

    Full Text Available Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.

  15. Cathodic hydrodimerization of nitroolefins.

    Science.gov (United States)

    Weßling, Michael; Schäfer, Hans J

    2015-01-01

    Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C-C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.

  16. Investigation of the flickering of La{sub 2}O{sub 3} and ThO{sub 2} doped tungsten cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Hoebing, T.; Hermanns, P.; Bergner, A.; Ruhrmann, C.; Mentel, J.; Awakowicz, P. [Ruhr University Bochum, Electrical Engineering and Plasma Technology, 44780 Bochum (Germany); Traxler, H.; Wesemann, I.; Knabl, W. [Plansee SE, Metallwerk-Plansee-Str. 71, 6600 Reutte (Austria)

    2015-07-14

    Short-arc lamps are equipped with tungsten electrodes due to their ability to withstand a high thermal load during operation. Nominal currents of more than one hundred amperes lead to a cathode tip temperature near the melting point of tungsten. To reduce the electrode temperature and, thereby, to increase the maintenance of such lamps, ThO{sub 2} or tentatively La{sub 2}O{sub 3} are added to the electrode material. They generate a reduced work function by establishing a monolayer of emitter atoms on the tungsten surface. Emitter enrichments on the lateral surface of doped cathodes are formed. They are traced back to transport mechanisms of emitter oxides in the interior of the electrode and on the electrode surface in dependence of the electrode temperature and to the redeposition of vaporized and ionized emitter atoms onto the cathode tip by the electric field in front. The investigation is undertaken by means of glow discharge mass spectrometry, scanning electron microscope images, energy dispersive x-ray spectroscopy, and through measurements of the optical surface emissivity. The effect of emitter enrichments on the stability of the arc attachment is presented by means of temporally resolved electrode temperature measurements and by measurements of the luminous flux from the cathode-near plasma. They show that the emitter enrichments on the lateral surface of the cathode are attractive for the arc attachment if the emitter at the cathode tip is depleted. In this case, it moves along the lateral surface from the cathode tip to sections of the cathode with a reduced work function. It induces a temporary variation of the cathode tip temperature and of the light intensity from the cathode-near plasma, a so-called flickering. In particular, in case of lanthanated cathodes, strong flickering is observed.

  17. A highly reliable trigger for vacuum ARC plasma source

    Energy Technology Data Exchange (ETDEWEB)

    Bernardet, H.; Godechot, X.; Jarjat, F. [SODERN, Limeil-Brevannes (France)

    1996-08-01

    The authors have developed a reliable electrical trigger and its associated circuitry to fire vacuum arc plasma or ion source. They tested different embodiments of the trigger device in order to get a highly reliable one, which is able to perform more than 1.2 x 10{sup 6} shots at 60 A and 6.5 ps pulse length. The evolution of the ion current emitted has been recorded as a function of the number of shots. They have also investigated in which direction the plasma jet is emitted : axially or radially. This device can be used to fire a vacuum arc plasma or ion source by plasma injection. It has obvious advantage to be placed outside the cathode and therefore would ease maintenance of vacuum arc devices.

  18. Compact lanthanum hexaboride hollow cathode.

    Science.gov (United States)

    Goebel, Dan M; Watkins, Ronald M

    2010-08-01

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

  19. Transient Response of Arc Temperature and Iron Vapor Concentration Affected by Current Frequency with Iron Vapor in Pulsed Arc

    Science.gov (United States)

    Tanaka, Tatsuro; Maeda, Yoshifumi; Yamamoto, Shinji; Iwao, Toru

    2016-10-01

    TIG arc welding is chemically a joining technology with melting the metallic material and it can be high quality. However, this welding should not be used in high current to prevent cathode melting. Thus, the heat transfer is poor. Therefore, the deep penetration cannot be obtained and the weld defect sometimes occurs. The pulsed arc welding has been used for the improvement of this defect. The pulsed arc welding can control the heat flux to anode. The convention and driving force in the weld pool are caused by the arc. Therefore, it is important to grasp the distribution of arc temperature. The metal vapor generate from the anode in welding. In addition, the pulsed current increased or decreased periodically. Therefore, the arc is affected by such as a current value and current frequency, the current rate of increment and the metal vapor. In this paper, the transient response of arc temperature and the iron vapor concentration affected by the current frequency with iron vapor in pulsed arc was elucidated by the EMTF (ElectroMagnetic Thermal Fluid) simulation. As a result, the arc temperature and the iron vapor were transient response as the current frequency increase. Thus, the temperature and the electrical conductivity decreased. Therefore, the electrical field increased in order to maintain the current continuity. The current density and electromagnetic force increased at the axial center. In addition, the electronic flow component of the heat flux increased at the axial center because the current density increased. However, the heat conduction component of the heat flux decreased.

  20. Synthesis method for ultrananocrystalline diamond in powder employing a coaxial arc plasma gun

    Science.gov (United States)

    Naragino, Hiroshi; Tominaga, Aki; Hanada, Kenji; Yoshitake, Tsuyoshi

    2015-07-01

    A new method that enables us to synthesize ultrananocrystalline diamond (UNCD) in powder is proposed. Highly energetic carbon species ejected from a graphite cathode of a coaxial arc plasma gun were provided on a quartz plate at a high density by repeated arc discharge in a compact vacuum chamber, and resultant films automatically peeled from the plate were aggregated and powdered. The grain size was easily controlled from 2.4 to 15.0 nm by changing the arc discharge energy. It was experimentally demonstrated that the proposed method is a new and promising method that enables us to synthesize UNCD in powder easily and controllably.

  1. An analysis of the anomalous high-current cathode emission in pseudospark and back-of-the-cathode lighted thyratron switches

    Science.gov (United States)

    Hartmann, W.; Dominic, V.; Kirkman, G. F.; Gundersen, M. A.

    1989-06-01

    An analysis of the anomalously large cathode emission recently observed in the superdense glow of pseudospark and back-lighted thyratrons is presented. These switches are low-pressure (27 PaH2) glow-discharge pulsed-power devices. After operating at peak discharge currents of 6 to 8 kA and pulse durations of 0.5 to 1 microsec., the surface surrounding the cathode hole was found to have been homogeneously melted within a radius of approx. 4 mm indicating that the discharge is a superdense glow discharge, not an arc, with a cross-sectional area on the order of 1 sq cm. This conclusion is also supported by streak camera measurements. The current density at the cathode surface under these conditions is 5 to 10 kA/sq cm, several orders of magnitude larger than that of thermionic cathodes in common thyratrons. This high-current density is explained by intense cathode heating from a high-current density ion beam produced in the cathode fall during the initial stage of current buildup. The surface heating resulting from this beam yields a significant field-enhanced thermionic emission of electrons.

  2. Electromagnetic Characteristic of Twin-wire Indirect Arc Welding

    Institute of Scientific and Technical Information of China (English)

    SHI Chuanwei; ZOU Yong; ZOU Zengda; WU Dongting

    2015-01-01

    Traditional welding methods are limited in low heat input to workpiece and high welding wire melting rate. Twin-wire indirect arc(TWIA) welding is a new welding method characterized by high melting rate and low heat input. This method uses two wires:one connected to the negative electrode and another to the positive electrode of a direct-current(DC) power source. The workpiece is an independent, non-connected unit. A three dimensional finite element model of TWIA is devised. Electric and magnetic fields are calculated and their influence upon TWIA behavior and the welding process is discussed. The results show that with a 100 A welding current, the maximum temperature reached is 17 758 K, arc voltage is 14.646 V while maximum current density was 61 A/mm2 with a maximum Lorene force of 84.5mN. The above mentioned arc parameters near the cathode and anode regions are far higher than those in the arc column region. The Lorene force is the key reason for plasma velocity direction deviated and charged particles flowed in the channel formed by the cathode, anode and upper part of arc column regions. This led to most of the energy being supplied to the polar and upper part of arc column regions. The interaction between electric and magnetic fields is a major determinant in shaping TWIA as well as heat input on the workpiece. This is a first study of electromagnetic characteristics and their influences in the TWIA welding process, and it is significant in both a theoretical and practical sense.

  3. Circular-Arc Cartograms

    CERN Document Server

    Kämper, Jan-Hinrich; Nöllenburg, Martin

    2011-01-01

    We present a new circular-arc cartogram model in which countries are drawn with circular arcs instead of straight-line segments. Given a geographic map and values associated with each country in the map, the cartogram is a new map in which the areas of the countries represent the corresponding values. In the circular-arc cartogram model straight-line segments can be replaced with circular arcs in order to achieve the desired areas, while the corners of the polygons defining each country remain fixed. The countries in circular-arc cartograms have the aesthetically pleasing appearance of clouds or snowflakes, depending on whether their edges are bent outwards or inwards. This makes is easy to determine whether a country has grown or shrunk, just by its overall shape. We show that determining whether a given map and area-values can be realized with a circular-arc cartogram is an NP-hard problem. Next we describe a heuristic method for constructing circular-arc cartograms, which uses a max-flow computation on the...

  4. Investigation of cathodic current collection in lithium/manganese dioxide cells by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Merritt, D.R.; Schmidt, C.L. [Medtronic, Inc., Minneapolis, MN (United States)

    1994-12-31

    Contact impedance between pressed composite manganese dioxide cathodes and current collectors has been shown to play an important role in the overall impedance of primary Li/MnO{sub 2} cells. Specifically, this impedance is manifested by an arc in the complex-plane impedance plot, representative of a parallel resistive/capacitive combination, This paper presents the results of a systematic series of experiments designed to better define the relationship between cathodic current collector configuration and cell impedance. A refined equivalent circuit model of the Li/MnO{sub 2} cell is also presented.

  5. Pulsed plasma arc cladding

    Institute of Scientific and Technical Information of China (English)

    龙; 白钢; 李振民; 张赋升; 杨思乾

    2004-01-01

    A prototype of Pulsed Plasma Arc Cladding system was developed, in which single power source supplies both transferred plasma arc (TPA) and non-transferred plasma arc (N-TPA). Both plasmas work in turn in a high frequency controlled by an IGBT connecting nozzle and workpiece. The working frequency of IGBT ranges from 50 ~ 7000Hz, in which the plasmas can work in turn smoothly. Higher than 500 Hz of working frequency is suggested for promotion of cladding quality and protection of IGBT. Drag phenomenon of TPA intensifies as the frequency goes up, which tends to increase the current proportion of TPA and suppress N-TPA. The occupation ratio of IGBT can be regulated from 5% ~ 95%, which balances the power supplies of both plasmas. An occupation ratio higher than 50% gives adequate proportion of arc current for N-TPA to preheat powder.

  6. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

    Science.gov (United States)

    Li, Y J; Wang, Y G; An, B; Xu, H; Liu, Y; Zhang, L C; Ma, H Y; Wang, W M

    2016-01-01

    A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials.

  7. RapidArc treatment verification in 3D using polymer gel dosimetry and Monte Carlo simulation

    DEFF Research Database (Denmark)

    Ceberg, Sofie; Gagne, Isabel; Gustafsson, Helen

    2010-01-01

    arc rotation and a target dose of 3.3 Gy. Magnetic resonance imaging of the gel was carried out using a 1.5 T scanner. The MC dose distributions were calculated using the VIMC-Arc code. The relative absorbed dose differences were calculated voxel-by-voxel, within the volume enclosed by the 90% isodose...

  8. 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.

  9. Influence of axial self-magnetic field component on arcing behavior of spiral-shaped contacts

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Dingyu; Xiu, Shixin, E-mail: xsx@mail.xjtu.edu.cn; Wang, Yi; Liu, Gang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Yali; Bi, Dongli [Shaanxi Baoguang Vacuum Electric Device Co., Ltd., 53 Xibao Road, Baoji 721006 (China)

    2015-10-15

    The transverse magnetic field (TMF) contact design is commonly used in vacuum interrupters. When arcing occurs between the TMF contacts, the contact structure can create a self-induced magnetic field that drives the arc to move and rotate on the contact, and thus local overheating and severe erosion can be avoided. However, TMF contacts could also create an axial self-magnetic component, and the influence of this component on the arc behavior has not been considered to date. In this paper, five different types of Cu-Cr spiral-shaped TMF contacts with three different structures are investigated in a demountable vacuum chamber that contains a high-speed charge-coupled device video camera. It was found that the contact structure greatly influenced the arc behavior, especially in terms of arc rotation and the effective contact area, while contacts with the same slot structure but different diameters showed similar arc behavior and arc motion. The magnetic field distribution and the Lorentz force of each of the three different contact structures are simulated, and the axial self-magnetic field was first taken into consideration for investigation of the TMF contact design. It was found that contact designs that have higher axial self-magnetic field components tend to have arc columns with larger diameters and show poorer arc motion and rotation performance in the experiments.

  10. Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

    Science.gov (United States)

    Wu, Shikai; Xiao, Rongshi

    2015-04-01

    The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

  11. Study of the Material Transfer Characteristics and Surface Morphology Due to Arc Erosion of PtIr Contact Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Saibei; XIE Ming; YANG Youcai; ZHANG Jiming; CHEN Yongtai; LIU Manmen; YANG Yunfeng; HU Jieqiong; CUI Hao

    2012-01-01

    By means of breaking tests on PtIr contact materials via a JF04C contact material testing machine,it was attempted to elucidate the characterstics of the various surface morphology and material transfer after the arc erosion process caused by break arc.The material transfer characteristics appeared in the experiments were concluded and analyzed.Meanwhile,the morphology of the anode and cathode surface were observed and analyzed by SEM.

  12. Liquid cathode primary batteries

    Science.gov (United States)

    Schlaikjer, Carl R.

    1985-03-01

    Lithium/liquid cathode/carbon primary batteries offer from 3 to 6 times the volumetric energy density of zinc/alkaline manganese cells, improved stability during elevated temperature storage, satisfactory operation at temperatures from -40 to +150 °C, and efficient discharge at moderate rates. he lithium/sulfur dioxide cell is the most efficient system at temperatures below 0 °C. Although chemical reactions leading to electrolyte degradation and lithium corrosion are known, the rates of these reactions are slow. While the normal temperature cell reaction produces lithium dithionite, discharge at 60 °C leads to a reduction in capacity due to side reactions involving sulfur dioxide and discharge intermediates. Lithium/thionyl chloride and lithium/sulfuryl chloride cells have the highest practical gravimetric and volumetric energy densities when compared with aqueous and most other nonaqueous systems. For thionyl chloride, discharge proceeds through a series of intermediates to sulfur, sulfur dioxide and lithium chloride. Catalysis, leading to improved rate capability and capacity, has been achieved. The causes of rapid reactions leading to thermal runaway are thought to be chemical in nature. Lithium/sulfuryl chloride cells, which produce sulfur dioxide and lithium chloride on discharge, experience more extensive anode corrosion. An inorganic cosolvent and suitable salt are capable of alleviating this corrosion. Calcium/oxyhalide cells have been studied because of their promise of increased safety without substantial sacrifice of energy density relative to lithium cells. Anode corrosion, particularly during discharge, has delayed practical development.

  13. Microhollow cathode discharges

    Science.gov (United States)

    Schoenbach, K. H.; Moselhy, M.; Shi, W.; Bentley, R.

    2003-07-01

    By reducing the dimensions of hollow cathodes into the hundred micrometer range, stable, direct current, high (atmospheric) pressure glow discharges in rare gases, rare gas-halide mixtures and in air could be generated. The electron energy distribution in these microdischarges is non-Maxwellian, with a pronounced high-energy tail. The high electron energy together with the high gas density, which favors three-body collisions, is the reason for an efficient excimer generation in these microplasmas. Excimer efficiencies from 1% to 9% have been measured for argon, xenon, argon fluoride, and xenon chloride direct current excimer emitters, with a radiant excimer emittance of up to 2 W/cm2 for xenon. Adding small amounts of oxygen to argon has allowed us to generate vacuum ultraviolet line radiation at 130.5 nm with an efficiency approaching 1%. Pulsing xenon discharges with nanosecond electrical pulses has led to an increase in intensity to 15 W/cm2 and to a simultaneous increase in efficiency to more than 20%. Operating the discharges in an abnormal glow mode has allowed us to generate microdischarge arrays without individual ballast. Applications of these plasma arrays are excimer lamps and plasma reactors.

  14. Liquid cathode primary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Schlaikjer, C.R.

    1985-01-15

    Lithium/liquid cathode/carbon primary batteries offer from 3 to 6 times the volumetric energy density of zinc/alkaline manganese cells, improved stability during elevated temperature storage, satisfactory operation at temperatures from -40 to +150/sup 0/C, and efficient discharge at moderate rates. The lithium/sulfur dioxide cell is the most efficient system at temperatures below 0/sup 0/C. Although chemical reactions leading to electrolyte degradation and lithium corrosion are known, the rates of these reactions are slow. While the normal temperature cell reaction produces lithium dithionite, discharge at 60/sup 0/C leads to a reduction in capacity due to side reactions involving sulfur dioxide and discharge intermediates. Lithium/thionyl chloride and lithium/sulfuryl chloride cells have the highest practical gravimetric and volumetric energy densities when compared with aqueous and most other nonaqueous systems. For thionyl chloride, discharge proceeds through a series of intermediates to sulfur, sulfur dioxide and lithium chloride. Catalysis, leading to improved rate capability and capacity, has been achieved. The causes of rapid reactions leading to thermal runaway are thought to be chemical in nature. Lithium/sulfuryl chloride cells, which produce sulfur dioxide and lithium chloride on discharge, experience more extensive anode corrosion. An inorganic cosolvent and suitable salt are capable of alleviating this corrosion. Calcium/oxyhalide cells have been studied because of their promise of increased safety without substantial sacrifice of energy density relative to lithium cells. Anode corrosion, particularly during discharge, has delayed practical development.

  15. Modeling of Arc Force in Plasma Arc Welding

    Institute of Scientific and Technical Information of China (English)

    GAO Zhonglin; HU Shengsun; YIN Fengliang; WANG Rui

    2008-01-01

    A three. dimensional mathematical model for the transferred-type argon arc was developed to describe arc force on the anode surface. The software ANSYS was employed to solve the model. The model includes a part of torch and tungsten electrode to achieve m ore reasonable results. The arc temperature and flow fields were derived. And the influences of welding parameters on arc force were also studied. The simulated results show that arc pressure at the anode are dependent on the welding current, plasma gas flow rate and electrode neck-in, while not sensitive to arc length.

  16. Abrasive-assisted Nickel Electroforming Process with Moving Cathode

    Science.gov (United States)

    REN, Jianhua; ZHU, Zengwei; XIA, Chunqiu; QU, Ningsong; ZHU, Di

    2017-03-01

    In traditional electroforming process for revolving parts with complex profiles, the drawbacks on surface of deposits, such as pinholes and nodules, will lead to varying physical and mechanical properties on different parts of electroformed components. To solve the problem, compositely moving cathode is employed in abrasive-assisted electroforming of revolving parts with complicated profiles. The cathode translates and rotates simultaneously to achieve uniform friction effect on deposits without drawbacks. The influences of current density and translation speed on the microstructure and properties of the electroformed nickel layers are investigated. It is found that abrasive-assisted electroforming with compound cathode motion can effectively remove the pinholes and nodules, positively affect the crystal nucleation, and refine the grains of layer. The increase of current density will lead to coarse microstructure and lower micro hardness, from 325 HV down to 189 HV. While, faster translational linear speed produces better surface quality and higher micro hardness, from 236 HV up to 283 HV. The weld-ability of the electroformed layers are also studied through the metallurgical analysis of welded joints between nickel layer and 304 stainless steel. The electrodeposited nickel layer shows fine performance in welding. The novel compound motion of cathode promotes the mechanical properties and refines the microstructure of deposited layer.

  17. Abrasive-assisted Nickel Electroforming Process with Moving Cathode

    Science.gov (United States)

    REN, Jianhua; ZHU, Zengwei; XIA, Chunqiu; QU, Ningsong; ZHU, Di

    2017-03-01

    In traditional electroforming process for revolving parts with complex profiles, the drawbacks on surface of deposits, such as pinholes and nodules, will lead to varying physical and mechanical properties on different parts of electroformed components. To solve the problem, compositely moving cathode is employed in abrasive-assisted electroforming of revolving parts with complicated profiles. The cathode translates and rotates simultaneously to achieve uniform friction effect on deposits without drawbacks. The influences of current density and translation speed on the microstructure and properties of the electroformed nickel layers are investigated. It is found that abrasive-assisted electroforming with compound cathode motion can effectively remove the pinholes and nodules, positively affect the crystal nucleation, and refine the grains of layer. The increase of current density will lead to coarse microstructure and lower micro hardness, from 325 HV down to 189 HV. While, faster translational linear speed produces better surface quality and higher micro hardness, from 236 HV up to 283 HV. The weld-ability of the electroformed layers are also studied through the metallurgical analysis of welded joints between nickel layer and 304 stainless steel. The electrodeposited nickel layer shows fine performance in welding. The novel compound motion of cathode promotes the mechanical properties and refines the microstructure of deposited layer.

  18. MODELING PARAMETERS OF ARC OF ELECTRIC ARC FURNACE

    Directory of Open Access Journals (Sweden)

    R.N. Khrestin

    2015-08-01

    Full Text Available Purpose. The aim is to build a mathematical model of the electric arc of arc furnace (EAF. The model should clearly show the relationship between the main parameters of the arc. These parameters determine the properties of the arc and the possibility of optimization of melting mode. Methodology. We have built a fairly simple model of the arc, which satisfies the above requirements. The model is designed for the analysis of electromagnetic processes arc of varying length. We have compared the results obtained when testing the model with the results obtained on actual furnaces. Results. During melting in real chipboard under the influence of changes in temperature changes its properties arc plasma. The proposed model takes into account these changes. Adjusting the length of the arc is the main way to regulate the mode of smelting chipboard. The arc length is controlled by the movement of the drive electrode. The model reflects the dynamic changes in the parameters of the arc when changing her length. We got the dynamic current-voltage characteristics (CVC of the arc for the different stages of melting. We got the arc voltage waveform and identified criteria by which possible identified stage of smelting. Originality. In contrast to the previously known models, this model clearly shows the relationship between the main parameters of the arc EAF: arc voltage Ud, amperage arc id and length arc d. Comparison of the simulation results and experimental data obtained from real particleboard showed the adequacy of the constructed model. It was found that character of change of magnitude Md, helps determine the stage of melting. Practical value. It turned out that the model can be used to simulate smelting in EAF any capacity. Thus, when designing the system of control mechanism for moving the electrode, the model takes into account changes in the parameters of the arc and it can significantly reduce electrode material consumption and energy consumption

  19. A review of vacuum ARC ion source research at ANSTO

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P.J.; Noorman, J.T.; Watt, G.C. [ANSTO, Menai (Australia)

    1996-08-01

    The authors talk briefly describes the history and current status of vacuum arc ion source research at the Australian Nuclear Science and Technology Organization (ANSTO). In addition, the author makes some mention of the important role of previous Vacuum Arc Ion Source Workshops in fostering the development of this research field internationally. During the period 1986 - 89, a type of plasma centrifuge known as a vacuum arc centrifuge was developed at ANSTO as part of a research project on stable isotope separation. In this device, a high current vacuum arc discharge was used to produce a metal plasma which was subsequently rotated in an axial magnetic field. The high rotational speeds (10{sup 5} - 10{sup 6} rad sec{sup {minus}1}) achievable with this method produce centrifugal separation of ions with different mass:charge ratios such as isotopic species. The first portent of things to come occurred in 1985 when Dr. Ian Brown visited ANSTO`s Lucas Heights Research Laboratories and presented a talk on the metal vapour vacuum arc (MEVVA) ion source which had only recently been invented by Brown and co-workers, J. Galvin and R. MacGill, at Lawrence Berkeley Laboratory. For those of us involved in vacuum arc centrifuge research, this was an exciting development primarily because the metal vapour vacuum arc plasma source was common to both devices. Thus, a type of arc, which had since the 1930`s been extensively investigated as a means of switching high current loads, had found wider application as a useful plasma source.

