Science.gov

Sample records for arc plasma science

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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)

  9. 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)

  10. 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.

  11. 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.

  12. 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.

  13. Plasma arc melting of zirconium

    SciTech Connect

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

    1997-12-31

    Zirconium, like some other refractory metals, has an undesirable sensitivity to interstitials such as oxygen. Traditionally, zirconium is processed by electron beam melting to maintain minimum interstitial contamination. Electron beam melted zirconium, however, does not respond positively to mechanical processing due to its large grain size. The authors undertook a study to determine if plasma arc melting (PAM) technology could be utilized to maintain low interstitial concentrations and improve the response of zirconium to subsequent mechanical processing. The PAM process enabled them to control and maintain low interstitial levels of oxygen and carbon, produce a more favorable grain structure, and with supplementary off-gassing, improve the response to mechanical forming.

  14. 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.

  15. Micro-arcing in radio frequency plasmas

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Bilek, M. M. M.; McKenzie, D. R.; Boswell, R. W.; Charles, C.

    2004-10-01

    Micro-arcing and breakdown of the wall plasma sheath in radio frequency (RF) plasmas is studied in a hollow cathode system, using a Langmuir probe to measure the floating potential. Micro-arcing was induced reproducibly by controlling the floating potential. By dc grounding the hollow cathode, a negative current can flow to ground resulting in a higher voltage sheath between the plasma and the earthed vacuum vessel. The wall arcing threshold of the plasma potential in this system is in the vicinity of 50 V. In the present system, the charging process to rebuild the plasma potential, which is about a few tens of milliseconds, is much slower than the microsecond discharge. The arcing frequency was found to depend strongly on the plasma potential and the pressure. We propose a mechanism for the dependence of the frequency of periodic micro-arcing based on the development of electron field emission sites. The measurement of floating potential is suggested as a useful parameter to monitor and prevent micro-arcing in RF plasmas.

  16. 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…

  17. 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.

  18. Plasma distribution of cathodic ARC deposition system

    SciTech Connect

    Anders, S.; Raoux, S.; Krishnan, K.; MacGill, R.A.; Brown, I.G.

    1996-08-01

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

  19. 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)

  20. Aligning Plasma-Arc Welding Oscillations

    NASA Technical Reports Server (NTRS)

    Norris, Jeff; Fairley, Mike

    1989-01-01

    Tool aids in alignment of oscillator probe on variable-polarity plasma-arc welding torch. Probe magnetically pulls arc from side to side as it moves along joint. Tensile strength of joint depends on alignment of weld bead and on alignment of probe. Operator installs new tool on front of torch body, levels it with built-in bubble glass, inserts probe in slot on tool, and locks probe in place. Procedure faster and easier and resulting alignment more accurate and repeatable.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Cathodic Vacuum Arc Plasma of Thallium

    SciTech Connect

    Yushkov, Georgy Yu.; Anders, Andre

    2006-10-02

    Thallium arc plasma was investigated in a vacuum arc ionsource. As expected from previous consideration of cathode materials inthe Periodic Table of the Elements, thallium plasma shows lead-likebehavior. Its mean ion charge state exceeds 2.0 immediately after arctriggering, reaches the predicted 1.60 and 1.45 after about 100 microsecand 150 microsec, respectively. The most likely ion velocity is initially8000 m/s and decays to 6500 m/s and 6200 m/s after 100 microsec and 150microsec, respectively. Both ion charge states and ion velocities decayfurther towards steady state values, which are not reached within the 300microsec pulses used here. It is argued that the exceptionally high vaporpressure and charge exchange reactions are associated with theestablishment of steady state ion values.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

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

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.; Tyree, E.

    1985-01-01

    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. Occasionally 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.

  14. 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.

  15. 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)

  16. 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)

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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).

  6. 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.

  7. 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.

  8. Acoustic Monitoring of Plasma Arcs in Direct Current Electric Arc Furnaces

    NASA Astrophysics Data System (ADS)

    Burchell, J. J.; Aldrich, C.; Eksteen, J. J.; Niesler, T. R.; Jemwa, G. T.

    2009-12-01

    In this article, the extraction of features from acoustic signals generated by a 60-kW direct current electric arc furnace and the use of these features to infer the arc length of the plasma jets in the furnace were considered. A sensor capable of such measurements would be more robust to the unobservable fluctuations of the arc length and would, in principle, allow better control of smelting operations. The collected data comprised sets of five separate 10-second recordings of the acoustic signal, furnace current, and voltage, each at nominal arc lengths of 5, 15, and 25 mm. In the approach, time-frequency features initially were obtained through filter bank analysis of the signals. Reduction of the dimensionality of these filter bank features was then performed using a nonlinear subspace method called kernel Fisher discriminant analysis. Finally, kernel discriminant features were used to infer the arc length via a nearest neighbor classification model that associated three classes of arc lengths (5, 15, and 25 mm) with their corresponding features. The results of the small number of experiments suggest that a significant statistical relationship exists between the length of a plasma arc and its acoustic signal despite potentially large variations in arc phenomena inside the furnace.

  9. An interchangeable-cathode vacuum arc plasma source.

    PubMed

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

    2010-01-01

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

  10. 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.

  11. 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.

  12. Rotating arc plasma characteristics in the presence of methane flame

    NASA Astrophysics Data System (ADS)

    Hwang, Nakyung; Lee, Dae Hoon; Kim, Kwan Tae; Song, Young-Hoon

    2012-10-01

    Plasmas can ignite and stabilize flames under extreme conditions and have already been applied in practical combustors, but further studies are needed to elucidate the complex flame--plasma interactions. Here, we present the results of an experimental study on the interactions between a methane flame on a rotating arc plasma, with particular focus on the influence of flame conditions on plasma generation. A gas chromatograph, chemiluminescent NOx analyzer, optical emission spectrograph, and intensified charge-coupled device were used to monitor product gases (CO2, H2, CO, C2, C3, and NOx) with and without the plasma and also plasma characteristics (arc length, angular speed, and peak voltage) under different flame equivalence ratios φ. The results confirmed that the rotating arc indeed stabilized the flame and extended both flammability limits. In addition, the rotating arc was pushed upward and out of the reactor for rich and lean mixtures. The highest NOx concentration was obtained at the lower flammability limit in the presence of the plasma, but at φ = 1.0 without the plasma.

  13. Electric-Arc Plasma Installation for Preparing Nanodispersed Carbon Structures

    NASA Astrophysics Data System (ADS)

    Stefanov, P.; Garlanov, D.; Vissokov, G.

    2008-08-01

    An electric-arc plasma installation operated in the hidden anode arrangement is constructed and used for the preparation of carbon nanostructures. A contracted plasma arc generated by a plasma torch using an inert gas is used as heat source. The average mass temperature of arc is higher than 104 K, while its power density, which is directly transferred onto the electrode (anode), is ~ 2 kW/mm2. The anode contact area formed on the electrode moves against the arc by way of shifting the electrode and is hidden completely in the interior of plasma gas stream moving towards it. As a result of both the direct plasma attack and the opposite movement of streams in the hidden anode contact area, a temperature higher than 6000 K is reached. Thus, intensive vaporization takes place, which forms a saturated plasma-gas-aerosol phase of the initial material of electrode (anode). This gas phase is mixed in and carried by the plasma stream. Over that mixed plasma stream, a controlled process of quenching (fixation) is carried out by twisted turbulent fluid streams. After the fixation, the resultant carbon nano-structures are caught by a filter and collected in a bunker.

  14. Temporal and spatial distributions of carbon shunting arc plasma

    NASA Astrophysics Data System (ADS)

    Takaki, Koichi; Konishi, Takumi; Mikawa, Ryota; Takahashi, Kazunori; Yukimura, Ken

    2015-01-01

    The temporal and spatial distributions of a magnetically driven shunting arc plasma were obtained using time-resolved probe measurement. A shunting arc was produced using a carbon rod and accelerated along a pair of rail electrodes by a Lorenz force. The pulse current for driving and maintaining the plasma was supplied from a 20 µF capacitor charged by a dc power supply. Double and single probes were employed to obtain the ion density of the shunting arc plasma. An ion density of 1 × 1019 m-3 was obtained at a distance of 50 mm from the carbon rod 15 µs after applying voltage. The ion density decreased to 2.0 × 1018 m-3 with increasing distance from 50 to 150 mm. The ion density changed with the energy inputted into the plasma.

  15. A highly reliable trigger for vacuum ARC plasma source

    SciTech Connect

    Bernardet, H.; Godechot, X.; Jarjat, F.

    1996-08-01

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

  16. Simple filtered repetitively pulsed vacuum arc plasma source

    SciTech Connect

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

    2010-02-15

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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. The expanding thermal arc plasma: the low-flow regime

    NASA Astrophysics Data System (ADS)

    van de Sanden, M. C. M.; Tobin, J. A.

    1998-02-01

    This paper reports on experiments on an expanding thermal arc plasma using pure argon flows in the 50 to 500 sccm range. From pressure and voltage measurements on the arc it is verified that the arc plasma is still a thermal plasma at these low flows. Langmuir probe measurements of the radial profiles downstream using different flows and chamber pressures are presented and discussed. These measurements indicate an enhanced ion loss for low flows at constant pressure. The enhanced loss is explained by the increase in residence time and due to this a relatively large volumetric recombination. The sputter etch rate of PECVD deposited silicon oxide at 100 mTorr and 400 V DC bias is measured and compared with the results of the Langmuir probe.

  3. On plasma jet formation in vacuum arc with composite cathode

    NASA Astrophysics Data System (ADS)

    Shmelev, D. L.; Barengolts, S. A.; Uimanov, I. V.; Tsventoukh, M. M.; Savkin, K. P.

    2015-11-01

    This paper deals with the computer modeling of vacuum arc with composite multicomponent cathode. This arc is typical for certain kind of ion sources, plasma generator and vacuum interrupters. The described hybrid model treats the electrons as an inertialess fluid and ions as macroparticles. The macroparticle dynamic is calculated with the use of particle-incell method. Ion-ion Coulomb collision is considered with the use of Monte Carlo method. The model can simulate vacuum arc as a whole including separate cathode plasma jets, mixing zone, and common plasma column. The dependence of ion angular current distribution on the cathode composition reproduced with the help of developed model agrees well with experimental results.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Control of arc plasma torches: compensation of operational enthalpy drifts

    NASA Astrophysics Data System (ADS)

    Oliver, D. H.; Alexieva, J.; Djakov, B. E.; Enikov, R.; Dimitrov, D.

    2008-05-01

    In arc plasma torches electrode wear is the main reason for slow changes in the electrical and thermal torch characteristics. Such effects hinder technological applications of this type of plasma torches whenever the enthalpy must be maintained at a fixed level, or varied as needed. To solve this problem, a new method and algorithm for torch control are proposed. The time evolution of the arc current, voltage and thermal power loss of the torch are recorded. The values measured are used to find the required value of the enthalpy.

  9. 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.

  10. 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.

  11. [Study on the fluctuation phenomena of arc plasma spraying jet].

    PubMed

    Zhao, Wen-hua; Liu, Di; Tian, Kuo

    2002-08-01

    The turbulence phenomenon is one of the most attractive characteristics of a DC arc plasma spraying jet. Most of the previous investigations believe that there is a laminar flow region in core of the jet. A spectrum diagnostic system has been built up in this paper to investigate these effects with the aid of high-speed digital camera. The FFT method has been applied to the analysis on the arc voltage and light signals. The influence of the arc behavior and the power supply on the jet is full-scale. It seems that there is not a laminar flow region in core of the jet. Moreover, from the light dynamic variation graph, the jet fluctuation due to the arc voltage behavior maybe is the dominant characteristic of the jet behavior.

  12. Optical Plasma Control During ARC Carbon Nanotube Growth

    NASA Technical Reports Server (NTRS)

    Hinkov, I.; Farhat, S.; DeLaChapelle, M. Lamy; Fan, S. S.; Han, H. X.; Li, G. H.; Scott, C. D.

    2001-01-01

    To improve nanotube production, we developed a novel optical control technique, based on the shape of the visible plasma zone created between the anode and the cathode in the direct current (DC) arc process. For a given inert gas, we adjust the anode to cathode distance (ACD) in order to obtain strong visible vortices around the cathode. This enhance anode vaporization, which improve nanotubes formation. In light of our experimental results, we focus our discussion on the relationship between plasma parameters and nanotube growth. Plasma temperature control during arc process is achieved using argon, helium, and their mixtures as a buffer gases. The variation of the gas mixture from pure argon to pure helium changes plasma temperature. As a consequence, the microscopic characteristics of nanotubes as diameter distribution is changed moving from smaller values for argon to higher diameters for helium. We also observe a dependence of the macroscopic characteristics of the final products as Brunauer-Emmett-Teller (BET) surface area.

  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. 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.

  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. 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.

  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. 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.

  1. 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.

  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. 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.

  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. 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.

  8. Plasma Spraying of Copper by Hybrid Water-Gas DC Arc Plasma Torch

    NASA Astrophysics Data System (ADS)

    Kavka, T.; Matějíček, J.; Ctibor, P.; Mašláni, A.; Hrabovský, M.

    2011-06-01

    Water-stabilized DC arc plasma torches offer a good alternative to common plasma sources used for plasma spraying applications. Unique properties of the generated plasma are determined by a specific plasma torch construction. This article is focused on a study of the plasma spraying process performed by a hybrid torch WSP500®-H, which combines two principles of arc stabilization—water vortex and gas flow. Spraying tests with copper powder have been carried out in a wide range of plasma torch parameters. First, analyses of particle in-flight behavior for various spraying conditions were done. After, particles were collected in liquid nitrogen, which enabled analyses of the particle in-flight oxidation. A series of spraying tests were carried out and coatings were analyzed for their microstructure, porosity, oxide content, mechanical, and thermal properties.

  9. 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,…

  10. 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.

  11. 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.

  12. Dynamic voltage-current characteristics for a water jet plasma arc

    SciTech Connect

    Yang Jiaxiang; Lan Sheng; Xu Zuoming

    2008-05-05

    A virtual instrument technology is used to measure arc current, arc voltage, dynamic V-I characteristics, and nonlinear conductance for a cone-shaped water jet plasma arc under ac voltage. Experimental results show that ac arc discharge mainly happens in water vapor evaporated from water when heated. However, due to water's cooling effect and its conductance, arc conductance, reignition voltage, extinguish voltage, and current zero time are very different from those for ac arc discharge in gas work fluid. These can be valuable to further studies on mechanism and characteristics of plasma ac discharge in water, and even in gas work fluid.

  13. 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.

  14. 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).

  15. Plasma arc welding takes on the advanced solid rocket motor

    NASA Astrophysics Data System (ADS)

    Irving, Bob

    1992-12-01

    The general design of the Advanced Solid Rocket Motor (ASRM), developed with the aim of improving the flight safety, reliability, producibility, and performance of the Space Shuttle Motor, is described. The material for the new ASRM will be the more weldable HP-9-4-30 steel; it will be welded by the plasma arc process used in the straight polarity mode. An HP-9-4-25 filler metal will be used to deposit the fill pass and a cap pass; the welding operation will be computer controlled.

  16. Formation of carbon deposits from coal in an arc plasma

    SciTech Connect

    Wang, B.; Tian, Y.; Zhang, Y.; Zhu, S.; Lu, Y.; Zhang, Y.; Xie, K.

    2007-07-01

    The issue of deposited carbon (DC) on a reactor wall during the production of acetylene by the coal/arc plasma process is a potential obstacle for the industrialization process. The formation mechanism of DC is very difficult to reveal because the high complexity of coal and the volatile matter. Combining with quenching technique, the methane, liquid petroleum gas and benzene were employed as the model materials to roughly act as the light gas, chain and aromatic subcomponents of volatile matter, and then the reasonable formation mechanism of DC was subtly speculated accordingly.

  17. Interchange instability in finite conductivity accelerated plasma arcs

    NASA Astrophysics Data System (ADS)

    Bourouis, M.; Huerta, M. A.; Rodriguez-Trelles, F.

    1993-01-01

    A first order perturbation expansion of the MHD equations is used to study the growth of the Rayleigh-Taylor or interchange instability in accelerated plasma arcs. The mode equation is fourth-order, due to the inclusion of finite conductivity. It is solved numerically to yield results that are an improvement over previous work. The growth rates are less than in the infinite conductivity model. As in previous work the growth rates in typical rail launcher situations are large enough to permit full development of the instability.

  18. 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.

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

    SciTech Connect

    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.

  20. 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.

  1. 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.

  2. 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.

