Science.gov

Sample records for arc plasma science

  1. Evolution of magnetically rotating arc into large area arc plasma

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Li, Wan-Wan; Zhang, Xiao-Ning; Zha, Jun; Xia, Wei-Dong

    2015-06-01

    An arc channel tends to shrink due to its conductivity increasing with the increase of temperature. In this study, to generate large area arc plasma, we construct a magnetically rotating arc plasma generator, which mainly consists of a lanthanide tungsten cathode (13 mm in diameter), a concentric cylindrical graphite anode chamber (60 mm in diameter) and a solenoid coil for producing an axial magnet field. By controlling the cold gas flow, the magnetically rotating arc evolves from constricted mode to diffuse mode, which almost fills the whole arc chamber cross section. Results show that the diffuse arc plasma has better uniformity and stability. The formation mechanism of large area arc plasma is discussed in this paper. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005, 11475174, and 50876101) and the Science Instrument Foundation of the Chinese Academy of Sciences (Grant No. Y201162).

  2. Welding arc plasma physics

    NASA Technical Reports Server (NTRS)

    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.

  3. Gas arc constriction for plasma arc welding

    NASA Technical Reports Server (NTRS)

    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.

  4. Arc initiation in cathodic arc plasma sources

    DOEpatents

    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.

  5. Laser Assisted Plasma Arc Welding

    SciTech Connect

    FUERSCHBACH,PHILLIP W.

    1999-10-05

    Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  6. Controlling Arc Length in Plasma Welding

    NASA Technical Reports Server (NTRS)

    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.

  7. Filters for cathodic arc plasmas

    DOEpatents

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  8. Purification of tantalum by plasma arc melting

    DOEpatents

    Dunn, Paul S.; Korzekwa, Deniece R.

    1999-01-01

    Purification of tantalum by plasma arc melting. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

  9. Purification of tantalum by plasma arc melting

    SciTech Connect

    Dunn, P.S.; Korzekwa, D.R.

    1999-10-26

    Purification of tantalum by plasma arc melting is disclosed. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

  10. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  11. Miniaturized cathodic arc plasma source

    DOEpatents

    Anders, Andre; MacGill, Robert A.

    2003-04-15

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

  12. ARC and Melting Efficiency of Plasma ARC Welds

    NASA Technical Reports Server (NTRS)

    McClure, J. C.; Nunes, A. C.; Evans, D. M.

    1999-01-01

    A series of partial penetration Variable Polarity Plasma Arc welds were made at equal power but various combinations of current and voltage on 2219 Aluminum. Arc efficiency was measured calorimetrically and ranged between 48% and 66% for the conditions of the welds. Arc efficiency depends in different ways on voltage and current. The voltage effect dominates. Raising voltage while reducing current increases arc efficiency. Longer, higher voltage arcs are thought to transfer a greater portion of arc power to the workpiece through shield gas convection. Melting efficiency depends upon weld pool shape as well as arc efficiency. Increased current increases the melting efficiency as it increases the depth to width ratio of the weld pool. Increased plasma gas flow does the same thing. Higher currents are thought to raise arc pressure and depress liquid at the bottom of the weld pool. More arc power then transfers to the workpiece through increasing plasma gas convection. If the power is held constant, the reduced voltage lowers the arc efficiency, while the pool shape change increases the melting efficiency,

  13. Plasma arc torch with coaxial wire feed

    DOEpatents

    Hooper, Frederick M

    2002-01-01

    A plasma arc welding apparatus having a coaxial wire feed. The apparatus includes a plasma arc welding torch, a wire guide disposed coaxially inside of the plasma arc welding torch, and a hollow non-consumable electrode. The coaxial wire guide feeds non-electrified filler wire through the tip of the hollow non-consumable electrode during plasma arc welding. Non-electrified filler wires as small as 0.010 inches can be used. This invention allows precision control of the positioning and feeding of the filler wire during plasma arc welding. Since the non-electrified filler wire is fed coaxially through the center of the plasma arc torch's electrode and nozzle, the wire is automatically aimed at the optimum point in the weld zone. Therefore, there is no need for additional equipment to position and feed the filler wire from the side before or during welding.

  14. ARC length control for plasma welding

    NASA Technical Reports Server (NTRS)

    Iceland, William F. (Inventor)

    1988-01-01

    A control system to be used with a plasma arc welding apparatus is disclosed. The plasma arc welding apparatus includes a plasma arc power supply, a contactor, and an electrode assembly for moving the electrode relative to a work piece. The electrode assembly is raised or lowered by a drive motor. The present apparatus includes a plasma arc adapter connected across the power supply to measure the voltage across the plasma arc. The plasma arc adapter forms a dc output signal input to a differential amplifier. A second input is defined by an adjustable resistor connected to a dc voltage supply to permit operator control. The differential amplifier forms an output difference signal provided to an adder circuit. The adder circuit then connects with a power amplifier which forms the driving signal for the motor. In addition, the motor connects to a tachometor which forms a feedback signal delivered to the adder to provide damping, therby avoiding servo loop overshoot.

  15. Vacuum arc plasma mass separator

    NASA Astrophysics Data System (ADS)

    Paperny, V. L.; Krasov, V. I.; Lebedev, N. V.; Astrakchantsev, N. V.; Chernikch, A. A.

    2015-02-01

    The propagation of a metal plasma flow in a transport system with a curvilinear magnetic field was studied experimentally. The flow was generated by a pulsed vacuum arc discharge with a composite (W+Fe) cathode. The ion energy measurements at the transport system output showed that all ion components were accelerated up to equal energies per charge unit, about 150 eV and 320 eV in the outer and inner areas of the curved plasma flow, respectively. The spatial separation of the atoms of the cathode material was measured at the system output by x-ray fluorescence spectrometry. The ions of the lighter element (Fe) were concentrated in the inner part of the cathodic plasma flow deflected by the magnetic field while the distribution of the heavy element (W) was substantially shifted toward the outer area of the flow. The maximum mass separation efficiency reached 45, the effective value being 7.7. Such a system is promising for use in plasma technology for reprocessing spent nuclear fuel, namely for the separation of the heavy radioactive fission product from nuclear waste.

  16. Plasma arc welding weld imaging

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    A welding torch for plasma arc welding apparatus has a transparent shield cup disposed about the constricting nozzle, the cup including a small outwardly extending polished lip. A guide tube extends externally of the torch and has a free end adjacent to the lip. First and second optical fiber bundle assemblies are supported within the guide tube. Light from a strobe light is transmitted along one of the assemblies to the free end and through the lip onto the weld site. A lens is positioned in the guide tube adjacent to the second assembly and focuses images of the weld site onto the end of the fiber bundle of the second assembly and these images are transmitted along the second assembly to a video camera so that the weld site may be viewed continuously for monitoring the welding process.

  17. Gas Tungsten Arc Welding and Plasma Arc Cutting. Teacher Edition.

    ERIC Educational Resources Information Center

    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…

  18. Arc plasma jets of a nontransferred plasma torch

    SciTech Connect

    Kang, K.D.; Hong, S.H.

    1996-02-01

    The dc plasma torches have been widely used as clean plasma sources for plasma processings such as plasma spraying and synthesis. The plasma flow of a nontransferred plasma torch used for thermal plasma processings is produced by the arc-gas interactions between a cathode tip and an anode nozzle and expands as a jet through the nozzle. In this work, numerically calculated images of the arc plasma characteristics are found over the entire plasma region, including both an arc-gas interacting region inside the torch and a jet expanding region outside the torch. A numerical model used assumes a local thermodynamic equilibrium (LTE) with near-electrode phenomena and compressible flow effects. The computational system is described by a two-dimensional (2-D) axisymmetric model which is solved for plasma temperature and velocity by a control volume approach with the modified SIMPLER algorithm in a real torch geometry.

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

    PubMed

    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. PMID:20545181

  20. Investigation on Plasma Jet Flow Phenomena During DC Air Arc Motion in Bridge-Type Contacts

    NASA Astrophysics Data System (ADS)

    Zhai, Guofu; Bo, Kai; Chen, Mo; Zhou, Xue; Qiao, Xinlei

    2016-05-01

    Arc plasma jet flow in the air was investigated under a bridge-type contacts in a DC 270 V resistive circuit. We characterized the arc plasma jet flow appearance at different currents by using high-speed photography, and two polished contacts were used to search for the relationship between roughness and plasma jet flow. Then, to make the nature of arc plasma jet flow phenomena clear, a simplified model based on magnetohydrodynamic (MHD) theory was established and calculated. The simulated DC arc plasma was presented with the temperature distribution and the current density distribution. Furthermore, the calculated arc flow velocity field showed that the circular vortex was an embodiment of the arc plasma jet flow progress. The combined action of volume force and contact surface was the main reason of the arc jet flow. supported by National Natural Science Foundation of China (Nos. 51307030, 51277038)

  1. Monochromatic imaging of cathodic arc plasma

    SciTech Connect

    Kinrot, U.; Goldsmith, S.; Boxman, R.L.

    1996-02-01

    Vacuum arc deposition (VAD) is an increasingly studied and applied technology that offers potential advantages such as high deposition rates, low deposition temperatures, and good adhesion. In the cathodic vacuum arc, minute hot areas on the cathode surface (``cathode spots``) emit highly ionized metallic plasma jets. Deposition of the cathode material is formed by placing a substrate in the plasma stream. Ceramic thin films such as TiN, SnO{sub 2}, and TiO{sub 2} can be deposited using VAD in the presence of a reactive gas. Plasma parameters such as the density of the various ionic components, ionic kinetic energy, electron temperature, and ion-excited state population densities, all have an important role in the film growth mechanism in VAD and largely affect the film characteristics (structure, morphology, stoichiometry, adhesion, uniformity, thickness, etc.). In the case of ceramic films, the interaction between the expanding plasma and the ambient gas is very important, but poorly understood. Here, monochromatic imaging is presented as a powerful tool for plasma diagnostics, and specifically for the investigation of cathodic vacuum arc plasma. Two-dimensional (2-D) monochromatic images in the visible region of an aluminum cathodic arc burning in helium background gas are presented. Inversion of Abel`s integral enables a reconstruction of the spatial distribution of the plasma emission coefficient. The qualitative and sometimes quantitative nature of the interaction between the expanding plasma and the ambient gas can be visualized with this technique.

  2. Study on Expansion Process of EDM Arc Plasma

    NASA Astrophysics Data System (ADS)

    Natsu, Wataru; Shimoyamada, Mayumi; Kunieda, Masanori

    In order to understand the phenomena of electrical discharge machining (EDM), the characteristics of transition arc plasma in EDM were investigated. The arc plasma was directly observed with a high speed video camera. In addition, to learn more about arc plasma expansion, plasma temperature was measured by spectroscopy. The arc plasma temperature was obtained by measuring the radiant fluxes of two different wavelengths from the arc plasma and applying the line pair method. Furthermore, a new expansion model for EDM arc plasma was proposed based on the observations, and validated by comparing experimental and computed results of the discharge crater.

  3. A mechanism that triggers double arcing during plasma arc cutting

    NASA Astrophysics Data System (ADS)

    Nemchinsky, Valerian

    2009-10-01

    Double arcing (DA) is a phenomenon when a transferred arc, flowing inside an electrically insulated nozzle, breaks into two separate arcs: one that connects the cathode and the nozzle and another that connects the nozzle and a work-piece. It is a commonly accepted opinion that the reason for DA is high voltage drop in the plasma inside the nozzle. However, the specific mechanism that triggers the DA development is not clear. In this paper, we propose such a mechanism. Dielectric films deposited inside the nozzle's orifice play the key role in this mechanism. These films are charged by ion current from plasma. A strong electric field is created inside the film and at the boundary of the film and clean metal of the nozzle. This gives rise to a thermo-field electron emission from the clean metal that borders the film. Emitted electrons are accelerated at the voltage drop between the nozzle and plasma. These electrons produce extra ions, which in turn move back to the film and additionally charge it. This sequence of events leads to explosive instability if the voltage drop inside the nozzle is high enough. Experiments to check the proposed mechanism are suggested.

  4. Melting Efficiency During Plasma Arc Welding

    NASA Technical Reports Server (NTRS)

    McClure, J.C.; Evans, D. M.; Tang, W.; Nunes, A. C.

    1999-01-01

    A series of partial penetration Variable Polarity Plasma Arc welds were made at equal power but various combinations of current and voltage on 2219 aluminum. Arc Efficiency was measured calorimetrically and ranged between 48% and 66%. Melting efficiency depends on the weld pool shape. Increased current increases the melting efficiency as it increases the depth to width ratio of the weld pool. Higher currents are thought to raise arc pressure and depress the liquid at the bottom of the weld pool causing a more nearly two dimensional heat flow condition.

  5. Plasma arc heated secondary combustion chamber

    SciTech Connect

    Haun, R.; Paulson, B.; Schlienger, M.; Goerz, D.; Kerns, J.; Vernazza, J.

    1995-02-01

    This paper describes a secondary combustion chamber (SCC) for hazardous waste treatment systems that uses a plasma arc torch as the heat source. Developed under a cooperative research and development agreement (CRADA) between Retech, Inc. and Lawrence Livermore National Laboratory (LLNL), the unit is intended primarily to handle the off-gas from a Plasma Arc Centrifugal Treatment (PACT) system. ft is designed to heat the effluent gas which may contain volatile organic compounds, and maintain the gas temperature above 1000 C for two seconds or more. The benefits of using a plasma arc gas heater are described in comparison to a conventional fossil fuel heated SCC. Thermal design considerations are discussed. Analysis and experimental results are presented to show the effectiveness in destroying hazardous compounds and reducing the total volume of gaseous emissions.

  6. Electric-arc steam plasma generator

    NASA Astrophysics Data System (ADS)

    Anshakov, A. S.; Urbakh, E. K.; Radko, S. I.; Urbakh, A. E.; Faleev, V. A.

    2015-01-01

    Investigation results on the arc plasmatorch for water-steam heating are presented. The construction arrangement of steam plasma generator with copper electrodes of the stepped geometry was firstly implemented. The energy characteristics of plasmatorch and erosion of electrodes reflect the features of their behavior at arc glow in the plasma-forming environment of steam. The results of numerical study of the thermal state of the composite copper-steel electrodes had a significant influence on optimization of anode water-cooling aimed at improvement of its operation life.

  7. Update on plasma arc centrifugal treatment

    SciTech Connect

    Haun, R.E.; Paulson, W.S.; Eschenbach, R.C.

    1996-12-31

    Over the last eight years, Retech has developed a plasma-powered system for destroying organics and stabilizing metal oxides in a non-leaching slag. The system, termed Plasma Arc Centrifugal Treatment (PACT), can handle a variety of waste streams such as contaminated soils, sludges, ion-exchange resins, incinerator bottom and fly-ash and drummed waste among others. This paper will review recent commercial applications of the technology. Three Plasma Arc Centrifugal Treatment systems having an eight-foot diameter centrifuge (PACT-8) are in the construction phase. One will be used in the Lockheed Environmental Systems and Technologies (LESAT) system for remediating Pit 9 at the Idaho National Engineering Lab (INEL). A second unit will be located at the Retech plant in Ukiah, California. The third unit will be located at a site in Munster, Germany.

  8. Entropy in an Arc Plasma Source

    SciTech Connect

    Kaminska, A.; Dudeck, M

    2008-03-19

    The entropy properties in a D.C. argon arc plasma source are studied. The local thermodynamical entropy relations are established for a set of uniform sub-systems (Ar, Ar{sup +}, e) in order to deduce the entropy balance equation in presence of dissipative effects and in the case of a thermal non equilibrium. Phenomenological linear laws are deduced in near equilibrium situation. The flow parameters inside the plasma source are calculated by a Navier-Stokes fluid description taking into account a thermal local non equilibrium. The entropy function is calculated in the plasma source using the values of the local variables obtained from the numerical code.

  9. Plasma magmavication of soils by nontransferred arc

    SciTech Connect

    Mayne, P.W.; Burns, S.E.; Circeo, L.J.

    2000-05-01

    Electrical plasma arcs create very high temperatures (T > 4,000 C) that can be specifically directed for the in-place melting of soils. This overview presents a summary of the basic features and capabilities of plasma torches having a nontransferred type of arc for the in situ vitrification of soils. Laboratory chamber experiments using 100 kW and 240 kW plasma systems and full-scale field trials using a 1 MW portable system have successfully melted a variety of soil types, including sands, silts, and clays. Within five minutes' exposure to the arc, a core region of magma forms within the soil matrix that expands radially outward and upward as the torch is pulled out vertically. Several days afterwards, the molten zone cools to form an artificial igneous rock similar to obsidian, basalt, or granite. The size of the vitrified mass is proportional to the electrical power demand. The plasma torch has a configuration similar to a flamethrower and will therefore be amenable to placement down boreholes for purposes of in situ ground modification and subsurface remediation.

  10. Interactions between laser and arc plasma during laser-arc hybrid welding of magnesium alloy

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Chen, Minghua

    2011-09-01

    This paper presents the results of the investigation on the interactions between laser and arc plasma during laser-arc hybrid welding on magnesium alloy AZ31B using the spectral diagnose technique. By comparably analyzing the variation in plasma information (the shape, the electron temperature and density) of single tungsten inert gas (TIG) welding with the laser-arc hybrid welding, it is found that the laser affects the arc plasma through the keyhole forming on the workpiece. Depending on the welding parameters there are three kinds of interactions taking place between laser and arc plasma.

  11. Modelling the Plasma Jet in Multi-Arc Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.; Möhwald, K.; Lummer, C.

    2016-08-01

    Particle in-flight characteristics in atmospheric plasma spraying process are determined by impulse and heat energy transferred between the plasma jet and injected powder particles. One of the important factors for the quality of the plasma-sprayed coatings is thus the distribution of plasma gas temperatures and velocities in plasma jet. Plasma jets generated by conventional single-arc plasma spraying systems and their interaction with powder particles were subject matter of intensive research. However, this does not apply to plasma jets generated by means of multi-arc plasma spraying systems yet. In this study, a numerical model has been developed which is designated to dealing with the flow characteristics of the plasma jet generated by means of a three-cathode spraying system. The upstream flow conditions, which were calculated using a priori conducted plasma generator simulations, have been coupled to the plasma jet simulations. The significances of the relevant numerical assumptions and aspects of the models are analyzed. The focus is placed on to the turbulence and diffusion/demixing modelling. A critical evaluation of the prediction power of the models is conducted by comparing the numerical results to the experimental results determined by means of emission spectroscopic computed tomography. It is evident that the numerical models exhibit a good accuracy for their intended use.

  12. Dual Torch Plasma Arc Furnace for Medical Waste Treatment

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Kikuchi, M.; Li, Heping; Iwao, T.; Inaba, T.

    2007-12-01

    In this paper, characteristics of a dual torch plasma arc used for hazardous waste treatment and operated at atmospheric pressure are studied, and also compared with those of the multi-torch plasma arc and the single torch plasma arc. The dual torch plasma arc is generated between the cathode and anode with argon as the working gas. The temperature distributions of the plasma arc are measured using a spectroscope and line pair method with the assumption of local thermodynamic equilibrium (LTE) for the DC arc current I = 100 A and argon flow rate Q = 15 slpm. The measurements show that the temperatures of the dual torch arc plasma in the regions near the cathode, the anode and the center point are 10,000 K, 11,000 K and 9,000 K, respectively. And the high temperature region of the multi torch plasma arc is of double or much wider size than that of a conventional dual torch plasma arc and single plasma torch. Based on the preceding studies, a dual torch plasma arc furnace is developed in this study. The measured gas temperature at the center region of the argon arc is about 11,000 K for the case of I = 200 A and Q = 30 slpm operated in atmosphere.

  13. Three-dimensional modeling of the plasma arc in arc welding

    SciTech Connect

    Xu, G.; Tsai, H. L.; Hu, J.

    2008-11-15

    Most previous three-dimensional modeling on gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) focuses on the weld pool dynamics and assumes the two-dimensional axisymmetric Gaussian distributions for plasma arc pressure and heat flux. In this article, a three-dimensional plasma arc model is developed, and the distributions of velocity, pressure, temperature, current density, and magnetic field of the plasma arc are calculated by solving the conservation equations of mass, momentum, and energy, as well as part of the Maxwell's equations. This three-dimensional model can be used to study the nonaxisymmetric plasma arc caused by external perturbations such as an external magnetic field. It also provides more accurate boundary conditions when modeling the weld pool dynamics. The present work lays a foundation for true three-dimensional comprehensive modeling of GTAW and GMAW including the plasma arc, weld pool, and/or electrode.

  14. Three-dimensional modeling of the plasma arc in arc welding

    NASA Astrophysics Data System (ADS)

    Xu, G.; Hu, J.; Tsai, H. L.

    2008-11-01

    Most previous three-dimensional modeling on gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) focuses on the weld pool dynamics and assumes the two-dimensional axisymmetric Gaussian distributions for plasma arc pressure and heat flux. In this article, a three-dimensional plasma arc model is developed, and the distributions of velocity, pressure, temperature, current density, and magnetic field of the plasma arc are calculated by solving the conservation equations of mass, momentum, and energy, as well as part of the Maxwell's equations. This three-dimensional model can be used to study the nonaxisymmetric plasma arc caused by external perturbations such as an external magnetic field. It also provides more accurate boundary conditions when modeling the weld pool dynamics. The present work lays a foundation for true three-dimensional comprehensive modeling of GTAW and GMAW including the plasma arc, weld pool, and/or electrode.

  15. Automated Variable-Polarity Plasma-Arc Welding

    NASA Technical Reports Server (NTRS)

    Numes, A. C., Jr.; Bayless, E. O., Jr.; Jones, S. C., III; Munafo, P.; Munafo, A.; Biddle, A.; Wilson, W.

    1984-01-01

    Variable-polarity plasma-arc methods produces better welds at lower cost than gas-shielded tungsten-arc welding in assemblies. Weld porosity very low and costs of joint preparation, depeaking, inspection, and weld repair minimized.

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

    SciTech Connect

    Anders, Andre

    2011-12-18

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

  17. Process characteristics of fibre-laser-assisted plasma arc welding

    NASA Astrophysics Data System (ADS)

    Mahrle, A.; Schnick, M.; Rose, S.; Demuth, C.; Beyer, E.; Füssel, U.

    2011-08-01

    Experimental and theoretical investigations on fibre-laser-assisted plasma arc welding (LAPW) were performed. Welding experiments were carried out on aluminium and steel sheets. In the case of a highly focused laser beam and a separate arrangement of plasma torch and laser beam, high-speed video recordings of the plasma arc and corresponding measurements of the time-dependent arc voltage revealed differences in the process behaviour for both materials. In the case of aluminium welding, a sharp decline in arc voltage and stabilization and guiding of the anodic arc root was observed whereas in steel welding the arc voltage was slightly increased after the laser beam was switched on. However, significant improvement of the melting efficiency with the combined action of plasma arc and laser beam was achieved for both types of material. Theoretical results of additional numerical simulations of the arc behaviour suggest that the properties of the arc plasma are mainly influenced not by a direct interaction with the laser radiation but by the laser-induced evaporation of metal. Arc stabilization with increased current densities is predicted for moderate rates of evaporated metal only whereas metal vapour rates above a certain threshold causes a destabilization of the arc and reduced current densities along the arc axis.

  18. Modeling of thermal plasma arc technology FY 1994 report

    SciTech Connect

    Hawkes, G.L.; Nguyen, H.D.; Paik, S.; McKellar, M.G.

    1995-03-01

    The thermal plasma arc process is under consideration to thermally treat hazardous and radioactive waste. A computer model for the thermal plasma arc technology was designed as a tool to aid in the development and use of the plasma arc-Joule beating process. The value of this computer model is to: (a) aid in understanding the plasma arc-Joule beating process as applied to buried waste or exhumed buried waste, (b) help design melter geometry and electrode configuration, (c) calculate the process capability of vitrifying waste (i.e., tons/hour), (d) develop efficient plasma and melter operating conditions to optimize the process and/or reduce safety hazards, (e) calculate chemical reactions during treatment of waste to track chemical composition of off-gas products, and composition of final vitrified waste form and (f) help compare the designs of different plasma-arc facilities. A steady-state model of a two-dimensional axisymmetric transferred plasma arc has been developed and validated. A parametric analysis was performed that studied the effects of arc length, plasma gas composition, and input power on the temperatures and velocity profiles of the slag and plasma gas. A two-dimensional transient thermo-fluid model of the US Bureau of Mines plasma arc melter has been developed. This model includes the growth of a slag pool. The thermo-fluid model is used to predict the temperature and pressure fields within a plasma arc furnace. An analysis was performed to determine the effects of a molten metal pool on the temperature, velocity, and voltage fields within the slag. A robust and accurate model for the chemical equilibrium calculations has been selected to determine chemical composition of final waste form and off-gas based on the temperatures and pressures within the plasma-arc furnace. A chemical database has been selected. The database is based on the materials to be processed in the plasma arc furnaces.

