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Sample records for vacuum arc discharge

  1. Technological ion sources based on the vacuum arc discharge

    CERN Document Server

    Bugaev, S P; Oks, E M; Yushkov, G Y; Shchanin, P M; Braun, Y

    2001-01-01

    The Titan service ion sources are designed to generate wide-aperture high-current ion beams of gases or metals, as well as, mixed two-component gas and metal ion beams with the controllable ratio of components in a beam. This possibility is achieved via integration of two discharge systems in a source discharge system. To generate metal ions one uses a vacuum, arc discharge, while gas ions are generated by a low pressure contracted arc discharge with cold cathodes. The paper describes operation of these sources, their design, technical characteristics, peculiarities of their operation and application fields

  2. Influence of discharge gap on the discharge stability in a short vacuum arc ion sourcea)

    Science.gov (United States)

    Chen, L.; Zhang, G. L.; Jin, D. Z.; Yang, L.; Dai, J. Y.

    2012-02-01

    The influence of the discharge gap between cathode and anode on the discharge stability in a short vacuum arc (SVA) ion source is presented in this paper. Planar cathode and cylindrical hollow anode made of titanium are investigated. There is a great need in present accelerator injection research for SVA source to produce the small deviation of the ion current beam. Current research shows that increasing the short discharge gap can reduce the level of ion current deviation and ion charge deviation from 29% and 31% to 15% and 17%, respectively. A microplasma plume generation mechanism in SVA and scanning electron microscopic results can be used to explain this interesting phenomenon.

  3. Influence of discharge gap on the discharge stability in a short vacuum arc ion source

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L. [Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Zhang, G. L.; Jin, D. Z.; Dai, J. Y. [Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Yang, L. [Institute of Nuclear Science and Technology, Louzhou University, Lanzhou, Gansu 730000 (China)

    2012-02-15

    The influence of the discharge gap between cathode and anode on the discharge stability in a short vacuum arc (SVA) ion source is presented in this paper. Planar cathode and cylindrical hollow anode made of titanium are investigated. There is a great need in present accelerator injection research for SVA source to produce the small deviation of the ion current beam. Current research shows that increasing the short discharge gap can reduce the level of ion current deviation and ion charge deviation from 29% and 31% to 15% and 17%, respectively. A microplasma plume generation mechanism in SVA and scanning electron microscopic results can be used to explain this interesting phenomenon.

  4. Fabrication of graphene from graphite by a thermal assisted vacuum arc discharge system

    Science.gov (United States)

    Cheng, Guo-Wei; Chu, Kevin; Chen, Jeng Shiung; Tsai, Jeff T. H.

    2017-04-01

    In this study, graphene was fabricated on copper foils using a high temperature furnace embedded in a vacuum arc discharge method. Combining the advantages of chemical vapor deposition and vacuum arc discharge, single-layer graphene can be fabricated at 600 °C base temperature from the mini furnace embedded with a fast heating via the photon radiation from the vacuum arc to 1100 °C on the substrates' surface. The optimal fabrication condition was determined through a series of experiments on ambient pressure, processing time, arc currents, and the cooling process. Observations by scanning electron microscopy, Raman spectroscopy, and optical microscopy showed that the main products were single-layer graphene, which has a uniform thickness across the entire substrate. The results demonstrated that the combination of a vacuum arc with a thermal method that uses graphite as a carbon source provides a low-cost and straight forward method to synthesize graphene films for graphene-based applications.

  5. Influence of Magnetic Field on Vacuum Arc Discharge Volt-Ampere Characteristics

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2015-01-01

    Full Text Available The vacuum arc evaporation technology was developed in the 70-s in the USSR and widely used nowadays for deposition of various functional coatings. Magnetic field provides stabilization of the discharge and cathode spot movement in arc evaporators. Usually, are used two types of magnetic systems: with divergent axisymmetrical magnetic field and with an arch-like magnetic field. The systems with the arch-like magnetic field allow a flexible control of the trajectory and the speed of the moving cathode spot and, recently, have been increasingly frequently used in facilities of vacuum arc deposition of coatings.Since the plasma of vacuum arc discharge is almost in completely ionized state even the weak magnetic fields have a significant influence on the vacuum arc discharge volt-ampere characteristics (VAC. Unfortunately, with a wealth of materials concerning the vacuum arc discharge there is still insufficient information about the influence of magnetic field magnitude and shape on the arc discharge VAC of the industrial arc evaporators.This work studies the effect of magnetic fields on VAC of two different arc evaporators with a titanium cathode, which possess axial and arch-like magnetic field.It was shown that the magnetic field significantly affects the VAC behavior changing it from increasing to descending one. The transition of VAC curves behavior from growing to descending one occurs at magnetic field values of 4.4 mT and 6.5 mT for axial and arch-like magnetic field, respectively.Voltage at fixed discharge current linearly increases with raising magnetic field induction. The discharge voltage growth with the arch-like magnetic field is greater than with its axial configuration.At the same time in the work the analytical expressions are given. These equations show that the VAC shape modification of the vacuum arc discharge in an external magnetic field may be explained by the inverse proportionality of the Hall parameter on its

  6. Plasma of a vacuum-arc discharge for obtaining carbon-based coatings

    Science.gov (United States)

    Pikus, M. I.; Lisenkov, A. A.; Kostrin, D. K.; Trifonov, S. A.

    2017-11-01

    Formation of the carbon films and coatings of different structural modifications can be efficiently achieved by sputtering graphite in a vacuum-arc plasma source. In this case the plasma flux is shaped in a form of a current-carrying jet with fairly distinct lateral borders. Spectral analysis shows that this plasma flux contains positively charged, excited and neutral carbon particles. In this paper is shown that for a technological cycle of deposition of a carbon-based coating it is possible to form a sublayer of the substrate material carbide, providing a possibility for the later growth of a well-formed coating.

  7. Model of liquid-metal splashing in the cathode spot of a vacuum arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Gashkov, M. A.; Zubarev, N. M., E-mail: nick@iep.uran.ru; Zubareva, O. V.; Mesyats, G. A.; Uimanov, I. V. [Russian Academy of Sciences, Institute of Electrophysics, Ural Branch (Russian Federation)

    2016-04-15

    The formation of microjets is studied during the extrusion of a melted metal by the plasma pressure from craters formed on a cathode in a burning vacuum arc. An analytic model of liquid-metal splashing that includes two stages is proposed. At the first stage, the liquid motion has the axial symmetry and a liquid-metal wall surrounding the crater is formed. At the second stage, the axial symmetry is broken due to the development of the Plateau–Rayleigh instability in the upper part of the wall. The wall breakup process is shown to have a threshold. The minimal plasma pressure and the minimal electric current flowing through the crater required for obtaining the liquid-metal splashing regime are found. The basic spatial and temporal characteristics of the jet formation process are found using the analytic model.

  8. Vacuum Arc Ion Sources

    CERN Document Server

    Brown, I.

    2013-12-16

    The vacuum arc ion source has evolved into a more or less standard laboratory tool for the production of high-current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. Applications include primarily ion implantation for material surface modification research, and good performance has been obtained for the injection of high-current beams of heavy-metal ions, in particular uranium, into particle accelerators. As the use of the source has grown, so also have the operational characteristics been improved in a variety of different ways. Here we review the principles, design, and performance of vacuum arc ion sources.

  9. Modeling Vacuum Arcs On Spacecraft Solar Panel Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft charging and subsequent vacuum arcing poses a significant threat to satellites in LEO and GEO plasma conditions. Localized arc discharges can cause a...

  10. 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.

  11. Diffuse vacuum arc with cerium oxide hot cathode

    Science.gov (United States)

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

    2016-11-01

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

  12. Angular distribution of plasma in the vacuum arc ion source.

    Science.gov (United States)

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

    2012-02-01

    This paper presents measurements of the angular distribution of the plasma components and different charge states of metal ions generated by a MEVVA-type ion source and measured by a time-of-flight mass-spectrometer. The experiments were performed for different cathode materials (Al, Cu, and Ti) and for different parameters of the vacuum arc discharge. The results are compared with prior results reported by other authors. The influence of different discharge parameters on the angular distribution in a vacuum arc source is discussed.

  13. 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.

  14. Arc Discharge Electrode Phenomena

    Science.gov (United States)

    Ecker, G.

    The ASI was dedicated to the topic "Electrical Breakdown and Discharges in Gases," — a part of the general field called "Gaseous Electronics." There are physicists — more than a few — who have hardly heard about Gaseous Electronics. There are others — particularly, so called pure theoreticians — who consider this field the esoterica of physics filled with bizarre oddities. But there are also those experts who dared to look closer into this field and found that it has many fascinating and tempting aspects combining extreme features from various fields of physics.

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

    Science.gov (United States)

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

    2014-11-01

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

  16. A novel post-arc current measuring equipment based on vacuum arc commutation and arc blow

    Science.gov (United States)

    Liao, Minfu; Ge, Guowei; Duan, Xiongying; Huang, Zhihui

    2017-07-01

    The paper proposes a novel post-arc current measuring equipment (NPACME), which is based on the vacuum arc commutation and magnetic arc blow. The NPACME is composed of the vacuum circuit breaker (VCB), shunt resistor, protective gap, high-precision current sensor and externally applied transverse magnetic field (ETMF). The prototype of the NPACME is designed and controlled by optical fiber communications. The vacuum arc commutation between the vacuum arc and the shunt resistor with ETMF is investigated. The test platform is established in the synthetic short-circuit test and the vacuum arc is observed by the high speed CMOS camera. The mathematic description of the vacuum arc commutation is obtained. Based on the current commutation characteristic, the parameters of the NPACME are optimized and the post-arc current is measured. The measuring result of the post-arc current is accurate with small interference and the post-arc charge is obtained. The experimental results verify that the NPACME is correct and accurate, which can be used to measure the post-arc characteristic in breaking test.

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Science.gov (United States)

    Xiang, W; Li, M; Chen, L

    2012-02-01

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

  19. Vacuum Arc Ion Sources: Recent Developments and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Ian; Oks, Efim

    2005-05-01

    The vacuum arc ion source has evolved over the past twenty years into a standard laboratory tool for the production of high current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. The primary application of this kind of source has evolved to be ion implantation for material surface modification. Another important use is for injection of high current beams of heavy metal ions into the front ends of particle accelerators, and much excellent work has been carried out in recent years in optimizing the source for reliable accelerator application. The source also provides a valuable tool for the investigation of the fundamental plasma physics of vacuum arc plasma discharges. As the use of the source has grown and diversified, at the same time the ion source performance and operational characteristics have been improved in a variety of different ways also. Here we review the growth and status of vacuum arc ion sources around the world, and summarize some of the applications for which the sources have been used.

  20. Advances in high voltage insulation and arc interruption in SF6 and vacuum

    CERN Document Server

    Maller, V N

    1982-01-01

    Advances in High Voltage Insulation and Arc Interruption in SF6 and Vacuum deals with high voltage breakdown and arc extinction in sulfur hexafluoride (SF6) and high vacuum, with special emphasis on the application of these insulating media in high voltage power apparatus and devices. The design and developmental aspects of various high voltage power apparatus using SF6 and high vacuum are highlighted. This book is comprised of eight chapters and opens with a discussion on electrical discharges in SF6 and high vacuum, along with the properties and handling of SF6 gas. The following chapters fo

  1. Suprathermal electrons in a vacuum spark discharge

    Energy Technology Data Exchange (ETDEWEB)

    Bashutin, O. A., E-mail: boa308@mail.ru; Savjolov, A. S., E-mail: savjolov@plasma.mephi.ru [National Research Nuclear University MEPhI (Russian Federation)

    2016-04-15

    Results of experiments on the detection of suprathermal electron beams in the plasma of a highcurrent low-inductance vacuum spark by means of space-resolved spectral X-ray polarimetry are presented. It is shown that the observed polarization of bremsstrahlung may be caused by an ~100-keV electron beam propagating along the discharge axis from the pinching region toward the anode. The influence of the discharge initiation conditions on the parameters of the generated electron beams is analyzed.

  2. Bibliography and author index for electrical discharges in vacuum (1897 to 1980)

    Energy Technology Data Exchange (ETDEWEB)

    Miller, H.C.

    1982-01-29

    This bibliography covers the field of electrical discharges in vacuum, comprising both electrical breakdown in vacuum and vacuum arcs. A brief review section lists some review papers which would be helpful to the novice in this field. The bulk of the paper consists of bibliographic listings, arranged by year of publication and within each year, alphabetically by first author. An author index refers one to all papers authored or coauthored by a particular person. There are 2450 papers listed through December 1980.

  3. Investigating Discharge Ignition Fundamentals of Micro-Cathode Arc Thrusters

    Science.gov (United States)

    Teel, George Lewis

    This dissertation is a compilation of studies of the volatile process that vacuum arcs undergo, known as breakdown. Breakdown is a transfer of electrons from one electrode to another. These electrons typically bombard the electrode surfaces causing secondary electron emission and ionization. This expulsion of ions and electrons then proceed to cause arc discharge, is what most people associate as ``the spark.'' This field-emission to breakdown process induces localized heating, which then causes this explosive ionization to occur. Once plasma is formed, high temperatures and pressures are forced on the surrounding surfaces. This initiation process, the effects of this process, and the manipulation of these effects have all been studied and described in this work. A series of initial observations of the before and after effects of discharge have been made through various equipment such as a Scanning Electron Microscope, Energy Dispersive X-Ray, and Confocal Microscope. Methods to develop a resistance measurement scheme provided a means to characterize the thruster's operation over its lifetime. Further characterization of the plasma plume was done through the use of Langmuir probes. Temperature and density distributions were also measured. An entirely new and miniaturized design of the thrusters were developed and initially tested. Last, a new application for these vacuum arc thrusters was studied for use in an underwater environment. The purpose of this work was to further develop a vacuum arc thruster, known as the Micro-Cathode Arc Thruster (muCAT), which has been developed at the George Washington University's Micro Propulsion and Nanotechnology Lab. The muCAT has been developed over the past decade, and in the last 5 years has gone from simple lab circuitry to space flown hardware. Therefore it is imperative to fully understand every aspect of this technology to achieve precisely what missions require. The results of this dissertation have allowed a new

  4. Preparation of nanocomposite fluid by electrical arc discharge technique.

    Science.gov (United States)

    Chang, Ho

    2008-02-01

    This study proposes a new method, the electrical arc discharge system, for preparing a nanocomposite fluid with the basic ingredients of Cu, Fe and O. The proposed system has the advantages of a high-power electric arc heating system, excellent stability of the electric arc, and well-developed control technology. In the fabrication process, the positive electrode uses a copper rod and the negative electrode an iron rod, and the two electrodes are processed in the insulating processing liquid. The nanocomposite fluid generated by the synthesis system is analyzed by morphological analysis, heat transfer analysis, magnetism analysis, and rheological testing. The experiment generates satisfactory results for nanocomposite fluid with an average particle diameter of 25 nm by process conditions of vacuum pressure of 30 torr, peak current of 7 A for arc discharge, breakdown voltage of 250 V and duration time of 10 micros. The experimental results showed that the nanocomposite fluid is composed of Fe, FeO, Cu, and Cu2O. SEM images show that Fe and Cu are spherical, FeO is square, and Cu2O is ovoid. For the heat transfer experiment, the experimental temperature was set at ambient temperature of 30 degrees C, the average heat transfer coefficient is 0.708 W/m oC, which is 16.3% higher than that of deionized water. The magnetism test shows that the magnetic retentivity of the fluid is 47.27 (Oe), which makes it a soft magnetic fluid.

  5. Influence of N{sub 2} partial pressure on structural and microhardness properties of TiN/ZrN multilayers deposited by Ar/N{sub 2} vacuum arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, M., E-mail: ascientific24@aec.org.sy [Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus (Syrian Arab Republic); Abdallah, B. [Department of Physics, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Ahmad, M. [IBA Laboratory, Department of Chemistry, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); A-Kharroub, M. [Department of Physics, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic)

    2016-08-15

    The influence of N{sub 2} partial pressure on structural, mechanical and wetting properties of multilayered TiN/ZrN thin films deposited on silicon substrates by vacuum arc discharge of (N{sub 2} + Ar) gas mixtures is investigated. X-ray diffraction (XRD) results show that the average texturing coefficient of (1 1 1) orientation and the grain size of both TiN and ZrN individual layers increase with increasing the N{sub 2} partial pressure. The Rutherford back scattering (RBS) measurements and analysis reveal that incorporation of the nitrogen in the film increases with increasing the N{sub 2} partial pressure and both TiN and ZrN individual layers have a nitrogen over-stoichiometry for N{sub 2} partial pressure ⩾50%. The change in the film micro-hardness is correlated to the changes in crystallographic texture, grain size, stoichiometry and the residual stress in the film as a function of the N{sub 2} partial pressure. In particular, stoichiometry of ZrN and TiN individual is found to play the vital role in determining the multilayer hardness. The multilayer film deposited at N{sub 2} partial pressure of 25% has the best stoichiometric ratio of both TiN and ZrN layers and the highest micro-hardness of about 32 GPa. In addition, water contact angle (WCA) measurements and analysis show a decrease in the work of adhesion on increasing the N{sub 2} partial pressure.

  6. Plasma jet characteristics in vacuum arc with diffused cathode spot

    Science.gov (United States)

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

    2017-05-01

    Diffused vacuum arc, which is characterized by the absence of microparticles in cathode erosion products and by the irregular voltage oscillations, is considered to be a perspective plasma source for plasma reprocessing technology of spent nuclear fuel (SNF). The development of this technology requires data on ions energy in plasma jet. In this work parameters of plasma jet in diffused vacuum arc with a gadolinium cathode were studied by a retarding field analyzer, Langmuir and condensation probes. Gadolinium is regarded as a substance simulating SNF plasma. Ion energy spectrum was studied at arc currents of 30-75 A and voltages of 4-15 V at the distance of 20 cm above the arc anode. Dependencies of spectrum widths and most possible ion energies on arc voltages were obtained. The measured electron temperature was 2 eV, the maximum ion energy reached 70 eV. Experimental data were used to calculate adiabatic plasma expansion through the anode outlet.

  7. An interchangeable-cathode vacuum arc plasma source.

    Science.gov (United States)

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

    2010-01-01

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

  8. 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.

  9. Influence of plasma properties on ARC discharge destabilization

    Science.gov (United States)

    Podenok, L. P.; Sharakhovskii, L. I.; Shimanovich, V. D.; Yas'ko, O. I.

    1997-01-01

    The influence of heat transfer processes in arc discharges on the development of thermal instability is considered. A substantial dependence of the process of destabilization on the plasma properties is shown by the example of argon and helium arcs.

  10. Vacuum Switches Arc Images Pre–processing Based on MATLAB

    Directory of Open Access Journals (Sweden)

    Huajun Dong

    2015-01-01

    Full Text Available In order to filter out the noise effects of Vacuum Switches Arc(VSAimages, enhance the characteristic details of the VSA images, and improve the visual effects of VSA images, in this paper, the VSA images were implemented pre-processing such as noise removal, edge detection, processing of image’s pseudo color and false color, and morphological processing by MATLAB software. Furthermore, the morphological characteristics of the VSA images were extracted, including isopleths of the gray value, arc area and perimeter.

  11. Particle tracking velocimetry of a gliding arc discharge

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2014-01-01

    A 35 kHz AC gliding arc discharge at atmospheric pressure is generated between two diverging electrodes and extended by an air flow. The gas flow velocity is measured by particle tracking velocimetry (PTV) while the moving velocity of the plasma column of the gliding arc discharge is measured...... by analyzing the movie taken by a high-speed camera. The two-dimensional velocity vector of the gas flow and of the gliding arc in the imaging plane was determined....

  12. Fullerenes synthesis by combined resistive heating and arc discharge techniques

    OpenAIRE

    Kyesmen, Pannan Isa; Onoja, Audu; Amah, Alexander Nwabueze

    2016-01-01

    The two main electrode techniques for fullerenes production; the direct arc technique and the resistive heating of graphite rod were employed in this work. One of the electrodes was resistively heated to high temperature and subjected to arc discharge along its length by the second graphite rod. Fullerenes solid were extracted from carbon soot samples collected from an installed arc discharge system using the solvent extraction method. The fullerenes solid obtained from carbon soot collected ...

  13. Vacuum arc localization in CLIC prototype radio frequency accelerating structures

    CERN Document Server

    AUTHOR|(CDS)2091976; Koivunen, Visa

    2016-04-04

    A future linear collider capable of reaching TeV collision energies should support accelerating gradients beyond 100 MV/m. At such high fields, the occurrence of vacuum arcs have to be mitigated through conditioning, during which an accelerating structure’s resilience against breakdowns is slowly increased through repeated radio frequency pulsing. Conditioning is very time and resource consuming, which is why developing more efficient procedures is desirable. At CERN, conditioning related research is conducted at the CLIC high-power X-band test stands. Breakdown localization is an important diagnostic tool of accelerating structure tests. Abnormal position distributions highlight issues in structure design, manufacturing or operation and may consequently help improve these processes. Additionally, positioning can provide insight into the physics of vacuum arcs. In this work, two established positioning methods based on the time-difference-ofarrival of radio frequency waves are extended. The first method i...

  14. Beam Vacuum Interconnects for the LHC Cold Arcs

    CERN Document Server

    Veness, R J M; Gröbner, Oswald; Lepeule, P; Reymermier, C; Schneider, G; Skoczen, Blazej; Kleimenok, V; Nikitin, I N

    1999-01-01

    The design of the beam vacuum interconnect is described in this paper. Features include a novel RF bridge design to maximise lateral flexibility during cryostat Cold arcs of the LHC will consist of twin aperture dipole, quadrupole and corrector magnets in cryostats, operating at 1.9 K. Beam vacuum chambers, along with all connecting elements require flexible 'interconnects' between adjacent cryostats to allow for thermal and mechanical offsets foreseen during machine operation and alignment. In addition, the beam vacuum chambers contain perforated beam screens to intercept beam induced heat loads at an intermediate temperature. These must also be connected with low impedance RF bridges in the interconnect zones.alignment and so-called 'nested' bellows to minimise the required length of the assembly.

  15. Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization.

    Science.gov (United States)

    Zhang, H-S; Komvopoulos, K

    2008-07-01

    Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp3) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.

  16. Metal plating removal from insulator substrate using pulsed arc discharge

    Science.gov (United States)

    Imasaka, K.; Gnapowski, S.; Akiyama, H.

    2014-06-01

    Removal technique of metal materials from a metal plating insulator substrate using a pulsed arc discharge was proposed and its fundamental characteristics were investigated. The metal plating substrate with three metal-layers structure (cupper, nickel and gold layers) is used as the sample substrate. Repetitive pulsed arc discharge plasma is generated using three types of electrode systems. Effects of the electrode systems on the metal plating removal from the insulator substrate were investigated. The metal plating was removed by the pulsed arc discharge between the electrode and substrate surface. A part of the gold layer, which is the topmost metal layer on the insulator substrate is vaporized and removed by the repetitive pulsed arc discharges.

  17. [Preliminary study of atomic emission spectrometry of Ti (H) plasma produced by vacuum arc ion source].

    Science.gov (United States)

    Deng, Chun-Feng; Wu, Chun-Lei; Wang, Yi-Fu; Lu, Biao; Wen, Zhong-Wei

    2014-03-01

    In order to study the discharge process of vacuum arc ion source, make a detail description of the discharge plasma, and lay the foundation for further research on ion source, atomic emission spectrometry was used to diagnose the parameters of plasma produced by vaccum arc ion source. In the present paper, two kinds of analysis method for the emission spectra data collected by a spectrometer were developed. Those were based in the stark broadening of spectral lines and Saba-Boltzmann equation. Using those two methods, the electron temperature, electron number density and the ion temperature of the plasma can be determined. The emission spectroscopy data used in this paper was collected from the plasma produced by a vacuum are ion source whose cathode was made by Ti material (which adsorbed hydrogen during storage procedure). Both of the two methods were used to diagnose the plasma parameters and judge the thermal motion state of the plasma. Otherwise, the validity of the diagnostic results by the two methods were analyzed and compared. In addition, the affection from laboratory background radiation during the spectral acquisition process was discussed.

  18. Vacuum ultraviolet radiometry of xenon positive column discharges

    Science.gov (United States)

    Doughty, D. A.; Fobare, D. F.

    1995-10-01

    In order to judge the potential fluorescent lamp applications of various low-pressure positive column discharges it is necessary to measure the absolute power emitted in the ultraviolet region of the spectrum. For rare-gas discharges the principle emission occurs in the vacuum ultraviolet so that it is difficult to measure the radiant emittance (power per unit area) of the resonance radiation by standard methods. Two independent techniques are discussed for measuring the radiant emittance of positive column discharges in the vacuum ultraviolet. These techniques are used to study xenon positive column discharges at the resonance wavelength of 147 nm. The first method relies on the measurement of the resonance level density by absorption techniques. The effective decay rate of the resonance level is then determined by the simulation of resonance radiation transport. These two quantities are combined to yield the radiant emittance at 147 nm without implementing vacuum ultraviolet techniques. The second method uses a measurement of the resonance radiation normal to the positive column axis made with a calibrated vacuum ultraviolet detector. The angular distribution of the resonance radiation leaving the tube is determined by the simulation of resonance radiation transport. The detector measurement places the angular distribution of the radiance on an absolute scale, which can then be integrated to yield the radiant emittance. These two techniques are compared for pure xenon discharges at various pressures and currents.

  19. REVIEW ARTICLE Fibre optic devices produced by arc discharges

    Science.gov (United States)

    Rego, G.

    2010-11-01

    We present an overview of the applications of the electric arc technique related to optical fibre technology. The use of arc discharges ranges from the well-known fibre splicing, going through the fabrication of basic devices such as fibre tapers and microspheres, to tailoring the spectra of UV-induced gratings such as in the apodization of fibre Bragg gratings and also in the fabrication of phase-shifted and sampled fibre Bragg gratings. However, in the past decade a topic more intensively investigated was probably long-period fibre gratings. Therefore, some devices based on arc-induced gratings, namely, phase-shifted and step-changed gratings and bandpass filters are discussed. We also present an electrically insulated thermocouple assembled in situ using arc discharges. This sensor is very useful in the determination of the temperature attained by the fibre during an arc discharge, this property being fundamental for the discussion of the mechanisms of formation and for the understanding of the thermal properties of arc-induced devices.

  20. Fullerenes synthesis by combined resistive heating and arc discharge techniques.

    Science.gov (United States)

    Kyesmen, Pannan Isa; Onoja, Audu; Amah, Alexander Nwabueze

    2016-01-01

    The two main electrode techniques for fullerenes production; the direct arc technique and the resistive heating of graphite rod were employed in this work. One of the electrodes was resistively heated to high temperature and subjected to arc discharge along its length by the second graphite rod. Fullerenes solid were extracted from carbon soot samples collected from an installed arc discharge system using the solvent extraction method. The fullerenes solid obtained from carbon soot collected for 2 min of arc discharge run when one of the electrodes was resistively heated at different voltages all gave higher yields (maximum of 67 % higher, at 150 A arc current and 200 Torr chamber pressure) compared to when no resistive heating was carried out. Scanning electron microscopy and ultraviolet visible spectroscopy analysis carried out on all fullerenes solid indicated the presence of fullerenes. The enhancement of fullerenes production by combined resistive and direct arc techniques shows prospect for possible use at industrial level for large scale production.

  1. Synthesis of carbon nanotubes by arc discharge in open air.

    Science.gov (United States)

    Paladugu, Mohan Chand; Maneesh, K; Nair, P Kesavan; Haridoss, Prathap

    2005-05-01

    In this work Carbon nanotubes have been synthesized by arc discharge in open air. A TIG welding ac/dc inverter was used as the power source for arc discharge. During each run of the arc discharge based synthesis, the anode was a low purity (approximately 85% C by weight) graphite rod. The effect of varying the atmosphere on the yield of soot of the carbon nanotube containing carbon soot has been studied. Various soots were produced, purified by oxidation and characterized to confirm formation of carbon nanotubes and their relative quality, using transmission electron microscopy, Raman spectroscopy, and XRD. It was found that the yield of soot formed on the cathode is higher when synthesis is carried out in open air than when carried out in a flowing argon atmosphere. When synthesized in open air, using a 7.2-mm-diameter graphite rod as anode, the yield of soot was around 50% by weight of the graphite consumed. Current and voltage for arcing were at identical starting values in all the experiments. This modified method does not require a controlled atmosphere as in the case of a conventional arc discharge method of synthesis and hence the cost of production may be reduced.

  2. Behavior of sustained high-current arcs on molten-alloy electrodes during vacuum consumable-arc remelting

    Science.gov (United States)

    Zanner, F. J.; Bertram, L. A.

    Vacuum consumable arc remelting is a casting process carried out in a vacuum with the aim of remelting the consumable electrode in such a way that the new ingot has improved chemical and physical homogeneity. The power which causes the melting is supplied by a vacuum arc burning between the electrodes. In order to determine the furnace partitions of electrical power and current, experiments were conducted on molten faced round electrodes. The quasi-steady melt rate was determined for both horizontally opposed 15 cm dia. Ni electrodes and for vertically suspended 40 cm dia. Inconel 718 electrodes.

  3. Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Zarchin, O [Electrical Discharge and Plasma Laboratory, Tel-Aviv University, POB 39040, Tel-Aviv 69978 (Israel); Zhitomirsky, V N [Electrical Discharge and Plasma Laboratory, Tel-Aviv University, POB 39040, Tel-Aviv 69978 (Israel); Goldsmith, S [Electrical Discharge and Plasma Laboratory, Tel-Aviv University, POB 39040, Tel-Aviv 69978 (Israel); Boxman, R L [Electrical Discharge and Plasma Laboratory, Tel-Aviv University, POB 39040, Tel-Aviv 69978 (Israel)

    2003-09-21

    The effect of an obstacle positioned normal to a plasma jet produced by a vacuum arc plasma source on the radial distribution of ion flux in the vicinity of the obstacle was studied. This study was motivated by interest in the mutual influence of tightly packed substrates on coatings in industrial vacuum arc deposition systems. The experimental system consisted of a vacuum arc plasma source, a straight plasma duct, and a multi-probe consisting of a removable disc obstacle and a set of ring probes for measuring the radial ion flux. A dc arc discharge was ignited in vacuum between a truncated cone-shaped Cu cathode and an annular anode. The plasma jet produced by cathode spots passed through the anode aperture into the straight plasma duct. An axial magnetic field guided the plasma jet in the duct. The multi-probe consisted of a removable disc obstacle and a set of five ring probes for measuring the radial plasma flux as a function of distance from the disc obstacle. The rings and the disc probes were coaxially arranged on the multi-probe assembly and positioned so that plasma from the source passed through the ring probes and then encountered the disc. The influence of the obstacle was determined by measuring the ring ion currents, both in the presence of the obstacle, and when the disc obstacle was removed. The difference between the measured ion currents with and without the obstacle was interpreted to be the contribution of reflected or sputtered particles from the obstacle to the radial ion flux. The ring probes were biased by -60 V with respect to the grounded anode, to collect the saturated ion current. The multi-probe was connected to a movable stem, and positioned at different distances from the plasma source. A plasma density of {approx}6 x 10{sup 17} m{sup -3} was estimated in this study based on the ion current to the obstacle. The radial ion flux collected by the ring probes increased by 20-25% due to the presence of the obstacle. As the calculated mean

  4. Characterization of Plasma Polymerized Hexamethyldisiloxane Films Prepared by Arc Discharge

    NARCIS (Netherlands)

    Lazauskas, A.; Baltrusaitis, Jonas; Grigaliunas, V.; Jucius, D; Guobiene, A.; Prosycevas, I.; Narmontas, P.

    2014-01-01

    Herein, we present a simple method for fabricating plasma polymerized hexamethyldisiloxane films (pp-HMDSO) possessing superhydrophobic characteristics via arc discharge. The pp-HMDSO films were deposited on a soda–lime–silica float glass using HMDSO monomer vapor as a precursor. A detailed surface

  5. The layered structure of the carbon arc discharge plasma

    Science.gov (United States)

    Vekselman, Vladislav; Stratton, Brentley; Raitses, Yevgeny; LaboratoryPlasma Nanosynthesis Team

    2016-10-01

    The arc discharge with a consumed anode is commonly used for synthesis of nanomaterials such as fullerenes, nanotubes and, more recently, graphene. The role of the arc plasma in nanosynthesis processes, including ablation of the graphite anode, nucleation and growth of nanostructures remains unclear. Our recent fast frame camera measurements revealed arc oscillations associated with the ablation processes at the anode. More sophisticated measurements using optical emission spectroscopy and spectrally resolved fast framing imaging revealed the complex, layered structure of plasma species distribution, which is dynamically changing. The results of this research include time- and space- resolved distributions of plasma species, plasma electron density and temperature. The obtained experimental data suggest a strong correlation between arc plasma parameters and nanosynthesis processes. This work was supported by US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  6. Generation of high charge state metal ion beams by electron cyclotron resonance heating of vacuum arc plasma in cusp trap.

    Science.gov (United States)

    Nikolaev, A G; Savkin, K P; Oks, E M; Vizir, A V; Yushkov, G Yu; Vodopyanov, A V; Izotov, I V; Mansfeld, D A

    2012-02-01

    A method for generating high charge state heavy metal ion beams based on high power microwave heating of vacuum arc plasma confined in a magnetic trap under electron cyclotron resonance conditions has been developed. A feature of the work described here is the use of a cusp magnetic field with inherent "minimum-B" structure as the confinement geometry, as opposed to a simple mirror device as we have reported on previously. The cusp configuration has been successfully used for microwave heating of gas discharge plasma and extraction from the plasma of highly charged, high current, gaseous ion beams. Now we use the trap for heavy metal ion beam generation. Two different approaches were used for injecting the vacuum arc metal plasma into the trap--axial injection from a miniature arc source located on-axis near the microwave window, and radial injection from sources mounted radially at the midplane of the trap. Here, we describe preliminary results of heating vacuum arc plasma in a cusp magnetic trap by pulsed (400 μs) high power (up to 100 kW) microwave radiation at 37.5 GHz for the generation of highly charged heavy metal ion beams.

  7. Large area, surface discharge pumped, vacuum ultraviolet light source

    Science.gov (United States)

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  8. Avoiding vacuum arcs in high gradient normal conducting RF structures

    CERN Document Server

    Sjøbæk, Kyrre Ness; Adli, Erik; Grudiev, Alexej; Wuensch, Walter

    In order to build the Compact LInear Collider (CLIC), accelerating structures reaching extremely high accelerating gradients are needed. Such structures have been built and tested using normal-conducting copper, powered by X-band RF power and reaching gradients of 100 MV/m and above. One phenomenon that must be avoided in order to reliably reach such gradients, is vacuum arcs or “breakdowns”. This can be accomplished by carefully designing the structure geometry such that high surface fields and large local power flows are avoided. The research presented in this thesis presents a method for optimizing the geometry of accelerating structures so that these breakdowns are made less likely, allowing the structure to operate reliably at high gradients. This was done primarily based on a phenomenological scaling model, which predicted the maximum gradient as a function of the break down rate, pulse length, and field distribution in the structure. The model is written in such a way that it allows direct comparis...

  9. Amorphous boron coatings produced with vacuum arc deposition technology

    CERN Document Server

    Klepper, C C; Yadlowsky, E J; Carlson, E P; Keitz, M D; Williams, J M; Zuhr, R A; Poker, D B

    2002-01-01

    In principle, boron (B) as a material has many excellent surface properties, including corrosion resistance, very high hardness, refractory properties, and a strong tendency to bond with most substrates. The potential technological benefits of the material have not been realized, because it is difficult to deposit it as coatings. B is difficult to evaporate, does not sputter well, and cannot be thermally sprayed. In this article, first successful deposition results from a robust system, based on the vacuum (cathodic) arc technology, are reported. Adherent coatings have been produced on 1100 Al, CP-Ti, Ti-6Al-4V, 316 SS, hard chrome plate, and 52 100 steel. Composition and thickness analyses have been performed by Rutherford backscattering spectroscopy. Hardness (H) and modules (E) have been evaluated by nanoindentation. The coatings are very pure and have properties characteristic of B suboxides. A microhardness of up to 27 GPa has been measured on a 400-nm-thick film deposited on 52 100 steel, with a corresp...

  10. Boron Nitride nanotube synthesis using liquid arc discharge

    Science.gov (United States)

    Holliday, Roger; Falvo, Mike; Washburn, Sean; Superfine, Richard

    2002-03-01

    We will present results on synthesis of Boron Nitride nanotubes using the liquid nitrogen plasma-arc discharge method previously reported for carbon nanotubes synthesis[1]. We created a 60-100A/20-40V arc across electrodes of Hafnium Boride and Molybdenum Sulfide in a liquid nitrogen atmosphere. Nanotube geometry, nano-structure and composition characterization using TEM and EDAX will be presented. Progress in electronic and mechanical characterization as well as our incorporation of these nanotubes in to novel NEMS devices will be discussed. [1] M. Ishigami, J. C., A. Zettl, S. Chen . Chemical Physical Letters 319 (2000),pp.457-459.

  11. Vacuum arcing behavior between transverse magnetic field contacts subjected to variable axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Hui; Wang, Jianhua; Liu, Zhiyuan, E-mail: liuzy@mail.xjtu.edu.cn; Geng, Yingsan; Wang, Zhenxing; Yan, Jing [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-06-15

    The objective of this work is to reveal the effects of an axial magnetic field (AMF) on the vacuum arc characteristics between transverse magnetic field (TMF) contacts. These vacuum arc characteristics include the vacuum arcing behavior and the arc voltage waveform. In the experiments, an external AMF was applied to a pair of TMF contacts. The external AMF flux density B{sub AMF} can be adjusted from 0 to 110 mT. The arc current in the tests varied over a range from 0 to 20 kA rms at 45 Hz. The contact material was CuCr25 (25% Cr). A high-speed charge-coupled device video camera was used to record the vacuum arc evolution. The experimental results show that the application of the AMF effectively reduces the TMF arc voltage noise component and reduces the formation of liquid metal drops between the contacts. The diffuse arc duration increases linearly with increasing AMF flux density, but it also decreases linearly with increasing arc current under application of the external AMF. The results also indicate that the diffuse arc duration before the current zero is usually more than 1 ms under the condition that the value of the AMF per kiloampere is more than 2.0 mT/kA. Finally, under application of the AMF, the arc column of the TMF contacts may constrict and remain in the center region without transverse rotation. Therefore, the combined TMF–AMF contacts should be designed such that they guarantee that the AMF is not so strong as to oppose transverse rotation of the arc column.

  12. 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.

  13. Ablation and deposition processes in carbon arc discharge for nanosynthesis

    Science.gov (United States)

    Raitses, Yevgeny; Ng, Jonathan; Nemchinsky, Valerian; Yeh, Yao-Wen; Gershman, Sophia; Vekselman, Vlad

    2015-09-01

    The anodic arc discharges with consumed anodes are used to produce various nanoparticles, including carbon nanotubes. Our experiments with the carbon arc at atmospheric pressure helium demonstrate the dependence of the anode ablation rate on the anode diameter, which cannot be explained by changes of the current density at the anode. In particular, the anode ablation rate for narrow graphite anodes is significantly enhanced resulting in high deposition rates of carbonaceous products on the copper cathode. The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes. Results of experimental validation of this model are presented. This work was supported by U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  14. Optical absorption spectroscopy of metallic (Cr) vapor in a vacuum arc

    Science.gov (United States)

    Wang, Haoran; Wang, Zhenxing; Liu, Jiankun; Zhou, Zhewei; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2018-01-01

    The measurement of the metallic vapor density in a vacuum arc is crucial to acquire a better understanding of both the anodic activity and the dielectric recovery process in vacuum interrupters. The objective of this study was to measure the chromium vapor density and its axial distribution within the gap between the chromium contacts. Optical absorption spectroscopy (OAS) with a broadband light-source is adopted for this investigation. The results show that when the vacuum arc burns in the diffuse mode, the metallic vapor density maxima occur near the electrodes during the arcing period. At the peak current, the vapor density near the electrodes can be as high as 2.5  ×  1018 m‑3. With the decrease of the arc current, the metallic vapor density near the electrodes decreases as well, while the vapor density in the center of the gap remains nearly constant during the arcing period. At current zero, the metallic vapor in the gap has a nearly uniform distribution of about 3  ×  1017 m‑3. When the vacuum arc burns in the high-current mode, the metallic vapor density near the anode is lower than that in other areas until the vacuum arc becomes diffuse. Then, the evaporation process of the anodic molten region starts to play an important role and the metallic vapor density near the anode increases. At current zero, the metallic vapor has a density of about 4  ×  1018 m‑3 near the anode, which is much higher than anywhere else. Because the metallic vapor density at current zero is too low to cause a Townsend avalanche, extra factors are needed for initiating the breakdown in the post-arc phase. These factors could include a residual plasma within the gap and the behavior of the liquid metal in the molten anodic region.

  15. Effect of laser pulse on alternative current arc discharge during laser-arc hybrid welding of magnesium alloy

    Science.gov (United States)

    Chen, Minghua; Xin, Lijun; Zhou, Qi; He, Lijia; Wu, Fufa

    2018-01-01

    The coupling effect between a laser and arc plasma was studied in situations in which the laser acts at the positive and negative waveforms of the arc discharge during the laser-arc hybrid welding of magnesium alloy. Using the methods of direct observation, high speed imaging, and spectral analysis, the surface status of weld seams, weld penetration depths, plasma behavior, and spectral characteristics of welding plasma were investigated, respectively. Results show that, as compared with the laser pulse acting at the negative waveform of the arc plasma discharge, a better weld seam formation can be achieved when the laser pulse acts at the positive waveform of the arc discharge. At the same time, the radiation intensity of Mg atoms in the arc plasma increases significantly. However, the weld penetration depth is weaker. The findings show that when the laser pulse is acting at the negative waveform of the arc plasma discharge, the position of the arc plasma discharge on the workpiece can be restrained by the laser action point, which improves the energy density of the welding arc.

  16. Electron Temperature of the Arc Discharge for Nanomaterial Synthesis

    Science.gov (United States)

    Feurer, Matthew; Vekselman, Vladislav; Startton, Brentley; Raitses, Yevgeny; LaboratoryPlasma Nanosynthesis Team

    2016-10-01

    Since the discovery of different allotropes of carbon in the twentieth century many uses have been found for carbon based nanomaterials such as buckyballs, nanotubes (CNTs), and graphene. An atmospheric pressure arc discharge with graphite electrodes is a promising technique for producing large volumes of these carbon nanostructures. Plasma drives the synthesis providing carbon feedstock by anode ablation and sustaining required composition and temperature of nanomaterial species, as such it is important to characterize the plasma used in this process in order to control the quality and attributes of the resulting carbon nanostructures. In work we present detailed in-situ measurements of spatial distribution of arc plasma parameters obtained with optical emission spectroscopy (OES) diagnostics. The plasma temperature has been determined using Boltzmann diagram method with collisional radiative modeling due to plasma deviation from complete local thermodynamic equilibrium (LTE). Results of these measurements demonstrate a strong correlation between arc plasma and synthesis processes. This work was supported by US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  17. Analysis of the Vacuum Arc Interruption Process in Aviation Intermediate-Frequency Power Supply Systems

    Directory of Open Access Journals (Sweden)

    Yuan Jiang

    2017-03-01

    Full Text Available In this paper, we present our research into the interruption performance of vacuum circuit breakers in aviation intermediate-frequency (360 Hz to 800 Hz power supply systems. Intermediate-frequency vacuum arc experiments were carried out in interrupters with a diameter of 41 mm and CuCr50 alloy contact material. The results show that, as the frequency and peak value of the current increase, both the peak value and rise rate of the intermediate-frequency vacuum arc voltage also increase, and the interruption ability decreases. However, compared to the power frequency current at the same value, the erosion of the contacts is weaker over a shorter arc period. When the vacuum arc reignites, metal droplets are emitted from the contacts. The drive force is from the center of the contact to the edge. If the density of the plasmas and metal vapors and the number of the metal droplets reaches a certain level, the arc may break down, which will cause the interruption to fail.

  18. Miniature pulsed vacuum arc plasma gun and apparatus for thin-film fabrication

    Science.gov (United States)

    Brown, Ian G.; MacGill, Robert A.; Galvin, James E.; Ogletree, David F.; Salmeron, Miquel

    1998-01-01

    A miniature (dime-size in cross-section) vapor vacuum arc plasma gun is described for use in an apparatus to produce thin films. Any conductive material can be layered as a film on virtually any substrate. Because the entire apparatus can easily be contained in a small vacuum chamber, multiple dissimilar layers can be applied without risk of additional contamination. The invention has special applications in semiconductor manufacturing.

  19. 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.

  20. Monochromatic imaging studies of a low pressure arc burning on molten Inconel 718 alloy electrodes during vacuum arc remelting

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, R.L.; Zanner, F.J.; Hareland, W.A.

    1988-01-01

    Vacuum arc remelting (VAR) is a melting and solidification process used to produce high quality ingots of chemically reactive or segregation sensitive alloys. Melting is accomplished through the use of a sustained high current (several kiloamperes) dc arc. Energy from the arc is used to melt a consumable electrode (cathode) which is cast from the alloy to be remelted. The molten material drips down into a water-cooled copper crucible (anode) where it solidifies as a larger diameter, homogeneous, porosity-free, cylindrical ingot. Solidification is driven mainly by radial heat extraction from the molten pool atop the ingot and is influenced by magnetically and buoyancy driven fluid flows that are coupled to the arc behavior. The paper reports the initial results of efforts to characterize the VAR furnace arc during remelting of Inconel 718 alloy using monochromatic imaging. This technique allows one to examine how individual atomic species are distributed throughout the arc plasma in the electrode gap. Because only species existing in excited electronic states are able to emit light, the images also give insight into the energy distribution in the gap. Chromium and manganese distributions were investigated. Chromium was chosen to represent one of the major alloy constituents, while manganese represents a highly volatile trace component. 13 refs., 7 figs.

  1. Novel Electrical Modeling of Arc Discharges of Fluorescent Lamps

    Science.gov (United States)

    Tamida, Taichiro; Funayama, Shinsuke; Iwata, Akihiko

    A simple and novel circuit model of the electrical characteristics of arc discharge of fluorescent lamps has been developed. The model has the features necessary for electrical circuit design, and enables circuit simulation with consideration of the effect of the electrical behavior of the discharge lamp, including the effects of some abnormal conditions. Although the model equation is a simple polynomial expression, each term is based on physical considerations, and non-linear and non-steady discharge phenomena have been successfully modeled. The model can express most aspects of lamp operation, and results quantitatively correct values over a wide operation frequency range. It also reproduces abnormal conditions such as worn-out lamps and rarely reproduced phenomena. The model is constructed as a combination of primitive circuit elements. Consequently, combined with a designed ballast circuit, one can easily perform circuit analysis by using a general-purpose circuit simulator. The model will be a very powerful tool for lamp ballast and peripheral circuit design.

  2. Modeling of cathode spot crater formation and development in vacuum arc

    Science.gov (United States)

    Zhang, Xiao; Wang, Lijun; Jia, Shenli; Shmelev, D. L.

    2017-11-01

    A two-dimensional (2D) rotary axisymmetric model has been developed to describe the formation and development of cathode spot in vacuum arc. The model includes hydrodynamic equations and heat transfer equation which considers surface evaporation and Joule heating. Parameters used in this model, such as the distributions of pressure, energy flux density, and current density, come from experiments and other researchers’ work. In this model, cathode spot maintains 30 ns and during this time, all parameters are fixed. The simulation results show that when the energy flux density is 1.5–3  ×  1012 W, discharge current is 1–6 A and the pressure is 1–3  ×  108 Pa, the crater radius is 1.4–4.1 µm, the crater depth is 1.4–2.1 µm, the velocity of liquid metal is 154–428 m s‑1 and the maximum temperature is 2145–5342 K which is located in the area with radius 0.5–1.5 µm. Besides, on the chromium cathode, the maximum temperature is higher mainly because of the lower thermal conductivity.

  3. Low pressure arc discharge lamp apparatus with magnetic field generating means

    Science.gov (United States)

    Grossman, Mark W.; George, William A.; Maya, Jakob

    1987-01-01

    A low-pressure arc discharge apparatus having a magnetic field generating means for increasing the output of a discharge lamp is disclosed. The magnetic field generating means, which in one embodiment includes a plurality of permanent magnets, is disposed along the lamp for applying a constant transverse magnetic field over at least a portion of the positive discharge column produced in the arc discharge lamp operating at an ambient temperature greater than about 25.degree. C.