  3. Analysis of Thomson scattered light from an arc plasma jet.

    PubMed

    Gregori, G; Kortshagen, U; Heberlein, J; Pfender, E

    2002-04-01

    In this paper we present an analysis of Thomson scattered light from an arc plasma jet. Our approach goes beyond the standard random-phase approximation (RPA) and provides more consistent data for the electron temperature and density in plasmas that are weakly nonideal and collisional. The theory is based on a memory function formalism for the spectral density function with the use of the three lowest-order frequency-moment sum rules. These moments are then corrected for temperature inhomogeneities in the scattering volume. The proposed interpretation of scattering data is compared with the RPA result and with the standard Bhatnagar-Gross-Krook collisional model for the dynamic structure factor. It is shown that the obtained electron temperature values are closer but not equal to local thermodynamic equilibrium temperature values extracted from spectroscopic measurements.

  4. Arc plasma simulation of the KAERI large ion sourcea)

    NASA Astrophysics Data System (ADS)

    In, S. R.; Jeong, S. H.; Kim, T. S.

    2008-02-01

    The KAERI large ion source, developed for the KSTAR NBI system, recently produced ion beams of 100keV, 50A levels in the first half campaign of 2007. These results seem to be the best performance of the present ion source at a maximum available input power of 145kW. A slight improvement in the ion source is certainly necessary to attain the final goal of an 8MW ion beam. Firstly, the experimental results were analyzed to differentiate the cause and effect for the insufficient beam currents. Secondly, a zero dimensional simulation was carried out on the ion source plasma to identify which factors control the arc plasma and to find out what improvements can be expected.

  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. 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.

  7. Probe characterization of high-current driven metal plasma in a vacuum-arc rail gun

    NASA Astrophysics Data System (ADS)

    Vijayan, T.; Roychowdhury, P.; Venkatramani, N.

    2004-10-01

    The characteristics of metal plasma launched by high-current electric arc in a vacuum-arc rail gun are determined by employing electrical and magnetic probes. These measurements are validated by results from theoretical simulations. The arc coupled nonlinear circuit equations are solved simultaneously with the Newtonian arc motion and revealed the undercritically damped behavior of the arc current identical to the arc-current signal recorded by the Rogowski magnetic probe. Similarly the arc velocity and displacement derived from the signatures of B-dot probes are shown to concur closely with the results of J ×B propulsion from simulation. The heating of plasma is formulated in a three-electron population regime with direct arc energy coupling through magnetohydrodynamic, ion-acoustic, Coulomb, and neutral interactions. This results in high temperature (Te) of hundreds of eV in the arc as revealed by the simulation. Hence Te of the rapidly cooling and equilibrating plasma that emerged from the muzzle is high around 80-90eV, which is confirmed by Langmuir electric probe measurements. Density ne of this metal plasma is shown to be in the range 4×1021-6×1021m-3 and includes multiple ion charge states. The exit velocity of the plasma measured by a pair of Langmuir probes is close to 2.2×106cm/s and matched well with the arc velocity determined by the B-dot probes and the results from simulation.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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.

  17. Decomposition of toluene in a gliding arc discharge plasma reactor

    NASA Astrophysics Data System (ADS)

    Du, Chang Ming; Yan, Jian Hua; Cheron, Bruno

    2007-11-01

    The decomposition of toluene in a gliding arc discharge (glidarc) was performed and studied. Experimental results indicate that the glidarc technology can effectively decompose toluene molecules and has bright prospects of being applied as an alternative tool to decompose volatile organic compounds. It is found that a change in the electrode material had an insignificant effect on the toluene removal efficiency. The toluene removal efficiency increases with increasing inlet gas temperature. The water vapor present in the gas mixture has a favorable effect on the toluene decomposition in the plasma. The energy efficiency is 29.46 g (kWh-1) at a relative humidity of 50% and a specific energy input of 0.26 kWh m-3, which is higher than other types of non-thermal plasmas. Too much or too little oxygen content does not favor toluene decomposition. The major gas phase products detected by FT-IR from the decomposition of toluene with air participation were CO, CO2, H2O and NO2. Some brown depositions were found on the surface of the electrodes, which were polar oxygenous and nitrogenous compounds determined by the GC-MS analysis, such as benzaldehyde, benzoic acid, quinine and nitrophenol from the reaction of toluene with radicals. A possible mechanism for toluene destruction via glidarc technology is proposed and summarized.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  20. 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.

  1. Metal vapor plasma behavior during vacuum arc remelting of alloy 718

    SciTech Connect

    Zanner, F.J.; Maguire, M.C.; Williamson, R.L. ); Adasczik, C.B. ); Roberts, R.R. ); Strohecker, R. )

    1992-01-01

    A production vacuum arc remelt (VAR) furnace was modified to enable direct viewing of the metal vapor arc and molten electrode tip during melting of 432 mm dia. alloy 718 electrodes into 508 mm dia. ingots. Diffuse and constricted arcing conditions were characterized using high speed cinematography, standard video format, and monochromatic imaging. Constricted arcing was observed while melting electrodes contaminated with oxide slag of the type used for refractory linings in vacuum induction furnaces. Monochromatic imaging was used in visualize the ion distribution in the arc plasma; these images clearly showed whether the arc operated in a diffuse or constricted model. Diffuse arc melting conditions were very similar to those previously reported in the literature for smaller laboratory sized melts.

  2. Metal vapor plasma behavior during vacuum arc remelting of alloy 718

    SciTech Connect

    Zanner, F.J.; Maguire, M.C.; Williamson, R.L.; Adasczik, C.B.; Roberts, R.R.; Strohecker, R.

    1992-05-01

    A production vacuum arc remelt (VAR) furnace was modified to enable direct viewing of the metal vapor arc and molten electrode tip during melting of 432 mm dia. alloy 718 electrodes into 508 mm dia. ingots. Diffuse and constricted arcing conditions were characterized using high speed cinematography, standard video format, and monochromatic imaging. Constricted arcing was observed while melting electrodes contaminated with oxide slag of the type used for refractory linings in vacuum induction furnaces. Monochromatic imaging was used in visualize the ion distribution in the arc plasma; these images clearly showed whether the arc operated in a diffuse or constricted model. Diffuse arc melting conditions were very similar to those previously reported in the literature for smaller laboratory sized melts.

  3. 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.

  4. 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.

  5. Simulation of Motion, Heating, and Breakup of Molten Metal Droplets in the Plasma Jet at Plasma-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.; Ryabovolyk, Y. V.; Demyanov, O. I.

    2015-04-01

    The mathematical model for the process of plasma-arc wire spraying is proposed, which describes behavior of molten metal droplets in the plasma jet, allowing for the processes of their deformation and gas-dynamic breakup. Numerical analysis of the processes of motion, heating, and breakup of molten metal droplets, detached from the sprayed wire at plasma-arc spraying of coatings, was performed. It is shown that during molten droplets movement in the plasma jet their multiple breakup takes place, leading to formation of sprayed particles with dimensions much smaller than dimensions of initial droplets, detached from the sprayed wire tip.

  6. Probe characterization of high-current driven metal plasma in a vacuum-arc rail gun

    SciTech Connect

    Vijayan, T.; Roychowdhury, P.; Venkatramani, N.

    2004-10-15

    The characteristics of metal plasma launched by high-current electric arc in a vacuum-arc rail gun are determined by employing electrical and magnetic probes. These measurements are validated by results from theoretical simulations. The arc coupled nonlinear circuit equations are solved simultaneously with the Newtonian arc motion and revealed the undercritically damped behavior of the arc current identical to the arc-current signal recorded by the Rogowski magnetic probe. Similarly the arc velocity and displacement derived from the signatures of B-dot probes are shown to concur closely with the results of JxB propulsion from simulation. The heating of plasma is formulated in a three-electron population regime with direct arc energy coupling through magnetohydrodynamic, ion-acoustic, Coulomb, and neutral interactions. This results in high temperature (T{sub e}) of hundreds of eV in the arc as revealed by the simulation. Hence T{sub e} of the rapidly cooling and equilibrating plasma that emerged from the muzzle is high around 80-90 eV, which is confirmed by Langmuir electric probe measurements. Density n{sub e} of this metal plasma is shown to be in the range 4x10{sup 21}-6x10{sup 21} m{sup -3} and includes multiple ion charge states. The exit velocity of the plasma measured by a pair of Langmuir probes is close to 2.2x10{sup 6} cm/s and matched well with the arc velocity determined by the B-dot probes and the results from simulation.

  7. Design of a circular cascaded arc torch array for plasma spray

    NASA Astrophysics Data System (ADS)

    Sugimoto, T.; Horenstein, M.

    2003-12-01

    A new concept has been verified for a plasma spray electrode system that improves plasma plume uniformity over that of a single arc torch. A six-electrode, circular, arc-cascade discharge was formed by mounting seven tungsten-rod electrodes radially around a stream of argon gas. To maintain the plasma plume, the cascade-arc discharge was repetitively triggered using a cascaded high-voltage spark initiated by a secondary spark gap. The typical cascade arc voltage and current were 130 V and 20 A. Results show that the cascaded arc array system can create a ring-shaped plasma plume having near-uniform electrical energy in the circular direction. This feature suggests that the configuration may have future use in plasma torch systems requiring uniform circular symmetry. In such a system, spray particles can be injected into the center of the plasma ring. At the same time, such an arrangement also could provide a lower-cost alternative to systems that use multiple two-electrode plasma torches arranged in a circular configuration. In the latter system, each two-electrode plasma torch is fed by a separate power supply.

  8. 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.

  9. Spatial and temporal characteristics of a vacuum-arc rail-gun plasma

    NASA Astrophysics Data System (ADS)

    Roychowdhury, P.; Vijayan, T.; Iyengar, S. T.

    1997-08-01

    The dynamics of a vacuum-arc operated rail-gun plasma were numerically simulated for the undercritically damped regime and confirmed in experiments. Analytical solutions of arc current, its velocity, and position also showed good agreement with the results. The spatial development of the arc is shown here to follow a linear behavior, even though the propulsion velocity followed an exponential-step function due to the sinusoidal nature of the arc current. Peak arc current ˜100 kA, 15 μs period was propelled to ˜106 cm/s as indicated in time-of-flight measurements and simulations. The voltage signal induced on a B-dot probe by the dynamic sinusoidal arc was simulated, which compared well with the measured probe signal. A Gaussian current distribution inside the measured arc length ˜1-2 cm, was established by unfolding the B-dot probe signal. A peak magnetic field of the order 1-5 kG was also interpreted inside the arc. The emerging plasma contained ion current over tens of amperes in the pulse duration encompassing the arc envelope.

  10. Spatial and temporal characteristics of a vacuum-arc rail-gun plasma

    SciTech Connect

    Roychowdhury, P.; Vijayan, T.; Iyengar, S.T.

    1997-08-01

    The dynamics of a vacuum-arc operated rail-gun plasma were numerically simulated for the undercritically damped regime and confirmed in experiments. Analytical solutions of arc current, its velocity, and position also showed good agreement with the results. The spatial development of the arc is shown here to follow a linear behavior, even though the propulsion velocity followed an exponential-step function due to the sinusoidal nature of the arc current. Peak arc current {approximately}100kA, 15 {mu}s period was propelled to {approximately}10{sup 6}cm/s as indicated in time-of-flight measurements and simulations. The voltage signal induced on a B-dot probe by the dynamic sinusoidal arc was simulated, which compared well with the measured probe signal. A Gaussian current distribution inside the measured arc length {approximately}1{endash}2cm, was established by unfolding the B-dot probe signal. A peak magnetic field of the order 1{endash}5 kG was also interpreted inside the arc. The emerging plasma contained ion current over tens of amperes in the pulse duration encompassing the arc envelope. {copyright} {ital 1997 American Institute of Physics.}

  11. 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.

  12. Cathodic cleaning and heat input in variable polarity plasma arc welding of aluminum

    SciTech Connect

    Fuerschbach, P.W.

    1998-02-01

    For variable polarity plasma arc welding (VPPAW) of 1,100 Al, it was found that the net heat input to the aluminum workpiece did not decrease as independent changes in polarity balance enabled the tungsten electrode to become the predominant anode in the alternating current arc. For the thin sheet edge welds made in this study, the independent parameters used to vary the arc current polarity balance were very effective in delivering a wide range of actual arc power polarity balance. The ratio of electrode positive polarity arc energy to the total arc energy ranged from as little as 0.03 to as high as 0.99. Despite this pronounced difference in arc polarity, no significant variation in the average arc efficiency (net heat input/arc energy) of 0.51 was found. Substantial heating of the workpiece during electrode positive polarity was attributed to field type emission of electrons from the low boiling point aluminum cathode. Unlike thermionic emission at the tungsten, field emission electrons do not cool the cathode. While the actual arc efficiency were relatively constant, there were significant differences in the measured heat input, the weld size, and the effectiveness of the cathodic cleaning.

  13. Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures

    SciTech Connect

    Shashurin, A.; Li, J.; Zhuang, T.; Keidar, M.; Beilis, I. I.

    2011-07-15

    The temporal evolution of a high pressure He arc producing nanotubes was considered and the Langmuir probe technique was applied for plasma parameter measurements. Two modes of arc were observed: cathodic arc where discharge is supported by erosion of cathode material and anodic arc which is supported by ablation of the anode packed with carbon and metallic catalysts in which carbon nanotubes are synthesized. Voltage-current (V-I) characteristics of single probes were measured and unusually low ratio of saturation current on positively biased probe to that on negatively biased of about 1-4 was observed. This effect was explained by increase of measured current at the negatively biased probe above the level of ion saturation current due to secondary electron emission from the probe surface. Since utilization of standard collisionless approach to determine plasma parameters from the measured V-I characteristic is not correct, the electron saturation current was used to estimate the plasma density.

  14. Controlling synthesis of carbon nanostructures by plasma means in arc discharge

    NASA Astrophysics Data System (ADS)

    Volotskova, Olga; Shashurin, Alexey; Torrey, Jon; Raitses, Yevgeny; Keidar, Michael

    2009-11-01

    Thermal stability of SWNTs at conditions of atmospheric arc is crucial for determination of region of their synthesis in arc and in general for clarification of the thermal regime of SWNT in arc plasmas. We investigated electrical resistance dependence on temperature of mats of SWNTs under variable pressures in helium atmosphere, in the air and in vacuum in high temperature ranges (300-1200K) which closely mimic conditions during the synthesis in arc discharge. Dependence of SWNT resistance on temperature exhibits similar ``V-shape'' behavior for all applied conditions which characterized by two temperatures: Tmin (temperature of the minimum of resistance) and Tcr (temperature of destruction of SWNT bundles). It is found that Tmin and Tcr increased with helium pressure, so that at 500 Torr Tcr was 1100K, while Tmin -900K. This is the temperature that corresponds to buffer region between the arc plasma and helium background in arc discharge. Based on that it can be suggested that region of formation of SWNTs in arc should be close to arc periphery. Our study also demonstrates a strong effect of electric and magnetic fields on properties and growth conditions of SWNTs and other carbon nanostructures such as graphene. These effects are quantified by variety of diagnostics tools: SEM, TEM, AFM - microcopies, TGA, RAMAN and UV-vis-NIR.

  15. TOPICAL REVIEW: High-speed imaging in plasma arc cutting: a review and new developments

    NASA Astrophysics Data System (ADS)

    Colombo, V.; Concetti, A.; Ghedini, E.; Dallavalle, S.; Vancini, M.

    2009-05-01

    The aim of this paper is twofold: (i) to review all the achievements in our understanding of the phenomena related to plasma arc cutting (PAC) technology by means of high-speed camera (HSC) imaging and flow visualization techniques and (ii) to report on new studies that make use of recent and advanced instrumentation for HSC diagnostics, also highlighting some previously uncovered research subjects. In the last decade HSC imaging and flow visualization techniques have progressed considerably as a powerful qualitative diagnostic technique for investigating some of the fundamental phenomena typically occurring in PAC technology. More recently, HSC imaging has also been used to investigate pre-cut phases in PAC analysis, such as pilot arcing and piercing of mild steel and stainless steel plates with dual gas torches in various operating conditions, providing new insight into the process and highlighting some interesting plasma behaviour. HSC imaging of pilot arcing has been used to investigate the influence of the arc current, plasma pressure and swirl strength on the shape of the arc, on the type of the rotational motion of its attachment on the nozzle tip and to track trajectories and velocities of hafnium particles emitted from the electrode insert during that phase. HSC imaging can also highlight the behaviour of the arc during piercing phases and the possible presence of short non-destructive double arcing, otherwise impossible to recognize.

  16. Welding arc and plasma studies using real time, multipass holographic interferometry

    NASA Technical Reports Server (NTRS)

    Deason, Vance

    1987-01-01

    Flow visualization of the plasma process in a welding arc is being studied with a multipass Argon ion interferometer. High speed movies at 10,000 frames per/sec are taken. The multipass interferometer and several interferograms of the plasma near the electrode of the welding are given. Digitization of the fringes is currently done by hand.

  17. 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.