  19. Numerical Study on Arc Plasma Behavior During Arc Commutation Process in Direct Current Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Ma, Ruiguang; Wu, Yi; Sun, Hao; Niu, Chunping; Rong, Mingzhe

    2012-02-01

    This paper focuses on the numerical investigation of arc plasma behavior during arc commutation process in a medium-voltage direct current circuit breaker (DCCB) contact system. A three-dimensional magneto-hydrodynamic (MHD) model of air arc plasma in the contact system of a DCCB is developed, based on commercial software FLUENT. Coupled electromagnetic and gas dynamic interactions are considered as usual, and a thin layer of nonlinear electrical resistance elements is used to represent the voltage drop of plasma sheath and the formation of new arc root. The distributions of pressure, temperature, gas flow and current density of arc plasma in arc region are calculated. The simulation results indicate that the pressure distribution related to the contact system has a strong effect on the arc commutation process, arising from the change of electrical conductivity in the arc root region. In DCCB contact system, the pressure of arc root region will be concentrated and higher if the space above the moving contact is enclosed, which is not good for arc root commutation. However, when the region is opened, the pressure distribution would be lower and more evenly, which is favorable for the arc root commutation.

  20. The effect of plasma on solar cell array arc characteristics

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.; Tyree, E.

    1984-01-01

    The influence from the ambient plasma on the arc characteristics of a negatively biased solar cell array was investigated. The arc characteristics examined were the peak current during an arc, the decay time as the arc terminates, and the charge lost during the arc. These arc characteristics were examined in a nitrogen plasma with charge densities ranging from 15,000 to 45,000 cu cm. Background gas pressures ranged from 8x1,000,000 to 6x100,000 torr. Over these ranges of parameters no significant effect on the arc characteristics were seen. Arc characteristics were also examined for three gas species: helium, nitrogen and argon. The helium arcs have higher peak currents and shorter decay times than nitrogen and argon arcs. There are slight differences in the arc characteristics between nitrogen and argon. These differences may be caused by the differences in mass of the respective species. Also, evidence is presented for an electron emission mechanism appearing as a precursor to solar array arcs. Occassionally the plasma generator could be turned off, and currents could still be detected in the vacuum system. When these currents are presented, arcs may occur.

  1. Characteristics of Single Cathode Cascaded Bias Voltage Arc Plasma

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  2. Applicability of moire deflection tomography for diagnosing arc plasmas

    SciTech Connect

    Chen Yunyun; Song Yang; He Anzhi; Li Zhenhua

    2009-01-20

    The argon arc plasma whose central temperature, 1.90x10{sup 4} K, is used as a practical example for an experiment to research the applicability of moire deflection tomography in arc plasma flow-field diagnosis. The experimental result indicates that moire deflection of the measured argon arc plasma is very small, even smaller than that of a common flame with the maximal temperature of nearly 1.80x10{sup 3} K. The refractive-index gradient in moire deflection tomography mainly contributes to the temperature gradient in essence when the probe wavelength and pressure are certain in plasma diagnosis. The applicable temperature ranges of moire deflection tomography in the argon arc plasma diagnosis are given with the probe wavelength 532 nm at 1 atm in certain measuring error requirements. In a word, the applicable temperature range of moire deflection tomography for arc plasma diagnosis is intimately related to the probe wavelength and the practical measuring requirements.

  3. NASA GRC and MSFC Space-Plasma Arc Testing Procedures

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Vayner, Boris V.; Galofaro, Joel T,; Hillard, G. Barry; Vaughn, Jason; Schneider, Todd

    2005-01-01

    Tests of arcing and current collection in simulated space plasma conditions have been performed at the NASA Glenn Research Center (GRC) in Cleveland, Ohio, for over 30 years and at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, for almost as long. During this period, proper test conditions for accurate and meaningful space simulation have been worked out, comparisons with actual space performance in spaceflight tests and with real operational satellites have been made, and NASA has achieved our own internal standards for test protocols. It is the purpose of this paper to communicate the test conditions, test procedures, and types of analysis used at NASA GRC and MSFC to the space environmental testing community at large, to help with international space-plasma arcing-testing standardization. To be discussed are: 1.Neutral pressures, neutral gases, and vacuum chamber sizes. 2. Electron and ion densities, plasma uniformity, sample sizes, and Debuy lengths. 3. Biasing samples versus self-generated voltages. Floating samples versus grounded. 4. Power supplies and current limits. Isolation of samples from power supplies during arcs. 5. Arc circuits. Capacitance during biased arc-threshold tests. Capacitance during sustained arcing and damage tests. Arc detection. Prevention sustained discharges during testing. 6. Real array or structure samples versus idealized samples. 7. Validity of LEO tests for GEO samples. 8. Extracting arc threshold information from arc rate versus voltage tests. 9. Snapover and current collection at positive sample bias. Glows at positive bias. Kapon (R) pyrolisis. 10. Trigger arc thresholds. Sustained arc thresholds. Paschen discharge during sustained arcing. 11. Testing for Paschen discharge threshold. Testing for dielectric breakdown thresholds. Testing for tether arcing. 12. Testing in very dense plasmas (ie thruster plumes). 13. Arc mitigation strategies. Charging mitigation strategies. Models. 14. Analysis of test results

  4. Direct probing of anode arc root dynamics and voltage instability in a dc non-transferred arc plasma jet

    NASA Astrophysics Data System (ADS)

    Ghorui, S.; Tiwari, N.; Meher, K. C.; Jan, A.; Bhat, A.; Sahasrabudhe, S. N.

    2015-12-01

    The transient dynamics of the anode arc root in a dc non-transferred arc plasma torch is captured through fast photography and directly correlated with the associated voltage instability for the first time. The coexistence of multiple arc roots, the transition to a single arc root, root formation and extinction are investigated for the steady, takeover and re-strike modes of the arc. Contrary to the usual concept, the emerging plasma jet of a dc non-transferred arc plasma torch is found to carry current. An unusually long self-propelled arc plasma jet, a consequence of the phenomenon, is demonstrated.

  5. Robotic Variable Polarity Plasma Arc (VPPA) Welding

    NASA Technical Reports Server (NTRS)

    Jaffery, Waris S.

    1993-01-01

    The need for automated plasma welding was identified in the early stages of the Space Station Freedom Program (SSFP) because it requires approximately 1.3 miles of welding for assembly. As a result of the Variable Polarity Plasma Arc Welding (VPPAW) process's ability to make virtually defect-free welds in aluminum, it was chosen to fulfill the welding needs. Space Station Freedom will be constructed of 2219 aluminum utilizing the computer controlled VPPAW process. The 'Node Radial Docking Port', with it's saddle shaped weld path, has a constantly changing surface angle over 360 deg of the 282 inch weld. The automated robotic VPPAW process requires eight-axes of motion (six-axes of robot and two-axes of positioner movement). The robot control system is programmed to maintain Torch Center Point (TCP) orientation perpendicular to the part while the part positioner is tilted and rotated to maintain the vertical up orientation as required by the VPPAW process. The combined speed of the robot and the positioner are integrated to maintain a constant speed between the part and the torch. A laser-based vision sensor system has also been integrated to track the seam and map the surface of the profile during welding.

  6. Robotic Variable Polarity Plasma Arc (VPPA) welding

    NASA Astrophysics Data System (ADS)

    Jaffery, Waris S.

    1993-02-01

    The need for automated plasma welding was identified in the early stages of the Space Station Freedom Program (SSFP) because it requires approximately 1.3 miles of welding for assembly. As a result of the Variable Polarity Plasma Arc Welding (VPPAW) process's ability to make virtually defect-free welds in aluminum, it was chosen to fulfill the welding needs. Space Station Freedom will be constructed of 2219 aluminum utilizing the computer controlled VPPAW process. The 'Node Radial Docking Port', with it's saddle shaped weld path, has a constantly changing surface angle over 360 deg of the 282 inch weld. The automated robotic VPPAW process requires eight-axes of motion (six-axes of robot and two-axes of positioner movement). The robot control system is programmed to maintain Torch Center Point (TCP) orientation perpendicular to the part while the part positioner is tilted and rotated to maintain the vertical up orientation as required by the VPPAW process. The combined speed of the robot and the positioner are integrated to maintain a constant speed between the part and the torch. A laser-based vision sensor system has also been integrated to track the seam and map the surface of the profile during welding.

  7. Acoustic stabilization of electric arc instabilities in nontransferred plasma torches

    SciTech Connect

    Rat, V.; Coudert, J. F.

    2010-03-08

    Electric arc instabilities in dc plasma torches lead to nonhomogeneous treatments of nanosized solid particles or liquids injected within thermal plasma jets. This paper shows that an additional acoustic resonator mounted on the cathode cavity allows reaching a significant damping of these instabilities, particularly the Helmholtz mode of arc oscillations. The acoustic resonator is coupled with the Helmholtz resonator of the plasma torch limiting the amplitude of arc voltage variations. It is also highlighted that this damping is dependent on friction effects in the acoustic resonator.

  8. Energy Balance in DC Arc Plasma Melting Furnace

    NASA Astrophysics Data System (ADS)

    Zhao, Peng; Meng, Yuedong; Yu, Xinyao; Chen, Longwei; Jiang, Yiman; Ni, Guohua; Chen, Mingzhou

    2009-04-01

    In order to treat hazardous municipal solid waste incinerator's (MSWI) fly ash, a new DC arc plasma furnace was developed. Taking an arc of 100 V/1000 A DC as an example, the heat transfer characteristics of the DC arc plasma, ablation of electrodes, heat properties of the fly ash during melting, heat transfer characteristics of the flue gas, and heat loss of the furnace were analyzed based on the energy conservation law, so as to achieve the total heat information and energy balance during plasma processing, and to provide a theoretical basis for an optimized design of the structure and to improve energy efficiency.

  9. Variable-Polarity Plasma Arc Welding Of Alloy 2219

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.; Nunes, Arthur C., Jr.

    1989-01-01

    Report presents results of study of variable-polarity plasma arc (VPPA) welding of aluminum alloy 2219. Consists of two parts: Examination of effects of microsegregation and transient weld stress on macrosegregation in weld pool and, electrical characterization of straight- and reverse-polarity portions of arc cycle.

  10. INTERIOR VIEW, LOOKING SOUTHWEST, WITH PLASMA ARC BURNING MACHINE (GALT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW, LOOKING SOUTHWEST, WITH PLASMA ARC BURNING MACHINE (GALT INDUSTRIES) WHICH CUTS STEEL SHAPES AND OPERATOR PHILIP WILLOUBY. - O'Neal Steel, Incorporated, Fabrication Shop, 744 Forty-first Avenue North, Birmingham, Jefferson County, AL

  11. Method for defect free keyhole plasma arc welding

    NASA Technical Reports Server (NTRS)

    Harwig, Dennis D. (Inventor); Hunt, James F. (Inventor); Ryan, Patrick M. (Inventor); Fisher, Walter J. (Inventor)

    1993-01-01

    A plasma arc welding process for welding metal of increased thickness with one pass includes operating the plasma arc welding apparatus at a selected plasma gas flow rate, travel speed and arc current, to form a weld having a penetration ratio to weld height to weld width, and maintaining the penetration ratio at less than 0.74. Parameters for the plasma gas flow rate, travel speed and arc current are adjusted to a steady state condition during a start up period and maintained during the steady state condition to complete a weld. During a terminal stopping period, the travel speed is stopped and instantaneously replaced by filler wire which adds material to fill the keyhole that had been formed by the welding process. Parameters are subsequently adjusted during the stopping period to terminate the weld in a sound manner.

  12. Inert-Gas Diffuser For Plasma Or Arc Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Spencer, Carl N.; Hosking, Timothy J.

    1994-01-01

    Inert-gas diffuser provides protective gas cover for weld bead as it cools. Follows welding torch, maintaining continuous flow of argon over newly formed joint and prevents it from oxidizing. Helps to ensure welds of consistently high quality. Devised for plasma arc keyhole welding of plates of 0.25-in. or greater thickness, also used in tungsten/inert-gas and other plasma or arc welding processes.

  13. Synthesis of silicon nanotubes by DC arc plasma method

    SciTech Connect

    Tank, C. M.; Bhoraskar, S. V.; Mathe, V. L.

    2012-06-05

    Plasma synthesis is a novel technique of synthesis of nanomaterials as they provide high rate of production and promote metastable reactions. Very thin walled silicon nanotubes were synthesized in a DC direct arc thermal plasma reactor. The effect of parameters of synthesis i.e. arc current and presence of hydrogen on the morphology of Si nanoparticles is reported. Silicon nanotubes were characterized by Transmission Electron Microscopy (TEM), Local Energy Dispersive X-ray analysis (EDAX), and Scanning Tunneling Microscopy (STM).

  14. Destruction of hazardous waste material using plasma arc technology

    SciTech Connect

    Brooman, E.W.; Patun, R.J.; Qazi, M.A.

    1995-12-31

    This paper gives an overview of Plasma Arc Technology (PAT), how it works, and whether it is a pyrolysis or combustion process. Arc generators and their applications are described along with examples of successful waste treatment applications. This paper also evaluates the economic impact and the advantages of using PAT systems. This paper concludes with a description of a PAT system that is being used to destroy military wastes, and describes the task plan, the selection process for the waste materials, and the Plasma Arc Centrifugal Treatment (PACT-2) system.

  15. NASA GRC and MSFC Space-Plasma Arc Testing Procedures

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Vayner, Boris V.; Galofaro, Joel T.; Hillard, G. Barry; Vaughn, Jason; Schneider, Todd

    2007-01-01

    Tests of arcing and current collection in simulated space plasma conditions have been performed at the NASA Glenn Research Center (GRC) in Cleveland, Ohio, for over 30 years and at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, for almost as long. During this period, proper test conditions for accurate and meaningful space simulation have been worked out, comparisons with actual space performance in spaceflight tests and with real operational satellites have been made, and NASA has achieved our own internal standards for test protocols. It is the purpose of this paper to communicate the test conditions, test procedures, and types of analysis used at NASA GRC and MSFC to the space environmental testing community at large, to help with international space-plasma arcing-testing standardization. Discussed herein are neutral gas conditions, plasma densities and uniformity, vacuum chamber sizes, sample sizes and Debye lengths, biasing samples versus self-generated voltages, floating samples versus grounded samples, test electrical conditions, arc detection, preventing sustained discharges during testing, real samples versus idealized samples, validity of LEO tests for GEO samples, extracting arc threshold information from arc rate versus voltage tests, snapover, current collection, and glows at positive sample bias, Kapton pyrolysis, thresholds for trigger arcs, sustained arcs, dielectric breakdown and Paschen discharge, tether arcing and testing in very dense plasmas (i.e. thruster plumes), arc mitigation strategies, charging mitigation strategies, models, and analysis of test results. Finally, the necessity of testing will be emphasized, not to the exclusion of modeling, but as part of a complete strategy for determining when and if arcs will occur, and preventing them from occurring in space.

  16. Scalability of Localized Arc Filament Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Brown, Clifford A.

    2008-01-01

    Temporal flow control of a jet has been widely studied in the past to enhance jet mixing or reduce jet noise. Most of this research, however, has been done using small diameter low Reynolds number jets that often have little resemblance to the much larger jets common in real world applications because the flow actuators available lacked either the power or bandwidth to sufficiently impact these larger higher energy jets. The Localized Arc Filament Plasma Actuators (LAFPA), developed at the Ohio State University (OSU), have demonstrated the ability to impact a small high speed jet in experiments conducted at OSU and the power to perturb a larger high Reynolds number jet in experiments conducted at the NASA Glenn Research Center. However, the response measured in the large-scale experiments was significantly reduced for the same number of actuators compared to the jet response found in the small-scale experiments. A computational study has been initiated to simulate the LAFPA system with additional actuators on a large-scale jet to determine the number of actuators required to achieve the same desired response for a given jet diameter. Central to this computational study is a model for the LAFPA that both accurately represents the physics of the actuator and can be implemented into a computational fluid dynamics solver. One possible model, based on pressure waves created by the rapid localized heating that occurs at the actuator, is investigated using simplified axisymmetric simulations. The results of these simulations will be used to determine the validity of the model before more realistic and time consuming three-dimensional simulations are conducted to ultimately determine the scalability of the LAFPA system.

  17. Arcing of negatively biased solar cells in a plasma environment

    NASA Astrophysics Data System (ADS)

    Upschulte, B. L.; Marinelli, W. J.; Carleton, K. L.; Weyl, G.; Aifer, E.; Hastings, D. E.

    1994-05-01

    Experimental and theoretical efforts have been conducted to investigate the arcing of negatively biased solar arrays in a low-Earth orbit plasma environment. Experiments were conducted in an ultrahigh vacuum plasma test chamber, where the environment could be controlled carefully. Outgassing of the adhesive used to bind the protective coverglass to the solar cells was determined to be a key factor in observed arcing rates. These rates could be reduced by greater than a factor of 100 by eliminating or fully outgassing the excess adhesive remaining at the edge of the solar cells. Optical emission from solar cell arcs was observed to correlate linearly with arc current, both temporally and in total intensity. Solar cell arcing rates were also observed to scale linearly with plasma density. The plasma scaling is in good agreement with a theory based on enhanced field electron emission charging of dielectric surfaces, leading to enhanced electric fields at the conductor/adhesive/plasma triple junction. Apparent thresholds for solar cell arcing are reported.

  18. Magneto-plasma-dynamic arc thruster

    NASA Technical Reports Server (NTRS)

    Burkhart, J. A. (Inventor)

    1973-01-01

    The performance of a magnetoplasmadynamic arc thruster, in the 600 to 2,100 seconds specific impulse range, was improved by locating its cathode in the exhaust beam downstream of the anode and main propellant injection point.

  19. Mathematical Model Of Variable-Polarity Plasma Arc Welding

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1996-01-01

    Mathematical model of variable-polarity plasma arc (VPPA) welding process developed for use in predicting characteristics of welds and thus serves as guide for selection of process parameters. Parameters include welding electric currents in, and durations of, straight and reverse polarities; rates of flow of plasma and shielding gases; and sizes and relative positions of welding electrode, welding orifice, and workpiece.

  20. Arc Plasma Gun With Coaxial Powder Feed

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, Isidor

    1988-01-01

    Redesigned plasma gun provides improved metallic and ceramic coatings. Particles injected directly through coaxial bore in cathode into central region of plasma jet. Introduced into hotter and faster region of plasma jet.

  1. Influence of a transverse magnetic field on arc root movements in a dc plasma torch: Diamagnetic effect of arc column

    SciTech Connect

    Kim, Keun Su

    2009-03-23

    The effect of a transverse magnetic field on the anodic arc root movement inside a dc plasma torch has been investigated. The arc voltage fluctuation, which represents the degree of the arc instability, was reduced to 28.6% of the original value and the high frequency components in the voltage signal also decreased in their magnitudes. The inherent arc instability in a dc thermal plasma torch seems to be suppressed by a diamagnetic effect of the arc column. Furthermore, the measured voltage wave forms indicated that the arc root attachment mode would be controllable by a transverse magnetic field.

  2. Numerical modeling of arc plasma generator for chemical laser applications

    NASA Astrophysics Data System (ADS)

    Sagar, Vidya; Ravikant, Chhaya; Singhal, Gaurav; Mittal, Alok P.

    2012-05-01

    The results of the numerical modeling of arc discharge phenomenon relevant to hydrogen fluoride/deuterium fluoride (HF/DF) laser applications are given. The overall mechanics of arc discharge phenomena on the basis of numerical modeling employing the commercial code COMSOL is discussed. The equations for a 2D axisymmetric, weakly compressible, laminar flow with heat transfer and the coupled hydrodynamic and electromagnetic equations are solved using the SIMPLE algorithm. The variations in the material properties, temperature, and velocity due to the generated arc are studied. A comparison of the results obtained with those from the studies available in the literature validates the computational data. Since each designed plasma arc tunnel is unique in itself and specific in application, this would enable one to alter arc discharge parameters to optimize a specific laser.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Gas Contamination In Plasma-Arc-Welded Aluminum

    NASA Technical Reports Server (NTRS)

    Mcclure, John C.; Torres, Martin R.; Gurevitch, Alan C.; Newman, Robert A.

    1992-01-01

    Document describes experimental investigation on visible and tactile effects of gaseous contaminants in variable-polarity plasma arc (VPPA) welding of 2219 T-87 aluminum alloy. Contaminant gases (nitrogen, methane, oxygen, and hydrogen) introduced in argon arc and in helium shield gas in various controlled concentrations. Report represents results of experiments in form of photographs of fronts, backs, polished cross sections, and etched cross sections of welds made with various contaminants at various concentrations. Provides detailed discussion of conditions under which welds made.

  5. Shunting arc plasma source for pure carbon ion beama)

    NASA Astrophysics Data System (ADS)

    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/mm2 at the peak of the pulse.

  6. Shunting arc plasma source for pure carbon ion beam.

    PubMed

    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. PMID:22380206

  7. The plasma arc torch -- its electrical and thermal characteristics

    SciTech Connect

    Camacho, S.L.

    1995-12-31

    The plasma arc torch is a very effective heating device. Plasma arc heating technology is very appropriate and essential for product manufacture and for remediating and protecting the environment. The plasma torch initiates and maintains a length of arc column, similar to a lightning bolt, and the electrically-conducting column is used in the conversion of electricity into heat energy. The format of the heat energy delivery is a low-mass, high-enthalpy gas. Heat energy is delivered by the plasma torch with a minimum of mass -- only about 2--3% of the mass delivery from a combustion heater that is delivering the same heat enthalpy. This virtually mass-less heat is ideal for promoting very rapid physical changes and chemical changes in the material being heated. It is ideal for the pyrolysis (or gasification) of organic materials and for the vitrification (or melting) of inorganic materials -- processes that are desirable for new product manufacture and for environmental remediation and protection. Plasma arc heating technology has been perfected by industry during the last 20--30 years, and the industrial sector today is employing this unique heating source in product manufacture and, lately, in environmental remediation and protection processes. It is a cost-effective industrial heat source. The primary objective of this paper is to familiarize one with plasma heaters and their operating characteristics. The essential elements of the plasma arc torch: electrodes, insulators, gas injectors, water-cooling, electrical connectors, etc., are described and the electrical and thermal characteristics of this novel heating device are highlighted. An overview of today`s employment of plasma heating technology and a sample of some of today`s applications of the technology in the industrial sector in the United States and around the world are presented.

  8. Cathodic arcs

    SciTech Connect

    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.

  9. Vacuum arc plasma thrusters with inductive energy storage driver

    NASA Technical Reports Server (NTRS)

    Schein, Jochen (Inventor); Gerhan, Andrew N. (Inventor); Woo, Robyn L. (Inventor); Au, Michael Y. (Inventor); Krishnan, Mahadevan (Inventor)

    2004-01-01

    An apparatus for producing a vacuum arc plasma source device using a low mass, compact inductive energy storage circuit powered by a low voltage DC supply acts as a vacuum arc plasma thruster. An inductor is charged through a switch, subsequently the switch is opened and a voltage spike of Ldi/dt is produced initiating plasma across a resistive path separating anode and cathode. The plasma is subsequently maintained by energy stored in the inductor. Plasma is produced from cathode material, which allows for any electrically conductive material to be used. A planar structure, a tubular structure, and a coaxial structure allow for consumption of cathode material feed and thereby long lifetime of the thruster for long durations of time.

  10. Arc Plasma Synthesis of Nanostructured Materials: Techniques and Innovations

    SciTech Connect

    Das, A. K.; Bhoraskar, S. V.; Kakati, M.; Karmakar, Soumen

    2008-10-23

    Arc plasma aided synthesis of nanostructured materials has the potential of producing complex nano phase structures in bulk quantities. Successful implementation of this potential capability to industrial scale nano generation needs establishment of a plasma parameter control regime in terms of plasma gas, flow pattern, pressure, local temperature and the plasma fields to obtain the desired nano phase structures. However, there is a need to design innovative in situ experiments for generation of an extensive database and subsequently to correlate plasma parameters to the size, shape and phase of the generated nanostructures. The present paper reviews the various approaches utilized in the field of arc plasma nanosynthesis in general and in the authors' laboratories in particular. Simple plasma diagnostics and monitoring schemes have been used in conjunction with nano materials characterization tools to explore the possibility of controlling the size, shape, yield and phase composition of the arc generated nanostructures through plasma control. Case studies related to synthesis of AlN, Al2O3, TiO2, ZrO2, ZnO), magnetic (e.g. {gamma}-Fe2O3, Fe3O4) and single elemental materials (e.g. carbon nanotubes) are presented.