  4. 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.

  5. Generation of high charge state platinum ions on vacuum arc plasma heated by gyrotron radiation.

    Science.gov (United States)

    Yushkov, G Yu; Vodopyanov, A V; Nikolaev, A G; Izotov, I V; Savkin, K P; Golubev, S V; Oks, E M

    2014-02-01

    The hybrid high charge metal ion source based on vacuum arc plasma heated by gyrotron radiation into simple magnetic trap has been developed. Two types of magnetic traps were used: a mirror configuration and a cusp one with inherent "minimum-B" structure. Pulsed high power (>100 kW) gyrotrons with frequency 37.5 GHz and 75 GHz were used for heating the vacuum arc plasma injected into the traps. Two different ways were used for injecting the metal plasma-axial injection by a miniature arc source located on-axis near the microwave window, and simultaneous radial injection by a number of sources mounted radially at the midplane of the traps. This article represents all data gathered for platinum ions, thus making comparison of the experimental results obtained with different traps and injections convenient and accurate.

  6. Experimental observation of high-voltage, low-current vacuum arcs

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, R.Y.; Puzanov, S.V.; Yashnov, Y.M. [Scientific-Research Inst. Titan, Moscow (Russian Federation)

    1995-12-01

    A poorly explored type of discharge has been investigated in high vacuum (10{sup {minus}7} to 10{sup {minus}6} torr), with a DC high voltage across 0.2- to 0.8-mm gaps. The discharge has been found to be quite different from other widely known types of vacuum and gas discharges by the combination of its voltage-current characteristics (hyperbola-type), source and carriers of current (mostly electrons), and spatial potential distribution (a considerable electric field across the gap and a steep potential fall near the cathode).

  7. Numerical simulation of synthesis of fullerenes by the arc discharge method

    NARCIS (Netherlands)

    Afanasyeva, A.; Ponyaev, S.; Krgiganovskaya, V.

    2013-01-01

    A mathematical model of the fullerene formation process by carbon vapor clustering in an arc discharge camera was developed. Numerical simulation of formation of fullerene clusters up to C60 and C70 from carbon vapor produced by an arc discharge in a plasma reactor camera was carried out. A

  8. Approach to modeling of the fast energy discharge in cryogenic systems in the form of an electric arc

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Superconducting magnets are supplied with a few kA of electric current and can store a large amount of energy. Therefore, cryogenic systems which are comprised of such magnets are subject to the risk of fast energy discharge from the magnets themselves in the form of an electric arc. The arcing can be a result of failure in the insulation of an electric circuit or in the connection between the magnet and its current lead. During the discharge, energy can be partially dissipated into the cryogen and partially into the cryogenic system metallic structure. The part of the energy that is transferred to the metallic structure will strongly heat up the metal surface, which can lead to material burning. In this case, the cryogen will flow through the perforation to the insulation vacuum space, which can trigger a rapid increase in pressure in the vacuum enclosure. However, the discharged energy that has been stored in the cryogen also causes a rapid increase in cryogenic pressure. Hence, the proper estimation of the...

  9. Effect of vacuum arc cathode spot distribution on breaking capacity of the arc-extinguishing chamber

    Science.gov (United States)

    Ding, Can; Yuan, Zhao; He, Junjia

    2017-10-01

    A DC circuit breaker performs a key function in breaking an intermediate-frequency (IF) current since breaking a pure IF current is equivalent to breaking a very small DC with a reverse IF current. In this study, it is found that cathode spots show a ring-shaped distribution at 2000 Hz. An arc with an uneven distribution of cathode spots has been simulated. The simulation results show that the distribution of cathode spots significantly affect the microparameter distribution of arc plasma. The current distribution on the anode side differs from that on the cathode side under the total radial electric field. Specifically, the anode current distribution is both uneven and concentrated. The applied axial magnetic field, which cannot reduce the concentrated anode current distribution effectively, might increase the concentration of the anode current. Finally, the uneven distribution of cathode spots reduces the breaking capacity of the arc-extinguishing chamber.

  10. Theory of the arc discharge in air blast breakers

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, H.F.

    1980-08-01

    The complete set of equations obtaining in the arc's length element are given. The arc length is determined when the external circuit equations are closed by an expression for the arc inductance as a function of the radius and length, in addition to our relationships for the radius and voltage gradients.

  11. Research of influence of mobile cathodic stains of the vacuum arc for reception of the adjustable roughness of metal surfaces

    Science.gov (United States)

    Anikeev, V. N.; Dokukin, M. Yu

    2017-05-01

    In the modern technics there is a requirement in micro- and macrorough surfaces of products for improvement of their operational characteristics (improvement of adhesive properties of various coverings, decrease in deterioration of rubbing details because of the best deduction of greasing, increase of the heat exchanging coefficient from a surface, stimulation of adhesive processes on sites of contact to a bone fabric of medical implants in stomatology and orthopedy etc.). In the given work the modes of reception regulated micro- and macrorough surfaces on samples from a titanic alloy and stainless steel by electrothermal influence of moving cathodic stains in the vacuum arc discharge are investigated. Chaotically moving stains, possessing high specific power allocation (∼ 107 W/cm2), “scan” the difficult design of a product, including “shadow” sites, doing rough its blanket. The sizes of roughnesses are regulated by a current and time of influence of the discharge, pressure in the vacuum chamber and a number of other parameters. The scheme of experimental device, photo and the characteristic of rough surfaces and technological modes of their reception are resulted.

  12. 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.

  13. Effect of annealing process on TiN/TiC bilayers grown by pulsed arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Rivera, L., E-mail: lramosr@unal.edu.co [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Aeropuerto Campus La Nubia (Colombia); Escobar, D.; Benavides-Palacios, V.; Arango, P.J.; Restrepo-Parra, E. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Aeropuerto Campus La Nubia (Colombia)

    2012-08-15

    In this work, a study of annealing process effect on TiN/TiC bilayer is presented. The annealing temperature was varied between room temperature and 500 Degree-Sign C. Materials were produced by the plasma-assisted pulsed vacuum arc discharge technique. In order to grow the films, a target of Ti with 99.9999% purity and stainless-steel 304 substrate were used. For the production of TiN layer, the reaction chamber was filled up with nitrogen gas until reaching 25 Pa and the discharge was performed at 310 V. The TiC layer was grown in a methane atmosphere at 30 Pa and 270 V. X-ray diffraction and X photoelectron spectroscopy were employed for studying the structure and chemical composition evolution during the annealing process. At 400 Degree-Sign C, TiO{sub 2} phase begun to appear and it was well observed at 500 Degree-Sign C. Crystallite size and microstrain was obtained as a function of the annealing temperature. XPS technique was employed for analyzing the bilayers before and after the annealing process. Narrow spectra of Ti2p, N1s and O1s were obtained, presenting TiO phases.

  14. Modification of anti-bacterial surface properties of textile polymers by vacuum arc ion source implantation

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaev, A.G., E-mail: nik@opee.hcei.tsc.ru [High Current Electronics Institute, Siberian Branch of the Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Yushkov, G.Yu.; Oks, E.M. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Oztarhan, A. [Izmir University, Izmir 35140 (Turkey); Akpek, A.; Hames-Kocabas, E.; Urkac, E.S. [Bioengineering Department, Ege University, Bornova 35100, Izmir (Turkey); Brown, I.G. [Lawrence Berkeley National Laboratory, Berkeley, CA 94708 (United States)

    2014-08-15

    Highlights: • Ion implantation. • Anti-bacterial properties. • Textile polymer. • Vacuum arc ion source. - Abstract: Ion implantation provides an important technology for the modification of material surface properties. The vacuum arc ion source is a unique instrument for the generation of intense beams of metal ions as well as gaseous ions, including mixed metal–gas beams with controllable metal:gas ion ratio. Here we describe our exploratory work on the application of vacuum arc ion source-generated ion beams for ion implantation into polymer textile materials for modification of their biological cell compatibility surface properties. We have investigated two specific aspects of cell compatibility: (i) enhancement of the antibacterial characteristics (we chose to use Staphylococcus aureus bacteria) of ion implanted polymer textile fabric, and (ii) the “inverse” concern of enhancement of neural cell growth rate (we chose Rat B-35 neuroblastoma cells) on ion implanted polymer textile. The results of both investigations were positive, with implantation-generated antibacterial efficiency factor up to about 90%, fully comparable to alternative conventional (non-implantation) approaches and with some potentially important advantages over the conventional approach; and with enhancement of neural cell growth rate of up to a factor of 3.5 when grown on suitably implanted polymer textile material.

  15. Wall interactions with plasma generated by vacuum arcs and targets irradiated by intense laser beams

    Energy Technology Data Exchange (ETDEWEB)

    Beilis, Isak I [Electrical Discharge and Plasma Laboratory, School of Electrical Engineering, Fleischman Faculty of Engineering Tel Aviv University, PO Box 39040, Tel Aviv 69978 (Israel)

    2009-02-01

    The theory of plasma-wall interactions in vacuum arc spots and in laser irradiated spots is reviewed in light of Langmuir's fundamental contributions to the theory of plasmas, sheaths, evaporation and electron emission. The mechanisms of plasma generation in the electrode and laser-target vapors are described. Models of sheath structures at surfaces which emit vapor and electrons are presented and the influence of the relation between the rates of electron and vapor emission on the electrical current continuity at the plasma-electrode boundary is discussed. The mechanisms of current continuity in the vacuum arc anode region, in the short vacuum arc, and in transient cathode spots are described. The important role of the near-target sheath in laser generated plasma is shown, indicating the effect of converting laser radiation absorbed in plasma into kinetic and potential energy of charged particles that impinge on the target. The description is summarized showing that understanding these phenomena relies on Langmuir's pioneering work.

  16. Spatiotemporally resolved characteristics of a gliding arc discharge in a turbulent air flow at atmospheric pressure

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2017-01-01

    of the glow-type discharge is the same as that of the electronic power dissipated in the plasma column. The glow-type discharge can transfer into a spark discharge characterized by a sharp peak current of several amperes and a sudden increase of the brightness in the plasma column. Transitions can also......A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by a 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the gliding arc discharge, including glow-type discharges, spark-type discharges, short-cutting events...... be found to take place from spark-type discharges to glow-type discharges. Short-cutting events were often observed as the intermediate states formed during the spark-glow transition. Three different types of short-cutting events have been observed to generate new current paths between two plasma channel...

  17. Protective coating of inner surface of steel tubes via vacuum arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Maile, K.; Roos, E.; Lyutovich, A.; Boese, J.; Itskov, M. [Stuttgart Univ. (DE). Materialpruefungsanstalt (MPA); Ashurov, Kh.; Mirkarimov, A.; Kazantsev, S.; Kadirov, Kh. [Uzbek Academy of Science, Tashkent (Uzbekistan). Arifov Inst. of Electronics

    2010-07-01

    The Vacuum Arc Deposition (VAD) technique based on sputtering a chosen electrode material and its deposition via plasma allows highly-productive technology for creating a wide class of protecting coatings on complex structures. In this work, VAD was applied as a method for the protection of the inner surface of tubes for power-plant boilers against steam oxidation. For this aim, a source cathode of an alloy with high chromium and nickel content was employed in two different VAD treatment systems: a horizontal vacuum chamber (MPA) and a vertical system where the work-piece of the tubes to be protected served as a vacuum changer (Arifov Institute of Electronics). Surface coating with variation of deposition parameters and layer thickness was performed. Characterisation of coated tubes has shown that the method realised in this work allows attainment of material transfer from the cathode to the inner surface with nearly equal chemical composition. It was demonstrated that the initial martensitic structure of the tubes was kept after the vacuum-arc treatment which can provide for both the high mechanical robustness and the corrosion-resistance of the final material. (orig.)

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

    Science.gov (United States)

    Zhu, Jiajian; Ehn, Andreas; Gao, Jinlong; Kong, Chengdong; Aldén, Marcus; Salewski, Mirko; Leipold, Frank; Kusano, Yukihiro; Li, Zhongshan

    2017-08-21

    Translational, rotational, vibrational and electron temperatures of a gliding arc discharge in atmospheric pressure air were experimentally investigated using in situ, non-intrusive optical diagnostic techniques. The gliding arc discharge was driven by a 35 kHz alternating current (AC) power source and operated in a glow-type regime. The two-dimensional distribution of the translational temperature (Tt) of the gliding arc discharge was determined using planar laser-induced Rayleigh scattering. The rotational and vibrational temperatures were obtained by simulating the experimental spectra. The OH A-X (0, 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 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 of these four different temperatures (Te>Tv>Tr >Tt) suggest a high-degree non-equilibrium state of the gliding arc discharge.

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

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Ehn, Andreas; Gao, Jinlong

    2017-01-01

    Translational, rotational, vibrational and electron temperatures of a gliding arc discharge in atmospheric pressure air were experimentally investigated using in situ, non-intrusive optical diagnostic techniques. The gliding arc discharge was driven by a 35 kHz alternating current (AC) power source...... and operated in a glow-type regime. The two-dimensional distribution of the translational temperature (Tt) of the gliding arc discharge was determined using planar laser-induced Rayleigh scattering. The rotational and vibrational temperatures were obtained by simulating the experimental spectra. The OH A–X (0......, 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...

  20. Monitoring Nanoparticle Synthesis in a Carbon Arc Discharge Environment, In Situ

    Science.gov (United States)

    Mitrani, James

    This work presents experimental and theoretical studies of gas-phase synthesis of fullerenes and carbon nanoparticles in the presence of an atmospheric-pressure, arc discharge plasma. Carbon arc discharges have been used for synthesizing carbon nanotubes for over 25 years, and have the potential for economically synthesizing industrial-scale quantities of fullerenes. However, the efficiency and selectivity of fullerene synthesis with carbon arc discharges are quite low. Optimizing carbon arc discharges for fullerene synthesis requires a thorough understanding of the dynamics behind gas-phase nanoparticle synthesis in the presence of an arc discharge plasma. We built a carbon arc discharge setup to study nanoparticle and fullerene synthesis. The laser-induced incandescence (LII) diagnostic was applied for monitoring nanoparticle synthesis, in situ. The LII diagnostic had previously been applied as a combustion diagnostic for in situ measurements of concentrations and sizes of soot particles in flame environments. Prior to the present study, it had never been applied for studying fullerenes, nor had it been applied to study nanoparticles in the presence of an atmospheric-pressure plasma. Therefore, experiments were designed that allowed for the calibration of the LII diagnostic with research-grade, arc-synthesized soot particles and carbon nanotubes. Additionally, the theory and models underpinning the LII diagnostic were adapted to include the presence of an atmospheric-pressure, arc-discharge plasma. Results presented in this work confirm the ability of the LII diagnostic to measure sizes of arc-synthesized nanoparticles in situ, and show the spatial location of high densities of arc-synthesized nanoparticles with respect to the arc discharge plasma. Determining the spatial location of nanoparticle synthesis and growth is crucial for understanding the background conditions (e.g. background gas temperature, electron densities ...) in which nanoparticles nucleate and

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

    Directory of Open Access Journals (Sweden)

    M. Arroyave Franco

    2006-06-01

    Full Text Available 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 in all cases it was possible to identify nanoparticle presence. Further X-ray Diffraction spectra of sample coating were taken. Existence of contaminant particles of 47 nanometers in diameter was reported.En este trabajo se presenta un método alternativo basado en microscopia de modulación de fuerza (FMM, para la identificación de nanogotas producidas en el plasma generado por los spots catódicos de los arcos en vacío. La técnica FMM esta habilitada para la detección de variaciones en las propiedades mecánicas de una superficie, con alta sensibilidad. Se han analizado recubrimientos de nitruro de titanio (TiN depositados sobre Silicio orientado por el proceso de arco en vacío pulsado. Se han obtenido simultáneamente imágenes de microscopia de fuerza atómica (AFM y de microscopia FMM mediante las cuales se ha podido identificar la presencia de nanogotas. Adicionalmente se han tomado espectros de difracción de rayos X (XRD de las muestras recubiertas. Se ha reportado la existencia de partículas contaminantes de 47 nanómetros de diámetro sobre los recubrimientos.

  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. Adhesion improvement of glass-fibre-reinforced polyester composites by gliding arc discharge treatment

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Sørensen, Bent F.; Løgstrup Andersen, Tom

    2013-01-01

    A gliding arc is a plasma that can be operated at atmospheric pressure and applied for plasma surface treatment for adhesion improvement. In the present work, glass-fibre-reinforced polyester plates were treated using an atmospheric pressure gliding arc discharge with an air flow to improve...... resistance as a function of nominal mode mixity) of the laminate adhesive interface. It was found that gliding arc treatment significantly increases the interfacial fracture energy and fracture resistance in comparison with a standard peel ply treatment, although the mixed mode fracture energy of the gliding...... arc treated specimen was not as high as that of the laminate itself....

  4. Multiwalled Carbon Nanotube Synthesis Using Arc Discharge with Hydrocarbon as Feedstock

    Directory of Open Access Journals (Sweden)

    K. T. Chaudhary

    2013-01-01

    Full Text Available Synthesis of multiwalled carbon nanotube (MWCNT by arc discharge process is investigated with methane (CH4 as background and feedstock gas. The arc discharge is carried out between two graphite electrodes for ambient pressures 100, 300, and 500 torr and arc currents 50, 70, and 90 A. Plasma kinetics such as the density and temperature for arc discharge carbon plasma is determined to find out the contribution of physical parameters as arc current and ambient pressure on the plasma dynamics and growth of MWCNT. With increase in applied arc current and ambient pressure, an increase in plasma temperature and density is observed. The synthesized samples of MWCNT at different experimental conditions are characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. A decrease in the diameter and improvement in structure quality and growth of MWCNT are observed with increase in CH4 ambient pressure and arc current. For CH4 ambient pressure 500 torr and arc current 90 A, the well-aligned and straight MWCNT along with graphene stakes are detected.

  5. Experimental Study of Magnetic Field Effect on dc Corona Discharge in Low Vacuum

    Science.gov (United States)

    Elabbas, K.

    2014-09-01

    In the present paper, an attempt was made to investigate the effect of applying a transverse magnetic field on the dc corona discharge behavior in low vacuum. In general, two experiments were carried out in this work: the first is the ionization-region magnetic field experiment, and the second was the drift region magnetic field experiment. In these experiments, permanent magnets were used to produce magnetic field. The degree of vacuum used in this test was 0.4×105 Pa. It is found that the effect of the magnetic field increases as the degree of vacuum increases. It is also seen from this study that the corona current values are higher with magnetic fields than without magnetic fields. The experimental results indicate that the enhancement of the magnetic field near the wire discharge electrode has a significant influence on the increment of the discharge current. The effect of the magnetic field on the discharge current is the most significant with the negative corona discharges rather than with positive corona discharge. In contrast to, the curves were demonstrated that the application of magnetic fields in drift region magnetic field does not significantly change the corona discharge current. Discharge characteristics of magnetically enhanced corona discharges, extracted from this study, can be applied to various industrial applications, such as, in an electrostatic enhancement filter for the purpose of capturing fine particles, and as effective method for production of high ozone concentrations in a generator as compared to the ultraviolet (UV) radiation method.

  6. Carbon Single-Wall Nanatube Growth in a Volumetrically Confined Arc Discharge System

    Energy Technology Data Exchange (ETDEWEB)

    Franz, K.J.; Alleman, J.L.; Jones, K.M.; Dillon, A.C.; Heben, M.J.

    2004-01-01

    Carbon nanotubes hold significant promise for a vast number of materials applications due to their unique mechanical, electrical, and gas storage properties. Although carbon single-wall nanotubes (SWNTs) have been synthesized since 1993 by the arc discharge method, and numerous other synthesis methods have since been developed, no method has yet produced 100% pure carbon nanotubes. Instead, a significant amount of impurities—various carbon structures and metal catalysts—are present in the raw soot. While arc discharge was the first method for SWNT synthesis, it also produces more impure raw soot in comparison to the more recently developed laser vaporization, which has produced the purest raw soot to date but is much slower. Geometry and thermal gradient are appreciably different between traditional arc discharge systems and laser vaporization systems. We report that, by incorporating some characteristics inherent to a laser vaporization system into an arc discharge system, improvement in the yield of SWNT raw soot may be achieved. This is accomplished by confining the arc within a 50 mm diameter quartz tube, similar to laser vaporization. We find through transmission electron microscopy and Raman spectroscopy that SWNTs are made in significant numbers in this confined arc discharge system, comparable to laser vaporization synthesized material. Further study is, however, required to prove reproducibility and attain an exact value for the purity of the produced raw soot.

  7. Correlation study of nanocrystalline carbon doped thin films prepared by a thermionic vacuum arc deposition technique

    Science.gov (United States)

    Dinca-Balan, Virginia; Vladoiu, Rodica; Mandes, Aurelia; Prodan, Gabriel

    2017-11-01

    The synthesis of Ag, Mg and Si nanocrystalline, embedded in a hydrogen-free amorphous carbon (a-C) matrix, deposited by a high vacuum and free buffer gas technique, were investigated. The films with compact structures and extremely smooth surfaces were prepared using the thermionic vacuum arc method in one electron gun configuration, on glass and silicon substrates. The surface morphology and wettability of the obtained multifunctional thin films were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and free surface energy (FSE) by See System. The results from the TEM measurements show how the Ag, Mg and Si interacted with carbon and the influence these materials have on the thin film structure formation and the grain size distribution. SEM correlated with EDX results reveal a very precise comparative study, regarding the quantity of the elements that morphed into carbides nanostructures. Also, the FSE results prove how different materials in combination with carbon can make changes to the surface properties.

  8. Modulation of field emission properties of znO nanorods during arc discharge.

    Science.gov (United States)

    Fang, F; Kennedy, J; Carder, D A; Futter, J; Murmu, P; Markwitz, A

    2010-12-01

    Zinc oxide (ZnO) nanorods have been synthesized via the arc discharge method. Different oxygen partial pressures were applied in the arc discharge chamber to modulate the field emission properties of the as-synthesized ZnO nanorods. Scanning electron microscopy (SEM) was carried out to analyze the morphology of the ZnO nanorods. The ion beam analysis technique of proton induced X-ray emission (PIXE) was performed to probe the impurities in ZnO nanorods. SEM images clearly revealed the formation of randomly oriented ZnO nanorods with diameters between 10-50 nm. It was found that the morphology and the electrical properties of the ZnO nanorods were dependent on the oxygen partial pressure during arc discharge. In addition enhanced UV-sensitive photoconductivity was found for ZnO nanorods synthesized at high oxygen partial pressure during arc discharge. The field emission properties of the nanorods were studied. The turn-on field, which is defined at a current density of 10 microA cm(-2), was about 3 V microm(-1) for ZnO nanorods synthesized at 99% oxygen partial pressure during arc discharge. The turn-on field for ZnO nanorods increased with the decrease of oxygen partial pressure during arc discharge. The simplicity of the synthesis route coupled with the modulation of field emission properties due to the arc discharge method make the ZnO nanorods a promising candidate for a low cost and compact cold cathode material.

  9. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan

    2014-01-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating...... current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column......, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light...

  10. Investigations of near infrared reflective behaviour of TiO2 nanopowders synthesized by arc discharge

    Science.gov (United States)

    Fang, Fang; Kennedy, John; Carder, Damian; Futter, John; Rubanov, Sergey

    2014-05-01

    Titanium dioxide (TiO2) nanopowders with different polymorphic phases were successfully synthesized by an arc discharge method. Samples were characterized using synchrotron radiation X-ray diffraction, high resolution scanning electron microscopy, high resolution transmission electron microscope and near infrared diffuse reflectance spectroscopy. Spherical structures were obtained after arc discharge. A mixture of both anatase and rutile phases was discovered in TiO2 samples synthesized at an arc current of 50 A, showing a majority particle size of 34 nm with size distribution between 5 nm and 60 nm. Completed anatase to rutile phase transformation was observed when the arc current increased from 50 A to 74 A. The crystallite size of the TiO2 nanopowders was significant effected by the arc discharge current during synthesis. After the arc current increased from 74 A to 110 A, the majority particle size of the obtained TiO2 increased to 85 nm with a size distribution in the range between 50 nm and 1800 nm. Diffuse reflectance of the TiO2 nanopowders synthesized at different arc discharge currents was measured. Broadband near infrared reflection (800-950 nm) of up to 50% was observed for TiO2 nanopowders synthesized at an arc current of 74 A. It is considered that rutile phase together with an appropriate mean crystallite size of the TiO2 nanopowders synthesized at an arc current of 74 A contributes to the best near infrared reflectivity in this study. The developed TiO2 nanoppowders will be of immense use in NIR reflective pigment.

  11. Differential Inactivation of Fungal Spores in Water and on Seeds by Ozone and Arc Discharge Plasma.

    Science.gov (United States)

    Kang, Min Ho; Pengkit, Anchalee; Choi, Kihong; Jeon, Seong Sil; Choi, Hyo Won; Shin, Dong Bum; Choi, Eun Ha; Uhm, Han Sup; Park, Gyungsoon

    2015-01-01

    Seed sterilization is essential for preventing seed borne fungal diseases. Sterilization tools based on physical technologies have recently received much attention. However, available information is very limited in terms of efficiency, safety, and mode of action. In this study, we have examined antifungal activity of ozone and arc discharge plasma, potential tools for seed sterilization. In our results, ozone and arc discharge plasma have shown differential antifungal effects, depending on the environment associated with fungal spores (freely submerged in water or infected seeds). Ozone inactivates Fusarium fujikuroi (fungus causing rice bakanae disease) spores submerged in water more efficiently than arc discharge plasma. However, fungal spores associated with or infecting rice seeds are more effectively deactivated by arc discharge plasma. ROS generated in water by ozone may function as a powerful fungicidal factor. On the other hand, shockwave generated from arc discharge plasma may have greatly contributed to antifungal effects on fungus associated with rice seeds. In support of this notion, addition of ultrasonic wave in ozone generating water has greatly increased the efficiency of seed disinfection.

  12. Differential Inactivation of Fungal Spores in Water and on Seeds by Ozone and Arc Discharge Plasma.

    Directory of Open Access Journals (Sweden)

    Min Ho Kang

    Full Text Available Seed sterilization is essential for preventing seed borne fungal diseases. Sterilization tools based on physical technologies have recently received much attention. However, available information is very limited in terms of efficiency, safety, and mode of action. In this study, we have examined antifungal activity of ozone and arc discharge plasma, potential tools for seed sterilization. In our results, ozone and arc discharge plasma have shown differential antifungal effects, depending on the environment associated with fungal spores (freely submerged in water or infected seeds. Ozone inactivates Fusarium fujikuroi (fungus causing rice bakanae disease spores submerged in water more efficiently than arc discharge plasma. However, fungal spores associated with or infecting rice seeds are more effectively deactivated by arc discharge plasma. ROS generated in water by ozone may function as a powerful fungicidal factor. On the other hand, shockwave generated from arc discharge plasma may have greatly contributed to antifungal effects on fungus associated with rice seeds. In support of this notion, addition of ultrasonic wave in ozone generating water has greatly increased the efficiency of seed disinfection.

  13. Ion charge state distributions of vacuum arc plasmas: The origin of species

    Energy Technology Data Exchange (ETDEWEB)

    Anders, A. [Ernest O. Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

    1997-01-01

    Vacuum arc plasmas are produced at micrometer-size, nonstationary cathode spots. Ion charge state distributions (CSD{close_quote}s) are experimentally known for 50 elements, but the theoretical understanding is unsatisfactory. In this paper, CSD{close_quote}s of vacuum arc plasmas are calculated under the assumption that the spot plasma experiences an instantaneous transition from equilibrium to nonequilibrium while expanding. Observable charge state distributions are the result of a freezing process at this transition. {open_quotes}Frozen{close_quotes} CSD{close_quote}s have been calculated using Saha equations in the Debye-H{umlt u}ckel approximation of the nonideal plasma for all metals of the Periodic Table and for boron, carbon, silicon, and germanium. The results are presented in a {open_quotes}periodic table of CSD.{close_quotes} The table contains also the mean ion charge state, the neutral vapor fraction, and the effective plasma temperature and density at the freezing point for each element. The validity of the concepts of {open_quotes}instantaneous freezing{close_quotes} and {open_quotes}effective temperature and density{close_quotes} is discussed for low and high currents and for the presence of a magnetic field. Temperature fluctuations have been identified to cause broadening of CSD{close_quote}s. {copyright} {ital 1997} {ital The American Physical Society}

  14. Ion charge state distributions of vacuum arc plasmas: The origin of species

    Science.gov (United States)

    Anders, André

    1997-01-01

    Vacuum arc plasmas are produced at micrometer-size, nonstationary cathode spots. Ion charge state distributions (CSD's) are experimentally known for 50 elements, but the theoretical understanding is unsatisfactory. In this paper, CSD's of vacuum arc plasmas are calculated under the assumption that the spot plasma experiences an instantaneous transition from equilibrium to nonequilibrium while expanding. Observable charge state distributions are the result of a freezing process at this transition. ``Frozen'' CSD's have been calculated using Saha equations in the Debye-Hüautckel approximation of the nonideal plasma for all metals of the Periodic Table and for boron, carbon, silicon, and germanium. The results are presented in a ``periodic table of CSD.'' The table contains also the mean ion charge state, the neutral vapor fraction, and the effective plasma temperature and density at the freezing point for each element. The validity of the concepts of ``instantaneous freezing'' and ``effective temperature and density'' is discussed for low and high currents and for the presence of a magnetic field. Temperature fluctuations have been identified to cause broadening of CSD's.

  15. 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...

  16. Ion confinement in laser-initiated vacuum arcs and advanced thermonuclear fuel studies. Final report, April 15, 1977-February 15, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, J L

    1981-03-01

    Experimental investigations were carried out of magneto-electrostatic confinement in laser-initiated vacuum arcs. Over a range of laser powers and discharge currents, inhibition in escape of energetic C/sup +/-C/sup 4 +/ ions was observed simultaneously in several directions. The ion confinement was observed to scale with the energy of the laser produced ions and the discharge voltage (i.e. anode sheath voltage). A numerical code was developed for determining fast proton coulomb slowing in a hot target plasma of lithium, boron, or berillium. This code showed that, under very optimistc conditions, F values in excess of unity appear possible for a catalyzed p-/sup 6/Li two component reactor.

  17. High-RRR thin-films of NB produced using energetic condensation from a coaxial, rotating vacuum ARC plasma (CEDTM)

    Science.gov (United States)

    Valderrama, Enrique Francisco; James, Colt; Krishnan, Mahadevan; Zhao, Xin; Phillips, Larry; Reece, Charles; Seo, Kang

    2012-06-01

    We have recently demonstrated unprecedentedly high values of RRR (up to 542) in thin-films of pure Nb deposited on a-plane sapphire and MgO crystal substrates. The Nb films were grown using a vacuum arc discharge struck between a reactor grade Nb cathode rod (RRR 30) and a coaxial, semi-transparent Mo mesh anode, with a heated substrate placed just outside it. The substrates were pre-heated for several hours prior to deposition at different temperatures. Low pre-heat temperatures (600°C) is correlated with better epitaxial crystal structure in both a-sapphire and MgO substrate grown films. However, the SIMS data reveal that the most important requirement for high-RRR Nb films on either substrate is the reduction of impurities in the film, especially hydrogen. The hydrogen content in the MgO grown films is 1000 times lower than in bulk Nb tested as a reference from SRF cavity grade Nb. This result has potential implications for SRF accelerators. Coating bulk Nb cavities with an MgO layer followed by our CEDTM deposited Nb films, might create superior SRF cavities that would avoid Q-slope and operate at higher peak fields. This research was supported by Department of Energy grants DE-SC0004994 and DE-FG02-08ER85162.

  18. Iron nanoparticles grown in a carbon arc discharge

    NARCIS (Netherlands)

    Zhang, G.L.; du Marchie van Voorthuysen, E.H.; Szymanski, K.; Boom, G; Verwerft, M.G M; Jonkman, H.T.; Niesen, L

    1996-01-01

    Iron particles, encapsulated by graphite layers, were produced by means of the Kratschmer are discharge method in an iron pentacarbonyl atmosphere. The Mossbauer effect is dominated by the vibration of the particles as a whole. Superparamagnetism is dominant for iron oxide particles. No endohedral

  19. Elastic modulus of diamond-like carbon films prepared by pulsed vacuum arc

    Science.gov (United States)

    Schultrich, B.; Scheibe, H.-J.; Grandremy, G.; Schneider, D.; Siemroth, P.

    1994-12-01

    Amorphous carbon films have been prepared by special pulsed vacuum arc depositon methods allowing high currents up to 1 kA and more. The Young's modulus of these films has been determined with respect to various technological parameters. For these measurements a method based on the propagation of ultrasonic surface waves has been applied which has been specially designed for the investigation of thin films below one micrometer. Large changes of the elastic modulus, depending on the technology, have been observed, contrasting with the common understanding of invariability of the elastic behavior. Reflecting the large structural variations possible in amorphous carbon, the elastic modulus represents a suitable parameter for characterizing the carbon-carbon network. Furthermore, the elastic modulus of amorphous carbon films may be used for a first estimation of film hardness because of the strong correlation of these two quantities.

  20. Highly transparent and conductive ZnO:Al thin films prepared by vacuum arc plasma evaporation

    Science.gov (United States)

    Miyata, Toshihiro; Minamino, Youhei; Ida, Satoshi; Minami, Tadatsugu

    2004-07-01

    A vacuum arc plasma evaporation (VAPE) method using both oxide fragments and gas sources as the source materials is demonstrated to be very effective for the preparation of multicomponent oxide thin films. Highly transparent and conductive Al-doped ZnO (AZO) thin films were prepared by the VAPE method using a ZnO fragment target and a gas source Al dopant, aluminum acethylacetonate (Al(C5H7O2)3) contained in a stainless steel vessel. The Al content in the AZO films was altered by controlling the partial pressure (or flow rate) of the Al dopant gas. High deposition rates as well as uniform distributions of resistivity and thickness on the substrate surface were obtained on large area glass substrates. A low resistivity on the order of 10-4 Ω cm and an average transmittance above 80% in the visible range were obtained in AZO thin films deposited on glass substrates. .

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

    Science.gov (United States)

    Raniszewski, Grzegorz; Wiak, Slawomir; Pietrzak, Lukasz; Szymanski, Lukasz; Kolacinski, Zbigniew

    2017-02-23

    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.

  2. 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.

  3. 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.

  4. Two-dimensional simulation research of secondary electron emission avalanche discharge on vacuum insulator surface

    Science.gov (United States)

    Cai, Libing; Wang, Jianguo; Zhu, Xiangqin; Wang, Yue; Zhang, Dianhui

    2015-01-01

    Based on the secondary electron emission avalanche (SEEA) model, the SEEA discharge on the vacuum insulator surface is simulated by using a 2D PIC-MCC code developed by ourselves. The evolutions of the number of discharge electrons, insulator surface charge, current, and 2D particle distribution are obtained. The effects of the strength of the applied electric field, secondary electron yield coefficient, rise time of the pulse, length of the insulator on the discharge are investigated. The results show that the number of the SEEA electrons presents a quadratic dependence upon the applied field strength. The SEEA current, which is on the order of Ampere, is directly proportional to the field strength and secondary electron yield coefficient. Finally, the electron-stimulated outgassing is included in the simulation code, and a three-phase discharge curve is presented by the simulation, which agrees with the experimental data.

  5. Effectiveness of recycling light in ultra-bright short-arc discharge lamps.

    Science.gov (United States)

    Malul, Asher; Nakar, Doron; Feuermann, Daniel; Gordon, Jeffrey M

    2007-10-17

    Recycling light back into a plasma lamp's radiant zone can enhance its radiance. Measurements are reported for the effectiveness, spectral properties and modified plasma radiance maps that result from light recycling with a specular hemispherical mirror in commercial 150 W ultrabright Xenon short-arc discharge lamps, motivated by projection, biomedical and high-temperature furnace applications. For certain spectral windows and plasma arc regions, radiance can be heightened by up to 70%. However, the overall light recycling efficiency is reduced to about half this value due to lamp geometry. The manner in which light-plasma interactions affect light recycling efficacy is also elucidated.

  6. On the Dissolution of Nitrided Titanium Defects During Vacuum Arc Remelting of Ti Alloys

    Science.gov (United States)

    Ghazal, G.; Jardy, A.; Chapelle, P.; Millet, Y.

    2010-06-01

    The elimination of high interstitial defects (also known as hard-α inclusions) is of great importance to the titanium industry. This article presents a model capable of simulating the motion and dissolution of such defects during their residence in the pool of a vacuum arc remelted (VAR) ingot. To predict the complete history of that inclusion, the study couples a dissolution model of the defect and a Lagrangian particle-tracking model. This numerical tool is implemented in SOLAR (solidification during arc remelting), a computational fluid dynamics code developed at the Nancy School of Mines in the framework of an important research project conducted during the last 15 years, which aims to study and optimize the VAR process. The dissolution model numerically solves the nitrogen diffusion equation in a spherical inclusion and in thermal equilibrium with the surrounding fluid. The computational domain is divided into a central zone (α phase) and a surrounding layer (β phase), which appears because the diffusion of nitrogen into the liquid pool causes some solidification. The dissolution kinetics strongly depend on the liquid temperature and velocity of the inclusion. The model can compute the nitrogen profile in the defect at each moment as well as the thickness of the different layers; therefore, it can compute the overall size of the inclusion. The trajectory model consists of solving Newton’s law of motion. Because the inclusion size is large, the consequence of fluid-flow turbulence is to modify the local flow around the inclusion so that the drag is affected. Results presented and discussed in this article include a parametric study of the influence of the pool thermohydrodynamics, the relative inclusion-fluid density, and the initial diameter of the defect as it enters the melt pool. Finally, an example of the full history of an inclusion during triple VAR illustrates the possibility to remove such a defect effectively by dissolving it in the liquid phase.

  7. The production of magnetic nanoparticles of Iron Oxide by arc discharge in water

    Science.gov (United States)

    Yousefi, Hamid Reza; Fathollah, Sara; Nikeyn, Maryam; Khatami, Shohreh

    2012-10-01

    Nanoparticles can be utilized for any practical application. In recent years; considerable attention has been paid to iron oxide magnetic. Iron oxide nanoparticles are the class of nanoparticle which can have useful magnetic properties. In this research, magnetic iron oxide nanoparticles were produced by Arc discharge method in water. Structural analysis carried out by X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM), and Spectrophotometer. Various magnetic nanoparticles like iron carbide (Fe3c), magnetic iron oxide (magnetite /maghemite) are obtained by arc discharge method in water. In this work have been showed, the influence of the time duration on the number of magnetic nanoparticles and the influence of the gap between the two electrodes on particle structure and size distribution. Furthermore, when iron nanoparticles are used under applied magnetic field, the particles would move in the direction of magnetic field. When the magnetic field is removed, the particles stop moving and still remain stably suspend in the dielectric liquid.

  8. Development of cold cathode arc discharge filament based multi-cusp H- ion source

    Science.gov (United States)

    Kumar, Rajnish; Ghodke, Dharmraj V.; Senecha, Vinod K.

    2017-08-01

    A cold cathode arc discharge filament based multicusp H- ion source (HNIS) has been developed using an innovative low power igniter system working in a glow discharge regime to achieve a longer lifetime of the filament. This HNIS is cesium-free and its experimental prototype generates a maximum H- ion beam (HNIB) current of 12 mA at 50 keV beam energy in pulse mode with a peak arc power of 27 kW using the triode extraction system. This article presents the results of initial commissioning of the HNIS and steering magnetic field used to separate out the co-extracted electrons from HNIB, verified through experiments and 3-D ion beam simulations.

  9. Spectroscopic studies of plasma in a carbon arc discharge for synthesis of nanomaterials

    Science.gov (United States)

    Vekselman, Vladislav; Feurer, Matthew; Yeh, Yao-Wen; Stratton, Brentley; Raitses, Yevgeny; LaboratoryPlasma Nanosynthesis Team

    2016-09-01

    An atmospheric pressure arc discharge with graphite electrodes is commonly used for synthesis of carbon nanomaterials such as buckyballs, nanotubes and graphene. In operation, the graphite anode ablates providing a feedstock material for synthesis these carbon nanostructures. Existing models predict that nucleation and growth of these nanomaterials in an arc discharge are governed by spatial distributions of density and temperature of plasma species. Control of these distributions can potentially enable optimization of nanosynthesis processes, to achieve the best combination of synthesis selectivity at the synthesis yield. In this work, we report first detail measurements of spatial distribution of arc plasma parameters obtained with a set of in-situ diagnostics, including optical emission spectroscopy and fast framing imaging. These parameters were measured in low- and high- anode ablation modes. Results of these measurements demonstrate a strong correlation between arc plasma and synthesis processes. This work was supported by U.S. Department of Energy, Office of Science, Basic Sciences, Materials Sciences and Engineering Division.

  10. Modeling of inhomogeneous mixing of plasma species in argon–steam arc discharge

    Science.gov (United States)

    Jeništa, J.; Takana, H.; Uehara, S.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; Murphy, A. B.

    2018-01-01

    This paper presents numerical simulation of mixing of argon- and water-plasma species in an argon–steam arc discharge generated in a thermal plasma generator with the combined stabilization of arc by axial gas flow (argon) and water vortex. The diffusion of plasma species itself is described by the combined diffusion coefficients method in which the coefficients describe the diffusion of argon ‘gas,’ with respect to water vapor ‘gas.’ Diffusion processes due to the gradients of mass density, temperature, pressure, and an electric field have been considered in the model. Calculations for currents 150–400 A with 15–22.5 standard liters per minute (slm) of argon reveal inhomogeneous mixing of argon and oxygen–hydrogen species with the argon species prevailing near the arc axis. All the combined diffusion coefficients exhibit highly nonlinear distribution of their values within the discharge, depending on the temperature, pressure, and argon mass fraction of the plasma. The argon diffusion mass flux is driven mainly by the concentration and temperature space gradients. Diffusions due to pressure gradients and due to the electric field are of about 1 order lower. Comparison with our former calculations based on the homogeneous mixing assumption shows differences in temperature, enthalpy, radiation losses, arc efficiency, and velocity at 400 A. Comparison with available experiments exhibits very good qualitative and quantitative agreement for the radial temperature and velocity profiles 2 mm downstream of the exit nozzle.

  11. Note: Arc discharge plasma source with plane segmented LaB6 cathode.

    Science.gov (United States)

    Akhmetov, T D; Davydenko, V I; Ivanov, A A; Kreter, A; Mishagin, V V; Savkin, V Ya; Shulzhenko, G I; Unterberg, B

    2016-05-01

    A plane cathode composed of close-packed hexagonal LaB6 (lanthanum hexaboride) segments is described. The 6 cm diameter circular cathode is heated by radiation from a graphite foil flat spiral. The cathode along with a hollow copper anode is used for the arc discharge plasma production in a newly developed linear plasma device. A separately powered coil located around the anode is used to change the magnetic field strength and geometry in the anode region. Different discharge regimes were realized using this coil.

  12. 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.

  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. Effect of Focussed Vacuum ARC Plasma Deposition on the Properties of Tetrahedral Amorphous Carbon Films

    Science.gov (United States)

    Chua, Daniel H. C.; Teo, K. B. K.; Tsai, T. H.; Robertson, J.; Milne, W. I.

    We have investigated the effect of using a magnetic field to confine and focus the plasma in a Filtered Cathodic Vacuum Arc (FCVA) deposition system used for the preparation of tetrahedrally bonded amorphous carbon (ta-C) thin films. The design of the magnetic field is such that the plasma can be confined into a high-density focussed spot or de-focussed into a lower density wide beam. Increasing the magnetic field directly increases the plasma density and thus increases the deposition rate. The ta-C films grown in the magnetic field were subsequently characterised. EELS and Raman measurement were used to measure the sp3/sp2 ratio and UV-vis spectroscopy for optical bandgap studies. The intrinsic stress and I-V characteristics of the thin films were also studied. The results show that it is possible to deposit the films at rates as high as 2.5 nm/sec without adversely affecting the material properties.

  15. Method and apparatus for controlling electrode gap during vacuum consumable arc remelting

    Science.gov (United States)

    Fisher, R.W.; Maroone, J.P.; Tipping, D.W.; Zanner, F.J.

    During vacuum consumable arc remelting the electrode gap between a consumable electrode and a pool of molten metal is difficult to control. The present invention monitors drop shorts by detecting a decrease in the voltage between the consumable electrode and molten pool. The drop shorts and their associated voltage reductions occur as repetitive pulses which are closely correlated to the electrode gap. Thus, the method and apparatus of the present invention controls electrode gap based upon drop shorts detected from the monitored anode-cathode voltage. The number of drop shorts are accumulated, and each time the number of drop shorts reach a predetermined number, the average period between drop shorts is calculated from this predetermined number and the time in which this number is accumulated. This average drop short period is used in a drop short period electrode gap model which determines the actual electrode gap from the drop short. The actual electrode gap is then compared with a desired electrode gap which is selected to produce optimum operating conditions and the velocity of the consumable error is varied based upon the gap error. The consumable electrode is driven according to any prior art system at this velocity. In the preferred embodiment, a microprocessor system is utilized to perform the necessary calculations and further to monitor the duration of each drop short. If any drop short exceeds a preset duration period, the consumable electrode is rapidly retracted a predetermined distance to prevent bonding of the consumable electrode to the molten remelt.

  16. 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.

  17. 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.

  18. High rate deposition of transparent conducting oxide thin films by vacuum arc plasma evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Minami, Tadatsugu; Ida, Satoshi; Miyata, Toshihiro

    2002-09-02

    Transparent conducting oxide (TCO) thin films have been deposited at a high rate above 370 nm/min by vacuum arc plasma evaporation (VAPE) using sintered oxide fragments as the source material. It was found that the deposition rate of TCO films was strongly dependent on the deposition pressure, whereas the obtained electrical properties were relatively independent of the pressure. Resistivities of 5.6x10{sup -4} and 2.3x10{sup -4} {omega}{center_dot}cm and an average transmittance above 80% (with substrate included) in the visible range were obtained in Ga-doped ZnO (GZO) thin films deposited at 100 and 350 deg. C, respectively. In addition, a resistivity as low as 1.4x10{sup -4} {omega}{center_dot}cm and an average transmittance above 80% were also obtained in indium-tin-oxide (ITO) films deposited at 300 deg. C. The deposited TCO films exhibited uniform distributions of resistivity and thickness on large area substrates.

  19. Preparation of anatase TiO{sub 2} thin films by vacuum arc plasma evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Miyata, Toshihiro [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan)]. E-mail: tmiyata@neptune.kanazawa-it.ac.jp; Tsukada, Satoshi [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan); Minami, Tadatsugu [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan)

    2006-02-01

    Anatase titanium dioxide (TiO{sub 2}) thin films with high photocatalytic activity have been prepared with deposition rates as high as 16 nm/min by a newly developed vacuum arc plasma evaporation (VAPE) method using sintered TiO{sub 2} pellets as the source material. Highly transparent TiO{sub 2} thin films prepared at substrate temperatures from room temperature to 400 deg. C exhibited photocatalytic activity, regardless whether oxygen (O{sub 2}) gas was introduced during the VAPE deposition. The highest photocatalytic activity and photo-induced hydrophilicity were obtained in anatase TiO{sub 2} thin films prepared at 300 deg. C, which correlated to the best crystallinity of the films, as evidenced from X-ray diffraction. In addition, a transparent and conductive anatase TiO{sub 2} thin film with a resistivity of 2.6 x 10{sup -1} {omega} cm was prepared at a substrate temperature of 400 deg. C without the introduction of O{sub 2} gas.

  20. Mechanism of Synthesis of Ultra-Long Single Wall Carbon Nanotubes in Arc Discharge Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Keidar, Michael [George Washington University

    2013-06-23

    In this project fundamental issues related to synthesis of single wall carbon nanotubes (SWNTs), which is relationship between plasma parameters and SWNT characteristics were investigated. Given that among plasma-based techniques arc discharge stands out as very advantageous in several ways (fewer defects, high flexibility, longer lifetime) this techniques warrants attention from the plasma physics and plasma technology standpoint. Both experimental and theoretical investigations of the plasma and SWNTs synthesis were conducted. Experimental efforts focused on plasma diagnostics, measurements of nanostructures parameters, and nanoparticle characterization. Theoretical efforts focused to focus on multi-dimensional modeling of the arc discharge and single wall nanotube synthesis in arc plasmas. It was demonstrated in experiment and theoretically that controlling plasma parameters can affect nanostucture synthesis altering SWNT properties (length and diameter) and leading to synthesis of new structures such as a few-layer graphene. Among clearly identified parameters affecting synthesis are magnetic and electric fields. Knowledge of the plasma parameters and discharge characteristics is crucial for ability to control synthesis process by virtue of both magnetic and electric fields. New graduate course on plasma engineering was introduced into curriculum. 3 undergraduate students were attracted to the project and 3 graduate students (two are female) were involved in the project. Undergraduate student from Historically Black University was attracted and participated in the project during Summer 2010.