  18. Heat flux characteristics in an atmospheric double arc argon plasma jet

    SciTech Connect

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

    2008-10-13

    In this study, the axial evolution of heat flux excited by a double arc argon plasma jet impinging on a flat plate is determined, while the nonstationary behavior of the heat flux is investigated by combined means of the fast Fourier transform, Wigner distribution, and short-time Fourier transform. Two frequency groups (<1 and 2-10 kHz) are identified in both the Fourier spectrum and the time-frequency distributions, which suggest that the nature of fluctuations in the heat flux is strongly associated with the dynamic behavior of the plasma arc and the engulfment of ambient air into different plasma jet regions.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. High-speed imaging investigation of transient phenomena impacting plasma arc cutting process optimization

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    In this work, we report on the investigation of selected transient phenomena taking place in plasma arc cutting (PAC) that are relevant for process optimization. High-speed imaging diagnostics is exploited for the characterization of different technological solutions in order to provide deeper insights into torch and process design. In particular, the pilot arc start-up phase is analysed for a 250 A automatic dual-gas torch equipped with electrodes with different shapes of the initial insert recess, revealing that there is no influence of the recess depth on the time for the stabilization of the pilot arc attachment on the cathode insert. The influence of different insert materials, including Ag-Hf and Cu-Zr binary alloys, on erosion during the shut-down phase is investigated at 120 A and reduced emission of material and faster shut-down is found for alloy inserts compared with standard Hf inserts. The start-up and shut-down transients are also investigated during transferred arc operation using a modified nozzle that comprises a viewing port on one side of the nozzle, and pulsing arc behaviour inside the plasma chamber that is correlated with cathode-nozzle voltage oscillations at a frequency of 7.7 kHz is found. Finally, results regarding the influence of different plasma gas diffusers on the arc stability during the cutting initiation phase in a 100 A mono-gas manual torch are reported.

  7. 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.

  8. Shapes of Spectral Lines of Nonuniform Plasma of Electric Arc Discharge Between Copper Electrodes

    NASA Astrophysics Data System (ADS)

    Babich, Ida L.; Boretskij, Viacheslav F.; Veklich, Anatoly N.

    2007-09-01

    The radial profiles of the temperature and electron density in the plasma of the free burning electric arc between copper electrodes are studied by optical spectroscopy techniques. The electron density and the temperature in plasma as initial parameters were used in the calculation of the plasma composition in local thermodynamic equilibrium (LTE) assumption. We used the Saha's equation for copper, nitrogen and oxygen, dissociation equation for nitrogen and oxygen, the equation of plasma electrical neutrality and Dalton's law as well. So, it would be possible to determine the amounts of metal vapours in plasma.

  9. Shapes of Spectral Lines of Nonuniform Plasma of Electric Arc Discharge Between Copper Electrodes

    SciTech Connect

    Babich, Ida L.; Boretskij, Viacheslav F.; Veklich, Anatoly N.

    2007-09-28

    The radial profiles of the temperature and electron density in the plasma of the free burning electric arc between copper electrodes are studied by optical spectroscopy techniques. The electron density and the temperature in plasma as initial parameters were used in the calculation of the plasma composition in local thermodynamic equilibrium (LTE) assumption. We used the Saha's equation for copper, nitrogen and oxygen, dissociation equation for nitrogen and oxygen, the equation of plasma electrical neutrality and Dalton's law as well. So, it would be possible to determine the amounts of metal vapours in plasma.

  10. 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.

  11. Preparation of High-Purity Cobalt by Anion-Exchange Separation and Plasma Arc Melting

    NASA Astrophysics Data System (ADS)

    Uchikoshi, Masahito; Shibuya, Hideka; Imaizumi, Junichi; Kékesi, Tamás; Mimura, Kouji; Isshiki, Minoru

    2010-04-01

    High-purity Co was prepared with valence-controlled anion-exchange separation, oxidation refining using plasma arc melting, and H2-Ar plasma arc melting on a pilot scale. The result of a laboratory-scale experiment indicated that the slower flow rate is more effective to remove the impurities by anion-exchange separation. However, the separation efficiency is reduced by scaling up the column from the laboratory to pilot scale. The discussion of the decrease in the separation efficiency implies that the distribution coefficient increases as the concentration of the adsorbate is lowered, but a reduced slower flow rate might increase the final purity of Co. In addition to anion-exchange separation, Co oxidation refining using plasma arc melting was useful. Consequently, a high-purity Co of 99.9998 pct by mass excluding gaseous elements was prepared, which represents the highest purity reported.

  12. 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.

  13. 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.

  14. 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

  15. [Experimental investigation of the chemical effect of direct current arc plasma igniter].

    PubMed

    Zhao, Bing-Bing; He, Li-Ming; Shen, Ying; Bai, Xiao-Feng; Yu, Jin-Lu

    2013-05-01

    To study the chemical effect of direct current arc plasma igniter, the emission spectrum of plasma jet was measured, and the active particles produced by the interaction of plasma jet with atmospheric air were analyzed. The NO and CO volume fractions were measured quantificationally by smoke analyzer at the 8cm downstream the plasma igniter exit, and the changing law between arc current and NO, CO volume fractions was obtained. The results show that the plasma jet interacting with atmospheric air produced active particles (H, O, N), charged particles (O2 +, N2+), and excited particles (N2 (A3), N2 (B3), N2 (C3), N2 (a1), O2 (a1), O2 (b1)). The NO and CO volume fractions increased with rising of are current and feedstock argon flow rate.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Thin film synthesis using miniature pulsed metal vapor vacuum arc plasma guns

    SciTech Connect

    Godechot, X.; Salmeron, M.B.; Ogletree, D.F.; Galvin, J.E.; MacGill, R.A.; Dickinson, M.R.; Yu, K.M.; Brown, I.G.

    1990-04-01

    Metallic coatings can be fabricated using the intense plasma generated by the metal vapor vacuum arc. We have made and tested an embodiment of vacuum arc plasma source that operates in a pulsed mode, thereby acquiring precise control over the plasma flux and so also over the deposition rate, and that is in the form of a miniature plasma gun, thereby allowing deposition of metallic thin films to be carried out in confined spaces and also allowing a number of such guns to be clustered together. The plasma is created at the cathode spots on the metallic cathode surface, and is highly ionized and of directed energy a few tens of electron volts. Adhesion of the film to the substrate is thus good. Virtually all of the solid metals of the Periodic Table can be used, including highly refractory metals like tantalum and tungsten. Films, including multilayer thin films, can be fabricated of thickness from Angstroms to microns. We have carried out preliminary experiments using several different versions of miniature, pulsed, metal vapor vacuum arc plasma guns to fabricate metallic thin films and multilayers. Here we describe the plasma guns and their operation in this application, and present examples of some of the thin film structures we have fabricated, including yttrium and platinum films of thicknesses from a few hundred Angstroms up to 1 micron and an yttrium-cobalt multilayer structure of layer thickness about 100 Angstroms. 33 refs., 5 figs.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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…

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    SciTech Connect

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

    2010-05-01

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

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.}

  10. 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.

  11. An in vivo study to compare a plasma arc light and a conventional quartz halogen curing light in orthodontic bonding.

    PubMed

    Pettemerides, A P; Sherriff, M; Ireland, A J

    2004-12-01

    The purpose of this study was to compare the effectiveness of a plasma arc lamp with a conventional tungsten quartz halogen lamp in orthodontic bonding. Twenty consecutive patients had their brackets bonded either with Transbond XT (n = 10) or Fuji Ortho LC (n = 10). In total, 352 teeth were bonded, 176 in each group. Using a randomized cross-mouth control study design, where diagonally opposite quadrants were assigned a particular treatment, the bonds were then either cured with the control light, namely a halogen lamp, or a plasma arc lamp. The halogen light was used for 20 seconds per tooth and the plasma arc lamp for 3 seconds per tooth. The measurement parameter used was bond failure and the patients were monitored for a period of 6 months following initial bond placement. In the Transbond XT group, the proportion of bond failures was 3.41 per cent for both the halogen and the plasma arc lamp. For the Fuji Ortho LC group, the proportions were 11.4 and 10.2 per cent, respectively. No difference was observed with respect to in-service bond failure proportions between bonds cured with the plasma arc or the conventional halogen lamp, irrespective of the bonding agent. Use of the plasma arc lamp could therefore lead to considerable savings in clinical time. However, this must be weighed against the increased purchase price of the plasma arc lamp. PMID:15650065

  12. Elements of arc welding

    SciTech Connect

    Not Available

    1993-07-01

    This paper looks at the following arc welding techniques: (1) shielded metal-arc welding; (2) submerged-arc welding; (3) gas metal-arc welding; (4) flux-cored arc welding; (5) electrogas welding; (6) gas tungsten-arc welding; and (7) plasma-arc welding.

  13. Disposal of spent tributylphosphate by gliding arc plasma.

    PubMed

    Moussa, David; Brisset, Jean Louis

    2003-08-29

    The gliding arc in humid air is a relevant source of free radicals and strongly oxidising species such as HO* (shown by emission spectroscopy), which are able to degrade organic wastes. This feature was used in a new process for mineralising spent tributylphosphate (TBP) which is an important waste from nuclear industry. The degradation kinetics is examined by monitoring the conversion of TBP into phosphoric acid in a batch reactor. The kinetics exhibits three steps and especially an overall zero-order linear step with a rate of 10 mmol h(-1) at the beginning of the treatment. This zero-order step agrees with a surface oxidation process. After a 13.7h treatment, about 45% of the TBP is converted into inorganic phosphorus compounds, with phosphoric acid as the major product (63% of inorganic phosphorus compounds), and at least 19.5% is not degraded. Dibutylphosphoric acid (HDBP) was identified as the main by-product by a nuclear magnetic resonance technique, infrared spectroscopy and gas chromatography.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. High-speed three-dimensional plasma temperature determination of axially symmetric free-burning arcs

    NASA Astrophysics Data System (ADS)

    Bachmann, B.; Kozakov, R.; Gött, G.; Ekkert, K.; Bachmann, J.-P.; Marques, J.-L.; Schöpp, H.; Uhrlandt, D.; Schein, J.

    2013-03-01

    In this paper we introduce an experimental technique that allows for high-speed, three-dimensional determination of electron density and temperature in axially symmetric free-burning arcs. Optical filters with narrow spectral bands of 487.5-488.5 nm and 689-699 nm are utilized to gain two-dimensional spectral information of a free-burning argon tungsten inert gas arc. A setup of mirrors allows one to image identical arc sections of the two spectral bands onto a single camera chip. Two-different Abel inversion algorithms have been developed to reconstruct the original radial distribution of emission coefficients detected with each spectral window and to confirm the results. With the assumption of local thermodynamic equilibrium we calculate emission coefficients as a function of temperature by application of the Saha equation, the ideal gas law, the quasineutral gas condition and the NIST compilation of spectral lines. Ratios of calculated emission coefficients are compared with measured ones yielding local plasma temperatures. In the case of axial symmetry the three-dimensional plasma temperature distributions have been determined at dc currents of 100, 125, 150 and 200 A yielding temperatures up to 20000 K in the hot cathode region. These measurements have been validated by four different techniques utilizing a high-resolution spectrometer at different positions in the plasma. Plasma temperatures show good agreement throughout the different methods. Additionally spatially resolved transient plasma temperatures have been measured of a dc pulsed process employing a high-speed frame rate of 33000 frames per second showing the modulation of the arc isothermals with time and providing information about the sensitivity of the experimental approach.

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

    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 5.18s drop towers at the NASA Glenn Research Center. The apparatus employed a 4mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300A at 30V to the arc for the duration of a 5s drop. However, the principal result is that no dramatic difference in sample yield or composition was noted between normal gravity and 2.2 and 5s 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Surface modification by nonthermal plasma induced by using magnetic-field-assisted gliding arc discharge

    NASA Astrophysics Data System (ADS)

    Feng, Zongbao; Saeki, Noboru; Kuroki, Tomoyuki; Tahara, Mitsuru; Okubo, Masaaki

    2012-07-01

    The authors report on the introduction of a magnetic field to gliding arc discharge (GD) in order to enhance surface modification by nonthermal plasma at atmospheric-pressure. The GD is induced between two wire electrodes by using a pulse high-voltage power supply with peak-to-peak voltage of 5 kV. When a magnetic field of 0.25 T is applied, the GD enlarged and a 19-cm-long stretch of plasma is excited. The surface treatment of polyethylene terephthalate and polytetrafluoroethylene films is performed. The adhesion improved by up to ˜30 times due to the enhanced chemical activity in the films.

  12. 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

  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. 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.

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

    NASA Astrophysics Data System (ADS)

    Davydenko, V. I.; Ivanov, A. A.; Shul'zhenko, G. I.

    2015-11-01

    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 LaB6 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.

  16. 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.

  17. Features of thermal processes of plasma deposition and hardening of coatings with external modulation parameters of the arc

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Sharifullin, S. N.; Maltsev, A. F.

    2016-06-01

    In the work on the basis of mathematical modeling analysis of processes of plasma deposition of coatings with modulation of the electrical parameters of the extension arc. The effect of modulation on the temperature field in the system "coating-basis" on a local scale, proportionate to the diameter of the spot attachment of the arc to the surface, and at the macrolevel of evaporation surface. It justifies the preconditions of the improvement of plasma deposition and hardening coatings.

  18. 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.

  19. 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.

  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. 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.

  3. 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.

  4. On a possible connection between the longitudinally propagating near-Earth plasma sheet and auroral arc waves: A reexamination

    NASA Astrophysics Data System (ADS)

    Motoba, T.; Ohtani, S.; Donovan, E. F.; Angelopoulos, V.

    2015-01-01

    propagating low-frequency waves (or wavy structures) often occur in a localized region of the near-Earth plasma sheet and auroral arc immediately prior to auroral breakup. Although both are believed to be magnetospheric and ionospheric manifestations of a plasma sheet instability that may lead to substorm onset, the fundamental coupling processes behind their relationship are not yet understood. To address this question, we reexamined in detail a fortuitous conjunction event of prebreakup near-Earth plasma sheet and auroral arc waves, initially reported by Uritsky et al. (2009) using the Time History of Events and Macroscale Interactions during Substorms space-ground observations. The event exhibited a morphological one-to-one association between longitudinally propagating arc wave (LPAW) in the ionosphere and Pi2/Pc4 range wave activity in the plasma sheet. Our analysis revealed that (1) the LPAW was the periodic luminosity modulation of the growth phase arc by faint, diffuse, green line-dominated auroral patches propagating westward along/near the arc, rather than some type of small-scale arc structuring, such as auroral beads/rays/undulations; and (2) the plasma sheet wave, which had a diamagnetic nature, propagated duskward with accompanying coincident modulation of field-aligned fluxes of 0.1-30 keV electrons. These findings suggest that the LPAW was likely connected to the plasma sheet wave via modulated diffuse precipitation of hard plasma sheet electrons (> ~1 keV), not via filamentary field-aligned currents, as expected from the ballooning instability regime. Another potential implication is that such prebreakup low-frequency wave activity in the near-Earth plasma sheet is not necessarily guaranteed to initiate prebreakup auroral arc structuring.

  5. Influence of steering magnetic field on the time-resolved plasma chemistry in cathodic arc discharges

    NASA Astrophysics Data System (ADS)

    Ehiasarian, A. P.; Hovsepian, P. Eh; New, R.; Valter, J.

    2004-08-01

    External magnetic fields are used extensively to steer the cathode spot of arc discharges in order to improve target utilization and minimize droplet generation. Optical emission spectroscopy (OES) and electrostatic probe measurements in a Cr arc discharge were used to characterize the effect of the external magnetic field on the ion flux to the substrates and on the composition and time evolution of the plasma. A combination of a permanent magnet array and an electromagnetic coil was used to vary the shape and strength of the magnetic field on the cathode surface. Finite element modelling of the magnetic field distribution identified two types of geometry—through-field, with lines normal to the cathode surface, and arched-field, with lines forming a magnetic 'tunnel'. The magnetic flux densities measured with a Hall probe were in the range from -15 to +15 mT. The particular shape and strength of the magnetic field determined the specific confinement regions and diffusion pathways for the plasma. The total ion saturation current density at the substrate position was in the range between 2 and 11.5 mA cm-2 depending on the magnetic field shape. The magnetic field strongly influenced the relative optical emission from Cr0, Cr1+ and Cr2+ metal species, and the resulting charge state distribution. Time-resolved OES and probe measurements of a particular position on the arc cathode revealed that an Ar plasma is trapped near the cathode and is sustained even when the cathode spot is a significant distance from the observation volume. The importance of this 'residual' Ar plasma for the charge state distribution of metal ions is discussed.

  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. 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.

  8. The plasma wave environment of an auroral arc - Electrostatic ion cyclotron waves in the diffuse aurora

    NASA Technical Reports Server (NTRS)

    Bering, E. A.