  11. Unique variable polarity plasma arc welding for space shuttle

    NASA Technical Reports Server (NTRS)

    Schwinghamer, R. J.

    1985-01-01

    Since the introduction of the Plasma Arc Torch in 1955 and subsequent to the work at Boeing in the 1960's, significant improvements crucial to success have been made in the Variable Polarity Plasma Arc (VPPA) Process at the Marshall Space Flight Center. Several very important advantages to this process are given, and the genesis of PA welding, the genesis of VPPA welding, special equiment requirements, weld property development, results with other aluminum alloys, and the eventual successful VPPA transition to production operations are discussed.

  12. The 26th IEEE international conference on plasma science

    SciTech Connect

    1999-07-01

    Some of the sessions covered by this conference are: Basic Processes in Fully and Partially Ionized Plasmas; Slow Wave Devices; Laser-Produced Plasma; Non-Equilibrium Plasma Processing; Space Plasmas and Partially Ionized Gases; Microwave Plasmas; Inertial Confinement Fusion; Plasma Diagnostics; Computational Plasma Physics; Microwave Systems; Laser Produced Plasmas and Dense Plasma Focus; Intense Electron and Ion Beams; Fast Wave Devices; Spherical Configurations and Ball Lightning; Thermal Plasma Chemistry and Processing and Environmental Issues in Plasma Science; Plasma, Ion, and Electron Sources; Fast Wave Devices and Intense Beams; Fast Z-pinches and X-ray Lasers; Plasma Opening Switches; Plasma for Lighting; Intense Beams; Vacuum Microwaves; Magnetic Fusion Energy; and Plasma Thrusters and Arcs. Separate abstracts were prepared for some of the papers in this volume.

  13. Predicting ion charge state distributions of vacuum arc plasmas

    SciTech Connect

    Anders, A.; Schulke, T.

    1996-04-01

    Multiply charged ions are present in vacuum arc plasmas. The ions are produced at cathode spots, and their charge state distributions (CSDs) depend on the cathode material but only little on the arc current or other parameters as long as the current is relatively low and the anode is not actively involved in the plasma production. There are experimental data of ion CSDs available in the literature for 50 different cathode materials. The CSDs can be calculated based on the assumption that thermodynamic equilibrium is valid in the vicinity of the cathode spot, and the equilibrium CSDs `freeze` at a certain distance from the cathode spot (transition to a non-equilibrium plasma). Plasma temperatures and densities at the `freezing points` have been calculated, and, based on the existence of characteristic groups of elements in the Periodic Table, predictions of CSDs can be made for metallic elements which have not yet been used as cathode materials.

  14. Plasma arc welding repair of space flight hardware

    NASA Technical Reports Server (NTRS)

    Hoffman, David S.

    1993-01-01

    A technique to weld repair the main combustion chamber of Space Shuttle Main Engines has been developed. The technique uses the plasma arc welding process and active cooling to seal cracks and pinholes in the hot-gas wall of the main combustion chamber liner. The liner hot-gas wall is made of NARloy-Z, a copper alloy previously thought to be unweldable using conventional arc welding processes. The process must provide extensive heat input to melt the high conductivity NARloy-Z while protecting the delicate structure of the surrounding material. The higher energy density of the plasma arc process provides the necessary heat input while active water cooling protects the surrounding structure. The welding process is precisely controlled using a computerized robotic welding system.

  15. Plasma arc welding repair of space flight hardware

    NASA Technical Reports Server (NTRS)

    Hoffman, David S.

    1993-01-01

    Repair and refurbishment of flight and test hardware can extend the useful life of very expensive components. A technique to weld repair the main combustion chamber of space shuttle main engines has been developed. The technique uses the plasma arc welding process and active cooling to seal cracks and pinholes in the hot-gas wall of the main combustion chamber liner. The liner hot-gas wall is made of NARloyZ, a copper alloy previously thought to be unweldable using conventional arc welding processes. The process must provide extensive heat input to melt the high conductivity NARloyZ while protecting the delicate structure of the surrounding material. The higher energy density of the plasma arc process provides the necessary heat input while active water cooling protects the surrounding structure. The welding process is precisely controlled using a computerized robotic welding system.

  16. Electromagnetic radiation generated by arcing in low density plasma

    NASA Technical Reports Server (NTRS)

    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.

  17. Plasma Arc Welding: How it Works

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur

    2004-01-01

    The physical principles of PAW from basic arcs to keyholing to variable polarity are outlined. A very brief account of the physics of PAW with an eye to the needs of a welder is presented. Understanding is usually (but not always) superior to handbooks and is required (unless dumb luck intervenes) for innovation. And, in any case, all welders by nature desire to know. A bit of history of the rise and fall of the Variable Polarity (VP) PA process in fabrication of the Space Shuttle External Tank is included.

  18. Pulse thermal processing of functional materials using directed plasma arc

    DOEpatents

    Ott, Ronald D.; Blue, Craig A.; Dudney, Nancy J.; Harper, David C.

    2007-05-22

    A method of thermally processing a material includes exposing the material to at least one pulse of infrared light emitted from a directed plasma arc to thermally process the material, the pulse having a duration of no more than 10 s.

  19. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    SciTech Connect

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  20. Supersonic Argon Flow In An Arc Plasma Source

    SciTech Connect

    Izrar, B.; Dudeck, M.; Andre, P.; Elchinger, M. F.; Aubreton, J.

    2006-01-15

    The plasma properties inside a D.C. arc-jet operating with argon is analysed by means of a continuum description taking into account non equilibrium ionization processes and dissipative effects. The relaxation of the different physical processes inside the nozzle and the evolution of the Mach number are aanalysed.

  1. Plasma-Arc Torch For Welding Ducts In Place

    NASA Technical Reports Server (NTRS)

    Gangl, Kenneth J.; Bayless, Ernest; Looney, Alan

    1991-01-01

    Plasma-arc-welding torch redesigned, more suitable for applications in which moved in circular or other orbits about stationary cylindrical workpieces. Preserves elements of original design critical to performance and endurance, but modifies other elements to decrease overall size of torch. Electrode collet and collet nut installed and removed through hole in top; makes installation and removal easier.

  2. Spacelab Life Sciences-2 ARC payload - An overview

    NASA Technical Reports Server (NTRS)

    Savage, P. D., Jr.; Dalton, B.; Hogan, R.; Leon, H.

    1988-01-01

    The effects of microgravity on the anatomy and physiology of rodent and primate systems will be investigated on the Spacelab Life Sciences 2 (SLS-2) mission. Here, the payload being developed at NASA Ames Research Center (ARC) is described and illustrated with drawings. The ARC payload will build upon the success of previous missions. Experiments includes asssessment of rodent cardiovascular and vestibular system responses, primate thermoregulation and metabolic responses.

  3. An interchangeable-cathode vacuum arc plasma source

    SciTech Connect

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

    2010-01-15

    A simplified vacuum arc design [based on metal vapor vacuum arc (MeVVA) concepts] is employed as a plasma source for a study of a {sup 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{sup 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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. PMID:27587176

  6. Plasma Heating and Flow in an Auroral Arc

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Chandler, M. O.; Pollock, C. J.; Reasoner, D. L.; Arnoldy, R. L.; Austin, B.; Kintner, P. M.; Bonnell, J.

    1996-01-01

    We report direct observations of the three-dimensional velocity distribution of selected topside ionospheric ion species in an auroral context between 500 and 550 km altitude. We find heating transverse to the local magnetic field in the core plasma, with significant heating of 0(+), He(+), and H(+), as well as tail heating events that occur independently of the core heating. The 0(+) velocity distribution departs from bi-Maxwellian, at one point exhibiting an apparent ring-like shape. However, these observations are shown to be aliased within the auroral arc by temporal variations that arc not well-resolved by the core plasma instrument. The dc electric field measurements reveal superthermal plasma drifts that are consistent with passage of the payload through a series of vortex structures or a larger scale circularly polarized hydromagnetic wave structure within the auroral arc. The dc electric field also shows that impulsive solitary structures, with a frequency spectrum in the ion cyclotron frequency range, occur in close correlation with the tail heating events. The drift and core heating observations lend support to the idea that core ion heating is driven at low altitudes by rapid convective motions imposed by the magnetosphere. Plasma wave emissions at ion frequencies and parallel heating of the low-energy electron plasma are observed in conjunction with this auroral form; however, the conditions are much more complex than those typically invoked in previous theoretical treatments of superthermal frictional heating. The observed ion heating within the arc clearly exceeds that expected from frictional heating for the light ion species H(+) and He(+), and the core distributions also contain hot transverse tails, indicating an anomalous transverse heat source.

  7. Plasma arc welding torch having means for vortexing plasma gas exiting the welding torch

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    A plasma arc welding torch is described wherein a plasma gas is directed through the body of the welding torch and out of the body across the tip of the welding electrode disposed at the forward end of the body. The plasma gas is provided with a vortexing motion prior to exiting the body by a vortex motion imparting member which is mounted in an orifice housing member and carried in the forward portion of the torch body. The orifice housing member is provided with an orifice of an predetermined diameter through which the electric arc and the plasma gas exits.

  8. A magnetically controlled arc for plasma torch incineration

    SciTech Connect

    Peterson, P.Y.; Mayo, R.M.; Bourham, M.A.; Corzine, R.K.; Hart, D.; Messimore, J.

    1996-12-31

    With the ever increasing problems of chemically hazardous and radioactive waste produced from federal, commercial, medical, academic, and nuclear utility sources, a safe means of waste elimination or disposal is desired. Plasma torches represent an electrical arc technology that possesses certain advantages in radioactive and hazardous waste incineration. A plasma torch provides an extremely high-temperature ionized gas (up to 1--2eV) that can be used to incinerate (and possibly vitrify) solid waste. What`s more, a plasma incinerator can be used to achieve high volume reduction ratios, possibly to 1/100 of the original waste volume, and can be used to eliminate chemical and biological hazardous waste. Further the technology is readily scalable so that a torch can be designed to operate at a power range from 30--50kW for a compact size incinerator to power level of 2 MW or greater for high throughput commercial incinerators. Several technology limiting problems, however, arise in the use of high temperature plasma torches. Present plasma incineration devices suffer from poor electrode (cathode) survivability. The authors discuss in this paper, recent developments in applying external magnetization to plasma torches in order to enhance the electrode performance through arc distribution.

  9. Physics Of Variable-Polarity Plasma Arc Welding

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.; Nunes, Arthur C., Jr.

    1990-01-01

    Report describes experimental study of some of the physical and chemical effects that occur during variable-polarity plasma arc (VPPA) keyhole welding of 2219 aluminum alloy. Comprised three major programs: (1) determination of effects of chemical additions (i.e., impurities) on structure and shape of bead and keyhole; (2) determination of flow in regions surrounding keyhole; (3) development of analog used easily to study flow in keyhole region.

  10. Gas Tungsten Arc Welding and Plasma Arc Cutting. Teacher Edition [and] Student Edition [and] Student Workbook. Second Edition.

    ERIC Educational Resources Information Center

    Harper, Eddie; Knapp, John

    This packet of instructional materials for a gas tungsten arc welding (GTAW) and plasma arc cutting course is comprised of a teacher edition, student edition, and student workbook. The teacher edition consists of introductory pages and teacher pages. Introductory pages include training and competency profile, state duty/task crosswalk,…

  11. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    SciTech Connect

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-04-15

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  12. Heat sink effects in variable polarity plasma arc welding

    NASA Technical Reports Server (NTRS)

    Abdelmessih, Amanie N.

    1991-01-01

    The Space Shuttle External Tank is fabricated by the variable polarity plasma arc (VPPA) welding process. In VPPA welding, a noble gas, usually argon, is directed through an arc to emerge from the torch as a hot plasma jet. This jet is surrounded by a shielding gas, usually helium, to protect the weld from contamination with air. The high velocity, hot plasma jet completely penetrates the workpiece (resembling a line heat source) when operated in the 'keyhole' mode. The metal melts on touching the side of the jet, as the torch travels in the perpendicular direction to the direction of the jet, and melted metal moves around the plasma jet in the keyhole forming a puddle which solidifies behind the jet. Heat sink effects are observed when there are irregularities in the workpiece configuration, especially, if these irregularities are close to the weld bead. These heat sinks affect the geometry of the weld bead, i.e., in extreme cases they could cause defects such as incomplete fusion. Also, different fixtures seem to have varying heat sink effects. The objective of this research is to study the effect of irregularities in workpiece configuration and fixture differences (heat sink effects) on the weld bead geometry with the ultimate objective to compensate for the heat sink effects and achieve a perfect weld. Experiments were performed on different workpiece geometries and compared to approximate models.

  13. Degradation of tetrafluoroethane using three-phase gliding arc plasma

    NASA Astrophysics Data System (ADS)

    Pacheco, J.; García, M.; Pacheco, M.; Valdivia, R.; Rivera, C.; Garduño, M.

    2012-06-01

    The use of many chlorofluorocarbons (CFC's) has negatively impacted the ozone layer. The Montreal Protocol was implemented, as a temporary solution for this problem by replacing CFC's by hydrofluorocarbons (HFC's). These kinds of gases have the propriety to be free of chlorine. However, in a next future, the Montreal Protocol also considers the replacement of HFC's because they have a high global warming potential when they enter in contact with the atmosphere. One of the methods to remove those compounds is the gliding arc plasma because it presents some advantages. The inlet system works near the atmospheric pressure and has a transition region from plasma at thermodynamic local partial equilibrium to non-thermal plasma; allowing high gas and electronic temperatures. Results present a promissory possibility to be scaled and to give an industrial service.

  14. Arc Inception Mechanism on a Solar Array Immersed in a Low-Density Plasma

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    In this report, results are presented of an experimental and theoretical study of arc phenomena and snapover for two samples of solar arrays immersed in argon plasma. The effects of arcing and snapover are investigated. I-V curves are measured, and arc and snapover inception voltages and arc rates are determined within the wide range of plasma parameters. A considerable increase in arc rate due to absorption of molecules from atmospheric air has been confirmed. It is shown that increasing gas pressure causes increasing ion current collection and, consequently, arc rate even though the effect of conditioning also takes place. Arc sites have been determined by employing a video-camera. It is confirmed that keeping sample under high vacuum for a long time results in shifting arc threshold voltage well below -300 V. The results obtained seem to be important for the understanding of arc inception mechanism.

  15. Effects of current on droplet generation and arc plasma in gas metal arc welding

    NASA Astrophysics Data System (ADS)

    Hu, J.; Tsai, H. L.

    2006-09-01

    In gas metal arc welding (GMAW), a technology using pulsed currents has been employed to achieve the one-droplet-per-pulse (ODPP) metal transfer mode with the advantages of low average currents, a stable and controllable droplet generation, and reduced spatter. In this paper, a comprehensive model was developed to study the effects of different current profiles on the droplet formation, plasma generation, metal transfer, and weld pool dynamics in GMAW. Five types of welding currents were studied, including two constant currents and three wave form currents. In each type, the transient temperature and velocity distributions of the arc plasma and the molten metal, and the shapes of the droplet and the weld pool were calculated. The results showed that a higher current generates smaller droplets, higher droplet frequency, and higher electromagnetic force that becomes the dominant factor detaching the droplet from the electrode tip. The model has demonstrated that a stable ODPP metal transfer mode can be achieved by choosing a current with proper wave form for given welding conditions.

  16. Outreach Activities for Plasma Science

    NASA Astrophysics Data System (ADS)

    Haynes, M.; Bannan, K.; Delooper, J.; Eastman, T.; Sweet, P.; Smith, T.

    1997-11-01

    The need for communication beyond experts from subfields of scientific inquiry has been long identified. In response to this need, new outreach activities for plasma science have begun to take shape and grow. One example of this increase in activity is the formation of the Coalition for Plasma Science. The focus of the Coalition's efforts is to enhance the understanding and support for plasma science in the scientific community, the education community, business and the general public. One of the Coalition's first activities was to coordinate the assembly of an eight panel exhibit entitled "Plasmas: Science and Technology for the 21st Century". The formation of the Coalition and the display will be described and some possible future activities will be outlined.

  17. Surface hardening of cutting elements agricultural machinery vibro arc plasma

    NASA Astrophysics Data System (ADS)

    Sharifullin, S. N.; Adigamov, N. R.; Adigamov, N. N.; Solovev, R. Y.; Arakcheeva, K. S.

    2016-01-01

    At present, the state technical policy aimed at the modernization of worn equipment, including agriculture, based on the use of high-performance technology called nanotechnology. By upgrading worn-out equipment meant restoring it with the achievement of the above parameters passport. The existing traditional technologies are not suitable for the repair of worn-out equipment modernization. This is especially true of imported equipment. Out here alone - is the use of high-performance technologies. In this paper, we consider the use of vibro arc plasma for surface hardening of cutting elements of agricultural machinery.

  18. Platelet-cooled plasma arc torch. Final report

    SciTech Connect

    1995-10-01

    In this 12-month program sponsored by the DOE Morgantown Energy Technology Center, Aerojet designed, fabricated, and tested six platelet cooled electrodes for a Retech 75T (90 MW) plasma arc torch capable of processing mixed radioactive waste. Two of the electrodes with gas injection through the electrode wall demonstrated between eight and forty times the life of conventional water cooled electrodes. If a similar life increase can be produced in a 1 Mw size electrode, then electrodes possessing thousands, rather than hundreds, of hours of life will be available to DOE for potential application to mixed radioactive waste processing.

  19. Superalloy material test in a plasma arc tunnel

    NASA Technical Reports Server (NTRS)

    Land, D. W.

    1972-01-01

    Seven superalloy models were tested in a plasma arc tunnel at the peak heating condition existing on the space shuttle orbiter's lower surface during a low cross-range entry. The models were 3 x 3 in. flat surfaces, nominally 0.01 to 0.02 in. thick, and were held in a water-cooled wedge holder at a 60 deg angle of attack. Five test models were recycled 25 times for 10 min periods (two were recycled 50 times) in a Mach 4.6 test stream, with the model's leading edge temperature maintained at 2200 F (2000 F in one case).

  20. Film synthesis on powders by cathodic arc plasma deposition

    SciTech Connect

    Anders, A.; Anders, S.; Brown, I.G.; Ivanov, I.C.

    1995-04-01

    Cathodic arc plasma deposition was used to coat Al{sub 2}O{sub 3} powder (mesh size 60) with platinum. The power particles were moved during deposition using a mechanical system operating at a resonance frequency of 20 Hz. Scanning electron microscopy and Auger electron microscopy show that all particles are completely coated with a platinum film having a thickness of about 100 nm. The actual deposition time was only 20 s, thus the deposition rate was very high (5 nm/s).

  1. A unified 3D model for an interaction mechanism of the plasma arc, weld pool and keyhole in plasma arc welding

    NASA Astrophysics Data System (ADS)

    Jian, Xiaoxia; Wu, ChuanSong; Zhang, Guokai; Chen, Ji

    2015-11-01

    A 3D model is developed to perform numerical investigation on the coupled interaction mechanism of the plasma arc, weld pool and keyhole in plasma arc welding. By considering the traveling of the plasma arc along the welding direction, unified governing equations are solved in the whole domain including the torch, plasma arc, keyhole, weld pool and workpiece, which involves different physical mechanisms in different zones. The local thermodynamic equilibrium-diffusion approximation is used to treat the interface between the plasma arc and weld pool, and the volume-of-fluid method is used to track the evolution of the keyhole wall. The interaction effects between the plasma arc, keyhole and weld pool as well as the heat, mass and pressure transport phenomena in the whole welding domain are quantitatively simulated. It is found that when the torch is moving along the joint line, the axis of the keyhole channel tilts backward, and the envelope of molten metal surrounding the keyhole wall inside the weld pool is unsymmetrical relative to the keyhole channel. The plasma arc welding tests are conducted, and the predicted keyhole dimensions and the fusion zone shape are in agreement with the experimentally measured results.

  2. Structure of propagating arc in a magneto-hydrodynamic rail plasma actuator

    NASA Astrophysics Data System (ADS)

    Gray, Miles D.; Choi, Young-Joon; Sirohi, Jayant; Raja, Laxminarayan L.

    2016-01-01

    The spatio-temporal evolution of a magnetically driven arc in a rail plasma flow actuator has been characterized with high-speed imaging, electrical measurements, and spectroscopy. The arc draws a peak current of ~1 kA. High-speed framing cameras were used to observe the complex arc propagation phenomenon. In particular, the anode and cathode roots were observed to have different modes of transit, which resulted in distinct types of electrode degradation on the anode and cathode surfaces. Observations of the arc electrical properties and induced magnetic fields are used to explain the transit mechanism of the arc. Emission spectroscopy revealed the arc temperature and species composition as a function of transit distance of the arc. The results obtained offer significant insights into the electromagnetic properties of the arc-rail system as well as arc-surface interaction phenomena in a propagating arc.

  3. Plasma arc melting of titanium-tantalum alloys

    SciTech Connect

    Dunn, P.; Patterson, R.A.; Haun, R.

    1994-08-01

    Los Alamos has several applications for high temperature, oxidation and liquid-metal corrosion resistant materials. Further, materials property constraints are dictated by a requirement to maintain low density; e.g., less than the density of stainless steel. Liquid metal compatibility and density requirements have driven the research toward the Ti-Ta system with an upper bound of 60 wt% Ta-40 wt% Ti. Initial melting of these materials was performed in a small button arc melter with several hundred grams of material; however, ingot quantities were soon needed. But, refractory metal alloys whose constituents possess very dissimilar densities, melting temperatures and vapor pressures pose significant difficulty and require specialized melting practices. The Ti-Ta alloys fall into this category with the density of tantalum 16.5 g/cc and that of titanium 4.5 g/cc. Melting is further complicated by the high melting point of Ta(3020 C) and the relatively low boiling point of Ti(3287 C). Previous electron beam melting experience with these materials resulted, in extensive vaporization of the titanium and poor chemical homogeneity. Vacuum arc remelting(VAR) was considered as a melting candidate and discarded due to density and vapor pressure issues associated with electron beam. Plasma arc melting offered the ability to supply a cover gas to deal with vapor pressure issues as well as solidification control to help with macrosegregation in the melt and has successfully produced high quality ingots of the Ti-Ta alloys.

  4. The variable polarity plasma arc welding process: Characteristics and performance

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Zhu, G. J.

    1991-01-01

    Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. The power distribution was analyzed for an argon plasma gas flow constituting the fluid in the VPPA Welding Process. The major heat loss at the torch nozzle is convective heat transfer; in the space between the outlet of the nozzle and the workpiece; radiative heat transfer; and in the keyhole in the workpiece, convective heat transfer. The power absorbed at the workpiece produces the molten puddle that solidifies into the weld bead. Crown and root widths, and crown and root heights of the weld bead are predicted. The basis is provided for an algorithm for automatic control of VPPA welding machine parameters to obtain desired weld bead dimensions.

  5. Deflection of a hyperbaric plasma arc in a transverse magnetic field

    SciTech Connect

    Richardson, I.M.

    1993-12-31

    Results are presented concerning the influence of operating parameters on the susceptibility of the plasma arc to deflection by an externally generated transverse magnetic field. Arc deflection susceptibility is found to increase rapidly with rising ambient pressure and is significantly greater for the free burning TIG arc compared with the weakly constricted (soft) plasma arc. In agreement with previously published work, it has been shown that for small amplitude deflections the arc column behaves in a manner analogous to a solid body. However, above a critical field strength the structure of the column undergoes a significant change characterized by a rapid deterioration in stability; mechanisms for this behavior are discussed.

  6. Variational analysis of railgun plasma-arc-armature for acceleration of solid hydrogen pellets for fusion reactor refueling

    SciTech Connect

    Choe, W.H.; Kim, K.