  1. A paradigm study for assessment of phenylalanine's damage under arc-discharge irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ke Zhigang [Laboratory of Ion Beam Bio-engineering, Institute of Plasma Physics of Chinese Academy of Sciences, P.O. Box 1126, Shushanhu Road 350, Hefei 230031 (China); Huang Qing, E-mail: huangq@ipp.ac.c [Laboratory of Ion Beam Bio-engineering, Institute of Plasma Physics of Chinese Academy of Sciences, P.O. Box 1126, Shushanhu Road 350, Hefei 230031 (China); Su Xi; Jiang Jiang; Wang Xiangqin; Yu Zengliang [Laboratory of Ion Beam Bio-engineering, Institute of Plasma Physics of Chinese Academy of Sciences, P.O. Box 1126, Shushanhu Road 350, Hefei 230031 (China)

    2010-05-15

    Energetic ions induce important biological effects and the research into radiolysis of amino acids can help to clarify radiolysis of proteins. For this purpose, arc-discharge induced radiolysis of the benzyl-containing aromatic amino acid phenylalanine in aqueous solution was studied and the damage was assessed quantitatively. The energetic ions were produced by arc-discharge in nitrogen and argon atmosphere. The arc-discharge induced chemical reactions of the biomolecule in aqueous solution were detected and analyzed by means of UV-Vis absorption, fluorescence, Fourier transformation infrared (FTIR) spectroscopy and high performance liquid chromatography (HPLC). Based on the multiple spectroscopic approach, the damage can be evaluated in a more reliable and convenient way. The fluorescence analysis in this case appears to be a more direct indicator for the assessment of damage, where it reveals that the damage increases with the irradiation time exponentially. On the contrary, the 'plateau region' or 'saddle-shape' apparently shown both in our rough absorption analysis and ninhydrin reaction test, similar to the previously reported feature of the dose effect for low-energy-ion induced damage, may be just a consequence with varied reactions and processes involved at different stages. This work thus demonstrated that application of appropriate combination of spectroscopic tools can effectively dissect the diversity of the radiolysis reaction system and assess the biomolecular damage properly.

  2. A paradigm study for assessment of phenylalanine’s damage under arc-discharge irradiation

    Science.gov (United States)

    Ke, Zhigang; Huang, Qing; Su, Xi; Jiang, Jiang; Wang, Xiangqin; Yu, Zengliang

    2010-05-01

    Energetic ions induce important biological effects and the research into radiolysis of amino acids can help to clarify radiolysis of proteins. For this purpose, arc-discharge induced radiolysis of the benzyl-containing aromatic amino acid phenylalanine in aqueous solution was studied and the damage was assessed quantitatively. The energetic ions were produced by arc-discharge in nitrogen and argon atmosphere. The arc-discharge induced chemical reactions of the biomolecule in aqueous solution were detected and analyzed by means of UV-Vis absorption, fluorescence, Fourier transformation infrared (FTIR) spectroscopy and high performance liquid chromatography (HPLC). Based on the multiple spectroscopic approach, the damage can be evaluated in a more reliable and convenient way. The fluorescence analysis in this case appears to be a more direct indicator for the assessment of damage, where it reveals that the damage increases with the irradiation time exponentially. On the contrary, the 'plateau region' or 'saddle-shape' apparently shown both in our rough absorption analysis and ninhydrin reaction test, similar to the previously reported feature of the dose effect for low-energy-ion induced damage, may be just a consequence with varied reactions and processes involved at different stages. This work thus demonstrated that application of appropriate combination of spectroscopic tools can effectively dissect the diversity of the radiolysis reaction system and assess the biomolecular damage properly.

  3. Optical and structural properties of colloidal zirconia nanoparticles prepared by arc discharge in liquid

    Science.gov (United States)

    Peymani forooshani, Reza; Poursalehi, Reza; Yourdkhani, Amin

    2018-01-01

    Zirconia is one of the important ceramic materials with unique properties such as high melting point, high ionic conductivity, high mechanical properties and low thermal conductivity. Therefore, zirconia is one of the useful materials in refractories, thermal barriers, cutting tools, oxygen sensors electrolytes, catalysis, catalyst supports and solid oxide fuel cells. Recently, direct current (DC) arc discharge is extensively employed to synthesis of metal oxide nanostructures in liquid environments. The aim of this work is the synthesis of colloidal zirconia nanoparticles by DC arc discharge method in water as a medium. Arc discharge was ignited between two pure zirconium electrodes in water. Optical and structural properties of prepared colloidal nanoparticles were investigated. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and UV-visible spectroscopy, were employed for characterization of particle size, morphology, crystal structure and optical properties, respectively. SEM images demonstrate that the nanoparticles are spherical in shape with an average size lower than 38 nm. The XRD patterns of the nanoparticles were consistent with tetragonal and monoclinic zirconia crystal structures. The optical transmission spectra of the colloidal solution show optical characteristic of zirconia nanoparticles as a wide band gap semiconductor with no absorption peak in visible wavelength with the considerable amount of oxygen deficiency. Oxidation of colloidal nanoparticles in water could be explained via reaction with either dissociated oxygen from water in hot plasma region or with dissolved oxygen in water. The results provide a simple and flexible method for preparation of zirconia nanoparticles with a capability of mass production without environmental footprints.

  4. Coagulation of carbon nanoparticles in the acoustic field in the vicinity of the arc discharge

    Science.gov (United States)

    Shneider, Mikhail

    2016-09-01

    An arc discharge produced in a background inert gase between graphite electrodes is one of the popular methods of nanoparticle synthesis. Nanoparticles and microscopic soot particles are produced in the peripheral region of arc. Intensive soot generation significantly reduces the efficiency of the arc as the technological process for production of fullerenes and other nanoparticles. Experimental studies have shown that exposure of peripheral region of the arc to intense ultrasound leads to a noticeable increase in the efficiency of the nanoparticle synthesis and reduces the soot yield (see, e.g.), because ultrasound causes coagulation of soot particles and decrease of their concentration without affecting the nanoparticles. The paper presents theoretical study of the threshold for the ultrasound intensity required for the coagulation as a function of particle sizes and charge, and background gas parameters. The charge acquired in a thermionic emission, as a result of particles heating by radiation from the arc, is calculated self-consistently. I would like to thank Dr. Yevgeny Raitses, Dr. Igor Kaganovich, and Mr. James Mitrani for their interest in this work and fruitful discussions. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  5. MgB{sub 2} superconducting thin films sequentially fabricated using DC magnetron sputtering and thermionic vacuum arc method

    Energy Technology Data Exchange (ETDEWEB)

    Okur, S. [Physics Department, Izmir Institute of Technology (Turkey)], E-mail: salihokur@iyte.edu.tr; Kalkanci, M. [Material Science Program, Izmir Institute of Technology (Turkey); Pat, S.; Ekem, N.; Akan, T. [Physics Department, Osmangazi University (Turkey); Balbag, Z. [Department of Science and Mathematics Education, Osmangazi University (Turkey); Musa, G. [Plasma and Radiation, National Institute for Physics of Laser (Romania); Tanoglu, M. [Mechanical Engineering Department, Izmir Institute of Technology (Turkey)

    2007-11-01

    In this work, we discuss fabrication and characterization of MgB{sub 2} thin films obtained by sequential deposition and annealing of sandwich like Mg/B/Mg thin films on glass substrates. Mg and B films were prepared using DC magnetron sputtering and thermionic vacuum arc techniques, respectively. The MgB{sub 2} thin films showed superconducting critical transition at 33 K after annealing at 650 deg. C.

  6. Flash vacuum-ultraviolet source utilizing a surface-discharge substrate

    Science.gov (United States)

    Sagae, Michiaki; Sato, Eiichi; Shikoda, Arimitsu; Oizumi, Teiji; Hayasi, Yasuomi; Shoji, Tetsuo; Shishido, Koro; Tamakawa, Yoshiharu; Yanagisawa, Toru

    1993-01-01

    The fundamental studies for the flash vacuum-ultraviolet (VUV) source utilizing a surface- discharge substrate are described. This flash VUV source consists of the following essential components: a high-voltage power supply, a polarity-inversion-type high-voltage pulser with a condenser capacity of 14.3 nF, an oil diffusion pump, and a flash VUV chamber with a glass body. The VUV chamber employed a surface-discharge ferrite substrate that's pattern was formed by means of the copper vacuum evaporation and was connected to an oil diffusion pump with a pressure of 1.3 X 10-3 Pa. The combined ceramic condenser in the pulser was charged from 10 to 30 kV by a power supply, and the electric charges in the condenser were discharged to the radiation chamber after closing a gap switch. Then the flash VUV rays were generated. The maximum values of the cathode voltage and the tube current were about -21 kV and 1.7 kA, respectively. The VUV outputs were measured by a combination of a plastic scintillator and a photomultiplier. The pulse durations of the VUV rays were nearly equivalent to the durations of the damped oscillations of the voltage and current, and their values were about 10 microsecond(s) .

  7. Synthesis and characteristics of Ag/Pt bimetallic nanocomposites by arc-discharge solution plasma processing.

    Science.gov (United States)

    Pootawang, Panuphong; Saito, Nagahiro; Takai, Osamu; Lee, Sang-Yul

    2012-10-05

    Arc discharge in solution, generated by applying a high voltage of unipolar pulsed dc to electrodes of Ag and Pt, was used as a method to form Ag/Pt bimetallic nanocomposites via electrode erosion by the effects of the electric arc at the cathode (Ag rod) and the sputtering at the anode (Pt rod). Ag/Pt bimetallic nanocomposites were formed as colloidal particles dispersed in solution via the reduction of hydrogen radicals generated during discharge without the addition of chemical precursor or reducing agent. At a discharge time of 30 s, the fine bimetallic nanoparticles with a mean particle size of approximately 5 nm were observed by transmission electron microscopy (TEM). With increasing discharge time, the bimetallic nanoparticle size tended to increase by forming an agglomeration. The presence of the relatively small amount of Pt dispersed in the Ag matrix could be observed by the analytical mapping mode of energy-dispersive x-ray spectroscopy and high-resolution TEM. This demonstrated that the synthesized particle was in the form of a nanocomposite. No contamination of other chemical substances was detected by x-ray photoelectron spectroscopy. Hence, solution plasma could be a clean and simple process to effectively synthesize Ag/Pt bimetallic nanocomposites and it is expected to be widely applicable in the preparation of several types of nanoparticle.

  8. Experimental analysis on the effects of DC arc discharges at various flow regimes

    Science.gov (United States)

    Bianchi, G.; Saracoglu, B. H.; Paniagua, G.; Regert, T.

    2015-03-01

    This paper addresses the control of the boundary layer on a compression ramp by means of DC electrical arc discharges. The development and realization of the control system are first described and then assessed in the wind tunnel. The objective of the research was to control the supersonic flow using the minimum amount of energy. The array of electrodes was located at the base of a ramp, where a low momentum flow develops. The electrical discharge was generated by a custom designed electronic facility based on high-voltage ignition coils. The slanted tungsten electrodes were insulated by mounting them in a ceramic support. The discharge evolution was studied through high-speed flow visualizations, while electrical measurements at the high-voltage section of the circuitry allowed to estimate the energy release. The development of a high-speed short exposure Schlieren imaging technique, based on a very short duration laser pulse illumination and a double shot CCD camera, allowed to observe the macroscopic effects associated with the arc establishment between the electrodes (glow, sound wave and heat release). Due to the long residence time, the thermal perturbation spread along the streamwise direction. Cross correlation of Schlieren images with short time separation revealed that in supersonic conditions, the discharges led to an overall acceleration of the flow field underneath the oblique shock wave.

  9. Investigation on the properties of nano copper matrix composite via vacuum arc melting method

    Science.gov (United States)

    Liu, Yi; Leng, Jinfeng; Wu, Qirui; Zhang, Shaochen; Teng, Xinying

    2017-10-01

    Copper and copper matrix composites (CMCs) are widely used as electrical contact materials in electrical switch systems due to their excellent electrical properties. Graphene has great mechanical, physical and electrical properties, which is competent as an attractive reinforcing material for fabricating CMCs. Therefore, graphene was added to CMCs to improve the mechanical properties. In this study, graphene-reinforced copper matrix composites (Gr/Cu composites) were obtained. The xGr/Cu (x  =  0, 0.1, 0.3 and 0.5 wt.%) composites were fabricated via the vacuum arc melting method and compared the performance of them. The mechanical properties and electrical properties were obtained by measuring the hardness and conductivity. The microstructure of Gr/Cu composites was observed by optical microscopy (OM) and scanning electron microscopy (SEM). With the addition of graphene from 0 wt.% to 0.5 wt.%, the densities of materials decreased from 97.0% to 95.7%. With the increasing of graphene content, the hardness of composites increased at beginning and then decreased. In this range of adding amount, the hardness of 0.3Gr/Cu composite was up to 66.8 HB and increased by 15.4% compared to Al2O3/Cu composites without graphene. With the addition of graphene powder, the international annealing copper standard IACS% of Gr/Cu composites decreased from 86.16 to 69.86. The range of decline and the percentage of decline range are middle and 18.9%, respectively.

  10. Arc-Discharge Synthesis of Iron Encapsulated in Carbon Nanoparticles for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    S. Chaitoglou

    2014-01-01

    Full Text Available The objective of the present work is to improve the protection against the oxidation that usually appears in core@shell nanoparticles. Spherical iron nanoparticles coated with a carbon shell were obtained by a modified arc-discharge reactor, which permits controlling the diameter of the iron core and the carbon shell of the particles. Oxidized iron nanoparticles involve a loss of the magnetic characteristics and also changes in the chemical properties. Our nanoparticles show superparamagnetic behavior and high magnetic saturation owing to the high purity α-Fe of core and to the high core sealing, provided by the carbon shell. A liquid iron precursor was injected in the plasma spot dragged by an inert gas flow. A fixed arc-discharge current of 40 A was used to secure a stable discharge, and several samples were produced at different conditions. Transmission electron microscopy indicated an iron core diameter between 5 and 9 nm. Selected area electron diffraction provided evidences of a highly crystalline and dense iron core. The magnetic properties were studied up to 5 K temperature using a superconducting quantum interference device. The results reveal a superparamagnetic behaviour, a narrow size distribution (σg=1.22, and an average diameter of 6 nm for nanoparticles having a blocking temperature near 40 K.

  11. X-ray spectra of plasma radiation from laser induced low-power vacuum discharge

    Science.gov (United States)

    Romanov, I. V.; Kologrivov, A. A.; Paperny, V. L.; Rupasov, A. A.; Starodub, A. N.

    2018-02-01

    The x-ray spectra of plasma radiation in the wavelength range 30–300 Å are studied. The radiation is emitted from plasma of a vacuum discharge with storage energy less than 30 J that is initiated on an Al or Fe cathode by beam from neodymium laser with a power density up to 1012 W cm‑2. It is shown that both the spectral composition and intensity of radiation of hot micropinch plasma that is formed in the cathodic jet are determined by the set of the discharge and the laser pulse characteristics. By optimizing these characteristics, a mode of the discharge operation is attainable, in which a significant portion of the radiation energy is located in the long-wave band of the quasi-continuum (230–270 Å and 160–200 Å for Al and Fe cathodes, respectively). That makes it possible to treat such a discharge as an intense source of narrow-band soft x-ray radiation.

  12. Growth of metal micro and/or nanoparticles utilizing arc-discharge immersed in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Rebollo P, B.; Gallardo G, G.; Ortega M, N.; Daniel P, G. [Instituto Tecnologico Superior de Irapuato, Km 12.5 Carretera Irapuato-Silao, 36821 Irapuato, Guanajuato (Mexico); Sampedro, M. P.; Zenteno M, B. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria, Ciudad Universitaria, 72590 Puebla, Puebla (Mexico); Bravo B, C. F. [Comision Federal de Electricidad, Laboratorio de Pruebas de Equipos y Materiales, Irapuato, Guanajuato (Mexico); Hernandez C, D. [Universidad Autonoma de Chiapas, Facultad de Ingenieria, 29050 Tuxtla Gutierrez, Chiapas (Mexico); Jimenez S, S., E-mail: mpstraviata@hotmail.com [Instituto Politecnico Nacional, Centro de Investigacion y de Estudios Avanzados, Laboratorio de Investigacion en Materiales, 76230 Santiago de Queretaro, Queretaro (Mexico)

    2014-07-01

    In this paper, we present results on the metal microcrystals and nanoparticles of Al, Cu and Al-Cu composite growth by arc-discharge with the system immersed in distilled water, under different conditions and varying the current from 50 to 150 A with constant voltage (27 V). These structures are characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and UV-Vis spectroscopy. Our results demonstrate that metal micro and nano structures can be prepared at low cost with high quality. (Author)

  13. Synthesis of multiwalled carbon nanotube from different grades of carbon black using arc discharge method

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Neha, E-mail: n4neha31@gmail.com [Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani (India); Sharma, N. N. [Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani (India); Director, School of Automobile, Mechanical & Mechatronics, Manipal University,Jaipur,India (India)

    2016-04-13

    This paper describes the synthesis of nanotube from different grades (Tread * A(non-ASTM), N134,N121,N660 and N330)of carbon black using DC arc discharge method at 40A current for 60sec. Carbon black samples of different grades were procured from industry (Aditya Birla Science and Technology Limited, India). Scanning Electron Micrographs (SEM) of the deposited carbon nanostructures suggests that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.The result formed indicates the N330 grade of carbon black gets converted to MWCNTs (Multiwall Carbon nanotube) as compared to other grades.

  14. Performance of carbon arc-discharge nanotubes to hydrogen energy storage.

    Science.gov (United States)

    Farhat, S; Weinberger, B; Lamari, F D; Izouyar, T; Noe, L; Monthioux, M

    2007-10-01

    Adsorption properties of gram-scale samples of different kind of arc discharge nanotubes were studied, namely: (A) raw collaret collected on the cathode, (B) raw soots collected on the lateral reactor wall, (C) thermally treated soot, and (D) thermally then chemically treated soot. The morphology, structure, and composition of these materials were characterized by SEM, TEM, TGA, and BET. In addition, hydrogen adsorption isotherms were recorded experimentally for A, B, and D samples over the pressure range of 0 to 55 bar at ambient temperature. Our experiments indicated a maximum-yet weak-hydrogen storage at room temperature of approximately 0.13 H2 wt% for the purified product (D).

  15. Discharge coefficient correlations for circular-arc venturi flowmeters at critical /sonic/ flow

    Science.gov (United States)

    Arnberg, B. T.; Britton, C. L.; Seidl, W. F.

    1973-01-01

    Experimental data are analyzed to support theoretical predictions for discharge coefficients in circular-arc venturi flow meters operating in the critical sonic flow regime at throat Reynolds numbers above 150 thousand. The data tend to verify the predicted 0.25% decrease in the discharge coefficient during transition from a laminar to turbulent boundary layer. Four different test gases and three flow measurement facilities were used in the experiments with 17 venturis with throat sizes from 0.15 to 1.37 in. and Beta ratios ranging from 0.014 to 0.25. Recommendations are given as to how the effectiveness of future studies in the field could be improved.

  16. Low-frequency flute instabilities of a hollow cathode arc discharge - Theory and experiment.

    Science.gov (United States)

    Ilic, D. B.; Rognlien, T. D.; Self, S. A.; Crawford, F. W.

    1973-01-01

    The characteristics of two low-frequency electrostatic flute instabilities of a low-pressure hollow cathode arc discharge are reported. Mode I has azimuthal mode number m = 1, and occurs when the radial electric field is negative (directed inward), while mode II has m = - 1 and occurs when the field is positive. The radial electric field is controlled by varying the potential of a secondary anode cylinder located close to the outer discharge radius. A linear perturbation analysis, based on the two-fluid equations, is given for a low-beta, collisionless, cylindrical plasma column, immersed in a uniform axial magnetic field, having a Gaussian density profile and an arbitrary radial electric field profile. Reasonable correlation between theory and experiment is demonstrated for both modes.

  17. Characterization of Ni ferrites powders prepared by plasma arc discharge process

    Science.gov (United States)

    Safari, A.; Gheisari, Kh.; Farbod, M.

    2017-01-01

    The aim of this work was to synthesize a single-phase spinel structure from a mixture of zinc, iron and nickel powders by plasma arc discharge method. A mixture of zinc, iron and nickel powders with the appropriate molar ratio was prepared and formed into a cylindrical shape. The synthesis process was performed in air, oxygen and argon atmospheres with the applied arc current of 400 A and pressure of 1 atm. After establishing an arc between the electrodes, the produced powders were collected and their structure and magnetic properties were examined by XRD and VSM, respectively. ZnO as an impurity was appeared in the as-produced powders owing to the high reactivity of zinc atoms, preventing the formation of Ni-Zn ferrite. A pure spinel structure with the highest saturation magnetization (43.8 emu/g) was observed as zinc powders removed completely from the initial mixture. Morphological evaluations using field emission scanning electron microscopy showed that the mean size of fabricated nanoparticles was in the range 100-200 nm and was dependent on the production conditions.

  18. Synthesis of graphene sheets with high electrical conductivity and good thermal stability by hydrogen arc discharge exfoliation.

    Science.gov (United States)

    Wu, Zhong-Shuai; Ren, Wencai; Gao, Libo; Zhao, Jinping; Chen, Zongping; Liu, Bilu; Tang, Daiming; Yu, Bing; Jiang, Chuanbin; Cheng, Hui-Ming

    2009-02-24

    We developed a hydrogen arc discharge exfoliation method for the synthesis of graphene sheets (GSs) with excellent electrical conductivity and good thermal stability from graphite oxide (GO), in combination with solution-phase dispersion and centrifugation techniques. It was found that efficient exfoliation and considerable deoxygenation of GO, and defect elimination and healing of exfoliated graphite can be simultaneously achieved during the hydrogen arc discharge exfoliation process. The GSs obtained by hydrogen arc discharge exfoliation exhibit a high electrical conductivity of approximately 2 x 10(3) S/cm and high thermal stability with oxidization resistance temperature of 601 degrees C, which are much better than those prepared by argon arc discharge exfoliation (approximately 2 x 10(2) S/cm, 525 degrees C) and by conventional thermal exfoliation (approximately 80 S/cm, 507 degrees C) with the same starting GO. These results demonstrate that this hydrogen arc discharge exfoliation method is a good approach for the preparation of GSs with a good quality.

  19. Copper induced hollow carbon nanospheres by arc discharge method: controlled synthesis and formation mechanism

    Science.gov (United States)

    Hu, Rui; Alexandru Ciolan, Mihai; Wang, Xiangke; Nagatsu, Masaaki

    2016-08-01

    Hollow carbon nanospheres with controlled morphologies were synthesized via the copper-carbon direct current arc discharge method by alternating the concentrations of methane in the reactant gas mixture. A self-healing process to keep the structural integrity of encapsulated graphitic shells was evolved gradually by adding methane gas from 0% to 20%. The outer part of the coated layers expanded and hollow nanospheres grew to be large fluffy ones with high methane concentrations from 30% to 50%. A self-repairing function by the reattachment of broken graphitic layers initiated from near-electrode space to distance was also distinctly exhibited. By comparing several comparable metals (e.g. copper, silver, gold, zinc, iron and nickel)-carbon arc discharge products, a catalytic carbon-encapsulation mechanism combined with a core-escaping process has been proposed. Specifically, on the basis of the experimental results, copper could be applied as a unique model for both the catalysis of graphitic encapsulation and as an adequate template for the formation of hollow nanostructures.

  20. Absolute calibration of a hydrogen discharge lamp in the vacuum ultraviolet

    Science.gov (United States)

    Nealy, J. E.

    1975-01-01

    A low-pressure hydrogen discharge lamp was calibrated for radiant intensity in the vacuum ultraviolet spectral region on an absolute basis and was employed as a laboratory standard source in spectrograph calibrations. This calibration was accomplished through the use of a standard photodiode detector obtained from the National Bureau of Standards together with onsite measurements of spectral properties of optical components used. The stability of the light source for use in the calibration of vacuum ultraviolet spectrographs and optical systems was investigated and found to be amenable to laboratory applications. The lamp was studied for a range of operating parameters; the results indicate that with appropriate peripheral instrumentation, the light source can be used as a secondary laboratory standard source when operated under preset controlled conditions. Absolute intensity measurements were recorded for the wavelengths 127.7, 158.0, 177.5, and 195.0 nm for a time period of over 1 month, and the measurements were found to be repeatable to within 11 percent.

  1. Effect of magnetic field on carbon nanotubes and graphene structure synthesized at low pressure via arc discharge process

    Science.gov (United States)

    Roslan, M. S.; Chaudary, K. T.; Haider, Z.; Zin, A. F. M.; Ali, J.

    2017-03-01

    Carbon nanomaterials have attracted vast attention due to the rising demand for various nanotechnology applications. The possibility of preparing multi-walled carbon nanotube (MWCNT) and graphene on large scale are demonstrated using direct current arc discharge with transverse magnetic field effect at low ambient pressure. In this work, we study, the effect of external transverse magnetic effect on structural perfection of graphene and multi-walled carbon nanotube. High quality carbon-nanotube were synthesized by arc discharge plasma in Hydrogen ambient at pressure 1 mbar in presence of external transverse magnetic field. The synthesized nanomaterials were characterized by electron microscopy, XRD and Raman Spectroscopy. A significant increase in the quantity and quality of carbon nanotube and graphene in the presence of transverse magnetic field during arc discharge process.

  2. Generation of metallic arc spectrum of pumping discharge of XeCl laser; XeCl ekishima laser reiki hoden ni okeru arc iko to kinzoku supekutoru no hassei

    Energy Technology Data Exchange (ETDEWEB)

    Koike, H.; Yukimura, K. [Doshisha University, Kyoto (Japan)

    1997-12-20

    An arc generation of a long-pulse spiker-sustainer excimer laser with about 250ns of pulse width , is discussed by using time-varying spectroscopic method. First arcing occurs during a main discharge for laser excitation and shows XeII spectrum, while a glow-like discharge represents only XeI spectrum, the metallic spectrum such as Nil caused by vaporization of electrode material begins to appear just after the termination of the main discharge. Second arcing occurs after about 2{mu}s, which brings strong intensity of Nil spectrum. It means that the reignition arc might be produced in a metallic vapor that appears during the main discharge. Accordingly, it is concluded that the reignition arc is inherently metallic, which is different from the main arc with rare gas plasma. 9 refs., 9 figs.

  3. Post-arc current simulation based on measurement in vacuum circuit breaker with a one-dimensional particle-in-cell model

    Science.gov (United States)

    Jia, Shenli; Mo, Yongpeng; Shi, Zongqian; Li, Junliang; Wang, Lijun

    2017-10-01

    The post-arc dielectric recovery process has a decisive effect on the current interruption performance in a vacuum circuit breaker. The dissipation of residual plasma at the moment of current zero under the transient recovery voltage, which is the first stage of the post-arc dielectric recovery process and forms the post-arc current, has attracted many concerns. A one-dimensional particle-in-cell model is developed to simulate the measured post-arc current in the vacuum circuit breaker in this paper. At first, the parameters of the residual plasma are estimated roughly by the waveform of the post-arc current which is taken from measurements. After that, different components of the post-arc current, which are formed by the movement of charged particles in the residual plasma, are discussed. Then, the residual plasma density is adjusted according to the proportion of electrons and ions absorbed by the post-arc anode derived from the particle-in-cell simulation. After this adjustment, the post-arc current waveform obtained from the simulation is closer to that obtained from measurements.

  4. Development of High Efficiency Versatile Arc Discharge Ion Source (VADIS) at CERN Isolde

    CERN Document Server

    Penescu, L; Lettry, J; Stora, T

    2010-01-01

    We report here recent developments of Forced Electron Beam Impact Arc Discharge (FEBIAD) ion sources at CERN-ISOLDE. As a result of the propositions to improve the ionization efficiency, two FEBIAD prototypes have been produced and successfully tested in 2008. Off-line studies showed that the 1+ ionization efficiencies for noble gases are 5 to 20 times larger than with the standard ISOLDE FEBIAD ion sources, and reach 60% for Radon, which allowed the identification at ISOLDE of 229Rn, an isotope that had never previously been observed in the laboratory. A factor 3 increase is also expected for the ionization efficiency of the other elements. The experimental and theoretical methodology is presented. The theoretical model which gives precise insights on the processes affecting the ionization is used to design optimal sources for the different chemical classes of the produced isotopes, as already demonstrated for noble gases.

  5. Measurements of 3D slip velocities and plasma column lengths of a gliding arc discharge

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2015-01-01

    A non-thermal gliding arc discharge was generated at atmospheric pressure in an air flow. The dynamics of the plasma column and tracer particles were recorded using two synchronized high-speed cameras. Whereas the data analysis for such systems has previously been performed in 2D (analyzing...... the single camera image), we provide here a 3D data analysis that includes 3D reconstructions of the plasma column and 3D particle tracking velocimetry based on discrete tomography methods. The 3D analysis, in particular, the determination of the 3D slip velocity between the plasma column and the gas flow......, gives more realistic insight into the convection cooling process. Additionally, with the determination of the 3D slip velocity and the 3D length of the plasma column, we give more accurate estimates for the drag force, the electric field strength, the power per unit length, and the radius...

  6. Study of Ag and Au Nanoparticles Synthesized by Arc Discharge in Deionized Water

    Directory of Open Access Journals (Sweden)

    Der-Chi Tien

    2010-01-01

    Full Text Available The paper presents a study of Ag and Au nanofluids synthesized by the arc discharge method (ADM in deionized water. The metallic Ag nanoparticle (Ag0 and ionic Ag (Ag+ have played an important role in the battle against germs which are becoming more drug-resistant every year. Our study indicates that Ag nanoparticle suspension (SNPS fabricated by using ADM without added surfactants exclusively contains the metallic Ag nanoparticle and ionic Ag. Besides that, the ADM in deionized water has also been employed for the fabrication process of Au nanoparticles. The experimental results indicate that the prepared Ag nanoparticles can react with the dissolved H2CO3 in deionized water, leading to the formation of Ag2CO3. Significantly different to Ag, the prepared Au nanoparticles with their surfaces bonded by oxygen are suspended in deionized water by the formation of hydrogen bonded with the neighboring water molecules.

  7. Complex structure of the carbon arc discharge for synthesis of nanotubes

    Science.gov (United States)

    Vekselman, V.; Feurer, M.; Huang, T.; Stratton, B.; Raitses, Y.

    2017-06-01

    Comprehensive non-invasive spectroscopic techniques and electrical measurements of the carbon arc revealed two distinguishable plasma synthesis regions in the radial direction normal to the arc axis. These regions, which are defined as the arc core and the arc periphery, are shown to have very different compositions of carbon species with different densities and temperatures. The colder arc periphery is dominated by carbon diatomic molecules (C2), which are in the minority in the composition of the hot arc core. These differences are due to a highly non-uniform distribution of the arc current, which is mainly conducted through the arc core populated with carbon atoms and ions. Therefore, the ablation of the graphite anode is governed by the arc core, while the formation of carbon molecules occurs in the colder arc periphery. This result is consistent with previous predictions that the plasma environment in the arc periphery is suitable for synthesis of carbon nanotubes.

  8. In-situ synthesis of palladium nanoparticles-filled carbon nanotubes using arc-discharge in solution

    NARCIS (Netherlands)

    Bera, D; Kuiry, SC; McCutchen, M; Kruize, A; Heinrich, H; Meyyappan, M; Seal, S

    2004-01-01

    A unique, simple, inexpensive and one-step synthesis route of carbon nanotubes (CNT) supported palladium nanoparticles using a simplified arc-discharge in solution is reported. Palladium nanoparticles with 3 nm diameter were found to form during reduction of palladium tetra-chloro-square-planar

  9. The application of a non-thermal plasma generated by gas-liquid gliding arc discharge in sterilization

    Science.gov (United States)

    Du, Chang Ming; Wang, Jing; Zhang, Lu; Xia Li, Hong; Liu, Hui; Xiong, Ya

    2012-01-01

    Gliding arc discharge has been investigated in recent years as an innovative physicochemical technique for contaminated water treatment at atmospheric pressure and ambient temperature. In this study we tested a gas-liquid gliding arc discharge reactor, the bacterial suspension of which was treated circularly. When the bacterial suspension was passed through the electrodes and circulated at defined flow rates, almost 100% of the bacteria were killed in less than 3.0 min. Experimental results showed that it is possible to achieve an abatement of 7.0 decimal logarithm units within only 30 s. Circulation flow rates and types of feeding gas caused a certain impact on bacteria inactivation, but the influences are not obvious. So, under the promise of sterilization effect, industrial applications can select their appropriate operating conditions. All inactivation curves presented the same three-phase profile showing an apparent sterilization effect. Analysis of the scanning electron microscope images of bacterial cells supports the speculation that the gas-liquid gliding arc discharge plasma is acting under various mechanisms driven essentially by oxidation and the effect of electric field. These results enhance the possibility of applying gas-liquid gliding arc discharge decontamination systems to disinfect bacterial-contaminated water. Furthermore, correlational research indicates the potential applications of this technology in rapid sterilization of medical devices, spacecraft and food.

  10. Arc Discharge Synthesis and Photoluminescence of 3D Feather-like AlN Nanostructures

    Science.gov (United States)

    Yang, Sl; Gao, Rs; Niu, Pl; Zou, Zy; Yu, Rh

    2011-12-01

    A complex three-dimensional (3D) feather-like AlN nanostructure was synthesized by a direct reaction of high-purity Al granules with nitrogen using an arc discharge method. By adjusting the discharge time, a coral-like nanostructure, which evolved from the feather-like nanostructure, has also been observed. The novel 3D feather-like AlN nanostructure has a hierarchical dendritic structure, which means that the angle between the trunk stem and its branch is always about 30° in any part of the structure. The fine branches on the surface of the feather-like nanostructure have shown a uniform fish scale shape, which are about 100 nm long, 10 nm thick and several tens of nanometers in width. An alternate growth model has been proposed to explain the novel nanostructure. The spectrum of the feather-like products shows a strong blue emission band centered at 438 nm (2.84 eV), which indicates their potential application as blue light-emitting diodes.

  11. Experimental and numerical study of shock wave propagation in water generated by pulsed arc electrohydraulic discharges

    Science.gov (United States)

    Chen, Wen; Maurel, Olivier; La Borderie, Christian; Reess, Thierry; De Ferron, Antoine; Matallah, Mohammed; Pijaudier-Cabot, Gilles; Jacques, Antoine; Rey-Bethbeder, Frank

    2014-05-01

    The objective of this study is to simulate the propagation of the shock wave in water due to an explosion. The study is part of a global research program on the development of an alternative stimulation technique to conventional hydraulic fracturing in tight gas reservoirs aimed at inducing a distributed state of microcracking of rocks instead of localized fracture. We consider the possibility of increasing the permeability of rocks with dynamic blasts. The blast is a shock wave generated in water by pulsed arc electrohydraulic discharges. The amplitude of these shock waves is prescribed by the electrohydraulic discharges which generate high pressures of several kilobars within microseconds. A simplified method has been used to simulate the injected electrical energy as augmentation of enthalpy in water locally. The finite element code EUROPLEXUS is used to perform fluid fast dynamic computation. The predicted pressure is consistent with the experimental results. In addition, shock wave propagation characteristics predicted with simulation can be valuable reference for design of underwater structural elements and engineering of underwater explosion.

  12. Refusion of zircaloy scraps by VAR (vacuum arc remelting): preliminary results; Fusao de cavacos de zircaloy por VAR: resultados preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, L.A.T.; Mucsi, C.S.; Sato, I.M.; Rossi, J.L.; Martinez, L.G., E-mail: lgallego@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Correa, H.P.S. [Universidade Federal do Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil); Orlando, M.T.D. [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil)

    2010-07-01

    Fuel elements and structural components of the core of PWR nuclear reactors are made in zirconium alloys known as Zircaloy. Machining chips and shavings resulting from the manufacturing of these components can not be discarded as scrap, once these alloys are strategic materials for the nuclear area, have high costs and are not produced in Brazil on an industrial bases and, consequently, are imported for the manufacture of nuclear fuel. The reuse of Zircaloy chips has economic, strategic and environmental aspects. In this work is proposed a process for recycling Zircaloy scraps using a VAR (vacuum arc remelting) furnace in order to obtain ingots suitable for the manufacture of components of the reactors. The ingots obtained are being studied in order to verify the influence of processing on composition and microstructure of the remelted material. In this work are presented preliminary results of the composition of obtained ingots compared to start material and the resulting microstructure. (author)

  13. Investigation on the physical properties of C-doped ZnO thin films deposited by the thermionic vacuum arc

    Science.gov (United States)

    Mohammadigharehbagh, Reza; Özen, Soner; Hakan Yudar, H.; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan

    2017-01-01

    The aim of this study is to determine some physical properties of C-doped ZnO coated on a glass substrate by using the thermionic vacuum arc method. The produced C-doped ZnO thin film is characterized by using several analysis techniques. The produced thin film has a cubic crystal structure, high transmittance in the visible region, symmetrical surface distribution, and optical band gap energy of 3.34 eV. According to the XRD analysis of the produced thin film, it is a fullerene (C60)-doped polycrystalline ZnO. Hardness value and Young's modulus value were determined as 8 GPa and 140 GPa, respectively. These physical properties are adequate for future transparent electrode applications.

  14. Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

    Directory of Open Access Journals (Sweden)

    Angeliki Lekatou

    2016-02-01

    Full Text Available Hypereutectic Al-Co alloys of various Co contents (7–20 weight % (wt.% Co were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co to coarse primary Al9Co2 predominance (20 wt.% Co. Co dissolution in Al far exceeded the negligible equilibrium solubility of Co in Al; however, it was hardly uniform. By increasing the cobalt content, the fraction and coarseness of Al9Co2, the content of Co dissolved in the Al matrix, and the hardness and porosity of the alloy increased. All alloys exhibited similar corrosion behavior in 3.5 wt.% NaCl with high resistance to localized corrosion. Al-7 wt.% Co showed slightly superior corrosion resistance than the other compositions in terms of relatively low corrosion rate, relatively low passivation current density and scarcity of stress corrosion cracking indications. All Al-Co compositions demonstrated substantially higher resistance to localized corrosion than commercially pure Al produced by casting, cold rolling and arc melting. A corrosion mechanism was formulated. Surface films were identified.

  15. The Formation of Composite Ti-Al-N Coatings Using Filtered Vacuum Arc Deposition with Separate Cathodes

    Directory of Open Access Journals (Sweden)

    Ivan A. Shulepov

    2017-11-01

    Full Text Available Ti-Al-N coatings were deposited on high-speed steel substrates by filtered vacuum arc deposition (FVAD during evaporation of aluminum and titanium cathodes. Distribution of elements, phase composition, and mechanical properties of Ti-Al-N coatings were investigated using Auger electron spectroscopy (AES, X-ray diffraction (XRD, transmission electron microscopy (TEM and nanoindentation, respectively. Additionally, tribological tests and scratch tests of the coatings were performed. The stoichiometry of the coating changes from Ti0.6Al0.4N to Ti0.48Al0.52N with increasing aluminum arc current from 70 A to 90 A, respectively. XRD and TEM showed only face-centered cubic Ti-Al-N phase with preferred orientation of the crystallites in (220 direction with respect to the sample normal and without precipitates of AlN or intermetallics inside the coatings. Incorporation of Al into the TiN lattice caused shifting of the (220 reflex to a higher 2θ angle with increasing Al content. Low content and size of microdroplets were obtained using coaxial plasma filters, which provides good mechanical and tribological properties of the coatings. The highest value of microhardness (36 GPa and the best wear-resistance were achieved for the coating with higher Al content, thus for Ti0.48Al0.52N. These coatings exhibit good adhesive properties up to 30 N load in the scratch tests.

  16. XPS STRUCTURE ANALYSIS OF TiN/TiC BILAYERS PRODUCED BY PULSED VACUUM ARC DISCHARGE

    Directory of Open Access Journals (Sweden)

    ELISABETH RESTREPO PARRA

    2010-01-01

    Full Text Available se crecieron bicapas de TiN/TiC sobre sustratos de acero inoxidable 304 usando un sistema de deposición física de vapor asistida por plasma en forma de arco pulsado a dos diferentes temperaturas del sustrato (50º C y150º C. Para el análisis de la composición química se empleó la técnica de la espectroscopía de fotoelectrones de rayos X (XPS. Se observó el comportamiento de las líneas Ti2p, N1s y C1s. Los análisis de energía de enlace confirmaron la conformación de TiN y TiC. Los picos C1s y Ti2p sufrieron un corrimiento a medida que se incrementó el tiempo de esputtering, revelando contaminación debido a la presencia de hidrocarburos. Además, los perfiles de profundidad de las bicapas de TiN/TiC mostraron que las películas crecidas a una temperatura de 150 ° C tienen una capa de TiN más gruesa que las muestras crecidas a 50º C. El nitrógeno se difundió en la capa de TiC y el carbón en la capa de TiN para ambas temperaturas.

  17. 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.

  18. Laser-induced incandescence (LII) diagnostic for in situ monitoring of nanoparticle synthesis in a high-pressure arc discharge

    Science.gov (United States)

    Yatom, Shurik; Vekselman, Vladislav; Mitrani, James; Stratton, Brentley; Raitses, Yevgeny; LaboratoryPlasma Nanosynthesis Team

    2016-10-01

    A DC arc discharge is commonly used for synthesis of carbon nanoparticles, including buckyballs, carbon nanotubes, and graphene flakes. In this work we show the first results of nanoparticles monitored during the arc discharge. The graphite electrode is vaporized by high current (60 A) in a buffer Helium gas leading to nanoparticle synthesis in a low temperature plasma. The arc was shown to oscillate, which can possibly influence the nano-synthesis. To visualize the nanoparticles in-situ we employ the LII technique. The nanoparticles with radii >50 nm, emerging from the arc area are heated with a short laser pulse and incandesce. The resulting radiation is captured with an ICCD camera, showing the location of the generated nanoparticles. The images of incandescence are studied together with temporally synchronized fast-framing imaging of C2 emission, to connect the dynamics of arc instabilities, C2 molecules concentration and nanoparticles. The time-resolved incandescence signal is analyzed with combination of ex-situ measurements of the synthesized nanoparticles and LII modeling, to provide the size distribution of produced nanoparticles. This work was supported by US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  19. Test of the beam effect on vacuum arc occurrence in a high-gradient accelerating structure for the CLIC project

    CERN Document Server

    AUTHOR|(CDS)2130409; Gagliardi, Martino

    A new generation of lepton colliders capable of reaching TeV energies is pres- ently under development, and to succeed in this task it is necessary to show that the technology for such a machine is available. The Compact Linear Collider (CLIC) is a possible design option among the future lepton collider projects. It consists of two normal-conducting linacs. Accelerating structures with a gradient of the order of 100 MV/m are necessary to reach the required high energies within a reasonable machine length. One of the strictest require- ments for such accelerating structures is a relatively low occurrence of vacuum arcs. CLIC prototype structures have been tested in the past, but only in absence of beam. In order to proof the feasibility of the high gradient technology for building a functional collider, it is necessary to understand the effect of the beam presence on the vacuum breakdowns. Tests of this type have never been performed previously. The main goal of this work is to provide a first measurement of t...

  20. The Study of Complex (Ti, Zr, Cs) Nanopowder Influencing the Effective Ionization Potential of Arc Discharge When Mma Welding

    Science.gov (United States)

    Sapozhkov, S. B.; Burakova, E. M.

    2016-08-01

    Strength is one of the most important characteristics of a weld joint. Mechanical properties of a weld metal can be improved in a variety of ways. One of the possibilities is to add a nanopowder to the weld metal. Authors of the paper suggest changing the production process of MMA welding electrodes via adding nanopowder Ti, Zr, Cs to electrode components through liquid glass. Theoretical research into the nanopowder influence on the effective ionization potential (Ueff) of welding arc discharge is also necessitated. These measures support arcing stability, improve strength of a weld joint, as the consequence, ensure quality enhancing of a weld joint and the structure on the whole.

  1. Synthesis and Characterization of Boron Nitride and Molybdenum Nitride Multi-Walled Nanotubes Using Liquid Plasma Arc Discharge

    Science.gov (United States)

    Holliday, Roger; Falvo, Mike; Washburn, Sean; Superfine, Rich

    2001-11-01

    We will present results on synthesis of Boron Nitride and Molybdenum Nitride nanotubes using the liquid nitrogen plasma-arc discharge method previously reported for carbon nanotubes synthesis[1]. We created a 60-100A/20-40V arc across electrodes of Hafnium Boride and Molybdenum Sulfide in a liquid nitrogen atmosphere. Nanotube geometry, nano-structure and composition characterization using TEM and EDAX will be presented. Progress in electronic and mechanical characterization as well as our incorporation of these nanotubes in to novel NEMS devices will be discussed. [1] M. Ishigami, J. Cummings, A. Zettl, S. Chen. Chemical Physical Letters 319 (2000) 457-459.

  2. Discovery of ionic silver in silver nanoparticle suspension fabricated by arc discharge method

    Energy Technology Data Exchange (ETDEWEB)

    Tien, D.-C. [Graduate Institute of Mechanical and Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China)], E-mail: s3408508@ntut.edu.tw; Tseng, K.-H.; Liao, C.-Y.; Huang, J.-C. [Department of Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China); Tsung, T.-T. [Graduate Institute of Mechanical and Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China)

    2008-09-08

    As a result of mankind's over-reliance on antibiotics, germs are becoming more drug-resistant every year. The gradual but inexorable decline in the efficacy of traditional antibiotics is forcing scientists and doctors to search for new weapons in the fight against germs. Metallic silver nanoparticle (Ag{sup 0}) and ionic silver (Ag{sup +}) are the future of the post-antibiotic era, with the latter playing perhaps the central role in this fight. Using the arc discharge method (ADM), our research has allowed us to fabricate silver nanoparticle suspension (SNPS) in deionized water with no added surfactants. Most related research in this field is confined to explore the composition of nanoparticle, ignoring ions. However, we aim to identify and measure the proportion of ionic silver in ADM-SNPS, using conductivity meters, centrifuges, titrator, and atomic absorption spectrophotometer (AA). The results of our experiments show that SNPS fabricated by means of ADM with no added surfactants contains metallic silver nanoparticle and ionic silver. The fabrication consumes silver rods at a rate of 100 mg/min, yielding metallic silver nanoparticle and ionic silver with concentrations of approximately 11 ppm and 19 ppm, respectively.

  3. Electric field formation in three different plasmas: A fusion reactor, arc discharge, and the ionosphere

    Science.gov (United States)

    Lee, Kwan Chul

    2017-11-01

    Three examples of electric field formation in the plasma are analyzed based on a new mechanism driven by ion-neutral collisions. The Gyro-Center Shift analysis uses the iteration of three equations including perpendicular current induced by the momentum exchange between ions and neutrals when there is asymmetry over the gyro-motion. This method includes non-zero divergence of current that leads the solution of time dependent state. The first example is radial electric field formation at the boundary of the nuclear fusion device, which is a key factor in the high-confinement mode operation of future fusion reactors. The second example is the reversed rotation of the arc discharge cathode spot, which has been a mysterious subject for more than one hundred years. The third example is electric field formations in the earth's ionosphere, which are important components of the equatorial electrojet and black aurora. The use of one method that explains various examples from different plasmas is reported, along with a discussion of the applications.

  4. Quantitative evaluation of fiber fuse initiation with exposure to arc discharge provided by a fusion splicer.

    Science.gov (United States)

    Todoroki, Shin-Ichi

    2016-05-03

    The optical communication industry and power-over-fiber applications face a dilemma as a result of the expanding demand of light power delivery and the potential risks of high-power light manipulation including the fiber fuse phenomenon, a continuous destruction of the fiber core pumped by the propagating light and triggered by a heat-induced strong absorption of silica glass. However, we have limited knowledge on its initiation process in the viewpoint of energy flow in the reactive area. Therefore, the conditions required for a fiber fuse initiation in standard single-mode fibers were determined quantitatively, namely the power of a 1480 nm fiber laser and the arc discharge intensity provided by a fusion splicer for one second as an outer heat source. Systematic investigation on the energy flow balance between these energy sources revealed that the initiation process consists of two steps; the generation of a precursor at the heated spot and the transition to a stable fiber fuse. The latter step needs a certain degree of heat accumulation at the core where waveguide deformation is ongoing competitively. This method is useful for comparing the tolerance to fiber fuse initiation among various fibers with a fixed energy amount that was not noticed before.