    1984-01-01

    Electric field plasma wave observations were made with a sounding rocket payload in and near a quiet auroral arc. This payload was launched on March 9, 1978 from Poker Flat, Alaska. The payload trajectory was close to the magnetic meridian and passed over a 40 kR auroral arc. The present investigation is concerned with ac electric field observations in the ELF and lower VLF covering a frequency range from 2.5 Hz to 8 kHz. Attention is given to aspects of instrumentation, the general situation, a data analysis, and the obtained results. Waves were observed at low altitude in a region of downward parallel current and diffuse aurora. These waves had properties consistent with those expected for hydrogen and oxygen electrostatic ion cyclotron (EIC) waves.

  9. 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.

  10. 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.

  11. 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.

  12. IEEE International conference on plasma science: Conference record--Abstracts

    SciTech Connect

    Not Available

    1993-01-01

    The conference covered the following topics: basic plasma physics; vacuum electronics; gaseous and electrical gas discharges; laser-produced plasma; space plasmas; computational plasma science; plasma diagnostics; electron, ion and plasma sources; intense electron and ion beams; intense beam microwaves; fast wave M/W devices; microwave-plasma interactions; magnetic fusion; MHD; plasma focus; ultrafast z-pinches and x-ray lasers; plasma processing; fast-opening switches; EM and ETH launchers; solid-state plasmas and switches; plasmas for lighting; ball lightning and spherical plasma configurations; and environmental/energy issues. Separate abstracts were prepared for 379 items in this conference.

  13. Experimental investigation on the characteristics of the plasma jet of a low-current vacuum arc in axial magnetic fields

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Shi, Zongqian; Wu, Bingzhou; Gao, Zhanpeng; Jia, Shenli; Wang, Lijun

    2016-04-01

    In this paper, the characteristics of the plasma jet of a low-current vacuum arc with a single cathode spot (CS) in an external axial magnetic field (AMF) up to 150 mT is investigated experimentally, at a constant arc current ranging from 20 A to 60 A. The experiments are conducted with Cu butt contacts in a demountable vacuum chamber. Images of the plasma jets are photographed with a high-speed digital camera with an exposure time of 2 μs. The uniform constant AMF (B n ) within the inter-contacts region is supplied by Nd-Fe-B permanent magnets. The influence of the external AMF on the shape of the jet near the anode surface as well as in the arc column is mainly investigated. A luminous ‘spot’ is observed on the anode surface facing the position of the CS under a relatively strong AMF. The mechanism of the appearance of the luminous ‘spot’ is proposed to be connected to the secondary plasma originating from the anode. Moreover, with the increase in the strength of the AMF, the spreading angle of the cone-shaped plasma jet in the arc-column region decreases gradually. The plasma jet, subjected to a relatively strong AMF (120 mT and 150 mT), becomes cylindrical in shape in the arc-column region and conical in shape in the near-electrode regions. The overall geometry of the plasma jet looks like a dumbbell.

  14. Influence of residual plasma drift velocity on the post-arc sheath expansion of vacuum circuit breakers

    NASA Astrophysics Data System (ADS)

    Mo, Yongpeng; Shi, Zongqian; Bai, Zhibin; Jia, Shenli; Wang, Lijun

    2016-05-01

    The residual plasma in the inter-contact region of a vacuum circuit breaker moves towards the post-arc cathode at current zero, because the residual plasma mainly comes from the cathode spots during the arc burning process. In the most previous theoretical researches on the post-arc sheath expansion process of vacuum circuit breakers, only the thermal motion of residual plasma was taken into consideration. Alternately, the residual plasma was even assumed to be static at the moment of current zero in some simplified models. However, the influence of residual plasma drift velocity at current zero on the post-arc sheath expansion process was rarely investigated. In this paper, this effect is investigated by a one-dimensional particle-in-cell model. Simulation results indicate that the sheath expands slower with higher residual plasma drift velocity in the initial sheath expansion stage. However, with the increase of residual plasma drift velocity, the overall plasma density in the inter-contact region decreases faster, and the sheath expansion velocity increases earlier. Consequently, as a whole, it needs shorter time to expel the residual plasma from the inter-contact region. Furthermore, if the residual plasma drift velocity is high enough, the sheath expansion process ceases before it develops to the post-arc anode. Besides, the influence of the collisions between charges and neutrals is investigated as well in terms of the density of metal vapor. It shows that the residual plasma drift velocity takes remarkable effect only if the density of the metal vapor is relatively low, which corresponds to the circumstance of low-current interruptions.

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

    SciTech Connect

    Bernardet, H.; Godechot, X.; Riviere, C.

    1996-08-01

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

  16. Cluster observations of the plasma sheet at very high latitudes: The in situ signature of a transpolar arc

    NASA Astrophysics Data System (ADS)

    Fear, R. C.; Milan, S. E.; Maggiolo, R.

    2013-12-01

    Transpolar arcs are auroral features which extend into the polar cap, which is the dim region poleward of the main auroral oval. Several case and statistical studies have shown that they are formed by the closure of lobe magnetic flux by magnetotail reconnection, and that the transpolar arc forms at the footprints of the newly-closed field lines which are embedded within the open flux of the polar cap. Therefore, when transpolar arcs occur, the magnetotail should contain closed magnetic field lines even at high latitudes (but in a localised sector), embedded within the open lobe flux. We present in situ observations of this phenomenon, taken by the Cluster spacecraft on 15th September 2005. Cluster was located at high latitudes in the southern hemisphere lobe (far from the typical location of the plasma sheet), and a transpolar arc was observed by the FUV cameras on the IMAGE satellite. An initial analysis reveals that Cluster periodically observed plasma similar to a typical plasma sheet distribution, but at much higher latitudes - indicative of closed flux embedded within the high latitude lobe. Each time that this plasma distribution was observed, the footprint of the spacecraft mapped to the transpolar arc (significantly poleward of the main auroral oval). These observations are consistent with closed flux being trapped in the magnetotail and embedded within the lobe, and provide further evidence for transpolar arcs being formed by magnetotail reconnection.

  17. Demonstration of Plasma Arc Environmental Technology Applications for the Demilitrization of DOD Stockpiles

    NASA Technical Reports Server (NTRS)

    Smith, Ed; Dee, P. E.; Zaghloul, Hany; Filius, Krag; Rivers, Tim

    2000-01-01

    Since 1989 the US Army Construction Engineering Research Laboratories (USACERL) have been active participants in the research and development towards establishing Plasma Arc Technology (PAT) as an efficient, economical, and safe hazardous waste immobilization tool. A plasma torch capable of generating high temperatures makes this technology a viable and powerful tool for the thermal destruction of various military industrial waste streams into an innocuous ceramic material no longer requiring hazardous waste landfill disposal. The emerging plasma environmental thermal treatment process has been used to safely and efficiently meet the waste disposal needs for various demilitarized components disposal needs, such as: (1) pyrotechnic smoke assemblies, (2) thermal batteries, (3) proximity fuses, (4) cartridge actuated devices (CADs), and (5) propellant actuated devices (PADs). MSE Technology Applications, Inc., (MSE) has proposed and fabricated a Mobile Plasma Treatment System to be a technology demonstrator for pilotscale mobile plasma waste processing. The system is capable of providing small-scale waste remediation services, and conducting waste stream applicability demonstrations. The Mobile Plasma Treatment System's innovative concept provides the flexibility to treat waste streams at numerous sites and sites with only a limited quantity of waste, yet too hazardous to transport to a regional fixed facility. The system was designed to be operated as skid mounted modules; consisting of a furnace module, controls module, offgas module, and ancillary systems module. All system components have been integrated to be operated from a single control station with both semi-continuous feeding and batch slag-pouring capability.

  18. Literature review of arc/plasma, combustion, and joule-heated melter vitrification systems

    SciTech Connect

    Freeman, C.J.; Abrigo, G.P.; Shafer, P.J.; Merrill, R.A.

    1995-07-01

    This report provides reviews of papers and reports for three basic categories of melters: arc/plasma-heated melters, combustion-heated melters, and joule-heated melters. The literature reviewed here represents those publications which may lend insight to phase I testing of low-level waste vitrification being performed at the Hanford Site in FY 1995. For each melter category, information from those papers and reports containing enough information to determine steady-state mass balance data is tabulated at the end of each section. The tables show the composition of the feed processed, the off-gas measured via decontamination factors, gross energy consumptions, and processing rates, among other data.

  19. High-density plasma-arc heating studies of FePt thin films

    NASA Astrophysics Data System (ADS)

    Cole, Amanda; Thompson, Gregory B.; Harrell, J. W.; Weston, J.; Ott, Ronald

    2006-06-01

    The effect of pulsed-thermal-processing with high-density plasma arc heating is discussed for 20 nm thick nanocrystalline FePt thin films. The dependence of the A1→L10 phase transformation on pulsed time and radiant energy of the pulse is quantified through x-ray diffraction and alternating gradient magnetometry. For 100 ms and 250 ms pulse widths, the phase transformation was observed. Higher radiant energy densities resulted in a larger measured coercivity associated with the L10 phase.

  20. Comparative characteristics of electron energy spectrum in PIG and arc type discharge plasmas

    NASA Technical Reports Server (NTRS)

    Romanyuk, L. I.; Suavilnyy, N. Y.

    1978-01-01

    The electron distribution functions relative to the velocity component directed along the magnetic field are compared for PIG and arc type discharges. The identity of these functions for the plasma region pierced by the primary electron beam and their difference in the peripheral part of the discharge are shown. It is concluded that the electron distribution function in the PIG type discharge is formed during one transit of the primary electron through the discharge gap. The mechanisms of electron energy spectrum formation in both the axis region and the peripheral region of the discharge are discussed.

  1. Research briefing on contemporary problems in plasma science

    NASA Technical Reports Server (NTRS)

    1991-01-01

    An overview is presented of the broad perspective of all plasma science. Detailed discussions are given of scientific opportunities in various subdisciplines of plasma science. The first subdiscipline to be discussed is the area where the contemporary applications of plasma science are the most widespread, low temperature plasma science. Opportunities for new research and technology development that have emerged as byproducts of research in magnetic and inertial fusion are then highlighted. Then follows a discussion of new opportunities in ultrafast plasma science opened up by recent developments in laser and particle beam technology. Next, research that uses smaller scale facilities is discussed, first discussing non-neutral plasmas, and then the area of basic plasma experiments. Discussions of analytic theory and computational plasma physics and of space and astrophysical plasma physics are then presented.

  2. Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

    PubMed

    Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

    2013-11-01

    To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films.

  3. Demonstration of Plasma Arc Environmental Technology Applications for the Demilitarization of DOD Stockpiles

    NASA Technical Reports Server (NTRS)

    Smith, Ed; Zaghloul, Hany; Filius, Krag; Rivers, Tim

    2000-01-01

    Since 1989 the U.S. Army Construction Engineering Research Laboratories (USACERL) have been active participants in the research and development toward establishing Plasma Arc Technology (PAT) as an efficient, economical, and safe hazardous waste immobilization tool. A plasma torch capable of generating high temperatures makes this technology a viable and powerful tool for the thermal destruction of various military industrial waste streams into an innocuous ceramic material no longer requiring hazardous waste landfill (Class 1) disposal. The emerging pl asma environmental thermal treatment process, has been used to safely and efficiently meet the waste disposal needs for various demilitarized components disposal needs, such as: pyrotechnic smoke assemblies, thermal batteries, proximity fuses, cartridge actuated devices (CAD's), and propellant actuated devices (PAD's). MSE Technology Applications, Inc., (MSE) has proposed and fabricated a Mobile Plasma Treatment System to be a technology demonstrator for pilot-scale mobile plasma waste processing. The system is capable of providing small-scale waste remediation services, and conducting waste stream applicability demonstrations. The Mobile Plasma Treatment System's innovative concept provides the flexibility to treat waste streams at numerous sites and sites with only a limited quantity of waste, yet too hazardous to transport to a regional fixed facility. The system was designed to be operated as skid mounted modules; consisting of a furnace module, controls module, offgas module, and ancillary systems module. All system components have been integrated to be operated from a single control station with both semi-continuous feeding and batch slag-pouring capability.

  4. Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

    PubMed

    Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

    2013-11-01

    To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films. PMID:24245257

  5. Structural evolution of Ti destroyable interlayer in large-size diamond film deposition by DC arc plasma jet

    NASA Astrophysics Data System (ADS)

    Guo, Jianchao; Li, Chengming; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Hua, Chenyi; Yan, Xiongbo

    2016-05-01

    The addition of titanium (Ti) interlayer was verified to reduce the residual stress of diamond films by self-fracturing and facilitate the harvest of a crack-free free-standing diamond film prepared by direct current (DC) arc plasma jet. In this study, the evolution of the Ti interlayer between large-area diamond film and substrate was studied and modeled in detail. The evolution of the interlayer was found to be relevant to the distribution of the DC arc plasma, which can be divided into three areas (arc center, arc main, and arc edge). The formation rate of titanium carbide (TiC) in the arc main was faster than in the other two areas and resulted in the preferred generation of crack in the diamond film in the arc main during cooling. Sandwich structures were formed along with the growth of TiC until the complete transformation of the Ti interlayer. The interlayer released stress via self-fracture. Avoiding uneven fragile regions that formed locally in the interlayer and achieving cooperatively released stress are crucial for the preparation of large crack-free diamond films.

  6. Nickel-containing carbon nanotubes and nanoparticles prepared in a high-frequency arc plasma

    NASA Astrophysics Data System (ADS)

    Osipova, I. V.; Vnukova, N. G.; Glushchenko, G. A.; Krylov, A. S.; Tomashevich, E. V.; Zharkov, S. M.; Churilov, G. N.

    2009-09-01

    This paper presents the results of an investigation of nickel-containing carbon nanostructures prepared by plasma-chemical synthesis in a carbon-helium plasma jet at atmospheric pressure with the arc fed by a high-frequency current. It is demonstrated that, under these conditions, the conversion of graphite into a carbon condensate reaches 98 wt % and the contents of carbon nanotubes and nickel in this condensate are 72 and 10 wt %, respectively. Sequential treatment with nitric and hydrochloric acids has made it possible to extract purified carbon nanotubes and nickel nanoparticles coated with a carbon shell (approximately 50 nm thick) in which the nickel content is 4 wt %. Data are presented on the diameters of the prepared nanotubes and on the state of carbon in the samples.

  7. Thermodynamic study on the formation of acetylene during coal pyrolysis in the arc plasma jet

    SciTech Connect

    Bao, W.; Li, F.; Cai, G.; Lu, Y.; Chang, L.

    2009-07-01

    Based on the principle of minimizing the Gibbs free energy, the composition of C-H-O-N-S equilibrium system about acetylene formation during the pyrolysis in arc plasma jet for four kinds of different rank-ordered coals such as Datong, Xianfeng, Yangcheng, and Luan was analyzed and calculated. The results indicated that hydrogen, as the reactive atmosphere, was beneficial to the acetylene formation. The coal ranks and the hydrogen, oxygen, nitrogen, and sulfur in coal all could obviously affect the acetylene yield. The mole fraction of acetylene is the maximum when the ratio value of atom H/C was 2. The content of oxygen was related to the acetylene yield, but it does not compete with CO formation. These agreed with the experimental results, and they could help to select the coal type for the production of acetylene through plasma pyrolysis process.

  8. Underwater plasma-MIG arc welding: Shielding technique and pressure reduction by a centrifugal pump

    SciTech Connect

    Creutz, M.; Mewes, D.; Bartzsch, J.; Draugelates, U.

    1995-12-31

    In comparison to hyperbaric underwater welding in diving chambers, wet welding techniques promise higher flexibility and lower costs. One technique for creating a local dry and pressure reduced welding zone is the use of a centrifugal pump. Results of experimental investigations in combination with a plasma-MIG arc welding system are presented in this paper. Special importance is attached to the local pressure reduction in view of the fact that low pressure, i.e. a high pressure difference between surrounding water and dry welding area, is a good condition for welding but is difficult to be obtained with other shielding systems than pressure chambers. Plasma-MIG welding has been done under water with a good result on the weld quality. Values of the hardness of the joint and the appearance of the weld structure are nearly comparable to atmospheric welds.

  9. Boron Ion Implantation into Silicon by Use of the Boron Vacuum-Arc Plasma Generator

    SciTech Connect

    Williams, J. M.; Klepper, C. C.; Chivers, D. J.; Hazelton, R. C.; Moschella, J. J.; Keitz, M. D.