  20. Rotating flow

    CERN Document Server

    Childs, Peter R N

    2010-01-01

    Rotating flow is critically important across a wide range of scientific, engineering and product applications, providing design and modeling capability for diverse products such as jet engines, pumps and vacuum cleaners, as well as geophysical flows. Developed over the course of 20 years' research into rotating fluids and associated heat transfer at the University of Sussex Thermo-Fluid Mechanics Research Centre (TFMRC), Rotating Flow is an indispensable reference and resource for all those working within the gas turbine and rotating machinery industries. Traditional fluid and flow dynamics

  1. Electrical characteristics of TIG arcs in argon from non-equilibrium modelling and experiment

    Science.gov (United States)

    Baeva, Margarita; Uhrlandt, Dirk; Siewert, Erwan

    2016-09-01

    Electric arcs are widely used in industrial processes so that a thorough understanding of the arc characteristics is highly important to industrial research and development. TIG welding arcs operated with pointed electrodes made of tungsten, doped with cerium oxide, have been studied in order to analyze in detail the electric field and the arc voltage. Newly developed non-equilibrium model of the arc is based on a complete diffusion treatment of particle fluxes, a generalized form of Ohm's law, and boundary conditions accounting for the space-charge sheaths within the magneto-hydrodynamic approach. Experiments have been carried out for electric currents in the range 5-200 A. The electric arc has been initiated between a WC20 cathode and a water-cooled copper plate placed 0.8 mm from each other. The arc length has been continuously increased by 0.1 mm up to 15 mm and the arc voltage has been simultaneously recorded. Modelling and experimental results will be presented and discussed.

  2. a Bombardment Heated Lanthanum-Hexaboride Thermionic Cathode Electron Gun.

    Science.gov (United States)

    Herniter, Marc Efrem

    This dissertation concerns the development and operation of a high current density Pierce-type electron gun with a 0.75-inch-diameter lanthanum hexaboride (LaB _6) thermionic cathode. The objective of this research is to achieve as high a current density as possible from the lanthanum hexaboride cathode. The topics which are addressed are the cathode heating and control system, the Pierce-type electron gun design, and the high voltage pulsing and isolation system. Lanthanum hexaboride is used as a cathode material in applications where high current density and resistance to chemical poisoning are important. Applications include free electron lasers and high power microwave generation. A four stage Marx generator capable of producing 140-kV-peak pulses with a 16 mus decay time constant is used to pulse the electron gun. The cathode is heated to temperatures greater than 1800 ^circ C by electron bombardment from a tungsten filament. Both temperature-limited and space -charge-limited bombardment methods have been investigated. The temperature-limited method is open-loop unstable. Analog and digital control circuits have been developed to control this instability. A simple heating model has been developed and criteria for constructing a controllable system have been established. An instability in the heating system which is caused by evaporation of lanthanum hexaboride from the cathode is discussed. This evaporation reduces the work function of the bombarding filament and makes the temperature -limited bombardment system uncontrollable. The gun has been operated up to voltages of 115 kV achieving beam current densities of 30 A/cm ^2. The electron gun operated dependably up to voltages of 90 kV achieving temperature-limited currents of 50 A. Due to the high fields at the tip of the Pierce -focusing electrode the gun would usually arc at voltages greater than 90 kV. Electron gun operation has been observed in the temperature-limited and space-charge-limited regimes. The

  3. Arc Heated Scramjet Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Arc Heated Scramjet Test Facility is an arc heated facility which simulates the true enthalpy of flight over the Mach number range of about 4.7 to 8 for free-jet...

  4. ARc Welding (Industrial Processing Series).

    Science.gov (United States)

    ARC WELDING , *BIBLIOGRAPHIES), (*ARC WELDS, BIBLIOGRAPHIES), ALUMINUM ALLOYS, TITANIUM ALLOYS, CHROMIUM ALLOYS, METAL PLATES, SPOT WELDING , STEEL...INERT GAS WELDING , MARAGING STEELS, MICROSTRUCTURE, HEAT RESISTANT ALLOYS, HEAT RESISTANT METALS, WELDABILITY, MECHANICAL PROPERTIES, MOLYBDENUM ALLOYS, NICKEL ALLOYS, RESISTANCE WELDING

  5. 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...

  6. 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....

  7. High-current-density, high brightness cathodes for free electron laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Green, M.C. (Varian Associates, Palo Alto, CA (USA). Palo Alto Microwave Tube Div.)

    1987-06-01

    This report discusses the following topics: brightness and emittance of electron beams and cathodes; general requirements for cathodes in high brightness electron guns; candidate cathode types; plasma and field emission cathodes; true field emission cathodes; oxide cathodes; lanthanum hexaborides cathodes; laser driven thermionic cathodes; laser driven photocathodes; impregnated porous tungsten dispenser cathodes; and choice of best performing cathode types.

  8. Rotating Wavepackets

    Science.gov (United States)

    Lekner, John

    2008-01-01

    Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

  9. Variable polarity arc welding

    Science.gov (United States)

    Bayless, E. O., Jr.

    1991-01-01

    Technological advances generate within themselves dissatisfactions that lead to further advances in a process. A series of advances in welding technology which culminated in the Variable Polarity Plasma Arc (VPPA) Welding Process and an advance instituted to overcome the latest dissatisfactions with the process: automated VPPA welding are described briefly.

  10. Thermal Arc Spray Overview

    Science.gov (United States)

    Hafiz Abd Malek, Muhamad; Hayati Saad, Nor; Kiyai Abas, Sunhaji; Mohd Shah, Noriyati

    2013-06-01

    Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

  11. ALICE: ARC integration

    CERN Document Server

    Anderlik, C; Kleist, J; Peters, A; Saiz, P

    2008-01-01

    AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a modu...

  12. ALICE-ARC integration

    DEFF Research Database (Denmark)

    Anderlik, Csaba; Gregersen, Anders Rhod; Kleist, Josva;

    2008-01-01

    Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The interoperation has two aspects, one is the data...

  13. 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.

  14. Rotational elasticity

    Science.gov (United States)

    Vassiliev, Dmitri

    2017-04-01

    We consider an infinite three-dimensional elastic continuum whose material points experience no displacements, only rotations. This framework is a special case of the Cosserat theory of elasticity. Rotations of material points are described mathematically by attaching to each geometric point an orthonormal basis that gives a field of orthonormal bases called the coframe. As the dynamical variables (unknowns) of our theory, we choose the coframe and a density. We write down the general dynamic variational functional for our rotational theory of elasticity, assuming our material to be physically linear but the kinematic model geometrically nonlinear. Allowing geometric nonlinearity is natural when dealing with rotations because rotations in dimension three are inherently nonlinear (rotations about different axes do not commute) and because there is no reason to exclude from our study large rotations such as full turns. The main result of the talk is an explicit construction of a class of time-dependent solutions that we call plane wave solutions; these are travelling waves of rotations. The existence of such explicit closed-form solutions is a non-trivial fact given that our system of Euler-Lagrange equations is highly nonlinear. We also consider a special case of our rotational theory of elasticity which in the stationary setting (harmonic time dependence and arbitrary dependence on spatial coordinates) turns out to be equivalent to a pair of massless Dirac equations. The talk is based on the paper [1]. [1] C.G.Boehmer, R.J.Downes and D.Vassiliev, Rotational elasticity, Quarterly Journal of Mechanics and Applied Mathematics, 2011, vol. 64, p. 415-439. The paper is a heavily revised version of preprint https://arxiv.org/abs/1008.3833

  15. Motion of polar cap arcs

    Science.gov (United States)

    Hosokawa, K.; Moen, J. I.; Shiokawa, K.; Otsuka, Y.

    2011-01-01

    A statistics of motion of polar cap arcs is conducted by using 5 years of optical data from an all-sky imager at Resolute Bay, Canada (74.73°N, 265.07°E). We identified 743 arcs by using an automated arc detection algorithm and statistically examined their moving velocities as estimated by the method of Hosokawa et al. (2006). The number of the arcs studied is about 5 times larger than that in the previous statistics of polar cap arcs by Valladares et al. (1994); thus, we could expect to obtain more statistically significant results. Polar cap arcs are found to fall into two distinct categories: the By-dependent and By-independent arcs. The motion of the former arcs follows the rule reported by Valladares et al. (1994), who showed that stable polar cap arcs move in the direction of the interplanetary magnetic field (IMF) By. About two thirds of the arcs during northward IMF conditions belong to this category. The latter arcs always move poleward irrespective of the sign of the IMF By, which possibly correspond to the poleward moving arcs in the morning side reported by Shiokawa et al. (1997). At least one third of the arcs belong to this category. The By-dependent arcs tend to move faster when the magnitude of the IMF By is larger, suggesting that the transport of open flux by lobe reconnection from one polar cap compartment to the other controls their motion. In contrast, the speed of the By-independent arcs does not correlate with the magnitude of the By. The motions of both the By-dependent and By-independent arcs are most probably caused by the magnetospheric convection. Convection in the region of By-dependent arcs is affected by the IMF By, which indicates that their sources may be on open field lines or in the closed magnetosphere adjacent to the open-closed boundary, whereas By-independent arcs seem to be well on closed field lines. Hence, the magnetospheric source of the two types of arc may be different. This implies that the mechanisms causing the

  16. Novel Cathodes Prepared by Impregnation Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Eduardo Paz

    2006-09-30

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

  17. An electrochemical impedance spectroscopic study of the electronic and ionic transport properties of LiCoO2 cathode

    Institute of Scientific and Technical Information of China (English)

    ZHUANG QuanChao; XU JinMei; FAN XiaoYong; DONG QuanFeng; JIANG YanXia; HUANG Ling; SUN ShiGang

    2007-01-01

    The storage behavior and process of the first delithiation-lithiation of LiCoO2 cathode were investigated by electrochemical impedance spectroscopy (EIS). The electronic and ionic transport properties of LiCoO2 cathode along with variation of electrode potential were obtained in 1 mol.L-1 LiPF6-EC: DMC:DEC electrolyte solution. It was found that after 9 h storage of the LiCoO2 cathode in electrolyte solutions, a new arc appears in the medium frequency range in Nyquist plots of ElS, which increases with increasing the storage time. In the charge/discharge processes, the diameter of the new arc is reversibly changed with electrode potential. Such variation coincides well with the electrode potential dependence of electronic conductivity of the LiCoO2. Thus this new ElS feature is attributed to the change of electronic conductivity of LixCoO2 during storage of the LiCoO2 cathode in electrolyte solutions, as well as in processes of intercalation-deintercalationtion of lithium ions. It has been revealed that the reversible increase and decrease of the resistance of SEI film in charge-discharge processes can be also ascribed to the variation of electronic conductance of active materials of the LiCoO2 cathode.

  18. Microhollow Cathode Discharge Excimer Lamps

    Science.gov (United States)

    Schoenbach, K. H.

    1999-11-01

    character. Reducing the diameter of the cathode hole in a hollow cathode discharge geometry to values on the order of 100 μm has allowed us to extend the pressure range of stable, direct current hollow cathode gas discharges up to atmospheric pressure. The large concentration of high-energy electrons generated in the cathode fall, in combination with the high neutral gas density favors three-body processes such as excimer formation. Excimer emission in xenon discharges peaking at 172 nm, was observed with efficiencies between 6% and 9% at pressures of several hundred Torr. Typical forward voltages are 200 V at dc currents up to 8 mA. Pulsed operation allowed us to extend the current range to 80 mA with corresponding linear increase in optical power. Spatially resolved measurements showed that the source of the excimer radiation at atmospheric pressure and currents of less than 8 mA is confined to the cathode opening. The radiative emittance at 8 mA and atmospheric pressure is approximately 20 W/cm^2. With reduced pressure and increased current, respectively, the excimer source extends into the area outside the cathode hole. Besides in xenon, excimer emission in argon at a peak wavelength of 128 nm has been recorded. In addition to operating the discharge in rare gases, we have also explored its use as rare gas-halide excimer source. In a gas mixture containing 1% ArF we were able to generate stable dc discharges in flowing gas at pressures ranging from 100 Torr to atmospheric pressure. The spectra of the high-pressure ArF discharges are dominated by excimer radiation peaking at 193 nm. The excimer emission of a single ArF discharge at 700 Torr was measured as 150 mW at an efficiency of 3%. Parallel operation of these discharges by means of a resistive anode, which has recently been demonstrated for argon discharges, offers the possibility to use microhollow cathode discharge arrays as dc-excimer lamps, with estimated power densities exceeding 10 W/cm^2. abstract

  19. A study of vacuum arc ion velocities using a linear set of probes

    Energy Technology Data Exchange (ETDEWEB)

    Hohenbild, Stefan; Grubel, Christoph; Yushkov, Georgy Yu.; Oks, Efim M.; Anders, Andre

    2008-07-15

    The most likely velocity of ions moving away from vacuum arc cathode spots was measured using a set of probes along the path of plasma expansion. The goal was to determine how much, if any, change of the ion drift velocity occurs in the expanded plasma. The arc discharge current was perturbed to create plasma density markers whose travel is picked up by the set of probes. It was found that the perturbation with current oscillations did not result in consistent data because ion current maxima and minima are not only determined by the plasma production but by the transients of the arc pulse and by the asymmetry of the ion velocity distribution function. Perturbation with a short current spike was more conclusive. The ion velocity was measured to be slightly reduced with increasing distance from the cathode, which can be explained by collisions of ions with the background of neutrals. The ion velocity was increased when the arc current was increased, which correlated with enhanced arc voltage and power dissipation. The ion velocity could be enhanced when the plasma was produced in a non-uniform magnetic field.

  20. Arc Behavior and Droplet Transfer of CWW CO2 Welding

    Institute of Scientific and Technical Information of China (English)

    Zhi-dong YANG; Chen-fu FANG; Yong CHEN; Guo-xiang XU; Qing-xian HU; Xiao-yan GU

    2016-01-01

    Cable-type welding wire (CWW)CO2 welding is an innovative process arc welding with high quality,high efficiency and energy saving,in which CWW is used as consumable electrode.The CWW is composed of seven wires with a diameter of 1.2 mm.One is in the center,while others uniformly distribute around it.The diameter of twisted wire is up to 3.6 mm,which can increase the deposition rate significantly.With continual wire-feeding and melting of CWW,the formed rotating arc improved welding quality obviously.The arc behavior and droplet transfer were ob-served by the electrical signal waveforms and corresponding synchronous images,based on the high speed digital camera and electrical signal system.The results showed that the shape of welding arc changed from bell arc to beam arc with the increase of welding parameter.The droplet transfer mode changed from repelled transfer,globular transfer to projected transfer in turn.Droplet transfer frequency increased from 18.17 Hz to 119.05 Hz,while the droplet diameter decreased from 1.5 times to 0.3 times of the CWW diameter.

  1. Cross-flow blowing of a two-dimensional stationary arc.

    Science.gov (United States)

    Bose, T. K.

    1971-01-01

    It is demonstrated in an analysis that the electrons emitted from the cathode undergo collisions with the heavy particles and are deflected in the flow direction by the component of a collisional force associated with the relative difference in flow velocities between electrons and heavy particles. The resultant motion of the electrons describing the arc is thus caused by a combined action of the collisional force that results from the externally applied electric field. An expression is given which enables computation of the arc shape to be made provided the velocity distribution of the cross-flow and the distribution of the externally applied electric field are prescribed.

  2. Modeling rf breakdown arcs

    CERN Document Server

    Insepov, Zeke; Huang, Dazhang; Mahalingam, Sudhakar; Veitzer, Seth

    2010-01-01

    We describe breakdown in 805 MHz rf accelerator cavities in terms of a number of mechanisms. We devide the breakdown process into three stages: (1) we model surface failure using molecular dynamics of fracture caused by electrostatic tensile stress, (2) we model the ionization of neutrals responsible for plasma initiation and plasma growth using a particle in cell code, and (3) we model surface damage by assuming a process similar to unipolar arcing. Although unipolar arcs are strictly defined with equipotential boundaries, we find that the cold, dense plasma in contact with the surface produces very small Debye lengths and very high electric fields over a large area. These high fields produce strong erosion mechanisms, primarily self sputtering, compatible with the crater formation that we see. Results from the plasma simulation are included as a guide to experimental verification of this model.

  3. ALICE - ARC integration

    DEFF Research Database (Denmark)

    Anderlik, Csaba; Gregersen, Anders Rhod; Kleist, Josva;

    AliEn or Alice Environment is the Gridware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic...... Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The interoperation has two aspects, one is the data...... management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. dCache provides support for several data management tools (among them for xrootd the tools used by AliEn) using the so called "doors". Therefore, we will concentrate on the second...

  4. The ARCS radial collimator

    OpenAIRE

    Stone M.B.; Niedziela J.L.; Overbay M.A.; Abernathy D.L.

    2015-01-01

    We have designed, installed, and commissioned a scattered beam radial collimator for use at the ARCS Wide Angular Range Chopper Spectrometer at the Spallation Neutron Source. The collimator has been designed to work effectively for thermal and epithermal neutrons and with a range of sample environments. Other design considerations include the accommodation of working within a high vacuum environment and having the ability to quickly install and remove the collimator from the scattered beam. W...

  5. Calculation of pediatric femoral fracture rotation from direct roentgenograms.

    Science.gov (United States)

    Ozel, M S; Ketenci, I E; Kaya, E; Tuna, S; Saygi, B

    2013-12-01

    Radiologic determination of pediatric femoral fracture rotation has been debated. Measuring the antetorsion angle of the fractured femur by computed tomography and comparing it with the opposite side has been the method of choice for this purpose. However, no simple method for direct measurement of femoral fracture rotation exists in the literature. In this study, our aim was to test a mathematical method of measuring the axial plane malrotation from direct roentgenograms. A pediatric femoral shaft fracture model was produced. The bone was secured to a wooden frame that allowed the distal part of the fracture to rotate around an axis. Radiographs were taken at known intervals of rotation ranging from the neutral position to 60° external rotation and to 60° internal rotation in 5° increments of rotation. Five independent, blinded observers measured the radiographs and calculated the fracture rotation according to a standard formula. Calculated rotation values were compared with known rotation values. Calculated rotation values were close to actual rotation values throughout the arc of rotation. The mean absolute error of five observers for all measurements of external and internal rotation was 3.97° (±0.83). The correlation coefficient between calculated and actual rotation values was 0.9927. The interobserver intraclass correlation coefficient for calculated rotation was 0.997. Absolute error and correlation coefficient values indicate that this method is accurate and reliable in determining the fracture rotation.

  6. Circular arc structures

    KAUST Repository

    Bo, Pengbo

    2011-07-01

    The most important guiding principle in computational methods for freeform architecture is the balance between cost efficiency on the one hand, and adherence to the design intent on the other. Key issues are the simplicity of supporting and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where geometric complexity is concentrated in the nodes, we stay with smooth surfaces and rather distribute complexity in a uniform way by allowing edges in the shape of circular arcs. We are able to achieve the simplest possible shape of nodes without interfering with known panel optimization algorithms. We study remarkable special cases of circular arc structures which possess simple supporting elements or repetitive edges, we present the first global approximation method for principal patches, and we show an extension to volumetric structures for truly threedimensional designs. © 2011 ACM.

  7. Clinical utility of RapidArcTM radiotherapy technology

    Directory of Open Access Journals (Sweden)

    Infusino E

    2015-11-01

    Full Text Available Erminia Infusino Department of Radiotherapy, Campus Bio-Medico University Hospital, Rome, Italy Abstract: RapidArcTM is a radiation technique that delivers highly conformal dose distributions through the complete rotation (360° and speed variation of the linear accelerator gantry. This technique, called volumetric modulated arc therapy (VMAT, compared with conventional radiotherapy techniques, can achieve high-target volume coverage and sparing damage to normal tissues. RapidArc delivers precise dose distribution and conformity similar to or greater than intensity-modulated radiation therapy in a short time, generally a few minutes, to which image-guided radiation therapy is added. RapidArc has become a currently used technology in many centers, which use RapidArc technology to treat a large number of patients. Large and small hospitals use it to treat the most challenging cases, but more and more frequently for the most common cancers. The clinical use of RapidArc and VMAT technology is constantly growing. At present, a limited number of clinical data are published, mostly concerning planning and feasibility studies. Clinical outcome data are increasing for a few tumor sites, even if only a little. The purpose of this work is to discuss the current status of VMAT techniques in clinical use through a review of the published data of planning systems and clinical outcomes in several tumor sites. The study consisted of a systematic review based on analysis of manuscripts retrieved from the PubMed, BioMed Central, and Scopus databases by searching for the keywords "RapidArc", "Volumetric modulated arc radiotherapy", and "Intensity-modulated radiotherapy". Keywords: IMRT, VMAT, SBRT, SRS, treatment planning software 

  8. Water-vortex stabilized electric arc: II. Effect of non-uniform evaporation of water

    Science.gov (United States)

    Jenista, Jirí

    1999-11-01

    The paper deals with a numerical model of an electric arc stabilized by a water vortex. The axisymmetric model involves the area between the cathode and the output nozzle of the arc. The rate of evaporation of water (production of water plasma) is determined from radial conduction and radiation heat fluxes near the water-water-vapour phase transition. The influence of non-uniform evaporation rate along the discharge coordinate on the outlet arc parameters is studied for the currents 300 and 600 A. It is found from calculations that part of the power spent on evaporation is in the range 1.4-3.1% of the total input power. The dominant source of power losses from the arc is plasma radiation, which exceeds conduction losses by a factor of two to four. Since the majority of the arc discharge is nearly thermally fully-developed, the effect of non-uniformity of evaporation on the overall arc performance is minor. The calculated arc outlet characteristics are in good agreement with our data published previously, as well as with experiments carried out on the water plasma torch operating at our Institute.