  5. The modelling of the cathode sheath of an electrical arc in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Rossignol, J [Laboratoire de Recherches sur la Reactivite des Solides, UMR 5613 CNRS, Universite de Bourgogne 21078 Dijon (France); Clain, S [Laboratoire de Mathematiques Appliquees, UMR 6620 CNRS, Universite Blaise Pascal, 63177 Aubiere (France); Abbaoui, M [Laboratoire Arc Electrique et Plasmas Thermiques, CNRS UPES-A 6069, Universite Blaise Pascal 63177 Aubiere (France)

    2003-07-07

    This paper presents a simple model of the fragment in the cathode electrical arc root taking into account the physical phenomena occurring on the cathode surface and the sheath. The goal is the obtainment of characteristics values of the heat flux, the electrons, and atoms density in the sheath. Computation is carried out on a one-dimensional model with a coupling between the equation obtained in the sheath and an enthalpy model of the cathode to describe the temperature evolution. In the modelling, we introduce a friction zone above the sheath edge to characterize the heavy particle interactions. Numerical simulation shows that the ionic friction phenomenon deriving from ion-atom collision regulates the heat flux lightening the surface, and the crucial necessity to obtain a good evaluation of the cross section of the charge exchange.

  6. Test preparation and lifetime measurement of very thin carbon stripper foils made by a controlled DC arc-discharge method

    CERN Document Server

    Sugai, I; Oyaizu, M; Kawakami, H; Hattori, Y; Kawasaki, K; Hayashizaki, N

    2002-01-01

    We have prepared very thin plastic supported carbon stripper foils (1.2+-0.3 mu g/cm sup 2) using a controlled DC arc-discharge (CDAD) method. The lifetime of these foils was measured with 3.2 MeV Ne sup + ions. These foils recorded lifetimes about four times longer at the maximum and three times longer on the average than those commercially available foils produced by evaporation-condensation.

  7. A glucose concentration and temperature sensor based on long period fiber gratings induced by electric-arc discharge

    Science.gov (United States)

    Du, Chao; Wang, Qi

    2017-10-01

    As one of the key parameters in biological and chemical reactions, glucose concentration objectively reflects the characteristics of reactions, so the real-time monitoring of glucose concentration is important in the field of biochemical. Meanwhile, the influence from temperature should be considered. The fiber sensors have been studied extensively for decades due to the advantages of small size, immunity to electromagnetic interference and high sensitivity, which are suitable for the application of biochemical sensing. A long period fiber grating (LPFG) sensor induced by electric-arc discharge has been fabricated and demonstrated for simultaneous measurement of glucose concentration and temperature. The proposed sensor was fabricated by inscribing a sing mode fiber (SMF) with periodic electric-arc discharge technology. During the fabrication process, the electric-arc discharge technology was produced by a commercial fusion splicer, and the period of inscribed LPFG was determined by the movement of translation stages. A serials of periodic geometrical deformations would be formed in SMF after the fabrication, and the discharge intensity and discharge time can be adjusted though the fusion splicer settings screen. The core mode can be coupled into the cladding modes at certain wavelength when they satisfy the phase-matching conditions, and there will be several resonance dips in the transmission spectrum in LPFG. The resonance dips formed by the coupling between cladding modes and core mode have different sensitivity responses, so the simultaneous measurement for multi-parameter can be realized by monitoring the wavelength shifts of the resonance dips. Compared with the LPFG based on conventional SMF, the glucose concentration sensitivity has been obviously enhanced by etching the cladding with hydrofluoric acid solution. Based on the independent measured results, a dual-parameter measurement matrix has been built for signal demodulation. Because of the easy

  8. Vacuum arc plasma deposition of thin titanium dioxide films on silicone elastomer as a functional coating for medical applications.

    Science.gov (United States)

    Boudot, Cécile; Kühn, Marvin; Kühn-Kauffeldt, Marina; Schein, Jochen

    2017-05-01

    Silicone elastomer is a promising material for medical applications and is widely used for implants with blood and tissue contact. However, its strong hydrophobicity limits adhesion of tissue cells to silicone surfaces, which can impair the healing process. To improve the biological properties of silicone, a triggerless pulsed vacuum cathodic arc plasma deposition technique was applied to deposit titanium dioxide (TiO2) films onto the surface. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and contact angle measurements were used for coating characterization. Deposited films were about 150nm thick and exhibited good adhesion to the underlying silicone substrate. Surface wettability and roughness both increased after deposition of the TiO2 layer. In addition, cell-biological investigations demonstrated that the in-vitro cytocompatibility of TiO2-coated samples was greatly improved without impacting silicone's nontoxicity. For validation of use in medical devices, further investigations were conducted and demonstrated stability of surface properties in an aqueous environment for a period of 68days and the coating's resistance to several sterilization methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Macrosegregation Behavior of Ti-10V-2Fe-3Al Alloy During Vacuum Consumable Arc Remelting Process

    Science.gov (United States)

    Yang, Zhijun; Kou, Hongchao; Li, Jinshan; Hu, Rui; Chang, Hui; Zhou, Lian

    2011-02-01

    The effects of melting current and magnetic field in vacuum consumable arc remelting (VAR) process on the macrosegregation of Ti-10V-2Fe-3Al ingot are investigated in this paper. The results show that Fe content increases gradually from the bottom to the top of ingots along axial direction and the degree of macrosegregation is greater in the radial direction in the middle of the ingot versus the top and bottom. The macrosegregation rate of Fe element is higher with melting current of 2.6 kA than that of 1.7 kA in Ti-10V-2Al-3Fe ingot. There are two forces, buoyancy and Lorentz forces which arise from the flow of current through the pool of VAR when without magnetic stirring, but a new Lorentz force arising from the presence of external inductors occurs with adding magnetic stirring which decreases the macrosegregation rate of Fe element in Ti-10V-2Fe-3Al.

  10. Preparation of transparent and conductive multicomponent Zn-In-Sn oxide thin films by vacuum arc plasma evaporation

    Science.gov (United States)

    Minami, Tadatsugu; Tsukada, Satoshi; Minamino, Youhei; Miyata, Toshihiro

    2005-07-01

    This article describes the preparation of transparent conducting oxide (TCO) thin films by a vacuum arc plasma evaporation (VAPE) method using multicomponent oxide materials composed of any combination of two of the following binary compounds: ZnO, In2O3, and SnO2. The resulting TCO thin films were prepared with high deposition rates with the desired chemical composition in the ZnO-In2O3, In2O3-SnO2, and SnO2-ZnO systems by altering the composition of the sintered oxide fragments used as the source materials. Minimum resistivities were obtained in amorphous In2O3-ZnO, SnO2-In2O3, and ZnO-SnO2 thin films that were prepared with a Zn content of about 8.5 at. %, an In content of about 46 at. %, and a Sn content of about 78 at. %, respectively. It was found that the electrical, optical and chemical properties in ZnO-SnO2 thin films prepared using the VAPE method could be controlled by altering the Sn content.

  11. Vacuum-arc chromium-based coatings for protection of zirconium alloys from the high-temperature oxidation in air

    Energy Technology Data Exchange (ETDEWEB)

    Kuprin, A.S.; Belous, V.A.; Voyevodin, V.N., E-mail: voyev@kipt.kharkov.ua; Bryk, V.V.; Vasilenko, R.L.; Ovcharenko, V.D.; Reshetnyak, E.N.; Tolmachova, G.N.; V' yugov, P.N.

    2015-10-15

    Multilayer Cr–Zr/Cr/Cr–N coatings for protection of zirconium alloys from the high-temperature oxidation in air have been obtained by the vacuum-arc evaporation technique with application of filters for plasma cleaning from macroparticles. The effect of the coatings on the corrosion resistance of zirconium alloys at test temperatures between 660 and 1100 °C for 3600 s has been investigated. The thickness, structure, phase composition, mechanical properties of the coatings and oxide layers before and after oxidation tests were examined by scanning electron microscopy, X-ray diffraction analysis and nanoindentation technique. It is shown that the hard multilayer coating effectively protects zirconium from the oxidation in air for 1 h at test temperatures. As a result of the oxidation in the coating the CrO and Cr{sub 2}O{sub 3} oxides are formed which reduce the oxygen penetration through the coating. At maximum test temperature of 1100 °C the oxide layer thickness in the coating is about 5 μm. The tube shape remains unchanged independent of alloy type. It has been found that uncoated zirconium oxidizes rapidly throughout the temperature range under study. At 1100 °C a porous monoclinic ZrO{sub 2} oxide layer of ≥120 μm is formed that leads to the deformation of the samples, cracking and spalling of the oxide layer.

  12. Detailed numerical simulation of cathode spots in vacuum arcs: Interplay of different mechanisms and ejection of droplets

    Science.gov (United States)

    Kaufmann, H. T. C.; Cunha, M. D.; Benilov, M. S.; Hartmann, W.; Wenzel, N.

    2017-10-01

    A model of cathode spots in high-current vacuum arcs is developed with account of all the potentially relevant mechanisms: the bombardment of the cathode surface by ions coming from a pre-existing plasma cloud; vaporization of the cathode material in the spot, its ionization, and the interaction of the produced plasma with the cathode; the Joule heat generation in the cathode body; melting of the cathode material and motion of the melt under the effect of the plasma pressure and the Lorentz force and related phenomena. After the spot has been ignited by the action of the cloud (which takes a few nanoseconds), the metal in the spot is melted and accelerated toward the periphery of the spot, with the main driving force being the pressure due to incident ions. Electron emission cooling and convective heat transfer are dominant mechanisms of cooling in the spot, limiting the maximum temperature of the cathode to approximately 4700-4800 K. A crater is formed on the cathode surface in this way. After the plasma cloud has been extinguished, a liquid-metal jet is formed and a droplet is ejected. No explosions have been observed. The modeling results conform to estimates of different mechanisms of cathode erosion derived from the experimental data on the net and ion erosion of copper cathodes.

  13. Characterization of an AC glow-type gliding arc discharge in atmospheric air with a current-voltage lumped model

    Science.gov (United States)

    Kong, Chengdong; Gao, Jinlong; Zhu, Jiajian; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan

    2017-09-01

    Quantitative characterization of a high-power glow-mode gliding arc (GM-GA) discharge operated in open air is performed using a current-voltage lumped model that is built from the perspective of energy balance and electron conservation. The GM-GA discharge is powered by a 35 kHz alternating current power supply. Instantaneous images of the discharge volume are recorded using a high-speed camera at a frame rate of 50 kHz, synchronized with the simultaneously recorded current and voltage waveforms. Detailed analyzation indicates that the electrical input power is dissipated mainly through the transport of vibrationally excited nitrogen and other active radicals (such as O). The plasma is quite non-thermal with the ratio of vibrational and translational temperatures (Tv/Tg) larger than 2 due to the intense energy dissipation. The electron number density reaches 3 × 1019 m-3 and is always above the steady value owing to the short cutting events, which can recover the electron density to a relatively large value and limits the maximum length of the gliding arc. The slow decaying rate of electrons is probably attributed to the decomposed state of a hot gaseous mixture and the related associative ionization.

  14. The dependence of filtered vacuum arc deposited ZnO-SnO{sub 2} thin films characteristics on substrate temperature

    Energy Technology Data Exchange (ETDEWEB)

    Cetinorgue, E [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel); Goldsmith, S [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel); Barkay, Z [Fleischman Faculty of Engineering, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel); Boxman, R L [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel)

    2006-12-21

    ZnO-SnO{sub 2} thin films were deposited by filtered vacuum arc deposition system and characterized using x-ray diffraction (XRD), energy dispersive spectroscopy, atomic force microscopy (AFM), spectrophotometer and ex situ variable angle spectroscopic ellipsometry. According to the XRD analysis the films were amorphous, independent of the deposition conditions. The root-mean-squares (RMS) of surface roughness and the average grain size obtained from the AFM images were 0.2-0.8 nm and 15-20 nm, respectively. Averaged optical transmission was 85%, and the refractive index and extinction coefficient of the films were in the range 2.05-2.28 and 0.001-0.044 at 500 nm wavelength, respectively. The range of the optical band gap of the films was 3.43-3.70 eV, depending on deposition conditions. The lowest resistivity was of the order of 10{sup -2} {omega} cm for films deposited on 400 {sup 0}C heated substrates, while films deposited on substrates at room temperature were non-conducting, and films on 200 {sup 0}C heated substrates were weakly conducting({approx}10{sup 1-2} {omega} cm). The resistivity of films decreased with increasing pressure for 200 and 400 {sup 0}C heated substrates relative to RT deposited films. The effect of deposition conditions on the optical constants was analysed statistically by single and two sided variance analysis, using the analysis code 'Analysis Of Variance' to determine the significance of the differences between sets.

  15. Preparation of carbon-encapsulated iron nanoparticles in high yield by DC arc discharge and their characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Cui, Lan; Lin, Kui [Center of Analysis, Tianjin University, Tianjin 300072 (China); Jin, Feng-min; Wang, Bin [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Shi, Shu-xiu [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Yang, De-an [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Wang, Hui [Center of Analysis, Tianjin University, Tianjin 300072 (China); He, Fei [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Chen, Xiao-ping [Center of Analysis, Tianjin University, Tianjin 300072 (China); Cui, Shen, E-mail: cuishen@tju.edu.cn [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China)

    2013-03-15

    Highlights: ► CEINPs with core–shell structure and high Fe content were prepared in high yield by DC arc discharge. ► The anode II with a mass ratio of total iron to carbon 8:1 was used in DC arc discharge. ► The possible process of formation of CEINPs is briefly discussed. ► The uniformity of composition of anode is very important for the formation of CEINPs. ► The MEF and MMF of iron element may also play an important role in the formation of CEINPs. -- Abstract: Carbon-encapsulated iron nanoparticles (CEINPs) were prepared by DC arc discharge under nitrogen atmosphere of high temperature. The products were characterized by transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), X-ray diffractometer (XRD), energy dispersive X-ray (EDX) spectroscope, and X-ray photoelectron spectroscope (XPS), and their magnetic properties were measured by physical property measurement system (PPMS). The product B{sub I}, obtained from the anode I, contains the nanoparticles of iron and iron carbide, and carbon coating with imperfect and disordered layer structure. The product B{sub II}, obtained from the anode II, mainly consists of CEINPs, whose cores mainly consist of iron and iron carbide and shells contain about 3–7 graphitic layers. The iron contents in the products B{sub I} and B{sub II} are 44.8 and 82.6 wt.%, respectively. The products B{sub I} and B{sub II} have similar phase composition which includes carbon, iron, iron carbide, ferrous and ferric oxide, iron nitride, and carbon nitride. The saturation magnetization (Ms) of the products B{sub I} and B{sub II} are 29.35 and 88.66 emu/g and their coercivity (Hc) are 220 and 240 Oe, respectively. The total yields of all the products formed in the arc discharge chamber from anodes I and II, except for the cylinder-shaped deposits formed on the top of the cathode, are 25.8 and 22.3 wt.%, respectively. The possible process of formation of CEINPs is briefly discussed on

  16. Gliding arc discharge — Application for adhesion improvement of fibre reinforced polyester composites

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Teodoru, Steluta; Leipold, Frank

    2008-01-01

    A gliding arc enables selective chemical process with high productivity due to its high degree of non-equilibrium and high energy density simultaneously, and thus can be preferably used for a variety of industrial applications such as gas cleaning, pollution control, fuel conversion, hydrogen...... production, and surface treatment. However, the application for adhesion improvement of structural materials has been rarely reported. In the present work, glass fibre reinforced polyester plates were treated using atmospheric pressure gliding arcs with high speed air flow for adhesion improvement...

  17. CO_{2} conversion in a gliding arc plasma : 1D cylindrical discharge model

    OpenAIRE

    Wang, Weizong; Berthelot, Antonin; Kolev, Stanimir; Tu, Xin; Bogaerts, Annemie

    2016-01-01

    Abstract: CO2 conversion by a gliding arc plasma is gaining increasing interest, but the underlying mechanisms for an energy-efficient process are still far from understood. Indeed, the chemical complexity of the non-equilibrium plasma poses a challenge for plasma modeling due to the huge computational load. In this paper, a one-dimensional (1D) gliding arc model is developed in a cylindrical frame, with a detailed non-equilibrium CO2 plasma chemistry set, including the CO2 vibrational kineti...

  18. Comparative Study on Extinction Process of Gas-Blasted Air and CO2 Arc Discharge Using Two-Dimensional Electron Density Imaging Sensor

    Science.gov (United States)

    Inada, Yuki; Kamiya, Tomoki; Matsuoka, Shigeyasu; Kumada, Akiko; Ikeda, Hisatoshi; Hidaka, Kunihiko; Nakano, Tomoyuki; Murai, Kosuke; Tanaka, Yasunori; Shinkai, Takeshi

    2015-09-01

    Systematic comparison of the electron density images for various kinds of arc-quenching gas media inside high-voltage circuit breakers is a promising method for the effective search and development of SF6-alternative gases. However, electron density imaging over the decaying arcs around the nozzle throat of the circuit breakers is extremely difficult by using the conventional arc generation setup and localized type sensing systems, due to the nozzle opaqueness and spatiotemporal instability of long-gap arc discharges around current zero. Here, we achieved two-dimensional electron density imaging over the decaying arcs around the nozzle throat first in the world, by a combination of the development of a unique gas flow nozzle integrating a cubic quartz cell and the single-shot recordings using Shack-Hartmann sensors. Shack-Hartmann sensors were applied to gas-blasted air and CO2 arc discharges under current-zero phases after sudden switch-off of stationary arc currents. These experimental results showed that the electron densities and arc diameters took the minimums in the upper stream nozzle regions with the maximum blasting gas speeds. In addition, CO2 had a shorter electron density decaying time constant than air, which is consistent with the previous theoretical studies on higher interruption performance of CO2 compared with air.

  19. Recent experimental study of DD fusion in the potential well of a virtual cathode at nanosecond vacuum discharge

    Science.gov (United States)

    Oginov, A. V.; Kurilenkov, Yu K.; Samoylov, I. S.; Shpakov, K. V.; Tarakanov, V. P.; Ostashev, V. E.; Rodionov, A. A.; Karpukhin, V. T.

    2016-11-01

    Processes of nuclear burning of various elements in the scheme of a compact inertial electrostatic confinement implemented on the basis of a nanosecond vacuum discharge (NVD) with low-energy hollow cathode were investigated experimentally earlier. This paper presents the results of a recent series of DD fusion experiments on the newly created experimental set-up NVD-2 combined with x-ray and neutron yield diagnostics. The voltage-current (VA) characteristics of the discharge, and the regimes of generation of x-ray and DD neutrons realized experimentally are presented and discussed. The experimental results are compared with the results of particle-in-cell simulation of the nuclear DD fusion processes in NVD using electrodynamic code KARAT. Recent series of DD fusion experiments have reproducing in TOF scheme some basic features of DD neutrons yield observed earlier. Meanwhile, the analysis of V-A characteristics and anode erosion shows that efficiency of energy deposition at initial stage of discharge is still insufficient, and the ways to optimize the electrophysical processes at NVD-2 are clarified.

  20. System for time resolved spectral studies of pulsed atmospheric discharges in the visible to vacuum ultraviolet range.

    Science.gov (United States)

    Laity, G; Neuber, A; Rogers, G; Frank, K

    2010-08-01

    Vacuum ultraviolet (VUV) emission is believed to play a major role in the development of plasma streamers in pulsed atmospheric discharges, but detection of VUV light is difficult in pulsed experiments at atmospheric pressures. Since VUV light is absorbed in most standard optical materials as well, careful attention must be given to the selection of the lens and mirror optics used in these studies. Of highest interest is the VUV emission during the initial stage of pulsed atmospheric discharges, which has a typical duration in the nanosecond regime. An experiment was designed to study this fast initial stage of VUV emission coupled with fast optical imaging of streamer propagation, both with temporal resolution on the order of nanoseconds. A repetitive solid-state high voltage pulser was constructed which produces triggered flashover discharges with low jitter and consistent pulse amplitude. VUV emission is captured utilizing both photomultiplier and intensified charge-coupled device detectors during the fast stage of streamer propagation. These results are discussed in context with the streamer formation photographed in the visible wavelength regime with 3 ns exposure time.

  1. Hydrogenation behavior of Ti-implanted Zr-1Nb alloy with TiN films deposited using filtered vacuum arc and magnetron sputtering

    Science.gov (United States)

    Kashkarov, E. B.; Nikitenkov, N. N.; Sutygina, A. N.; Bezmaternykh, A. O.; Kudiiarov, V. N.; Syrtanov, M. S.; Pryamushko, T. S.

    2018-02-01

    More than 60 years of operation of water-cooled reactors have shown that local or general critical hydrogen concentration is one of the basic limiting criteria of zirconium-based fuel element claddings. During the coolant radiolysis, released hydrogen penetrates and accumulates in zirconium alloys. Hydrogenation of zirconium alloys leads to degradation of their mechanical properties, hydride cracking and stress corrosion cracking. In this research the effect of titanium nitride (TiN) deposition on hydrogenation behavior of Ti-implanted Zr-1Nb alloy was described. Ti-implanted interlayer was fabricated by plasma immersion ion implantation (PIII) at the pulsed bias voltage of 1500 V to improve the adhesion of TiN and reduce hydrogen penetration into Zr-1Nb alloy. We conducted the comparative analysis on hydrogenation behavior of the Ti-implanted alloy with sputtered and evaporated TiN films by reactive dc magnetron sputtering (dcMS) and filtered cathodic vacuum arc deposition (FVAD), respectively. The crystalline structure and surface morphology were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The elemental distribution was analyzed using glow-discharge optical emission spectroscopy (GD-OES). Hydrogenation was performed from gas atmosphere at 350 °C and 2 atm hydrogen pressure. The results revealed that TiN films as well as Ti implantation significantly reduce hydrogen absorption rate of Zr-1Nb alloy. The best performance to reduce the rate of hydrogen absorption is Ti-implanted layer with evaporated TiN film. Morphology of the films impacted hydrogen permeation through TiN films: the denser film the lower hydrogen permeation. The Ti-implanted interface plays an important role of hydrogen accumulation layer for trapping the penetrated hydrogen. No deterioration of adhesive properties of TiN films on Zr-1Nb alloy with Ti-implanted interface occurs under high-temperature hydrogen exposure. Thus, the fabrication of Ti

  2. Structural and optical characteristics of filtered vacuum arc deposited N:TiO{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Çetinörgü-Goldenberg, E., E-mail: edacetinorgu@gmail.com [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel); Burstein, L. [Wolfson Applied Materials Research Center, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel); Chayun-Zucker, I.; Avni, R.; Boxman, R.L. [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel)

    2013-06-30

    Nitrogen doped titanium oxide (N:TiO{sub x}) thin films were deposited using filtered vacuum arc deposition. The X-ray diffraction patterns of the TiO{sub 2} thin films deposited in a pure oxygen environment indicated that films were polycrystalline in the anatase phase, while films deposited in an atmosphere in which the N{sub 2} fraction was greater than 9% were amorphous, for substrate temperatures up to 500 °C. Annealing at 400 °C in N{sub 2} for 1 h generated polycrystalline films with anatase phase, independent of %N{sub 2} during deposition. Film surface roughness increased from 0.5 up to 3.2 nm when the substrate temperature was increased from room temperature to 500 °C for films deposited in a 41%N{sub 2}. X-ray photoelectron spectroscopy analysis indicated that all films deposited in pure oxygen were stoichiometric TiO{sub 2}. N content in the films increased with %N{sub 2} in the deposition atmosphere, however the N-content in the film, 1-5 at.% N, was much less than that in the gas mixture (9–69%N{sub 2}). Annealing decreased the N-content in these films to < 1 at.%. In addition, the data revealed that all N:TiO{sub x} films had two main N 1s components, at 396–397 eV and at 399–400 eV, associated with substitutional and interstitial nitrogen, respectively. Transmission data indicated that the average transmission of films deposited at lower N{sub 2} partial pressures (< 41%) was approximately 80%, and it decreased to ∼ 50% for higher %N{sub 2}. The absorption edge of the films shifted to longer wavelengths with increased substrate temperature and %N{sub 2}, from ∼ 380 nm up to ∼ 485 nm for films deposited with 41%N{sub 2} and a substrate temperature of 500 °C. - Highlights: • Amorphous films were deposited in N{sub 2} atmosphere (> 9%). • Film surface roughness decreased with %N{sub 2} in the total deposition pressure. • Two main N 1s peaks associated with substitutional and interstitial nitrogen. • Absorption edge shifted to

  3. Comparative study on extinction process of gas-blasted air and CO2 arc discharge using two-dimensional electron density imaging sensor

    Science.gov (United States)

    Inada, Yuki; Kumada, Akiko; Ikeda, Hisatoshi; Hidaka, Kunihiko; Nakano, Tomoyuki; Murai, Kosuke; Tanaka, Yasunori; Shinkai, Takeshi

    2017-05-01

    Shack-Hartmann type laser wavefront sensors were applied to gas-blasted arc discharges under current-zero phases, generated in a 50 mm-long interelectrode gap confined by a gas flow nozzle, in order to conduct a systematic comparison of electron density decaying processes for two kinds of arc-quenching gas media: air and \\text{C}{{\\text{O}}2} . The experimental results for the air and \\text{C}{{\\text{O}}2} arc plasmas showed that the electron densities and arc diameters became thinner toward the nozzle-throat inlet due to a stronger convection loss in the arc radial direction. In addition, \\text{C}{{\\text{O}}2} had a shorter electron density decaying time constant than air, which could be caused by convection loss and turbulent flow of \\text{C}{{\\text{O}}2} stronger than air.

  4. Experimental Test Of Whether Electrostatically Charged Micro-organisms And Their Spores Contribute To The Onset Of Arcs Across Vacuum Gaps

    Energy Technology Data Exchange (ETDEWEB)

    none,; Grisham, Larry R.

    2014-02-24

    Recently it was proposed [L.R. Grisham, A. vonHalle, A.F. Carpe, Guy Rossi, K.R. Gilton, E.D. McBride, E.P. Gilson, A. Stepanov, T.N. Stevenson, Physics of Plasma 19 023107 (2012)] that one of the initiators of vacuum voltage breakdown between condu cting electrodes might be micro-organisms and their spores, previously deposited during exposure to air, which tnen become electrostatically charged when an electric potential is applied across the vacuum gap. The note describes a simple experiment to compare the number of voltage-conditioning pulses required to reach the nominal maxium operating voltage across a gap between two metallic conductors in a vacuum, comparing cases in which biological cleaning was done just prior to pump-down with cases where this was not done, with each preceded by exposure to ambient air for three days. Based upon these results, it does not appear that air-deposited microbes and their spores constitute a major pathway for arc initiation, at least for exposure periods of a few days, and for vacuum gaps of a few millimeters, in the regime where voltage holding is usually observed to vary linearly with gap distance

  5. The effect of the operation modes of a gas discharge low-pressure amalgam lamp on the intensity of generation of 185 nm UV vacuum radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyak, L. M., E-mail: vasilyak@ihed.ras.ru [Russian Academy of Sciences, Joint Institute of High Temperatures (Russian Federation); Drozdov, L. A., E-mail: lit@npo.lit.ru; Kostyuchenko, S. V.; Sokolov, D. V. [ZAO LIT (Russian Federation); Kudryavtsev, N. N.; Sobur, D. A., E-mail: soburda@gmail.com [Moscow Institute for Physics and Technology (Russian Federation)

    2011-12-15

    The effect of the discharge current, mercury vapor pressure, and the inert gas pressure on the intensity and efficiency of the 185 nm line generation are considered. The spectra of the UV radiation (vacuum ultraviolet) transmission by protective coatings from the oxides of rare earth metals and aluminum are investigated.

  6. Modeling of high pressure arc-discharge with a fully-implicit Navier-Stokes stabilized finite element flow solver

    Science.gov (United States)

    Sahai, A.; Mansour, N. N.; Lopez, B.; Panesi, M.

    2017-05-01

    This work addresses the modeling of high pressure electric discharge in an arc-heated wind tunnel. The combined numerical solution of Poisson’s equation, radiative transfer equations, and the set of Favre-averaged thermochemical nonequilibrium Navier-Stokes equations allows for the determination of the electric, radiation, and flow fields, accounting for their mutual interaction. Semi-classical statistical thermodynamics is used to determine the plasma thermodynamic properties, while transport properties are obtained from kinetic principles with the Chapman-Enskog method. A multi-temperature formulation is used to account for thermal non-equilibrium. Finally, the turbulence closure of the flow equations is obtained by means of the Spalart-Allmaras model, which requires the solution of an additional scalar transport equation. A Streamline upwind Petrov-Galerkin stabilized finite element formulation is employed to solve the Navier-Stokes equation. The electric field equation is solved using the standard Galerkin formulation. A stable formulation for the radiative transfer equations is obtained using the least-squares finite element method. The developed simulation framework has been applied to investigate turbulent plasma flows in the 20 MW Aerodynamic Heating Facility at NASA Ames Research Center. The current model is able to predict the process of energy addition and re-distribution due to Joule heating and thermal radiation, resulting in a hot central core surrounded by colder flow. The use of an unsteady three-dimensional treatment also allows the asymmetry due to a dynamic electric arc attachment point in the cathode chamber to be captured accurately. The current work paves the way for detailed estimation of operating characteristics for arc-heated wind tunnels which are critical in testing thermal protection systems.

  7. Multitudinous industrialized fabrication of BNNT with high-energy ball milling and arc-discharge-aided template methods

    Science.gov (United States)

    Wang, Shouren; Wen, Daosheng; Wang, Gaoqi; Yang, Liying; Guo, Peiquan; Qiao, Yang

    2017-10-01

    A novel large-scale fabrication technology for single-walled boron nitride nanotube (BNNT) relying on a template of single-walled carbon nanotube (SWCNTs) was introduced. In order to obtain large-scale product, the high-energy ball milling-aided heating technology was used to promote the formation of BNNTs. And arc-discharge methods were used to provide nitrogen ion source. The products were oxidized at 800 °C in air atmosphere to obtain pure BNNTs. The structure and morphology of BNNTs were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermogravimetric analysis. The multitudinous industrialized preparation methods for BNNTs were realized as a simple and effective route.

  8. Fabrication of TiO2/Carbon Photocatalyst using Submerged DC Arc Discharged in Ethanol/Acetic Acid Medium

    Science.gov (United States)

    Saraswati, T. E.; Nandika, A. O.; Andhika, I. F.; Patiha; Purnawan, C.; Wahyuningsih, S.; Rahardjo, S. B.

    2017-05-01

    This study aimed to fabricate a modified photocatalyst of TiO2/C to enhance its performance. The fabrication was achieved using the submerged direct current (DC) arc-discharge method employing two graphite electrodes, one of which was filled with a mixture of carbon powder, TiO2, and binder, in ethanol with acetic acid added in various concentrations. The arc-discharge method was conducted by flowing a current of 10-20 A (~20 V). X-ray diffraction (XRD) patterns showed significant placements of the main peak characteristics of TiO2, C graphite, and titanium carbide. The surface analysis using Fourier transform infrared spectroscopy (FTIR) revealed that fabricated TiO2/C nanoparticles had stretching vibrations of Ti-O, C-H, C═O, C-O, O-H and C═C in the regions of 450-550 cm-1, 2900-2880 cm-1, 1690-1760 cm-1, 1050-1300 cm-1, 3400-3700 cm-1 and ~1600 cm-1, respectively. In addition, the study investigated the photocatalysts of unmodified and modified TiO2/C for photodegradation of methylene blue (MB) dye solution under mercury lamp irradiation. The effectiveness of the degradation was defined by the decrease in 60-minute absorbance under a UV-Vis spectrophotometer. Modified TiO2/C proved to be significantly more efficient in reducing dye concentrations, reaching ~70%. It indicated that the oxygen-containing functional groups have been successfully attached to the surface of the nanoparticles and played a role in enhancing photocatalytic activity.

  9. OH and O radicals production in atmospheric pressure air/Ar/H2O gliding arc discharge plasma jet

    Science.gov (United States)

    N, C. ROY; M, R. TALUKDER; A, N. CHOWDHURY

    2017-12-01

    Atmospheric pressure air/Ar/H2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic (OES) diagnostic technique is used for the characterization of plasmas and for identifications of {{OH}} and {{O}} radicals along with other species in the plasmas. The OES diagnostic technique reveals the excitation T x ≈ 5550–9000 K, rotational T r ≈ 1350–2700 K and gas T g ≈ 850–1600 K temperatures, and electron density {n}{{e}}≈ ({1.1-1.9})× {10}14 {{{cm}}}-3 under different experimental conditions. The production and destruction of {{OH}} and {{O}} radicals are investigated as functions of applied voltage and air flow rate. Relative intensities of {{OH}} and {{O}} radicals indicate that their production rates are increased with increasing {{Ar}} content in the gas mixture and applied voltage. {n}{{e}} reveals that the higher densities of {{OH}} and {{O}} radicals are produced in the discharge due to more effective electron impact dissociation of {{{H}}}2{{O}} and {{{O}}}2 molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced {n}{{e}}. The productions of {{OH}} and {{O}} are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties. Besides, {T}{{g}} significantly reduces with the enhanced air flow rate. This investigation reveals that {{Ar}} plays a significant role in the production of {{OH}} and {{O}} radicals.

  10. Degradation of palm oil refinery wastewaters by non-thermal gliding arc discharge at atmospheric pressure.

    Science.gov (United States)

    Mountapmbeme-Kouotou, P; Laminsi, S; Acayanka, E; Brisset, J-L

    2013-07-01

    The gliding electric discharge in humid air is a source of activated species forming (e.g. (•)OH, (•)NO and their derivatives H2O2, ONO2H and NO3H) which are present in a non-thermal plasma at atmospheric pressure. These species are able to degrade organic pollutants in palm oil refinery wastewaters (PORW). The increase in acidity (pH decrease), conductivity and total dissolved solids (TDS) and the decrease in the total organic carbon (TOC) of PORW samples exposed to the discharge are reported. More than 50% TOC abatement is obtained for 15 min treatment in batch conditions with a laboratory reactor. The organic pollutants of PORW, i.e. mainly fatty acids are degraded according to a pseudo first-order reaction (k* = 0.06 min(-1)). Post discharge reactions are also observed after having switched off the discharge, which suggests that the pseudo first-order (k ≈ 0.05 min(-1)) degradation reactions should be attributed to the diffusion of soluble reactive species, e.g. H2O2 and ONOOH in the liquid target.

  11. 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.

  12. Synthesis of aluminium nanoparticles by arc evaporation of an ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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.

  13. 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.

  14. Effect of deposition conditions on the characteristics of ZnO-SnO{sub 2} thin films deposited by filtered vacuum arc

    Energy Technology Data Exchange (ETDEWEB)

    Cetinoergue, E. [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB39040, Tel Aviv 69978 (Israel) and Cukurova University, Physics Department 01330 Adana (Turkey)]. E-mail: eda@eng.tau.ac.il; Goldsmith, S. [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB39040, Tel Aviv 69978 (Israel); School of Physics and Astronomy, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel); Boxman, R.L. [Electrical Discharge and Plasma Laboratory, Tel Aviv University, POB39040, Tel Aviv 69978 (Israel); Fleischman Faculty of Engineering, Tel Aviv University, POB 39040, Tel Aviv 69978 (Israel)

    2006-11-23

    ZnO-SnO{sub 2} thin films were deposited on microscope glass substrates by filtered vacuum arc deposition system. The effects of deposition conditions on film characteristics were studied using cathodes prepared with three different ratios of atomic concentrations of Zn to Sn. The micro and the macro properties of the films were investigated as a function of cathode composition, arc current, background oxygen deposition pressure, and deposition time. X-ray diffraction analysis indicated that deposited films were amorphous, independent of the cathode composition. The atomic concentration ratio of Zn to Sn in the film as determined by XPS analysis were 33.9%: 10.6%, 43.9%: 3.8%, 44.7%: 4.7% for 50%: 50%, 70%: 30% and 90%: 10% Zn-Sn alloy cathodes, respectively. Film transmission in the visible was 70 to 90%, affected by interference effects. The maximal and minimal values of the refractive index n and the absorption coefficient k in the visible were 2.11 to 1.94 and 0.07 to 0.001, respectively. The optical band gap was in the range of 3.13 to 3.59 eV. All films were highly resistive independent of deposition conditions used.

  15. Optical and structural properties of carbon dots/TiO2 nanostructures prepared via DC arc discharge in liquid

    Science.gov (United States)

    Biazar, Nooshin; Poursalehi, Reza; Delavari, Hamid

    2018-01-01

    Synthesis and development of visible active catalysts is an important issue in photocatalytic applications of nanomaterials. TiO2 nanostructures coupled with carbon dots demonstrate a considerable photocatalytic activity in visible wavelengths. Extending optical absorption of a wide band gap semiconductor such as TiO2 with carbon dots is the origin of the visible activity of carbon dots modified semiconductor nanostructures. In addition, carbon dots exhibit high photostability, appropriate electron transport and chemical stability without considerable toxicity or environmental footprints. In this study, optical and structural properties of carbon dots/TiO2 nanostructures prepared via (direct current) DC arc discharge in liquid were investigated. Crystal structure, morphology and optical properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible spectroscopy respectively. SEM images show formation of spherical nanoparticles with an average size of 27 nm. In comparison with pristine TiO2, optical transmission spectrum of carbon dots/TiO2 nanostructures demonstrates an absorption edge at longer wavelengths as well a high optical absorption in visible wavelengths which is significant for visible activity of nanostructures as a photocatalyst. Finally, these results can provide a flexible and versatile pathway for synthesis of carbon dots/oxide semiconductor nanostructures with an appropriate activity under visible light.

  16. Synthesis of carbon nanotubes by arc-discharge and chemical vapor deposition method with analysis of its morphology, dispersion and functionalization characteristics

    Directory of Open Access Journals (Sweden)

    Ritu Sharma

    2015-12-01

    Full Text Available In this paper, multi-walled carbon nanotubes are synthesized by arc-discharge and chemical vapor decomposition methods. Multi-walled carbon nanotubes are synthesized on thin film of nickel sputtered on silicon substrate by thermal chemical vapor deposition of acetylene at a temperature of 750°C. The flow of current in arc-discharge method varies in the range 50–200 A. Further arc-synthesized carbon nanotubes are characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and the results are compared with nanotubes grown by chemical vapor deposition method. XRD result shows a characteristic peak (0 0 2 at 26.54° corresponding to the presence of carbon nanotubes. SEM and TEM results give morphology of as-synthesized multi-walled nanotubes. TEM results indicate synthesis of well-graphitized carbon nanotubes by arc-discharge method. Dispersion of arc-synthesized nanotubes in SDS solution under the effect of different sonication times is studied. Dispersion of nanotubes in SDS solution is analyzed using UV–vis–NIR spectroscopy and it shows an absorption peak at 260 nm. It was found that with the increase in sonication time, the absorption peak in UV–vis–NIR spectra will increase and optimum sonication time was 2 hours. Functionalization of synthesized carbon nanotubes by H2SO4 and HNO3 acids has been studied and analysis of functionalized groups has been done using FT-IR spectroscopy and compared and the results are reported in this paper. FT-IR spectroscopy verifies the presence of carboxylic groups attached to carbon nanotubes. These functional groups may change properties of carbon nanotubes and may be used in vast applications of carbon nanotubes.

  17. High thrust-to-power ratio micro-cathode arc thruster

    OpenAIRE

    Joseph Lukas; George Teel; Jonathan Kolbeck; Michael Keidar

    2016-01-01

    The Micro-Cathode Arc Thruster (μCAT) is an electric propulsion device that ablates solid cathode material, through an electrical vacuum arc discharge, to create plasma and ultimately produce thrust in the μN to mN range. 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. A preliminary set of experiments were conducted to show that,...

  18. 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.

  19. SURFACE CHARACTER OF IRON OXIDE/CARBON NANOPARTICLES SYNTHESIZED BY SUBMERGED ARC DISCHARGE METHOD IN ETHANOL/UREA MEDIUM

    Directory of Open Access Journals (Sweden)

    Teguh Endah Saraswati

    2017-08-01

    Full Text Available Synthesis of iron oxide nanoparticles modified with carbon has been successfully performed by submerged arc-discharge method in ethanol/urea medium. Iron oxide used in the fabrication process was prepared by iron electrolysis in an electrolyte solution of NaCl. Fabrication of nanoparticles in this method uses two graphite electrodes. One of them was made in a pointed shape and the other graphite electrodes hollowed out and filled with a mixture of iron oxide, graphite and glue silica (as binder with a ratio of 1:3:1 (w/w/w. The liquid medium used in this method is a mixture solution of ethanol 50% and urea (0%, 10%, 25% and 50% with a volume ratio of 1:1 (v/v. The crystalline of iron oxide was characterized using X-Ray Diffraction (XRD, compared to JCPDS No. 89-0597, No. 89-0691 and No. 39-1346. Variations in the urea concentration in the liquid medium provided the changes of the surface character of the synthesized nanoparticles. The changes of surface character were analyzed by the Fourier Transform Infra Red (FTIR spectra and nanoparticle dispersion in water and ethanol. FTIR spectra showed the absorption of Fe-O, CH, CN, C = O, OH and NH at 460-555 cm-1, 650-1000 cm-1, 1000-1350 cm-1, 1640-1680 cm-1, 2400-3400 cm-1, 3200-3400 cm-1, 3100-3500 cm-1, respectively. The best hydrophilic surface character achieved when the nanoparticle was synthesized in medium of ethanol 50% with the addition of urea50%. The existence of a functional group attached on the surface of nanoparticles synthesized in ethanol/urea makes these nanoparticles had better dispersion than nanoparticles synthesized in ethanol medium without urea addition.

  20. Magnetic hysterysis evolution of Ni-Al alloy with Fe and Mn substitution by vacuum arc melting to produce the room temperature magnetocaloric effect material

    Energy Technology Data Exchange (ETDEWEB)

    Notonegoro, Hamdan Akbar [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa, Cilegon 42435 (Indonesia); Kurniawan, Budhy; Manaf, Azwar, E-mail: azwar@sci.ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Setiawan, Jan [Center for Nuclear Fuel Tecnology-Badan Tenaga Atom Nasional, Tangerang Selatan 15310 (Indonesia)

    2016-06-17

    The development of magnetocaloric effect (MCE) material is done in order to reduce the damage of the ozone layer caused by the chlorofluorocarbons (CFCs) emitted into the air. The research dealing with synthesis of magnetocaloric materials based of Ni-Al Heusler Alloy structure and by varying substitution some atoms of Ni with Fe and Al with Mn on Ni-Al Heusler Alloy structure to become Ni{sub 44}Fe{sub 6}Mn{sub 32}Al{sub 18}. Vacuum Arc Melting (VAM) equipment is used to form the alloys on vacuum condition and by flowing argon gas atmosphere and then followed by annealing process for 72 hours. X-Ray Diffraction (XRD) reveals that crystallite structure of material is observed. We define that Ni{sub 44}Fe{sub 6} as X{sub 2}, Mn{sub 25} as Y, and Al{sub 18}Mn{sub 7} as Z. Based on the XRD result, we observed that the general formula X{sub 2}YZ is not changed. The PERMAGRAF measurement revealed that there exists of magnetic hysterysis. The hysterysis show that the magnetic structures of the system undego evolution from diamagnetic to soft ferromagnetic material which all of the compound have the same crystallite structure. This evolution indicated that the change in the composition has led to changes the magnetic composition. Mn is the major element that gives strong magnetic properties to the sample. When Mn partially replaced position of Al, the sample became dominant to be influenced to improve their magnetic properties. In addition, substitution a part of Ni by Fe in the composition reveals a pinning of the domain walls in the sample.

  1. CO-AXIAL DISCHARGES

    Science.gov (United States)

    Luce, J.S.; Smith, L.P.

    1960-11-22

    A method and apparatus are given for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons will diffuse to the more positive arc from the negative arc, and positive ions will diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantage that ions which return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. Those discharges are useful in confining an ionized plasma between the discharges, and have the advantage of preventing impurities from the walls of the enclosure from entering ihe plasma area because of the arc barrier set up bv the cylindrical outer arc.

  2. METHOD AND APPARATUS FOR PRODUCING INTENSE ENERGETIC GAS DISCHARGES

    Science.gov (United States)

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

    1960-01-01

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

  3. Synthesis of graphene-like transparent conductive films on dielectric substrates using a modified filtered vacuum arc system

    Energy Technology Data Exchange (ETDEWEB)

    Lux, Helge, E-mail: lux@th-wildau.de; Schrader, Sigurd [Technical University of Applied Sciences Wildau, Hochschulring 1, Wildau 15745 (Germany); Siemroth, Peter [Arc Precision GmbH, Schwartzkopffstraße 2, Wildau 15745 (Germany); Sgarlata, Anna [Department of Physics, University of Roma - Tor Vergata, Via della Ricerca Scientifica 1, Roma 00133 (Italy); Prosposito, Paolo; Casalboni, Mauro [Department of Industrial Engineering, University of Roma - Tor Vergata, and Italian Interuniversity Consortium on Materials Science and Technology (INSTM), Research Unit Roma Tor Vergata Via del Politecnico 1, Roma 00133 (Italy); Schubert, Markus Andreas [IHP Innovations for High Performance Microelectronics, Im Technologiepark 25, Frankfurt (Oder) 15236 (Germany)

    2015-05-21

    Here, we present a reliable process to deposit transparent conductive films on silicon oxide, quartz, and sapphire using a solid carbon source. This layer consists of partially ordered graphene flakes with a lateral dimension of about 5 nm. The process does not require any catalytic metal and exploits a high current arc evaporation (Φ-HCA) to homogeneously deposit a layer of carbon on heated substrates. A gas atmosphere consisting of Argon or Argon/Hydrogen blend acting as a buffer influences the morphology of the growing film. scanning tunneling microscopy, transmission electron microscopy, and Raman spectra were used for a thorough characterization of the samples in order to optimize the growth parameters. The best carbon layers have a surface resistance of 5.7 × 10{sup 3} Ω{sub ◻} whereas the optical transparency of the coatings is 88% with an excellent homogeneity over areas of several cm{sup 2}. Such results are compatible with most semiconductor fabrication processes and make this method very promising for various industrial applications.

  4. 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.

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Guan, J.J. [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Wang, H.Q. [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Qin, L.Z., E-mail: qin8394@163.com [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Liao, B.; Liang, H. [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Li, B. [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China)

    2017-04-15

    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 N{sub 2}/C{sub 2}H{sub 2} 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 C{sub 2}H{sub 2} content ranging from 5% to 20%, and it will be evolved into amorphous carbon and amorphous CN{sub x} phases as C{sub 2}H{sub 2} 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% C{sub 2}H{sub 2} content, due to the graphite (sp{sup 2} C−C) phase embed in CrN host lattice; while the chromium carbon (Cr{sub 3}C{sub 2}) and diamond (sp{sup 3} C−C) phases may give rise to the increase of the coating hardness with the highest value at 23.97 GPa under 20% C{sub 2}H{sub 2} content.

  7. Exposure and emission measurements during production, purification, and functionalization of arc-discharge-produced multi-walled carbon nanotubes.

    Science.gov (United States)

    Hedmer, Maria; Isaxon, Christina; Nilsson, Patrik T; Ludvigsson, Linus; Messing, Maria E; Genberg, Johan; Skaug, Vidar; Bohgard, Mats; Tinnerberg, Håkan; Pagels, Joakim H

    2014-04-01

    The production and use of carbon nanotubes (CNTs) is rapidly growing. With increased production, there is potential that the number of occupational exposed workers will rapidly increase. Toxicological studies on rats have shown effects in the lungs, e.g., inflammation, granuloma formation, and fibrosis after repeated inhalation exposure to some forms of multi-walled CNTs (MWCNTs). Still, when it comes to health effects, it is unknown which dose metric is most relevant. Limited exposure data for CNTs exist today and no legally enforced occupational exposure limits are yet established. The aim of this work was to quantify the occupational exposures and emissions during arc discharge production, purification, and functionalization of MWCNTs. The CNT material handled typically had a mean length carbon (EC) concentrations, and number concentrations of CNT-containing particles were measured in the workers' breathing zones with filter-based methods during work. Additionally, emission measurements near the source were carried out during different work tasks. Respirable dust was gravimetrically determined; EC was analysed with thermal-optical analysis and the number of CNT-containing particles was analysed with scanning electron microscopy. For the personal exposure measurements, respirable dust ranged between production of CNTs. The highest emitted number concentration of CNT-containing particles occurred in the sieving, mechanical work-up, pouring, weighing, and packaging of CNT powder during the production stage. To be able to quantify exposures and emissions of CNTs, a selective and sensitive method is needed. Limitations with measuring EC and respirable dust are that these exposure metrics do not measure CNTs specifically. Only filter-based methods with electron microscopy analysis are, to date, selective and sensitive enough. This study showed that counting of CNT-containing particles is the method that fulfils those criteria and is therefore the method recommended

  8. Carbon Nanotube Emissions from Arc Discharge Production: Classification of Particle Types with Electron Microscopy and Comparison with Direct Reading Techniques.