    1988-12-01

    This paper discusses fueling magnetically confined plasmas using a railgun plasma-arc-armature. The topics covered are: the Plasma model; Variational analysis; Current density in the plasma arc and arc voltage; and Magnetic field and the net railgun force. 5 refs., 5 figs. (LSP)

  7. Ionization effect on arc plasma's optical diagnosis by the measurement of the refractive index.

    PubMed

    Chen, Yun-yun; Zhang, Cheng-yi; Gu, Fang; Wang, Qing-hua; Li, Zhen-hua

    2012-06-01

    The effect of arc plasma ionization on its temperature diagnosis by the measurement of the refractive index is discussed. The refractive index of arc plasma in two conditions is compared: 1) only the first ionization is considered and 2) both the first and second ionizations are considered. In order to facilitate plasma temperature reconstruction, two corresponding refractive index models are deduced. For the sake of making this study universal, both the monatomic and dual-atomic molecule arc plasmas are chosen as typical examples for theoretical deduction and analysis. A condition, which can be adopted to estimate whether the second ionization should be considered in temperature reconstruction, is proposed. Finally, an argon arc plasma is chosen as an example for experiment, and the experimental results match well with the theoretical analysis. This study is crucial to arc plasma's optical diagnosis, which is based on the measurement of the refractive index. PMID:22695575

  8. Effects of Anode Arc Root Fluctuation on Coating Quality During Plasma Spraying

    NASA Astrophysics Data System (ADS)

    An, Lian-Tong; Gao, Yang; Sun, Chengqi

    2011-06-01

    To obtain a coating of high quality, a new type of plasma torch was designed and constructed to increase the stability of the plasma arc and reduce the air entrainment into the plasma jet. The torch, called bi-anode torch, generates an elongated arc with comparatively high arc voltage and low arc fluctuation. Spraying experiments were carried out to compare the quality of coatings deposited by a conventional torch and a bi-anode torch. Alumina coatings and tungsten carbide coatings were prepared to appraise the heating of the sprayed particles in the plasma jets and the entrainment of the surrounding air into the plasma jets, respectively. The results show that anode arc root fluctuation has only a small effect on the melting rate of alumina particles. On the other hand, reduced air entrainment into the plasma jet of the bi-anode torch will drastically reduce the decarbonization of tungsten carbide coatings.

  9. Filtered pulsed carbon cathodic arc: Plasma and amorphous carbon properties

    NASA Astrophysics Data System (ADS)

    Liu, Dongping; Benstetter, Günther; Lodermeier, Edgar; Zhang, Jialiang; Liu, Yanhong; Vancea, Johann

    2004-06-01

    The carbon plasma ion energies produced by the filtered pulsed cathodic arc discharge method were measured as a function of filter inductance. The energy determination is based on the electro-optical time-of-flight method. The average ion energies of the pulsed ion beams were found to depend upon the rise time and duration of pulsed arc currents, which suggests that a gain of ion kinetic energy mainly arises from the electric plasma field from the ambipolar expansion of both electrons and ions, and an electron drag force because of the high expansion velocity of the electrons. The tetrahedral amorphous carbon (ta-C) films with a sp3 fraction of ˜70% were deposited on silicon substrates at the average ion energies of >6 eV in the highly ionized plasmas. The ta-C films were found to be covered with a few graphitelike atomic layers. The surface properties of ultrathin carbon films, such as nanoscale friction coefficients, surface layer thickness, and silicon contents were strongly dependent on the ion energies. The growth of amorphous carbon films was explained in terms of the thermal spike migration of surface carbon atoms. In terms of this model, the thermal spike provides the energy required to release surface atoms from their metastable positions and leads to the formation of the sp3 bonded carbon on a sp3 bonded matrix. The experimental results indicate that the low-energy (<3 eV) carbon ions have insufficient energies to cause the rearrangement reaction within the film and they form graphitelike structures at film surface.

  10. Approaches to rid cathodic arc plasmas of macro- andnanoparticles: A review

    SciTech Connect

    Anders, Andre

    1999-06-01

    A major obstacle for the broad application of cathodic arc plasma deposition is the presence of micro- and nanoparticles in the plasma, also often referred to as 'macroparticles'. This paper reviews the formation of macroparticles at cathode spots, their interaction with the arc plasma and substrate, and macroparticle separation and removal from the plasma by various filtering methods. Nineteen variants of filters are discussed, including Aksenov's classic 90{sup o}-duct filter, filters of open architecture, and the concept of stroboscopic filtering.

  11. Improved Back-Side Purge-Gas Chambers For Plasma Arc Welding

    NASA Technical Reports Server (NTRS)

    Ezell, Kenneth G.; Mcgee, William F.; Rybicki, Daniel J.

    1995-01-01

    Improved chambers for inert-gas purging of back sides of workpieces during plasma arc welding in keyhole (full-penetration) mode based on concept of directing flows of inert gases toward, and concentrating them on, hot weld zones. Tapered chamber concentrates flow of inert gas on plasma arc plume and surrounding metal.

  12. Method and device for reducing overpenetration at the start of plasma arc welds

    DOEpatents

    Sanders, John M.; Lehmann, John M.; Ryan, Patrick M.

    1998-01-01

    A shim for improving plasma arc weld quality has ends tapered at about 25.degree. and notches at each end roughly centered over the corner between the tapered ends and main body of the shim. The improved shim allows lower starting plasma arc heat input and reduces the occurrence of sagging, or overpenetration, of the weld.

  13. ARC: A compact, high-field, disassemblable fusion nuclear science facility and demonstration power plant

    NASA Astrophysics Data System (ADS)

    Sorbom, Brandon; Ball, Justin; Palmer, Timothy; Mangiarotti, Franco; Sierchio, Jennifer; Bonoli, Paul; Kasten, Cale; Sutherland, Derek; Barnard, Harold; Haakonsen, Christian; Goh, Jon; Sung, Choongki; Whyte, Dennis

    2014-10-01

    The Affordable, Robust, Compact (ARC) reactor conceptual design aims to reduce the size, cost, and complexity of a combined Fusion Nuclear Science Facility (FNSF) and demonstration fusion pilot power plant. ARC is a 270 MWe tokamak reactor with a major radius of 3.3 m, a minor radius of 1.1 m, and an on-axis magnetic field of 9.2 T. ARC has Rare Earth Barium Copper Oxide (REBCO) superconducting toroidal field coils with joints to allow disassembly, allowing for removal and replacement of the vacuum vessel as a single component. Inboard-launched current drive of 25 MW LHRF power and 13.6 MW ICRF power is used to provide a robust, steady state core plasma far from disruptive limits. ARC uses an all-liquid blanket, consisting of low pressure, slowly flowing Fluorine Lithium Beryllium (FLiBe) molten salt. The liquid blanket acts as a working fluid, coolant, and tritium breeder, and minimizes the solid material that can become activated. The large temperature range over which FLiBe is liquid permits blanket operation at 800-900 K with single phase fluid cooling and allows use of a high-efficiency Brayton cycle for electricity production in the secondary coolant loop.

  14. Glass Strengthening via High-Intensity Plasma-Arc Heating

    SciTech Connect

    Wereszczak, Andrew A; Harper, David C; Duty, Chad E; Patel, P

    2010-01-01

    The use of a high-intensity plasma-arc lamp was used to irradiate the surface of soda-lime silicate glass tiles to determine if an increase in strength could be achieved. The lamp had a power density of 3500 W/cm2, a processing area of 1 cm x 10 cm, irradiated near-infrared heating at a wavelength between 0.2 1.4 m, and was controlled to unidirectionally sweep across 50-mm-square tiles at a constant speed of 8 mm/s. Ring-on-ring (RoR) equibiaxial flexure and 4 pt uni-directional flexure testings of entire tiles were used to measure and compare failure stress distributions of treated and untreated glass. Even with non-optimized processing conditions, RoR failure stress increased by approximately 25% and the 4 pt bend failure stress increased by approximately 65%. Strengthening was due to a fire-polishing-like mechanism. The arc-lamp heat-treatment caused the location of the strength-limiting flaws in the 4-pt-bend tiles to change; namely, failure initiation occurred on the gage section surface for the treated glass whereas it occurred at a gage section edge for the untreated. Arc-lamp heat-treatment is attractive not only because it provides strengthening, but because it can (non-contact) process large amounts of glass quickly and inexpensively, and is a process that either a glass manufacturer or end-user can readily employ.

  15. Plasma plume characterization of a vacuum arc thruster

    NASA Astrophysics Data System (ADS)

    Sekerak, Michael James

    A Vacuum Arc Thruster (VAT) is a thruster that uses the plasma created in a vacuum arc, an electrical discharge in a vacuum that creates high velocity and highly ionized plasmas, as the propellant without additional acceleration. A VAT would be a small and inexpensive low thrust ion thruster, ideal for small satellites and formation flying spacecraft. The purpose of this thesis was to quantitatively and qualitatively examine the VAT plasma plume to determine operating characteristics and limitations. A VAT with a titanium cathode was operated in two regimes: (A) single ˜100mus pulse, discharge current JD=510A, and (B) multiple ˜1500mus pulses at f=40.8Hz, JD=14A. The cathode was 3.18mm diameter Ti rod, surrounded by a 0.80mm thick alumina insulator, set in a molybdenum anode. Three Configurations were tested: Cfg1 (Regime A, cathode recessed 3.00mm from anode), Cfg2 (Regime A, cathode and anode flush), Cfg3 (Regime B, cathode recessed 3.00mm). A semi-empirical model was derived for VAT performance based on the MHD equation of motion using data for ion velocity, ion charge state distribution, ion current fraction (F), and ion current density distribution (ICDD). Additional performance parameters were a2, the peak ion current density angular offset from the cathode normal, and a3, the width of the ion current distribution. Measurements were taken at 162 points on a plane in the plasma plume using a custom faraday probe, and the ICDD empirical form was determined to be a Gaussian. The discharge voltage (VD) and F were Cfg1: VD=25.5V, F=0.025-0.035; Cfg2: VD=40.7V, F=0.08-0.10; Cfg3: VD=14.9V, F=0.006-0.021. For Cfg1, a2 started 15° off-axis while a2˜0 for Cfg2 and 3. In Cfg1, a 3=0.7-0.6, and in Cfg2 a3=1.0-1.1, so the recessed cathode focused the plasma more. However, F is more important for VAT performance because upper and lower bounds for thrust, specific impulse, thrust-to-power, and efficiency were calculated and Cfg2 had the highest performance. High

  16. Method of operating a centrifugal plasma arc furnace

    DOEpatents

    Kujawa, Stephan T.; Battleson, Daniel M.; Rademacher, Jr., Edward L.; Cashell, Patrick V.; Filius, Krag D.; Flannery, Philip A.; Whitworth, Clarence G.

    1998-01-01

    A centrifugal plasma arc furnace is used to vitrify contaminated soils and other waste materials. An assessment of the characteristics of the waste is performed prior to introducing the waste into the furnace. Based on the assessment, a predetermined amount of iron is added to each batch of waste. The waste is melted in an oxidizing atmosphere into a slag. The added iron is oxidized into Fe.sub.3 O.sub.4. Time of exposure to oxygen is controlled so that the iron does not oxidize into Fe.sub.2 O.sub.3. Slag in the furnace remains relatively non-viscous and consequently it pours out of the furnace readily. Cooled and solidified slag produced by the furnace is very resistant to groundwater leaching. The slag can be safely buried in the earth without fear of contaminating groundwater.

  17. Method of operating a centrifugal plasma arc furnace

    DOEpatents

    Kujawa, S.T.; Battleson, D.M.; Rademacher, E.L. Jr.; Cashell, P.V.; Filius, K.D.; Flannery, P.A.; Whitworth, C.G.

    1998-03-24

    A centrifugal plasma arc furnace is used to vitrify contaminated soils and other waste materials. An assessment of the characteristics of the waste is performed prior to introducing the waste into the furnace. Based on the assessment, a predetermined amount of iron is added to each batch of waste. The waste is melted in an oxidizing atmosphere into a slag. The added iron is oxidized into Fe{sub 3}O{sub 4}. Time of exposure to oxygen is controlled so that the iron does not oxidize into Fe{sub 2}O{sub 3}. Slag in the furnace remains relatively non-viscous and consequently it pours out of the furnace readily. Cooled and solidified slag produced by the furnace is very resistant to groundwater leaching. The slag can be safely buried in the earth without fear of contaminating groundwater. 3 figs.

  18. Heat flow in variable polarity plasma arc welds

    NASA Technical Reports Server (NTRS)

    Abdelmessih, Amanie N.

    1992-01-01

    The space shuttle external tank and the space station Freedom are fabricated by the variable polarity plasma arc (VPPA) welding. Heat sink effects (taper) are observed when there are irregularities in the work-piece configuration especially if these irregularities are close to the weld bead. These heat sinks affect the geometry of the weld bead, and in extreme cases they could cause defects such as incomplete fusion. Also, different fixtures seem to have varying heat sink effects. The objective of the previous, present, and consecutive research studies is to investigate the effect of irregularities in the work-piece configuration and fixture differences on the weld bead geometry with the ultimate objective to compensate automatically for the heat sink effects and achieve a perfect weld.

  19. Heat flow in variable polarity plasma arc welds

    NASA Astrophysics Data System (ADS)

    Abdelmessih, Amanie N.

    1992-12-01

    The space shuttle external tank and the space station Freedom are fabricated by the variable polarity plasma arc (VPPA) welding. Heat sink effects (taper) are observed when there are irregularities in the work-piece configuration especially if these irregularities are close to the weld bead. These heat sinks affect the geometry of the weld bead, and in extreme cases they could cause defects such as incomplete fusion. Also, different fixtures seem to have varying heat sink effects. The objective of the previous, present, and consecutive research studies is to investigate the effect of irregularities in the work-piece configuration and fixture differences on the weld bead geometry with the ultimate objective to compensate automatically for the heat sink effects and achieve a perfect weld.

  20. Emission spectra analysis of arc plasma for synthesis of carbon nanostructures in various magnetic conditions

    SciTech Connect

    Li Jian; Kundrapu, Madhusudhan; Shashurin, Alexey; Keidar, Michael

    2012-07-15

    Arc discharge supported by the erosion of anode materials is one of the most practical and efficient methods to synthesize various high-quality carbon nanostructures. By introducing a non-uniform magnetic field in arc plasmas, high-purity single-walled carbon nanotubes (SWCNT) and large-scale graphene flakes can be obtained in a single step. In this paper, ultraviolet-visible emission spectra of arc in different spots under various magnetic conditions are analyzed to provide an in situ investigation for transformation processes of evaporated species and growth of carbon nanostructures in arc. Based on the arc spectra of carbon diatomic Swan bands, vibrational temperature in arc is determined. The vibrational temperature in arc center was measured around 6950 K, which is in good agreement with our simulation results. Experimental and simulation results suggest that SWCNT are formed in the arc periphery region. Transmission electronic microscope and Raman spectroscope are also employed to characterize the properties of carbon nanostructures.

  1. Characterization of an atmospheric double arc argon-nitrogen plasma source

    SciTech Connect

    Tu, X.; Cheron, B. G.; Yan, J. H.; Yu, L.; Cen, K. F.

    2008-05-15

    In the framework of studies devoted to hazardous waste destruction, an original dc double anode plasma torch has been designed and tested, which produces an elongated, weak fluctuation and reproducible plasma jet at atmospheric pressure. The arc instabilities and dynamic behavior of the double arc argon-nitrogen plasma jet are investigated through the oscillations of electrical signals by combined means of fast Fourier transform and Wigner distribution. In our experiment, the restrike mode is identified as the typical fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra and Wigner distributions exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which reveals that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the undulation of the power supply and both arc roots motion on the anode channels. In addition, the microscopic properties of the plasma jet inside and outside the arc chamber are investigated by means of optical emission spectroscopy, which yields excitation, electronic, rotational, and vibrational temperatures, as well as the electron number density. The results allow us to examine the validity criteria of a local thermodynamic equilibrium (LTE) state in the plasma arc. The measured electron densities are in good agreement with those calculated from the LTE model, which indicates that the atmospheric double arc argon-nitrogen plasma in the core region is close to the LTE state under our experimental conditions.

  2. Arc-Cathode Coupling in the Modeling of a Conventional DC Plasma Spray Torch

    NASA Astrophysics Data System (ADS)

    Alaya, M.; Chazelas, C.; Mariaux, G.; Vardelle, A.

    2015-01-01

    The plasma torch is the basis of the plasma spray process and understanding of the electric arc dynamics within the plasma torch is necessary for better control of torch and process instabilities. Numerical simulation is a useful tool for investigating the effect of the torch geometry and operating parameters on the electric arc characteristics provided that the model of arc dynamics is reliable and the boundary conditions of the computational domain are well founded. However, such a model should also address the intricate transient and 3D interactions between the electrically conducting fluid and electromagnetic, thermal, and acoustics phenomena. Especially, the description of the electrode regions where the electric arc connects with solid material is an important part of a realistic model of the plasma torch operation as the properties of electric arcs at atmospheric pressure depend not only on the arc plasma medium, but also on the electrodes. This paper describes the 3D and time-dependent numerical simulation of a plasma arc and is focused on the cathode boundary conditions. This model was used to investigate the differences in arc characteristics when the cathode is included into the numerical domain and coupled with the arc. The magnetic and thermal coupling between the cathode and arc made it possible to get rid of the current density boundary condition at the cathode tip that is delicate to predetermine. It also allowed a better prediction of the cathode flow jet generated by the pumping action induced by the interaction of the self-magnetic field with the electric current and so it allowed a better description of the dynamics of arc. It should be a necessary step in the development of a fully predictive model of DC plasma torch operation.

  3. Simulation science for fusion plasmas

    NASA Astrophysics Data System (ADS)

    Sudo, S.; Škorić, M. M.; Watanabe, T.-H.; Todo, Y.; Ishizawa, A.; Miura, H.; Ishizaki, R.; Ito, A.; Ohtani, H.; Usami, S.; Nakamura, H.; Ito, Atsushi; Ishiguro, S.; Tomita, Y.; Takayama, A.; Sato, M.; Yamamoto, T.; Den, M.; Sakagami, H.; Horiuchi, R.; Okamura, S.; Nakajima, N.

    2008-10-01

    The world fusion effort has embarked into a new age with the construction of ITER in Cadarache, France, which will be the first magnetic confinement fusion plasma experiment dominated by the self-heating of fusion reactions. In order to operate and control burning plasmas and next generation demo fusion reactors, an advanced capability for comprehensive integrated computer simulations that are fully verified and validated against experimental data will be necessary. The ultimate goal is to predict reliably the behaviour of plasmas in toroidal magnetic confinement devices on all relevant scales, both in time and space. In addition to developing a sophisticated integrated simulation codes, directed advanced research in fusion physics, applied mathematics, computer science and software is envisaged. In this paper we review the basic strategy and main research efforts at the Department of Simulation Science of the National Institute for Fusion Science (NIFS)- which is the Inter University Institute and the coordinating Center of Excellence for academic fusion research in Japan. We overview a simulation research at NIFS, in particular relation to experiments in the Large Helical Device (LHD), the world's largest superconducting heliotron device, as a National Users' facility (see Motojima et al. [1]). Our main goal is understanding and systemizing the rich hierarchy of physical mechanisms in fusion plasmas, supported by exploring a basic science of complexity of plasma as a highly nonlinear, non-equilibrium, open system. The aim is to establish a simulation science as a new interdisciplinary field by fostering collaborative research in utilizing the large-scale supercomputer simulators. A concept of the hierarchy-renormalized simulation modelling will be invoked en route toward the LHD numerical test reactor.

  4. Simulation Science for Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Skoric, M. M.; Sudo, S.

    2008-07-01

    The world fusion effort has recently entered a new age with the construction of ITER in Cadarache, France, which will be the first magnetic confinement fusion plasma experiment dominated by the self-heating of fusion reactions. In order to operate and control burning plasmas and future demo fusion reactors, an advanced ability for comprehensive computer simulations that are fully verified and validated against experimental data will be necessary. The ultimate goal is to develop the capability to predict reliably the behavior of plasmas in toroidal magnetic confinement devices on all relevant time and space scales. In addition to developing a sophisticated integrated simulation codes, directed advanced research in fusion physics, applied mathematics and computer science is envisaged. In this talk we review the basic strategy and main research efforts at the Department of Simulation Science of the National Institute for Fusion Science (NIFS)- which is the Inter University Institute and the coordinating Center of Excellence for academic fusion research in Japan. We overview a simulation research at NIFS, in particular relation to experiments in the Large Helical Device (LHD), the world's largest superconducting heliotron device, as a National Users' facility (see Motojima et al. 2003). Our main goal is understanding and systemizing the rich hierarchy of physical mechanisms in fusion plasmas, supported by exploring a basic science of complexity of plasma as a highly nonlinear, non-equilibrium, open system. The aim is to establish a simulation science as a new interdisciplinary field by fostering collaborative research in utilizing the large-scale supercomputer simulators. A concept of the hierarchy-renormalized simulation modelling will be invoked en route toward the LHD numerical test reactor. Finally, a perspective role is given on the ITER Broad Approach program at Rokkasho Center, as an integrated part of ITER and Development of Fusion Energy Agreement.

  5. Multiple ionization of metal ions by ECR heating of electrons in vacuum arc plasmas

    NASA Astrophysics Data System (ADS)

    Vodopyanov, A. V.; Golubev, S. V.; Zorin, V. G.; Razin, S. V.; Vizir, A. V.; Nikolaev, A. G.; Oks, E. M.; Yushkov, G. Yu.

    2004-05-01

    A joint research and development effort has been initiated, whose ultimate goal is the enhancement of the mean ion charge states in vacuum arc metal plasmas by a combination of a vacuum arc discharge and electron cyclotron resonance (ECR) heating. Metal plasma was generated by a special vacuum arc mini-gun. Plasma was pumped by high frequency gyrotron-generated microwave radiation. The results have demonstrated substantial multiple ionization of metal ions. For a lead plasma, ECR heating increased the maximum attainable ion charge state from Pb2+ up to Pb6+. The confinement parameter was as high as ˜109 cm-3 s. Further increase of the ion charge states will be attained by increasing the vacuum arc plasma density and optimizing the ECR heating conditions.

  6. The nature of fluctuations in a double arc argon-nitrogen plasma jet

    SciTech Connect

    Tu Xin; Yan Jianhua; Yu Liang; Cen, Kefa; Cheron, Bruno

    2007-09-24

    The dynamic behavior of the double arc argon-nitrogen plasma jet is investigated by combined means of the fast Fourier transform, correlation function, and Wigner distribution. The restrike mode is identified as the fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which indicates that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the power supply undulation and both arc roots motion on the anode channels. It is further found that the double anode torch could inhibit and reduce the restrike phenomenon.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  8. Plasma drifts associated with a system of sun-aligned arcs in the polar cap

    SciTech Connect

    Mende, S.B.; Doolittle, J.H.; Robinson, R.M.; Vondrak, R.R.; Rich, F.J.

    1988-01-01

    A series of four sun-aligned arcs passed over Sondre Stromfjord, Greenland, on the night of the 17th and 18th of February, 1985. Observations of these arcs were made using the Sondrestrom incoherent scatter radar and an intensified all-sky imaging TV system that was operated at the radar site. The first of the four arcs crossed the Sondre Stromfjord meridian just before local midnight moving westward, and the other three arcs followed at approximately half-hour intervals. When we account for the earth's rotation, the arc drift in an inertial frame was eastward, or dusk to dawn. The half-hour interval between meridian crossings of the arcs implies that the mean spacing between the arcs was 180 km. A Defense Meteorological Satellite Program (DMSP) F6 satellite pass at 0110 UT revealed the presence of highly structured electron and ion precipitation throughout the polar cap. The DMSP visible imager detected a single, sun-aligned arc associated with the largest peak in precipitating electron flux. This arc was also observed at Thule, Greenland, with an intensified film camera. These observations suggest that at least one of the arcs that were observed at Sondre Stromfjord extended across a large part of the polar cap. The radar at Sondre Stromfjord measured electron density and ion drift velocities associated with the four arcs. The radar drift measurements were superimposed on the all-sky video images to determine the location of the measurements relative to the arcs. Plasma drifts outside the arcs were found to be both sunward and antisunward, while within the arcs the drifts were predominantly antisunward. The variability of the drifts in the direction parallel to the arcs indicates that the electric fields were highly structured even though the configuration and motion of the arcs were well behaved.

  9. The variable polarity plasma arc welding process: Its application to the Space Shuttle external tank

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Bayless, O. E., Jr.; Jones, C. S., III; Munafo, A. P.; Wilson, W. A.

    1983-01-01

    The technical history of the variable polarity plasma arc (VPPA) welding process being introduced as a partial replacement for the gas shielded tungsten arc process in assembly welding of the space shuttle external tank is described. Interim results of the weld strength qualification studies, and plans for further work on the implementation of the VPPA process are included.

  10. Life cycle cost analysis for the Plasma Arc Furnace

    SciTech Connect

    Barnes-Smith, P.