  9. Arc-preserving subsequences of arc-annotated sequences

    CERN Document Server

    Popov, Vladimir Yu

    2011-01-01

    Arc-annotated sequences are useful in representing the structural information of RNA and protein sequences. The longest arc-preserving common subsequence problem has been introduced as a framework for studying the similarity of arc-annotated sequences. In this paper, we consider arc-annotated sequences with various arc structures. We consider the longest arc preserving common subsequence problem. In particular, we show that the decision version of the 1-{\\sc fragment LAPCS(crossing,chain)} and the decision version of the 0-{\\sc diagonal LAPCS(crossing,chain)} are {\\bf NP}-complete for some fixed alphabet $\\Sigma$ such that $|\\Sigma| = 2$. Also we show that if $|\\Sigma| = 1$, then the decision version of the 1-{\\sc fragment LAPCS(unlimited, plain)} and the decision version of the 0-{\\sc diagonal LAPCS(unlimited, plain)} are {\\bf NP}-complete.

  10. 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

  11. Mass Transfer Coefficient During Cathodic Protectionof Low Carbon Steel in Seawater

    Directory of Open Access Journals (Sweden)

    Ameel Mohammed Rahman

    2009-01-01

    Full Text Available The aim of this research is to calculate mass transfer coefficient, kd, during cathodic protection of low carbon steel in neutral seawater (3.5% W/V NaCl in distilled water with pH = 7. Two types of cathodic protection were used:First: Sacrificial anode cathodic protection (SACP were a pipeline of steel carrying seawater using zinc as a sacrificial anode and with variable temperatures ranged (0 – 45oC and volumetric flow rate ranged (5 – 900 lit/hr. It was found that the kd increases with increasing temperature and volumetric flow rate of seawater, where kd ranged (0.24×10-6 – 41.6×10-6 m/s.Second: Impressed current cathodic protection (ICCP technique adopting a rotating vertical steel cylinder in seawater with variable temperatures ranged (0 – 45oC and rotating velocity ranged (0 – 400 rpm. It was found that the kd increases with increasing temperature and rotating velocity, where kd ranged (7.25×10-6 – 36.82×10-6 m/s.

  12. Numerical Simulation of High-current Vacuum Arc in Short Gap%Numerical Simulation of High-current Vacuum Arc in Short Gap

    Institute of Scientific and Technical Information of China (English)

    XIANG Chuan; LIAO Min-fu; DONG Hua-jun; HUANG Zhi-hui; ZOU Ji-yan

    2011-01-01

    The plasma status of vacuum arc before arc current zero, has a great influence on the interruption perform- ance of the vacuum circuit breakers. In this paper, a vacuum arc model in a short gap was established based on the magnet hydrodynamic (MHD) and a common computational fluid dynamics (CFD) software was utilized to specially investigate the properties of this arc. The spatial distributions of plasma pressure, plasma density, ion axial velocity, and axial current density in front of the anode surface of vacuum arc in this case were obtained. Simulation results in- dicate that: from the cathode to the anode, both of the plasma pressure and the plasma density increase gradually, and the plasma axial velocity decreases gradually; the axial current density in front of anode has a large radial gradient, and the maximum value is still smaller than the threshold current density for the anode-spot formation, thus, the anode is still passive. The comparison between the plasma density of simulation and the CMOS images taken by the high-speed camera indicates that they are in reasonable agreement with each other and demonstrates the feasibility of the vacuum arc model.

  13. Control of the low-frequency vibrations of elastic metamaterial shafts with discretized arc-rubber layers

    Science.gov (United States)

    Lixia, Li; Anjiang, Cai

    2016-06-01

    We propose a new kind of elastic metamaterial (EM) shaft with discretized arc-shaped rubber layers, which shows excellent low-frequency vibration properties. The band gaps of the shaft structure were analyzed by employing the finite element method. The proposed EM shaft exhibits much lower band gaps than the corresponding structures with the whole rubber ring. Furthermore, the band gaps can be modulated by tuning the arc angle and the number of the arc-shaped rubbers. Additionally, we observed that the first complete band gap tends to disappear when the arc angle of each arc-shaped rubber section is decreased but the arc number remains fixed because the arc angle more strongly affects the rotational stiffness than the transverse stiffness of the rubber layers. This new type of EM shafts could find potential application as a means to control the low-frequency vibrations of rotor shafts in mechanical engineering.

  14. High ion charge states in a high-current, short-pulse, vacuum ARC ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M. [Lawrence Berkeley National Lab., CA (United States)

    1996-08-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1-4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several {mu}s) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution.

  15. Microhollow cathode discharge excimer lamps

    Science.gov (United States)

    Schoenbach, Karl H.; El-Habachi, Ahmed; Moselhy, Mohamed M.; Shi, Wenhui; Stark, Robert H.

    2000-05-01

    Microhollow cathode discharges are high-pressure, nonequilibrium gas discharges between a hollow cathode and a planar or hollow anode with electrode dimensions in the 100 μm range. The large concentration of high-energy electrons, in combination with the high-gas density favors excimer formation. Excimer emission was observed in xenon and argon, at wavelengths of 128 and 172 nm, respectively, and in argon fluoride and xenon chloride, at 193 and 308 nm. The radiant emittance of the excimer radiation was found to increase monotonically with pressure. However, due to the decrease in source size with pressure, the efficiency (ratio of excimer radiant power to input electrical power), has for xenon and argon fluoride a maximum at ˜400 Torr. The maximum efficiency is between 6% and 9% for xenon, and ˜2% for argon fluoride.

  16. Characterization of multicapillary dielectric cathodes

    Science.gov (United States)

    Gleizer, J. Z.; Hadas, Y.; Yarmolich, D.; Felsteiner, J.; Krasik, Ya. E.

    2007-04-01

    Parameters of the plasma and electron beam produced by a multicapillary cathode in a diode powered by a ˜200kV, ˜300ns pulse are presented. It was found that the source of electrons is the plasma ejected from the capillaries. Inside the capillaries this plasma obtains electron density and temperature of ˜8×1015cm-3 and ˜5eV, respectively. In the vicinity of the cathode, the density and temperature of the plasma electrons were found to be 2×1014cm-3 and 4.5eV, respectively, for electron current density of ˜40A/cm2. It was shown that the plasma expansion velocity is in the range of (1-2)×106cm/s for current density of >12A/cm2.

  17. Hybrid laser-arc welding

    DEFF Research Database (Denmark)

    Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

  18. A simple arc column model that accounts for the relationship between voltage, current and electrode gap during VAR

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, R.L. [Sandia National Labs., Albuquerque, NM (United States). Liquid Metal Processing Lab.

    1997-02-01

    Mean arc voltage is a process parameter commonly used in vacuum arc remelting (VAR) control schemes. The response of this parameter to changes in melting current (I) and electrode gap (g{sub e}) at constant pressure may be accurately described by an equation of the form V = V{sub 0} + c{sub 1}g{sub e}I + c{sub 2}g{sub e}{sup 2} + c{sub 3}I{sup 2}, where c{sub 1}, c{sub 2} and c{sub 3} are constants, and where the non-linear terms generally constitute a relatively small correction. If the non-linear terms are ignored, the equation has the form of Ohm`s law with a constant offset (V{sub 0}), c{sub 1}g{sub e} playing the role of resistance. This implies that the arc column may be treated approximately as a simple resistor during constant current VAR, the resistance changing linearly with g{sub e}. The VAR furnace arc is known to originate from multiple cathode spot clusters situated randomly on the electrode tip surface. Each cluster marks a point of exist for conduction electrons leaving the cathode surface and entering the electrode gap. Because the spot clusters re highly localized on the cathode surface, each gives rise to an arc column that may be considered to operate independently of other local arc columns. This approximation is used to develop a model that accounts for the observed arc voltage dependence on electrode gap at constant current. Local arc column resistivity is estimated from elementary plasma physics and used to test the model for consistency by using it to predict local column heavy particle density. Furthermore, it is shown that the local arc column resistance increases as particle density increases. This is used to account for the common observation that the arc stiffens with increasing current, i.e. the arc voltage becomes more sensitive to changes in electrode gap as the melting current is increased. This explains why arc voltage is an accurate electrode gap indicator for high current VAR processes but not low current VAR processes.

  19. Correlation methods in cutting arcs

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L; Kelly, H, E-mail: prevosto@waycom.com.ar [Grupo de Descargas Electricas, Departamento Ing. Electromecanica, Universidad Tecnologica Nacional, Regional Venado Tuerto, Laprida 651, Venado Tuerto (2600), Santa Fe (Argentina)

    2011-05-01

    The present work applies similarity theory to the plasma emanating from transferred arc, gas-vortex stabilized plasma cutting torches, to analyze the existing correlation between the arc temperature and the physical parameters of such torches. It has been found that the enthalpy number significantly influence the temperature of the electric arc. The obtained correlation shows an average deviation of 3% from the temperature data points. Such correlation can be used, for instance, to predict changes in the peak value of the arc temperature at the nozzle exit of a geometrically similar cutting torch due to changes in its operation parameters.

  20. Joan of Arc.

    Science.gov (United States)

    Foote-Smith, E; Bayne, L

    1991-01-01

    For centuries, romantics have praised and historians and scientists debated the mystery of Joan of Arc's exceptional achievements. How could an uneducated farmer's daughter, raised in harsh isolation in a remote village in medieval France, have found the strength and resolution to alter the course of history? Hypotheses have ranged from miraculous intervention to creative psychopathy. We suggest, based on her own words and the contemporary descriptions of observers, that the source of her visions and convictions was in part ecstatic epileptic auras and that she joins the host of creative religious thinkers suspected or known to have epilepsy, from St. Paul and Mohammed to Dostoevsky, who have changed western civilization.

  1. The ARCS radial collimator

    Directory of Open Access Journals (Sweden)

    Stone M.B.

    2015-01-01

    Full Text Available We have designed, installed, and commissioned a scattered beam radial collimator for use at the ARCS Wide Angular Range Chopper Spectrometer at the Spallation Neutron Source. The collimator has been designed to work effectively for thermal and epithermal neutrons and with a range of sample environments. Other design considerations include the accommodation of working within a high vacuum environment and having the ability to quickly install and remove the collimator from the scattered beam. We present here characterization of the collimator's performance and methodologies for its effective use.

  2. The ARCS radial collimator

    Science.gov (United States)

    Stone, M. B.; Niedziela, J. L.; Overbay, M. A.; Abernathy, D. L.

    2015-01-01

    We have designed, installed, and commissioned a scattered beam radial collimator for use at the ARCS Wide Angular Range Chopper Spectrometer at the Spallation Neutron Source. The collimator has been designed to work effectively for thermal and epithermal neutrons and with a range of sample environments. Other design considerations include the accommodation of working within a high vacuum environment and having the ability to quickly install and remove the collimator from the scattered beam. We present here characterization of the collimator's performance and methodologies for its effective use.

  3. Reflective article having a sacrificial cathodic layer

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-09-12

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

  4. Sun powers Libya cathodic-protection system

    Energy Technology Data Exchange (ETDEWEB)

    Currer, G.W.

    1982-03-22

    Well castings and part of the main 300-mile-long, 32-in diameter pipeline from Sarir to Tobruk are cathodically protected by solar power, which prevents galvanic action by applying an electric direct current of appropriate magnitude and polarity to the steel structures. They then act as cathodes and become the recipients of metallic ions. At each cathodic-protection station, the solar-generaor system consists of solar-panel arrays, electronic controls, and batteries.

  5. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith...dominate the metal’s cathodic behavior. Within an alkaline environment, we expect the following reduction reactions to be catalyzed on the oxide

  6. Nonactivated and Activated Biochar Derived from Bananas as Alternative Cathode Catalyst in Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Haoran Yuan

    2014-01-01

    Full Text Available Nonactivated and activated biochars have been successfully prepared by bananas at different thermotreatment temperatures. The activated biochar generated at 900°C (Biochar-act900 exhibited improved oxygen reduction reaction (ORR and oxygen evolution reaction (OER performances in alkaline media, in terms of the onset potential and generated current density. Rotating disk electron result shows that the average of 2.65 electrons per oxygen molecule was transferred during ORR of Biochar-act900. The highest power density of 528.2 mW/m2 and the maximum stable voltage of 0.47 V were obtained by employing Biochar-act900 as cathode catalyst, which is comparable to the Pt/C cathode. Owning to these advantages, it is expected that the banana-derived biochar cathode can find application in microbial fuel cell systems.

  7. Nonactivated and activated biochar derived from bananas as alternative cathode catalyst in microbial fuel cells.

    Science.gov (United States)

    Yuan, Haoran; Deng, Lifang; Qi, Yujie; Kobayashi, Noriyuki; Tang, Jiahuan

    2014-01-01

    Nonactivated and activated biochars have been successfully prepared by bananas at different thermotreatment temperatures. The activated biochar generated at 900°C (Biochar-act900) exhibited improved oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performances in alkaline media, in terms of the onset potential and generated current density. Rotating disk electron result shows that the average of 2.65 electrons per oxygen molecule was transferred during ORR of Biochar-act900. The highest power density of 528.2 mW/m(2) and the maximum stable voltage of 0.47 V were obtained by employing Biochar-act900 as cathode catalyst, which is comparable to the Pt/C cathode. Owning to these advantages, it is expected that the banana-derived biochar cathode can find application in microbial fuel cell systems.

  8. Methodology for the design of accelerated stress tests for non-precious metal catalysts in fuel cell cathodes

    Science.gov (United States)

    Sharabi, Ronit; Wijsboom, Yair Haim; Borchtchoukova, Nino; Finkelshtain, Gennadi; Elbaz, Lior

    2016-12-01

    In this work we propose systematic methods for testing non-precious group metal catalysts and support degradation alkaline fuel cell cathodes. In this case study, we used a cathode composed of a pyrolyzed non-precious metal catalyst (NPMC) on activated carbon. The vulnerabilities of the cathode components were studied in order to develop the methodology and design an accelerated stress test (AST) for NPMC-based cathode in alkaline environment. Cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were used to characterize the electrochemical behavior of the cathode and to follow the changes that occur as a result of exposing the cathodes to extreme operating conditions. Rotating ring disk electrode (RRDE) was used to study the cathodes kinetics; Raman spectroscopy and X-ray fluorescence (XRF) were used to study the structural changes in the electrode surface as well as depletion of the catalysts' active sites from the electrode. The changes in the composition of the electrode and catalyst were detected using X-ray diffraction (XRD). For the first time, we show that NPMC degrade rapidly at low operating potentials whereas the support degrades at high operating potentials and developed a tailor-made AST to take these into account.

  9. Alternating-Polarity Arc Welding

    Science.gov (United States)

    Schwinghamer, R. J.

    1987-01-01

    Brief reversing polarity of welding current greatly improves quality of welds. NASA technical memorandum recounts progress in art of variable-polarity plasma-arc (VPPA) welding, with emphasis on welding of aluminum-alloy tanks. VPPA welders offer important advantages over conventional single-polarity gas/tungsten arc welders.

  10. Structural evolution of the Kamchatka - Aleutian arc junction area in the Late Mesozoic and Tertiary

    Science.gov (United States)

    Alexeiev, D.; Gaedicke, C.; Tsukanov, N. V.; Freitag, R.; Harbert, W.

    2002-05-01

    Structural, sedimentological and paleomagnetic studies have been conducted within the Kamchatka - Aleutian junction area aiming to a reconstruction of the tectonic history of the region from the Late Cretaceous to the Miocene. Pre-Pliocene structures of the area are comprised of 1) Achaivayam -Valaginskiy (Olyutorskiy) arc, 2) Vetlovskiy terrane, 3) Kronotskiy arc, and 4) Tyushevka basin, which goes along the boundary between Vetlovskiy and Kronotskiy units. In the Late Cretaceous and Tertiary deformations within the area of study were controlled by the following processes: 1) Northward subduction of the Pacific and Kula plates underneath the Kronotskiy arc and accretion in the fore-arc wedge south of the arc from the Late Cretaceous to the Middle Eocene. 2) Collision of the Achaivayam - Valaginskiy arc against Eurasia during the Early and Middle Eocene. 3) Northwest directed subduction in Proto-Kamchatka subduction zone and development of the accretionary wedge within Vetlovskiy terrane in the Middle and Late Eocene. 4) Collision of the Kronotskiy arc against Kamchatka during the Late Eocene through the Middle Miocene. We reconstruct seven structural complexes with individual structural patterns, which document different episodes of the regional deformation history. Age of the Kronotskiy arc collision is constrained by that 1) the Tyushevka foreland basin developed during the Late Eocene (?), Oligocene, Early and Middle Miocene, and 2) the foreland basin discordantly crosses syn-collisional plunging folds within the Kronotskiy arc. Syn-collisional deformations were controlled by the northwest motion of the Kronotskiy arc as part of the Pacific plate, and by the simultaneous motion of the entire northeast Eurasia margin toward the South. This caused deflection of the western segment of the Kronotskiy arc toward the south; it's rotation up to 90o counterclockwise and the subsequent bent of the arc into a large knee-like structure. The eastern portion of the

  11. Characteristics of Arcs Between Porous Carbon Electrodes

    OpenAIRE

    Carvou, Erwann; Le Garrec, Jean-Luc; Mitchell, Brian

    2013-01-01

    International audience; Arcs between carbon electrodes present some specific differences compared with metallic arcs. The arc voltage is higher, but does not attain a stable value displaying large fluctuations. Indeed, the arcs are produced by the direct sublimation of the electrodes, without passing through a molten phase. The arc production is also facilitated by both circuit breaking and electric field breakdown. In this paper, arcing has been examined under various conditions (voltage, cu...

  12. Variation of plasma parameters of vacuum arc column with gap distance

    Science.gov (United States)

    Han, Wen; Yuan, Zhao; He, Junjia

    2016-07-01

    On the basis of a two-dimensional (2D) magneto-hydrodynamic model, we studied long-gap-distance vacuum arcs in a uniform axial magnetic field and determined the effect of gap distance varying in a large range on plasma parameters. Simulation results showed that with increasing gap distance, the parameters of the plasma near the cathode are almost invariant, except for ion number density, but the parameters of the plasma in front of the anode clearly vary; meanwhile, joule heat gradually becomes the main source of energy for the arc column. In a short gap, a clear current constriction can be found in the entire arc column. Whereas when the gap distance exceeds a certain value, a sharp contraction of the current only arises in front of the anode.

  13. Cathode materials: A personal perspective

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B. [Texas Materials Institute, University of Texas at Austin, ETC 9.102, 1 University Station, Austin, TX 78712-1063 (United States)

    2007-12-06

    A thermodynamically stable rechargeable battery has a voltage limited by the window of the electrolyte. An aqueous electrolyte has a window of 1.2 eV, which prevents achieving the high energy density desired for many applications. A non-aqueous electrolyte with a window of 5 eV requires Li{sup +} rather than H{sup +} as the working ion. Early experiments with Li{sub x}TiS{sub 2} cathodes showed competitive capacity and rate capability, but problems with a lithium anode made the voltage of a safe cell based on a sulfide cathode too low to be competitive with a nickel/metal-hydride battery. Transition-metal oxides can give voltages of 4.5 V versus Li{sup +}/Li{sup 0}. However, the challenge with oxides has been to obtain a competitive capacity and rate capability while retaining a high voltage with low-cost, environmentally friendly cathode materials. Comparisons will be made between layered Li{sub 1-x}MO{sub 2}, spinels Li{sub 1-x}[M{sub 2}]O{sub 4}, and olivines Li{sub 1-x}MPO{sub 4} having 0 < x < 1. Although higher capacities can be obtained with layered Li{sub 1-x}MO{sub 2} compounds, which have enabled the wireless revolution, their metastability makes them unlikely to be used in power applications. The spinel and olivine framework structures have been shown to be capable of charge/discharge rates of over 10C with a suitable temperature range for plug-in hybrid vehicles. (author)

  14. Distribution of Argon Arc Contaminated with Nitrogen as Function of Frequency in Pulsed TIG Welding

    Science.gov (United States)

    Takahashi, Hiroki; Tanaka, Tatsuro; Yamamoto, Shinji; Iwao, Toru

    2016-09-01

    TIG arc welding is the high-quality and much applicable material joining technology. However, the current has to be small because the cathode melting should be prevented. In this case, the heat input to the welding pool becomes low, then, the welding defect sometimes occurs. The pulsed TIG arc welding is used to improve this disadvantage This welding can be controlled by some current parameters such as frequency However, few report has reported the distribution of argon arc contaminated with nitrogen It is important to prevent the contamination of nitrogen because the melting depth increases in order to prevent the welding defects. In this paper, the distribution of argon arc contaminated as function of frequency with nitrogen in pulsed TIG welding is elucidated. The nitrogen concentration, the radial flow velocity, the arc temperature were calculated using the EMTF simulation when the time reached at the base current. As a result, the nitrogen concentration into the arc became low with increasing the frequency The diffusion coefficient decreased because of the decrement of temperature over 4000 K. In this case, the nitrogen concentration became low near the anode. Therefore, the nitrogen concentration became low because the frequency is high.

  15. A bird's eye view of "Understanding volcanoes in the Vanuatu arc"

    Science.gov (United States)

    Vergniolle, S.; Métrich, N.

    2016-08-01

    The Vanuatu intra-oceanic arc, located between 13 and 22°S in the southwest Pacific Ocean (Fig. 1), is one of the most seismically active regions with almost 39 earthquakes magnitude 7 + in the past 43 years (Baillard et al., 2015). Active deformation in both the Vanuatu subduction zone and the back-arc North-Fiji basin accommodates the variation of convergence rates which are c.a. 90-120 mm/yr along most of the arc (Taylor et al., 1995; Pelletier et al., 1998). The convergence rate is slowed down to 25-43 mm/yr (Baillard et al., 2015) in the central segment where the D'Entrecasteaux ridge - an Eocene-Oligocene island arc complex on the Australian subducting plate - collides and is subducted beneath the fore-arc (Taylor et al., 2005). Hence, the Vanuatu arc is segmented in three blocks which move independently; as the north block rotates counter-clockwise in association with rapid back-arc spreading ( 80 mm/year), the central block translates eastward and the south block rotates clockwise (Calmant et al., 2003; Bergeot et al., 2009). (See Fig. 1.)