    Science.gov (United States)

    Ludvigsson, Linus; Isaxon, Christina; Nilsson, Patrik T; Tinnerberg, Hakan; Messing, Maria E; Rissler, Jenny; Skaug, Vidar; Gudmundsson, Anders; Bohgard, Mats; Hedmer, Maria; Pagels, Joakim

    2016-05-01

    An increased production and use of carbon nanotubes (CNTs) is occurring worldwide. In parallel, a growing concern is emerging on the adverse effects the unintentional inhalation of CNTs can have on humans. There is currently a debate regarding which exposure metrics and measurement strategies are the most relevant to investigate workplace exposures to CNTs. This study investigated workplace CNT emissions using a combination of time-integrated filter sampling for scanning electron microscopy (SEM) and direct reading aerosol instruments (DRIs). Field measurements were performed during small-scale manufacturing of multiwalled carbon nanotubes using the arc discharge technique. Measurements with highly time- and size-resolved DRI techniques were carried out both in the emission and background (far-field) zones. Novel classifications and counting criteria were set up for the SEM method. Three classes of CNT-containing particles were defined: type 1: particles with aspect ratio length:width >3:1 (fibrous particles); type 2: particles without fibre characteristics but with high CNT content; and type 3: particles with visible embedded CNTs. Offline sampling using SEM showed emissions of CNT-containing particles in 5 out of 11 work tasks. The particles were classified into the three classes, of which type 1, fibrous CNT particles contributed 37%. The concentration of all CNT-containing particles and the occurrence of the particle classes varied strongly between work tasks. Based on the emission measurements, it was assessed that more than 85% of the exposure originated from open handling of CNT powder during the Sieving, mechanical work-up, and packaging work task. The DRI measurements provided complementary information, which combined with SEM provided information on: (i) the background adjusted emission concentration from each work task in different particle size ranges, (ii) identification of the key procedures in each work task that lead to emission peaks, (iii

  9. SiC Nanowires Synthesized by Rapidly Heating a Mixture of SiO and Arc-Discharge Plasma Pretreated Carbon Black

    Directory of Open Access Journals (Sweden)

    Wang Feng-Lei

    2008-01-01

    Full Text Available Abstract SiC nanowires have been synthesized at 1,600 °C by using a simple and low-cost method in a high-frequency induction furnace. The commercial SiO powder and the arc-discharge plasma pretreated carbon black were mixed and used as the source materials. The heating-up and reaction time is less than half an hour. It was found that most of the nanowires have core-shell SiC/SiO2nanostructures. The nucleation, precipitation, and growth processes were discussed in terms of the oxide-assisted cluster-solid mechanism.

  10. 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.

  11. SiC Nanowires Synthesized by Rapidly Heating a Mixture of SiO and Arc-Discharge Plasma Pretreated Carbon Black

    OpenAIRE

    Wang Feng-Lei; Zhang Li-Ying; Zhang Ya-Fei

    2008-01-01

    Abstract SiC nanowires have been synthesized at 1,600 °C by using a simple and low-cost method in a high-frequency induction furnace. The commercial SiO powder and the arc-discharge plasma pretreated carbon black were mixed and used as the source materials. The heating-up and reaction time is less than half an hour. It was found that most of the nanowires have core-shell SiC/SiO2nanostructures. The nucleation, precipitation, and growth processes were discussed in terms of the oxide-assis...

  12. The electrical, elemental, optical, and surface properties of Si-doped ZnO thin films prepared by thermionic vacuum arc

    Science.gov (United States)

    Mohammadigharehbagh, Reza; Özen, Soner; Yudar, Hafizittin Hakan; Pat, Suat; Korkmaz, Şadan

    2017-09-01

    The purpose of this work is to study the properties of Si-doped ZnO (SZO) thin films, which were prepared using the non-reactive thermionic vacuum arc technique. The analysis of the elemental, optical, and surface properties of ZnO:Si thin films was carried out using energy dispersive x-ray spectroscopy, UV-VIS spectrophotometry, atomic force microscopy, and scanning electron microscopy, respectively. The current-voltage measurement was employed in order to study the electrical properties of the films. The effect of Si doping on the physical properties of ZnO films was investigated. The film thicknesses were measured as 55 and 35 nm for glass and PET substrates, respectively. It was clearly observed from the x-ray diffraction results that the Si and ZnO peaks were present in the coated SZO films for all samples. The morphological studies showed that the deposited surfaces are homogenous, dense, and have a uniform surface, with the existence of some cracks only on the glass substrate. The elemental composition has confirmed the existence of Zn, Si, and O elements within the prepared films. Using a UV-VIS spectrophotometer, the optical parameters such as transmittance, absorbance, refractive index, and reflectance were calculated. It should be noted that the transparency and refractive indices obtained from the measurements decrease with increasing Si concentration. The obtained optical bandgap values using transmittance spectra were determined to be 3.74 and 3.84 eV for the glass and PET substrates, respectively. An increase in the bandgap results demonstrates that the Si doping concentration is comparable to the pure ZnO thin films. The current versus voltage curves revealed the ohmic nature of the films. Subsequently, the development and fabrication of excellent transparent conducting electrodes enabled the appropriate use of Si-doped ZnO thin films.

  13. A hybrid surface arc discharge ion source to produce ultra pure Ca(+2) beams for (40)Ca(alpha,gamma)(44)Ti reaction studies at ISAC/TRIUMF.

    Science.gov (United States)

    Jayamanna, K; Vockenhuber, C

    2008-02-01

    ISAC is an accelerator facility primarily dedicated to astrophysical studies. Off-line and online ion sources provide up to 65 keV of stable and radioactive beams to the ISAC accelerators. Initial acceleration is done via a constant velocity radio frequency quadrupole that requires 2 keV/u. Then the beam is further accelerated to 1.5 MeVu at ISAC-I and 6.5 MeV/u at ISAC-II. To study radiative capture reactions relevant for astrophysics, the recoil mass spectrometer DRAGON was built in the experimental area. (40)Ca(alpha,gamma)(44)Ti is identified as one of the key reactions in supernovae to produce (44)Ti and is given highest priority. For this experiment, an ultrapure Ca(+2) beam was requested from the off-line ion source. Initial tests showed that, when using conventional ion sources, (40)Ar and (40)K are the impurities that are most difficult to eliminate. In order to overcome this problem, a new concept was needed and the hybrid surface arc discharge ion source was born. The hybrid surface ion source consists of a small surface ionizer and an arc discharge placed in a solenoid field. A very low ratio of (40)Ar/(40)Ca=8 x 10(-5) was achieved with this new source and the experiment was completed successfully. The source is described in detail and its performance is discussed in this article.

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

    Directory of Open Access Journals (Sweden)

    Misiruk Ivan O.

    2016-06-01

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

  15. Synthesis of Ti-doped DLC film on SS304 steels by Filtered Cathodic Vacuum Arc (FCVA) technique for tribological improvement

    Science.gov (United States)

    Bootkul, D.; Saenphinit, N.; Supsermpol, B.; Aramwit, C.; Intarasiri, S.

    2014-08-01

    Currently, stainless steels are widely used in various industrial applications due to their excellence in toughness and corrosion resistance. But their resistance to wear needs to be improved for appropriate use in tribological applications. The Filtered Cathodic Vacuum Arc (FCVA) is a superior technique for forming a high-density film structure of amorphous carbon, especially for a tetrahedral amorphous carbon (ta-C) type, because it can produce a plasma of highly energetic ions that can penetrate into a growing coating, resulting in densification of the film. However, this technique tends to generate high internal stress, due to serious accumulation of energy in the film structure that then leads to film delamination. In general, there are numerous solutions that have been used to reduce the internal stress. DLC with various additive elements such as Ti, Cr or W as strong-carbide-forming (SCF) metals is one of the popular methods to provide attractive combinations of properties of wear resistance and film adhesion as well as reducing the internal stress. The present study was focused on investigation of titanium-doped DLC coating on SS304 steel, mainly for adhesion improvement in optimizing for tribological applications. The synthesized films were formed by the FCVA technique at normal substrate temperature. In the experimental set-up, the films were produced by mixing the titanium and carbon ions generated by dual cathode plasma source operating in synchronous pulsed mode. Their compositions were adjusted by varying the relative duration of the pulse length from each cathode. Titanium doping concentration was varied from pure DLC deposition as the control group to titanium and graphite trigger pulses ratios of 1:16, 1:12, 1:10, 1:8 and 1:4, as the Ti-doped DLC group. The results showed that by increasing titanium trigger pulses ratio from 1:16, 1:12, 1:10 and 1:8, respectively, the film adhesion was increased while the wear rate did not change significantly as

  16. A straightforward method for Vacuum-Ultraviolet flux measurements: The case of the hydrogen discharge lamp and implications for solid-phase actinometry

    Energy Technology Data Exchange (ETDEWEB)

    Fulvio, D., E-mail: daniele.fulvio@uni-jena.de, E-mail: dfu@oact.inaf.it; Brieva, A. C.; Jäger, C. [Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, D-07743 Jena (Germany); Cuylle, S. H.; Linnartz, H. [Raymond and Beverly Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. box 9513, 2300 RA Leiden (Netherlands); Henning, T. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

    2014-07-07

    Vacuum-Ultraviolet (VUV) radiation is responsible for the photo-processing of simple and complex molecules in several terrestrial and extraterrestrial environments. In the laboratory such radiation is commonly simulated by inexpensive and easy-to-use microwave-powered hydrogen discharge lamps. However, VUV flux measurements are not trivial and the methods/devices typically used for this purpose, mainly actinometry and calibrated VUV silicon photodiodes, are not very accurate or expensive and lack of general suitability to experimental setups. Here, we present a straightforward method for measuring the VUV photon flux based on the photoelectric effect and using a gold photodetector. This method is easily applicable to most experimental setups, bypasses the major problems of the other methods, and provides reliable flux measurements. As a case study, the method is applied to a microwave-powered hydrogen discharge lamp. In addition, the comparison of these flux measurements to those obtained by O{sub 2} actinometry experiments allow us to estimate the quantum yield (QY) values QY{sub 122} = 0.44 ± 0.16 and QY{sub 160} = 0.87 ± 0.30 for solid-phase O{sub 2} actinometry.

  17. Three dimensional numerical study of different parameters effect on the external magnetic field applied to center the arc of the horizontal mercury discharge lamp

    Directory of Open Access Journals (Sweden)

    Mohamed Bechir Ben Hamida

    2015-10-01

    Full Text Available The aim of this paper is to evaluate the magnitude of the external magnetic field to be applied to a horizontal mercury discharge lamp such that the Lorentz forces counterbalance buoyancy forces and the hot region of the arc remains centered inside the lamp with the variation of six parameters of the lamp such as the external temperature of the lamp, envelope thickness, convective loss, Interelectrodeslength, pressure and current supply pointing to the influence of the parameters to the compensating magnetic field value. To achieve this objective, a commercial numerical software “Comsol Multiphysics” is used to implement the model that solves the equations of mass, energy and momentum for laminar compressible flow combined with the Laplace equation for the plasma in a three dimensional.

  18. Enhancement of the bleaching and degradation of textile wastewaters by Gliding arc discharge plasma in the presence of TiO2 catalyst.

    Science.gov (United States)

    Ghezzar, M R; Abdelmalek, F; Belhadj, M; Benderdouche, N; Addou, A

    2009-05-30

    The degradation of two polluted textile wastewaters from SOITEX (silk and textile) industry using the plasma-catalytic process, has been studied by non-thermal Gliding arc technique coupled to Degussa P25 titanium dioxide (TiO(2)) as photo-catalyst. Experiments were carried out to optimise the amount of phtoto-catalyst. The results showed that maximum degradation was attained for 3 g L(-1) TiO(2) concentration. For wastewater (1) degradation was 95% at the end of 60 min of treatment time. The same wastewater was completely decolourised after only 30min of plasma-catalytic treatment time. In parallel, the biodegradability was significantly enhanced through 20 min of exposure to the plasmagenous source for both wastewater samples. Turbidity of wastewater (1) and wastewater (2) decreased with rate constants of 0.015 and 0.017m in(-1), respectively. The TiO(2)-mediated Gliding Arc discharge (GAD(TiO(2)) showed potential application for the treatment of liquid wastes, resulting in the mineralization of the wastewater samples confirmed by chloride, sulphate and phosphate ions formation. In both cases of GAD treatments, with and without photo-catalyst, the plasmagenous process proves efficient in the field of wastewaters degradation.

  19. Fast production of ZnO nanorods by arc discharge in de-ionized water and applications in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sönmezoğlu, S., E-mail: svssonmezoglu@kmu.edu.tr [Department of Materials Science and Engineering, Karamanoğlu Mehmetbey University, Karaman (Turkey); Eskizeybek, V. [Department of Materials Science and Engineering, Çanakkale Onsekiz Mart University, Çanakkale (Turkey); Toumiat, A. [Department of Physics, Constantine Ceramics Lab., Mentouri University (Algeria); Avcı, A. [Department of Mechanical Engineering, Selçuk University, Konya (Turkey)

    2014-02-15

    Highlights: • Fast production of ZnO nanorods was synthesized by bottom up approach using arc discharge in de-ionized water method. • A dye-sensitized solar cell based on ZnO nanorod displayed the most efficient solar to electricity conversion efficiency of the N719 dyes with a maximum η value of 6.96%. • We focused on the morphology, photocatalytical and optical properties of the ZnO nanorods. -- Abstract: Fast production of the ZnO nanorods by bottom up approach using arc discharge method in de-ionized water was carried out. Structural analysis showed that the obtained ZnO powder exhibits crystallize in the hexagonal wurtzite structure with (1 0 1) preferential orientation. Furthermore, transmission electron microscopy observations showed that rod-like structure is the abundant form with a bimodial grain size distribution around 10 and 30 nm. Optical characterization of the as-synthesized ZnO nanorods revealed the existence of the two absorption and photoluminescence (PL) bands both located at UV spectral region attributed to the two grain size distributions. In addition, the two additional visible bands PL spectrum located at 430 and 492 nm are attributed the interstitial zinc and oxygen vacancies; respectively. Dye sensitized solar cells (DSSCs) were successfully produced via different ruthenium based dyes and ferrocene liquid electrolyte by using of as synthesized ZnO nanorods modified photoanodes. It has been found that DSSCs made with N719 dye is the most efficient with photoconversion of approximately 7% compared to the other dyes. Such nanorod form of the ZnO nanostructures with ruthenium dyes resulted in significant improvements of the device performance in terms of electron transportation and UV light absorption. This work would explore feasible routes to synthesize efficient metal-oxide nanostructures for opto-electronic or other related applications.

  20. Magnetocaloric properties of TbN, DyN and HoN nanopowders prepared by the plasma arc discharge method.

    Science.gov (United States)

    Shinde, K P; Jang, S H; Kim, J W; Kim, D S; Ranot, M; Chung, K C

    2015-12-21

    We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications. The nitridization of terbium, dysprosium and holmium was obtained using a mixture of nitrogen and argon gas inside a discharge chamber with 4 kPa pressure. The structural and microstructural properties of these rare earth nitrides were investigated by using X-ray diffraction and transmission electron microscopy. The studied nitrides undergo a second-order ferromagnetic to paramagnetic phase transition at Curie temperatures of 35.7, 19.9 and 14.2 K for TbN, DyN and HoN, respectively. The magnetocaloric effects were estimated by calculating the magnetic entropy changes from the magnetization data sets measured at the different applied magnetic fields and temperatures. The changes in entropy -ΔSM were found to be 12.0, 13.6 and 24.5 J kg(-1) K(-1) at an applied magnetic field of 5 T.

  1. High-voltage discharge in supersonic jet of plumbum vapor

    Science.gov (United States)

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

    2015-11-01

    During study of vacuum discharge in plumbum evaporating from molybdenum crucible in identical geometry of discharge gap and the same crucible temperature existence of two different discharge forms were observed. These two forms are vacuum arc with current above 10 A and voltage about 15 V and high-voltage discharge with current about 10 mA and voltage of 340 V. Plumbum was placed in heat-isolated crucible (cathode). Electron-beam heater was situated under the crucible. At the temperature of 1.25 kK that corresponds to plumbum saturated vapor pressure about 0.1 kPa voltage from power source (380 V, 200 A) was applied to anode and high-voltage discharge initiated with characteristics mentioned above. After a few seconds this discharge could turn into arc or could exist hundreds of seconds until total plumbum evaporation. Glow of discharge could take the form of a cone, harness or plasma bunch that hanged at the appreciable distance from the electrodes. The estimations of plasma parameters are presented.

  2. Vacuum ultraviolet emission spectrum measurement of a microwave-discharge hydrogen-flow lamp in several configurations: Application to photodesorption of CO ice

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.-J.; Wu, C.-Y. R. [Space Sciences Center and Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-1341 (United States); Chuang, K.-J.; Chu, C.-C.; Yih, T.-S. [Department of Physics, National Central University, Jhongli City, Taoyuan County 32054, Taiwan (China); Muñoz Caro, G. M. [Centro de Astrobiología, INTA-CSIC, Torrejón de Ardoz, E-28850 Madrid (Spain); Nuevo, M. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Ip, W.-H., E-mail: yujung@usc.edu [Graduate Institute of Astronomy, National Central University, Jhongli City, Taoyuan County 32049, Taiwan (China)

    2014-01-20

    We report measurements of the vacuum ultraviolet (VUV) emission spectra of a microwave-discharge hydrogen-flow lamp (MDHL), a common tool in astrochemistry laboratories working on ice VUV photoprocessing. The MDHL provides hydrogen Ly-α (121.6 nm) and H{sub 2} molecular emission in the 110-180 nm range. We show that the spectral characteristics of the VUV light emitted in this range, in particular the relative proportion of Ly-α to molecular emission bands, strongly depend on the pressure of H{sub 2} inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H{sub 2} versus H{sub 2} seeded in He), and the optical properties of the window used (MgF{sub 2} versus CaF{sub 2}). These different configurations are used to study the VUV irradiation of CO ice at 14 K. In contrast to the majority of studies dedicated to the VUV irradiation of astrophysical ice analogs, which have not taken into consideration the emission spectrum of the MDHL, our results show that the processes induced by photons in CO ice from a broad energy range are different and more complex than the sum of individual processes induced by monochromatic sources spanning the same energy range, as a result of the existence of multistate electronic transitions and discrepancy in absorption cross sections between parent molecules and products in the Ly-α and H{sub 2} molecular emission ranges.

  3. Experimental Study on the Sensitive Emission Lines Intensities of Metal Samples Using Laser Ablation Technique and Its Comparison to Arc Discharge Technique

    Directory of Open Access Journals (Sweden)

    Eko Susilowati

    2004-05-01

    Full Text Available An experimental study has been carried out to measure the sensitive emission lines intensities of several metal samples (copper, zinc, silver, gold, gallium, nickel, silicone and iron using laser ablation technique conducted in low pressure surrounding gas by means of Laser Induced Shock Wave Plasma Spectroscopy (LISPS and in atmospheric pressure region using Laser Induced Breakdown Spectroscopy (LIBS. In both cases the Nd-YAG laser was operated at its fundamental wavelength of 1,064 nm with pulse duration of 8 ns and its intensity tightly focused on the metal samples in helium or air as an ambient gas. The laser energy was fixed at approximately 100 mJ using a set of neutral density filters placed tilted in front of the laser output window. The result of the intensity measurements showed a good agreement which those obtained using arc discharge technique as shown in Massachusetts Institute of Technology Wavelength Table. Further evaluation of these results on the basis of standard deviation leads to the conclusion that LISPS is more favorable for quantitative analysis compared to LIBS. It was further shown that replacing air by helium gas at low pressure improve to some extent the LISPS reproducibility and sensitivity.

  4. INTENSE ENERGETIC GAS DISCHARGE

    Science.gov (United States)

    Luce, J.S.

    1960-03-01

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

  5. On the features of bursts of neutrons, hard x-rays and alpha-particles in the pulse vacuum discharge with a virtual cathode and self-organization

    Science.gov (United States)

    Kurilenkov, Yu K.; Tarakanov, V. P.; Gus'kov, S. Yu; Samoylov, I. S.; Ostashev, V. E.

    2015-11-01

    In this paper, we continue the discussion of the experimental results on the yield of DD neutrons and hard x-rays in the nanosecond vacuum discharge (NVD) with a virtual cathode, which was started in the previous article of this issue, and previously (Kurilenkov Y K et al 2006 J. Phys. A: Math. Gen. 39 4375). We have considered here the regimes of very dense interelectrode aerosol ensembles, in which diffusion of even hard x-rays is found. The yield of DD neutrons in these regimes is conditioned not only by the head-on deuteron-deuteron collisions in the potential well of virtual cathode, but also by the channel of “deuteron-deuterium cluster” reaction, which exceeds overall yield of neutrons per a shot by more than an order of magnitude, bringing it up to ∼ 107/(4π). Very bright bursts of hard x-rays are also represented and discussed here. Presumably, their nature may be associated with the appearance in the NVD of some properties of random laser in the x-ray spectrum. Good preceding agreeing of the experiment on the DD fusion in the NVD with its particle-in-cell (PIC) simulations provides a basis to begin consideration of nuclear burning “proton-boron” in the NVD, which will be accompanied by the release of alpha particles only. With this objective in view, there has been started the PIC-simulation of aneutronic burning of p-B11, and its preliminary results are presented.

  6. 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.

  7. Vacuum electronics

    CERN Document Server

    Eichmeier, Joseph A

    2008-01-01

    Nineteen experts from the electronics industry, research institutes and universities have joined forces to prepare this book. ""Vacuum Electronics"" covers the electrophysical fundamentals, the present state of the art and applications, as well as the future prospects of microwave tubes and systems, optoelectronics vacuum devices, electron and ion beam devices, light and X-ray emitters, particle accelerators and vacuum interrupters. These topics are supplemented by useful information about the materials and technologies of vacuum electronics and vacuum technology.

  8. 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.

  9. APPROXIMATE CALCULATION OF ACTIVE RESISTANCE AND TEMPERATURE OF THE PULSE ELECTRIC ARC CHANNEL IN A HIGH-CURRENT DISCHARGE CIRCUIT OF A POWERFUL HIGH-VOLTAGE CAPACITOR ENERGY STORAGE

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2017-08-01

    Full Text Available Purpose. To obtain calculation correlations for active resistance Rce and maximal temperature Tme of plasma channel of pulse electric arc in the air double-electrode system (DES with metal (graphite electrodes, and also practical approbation of the obtained correlations for Rce and Tme in the conditions of high-voltage laboratory on the powerful capacity energy storage (CES of electric setting, intended for reproducing on the electric loading of protracted C- component of current of artificial lightning with the USA rationed on normative documents by amplitude-temporal parameters (ATP. Methodology. Electrophysics bases of high-voltage impulse technique, scientific and technical bases of development and creation of high-voltage high-current impulse electrical equipment, including powerful CES, and also measuring methods in discharge circuits of powerful high-voltage CES of pulse currents of millisecond temporal range. Results. On the basis of engineering approach the new results of approximate calculation of values of Rce and Tme are resulted in the plasma channel of pulse electric arc discharge in air DES of atmospheric pressure with metallic (graphite electrodes. Practical approbation of results of calculation of values of Rce and Tme is executed as it applies to air DES, to connected in a discharge circuit of powerful high-voltage CES with protracted C- of component current of artificial lightning, characterized rationed ATP. It is shown that calculation of numeral value Rce approximately in 100 times exceeds the proper value of active resistance for the plasma channel of impulsive spark of electric discharge in air DES other things being equal, and a calculation of numeral value Tme well corresponds with the known thermodynamics information for classic electric arc in air DES of atmospheric pressure with graphite electrodes. Originality. New engineering approach is developed for the approximate calculation of values of Rce and Tme in electron

  10. ???????? ??????? ???????? ????? ?? ?????? ArcGIS ??? ?????? ??????????????? ?????????? ????? ???????????? ?????????? ???????????

    OpenAIRE

    ?????, ?.; ???????????, ?.; ????????, ?.

    2016-01-01

    ?????????? ?????? ????????? ???????????????? ??????? ??? ???????? ????? ??? ???????????? ????????? ????? ?????? ?? ????????? ???????????? ?????????? ???????????. ??????? ??????? ??????? ???????, ???????????? ?? ???? ??????????? ???????????? ArcGIS. ?????????? ?????????? ?????????? ???????? ?? ??????????? ?????????? ? ????????????? ??????? ArcGIS Online ?? ??????? Collector for ArcGIS. ???????? ???? ???????? ????????????????? ??????? ??? ????? ?????? ? ?????????????? ?????? ????? ???????? ?? ?...

  11. Vacuum extraction

    DEFF Research Database (Denmark)

    Maagaard, Mathilde; Oestergaard, Jeanett; Johansen, Marianne

    2012-01-01

    Objectives. To develop and validate an Objective Structured Assessment of Technical Skills (OSATS) scale for vacuum extraction. Design. Two part study design: Primarily, development of a procedure-specific checklist for vacuum extraction. Hereafter, validationof the developed OSATS scale for vacuum...

  12. 14 CFR 29.1433 - Vacuum systems.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vacuum systems. 29.1433 Section 29.1433... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Miscellaneous Equipment § 29.1433 Vacuum systems. (a... the discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe...

  13. 14 CFR 25.1433 - Vacuum systems.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vacuum systems. 25.1433 Section 25.1433... STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1433 Vacuum systems. There... discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe. ...

  14. 2D arc-PIC code description: methods and documentation

    CERN Document Server

    Timko, Helga

    2011-01-01

    Vacuum discharges are one of the main limiting factors for future linear collider designs such as that of the Compact LInear Collider. To optimize machine efficiency, maintaining the highest feasible accelerating gradient below a certain breakdown rate is desirable; understanding breakdowns can therefore help us to achieve this goal. As a part of ongoing theoretical research on vacuum discharges at the Helsinki Institute of Physics, the build-up of plasma can be investigated through the particle-in-cell method. For this purpose, we have developed the 2D Arc-PIC code introduced here. We present an exhaustive description of the 2D Arc-PIC code in two parts. In the first part, we introduce the particle-in-cell method in general and detail the techniques used in the code. In the second part, we provide a documentation and derivation of the key equations occurring in the code. The code is original work of the author, written in 2010, and is therefore under the copyright of the author. The development of the code h...

  15. Effects of oxygen gas flow rates and Ga contents on structural properties of Ga-doped ZnO films prepared by ion-plating with a DC arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Terasako, Tomoaki, E-mail: terasako.tomoaki.mz@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Nomoto, Junichi; Makino, Hisao; Yamamoto, Naoki [Research Institute, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-shi, Kochi 782-8502 (Japan); Shirakata, Sho [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama-shi, Ehime 790-8577 (Japan); Yamamoto, Tetsuya [Research Institute, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-shi, Kochi 782-8502 (Japan)

    2015-12-01

    Structural properties of highly c-axis oriented polycrystalline Ga-doped ZnO (GZO) films prepared by ion-plating with a DC arc discharge were studied in terms of the oxygen gas flow rate (F{sub O2}) introduced into the chamber during the deposition process and the Ga{sub 2}O{sub 3} content in the GZO sintered pellet. The X-ray diffraction (XRD) measurements revealed that the GZO films have the residual compressive stress along the a-axis direction (in-plane) and the tensile stress along the c-axis direction (out-of-plane). The increase in F{sub O2} or the increase in Ga{sub 2}O{sub 3} content was effective for relaxing the in-plane compressive stress induced by the so-called atomic peening effect. The positive correlation between the carrier concentration (n) and the primitive cell volume (V) would be due to the incorporation of Ga atoms substituting Zn sites (Ga{sub Zn}s) together with the generation of n-type intrinsic defects or complex defects. - Highlights: • Films of Ga-doped ZnO (GZO) films were deposited by ion-plating with a DC arc discharge. • Structural properties of GZO films were examined by X-ray diffraction measurements. • GZO films had the residual compressive stress along the a-axis direction. • There was the correlation between the carrier concentration and the cell volume.

  16. Simulations of Atmospheric Plasma Arcs

    Science.gov (United States)

    Pearcy, Jacob; Chopra, Nirbhav; Jaworski, Michael

    2017-10-01

    We present the results of computer simulation of cylindrical plasma arcs with characteristics similar to those predicted to be relevant in magnetohydrodynamic (MHD) power conversion systems. These arcs, with core temperatures on the order of 1 eV, place stringent limitations on the lifetime of conventional electrodes used in such systems, suggesting that a detailed analysis of arc characteristics will be crucial in designing more robust electrode systems. Simulations utilize results from NASA's Chemical Equilibrium with Applications (CEA) program to solve the Elenbaas-Heller equation in a variety of plasma compositions, including approximations of coal-burning plasmas as well as pure gas discharges. The effect of carbon dioxide injection on arc characteristics, emulating discharges from molten carbonate salt electrodes, is also analyzed. Results include radial temperature profiles, composition maps, and current-voltage (IV) characteristics of these arcs. Work supported by DOE contract DE-AC02-09CH11466.

  17. VACUUM TRAP

    Science.gov (United States)

    Gordon, H.S.

    1959-09-15

    An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

  18. Vacuum Technology

    Energy Technology Data Exchange (ETDEWEB)

    Biltoft, P J

    2004-10-15

    The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.

  19. On Possible Arc Inception on Low Voltage Solar Array

    Science.gov (United States)

    Vayner, Boris

    2015-01-01

    Recent analysis of spacecraft failures during the period of 1990-2013 demonstrated clearly that electrostatic discharges caused more than 8 percent of all registered failures and anomalies, and comprised the most costly losses (25 percent) for operating companies and agencies. The electrostatic discharges on spacecraft surfaces are the results of differential charging above some critical (threshold) voltages. The mechanisms of differential charging are well known, and various methods have been developed to prevent a generation of significant electric fields in areas of triple junctions. For example, low bus voltages in Low Earth Orbit plasma environment and slightly conducting layer over cover-glass (ITO) in Geosynchronous Orbit surroundings are believed to be quite reliable measures to prevent discharges on respective surfaces. In most cases, the vulnerable elements of spacecraft (solar arrays, diode boards, etc.) go through comprehensive ground tests in vacuum chambers. However, tests articles contain the miniscule fragments of spacecraft components such as 10-30 solar cells of many thousands deployed on spacecraft in orbit. This is one reason why manufacturing defects may not be revealed in ground tests but expose themselves in arcing on array surface in space. The other reason for ineffectiveness of discharge preventive measures is aging of all materials in harsh orbital environments. The expected life time of modern spacecraft varies within the range of five-fifteen years, and thermal cycling, radiation damages, and mechanical stresses can result in surface erosion on conductive layers and microscopic cracks in cover-glass sheets and adhesive films. These possible damages may cause significant increases in local electric field strengths and subsequent discharges. The primary discharges may or may not be detrimental to spacecraft operation, but they can produce the necessary conditions for sustained arcs initiation. Multiple measures were developed to prevent

  20. Vacuum mechatronics

    Science.gov (United States)

    Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

    1989-01-01

    The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

  1. Mastectomy - discharge

    Science.gov (United States)

    Breast removal surgery - discharge; Nipple-sparing mastectomy - discharge; Total mastectomy - discharge; Simple mastectomy - discharge; Modified radical mastectomy - discharge; Breast cancer - mastectomy -discharge

  2. Investigations into electrical discharges in gases

    CERN Document Server

    Klyarfel'D, B N

    2013-01-01

    Investigations into Electrical Discharges in Gases is a compilation of scientific articles that covers the advances in the investigation of the fundamental processes occurring in electrical discharges in gases and vapors. The book details the different aspects of the whole life cycle of an arc, which include the initiation of a discharge, its transition into an arc, the lateral spread of the arc column, and the recovery of electric strength after extinction of an arc. The text also discusses the methods for the dynamic measurement of vapor density in the vicinity of electrical discharges, alon

  3. Invariant vacuum

    Science.gov (United States)

    Robles-Pérez, Salvador

    2017-11-01

    We apply the Lewis-Riesenfeld invariant method for the harmonic oscillator with time dependent mass and frequency to the modes of a charged scalar field that propagates in a curved, homogeneous and isotropic spacetime. We recover the Bunch-Davies vacuum in the case of a flat DeSitter spacetime, the equivalent one in the case of a closed DeSitter spacetime and the invariant vacuum in a curved spacetime that evolves adiabatically. In the three cases, it is computed the thermodynamical magnitudes of entanglement between the modes of the particles and antiparticles of the invariant vacuum, and the modification of the Friedmann equation caused by the existence of the energy density of entanglement. The amplitude of the vacuum fluctuations are also computed.

  4. Cosmic vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Chernin, Artur D [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2001-11-30

    Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)

  5. Vacuum II

    CERN Document Server

    Franchetti, G

    2013-01-01

    This paper continues the presentation of pumps begun in ‘Vacuum I’. The main topic here is gauges and partial-pressure measurements. Starting from the kinetics of gases, the various strategies for measuring vacuum pressures are presented at an introductory level, with some reference to hardware devices. Partial-pressure measurement techniques are introduced, showing that the principles of ion selection have a direct similarity to particle dynamics in accelerators.

  6. High thrust-to-power ratio micro-cathode arc thruster

    Directory of Open Access Journals (Sweden)

    Joseph Lukas

    2016-02-01

    Full Text Available The Micro-Cathode Arc Thruster (μCAT is an electric propulsion device that ablates solid cathode material, through an electrical vacuum arc discharge, to create plasma and ultimately produce thrust in the μN to mN range. 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. A preliminary set of experiments were conducted to show that, at the same power level, thrust may increase by utilizing an ablative anode. It was shown that ablative anode particles were found on a collection plate, compared to no particles from a non-ablative anode, while another experiment showed an increase in ion-to-arc current by approximately 40% at low frequencies compared to the non-ablative anode. Utilizing anode ablation leads to an increase in thrust-to-power ratio in the case of the μCAT.

  7. 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

  8. INFLUENCE OF THE MAGNETIC FIELD OF THE CONDUCTOR ON THE METAL CURRENT AT THE WIRE END FACE IN THE ARC DISCHARGE

    Directory of Open Access Journals (Sweden)

    A. V. Yershov

    2013-12-01

    Full Text Available The influence of the intrinsic magnetic field of current-carrying wire, the anode and the magnetic field of an electric arc to the viscous flow of the liquid metal at the end of the wire was considered. It is shown that when the direction of the current at the end of the wire-anode changes the asymmetry of magnetic field distribution arises, that leads to an acceleration of the liquid metal flow. By using the equations of magneto-hydrodynamics the additional stress caused by viscous friction of unbalanced electromagnetic forces was found. It is shown that the shear stress in the flow of molten metal was formed under the joint action of the electromagnetic and gas dynamic forces. It was determined that the film thickness in the flow of molten metal only under the influence of the electromagnetic force is lower than the influence of the gas dynamic forces. The conclusion shows that under the above conditions, the influence of the electromagnetic forces on the film thickness of the liquid metal is significantly superior to gas-dynamic friction.

  9. Conductive Bands Diminish Electrostatic Discharges

    Science.gov (United States)

    Leung, Philip L.; Whittlesey, Albert

    1992-01-01

    Electrostatic discharges on surfaces covered with electrically insulating paints reduced by connecting edges of painted surfaces to electrical grounds with band of conductive material. Prevents charge build up on paint which eventually arcs to conductive surface, damaging structures and equipment.

  10. Mechanism of surface modification in the plasma surface interaction in electrical arcs

    CERN Document Server

    Timko, Helga; Djurabekova, Flyura; Nordlund, Kai; Matyash, Konstantin; Schneider, Ralf; Toerklep, Anders; Arnau-Izquierdo, Gonzalo; Descoeudres, Antoine; Calatroni, Sergio; Taborelli, Mauro; Wuensch, Walter

    2010-01-01

    Electrical sparks and arcs are plasma discharges that carry large currents and can strongly modify surfaces. This damage usually comes in the form of micrometer-sized craters and frozen-in liquid on the surface. Using a combination of experiments, plasma and atomistic simulation tools, we now show that the observed formation of deep craters and liquidlike features during sparking in vacuum is explained by the impacts of energetic ions, accelerated under the given conditions in the plasma sheath to kiloelectron volt energies, on surfaces. The flux in arcs is so high that in combination with kiloelectron volt energies it produces multiple overlapping heat spikes, which can lead to cratering even in materials such as Cu, where a single heat spike normally does not.

  11. Mechanism of surface modification in the plasma-surface interaction in electrical arcs

    CERN Document Server

    Timko, H; Nordlund, K; Costelle, L; Matyash, K; Schneider, R; Toerklep, A; Arnau-Izquierdo, G; Descoeudres, A; Calatroni, S; Taborelli, M; Wuensch, W

    2010-01-01

    Electrical sparks and arcs are plasma discharges that carry large currents and can strongly modify surfaces. This damage usually comes in the form of micrometer-sized craters and frozen-in liquid on the surface. Using a combination of experiments, plasma and atomistic simulation tools, we now show that the observed formation of deep craters and liquidlike features during sparking in vacuum is explained by the impacts of energetic ions, accelerated under the given conditions in the plasma sheath to kiloelectron volt energies, on surfaces. The flux in arcs is so high that in combination with kiloelectron volt energies it produces multiple overlapping heat spikes, which can lead to cratering even in materials such as Cu, where a single heat spike normally does not.

  12. Vacuum Valve

    CERN Multimedia

    1974-01-01

    This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.

  13. Diffuse coplanar surface barrier discharge -- basic properties and its application in surface treatment of nonwovens

    Science.gov (United States)

    Kovacik, Dusan; Rahel, Jozef; Kubincova, Jana; Zahoranova, Anna; Cernak, Mirko

    2009-10-01

    In recent years, low temperature atmospheric pressure plasma surface treatments have become a hot topic because of the potential of fast and efficient in-line processing fabrication without expensive vacuum equipment. A major problem of atmospheric pressure treatment in air is insufficient treatment uniformity because, particularly at the higher plasma power densities, the air plasma has the tendency of filamentation and transition into an arc discharge. Diffuse coplanar surface barrier discharge (DCSBD) plasma source has been developed to overcome these problems. This type of discharge enables to generate macroscopically homogeneous thin (˜ 0.3 mm) plasma layer with power density of some 100 W/cm^3 practically in any gas without admixture of He. It was found that the ambient air plasma of DCSBD is capable to make lightweight polypropylene nonwoven fabrics permanently hydrophilic, without any pinholing and with low power consumption of some 1 kWh/kg.

  14. Stability of alternating current gliding arcs

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Salewski, Mirko; Leipold, Frank

    2014-01-01

    A gliding arc is a quenched plasma that can be operated as a non-thermal plasma at atmospheric pressure and that is thus suitable for large-scale plasma surface treatment. For its practical industrial use the discharge should be extended stably in ambient air. A simple analytical calculation based...... on Ohm’s law indicates that the critical length of alternating current (AC) gliding arc discharge columns can be larger than that of a corresponding direct current (DC) gliding arc. This finding is supported by previously published images of AC and DC gliding arcs. Furthermore, the analysis shows...... that the critical length can be increased by increasing the AC frequency, decreasing the serial resistance and lowering the gas flow rate. The predicted dependence of gas flow rate on the arc length is experimentally demonstrated. The gap width is varied to study an optimal electrode design, since the extended non...

  15. Quasi-equilibrium channel model of an constant current arc

    OpenAIRE

    Gerasimov Alexander V.; Kirpichnikov Alexander P.

    2003-01-01

    The rather simple method of calculation of electronic and gas temperature in the channel of arc of plasma generator is offered. This method is based on self-consistent two-temperature channel model of an electric arc. The method proposed enables to obtain radial allocation of gas and electronic temperatures in a non-conducting zone of an constant current arc, for prescribed parameters of discharge (current intensity and power of the discharge), with enough good precision. The results obtained...

  16. Hypergravity effects on glide arc plasma

    NARCIS (Netherlands)

    Sperka, J.; Soucek, P.; van Loon, J.J.W.A.; Dowson, A.; Schwarz, C.; Krause, J.; Kroesen, G.; Kudrle, V.

    2013-01-01

    The behaviour of a special type of electric discharge - the gliding arc plasma - has been investigated in hypergravity (1g-18g) using the Large Diameter Centrifuge (LDC) at ESA/ESTEC. The discharge voltage and current together with the videosignal from a fast camera have been recorded during the

  17. Physical characteristics of welding arc ignition process

    Science.gov (United States)

    Shi, Linan; Song, Yonglun; Xiao, Tianjiao; Ran, Guowei

    2012-07-01

    The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack. The tungsten inert gas(TIG) touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system. The changing phenomenon of main ionized element provided the electrons in the arc ignition is found. The metallic element is the main contributor to provide the electrons at the beginning of the discharging, and then the excitated shielding gas element replaces the function of the metallic element. The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα. Through the discussion with the repeatability in relaxation phenomenon, the statistical regularity in the arc ignition process is analyzed. The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas(MIG) arc ignition experiments. This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.

  18. Design of the Vacuum Feedthrough for the EAST ICRF Antenna

    Science.gov (United States)

    Yang, Qingxi; Song, Yuntao; Wu, Songtao; Zhao, Yanping

    2011-04-01

    Detailed design of the vacuum feedthrough for the ion cyclotron radio frequency (ICRF) antenna in EAST, along with an electro-analysis and thermal structural analysis, is presented. The electric field, the voltage standing wave ratio (VSWR) and the stresses in the vacuum feedthrough are studied. A method using the rings of oxygen-free copper as the cushion and macro-beam plasma arc welding is applied in the assembly to protect the ceramic from being damaged during welding. The vacuum leak test on the prototype of vacuum feedthrough is introduced.

  19. Fluid simulation of carbon arc plasma

    Science.gov (United States)

    Hara, Kentaro; Raitses, Yevgeny; Kaganovich, Igor

    2016-09-01

    An arc discharge using graphite electrodes is known to produce carbon nanomaterials, e.g. nanotubes and fullerenes. In order to understand where and how such nanomaterials are synthesized, the plasma properties inside the arc discharge must be characterized. The mechanism of the carbon arc plasma is as follows. Carbon particles evaporate from the graphite anode, which is mainly heated by the electrons. Carbon atoms and ions condensate and form a deposit on the cathode, from which the electrons are thermionically emitted. A one-dimensional fluid model is developed to study the characteristics of the carbon arc plasma in atmospheric pressures. Sheath models for the anode and cathode are coupled to the fluid simulation to obtain the material temperature and sheath potential. In the model, thermal nonequilibrium is assumed and atomic carbon, dimer, and trimer are considered. A typical operating condition of a carbon arc plasma is discharge voltage of 20 V, discharge current of 60 A, the electron radius of 6 to 12 mm, and background pressure of 500 Torr. Transition from low to high ablation mode is obtained from the simulations with a smaller electrode radius and with a larger discharge current, which agrees with experimental observations. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  20. Pancreatitis - discharge

    Science.gov (United States)

    Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... You were in the hospital because you have pancreatitis. This is a swelling of the pancreas. You ...

  1. Vacuum phenomenon.

    Science.gov (United States)

    Yanagawa, Youichi; Ohsaka, Hiromichi; Jitsuiki, Kei; Yoshizawa, Toshihiko; Takeuchi, Ikuto; Omori, Kazuhiko; Oode, Yasumasa; Ishikawa, Kouhei

    2016-08-01

    This article describes the theory of the formation of the vacuum phenomenon (VP), the detection of the VP, the different medical causes, the different locations of the presentation of the VP, and the differential diagnoses. In the human body, the cavitation effect is recognized on radiological studies; it is called the VP. The mechanism responsible for the formation of the VP is as follows: if an enclosed tissue space is allowed to expand as a rebound phenomenon after an external impact, the volume within the enclosed space will increase. In the setting of expanding volume, the pressure within the space will decrease. The solubility of the gas in the enclosed space will decrease as the pressure of the space decreases. Decreased solubility allows a gas to leave a solution. Clinically, the pathologies associated with the VP have been reported to mainly include the normal joint motion, degeneration of the intervertebral discs or joints, and trauma. The frequent use of CT for trauma patients and the high spatial resolution of CT images might produce the greatest number of chances to detect the VP in trauma patients. The VP is observed at locations that experience a traumatic impact; thus, an analysis of the VP may be useful for elucidating the mechanism of an injury. When the VP is located in the abdomen, it is important to include perforation of the digestive tract in the differential diagnosis. The presence of the VP in trauma patients does not itself influence the final outcome.

  2. Quasi-equilibrium channel model of an constant current arc

    Directory of Open Access Journals (Sweden)

    Gerasimov Alexander V.

    2003-01-01

    Full Text Available The rather simple method of calculation of electronic and gas temperature in the channel of arc of plasma generator is offered. This method is based on self-consistent two-temperature channel model of an electric arc. The method proposed enables to obtain radial allocation of gas and electronic temperatures in a non-conducting zone of an constant current arc, for prescribed parameters of discharge (current intensity and power of the discharge, with enough good precision. The results obtained can be used in model and engineering calculations to estimate gas and electronic temperatures in the channel of an arc plasma generator.

  3. Physical electronics handbook of vacuum physics

    CERN Document Server

    Beck, A H

    2013-01-01

    Handbook of Vacuum Physics, Volume 2, Physical Electronics, discusses the fundamentals of electric discharges in gases. Electrical discharges in gases is used generically to denote the passage of electricity through a gas and implicitly embraces the wide variety of physical phenomena which accompany such a discharge of electricity. The discharge currents may be as small as 10-16A in certain ionization growth studies, or be as large as megamperes in thermonuclear and plasma physics studies. Key topics discussed include collision phenomena in gases; surface phenomena and transport of charged par

  4. HIGH TEMPERATURE VACUUM MIXER

    Directory of Open Access Journals (Sweden)

    E. D. Chertov

    2015-01-01

    Full Text Available The work is devoted to the creation of a new type of mixer to produce homogeneous mixtures of dissimilar materials applied to recycling of housing and communal services waste. The article describes the design of a dual-chamber device of the original high-temperature vacuum mixer, there investigated the processes occurring in the chambers of such devices. The results of theoretical and experimental research of the process of mixing recycled polyethylene with a mixture of "grinded food waste – Eco wool” are presented. The problem of the optimum choice of bending the curvilinear blades in the working volume of the seal, which is achieved by setting their profile in the form of involute arc of several circles of different radii, is examined . The dependences, allowing to define the limits of the changes of the main mode parameters the angular velocity of rotation of the working body of the mixer using two ways of setting the profile of the curvilinear blade mixer are obtained. Represented design of the mixer is proposed to use for a wide range of tasks associated with the mixing of the components with a strongly pronounced difference of physic al chemical properties and, in particular, in the production of composites out of housing and communal services waste.

  5. Overvoltages during switching operations of vacuum switching devices

    Directory of Open Access Journals (Sweden)

    Vukelja Petar

    2013-01-01

    Full Text Available This paper presents the results of experimental studies of voltage phenomena in the switching operations of vacuum switching devices made by various manufacturers in several different configurations of 6 kV, 10 kV, 20 kV and 35 kV networks. During switching-on operations of the inductive loads, re-ignition of the electric arc between the contacts of the vacuum switching devices appears. Each arc ignition appearance leads to overvoltages with gradients close to those of lightning overvoltages. Switching-off operations of the inductive loads with vacuum switching devices leads to the cutting of the current before it passed through a natural zero and the appearance of multiple re-ignition of the arc between their contacts. All this leads to significant overvoltages on the equipment insulation. The analysis of surges in the studied networks, and the measures and means to reduce the stress of isolation are proposed.

  6. Phenomenology of surface arcs on spacecraft dielectric materials

    Science.gov (United States)

    Balmain, K. G.; Gossland, M.; Reeves, R. D.; Kuller, W. G.