    2006-11-13

    This paper continues with presentation of experimental work pertaining to use of the boron vacuum arc (a.k.a. cathodic arc) plasma generator for boron doping in semiconductor silicon, particularly with a view to the problems associated with shallow junction doping. Progress includes development of an excellent and novel macroparticle filter and subsequent ion implantations. An important perceived issue for vacuum arc generators is the production of copious macroparticles from cathode material. This issue is more important for cathodes of materials such as carbon or boron, for which the particles are not molten or plastic, but instead are elastic, and tend to recoil from baffles used in particle filters. The present design starts with two vanes of special orientation, so as to back reflect the particles, while steering the plasma between the vanes by use of high countercurrents in the vanes. Secondly, behind and surrounding the vanes is a complex system of baffles that has been designed by a computer-based strategy to ultimately trap the particles for multiple bounces. The statistical transmittance of particles is less than 5 per coulomb of boron ions transmitted at a position just a few centimeters outside the filter. This value appears adequate for the silicon wafer application, but improvement is easily visualized as wafers will be situated much further away when they are treated in systems. A total of 11 silicon samples, comprising an area of 250 cm2, have been implanted. Particles were not detected. Sample biases ranged from 60 to 500 V. Boron doses ranged from 5 x 1014 to 5 x 1015/cm2. Exposure times ranged from 20 to 200 ms for average transmitted boron current values of about 125 mA. SIMS concentration profiles from crystalline material are presented. The results appear broadly favorable in relation to competitive techniques and will be discussed. It is concluded that doubly charged boron ions are not present in the plume.

  10. Formation of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films in Vacuum Using Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Hanada, Kenji; Yoshida, Tomohiro; Nakagawa, You; Yoshitake, Tsuyoshi

    2010-12-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite films were grown in vacuum using a coaxial arc plasma gun. From the X-ray diffraction measurement, the UNCD crystallite size was estimated to be 1.6 nm. This size is dramatically reduced from that (2.3 nm) of UNCD/hydrogenated amorphous carbon (a-C:H) composite films grown in a hydrogen atmosphere. The sp3/(sp3 + sp2) value, which was estimated from the X-ray photoemission spectrum, was also reduced to be 41%. A reason for it might be the reduction in the UNCD crystallite size. From the near-edge X-ray absorption fine-structure (NEXAFS) spectrum, it was found that the π*C=C and π*C≡C bonds are preferentially formed instead of the σ*C-H bonds in the UNCD/a-C:H films. Since the extremely small UNCD crystallites (1.6 nm) correspond to the nuclei of diamond, we consider that UNCD crystallite formation should be due predominantly to nucleation. The supersaturated condition required for nucleation is expected to be realized in the deposition using the coaxial arc plasma gun.

  11. Development of a gliding arc plasma reactor for CO₂destruction.

    PubMed

    Kim, Seong Cheon; Chun, Young Nam

    2014-01-01

    A gliding arc plasma reactor was designed to destruct carbon dioxide (CO₂), which is a major greenhouse gas. To increase the CO₂destruction rate with a high processing gas volume, an orifice baffle for gathering the gas flow at the centre of the electrodes was installed in the gliding arc plasma reactor. The CO₂inflows with methane (CH₄) and steam (H₂O) improve the CO₂destruction. The parametric studies have been made of the change of CH4 addition, gas injection velocity of the centre nozzle, change of CO₂gas flow rate, and orifice baffle configuration. The produced gases were measured, and the data analysis has been achieved in determining the CO₂destruction rate, CH₄conversion rate, destruction energy efficiency, and selectivity for CO₂and H₂. The highest CO₂ destruction rate for each parameter has been shown as follows: the CH₄/CO₂ratio is 1 as 40%, and the injection gas velocity is 69.5 m/s as 35.7%, the CO₂flow rate is 5 L/min as 42.6%, and the orifice baffle is Type 1, which had the smallest internal area, as 35.7%.

  12. Theoretical and experimental investigations of the coupling of time-dependent parameters in a blown arc plasma torch

    NASA Astrophysics Data System (ADS)

    Rat, V.; Coudert, J. F.

    2016-02-01

    A low-power dc arc torch using nitrogen as plasma-forming gas is studied to highlight the modulation of plasma jet specific enthalpy and speed at the nozzle exit. A special design is used for the torch and by tuning the arc current and the mass flow rate a resonant oscillating mode is obtained in the kHz range, for which the arc voltage presents a periodic triangular waveform, which is the result of the combination of the input parameters. At stabilized current and following the voltage, the electric power is modulated for the specific enthalpy, the mass density and the speed of the plasma at the nozzle exit. A change in the plasma speed is accompanied by a change in the momentum of the jet, which must influence the pressure inside the torch and particularly in the cathode cavity, the volume of which stores the cold gas before it enters the arc region. Even though the torch is fed with a constant flow rate, the arc is subjected to a more or less fluctuating flow rate depending on the cathode cavity volume. The link between the fluctuating components of the different parameters is searched by using a conservation equation and solutions are obtained by means of Fourier analysis. The results obtained are consistent with speed measurements and time-resolved temperature measurements.

  13. Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

    PubMed Central

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

    2012-01-01

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices1-4. Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT 5, narrow the diameter distribution of metallic catalyst particles and carbon nanotubes 6, and change the ratio of metallic and semiconducting carbon nanotubes 7, as well as lead to graphene synthesis 8. Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the arc

  14. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    PubMed

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

    2012-02-02

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the

  15. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    PubMed

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

    2012-01-01

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the

  16. Coalition for Plasma Science (CPS) Education and Outreach Activities

    NASA Astrophysics Data System (ADS)

    Berry, L. A.

    2002-11-01

    The Coalition for Plasma Science (http://plasmacoalition.org/, CPS@plasmacoalition.org) is a group of institutions, organizations, and companies joining forces to increase awareness and understanding of plasma science and its many applications and benefits for society. Ongoing CPS educational activities include: (1) Construction and maintenance of a web site featuring "A Teacher's Guide to Plasma Science on the Web," a page that links to a wide range of plasma-related education sites, most of them analyzed for consistency with national science standards. The web site also directs visitors to our "Plasma Page," a brief, clear summary of plasma-related news; (2) Preparation of two-page articles on a wide range of plasma topics, including lighting, fusion, and space plasmas; and (3) Printing and distribution of an educational brochure entitled "Plasmas are Everywhere." The audience for these activities is primarily nontechnical, and includes students, teachers, and policy makers.

  17. Active control of massively separated high-speed/base flows with electric arc plasma actuators

    NASA Astrophysics Data System (ADS)

    DeBlauw, Bradley G.

    The current project was undertaken to evaluate the effects of electric arc plasma actuators on high-speed separated flows. Two underlying goals motivated these experiments. The first goal was to provide a flow control technique that will result in enhanced flight performance for supersonic vehicles by altering the near-wake characteristics. The second goal was to gain a broader and more sophisticated understanding of these complex, supersonic, massively-separated, compressible, and turbulent flow fields. The attainment of the proposed objectives was facilitated through energy deposition from multiple electric-arc plasma discharges near the base corner separation point. The control authority of electric arc plasma actuators on a supersonic axisymmetric base flow was evaluated for several actuator geometries, frequencies, forcing modes, duty cycles/on-times, and currents. Initially, an electric arc plasma actuator power supply and control system were constructed to generate the arcs. Experiments were performed to evaluate the operational characteristics, electromagnetic emission, and fluidic effect of the actuators in quiescent ambient air. The maximum velocity induced by the arc when formed in a 5 mm x 1.6 mm x 2 mm deep cavity was about 40 m/s. During breakdown, the electromagnetic emission exhibited a rise and fall in intensity over a period of about 340 ns. After breakdown, the emission stabilized to a near-constant distribution. It was also observed that the plasma formed into two different modes: "high-voltage" and "low-voltage". It is believed that the plasma may be switching between an arc discharge and a glow discharge for these different modes. The two types of plasma do not appear to cause substantial differences on the induced fluidic effects of the actuator. In general, the characterization study provided a greater fundamental understanding of the operation of the actuators, as well as data for computational model comparison. Preliminary investigations

  18. NSTX Diagnostics for Fusion Plasma Science Studies

    SciTech Connect

    R. Kaita; D. Johnson; L. Roquemore; M. Bitter; F. Levinton; F. Paoletti; D. Stutman; and the NSTX Team

    2001-07-05

    This paper will discuss how plasma science issues are addressed by the diagnostics for the National Spherical Torus Experiment (NSTX), the newest large-scale machine in the magnetic confinement fusion (MCF) program. The development of new schemes for plasma confinement involves the interplay of experimental results and theoretical interpretations. A fundamental requirement, for example, is a determination of the equilibria for these configurations. For MCF, this is well established in the solutions of the Grad-Shafranov equation. While it is simple to state its basis in the balance between the kinetic and magnetic pressures, what they are as functions of space and time are often not easy to obtain. Quantities like the plasma pressure and current density are not directly measurable. They are derived from data that are themselves complex products of more basic parameters. The same difficulties apply to the understanding of plasma instabilities. Not only are the needs for spatial and temporal resolution more stringent, but the wave parameters which characterize the instabilities are difficult to resolve. We will show how solutions to the problems of diagnostic design on NSTX, and the physics insight the data analysis provides, benefits both NSTX and the broader scientific community.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    SciTech Connect

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

    2015-12-15

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

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

    SciTech Connect

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

    2012-02-15

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

  2. A Desorbed Gas Molecular Ionization Mechanism for Arcing Onset in Solar Arrays Immersed in a Low-Density Plasma

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    Previous experimental studies have hypothesized that the onset of Solar Array Arc (SAA) initiation in low-density space plasmas is caused by a desorbed gas molecular ionization mechanism. Indeed past investigations performed at the NASA Glenn Plasma Interaction Facility tend to not only support the desorbed gas molecular ionization mechanism, but have gone as far as identifying the crucial molecular species that must be present for molecular ion dominated process to occur. When electrical breakdown occurs at a triple junction site on a solar array panel, a quasi-neutral plasma cloud is ejected. Assuming the main component of the expelled plasma cloud by weight is due to water vapor, the fastest process available is due to HO molecules and OH(+) ions, or more succinctly, dissociative molecular-ion dominated recombination processes: H2O(+) + e(-) yields H* + OH*. Recently published spectroscopic observations of solar array arc spectra in ground tests have revealed the well-known molecular OH band (302 to 309nm), as well as the molecular SiH band (387nm peak), and the molecular CH band (432nm peak). Note that the OH band is observed in emission arcs where water vapor is present. Strong atomic lines were also observed for H(sub beta) at 486nm and H(sub alpha) at 656.3nm in prior ground testing. Independent supporting evidence of desorbed gas molecular ionization mechanisms also come from measurements of arc current pulse widths at different capacitances. We will revisit an earlier first order approximation demonstrating the dependence of arc current pulse widths on the square root of the capacitance. The simple arc current pulse width model will be then be used to estimate the temperature of the arc plasma (currently believed to be somewhere in the range of 3 to 5 eV). The current paper then seeks to extend the outlined work by including numerous vacuum chamber measurements obtained with a quadrupole mass spectrometer. A small solar array was mounted inside the vacuum

  3. In situ measurement of the two-dimensional temperature field of a dual-jet direct-current arc plasma

    NASA Astrophysics Data System (ADS)

    Guo, Heng; Li, Peng; Li, He-Ping; Ge, Nan; Bao, Cheng-Yu

    2016-03-01

    In this paper, a real time method for an in situ measurement of the two-dimensional (2-D) temperature filed of thermal plasmas is developed with the combination of the visible image processing technique and the spectroscopic line-ratio method at two specified wavelengths. After the calibration of the gray scale values of the recorded images with the CCD cameras by the emission intensity received using a spectrometer, the 2-D temperature field of the plasma arc-jet can be obtained conveniently based on the derived gray scale values of the CCD images at two specified wavelengths and the formula similar to that of spectroscopic line-ratio method. The experimental results show that the obtained temperature fields of the plasma arc-jet at different times are qualitatively reasonable and consistent with the modeling result. This newly developed method can be employed to measure the transient temperature fields of the plasmas with fluctuations during discharges effectively.

  4. In situ measurement of the two-dimensional temperature field of a dual-jet direct-current arc plasma.

    PubMed

    Guo, Heng; Li, Peng; Li, He-Ping; Ge, Nan; Bao, Cheng-Yu

    2016-03-01

    In this paper, a real time method for an in situ measurement of the two-dimensional (2-D) temperature filed of thermal plasmas is developed with the combination of the visible image processing technique and the spectroscopic line-ratio method at two specified wavelengths. After the calibration of the gray scale values of the recorded images with the CCD cameras by the emission intensity received using a spectrometer, the 2-D temperature field of the plasma arc-jet can be obtained conveniently based on the derived gray scale values of the CCD images at two specified wavelengths and the formula similar to that of spectroscopic line-ratio method. The experimental results show that the obtained temperature fields of the plasma arc-jet at different times are qualitatively reasonable and consistent with the modeling result. This newly developed method can be employed to measure the transient temperature fields of the plasmas with fluctuations during discharges effectively.

  5. Synthesis and characterization of carbon-encapsulated magnetic nanoparticles via arc-plasma assisted CVD

    SciTech Connect

    Li, Z.T.; Hu, C.; Yu, C.; Qiu, J.S.

    2009-12-15

    Carbon-encapsulated magnetic nanoparticles (CEMNs) were fabricated on a large scale by arc-plasma assisted CVD in acetylene. The coal-derived metal-containing (Fe, Co and Ni) carbon rods were used as anodes, while a high-purity graphite rod was used as a cathode that remained unchanged during the arcing process. The CEMNs obtained were characterized by TEM, XRD, Raman spectroscopy, N{sub 2} adsorption isotherms and VSM. The diameter distribution of the obtained CEMNs varies from 10 to 70 nm, of which the metal cores are proximately 5-50 nm. The core phases in Fe ) nanoparticles are body-centered cubic Fe and orthorhombic Fe3C while Co ) nanoparticles and Ni ) nanoparticles show the characteristic of a face-centered cubic structure. The Fe ), Co ) and Ni ) nanoparticles with well-ordered graphitic shells have the surface area of 89 m{sup 2}/g, 72 m{sup 2}/g and 75 m{sup 2}/g, respectively. The CEMNs show ferromagnetic of which was characterized by a ratio of remnant magnetization (MR) to saturation magnetization (MS).

  6. On characterisation of wire-arc-plasma-sprayed Ni on alumina substrate

    SciTech Connect

    Laik, A.; Chakravarthy, D.P.; Kale, G.B. . E-mail: gbkale@apsara.barc.ernet.in

    2005-08-15

    A study was carried out on metal-ceramic bonding produced by the technique of wire-arc-plasma spraying of Ni on Al{sub 2}O{sub 3} substrate. The Ni layer and the Ni/Al{sub 2}O{sub 3} interface were characterised using optical and electro-optic techniques. The plasma-deposited Ni layer shows a uniform lamellar microstructure throughout the cross-section. The metal-ceramic interface was found to be well bonded with no pores, flaws or cracks in the as-sprayed condition. The optical metallography and concentration profiles established with the help of an electron probe microanalyser confirmed the absence of any intermediate phase at the interface. An annealing treatment at 1273 K for 24 h on the plasma-coated samples did not result in formation of any intermetallic compound or spinel at the Ni/Al{sub 2}O{sub 3} interface. This indicates that the oxygen picked up by Ni during the spraying operation is less than the threshold value required to form the spinel NiAl{sub 2}O{sub 4}.

  7. Laser Doppler velocity measurements in a transferred-arc plasma torch

    SciTech Connect

    Norton, O.P.; Okhuysen, W.P.

    1995-12-31

    Laser Doppler velocimetry (LDV) is a nonintrusive method of measuring velocity. The measurement volume formed by the intersection of the two laser beams is compact, thus the method provides excellent spatial resolution. Furthermore, aside from the requirement that the flow contain scattering particles, the method is nonintrusive. Thus, no probe disturbs the flow and measurements can be made in extremely high temperature and hostile environments. Here, the LDV technique has been used to map the velocity field in the plasma jet issuing from a transferred-arc, reverse polarity plasma torch. This gas flow field is important in understanding the physics of the plasma torch. The torch was operated with nitrogen at a fixed distance of 5 inches from the graphite billet. Velocity measurements were made for combinations of current at 125 and 175 A and pressure at 22 and 55 psig. Results are presented for the high current/high pressure condition. Since the test procedure involves reestablishing the same flow conditions after swapping graphite billets, it is instructive to see how closely the torch operating variables were reproduced. The average current varied from 175.2 to 175.8 A over the eight separate time periods. The nitrogen supply pressure varied from 52.5 to 53.9 psi. The torch voltage drop ranged from 430.6 to 436.1 V, and the nitrogen flow rate from 4.8 to 5.4 scfm.

  8. Ion velocities in direct current arc plasma generated from compound cathodes

    SciTech Connect

    Zhirkov, I.; Rosen, J.; Eriksson, A. O.