  16. Purification of carbon nanotubes from cathode deposit by means of different oxidation rates

    Energy Technology Data Exchange (ETDEWEB)

    Ikazaki, Fumikazu; Uchida, Kunio; Ohshima, Satoshi; Kuriki, Yasunori [National Inst. of Materials and Chemical Research, Ibaraki (Japan)] [and others

    1996-10-01

    Two purification methods of nanotubes from a cathode deposit by an arc plasma were conducted by means of different oxidation rates of various graphites. One was chemical and the other physical method. Both could purify nanotubes at their optimum conditions. In the former, the catalytic oxidation was used of graphitic materials by copper. Copper supported graphite was prepared by the intercalation of copper chloride and by the reduction to metal copper. The catalytic oxidation decomposed the graphite at 773 K. The temperature was 200 K lower than the oxidation temperature of graphite, which enabled purification. In the latter, dispersion, comminution and filtration of a cathode deposit in ethanol were used to separate coarse graphite. The rate of weight loss by oxidation increased with the decrease of size of the graphite. Nanotubes were more slowly oxidized from the edges than the graphite of the same size. This could purify nanotubes.

  17. Purification of carbon nanotubes from cathode deposit by means of different oxidation rates

    Energy Technology Data Exchange (ETDEWEB)

    Ikazaki, F.; Uchida, K.; Ohshima, S. [National Institute of Materials and Chemical Research, Tsukuba, Ibaraki (Japan)] [and others

    1996-12-31

    Two purification methods of nanotubes from a cathode deposit by an arc plasma were conducted by means of different oxidation rates of various graphites. One was chemical and the other physical method. Both could purify nanotubes at their optimum conditions. In the former, the catalytic oxidation was used of graphite materials by copper. Copper supported graphite was prepared by the intercalation of copper chloride and by the reduction to metal copper. The catalytic oxidation decomposed the graphite at 773 K and less. The temperature was significantly lower than the oxidation temperature former reported of graphite, which enabled purification. In the latter, dispersion, comminution and filtration of a cathode deposit in ethanol were used to separate coarse graphite. The rate of weight loss by oxidation increased with the decrease of size of the graphite. Nanotubes were more slowly oxidized from the edges than the graphite of the same size. This could purify nanotubes.

  18. On the suppression of cathodic hypochlorite reduction by electrolyte additions of molybdate and chromate ions

    Directory of Open Access Journals (Sweden)

    JOHN GUSTAVSSON

    2012-11-01

    Full Text Available The goal of this study was to gain a better understanding of the feasibility of replacing Cr(VI in the chlorate process by Mo(VI, focusing on the cathode reaction selectivity for hydrogen evolution on steel and titanium in a hypochlorite containing electrolyte. To evaluate the ability of Cr(VI and Mo(VI additions to hinder hypochlorite reduction, potential sweep experiments on rotating disc electrodes and cathodic current efficiency (CE measurements on stationary electrodes were performed. Formed electrode films were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cathodic hypochlorite reduction is hindered by the Mo-containing films formed on the cathode surface after Mo(VI addition to the electrolyte, but much less efficient compared to Cr(VI addition. Very low levels of Cr(VI, in the mM range, can efficiently suppress hypochlorite reduction on polished titanium and steel. Phosphate does not negatively influence the CE in the presence of Cr(VI or Mo(VI but the Mo-containing cathode films become thinner if the electrolyte during the film build-up also contains phosphate. For a RuO2-TiO2 anode polarized in electrolyte with 40 mM Mo(VI, the anode potential increased and increased molybdenum levels were detected on the electrode surface

  19. Comparative process analysis of fullerene production by the arc and the radio-frequency discharge methods.

    Science.gov (United States)

    Marković, Z; Todorović-Marković, B; Mohai, I; Farkas, Z; Kovats, E; Szepvolgyi, J; Otasević, D; Scheier, P; Feil, S; Romcević, N

    2007-01-01

    In this work, comparative analysis of processes in carbon arc and radio frequency (RF) plasma during fullerene synthesis has been presented. The kinetic model of fullerene formation developed earlier has been verified in both types of plasma reactors. The fullerene yield depended on carbon concentration, velocity of plasma flame and rotational temperature of C2 radicals predominantly. When mean rotational temperature of C2 radicals was 3000 K, the fullerene yield was the highest regardless of the type of used reactor. The zone of fullerene formation is larger significantly in RF plasma reactor compared to arc reactor.

  20. Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process

    Directory of Open Access Journals (Sweden)

    Dingjian Ye

    2013-01-01

    Full Text Available In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc is added to the middle arc (M-arc in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.

  1. Preliminary Results of Field Emission Cathode Tests

    Science.gov (United States)

    Sovey, James S.; Kovaleski, Scott D.

    2001-01-01

    Preliminary screening tests of field emission cathodes such as chemical vapor deposited (CVD) diamond, textured pyrolytic graphite, and textured copper were conducted at background pressures typical of electric thruster test facilities to assess cathode performance and stability. Very low power electric thrusters which provide tens to hundreds micronewtons of thrust may need field emission neutralizers that have a capability of tens to hundreds of microamperes. From current voltage characteristics, it was found that the CVD diamond and textured metals cathodes clearly satisfied the Fowler-Nordheim emission relation. The CVD diamond and a textured copper cathode had average current densities of 270 and 380 mA/sq cm, respectively, at the beginning-of-life. After a few hours of operation the cathode emission currents degraded by 40 to 75% at background pressures in the 10(exp -5) Pa to 10(exp -4) Pa range. The textured pyrolytic graphite had a modest current density at beginning-of-life of 84 mA/sq cm, but this cathode was the most stable of all. Extended testing of the most promising cathodes is warranted to determine if current degradation is a burn-in effect or whether it is a long-term degradation process. Preliminary experiments with ferroelectric emission cathodes, which are ceramics with spontaneous electric polarization, were conducted. Peak current densities of 30 to 120 mA/sq cm were obtained for pulse durations of about 500 ns in the 10(exp -4) Pa pressure range.

  2. Controllability of arc jet from arc horns with slits. Slit tsuki arc horn no arc jet seigyo tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Sunabe, K.; Inaba, T.; Fukagawa, H. (Central Research Institute of Electric Power Industry, Tokyo (Japan)); Kito, Y. (Nagoya University, Nagoya (Japan))

    1993-09-20

    To improve the corona discharge characteristics, test preparation was made of hollow rod form horns with slits for the overhead power transmission line use. Two types of horn electrode were prepared. The first horn electrode is of a hollow hemisphere fitted with and divided by slits on its tip. The second horn electrode is the first one which is further fitted with rod form electrode at the center of its tip. In experiment, relation was obtained between the deflection angle of arc jet and arc current, electrode diameter, etc., through an observation of arc jet by high speed camera. Melting loss of electrode was also made clear. The following knowledge was obtained: For the first horn electrode, the deflection angle can be limited to a narrow range by a division with slits, e.g., within 30 degrees under the condition of 5kA in arc current, 4 in number of sectors and 200mm in diameter. For the second horn electrode, the deflection angle can be limited to within 20 degrees under the condition of 5kA in arc current and 4 in number of sectors. The arc current is also limited to below 5kA by an addition of 50mm diameter central electrode. As a conclusion for the first electrode, the arc jet control characteristics excels in the stronger arc current range than 5kA, while for the second electrode, they are effective in the weaker arc current range than 5kA. 6 refs., 19 figs., 1 tab.

  3. Convergent evolution of the arginine deiminase pathway: the ArcD and ArcE arginine/ornithine exchangers.

    Science.gov (United States)

    Noens, Elke E E; Lolkema, Juke S

    2017-02-01

    The arginine deiminase (ADI) pathway converts L-arginine into L-ornithine and yields 1 mol of ATP per mol of L-arginine consumed. The L-arginine/L-ornithine exchanger in the pathway takes up L-arginine and excretes L-ornithine from the cytoplasm. Analysis of the genomes of 1281 bacterial species revealed the presence of 124 arc gene clusters encoding the pathway. About half of the clusters contained the gene encoding the well-studied L-arginine/L-ornithine exchanger ArcD, while the other half contained a gene, termed here arcE, encoding a membrane protein that is not a homolog of ArcD. The arcE gene product of Streptococcus pneumoniae was shown to take up L-arginine and L-ornithine with affinities of 0.6 and 1 μmol/L, respectively, and to catalyze metabolic energy-independent, electroneutral exchange. ArcE of S. pneumoniae could replace ArcD in the ADI pathway of Lactococcus lactis and provided the cells with a growth advantage. In contrast to ArcD, ArcE catalyzed translocation of the pathway intermediate L-citrulline with high efficiency. A short version of the ADI pathway is proposed for L-citrulline catabolism and the presence of the evolutionary unrelated arcD and arcE genes in different organisms is discussed in the context of the evolution of the ADI pathway.

  4. Arc spot grouping: An entanglement of arc spot cells

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Shin, E-mail: kajita.shin@nagoya-u.jp [EcoTopia Science Institute, Nagoya University, Nagoya 464-8603 (Japan); Hwangbo, Dogyun; Ohno, Noriyasu [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Tsventoukh, Mikhail M. [Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Barengolts, Sergey A. [Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation)

    2014-12-21

    In recent experiments, clear transitions in velocity and trail width of an arc spot initiated on nanostructured tungsten were observed on the boundary of the thick and thin nanostructured layer regions. The velocity of arc spot was significantly decreased on the thick nanostructured region. It was suggested that the grouping decreased the velocity of arc spot. In this study, we try to explain the phenomena using a simple random walk model that has properties of directionality and self-avoidance. And grouping feature was added by installing an attractive force between spot cells with dealing with multi-spots. It was revealed that an entanglement of arc spot cells decreased the spot velocity, and spot cells tend to stamp at the same location many times.

  5. Hybrid laser-arc welding

    DEFF Research Database (Denmark)

    the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

  6. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

    Directory of Open Access Journals (Sweden)

    Y J Li

    Full Text Available A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials.

  7. On arc efficiency in gas tungsten arc welding

    Directory of Open Access Journals (Sweden)

    Nils Stenbacka

    2013-12-01

    Full Text Available The aim of this study was to review the literature on published arc efficiency values for GTAW and, if possible, propose a narrower band. Articles between the years 1955 - 2011 have been found. Published arc efficiency values for GTAW DCEN show to lie on a wide range, between 0.36 to 0.90. Only a few studies covered DCEP - direct current electrode positive and AC current. Specific information about the reproducibility in calorimetric studies as well as in modeling and simulation studies (considering that both random and systematic errors are small was scarce. An estimate of the average arc efficiency value for GTAW DCEN indicates that it should be about 0.77. It indicates anyway that the GTAW process with DCEN is an efficient welding method. The arc efficiency is reduced when the arc length is increased. On the other hand, there are conflicting results in the literature as to the influence of arc current and travel speed.

  8. The role of current characteristics of the arc evaporator in formation of the surface metal-coating composite

    Science.gov (United States)

    Plikhunov, V. V.; Petrov, L. M.; Grigorovich, K. V.

    2016-07-01

    The influence of current characteristics of the vacuum arc evaporator on the interaction process of plasma streams with the surface under treatment during generation of the physicochemical properties of the formed metal-coating composite is considered. It is shown that the interaction of plasma streams with the processed surface provides surface heating, defects elimination, change in energy properties, and mass transfer of plasma stream elements activating surface diffusion processes whose intensity is evaluated by the arc current magnitude and location of the processed surface relative to the cathode axis.

  9. STUDY ON THE PRESSURE IN PLASMA ARC

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The axial pressure in plasma arc is measured under different conditions. The effects of the parameters, such as welding current, plasma gas flow rate, electrode setback and arc length, on the pressure in plasma arc are investigated and quantitative analyzed to explain the relationship between the quality of weld and the matching of parameters in plasma arc welding process.

  10. 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.

  11. Hall-effect thruster--Cathode coupling: The effect of cathode position and magnetic field topology

    Science.gov (United States)

    Sommerville, Jason D.

    2009-12-01

    Hall-effect thruster (HET) cathodes are responsible for the generation of the free electrons necessary to initiate and sustain the main plasma discharge and to neutralize the ion beam. The position of the cathode relative to the thruster strongly affects the efficiency of thrust generation. However, the mechanisms by which the position affects the efficiency are not well understood. This dissertation explores the effect of cathode position on HET efficiency. Magnetic field topology is shown to play an important role in the coupling between the cathode plasma and the main discharge plasma. The position of the cathode within the magnetic field affects the ion beam and the plasma properties of the near-field plume, which explains the changes in efficiency of the thruster. Several experiments were conducted which explored the changes of efficiency arising from changes in cathode coupling. In each experiment, the thrust, discharge current, and cathode coupling voltage were monitored while changes in the independent variables of cathode position, cathode mass flow and magnetic field topology were made. From the telemetry data, the efficiency of the HET thrust generation was calculated. Furthermore, several ion beam and plasma properties were measured including ion energy distribution, beam current density profile, near-field plasma potential, electron temperature, and electron density. The ion beam data show how the independent variables affected the quality of ion beam and therefore the efficiency of thrust generation. The measurements of near-field plasma properties partially explain how the changes in ion beam quality arise. The results of the experiments show that cathode position, mass flow, and field topology affect several aspects of the HET operation, especially beam divergence and voltage utilization efficiencies. Furthermore, the experiments show that magnetic field topology is important in the cathode coupling process. In particular, the magnetic field

  12. Arc of opportunity.

    Science.gov (United States)

    Delaney, Adam Vai

    2011-07-01

    Born in Port Moresby, Papua New Guinea, the author had a 20 year career in diplomacy, political affairs, and development policy analysis at the Pacific Islands Forum, the United Nations in New York; the Prime Minister's Department in Papua New Guinea (PNG) and in the Foreign Ministry of PNG. He has also been involved in theatre for over a decade in PNG, and participated in a three-month program at the Eugene O'Neill Theatre Center in Connecticut, USA. He is currently the Business Development Manager at the Torres Strait Regional Authority (Commonwealth) on Thursday Island. Since 1975 the Australian government's overseas development policy has supported various sectoral programs in its neighbouring countries, in particular Papua New Guinea and the Solomon Islands. The "creative" field has not been prominent in this strategy. While natural resources and the sports sectors have gained much greater attention, in terms of being viable international commercial enterprises, the arts, have remained stagnant. In this paper the need for joint programs genuinely supporting "wellbeing" and promoting social enterprise throughout the "arc of opportunity" is described to harness Melanesian creativity to compete successfully in world-markets, starting with penetration of the largest economy at its door-step: Australia.

  13. Cathode heating mechanisms in pseudospark plasma switches

    Science.gov (United States)

    Sommerer, Timothy J.; Pak, Hoyoung; Kushner, Mark J.

    1992-10-01

    Pseudosparks, and the back-lighted thyratron (BLT) in particular, are finding increasing application as pulse power switches. An attractive feature of BLTs is that high current densities (≥ tens of kA cm-2) can be sustained from metal cathodes without auxiliary heating. The source of this current is believed to be electric-field-enhanced thermionic emission resulting from heating of the cathode by ion bombardment during commutation which ultimately melts the surface of the cathode. It is proposed that a photon-driven ionization mechanism in the interelectrode gap of the BLT is responsible for initiating the observed patterns of cathode surface melting and electron emission. A 21/2-dimensional computer model is presented that incorporates a photo-induced ionization mechanism to spread the plasma into the interelectrode gap. It predicts a melting of the cathode in a pattern similar to that which is experimentally observed, and predicts a rate of field-enhanced thermionic electron emission that is sufficient to explain the high BLT conduction current density. In the absence of these mechanisms, the model does not predict the observed large-area melting of the face of the cathode. The cathode heating rate during the BLT switching phase is maximum for operating parameters that are very close to the limit for which the switch will close (that is, the smallest possible pressure-electrode spacing product and smallest possible electrode holes).

  14. STM observation of asymmetrical Y-branched carbon nanotubes and nano-knees produced by the arc discharge method

    Energy Technology Data Exchange (ETDEWEB)

    Osvath, Z.; Koos, A.A.; Horvath, Z.E.; Gyulai, J.; Benito, A.M.; Martinez, M.T.; Maser, W.; Biro, L.P

    2003-06-10

    The scanning tunneling microscopy (STM) observation of arc-grown Y-branched carbon nanotubes and sharp nanotube bends (nano-knees) is reported. A drilled out graphite rod filled with a nickel/yttrium particle mixture was used as the anode in an arc chamber under He atmosphere of 660-mbar pressure. Straight multi-wall nanotubes, Y-branches and nano-knees were found in a sample taken from the cathodic deposit. The asymmetrical Y-branches and complex nano-knees found in this experiment may be related to the additional use of metals or/and to induced changes of the temperature distribution on the cathode side. It is suggested that complex nano-knees could be new examples for carbon quantum dots.

  15. 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

  16. 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

  17. Origin of microplasma instabilities during DC operation of silicon based microhollow cathode devices

    Science.gov (United States)

    Felix, Valentin; Lefaucheux, Philippe; Aubry, Olivier; Golda, Judith; Schulz-von der Gathen, Volker; Overzet, Lawrence J.; Dussart, Rémi

    2016-04-01

    The failure mechanisms of micro hollow cathode discharges (MHCD) in silicon have been investigated using their I-V characteristics, high speed photography and scanning electron microscopy. Experiments were carried out in helium. We observed I-V instabilities in the form of rapid voltage decreases associated with current spikes. The current spikes can reach values more than 100 times greater than the average MHCD current. (The peaks can be more than 1 Ampere for a few 10’s of nanoseconds.) These current spikes are correlated in time with 3-10 μm diameter optical flashes that occur inside the cavities. The SEM characterizations indicated that blister-like structures form on the Si surface during plasma operation. Thin Si layers detach from the surface in localized regions. We theorize that shallow helium implantation occurs and forms the ‘blisters’ whenever the Si is biased as the cathode. These blisters ‘explode’ when the helium pressure inside them becomes too large leading to the transient micro-arcs seen in both the optical emission and the I-V characteristics. We noted that blisters were never found on the metal counter electrode, even when it was biased as the cathode (and the Si as the anode). This observation led to a few suggestions for delaying the failure of Si MHCDs. One may coat the Si cathode (cavities) with blister resistant material; design the MHCD array to operate with the Si as the anode rather than as the cathode; or use a gas additive to prevent surface damage. Regarding the latter, tests using SF6 as the gas additive successfully prevented blister formation through rapid etching. The result was an enhanced MHCD lifetime.

  18. Electrochemical Impedance Studies of SOFC Cathodes

    DEFF Research Database (Denmark)

    Hjelm, Johan; Søgaard, Martin; Wandel, Marie

    2007-01-01

    impedance of the cathode at intermediate operating temperatures. The perovskite is of the La-Sr-Co-Fe type. The EIS response of symmetrical cells with a thick (similar to 200 mu m) gadolinia doped ceria electrolyte was compared with the impedance contribution of the cathode of a full anode supported cell....... The full cells had a Ni-YSZ anode and anode support, a thin YSZ electrolyte, and a CGO barrier layer. The symmetric and full cell cathode responses were compared at open-circuit voltage. Humidified hydrogen was used as the fuel in the full cell measurements. Differential analysis of the impedance data...

  19. Lanthanum manganate based cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Juhl Joergensen, M.

    2001-07-01

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

  20. Isosynchronous paths on a rotating surface

    CERN Document Server

    Ashby, Neil

    2014-01-01

    In special relativity, clock networks may be self-consistently synchronized in an inertial frame by slowly transporting clocks, or by exchanging electromagnetic signals between network nodes. However, clocks at rest in a rotating coordinate system--such as on the surface of the rotating earth--cannot be self-consistently synchronized by such processes, due to the Sagnac effect. Discrepancies that arise are proportional to the area swept out by a vector from the rotation axis to the portable clock or electromagnetic pulse, projected onto a plane normal to the rotation axis. This raises the question whether paths of minimal or extremal length can be found, for which the Sagnac discrepancies are zero. This paper discusses the variational problem of finding such "isosynchronous" paths on rotating discs and rotating spheres. On a disc, the problem resembles the classical isoperimetric problem and the paths turn out to be circular arcs. On a rotating sphere, however, between any two endpoints there are an infinite ...

  1. Characterization of magnetically impelled arc butt welded T11 tubes for high pressure applications

    Directory of Open Access Journals (Sweden)

    R. Sivasankari

    2015-09-01

    Full Text Available Magnetically impelled arc butt (MIAB welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of low alloy steel (T11 tubes were carried out to study the microstructural changes occurring in thermo-mechanically affected zone (TMAZ. To qualify the process for the welding applications where pressure could be up to 300 bar, the MIAB welds are studied with variations of arc current and arc rotation time. It is found that TMAZ shows higher hardness than that in base metal and displays higher weld tensile strength and ductility due to bainitic transformation. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded samples exhibits good structural property correlation for high pressure applications with an added benefit of enhanced productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

  2. Numerical and Experimental Studies of an Arc-heated Nonequilibrium Nozzle Flow

    Institute of Scientific and Technical Information of China (English)

    Michio Nishida; Ken-ichi Abe; Hisashi Kihara

    2003-01-01

    The arc-heated high-temperature gas is rotationally and vibrationally excited, and partially dissociated and ionized. When such gas flows inside a nozzle, energy transfers from rotational and vibrational energy modes to translational energy mode, and, in addition, recombination reactions occur. These processes are in thermal and chemical nonequilibrium. The present computations treat arc-heated nonequilibrium nozzle flows using a six temperature model (translational, rotational, N2 vibrational, O2 vibrational, NO vibrational and electron temperatures), and nonequilibrium chemical reactions of air. From the calculated flow properties, emission spectra at the nozzle exit were re-constructed by using the code for computing spectra of high temperature air. On the other hand, measurements of N+2 (1-) emission spectra were conducted at the nozzle exit in the 20 kW arc-heated wind tunnel. Vibrational and rotational temperatures of N2 were determined using a curve fitting method on N+2 (1-) emission spectra, with the vibrational and rotational temperatures for N2 and N+2 being assumed equal. Comparison of the measured and computed results elucidated that the experimental temperatures were larger than the computed ones. At present, we are trying to reveal the main reason for the discrepancy between the computed and measured N2 vibrational and rotational temperatures.

  3. Advances in Thermionic Cathode of Tungsten and Molybdenum

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Several kinds of tungsten thermonic cathodes have been introduced. As a promising alternative for thoriated tungsten, rare earth doped molybdenum cathode has been studied. Compared with the traditional thoriated tungsten, La-Mo cathode has higher emission current density at lower temperature, but it has poor emission stability. In order to improve the emission stability, systematical study on the emission mechanism of La-Mo cathode has been carried out. The life of La-Mo cathode has been improved and has achieved 1400 h, which exceeds the minimum life for practical uses (1000 h). As another alternative for thoriated tungsten cathode, Y-Mo cathode has shown better performance. The thermionic emission capability of Y-Mo cathode is between that of La-Mo cathode and Th-W cathode.

  4. 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.