    1982-01-01

    For electron beam incidence on large specimens of Kapton thermal blanket material, surface arc discharges are shown to cause damage consisting of punchthrough holes which act as focal points for other types of damage, including subsurface tunnels, blowout holes and surface breakup. Under electron bombardment, dielectric sheet specimens separated by a gap are shown to discharge simultaneously. Teflon specimens which have been brushed or rubbed are shown to exhibit directional guidance of discharge arcs, and this phenomenon has been used to generate straight arcs whose velocities have been measured optically.

  7. 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.

  8. Optical arc sensor using energy harvesting power source

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoo Nam, E-mail: knchoi@inu.ac.kr; Rho, Hee Hyuk, E-mail: rdoubleh0902@inu.ac.kr [Dept. of Information and Telecommunication Engineering Incheon National University Incheon 22012 (Korea, Republic of)

    2016-06-03

    Wireless sensors without external power supply gained considerable attention due to convenience both in installation and operation. Optical arc detecting sensor equipping with self sustaining power supply using energy harvesting method was investigated. Continuous energy harvesting method was attempted using thermoelectric generator to supply standby power in micro ampere scale and operating power in mA scale. Peltier module with heat-sink was used for high efficiency electricity generator. Optical arc detecting sensor with hybrid filter showed insensitivity to fluorescent and incandescent lamps under simulated distribution panel condition. Signal processing using integrating function showed selective arc discharge detection capability to different arc energy levels, with a resolution below 17 J energy difference, unaffected by bursting arc waveform. The sensor showed possibility for application to arc discharge detecting sensor in power distribution panel. Also experiment with proposed continuous energy harvesting method using thermoelectric power showed possibility as a self sustainable power source of remote sensor.

  9. Optical arc sensor using energy harvesting power source

    Science.gov (United States)

    Choi, Kyoo Nam; Rho, Hee Hyuk

    2016-06-01

    Wireless sensors without external power supply gained considerable attention due to convenience both in installation and operation. Optical arc detecting sensor equipping with self sustaining power supply using energy harvesting method was investigated. Continuous energy harvesting method was attempted using thermoelectric generator to supply standby power in micro ampere scale and operating power in mA scale. Peltier module with heat-sink was used for high efficiency electricity generator. Optical arc detecting sensor with hybrid filter showed insensitivity to fluorescent and incandescent lamps under simulated distribution panel condition. Signal processing using integrating function showed selective arc discharge detection capability to different arc energy levels, with a resolution below 17J energy difference, unaffected by bursting arc waveform. The sensor showed possibility for application to arc discharge detecting sensor in power distribution panel. Also experiment with proposed continuous energy harvesting method using thermoelectric power showed possibility as a self sustainable power source of remote sensor.

  10. High Current, High Density Arc Plasma as a New Source for WiPAL

    Science.gov (United States)

    Waleffe, Roger; Endrizzi, Doug; Myers, Rachel; Wallace, John; Clark, Mike; Forest, Cary; WiPAL Team

    2016-10-01

    The Wisconsin Plasma Astrophysics Lab (WiPAL) has installed a new array of nineteen plasma sources (plasma guns) on its 3 m diameter, spherical vacuum vessel. Each gun is a cylindrical, molybdenum, washer-stabilized, arc plasma source. During discharge, the guns are maintained at 1.2 kA across 100 V for 10 ms by the gun power supply establishing a high density plasma. Each plasma source is fired independently allowing for adjustable plasma parameters, with densities varying between 1018 -1019 m-3 and electron temperatures of 5-15 eV. Measurements were characterized using a 16 tip Langmuir probe. The plasma source will be used as a background plasma for the magnetized coaxial plasma gun (MCPG), the Terrestrial Reconnection Experiment (TREX), and as the plasma source for a magnetic mirror experiment. Temperature, density, and confinement results will be presented. This work is supported by the DoE and the NSF.

  11. Main reaction process simulation of hydrogen gas discharge in a ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... ... reactions of hydrogen discharge in small electric vacuum components at low pressure and weak ionization were confirmed. Among the 21 types of reactions in hydrogen discharge process, 11 of them play importnat roles under low pressure and weak ionization in cold cathode electric vacuum device.

  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. Innovation approaches to controlling the electric regimes of electric arc furnaces

    Science.gov (United States)

    Bikeev, R. A.; Serikov, V. A.; Ognev, A. M.; Rechkalov, A. V.; Cherednichenko, V. S.

    2015-12-01

    The processes of current passage in an ac electric arc furnace (EAF) are subjected to industrial experiments and mathematical simulation. It is shown that, when a charge is melted, arcs between charge fragments exist in series with main arc discharges, and these arcs influence the stability of the main arc discharges. The measurement of instantaneous currents and voltages allowed us to perform a real-time calculation of the electrical characteristics of a three-phase circuit and to determine the θ parameter, which characterizes the nonlinearity of the circuit segment between electrodes. Based on these studies, we created an advanced system for controlling the electric regime of EAF.

  14. 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.

  15. Acoustic characteristics of electric arc furnaces

    Science.gov (United States)

    Cherednichenko, V. S.; Bikeev, R. A.; Cherednichenko, A. V.; Ognev, A. M.

    2016-06-01

    A mathematical model is constructed to describe the appearance and development of the noise characteristics of superpower electric arc furnaces. The noise formation is shown to be related to the pulsation of the axial plasma flows in arc discharges because of the electrodynamic pressure oscillations caused by the interaction of the self-magnetic field with the current passing in an arc. The pressure in the arc axis changes at a frequency of 100 Hz at the maximum operating pressure of 66 kPa for an arc current of 80 kA. The main ac arc sound frequencies are multiples of 100 Hz, which is supported in the practice of operation of electric arc furnaces. The sound intensity in the furnace laboratory reaches 160 dB and is decreased to 115-120 dB in the working furnace area due to shielding by the furnace jacket, the molten metal, and the molten slag. The appropriateness of increasing the hermetic sealing of electric furnaces and creating furnaces operating at low currents and high transformer voltages is corroborated.

  16. Comparative study on interactions between laser and arc plasma during laser-GTA welding and laser-GMA welding

    Science.gov (United States)

    Chen, Minghua; Xu, Jiannan; Xin, Lijun; Zhao, Zuofu; Wu, Fufa

    2016-10-01

    This paper describes an investigation on differences in interactions between laser and arc plasma during laser-gas tungsten arc (LT) welding and laser-gas metal arc (LM) welding. The characteristics of LT heat source and LM heat source, such as plasma behavior, heat penetration ability and spectral information were comparably studied. Based on the plasma discharge theory, the interactions during plasma discharge were modeled and analyzed. Results show that in both LT and LM welding, coupling discharge between the laser keyhole plasma and arc happens, which strongly enhance the arc. But, the enhancing effect in LT welding is much more sensitive than that in LM welding when parameters are adjusted.

  17. Nanoscale Vacuum Channel Transistor.

    Science.gov (United States)

    Han, Jin-Woo; Moon, Dong-Il; Meyyappan, M

    2017-04-12

    Vacuum tubes that sparked the electronics era had given way to semiconductor transistors. Despite their faster operation and better immunity to noise and radiation compared to the transistors, the vacuum device technology became extinct due to the high power consumption, integration difficulties, and short lifetime of the vacuum tubes. We combine the best of vacuum tubes and modern silicon nanofabrication technology here. The surround gate nanoscale vacuum channel transistor consists of sharp source and drain electrodes separated by sub-50 nm vacuum channel with a source to gate distance of 10 nm. This transistor performs at a low voltage (3 microamperes). The nanoscale vacuum channel transistor can be a possible alternative to semiconductor transistors beyond Moore's law.

  18. Heart bypass surgery - discharge

    Science.gov (United States)

    Off-pump coronary artery bypass - discharge; OPCAB - discharge; Beating heart surgery - discharge; Bypass surgery - heart - discharge; CABG - discharge; Coronary artery bypass graft - discharge; Coronary artery ...

  19. Indian Vacuum Society: The Indian Vacuum Society

    Science.gov (United States)

    Saha, T. K.

    2008-03-01

    The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

  20. Bronchiolitis - discharge

    Science.gov (United States)

    RSV bronchiolitis - discharge; Respiratory syncytial virus bronchiolitis - discharge ... Your child has bronchiolitis , which causes swelling and mucus to build up in the smallest air passages of the lungs. In the hospital, ...

  1. Angina - discharge

    Science.gov (United States)

    ... also learn how to take care of your heart disease . Diet and lifestyle Try to limit how much alcohol ... surgery - discharge Heart bypass surgery - minimally invasive - discharge Heart disease - risk ... Review Date 8/2/2016 Updated by: Michael ...

  2. Modification of Ultra-High Vacuum Surfaces Using Free Radicals

    CERN Document Server

    Vorlaufer, G

    2002-01-01

    In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption of surface adsorbates are usually the factors which determine pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchrotron radiation and bombardment by energetic ions and electrons, surface properties like the molecular desorption yield or secondary electron yield can strongly influence the performance of the accelerator. Well-established treatment methods like vacuum bake-out or glow-discharge cleaning have been successfully applied in the past to condition ultra-high vacuum surfaces, but these methods are sometimes difficult to carry out, for example if the vacuum chambers are not accessible. In this work, an alternative treatment method is investigated. This method is based on the strong chemical reactivity of free radicals, electrically neutral fragments of molecules. Free radicals (in the case of this work, nitrogen and oxygen radi...

  3. Alternating current carrying features of copper spot-contacts with powder contamination produced by arc discharges in SF sub 6 gas. SF sub 6 bunkai seiseibutsu ga kaizaishita do ten sesshokushi no koryu denryu tsuden tokusei ni kansuru jikken teki kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Aichi, H.; Satone, H. (Daido Inst. of Tech., Nagoya (Japan)); Matsumura, T. (Kyoto Univ., Kyoto (Japan)); Kito, Y. (Nagoya Univ., Nagoya (Japan)); Mukaiyama, Y.; Takagi, I. (Chubu Electric Power Co. Inc., Nagoya (Japan))

    1991-05-20

    The voltage and its waveform were experimentally investigated when alternating current was carried by copper spot-contacts contaminated by the powder products produced between them by the arc discharge or the like in SF {sub 6}. The voltage between the contacts and the abnormal phenomena of its waveform were studied when the decomposed product powder of SF {sub 6} adhered the contact area. It was observed that the waveform of the voltage is square in the early stage of current carrying which becomes triangular with the increases in current carrying and passage of time, and then changes further into sinusoidal form. As a result, it was confirmed that the square and triangular voltage waveforms were produced because the spot-contacts are contaminated with powder substances. 4 refs., 9 figs., 1 tab.

  4. DC arc weld starter

    Science.gov (United States)

    Campiotti, Richard H.; Hopwood, James E.

    1990-01-01

    A system for starting an arc for welding uses three DC power supplies, a high voltage supply for initiating the arc, an intermediate voltage supply for sustaining the arc, and a low voltage welding supply directly connected across the gap after the high voltage supply is disconnected.

  5. The vacuum disconnector

    Energy Technology Data Exchange (ETDEWEB)

    Schellekens, H.

    1989-05-01

    After showing the extended experience of Holec with vacuum disconnectors, the difficulties encountered in developing the type SVS vacuum bottle are indicated. The implications of demands imposed on price and dimensions are translated into design features. The function and the design of the getter is explained to show how Holec guarantees a 20 year approved vacuum in the bottle. Finally, the results of switching tests are mentioned to explain the reliability and capability of the new disconnector. 12 figs.

  6. Cardiac catheterization - discharge

    Science.gov (United States)

    Catheterization - cardiac - discharge; Heart catheterization - discharge: Catheterization - cardiac; Heart catheterization; Angina - cardiac catheterization discharge; CAD - cardiac catheterization discharge; Coronary ...

  7. Discharging test of electric power harness

    OpenAIRE

    Kawakita, Shiro; Takahashi, Masato; Kusawake, Hiroaki; Kuwajima, Saburo; 川北 史朗; 高橋 真人; 艸分 宏晶; 桑島 三郎

    2004-01-01

    The mechanism of electric power failure of a satellite has been researched. There are many reasons of loss of electric power of a satellite. Investigated was the power loss due to the sustained arc between primary power cables. The heat though arc tracking between the hot and return cables by secondary are discharge made them burn out. If the phenomenon were occurred in space, the satellite would suffer great damage.

  8. Vacuum Large Current Parallel Transfer Numerical Analysis

    Directory of Open Access Journals (Sweden)

    Enyuan Dong

    2014-01-01

    Full Text Available The stable operation and reliable breaking of large generator current are a difficult problem in power system. It can be solved successfully by the parallel interrupters and proper timing sequence with phase-control technology, in which the strategy of breaker’s control is decided by the time of both the first-opening phase and second-opening phase. The precise transfer current’s model can provide the proper timing sequence to break the generator circuit breaker. By analysis of the transfer current’s experiments and data, the real vacuum arc resistance and precise correctional model in the large transfer current’s process are obtained in this paper. The transfer time calculated by the correctional model of transfer current is very close to the actual transfer time. It can provide guidance for planning proper timing sequence and breaking the vacuum generator circuit breaker with the parallel interrupters.

  9. Characteristics of a miniature vacuum spark

    Science.gov (United States)

    Wong, C. S.; Ong, C. X.; Chin, O. H.; Lee, S.; Choi, P.

    1989-12-01

    The characteristics of a miniature vacuum spark device are investigated. It is powered by a 2-stage 50 kV Marx and operated without an external triggering source. Discharge initiation is effected by an electron beam produced by the Pseudospark effect behind the hollow cathode. For discharges performed in air at a pressure of below 10-2 mbar, intense X-ray is detected. Although this X-ray has been found to consist of predominantly the Fe-Kα line produced by the electron beam bombardment of the stainless steel anode, its high intensity, singly-pulsed short-duration temporal structure and nearly monochromatic spectrum make the present vacuum spark an ideal pulsed X-ray source for many applications. The device is also compact, low cost and easy to operate. As an example of its applications, the contact radiography of a living lizard has been obtained using this X-ray source.

  10. Vacuum arc plasma thrusters with inductive energy storage driver

    Science.gov (United States)

    Krishnan, Mahadevan (Inventor)

    2009-01-01

    A plasma thruster with a cylindrical inner and cylindrical outer electrode generates plasma particles from the application of energy stored in an inductor to a surface suitable for the formation of a plasma and expansion of plasma particles. The plasma production results in the generation of charged particles suitable for generating a reaction force, and the charged particles are guided by a magnetic field produced by the same inductor used to store the energy used to form the plasma.

  11. Microfabricated triggered vacuum switch

    Science.gov (United States)

    Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  12. Insulation vacuum and beam vacuum overpressure release

    CERN Document Server

    Parma, V

    2009-01-01

    There is evidence that the incident of 19th September caused a high pressure build-up inside the cryostat insulation vacuum which the existing overpressure devices could not contain. As a result, high longitudinal forces acting on the insulation vacuum barriers developed and broke the floor and the floor fixations of the SSS with vacuum barriers. The consequent large longitudinal displacements of the SSS damaged chains of adjacent dipole cryo-magnets. Estimates of the helium mass flow and the pressure build- up experienced in the incident are presented together with the pressure build-up for an even more hazardous event, the Maximum Credible Incident (MCI). The strategy of limiting the maximum pressure by the installation of addition pressure relieve devices is presented and discussed. Both beam vacuum lines were ruptured during the incident in sector 3-4 giving rise to both mechanical damage and pollution of the system. The sequence, causes and effects of this damage will be briefly reviewed. We will then an...

  13. Rethinking Recycling in Arcs

    Science.gov (United States)

    Kelemen, P.; Behn, M. D.; Jagoutz, O.

    2012-12-01

    Hacker et al EPSL 2011 and Behn et al Nature Geosci 2011 investigated pathways for return of buoyant, subducted material to arc crust. These include (1) diapirs rising into the hot mantle wedge, with extensive melts adding a component to arc magmas, (2) flow of material back up a relatively cold "subduction channel", adding solids to the lower crust and small-degree partial melts to the upper crust, (3) flow from the forearc along the base of arc crust, and (4) imbrication of forearc material into arc crust. These processes add felsic, incompatible-element-rich components to arc crust. The flux of incompatible elements such as Th in arc lavas, thought to be mainly recycled from subducted sediments, is > sediment subduction flux. There are large uncertainties: arc crustal growth rates are imprecise; young, primitive arc lavas may not be representative of magmatic flux into arc crust; sediment subduction flux may have varied. Nevertheless, this result is found for all arcs examined, using recently published growth rates. Perhaps arc growth rates that include subduction erosion are systematically overestimated. Instead or in addition, maybe significant Th comes from material other than sediments. Here, we consider the implications of pathways 1-4 for arc growth rates and incompatible element enrichment, in the context of subduction erosion and arc-arc collision. Subducting arc lithologies can become separated, with only felsic components returned to arc crust. Buoyant lithologies are mobile in viscous instabilities at > 700-800°C. Whereas thin layers such as sediments may become mobile all at once, instabilities may periodically strip the hottest parts from the top of thick buoyant layers, replacing them with hot mantle. In arc-arc collision, the top of a subducting plate starts at about 0°C on the seafloor, so heating is slow. In subduction erosion, forearc material in the subducting package can be > 200°C before erosion so buoyant lithologies reach 700-800

  14. Arc initiation in cathodic arc plasma sources

    Science.gov (United States)

    Anders, Andre

    2002-01-01

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

  15. NIPPLE DISCHARGE

    Directory of Open Access Journals (Sweden)

    T. N. Bukharova

    2008-01-01

    Full Text Available According to the data available in the literature, as high as 50% of women have benign breast tumors frequently accompanied by nip- ple discharge. Nipple discharge may be serous, bloody, purulent, and colostric. The most common causes are breast abscess, injury, drugs, prolactinoma, intraductal pappiloma, ductal ectasia, intraductal cancer (not more than 10%.

  16. ABOUT FACTORS INFLUENCING ON ELIMINATION OF HYDROGEN IN CIRCULATING VACUUMATOR OF RUP “BMZ” FOR KILLED AND UNKILLED STEELS

    Directory of Open Access Journals (Sweden)

    A. A. Chichko

    2006-01-01

    Full Text Available The characteristics of the vacuum degassing process in RH-vacuumator of RUP are experimentally investigated. The profiles of vacuumator pressure, discharge of argon, metal temperatures and others for different melting processes of cord steel assortment are determined.

  17. 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 ...

  18. Vacuum spin squeezing

    Science.gov (United States)

    Hu, Jiazhong; Chen, Wenlan; Vendeiro, Zachary; Urvoy, Alban; Braverman, Boris; Vuletić, Vladan

    2017-11-01

    We investigate the generation of entanglement (spin squeezing) in an optical-transition atomic clock through the coupling to an optical cavity in its vacuum state. We show that if each atom is prepared in a superposition of the ground state and a long-lived electronic excited state, and viewed as a spin-1/2 system, then the collective vacuum light shift entangles the atoms, resulting in a squeezed distribution of the ensemble collective spin, without any light applied. This scheme reveals that even an electromagnetic vacuum can constitute a useful resource for entanglement and quantum manipulation. By rotating the spin direction while coupling to the vacuum, the scheme can be extended to implement two-axis twisting resulting in stronger squeezing.

  19. Handbook of vacuum technology

    CERN Document Server

    2016-01-01

    This comprehensive, standard work has been updated to remain an important resource for all those needing detailed knowledge of the theory and applications of vacuum technology. With many numerical examples and illustrations to visualize the theoretical issues.

  20. Cold Vacuum Drying Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Located near the K-Basins (see K-Basins link) in Hanford's 100 Area is a facility called the Cold Vacuum Drying Facility (CVDF).Between 2000 and 2004, workers at the...

  1. Vacuum-assisted delivery

    Science.gov (United States)

    ... the birth canal. The vacuum uses a soft plastic cup that attaches to the baby's head with suction. ... a numbing medicine placed in the vagina. The plastic cup will be placed on the baby's head. Then, ...

  2. Ultra high vacuum technology

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    A short introduction for some basic facts and equations. Subsquently, discussion about: Building blocks of an ultrahigh vacuum system - Various types of pumps required to reach uhv and methods to reduce these effects - Outgassing phenomena induced by the presence of a particle beam and the most common methods to reduce these effects It will be given some practical examples from existing CERN accelerators and discuss the novel features of the future LHC vacuum system.

  3. Power vacuum tubes handbook

    CERN Document Server

    Whitaker, Jerry

    2012-01-01

    Providing examples of applications, Power Vacuum Tubes Handbook, Third Edition examines the underlying technology of each type of power vacuum tube device in common use today. The author presents basic principles, reports on new development efforts, and discusses implementation and maintenance considerations. Supporting mathematical equations and extensive technical illustrations and schematic diagrams help readers understand the material. Translate Principles into Specific Applications This one-stop reference is a hands-on guide for engineering personnel involved in the design, specification,

  4. A Planck Vacuum Cosmology

    Directory of Open Access Journals (Sweden)

    Daywitt W. C.

    2009-04-01

    Full Text Available Both the big-bang and the quasi-steady-state cosmologies originate in some type of Planck state. This paper presents a new cosmological theory based on the Planck- vacuum negative-energy state, a state consisting of a degenerate collection of negative- energy Planck particles. A heuristic look at the Einstein field equation provides a con- vincing argument that such a vacuum state could provide a theoretical explanation for the visible universe.

  5. Ear discharge

    Science.gov (United States)

    ... antibiotic medicines, which are placed in the ear. Antibiotics may be given by mouth if a ruptured eardrum from an ear infection is causing the discharge. Alternative Names Drainage from the ear; Otorrhea; Ear bleeding; ...

  6. Osteomyelitis - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000297.htm Osteomyelitis - discharge To use the sharing features on this page, please enable JavaScript. You have osteomyelitis , a bone infection caused by bacteria or other ...

  7. Development of circuit model for arcing on solar panels

    Science.gov (United States)

    Mehta, Bhoomi K.; Deshpande, S. P.; Mukherjee, S.; Gupta, S. B.; Ranjan, M.; Rane, R.; Vaghela, N.; Acharya, V.; Sudhakar, M.; Sankaran, M.; Suresh, E. P.

    2010-02-01

    The increased requirements of payload capacity of the satellites have resulted in much higher power requirements of the satellites. In order to minimize the energy loss during power transmission due to cable loss, use of high voltage solar panels becomes necessary. When a satellite encounters space plasma it floats negatively with respect to the surrounding space plasma environment. At high voltage, charging and discharging on solar panels causes the power system breakdown. Once a solar panel surface is charged and potential difference between surface insulator and conductor exceeds certain value, electrostatic discharge (ESD) may occur. This ESD may trigger a secondary arc that can destroy the solar panel circuit. ESD is also called as primary or minor arc and secondary is called major arc. The energy of minor arc is supplied by the charge stored in the coverglass of solar array and is a pulse of typically several 100 ns to several 100 μs duration. The damage caused by minor arc is less compared to major arcs, but it is observed that the minor arc is cause of major arc. Therefore it is important to develop an understanding of minor arc and mitigation techniques. In this paper we present a linear circuit analysis for minor arcs on solar panels. To study arcing event, a ground experimental facility to simulate space plasma environment has been developed at Facilitation Centre for Industrial Plasma Technologies (Institute for Plasma Research) in collaboration with Indian Space Research Organization's ISRO Satellite Technology Centre (ISAC). A linear circuit model has been developed to explain the experimental results by representing the coverglass, solar cell interconnect and wiring by an LCR circuit and the primary arc by an equivalent LR circuit. The aim of the circuit analysis is to predict the arc current which flows through the arc plasma. It is established from the model that the current depends on various parameters like potential difference between insulator

  8. Cold Beam Vacuum Interconnects for the LHC Insertion Regions

    CERN Document Server

    Ramos, D; Knaster, J R; Veness, R J M

    2004-01-01

    The LHC machine is composed of arcs and insertion regions where superconducting magnets, working at temperatures of 1.9 K and 4.5 K, have flexibly interconnected beam vacuum chambers. These interconnects must respect strict requirements in terms of impedance, aperture, space optimization and reliability. A complete interconnect design was first developed for the arc regions, and from which a total of 20 variants have been created according to the different functional requirements of each pair of cryostats along the machine. All design features and manufacture processes were validated through extensive testing. Manufacture and assembly cost was minimised by using a modular interconnect design, with common components shared among different design variants. A detailed quality assurance structure was implemented in order to achieve the high level of reliability required. This paper presents the layout of cold beam vacuum interconnects along with details of development and testing performed to validate design and ...

  9. The vacuum system for technological unit development and design

    Science.gov (United States)

    Zhukeshov, A. M.; Gabdullina, A. T.; Amrenova, A. U.; Giniyatova, Sh G.; Kaibar, A.; Sundetov, A.; Fermakhan, K.

    2015-11-01

    The paper shows results of development of plasma technological unit on the basis of accelerator of vacuum arc and automated system. During the previous years, the authors investigated the operation of pulsed plasma accelerator and developed unique technologies for hardening of materials. Principles of plasma formation in pulsed plasma accelerator were put into basis of the developed unit. Operation of the pulsed arc accelerator was investigated at different parameters of the charge. The developed vacuum system is designed for production of hi-tech plasma units in high technologies in fields of nanomaterials, mechanical and power engineering and production with high added value. Unlike integrated solutions, the system is a module one to allow its low cost, high reliability and simple maintenance. The problems of use of robots are discussed to modernize the technological process.

  10. TWIN CARBON ARC TORCH

    African Journals Online (AJOL)

    its predominate applications in heating, brazing, and welding have been supplanted by the highly developed oxyacetylene torch. As seen in Fig. l, the twin carbon arc torch (henceforth referred to in this article as simply the carbon-arc torch) consists of a hand held apparatus made of two ('twin') carbon or graphite electrodes ...

  11. Pulsed high voltage discharge induce hematologic changes

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... The aim of this work to examine the effect of the gas-liquid hybrid discharge treatment system on some hematological ... liquid phase. The high energy plasma arc produces a pressure shock wave, electromagnetic radiations, .... through a 50 kilo-ohm resistor by a negative dc high-voltage power supply and ...

  12. Hip fracture - discharge

    Science.gov (United States)

    Inter-trochanteric fracture repair - discharge; Subtrochanteric fracture repair - discharge; Femoral neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - ...

  13. Busbar arcs at large fusion magnets: Conductor to feeder tube arcing model experiments with the LONGARC device

    Energy Technology Data Exchange (ETDEWEB)

    Klimenko, Dmitry, E-mail: dmitry.klimenko@kit.edu; Pasler, Volker

    2014-10-15

    Highlights: •The LONGARC device was successfully implemented for busbar to feeder tubes arcing model experiments. •Arcing at an ITER busbar inside its feeder tube was simulated in scaled model experiments. •The narrower half tubes imply a slight increase of the arc propagation speed in compare to full tube experiments. •All simulated half tubes experiments show severe damage indicating that the ITER inner feeder tube will not withstand a busbar arc. -- Abstract: Electric arcs moving along the power cables (the so-called busbars) of the toroidal field (TF) coils of ITER may reach and penetrate the cryostat wall. Model experiments with the new LONGARC device continue the VACARC (VACuum ARC) experiments that were initiated to investigate the propagation and destruction mechanisms of busbar arcs in small scale [1]. The experiments are intended to support the development and validation of a numerical model. LONGARC overcomes the space limitations inside VACARC and allows also for advanced 1:3 (vs. ITER full scale) model setups. The LONGARC device and first results are presented below.

  14. Vacuum induced photoresist outgassing

    Science.gov (United States)

    Waterman, Justin; Mbanaso, Chimaobi; Denbeaux, Gregory

    2008-03-01

    In order to continue the trend toward smaller feature sizes in lithography, new methods of lithography will be needed. A likely method for printing features 32 nm and smaller is extreme ultraviolet (EUV) lithography. EUV allows for features to be printed that are smaller than the current methods can achieve. However, outgassing of the photoresist is a concern for EUV lithography. The outgassed components can lead to contamination of the optics, degrading the reflectivity and hence lowering throughput of the exposure tools. Outgassing due to EUV exposure has been investigated by many groups. However, there were no complete investigations available of vacuum induced outgassing. In this paper, several methods were employed to investigate the outgassing due to vacuum. It was found that the vacuum induced outgassing outgassed a similar number of molecules as the outgassing due to EUV exposure. Furthermore, almost all of the outgassing was completed after about two minutes in vacuum. To mitigate the potential concern of outgassing due to vacuum causing contamination of optics, this work shows that photoresist coated silicon wafers only require about two minutes of pumping prior to insertion near the optics within EUV lithography tools.

  15. Improving Vacuum Cleaners

    Science.gov (United States)

    1997-01-01

    Under a Space Act Agreement between the Kirby company and Lewis Research Center, NASA technology was applied to a commercial vacuum cleaner product line. Kirby engineers were interested in advanced operational concepts, such as particle flow behavior and vibration, critical factors to improve vacuum cleaner performance. An evaluation of the company 1994 home care system, the Kirby G4, led to the refinement of the new G5 and future models. Under the cooperative agreement, Kirby had access to Lewis' holography equipment, which added insight into how long a vacuum cleaner fan would perform, as well as advanced computer software that can simulate the flow of air through fans. The collaboration resulted in several successes including fan blade redesign and continuing dialogue on how to improve air-flow traits in various nozzle designs.

  16. New design for a microwave discharge lamp.

    Science.gov (United States)

    Glangetas, A

    1980-03-01

    A simple discharge lamp with a microwave cavity fitting inside provides an intense source of VUV resonance radiation for photochemical work inside a vacuum chamber. Good coupling and minimum reabsorption result in better efficiency ( greater, similar1%) and more intense output power (up to 2.5x10(16) quanta s(-1)) than have been achieved previously.

  17. Baryogenesis in false vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta [KEK Theory Center, IPNS, KEK, Tsukuba, Ibaraki (Japan); Yamada, Masatoshi [Kanazawa University, Institute for Theoretical Physics, Kanazawa (Japan)

    2017-09-15

    The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators. (orig.)

  18. A rotating quantum vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Lorenci, V.A. de; Svaiter, N.F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    1996-11-01

    It was investigated which mapping has to be used to compare measurements made in a rotating frame to those made in an inertial frame. Using a non-Galilean coordinate transformation, the creation-annihilation operators of a massive scalar field in the rotating frame are not the same as those of an inertial observer. This leads to a new vacuum state(a rotating vacuum) which is a superposition of positive and negative frequency Minkowski particles. Polarization effects in circular accelerators in the proper frame of the electron making a connection with the inertial frame point of view were analysed. 65 refs.

  19. Handbook of vacuum physics

    CERN Document Server

    1964-01-01

    Handbook of Vacuum Physics, Volume 3: Technology is a handbook of vacuum physics, with emphasis on the properties of miscellaneous materials such as mica, oils, greases, waxes, and rubber. Accurate modern tables of physical constants, properties of materials, laboratory techniques, and properties of commercial pumps, gauges, and leak detectors are presented. This volume is comprised of 12 chapters and begins with a discussion on pump oils, divided into rotary pump oils and vapor pump oils. The next chapter deals with the properties and applications of greases, including outgassing and vapor pr

  20. Influence of DC arc current on the formation of cobalt-based ...

    Indian Academy of Sciences (India)

    The synthesis of cobalt-based magnetic nanostructures using DC arc discharge technique with varying arc current is reported here. ... Facilitation Centre for Industrial Plasma Technologies, Institute for Plasma Research, A-10/B, G.I.D.C. Electronic Estate, Sector-25, Gandhinagar 382 016, India; Department of Physical ...

  1. Achieving ultrahigh vacuum in an unbaked chamber with glow ...

    Indian Academy of Sciences (India)

    Glow discharge conditioning (GDC) has long been accepted as one of the basic wall conditioning techniques for achieving ultrahigh vacuum in an unbaked chamber. As a part of this fundamental experimental study, a test chamber has been fabricated from stainless steel 304 L with its inner surface electropolished on ...

  2. Technology handbook of vacuum physics

    CERN Document Server

    Beck, A H

    2013-01-01

    Handbook of Vacuum Physics, Volume 3: Technology is part of a series of publications that presents articles featuring the whole spectrum of vacuum physics. This particular volume presents materials that deal with technology concerns in vacuum mechanics. The first material talks about the utilization of ceramic materials in the construction of vacuum devices. The next paper details the application of vacuum physics in soldering and brazing process. The last article deals with the utilization of vacuum technology in high frequency heating. The book will be of great use to professionals involved

  3. Optical diagnostics of a gliding arc.

    Science.gov (United States)

    Sun, Z W; Zhu, J J; Li, Z S; Aldén, M; Leipold, F; Salewski, M; Kusano, Y

    2013-03-11

    Dynamic processes in a gliding arc plasma generated between two diverging electrodes in ambient air driven by 31.25 kHz AC voltage were investigated using spatially and temporally resolved optical techniques. The life cycles of the gliding arc were tracked in fast movies using a high-speed camera with framing rates of tens to hundreds of kHz, showing details of ignition, motion, pulsation, short-cutting, and extinction of the plasma column. The ignition of a new discharge occurs before the extinction of the previous discharge. The developed, moving plasma column often short-cuts its current path triggered by Townsend breakdown between the two legs of the gliding arc. The emission from the plasma column is shown to pulsate at a frequency of 62.5 kHz, i.e., twice the frequency of the AC power supply. Optical emission spectra of the plasma radiation show the presence of excited N2, NO and OH radicals generated in the plasma and the dependence of their relative intensities on both the distance relative to the electrodes and the phase of the driving AC power. Planar laser-induced fluorescence of the ground-state OH radicals shows high intensity outside the plasma column rather than in the center suggesting that ground-state OH is not formed in the plasma column but in its vicinity.

  4. LEP Vacuum Chamber

    CERN Multimedia

    1983-01-01

    This is a cut-out of a LEP vacuum chamber for dipole magnets showing the beam channel and the pumping channel with the getter (NEG) strip and its insulating supports. A water pipe connected to the cooling channel can also be seen at the back.The lead radiation shield lining is also shown. See also 8305563X.

  5. The vacuum strikes back

    CERN Multimedia

    2007-01-01

    "Modern physics has shown that the vacuum, previously thought of as a stated of total nothingness, is really a seething background of virtual particles springing in and out of eixstence until they can seize enough energy to materialize as "real" particles." (1,5 page)

  6. LEP vacuum chamber, prototype

    CERN Multimedia

    CERN PhotoLab

    1983-01-01

    Final prototype for the LEP vacuum chamber, see 8305170 for more details. Here we see the strips of the NEG pump, providing "distributed pumping". The strips are made from a Zr-Ti-Fe alloy. By passing an electrical current, they were heated to 700 deg C.

  7. ISR vacuum system

    CERN Multimedia

    CERN PhotoLab

    1971-01-01

    Some of the most important components of the vacuum system are shown. At the left, the rectangular box is a sputter-ion pump inside its bake-out oven. The assembly in the centre includes a sector valve, three roughing valves, a turbomolecular pump, a rotary backing pump and auxiliary equipment. At the right, the small elbow houses a Bayard-

  8. Investigation of the effects of capacity on asbestos vacuum cleaners.

    Science.gov (United States)

    Johnston, W L; Loflin, W J

    1980-12-01

    Nine industrial vacuum cleaners, designed for collection of asbestos waste, were tested to determine how the performance was affected when the manufacturer's specified capacity was approached, attained, and exceeded. This determination was assessed by measurement of the airborne asbestos fiber concentration in the vacuum cleaner discharge air and the change in vacuum cleaner suction pressure. Airborne fiber concentrations were found to be far below the present OSHA standard; however, the suction pressure of each vacuum cleaner dropped considerably as the capacity was approached and/or exceeded. All of the units tested except one were able to contain 25% more than their specified capacity without any internal problems, filtering system failure, or total loss of suction pressure.

  9. Furnace brazing under partial vacuum

    Science.gov (United States)

    Mckown, R. D.

    1979-01-01

    Brazing furnace utilizing partial-vacuum technique reduces tooling requirements and produces better bond. Benefit in that partial vacuum helps to dissociate metal oxides that inhibit metal flow and eliminates heavy tooling required to hold parts together during brazing.

  10. Tritium handling in vacuum systems

    Energy Technology Data Exchange (ETDEWEB)

    Gill, J.T. [Monsanto Research Corp., Miamisburg, OH (United States). Mound Facility; Coffin, D.O. [Los Alamos National Lab., NM (United States)

    1986-10-01

    This report provides a course in Tritium handling in vacuum systems. Topics presented are: Properties of Tritium; Tritium compatibility of materials; Tritium-compatible vacuum equipment; and Tritium waste treatment.

  11. Using of fiber-array diagnostic to measure the propagation of fast axial ionization wave during breakdown of electrically exploding tungsten wire in vacuum

    Science.gov (United States)

    Shi, Huantong; Zou, Xiaobing; Wang, Xinxin

    2017-12-01

    The physical process of electrical explosion of wires in vacuum is featured with the surface discharge along the wire, which generates the corona plasma layer and terminates the Joule heating of the wire core. In this paper, a fiber-array probe was designed to directly measure the radiation of surface arc with spatial and temporal resolution. The radiation of the exploding wire was casted to the section of an optical-fiber-array by a lens and transmitted to PIN diodes and finally collected with an oscilloscope. This probe enables direct diagnostics of the evolution of surface discharge with high temporal resolution and certain spatial resolution. The radiation of a tungsten wire driven by a positive current pulse was measured, and results showed that surface discharge initiates near the cathode and propagates toward the anode with a speed of 7.7 ± 1.6 mm/ns; further estimations showed that this process is responsible for the "conical" structure of the exploding wire.

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

    Science.gov (United States)

    Roberts, F Sloan; Anderson, Scott L

    2013-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-15

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

  14. 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

  15. Nonperturbative QED vacuum birefringence

    Science.gov (United States)

    Denisov, V. I.; Dolgaya, E. E.; Sokolov, V. A.

    2017-05-01

    In this paper we represent nonperturbative calculation for one-loop Quantum Electrodynamics (QED) vacuum birefringence in presence of strong magnetic field. The dispersion relations for electromagnetic wave propagating in strong magnetic field point to retention of vacuum birefringence even in case when the field strength greatly exceeds Sauter-Schwinger limit. This gives a possibility to extend some predictions of perturbative QED such as electromagnetic waves delay in pulsars neighbourhood or wave polarization state changing (tested in PVLAS) to arbitrary magnetic field values. Such expansion is especially important in astrophysics because magnetic fields of some pulsars and magnetars greatly exceed quantum magnetic field limit, so the estimates of perturbative QED effects in this case require clarification.

  16. Vacuum distillation device

    Energy Technology Data Exchange (ETDEWEB)

    Hamer, J.A.; Burg, C.J. Van Der; Kanbier, D.; Heijden, P. Van Der.

    1990-09-18

    This invention relates to a vacuum distillation device comprising a vacuum distillation column, a furnace provided with a heat exchange tube, and a connecting conduit between the column and the heat exchange tube. Such a device is used to fractionate a hydrocarbon-containing feed sometimes referred to as long residue. An object of this invention is to provide a vacuum distillation device which allows vaporization of a major part of the feed upstream of the column inlet. To this end, the device according to the invention comprises a vacuum distillation device as described above, in which the inner diameter of the heat exchange tube increases along its length to between 2.4 and 3 times the inner diameter of the tube inlet, and in which the inner diameter of the connecting conduit gradually increases along its length to between 2.5 and 5.4 times the inner diameter of the tube outlet. During normal operation of the device of the invention, only less than 50 wt % of the feed is vaporized in the heat exchange tube in the furnace, and more feed is vaporized in the connecting conduit, so that at the outlet end of the conduit the feed comprises about 0.9 kg vapor per kg of feed. The invention provides improved heat transfer in the heat exchange tubes such that fouling is reduced, consequently more heat can be applied per unit of time in the heat exchange tube. This allows either heating of the feed to a higher temperature or increasing the throughput for the same temperature.

  17. A comparative study of modelling AC electric arc by one-dimensional interpolation for power system harmonics analysis

    Directory of Open Access Journals (Sweden)

    Liu Yu-Jen

    2016-01-01

    Full Text Available Electric arc is a discharge phenomenon caused by particular electrical events and arc produced facilities in power system, for example the occurrence of short-circuit fault in feeders and the use of electric arc furnace for steel-making. All of these electric arcs have a highly nonlinear nature and can be considered as a significant source of power quality problems. To investigate the impacts of the electric arcs on power quality studies the development of the electric arc models for simulation analysis is became necessary. This paper thus presents the use of different one-dimensional interpolation methods for modelling the alternating current electric arc. The performances of different methods are compared by simulation results that are derived from the modelling of an alternating current electric arc furnace load and a low-frequency fluorescent tube.

  18. PARAFFIN SEPARATION VACUUM DISTILLATION

    Directory of Open Access Journals (Sweden)

    Zaid A. Abdulrahman

    2013-05-01

    Full Text Available Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji-Iraq. The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13 present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the  paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as  the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCAD

  19. Arc characteristics of submerged arc welding with stainless steel wire

    Science.gov (United States)

    Li, Ke; Wu, Zhi-sheng; Liu, Cui-rong; Chen, Feng-hua

    2014-08-01

    The arc characteristics of submerged arc welding (SAW) with stainless steel wire were studied by using Analysator Hannover (AH). The tests were carried out under the same preset arc voltage combined with different welding currents. By comparing the probability density distribution (PDD) curves of arc voltage and welding current, the changes were analyzed, the metal transfer mode in SAW was deduced, and the characteristics of a stable arc were summarized. The analysis results show that, with an increase of welding parameters, the short-circuiting peak in the PDD curves of arc voltage decreases gradually until it disappears, and the dominant metal transfer mode changes from flux-wall guided transfer to projected transfer and then to streaming transfer. Moreover, when the PDD curves of arc voltage are both unimodal and generally symmetrical, the greater the peak probability and the smaller the peak span, the more stable the arc becomes.

  20. Large high-vacuum systems for CERN accelerators

    Science.gov (United States)

    Strubin, P.

    2008-05-01

    CERN operated over the more than 50 years of its existence particle accelerators and storage rings ranging from a few tens of metre to 27 km, the size of its latest project, the Large Hadron Collider (LHC) which is under construction and will be started in 2008. The challenges began with the Intersection Storage Rings (ISR) in the seventies. With a beam pipe length of 2 × 1 km, this accelerator required innovative solutions like bake-out and glow discharge to achieve the required static vacuum level, fight against beam-induced pressure increases and cancel beam neutralisation by trapped electrons. The vacuum system of the Large Electron Positron (LEP) storage ring (in operation between 1989 and 2001) of a total length of 27 km had to cope with very high levels of synchrotron power. The beam vacuum system of LHC (2 × 27 km) integrates some parts at 1.9 K and others at room temperature and will also have to cope with dynamic effects. In addition to the beam vacuum system, LHC requires insulation vacuum for the superconducting magnets and the helium distribution line. Whereas the required pressure is not very low, the leak detection and localisation is significantly more demanding for the insulation vacuum than for the beam vacuum because of the large volumes and the thermal insulation. When the size of an accelerator grows, the difficulties are not only to get a clean and leak tight vacuum system, but also to be able to measure reliably pressure or gas composition over long distances. Furthermore, in the case of LHC the integration of the beam vacuum system was particularly difficult because of the complexity induced by a superconducting magnet scheme and the reduced space available for the beam pipes. Planning and logistics aspects during installation, including the usage of mobile pumping and diagnostic means, were much more difficult to manage in LHC than in previous projects.

  1. Experimental and Numerical Study of the Carbon Arc: Plasma Properties in the Region of Nanotube Synthesis

    Science.gov (United States)

    Vekselman, Vladislav; Khrabry, Alexander; Kaganovich, Igor; Stratton, Brentley; Raitses, Yevgeny

    2017-10-01

    A carbon arc for nanomaterial synthesis was comprehensively studied using spectroscopic techniques and electrical measurements and modeled by specially modified computationally fluid dynamic (CFD) code ANSYS. The carbon arc plasma is generated and sustained by ablation of the graphite anode. In this study the plasma and carbon composition is fully characterized in the synthesis region that is important for understanding of synthesis of carbon nanomaterials by the arc method. We applied planar laser induced fluorescence (LIF) diagnostic to obtain instantaneous distribution of C2 in carbon arc. In addition, the arc was characterized by optical emission spectroscopy (OES) and fast filtered imaging. Results of the current work revealed two main arc plasma regions defined as the arc core and the arc periphery different by composition of carbon species. The core represents the dense and hot plasma region conducting most of the discharge current which is self-consistently sustained. The arc periphery is colder and characterized by intensive formation of carbon molecules. The resulting radial distribution of carbon molecules has a distinguished hollow profile structure which is preserved regardless of the arc stochastic motion realized in some modes. These results are in agreement with results of two dimensional CFD simulations of the carbon arc under operating conditions used in experiments. This work was supported by DOE Contract No. DE-AC02-09CH11466.

  2. 1020 steel coated with Ti/TiN by Cathodic Arc and Ion Implantation

    Science.gov (United States)

    Bermeo, F.; Quintana, J. P.; Kleiman, A.; Sequeda, F.; Márquez, A.

    2017-01-01

    TiN coatings have been widely studied in order to improve mechanical properties of steels. In this work, thin Ti/TiN films were prepared by plasma based immersion ion implantation and deposition (PBII&D) with a cathodic arc on AISI 1020 steel substrates. Substrates were exposed to the discharge during 1 min in vacuum for the deposition of a Tiunderlayer with the aim of improving the adhesion to the substrate. Then, a TiN layer was deposited during 6 min in a nitrogen environment at a pressure of 3xl0-4 mbar. Samples were obtained at room temperature and at 300 °C, and with or without ion implantation in order to analyze differences between the effects of each treatment on the tribological properties. The mechanical and tribological properties of the films were characterized. The coatings deposited by PBII&D at 300 °C presented the highest hardness and young modulus, the best wear resistance and corrosion performance.

  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. Stereotactic radiosurgery - discharge

    Science.gov (United States)

    ... discharge; Linear accelerator - discharge; Lineacs - discharge; Proton beam radiosurgery - discharge ... You received stereotactic radiosurgery (SRS), or radiotherapy. This is a form of radiation therapy that focuses high-powered x-rays onto a small ...

  5. Atrial fibrillation - discharge

    Science.gov (United States)

    Auricular fibrillation - discharge; A-fib - discharge; AF - discharge; Afib - discharge ... Avoid salty and fatty foods. Stay away from fast-food restaurants. ... how to check your pulse, and check it every day. It is better ...

  6. Arc Discharge Ion Source Development at CERN ISOLDE

    CERN Document Server

    Penescu, Liviu; Stora, Thierry; Catherall, Richard; Cata-Danil, Gheorghe

    2010-01-01

    Within a Marie Curie Early Stage Training project at CERN, a detailed study (experimental, analytical and numerical) of the standard ISOLDE FEBIAD ion sources has been done. A new theoretical model global source behavior could be inferred, based on the acquired experimental data. The source model already served to the development of two FEBIAD prototypes which improved the I+ ionization efficiencies for the noble gases by 5 to 20 times (depending on element) This development can now serve to future ion source optimizations, for specific user or facility requirements around the world, especially for the production of high intensity radioactive beams.

  7. 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...

  8. ALICE - ARC integration

    DEFF Research Database (Denmark)

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

    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...

  9. Jeanne d'Arc

    CERN Document Server

    Guillemin,H

    1970-01-01

    L'historien H.Guillemin a fouillé pendant des nombreux mois tous les documents qu'il a pu trouver concernant ce fameux énigme qui était Jeanne d'Arc. Le résultat de ses recherches il a écrit dans un merveilleux livre pour dire la vérité sur Jeanne

  10. The vacuum platform

    Science.gov (United States)

    McNab, A.

    2017-10-01

    This paper describes GridPP’s Vacuum Platform for managing virtual machines (VMs), which has been used to run production workloads for WLCG and other HEP experiments. The platform provides a uniform interface between VMs and the sites they run at, whether the site is organised as an Infrastructure-as-a-Service cloud system such as OpenStack, or an Infrastructure-as-a-Client system such as Vac. The paper describes our experience in using this platform, in developing and operating VM lifecycle managers Vac and Vcycle, and in interacting with VMs provided by LHCb, ATLAS, ALICE, CMS, and the GridPP DIRAC service to run production workloads.