    1994-03-01

    This document is a draft version. The Mixed Waste Integrated Program requested that the Systems Analysis Group investigate the cost effectiveness of using the Plasma Arc Furnace (PAF) module in place of specified thermal and final forms treatment equipment in the baseline Mixed Waste Treatment Project (MWTP) study as performed by Bechtel Corporation, September 1992. The attached estimates are based on the process equipment and facilities cost data contained in the Bechtel study. The PAF process equipment and facilities cost data were developed using independent cost estimates for the equipment list provided by SAIC, Waste Management and Technology Division, in cooperation with the Pollution Prevention and Systems Analysis Group of the Oak Ridge National Laboratory, Chemical Technology Division. In order to develop the total life cycle cost estimate comparison for this study, it was necessary to use a common base for comparison. Although it was felt that the Bechtel MWTP study did not fully reflect the optimum size for the thermal and final forms treatment equipment, it was the best available data at the time.

  11. Effects of shielding gas compositions on arc plasma and metal transfer in gas metal arc welding

    SciTech Connect

    Rao, Z. H.; Liao, S. M.; Tsai, H. L.

    2010-02-15

    This article presents the effects of shielding gas compositions on the transient transport phenomena, including the distributions of temperature, flow velocity, current density, and electromagnetic force in the arc and the metal, and arc pressure in gas metal arc welding of mild steel at a constant current input. The shielding gas considered includes pure argon, 75% Ar, 50% Ar, and 25% Ar with the balance of helium. It is found that the shielding gas composition has significant influences on the arc characteristics; droplet formation, detachment, transfer, and impingement onto the workpiece; and weld pool dynamics and weld bead profile. As helium increases in the shielding gas, the droplet size increases but the droplet detachment frequency decreases. For helium-rich gases, the current converges at the workpiece with a 'ring' shape which produces non-Gaussian-like distributions of arc pressure and temperature along the workpiece surface. Detailed explanations to the physics of the very complex but interesting transport phenomena are given.

  12. Ultrathin ta-C films on heads depositied by twist-filteredcathodic arc carbon plasmas

    SciTech Connect

    Anders, Andre; Ryan, Francis W.

    2000-07-14

    It is known that filtered cathodic-arc-deposited ta-C films have outstanding properties even within the family of diamondlike materials. However, filtering of macroparticles is usually incomplete or accompanied by significant plasma losses. Ongoing research effort is directed towards the following goals: (1) complete elimination of macro- and nanoparticles from the vacuum arc plasma, (2) increase of plasma utilization in the cathodic-arc and macroparticle-filter system, (3) precise control and reproducibility of film deposition, and (4) synthesis of ultrathin films (< 5 nm) that meet requirements of the magnetic storage industry. The development of new filters, in particular the ''Twist Filter'', enables cathodic arc plasma deposition to synthesize ultrathin ta-C films of 3 nm on heads that pass corrosion and other relevant tests. We describe the Twist Filter system and report about recent ta-C tests results. In light of these results, even thinner films seem to be possible.

  13. A unified model of coupled arc plasma and weld pool for double electrodes TIG welding

    NASA Astrophysics Data System (ADS)

    Wang, Xinxin; Fan, Ding; Huang, Jiankang; Huang, Yong

    2014-07-01

    A three-dimensional model containing tungsten electrodes, arc plasma and a weld pool is presented for double electrodes tungsten inert gas welding. The model is validated by available experimental data. The distributions of temperature, velocity and pressure of the coupled arc plasma are investigated. The current density, heat flux and shear stress over the weld pool are highlighted. The weld pool dynamic is described by taking into account buoyance, Lorentz force, surface tension and plasma drag force. The turbulent effect in the weld pool is also considered. It is found that the temperature and velocity distributions of the coupled arc are not rotationally symmetrical. A similar property is also shown by the arc pressure, current density and heat flux at the anode surface. The surface tension gradient is much larger than the plasma drag force and dominates the convective pattern in the weld pool, thus determining the weld penetration. The anodic heat flux and plasma drag force, as well as the surface tension gradient over the weld pool, determine the weld shape and size. In addition, provided the welding current through one electrode increases and that through the other decreases, keeping the total current unchanged, the coupled arc behaviour and weld pool dynamic change significantly, while the weld shape and size show little change. The results demonstrate the necessity of a unified model in the study of the arc plasma and weld pool.

  14. Plasma arc welding Hp-9Ni-4Co-0.30C steel

    SciTech Connect

    Harwig, D.D.; Hunt, J.F.; Theus, G.J.

    1994-12-31

    The plasma arc welding process is used to fabricate the advanced solid rocket motor (ASRM) casing for the Space Shuttle. Plasma arc welding (PAW) was chosen because this process assures a full penetration root pass with the keyhole mode. The HP 9Ni-4Co-0.30C steel was chosen for the ASRM application because the material has excellent strength, toughness, and weldability. The minimum mechanical property requirements of the weldment are 190 ksi yield, 205 ksi ultimate, 8% elongation, 25% reduction in area and 90 ksi/in. fracture toughness. Therefore, a comprehensive development plan was performed to fully characterize plasma arc welding HP 9Ni-4Co-0.30 steel. The test technique systematically varied the essential plasma arc parameters: current, travel speed, plasma gas or wire feed speed while maintaining constant arc length and torch set-up conditions. This PWHT produced the best combination of strength, toughness, and acceptable residual stresses. Variations in land thickness, plasma gas flow rate, current, travel speed, and arc length were characterized by measuring weld bead shape geometry. The weld procedure was found to be tolerant to rather wide parameter variations.

  15. Spectroscopic characterization and imaging of laser- and unipolar arc-induced plasmas

    SciTech Connect

    Aussems, Damien U. B.; Nishijima, Daisuke; Brandt, Christian; Doerner, Russell P.; Cardozo, Niek J. Lopes

    2014-08-14

    Tungsten plasmas induced by unipolar arcs were investigated using optical emission spectroscopy and imaging, and compared with laser-induced tungsten plasmas. The unipolar arcs were initiated in the linear-plasma simulator PISCES-A at UCSD under fusion relevant conditions. The electron temperature and density of the unipolar arc plasmas were in the range 0.5–0.7 eV and 0.7–2.0 × 10{sup 20 }m{sup −3}, respectively, and increased with increasing negative bias voltage, but did not correlate with the surface temperature. In comparison, the electron temperature and density of the laser-induced plasmas were in the range 0.6–1.4 eV and 7 × 10{sup 19}–1 × 10{sup 22 }m{sup −3}, respectively.

  16. Relationship between wave-like auroral arcs and Pi2 pulsations in plasma sheet during substorms

    NASA Astrophysics Data System (ADS)

    Chang, T. F.; Cheng, C. Z.

    2014-12-01

    The observations of substorm onset phenomena in the magnetosphere and ionosphere are examined to investigate their correlation and to understand the substorm onset mechanism. In particular, we examine the Pi2 wave structure, propagation, frequency in the magnetosphere observed by the THEMIS satellites in the near-Earth plasma sheet and the structure and propagation of the substorm auroral onset arcs. The azimuthal mode number values of the wave-like substorm arcs are found to be in the range of ~ 100 - 260 and decrease with increasing geomagnetic latitude of the substorm auroral arc location. The wave-like arc brightness structures on the substorm auroral arcs tend to move azimuthally westward, but with a few exceptions of eastward movement, during tens of seconds prior to the substorm onset. The movement of the wave-like arc brightness structure is linearly correlated with the phase velocity of the Pi2 δBy pulsations in the near-Earth plasma sheet region. The result suggests that the Pi2 transverse δBy disturbances are related to the intensifying wave-like substorm onset arcs. One plausible explanation of the observations is the kinetic ballooning instability, which has high azimuthal mode number due to the ion gyro-radius effect and finite parallel electric field that accelerates electrons into the ionosphere to produce the wave-like arc structure.

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

    SciTech Connect

    Zhang, H.-S.; Komvopoulos, K.

    2008-07-15

    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 (sp{sup 3}) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.

  18. Applicability of moiré deflection tomography for diagnosing arc plasmas.

    PubMed

    Chen, Yun-yun; Song, Yang; He, An-zhi; Li, Zhen-hua

    2009-01-20

    The argon arc plasma whose central temperature, 1.90x10(4) K, is used as a practical example for an experiment to research the applicability of moiré deflection tomography in arc plasma flow-field diagnosis. The experimental result indicates that moiré deflection of the measured argon arc plasma is very small, even smaller than that of a common flame with the maximal temperature of nearly 1.80x10(3) K. The refractive-index gradient in moiré deflection tomography mainly contributes to the temperature gradient in essence when the probe wavelength and pressure are certain in plasma diagnosis. The applicable temperature ranges of moiré deflection tomography in the argon arc plasma diagnosis are given with the probe wavelength 532 nm at 1 atm in certain measuring error requirements. In a word, the applicable temperature range of moiré deflection tomography for arc plasma diagnosis is intimately related to the probe wavelength and the practical measuring requirements. PMID:19151817

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

    PubMed

    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. PMID:18681714

  20. The plasma wave environment of an auroral arc. II - ULF waves on an auroral arc boundary

    NASA Technical Reports Server (NTRS)

    Gelpi, C. G.; Bering, E. A.

    1984-01-01

    On March 9, 1978, a sounding rocket launched from Poker Flat, Alaska, at 2200 LT, made a four-component measurement of a 0.5 Hz hydromagnetic wave as the payload crossed the poleward boundary of a quiet homogeneous auroral arc. An energy flux of about 10 to the -6th W/sq m was observed propagating upward with a left-handed polarization within the arc, and a flux 6 times greater was observed propagating downward with a right-handed polarization on the arc boundary. The waves were identified as shear mode Alfven waves. Various models for the source of the free energy are discussed with the conclusion that the most likely production mechanism was either the electromagnetic or electrostatic Kelvin-Helmholtz instability.

  1. Multiple Ionization Of Metal Ions By ECR Heating Of Electrons In Vacuum Arc Plasmas

    NASA Astrophysics Data System (ADS)

    Vodopyanov, A. V.; Golubev, S. V.; Mansfeld, D. A.; Nikolaev, A. G.; Oks, E. M.; Razin, S. V.; Savkin, K. P.

    2005-03-01

    A joint research and development effort has been initiated, whose ultimate goal is the enhancement the mean ion charge states in vacuum arc metal plasmas by a combination of a vacuum arc discharge and an electron cyclotron resonance (ECR) heating. Metal plasma was generated by a special vacuum arc mini-gun and injected into mirror magnetic trap. Plasma was pumped by high frequency gyrotron-generated microwave radiation (frequency 37.5 GHz, max power 100 kW, pulse duration 1.5 ms). Using of powerful microwaves makes it possible to sustain sufficient temperature of electrons needed for multiple ionizations at high plasma density (more then 1013 cm-3). Parameter of multiple ionization efficiency Neτi, where Ne is plasma density, τi, is ion lifetime, in such a case could reach rather high value ˜109 cm-3-s. In our situation τi = Ltrap/Vi, where Ltrap is trap length, Vi is plasma gun flow velocity. The results have demonstrated substantial multiple ionization of metal ions (including metals with high melting temperature). For a metal (lead, platinum) plasma, ECR heating shifted the average ion charge up to 5+. Further increase of the ion charge states will be attained by increasing the vacuum arc plasma density and optimizing the ECR heating conditions.

  2. Optical Analysis Of The Vacuum Arc Plasma Generated In Cup-Shape Contacts

    SciTech Connect

    Pavelescu, G.; Gherendi, F.; Pavelescu, D.; Dumitrescu, G.; Anghelita, P.

    2007-04-23

    In this paper are presented the results of the optical analysis on the rotating arc plasma, generated in the vacuum low voltage circuit breaker with cup-shaped contacts. An adequate experimental setup was used for single shot time and spatial resolved spectroscopy in order to analyze the evolution of the vacuum arc plasma. Different current interruption situations are correlated with plasma spectral diagnosis. The study is aimed to contribute to a better understanding of the complex phenomena that take place in the interruption process of high currents that appears in the short-circuit regime of electrical networks.

  3. Hypervelocity impact induced arcing and Kapton pyrolization in a plasma environment

    NASA Astrophysics Data System (ADS)

    Christie, Robert J.; Best, Steve R.; Myhre, Craig A.

    1994-03-01

    Tests were performed on the Space Station Freedom (SSF) solar array flat conductor circuit (FCC) to determine if hypervelocity impacts could induce pyrolization of Kapton and/or cross-conductor arcing. A sample piece of FCC was placed in a plasma environment and biased to +200 V relative to the plasma potential. The FCC was then impacted with particles in the 100 micron size range with hypervelocities of about 7 km/s. These tests were unable to induce Kapton pyrolization, cross-conductor arcing, or any other plasma interaction.

  4. Vacuum arc plasma thrusters with inductive energy storage driver

    NASA Technical Reports Server (NTRS)

    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.

  5. Free Fall Plasma-Arc Reactor for Synthesis of Carbon Nanotubes in Microgravity

    NASA Technical Reports Server (NTRS)

    Alford, J. M.; Mason, G. R.; Feinkema, D. A.

    2006-01-01

    High temperatures inside the plasma of a carbon arc generate strong buoyancy driven convection which has an effect on the growth and morphology of the single-walled carbon nanotubes (SWNTs). To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was designed and developed to synthesize SWNTs in a microgravity environment substantially free from buoyant convective flows. An arc reactor was operated in the 2.2- and 5.18-second drop towers at the NASA Glenn Research Center. The apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 amps at 30 volts to the arc for the duration of a 5-second drop. However, the principal result is that no dramatic difference in sample yield or composition was noted between normal gravity, 2.2-and 5-second long microgravity runs.

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

    SciTech Connect

    Keidar, Michael

    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.

  7. Plasma irregularities associated with a morning discrete auroral arc - Radar interferometer observations and theory

    NASA Technical Reports Server (NTRS)

    Providakes, J.; Farley, D. T.; Swartz, W. E.; Riggin, D.

    1985-01-01

    A description is given of E region auroral plasma irregularities associated with an intense auroral morning arc observed over Fort Churchill by radar. The observations are compared with data from an all-sky camera (ASC) operated at Fort Churchill by the National Research Council of Canada. The particular event described was chosen because of the rapid variation in structure and motion of the arc as it traveled through the radar beam. The horizontal vector electron drift velocity and electric field along the poleward boundary of the morning discrete auroral arc was successfully measured with a radar interferometer. This instrument provided information concerning the temporal and spatial structure of the electrostatic plasma turbulence in the arc. The observations are described.

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

    PubMed

    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. PMID:26406468

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

    PubMed Central

    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. PMID:26406468

  10. Morphology of zirconia particles exposed to D.C. arc plasma jet

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, Isidor

    1987-01-01

    Zirconia particles were sprayed into water with an arc plasma gun in order to determine the effect of various gun operating parameters on their morphology. The collected particles were examined by XRD and SEM techniques. A correlation was established between the content of spherical (molten) particles and the operating parameters by visual inspection and regression analysis. It was determined that the composition of the arc gas and the power input were the predominant parameters that affected the melting of zirconia particles.

  11. Improvements of the welding performance of plasma arcs by a superimposed fibre laser beam

    NASA Astrophysics Data System (ADS)

    Mahrle, Achim; Rose, Sascha; Schnick, Michael; Pinder, Thomas; Beyer, Eckhard; Füssel, Uwe

    2012-03-01

    Details and results of experimental investigations of a laser-supported plasma arc welding process are presented. The particular feature of the realized experimental set-up is the coaxial arrangement of a single-mode fibre laser beam through a hollow tungsten electrode in combination with a modified plasma welding torch. The analysis of the welding capabilities of the combined laser-arc source comprises high-speed video recordings of the arc shape and size, corresponding simultaneous measurements of the arc voltage as well as an evaluation of the resultant weld seam geometries. Results of welding trials on different types of steel and aluminum alloys are discussed. The corresponding investigations reveal that a fibre laser beam with a wavelength of 1.07 microns can have a crucial impact on the arc and welding characteristics for both categories of materials even at very low laser power output levels. Beneficial effects are especially observed with high welding speeds. In that particular case the arc root and therefore arc column can be substantially stabilized and guided by the laser-induced hot spot.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Ultraviolet imaging of the anode attachment in transferred-arc plasma cutting

    SciTech Connect

    Bemis, B.L.; Settles, G.S.

    1999-02-01

    The anode phenomena occurring at the location of current transfer from the plasma jet to the plate affects cut quality in plasma cutting of mild steel plate. To understand these phenomena, an ultraviolet imaging technique was used to visualize the anode attachment spot under various cutting conditions. This technique has provided a unique view and fostered a better understanding of the plasma-arc cutting process.

  14. Modelling on dynamics properties of a stationary argon cascaded arc plasma flows

    SciTech Connect

    Wei, G. D.; Qi, X.; Yang, L.

    2014-03-15

    The gas dynamics properties of a stationary arc plasma flows are studied through the numerical simulations. A two dimensional axis-symmetric turbulent magneto-hydrodynamic plasma model is developed with the commercial code ANSYS FLUENT. The reliable κ-ε model is used to account for turbulence. In this paper, the plasma is assumed to be a fluid following Navier–Stokes equations, respecting local thermodynamic equilibrium, and described by only one temperature. Distributions of the pressure, velocity, temperature, density, and electric potential inside of thus cascaded arc are obtained for an arc current density of 10{sup 6} A/m{sup 2}. The pressure inside the arc varies from 10{sup 5} Pa to 100 Pa. The temperature at the arc axis can reach as high as 13 600 K. The electric potential drops uniformly along the axis with a magnitude of 160 V. In addition, distributions of the sonic velocity and Mach number are shown to describe supersonic behavior of thus cascaded arc, which have a good agreement with the analytical formula.

  15. Modelling on dynamics properties of a stationary argon cascaded arc plasma flows

    NASA Astrophysics Data System (ADS)

    Wei, G. D.; Qi, X.; Yang, L.

    2014-03-01

    The gas dynamics properties of a stationary arc plasma flows are studied through the numerical simulations. A two dimensional axis-symmetric turbulent magneto-hydrodynamic plasma model is developed with the commercial code ANSYS FLUENT. The reliable κ-ɛ model is used to account for turbulence. In this paper, the plasma is assumed to be a fluid following Navier-Stokes equations, respecting local thermodynamic equilibrium, and described by only one temperature. Distributions of the pressure, velocity, temperature, density, and electric potential inside of thus cascaded arc are obtained for an arc current density of 106 A/m2. The pressure inside the arc varies from 105 Pa to 100 Pa. The temperature at the arc axis can reach as high as 13 600 K. The electric potential drops uniformly along the axis with a magnitude of 160 V. In addition, distributions of the sonic velocity and Mach number are shown to describe supersonic behavior of thus cascaded arc, which have a good agreement with the analytical formula.

  16. Remote automatic control scheme for plasma arc cutting of contaminated waste

    SciTech Connect

    Dudar, A.M.; Ward, C.R.; Kriikku, E.M.

    1993-10-01

    The Robotics Development Group at the Savannah River Technology Center has developed and implemented a scheme to perform automatic cutting of metallic contaminated waste. The scheme employs a plasma arc cutter in conjunction with a laser ranging sensor attached to a robotic manipulator called the Telerobot. A software algorithm using proportional control is then used to perturb the robot`s trajectory in such a way as to regulate the plasma arc standoff and the robot`s speed in order to achieve automatic plasma arc cuts. The scheme has been successfully tested on simulated waste materials and the results have been very favorable. This report details the development and testing of the scheme.

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

    PubMed

    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. PMID:24593607

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

    NASA Astrophysics Data System (ADS)

    Han, Wen; Yuan, Zhao; He, Junjia

    2016-07-01

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

  19. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    PubMed

    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. PMID:18315170

  20. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma

    SciTech Connect

    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.

    2008-02-15

    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 {mu}s, 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.

  1. Synthesis of Single Wall Carbon Nanotubes by Plasma Arc: Role of Plasma Parameters

    NASA Technical Reports Server (NTRS)

    Farhart, Samir; Scott, Carl D.

    2000-01-01

    Single wall carbon nanotubes (SWNT) are porous objects on the molecular scale and have a low density, which gives them potential applications as adsorbent for molecular hydrogen. Their H2 absorption capacity published in the literature varies from 4 to 10% by mass according to the purity of the materials and storage conditions. Optimization of production methods of SWNTs should permit improving these new materials for storage of hydrogen. In this article, we show the potential of using SWNTs in hydrogen storage. In particular, we pose problems associated with synthesis, purification, and opening up of the nanotubes. We present an electric arc process currently used at laboratory scale to produce single wall carbon nanotubes. We discuss, in particular, operating conditions that permit growth of nanotubes and some plasma parameters that assure control of the material. Analysis of the process is carried out with the aid of local measurements of temperature and scanning and transmission electron microscopy of the materials.

  2. Investigation on oblique shock wave control by arc discharge plasma in supersonic airflow

    SciTech Connect

    Wang Jian; Li Yinghong; Xing Fei

    2009-10-01

    Wedge oblique shock wave control by arc discharge plasma in supersonic airflow was investigated theoretically, experimentally, and numerically in this paper. Using thermal choking model, the change in oblique shock wave was deduced, which refer that the start point of shock wave shifts upstream, the shock wave angle decreases, and its intensity weakens. Then the theoretical results were validated experimentally in a Mach 2.2 wind tunnel. On the test conditions of arc discharge power of approx1 kW and arc plasma temperature of approx3000 K, schlieren photography and gas pressure measurements indicated that the start point of shock wave shifted upstream of approx4 mm, the shock wave angle decreased 8.6%, and its intensity weakened 8.8%. The deduced theoretical results match the test results qualitatively, so thermal mechanism and thermal choking model are rational to explain the problem of oblique shock wave control by arc discharge plasma. Finally, numerical simulation was developed. Based on thermal mechanism, the arc discharge plasma was simplified as a thermal source term that added to the Navier-Stokes equations. The simulation results of the change in oblique shock wave were consistent with the test results, so the thermal mechanism indeed dominates the oblique shock wave control process.

  3. Effects of the bleaching procedures on enamel micro-hardness: Plasma Arc and diode laser comparison

    PubMed Central

    Nematianaraki, Saeid; Naghibi, Nasim; Kalhori, Katayoun AM; Junior, Aldo Brugnera

    2015-01-01

    Background and aims: One of the major side effects of vital bleaching is the reduction of enamel micro-hardness. The purpose of this study was to evaluate the influence of two different bleaching systems, Plasma Arc and GaAlAs laser, on the enamel micro-hardness. Materials and methods: 15 freshly extracted human third molars were sectioned to prepare 30 enamel blocks (5×5 mm). These samples were then randomly divided into 2 groups of 15 each (n=15): a plasma arc bleaching group (: 350–700 nm) + 35% Hydrogen Peroxide whitening gel and a laser bleaching group (GaAlAs laser, λ: 810 nm, P: 10 W, CW, Special Tip) + 35% Hydrogen Peroxide whitening gel. Samples were subjected to the Vickers micro-hardness test (VHN) at a load of 50 g for 15s before and after treatment. Data were statistically analyzed by a Mann-Whitney test (p≤0.05). Results: In the GaAlAs laser group, the enamel micro-hardness was 618.2 before and was reduced to 544.6 after bleaching procedures. In the plasma arc group, the enamel micro-hardness was 644.8 before and 498.9 after bleaching. Although both techniques significantly reduced VHN, plasma arc bleaching resulted in a 22.62% reduction in VHN for enamel micro-hardness, whereas an 11.89% reduction in VHN was observed for laser bleaching; this difference is statistically significant (p<0.001). Conclusion: Both bleaching techniques reduced enamel micro-hardness, although the reduction is much less significant with the GaAlAs laser than with the plasma arc. Therefore GaAlAs laser bleaching has fewer harmful effects than plasma arc in respect to enamel micro-hardness reduction. PMID:26557731

  4. Spectroscopy peculiarities of thermal plasma of electric arc discharge between electrodes with Zn admixtures

    NASA Astrophysics Data System (ADS)

    Semenyshyn, R. V.; Veklich, A. N.; Babich, I. L.; Boretskij, V. F.

    2014-10-01

    Plasma of the free burning electric arc between Ag-SnO2-ZnO composite electrodes as well as brass electrodes were investigated. The plasma temperature distributions were obtained by Boltzmann plot method involving Cu I, Ag I or Zn I spectral line emissions. The electron density distributions were obtained from the width and from absolute intensity of spectral lines. The laser absorption spectroscopy was used for measurement of copper atom concentration in plasma. Plasma equilibrium composition was calculated using two independent groups of experimental values (temperature and copper atom concentration, temperature and electron density). It was found that plasma of the free burning electric arc between brass electrodes is in local thermodynamical equilibrium. The experimental verification of the spectroscopic data of Zn I spectral lines was carried out.

  5. Use of vacuum arc plasma guns for a metal puff Z-pinch system

    SciTech Connect

    Rousskikh, A. G.; Zhigalin, A. S.; Oreshkin, V. I.; Chaikovsky, S. A.; Labetskaya, N. A.; Baksht, R. B.