  5. Enhanced Activated Carbon Cathode Performance for Microbial Fuel Cell by Blending Carbon Black

    KAUST Repository

    Zhang, Xiaoyuan

    2014-02-04

    Activated carbon (AC) is a useful and environmentally sustainable catalyst for oxygen reduction in air-cathode microbial fuel cells (MFCs), but there is great interest in improving its performance and longevity. To enhance the performance of AC cathodes, carbon black (CB) was added into AC at CB:AC ratios of 0, 2, 5, 10, and 15 wt % to increase electrical conductivity and facilitate electron transfer. AC cathodes were then evaluated in both MFCs and electrochemical cells and compared to reactors with cathodes made with Pt. Maximum power densities of MFCs were increased by 9-16% with CB compared to the plain AC in the first week. The optimal CB:AC ratio was 10% based on both MFC polarization tests and three electrode electrochemical tests. The maximum power density of the 10% CB cathode was initially 1560 ± 40 mW/m2 and decreased by only 7% after 5 months of operation compared to a 61% decrease for the control (Pt catalyst, 570 ± 30 mW/m2 after 5 months). The catalytic activities of Pt and AC (plain or with 10% CB) were further examined in rotating disk electrode (RDE) tests that minimized mass transfer limitations. The RDE tests showed that the limiting current of the AC with 10% CB was improved by up to 21% primarily due to a decrease in charge transfer resistance (25%). These results show that blending CB in AC is a simple and effective strategy to enhance AC cathode performance in MFCs and that further improvement in performance could be obtained by reducing mass transfer limitations. © 2014 American Chemical Society.

  6. 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.

  7. 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...

  8. Dosimetric verification of RapidArc treatment delivery

    DEFF Research Database (Denmark)

    Korreman, Stine; Medin, Joakim; Kjaer-Kristoffersen, Flemming

    2009-01-01

    doses. All plans were then delivered several times to verify consistency of the delivery. Gamma analysis was used to verify the correspondence between dose distributions. The temporal resolution of the delivery was analysed by investigating the arc segments between control points separately. RESULTS......: Overall, good agreement was observed between measured and calculated doses in most cases with gamma values above 1 in >95% of measured points. The reproducibility of delivery was also very high. Gamma analysis between two consecutive runs of the same delivery plan generally showed gamma values above 1......PURPOSE: Recently, Varian Medical Systems have announced the introduction of a new treatment technique, in which dose is delivered over a single gantry rotation with variable MLC positions, dose rate and gantry speed. In February 2008, a preclinical installation of the RapidArc beam delivery...

  9. Synthesis and evaluation of nano-size lanthanum strontium manganite-yttria-stablized zirconia composite powders as cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jungdeok; Zou, Jing [Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea); Chung, Jongshik [Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea); School of Environmental Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea)

    2010-08-01

    Nano-sized (50 nm) lanthanum strontium manganite (La{sub 0.8}Sr{sub 0.2}MnO{sub 3}, LSM) particles are deposited on yttria-stablized zirconia (8YSZ) by synthesizing LSM particles in situ in an YSZ-dispersed solution. As the LSM content is decreased from 80 to 25 wt.%, 50 wt.% powder shows the best microstructure and phase connectivity. This composite, when used as a cathode in a button cell, also has the highest power density of 791 mW cm{sup -2} at 800 C and the lowest values of the cathode polarization resistance and high-frequency arc (0.315 and 0.120 {omega} cm{sup 2}, respectively). Initially, the low-frequency arc shows a rapid decrease as the LSM content is reduced from 80 to 60 wt.%. After this, an abrupt drop at 50 wt.% LSM content is followed by a slow decrease in the low-frequency arc with further decrease in the LSM content. The results suggest that the high-frequency arc is related to charge transfer and the low-frequency arc to the site density of the triple-phase boundary (TPB). A new parameter, the charge-transfer efficiency of the TPB site, is defined and used to explain further the observed effect of LSM content on YSZ. (author)

  10. Modeling High Pressure Micro Hollow Cathode Discharges

    Science.gov (United States)

    2007-11-02

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

  11. Eocene to Miocene back-arc basin basalts and associated island arc tholeiites from northern Sulawesi (Indonesia): Implications for the geodynamic evolution of the Celebes basin; Basaltes de bassin arriere-arc de l`Eocene-Miocene et tholeiites d`arc insulaire associees du nord Sulawesi (Indonesie): implications pour l`evolution geodynamique du bassin des Celebes

    Energy Technology Data Exchange (ETDEWEB)

    Rangin, C. [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France); Maury, R.C.; Bellon, H.; Cotten, J. [Universite de Bretagne Occidentale, 29 - Brest (France); Polve, M. [Universite Paul Sabatier, 31 - Toulouse (France); Priadi, B.; Soeria-Atmadja, R. [Department of Geology, ITB, Bandung (Indonesia); Joron, J.L. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Recherche sur l`Etat Condense, les Atomes et les Molecules

    1997-12-31

    Eocene BABB basalts intruded by tholeiitic and calk-alkalic island arc magmatic rocks are reported from the north arm of Sulawesi (Indonesia). Age and geochemical similarities between these basalts and those drilled in the Celebes Sea indicate this North Sulawesi volcanic arc was built on the same oceanic crust. The 25 deg late Neogene clockwise rotation of the north arm of Sulawesi following its collision with fragments of Australia (Sula, Buton) is not sufficient to explain the asymmetrical magnetic anomalies in the Celebes basin. The North Sulawesi island arc could be interpreted as having progressively retreated northward on its own Celebes sea back arc basin, during an episode of Palaeogene-early Neogene tectonic erosion along the trench. (authors) 37 refs.

  12. High pressure neon arc lamp

    Science.gov (United States)

    Sze, Robert C.; Bigio, Irving J.

    2003-07-15

    A high pressure neon arc lamp and method of using the same for photodynamic therapies is provided. The high pressure neon arc lamp includes a housing that encloses a quantity of neon gas pressurized to about 500 Torr to about 22,000 Torr. At each end of the housing the lamp is connected by electrodes and wires to a pulse generator. The pulse generator generates an initial pulse voltage to breakdown the impedance of the neon gas. Then the pulse generator delivers a current through the neon gas to create an electrical arc that emits light having wavelengths from about 620 nanometers to about 645 nanometers. A method for activating a photosensitizer is provided. Initially, a photosensitizer is administered to a patient and allowed time to be absorbed into target cells. Then the high pressure neon arc lamp is used to illuminate the target cells with red light having wavelengths from about 620 nanometers to about 645 nanometers. The red light activates the photosensitizers to start a chain reaction that may involve oxygen free radicals to destroy the target cells. In this manner, a high pressure neon arc lamp that is inexpensive and efficiently generates red light useful in photodynamic therapy is provided.

  13. Collimator angle influence on dose distribution optimization for vertebral metastases using volumetric modulated arc therapy

    Energy Technology Data Exchange (ETDEWEB)

    Mancosu, Pietro; Cozzi, Luca; Fogliata, Antonella; Lattuada, Paola; Reggiori, Giacomo; Cantone, Marie Claire; Navarria, Pierina; Scorsetti, Marta [Department of Radiation Oncology, IRCCS Istituto Clinico Humanitas, Milano (Rozzano) 20089 (Italy); Medical Physics Unit, Oncology Institute of Southern Switzerland, Bellinzona 6504 (Switzerland); Department of Radiation Oncology, IRCCS Istituto Clinico Humanitas, Milano (Rozzano) 20089 (Italy); Department of Physics, Universita Degli Studi di Milano, Milano 20133 (Italy); Department of Radiation Oncology, IRCCS Istituto Clinico Humanitas, Milano (Rozzano) 20089 (Italy)

    2010-08-15

    Purpose: The cylindrical symmetry of vertebrae favors the use of volumetric modulated arc therapy in generating a dose ''hole'' on the center of the vertebrae limiting the dose to the spinal cord. The authors have evaluated if collimator angle is a significant parameter for dose distribution optimization in vertebral metastases. Methods: Three patients with one-three vertebrae involved were considered. Twenty-one differently optimized plans (nine single-arc and 12 double-arc plans) were performed, testing various collimator angle positions. Clinical target volume was defined as the whole vertebrae, excluding the spinal cord canal. The planning target volume (PTV) was defined as CTV+5 mm. Dose prescription was 5x4 Gy{sup 2} with normalization to PTV mean dose. The dose at 1 cm{sup 3} of spinal cord was limited to 11.5Gy. Results: The best plans in terms of target coverage and spinal cord sparing were achieved by two arcs and Arc1-80 deg. and Arc2-280 deg. collimator angles for all the cases considered (i.e., leaf travel parallel to the spinal cord primary orientation). If one arc is used, only 80 deg. reached the objectives. Conclusions: This study demonstrated the role of collimation rotation for the vertebrae metastasis irradiation, with the leaf travel parallel to the spinal cord primary orientation to be better than other solutions. Thus, optimal choice of collimator angle increases the optimization freedom to shape a desired dose distribution.

  14. Characterization of an atmospheric double arc argon-nitrogen plasma source

    Science.gov (United States)

    Tu, X.; Chéron, B. G.; Yan, J. H.; Yu, L.; Cen, K. F.

    2008-05-01

    In the framework of studies devoted to hazardous waste destruction, an original dc double anode plasma torch has been designed and tested, which produces an elongated, weak fluctuation and reproducible plasma jet at atmospheric pressure. The arc instabilities and dynamic behavior of the double arc argon-nitrogen plasma jet are investigated through the oscillations of electrical signals by combined means of fast Fourier transform and Wigner distribution. In our experiment, the restrike mode is identified as the typical fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra and Wigner distributions exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which reveals that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the undulation of the power supply and both arc roots motion on the anode channels. In addition, the microscopic properties of the plasma jet inside and outside the arc chamber are investigated by means of optical emission spectroscopy, which yields excitation, electronic, rotational, and vibrational temperatures, as well as the electron number density. The results allow us to examine the validity criteria of a local thermodynamic equilibrium (LTE) state in the plasma arc. The measured electron densities are in good agreement with those calculated from the LTE model, which indicates that the atmospheric double arc argon-nitrogen plasma in the core region is close to the LTE state under our experimental conditions.

  15. Arcing phenomena in fusion devices workshop

    Energy Technology Data Exchange (ETDEWEB)

    Clausing, R.E.

    1979-01-01

    The workshop on arcing phenomena in fusion devices was organized (1) to review the pesent status of our understanding of arcing as it relates to confinement devices, (2) to determine what informaion is needed to suppress arcing and (3) to define both laboratory and in-situ experiments which can ultimately lead to reduction of impurities in the plasma caused by arcing. The workshop was attended by experts in the area of vacuum arc electrode phenomena and ion source technology, materials scientists, and both theoreticians and experimentalists engaged in assessing the importance of unipolar arcing in today's tokamaks. Abstracts for papers presented at the workshop are included.

  16. Modelling the Plasma Jet in Multi-Arc Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.; Möhwald, K.; Lummer, C.

    2016-08-01

    Particle in-flight characteristics in atmospheric plasma spraying process are determined by impulse and heat energy transferred between the plasma jet and injected powder particles. One of the important factors for the quality of the plasma-sprayed coatings is thus the distribution of plasma gas temperatures and velocities in plasma jet. Plasma jets generated by conventional single-arc plasma spraying systems and their interaction with powder particles were subject matter of intensive research. However, this does not apply to plasma jets generated by means of multi-arc plasma spraying systems yet. In this study, a numerical model has been developed which is designated to dealing with the flow characteristics of the plasma jet generated by means of a three-cathode spraying system. The upstream flow conditions, which were calculated using a priori conducted plasma generator simulations, have been coupled to the plasma jet simulations. The significances of the relevant numerical assumptions and aspects of the models are analyzed. The focus is placed on to the turbulence and diffusion/demixing modelling. A critical evaluation of the prediction power of the models is conducted by comparing the numerical results to the experimental results determined by means of emission spectroscopic computed tomography. It is evident that the numerical models exhibit a good accuracy for their intended use.

  17. Application of Taguchi method for the characterization of calcareous deposits formed by pulse cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Zamanzade, M.; Shahrabi, T. [Department of Materials Science and Engineering, Faculty of Engineering, Tarbiat Modares University, Tehran (Iran); Gharacheh, E.A. [Department of Industrial Engineering, Faculty of Engineering, Tarbiat Modares University, Tehran (Iran)

    2007-09-15

    In this study, the Taguchi method, a powerful tool to design optimization for quality, is used to find the optimal process parameters of pulse cathodic protection system for the calcareous deposits' formation. An orthogonal array, main effect and the signal-to-noise (S/N) ratio are employed to investigate the process parameters in order to achieve optimum final current density. Through this study also the main process parameters that affect the calcareous deposits' formation can be found. Experiments were carried out to confirm the effectiveness of this approach. From the results, chronoamperometric measurements have been used to evaluate the influence of pulse cathodic protection on decreasing the required cathodic current for protection and also decreasing the surface coverage. The morphology of the formed deposits has been evaluated through scanning electron microscopy (SEM) and chemical analysis of the formed deposits has been performed using X-ray diffraction (XRD). It is found that the different environmental conditions, i.e., Ca{sup 2+} concentration, Mg{sup 2+} concentration, rotation speed, and temperature significantly affect the final required current density of the pulse cathodic protection. The optimum levels of parameters at different frequencies are also presented. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  18. Another Explanation for Neptune's Ring Arcs

    Science.gov (United States)

    Namouni, F.; Porco, C.

    2001-11-01

    Recent HST and Earth-based observations (Dumas et al 1999, Nature 400, 733; Sicardy et al 1999, Nature 400, 731) indicate that Neptune's ring arcs are not located at the corotation resonance with Galatea thought to be responsible for the azimuthal confinement of the arc system (Porco, 1991 Science 253, 995). Although small (5x 10-3od-1), the new observed mean motion offset puts the arcs near the resonance separatrix where the particles' semimajor axes would experience chaotic motion leading to the azimuthal spreading of the arcs within months, thereby calling into question their very existence. We have found a new resonant structure, dependent on the arcs having a small fraction of the mass of Galatea, in which Galatea's 43:42 eccentric corotation resonance, located (in the massless case) ~ 3 km inside the arcs' orbit, is made coincident with the arcs' semimajor axis. The arcs are primarily confined by this resonance, which is stronger ( e Galatea) than the inclined corotation resonance ( I2 Galatea) invoked in the Porco model. Moreover, the coupling of all the resonances in the arcs' neighborhood (eccentric corotation, inclined corotation and Lindblad resonances) modifies the interaction potential, creating smaller structures at the arcs' location. Consequently, this new confinement mechanism can simultaneously explain the arcs' confinement, the general spacing of the arcs, the Fraternité arc length of ~ 10o, and smaller-scale features seen in the arc system. Finally, the possibility of non-massless arcs supports an earlier suggestion by Porco et al (1991, in Neptune and Triton, the University of Arizona Series) that the rapid expected radial migration of the arc system, due to Galatea's secular torques, can be slowed down if the arcs have substantial mass.

  19. Rotator cuff exercises

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000357.htm Rotator cuff exercises To use the sharing features on this ... gov/pubmed/25560729 . Read More Frozen shoulder Rotator cuff problems Rotator cuff repair Shoulder arthroscopy Shoulder CT scan Shoulder ...

  20. 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

  1. Gas Tungsten Arc Welding and Plasma Arc Cutting. Teacher Edition.

    Science.gov (United States)

    Fortney, Clarence; And Others

    This welding curriculum guide treats two topics in detail: the care of tungsten electrodes and the entire concept of contamination control and the hafnium electrode and its importance in dual-air cutting systems that use compressed shop air for plasma arc cutting activities. The guide contains three units of instruction that cover the following…

  2. Approximate Design of Alloy Composition of Cathode Target

    Institute of Scientific and Technical Information of China (English)

    Jun ZHANG; Yu ZHANG; Li LI; Guoqiang LIN; Chuang DONG

    2006-01-01

    An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.

  3. 2013 Estorm - Invited Paper - Cathode Materials Review

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Claus [ORNL; Mohanty, Debasish [ORNL; Li, Jianlin [ORNL; Wood III, David L [ORNL

    2014-01-01

    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.

  4. Improved cathode materials for microbial electrosynthesis

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

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

  5. Multiple cathodic reaction mechanisms in seawater cathodic biofilms operating in sediment microbial fuel cells.

    Science.gov (United States)

    Babauta, Jerome T; Hsu, Lewis; Atci, Erhan; Kagan, Jeff; Chadwick, Bart; Beyenal, Haluk

    2014-10-01

    In this study, multiple reaction mechanisms in cathodes of sediment microbial fuel cells (SMFCs) were characterized by using cyclic voltammetry and microelectrode measurements of dissolved oxygen and pH. The cathodes were acclimated in SMFCs with sediment and seawater from San Diego Bay. Two limiting current regions were observed with onset potentials of approximately +400 mVAg/AgCl for limiting current I and -120 mVAg/AgCl for limiting current II. The appearance of two catalytic waves suggests that multiple cathodic reaction mechanisms influence cathodic performance. Microscale oxygen concentration measurements showed a zero surface concentration at the electrode surface for limiting current II but not for limiting current I, which allowed us to distinguish limiting current II as the conventional oxygen reduction reaction and limiting current I as a currently unidentified cathodic reaction mechanism. Microscale pH measurements further confirmed these results.

  6. METALLIC CATHODE SURFACE MODIFICATION BY USING LOW-PRESSURE PULSED VACUUM ARC DISCHARGE

    Directory of Open Access Journals (Sweden)

    LUIS ALPIDIO GARCIA

    2012-01-01

    Full Text Available Se produjeron descargas eléctricas en un sistema de arco pulsado a baja presión, con una corriente máxima de 100 A con pulsos de 30 ms. Las descargas se llevaron a cabo aplicando un voltaje de 104 V entre los electrodos. Los materiales utilizados como cátodo fueron Ti, Zr, Ni, Cu, Mo y W. La morfología de cátodos después de la descarga fue estudiada mediante la técnica de microscopía electrónica de barrido (SEM. Los cátodos de Ti y Zr presentaron la mayor erosión. Por otra parte, se observaron cráteres circulares sobre cátodos de Ni y Mo y se analizó una región del cátodo Zr, con alta erosión y gran cantidad de cráteres. Se midió el voltaje de descarga para cada material, obteniendo valores de voltaje del arco. Finalmente, se observaron las relaciones entre los voltajes de arco y algunas características del material como punto de fusión y de ebullición, presentando una tendencia exponencial.

  7. Cell adhesion to cathodic arc plasma deposited CrAlSiN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Kyu, E-mail: skim@ulsan.ac.kr [School of Materials Science and Engineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Pham, Vuong-Hung [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Kim, Chong-Hyun [Department of Food Science, Cornell University, Ithaca, NY 14853 (United States)

    2012-07-01

    Osteoblast cell response (cell adhesion, actin cytoskeleton and focal contact adhesion as well as cell proliferation) to CrN, CrAlSiN and Ti thin films was evaluated in vitro. Cell adhesion and actin stress fibers organization depended on the film composition significantly. Immunofluorescent staining of vinculin in osteoblast cells showed good focal contact adhesion on the CrAlSiN and Ti thin films but not on the CrN thin films. Cell proliferation was significantly greater on the CrAlSiN thin films as well as on Ti thin films than on the CrN thin films.

  8. Carbon nitride films grown by cathodic vacuum arc for hemocompatibility applications

    Directory of Open Access Journals (Sweden)

    Diana Shirley Galeano-Osorio

    2014-01-01

    Full Text Available Se obtuvieron películas delgadas de nitruro de carbono amorfo empleando arco pulsado y variando la temperatura del sustrato a temperatura ambiente, 100, 150 y 200 °C. Los enlaces de las estructuras se investigaron empleando la técnica de espectroscopía infrarroja por transformada de Fourier (FTIR y espectroscopía Raman. Se identificaron bandas de nitrilos en aproximadamente 2200 cm-1. Se observó una reducción en la concentración de los enlaces sp3 y del desorden estructural de las películas. La relación entre las intensidades de las bandas D y G aumentó con la temperatura del sustrato desde temperatura ambiente hasta 100°C; sin embargo, a una temperatura crítica de 150°C, esta tendencia desapareció y las películas se tornaron amorfas. Se observó un pico ubicado en aproximadamente 1610 cm-1 en las películas crecidas a 100°C, 150°C y 200 °C; además, las películas crecidas a 150 °C presentaron la rugosidad más baja y mayores durezas y hemocompatibilidad.

  9. Structural investigation of two carbon nitride solids produced by cathodic arc deposition and nitrogen implantation

    Energy Technology Data Exchange (ETDEWEB)

    Merchant, A.R.; McCulloch, D.; McKenzie, D.R.; Yin, Y.; Gerstner, E.G. [New South Wales Univ., Kensington, NSW (Australia)

    1996-12-31

    Carbon nitride materials have been the focus of research efforts worldwide. Most materials studied have been amorphous, with only a few groups claiming to have found a crystalline material. In this paper, carbon nitride materials prepared by two different techniques are analysed, and found to be remarkably similar in bonding and structure. The materials appear to have a primarily sp{sup 2} bonded carbon structure with a lower bond length than found in an amorphous carbon. This is explained by nitrogen substituting into `rings` to a saturation level of about one nitrogen per three carbon atoms. No evidence was found for a crystalline structure of formula C{sub 3}N{sub 4}, or any amorphous derivative of it. 16 refs., 1 tab., 5 figs.

  10. Rotating Cavitation Supression Project

    Data.gov (United States)

    National Aeronautics and Space Administration — FTT proposes development of a rotating cavitation (RC) suppressor for liquid rocket engine turbopump inducers. Cavitation instabilities, such as rotating...

  11. The effect of polarity on dc arc development over an ice surface

    Energy Technology Data Exchange (ETDEWEB)

    Farokhi, S; Farzaneh, M; Fofana, I [NSERC/Hydro-Quebec/UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment (CIGELE) and Canada Research Chair on Engineering of Power Network Atmospheric Icing (INGIVRE), Universite du Quebec a Chicoutimi, Quebec (Canada)

    2010-05-12

    Electrical/optical measurements have been carried out to study the dynamic behaviour of discharge on an ice surface. Significant differences in behaviour between positive and negative arcs have been revealed during discharge propagation. Also, its root structure, shape and velocity were found to be strongly polarity dependent. High-speed photography of the decays observed during discharge propagation showed two different patterns for dc positive and negative. Using simultaneous analysis of the captured pictures along with the current measurements at anode and cathode a mechanism describing the observed patterns is proposed. The effect of space charge regions observed around the main discharge channel is also discussed.