  11. Vacuum ultraviolet spectroscopy I

    CERN Document Server

    Samson, James A; Lucatorto, Thomas

    1998-01-01

    This volume is for practitioners, experimentalists, and graduate students in applied physics, particularly in the fields of atomic and molecular physics, who work with vacuum ultraviolet applications and are in need of choosing the best type of modern instrumentation. It provides first-hand knowledge of the state-of-the-art equipment sources and gives technical information on how to use it, along with a broad reference bibliography.Key Features* Aimed at experimentalists who are in need of choosing the best type of modern instrumentation in this applied field* Contains a detailed chapter on la

  12. R&D ERL: Vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Mapes, M.; Smart, L.; Weiss, D.; Steszyn, A.; Todd, R.

    2010-01-01

    The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the {approx}10{sup -9} torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2{sup o}K is reduced to low 10{sup -11} torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The

  13. Of vacuum and gas

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    A new LHCb programme is delving into uncharted waters for the LHC: exploring how protons interact with noble gases inside the machine pipe. While, at first glance, it may sound risky for the overall quality of the vacuum in the machine, the procedure is safe and potentially very rich in rewards. The results could uncover the high-energy helium-proton cross-section (with all the implications thereof), explore new boundaries of the quark-gluon plasma and much more.   As the beam passes through LHCb, interactions with neon gas allow the experiment to measure the full beam profile. In this diagram, beam 1 (blue) and beam 2 (red) are measured by the surrounding VELO detector. It all begins with luminosity. In 2011, LHCb set out to further improve its notoriously precise measurements of the beam profile, using the so-called Beam-Gas Imaging (BGI) method. BGI does exactly what it says on the tin: a small amount of gas is inserted into the vacuum, increasing the rate of collisions around the interaction ...

  14. LHC vacuum system

    CERN Document Server

    Gröbner, Oswald

    1999-01-01

    The Large Hadron Collider (LHC) project, now in the advanced construction phase at CERN, comprises two proton storage rings with colliding beams of 7-TeV energy. The machine is housed in the existing LEP tunnel with a circumference of 26.7 km and requires a bending magnetic field of 8.4 T with 14-m long superconducting magnets. The beam vacuum chambers comprise the inner 'cold bore' walls of the magnets. These magnets operate at 1.9 K, and thus serve as very good cryo-pumps. In order to reduce the cryogenic power consumption, both the heat load from synchrotron radiation emitted by the proton beams and the resistive power dissipation by the beam image currents have to be absorbed on a 'beam screen', which operates between 5 and 20 K and is inserted inside the vacuum chamber. The design of this beam screen represents a technological challenge in view of the numerous and often conflicting requirements and the very tight mechanical tolerances imposed. The synchrotron radiation produces strong outgassing from the...

  15. Vacuum science, technology, and applications

    CERN Document Server

    Naik, Pramod K

    2018-01-01

    Vacuum plays an important role in science and technology. The study of interaction of charged particles, neutrals and radiation with each other and with solid surfaces requires a vacuum environment for reliable investigations. Vacuum has contributed immensely to advancements made in nuclear science, space, metallurgy, electrical/electronic technology, chemical engineering, transportation, robotics and many other fields. This book is intended to assist students, scientists, technicians and engineers to understand the basics of vacuum science and technology for application in their projects. The fundamental theories, concepts, devices, applications, and key inventions are discussed.

  16. On Orbit Daytime Solar Heating Effects: A Comparison of Ground Chamber Arcing Results

    Science.gov (United States)

    Galofaro, J.; Vayner, B.; Ferguson, D.

    2004-01-01

    The purpose of the current experiment is to make direct comparisons between the arcing results obtained from the diffusion pumped vertical chamber and our newly renovated Teney vacuum chamber which is equipped with a cryogenic pump. Recall that the prior reported results obtained for the Vertical chamber were nominal at best, showing only a slight reduction in the arc rate after 5 heating cycles at the lower bias potentials and virtually no changes at high potential biases. It was concluded that the vertical chamber was unable to remove enough water vapor from the chamber to adequately test the arcing criterion. Because the cryo-pumped Teney chamber has a ten times better pumping speed, (40,000 liters per sec compared to 4,000 liters per sec for the diffusion pumped vertical chamber), a decision was made to retest that experiment in both the Teney and Vertical vacuum chambers. A comparison of the various data is presented with encouraging results.

  17. Chapters in the industrial history of plasma arcs: The precursors (1800-1900); fixation of atmospheric nitrogen (1898-1920)

    Science.gov (United States)

    Bailleux, C.

    1981-12-01

    Early experiments involving plasma arc discharges are recalled, including Humphry Davy's electric egg, and Birkeland's disastrous attempt to build an electric cannon. The development of arc furnaces is traced, and the search for new sources of nitrogen at the turn of the century is described.

  18. Arc behavior in low-voltage arc chambers

    Science.gov (United States)

    Mutzke, A.; Rüther, T.; Lindmayer, M.; Kurrat, M.

    2010-02-01

    The arc behavior in an arrangement of parallel arc rails with a splitter plate in between has been investigated experimentally and in numerical computations. Thereby, the arc is simulated by coupling finite-volume modeling for the gasdynamics and finite-elements modeling for the electromagnetics. The formation of arc roots on the splitter plate can be described by a thin layer of elements with a current-density dependent specific resistance. The simulations were extended to model the experimental arrangement exactly. Additionally, net emission coefficients and radiation heat conductivity of air plasma instead of a simplified T4 net emission of a black body were used to model the radiative cooling of the arc. The results of the arc voltage, the arc movement and the splitting process have been compared to measurements and high speed movies of the arc and yield good correlation. Moreover, the simulations allow good insight into the temperature distribution of the arc and the movement of the pressure waves caused at the arc ignition.

  19. Vacuum energy sequestering and graviton loops

    OpenAIRE

    Kaloper, Nemanja; Padilla, Antonio

    2017-01-01

    We recently formulated a local mechanism of vacuum energy sequester. This mechanism automatically removes all matter loop contributions to vacuum energy from the stress energy tensor which sources the curvature. Here we adapt the local vacuum energy sequestering mechanism to also cancel all the vacuum energy loops involving virtual gravitons, in addition to the vacuum energy generated by matter fields alone.

  20. THERMOCOUPLE VACUUM GAUGE

    Science.gov (United States)

    Price, G.W.

    1954-08-01

    A protector device is described for use in controlling the pressure within a cyclotron. In particular, an electrical circuit functions to actuate a vacuum pump when a predetermined low pressure is reached and disconnect the pump when the pressure increases abcve a certain value. The principal feature of the control circuit lies in the use of a voltage divider network at the input to a relay control tube comprising two parallel, adjustable resistances wherein one resistor is switched into the circuit when the relay connects the pump to a power source. With this arrangement the relay is energized at one input level received from a sensing element within the cyclotron chamber and is de-energized when a second input level, representing the higher pressure limit, is reached.

  1. 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.

  2. Abdominal intrauterine vacuum aspiration.

    Science.gov (United States)

    Tjalma, W A A

    2014-01-01

    Evaluating and "cleaning" of the uterine cavity is probably the most performed operation in women. It is done for several reasons: abortion, evaluation of irregular bleeding in premenopausal period, and postmenopausal bleeding. Abortion is undoubtedly the number one procedure with more than 44 million pregnancies terminated every year. This procedure should not be underestimated and a careful preoperative evaluation is needed. Ideally a sensitive pregnancy test should be done together with an ultrasound in order to confirm a uterine pregnancy, excluding extra-uterine pregnancy, and to detect genital and/or uterine malformations. Three out of four abortions are performed by surgical methods. Surgical methods include a sharp, blunt, and suction curettage. Suction curettage or vacuum aspiration is the preferred method. Despite the fact that it is a relative safe procedure with major complications in less than one percent of cases, it is still responsible for 13% of all maternal deaths. All the figures have not declined in the last decade. Trauma, perforation, and bleeding are a danger triage. When there is a perforation, a laparoscopy should be performed immediately, in order to detect intra-abdominal lacerations and bleeding. The bleeding should be stopped as soon as possible in order to not destabilize the patient. When there is a perforation in the uterus, this "entrance" can be used to perform the curettage. This is particularly useful if there is trauma of the isthmus and uterine wall, and it is difficult to identify the uterine canal. A curettage is a frequent performed procedure, which should not be underestimated. If there is a perforation in the uterus, then this opening can safely be used for vacuum aspiration.

  3. ULTRARAPID VACUUM-MICROWAVE HISTOPROCESSING

    NARCIS (Netherlands)

    KOK, LP; BOON, ME

    A novel histoprocessing method for paraffin sections is presented in which the combination of vacuum and microwave exposure is the key element. By exploiting the decrease in boiling temperature under vacuum, the liquid molecules in the tissues have been successfully extracted and exchanged at

  4. Vacuum Technology for Superconducting Devices

    CERN Document Server

    Chiggiato, P

    2014-01-01

    The basic notions of vacuum technology for superconducting applications are presented, with an emphasis on mass and heat transport in free molecular regimes. The working principles and practical details of turbomolecular pumps and cryopumps are introduced. The specific case of the Large Hadron Collider’s cryogenic vacuum system is briefly reviewed.

  5. Controlling Arc Length in Plasma Welding

    Science.gov (United States)

    Iceland, W. F.

    1986-01-01

    Circuit maintains arc length on irregularly shaped workpieces. Length of plasma arc continuously adjusted by control circuit to maintain commanded value. After pilot arc is established, contactor closed and transfers arc to workpiece. Control circuit then half-wave rectifies ac arc voltage to produce dc control signal proportional to arc length. Circuit added to plasma arc welding machines with few wiring changes. Welds made with circuit cleaner and require less rework than welds made without it. Beads smooth and free of inclusions.

  6. Vacuum fiber-fiber coupler

    Science.gov (United States)

    Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe

    2017-02-01

    Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.

  7. 49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Vacuum brake assist unit and vacuum brake system... Vehicles With GVWR of More Than 10,000 Pounds § 570.56 Vacuum brake assist unit and vacuum brake system. The following requirements apply to vehicles with vacuum brake assist units and vacuum brake systems...

  8. Electromagnetic radiation generated by arcing in low density plasma

    Science.gov (United States)

    Vayner, Boris V.; Ferguson, Dale C.; Snyder, David B.; Doreswamy, C. V.

    1996-01-01

    An unavoidable step in the process of space exploration is to use high-power, very large spacecraft launched into Earth orbit. Obviously, the spacecraft will need powerful energy sources. Previous experience has shown that electrical discharges occur on the surfaces of a high-voltage array, and these discharges (arcs) are undesirable in many respects. Moreover, any high voltage conductor will interact with the surrounding plasma, and that interaction may result in electrical discharges between the conductor and plasma (or between two conductors with different potentials, for example, during docking and extravehicular activity). One very important aspect is the generation of electromagnetic radiation by arcing. To prevent the negative influence of electromagnetic noise on the operation of spacecraft systems, it seems necessary to determine the spectra and absolute levels of the radiation, and to determine limitations on the solar array bias voltage that depend on the parameters of LEO plasma and the technical requirements of the spacecraft equipment. This report describes the results of an experimental study and computer simulation of the electromagnetic radiation generated by arcing on spacecraft surfaces. A large set of high quality data was obtained during the Solar Array Module Plasma Interaction Experiment (SAMPIE, flight STS-62) and ground test. These data include the amplitudes of current, pulse forms, duration of each arc, and spectra of plasma waves. A theoretical explanation of the observed features is presented in this report too. The elaborated model allows us to determine the parameters of the electromagnetic noise for different frequency ranges, distances from the arcing site, and distinct kinds of plasma waves.

  9. 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...

  10. Concussion - adults - discharge

    Science.gov (United States)

    Brain injury - concussion - discharge; Traumatic brain injury - concussion - discharge; Closed head injury - concussion - discharge ... a car Ski, snowboard, skate, skateboard, or do gymnastics or martial arts Participate in any activity where ...

  11. Tennis elbow surgery - discharge

    Science.gov (United States)

    Lateral epicondylitis surgery - discharge; Lateral tendinosis surgery - discharge; Lateral tennis elbow surgery - discharge ... Soon after surgery, severe pain will decrease, but you may have mild soreness for 3 to 6 months.

  12. Eye muscle repair - discharge

    Science.gov (United States)

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  13. Ventriculoperitoneal shunt - discharge

    Science.gov (United States)

    ... VP shunt - discharge; Shunt revision - discharge; Hydrocephalus shunt placement - discharge ... The major problems to watch for are an infected shunt and a blocked shunt. Call your child's provider if your child ...

  14. Pemesinan Nonkonvensional Plasma Arc Cutting

    OpenAIRE

    Akhmad, Al Antoni

    2009-01-01

    Dalam proses pemesinan dikenal 2 jenis proses pemesian, yaitu pemesinan konvensional dan pemesinan nonkonvensional. Salah satu jenis pemesinan nonkonvensional ini adalah Plasma Arc Cutting. Plasma Arc Cutting sangat banyak digunakan dalam berbagai industri yang mengunakan bahan baku logam. Jenis torch pada Plasma Arc Cutting ini ada banyak. Setiap jenis torch mempunyai karakteristik tertentu dan fungsi tertentu. In machining process known 2 kind machining process, conventional machining and n...

  15. Prostate brachytherapy - discharge

    Science.gov (United States)

    Implant therapy - prostate cancer - discharge; Radioactive seed placement - discharge ... You had a procedure called brachytherapy to treat prostate cancer. Your treatment lasted 30 minutes or more, ...

  16. Of Eggs and Arcs

    Science.gov (United States)

    Burns, Joseph A.; Thomas, P. C.; Helfenstein, P.; Tiscareno, M. S.; Hedman, M. M.; Agarwal, M.

    2012-10-01

    New scenarios for the origins of Saturn’s rings/interior moons have directed scientific attention to the region just exterior to Saturn’s main rings. Four satellites (Aegaeon = Ae; Anthe = An; Methone = Me; Pallene = Pa) discovered by the Cassini mission on either side of Mimas’s orbit perhaps comprise a distinct class of ring-moon. They are tiny (R = 0.3-2.5 km); three (AeAnMe) are trapped in co-rotation resonances with Mimas and reside within ring-arcs; and at least two (MePa) have remarkably regular shapes. Images with pixel scales as fine as 27 m taken in May 2012 reveal Methone to be ovoid within 10 m (from sub-pixel limb detection) and devoid of any craters (>130 m) across its 9 km2 of surface; Pallene and even tiny Aegaeon have similar appearances in lesser-quality images. Numerical simulations demonstrate that particles comprising the surrounding ring-arcs populate the same resonances as their embedded moons; escape speeds from the moons are transfer of particles back and forth between the ring-arcs and any embedded bodies. In this environment, the moons’ shapes are smooth equipotentials; electrostatic effects may also determine how grains settle to surfaces. Considering these shapes to represent equipotential surfaces for rotating, tidally distorted, homogeneous bodies, we infer mean satellite densities of 250+/-60 (Pa), 310+/-30 (Me), and 540+/-120 (Ae) kg m-3. About half of Methone’s leading hemisphere is covered by a sharply bounded, lemon-shaped, relatively dark region, having a form reminiscent of Mimas’s thermal anomaly (Howett et al. 2011). Its (601 nm) albedo is 13% lower than the bounding brighter material. An irregularly shaped, even-darker (by 4%) blotch straddles the apex of the moon’s motion. Impacts with circum-planetary meteoroids and plasma are likely responsible for these features.

  17. Coupled simulations of electric arcs for switching devices with MpCCI and ANSYS

    OpenAIRE

    Bayrasy, Pascal

    2016-01-01

    Electric arcs occur in various industrial applications from melting, welding, and lighting to switching devices. The discharge phenomenon is governed by the magneto-hydrodynamic equations, considering the Lorentz forces, Ohmic heating and radiation transport. The resulting arc is coupled with the dynamics of the compressible flow of the gas. This simulation procedure is well established in the swichting devices industry. In the present case a multi-physics framework solution MpCCI is applied ...

  18. 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.

  19. Experimental tests of vacuum energy

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    While the current vacuum energy of the Universe is very small, in our standard cosmological picture it has been much larger at earlier epochs. We try to address the question of what are possible ways to try to experimentally verify this. One direction is to look for systems where vacuum energy constitutes a non-negligible fraction of the total energy, and study the properties of those. Another possibility is to focus on the epochs around cosmic phase transitions, when the vacuum energy is of the same order as the total energy. Along these lines we investigate properties of neutron stars and the imprint of phase transitions on primordial gravitational waves.

  20. 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.

  1. Controlling the net charge on a nanoparticle optically levitated in vacuum

    Science.gov (United States)

    Frimmer, Martin; Luszcz, Karol; Ferreiro, Sandra; Jain, Vijay; Hebestreit, Erik; Novotny, Lukas

    2017-06-01

    Optically levitated nanoparticles in vacuum are a promising model system to test physics beyond our current understanding of quantum mechanics. Such experimental tests require extreme control over the dephasing of the levitated particle's motion. If the nanoparticle carries a finite net charge, it experiences a random Coulomb force due to fluctuating electric fields. This dephasing mechanism can be fully excluded by discharging the levitated particle. Here, we present a simple and reliable technique to control the charge on an optically levitated nanoparticle in vacuum. Our method is based on the generation of charges in an electric discharge and does not require additional optics or mechanics close to the optical trap.

  2. Alumina barrier for vacuum brazing

    Science.gov (United States)

    Beuyukian, C. S.

    1980-01-01

    Heating platens of vacuum-brazing press will not stick to workpiece if aluminum oxide "paper" is interposed. Paper does not disintegrate in press, will not contaminate braze alloy, and helps form smoothly contoured, regular fillet at brazed edges.

  3. [Endoscopic vacuum-assisted closure].

    Science.gov (United States)

    Wedemeyer, J; Lankisch, T

    2013-03-01

    Anastomotic leakage in the upper and lower intestinal tract is associated with high morbidity and mortality. Within the last 10 years endoscopic treatment options have been accepted as sufficient treatment option of these surgical complications. Endoscopic vacuum assisted closure (E-VAC) is a new innovative endoscopic therapeutic option in this field. E-VAC transfers the positive effects of vacuum assisted closure (VAC) on infected cutaneous wounds to infected cavities that can only be reached endoscopically. A sponge connected to a drainage tube is endoscopically placed in the leakage and a continuous vacuum is applied. Sponge and vacuum allow removal of infected fluids and promote granulation of the leakage. This results in clean wound grounds and finally allows wound closure. Meanwhile the method was also successfully used in the treatment of necrotic pancreatitis.

  4. SILICON REFINING BY VACUUM TREATMENT

    Directory of Open Access Journals (Sweden)

    André Alexandrino Lotto

    2014-12-01

    Full Text Available This work aims to investigate the phosphorus removal by vacuum from metallurgical grade silicon (MGSi (98.5% to 99% Si. Melting experiments were carried out in a vacuum induction furnace, varying parameters such as temperature, time and relation area exposed to the vacuum / volume of molten silicon. The results of chemical analysis were obtained by inductively coupled plasma (ICP, and evaluated based on thermodynamic and kinetic aspects of the reaction of vaporization of the phosphorus in the silicon. The phosphorus was decreased from 33 to approximately 1.5 ppm after three hours of vacuum treatment, concluding that the evaporation step is the controlling step of the process for parameters of temperature, pressure and agitation used and refining by this process is technically feasible.

  5. Vacuum production; Produccion de vacio

    Energy Technology Data Exchange (ETDEWEB)

    Segovia, J. L. de

    2010-07-01

    Since the advent of ultra high vacuum in 1958 has been a great demand for new as means of production and to meet the process needs to be done: industry heavy, high technology and space research areas, large accelerator systems particles or nuclear fusion. In this paper we explore the modern media production: dry vacuum pumps, turbo pumps, pump status diffusion ion pumps and cryopumps. (Author)

  6. Edge conduction in vacuum glazing

    Energy Technology Data Exchange (ETDEWEB)

    Simko, T.M.; Collins, R.E. [Sydney Univ., NSW (Australia). Dept. of Applied Physics; Beck, F.A.; Arasteh, D. [Lawrence Berkeley Lab., CA (United States)

    1995-03-01

    Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation. Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.

  7. Vacuum-assisted cesarean section

    Directory of Open Access Journals (Sweden)

    McQuivey RW

    2017-03-01

    Full Text Available Ross W McQuivey,1 Jon E Block2 1Clinical Innovations, Salt Lake City, UT, 2Independent consultant, San Francisco, CA, USA Abstract: There has been a dramatic rise in the frequency of cesarean sections, surpassing 30% of all deliveries in the US. This upsurge, coupled with a decreasing willingness to allow vaginal birth after cesarean section, has resulted in an expansion of the use of vacuum assistance to safely extract the fetal head. By avoiding the use of a delivering hand or forceps blade, the volume being delivered through the uterine incision can be decreased when the vacuum is used properly. Reducing uterine extensions with their associated complications (eg, excessive blood loss in difficult cases is also a theoretical advantage of vacuum delivery. Maternal discomfort related to excessive fundal pressure may also be lessened. To minimize the risk of neonatal morbidity, proper cup placement over the “flexion point” remains essential to maintain vacuum integrity and reduce the chance of inadvertent detachment and uterine extensions. Based on the published literature and pragmatic clinical experience, utilization of the vacuum device is a safe and effective technique to assist delivery during cesarean section. Keywords: cesarean section, vacuum, forceps, birth, delivery

  8. Technical specification for vacuum systems

    Energy Technology Data Exchange (ETDEWEB)

    Khaw, J. (ed.)

    1987-01-01

    The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing and designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)

  9. Arcing at B 4C-covered limiters exposed to a SOL-plasma

    Science.gov (United States)

    Laux, M.; Schneider, W.; Wienhold, P.; Jüttner, B.; Huber, A.; Balden, M.; Linke, J.; Kostial, H.; Mayer, M.; Rubel, M.; Herrmann, A.; Pospieszczyk, A.; Jachmich, S.; Schweer, B.; Hildebrandt, D.; Bolt, H.

    2003-03-01

    Plasma sprayed B 4C-layers considered as wall coatings for the W7X stellarator have been studied during and after exposure to TEXTOR and after arcing experiments in vacuum. Arcing through the B 4C layer occurred favoured by high power fluxes and not restricted to less stable phases. But this arcing implies an especially noisy scrape-off layer (SOL). Instead of moving retrograde in the external magnetic field, the arc spot on the B 4C-layer sticks to the same location for its whole lifetime. Consequently, the arc erodes the entire B 4C layer, finally burning down to the Cu substrate. In the neighbourhood of craters the surface contains Cu originating from those craters. This material, hauled to the surface by the arc, is subject to subsequent erosion, transport, and redeposition by the SOL-plasma. The behaviour of arcs on B 4C is most probably caused by the peculiar temperature dependences of the electrical and heat conductivity of B 4C.

  10. Arcing at B{sub 4}C-covered limiters exposed to a SOL-plasma

    Energy Technology Data Exchange (ETDEWEB)

    Laux, M. E-mail: michael.laux@ipp.mpg.delaux@ipp.mpg.de; Schneider, W.; Wienhold, P.; Juettner, B.; Huber, A.; Balden, M.; Linke, J.; Kostial, H.; Mayer, M.; Rubel, M.; Herrmann, A.; Pospieszczyk, A.; Jachmich, S.; Schweer, B.; Hildebrandt, D.; Bolt, H

    2003-03-01

    Plasma sprayed B{sub 4}C-layers considered as wall coatings for the W7X stellarator have been studied during and after exposure to TEXTOR and after arcing experiments in vacuum. Arcing through the B{sub 4}C layer occurred favoured by high power fluxes and not restricted to less stable phases. But this arcing implies an especially noisy scrape-off layer (SOL). Instead of moving retrograde in the external magnetic field, the arc spot on the B{sub 4}C-layer sticks to the same location for its whole lifetime. Consequently, the arc erodes the entire B{sub 4}C layer, finally burning down to the Cu substrate. In the neighbourhood of craters the surface contains Cu originating from those craters. This material, hauled to the surface by the arc, is subject to subsequent erosion, transport, and redeposition by the SOL-plasma. The behaviour of arcs on B{sub 4}C is most probably caused by the peculiar temperature dependences of the electrical and heat conductivity of B{sub 4}C.

  11. Opening Electrical Contacts: The Transition from the Molten Metal Bridge to the Electric Arc

    Science.gov (United States)

    Slade, Paul G.

    This paper presents a comprehensive explanation of the formation of the electric arc between opening contacts in a current carrying electric circuit. As the contacts begin to open a molten metal bridge forms between them. The rupture of this bridge and the initial formation of the electric arc are studied in both atmospheric air and vacuum using experiments to determine the direction of metal transfer between the contacts as a function of time after the rupture of the molten metal bridge. High speed streak photography is also used to show the rupture of the molten metal bridge and the initial formation of the electric arc. Analysis of these data show that a very high-pressure, high-temperature metal vapor zone exists between the contacts after the rupture of the molten metal bridge. Under this condition a pseudo-arc forms where current is carried by metal ions and an anomalous, high net transfer of metal to the cathodic contact occurs. The pressure in this region decreases rapidly and there is a transition to the usual electric arc, which still operates in the metal vapor. In this arc the current is now mostly carried by electrons. The data shows that there is still a net transfer of metal to the cathode, but now its volume is a function of the arcing time.

  12. Arc model for slag coated electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Satheesh Kumar, A.; Gupta, B.; Tewari, D.P. [Department of Physics, IIT, New Delhi (India)

    1998-12-31

    A model for arcs in the cathode region in the presence of a slag layer is given. The arc has been assumed to be comprised of two sections; one in the slag layer and the other in the plasma boundary layer. A model for the arc consisting of an arc column, a spreading region and a diffuse region has been considered. The dimensions of the arc, such as arc height and diameter, have been obtained. The boundary layer voltage drop, comprised of the arc column voltage drop, spreading region voltage drop and diffuse region drop, and the arc current have also been obtained. (Author)

  13. Numerical Model with Arc Length Variation of Welding Arc with Constant Voltage Power Source

    OpenAIRE

    Tanaka, Manabu; Tsujimura, Yoshihiro; Tashiro, Shinichi

    2012-01-01

    In the present paper, Tungsten Inert Gas (TIG) arc with Constant Voltage (CV) power source is modeled if arc length changes. And TIG arc with Constant Current (CC) power source is also modeled if arc length changes. The TIG arc is assumed on base material of water-cooled copper. For the CV power source, Maximum temperature of arc plasma and arc current increase with decrease of arc length. For the CC power source, arc voltage changes but maximum temperatures of arc plasma is almost constant i...

  14. Jeanne d’Arc

    OpenAIRE

    Anonymous

    2016-01-01

    Malgré les nombreuses informations historiques dont on dispose à son sujet, Jeanne d’Arc reste un personnage médiéval atypique et mystérieux. En effet, si son action est bien connue grâce aux comptes rendus de ses deux procès, celle-ci reste difficilement compréhensible. Comment expliquer qu’une jeune paysanne de Domrémy, ne sachant ni lire ni écrire, parvienne à prendre la tête d’une armée, à faire lever le siège d’Orléans et à permettre le sacre du roi Charles VII à Reims ? De plus, les ten...

  15. 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.

  16. Hydrothermal heat discharge in the Cascade Range, northwestern United States

    Science.gov (United States)

    Ingebritsen, S.E.; Mariner, R.H.

    2010-01-01

    Hydrothermal heat discharge in the Cascade Range includes the heat discharged by thermal springs, by "slightly thermal" springs that are only a few degrees warmer than ambient temperature, and by fumaroles. Thermal-spring heat discharge is calculated on the basis of chloride-flux measurements and geothermometer temperatures and totals ~ 240 MW in the U.S. part of the Cascade Range, excluding the transient post-1980 discharge at Mount St. Helens (~80 MW as of 2004-5). Heat discharge from "slightly thermal" springs is based on the degree of geothermal warming (after correction for gravitational potential energy effects) and totals ~. 660. MW. Fumarolic heat discharge is calculated by a variety of indirect and direct methods and totals ~160 MW, excluding the transient mid-1970s discharge at Mount Baker (~80 MW) and transient post-1980 discharge at Mount St. Helens (>. 230. MW as of 2005). Other than the pronounced transients at Mount St. Helens and Mount Baker, hydrothermal heat discharge in the Cascade Range appears to be fairly steady over a ~25-year period of measurement. Of the total of ~. 1050. MW of "steady" hydrothermal heat discharge identified in the U.S. part of the Cascade Range, less than 50. MW occurs north of latitude 45??15' N (~0.1 MW per km arc length from 45??15' to 49??N). Much greater rates of hydrothermal heat discharge south of 45??15'N (~1.7 MW per km arc length from 40?? to 45??15'N) may reflect the influence of Basin and Range-style extensional tectonics (faulting) that impinges on the Cascades as far north as Mount Jefferson but is not evident farther north. ?? 2010.

  17. RFQ Vacuum brazing at CERN

    CERN Document Server

    Mathot, S

    2008-01-01

    The aim of this paper is to describe the vacuum brazing procedure used at CERN for the brazing of Radio Frequency Quadrupole (RFQ). The RFQ is made of high precision machined OFE copper pieces assembled together. Vacuum brazing is one of the most promising techniques used to join the individual components leading to vacuum tightness and high precision alignment. The RFQ modules brazed at CERN are made of four 100 or 120 cm long vanes (two major and two minor vanes). Our brazing procedure consists of two steps. The first step involves the brazing of the four vanes in a horizontal position. The second step consists of brazing the vacuum stainless steel flanges to the copper structure in a vertical position. The paper describes the problems encountered with the alignment and the vacuum tightness. The difficulties related to the stress relaxation of the machined copper pieces during the brazing heat treatment are discussed. In addition, the solutions developed to improve the alignment of the brazed RFQ’s are...

  18. Measurement of partial pressures in vacuum technology and vacuum physics

    Science.gov (United States)

    Huber, W. K.

    1986-01-01

    It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

  19. [Use of vacuum-assisted closure in the topical treatment of surgical site infections].

    Science.gov (United States)

    Kiliç, Ayhan; Ozkaya, Ufuk; Sökücü, Sami; Basilgan, Seçkin; Kabukçuoğlu, Yavuz

    2009-01-01

    This study was designed to evaluate the results of vacuum-assisted closure in the topical treatment of surgical site infections. Vacuum therapy was performed in 17 patients (10 males, 7 females; mean age 60 + or - 20 years) using the VAC system (Vacuum-Assisted Closure, Kinetic Concept Inc) for the treatment of surgical site infections. Infective wounds were in the hip (n=6), crus (n=5), knee (n=3), sacrum (n=2), and hand (n=1). The causative organism for infections was gram-positive bacteria in 15 patients (88.2%), and six patients (35.3%) had nosocomial infections. The wounds were treated with a negative pressure of 100-125 mmHg applied continuously for the first two days, and then intermittently for the following days. The mean follow-up period was 11 + or - 6 months. The mean duration of vacuum therapy was 16 + or - 4 days and the mean length of hospitalization was 31 + or - 19 days. The patients underwent a mean number of three surgical procedures (range 1 to 6) before vacuum therapy. The mean amount of discharge from the wound was 500 + or - 150 ml. Tissue edema and discharge problems were resolved in all the wounds and a hygienic and dry-looking surgical site was attained. In 11 patients (64.7%), clinical and bacteriologic eradication of infections was achieved at the surgical site through antibiotic use and vacuum therapy. Six patients with nosocomial infections continued to receive antibiotic treatment following resolution of surgical site problems. The mean wound area showed a significant reduction from 36 + or - 14 cm(2) to 11 + or - 10 cm(2) following vacuum therapy (pclosure of wound site. Two patients (11.8%) complained of pain associated with vacuum application. Besides its topical advantages in the care of infected wounds, vacuum-assisted closure provides a more rapid and comfortable treatment opportunity, representing a reliable alternative to conventional wound care methods.

  20. Heart bypass surgery - minimally invasive - discharge

    Science.gov (United States)

    Minimally invasive direct coronary artery bypass - discharge; MIDCAB - discharge; Robot assisted coronary artery bypass - discharge; RACAB - discharge; Keyhole heart surgery - discharge; Coronary artery disease - MIDCAB discharge; CAD - ...

  1. 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.

  2. Microscale Digital Vacuum Electronic Gates

    Science.gov (United States)

    Manohara, Harish (Inventor); Mojarradi, Mohammed M. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement microscale digital vacuum electronic gates. In one embodiment, a microscale digital vacuum electronic gate includes: a microscale field emitter that can emit electrons and that is a microscale cathode; and a microscale anode; where the microscale field emitter and the microscale anode are disposed within at least a partial vacuum; where the microscale field emitter and the microscale anode are separated by a gap; and where the potential difference between the microscale field emitter and the microscale anode is controllable such that the flow of electrons between the microscale field emitter and the microscale anode is thereby controllable; where when the microscale anode receives a flow of electrons, a first logic state is defined; and where when the microscale anode does not receive a flow of electrons, a second logic state is defined.

  3. Carbon nanotubes based vacuum gauge

    Science.gov (United States)

    Rudyk, N. N.; Il’in, O. I.; Il’ina, M. V.; Fedotov, A. A.; Klimin, V. S.; Ageev, O. A.

    2017-11-01

    We have created an ionization type Vacuum gauge with sensor element based on an array of vertically aligned carbon nanotubes. Obtained asymmetrical current-voltage characteristics at different voltage polarity on the electrode with the CNTs. It was found that when applying a negative potential on an electrode with the CNTs, the current in the gap is higher than at a positive potential. In the pressure range of 1 ÷ 103 Torr vacuum gauge sensitivity was 6 mV/Torr (at a current of 4.5·10-5 A) and in the range of 10-5 ÷ 1 Torr was 10 mV/Torr (at a current of 1.3·10-5 A). It is shown that the energy efficiency of vacuum gauge can be increased in the case where electrode with CNT operates as an emitter of electrons.

  4. Vacuum properties of TiZrV non-evaporable getter films [for LHC vacuum system

    CERN Document Server

    Benvenuti, Cristoforo; Costa-Pinto, P; Escudeiro-Santana, A; Hedley, T; Mongelluzzo, A; Ruzinov, V; Wevers, I

    2001-01-01

    Sputter-deposited thin films of TiZrV are fully activated after 24 h "in situ" heating at 180 degrees C. This activation temperature is the lowest of some 18 different getter coatings studied so far, and it allows the use of the getter thin film technology with aluminium alloy vacuum chambers, which cannot be baked at temperatures higher than 200 degrees C. An updated review is given of the most recent results obtained on TiZrV coatings, covering the following topics: influence of the elemental composition and crystal structure on activation temperature, discharge gas trapping and degassing, dependence of pumping speed and surface saturation capacity on film morphology, ageing consequent to activation-air-venting cycles and ultimate pressures. Furthermore, the results obtained when exposing a coated particle beam chamber to synchrotron radiation in a real accelerator environment (ESRF Grenoble) are presented and discussed. (13 refs).

  5. Vacuum Cleaner Fan Being Improved

    Science.gov (United States)

    Tweedt, Daniel L.

    1997-01-01

    As part of the technology utilization program at the NASA Lewis Research Center, efforts are underway to transfer aerospace technologies to new areas of practical application. One such effort involves using advanced computational fluid dynamics (CFD) codes for turbomachinery to analyze the internal fluid dynamics of low-speed fans and blowers. This year, the Kirby Company in Cleveland, Ohio, approached NASA with a request for technologies that could help them improve their vacuum cleaners. Of particular interest to Kirby is the high-frequency blade-passing noise generation of their vacuum cleaner fan at low airflow rates.

  6. Urethral discharge culture

    Science.gov (United States)

    Culture of urethral discharge; Genital exudate culture; Culture - genital discharge or exudate ... 2015:chap 109. Craft AC, Woods GL. Specimen collection and handling for diagnosis of infectious diseases. In: ...

  7. Foot amputation - discharge

    Science.gov (United States)

    Amputation - foot - discharge; Trans-metatarsal amputation - discharge ... You have had a foot amputation. You may have had an accident, or your foot may have had an infection or disease and doctors could ...

  8. Hysterectomy - laparoscopic - discharge

    Science.gov (United States)

    ... a shower the day after surgery. If tape strips were used to close your skin, they should ... cancer Endometriosis Hysterectomy Uterine fibroids Patient Instructions Hysterectomy - abdominal - discharge Hysterectomy - vaginal - discharge Review Date 2/18/ ...

  9. 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.

  10. Prospects of airflow control by a gliding arc in a static magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Balcon, N; Benard, N; Braud, P; Touchard, G; Moreau, E [Laboratoire d' Etudes Aerodynamiques (LEA), Universite de Poitiers, ENSMA, CNRS Bld Marie et Pierre Curie, Teleport 2, 86962 Futuroscope Cedex (France); Mizuno, A [Toyohashi University of Technology, Japan, Hibarigaoka, Tempaku-cho, Toyoashi, Aichi 441-8580 (Japan)

    2008-10-21

    The electrical properties of a gliding arc operating in air at atmospheric pressure are studied to evaluate its possible applications to flow control. The electromechanical behaviour of the discharge travelling at 4 m s{sup -1} along diverging electrodes in a static magnetic field is analysed in detail. Two different methods are proposed to evaluate the velocity of the arc. An initial estimation is based on the arc current evolution during its transit and additional information is gained from fast digital imaging with a CCD camera. The displacement of the arc observed with short exposure time corroborates the electrical measurement and also exhibits the existence of luminous points on the cathode that can slow down the arc motion. In addition, a particle image velocimetry system is used to investigate the interaction between the gliding arc and the surrounding air. The displacement of the low current glidarc creates a low velocity convection (around 0.2 m s{sup -1}) in the gas and also generate faster structures up to 1 m s{sup -1} directly in front of the discharge. These electromechanical effects could be used to manipulate the boundary layer region of various aerodynamic shapes.

  11. Gases and vacua handbook of vacuum physics

    CERN Document Server

    Beck, A H

    2013-01-01

    Handbook of Vacuum Physics, Volume 1: Gases and Vacua provides information on the many aspects of vacuum technology, from material on the quantum theoretical aspects of the complex semi-conductors used for thermionic and photo-electric emission to data on the performance of commercially available pumps, gauges, and high-vacuum materials. The handbook satisfies the need of workers using vacuum apparatuses or works on the diverse applications of high-vacuum technology in research and industry. The book is a compilation of long articles prepared by experts in vacuum technology. Sufficient theoret

  12. Nurse-led discharge.

    Science.gov (United States)

    Page, Carole

    2010-12-01

    Delayed discharges have financial implications for hospital trusts and cause dissatisfaction for patients and their families. This article looks at nurse-led discharge pathways at Milton Keynes Hospital's ambulatory care unit. It explains how giving nurses the responsibility to discharge has improved the patient experience, made nurses more accountable and saved money for the trust.

  13. [Spectra and thermal analysis of the arc in activating flux plasma arc welding].

    Science.gov (United States)

    Chai, Guo-Ming; Zhu, Yi-Feng

    2010-04-01

    In activating flux plasma arc welding the welding arc was analyzed by spectra analysis technique, and the welding arc temperature field was measured by the infrared sensing and computer image technique. The distribution models of welding arc heat flow density of activating flux PAW welding were developed. The composition of welding arc affected by activated flux was studied, and the welding arc temperature field was studied. The results show that the spectral lines of argon atom and ionized argon atom of primary ionization are the main spectra lines of the conventional plasma welding arc. The spectra lines of weld metal are inappreciable in the spectra lines of the conventional plasma welding arc. The gas particle is the main in the conventional plasma welding arc. The conventional plasma welding arc is gas welding arc. The spectra lines of argon atom and ionized argon atom of primary ionization are intensified in the activating flux plasma welding arc, and the spectra lines of Ti, Cr and Fe elements are found in the activating flux plasma welding arc. The welding arc temperature distribution in activating flux plasma arc welding is compact, the outline of the welding arc temperature field is narrow, the range of the welding arc temperature distribution is concentrated, the welding arc radial temperature gradient is large, and the welding arc radial temperature gradient shows normal Gauss distribution.

  14. Cleaner Vacuum-Bag Curing

    Science.gov (United States)

    Clemons, J. M.; Penn, B. G.; Ledbetter, Frank E., III; Daniels, J. G.

    1987-01-01

    Improvement upon recommended procedures saves time and expense. Autoclave molding in vacuum bag cleaner if adhesive-backed covering placed around caul plate as well as on mold plate. Covering easy to remove after curing and leaves caul plate free of resin deposits.

  15. Brine Distribution after Vacuum Saturation

    DEFF Research Database (Denmark)

    Hedegaard, Kathrine; Andersen, Bertel Lohmann

    1999-01-01

    Experiments with the vacuum saturation method for brine in plugs of chalk showed that a homogeneous distribution of brine cannot be ensured at saturations below 20% volume. Instead of a homogeneous volume distribution the brine becomes concentrated close to the surfaces of the plugs...

  16. Quantum Vacuum Structure and Cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Rafelski, Johann; Labun, Lance; Hadad, Yaron; /Arizona U. /Munich U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC

    2011-12-05

    Contemporary physics faces three great riddles that lie at the intersection of quantum theory, particle physics and cosmology. They are: (1) The expansion of the universe is accelerating - an extra factor of two appears in the size; (2) Zero-point fluctuations do not gravitate - a matter of 120 orders of magnitude; and (3) The 'True' quantum vacuum state does not gravitate. The latter two are explicitly problems related to the interpretation and the physical role and relation of the quantum vacuum with and in general relativity. Their resolution may require a major advance in our formulation and understanding of a common unified approach to quantum physics and gravity. To achieve this goal we must develop an experimental basis and much of the discussion we present is devoted to this task. In the following, we examine the observations and the theory contributing to the current framework comprising these riddles. We consider an interpretation of the first riddle within the context of the universe's quantum vacuum state, and propose an experimental concept to probe the vacuum state of the universe.

  17. LEP vacuum chamber, early prototype

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The same vacuum chamber as in 7810256, read the detailed description there. Here, the 4 strip-shaped ion-getter pumps are poised at the entrance to their slots. Ion-getter pumps were not retained, thermal getter pumps were chosen instead (see 8301153 and 8305170).

  18. Filling the vacuum at LHCb

    CERN Multimedia

    Katarina Anthony

    2013-01-01

    Last month, the Vacuum, Surfaces and Coatings (VSC) group was tasked with an unusually delicate operation in the LHCb experiment cavern: removing the LHC beam pipe while keeping the sensitive Vertex Locator vacuum vessel (VELO) completely isolated from the action.   The VSC group seal off the VELO beam pipe with a flange. Image: Gloria Corti. LHCb’s VELO detector is one of the crown jewels of the experiment. With detector elements surrounded by a vacuum, it gets as close as 5 cm from the beam. Fantastic for physics, but difficult for all-important access. “Because of the sensitivity of the VELO detector and its proximity to the beam, the collaboration decided not to bake (see box) its portion of the beam pipe,” says Giulia Lanza (TE-VSC-LBV), the expert in charge of the beam vacuum operation. “Our group was therefore asked to remove the rest of the LHC beam pipe while keeping the VELO portion of the pipe completely isolated. This work...

  19. Vacuum Stability of Standard Model^{++}

    CERN Document Server

    Anchordoqui, Luis A.; Goldberg, Haim; Huang, Xing; Lust, Dieter; Taylor, Tomasz R.; Vlcek, Brian

    2013-01-01

    The latest results of the ATLAS and CMS experiments point to a preferred narrow Higgs mass range (m_h \\simeq 124 - 126 GeV) in which the effective potential of the Standard Model (SM) develops a vacuum instability at a scale 10^{9} -10^{11} GeV, with the precise scale depending on the precise value of the top quark mass and the strong coupling constant. Motivated by this experimental situation, we present here a detailed investigation about the stability of the SM^{++} vacuum, which is characterized by a simple extension of the SM obtained by adding to the scalar sector a complex SU(2) singlet that has the quantum numbers of the right-handed neutrino, H", and to the gauge sector an U(1) that is broken by the vacuum expectation value of H". We derive the complete set of renormalization group equations at one loop. We then pursue a numerical study of the system to determine the triviality and vacuum stability bounds, using a scan of 10^4 random set of points to fix the initial conditions. We show that, if there...

  20. Vacuum assisted closure in coloproctology

    NARCIS (Netherlands)

    Bemelman, W.A.

    2009-01-01

    Vacuum-assisted closure has earned its indications in coloproctology. It has been described with variable results in the treatment of large perineal defects after abdominoperineal excision, in the treatment of stoma dehiscence and perirectal abscesses. The most promising indication for

  1. Optimization of the output and efficiency of a high power cascaded arc hydrogen plasma source

    NARCIS (Netherlands)

    Vijvers, W. A. J.; van Gils, C. A. J.; W. J. Goedheer,; van der Meiden, H. J.; D.C. Schram,; Veremiyenko, V. P.; Westerhout, J.; Cardozo, N. J. L.; van Rooij, G. J.

    2008-01-01

    The operation of a cascaded arc hydrogen plasma source was experimentally investigated to provide an empirical basis for the scaling of this source to higher plasma fluxes and efficiencies. The flux and efficiency were determined as a function of the input power, discharge channel diameter, and

  2. Techno-economics of carbon nanotubes produced by open air arc ...

    African Journals Online (AJOL)

    user

    Techno-economics of carbon nanotubes produced by open air arc discharge method. M.S. Senthil Saravanan, S.P. Kumaresh Babu*, K. Sivaprasad, M. Jagannatham. Advanced Materials Processing Laboratory, Department of Metallurgical &Materials Engineering, National institute of Technology, Tiruchirapalli, INDIA.

  3. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    William S. McPhee

    1999-05-31

    The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and

  4. Vacuum-assisted closure system in treatment of postoperative mediastinitis.

    Science.gov (United States)

    Elawadi, Mohamed Ahmed; Oueida, Farouk

    2013-12-01

    Post-cardiac surgery mediastinitis is a serious complication with high morbidity and high financial costs. Using a vacuum-assisted closure system is the established line of treatment for mediastinitis, which improves outcome, especially in the high-risk group of patients. From January 2007 to April 2011, a retrospective study was carried out to evaluate the outcome of vacuum-assisted closure in the treatment of postoperative mediastinitis. There were 34 patients; 27 were male and 7 female. Mean time from infection to vacuum-assisted closure was 3.34 ± 1.10 days. The duration of vacuum-assisted closure was 6.51 ± 1.85 days (3-9 days). The mean amount of discharge was 759.60 ± 175.28 mL (range, 354-990 mL). Of the 34 patients, 21 (61.76%) had direct surgical wound closure and 13 (41.16%) had re-wiring. Two patients had bilateral pectoral flaps. One patient had chronic fistula formation, and one had a tear in the right ventricle. Mean hospital stay was 11.28 ± 2.09 days (range, 6-16 days). Vacuum-assisted closure therapy is a safe, reliable, and cost-effective modality of treatment for postoperative mediastinitis. It improves the outcome and can be combined with other modalities of conventional treatment, especially in high-risk groups such as the elderly or patients with diabetes.

  5. Vacuum polarization and Hawking radiation

    Science.gov (United States)

    Rahmati, Shohreh

    Quantum gravity is one of the interesting fields in contemporary physics which is still in progress. The purpose of quantum gravity is to present a quantum description for spacetime at 10-33cm or find the 'quanta' of gravitational interaction.. At present, the most viable theory to describe gravitational interaction is general relativity which is a classical theory. Semi-classical quantum gravity or quantum field theory in curved spacetime is an approximation to a full quantum theory of gravity. This approximation considers gravity as a classical field and matter fields are quantized. One interesting phenomena in semi-classical quantum gravity is Hawking radiation. Hawking radiation was derived by Stephen Hawking as a thermal emission of particles from the black hole horizon. In this thesis we obtain the spectrum of Hawking radiation using a new method. Vacuum is defined as the possible lowest energy state which is filled with pairs of virtual particle-antiparticle. Vacuum polarization is a consequence of pair creation in the presence of an external field such as an electromagnetic or gravitational field. Vacuum polarization in the vicinity of a black hole horizon can be interpreted as the cause of the emission from black holes known as Hawking radiation. In this thesis we try to obtain the Hawking spectrum using this approach. We re-examine vacuum polarization of a scalar field in a quasi-local volume that includes the horizon. We study the interaction of a scalar field with the background gravitational field of the black hole in the desired quasi-local region. The quasi-local volume is a hollow cylinder enclosed by two membranes, one inside the horizon and one outside the horizon. The net rate of particle emission can be obtained as the difference of the vacuum polarization from the outer boundary and inner boundary of the cylinder. Thus we found a new method to derive Hawking emission which is unitary and well defined in quantum field theory.

  6. Laboratory Simulation of Electrical Discharge in Surface Lunar Regolith

    Science.gov (United States)

    Shusterman, M.; Izenberg, N.; Wing, B. R.; Liang, S.