    2013-12-07

    Arc plasma from Ti-C, Ti-Al, and Ti-Si cathodes was characterized with respect to charge-state-resolved ion energy. The evaluated peak velocities of different ion species in plasma generated from a compound cathode were found to be equal and independent on ion mass. Therefore, measured difference in kinetic energies can be inferred from the difference in ion mass, with no dependence on ion charge state. The latter is consistent with previous work. These findings can be explained by plasma quasineutrality, ion acceleration by pressure gradients, and electron-ion coupling. Increasing the C concentration in Ti-C cathodes resulted in increasing average and peak ion energies for all ion species. This effect can be explained by the “cohesive energy rule,” where material and phases of higher cohesive energy generally result in increasing energies (velocities). This is also consistent with the here obtained peak velocities around 1.37, 1.42, and 1.55 (10{sup 4} m/s) for ions from Ti{sub 0.84}Al{sub 0.16}, Ti{sub 0.90}Si{sub 0.10}, and Ti{sub 0.90}C{sub 0.10} cathodes, respectively.

  9. The effect of impurity gasses on variable polarity plasma arc welded 2219 aluminum

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Variable polarity plasma arc (VPPA) welding has been used with considerable success by NASA for the welds on the Space Shuttle External Tank as well as by others concerned with high quality welded structures. The effects of gaseous contaminants on the appearance of VPPA welds on 2219 aluminum are examined so that a welder can recognize that such contamination is present and take corrective measures. There are many possible sources of such contamination including, contaminated gas bottles, leaks in the gas plumbing, inadequate shield gas flow, condensed moisture in the gas lines or torch body, or excessive contaminants on the workpiece. The gasses chosen for study in the program were nitrogen, oxygen, methane, and hydrogen. Welds were made in a carefully controlled environment and comparisons were made between welds with various levels of these contaminants and welds made with research purity (99.9999 percent) gasses. Photographs of the weld front and backside as well as polished and etched cross sections are presented.

  10. Magnetorheology of colloidal dispersion containing Fe nanoparticles synthesized by the arc-plasma method

    NASA Astrophysics Data System (ADS)

    Noma, Junichi; Abe, Hiroya; Kikuchi, Takehito; Furusho, Junji; Naito, Makio

    2010-07-01

    Spherical crystalline Fe nanoparticles, ˜100 nm in diameter, were synthesized under Ar-50% H 2 arc-plasma. These nanoparticles were dispersed in silicone oil after silane treatment on as-grown thin oxide layer (˜2 nm) to make their surfaces hydrophobic. The resulting Fe nanoparticles exhibited a high saturation magnetization of ˜190 emu/g at room temperature. The static magnetorheological behavior was measured for the colloidal dispersion (solid concentration: 15 vol%) at room temperature under magnetic flux densities of 0-0.3 T, using a parallel-plate-type commercial rheometer. The yield stress continuously increased with magnetic flux density, demonstrating the Bingham plastic behavior. Moreover, subjecting the sample to a magnetic flux density of 0.3 T increased the yield stress by ˜10 2. Additionally, the colloidal dispersion exhibited good stability against sedimentation.

  11. A Radiative Transport Model for Heating Paints using High Density Plasma Arc Lamps

    SciTech Connect

    Sabau, Adrian S; Duty, Chad E; Dinwiddie, Ralph Barton; Nichols, Mark; Blue, Craig A; Ott, Ronald D

    2009-01-01

    The energy distribution and ensuing temperature evolution within paint-like systems under the influence of infrared radiation was studied. Thermal radiation effects as well as those due to heat conduction were considered. A complete set of material properties was derived and discussed. Infrared measurements were conducted to obtain experimental data for the temperature in the paint film. The heat flux of the incident radiation from the plasma arc lamp was measured using a heat flux sensor with a very short response time. The comparison between the computed and experimental results for temperature show that the models that are based on spectral four-flux RTE and accurate optical properties yield accurate results for the black paint systems.

  12. Performance of coated columbium and tantalum alloys in plasma arc reentry simulation tests

    NASA Technical Reports Server (NTRS)

    Levine, S. R.; Merutka, J. P.

    1974-01-01

    The evaluation of coated refractory metals screened in stagnation model plasma arc tests is reported. Columbium alloys FS-85, C-129Y, and Cb-752 coated with Si-20Cr-20Fe (R512E) were tested at 1390 C. Three silicide coatings on Ta-10W were tested at 1470 C. Half-hour cycles and a 6500 N/sqm stagnation pressure were used. The best R512E coated columbium alloy was FS-85 with first local coating breakdowns occurring in 12 to 50 cycles. At coating defects, low metal recession rates (0.005 mm/min) were generally observed on coated columbium alloys while high rates (0.15 mm/min) were observed on coated Ta-10W. Coated columbium suffered large emittance losses (to below 0.7) due to surface refractory metal pentoxide formation.

  13. THERMAL ANNEALING OF ZNO FILMS USING HIGH-DENSITY PLASMA ARC LAMPS

    SciTech Connect

    Sabau, Adrian S; Dinwiddie, Ralph Barton; Xu, Jun; Angelini, Joseph Attilio; Harper, David C

    2011-01-01

    Nanostructured materials are rarely synthesized with appropriate phase and/or morphology. In this study, critical additional of as-synthesized nanostructured materials, such as annealing and/or activation of dopants, are addressed using infrared plasma arc lamps (PAL) over areas as large as 1,000 cm2. The broad spectral range of the PAL and the spectral variation of light absorption in nanostructured materials make the selection of processing parameters extremely difficult, posing a major technological barrier. In this study, the measurement of the surface temperature using various techniques for ZnO films on crystalline silicon wafers is discussed. An energy transport model for the simulation of rapid thermal processing using PAL is presented. The experimental and computational results show that the surface temperature cannot be measured directly and that computer simulation results are an effective tool for obtaining accurate data on processing temperatures.

  14. Study of Earth and Jupiter-like plasmas for atmospheric entries using a non-transferred arc torch

    NASA Astrophysics Data System (ADS)

    Menecier, S.; Gouy, P. A.; Duffour, E.; Perisse, F.; Vacher, D.; Cerqueira, N.; Dudeck, M.; Reynier, Ph; Marraffa, L.

    2015-08-01

    This paper presents the results obtained by a 100 kW non-transferred arc plasma torch dedicated to the studies of plasmas characteristics of atmospheric entries of spatial probes, especially Earth and Jupiter entries. Spectra acquisition of the produced plasmas is achieved using optical emission spectroscopy. For Earth entry conditions, air plasma was obtained with a maximal temperature around 6800 K with a good agreement using atomic lines of oxygen and nitrogen (and also copper coming from electrode’s ablation) and molecular bands of N2, CN and \\text{N}2+ , testifying to a good thermal equilibrium. As the first step in the study of Jupiter atmospheric entry, pure helium plasma was produced with the same maximal temperature of about 7500 K. Helium plasma was achieved for the first time using the plasma torch. Recorded spectra show a continuum, He I lines as well as copper. He II lines are not detected.

  15. Shear-flow excitation mechanisms of recessed localized arc-filament plasma actuators

    NASA Astrophysics Data System (ADS)

    Kleinman, R. R.; Bodony, D. J.; Freund, J. B.

    2010-11-01

    Localized arc-filament plasma actuators, placed near the nozzle lip of a laboratory jet, have recently been demonstrated to have sufficient control authority to significantly excite the jet downstream [M. Samimy et al., J. Fluid Mech. 578, 305 (2007)]. This class of plasma actuator, which in this application is recessed in a small cavity near the nozzle lip, causes intense local heating. This heating is thought to be the root mechanism of its influence on the flow, but how this principally entropic thermal source couples with the vortical jet shear layer turbulence downstream is unclear. We investigate this using direct numerical simulations, which match the flow conditions of the corresponding experiment, including Reynolds number, but are two-dimensional to ease computational expense. Despite this obvious modeling approximation, the simulations include the key features of the laboratory system: a thin boundary layer, a plasma-like thermal source in a small recessed cavity, a nozzle lip, and a downstream free shear layer. Results are shown to match the temperature and near-field pressure measured in the laboratory actuators. It is found that the cavity, which was initially included to shield the actuator plasma from the flow, is essential for its action. Thermal expansion within the cavity leads to an ejection of fluid from it, which perturbs the boundary layer and the downstream mixing layer. There is a finite baroclinic torque, but its effects are relatively minor. An alternate actuator designed to mimic the pressure effects of the full actuator, without its concomitant thermal heating, is nearly as effective at exciting the shear layer. An actuator model without the cavity recess does not provide effective actuation. These results suggest that there is significant potential to optimize the actuation authority through design of cavity recesses that augment its effect.

  16. Effect of Ti-Al cathode composition on plasma generation and plasma transport in direct current vacuum arc

    SciTech Connect

    Zhirkov, I. Petruhins, A.; Dahlqvist, M.; Ingason, A. S.; Rosen, J.; Eriksson, A. O.

    2014-03-28

    DC arc plasma from Ti, Al, and Ti{sub 1-x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes was characterized with respect to plasma chemistry and charge-state-resolved ion energy. Scanning electron microscopy, X-ray diffraction, and Energy-dispersive X-ray spectroscopy of the deposited films and the cathode surfaces were used for exploring the correlation between cathode-, plasma-, and film composition. Experimental work was performed at a base pressure of 10{sup −6} Torr, to exclude plasma-gas interaction. The plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. This may be explained by presence of neutrals in the plasma/vapour phase. The average ion charge states (Ti = 2.2, Al = 1.65) were consistent with reference data for elemental cathodes, and approximately independent on the cathode composition. On the contrary, the width of the ion energy distributions (IEDs) were drastically reduced when comparing the elemental Ti and Al cathodes with Ti{sub 0.5}Al{sub 0.5}, going from ∼150 and ∼175 eV to ∼100 and ∼75 eV for Ti and Al ions, respectively. This may be explained by a reduction in electron temperature, commonly associated with the high energy tail of the IED. The average Ti and Al ion energies ranged between ∼50 and ∼61 eV, and ∼30 and ∼50 eV, respectively, for different cathode compositions. The attained energy trends were explained by the velocity rule for compound cathodes, which states that the most likely velocities of ions of different mass are equal. Hence, compared to elemental cathodes, the faster Al ions will be decelerated, and the slower Ti ions will be accelerated when originating from compound cathodes. The intensity of the macroparticle generation and thickness of the deposited films were also found to be dependent on the cathode composition. The presented results

  17. REVIEW ARTICLE: Modelling of thermal plasmas for arc welding: the role of the shielding gas properties and of metal vapour

    NASA Astrophysics Data System (ADS)

    Murphy, A. B.; Tanaka, M.; Yamamoto, K.; Tashiro, S.; Sato, T.; Lowke, J. J.

    2009-10-01

    The methods used to model thermal plasmas, including treatments of diffusion in arcs in gas mixtures, are reviewed. The influence of thermophysical properties on the parameters of tungsten-inert-gas (TIG) welding arcs, particularly those that affect the weld pool, is investigated using a two-dimensional model in which the arc, anode and cathode are included self-consistently. The effect of changing each of six thermophysical properties on the characteristics of an argon TIG arc is assessed. The influence of the product of specific heat and mass density is found to be particularly important in determining the arc constriction. By examining the influence of the different properties on the heat flux density, current density and shear stress at the anode, it is concluded that the weld pool depth can be increased by using shielding gases with high specific heat, thermal conductivity and viscosity. The effect of metal vapour on the arc and weld pool properties is assessed. The most important effect of the metal vapour is found to be the increased electrical conductivity at low temperatures, which leads to lower heat flux density and current density at the weld pool, implying a shallower weld pool.

  18. Micro-Plasma Transferred Arc Additive Manufacturing for Die and Mold Surface Remanufacturing

    NASA Astrophysics Data System (ADS)

    Jhavar, Suyog; Paul, Christ Prakash; Jain, Neelesh Kumar

    2016-07-01

    Micro-plasma transferred arc ( µPTA) additive manufacturing is one of the newest options for remanufacturing of dies and molds surfaces in the near-millimeter range leading to extended usage of the same. We deployed an automatic micro-plasma deposition setup to deposit a wire of 300 µm of AISI P20 tool steel on the substrate of same material for the potential application in remanufacturing of the die and mold surface. Our present research effort is to establish µPTA additive manufacturing as a viable economical and cleaner methodology for potential industrial applications. We undertook the optimization of single weld bead geometry as the first step in our present study. Bead-on-plate trials were conducted to deposit single bead geometry at various processing parameters. The bead geometry (shape and size) and dilution were measured and the parametric dependence was derived. A set of parameters leading to reproducible regular and smooth single bead geometry were identified and used to prepare a thin wall for mechanical testing. The deposits were subjected to material characterization such as microscopic studies, micro-hardness measurements and tensile testing. The process was compared qualitatively with other deposition processes involving high-energy density beams and was found to be advantageous in terms of low initial and running costs with comparable properties. The outcome of the study confirmed the process capability of µPTA deposition leading to deployment of cost-effective and environmentally friendlier technology for die and mold remanufacturing.

  19. Experimental investigation of supersonic low pressure air plasma flows obtained with different arc-jet operating conditions

    NASA Astrophysics Data System (ADS)

    Lago, Viviana; Ndiaye, Abdoul-Aziz

    2012-11-01

    A stationary arc-jet plasma flow at low pressure is used to simulate some properties of the gas flow surrounding a vehicle during its entry into celestial body's atmospheres. This paper presents an experimental study concerning plasmas simulating a re-entry into our planet. Optical measurements have been carried out for several operating plasma conditions in the free stream, and in the shock layer formed in front of a flat cylindrical plate, placed in the plasma jet. The analysis of the spectral radiation enabled the identification of the emitting species, the determination of the rotational and vibrational temperatures in the free-stream and in the shock layer and the determination of the distance of the shock to the flat plate face. Some plasma fluid parameters like, stagnation pressure, specific enthalpy and heat flux have been determined experimentally along the plasma-jet axis.

  20. Experimental investigation of supersonic low pressure air plasma flows obtained with different arc-jet operating conditions

    SciTech Connect

    Lago, Viviana; Ndiaye, Abdoul-Aziz

    2012-11-27

    A stationary arc-jet plasma flow at low pressure is used to simulate some properties of the gas flow surrounding a vehicle during its entry into celestial body's atmospheres. This paper presents an experimental study concerning plasmas simulating a re-entry into our planet. Optical measurements have been carried out for several operating plasma conditions in the free stream, and in the shock layer formed in front of a flat cylindrical plate, placed in the plasma jet. The analysis of the spectral radiation enabled the identification of the emitting species, the determination of the rotational and vibrational temperatures in the free-stream and in the shock layer and the determination of the distance of the shock to the flat plate face. Some plasma fluid parameters like, stagnation pressure, specific enthalpy and heat flux have been determined experimentally along the plasma-jet axis.

  1. High photoelectron emission from Co-diffused MgO deposited using arc plasma gun

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shin-ichi; Kosuga, Hiroki

    2015-08-01

    MgO has several advantageous characteristics and has been applied in various fields. In this study, we deposited Co nanoparticles in an island pattern on a Si substrate using an arc plasma gun (APG). We subsequently formed a MgO thin film on this substrate by metal-organic decomposition (MOD), which enables the formation of films in the atmosphere, thereby yielding a double-layer structure. The MgO thin film formed on Co nanoparticles deposited using the APG with 500 pulses of arc discharge exhibited improved crystallinity and photoelectron emission at least threefold higher than that of a MgO thin film formed directly without depositing Co nanoparticles. Although the transmittance of the specimen formed by depositing Co nanoparticles was initially 30% or lower, it increased to greater than 90% after the formation of the MgO thin film and the dispersion of the Co nanoparticles in the MgO thin film during heat treatment at 900 °C. Our results clarify that the characteristics of MgO thin films are markedly improved by depositing Co nanoparticles before forming the films. The results of Kelvin probe force microscopy (KPFM) indicate that the outermost surface of the Co material had become CoO (cobalt oxide) with the dispersion of Co nanoparticles in the MgO thin film. The lattice parameter of CoO nanoparticles (an-axis lattice parameter of 4.2615 Å) after heating matches well with that of MgO (4.2126 Å). The MgO thin films that grew in conjunction with the CoO nanoparticles were highly crystallized. We successfully established a high-performance, cost-effective bottom-up process that requires no ion injection by dispersing Co nanoparticles in a MgO thin film through heat treatment.

  2. Examination of the physical processes associated with the keyhole region of variable polarity plasma arc welds in aluminum alloy 2219

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.

    1987-01-01

    The morphology and properties of the Variable Polarity Plasma Arc (VPPA) weld composite zone are intimately related to the physical processes associated with the keyhole. This study examined the effects of oxide, halide, and sulfate additions to the weld plate on the keyhole and the weld pool. Changes in both the arc plasma character and the bead morphology were correlated to the chemical environment of the weld. Pool behavior was observed by adding flow markers to actual VPPA welds. A low temperature analog to the welding process was developed. The results of the study indicate that oxygen, even at low partial pressures, can disrupt the stable keyhole and weld pool. The results also indicate that the Marangoni surface tension driven flows dominate the weld pool over the range of welding currents studied.