  12. Expanding sheath in a bounded plasma in the context of the post-arc phase of a vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Sarrailh, P [LAboratoire PLAsma et Conversion de l' Energie (LAPLACE), UMR5213, Universite Paul Sabatier, bat. 3R2, 118 route de Narbonne, 31062 Toulouse cedex 4 (France); Garrigues, L [LAboratoire PLAsma et Conversion de l' Energie (LAPLACE), UMR5213, Universite Paul Sabatier, bat. 3R2, 118 route de Narbonne, 31062 Toulouse cedex 4 (France); Hagelaar, G J M [LAboratoire PLAsma et Conversion de l' Energie (LAPLACE), UMR5213, Universite Paul Sabatier, bat. 3R2, 118 route de Narbonne, 31062 Toulouse cedex 4 (France); Sandolache, G [Schneider Electric Centre de Recherche, 38 TEC, 38050 Grenoble Cedex 09 (France); Rowe, S [Schneider Electric Centre de Recherche, 38 TEC, 38050 Grenoble Cedex 09 (France); Jusselin, B [Schneider Electric Centre de Recherche, 38 TEC, 38050 Grenoble Cedex 09 (France); Boeuf, J P [LAboratoire PLAsma et Conversion de l' Energie (LAPLACE), UMR5213, Universite Paul Sabatier, bat. 3R2, 118 route de Narbonne, 31062 Toulouse cedex 4 (France)

    2008-01-07

    A numerical model of sheath expansion and plasma decay in a bounded plasma subjected to a linearly increasing voltage has been developed. Numerical results obtained with a hybrid-MB model (Maxwell-Boltzmann electrons, particle ions and Poisson's equations) are compared with analytical theory and results from particle-in-cell (PIC) simulations. The hybrid-MB model is similar to models used for plasma immersion ion implantation except that plasma decay due to particle losses to the electrodes is taken into account. The comparisons with more accurate and much more time consuming PIC models show that the hybrid-MB model provides a very satisfactory description of the sheath expansion and plasma decay even for conditions where the grid spacing is much larger than the Debye length. The model is used for high plasma density conditions, corresponding to the post-arc phase of a vacuum arc circuit breaker where a vacuum gap is subject to a transient recovery voltage (TRV) after it has ceased to sustain a vacuum arc. The results show that the plasma sheath expansion is subsonic under these conditions, and that the plasma starts to decay exponentially after two rarefaction waves from the cathode and anode merge in the centre of the gap. A parametric study also shows the strong influence of the TRV rise rate and initial plasma density on the plasma decay time and on the ion current collected by each electrode. The effect of collisions between charged particles and metal atoms resulting for the electrode evaporation is also discussed.

  13. Vacuum Gas Tungsten Arc Welding

    Science.gov (United States)

    Weeks, J. L.; Todd, D. T.; Wooten, J. R.

    1997-01-01

    A two-year program investigated vacuum gas tungsten arc welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. After a vacuum chamber and GTAW power supply were modified, several difficult-to-weld materials were studied and key parameters developed. Finally, Incoloy 903 weld overlays were produced without microfissures.

  14. Hooded arc ion-source

    CERN Multimedia

    1972-01-01

    The positioning system for the hooded arc ion-source, shown prior to mounting, consists of four excentric shafts to locate the ion-source and central electrodes. It will be placed on the axis of the SC and introduced into the vacuum tank via the air locks visible in the foreground.

  15. Warm storage for arc magmas.

    Science.gov (United States)

    Barboni, Mélanie; Boehnke, Patrick; Schmitt, Axel K; Harrison, T Mark; Shane, Phil; Bouvier, Anne-Sophie; Baumgartner, Lukas

    2016-12-06

    Felsic magmatic systems represent the vast majority of volcanic activity that poses a threat to human life. The tempo and magnitude of these eruptions depends on the physical conditions under which magmas are retained within the crust. Recently the case has been made that volcanic reservoirs are rarely molten and only capable of eruption for durations as brief as 1,000 years following magma recharge. If the "cold storage" model is generally applicable, then geophysical detection of melt beneath volcanoes is likely a sign of imminent eruption. However, some arc volcanic centers have been active for tens of thousands of years and show evidence for the continual presence of melt. To address this seeming paradox, zircon geochronology and geochemistry from both the frozen lava and the cogenetic enclaves they host from the Soufrière Volcanic Center (SVC), a long-lived volcanic complex in the Lesser Antilles arc, were integrated to track the preeruptive thermal and chemical history of the magma reservoir. Our results show that the SVC reservoir was likely eruptible for periods of several tens of thousands of years or more with punctuated eruptions during these periods. These conclusions are consistent with results from other arc volcanic reservoirs and suggest that arc magmas are generally stored warm. Thus, the presence of intracrustal melt alone is insufficient as an indicator of imminent eruption, but instead represents the normal state of magma storage underneath dormant volcanoes.

  16. Arc discharge deposition of stainless steel coatings at different nitrogen pressures

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, J. [VTT Manufacturing Technology (Finland); Torri, P. [Helsinki Univ. (Finland). Dept. of Physics; Hirvonen, J.P. [VTT Manufacturing Technology (Finland); Mahiout, A. [VTT Manufacturing Technology (Finland); Stanishevsky, A. [Plasmoteg Engineering Centre, Minsk (Belarus)

    1996-03-01

    A filtered arc discharge process was employed to deposit stainless steel films using an AISI316 cathode. In this procedure, macroparticles and droplets, which are the most serious drawback of arc deposition processes especially in corrosion applications, are mostly filtered out. Films were deposited in vacuum or in the presence of a nitrogen plasma at different partial pressures. Low carbon steel and silicon single crystals were employed as substrates. Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA) and X-ray diffraction (XRD) were used to characterize the films. The corrosion properties were examined using electrochemical polarization measurements. The corrosion current density was clearly lower than that of bulk steel, but higher than that of bulk AISI316. Increasing the film thickness and nitrogen content lowered the corrosion current density. (orig.)

  17. Volt-ampere characteristics of a nitrogen DC plasma arc with anode melting

    Institute of Scientific and Technical Information of China (English)

    Zhao Peng; Ni Guo-Hua; Meng Yue-Dong; Nagatsu Masaaki

    2013-01-01

    The characteristics of a nitrogen arc using a graphite cathode and a melting anode in a pilot-scale plasma furnace are investigated.The voltage is examined as a function of current and apparent plasma length.The voltage increases non-linearly with the increase of apparent plasma length,with the current fixed.The experimental data so obtained are compared with the predictions of the Bowman model for the electric arc,and with numerical simulations as well.The level of agreement between the experimental data at the melting anode and the numerical predictions confirms the suitability of the proposed the Bowman model.These characteristics are relevant to the engineering design and evaluation of a DC plasma furnace and reactor for the treatment of hazardous fly ash waste.

  18. Parallel Operation of Microhollow Cathode Discharges

    Science.gov (United States)

    Stark, Robert H.; Shi, Wenhui; Schoenbach, Karl H.

    1998-10-01

    The dc current-voltage characteristics of microhollow cathode discharges has, in certain ranges of the discharge current, a positive slope [1]. In these current ranges it should be possible to operate multiple discharges in parallel without individual ballast, and be used as flat panel excimer lamps [2] or large area plasma cathodes. In order to verify this hypothesis we have studied the parallel operation of two microhollow cathode discharges of 100 micrometer hole diameter in argon at pressures from 100 Torr to 800 Torr. Stable dc operation of the two discharges, without individual ballast, was obtained if the voltage-current characteristics of the individual discharges had a positive slope greater than 10 V/mA over a voltage range of more than 5 to obtain parallel operation over the entire current range of the microhollow cathode discharges, which includes regions of negative differential conductivity, we have replaced the metal anode by a semi-insulating semiconductor, which serves as distributed resistive ballast. With this method, we were able to ignite and sustain an array of dc microhollow cathode discharges over a wide range of pressure and discharge current. [1] K.H.Schoenbach et al. Appl. Phys. Lett. 68, 13 (1996). [2] A.El-Habachi and K.H.Schoenbach, APL. 72, 1 (1998). This work was funded by the Department of Energy, Advanced Energy Division, and by the Air Force Office of Scientific Research (AFOSR) in cooperation with the DDR&E Air Plasma Ramparts MURI Program.

  19. STRUVE arc and EUPOS® stations

    Science.gov (United States)

    Lasmane, Ieva; Kaminskis, Janis; Balodis, Janis; Haritonova, Diana

    2013-04-01

    The Struve Geodetic Arc was developed in Years 1816 to 1855, 200 years ago. Historic information on the points of the Struve Geodetic Arc are included in the UNESCO World Heritage list in 2005. Nevertheless, the sites of many points are still not identified nor included in the data bases nowadays. Originally STRUVE arc consisted of 258 main triangles with 265 triangulation points. Currently 34 of the original station points are identified and included in the in the UNESCO World Heritage list. identified original measurement points of the Meridian Arc are located in Sweden (7 points), Norway (15), Finland (83), Russia (1), Estonia (22), Latvia (16), Lithuania (18), Belorussia (28), Ukraine (59) and Moldova (27). In Year 2002 was initiated another large coverage project - European Position Determination System "EUPOS®". Currently there are about 400 continuously operating GNSS (Global Navigation Satellite Systems) stations covering EU countries Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Hungary, Bulgaria, Romania and East European countries Ukraine and Moldavia. EUPOS® network is a ground based GNSS augmentation system widely used for geodesy, land surveying, geophysics and navigation. It gives the opportunity for fast and accurate position determination never available before. It is an honorable task to use the EUPOS® system for research of the Struve triangulation former sites. Projects with Struve arc can popularize geodesy, geo-information and its meaning in nowadays GIS and GNSS systems. Struve Arc and its points is unique cooperation cross-border object which deserve special attention because of their natural beauty and historical value for mankind. GNSS in geodesy discovers a powerful tool for the verification and validation of the height values of geodetic leveling benchmarks established historically almost 200 years ago. The differential GNSS and RTK methods appear very useful to identify vertical displacement of landscape by means of

  20. The structure and singularities of arc complexes

    DEFF Research Database (Denmark)

    Penner, Robert

    boundary components. The main result of this paper is the determination of those arc complexes Arc(F) that are also spherical. This classification has consequences for Riemann's moduli space via its known identification with an analogous arc complex in the punctured case with no boundary. Namely...

  1. Laboratory experiments on arc deflection and instability

    Energy Technology Data Exchange (ETDEWEB)

    Zweben, S.; Karasik, M.

    2000-03-21

    This article describes experiments on arc deflection instability carried out during the past few years at the Princeton University Plasma Physics Laboratory (PPPL). The approach has been that of plasma physicists interested in arcs, but they believe these results may be useful to engineers who are responsible for controlling arc behavior in large electric steel furnaces.

  2. Making Conductive Polymers By Arc Tracking

    Science.gov (United States)

    Daech, Alfred F.

    1992-01-01

    Experimental technique for fabrication of electrically conductive polymeric filaments based on arc tracking, in which electrical arc creates conductive carbon track in material that initially was insulator. Electrically conductive polymeric structures made by arc tracking aligned along wire on which formed. Alignment particularly suited to high conductivity and desirable in materials intended for testing as candidate superconductors.

  3. Magnification Bias in Gravitational Arc Statistics

    Energy Technology Data Exchange (ETDEWEB)

    Caminha, G. B. [Rio de Janeiro, CBPF; Estrada, J. [Fermilab; Makler, M. [Rio de Janeiro, CBPF

    2013-08-29

    The statistics of gravitational arcs in galaxy clusters is a powerful probe of cluster structure and may provide complementary cosmological constraints. Despite recent progresses, discrepancies still remain among modelling and observations of arc abundance, specially regarding the redshift distribution of strong lensing clusters. Besides, fast "semi-analytic" methods still have to incorporate the success obtained with simulations. In this paper we discuss the contribution of the magnification in gravitational arc statistics. Although lensing conserves surface brightness, the magnification increases the signal-to-noise ratio of the arcs, enhancing their detectability. We present an approach to include this and other observational effects in semi-analytic calculations for arc statistics. The cross section for arc formation ({\\sigma}) is computed through a semi-analytic method based on the ratio of the eigenvalues of the magnification tensor. Using this approach we obtained the scaling of {\\sigma} with respect to the magnification, and other parameters, allowing for a fast computation of the cross section. We apply this method to evaluate the expected number of arcs per cluster using an elliptical Navarro--Frenk--White matter distribution. Our results show that the magnification has a strong effect on the arc abundance, enhancing the fraction of arcs, moving the peak of the arc fraction to higher redshifts, and softening its decrease at high redshifts. We argue that the effect of magnification should be included in arc statistics modelling and that it could help to reconcile arcs statistics predictions with the observational data.

  4. Transient mass transfer at the rotating disk electrode.

    Science.gov (United States)

    Nanis, L.; Klein, I.

    1972-01-01

    Transient mass transfer at the rotating disk has been investigated theoretically and experimentally for cathodic reduction of ferricyanide in the redox system ferricyanide-ferrocyanide with potassium hydroxide supporting electrolyte. It has been shown that overpotential-time predictions for the rotating disk are fitted very well for decay (current interruption) but poorly for build-up following switching on of constant current. As an explanation for this behavior, attention is directed to the inadequacy of the assumption that a radially independent concentration profile exists at the disk surface just at the start of galvanostatic current passage.

  5. Spatially resolved measurements and diagnostics of digitally controlled rotating field pulsed plasma operated in helium at 20 kHz

    Science.gov (United States)

    Giersz, Jacek; Jankowski, Krzysztof; Reszke, Edward

    2017-04-01

    Using optical emission spectrometry, fundamental properties are investigated of a stable, planar atmospheric pressure micro discharge, several dozen microliters in volume, driven by a digitally controlled 20 kHz rotating microsecond pulsed power. The discharge is generated by rectangular wave pulses using helium as the working gas. At a low cost, the digitally controlled plasma source produces a highly symmetrical, non-stationary helium discharge maintained in open air within 5 electrodes positioned in the plane toward the center. It has been shown that the geometrical shapes of the momentary discharges, which occur between the electrodes, are not arc-like shaped, but rather have a diffusive character and the resulting plasma can become doughnut-like in shape. Rotational and vibrational temperatures from OH and N2 bands, excitation temperatures from He lines and ionization temperatures from Ca lines, as well as electron number densities from Hβ Stark broadening have been estimated along the plasma diameter using axial viewing. The results demonstrated that Texc (He) reaches stable value of 3800 K for selected plasma generation conditions (one anode and two cathodes commutation mode, cathode pulse width 8 microseconds, supplied power 200 W, helium gas flow 1 L·min- 1), while the Trot (OH) is considerably lower (1700 K). The electron number density has been evaluated to be (1.7-3.3) × 1014 cm- 3 and both Tion (Ca) and Tvib (N2) varied, throughout in the 4500-5100 K and 4000-4800 K ranges respectively, reaching its peak value near 2 mm off the plasma axis. Spatial measurements revealed symmetrical distribution of the plasma parameters, while the measurements of calcium and nitrogen ionic emission confirmed symmetrical doughnut shape of the discharge. Moreover, the processes running inside the discharge and their interaction with the surrounding atmosphere have been described in accordance to the recorded spectra. Spectroscopic observation has shown the existence of

  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. Synthesis and evaluation of highly tolerant Pd electrocatalysts as cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Varela, F. J.; Fraire Luna, S. [Grupo de Recursos Naturales y Energeticos, Cinvestav Unidad Saltillo, Carr. Saltillo-Monterrey Km. 13.5, Ramos Arizpe, Coahuila, C.P. 25900 (Mexico); Savadogo, O. [Laboratoire d' Electrochimie et de Materiaux Energetiques, Ecole Polytechnique de Montreal, C.P. 6079, succ. Centre-Ville, Montreal, QC, H3C 3A7 (Canada)

    2009-07-01

    Highly selective Pd electrocatalysts were synthesized by the formic acid (FA) method and evaluated as cathodes for DEGFC applications. In rotating disc measurements in acid medium, the Pd/C cathode showed important catalytic activity for the Oxygen Reduction Reaction (ORR). In the presence of ethylene glycol (EG, C{sub 2}H{sub 6}O{sub 2}), Pd/C exhibited a noteworthy electrochemical behavior and full tolerance to the organic molecule. No current density peaks associated to the EG oxidation reaction emerged and the shift in onset potential for the ORR (E{sub onset}) toward more negative potentials was negligible on this cathode. As a comparison, commercial Pt/C was tested under the same conditions showing a poor selectivity for the ORR when EG was present. The detrimental effect of EG on the Pt electrocatalysts resulted in high intensity current density peaks due to the oxidation of EG and a significant shift in E{sub onset}. The evaluation of Pd/C in a DEGFC operating at 80 {sup o}C demonstrated its good performance as cathode material. Given these results, it is expected that highly efficient Pd-based cathodes can find application in DEGFCs. (author)

  8. Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC

    Directory of Open Access Journals (Sweden)

    Oumarou Savadogo

    2009-10-01

    Full Text Available Highly selective Pd electrocatalysts were synthesized by the formic acid (FA method and evaluated as cathodes for DEGFC applications. In rotating disc measurements in acid medium, the Pd/C cathode showed important catalytic activity for the Oxygen Reduction Reaction (ORR. In the presence of ethylene glycol (EG, C2H6O2, Pd/C exhibited a noteworthy electrochemical behavior and full tolerance to the organic molecule. No current density peaks associated to the EG oxidation reaction emerged and the shift in onset potential for the ORR (Eonset toward more negative potentials was negligible on this cathode. As a comparison, commercial Pt/C was tested under the same conditions showing a poor selectivity for the ORR when EG was present. The detrimental effect of EG on the Pt electrocatalysts resulted in high intensity current density peaks due to the oxidation of EG and a significant shift in Eonset. The evaluation of Pd/C in a DEGFC operating at 80 °C demonstrated its good performance as cathode material. Given these results, it is expected that highly efficient Pd-based cathodes can find application in DEGFCs.

  9. 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.

  10. Robotic Variable Polarity Plasma Arc (VPPA) Welding

    Science.gov (United States)

    Jaffery, Waris S.

    1993-01-01

    The need for automated plasma welding was identified in the early stages of the Space Station Freedom Program (SSFP) because it requires approximately 1.3 miles of welding for assembly. As a result of the Variable Polarity Plasma Arc Welding (VPPAW) process's ability to make virtually defect-free welds in aluminum, it was chosen to fulfill the welding needs. Space Station Freedom will be constructed of 2219 aluminum utilizing the computer controlled VPPAW process. The 'Node Radial Docking Port', with it's saddle shaped weld path, has a constantly changing surface angle over 360 deg of the 282 inch weld. The automated robotic VPPAW process requires eight-axes of motion (six-axes of robot and two-axes of positioner movement). The robot control system is programmed to maintain Torch Center Point (TCP) orientation perpendicular to the part while the part positioner is tilted and rotated to maintain the vertical up orientation as required by the VPPAW process. The combined speed of the robot and the positioner are integrated to maintain a constant speed between the part and the torch. A laser-based vision sensor system has also been integrated to track the seam and map the surface of the profile during welding.

  11. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    Science.gov (United States)

    Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

    2008-02-01

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

  12. The Modification of Carbon with Iron Oxide Synthesized in Electrolysis Using the Arc Discharge Method

    Science.gov (United States)

    Endah Saraswati, Teguh; Dewi Indah Prasiwi, Oktaviana; Masykur, Abu; Handayani, Nestri; Anwar, Miftahul

    2017-02-01

    The modification of carbon-based nanomaterials with metals is widely studied due to its unique properties. Here, the modification of carbon nanomaterial with iron oxide has been successfully carried out. This modification was achieved using arc discharge in 50% ethanol liquid media. The anode used in the arc discharge was prepared from a mixture of carbon and iron oxide that was synthesized in electrolysis and was then calcined at 250°C with silicon binder with a mass ratio of 3:1:1, and the cathode used was graphite rod. Both electrodes were set in the nearest gap that could provide an arc during arc-discharging, leading to carbon-based nanoparticle formation. The diffractogram pattern of the X-ray diffraction of the fabricated nanoparticles confirmed the typical peak of carbon, iron oxide and iron. The magnetization value of the result analysis of the vibrating sample magnetometer was 9.9 emu/g. The bandgap energy measurement using diffuse reflectance ultra violet was estimated to be 2.18 eV. Using the transmission electron microscopy, the structure of the nanomaterial produced was observed as carbon-encapsulated iron compound nanoparticles.

  13. Review on MIEC Cathode Materials for Solid Oxide Fuel Cells

    Science.gov (United States)

    Burnwal, Suman Kumar; Bharadwaj, S.; Kistaiah, P.

    2016-11-01

    The cathode is one of the most important components of solid oxide fuel cells (SOFCs). The reduction of oxygen at the cathode (traditional cathodes like LSM, LSGM, etc.) is the slow step in the cell reaction at intermediate temperature (600-800∘C) which is one of the key obstacles to the development of SOFCs. The mixed ionic and electronic conducting cathode (MIEC) like LSCF, BSCF, etc., has recently been proposed as a promising cathode material for SOFC due to the improvement of the kinetic of the cathode reaction. The MIEC materials provide not only the electrons for the reduction of oxygen, but also the ionic conduction required to ensure the transport of the formed oxygen ions and thereby improves the overall electrochemical performance of SOFC system. The characteristics of MIEC cathode materials and its comparison with other traditional cathode materials is studied and presented in the paper.

  14. 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...

  15. 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...

  16. Klystron Amplifier Utilizing Scandate Cathode and Electrostatic Focusing Project

    Data.gov (United States)

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

  17. Statistical quality control for volumetric modulated arc therapy (VMAT) delivery by using the machine's log data

    Science.gov (United States)

    Cheong, Kwang-Ho; Lee, Me-Yeon; Kang, Sei-Kwon; Yoon, Jai-Woong; Park, Soah; Hwang, Taejin; Kim, Haeyoung; Kim, Kyoung Ju; Han, Tae Jin; Bae, Hoonsik

    2015-07-01

    The aim of this study is to set up statistical quality control for monitoring the volumetric modulated arc therapy (VMAT) delivery error by using the machine's log data. Eclipse and a Clinac iX linac with the RapidArc system (Varian Medical Systems, Palo Alto, USA) are used for delivery of the VMAT plan. During the delivery of the RapidArc fields, the machine determines the delivered monitor units (MUs) and the gantry angle's position accuracy and the standard deviations of the MU ( σMU: dosimetric error) and the gantry angle ( σGA: geometric error) are displayed on the console monitor after completion of the RapidArc delivery. In the present study, first, the log data were analyzed to confirm its validity and usability; then, statistical process control (SPC) was applied to monitor the σMU and the σGA in a timely manner for all RapidArc fields: a total of 195 arc fields for 99 patients. The MU and the GA were determined twice for all fields, that is, first during the patient-specific plan QA and then again during the first treatment. The sMU and the σGA time series were quite stable irrespective of the treatment site; however, the sGA strongly depended on the gantry's rotation speed. The σGA of the RapidArc delivery for stereotactic body radiation therapy (SBRT) was smaller than that for the typical VMAT. Therefore, SPC was applied for SBRT cases and general cases respectively. Moreover, the accuracy of the potential meter of the gantry rotation is important because the σGA can change dramatically due to its condition. By applying SPC to the σMU and σGA, we could monitor the delivery error efficiently. However, the upper and the lower limits of SPC need to be determined carefully with full knowledge of the machine and log data.