    2016-12-01

    Physical, chemical, and optical characteristics of space-weathered surface materials on airless bodies are produced primarily from bombardment by solar energetic particles and micrometeoroid impacts. On bodies such as the Moon and Mercury, soils in permanently shadowed regions (PSRs) are very cold, have low electrical conductivities, and are subjected to a high flux of incoming energetic particles accelerated by solar events. Theoretical models predict that up to 25% of gardened soils in the lunar polar regions are altered by dielectric breakdown; a potentially significant weathering process that is currently unconfirmed. Although electrical properties of lunar soils have been studied in relation to flight electronics and spacecraft safety, no studies have characterized potential alterations to soils resulting from electrical discharge. To replicate the surface charge field in PSRs, lunar regolith simulant JSC-1A was placed between two parallel plane electrodes under both low and high vacuum environments, 10e-3 torr and 2.5e-6 torr, respectively. Voltage was increased until discharge occurred within the sample. Grains were analyzed using an SVC fiber-fed point spectrometer, Olympus BX51 upright metallurgical microscope, and a Hitachi TM3000 scanning electron microscope with Bruker Quantax-70 X-ray spectrometer. Discharges occurring in samples under low vacuum resulted in surficial melting, silicate vapor deposition, coalescence of metallic iron, and micro-scale changes to surface topography. Samples treated under a high vacuum environment showed similar types of effects, but fewer in number compared to low vacuum samples. The variation in alteration abundances between the two environments implies that discharges may be occurring across surface contaminants, even at high vacuum conditions, inhibiting dielectric breakdown in our laboratory simulations.

  7. Chronic obstructive pulmonary disease - adults - discharge

    Science.gov (United States)

    ... adults - discharge; Chronic obstructive airways disease - adults - discharge; Chronic obstructive lung disease - adults - discharge; Chronic bronchitis - adults - discharge; Emphysema - adults - ...

  8. Final Design and Manufacturing of the PEP-II High Energy Ring Arc Bellows Module

    Science.gov (United States)

    Kurita, Nadine R.; Kulikov, Artem; Corlett, John

    1997-05-01

    An update on the Arc Bellows Module for the PEP-II High Energy Ring is presented (M.E. Nordby, N. Kurita, C-K Ng, " Bellows Design for the PEP-II High Energy Ring Arc Chambers", PAC95 Conference Proceedings, Dallas, Texas). This paper includes final design, manufacturing issues, material and coating selection, and tribological and Higher Order Mode testing. The final performance requirements and operational requirements are also reviewed. The RF Shield design was proven during assembly to allow for large manufacturing tolerances without reducing the mechanical spring force below required values. In addition, the RF Shield does not loose electrical contact with large misalignments across the module. Also discussed is the adaptation of the Arc Bellows Module into a circular geometry for use in the PEP-II Abort Line vacuum system.

  9. Water-cooled non-thermal gliding arc for adhesion improvement of glass-fibre-reinforced polyester

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Sørensen, Bent F.; Løgstrup Andersen, Tom

    2013-01-01

    A non-equilibrium quenched plasma is prepared using a gliding-arc discharge generated between diverging electrodes and extended by a gas flow. It can be operated at atmospheric pressure and applied to plasma surface treatment to improve adhesion properties of material surfaces. In this work, glass......-fibre-reinforced polyester plates were treated using an atmospheric pressure gliding-arc discharge with air flow to improve adhesion with a vinylester adhesive. The electrodes were water-cooled so as to operate the gliding arc continually. The treatment improved wettability and increased the density of oxygen......-containing polar functional groups on the surfaces. Double cantilever beam specimens were prepared for fracture mechanic characterization of the laminate adhesive interface. It was found that gliding-arc treatment significantly increases the fracture resistance in comparison with a standard peel-ply treatment....

  10. Gravitational Waves in Decaying Vacuum Cosmologies

    OpenAIRE

    David Alejandro Tamayo Ramirez

    2015-01-01

    In the present monograph we study in detail the primordial gravitational waves in cosmologies with a decaying vacuum. The decaying vacuum models are an alternative to solve the cosmological constant problem attributing a dynamic to the vacuum energy. The problem of primordial gravitational waves is discussed in the framework of an expanding, flat, spatially homogeneous and isotropic FLRW Universe described by General Relativity theory with decaying vacuum energy density of the type $\\\\Lambda ...

  11. Robot Vacuum Cleaner Personality and Behavior

    OpenAIRE

    Hendriks, A.F.M.; Meerbeek, B.W.; Boess, S.; Pauws, S.C.; Sonneveld, M.

    2011-01-01

    In this paper we report our study on the user experience of robot vacuum cleaner behavior. How do people want to experience this new type of cleaning appliance? Interviews were conducted to elicit a desired robot vacuum cleaner personality. With this knowledge in mind, behavior was designed for a future robot vacuum cleaner. A video prototype was used to evaluate how people experienced the behavior of this robot vacuum cleaner. The results indicate that people recognizedthe intended personali...

  12. 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.

  13. Utilize Vacuum Forming to Make Interdisciplinary Connections

    Science.gov (United States)

    Love, Tyler S.; Valenza, Frank

    2011-01-01

    The concept of vacuum forming has been around since the 19th century, despite not being fully utilized in industry until the 1950s. In the past, industrial arts classes have used vacuum-forming projects to concentrate solely on the manufacturing process and the final product. However, vacuum forming is not just an old industrial arts activity; it…

  14. The Dirac-Electron Vacuum Wave

    Directory of Open Access Journals (Sweden)

    Daywitt W. C.

    2016-07-01

    Full Text Available This paper argues that the Dirac equation can be interpreted as an interaction between the electron core and the Planck vacuum state, where the positive and negative solutions represent respectively the dynamics of the electron core and a vacuum wave propagating within the vacuum state. Results show that the nonrelativistic positive solution reduces to the Schrödinger wave equation

  15. Study of Arc-Related RF Faults in the CEBAF Cryomodules

    Energy Technology Data Exchange (ETDEWEB)

    Douglas Curry; Ganapati Myneni; Ganapati Rao Myneni; John Musson; Thomas Powers; Timothy Whitlatch; Isidoro Campisi; Haipeng Wang

    2004-07-01

    A series of measurements has been conducted on two superconducting radio-frequency (RF) cavity pairs, installed in cryomodules and routinely operated in the Continuous Electron Beam Accelerator Facility, in order to study the RF-vacuum interaction during an RF fault. These arc-related fault rates increase with increasing machine energy, contribute to system downtime, and directly affect the accelerator's availability. For this study, the fundamental power coupler waveguides have been instrumented with vacuum gauges, additional arc detectors, additional infrared sensors, and temperature sensors in order to measure the system response during both steady-state operations and RF fault conditions. Residual gas analyzers have been installed on the waveguide vacuum manifolds to monitor the gas species present during cooldown, RF processing, and operation. Measurements of the signals are presented, a comparison with analysis is shown and results are discussed. The goal of this study is to characterize the RF-vacuum interaction during normal operations. With a better understanding of the installed system response, methods for reducing the fault rate may be devised, ultimately leading to improvements in availability.

  16. Conditioning of the vacuum chamber of the Tokamak Novillo; Acondicionamiento de la camara de vacio del Tokamak Novillo

    Energy Technology Data Exchange (ETDEWEB)

    Valencia A, R.; Lopez C, R.; Melendez L, L.; Chavez A, E.; Colunga S, S.; Gaytan G, E

    1992-03-15

    The obtained experimental results of the implementation of two techniques of present time for the conditioning of the internal wall of the chamber of discharges of the Tokamak Novillo are presented, which has been designed, built and put in operation in the Laboratory of Plasma Physics of the National Institute of Nuclear Research (ININ). These techniques are: the vacuum baking and the low energy pulsed discharges, which were applied after having reached an initial pressure of the order of 10{sup -7} Torr. with a system of turbomolecular pumping previous preparation of surfaces and vacuum seals. The analysis of residual gases was carried out with a mass spectrometer before and after conditioning. The obtained results show that the vacuum baking it was of great effectiveness to reduce the value of the initial pressure in short time, in more of a magnitude order and the low energy discharges reduced the oxygen at worthless levels with regard to the initial values. (Author)

  17. Improving Hospital Discharge Time

    Science.gov (United States)

    El-Eid, Ghada R.; Kaddoum, Roland; Tamim, Hani; Hitti, Eveline A.

    2015-01-01

    Abstract Delays in discharging patients can impact hospital and emergency department (ED) throughput. The discharge process is complex and involves setting specific challenges that limit generalizability of solutions. The aim of this study was to assess the effectiveness of using Six Sigma methods to improve the patient discharge process. This is a quantitative pre and post-intervention study. Three hundred and eighty-six bed tertiary care hospital. A series of Six Sigma driven interventions over a 10-month period. The primary outcome was discharge time (time from discharge order to patient leaving the room). Secondary outcome measures included percent of patients whose discharge order was written before noon, percent of patients leaving the room by noon, hospital length of stay (LOS), and LOS of admitted ED patients. Discharge time decreased by 22.7% from 2.2 hours during the preintervention period to 1.7 hours post-intervention (P discharge. Hospital LOS dropped from 3.4 to 3.1 days postintervention (P hospital was significantly lower in the postintervention period (6.9 ± 7.8 vs 5.9 ± 7.7 hours; P discharge time. The focus of institutions aspiring to tackle delays in the discharge process should be on adopting the core principles of Six Sigma rather than specific interventions that may be institution-specific. PMID:25816029

  18. 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.

  19. Hydrogen mitigation in submerged arc welding

    Science.gov (United States)

    Klimowicz, Steven

    With the role of hydrogen in weld metal well understood in its relation to cold cracking, there has been a push to produce welds with lower and lower diffusible hydrogen contents. The push for lower diffusible hydrogen contents has placed pressure on consumables manufactures to create consumables that can achieve the requirements for lower diffusible hydrogen content. Currently EM12K flux is produced so that it can achieve below 4 ml of diffusible hydrogen for every 100g of weld metal deposited (ml/100g) for submerged arc welding (SAW). The recent trend for industry is to preferentially achieve diffusible hydrogen contents below 3 ml/100g. Making it necessary to find a way to modify the flux to achieve a lower diffusible hydrogen content for the welds it produces. To achieve this goal a two phase plan was developed. The first phase was to characterize the entire welding system for hydrogen. Since the goal of the project is hydrogen mitigation, any amount of hydrogen that could be reduced is helpful and therefore must first be discovered. Sources of hydrogen may be found by analyzing the welding wire and base metal, as well as breaking the flux down into its components and production steps. The wire was analyzed for total hydrogen content as was the base metal. The flux and its components were analyzed using differential thermal analysis-simultaneous thermal analysis (DTA-STA) and later vacuum degassing for moisture content. The analysis of the wire showed that the copper coating on the wire was the largest contributor of hydrogen. There was lubricant present on the wire surface as well, but it did not contribute as much as the copper coating. It was found that a simple low temperature baking of the wire was enough to remove the lubricant and coating moisture. The base metal was found to have a similar total hydrogen content to that of the wire. The breakdown of the flux and production process for moisture content analysis revealed that the production process

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

    Science.gov (United States)

    Christophorou, L.G.; Hunter, S.R.

    1988-06-28

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  1. "Flat-Fish" Vacuum Chamber

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

  2. Advanced window incorporating vacuum glazing

    Science.gov (United States)

    Asano, Osamu; Misonou, Masao; Kato, Hidemi; Nagasaka, Shigeki

    1999-10-01

    Vacuum glazing product named SPACIATM, being an unique product with very high levels of thermal insulation properties in a very small thickness, is described in detail. The construction and manufacturing process of SPACIATM are reported. Its design, which was originally established by R.E. Collins et al. of the University of Sydney, has been adjusted in order to meet the requirements of the Japanese market and the requirements of mass production process. SPACIATM is found to have several unique features including airborne sound insulation as well as thermal insulation. Energy required for air conditioning was simulated for Japanese houses with various glazings, and it was revealed that SPACIATM could save the energy efficiently. Finally, hybrid IG unit, where vacuum glazing is incorporated into a conventional IG unit, is proposed for further improvement of thermal insulation.

  3. LEP vacuum chamber, early prototype

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The structure of LEP, with long bending magnets and little access to the vacuum chamber between them, required distributed pumping. This is an early prototype for the LEP vacuum chamber, made from extruded aluminium. The main opening is for the beam. The small channel to the right is for cooling water, to carry away the heat deposited by the synchroton radiation from the beam. The 4 slots in the channel to the left house the strip-shaped ion-getter pumps (see 7810255). The ion-getter pumps depended on the magnetic field of the bending magnets, too low at injection energy for the pumps to function well. Also, a different design was required outside the bending magnets. This design was therefore abandoned, in favour of a thermal getter pump (see 8301153 and 8305170).

  4. Vacuum Alignment with more Flavors

    DEFF Research Database (Denmark)

    Ryttov, Thomas

    2014-01-01

    _f=2$ and $N_f=3$ we reproduce earlier known results including the Dashen phase with spontaneous violation of the combined charge conjugation and parity symmetry, CP. For $N_f=4$ we find regions with and without spontaneous CP violation. We then generalize to an arbitrary number of flavors. Here......We study the alignment of the vacuum in gauge theories with $N_f$ Dirac fermions transforming according to a complex representation of the gauge group. The alignment of the vacuum is produced by adding a small mass perturbation to the theory. We study in detail the $N_f=2,3$ and $4$ case. For $N...... it is shown that at the point where $N_f-1$ flavors are degenerate with positive mass $m>0$ and the mass of the $N_f$'th flavor becomes negative and equal to $-m$ CP breaks spontaneously....

  5. Visualizing electromagnetic vacuum by MRI

    CERN Document Server

    Chandrashekar, Chandrika S; Chandrashekar, S; Taylor, Erika A; Taylor, Deanne M

    2016-01-01

    Based upon Maxwell's equations, it has long been established that oscillating electromagnetic (EM) fields incident upon a metal surface decay exponentially inside the conductor, leading to a virtual EM vacuum at sufficient depths. Magnetic resonance imaging (MRI) utilizes radiofrequency (r.f.) EM fields to produce images. Here we present the first visualization of an EM vacuum inside a bulk metal strip by MRI, amongst several novel findings. We uncover unexpected MRI intensity patterns arising from two orthogonal pairs of faces of a metal strip, and derive formulae for their intensity ratios. Further, we furnish chemical shift imaging (CSI) results that discriminate different faces (surfaces) of a metal block according to their distinct nuclear magnetic resonance (NMR) chemical shifts, which holds much promise for monitoring surface chemical reactions noninvasively. Bulk metals are ubiquitous, and MRI is a premier noninvasive diagnostic tool. Combining the two, the emerging field of bulk metal MRI can be expe...

  6. Quantum vacuum and dark matter

    CERN Document Server

    Hajdukovic, Dragan Slavkov

    2012-01-01

    Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.

  7. Mass dependence of vacuum energy

    OpenAIRE

    Fulling, S. A.

    2005-01-01

    The regularized vacuum energy (or energy density) of a quantum field subjected to static external conditions is shown to satisfy a certain partial differential equation with respect to two variables, the mass and the "time" (ultraviolet cutoff parameter). The equation is solved to provide integral expressions for the regularized energy (more precisely, the cylinder kernel) at positive mass in terms of that for zero mass. Alternatively, for fixed positive mass all coefficients in the short-tim...

  8. Vacuum configuration for inflationary superstring

    Energy Technology Data Exchange (ETDEWEB)

    Baadhio, R.A. (Theoretical Physics Group, Physics Division, Lawrence Berkeley Laboratory and Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States))

    1993-02-01

    The vacuum configuration for the inflationary superstring theory is established. It is argued that the basic physical contents of the inflationary universe are characterized by the Novikov higher signature. Finally it is shown, with respect to the splitting of Paper II, that the index of the Dirac operator defined in our inflated universe, and in the parallel shadow one, is indeed [ital h]-cobordant.

  9. Entanglement in the Bogoliubov vacuum

    DEFF Research Database (Denmark)

    Poulsen, Uffe Vestergaard; Meyer, T.; Lewenstein, M.

    2005-01-01

    We analyze the entanglement properties of the Bogoliubov vacuum, which is obtained as a second-order approximation to the ground state of an interacting Bose-Einstein condensate. We work in one- and two-dimensional lattices and study the entanglement between two groups of sites as a function...... and to be favoured by strong interactions. Conversely, long-range entanglement is favoured by relatively weak interactions. No examples of bound entanglement are found....

  10. Field Emission in Vacuum Microelectronics

    CERN Document Server

    Fursey, George; Schwoebel, Paul

    2005-01-01

    Field emission is a phenomenon described by quantum mechanics. Its emission capability is millions times higher than that of any other known types of electron emission. Nowadays this phenomenon is experiencing a new life due to wonderful applications in the atomic resolution microscopy, in electronic holography, and in the vacuum micro- and nanoelectronics in general. The main field emission properties, and some most remarkable experimental facts and applications, are described in this book.

  11. Oscillations of a polarizable vacuum

    Directory of Open Access Journals (Sweden)

    James G. Gilson

    1991-01-01

    Full Text Available A classical basis for one-dimensional Schrödinger quantum theory is constructed from simple vacuum polarization harmonic oscillators within standard stochastic theory. The model is constructed on a two-dimensional phase configuration surface with phase velocity vectors that have a speed of light zitterbewegung behaviour character. The system supplies a natural Hermitian scalar product describing probability density which is derived from angular momentum considerations. The generality of the model which is extensive is discussed.

  12. Analysis of radial energy loss in an arc heater channel

    Czech Academy of Sciences Publication Activity Database

    Gregor, J.; Jakubová, I.; Šenk, J.; Mašláni, Alan

    2009-01-01

    Roč. 13, č. 2 (2009), s. 179-188 ISSN 1093-3611. [ European High Temperature Plasma Processes (HTPP)/10th./. Patras (Patras University), 07.07.2008-11.07.2008] Institutional research plan: CEZ:AV0Z20430508 Keywords : arc heater * argon * radiation * experiment * mathematical model Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.333, year: 2009 http://www.begellhouse.com/journals/57d172397126f956,4e2a92412d8c6bb5,161d9fdc35c6e905.html

  13. Shunting arc plasma source for pure carbon ion beam.

    Science.gov (United States)

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

  14. Ecton processes in the generation of pulsed runaway electron beams in a gas discharge

    Science.gov (United States)

    Mesyats, G. A.

    2017-09-01

    As was shown earlier for pulsed discharges that occur in electric fields rising with extremely high rates (1018 V/(cm s)) during the pulse rise time, the electron current in a vacuum discharge is lower than the current of runaway electrons in an atmospheric air discharge in a 1-cm-long gap. In this paper, this is explained by that the field emission current from cathode microprotrusions in a gas discharge is enhanced due to gas ionization. This hastens the initiation of explosive electron emission, which occurs within 10-11 s at a current density of up to 1010 A/cm2. Thereafter, a first-type cathode spot starts forming. The temperature of the cathode spot decreases due to heat conduction, and the explosive emission current ceases. Thus, the runaway electron current pulse is similar in nature to the ecton phenomenon in a vacuum discharge.

  15. Running Jobs in the Vacuum

    Science.gov (United States)

    McNab, A.; Stagni, F.; Ubeda Garcia, M.

    2014-06-01

    We present a model for the operation of computing nodes at a site using Virtual Machines (VMs), in which VMs are created and contextualized for experiments by the site itself. For the experiment, these VMs appear to be produced spontaneously "in the vacuum" rather having to ask the site to create each one. This model takes advantage of the existing pilot job frameworks adopted by many experiments. In the Vacuum model, the contextualization process starts a job agent within the VM and real jobs are fetched from the central task queue as normal. An implementation of the Vacuum scheme, Vac, is presented in which a VM factory runs on each physical worker node to create and contextualize its set of VMs. With this system, each node's VM factory can decide which experiments' VMs to run, based on site-wide target shares and on a peer-to-peer protocol in which the site's VM factories query each other to discover which VM types they are running. A property of this system is that there is no gate keeper service, head node, or batch system accepting and then directing jobs to particular worker nodes, avoiding several central points of failure. Finally, we describe tests of the Vac system using jobs from the central LHCb task queue, using the same contextualization procedure for VMs developed by LHCb for Clouds.

  16. Vacuum electronics applications at CERN

    CERN Document Server

    Jensen, E

    2009-01-01

    CERN operates a large number of vacuum electronics based RF power amplifiers covering a wide frequency range – over 300 sockets with 24 different grid tubes and klystrons are in use and require constant care to insure reliable operation of the accelerators. This is in particular true for the LHC and its injector chain, for which a program of improvement and stepwise upgrade has started. These include IOT’s for the SPS and klystrons and modulators for Linac4 and SPL. The CLIC study and the CTF3 facility are relevant to vacuum electronics in many ways: The CLIC primary RF power, to be provided at 1 GHz, requires highest possible efficiency and phase stability, MBK’s are likely candidates. The CLIC RF power source and CTF3 are themselves large vacuum electronics applications, consequently there are areas of common interest and concern, including fabrication techniques, pulse compression techniques, breakdown and multipactor theory and simulation, material fatigue, numerical analysis of slow-wave structures...

  17. Improved Aerogel Vacuum Thermal Insulation

    Science.gov (United States)

    Ruemmele, Warren P.; Bue, Grant C.

    2009-01-01

    An improved design concept for aerogel vacuum thermal-insulation panels calls for multiple layers of aerogel sandwiched between layers of aluminized Mylar (or equivalent) poly(ethylene terephthalate), as depicted in the figure. This concept is applicable to both the rigid (brick) form and the flexible (blanket) form of aerogel vacuum thermal-insulation panels. Heretofore, the fabrication of a typical aerogel vacuum insulating panel has involved encapsulation of a single layer of aerogel in poly(ethylene terephthalate) and pumping of gases out of the aerogel-filled volume. A multilayer panel according to the improved design concept is fabricated in basically the same way: Multiple alternating layers of aerogel and aluminized poly(ethylene terephthalate) are assembled, then encapsulated in an outer layer of poly(ethylene terephthalate), and then the volume containing the multilayer structure is evacuated as in the single-layer case. The multilayer concept makes it possible to reduce effective thermal conductivity of a panel below that of a comparable single-layer panel, without adding weight or incurring other performance penalties. Implementation of the multilayer concept is simple and relatively inexpensive, involving only a few additional fabrication steps to assemble the multiple layers prior to evacuation. For a panel of the blanket type, the multilayer concept, affords the additional advantage of reduced stiffness.

  18. 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…

  19. Getting to know ArcGIS desktop

    National Research Council Canada - National Science Library

    Ormsby, Tim

    2010-01-01

    .... Key concepts are combined with detailed illustrations and step-by-step exercises to acquaint readers with the building blocks of ArcGIS Desktop including ArcMap, for displaying and querying maps...

  20. Dynamics of a Planar Magnetron Discharge.

    Science.gov (United States)

    Wendt, Amy Eileen

    In planar magnetron sputter deposition, metal atoms are sputtered from a source by a magnetically confined plasma. The sputtered atoms come to rest on substrates placed in the vacuum chamber, coating them with a thin metal film. The operation of the planar magnetron depends on gas pressure, voltage V, current I, magnetic field strength B and other parameters in a manner not yet completely understood. This work employs modelling and experimental techniques to investigate the physical mechanisms which govern the operation of a planar magnetron discharge. The primary investigation centers on distribution of discharge current at the cathode. The cylindrically symmetric experimental system consists of a 12-inch diameter aluminum vacuum chamber with movable 9-inch diameter copper electrodes. The DC discharge is operated in argon, and a variable magnetic field is provided by an iron core electromagnet. The radial distribution of current at the cathode has been measured with a radially staggered array of 1-mm diameter current probes embedded in the cathode plate. The distribution is peaked at the radius at which the magnetic field is tangent to the cathode, and the width of the distribution, w is a function of the discharge parameters. Energy gained in the cathode sheath by secondary electrons emitted from the cathode goes into the ionization necessary for discharge maintenance. By examining the range of motion of these electrons in the magnetic field, the location of the plasma and thus the distribution of current at the cathode can be calculated. Such a calculation was carried out for the following scenarios: (1) the sheath is thin compared to the range of the electrons and electron motion is hamiltonian, (2) the sheath is thin and electron motion is dominated by diffusion, and (3) the sheath is thick compared to the range of the electrons and electron motion is hamiltonian. Only the latter, thick sheath model, gives good agreement with experimentally observed scaling

  1. An experimental system for controlled exposure of biological samples to electrostatic discharges.

    Science.gov (United States)

    Marjanovič, Igor; Kotnik, Tadej

    2013-12-01

    Electrostatic discharges occur naturally as lightning strokes, and artificially in light sources and in materials processing. When an electrostatic discharge interacts with living matter, the basic physical effects can be accompanied by biophysical and biochemical phenomena, including cell excitation, electroporation, and electrofusion. To study these phenomena, we developed an experimental system that provides easy sample insertion and removal, protection from airborne particles, observability during the experiment, accurate discharge origin positioning, discharge delivery into the sample either through an electric arc with adjustable air gap width or through direct contact, and reliable electrical insulation where required. We tested the system by assessing irreversible electroporation of Escherichia coli bacteria (15 mm discharge arc, 100 A peak current, 0.1 μs zero-to-peak time, 0.2 μs peak-to-halving time), and gene electrotransfer into CHO cells (7 mm discharge arc, 14 A peak current, 0.5 μs zero-to-peak time, 1.0 μs peak-to-halving time). Exposures to natural lightning stroke can also be studied with this system, as due to radial current dissipation, the conditions achieved by a stroke at a particular distance from its entry are also achieved by an artificial discharge with electric current downscaled in magnitude, but similar in time course, correspondingly closer to its entry. © 2013.

  2. Paediatric vaginal discharge

    African Journals Online (AJOL)

    Vaginal discharge in the prepubertal patient is a common symptom, and can be a source of distress for the caregiver and con- cern for the healthcare worker. Several factors predispose these patients to the development of recurrent vaginal discharge. Unless noticed by the caregiver, this problem can persist for long periods ...

  3. Graywater Discharges from Vessels

    Science.gov (United States)

    2011-11-01

    both sewage and graywater, or sewage collected from “ honey dipper” trucks, which may contain far less graywater, depending on the source (See... crystal clean effluent discharge. As a reference, Cruiseliners equipped with Scanship AWP systems has obtained continous discharge permits in Hawaii and

  4. Lithium battery discharge tests

    Science.gov (United States)

    Johnson, C. J.

    1980-01-01

    The long term discharge of a variety of lithium cells was characterized and the susceptibility of the cells to chemical variation during the slow discharge was tested. A shunt resistor was set across the terminals to monitor the voltage as a function of time. Failures were identified by premature voltage drops.

  5. The next-generation ARC middleware

    DEFF Research Database (Denmark)

    Appleton, O.; Cameron, D.; Cernak, J.

    2010-01-01

    The Advanced Resource Connector (ARC) is a light-weight, non-intrusive, simple yet powerful Grid middleware capable of connecting highly heterogeneous computing and storage resources. ARC aims at providing general purpose, flexible, collaborative computing environments suitable for a range of uses...... the next-generation ARC middleware, implemented as Web Services with the aim of standard-compliant interoperability....

  6. 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.

  7. Validating the Goldstein-Wehner Law for the Stratified Positive Column of DC Discharge in an Undergraduate Laboratory

    Science.gov (United States)

    Lisovskiy, V. A.; Koval, V. A.; Artushenko, E. P.; Yegorenkov, V. D.

    2012-01-01

    In this paper we suggest a simple technique for validating the Goldstein-Wehner law for a stratified positive column of dc glow discharge while studying the properties of gas discharges in an undergraduate laboratory. To accomplish this a simple device with a pre-vacuum mechanical pump, dc source and gas pressure gauge is required. Experiments may…

  8. 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

  9. Atmospheric-pressure electric discharge as an instrument of chemical activation of water solutions

    Science.gov (United States)

    Rybkin, V. V.; Shutov, D. A.

    2017-11-01

    Results of experimental studies and numerical simulations of physicochemical characteristics of plasmas generated in different types of atmospheric-pressure discharges (pulsed streamer corona, gliding electric arc, dielectric barrier discharge, glow-discharge electrolysis, diaphragmatic discharge, and dc glow discharge) used to initiate various chemical processes in water solutions are analyzed. Typical reactor designs are considered. Data on the power supply characteristics, plasma electron parameters, gas temperatures, and densities of active particles in different types of discharges excited in different gases and their dependences on the external parameters of discharges are presented. The chemical composition of active particles formed in water is described. Possible mechanisms of production and loss of plasma particles are discussed.

  10. Silane Discharge Ion Chemistry.

    Science.gov (United States)

    Chatham, Robert Hood, III

    We have studied silane dc, rf and dc proximity discharges, using mass spectroscopic measurements of the positive ions as a detailed diagnostic for the type of discharge used to produce hydrogenated amorphous silicon solar photovoltaic cells. The properties and quality of these films depends in a very complex way upon the interactions of the many reactive neutral and ion species in the discharge. We have developed qualitative models of the ion chemical processes in these discharges from our measurements. Knowledge of the ion-molecule and electron-molecule collision cross sections is important to any attempt at understanding silane discharge chemistry. Consequently, we have measured the electron impact ionization cross sections for silane and disilane, and for comparison purposes also for methane and ethane. In addition, we have measured the rate coefficients for charge exchange reactions of He('+), Ne('+), and Ar('+) with silane, disilane, methane, and ethane, as these are important to understanding discharges in inert gas-silane mixtures. We have developed a detailed quantitative model of the cathode sheath region of a silane dc discharge, by extending the best recent calculation of the electron motion in the sheath to a self-consistent form which includes the ion motion. This model is used with comparison of silane dc discharge data to diagnose the ion chemistry occurring in the sheath region of silane dc discharge. The understanding of the discharge ion chemical processes that we have gained in this study represent an important step toward understanding the chemical and physical processes leading to film growth.

  11. Static Heat Loads in the LHC Arc Cryostats: Final Assessment

    CERN Document Server

    Parma, V

    2010-01-01

    This note presents the final assessment of the static heat loads in the LHC arc cryostats, using different experimental methods during the first commissioning period in 2007. This assessment further develops and completes previous estimates made during the commissioning of sector 7_8 [1]. The estimate of the helium inventory, a prerequisite for the heat load calculation, is also presented. Heat loads to the cold mass are evaluated from the internal energy balance during natural as well as powered warm-ups of the helium baths in different subsector. The helium inventory is calculated from the internal energy balance during powered warm-ups and matched with previous assessments. Furthermore, heat loads to the thermal shield are estimated from the non-isothermal cooling of the supercritical helium in line E. The comparison of measured heat loads with previous estimates and with budgeted values is then presented, while their correlation with some important parameters like insulation vacuum pressure and some heat ...

  12. 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.

  13. ARC System fuel cycle analysis capability, REBUS-2

    Energy Technology Data Exchange (ETDEWEB)

    Hosteny, R.P.

    1978-10-01

    A detailed description is given of the ARC System fuel cycle modules FCI001, FCC001, FCC002, and FCC003 which form the fuel cycle analysis modules of the ARC System. These modules, in conjunction with certain other modules of the ARC System previously described in documents of this series, form the fuel cycle analysis system called REBUS-2. The physical model upon which the REBUS-2 fuel cycle modules are based and the calculational approach used in solving this model are discussed in detail. The REBUS-2 system either solves for the infinite time (i.e., equilibrium) operating conditions of a fuel recycle system under fixed fuel management conditions, or solves for the operating conditions during each of a series of explicitly specified (i.e., nonequilibrium) sequence of burn cycles. The code has the capability to adjust the fuel enrichment, the burn time, and the control poison requirements in order to satisfy user specified constraints on criticality, discharge fuel burnup, or to give the desired multiplication constant at some specified time during the reactor operation.

  14. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    Science.gov (United States)

    Li, Jian; Shashurin, Alexey; Kundrapu, Madhusudhan; Keidar, Michael

    2012-02-02

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the

  15. Vacuum Chambers for LEP sections

    CERN Multimedia

    1983-01-01

    The picture shows sections of the LEP vacuum chambers to be installed in the dipole magnets (left) and in the quadrupoles (right). The dipole chamber has three channels: the beam chamber, the pumping duct where the NEG (non-evaporabe getter) is installed and the water channel for cooling (on top in the picture). The pumping duct is connected to the beam chamber through holes in the separating wall. The thick lead lining to shield radiation can also be seen. These chambers were manufactured as extruded aluminium alloy profiles.

  16. Wet/Dry Vacuum Cleaner

    Science.gov (United States)

    Reimers, Harold; Andampour, Jay; Kunitser, Craig; Thomas, Ike

    1995-01-01

    Vacuum cleaner collects and retains dust, wet debris, and liquids. Designed for housekeeping on Space Station Freedom, it functions equally well in normal Earth Gravity or in microgravity. Generates acoustic noise at comfortably low levels and includes circuitry that reduces electromagnetic interference to other electronic equipment. Draws materials into bag made of hydrophobic sheet with layers of hydrophilic super-absorbing pads at downstream end material. Hydrophilic material can gel many times its own weight of liquid. Blower also provides secondary airflow to cool its electronic components.

  17. Characterization of ultra-short pulsed discharge plasma for CVD processing. [Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, Akira (Toyohashi Univ. of Technology (Japan). Dept. of Ecological Engineering); Okazaki, Ken (Tokyo Inst. of Technology (Japan). Research Center for Carbon Recycling and Utilization); Takekoshi, Takashi (Mitsubishi Kasei Co., Okayama (Japan). Mizushima Works); Tobe, Ryoki (Anelva Corp., Tokyo (Japan). Research Development Center)

    Characteristics of pulsed discharge plasma of methane-hydrogen gas mixture and Ar gas have been studied for active control of plasma chemical vapor deposition (CVD) processing. Voltage-current characteristics, time-lag of the current pulse, and the photon emission intensity profile have been investigated using high-voltage pulses of 50-1000 ns duration. In such a pulse discharge, voltages much higher than those in a dc glow discharge can be applied without any plasma nonuniformity or arcing because voltage amplitude falls to zero before glow to arc transition. A current value of more than 10[sup 3] times those in a glow discharge can be established. Very high photon emission intensity from CH radicals and H ions have been observed near the anode in a pulsed plasma. This is different in dc plasma, where the negative glow region near the cathode is the brightest.

  18. Thin-wall vacuum domain evolution

    Directory of Open Access Journals (Sweden)

    V.A. Berezin

    1983-01-01

    Full Text Available In the framework of general relativity the equation of motion of a thin-wall vacuum shell is derived at arbitrary values of the vacuum parameters inside and outside the shell. We obtain that the velocity of the walls of the true vacuum bubble at its expansion does not tend to the velocity of light. We find that vacuum shells could exist now in the universe, which do not contradict to observational cosmology. The types of black holes created are investigated. Restrictions on the mass of the black holes formed from remnants of the false vacuum and on the fraction of the vacuum energy pumped into such black holes are obtained.

  19. A new vacuum for Loop Quantum Gravity

    CERN Document Server

    Dittrich, Bianca

    2014-01-01

    We construct a new vacuum for loop quantum gravity, which is dual to the Ashtekar-Lewandowski vacuum. Because it is based on BF theory, this new vacuum is physical for $(2+1)$-dimensional gravity, and much closer to the spirit of spin foam quantization in general. To construct this new vacuum and the associated representation of quantum observables, we introduce a modified holonomy-flux algebra which is cylindrically consistent with respect to the notion of refinement by time evolution suggested in [1]. This supports the proposal for a construction of a physical vacuum made in [1,2], also for $(3+1)$-dimensional gravity. We expect that the vacuum introduced here will facilitate the extraction of large scale physics and cosmological predictions from loop quantum gravity.

  20. Vacuum systems for the ILC helical undulator

    CERN Document Server

    Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A

    2007-01-01

    The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

  1. Discharge lamp technologies

    Science.gov (United States)

    Dakin, James

    1994-03-01

    This talk is an overview of discharge lamp technology commonly employed in general lighting, with emphasis on issues pertinent to lighting for plant growth. Since the audience is primarily from the plant growth community, and this begins the light source part of the program, we will start with a brief description of the discharge lamps. Challenges of economics and of thermal management make lamp efficiency a prime concern in controlled environment agriculture, so we will emphasize science considerations relating to discharge lamp efficiency. We will then look at the spectra and ratings of some representative lighting products, and conclude with a discussion of technological advances.

  2. Capacitor discharge engineering

    CERN Document Server

    Früngel, Frank B A

    1976-01-01

    High Speed Pulse Technology, Volume III: Capacitor Discharge Engineering covers the production and practical application of capacitor dischargers for the generation and utilization of high speed pulsed of energy in different forms. This nine-chapter volume discusses the principles of electric current, voltage, X-rays, gamma rays, heat, beams of electrons, neutrons and ions, magnetic fields, sound, and shock waves in gases and liquids. Considerable chapters consider the applications of capacitor discharges, such as impulse hardening of steel, ultrapulse welding of precision parts, X-ray flash t

  3. Discharge lamp technologies

    Science.gov (United States)

    Dakin, James

    1994-01-01

    This talk is an overview of discharge lamp technology commonly employed in general lighting, with emphasis on issues pertinent to lighting for plant growth. Since the audience is primarily from the plant growth community, and this begins the light source part of the program, we will start with a brief description of the discharge lamps. Challenges of economics and of thermal management make lamp efficiency a prime concern in controlled environment agriculture, so we will emphasize science considerations relating to discharge lamp efficiency. We will then look at the spectra and ratings of some representative lighting products, and conclude with a discussion of technological advances.

  4. The influence of Ac parameters in the process of micro-arc oxidation film electric breakdown

    Directory of Open Access Journals (Sweden)

    Ma Jin

    2016-01-01

    Full Text Available This paper studies the electric breakdown discharge process of micro-arc oxidation film on the surface of aluminum alloy. Based on the analysis of the AC parameters variation in the micro-arc oxidation process, the following conclusions can be drawn: The growth of oxide film can be divided into three stages, and Oxide film breakdown discharge occurs twice in the micro-arc oxidation process. The first stage is the formation and disruptive discharge of amorphous oxide film, producing the ceramic oxide granules, which belong to solid dielectric breakdown. In this stage the membrane voltage of the oxide film plays a key role; the second stage is the formation of ceramic oxide film, the ceramic oxide granules turns into porous structure oxide film in this stage; the third stage is the growth of ceramic oxide film, the gas film that forms in the oxide film’s porous structure is electric broken-down, which is the second breakdown discharge process, the current density on the oxide film surface could affect the breakdown process significantly.

  5. Atomic Oscillator Strengths In The Vacuum Ultraviolet

    Science.gov (United States)

    Nave, Gillian; Sansonetti, C. J.; Szabo, C. I.

    2008-05-01

    Transitionsin singly-ionized and doubly-ionized iron-group elements give rise to prominent emission lines from a wide variety of astrophysical objects. Although the database of experimental oscillator strengths of Fe II has also been greatly extended by the FERRUM project, few experimental oscillator strengths are available in the region below 1600 Å, where many levels that give rise to emission lines at longer wavelengths have their dominant decays. The established way to measure accurate oscillator strengths for atomic lines combines the measurement of a lifetime of an upper energy level with a separate measurement of the branching fractions of all the lines emitted from that level. This technique relies on being able to observe all the spectral lines emitted by the upper level, which range down to Ly-α or below for many fluorescence lines. We have developed techniques to measure branching fractions in the vacuum ultraviolet using our 10.7-m normal incidence grating spectrograph. For this we use phosphor image plates as replacements for the photographic plates previously used on this instrument. Image plates are sensitive to wavelengths from the X-ray region to 2200 Å, and have a linear intensity response with a dynamic range of at least 10000. We have recorded spectra of iron-neon hollow cathode and Penning discharges, using a deuterium standard lamp for radiometric calibration. We will present the first measurements of oscillator strengths using this technique. We are also investigating methods of radiometric calibration below 1150 Å using hollow cathode standard lamps. This will enable us to measure branching ratios down to 800 Å or below. This work is partially funded by NASA under the inter-agency agreement W-10,255.

  6. Straw detector: 1 - Vacuum: 0

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    The NA62 straw tracker is using pioneering CERN technology to measure charged particles from very rare kaon decays. For the first time, a large straw tracker with a 4.4 m2 coverage will be placed directly into an experiment’s vacuum tank, allowing physicists to measure the direction and momentum of charged particles with extreme precision. NA62 measurements using this technique will help physicists take a clear look at the kaon decay rate, which might be influenced by particles and processes that are not included in the Standard Model.   Straw ends are glued to an aluminium frame, a crucial step in the assembly of a module. The ends are then visually inspected before a leak test is performed.  “Although straw detectors have been around since the 1980s, what makes the NA62 straw trackers different is that they can work under vacuum,” explains Hans Danielsson from the PH-DT group leading the NA62 straw project. Straw detectors are basically small drift cha...

  7. Gases vacuum dedusting and cooling

    Directory of Open Access Journals (Sweden)

    Alexey А. Burov

    2015-03-01

    Full Text Available Represented are the results of operating the ladle degassing vacuum plant (productivity: 120 tons of liquid steel with various dust collectors. The process gases’ cooling and dedusting, obtained in the closed loop buran study, provides opportunity to install a bag filter after that closed loop and its efficient use. Proven is the effectiveness of the cylindrical cyclone replacement with a multichannel (buran dust collector, based on a system of closed-loop (return coupling serially connected curved ducts, where the dusty gas flow rotation axis is vertically positioned. The system of closed-loop serially connected curvilinear channels creates preconditions for the emergence of a negative feedback at the curvilinear gas flow containing transit and circulating flows. These conditions are embodied with circulating flows connecting the in- and outputs of the whole system each channel. The transit flow multiple continuous filtration through the circulating dust layers leads to the formation and accumulation of particles aggregates in the collection chamber. The validity of such a dusty flow control mechanism is confirmed by experimental data obtained in a vacuum chamber. Therefore, replacing one of the two buran’s forevacuum pumps assemblies with the necessary number of curved channels (closed loop is estimated in a promising method.

  8. Vacuum silicon photomultipliers: Recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Barbarino, Giancarlo [Dipartimento Scienze Fisiche, Università “Federico II” Napoli (Italy); INFN Napoli (Italy); Barbato, Felicia Carla Tiziana [INFN Napoli (Italy); Campajola, Luigi [Dipartimento Scienze Fisiche, Università “Federico II” Napoli (Italy); Asmundis, Riccardo de [INFN Napoli (Italy); De Rosa, Gianfranca [Dipartimento Scienze Fisiche, Università “Federico II” Napoli (Italy); Mollo, Carlos Maximiliano [INFN Napoli (Italy); Vivolo, Daniele, E-mail: vivolo@na.infn.it [Dipartimento Scienze Fisiche, Università “Federico II” Napoli (Italy); INFN Napoli (Italy)

    2013-08-01

    VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design for a modern hybrid, high gain, silicon based photodetector based on the combination of a SiPM with a hemispherical vacuum glass PMT standard envelope. In such a device photoelectrons emitted by the photocathode are accelerated and focused by an electric field towards a small focal area covered by the SiPM which therefore acts as an amplifier, thus substituting the classical dynode chain of a PMT. With a view to the realization of a first prototype of VSiPMT our group is carrying out a preliminary work aimed at the study of SiPM performances as an electron detector, including an accurate Geant4-based simulation of the interaction between SiPM and electron beams. In order to perform a full characterization of the SiPM we developed an experimental setup for the extraction and the acceleration of a beam of backward secondary electrons emitted after the bombardment of a carbon foil by a proton beam extracted in a TTT-3 accelerator.

  9. Vacuum Attachment for XRF Scanner

    Science.gov (United States)

    Schramm, Harry F.; Kaiser, Bruce

    2005-01-01

    Vacuum apparatuses have been developed for increasing the range of elements that can be identified by use of x-ray fluorescent (XRF) scanners of the type mentioned in the two immediately preceding articles. As a consequence of the underlying physical principles, in the presence of air, such an XRF scanner is limited to analysis of chlorine and elements of greater atomic number. When the XRF scanner is operated in a vacuum, it extends the range of analysis to lower atomic numbers - even as far as aluminum and sodium. Hence, more elements will be available for use in XRF labeling of objects as discussed in the two preceding articles. The added benefits of the extended capabilities also have other uses for NASA. Detection of elements of low atomic number is of high interest to the aerospace community. High-strength aluminum alloys will be easily analyzed for composition. Silicon, a major contaminant in certain processes, will be detectable before the process is begun, possibly eliminating weld or adhesion problems. Exotic alloys will be evaluated for composition prior to being placed in service where lives depend on them. And in the less glamorous applications, such as bolts and fasteners, substandard products and counterfeit items will be evaluated at the receiving function and never allowed to enter the operation

  10. Cold vacuum drying facility design requirements

    Energy Technology Data Exchange (ETDEWEB)

    IRWIN, J.J.

    1999-07-01

    This document provides the detailed design requirements for the Spent Nuclear Fuel Project Cold Vacuum Drying Facility. Process, safety, and quality assurance requirements and interfaces are specified.

  11. Vacuum Compatible Percussive Dynamic Cone Penetrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics proposes to develop a vacuum compatible percussive dynamic cone penetrometer (PDCP), for establishing soil bin characteristics, with the ultimate...

  12. Vacuum Technology Considerations For Mass Metrology

    Science.gov (United States)

    Abbott, Patrick J.; Jabour, Zeina J.

    2011-01-01

    Vacuum weighing of mass artifacts eliminates the necessity of air buoyancy correction and its contribution to the measurement uncertainty. Vacuum weighing is also an important process in the experiments currently underway for the redefinition of the SI mass unit, the kilogram. Creating the optimum vacuum environment for mass metrology requires careful design and selection of construction materials, plumbing components, pumping, and pressure gauging technologies. We review the vacuum technology1 required for mass metrology and suggest procedures and hardware for successful and reproducible operation. PMID:26989593

  13. Quantum vacuum noise in physics and cosmology.

    Science.gov (United States)

    Davies, P. C. W.

    2001-09-01

    The concept of the vacuum in quantum field theory is a subtle one. Vacuum states have a rich and complex set of properties that produce distinctive, though usually exceedingly small, physical effects. Quantum vacuum noise is familiar in optical and electronic devices, but in this paper I wish to consider extending the discussion to systems in which gravitation, or large accelerations, are important. This leads to the prediction of vacuum friction: The quantum vacuum can act in a manner reminiscent of a viscous fluid. One result is that rapidly changing gravitational fields can create particles from the vacuum, and in turn the backreaction on the gravitational dynamics operates like a damping force. I consider such effects in early universe cosmology and the theory of quantum black holes, including the possibility that the large-scale structure of the universe might be produced by quantum vacuum noise in an early inflationary phase. I also discuss the curious phenomenon that an observer who accelerates through a quantum vacuum perceives a bath of thermal radiation closely analogous to Hawking radiation from black holes, even though an inertial observer registers no particles. The effects predicted raise very deep and unresolved issues about the nature of quantum particles, the role of the observer, and the relationship between the quantum vacuum and the concepts of information and entropy. (c) 2001 American Institute of Physics.

  14. Vacuum technology in the chemical industry

    CERN Document Server

    Jorisch, Wolfgang

    2015-01-01

    Based on the very successful German edition and a seminar held by the German Engineers` Association (VDI) on a regular basis for years now, this English edition has been thoroughly updated and revised to reflect the latest developments. It supplies in particular the special aspects of vacuum technology, applied vacuum pump types and vacuum engineering in the chemical, pharmaceutical and process industry application-segments. The text includes chapters dedicated to latest European regulations for operating in hazardous zones with vacuum systems, methods for process pressure control and regulati

  15. Brain radiation - discharge

    Science.gov (United States)

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  16. Brain injury - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000163.htm Brain injury - discharge To use the sharing features on ... know was in the hospital for a serious brain injury. At home, it will take time for ...

  17. Hypospadias repair - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000158.htm Hypospadias repair - discharge To use the sharing features on this page, please enable JavaScript. Your child had hypospadias repair to fix a birth defect in which ...

  18. Femur fracture repair - discharge

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000166.htm Femur fracture repair - discharge To use the sharing features on this page, please enable JavaScript. You had a fracture (break) in the femur in your leg. It ...

  19. Thyroid gland removal - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000293.htm Thyroid gland removal - discharge To use the sharing features ... surgery. This will make your scar show less. Thyroid Hormone Replacement You may need to take thyroid ...

  20. Breast radiation - discharge

    Science.gov (United States)

    Radiation - breast - discharge ... You may notice changes in the way your breast looks or feels (if you are getting radiation ... after treatment is over. The skin on your breast may become more sensitive or numb. Skin and ...