    2011-09-15

    The performance of a metal puff Z-pinch system has been studied experimentally. In this type of system, the initial cylindrical shell 4 cm in diameter was produced by ten plasma guns. Each gun initiates a vacuum arc operating between magnesium electrodes. The net current of the guns was 80 kA. The arc-produced plasma shell was compressed by using a 450-kA, 450-ns driver, and as a result, a plasma column 0.3 cm in diameter was formed. The electron temperature of the plasma reached 400 eV at an average ion concentration of 1.85 {center_dot} 10{sup 18} cm{sup -3}. The power of the Mg K-line radiation emitted by the plasma for 15-30 ns was 300 MW/cm.

  6. Arc plasma generator of atomic driver for steady-state negative ion source.

    PubMed

    Ivanov, A A; Belchenko, Yu I; Davydenko, V I; Ivanov, I A; Kolmogorov, V V; Listopad, A A; Mishagin, V V; Putvinsky, S V; Shulzhenko, G I; Smirnov, A

    2014-02-01

    The paper reviews the results of development of steady-state arc-discharge plasma generator with directly heated LaB6 cathode. This arc-discharge plasma generator produces a plasma jet which is to be converted into an atomic one after recombination on a metallic plate. The plate is electrically biased relative to the plasma in order to control the atom energies. Such an intensive jet of hydrogen atoms can be used in negative ion sources for effective production of negative ions on a cesiated surface of plasma grid. All elements of the plasma generator have an augmented water cooling to operate in long pulse mode or in steady state. The thermo-mechanical stresses and deformations of the most critical elements of the plasma generator were determined by simulations. Magnetic field inside the discharge chamber was optimized to reduce the local power loads. The first tests of the steady-state arc plasma generator prototype have performed in long-pulse mode. PMID:24593569

  7. Arc plasma generator of atomic driver for steady-state negative ion source

    SciTech Connect

    Ivanov, A. A.; Belchenko, Yu. I.; Davydenko, V. I.; Ivanov, I. A.; Kolmogorov, V. V.; Listopad, A. A. Mishagin, V. V.; Shulzhenko, G. I.; Putvinsky, S. V.; Smirnov, A.

    2014-02-15

    The paper reviews the results of development of steady-state arc-discharge plasma generator with directly heated LaB{sub 6} cathode. This arc-discharge plasma generator produces a plasma jet which is to be converted into an atomic one after recombination on a metallic plate. The plate is electrically biased relative to the plasma in order to control the atom energies. Such an intensive jet of hydrogen atoms can be used in negative ion sources for effective production of negative ions on a cesiated surface of plasma grid. All elements of the plasma generator have an augmented water cooling to operate in long pulse mode or in steady state. The thermo-mechanical stresses and deformations of the most critical elements of the plasma generator were determined by simulations. Magnetic field inside the discharge chamber was optimized to reduce the local power loads. The first tests of the steady-state arc plasma generator prototype have performed in long-pulse mode.

  8. Magnetic Dipole Inflation with Cascaded ARC and Applications to Mini-Magnetospheric Plasma Propulsion

    NASA Technical Reports Server (NTRS)

    Giersch, L.; Winglee, R.; Slough, J.; Ziemba, T.; Euripides, P.

    2003-01-01

    Mini-Magnetospheric Plasma Propulsion (M2P2) seeks to create a plasma-inflated magnetic bubble capable of intercepting significant thrust from the solar wind for the purposes of high speed, high efficiency spacecraft propulsion. Previous laboratory experiments into the M2P2 concept have primarily used helicon plasma sources to inflate the dipole magnetic field. The work presented here uses an alternative plasma source, the cascaded arc, in a geometry similar to that used in previous helicon experiments. Time resolved measurements of the equatorial plasma density have been conducted and the results are discussed. The equatorial plasma density transitions from an initially asymmetric configuration early in the shot to a quasisymmetric configuration during plasma production, and then returns to an asymmetric configuration when the source is shut off. The exact reasons for these changes in configuration are unknown, but convection of the loaded flux tube is suspected. The diffusion time was found to be an order of magnitude longer than the Bohm diffusion time for the period of time after the plasma source was shut off. The data collected indicate the plasma has an electron temperature of approximately 11 eV, an order of magnitude hotter than plasmas generated by cascaded arcs operating under different conditions. In addition, indirect evidence suggests that the plasma has a beta of order unity in the source region.

  9. Pulsar Scintillation Arcs reveal filaments in the Interstellar Plasma

    NASA Astrophysics Data System (ADS)

    Rickett, Barney; Stinebring, Dan; Coles, Bill; Jian-Jian, Gao

    2011-08-01

    Both forward and reverse Scintillation Arcs are seen in observations of several pulsars. We study the arcs, which are seen in the 2-D Fourier transform of the dynamic spectrum, from PSRs B0834+06 and B1737+13. In both cases we conclude that the underlying scattered image is highly extended along an axis and also highly modulated along that axis. The corresponding spatial structure in the ionized interstellar medium must be bundles of spaghetti-like filaments--highly anisotropic turbulence (on scales of 1000-10000 km) which is also very intermittent on scales of an AU. We speculate on their possible origin as remnant turbulence from long past supernovae.

  10. Parametric Study of Plasma Torch Operation Using a MHD Model Coupling the Arc and Electrodes

    NASA Astrophysics Data System (ADS)

    Alaya, M.; Chazelas, C.; Vardelle, A.

    2016-01-01

    Coupling of the electromagnetic and heat transfer phenomena in a non-transferred arc plasma torch is generally based on a current density profile and a temperature imposed on the cathode surface. However, it is not possible to observe the current density profile experimentally and so the computations are grounded on an estimation of current distribution at cathode tip. To eliminate this boundary condition and be able to predict the arc dynamics in the plasma torch, the cathode was included in the computational domain, the arc current was imposed on the rear surface of the cathode, and the electromagnetism and energy conservation equations for the fluid and the electrode were coupled and solved. The solution of this system of equations was implemented in a CFD computer code to model various plasma torch operating conditions. The model predictions for various arc currents were consistent and indicated that such a model could be applied with confidence to plasma torches of different geometries, such as cascaded-anode plasma torches.

  11. Electron beam, laser beam and plasma arc welding studies

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

  12. Vacuum-arc plasma-beam motion in curved magnetic fields

    NASA Astrophysics Data System (ADS)

    Gidalevich, Evgeny; Goldsmith, Samuel; Boxman, Raymond

    1994-05-01

    A theoretical model is presented for transport of vacuum arc generated metal vapor plasma through a magnetized quarter-tours duct used for filtering out macroparticles in order to deposit high quality thin films. The model utilizes a two fluid approximation which takes into account collisions among the plasma particles. It is found that centrifugal forces must lead to a charge separation generated field, that determines plasma drift in the centrifugal force direction to the duct wall and give rise to ion loss. Another cause for plasma is the plasma pressure gradient. The plasma output flux is an increasing function of the magnetic field strength. The plasma flux in the output plane is asymmetrically skewed to favor the outside half. A further asymmetry in the flux distribution in the direction of the torroidal axis of symmetry is introduced if ions of different charge states are present in the plasma.

  13. Optimization of the output and efficiency of a high power cascaded arc hydrogen plasma source

    SciTech Connect

    Vijvers, W. A. J.; Gils, C. A. J. van; Goedheer, W. J.; Meiden, H. J. van der; Veremiyenko, V. P.; Westerhout, J.; Lopes Cardozo, N. J.; Rooij, G. J. van; Schram, D. C.

    2008-09-15

    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 hydrogen gas flow rate. Measurements of the pressure in the arc channel show that the flow is well described by Poiseuille flow and that the effective heavy particle temperature is approximately 0.8 eV. Interpretation of the measured I-V data in terms of a one-parameter model shows that the plasma production is proportional to the input power, to the square root of the hydrogen flow rate, and is independent of the channel diameter. The observed scaling shows that the dominant power loss mechanism inside the arc channel is one that scales with the effective volume of the plasma in the discharge channel. Measurements on the plasma output with Thomson scattering confirm the linear dependence of the plasma production on the input power. Extrapolation of these results shows that (without a magnetic field) an improvement in the plasma production by a factor of 10 over where it was in van Rooij et al. [Appl. Phys. Lett. 90, 121501 (2007)] should be possible.

  14. Arcing of negatively biased solar cells in a plasma environment. I - Experimental observations

    NASA Technical Reports Server (NTRS)

    Upschulte, B. L.; Marinelli, W. J.; Weyl, G.; Carleton, K. L.; Aifer, E.

    1992-01-01

    A variety of experiments have been performed which identify key factors contributing to the arcing of negatively biased high voltage solar cells operating in a low earth orbit plasma environment. These efforts have led to a reduction of greater than a factor of 100 in the arc frequency of a single cells following proper remeditation procedures. Experiments naturally led to and focused on the adhesive/encapsulating that is used to bond the protective cover slip to the solar cell. An image-intensified CCD camera system recorded UV emission from arc events which occurred exclusively along the interfacial edge between the cover slip and the solar cell. Microscopic inspection of this interfacial region showed a bead of encapsulant along this entire edge. Elimination of this encapsulant bead reduced the arc frequency by two orders of magnitude.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  16. ARC - A source of multisensor satellite data for polar science

    NASA Technical Reports Server (NTRS)

    Van Woert, Michael L.; Whritner, Robert H.; Waliser, Duane E.; Bromwich, David H.; Comiso, J. C.

    1992-01-01

    The NSF's Antarctic Research Center (ARC) has been established to furnish real-time polar-orbiting satellite data in support of Antarctic field studies, as well as to maintain a multisensor satellite data (MSD) archive for retrospective data analysis. An account is presently given of the ways in which the complementary nature of an MSD set can deepen understanding of Antarctic physical processes. An active microwave SAR with 30-m resolution and a radar altimeter will be added to the ARC resources later in this decade, as will the Earth Observing System.

  17. Volt-ampere characteristics of a nitrogen DC plasma arc with anode melting

    NASA Astrophysics Data System (ADS)

    Zhao, Peng; Ni, Guo-Hua; Meng, Yue-Dong; Nagatsu, Masaaki

    2013-06-01

    The characteristics of a nitrogen arc using a graphite cathode and a melting anode in a pilot-scale plasma furnace are investigated. The voltage is examined as a function of current and apparent plasma length. The voltage increases non-linearly with the increase of apparent plasma length, with the current fixed. The experimental data so obtained are compared with the predictions of the Bowman model for the electric arc, and with numerical simulations as well. The level of agreement between the experimental data at the melting anode and the numerical predictions confirms the suitability of the proposed the Bowman model. These characteristics are relevant to the engineering design and evaluation of a DC plasma furnace and reactor for the treatment of hazardous fly ash waste.

  18. The Coalition for Plasma Science: Bringing Plasmas to the Public

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2003-10-01

    The Coalition for Plasma Science is a group of institutions, organizations, and companies that have joined forces to increase awareness and understanding of plasma science and its many applications and benefits for society. The CPS undertakes a range of activities to support this goal. Members include national laboratories, universities, industries, and individuals. The CPS maintains a web page (http://www.plasmacoalition.org), and has developed several types of plasma-related publications. The web page includes a compilation of evaluated plasma web sites. The evaluations were conducted by teachers and based on national teaching standards. The web site also contains copies of CPS publications including the brochure ''Plasmas are Everywhere.'' Thousands of these brochures are distributed each year, and a poster version is now available. Another publication is the ''About Plasmas'' series. Each of these two-page papers (which is written for a general audience) is about a specific plasma-related topic, such as lighting, fusion, space plasmas and plasma decontamination of biological hazards. Papers on other topics are under development. The CPS also organizes educational luncheon/seminars for Members of Congress and their staff. The most recent seminar was given by David Newman on January 28th of this year and was his ''state of the universe'' address. A second seminar is planned this year on the topic of semiconductor manufacturing. Activities under discussion include a topical science fair award for a project on plasmas and the development of a broad, history-based educational web site.

  19. Localized arc filament plasma actuators for noise mitigation and mixing enhancement

    NASA Technical Reports Server (NTRS)

    Samimy, Mohammad (Inventor); Adamovich, Igor (Inventor)

    2010-01-01

    A device for controlling fluid flow. The device includes an arc generator coupled to electrodes. The electrodes are placed adjacent a fluid flowpath such that upon being energized by the arc generator, an arc filament plasma adjacent the electrodes is formed. In turn, this plasma forms a localized high temperature, high pressure perturbation in the adjacent fluid flowpath. The perturbations can be arranged to produce vortices, such as streamwise vortices, in the flowing fluid to control mixing and noise in such flows. The electrodes can further be arranged within a conduit configured to contain the flowing fluid such that when energized in a particular frequency and sequence, can excite flow instabilities in the flowing fluid. The placement of the electrodes is such that they are unobtrusive relative to the fluid flowpath being controlled.

  20. Localized arc filament plasma actuators for noise mitigation and mixing enhancement

    NASA Technical Reports Server (NTRS)

    Samimy, Mohammad (Inventor); Adamovich, Igor (Inventor)

    2008-01-01

    A device for controlling fluid flow. The device includes an arc generator coupled to electrodes. The electrodes are placed adjacent a fluid flowpath such that upon being energized by the arc generator, an arc filament plasma adjacent the electrodes is formed. In turn, this plasma forms a localized high temperature, high pressure perturbation in the adjacent fluid flowpath. The perturbations can be arranged to produce vortices, such as streamwise vortices, in the flowing fluid to control mixing and noise in such flows. The electrodes can further be arranged within a conduit configured to contain the flowing fluid such that when energized in a particular frequency and sequence, can excite flow instabilities in the flowing fluid. The placement of the electrodes is such that they are unobtrusive relative to the fluid flowpath being controlled.

  1. The electric field structure of auroral arcs as determined from barium plasma injection experiments

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.

    1981-01-01

    Barium plasma injection experiments have revealed a number of features of electric fields in and near auroral forms extending from a few hundred to many thousands of km in altitude. There is evidence for V-type potential structures over some auroras, but not in others. For some auroral arcs, large E fields are found at ionospheric altitudes outside the arc but the E field inside the arc is near zero. In a few other auroras, most recently one investigated in an experiment conducted from Poker Flat on March 22, 1980, large, rapidly fluctuating E fields were detected by barium plasma near 600 km altitude. These E fields suggest that the motion of auroral rays can be an effect of low-altitude electric fields, or that V-type potential structures may be found at low altitudes.

  2. STACK TESTING OF THE MOBILE PLASMA ARC UNIT

    EPA Science Inventory

    A trial burn program involving a plasma pyrolysis system was conducted at the Royal Military College, Kingston, Ontario. The plasma pyrolysis unit was developed by Pyrolysis Systems, Inc. under contract to the New York State Department of Environmental Conservation (NYSDEC). HWER...

  3. Micro-scale Plasma Arc Gasification for Waste Treatment and Energy Production Project

    NASA Technical Reports Server (NTRS)

    Caraccio, Anne

    2015-01-01

    As NASA continues to develop technology for spaceflight beyond low earth orbit, we must develop the right systems for sustaining human life on a long duration or planetary mission. Plasma arc gasification (PAG) is an energy efficient mechanism of waste management for power generation and synthetic gas(syngas) production.

  4. Plasma Cutting and Carbon-Arc Cutting. Welding Module 8. Instructor's Guide.

    ERIC Educational Resources Information Center

    Missouri Univ., Columbia. Instructional Materials Lab.

    This guide is intended to assist vocational educators in teaching the two units of a module in operating plasma cutting and carbon-arc cutting equipment. The module is part of a welding curriculum that has been designed to be totally integrated with Missouri's Vocational Instruction Management System. The materials included in the module have been…

  5. The Variable Polarity Plasma Arc Welding Process: Its Application to the Space Shuttle External Tank

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Bayless, E. O., Jr.; Wilson, W. A.

    1984-01-01

    This report describes progress in the implementation of the Variable Polarity Plasma Arc Welding (VPPAW) process at the External Tank (ET) assembly facility. Design allowable data has been developed for thicknesses up to 1.00 in. More than 24,000 in. of welding on liquid oxygen and liquid hydrogen cylinders has been made without an internal defect.

  6. UAH mathematical model of the variable polarity plasma ARC welding system calculation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1994-01-01

    Significant advantages of Variable Polarity Plasma Arc (VPPA) welding process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. A mathematical model is presented to analyze the VPPA welding process. Results of the mathematical model were compared with the experimental observation accomplished by the GDI team.

  7. Temperature-independent formation of Au nanoparticles in ionic liquids by arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Yoshikiyo; Kimura, Satoshi; Kameyama, Tatsuya; Agawa, Yoshiaki; Tanaka, Hiroyuki; Judai, Ken; Torimoto, Tsukasa; Nishikawa, Keiko

    2016-08-01

    An effective preparation method of Au nanoparticles (NPs) is presented, wherein an arc plasma deposition technique is combined with ionic liquids (ILs) used as capture media. This method requires no chemical reaction. By selecting ILs, size-controlled Au NPs are produced easily and on a massive scale.

  8. Formation Of Antifriction And Wear-Proof Coatings By Heterogeneous Arc Plasma

    NASA Astrophysics Data System (ADS)

    Smyaglikov, I. P.; Chubrik, N. I.; Kuznechik, O. O.; Minko, D. V.

    2010-07-01

    Formation of coatings of the various functionality on electrode-detail while injecting of metal particles in plasma flow of short argon arc is considered. The possibility of formation both antifriction and wear-proof dense coatings, which have a metallurgical bond with a base, is shown.

  9. Surface Plasma Arc by Radio-Frequency Control Study (SPARCS)

    SciTech Connect

    Ruzic, David N.

    2013-04-29

    This paper is to summarize the work carried out between April 2012 and April 2013 for development of an experimental device to simulate interactions of o -normal detrimental events in a tokamak and ICRF antenna. The work was mainly focused on development of a pulsed plasma source using theta pinch and coaxial plasma gun. This device, once completed, will have a possible application as a test stand for high voltage breakdown of an ICRF antenna in extreme events in a tokamak such as edge-localized modes or disruption. Currently, DEVeX does not produce plasma with high temperature enough to requirement for an ELM simulator. However, theta pinch is a good way to produce high temperature ions. The unique characteristic of plasma heating by a theta pinch is advantageous for an ELM simulator due to its effective ion heating. The objective of the proposed work, therefore, is to build a test facility using the existing theta pinch facility in addition to a coaxial plasma gun. It is expected to produce a similar pulsed-plasma heat load to the extreme events in tokamaks and to be applied for studying interactions of hot plasma and ICRF antennas.

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

    NASA Astrophysics Data System (ADS)

    Amirov, R. Kh.; Vorona, N. A.; Gavrikov, A. V.; Lizyakin, G. D.; Polishchuk, V. P.; Samoilov, I. S.; Smirnov, V. P.; Usmanov, R. A.; Yartsev, I. M.

    2015-10-01

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

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

    SciTech Connect

    Amirov, R. Kh. Vorona, N. A.; Gavrikov, A. V.; Lizyakin, G. D.; Polishchuk, V. P.; Samoilov, I. S.; Smirnov, V. P.; Usmanov, R. A.; Yartsev, I. M.

    2015-10-15

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

  12. Solid oxide fuel cell processing using plasma arc spray deposition techniques

    SciTech Connect

    Ray, E.R.; Spengler, C.J.; Herman, H.

    1991-07-01

    The Westinghouse Electric Corporation, in conjunction with the Thermal Spray Laboratory of the State University of New York, Stony Brook, investigated the fabrication of a gas-tight interconnect layer on a tubular solid oxide fuel cell with plasma arc spray deposition. The principal objective was to determine the process variables for the plasma spray deposition of an interconnect with adequate electrical conductivity and other desired properties. Plasma arc spray deposition is a process where the coating material in powder form is heated to or above its melting temperature, while being accelerated by a carrier gas stream through a high power electric arc. The molten powder particles are directed at the substrate, and on impact, form a coating consisting of many layers of overlapping, thin, lenticular particles or splats. The variables investigated were gun power, spray distance, powder feed rate, plasma gas flow rates, number of gun passes, powder size distribution, injection angle of powder into the plasma plume, vacuum or atmospheric plasma spraying, and substrate heating. Typically, coatings produced by both systems showed bands of lanthanum rich material and cracking with the coating. Preheating the substrate reduced but did not eliminate internal coating cracking. A uniformly thick, dense, adherent interconnect of the desired chemistry was finally achieved with sufficient gas- tightness to allow fabrication of cells and samples for measurement of physical and electrical properties. A cell was tested successfully at 1000{degree}C for over 1,000 hours demonstrating the mechanical, electrical, and chemical stability of a plasma-arc sprayed interconnect layer.

  13. Solid oxide fuel cell processing using plasma arc spray deposition techniques. Final report

    SciTech Connect

    Ray, E.R.; Spengler, C.J.; Herman, H.

    1991-07-01

    The Westinghouse Electric Corporation, in conjunction with the Thermal Spray Laboratory of the State University of New York, Stony Brook, investigated the fabrication of a gas-tight interconnect layer on a tubular solid oxide fuel cell with plasma arc spray deposition. The principal objective was to determine the process variables for the plasma spray deposition of an interconnect with adequate electrical conductivity and other desired properties. Plasma arc spray deposition is a process where the coating material in powder form is heated to or above its melting temperature, while being accelerated by a carrier gas stream through a high power electric arc. The molten powder particles are directed at the substrate, and on impact, form a coating consisting of many layers of overlapping, thin, lenticular particles or splats. The variables investigated were gun power, spray distance, powder feed rate, plasma gas flow rates, number of gun passes, powder size distribution, injection angle of powder into the plasma plume, vacuum or atmospheric plasma spraying, and substrate heating. Typically, coatings produced by both systems showed bands of lanthanum rich material and cracking with the coating. Preheating the substrate reduced but did not eliminate internal coating cracking. A uniformly thick, dense, adherent interconnect of the desired chemistry was finally achieved with sufficient gas- tightness to allow fabrication of cells and samples for measurement of physical and electrical properties. A cell was tested successfully at 1000{degree}C for over 1,000 hours demonstrating the mechanical, electrical, and chemical stability of a plasma-arc sprayed interconnect layer.

  14. Measurement of transient force produced by a propagating arc magnetohydrodynamic plasma actuator in quiescent atmospheric air

    NASA Astrophysics Data System (ADS)

    Choi, Young Joon; Sirohi, Jayant; Raja, Laxminarayan L.

    2015-10-01

    An experimental study was conducted on a magnetohydrodynamic plasma actuator consisting of two parallel, six inch long, copper electrodes flush mounted on an insulating ceramic plate. An electrical arc is generated by a  ∼1 kA current pulse at  ∼100 V across the electrodes. A self-induced Lorentz force drives the arc along the electrodes. The motion of the arc induces flow in the surrounding air through compression as well as entrainment, and generates a transient force, about  ∼4 ms in duration. Experiments were performed on a prototype actuator in quiescent atmospheric air to characterize the motion of the arc and the momentum transferred to the surrounding air. Measurements included transient force and total impulse generated by the actuator as well as the armature voltage and current. The arc shape and transit velocity were determined by high-speed imaging. A peak force of 0.4 N imparting an impulse of 0.68 mN-s was measured for a peak current of 1.2 kA. The force scaled with the square of the armature current and the impulse scaled linearly with the spent capacitor energy. The results provide insight into the mechanisms of body force generation and momentum transfer of a magnetohydrodynamic plasma actuator.

  15. Experimental observation and numerical analysis of arc plasmas diffused by magnetism

    NASA Astrophysics Data System (ADS)

    Li, L. C.; Xia, W. D.; Zhou, H. L.; Zhou, Z. P.; Bai, B.

    2008-04-01

    At atmospheric pressure, an intensified charge-coupled device (ICCD) camera with a narrow-band filter is used to capture the unsaturated images of a magnetically rotating arc. Comparison of its configurations with different arc current and external axial magnetic field (AMF) strength shows that the strong electromagnetic force may impel the arc to diffuse. Under the fully diffuse mode, the plasma is distributed throughout the electrode gap and no anode attachment can be seen in the cross-section of the torch. The fully diffuse plasma runs more steadily and its intensity distribution is more uniform, while its voltage fluctuation is reduced significantly. Using a commercial CFD (computational fluid dynamics) code FLUENT, the fluid flow and heat transfer of the fully diffuse plasma in an assumed magnetron torch have been simulated for qualitatively discussing the AMF effects. Numerical results show that the AMF significantly impels the plasma to retract axially and expand radially. As a result, the plasma intensity distribution on the cross section of the torch gets to be more uniform.

  16. Pressure and arc voltage coupling in dc plasma torches: Identification and extraction of oscillation modes

    SciTech Connect

    Rat, V.; Coudert, J. F.