  18. 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

  19. 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.

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

    OpenAIRE

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

  2. A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

    Science.gov (United States)

    Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

    2015-09-28

    Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives.

  3. Tectonomagmatism in continental arcs: evidence from the Sark arc complex

    Science.gov (United States)

    Gibbons, Wes; Moreno, Teresa

    2002-07-01

    The island of Sark (Channel Islands, UK) exposes syntectonic plutons and country rock gneisses within a Precambrian (Cadomian) continental arc. This Sark arc complex records sequential pulses of magmatism over a period of 7 Ma (ca. 616-609 Ma). The earliest intrusion (ca. 616 Ma) was a composite sill that shows an ultramafic base overlain by a magma-mingled net vein complex subsequently deformed at near-solidus temperatures into the amphibolitic and tonalitic Tintageu banded gneisses. The deformation was synchronous with D 2 deformation of the paragneissic envelope, with both intrusion and country rock showing flat, top-to-the-south LS fabrics. Later plutonism injected three homogeneous quartz diorite-granodiorite sheets: the Creux-Moulin pluton (150-250 m; ca. 614 Ma), the Little Sark pluton (>700 m; 611 Ma), and the Northern pluton (>500 m; 609 Ma). Similar but thinner sheets in the south (Derrible-Hogsback-Dixcart) and west (Port es Saies-Brecqhou) are interpreted as offshoots from the Creux-Moulin pluton and Little Sark pluton, respectively. All these plutons show the same LS fabric seen in the older gneisses, with rare magmatic fabrics and common solid state fabrics recording syntectonic crystallisation and cooling. The cooling rate increased rapidly with decreasing crystallisation age: >9 Ma for the oldest intrusion to cool to lower amphibolite conditions, 7-8 Ma for the Creux Moulin pluton, 5-6 Ma for the Little Sark pluton, and 10 -14 s -1) that focussed extensional deformation into the Sark area. The increased rates of extension allowed ingress of the subsequent quartz diorite-granodiorite sheets, although strain rate slowly declined as the whole complex cooled during exhumation. The regional architecture of syntectonic Cadomian arc complexes includes flat-lying "Sark-type" and steep "Guernsey-type" domains produced synchronously in shear zone networks induced by oblique subduction: a pattern seen in other continental arcs such as that running from Alaska

  4. Uniform large-area thermionic cathode for SCALPEL

    Science.gov (United States)

    Katsap, Victor; Sewell, Peter B.; Waskiewicz, Warren K.; Zhu, Wei

    1999-11-01

    An electron beam lithography tool, which employs the SCALPEL technique, requires an extremely uniform beam to illuminate the scattering Mask, with the cathode operating in the temperature limited mode. It has been previously shown that LaB6 cathodes are not stable in this mode of operation. We have explored the possibility of implementing refined Tantalum-based emitters in the SCALPEL source cathode, and have developed large-area flat cathodes featuring suitably high emission uniformity under temperature limited operation.

  5. A Contribution to Arc Length Discussion

    Directory of Open Access Journals (Sweden)

    Stephan Egerland

    2015-09-01

    Full Text Available Abstract An investigation was raising the question: "What does 'arc length' mean?" Actually, it is considered expressing a kind of natural relationship between arc voltage and arc column shape. Statements such as "The higher the voltage the longer the arc" or "The arc voltage proves approximately proportional to the arc length", are frequently noticed in this conjunction. However, the author suggests that there is no general possibility of describing 'arc length' over the whole welding process range. Instances are represented in this paper, showing both theoretical attempts of definition and practical observations. This paper intends to contribute to a serious discussion of something trivial, indeed very well-known or used among welding experts, but actually yet hardly understood, at least as when it comes to closer examination

  6. In-process electrical discharge dressing of arc-shaped metal bonded diamond wheels

    Science.gov (United States)

    Wang, Kai; Fan, Fei; Tian, Guoyu; Zhang, Feihu; Liu, Zhongde

    2016-10-01

    Due to the high hardness of SiC ceramics, the wear of the arc-shaped metal bonded diamond wheels is very serious during the grinding process of large-aperture aspheric SiC mirrors. The surface accuracy and surface/sub-surface quality of the aspheric mirror will be affected seriously if the grinding wheel is not timely dressed. Therefore, this paper focus on the in-process dressing of the arc-shaped metal bonded diamond wheels. In this paper, the application of the asymmetric arc profile grinding wheel in the grinding of aspheric mirrors is discussed first. Then a rotating cup-shaped electrode in-process electro discharge dressing device for the arc-shaped wheels is developed based on the analysis. The dressing experiments are carried out with the device. The experimental results show that the in-process dressing device can did the dressing for the asymmetric and symmetric arc-shaped wheel. The profile error of the arc can reach to 3μm with the in-process dressing device.

  7. Optical properties of lamps with cold emission cathode

    Science.gov (United States)

    Kalenik, Jerzy; Czerwosz, ElŻbieta; Biernacki, Krzysztof; Rymarczyk, Joanna; Stepińska, Izabela

    2016-12-01

    A luminescent lamp was constructed and tested. Phosphor excited by electrons is the source of light. The source of electrons is field emission cathode. The cathode is covered with nickel-carbon layer containing carbon nanotubes that enhance electron emission from the cathode. Results of luminance measurements are presented. Luminance is high enough for lighting application.

  8. NOTE: Pre-clinical evaluation of respiratory-gated delivery of volumetric modulated arc therapy with RapidArc

    Science.gov (United States)

    Nicolini, Giorgia; Vanetti, Eugenio; Clivio, Alessandro; Fogliata, Antonella; Cozzi, Luca

    2010-06-01

    A study was carried out to evaluate the possibility of delivering volumetric modulated arc therapy with the RapidArc technology under respiratory-gated conditions. The experiments were performed in the framework of a non-clinically released environment. Plans of six patients, all realized for a single arc, were used for the experiments. The Real-time Position Management™ (RPM) respiratory gating system from Varian was used to generate gate-open signals of different durations. Arcs were delivered applying the different gates creating sequences of beam-hold/beam-on during the dose delivery: the average number of interruptions for a single arc ranged from 0 to 45. Dose prescription was set to 2 Gy and different gate-open periods of 30, 15 and 5 s to keep gantry speed constant at maximum. 5 Gy and 15 Gy doses were then applied to gate-open signals of 5 and 8 s, respectively, to mimic the most challenging conditions of slow gantry rotation and high-frequency interruptions. The 5 and 15 Gy experiments represent dose conditions of clinical interest for stereotactic treatments. For each patient and gating condition, pre-treatment 2D verification measurements were performed using the PTW-729 array in conjunction with the Octavius phantom (PTW, Freiburg); measurements were performed on different days (one per patient, with the complete setup of phantom and detectors every time), while each gating experiment was repeated seven consecutive times for reproducibility (without a new setup of the measurement equipment). Measurements were compared with dose calculations in the treatment planning system (performed without any gating) to appraise the dosimetric impact of the presence of gating and the eventual dependence from the number of interruptions during a single arc. Analysis of machine-registered log files in terms of average deviations between actual and expected positions (from automatic measurements every 50 ms) resulted in mean ΔMU (monitor units) <0.02% for all gating

  9. Pre-clinical evaluation of respiratory-gated delivery of volumetric modulated arc therapy with RapidArc.

    Science.gov (United States)

    Nicolini, Giorgia; Vanetti, Eugenio; Clivio, Alessandro; Fogliata, Antonella; Cozzi, Luca

    2010-06-21

    A study was carried out to evaluate the possibility of delivering volumetric modulated arc therapy with the RapidArc technology under respiratory-gated conditions. The experiments were performed in the framework of a non-clinically released environment. Plans of six patients, all realized for a single arc, were used for the experiments. The Real-time Position Management (RPM) respiratory gating system from Varian was used to generate gate-open signals of different durations. Arcs were delivered applying the different gates creating sequences of beam-hold/beam-on during the dose delivery: the average number of interruptions for a single arc ranged from 0 to 45. Dose prescription was set to 2 Gy and different gate-open periods of 30, 15 and 5 s to keep gantry speed constant at maximum. 5 Gy and 15 Gy doses were then applied to gate-open signals of 5 and 8 s, respectively, to mimic the most challenging conditions of slow gantry rotation and high-frequency interruptions. The 5 and 15 Gy experiments represent dose conditions of clinical interest for stereotactic treatments. For each patient and gating condition, pre-treatment 2D verification measurements were performed using the PTW-729 array in conjunction with the Octavius phantom (PTW, Freiburg); measurements were performed on different days (one per patient, with the complete setup of phantom and detectors every time), while each gating experiment was repeated seven consecutive times for reproducibility (without a new setup of the measurement equipment). Measurements were compared with dose calculations in the treatment planning system (performed without any gating) to appraise the dosimetric impact of the presence of gating and the eventual dependence from the number of interruptions during a single arc. Analysis of machine-registered log files in terms of average deviations between actual and expected positions (from automatic measurements every 50 ms) resulted in mean Delta MU (monitor units) <0.02% for all

  10. Pre-clinical evaluation of respiratory-gated delivery of volumetric modulated arc therapy with RapidArc

    Energy Technology Data Exchange (ETDEWEB)

    Nicolini, Giorgia; Vanetti, Eugenio; Clivio, Alessandro; Fogliata, Antonella; Cozzi, Luca, E-mail: lucozzi@iosi.c [Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona (Switzerland)

    2010-06-21

    A study was carried out to evaluate the possibility of delivering volumetric modulated arc therapy with the RapidArc technology under respiratory-gated conditions. The experiments were performed in the framework of a non-clinically released environment. Plans of six patients, all realized for a single arc, were used for the experiments. The Real-time Position Management(TM) (RPM) respiratory gating system from Varian was used to generate gate-open signals of different durations. Arcs were delivered applying the different gates creating sequences of beam-hold/beam-on during the dose delivery: the average number of interruptions for a single arc ranged from 0 to 45. Dose prescription was set to 2 Gy and different gate-open periods of 30, 15 and 5 s to keep gantry speed constant at maximum. 5 Gy and 15 Gy doses were then applied to gate-open signals of 5 and 8 s, respectively, to mimic the most challenging conditions of slow gantry rotation and high-frequency interruptions. The 5 and 15 Gy experiments represent dose conditions of clinical interest for stereotactic treatments. For each patient and gating condition, pre-treatment 2D verification measurements were performed using the PTW-729 array in conjunction with the Octavius phantom (PTW, Freiburg); measurements were performed on different days (one per patient, with the complete setup of phantom and detectors every time), while each gating experiment was repeated seven consecutive times for reproducibility (without a new setup of the measurement equipment). Measurements were compared with dose calculations in the treatment planning system (performed without any gating) to appraise the dosimetric impact of the presence of gating and the eventual dependence from the number of interruptions during a single arc. Analysis of machine-registered log files in terms of average deviations between actual and expected positions (from automatic measurements every 50 ms) resulted in mean {Delta}MU (monitor units) <0.02% for all

  11. Zircon Recycling in Arc Intrusions

    Science.gov (United States)

    Miller, J.; Barth, A.; Matzel, J.; Wooden, J.; Burgess, S.

    2008-12-01

    Recycling of zircon has been well established in arc intrusions and arc volcanoes, but a better understanding of where and how zircons are recycled can help illuminate how arc magma systems are constructed. To that end, we are conducting age, trace element (including Ti-in-zircon temperatures; TzrnTi) and isotopic studies of zircons from the Late Cretaceous (95-85 Ma) Tuolumne Intrusive Suite (TIS) in the Sierra Nevada Batholith (CA). Within the TIS zircons inherited from ancient basement sources and/or distinctly older host rocks are uncommon, but recycled zircon antecrysts from earlier periods of TIS-related magmatism are common and conspicuous in the inner and two most voluminous units of the TIS, the Half Dome and Cathedral Peak Granodiorites. All TIS units have low bulk Zr ([Zr]825°C), [Zr] in the TIS is a factor of 2 to 3 lower than saturation values. Low [Zr] in TIS rocks might be attributed to a very limited supply of zircon in the source, by disequilibrium melting and rapid melt extraction [1], by melting reactions involving formation of other phases that can incorporate appreciable Zr [2], or by removal of zircon at an earlier stage of magma evolution. Based on a preliminary compilation of literature data, low [Zr] is common to Late Cretaceous N.A. Cordilleran granodioritic/tonalitic intrusions (typically Tzrnsat [3]. A corollary is that slightly older zircon antecrysts that are common in the inner units of the TIS could be considered inherited if they are derived from remelting of slightly older intrusions. Remelting at such low temperatures in the arc would require a source of external water. Refs: [1] Sawyer, J.Pet 32:701-738; [2] Fraser et al, Geology 25:607-610; [3] Harrison et al, Geology 35:635- 638

  12. 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.

  13. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Wayne Huebner; Igor Kosacki

    2001-09-30

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. In this portion of study we have focused on producing YSZ films on porous LSM substrates. When using the polymer precursor there are a number of obstacles to overcome in order to form dense electrolyte layers on porous substrates (cathode or anode). Probably the most difficult problems are: (1) Extreme penetration of the polymer into the substrate must be prevented. (2) Shrinkage cracking must be avoided. (3) Film thickness in the 1 to 5{micro}m range must be achieved. We have demonstrated that cracking due to shrinkage involved during the elimination of solvents and organic matter and densification of the remaining oxide is not a problem as long as the resulting oxide film is < {approx} 0.15 {micro}m in thickness. We have also shown that we can make thicker films by making multiple depositions if the substrate is smooth (roughness {le} 0.1 {micro}m) and contains no surface pores > 0.2 {micro}m. The penetration of the polymer into the porous substrate can be minimized by increasing the viscosity of the polymer and reducing the largest pore at the surface of the substrate to {le} 0.2 {micro}m. We have shown that this can be done, but we have also shown that it is difficult to make dense films that are defect free with areas > 1 cm{sup 2}. This is because of the roughness of the substrate and the difficulty in making a substrate which does not have surface voids > 0.2 {micro}m. Thus the process works well for dense, smooth substrates for films < 1 {micro}m thick, but is difficult to apply to rough, porous surfaces and to make film thickness > 1 {micro}m. As a result of these problems, we have been addressing the issue of how to make dense films in the thickness range of 1 to 5 {micro}m on sintered porous substrates without introducing cracks and holes due to shrinkage and surface voids? These

  14. History of Neptune's Ring Arcs

    Science.gov (United States)

    Esposito, L. W.; Colwell, J. E.; Canup, R. M.

    1997-07-01

    The recent dynamical calculations for Neptune's Adams ring arcs by Foryta and Sicardy (1996) and Hanninen and Porco (1997) determine the basic evolutionary parameters for this system. The ring evolution is dominated by stochastic events, particularly chaotic motion that causes a migration between the corotation sites (FS96) and collisions near quadrature (HP97). A basic problem is that the high velocity collisions that produce the dusty arcs at the Galatea corotation resonances rapidly depopulate these sites (Colwell and Esposito 1990). With the new results in hand for the evolution of the ring particles over periods of less than a century, we can now calculate the long-term stochastic evolution of the Adams ring. Using a finite Markov chain as a model for this stochastic process, we follow the suggestion by FS96 that corotation sites provide preferential locations for accretion. A more general conclusion is that the longitudinal concentration of material in a few nearby sites (and that the majority of the Adams ring material is residing there) requires either an exceedingly recent event (EC92) or that the corotation sites be absorbing states of the Markov chain.In the latter case, the competing processes of chaotic diffusion and frustrated accretion can provide the arc and clump features as recurrent transient events near the Roche limit. Similar phenomena would be expected for Saturn's F and G rings.

  15. High-pressure hollow cathode discharges

    Science.gov (United States)

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

    1997-11-01

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

  16. ME1/1 Cathode Strip Chambers

    CERN Document Server

    Erchov, Yu V; Kamenev, Alexey; Karjavin, Vladimir; Khabarov, Serguei; Moissenz, P V; Moissenz, K P; Movchan, Sergey; Perelygin, Victor; Vassiliev, S E; Zarubin, Anatoli; Tchekhovski, V A

    2008-01-01

    The 76 innermost ME1/1 cathode strip chambers (CSC) of the CMS Experiment were designed and produced in Dubna. The chambers have been installed in the detector and commissioning has been completed. This paper describes the design of the CSCs, their main mechanical parameters and read-out electronics, and the results of tests with cosmic-ray muons.

  17. 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.

  18. 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

  19. H_2O and CO_2 in magmas from the Mariana arc and back arc systems

    OpenAIRE

    Newman, Sally; Stolper, Edward; STERN, Robert

    2000-01-01

    We examined the H2O and CO2 contents of glasses from lavas and xenoliths from the Mariana arc system, an intraoceanic convergent margin in the western Pacific, which contains an active volcanic arc, an actively spreading back arc basin, and active behind-the-arc cross-chain volcanoes. Samples include (1) glass rims from Mariana arc, Mariana trough, and cross-chain submarine lavas; (2) glass inclusions in arc and trough phenocrysts; and (3) glass inclusions from a gabbro + anorthosite xenolith...

  20. Arc Root Attachment on the Anode Surface of Arc Plasma Torch Observed with a Novel Method

    Institute of Scientific and Technical Information of China (English)

    PAN Wen-Xia; LI Teng; MENG Xian; CHEN Xi; WU Cheng-Kang

    2005-01-01

    @@ The arc-root attachment on the anode surface of a dc non-transferred arc plasma torch has been successfullyobserved using a novel approach. A specially designed copper mirror with a boron nitride film coated on itssurface central-region is employed to avoid the effect of intensive light emitted from the arc column upon theobservation of weakly luminous arc root. It is found that the arc-root attachment is diffusive on the anode surfaceof the argon plasma torch, while constricted arc roots often occur when hydrogen or nitrogen is added into argonas the plasma-forming gas.

  1. Highly zone-dependent synthesis of different carbon nanostructures using plasma-enhanced arc discharge technique

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajesh, E-mail: rajeshbhu1@gmail.com [Yonsei University, Department of Materials Science & Engineering (Korea, Republic of); Singh, Rajesh Kumar, E-mail: rksbhu@gmail.com [Banaras Hindu University, Department of Applied Physics, Indian Institute of Technology (India); Dubey, Pawan Kumar [University of Allahabad, Nanotechnology Application Centre (India); Yadav, Ram Manohar [Rice University, Department of Materials Science and Nano Engineering (United States); Singh, Dinesh Pratap [Universidad de Santiago de Chile, Departamento de Física (Chile); Tiwari, R. S.; Srivastava, O. N. [Banaras Hindu University, Department of Physics (India)

    2015-01-15

    Three kinds of carbon nanostructures, i.e., graphene nanoflakes (GNFs), multi walled carbon nanotubes (MWCNTs), and spherical carbon nanoparticles (SCNPs) were comparatively investigated in one run experiment. These carbon nanostructures are located at specific location inside the direct current plasma-assisted arc discharge chamber. These carbon nanomaterials have been successfully synthesized using graphite as arcing electrodes at 400 torr in helium (He) atmosphere. The SCNPs were found in the deposits formed on the cathode holder, in which highly curled graphitic structure are found in majority. The diameter varies from 20 to 60 nm and it also appears that these particles are self-assembled to each other. The MWCNTs with the diameter of 10–30 nm were obtained which were present inside the swelling portion of cathode deposited. These MWCNTs have 14–18 graphitic layers with 3.59 Å interlayer spacing. The GNFs have average lateral sizes of 1–5 μm and few of them are stacked layers and shows crumpled like structure. The GNFs are more stable at low temperature (low mass loss) but SCNPs have low mass loss at high temperature.

  2. Fully kinetic model of breakdown during sheath expansion after interruption of vacuum arcs

    Science.gov (United States)

    Wang, Zhenxing; Wang, Haoran; Zhou, Zhipeng; Tian, Yunbo; Geng, Yingsan; Wang, Jianhua; Liu, Zhiyuan

    2016-08-01

    Research on sheath expansion is critical to the understanding of the dielectric recovery process in a vacuum interrupter after interruption of vacuum arcs. In this paper, we investigated how residual plasma affects breakdown in the sheath expansion period after the current zero. To simulate sheath expansion and breakdown, we developed a fully kinetic particle-in-cell Monte Carlo collision model with one spatial dimension and three velocity dimensions. The model accounted for various collisions, including ionization, excitation, elastic collisions, charge exchange, and momentum exchange, and we added an external circuit to the model to make the calculations self-consistent. The existence of metal vapor slowed the sheath expansion in the gap and caused high electric field formation in front of the cathode surface. The initial residual plasma, which was at sufficiently low density, seemed to have a limited impact on breakdown, and the metal vapor dominated the breakdown in this case. Additionally, the breakdown probability was sensitive to the initial plasma density if the value exceeded a specific threshold, and plasma at sufficiently high density could mean that breakdown would occur more easily. We found that if the simulation does not take the residual plasma into account, it could overestimate the critical value of the metal vapor density, which is always used to describe the boundary of breakdown after interruption of vacuum arcs. We discussed the breakdown mechanism in sheath expansion, and the breakdown is determined by a combination of metal vapor, residual plasma, and the electric field in front of the cathode surface.

  3. Cathode depth sensing in CZT detectors

    Science.gov (United States)

    Hong, JaeSub; Bellm, Eric C.; Grindlay, Jonathan E.; Narita, Tomohiko

    2004-02-01

    Measuring the depth of interaction in thick Cadmium-Zinc-Telluride (CZT) detectors allows improved imaging and spectroscopy for hard X-ray imaging above 100 keV. The Energetic X-ray Imaging Survey Telescope (EXIST) will employ relatively thick (5 - 10 mm) CZT detectors, which are required to perform the broad energy-band sky survey. Interaction depth information is needed to correct events to the detector "focal plane" for correct imaging and can be used to improve the energy resolution of the detector at high energies by allowing event-based corrections for incomplete charge collection. Background rejection is also improved by allowing low energy events from the rear and sides of the detector to be rejected. We present experimental results of intereaction depth sensing in a 5 mm thick pixellated Au-contact IMARAD CZT detector. The depth sensing was done by making simultaneous measurements of cathode and anode signals, where the interaction depth at a given energy is proportional to the ratio of cathode/anode signals. We demonstrate how a simple empirical formula describing the event distributions in the cathode/anode signal space can dramatically improve the energy resolution. We also estimate the energy and depth resolution of the detector as a function of the energy and the interaction depth. We also show a depth-sensing prototype system currently under development for EXIST in which cathode signals from 8, 16 or 32 crystals can be read-out by a small multi-channel ASIC board that is vertically edge-mounted on the cathode electrode along every second CZT crystal boundary. This allows CZT crystals to be tiled contiguously with minimum impact on throughput of incoming photons. The robust packaging is crucial in EXIST, which will employ very large area imaging CZT detector arrays.