  3. Town Meeting on Plasma Physics at the National Science Foundation

    NASA Astrophysics Data System (ADS)

    2015-11-01

    We invite you to the Town Meeting on the role of the National Science Foundation (NSF) in supporting basic and applied research in Plasma Physics in the U.S. The overarching goal of NSF is to promote the progress of science and to enable training of the next generation of scientists and engineers at US colleges and universities. In this context, the role of the NSF Physics Division in leading the nearly 20 year old NSF/DOE Partnership in Basic Plasma Science and Engineering serves as an example of the long history of NSF support for basic plasma physics research. Yet, the NSF interest in maintaining a healthy university research base in plasma sciences extends across the Foundation. A total of five NSF Divisions are participating in the most recent Partnership solicitation, and a host of other multi-disciplinary and core programs provide opportunities for scientists to perform research on applications of plasma physics to Space & Solar Physics, Astrophysics, Accelerator Science, Material Science, Plasma Medicine, and many sub-disciplines within Engineering. This Town Meeting will provide a chance to discuss the full range of relevant NSF funding opportunities, and to begin a conversation on the present and future role of NSF in stewarding basic plasma science and engineering research at US colleges and universities. We would like to particularly encourage early career scientists and graduate students to participate in this Town Meeting, though everyone is invited to join what we hope to be a lively discussion.

  4. Diagnostics for a waste processing plasma arc furnace (invited) (abstract)a)

    NASA Astrophysics Data System (ADS)

    Woskov, P. P.

    1995-01-01

    Maintaining the quality of our environment has become an important goal of society. As part of this goal new technologies are being sought to clean up hazardous waste sites and to treat ongoing waste streams. A 1 MW pilot scale dc graphite electrode plasma arc furnace (Mark II) has been constructed at MIT under a joint program among Pacific Northwest Laboratory (PNL), MIT, and Electro-Pyrolysis, Inc. (EPI)c) for the remediation of buried wastes in the DOE complex. A key part of this program is the development of new and improved diagnostics to study, monitor, and control the entire waste remediation process for the optimization of this technology and to safeguard the environment. Continuous, real time diagnostics are needed for a variety of the waste process parameters. These parameters include internal furnace temperatures, slag fill levels, trace metals content in the off-gas stream, off-gas molecular content, feed and slag characterization, and off-gas particulate size, density, and velocity distributions. Diagnostics are currently being tested at MIT for the first three parameters. An active millimeter-wave radiometer with a novel, rotatable graphite waveguide/mirror antenna system has been implemented on Mark II for the measurement of surface emission and emissivity which can be used to determine internal furnace temperatures and fill levels. A microwave torch plasma is being evaluated for use as a excitation source in the furnace off-gas stream for continuous atomic emission spectroscopy of trace metals. These diagnostics should find applicability not only to waste remediation, but also to other high temperature processes such as incinerators, power plants, and steel plants.

  5. Determination of Nickel, Vanadium and Iron in Crude Oil by Three-Phase Plasma Arc Spectrometry

    NASA Astrophysics Data System (ADS)

    Ghatass, Zekry F.

    2002-12-01

    Three-phase plasma arc (TPPA) with ultrasonic nebulizer is developed for simultaneous determination of trace elements in crude oil samples. Ultrasonic nebulizer is used instead of pneumatic nebulizer in order to minimize the problems caused by the oil viscosity during the operation. This system was used for determination of some trace elements (V, Ni, and Fe) in a crude oil samples. Methyl isobutyl ketone (MIBK) was used to dilute the oil samples. The TPPA instrument offers several advantages including a low cost power supply with no radio frequency, linear dynamic ranges from 4 to 5 of orders of magnitude, and detection limits (0.121, 0.313 and 0.242 (μg/ml) for Ni, V and Fe respectively. The average concentrations were 31 ± 0.45 (μg/ml) for Ni, 40 ± 0.88 (μg/ml) for V and 8 ± 0.74 (μg/ml) for Fe at Balaaiem fields and 2 ± 0.05 (μg/ml) for Ni, 4.8 ± 0.25 (μg/ml) for V and 2 ± 0.10 (μg/ml) for Fe at Wastern Desert fields.

  6. Multi-Scale-Structured Composite Coatings by Plasma-Transferred Arc for Nuclear Applications

    NASA Astrophysics Data System (ADS)

    Werry, A.; Chazelas, C.; Denoirjean, A.; Valette, S.; Vardelle, A.; Meillot, E.

    2016-01-01

    In nuclear plants, the replacement of hardfacing Stellite, a cobalt-based alloy, on parts of the piping system in connection with the reactor has been investigated since the late 60's. Various Fe-based or Ni-based alloys, Co-free or with a low content of Co, have been developed but with mechanical properties generally lower than that of Stellites. The 4th generation nuclear plants impose additional or more stringent requirements for hardfacing materials. Plasma-transferred arc (PTA) coatings of cobalt-free nickel-based alloys with the addition of sub-micrometric or micrometric alumina particles are thought to be a potential solution for tribological applications in the primary system of sodium-cooled fast reactors. In this study, PTA coatings of nickel-based alloys reinforced with alumina particles were deposited on 316L stainless steel substrates. Under the conditions of this study, the addition of alumina particles resulted in a refinement of coating microstructure and the improvement of their resistance to abrasive wear. However, it does not bring about any change in coating micro-hardness.

  7. Thermal annealing of FePt thin films by millisecond plasma arc pulses

    NASA Astrophysics Data System (ADS)

    Inaba, Yuki; Torres, Karen L.; Cole, Amanda; Vanfleet, Richard; Ott, Ronald; Klemmer, Tim; Harrell, J. W.; Thompson, Gregory B.

    2009-08-01

    A series of 20 and 100 nm Fe 53Pt 47 thin films sputter-deposited onto Si substrates have been thermally annealed using a pulsed thermal plasma arc lamp. A series of one, three or five pulses were applied to the thin films with widths of either 50 or 100 ms. The microstructure and magnetic properties of these annealed Fe 53Pt 47 films are discussed according to the various annealing conditions and A1 to L1 0 phase transformation. Upon pulse annealing, the average in-plane grain size of 15 nm (nearly equivalent for both film thicknesses) was observed to increase to values near 20 nm. In general, increasing the pulse width or number of pulses increased the L1 0 order parameter, tetragonality of the c/a ratio and coercivity of the specimen. The exception to this trend was for five pulses at 100 ms for both film thicknesses, which indicated a reduction of the order parameter and coercivity. This reduction is believed to be a result of the interdiffusion of Fe and Pt into the Si substrate and the formation of iron oxide clusters in the grain boundaries characterized by atom probe tomography.

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

    PubMed

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

    2015-01-01

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

  9. Gas Sensors Based on Tin Oxide Nanoparticles Synthesized from a Mini-Arc Plasma Source

    DOE PAGESBeta

    Lu, Ganhua; Huebner, Kyle L.; Ocola, Leonidas E.; Gajdardziska-Josifovska, Marija; Chen, Junhong

    2006-01-01

    Minimore » aturized gas sensors or electronic noses to rapidly detect and differentiate trace amount of chemical agents are extremely attractive. In this paper, we report on the fabrication and characterization of a functional tin oxide nanoparticle gas sensor. Tin oxide nanoparticles are first synthesized using a convenient and low-cost mini-arc plasma source. The nanoparticle size distribution is measured online using a scanning electrical mobility spectrometer (SEMS). The product nanoparticles are analyzed ex-situ by high resolution transmission electron microscopy (HRTEM) for morphology and defects, energy dispersive X-ray (EDX) spectroscopy for elemental composition, electron diffraction for crystal structure, and X-ray photoelectron spectroscopy (XPS) for surface composition. Nonagglomerated rutile tin oxide ( SnO 2 ) nanoparticles as small as a few nm have been produced. Larger particles bear a core-shell structure with a metallic core and an oxide shell. The nanoparticles are then assembled onto an e-beam lithographically patterned interdigitated electrode using electrostatic force to fabricate the gas sensor. The nanoparticle sensor exhibits a fast response and a good sensitivity when exposed to 100 ppm ethanol vapor in air.« less

  10. Preparation and characterization of carbon nanofluid by a plasma arc nanoparticles synthesis system

    PubMed Central

    2011-01-01

    Heat dissipation from electrical appliances is a significant issue with contemporary electrical devices. One factor in the improvement of heat dissipation is the heat transfer performance of the working fluid. In this study, we used plasma arc technology to produce a nanofluid of carbon nanoparticles dispersed in distilled water. In a one-step synthesis, carbon was simultaneously heated and vaporized in the chamber, the carbon vapor and particles were then carried to a collector, where cooling furnished the desired carbon/water nanofluid. The particle size and shape were determined using the light-scattering size analyzer, SEM, and TEM. Crystal morphology was examined by XRD. Finally, the characterization include thermal conductivity, viscosity, density and electric conductivity were evaluated by suitable instruments under different temperatures. The thermal conductivity of carbon/water nanofluid increased by about 25% at 50°C compared to distilled water. The experimental results demonstrated excellent thermal conductivity and feasibility for manufacturing of carbon/water nanofluids. PMID:21711828

  11. LES of a Jet Excited by the Localized Arc Filament Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Brown, Clifford A.

    2011-01-01

    The fluid dynamics of a high-speed jet are governed by the instability waves that form in the free-shear boundary layer of the jet. Jet excitation manipulates the growth and saturation of particular instability waves to control the unsteady flow structures that characterize the energy cascade in the jet.The results may include jet noise mitigation or a reduction in the infrared signature of the jet. The Localized Arc Filament Plasma Actuators (LAFPA) have demonstrated the ability to excite a high-speed jets in laboratory experiments. Extending and optimizing this excitation technology, however, is a complex process that will require many tests and trials. Computational simulations can play an important role in understanding and optimizing this actuator technology for real-world applications. Previous research has focused on developing a suitable actuator model and coupling it with the appropriate computational fluid dynamics (CFD) methods using two-dimensional spatial flow approximations. This work is now extended to three-dimensions (3-D) in space. The actuator model is adapted to a series of discrete actuators and a 3-D LES simulation of an excited jet is run. The results are used to study the fluid dynamics near the actuator and in the jet plume.

  12. Thermal annealing of FePt thin films by millisecond plasma arc pulses

    SciTech Connect

    Inaba, Yuki; Torres, Karen; Cole, Amanda; Ott, Ronald D; Klemmer, Timothy; Harrell, J W; Thompson, Gregory

    2009-01-01

    A series of 20 and 100 nm Fe{sub 53}Pt{sub 47} thin films sputter-deposited onto Si substrates have been thermally annealed using a pulsed thermal plasma arc lamp. A series of one, three or five pulses were applied to the thin films with widths of either 50 or 100 ms. The microstructure and magnetic properties of these annealed Fe{sub 53}Pt{sub 47} films are discussed according to the various annealing conditions and A1 to L1{sub 0} phase transformation. Upon pulse annealing, the average in-plane grain size of 15 nm (nearly equivalent for both film thicknesses) was observed to increase to values near 20 nm. In general, increasing the pulse width or number of pulses increased the L1{sub 0} order parameter, tetragonality of the c/a ratio and coercivity of the specimen. The exception to this trend was for five pulses at 100 ms for both film thicknesses, which indicated a reduction of the order parameter and coercivity. This reduction is believed to be a result of the interdiffusion of Fe and Pt into the Si substrate and the formation of iron oxide clusters in the grain boundaries characterized by atom probe tomography.

  13. Performance of an ablator for Space Shuttle inorbit repair in an arc-plasma airstream

    NASA Technical Reports Server (NTRS)

    Stewart, D. A.; Cuellar, M.; Flowers, O.

    1983-01-01

    An ablator patch material performed well in an arc plasma environment simulating nominal Earth entry conditions for the Space Shuttle. Ablation tests using vacuum molded cones provided data to optimize the formulation of a two part polymer system for application under space conditions. The blunt cones were made using a Teflon mold and a state of the art caulking gun. Char stability of formulations with various amounts of catalyst and diluent were investigated. The char was found to be unstable in formulations with low amounts of catalyst and high amounts of diluent. The best polymer system determined by these tests was evaluated using a half tile patch in a multiple High Temperature Reusable surface Insulation tile model. It was demonstrated that this ablator could be applied in a space environment using a state of the art caulking gun, would maintain the outer mold line of the thermal protection system during entry, and would keep the bond line temperature at the aluminum tile interface below the design limit.

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

    PubMed Central

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

    2015-01-01

    Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing bio-mimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications. PMID:26677327

  15. Structure and Magnetic Properties of Carbon-Encapsulated fe Nanoparticles Obtained by a Modified Arc Plasma Method

    NASA Astrophysics Data System (ADS)

    Wang, Guizhen; Wan, Gengping; Hao, Chuncheng

    Carbon-encapsulated Fe nanoparticles were synthesized by a modified arc plasma method using methane and starch as carbon sources, respectively. The particles were characterized in detail by transmission electron microscope and X-ray powder diffraction. They are somewhat spherical in shape and the coating layers of the two sample types are composed of amorphous carbon. Magnetic measurements using a vibrating sample magnetometer demonstrate that the prepared composites have different magnetic properties.

  16. Numerical simulation of a cascaded arc source with different Ar-H2 mixtures of nonlocal thermal equilibrium plasmas

    NASA Astrophysics Data System (ADS)

    Ahmad, Zahoor

    2009-08-01

    Cascaded arc of Pilot-PSI is modeled using numerical simulation code PLASIMO [G. M. Janssen, Ph.D. thesis, Eindhoven University of Technology (2000), http://plasimo.phys.tue.nl]. Pilot-PSI is a linear device used to produce a high density plasma column for the study of plasma surface interaction processes. In this modeling effort nonlocal thermal equilibrium plasma of Ar-H2 mixture is used. The purpose of these simulations is to optimize the cascaded arc for a higher yield of H+ ions and to investigate the role of Ar-H2 mixture ratios. The associative charge exchange reaction followed by dissociative recombination plays a very important role in the dissociation of H2 molecules and as a consequence the yield of H+ increases and of Ar+ decreases. The Ar+ density also decreases in the arc when H2 concentration is increased beyond certain value. With a mixture of 2.5 standard liters per minute Ar and 0.5 SLM H2 the H+ ion flux exceeds the flux obtained in pure H2 gas, at a reduced expenditure of energy per ion.

  17. Investigation in the use of plasma arc welding and alternative feedstock delivery method in additive manufacture

    NASA Astrophysics Data System (ADS)

    Alhuzaim, Abdullah F.

    The work conducted for this thesis was to investigate the use of plasma arc welding (PAW) and steel shot as a means of additive manufacturing. A robotic PAW system and automatic shot feeder were used to manufacture linear walls approximately 100 mm long by 7 mm wide and 20 mm tall. The walls were built, layer-by-layer, on plain carbon steel substrate by adding individual 2.5 mm diameter plain carbon steel shot. Each layer was built, shot-by-shot, using a pulse of arc current to form a molten pool on the deposit into which each shot was deposited and melted. The deposition rate, a measure of productivity, was approximately 50 g/hour. Three walls were built using the same conditions except for the deposit preheat temperature prior to adding each new layer. The deposit preheat temperature was controlled by allowing the deposit to cool after each layer for an amount of time called the inter-layer wait time. The walls were sectioned and grain size and hardness distribution were measured as a function of wall height. The results indicated that, for all specimens, deposit grain size increased and hardness decreased as wall height increased. Furthermore, average grain size decreased and hardness increased as interlayer wait time increased. An analytical heat flow model was developed to study the influence of interlayer wait time on deposit temperature and therefore grain size and hardness. The results of the model indicated that as wall height increased, the rate of deposit heat removal by conduction to the substrate decreased leading to a higher preheat temperature after a fixed interlayer wait time causing grain size to increase as wall height increased. However, the model results also show that as wall height increased, the deposit surface area from which heat energy is lost via convection and radiation increased. The model also demonstrated that the use of a means of forced convection to rapidly remove heat from the deposit could be an effective way to boost

  18. Electric Plasma Arc-Lamp Combustor Liner Durability Test System Developed

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.; Halbig, Michael C.