    2010-08-15

    This work is devoted to the instabilities occurring in a plasma torch, such as those found in plasma spraying. These instabilities are responsible for a lack of reproducibility of coatings properties, especially in the case of suspension plasma spraying that is an innovative way to obtain thin coatings of submicron-sized particles. Strong Helmholtz oscillations are highlighted in the plasma flow and it is demonstrated that they overlap with different acoustic modes in addition with the more commonly admitted ''restrike'' mode, the later being due to rearcing events in the arc region. The instabilities occur in the arc voltage but it is experimentally shown in this paper that the pressure within the torch body presents the same kind of instabilities. Besides, a numerical filtering technique has been adapted to isolate the different instability components. The operating parameters of the plasma torch were varied in order to highlight their influence on the amplitude of the different modes, both for the arc voltage and the pressure.

  17. PREFACE: 1st International Symposium on Electrical Arc and Thermal Plasmas in Africa (ISAPA)

    NASA Astrophysics Data System (ADS)

    Andre, Pascal; Koalaga, Zacharie

    2012-02-01

    Logos of the University of Ouagadougou, ISAPA and Universite Blaise Pascal Africa (especially Sub-Saharan Africa) is a continent where electrification is at a low level. However, the development of the electrical power sector is a prerequisite for the growth of other industrial activities, that is to say for the social and economic development of African countries. Consequently, a large number of electrification projects (rural electrification, interconnection of different country's grids) takes place in many countries. These projects need expertise and make Africa a continent of opportunity for companies in different domains for business and research: energy; energetic production, transmission, distribution and protection of electricity; the supply of cable; the construction, engineering and expertise in the field of solar and wind power. The first International Symposium on electrical Arc and thermal Plasma in Africa (ISAPA) was held for the first time in Ouagadougou, Burkina Faso to progress and develop the research of new physical developments, technical breakthroughs, and ideas in the fields of electrical production and electrical applications. The ISAPA aims to encourage the advancement of the science and applications of electrical power transformation in Africa by bringing together specialists from many areas in Africa and the rest of the world. Such considerations have led us to define a Scientific Committee including representatives from many countries. This first meeting was an innovative opportunity for researchers and engineers from academic and industrial sectors to exchange views and knowledge. Both fundamental aspects such as thermal plasma, electrical arc, diagnostics and applied aspects as circuit breakers, ICP analyses, photovoltaic energy conversion and alternative energies, as well as space applications were covered. The Laboratory of Material and Environment (LAME) from Ouagadougou University and the Laboratory of Electric Arc and Thermal

  18. Use of the Plasma Spectrum RMS Signal for Arc-Welding Diagnostics

    PubMed Central

    Mirapeix, Jesus; Cobo, Adolfo; Fuentes, Jose; Davila, Marta; Etayo, Juan Maria; Lopez-Higuera, Jose-Miguel

    2009-01-01

    A new spectroscopic parameter is used in this paper for on-line arc-welding quality monitoring. Plasma spectroscopy applied to welding diagnostics has typically relied on the estimation of the plasma electronic temperature, as there is a known correlation between this parameter and the quality of the seams. However, the practical use of this parameter gives rise to some uncertainties that could provoke ambiguous results. For an efficient on-line welding monitoring system, it is essential to prevent the appearance of false alarms, as well as to detect all the possible defects. In this regard, we propose the use of the root mean square signal of the welding plasma spectra, as this parameter will be proven to exhibit a good correlation with the quality of the resulting seams. Results corresponding to several arc-welding field tests performed on Inconel and titanium specimens will be discussed and compared to non-destructive evaluation techniques. PMID:22346696

  19. Use of the Plasma Spectrum RMS Signal for Arc-Welding Diagnostics.

    PubMed

    Mirapeix, Jesus; Cobo, Adolfo; Fuentes, Jose; Davila, Marta; Etayo, Juan Maria; Lopez-Higuera, Jose-Miguel

    2009-01-01

    A new spectroscopic parameter is used in this paper for on-line arc-welding quality monitoring. Plasma spectroscopy applied to welding diagnostics has typically relied on the estimation of the plasma electronic temperature, as there is a known correlation between this parameter and the quality of the seams. However, the practical use of this parameter gives rise to some uncertainties that could provoke ambiguous results. For an efficient on-line welding monitoring system, it is essential to prevent the appearance of false alarms, as well as to detect all the possible defects. In this regard, we propose the use of the root mean square signal of the welding plasma spectra, as this parameter will be proven to exhibit a good correlation with the quality of the resulting seams. Results corresponding to several arc-welding field tests performed on Inconel and titanium specimens will be discussed and compared to non-destructive evaluation techniques. PMID:22346696

  20. Arc-Plasma Wire Spraying: An Optical Study of Process Phenomenology

    NASA Astrophysics Data System (ADS)

    Gulyaev, I. P.; Dolmatov, A. V.; Kharlamov, M. Yu.; Gulyaev, P. Yu.; Jordan, V. I.; Krivtsun, I. V.; Korzhyk, V. M.; Demyanov, O. I.

    2015-12-01

    In the present paper, we report on the results of an experimental study of heat- and mass-transfer processes in a Plazer 30-PL-W plasma-jet facility used for arc-plasma wire spraying. Using an original optical diagnostic system, we have studied melting behavior of the metal wire, break up and atomization of liquid metal. For the first time, experimental data on the in-flight velocity and temperature of spray particles in arc-plasma wire spraying were obtained. In spite of moderate particle velocities (about 50 m/s), the obtained steel coatings proved to have a low porosity of 1.5%. While studying the spraying process of tungsten wire, we observed the occurrence of anomalous high-velocity (over 4000 m/s) outbursts ejected from the surface of liquid metal droplets. The nature of such outbursts calls for further study.

  1. SiC/C nanocable structure produced in silicon carbide by arc plasma heating

    NASA Astrophysics Data System (ADS)

    Nayak, B. B.

    2012-01-01

    Defect-free and long SiC/C nanocables have been produced by heating SiC powder at 3000°C by employing dc arc plasma (Ar) in a specially designed configuration of graphite arc. Microstructural characterizations of the heat-treated powder carried out by TEM, HRTEM, SAED, EDS, and micro Raman spectroscopy showed the nanocables to consist of a SiC shell/sheath stuffed with wire type solid C core. A possible mechanism is discussed to explain the cable-type growth.

  2. Coherent anti-Stokes Raman scattering performed on expanding thermal arc plasmas

    NASA Astrophysics Data System (ADS)

    Meulenbroeks, R. F. G.; Engeln, R. A. H.; van der Mullen, J. A. M.; Schram, D. C.

    1996-05-01

    The expanding plasma emanating from a thermal arc plasma source that can be used for deposition of thin films is studied using laser spectroscopic techniques. The argon-hydrogen plasma is characterized by very fast recombination that cannot be explained by atomic processes. To explore this phenomenon, which has been related to wall association of hydrogen atoms and recirculation, CARS (coherent anti-Stokes Raman scattering) is performed on (argon-)hydrogen plasmas. The periphery of the plasma appears to be rich in hydrogen molecules, in accordance with the recirculation model. No highly rovibrationally excited states are detected in the periphery, in spite of the spectrometer's very good sensitivity (0.1 Pa H2 at 300 K). For the plasma, rotational and vibrational temperatures as well as absolute H2 densities are measured. A simple model for the observed (non-Boltzmann) rotational populations is developed.

  3. Coherent anti-Stokes Raman scattering performed on expanding thermal arc plasmas

    SciTech Connect

    Meulenbroeks, R.F.; Engeln, R.A.; van der Mullen, J.A.; Schram, D.C.

    1996-05-01

    The expanding plasma emanating from a thermal arc plasma source that can be used for deposition of thin films is studied using laser spectroscopic techniques. The argon-hydrogen plasma is characterized by very fast recombination that cannot be explained by atomic processes. To explore this phenomenon, which has been related to wall association of hydrogen atoms and recirculation, CARS (coherent anti-Stokes Raman scattering) is performed on (argon-)hydrogen plasmas. The periphery of the plasma appears to be rich in hydrogen molecules, in accordance with the recirculation model. No highly rovibrationally excited states are detected in the periphery, in spite of the spectrometer{close_quote}s very good sensitivity (0.1 Pa H{sub 2} at 300 K). For the plasma, rotational and vibrational temperatures as well as absolute H{sub 2} densities are measured. A simple model for the observed (non-Boltzmann) rotational populations is developed. {copyright} {ital 1996 The American Physical Society.}

  4. The Radiative Transfer Of CH{sub 4}-N{sub 2} Plasma Arc

    SciTech Connect

    Benallal, R.; Liani, B.

    2008-09-23

    Any physical modelling of a circuit-breaker arc therefore requires an understanding of the radiated energy which is taken into account in the form of a net coefficient. The evaluation of the net emission coefficient is performed by the knowledge of the chemical plasma composition and the resolution of the radiative transfer equation. In this paper, the total radiation which escapes from a CH{sub 4}-N{sub 2} plasma is calculated in the temperature range between 5000 and 30000K on the assumption of a local thermodynamic equilibrium and we have studied the nitrogen effect in the hydrocarbon plasmas.

  5. Plasma surface interaction in hot filament cathode arc discharge used to nitride steel substrates

    NASA Astrophysics Data System (ADS)

    Dahiya, R. P.; Singh, O.; Aggarwal, V.; Malik, H. K.; Kumari, Nisha

    2012-10-01

    Plasma-assisted nitriding process is a well developed technique for increasing the surface hardness. The process is energy efficient, environment friendly and versatile to treat samples of various shapes and sizes. Though the use of this process in industry is established, there are several scientific questions in the basic understanding of the migration of ions, electrons and radicals and plasma surface interaction. We have studied these processes in an experimental system developed with hot cathode arc discharge plasma. A mixture of nitrogen and hydrogen is utilized for plasma generation. Negatively biased steel substrate is nitrided in this plasma. The hot cathode arc discharge plasma source is utilized to independently monitor and optimise the plasma and the work piece parameters. Substrate bias and temperature, which are the important parameters for achieving the desirable surface hardness, are regulated. Hardness depth profile and nitrogen content in the hardened sample are also measured. Transport and diffusion of ions, electrons, radicals and neutrals are considered to explain the results.

  6. Thermofluid Simulation of Arc Plasmas Confined by a Polymer Hollow Cylinder

    NASA Astrophysics Data System (ADS)

    Onchi, Toshiyuki; Tanaka, Yasunori; Kawasaki, Kei; Uesugi, Yoshihiko

    A numerical thermofluid model was developed for a simplified circuit breaker with POM or PTFE ablation phenomena to investigate their ablation effect on arc properties such as arc voltage, and temperature distribution. It is well known that polymer ablation occurs in actual circuit breakers, which markedly affects their current interruption capability. In this study, thermal plasma-polymer solid coupling phenomena such as melting and evaporation were calculated without any empirical model based on measurements unlike other existing numerical thermofluid model. Results showed that the ablated mass rate calculated with this model fairly agreed to the measurement. The influence of turbulent model on arc properties was also evaluated. As a result, it was confirmed that it was effective to consider the turbulent model.

  7. Spectroscopic Diagnostics and an Arc Jet Heated Air Plasma

    NASA Technical Reports Server (NTRS)

    Mack, Larry Howard, Jr.

    1996-01-01

    Spectral radiation measurements were made in the range of 200 to 900 nm across a section of the plenum of an arc jet wind tunnel using a series of optical fibers. The spectra contained line radiation from Oxygen and Nitrogen atoms and molecular radiation from N2(+), N2, and NO. Abel inversion technique is used to obtain radial distribution of the spectra. The analysis yielded radial profiles of the electronic excitation, vibrational and rotational temperatures of the flow field. Spectral fitting yielded branching ratios for different vibrational and rotational bands. Relatively mild flow conditions, i.e. enthalpy and mass flow rate, were used for prolonged measurements of up to and over two hours to establish the best experimental methods of temperature determinations. Signal to noise was improved by at least an order of magnitude enabling the molecular vibrational band heads of N2(+) (first negative system), N2 (second positive system), and NO (beta, gamma, delta, and epsilon systems) to be resolved in the lower ultraviolet wavelength regions. The increased signal to noise ratio also enabled partial resolution of the rotational lines of N2(+) and N2 in certain regions of minimal overlap. Comparison of the spectra with theoretical models such as the NEQAIR2 code are presented and show potential for fitting the spectra when reliable calibration is performed for the complete wavelength range.

  8. Contribution to arc plasma modeling for welding TIG application

    NASA Astrophysics Data System (ADS)

    Borel, Damien; Delalondre, Clarisse; Carpreau, Jean-Michel; Chéron, B. G.; Boubert, J.-P.

    2014-06-01

    In this paper we present a numerical model that simulates transferred energy by a welding thermal plasma to the weld pool. This energy transfer allows materials melting. The originality of our model is to include the modeling of transition zones and the vaporization of the anode. The cathodic and anodic areas are taken into account in the model by means of heat balance at the gas-solid interfaces. We report the heating and cooling effects they induce on the solid (cathode, anode) and plasma. Code_Saturne® the CFD software developed at EDF R&D is used for this work Comparisons between simulations and measurements of temperature and electron density confirm the model assumptions for TIG welding.

  9. Effect of plasma arc curing on polymerization shrinkage of orthodontic adhesive resins.

    PubMed

    Bang, H-C; Lim, B-S; Yoon, T-H; Lee, Y-K; Kim, C-W

    2004-08-01

    The purpose of this study was to evaluate the polymerization shrinkage of three orthodontic adhesive resins when polymerized with a high-energy plasma arc light (1340 mW cm(-2)) and a conventional halogen light (500 mW cm(-2)), and to correlate the polymerization shrinkage with the degree of conversion. To equalize the total light energy delivered to the adhesive resin, irradiation time was varied between 3 or 6 s for a plasma arc-curing unit, and 8 or 16 s for a halogen light-curing unit. The polymerization shrinkage of adhesive resins during the light-curing process was measured using a computer-controlled mercury dilatometer and the degree of conversion was measured using Fourier transform infrared spectroscopy. A plasma arccuring unit produced significantly lower polymerization shrinkage than a halogen light-curing unit when the equivalent total light energy was irradiated to the orthodontic adhesive resins (P < 0.05). The magnitude of polymerization shrinkage was significantly different depending on the kind of adhesive resins (P < 0.05), but there was no significant correlation between the filler fraction and the polymerization shrinkage (r2 = 0.039). There was strong correlation (r2 = 0.787) between the polymerization shrinkage and the degree of conversion with a halogen light-curing unit, but poor correlation (r2 = 0.377) was observed with a plasma arc-curing unit. PMID:15265218

  10. Variable polarity plasma arc welding on the Space Shuttle external tank

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Bayless, E. O., Jr.; Jones, C. S., III; Munafo, P. M.; Biddle, A. P.; Wilson, W. A.

    1984-01-01

    Variable polarity plasma arc (VPPA) techniques used at NASA's Marshall Space Flight Center for the fabrication of the Space Shuttle External Tank are presentedd. The high plasma arc jet velocities of 300-2000 m/s are produced by heating the plasma gas as it passes through a constraining orifice, with the plasma arc torch becoming a miniature jet engine. As compared to the GTA jet, the VPPA has the following advantages: (1) less sensitive to contamination, (2) a more symmetrical fusion zone, and (3) greater joint penetration. The VPPA welding system is computerized, operating with a microprocessor, to set welding variables in accordance with set points inputs, including the manipulator and wire feeder, as well as torch control and power supply. Some other VPPA welding technique advantages are: reduction in weld repair costs by elimination of porosity; reduction of joint preparation costs through elimination of the need to scrape or file faying surfaces; reduction in depeaking costs; eventual reduction of the 100 percent-X-ray inspection requirements. The paper includes a series of schematic and block diagrams.

  11. Plasma Science and Applications at the Intel

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2006-10-01

    The Coalition for Plasma Science (CPS) has established a plasma prize at the annual Intel International Science and Engineering Fair (ISEF). The 2006 prize was awarded for a project that investigated the correlation of GPS errors with various measures of near-earth plasma activity. The CPS is a broadly-based group of institutions and individuals whose goal is to increase the understanding of plasmas for non-technical audiences. In addition to the ISEF plasma award, CPS activities include maintaining a website, http://www.plasmacoalition.org; developing educational literature; organizing educational luncheon presentations for Members of Congress and their staffs; and responding to questions about plasmas. In addition, the CPS has begun as effort to examine the plasma content of state education standards with the goal of promoting the adoption of standards with appropriate plasma conten; e.g. are there three or four states of matter. The success of this and other activities depend on the voluntary labor of CPS members and associates. Please send an e-mail to the CPS at CPS@plasmacoalition.org for information if you would like to become involved in spreading the good word about plasmas.

  12. Study of the effect of plasma-striking atmosphere on Fe-oxidation in thermal dc arc-plasma processing

    SciTech Connect

    Banerjee, I.; Khollam, Y. B.; Mahapatra, S. K.; Das, A. K.; Bhoraskar, S. V.

    2010-11-15

    The effect of plasma-striking atmosphere: air and air+Ar-gas on the crystallization of Fe-oxide phases was studied using dc thermal arc-plasma processing route. The powders were characterized by x-ray diffraction, vibrating sample magnetometry, transmission electron microscopy, and Moessbauer spectroscopy techniques. At room temperature and O{sub 2} rich atmosphere, arc-evaporated Fe{sup 2+} ions oxidize into either {gamma}-Fe{sub 2}O{sub 3} or Fe{sub 3}O{sub 4} depending upon the combining ratio of Fe with molecular O{sub 2}. Fe/O ratio could be adjusted using proper flow rate of Ar gas to crystallize the pure {gamma}-Fe{sub 2}O{sub 3}.

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

    SciTech Connect

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan E-mail: alpers@ma.tum.de; Moseev, Dmitry; Kusano, Yukihiro; Salewski, Mirko; Alpers, Andreas E-mail: alpers@ma.tum.de; Gritzmann, Peter; Schwenk, Martin

    2015-01-26

    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 of the conducting zone of the plasma column.

  14. Radial Profiles of the Plasma Electron Characteristics in a 30 kW Arc Jet

    NASA Technical Reports Server (NTRS)

    Codron, Douglas A.; Nawaz, Anuscheh

    2013-01-01

    The present effort aims to strengthen modeling work conducted at the NASA Ames Research Center by measuring the critical plasma electron characteristics within and slightly outside of an arc jet plasma column. These characteristics are intended to give physical insights while assisting in the formulation of boundary conditions to validate full scale simulations. Single and triple Langmuir probes have been used to achieve estimates of the electron temperature (T(sub e)), electron number density (n(sub e)) and plasma potential (outside of the plasma column) as probing location is varied radially from the flow centerline. Both the electron temperature and electron number density measurements show a large dependence on radial distance from the plasma column centerline with T(sub e) approx. = (3 - 12 eV and n(sub e) approx. = 10(exp 12) - 10(exp 14)/cu cm.

  15. Influence of the arc plasma parameters on the weld pool profile in TIG welding

    NASA Astrophysics Data System (ADS)

    Toropchin, A.; Frolov, V.; Pipa, A. V.; Kozakov, R.; Uhrlandt, D.

    2014-11-01

    Magneto-hydrodynamic simulations of the arc and fluid simulations of the weld pool can be beneficial in the analysis and further development of arc welding processes and welding machines. However, the appropriate coupling of arc and weld pool simulations needs further improvement. The tungsten inert gas (TIG) welding process is investigated by simulations including the weld pool. Experiments with optical diagnostics are used for the validation. A coupled computational model of the arc and the weld pool is developed using the software ANSYS CFX. The weld pool model considers the forces acting on the motion of the melt inside and on the surface of the pool, such as Marangoni, drag, electromagnetic forces and buoyancy. The experimental work includes analysis of cross-sections of the workpieces, highspeed video images and spectroscopic measurements. Experiments and calculations have been performed for various currents, distances between electrode and workpiece and nozzle diameters. The studies show the significant impact of material properties like surface tension dependence on temperature as well as of the arc structure on the weld pool behaviour and finally the weld seam depth. The experimental weld pool profiles and plasma temperatures are in good agreement with computational results.

  16. Free fall plasma-arc reactor for synthesis of carbon nanotubes in microgravity

    SciTech Connect

    Alford, J. M.; Mason, G. R.; Feikema, D. A.

    2006-07-15

    High temperatures inside the plasma of a carbon arc generate strong buoyancy driven convection which has an effect on the growth and morphology of the single-walled carbon nanotubes (SWNTs). To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was designed and developed to synthesize SWNTs in a microgravity environment substantially free from buoyant convective flows. An arc reactor was operated in the 2.2 and 5.18 s drop towers at the NASA Glenn Research Center. The apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 A at 30 V to the arc for the duration of a 5 s drop. However, the principal result is that no dramatic difference in sample yield or composition was noted between normal gravity and 2.2 and 5 s long microgravity runs. Much longer duration microgravity time is required for SWNT's growth such as the zero-G aircraft, but more likely will need to be performed on the international space station or an orbiting spacecraft.

  17. Plasma Physics, Fusion Science, and California High School Science

    NASA Astrophysics Data System (ADS)

    Correll, Donald

    2004-11-01

    In order to further engage California HIgh School science teachers in plasma physics and fusion science, a collaboration was formed between LLNL's Fusion Energy Program and the University of California's Edward Teller Education Center (etec.ucdavis.edu). California's Science Content Standards for high school physics (www.cde.ca.gov/be/st/ss/scphysics.asp) were used to create a public lecture (education.llnl.gov/sos/) that covered "students are expected to achieve" physics topics relevant to astrophysical and fusion plasma research. In addition to the lecture, a two day workshop for the Edward Teller Education Symposium, September 24 - 25, 2004 (education.llnl.gov/symposium2004) was designed around plasma spectroscopy (education.llnl.gov/symposium2004/agenda_astro.html). Plasma spectroscopy was chosen as the "anchor" to the workshop given the breadth and depth of the field to both astrophysical and fusion plasma research. Workshop participation includes lectures, tours, spectroscopic measurements, and building a 'spectroscope' for use in the teachers' respective high school classrooms. Accomplishments will be reported and future plans will be presented that include development of a one to two week expanded workshop that includes plasma research methods and advanced science skills essential to guiding students to conduct research projects.

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

    PubMed

    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. PMID:25208416

  19. Plasma Display at the Liberty Science Center

    NASA Astrophysics Data System (ADS)

    Bruder, Dan; Gilligan, Nick; Tarman, Lisa; Ferris, Pamella; Morgan, James; Delooper, John; Zwicker, Andrew

    2009-11-01

    The Liberty Science Center (LSC) is the largest (300,000 sq. ft.) education resource in the New Jersey -- New York City region. PPPL in collaboration with the LSC has had a display at the center since 2007 More than 1.5 million visitors have come to the museum since the plasma display has been introduced. The plasma display has had significant use during that time frame. During the summer of 2009 a redesigned plasma exhibit was created by a student teacher-team using the lessons learned from the existing exhibit. The display includes a DC glow discharge tube with a permanent external magnet allowing visitors to manipulate the plasma and see how plasma can be used for fusion research. The goal of the display is to allow an individual to see a plasma and understand the potential benefits of fusion energy.

  20. Plasma arc melting of a 80 wt % tantalum-20 wt % titanium alloy

    SciTech Connect

    Dunn, P.S.; Patterson, R.A.

    1994-10-01

    An alloy of 80wt% tantalum-20wt% titanium is being considered for use in an oxidizing and highly corrosive liquid metal application. The high melting point of the alloy, 2400 C, and other physical properties narrowed the possible melting techniques. Previous melting experience with these materials by electron beam resulted in extensive vaporization of the titanium during the melt and poor chemical homogeneity. A technique has been developed using plasma arc melting to melt refractory alloys with very dissimilar densities and vapor pressures. The 80Ta--20Ti alloy falls into this category with the density of tantalum 16.5 g/cc and that of titanium 4.5 g/cc. The melting of these materials is further complicated by the high melting point of tantalum( 3020 C) and the relatively low boiling point of titanium( 3287 C). The plasma arc melting technique described results in good chemical homogeneity with ingot size quantities of material.

  1. Graphene layer growth on silicon substrates with nickel film by pulse arc plasma deposition

    SciTech Connect

    Fujita, K.; Banno, K.; Aryal, H. R.; Egawa, T.

    2012-10-15

    Carbon layer has been grown on a Ni/SiO{sub 2}/Si(111) substrate under high vacuum pressure by pulse arc plasma deposition. From the results of Raman spectroscopy for the sample, it is found that graphene was formed by ex-situ annealing of sample grown at room temperature. Furthermore, for the sample grown at high temperature, graphene formation was shown and optimum temperature was around 1000 Degree-Sign C. Transmission electron microscopy observation of the sample suggests that the graphene was grown from step site caused by grain of Ni film. The results show that the pulse arc plasma technique has the possibility for acquiring homogenous graphene layer with controlled layer thickness.