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

    Science.gov (United States)

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

    2017-07-01

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

  5. 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.

  6. Performance of water and hybrid stabilized electric arcs: the impact of dependence of radiation losses and plasma density on pressure

    Science.gov (United States)

    Jeništa, J.; Bartlová, M.; Aubrecht, V.

    2006-10-01

    Processes in the worldwide unique type of thermal plasma generator with water vortex stabilization and combined stabilization of arc by argon flow and water vortex have been numerically studied. Two-dimensional axisymmetric numerical model assumes laminar and compressible plasma flow in the state of local thermodynamic equilibrium. The calculation domain includes the arc discharge area between the near-cathode region and the outlet nozzle of the plasma torch. Radiation losses from the arc are calculated by the partial characteristics method for atmospheric pressure water and argon-water discharges. Thermal, electrical and fluid-dynamic characteristics of such arcs have been studied for the range of currents 150÷600 A under the assumption that radiation losses and plasma density depend linearly on pressure. It was proved that, taking this dependence into account, plasma velocity decrease while power losses from the arc by radiation and radial conduction increase with current. Outlet plasma temperature as well as electric potential drop remain practically unchanged.

  7. 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.

  8. 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.

  9. Virtual cathode microwave generator having annular anode slit

    Science.gov (United States)

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  10. Influence of residual plasma drift velocity on the post-arc sheath expansion of vacuum circuit breakers

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Yongpeng; Shi, Zongqian; Jia, Shenli; Wang, Lijun [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Bai, Zhibin [State Grid Yulin Electric Power Supply Company, Shaanxi 719000 (China)

    2016-05-15

    The residual plasma in the inter-contact region of a vacuum circuit breaker moves towards the post-arc cathode at current zero, because the residual plasma mainly comes from the cathode spots during the arc burning process. In the most previous theoretical researches on the post-arc sheath expansion process of vacuum circuit breakers, only the thermal motion of residual plasma was taken into consideration. Alternately, the residual plasma was even assumed to be static at the moment of current zero in some simplified models. However, the influence of residual plasma drift velocity at current zero on the post-arc sheath expansion process was rarely investigated. In this paper, this effect is investigated by a one-dimensional particle-in-cell model. Simulation results indicate that the sheath expands slower with higher residual plasma drift velocity in the initial sheath expansion stage. However, with the increase of residual plasma drift velocity, the overall plasma density in the inter-contact region decreases faster, and the sheath expansion velocity increases earlier. Consequently, as a whole, it needs shorter time to expel the residual plasma from the inter-contact region. Furthermore, if the residual plasma drift velocity is high enough, the sheath expansion process ceases before it develops to the post-arc anode. Besides, the influence of the collisions between charges and neutrals is investigated as well in terms of the density of metal vapor. It shows that the residual plasma drift velocity takes remarkable effect only if the density of the metal vapor is relatively low, which corresponds to the circumstance of low-current interruptions.

  11. Influence of residual plasma drift velocity on the post-arc sheath expansion of vacuum circuit breakers

    Science.gov (United States)

    Mo, Yongpeng; Shi, Zongqian; Bai, Zhibin; Jia, Shenli; Wang, Lijun

    2016-05-01

    The residual plasma in the inter-contact region of a vacuum circuit breaker moves towards the post-arc cathode at current zero, because the residual plasma mainly comes from the cathode spots during the arc burning process. In the most previous theoretical researches on the post-arc sheath expansion process of vacuum circuit breakers, only the thermal motion of residual plasma was taken into consideration. Alternately, the residual plasma was even assumed to be static at the moment of current zero in some simplified models. However, the influence of residual plasma drift velocity at current zero on the post-arc sheath expansion process was rarely investigated. In this paper, this effect is investigated by a one-dimensional particle-in-cell model. Simulation results indicate that the sheath expands slower with higher residual plasma drift velocity in the initial sheath expansion stage. However, with the increase of residual plasma drift velocity, the overall plasma density in the inter-contact region decreases faster, and the sheath expansion velocity increases earlier. Consequently, as a whole, it needs shorter time to expel the residual plasma from the inter-contact region. Furthermore, if the residual plasma drift velocity is high enough, the sheath expansion process ceases before it develops to the post-arc anode. Besides, the influence of the collisions between charges and neutrals is investigated as well in terms of the density of metal vapor. It shows that the residual plasma drift velocity takes remarkable effect only if the density of the metal vapor is relatively low, which corresponds to the circumstance of low-current interruptions.

  12. Gliding arc surface treatment of glass-fiber-reinforced polyester enhanced by ultrasonic irradiation

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Norrman, Kion; Drews, Joanna Maria

    2011-01-01

    A gliding arc is a plasma generated between diverging electrodes and extended by a high speed gas flow. It can be operated in air at atmospheric pressure. It potentially enables selective chemical processing with high productivity, and is useful for adhesion improvement of material surfaces....... The efficiency of such a plasma treatment at atmospheric pressure can be further improved by ultrasonic irradiation onto the surface during the treatment. In the present work glass fiber reinforced polyester (GFRP) plates are treated using an atmospheric pressure gliding arc with and without ultrasonic...... that ultrasonic irradiation reduced the OH rotational temperature of the gliding arc. The wettability of the GFRP surface was significantly improved by the plasma treatment without ultrasonic irradiation, and tended to improve furthermore at higher power to the plasma. Ultrasonic irradiation during the plasma...

  13. Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: circuitry and mechanical design.

    Science.gov (United States)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

    A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

  14. Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: Circuitry and mechanical design

    Science.gov (United States)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

    A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

  15. Rotator cuff repair - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100229.htm Rotator cuff repair - series—Normal anatomy To use the sharing ... to slide 4 out of 4 Overview The rotator cuff is a group of muscles and tendons that ...

  16. Novel one-step synthesis of wool-ball-like Ni-carbon nanotubes composite cathodes with favorable electrocatalytic activity for hydrogen evolution reaction in alkaline solution

    Science.gov (United States)

    Chen, Zhouhao; Ma, Zhipeng; Song, Jianjun; Wang, Lixin; Shao, Guangjie

    2016-08-01

    In this work, supergravity fields are performed to prepare Ni-CNTs composite cathodes with wool-ball-like morphology from the Watts bath containing well-distributed functionalized CNTs. The prepared Ni-CNTs composite cathodes are used as noble metal-free electrocatalyst with favorable electrocatalytic activity for hydrogen evolution reaction (HER) in alkaline solutions. The crystal structure and morphology of the composite cathodes are characterized by XRD and SEM measurements. The electrochemical activities of the cathodes are characterized through Tafel polarization measurement, electrochemical impedance spectroscopy and cyclic voltammetric study in 1.0 M NaOH solution. The results indicate that catalytic activities of the Ni-CNTs cathodes prepared under supergravity fields are enhanced significantly, and the sample prepared at rotating speed 3000 rpm from the bath containing 1 g dm-3 CNTs exhibits the highest HER activity with smallest Tafel slope and largest exchange current density of 823.9 μA cm-2. Furthermore, the effects of both the CNTs concentrations and the intensities of supergravity fields on the properties of the Ni-CNTs cathodes are investigated.

  17. Petrologic, tectonic, and metallogenic evolution of the Ancestral Cascades magmatic arc, Washington, Oregon, and northern California

    Science.gov (United States)

    du Bray, Edward A.; John, David A.

    2011-01-01

    reflects extensional tectonics that dominated during these periods of arc magmatism. Mineral deposits associated with ancestral Cascades arc rocks are uncommon; most are small and low grade relative to those found in other continental magmatic arcs. The small size, low grade, and dearth of deposits, especially in the southern two-thirds of the ancestral arc, probably reflect many factors, the most important of which may be the prevalence of extensional tectonics within this arc domain during this magmatic episode. Progressive clockwise rotation of the forearc block west of the evolving Oregon part of the ancestral Cascades magmatism produced an extensional regime that did not foster significant mineral deposit formation. In contrast, the Washington arc domain developed in a transpressional to mildly compressive regime that was more conducive to magmatic processes and hydrothermal fluid channeling critical to deposit formation. Small, low-grade porphyry copper deposits in the northern third of the ancestral Cascades arc segment also may be a consequence of more mature continental crust, including a Mesozoic component, beneath Washington north of Mount St. Helens.

  18. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  19. Programming ArcGIS with Python cookbook

    CERN Document Server

    Pimpler, Eric

    2015-01-01

    Programming ArcGIS with Python Cookbook, Second Edition, is written for GIS professionals who wish to revolutionize their ArcGIS workflow with Python. Whether you are new to ArcGIS or a seasoned professional, you almost certainly spend time each day performing various geoprocessing tasks. This book will teach you how to use the Python programming language to automate these geoprocessing tasks and make you a more efficient and effective GIS professional.

  20. Statistical analysis of geographic information with ArcView GIS and ArcGIS

    National Research Council Canada - National Science Library

    Wong, David W. S; Lee, Jay

    2005-01-01

    ... of its capabilities for spatial-quantitative synthesis. Now, David Wong and Jay Lee update their comprehensive handbook with Statistical Analysis of Geographic Information with ArcView GIS and ArcGIS...

  1. Rotations with Rodrigues' Vector

    Science.gov (United States)

    Pina, E.

    2011-01-01

    The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…

  2. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    2001-01-01

    In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...

  3. High-Performance Carbon Aerogel Air Cathodes for Microbial Fuel Cells

    KAUST Repository

    Zhang, Xiaoyuan

    2016-08-11

    Microbial fuel cells (MFCs) can generate electricity from the oxidation of organic substrates using anodic exoelectrogenic bacteria and have great potential for harvesting electric energy from wastewater. Improving oxygen reduction reaction (ORR) performance at a neutral pH is needed for efficient energy production. Here we show a nitrogen doped (≈4 wt%) ionothermal carbon aerogel (NDC) with a high surface area, large pore volume, and hierarchical porosity, with good electrocatalytic properties for ORR in MFCs. The MFCs using NDC air cathodes achieved a high maximum power density of 2300 mW m−2, which was 1.7 times higher than the most commonly used Pt/C air cathodes and also higher than most state-of-the-art ORR catalyst air cathodes. Rotating disk electrode measurements verified the superior electrocatalytic activity of NDC with an efficient four-electron transfer pathway (n=3.9). These findings highlight NDC as a better-performing and cost-efficient catalyst compared with Pt/C, making it highly viable for MFC applications.

  4. The Confinement of Neptune's Ring Arcs

    Science.gov (United States)

    Porco, C.; Namouni, F.

    2002-09-01

    The stability of the narrow ring arcs of Neptune has been a puzzle since their discovery. First detected in 1984 from the Earth in stellar occultations and imaged by the Voyager spacecraft in 1989, the 5 arcs spanning approximately 40 deg in longitude are apparently confined against the rapid azimuthal and radial spreading that results from energy dissipation in inter-particle collisions. Voyager data were used to argue in favor of an arc confinement model (Goldreich et al. AJ 1986; Porco, Science 1991) that relies on both the vertical and mean angular motions of the nearby Neptunian moon, Galatea, to produce a pair of Lindblad (LR) and corotation inclination (CIR) resonances capable of trapping ring particles into a sequence of arcs. However, HST and Earth-based observations taken in 1998 (Dumas et al. Nature 1999; Sicardy et al. Nature 1999) indicate a revised arc mean angular motion which displaces the arcs away from the CIR, leaving their stability once again unexplained. In this presentation, we will discuss the workings of a hitherto neglected resonance which relies on Galatea's orbital eccentricity and which, together with the LR, is likely responsible for the angular confinement of the arcs. The action of this resonance, which operates through the precession of Galatea's eccentric orbit forced by the arcs' inertia, will allow a determination of the arcs' mass from future measurements of Galatea's eccentricity. We acknowledge the financial support of NASA's Planetary Geology and Geophysics Program and the Southwest Research Institute's Internal Research Grant program.

  5. The Team Orienteering Arc Routing Problem

    OpenAIRE

    Archetti, Claudia; Speranza, M. Grazia; Corberan, Angel; Sanchís Llopis, José María; Plana, Isaac

    2014-01-01

    The team orienteering arc routing problem (TOARP) is the extension to the arc routing setting of the team orienteering problem. In the TOARP, in addition to a possible set of regular customers that have to be serviced, another set of potential customers is available. Each customer is associated with an arc of a directed graph. Each potential customer has a profit that is collected when it is serviced, that is, when the associated arc is traversed. A fleet of vehicles with a given maximum trav...

  6. Electrode Evaporation Effects on Air Arc Behavior

    Institute of Scientific and Technical Information of China (English)

    LI Xingwen; CHEN Degui; LI Rui; WU Yi; NIU Chunping

    2008-01-01

    A numerical study of the effects of copper and silver vapours on the air arc behavior is performed. The commercial software FLUENT is adapted and modified to develop a two-dimensional magneto-hydrodynamic (MHD) models of arc with the thermodynamic properties and transport coefficients, net emission coefficient for the radiation model of 99% ai-1% Cu, 99% air-1% Ag, and pure air, respectively. The simulation result demonstrates that vaporization of the electrode material may cool the arc center region and reduce the arc velocity. The effects of Ag vapour are stronger compared to those of Cu vapour.

  7. Metals purification by improved vacuum arc remelting

    Science.gov (United States)

    Zanner, Frank J.; Williamson, Rodney L.; Smith, Mark F.

    1994-12-13

    The invention relates to improved apparatuses and methods for remelting metal alloys in furnaces, particularly consumable electrode vacuum arc furnaces. Excited reactive gas is injected into a stationary furnace arc zone, thus accelerating the reduction reactions which purify the metal being melted. Additionally, a cooled condensation surface is disposed within the furnace to reduce the partial pressure of water in the furnace, which also fosters the reduction reactions which result in a purer produced ingot. Methods and means are provided for maintaining the stationary arc zone, thereby reducing the opportunity for contaminants evaporated from the arc zone to be reintroduced into the produced ingot.

  8. Class `E` protective headwear: electric arc exposure

    Energy Technology Data Exchange (ETDEWEB)

    Jones, E.

    1997-04-01

    A series of tests were conducted using electric arcs under laboratory conditions to determine what, if any, damages can be inflicted upon class `E` hard hats. Ten hard hats were subjected to different levels of arc exposure to see if the hat would ignite, melt, drip, stick to the head, etc. It was noted that there is no standard on hard hat exposure to an electric arc. It was recommended that the CSA committee revise the protective headwear standard to include a requirement for flame/arc resistance, including specification of pass/fail criteria. 1 tab., 3 figs.

  9. Boxicity of Circular Arc Graphs

    OpenAIRE

    Bhowmick, Diptendu; Chandran, L. Sunil

    2008-01-01

    A $k$-dimensional box is the cartesian product $R_1 \\times R_2 \\times ... \\times R_k$ where each $R_i$ is a closed interval on the real line. The {\\it boxicity} of a graph $G$, denoted as $box(G)$, is the minimum integer $k$ such that $G$ can be represented as the intersection graph of a collection of $k$-dimensional boxes: that is two vertices are adjacent if and only if their corresponding boxes intersect. A circular arc graph is a graph that can be represented as the intersection graph of ...

  10. Feedback Linearization Based Arc Length Control for Gas Metal Arc Welding

    DEFF Research Database (Denmark)

    Thomsen, Jesper Sandberg

    2005-01-01

    In this paper a feedback linearization based arc length controller for gas metal arc welding (GMAW) is described. A nonlinear model describing the dynamic arc length is transformed into a system where nonlinearities can be cancelled by a nonlinear state feedback control part, and thus, leaving only...

  11. Cathode material comparison of thermal runaway behavior of Li-ion cells at different state of charges including over charge

    Science.gov (United States)

    Mendoza-Hernandez, Omar Samuel; Ishikawa, Hiroaki; Nishikawa, Yuuki; Maruyama, Yuki; Umeda, Minoru

    2015-04-01

    The analysis of Li-ion secondary cells under outstanding conditions, as overcharge and high temperatures, is important to determine thermal abuse characteristics of electroactive materials and precise risk assessments on Li-ion cells. In this work, the thermal runaway behavior of LiCoO2 and LiMn2O4 cathode materials were compared at different state of charges (SOCs), including overcharge, by carrying out accelerating rate calorimetry (ARC) measurements using 18650 Li-ion cells. Onset temperatures of self-heating reactions and thermal runaway behavior were identified, and by using these onset points thermal mapping plots were made. We were able to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge and temperature. The cell using LiMn2O4 cathode material was found to be more thermally stable than the cell using LiCoO2. In parallel with the ARC measurements, the electrochemical behavior of the cells was monitored by measuring the OCV and internal resistance of the cells. The electrochemical behavior of the cells showed a slightly dependency on SOC.

  12. Predictors of human rotation.

    Science.gov (United States)

    Stochl, Jan; Croudace, Tim

    2013-01-01

    Why some humans prefer to rotate clockwise rather than anticlockwise is not well understood. This study aims to identify the predictors of the preferred rotation direction in humans. The variables hypothesised to influence rotation preference include handedness, footedness, sex, brain hemisphere lateralisation, and the Coriolis effect (which results from geospatial location on the Earth). An online questionnaire allowed us to analyse data from 1526 respondents in 97 countries. Factor analysis showed that the direction of rotation should be studied separately for local and global movements. Handedness, footedness, and the item hypothesised to measure brain hemisphere lateralisation are predictors of rotation direction for both global and local movements. Sex is a predictor of the direction of global rotation movements but not local ones, and both sexes tend to rotate clockwise. Geospatial location does not predict the preferred direction of rotation. Our study confirms previous findings concerning the influence of handedness, footedness, and sex on human rotation; our study also provides new insight into the underlying structure of human rotation movements and excludes the Coriolis effect as a predictor of rotation.

  13. Pulsed current cathodic protection of well casings

    Energy Technology Data Exchange (ETDEWEB)

    Bich, N.N. [Shell Canada Ltd., Fort Saskatchewan, Alberta (Canada). Scotford Complex; Bauman, J. [Shell Canada Ltd., Cochrane, Alberta (Canada). Jumping Pound Complex

    1995-04-01

    Electric pulses of several hundred volts, applied for very brief periods of time, several thousand times per second, are more effective and economical than conventional steady-state DC currents in protecting deep and/or close-spaced well casings against external corrosion. More uniform current distribution, greater depth of protection, reduced stray current interference, and small anode bed requirements are the main benefits of pulsed technology. Operating principles, equivalent electrical circuits, design considerations, and field cathodic protection logging experience is reviewed.

  14. Plasma Cathode for E-Beam Lasers

    Science.gov (United States)

    1975-08-01

    JMJIIJUillWWpi^WiffW^HipaHIP’Pi1’’’ "a" ii.lllVi;lM’iiWMlMBfj!|l|>WiiU|’lUW"L’l’w«|M>l|Wy™.^J"^^y-ff^w», iitM ^^^ The 4 cm x 40 cm plasma cathode e-gun, which is

  15. The Hollow Cathode Phase of Pseudospark Operation

    Science.gov (United States)

    1993-06-01

    THE HOLLOW CATHODE PHASE OF PSEUDOSPARK OPERATION L. Pitchford and J. P. Boeuf University Paul Sabatier, France V. Puech University De Paris-Sud...ORGANIZATION NAME(S) AND ADDRESS(ES) University Paul Sabatier, France 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME...Appl. Phys. 53, 1699 (1988). [9] A. Anders, S. Anders, and M. Gundersen, submitted to Phys. Rev. Lett. [10] J. P. Boeuf and L. Pitchford , IEEE

  16. Cathodic Cage Plasma Nitriding: An Innovative Technique

    OpenAIRE

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

    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...

  17. FUZZY LOGIC CONTROLLED CATHODIC PROTECTION CIRCUIT DESIGN

    OpenAIRE

    AKÇAYOL, M. Ali

    2010-01-01

    In this study, output voltage of automatic transformer-rectifier (TR) unit of impressed current cathodic protection has been controlled by using fuzzy logic controller. To prevent corrosion, voltage between the protection metal and the auxiliary anode has to be controlled on a desired level. Because soil resistance in the environment changes with humidity and soil characteristics, TRs must control the output voltage between protection metal and auxiliary anode automatically. In this study, a ...

  18. Modeling lithium/hybrid-cathode batteries

    Energy Technology Data Exchange (ETDEWEB)

    Gomadam, Parthasarathy M.; Merritt, Don R.; Scott, Erik R.; Schmidt, Craig L.; Skarstad, Paul M. [Medtronic Energy and Component Center, 6700 Shingle Creek Pkwy, Brooklyn Center, MN 55430 (United States); Weidner, John W. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2007-12-06

    This document describes a first-principles-based mathematical model developed to predict the voltage-capacity behavior of batteries having hybrid cathodes comprising a mixture of carbon monofluoride (CF{sub x}) and silver vanadium oxide (SVO). These batteries typically operate at moderate rates of discharge, lasting several years. The model presented here is an accurate tool for design optimization and performance prediction of batteries under current drains that encompass both the application rate and accelerated testing. (author)

  19. Nanodiamond embedded ta-C composite film by pulsed filtered vacuum arc deposition from a single target

    Science.gov (United States)

    Iyer, Ajai; Etula, Jarkko; Ge, Yanling; Liu, Xuwen; Koskinen, Jari

    2016-11-01

    Detonation Nanodiamonds (DNDs) are known to have sp3 core, sp2 shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp3 content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness.

  20. The spatial rotator

    DEFF Research Database (Denmark)

    Rasmusson, Allan; Hahn, Ute; Larsen, Jytte Overgaard

    2013-01-01

    to identify the specific tissue region under study. In order to use the spatial rotator in practice, however, it is necessary to be able to identify intersection points between cell boundaries and test rays in a series of parallel focal planes, also at the peripheral parts of the cell boundaries. In cases......This paper presents a new local volume estimator, the spatial rotator, which is based on measurements on a virtual 3D probe, using computer assisted microscopy. The basic design of the probe builds upon the rotator principle which requires only a few manual intersection markings, thus making...... the spatial rotator fast to use. Since a 3D probe is involved, it is expected that the spatial rotator will be more efficient than the the nucleator and the planar rotator, which are based on measurements in a single plane. An extensive simulation study shows that the spatial rotator may be more efficient...