  2. Inner Surface Modification of a Tube by Magnetic Glow-Arc Plasma Source Ion Implantation

    NASA Astrophysics Data System (ADS)

    Zhang, Gu-Ling; Wang, Jiu-Li; Wu, Xing-Fang; Feng, Wen-Ran; Chen, Guang-Liang; Gu, Wei-Chao; Niu, Er-Wu; Fan, Song-Hua; Liu, Chi-Zi; Yang, Si-Ze

    2006-05-01

    A new method named the magnetic glow-arc plasma source ion implantation (MGA-PSII) is proposed for inner surface modification of tubes. In MGA-PSII, under the control of an axial magnetic field, which is generated by an electric coil around the tube sample, glow arc plasma moves spirally into the tube from its two ends. A negative voltage applied on the tube realized its inner surface implantation. Titanium nitride (TiN) films are prepared on the inner surface of a stainless steel tube in diameter 90 mm and length 600 mm. Hardness tests show that the hardness at the tube centre is up to 20 GPa. XRD, XPS and AES analyses demonstrate that good quality of TiN films can be achieved.

  3. Eddy intrustion of hot plasma into the polar cap and formation of polar-cap arcs

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Gorney, D. J.

    1983-01-01

    Under the simple postulate that multiple large scale detachable magnetospheric convection eddies can exist in the vicinity of the convection reversal boundary and in the polar cap, by Kelvin-Helmholtz instability or otherwise, it is shown that a number of seemingly disconnected plasma and electric field observations in the polar cap can be organized into a theory of magnetosheath and plasmasheet plasma intrusion into the polar cap. Current theory of inverted V structures then predicts existence of similar, but weaker, structures at the eddy convection reversal boundaries in the polar cap. A possible consequence is that the polar cap auroras are natural offshoots from discrete oval arcs and evidently are formed by similar processes. The two arc systems can occassionally produce an optical image in the form of the theta aurora.

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

    DOEpatents

    Brown, I.G.; MacGill, R.A.; Galvin, J.E.; Ogletree, D.F.; Salmeron, M.

    1998-11-24

    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. 8 figs.

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

    DOEpatents

    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.

  6. Analytical interpretation of arc instabilities in a DC plasma spray torch: the role of pressure

    NASA Astrophysics Data System (ADS)

    Rat, V.; Coudert, J. F.

    2016-06-01

    Arc instabilities in a plasma spray torch are investigated experimentally and theoretically thanks to a linear simplified analytical model. The different parameters that determine the useful properties of the plasma jet at the torch exit, such as specific enthalpy and speed, but also pressure inside the torch and time variations of the flow rate are studied. The work is particularly focused on the link between the recorded arc voltage and the pressure in the cathode cavity. A frequency analysis of the recorded voltage and pressure allows the separation of different contributions following their spectral characteristics and highlights a resonance effect due to Helmholtz oscillations; these oscillations are responsible for the large amplitude fluctuations of all the parameters investigated. The influence of heat transfer, friction forces and residence time of the plasma in the nozzle are taken into account, thanks to different characteristics’ times. The volume of the cathode cavity in which the cold gas is stored before entering the arc region appears to be of prime importance for the dynamics of instabilities, particularly for the non-intuitive effect that induces flow-rate fluctuations in spite of the fact that the torch is fed at a constant flow rate.

  7. Vacuum arc plasma generation and thin film deposition from a TiB{sub 2} cathode

    SciTech Connect

    Zhirkov, Igor Petruhins, Andrejs; Naslund, Lars-Ake; Rosen, Johanna; Kolozsvári, Szilard; Polcik, Peter

    2015-11-02

    We have studied the utilization of TiB{sub 2} cathodes for thin film deposition in a DC vacuum arc system. We present a route for attaining a stable, reproducible, and fully ionized plasma flux of Ti and B by removal of the external magnetic field, which leads to dissipation of the vacuum arc discharge and an increased active surface area of the cathode. Applying a magnetic field resulted in instability and cracking, consistent with the previous reports. Plasma analysis shows average energies of 115 and 26 eV, average ion charge states of 2.1 and 1.1 for Ti and B, respectively, and a plasma ion composition of approximately 50% Ti and 50% B. This is consistent with measured resulting film composition from X-ray photoelectron spectroscopy, suggesting a negligible contribution of neutrals and macroparticles to the film growth. Also, despite the observations of macroparticle generation, the film surface is very smooth. These results are of importance for the utilization of cathodic arc as a method for synthesis of metal borides.

  8. Vacuum arc plasma generation and thin film deposition from a TiB2 cathode

    NASA Astrophysics Data System (ADS)

    Zhirkov, Igor; Petruhins, Andrejs; Naslund, Lars-Ake; Kolozsvári, Szilard; Polcik, Peter; Rosen, Johanna

    2015-11-01

    We have studied the utilization of TiB2 cathodes for thin film deposition in a DC vacuum arc system. We present a route for attaining a stable, reproducible, and fully ionized plasma flux of Ti and B by removal of the external magnetic field, which leads to dissipation of the vacuum arc discharge and an increased active surface area of the cathode. Applying a magnetic field resulted in instability and cracking, consistent with the previous reports. Plasma analysis shows average energies of 115 and 26 eV, average ion charge states of 2.1 and 1.1 for Ti and B, respectively, and a plasma ion composition of approximately 50% Ti and 50% B. This is consistent with measured resulting film composition from X-ray photoelectron spectroscopy, suggesting a negligible contribution of neutrals and macroparticles to the film growth. Also, despite the observations of macroparticle generation, the film surface is very smooth. These results are of importance for the utilization of cathodic arc as a method for synthesis of metal borides.

  9. Plasma arc technology development for application to demilitarization of pyrotechnic ordnance

    SciTech Connect

    Mescavage, G.; Filius, K. |

    1995-12-31

    An initial investigation into the use of a plasma arc furnace for demilitarization of completely assembled, small-caliber, hand-emplaced pyrotechnic, smoke, and dye ordnance was conducted at the Department of Energy`s Western Environmental Technology Office, located in Butte, Montana. This technology is being pursued as an alternative to open burning/open detonation (OB/OD), which is the method of demilitarization traditionally used for these items, as increasingly more stringent environmental regulations have discouraged and disallowed the use of OB/OD. Problems have been experienced with the use of existing incinerators for demilitarization of these items. Varying quantities of 19 different types of live, completely assembled, small pyrotechnic, smoke, and dye items were processed in a pilot-scale Retech, Inc., Plasma Arc Centrifugal Treatment System. This testing demonstrated that a plasma arc furnace equipped with pollution abatement equipment can safely demilitarize these items in compliance with applicable environmental regulations. In addition, the process encapsulates heavy metals and other hazardous constituents into a solid, low-leachable slag product that passes Federally established tests as a nonhazardous material. This provides an advantage over standard incineration which yields a hazardous ash. The process also is able to overcome problems reported with standard incinerators. In addition, gas flows are significantly lower than those in standard incinerators, allowing smaller pollution abatement equipment to be used. However, operational problems and inefficiencies were identified that need to be resolved before full-scale implementation.

  10. A study of gas flow pattern, undercutting and torch modification in variable polarity plasma arc welding

    NASA Technical Reports Server (NTRS)

    Mcclure, John C.; Hou, Haihui Ron

    1994-01-01

    A study on the plasma and shield gas flow patterns in variable polarity plasma arc (VPPA) welding was undertaken by shadowgraph techniques. Visualization of gas flow under different welding conditions was obtained. Undercutting is often present with aluminum welds. The effects of torch alignment, shield gas flow rate and gas contamination on undercutting were investigated and suggestions made to minimize the defect. A modified shield cup for the welding torch was fabricated which consumes much less shield gas while maintaining the weld quality. The current torch was modified with a trailer flow for Al-Li welding, in which hot cracking is a critical problem. The modification shows improved weldablility on these alloys.

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

    PubMed

    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. PMID:27250481

  12. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  13. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    SciTech Connect

    Davydenko, V. I. Ivanov, A. A. Shul’zhenko, G. I.

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  14. Deposition of carbonic films from plasma of arc discharge without a cathode spot

    NASA Astrophysics Data System (ADS)

    Gasanov, I.; Gurbanov, I.

    2003-09-01

    PVD ways of synthesis of hydrogen-free diamond-like films with high speed of a deposition of particles are analyzed. The technique of obtaining of coatings by means of a vacuum - arc discharge and of a plasma-optical filter provide the highest characteristics of -C amorphous diamond. However, the given way of synthesis is unwieldy and requires considerable costs. The capability of creation of the reactor of carbonic plasma in discharge with electron-beam heating of the cathode is consider. The control of power, entered into the graphitic cathode, allows essentially to limit a dispersion of an evaporated material.

  15. Deposition of Functional Coatings Based on Intermetallic Systems TiAl on the Steel Surface by Vacuum Arc Plasma

    NASA Astrophysics Data System (ADS)

    Budilov, V.; Vardanyan, E.; Ramazanov, K.

    2015-11-01

    Laws governing the formation of intermetallic phase by sequential deposition of nano-sized layers coatings from vacuum arc plasma were studied. Mathematical modeling process of deposition by vacuum arc plasma was performed. In order to identify the structural and phase composition of coatings and to explain their physical and chemical behaviour XRD studies were carried out. Production tests of the hardened punching tools were performed.

  16. Low Friction-Coefficient TiBCN Nanocomposite Coatings Prepared by Cathode Arc Plasma Deposition

    NASA Astrophysics Data System (ADS)

    LIN, Baozhu; WANG, Lingling; WAN, Qiang; YAN, Shaojian; WANG, Zesong; YANG, Bing; FU, Dejun

    2015-03-01

    TiBCN nanocomposite coatings were deposited on cemented carbide and Si (100) by a cathode arc plasma system, in which TiB2 cathodes were used in mixture gases of N2 and C2H2. X-ray diffraction shows that TiB2 and Ti2B5 peaks enhance at low flow rates of C2H2, but they shrink when the flow rate is over 200 sccm. An increase of deposition rate was obtained from different TiBCN thicknesses for the same deposition time measured by scanning electron microscopy. Atomic force microscopy shows that the surface roughnesses are ˜10 nm and ˜20 nm at C2H2 flow rates of 0-100 sccm and of 150-300 sccm, respectively. High resolution transmission electron microscopy and X-ray photoelectron spectroscopy show that the coatings consist of nanocrystal phases Ti2BB, TiB2 and TiN, and amorphous phase carbon and BN. The average crystal sizes embedded in the amorphous matrices are 200 nm and 10 nm at C2H2 flow rates of 200 sccm and 300 sccm, respectively. In Raman spectra, the D- and G-bands increase with C2H2 flows at low flow rates, but weaken at high flow rates. The microhardness of the coatings decreases from 28.6 GPa to 20 GPa as the C2H2 increases from 0 sccm to 300 sccm, and the ball-on-disk measurement shows a dramatic decrease of the friction coefficient from 0.84 to 0.13. The reason for the reduced hardness and friction coefficient with the change of C2H2 flow rates is discussed. supported by National Natural Science Foundation of China (Nos. 11350110206, 11375133) and the Fundamental Research Funds for the Central Universities of China (No. 11275141)

  17. Railguns and plasma accelerators: arc armatures, pulse power sources and US patents

    SciTech Connect

    Friedrich, O.M. Jr.

    1980-11-01

    Railguns and plasma accelerators have the potential for use in many basic and applied research projects, such as in creating high-pressures for equation-of-state studies and in impact fusion. A brief review of railguns and plasma accelerators with references is presented. Railgun performance is critically dependent on armature operation. Plasma arc railgun armatures are addressed. Pulsed power supplies for multi-stage railguns are considered. This includes brief comments on the compensated pulsed alternator, or compulsator, rotating machinery, and distributed energy sources for railguns. References are given at the end of each section. Appendix A contains a brief review of the US Patents on multi-staging techniques for electromagnetic accelerators, plasma propulsion devices, and electric guns.

  18. Keyhole and weld shapes for plasma arc welding under normal and zero gravity

    NASA Technical Reports Server (NTRS)

    Keanini, R. G.; Rubinsky, B.

    1990-01-01

    A first order study of the interfacial (keyhole) shape between a penetrating argon plasma arc jet and a stationary liquid metal weld pool is presented. The interface is determined using the Young-Laplace equation by assuming that the plasma jet behaves as a one-dimensional ideal gas flow and by neglecting flow within the weld pool. The solution for the keyhole shape allows an approximate determination of the liquid-solid metal phase boundary location based on the assumption that the liquid melt is a stagnant thermal boundary layer. Parametric studies examine the effect of plasma mass flow rate, initial plasma enthalpy, liquid metal surface tension, and jet shear on weldment shape under both normal and zero gravity. Among the more important findings of this study is that keyhole and weld geometries are minimally affected by gravity, suggesting that data gathered under gravity can be used in planning in-space welding.

  19. Contamination due to memory effects in filtered vacuum arc plasma deposition systems

    SciTech Connect

    Martins, D.R.; Salvadori, M.C.; Verdonck, P.; Brown, I.G.

    2002-08-13

    Thin film synthesis by filtered vacuum arc plasma deposition is a widely used technique with a number of important emerging technological applications. A characteristic feature of the method is that during the deposition process not only is the substrate coated by the plasma, but the plasma gun itself and the magnetic field coil and/or vacuum vessel section constituting the macroparticle filter are also coated to some extent. If then the plasma gun cathode is changed to a new element, there can be a contamination of the subsequent film deposition by sputtering from various parts of the system of the previous coating species. We have experimentally explored this effect and compared our results with theoretical estimates of sputtering from the SRIM (Stopping and Range of Ions in Matter) code. We find film contamination of order 10-4 - 10-3, and the memory of the prior history of the deposition hardware can be relatively long-lasting.

  20. Formation of NOx precursors during Chinese pulverized coal pyrolysis in an arc plasma jet

    SciTech Connect

    Wei-ren Bao; Jin-cao Zhang; Fan Li; Li-ping Chang

    2007-08-15

    The formation of NOx precursors (HCN and NH{sub 3}) from the pyrolysis of several Chinese pulverized coals in an arc plasma jet was investigated through both thermodynamic analysis of the C-H-O-N system and experiments. Results of thermodynamic analysis show that the dominant N-containing gaseous species is HCN together with a small amount of ammonia above the temperature of 2000 K. The increase of H content advances the formation of HCN and NH{sub 3}, but the yields of HCN and NH{sub 3} are decreased with a high concentration of O in the system. These results are accordant with the experimental data. The increasing of input power promotes the formation of HCN and NH{sub 3} from coal pyrolysis in an arc plasma jet. Tar-N is not formed during the process. The yield of HCN changes insignificantly with the changing of the residence time of coal particles in the reactor, but that of NH{sub 3} decreases as residence times increase because of the relative instability at high temperature. Adsorption and gasification of CO{sub 2} on the coal surface also can restrain the formation of HCN and NH{sub 3} compare to the results in an Ar plasma jet. Yields of HCN and NH{sub 3} are sensitive to the coal feeding rate, indicating that NOx precursors could interact with the nascent char to form other N-containing species. The formation of HCN and NH{sub 3} during coal pyrolysis in a H{sub 2}/Ar plasma jet are not dependent on coal rank. The N-containing gaseous species is released faster than others in the volatiles during coal pyrolysis in an arc plasma jet, and the final nitrogen content in the char is lower than that in the parent coal, which it is independent of coal type. 16 refs., 9 figs., 1 tab.

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

    SciTech Connect

    Eriksson, A. O.; Zhirkov, I.; Dahlqvist, M.; Jensen, J.; Hultman, L.; Rosen, J.

    2013-04-28

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

  2. Measurement of temperature and electrons density distribution of atmospheric arc plasma by moiré deflectometry technique

    NASA Astrophysics Data System (ADS)

    Salimi Meidanshahi, Fatemeh; Madanipour, Khosro; Shokri, Babak

    2013-04-01

    In the present paper, the refractive index, electron density and temperature distribution of atmospheric arc plasmas are measured by moiré deflectometry. The deflection angle of rays passing through the plasma is obtained by moiré fringe analysis. Then by using inverse Abel transform integral for this axisymmetric plasma, the refractive index distribution is obtained in different points of plasma and environment. Considering the relation between plasma temperature and refractive index, the spatial temperature distribution of the arc plasma is evaluated. Also, in contrast to conventional models to obtain electron number density, in which the refractive index of plasmas is approximately assumed equal to the electron refractive index, a model is used for accurate and absolute measurement of the electron density profile. This technique is especially suitable for measuring axially symmetric plasma parameters.

  3. Plasma transferred arc rotary furnace for {open_quotes}corium{close_quotes} melting

    SciTech Connect

    Kassabji, F.; Cognet, G.; Jegou, C.; Roubaud, A.

    1995-12-31

    This paper presents a new plasma transferred arc rotary furnace equipment installed for the CEA in the research Centre of Cadarache in France; this project is conducted with EDF technical assistance. It is constructed by GEC-ALSTHOM for the total project and TETRONICS for plasma systems. This furnace is the central unit of a new facility, VULCANO E-30, prototype of a larger one, built in order to study the key phenomena involved in the behaviour and cooling of CORIUM at temperatures up to 3000{degrees}C. This centrifugal and tilted furnace is water cooled in a double shielded jacket. A self crucible is made up by the centrifugation of the powder material. A 300kW transferred arc is created between two plasma electrodes-torches allowing the creation of a plasma column at a high and relatively homogeneous temperature. The furnace is equipped by a product feeder at one of its extremities and by a boarded telemtry system allowing the transmission by infrared signals of the temperature measurements.

  4. Two-temperature modelling and optical emission spectroscopy of a constant current plasma arc welding process

    NASA Astrophysics Data System (ADS)

    Boselli, M.; Colombo, V.; Ghedini, E.; Gherardi, M.; Sanibondi, P.

    2013-06-01

    In this work, a plasma arc welding process with constant current in the range 25-70 A operating in pure Ar is characterized by means of both thermo-fluid-dynamic modelling under the assumption of local thermodynamic equilibrium (LTE) and two-temperature thermal non-equilibrium modelling (2T), allowing a comparison of the LTE temperature fields with electron and heavy particle temperature fields: thermal non-equilibrium is strongest in the fringes of the arc and upstream the plasma flow even though a temperature difference between electrons and heavy particles is also found in the arc core in the nozzle orifice, due to the high velocity of the gas. Also, excitation temperature of Ar atoms is obtained from optical emission spectroscopy measurements using a new method (called hybrid method) that extends the usability of the Boltzmann plot method to spatial regions where the signal-to-noise ratio of the spectral lines adopted in the calculation is poor. Good agreement is obtained between the modelling predicted electron temperature and the measured excitation temperature in the whole investigated spatial region.

  5. Plasma arc cutting optimization parameters for aluminum alloy with two thickness by using Taguchi method

    NASA Astrophysics Data System (ADS)

    Abdulnasser, B.; Bhuvenesh, R.

    2016-07-01

    Manufacturing companies define the qualities of thermal removing process based on the dimension and physical appearance of the cutting material surface. The surface roughness of the cutting area for the material and the material removal rate being removed during the manual plasma arc cutting process were importantly considered. Plasma arc cutter machine model PS-100 was used to cut the specimens made from aluminium alloy 1100 manually based on the selected parameters setting. Two different thicknesses of specimens, 3mm and 6mm were used. The material removal rate (MRR) was measured by determining the difference between the weight of specimens before and after the cutting process. The surface roughness (Ra) was measured by using MITUTOYO CS-3100 machine and analysis was conducted to determine the average roughness (Ra) value, Taguchi method was utilized as an experimental layout to obtain MRR and Ra values. The results indicate that the current and cutting speed is the most significant parameters, followed by the arc gap for both rate of material removal and surface roughness.

  6. Synthesis of few layer graphene by non-transferred arc plasma system.

    PubMed

    Baek, Jong-Jun; Kim, Tae-Hee; Park, Dong-Wha

    2013-11-01

    Graphene has recently been the focus of a great deal of attention owing to its outstanding properties, which include high mobility, high thermal conductivity and high structural stability. In this study, a few layer graphene was successfully synthesized from methane gas using a non-transferred direct current arc plasma system. Non-transferred thermal plasma offers high temperature, steep temperature gradient and high enthalpy to enhance the reaction kinetics of graphene synthesis. In order to prepare high quality few layer graphene, graphene products synthesized under several conditions was analyzed comparatively. Effects of gap distance between the plasma torch and graphite substrate, the flow rate of additional reactant gas, and different types of plasma forming gas on the synthesis of few layer graphene were investigated. Methane gas was injected into the plasma jet as a carbon source for the synthesis of graphene and a thermal plasma jet was generated by pure argon or a mixture of argon-hydrogen. The results revealed that hydrogen gas improved the quality of few layer graphene by inducing surface etching and increasing plasma power. PMID:24245266

  7. Enhancement of emission currents in plasma electron sources based on a low-pressure arc discharge

    NASA Astrophysics Data System (ADS)

    Koval, T. V.; Devyatkov, V. N.; Hung, Nguyen Bao

    2015-11-01

    The paper reports on a theoretical and experimental study of the discharge plasma generation with an enhanced electron emission current in a plasma electron source based on a low-pressure arc discharge with a grid-stabilized plasma emission boundary. The source operates at a pressure in the working chamber of p = 0.02-0.05 Pa (Ar), accelerating voltage of up to Ua = 10 kV, and longitudinal magnetic field for electron beam transport of up to Bz = 0.1 T. The experiments show that in the mode of electron emission from the plasma, the voltage Ud between the cathode and grid electrode changes its sign. The numerical simulation demonstrates that the plasma potential and voltage Ud depend on the electric field penetrating from the acceleration gap into the discharge region through the grid meshes, and on the discharge current, gas pressure, geometric transparency of the grid, and gas kind. It is shown that the main mechanisms responsible for the increase in the discharge current and electron emission current from the plasma are associated with secondary ion-electron emission from the emission electrode and with positive feedback between the region of cathode plasma generation and the channel of electron beam transport.

  8. Rocket measurements within a polar cap arc - Plasma, particle, and electric circuit parameters

    NASA Technical Reports Server (NTRS)

    Weber, E. J.; Ballenthin, J. O.; Basu, S.; Carlson, H. C.; Hardy, D. A.; Maynard, N. C.; Kelley, M. C.; Fleischman, J. R.; Pfaff, R. F.

    1989-01-01

    Results are presented from the Polar Ionospheric Irregularities Experiment (PIIE), conducted from Sondrestrom, Greenland, on March 15, 1985, designed for an investigation of processes which lead to the generation of small-scale (less than 1 km) ionospheric irregularities within polar-cap F-layer auroras. An instrumented rocket was launched into a polar cap F layer aurora to measure energetic electron flux, plasma, and electric circuit parameters of a sun-aligned arc, coordinated with simultaneous measurements from the Sondrestrom incoherent scatter radar and the AFGL Airborne Ionospheric Observatory. Results indicated the existence of two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability.

  9. Ion Species and Charge States of Vacuum Arc Plasma with Gas Feed and Longitudinal Magnetic Field

    SciTech Connect

    Oks, Efim; Anders, Andre

    2010-06-23

    The evolution of copper ion species and charge state distributions is measured for a long vacuum arc discharge plasma operated in the presence of a longitudinal magnetic field of several 10 mT and working gas (Ar). It was found that changing the cathode-anode distance within 20 cm as well as increasing the gas pressure did not affect the arc burning voltage and power dissipation by much. In contrast, burning voltage and power dissipation were greatly increased as the magnetic field was increased. The longer the discharge gap the greater was the fraction of gaseous ions and the lower the fraction of metal ions, while the mean ion charge state was reduced. It is argued that the results are affected by charge exchange collisions and electron impact ionization.

  10. Validated model of arc-filament plasma actuators for control of wall-bounded flows

    NASA Astrophysics Data System (ADS)

    Bodony, Daniel; Natarajan, Mahesh

    2011-11-01

    Plasma actuators based on the electrical arcs between two electrodes have shown promise in controlling high-subsonic and low-supersonic flows. Simulation-based predictions of these flows have often used heuristic models for the effect the plasma has on the flow to be controlled. In this talk we present a two-parameter model of the actuator which combines the unsteady Joule heating induced by the plasma with a thermally perfect model of air. PIV and spectroscopy data are used, in conjunction with simulations, to understand the two parameters and demonstrate how their values are to be determined. The importance of the cavity in which the electrodes are mounted is discussed, as is the role of diffusion. We demonstrate the use of the actuator model by controlling a high-subsonic, separating boundary layer in an S-duct geometry. Supported by the Rolls-Royce Corporation.