    2000-01-01

    Silicon carbide matrix composites are candidate materials for high-temperature combustor liners. Because through-the-thickness thermal gradients are the primary cause of stress on combustor liners, a unique test facility was developed at the NASA Glenn Research Center at Lewis Field to simulate in-service pure thermal stress distributions in fiber reinforced silicon carbide cylinders. It was developed initially under Phase II of the High- Speed Research Program. This test stand can accommodate 8-in.-long test cylinders that have outer diameters of 4 in. and a wall thickness of about 0.08 to 0.12 in. One cylinder at a time is loaded vertically into the test stand. Water-cooled plates enclose the open ends of the cylinder and provide cooling. Load plates on the exterior side of the water-cooled plates provide support and compression loads. To evaluate a combustor liner material s potential performance, researchers induce thermal gradients with an axisymmetric, direct-current, electric arc within the cylinder while refrigerated air at a rate of 1.5 lb/sec impinges on the outside surface of the cylinder. The achievable through-the-thickness thermal gradient is predicted to be in excess of 200 C. The 8-in. long, 0.5-in.-diameter plasma arc emits full spectrum visible light; radiant intensity exceeds 300 Watts per square centimeters to produce temperatures in excess of 1500 C on materials with emissivity near unity. Because the system does not rely upon the combustion of fuels to achieve the related thermal conditions, ancillary environmental reactions with the sample are eliminated. The system incorporates a standard mechanical test frame, which can impose constant as well cyclical axial stresses up to 2200 lb upon the test piece. Silicon-carbide-fiber reinforced silicon carbide matrix composite cylinders were instrumented with thin-film thermocouples to obtain through-the-thickness thermal flux measurements. Inside wall temperatures reached 1200 C with only 250 A of

  19. PREFACE: 23rd National Symposium on Plasma Science & Technology (PLASMA-2008)

    NASA Astrophysics Data System (ADS)

    Mago, V. K.; Ananthapadmanabhan, P. V.; Patil, D. S.; Das, A. K.

    2010-01-01

    It is our pleasure to present the proceedings of the 23rd National Symposium on Plasma Science and Technology (PLASMA-2008) held at Bhabha Atomic Research Center, Mumbai, 10- December 2008 in association with the Plasma Science Society of India. The Plasma Science Society of India has been holding regular symposia on general topics related to Plasma. The symposium was designed to provide a forum for young researchers in Plasma Science and Technology to interact with eminent plasma scientists from India and abroad and to present their work. The scope of the symposium included frontline research in Basic Plasma Physics as well as significant advances in Plasma Technology. In view of the ever-growing importance of Plasma Science and Technology to India's Nuclear Energy program, the focal theme of the symposium was chosen as 'Plasmas in Nuclear Fuel Cycle'. The scientific program of this four day symposium consisted of review talks, invited topical lectures, contributed oral and poster presentations in the following areas of Plasma Science & Technology. Basic Plasma Physics, simulations and modeling (BP) Nuclear fusion and Technology (NF) Space & Astrophysical Plasma(SA) Exotic Plasmas, Non-linear Dynamics(EP) Laser Plasma Interaction and Beam Physics (LP) Industrial applications of plasmas (IP) Plasma Diagnostics(PD) Plasmas and clean environment(PC) There was also a Special Session devoted to the focal theme Plasmas in Nuclear Fuel Cycle (PANFC) Applications in Nuclear Fusion Technology (ANFT) Physics and technology of Processing Plasmas in Nuclear Fuel Cycle (PPNFC). Plasma Technology finds wide applications not only in nuclear, space and defense-related industries but also in medical, nano-technology and semiconductor industries. Plasma technologies have distinguished themselves in terms of compactness, process efficiency, techno economics and innovative possibilities. As we advance into the new technology era, there is a need for evolving strategies to apply the

  20. Effect of Nozzle Length on Arc Attachment and Heat Trasnfer on The Anode in A Transferred Plasma Torch for Waste Melting Process

    NASA Astrophysics Data System (ADS)

    Lee, Chan Min; Choi, Shin Il; Choi, Soo Seok; Hong, Sang Hee

    2002-10-01

    The effects of nozzle length on arc attachment and heat transfer on a water-cooled copper anode plate in a transferred arc plasma torch for its application to melting and vitrification of solid wastes are discussed on the basis of experimental investigations. In the previous study(M. Hur, T. H. Hwang, W. T. Ju, C. M. Lee, and S. H. Hong, Thin Solid Films) 390 (2001) 186., the input power fractions to the anode is very rapidly decreased with increasing the arc length in a torch of short nozzle type compared to one of long nozzle type. In the present work, different modes of the arc attachment are experimentally identified by measuring arc voltage fluctuations and arc column images with a CCD camera. The different features of heat transfer rate obtained by the torch nozzle type are explained by its correlation with the arc anode attachment modes. In addition, the arc length ranges maintaining a diffuse mode according to arc current and gas flow rate are compared for the two types of plasma torches.

  1. Modeling Arcs

    SciTech Connect

    Insepov, Z.; Norem, J.; Vetizer, S.; Mahalingam, S.

    2011-12-23

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

  2. Global Geospace Science/Polar Plasma Laboratory: POLAR

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Global Geospace Science (GGS) Project is discussed as part of the International Solar-Terrestrial Physics (ISTP) Science Initiative. The objectives of Polar Plasma Laboratory (POLAR), one of the two spacecraft to be used by the Project to fill critical gaps in the scientific understanding of solar and plasma physics, are outlined. POLAR Laboratory is described, along with POLAR instrumentation, support subsystems, and orbits. Launch vehicle and injection into orbit are also addressed.

  3. Characteristics and performance of the variable polarity plasma arc welding process used in the Space Shuttle external tank

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Lee, C. C.; Liu, J. W.

    1990-01-01

    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. Flow profiles and power distribution of argon plasma gas as a working fluid to produce plasma arc jet in the VPPA welding process was analyzed. Major loss of heat transfer for flow through the nozzle is convective heat transfer; for the plasma jet flow between the outlet of the nozzle and workpiece is radiative heat transfer; and for the flow through the keyhole of the workpiece is convective heat transfer. The majority of the power absorbed by the keyhole of the workpiece is used for melting the solid metal workpiece into a molten metallic puddle. The crown and root widths and the crown and root heights can be predicted. An algorithm for promoting automatic control of flow parameters and the dimensions of the final product of the welding specification to be used for the VPPA Welding System operated at MSFC are provided.

  4. Comparative study of two- and three-dimensional modeling on arc discharge phenomena inside a thermal plasma torch with hollow electrodes

    SciTech Connect

    Kim, Keun Su; Park, Jin Myung; Choi, Sooseok; Kim, Jongin; Hong, Sang Hee

    2008-02-15

    A comparative study between two- and three-dimensional (2D and 3D) modeling is carried out on arc discharge phenomena inside a thermal plasma torch with hollow electrodes, in order to evaluate the effects of arc root configuration characterized by either 2D annular or 3D highly localized attachment on the electrode surface. For this purpose, a more precise 3D transient model has been developed by taking account of 3D arc current distribution and arc root rotation. The 3D simulation results apparently reveal that the 3D arc root attachment brings about the inherent 3D and turbulence nature of plasma fields inside the torch. It is also found that the constricted arc column near the vortex chamber plays an important role in heating and acceleration of injected arc gases by concentrating arc currents on the axis of the hollow electrodes. The inherent 3D nature of arc discharge is well preserved inside the cathode region, while these 3D features slowly diminish behind the vortex chamber where the turbulent flow begins to be developed in the anode region. Based on the present simulation results, it is noted that the mixing effects of the strong turbulent flow on the heat and mass transfer are mainly responsible for the gradual relaxation of the 3D structures of plasma fields into the 2D axisymmetric ones that eventually appear in the anode region near the torch exit. From a detailed comparison of the 3D results with the 2D ones, the arc root configuration seems to have a significant effect on the heat transfer to the electrode surfaces interacting with the turbulent plasma flow. That is, in the 2D simulation based on an axisymmetric stationary model, the turbulence phenomena are fairly underestimated and the amount of heat transferred to the cold anode wall is calculated to be smaller than that obtained in the 3D simulation. For the validation of the numerical simulations, calculated plasma temperatures and axial velocities are compared with experimentally measured ones

  5. New Plasma Tools for Antimatter Science

    SciTech Connect

    Danielson, J. R.; Weber, T. R.; Surko, C. M.

    2008-08-08

    Recent research is described that exploits nonneutral plasma techniques to develop new tools to accumulate, manipulate and store antimatter and to make cold, bright antiparticle beams. Progress is described in three areas: radial compression of single-component plasmas using rotating electric fields in a novel, strong-drive regime; experiments and complementary theoretical modeling of the extraction of antiparticle beams with small transverse spatial extent from single-component plasmas; and work to develop a multicell trap to increase, by orders of magnitude, the capacity for antiparticle storage. Potential applications of these tools and challenges for future research are discussed.

  6. IEEE conference record -- abstracts: 1995 IEEE international conference on plasma science

    SciTech Connect

    1995-12-31

    Topics covered at this meeting are: computational plasma physics; slow wave devices; basic phenomena in fully ionized plasmas; microwave-plasma interactions; space plasmas; fast wave devices; plasma processing; plasma, ion, and electron sources; vacuum microelectronics; basic phenomena in partially ionized gases; microwave systems; plasma diagnostics; magnetic fusion theory/experiment; fast opening switches; laser-produced plasmas; dense plasma focus; intense ion and electron beams; plasmas for lighting; fast z-pinches and x-ray lasers; intense beam microwaves; ball lightning/spherical plasma configuration; environmental plasma science; EM and ETH launchers; and environmental/energy issues in plasma science. Separate abstracts were prepared for most of the individual papers.

  7. Magnesium plasma diagnostics by heated probe and characterization of the Mg thin films deposited by thermionic vacuum arc technology

    NASA Astrophysics Data System (ADS)

    Vladoiu, Rodica; Mandes, Aurelia; Dinca Balan, Virginia; Prodan, Gabriel; Kudrna, Pavel; Tichý, Milan

    2015-06-01

    The aim of this paper is to report on magnesium plasma diagnostics and to investigate the properties of thin Mg films deposited on Si and glass substrates by using thermionic vacuum arc (TVA) technology. TVA is an original deposition method using a combination of anodic arc and powerful electron gun system (up to 600 W) for the growth of thin films from solid precursors under a vacuum of 10-6Torr. Due to the comparatively high deposition rate as well as comparatively high plasma potential—around 0.5 kV—plasma diagnostics were carried out by a heated probe that prevents layer deposition on the probe surface. The estimated value of electron density was in the order of 1.0  ×  1016m-3 and the electron temperature varied between 4  ×  104 and 1.2  ×  105 K (corresponding to two different discharge conditions). The thin Mg films were investigated using SEM images and TEM analyses provided with HR-TEM and SAED facilities. According to the SAED patterns the structure of the films can be indexed as two forms: hexagonal structure for Mg and cubic structure for MgO; the peak value of grain size distribution was 91.29 nm in diameter for Mg TVA/Si and 61.06 nm for Mg TVA/Gl.

  8. High-heat-flux testing of irradiated tungsten-based materials for fusion applications using infrared plasma arc lamps

    DOE PAGESBeta

    Sabau, Adrian S.; Ohriner, Evan K.; Kiggans, Jim; Schaich, Charles R.; Ueda, Yoshio; Harper, David C.; Katoh, Yutai; Snead, Lance L.; Byun, Thak S.

    2014-11-01

    Testing of advanced materials and component mock-ups under prototypical fusion high-heat-flux conditions, while historically a mainstay of fusion research, has proved to be quite challenging, especially for irradiated materials. A new high-heat-flux–testing (HHFT) facility based on water-wall plasma arc lamps (PALs) is now introduced for materials and small-component testing. Two PAL systems, utilizing a 12 000°C plasma arc contained in a quartz tube cooled by a spiral water flow over the inside tube surface, provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over areas of 9×12 and 1×10 cm2, respectively. This paper will present the overall design andmore » implementation of a PAL-based irradiated material target station (IMTS). The IMTS is primarily designed for testing the effects of heat flux or thermal cycling on material coupons of interest, such as those for plasma-facing components. Temperature results are shown for thermal cycling under HHFT of tungsten coupon specimens that were neutron irradiated in HFIR. Finally, radiological surveys indicated minimal contamination of the 36×36×18 cm test section, demonstrating the capability of the new facility to handle irradiated specimens at high temperature.« less

  9. Microstructure and Mechanical Properties of Plasma Arc Brazed AISI 304L Stainless Steel and Galvanized Steel Plates

    NASA Astrophysics Data System (ADS)

    Jin, Yajuan; Li, Ruifeng; Yu, Zhishui; Wang, Yu

    2016-04-01

    Plasma arc brazing is used to join the AISI 304L stainless steel and galvanized steel plate butt joints with the CuSi3Mn1 filler wire. The effect of parameters on weld surface appearance, interfacial microstructure, and composition distribution in the joint was studied. The microhardness and mechanical tests were conducted to determine the mechanical properties of the welded specimens. The results indicated that good appearance, bead shape, and sufficient metallurgical bonding could be obtained when the brazing process was performed with a wire feeding speed of 0.8 m/min, plasma gas flow rate of 3.0 l/min, welding current of 100 A, and welding speed of 27 cm/min. During plasma arc brazing process, the top corner of the stainless steel and galvanized steel plate were heated and melted, and the melted quantity of stainless steel was much more than that of the galvanized steel due to the thermal conductivity coefficient difference between the dissimilar materials. The microhardness test results shows that the microhardness value gradually increased from the side of the galvanized steel to the stainless steel in the joint, and it is good for improving the mechanical properties of joint. The tensile strength was a little higher than that of the brazing filler, and the fracture position of weld joint was at the base metal of galvanized steel plate.

  10. High-heat-flux testing of irradiated tungsten-based materials for fusion applications using infrared plasma arc lamps

    SciTech Connect

    Sabau, Adrian S.; Ohriner, Evan K.; Kiggans, Jim; Schaich, Charles R.; Ueda, Yoshio; Harper, David C.; Katoh, Yutai; Snead, Lance L.; Byun, Thak S.

    2014-11-01

    Testing of advanced materials and component mock-ups under prototypical fusion high-heat-flux conditions, while historically a mainstay of fusion research, has proved to be quite challenging, especially for irradiated materials. A new high-heat-flux–testing (HHFT) facility based on water-wall plasma arc lamps (PALs) is now introduced for materials and small-component testing. Two PAL systems, utilizing a 12 000°C plasma arc contained in a quartz tube cooled by a spiral water flow over the inside tube surface, provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over areas of 9×12 and 1×10 cm2, respectively. This paper will present the overall design and implementation of a PAL-based irradiated material target station (IMTS). The IMTS is primarily designed for testing the effects of heat flux or thermal cycling on material coupons of interest, such as those for plasma-facing components. Temperature results are shown for thermal cycling under HHFT of tungsten coupon specimens that were neutron irradiated in HFIR. Finally, radiological surveys indicated minimal contamination of the 36×36×18 cm test section, demonstrating the capability of the new facility to handle irradiated specimens at high temperature.

  11. Advances and Challenges in Computational Plasma Science

    SciTech Connect

    W.M. Tang; V.S. Chan

    2005-01-03

    Scientific simulation, which provides a natural bridge between theory and experiment, is an essential tool for understanding complex plasma behavior. Recent advances in simulations of magnetically-confined plasmas are reviewed in this paper with illustrative examples chosen from associated research areas such as microturbulence, magnetohydrodynamics, and other topics. Progress has been stimulated in particular by the exponential growth of computer speed along with significant improvements in computer technology.

  12. Development of a plasma arc system for the destruction of U.S. Department of Defense hazardous waste

    SciTech Connect

    Sartwell, B.D.; Gehrman, F.H. Jr.; Telfer, T.R.

    1999-07-01

    The Naval Base, Norfolk, located in the northern portion of the city of Norfolk, Virginia, is the world's largest naval base and home of the Atlantic Fleet. Activities at the naval base generate approximately 1.4 million kilograms (3.0 million pounds) of industrial waste (hazardous and non-hazardous) annually. Significant components of the waste stream include used paint, cleaning rags, cleaning compounds, solvents, and other chemicals used in industrial operations. The costs of disposing of this waste are significant and are currently over $4 million annually, representing an average of $3.30 per kilogram ($1.50 per pound). Plasma arc technology has been identified as having the potential to cost-effectively treat and destroy various types of waste materials, including contaminated soil, ordnance, pyrotechnics, and low-level radioactive waste. There are currently several pilot-scale plasma arc units being tested in the United States, but at present there are no fully-permitted production-scale units in operation. In July 1995 a project was awarded to the Naval Research Laboratory and Norfolk Naval Base under the DOD Environmental Security Technology Certification Program with the objective of establishing a production scale demonstration plasma arc hazardous waste treatment facility (PAHWTF) at the Naval Base that would be capable of destroying both solid and liquid waste on a production basis and obtaining operational data necessary to determine the cost effectiveness of the process. This paper provides a detailed description of the PAHWTF, which was designed and built by Retech in Ukiah, CA, and also provides results of treatability tests. Information is also provided on the status of an Environmental Impact Statement and of RCRA Research, Development, and Demonstration, and air permits.

  13. Tunable, self-powered integrated arc plasma-melter vitrification system for waste treatment and resource recovery

    DOEpatents

    Titus, Charles H.; Cohn, Daniel R.; Surma, Jeffrey E.

    1998-01-01

    The present invention provides a relatively compact self-powered, tunable waste conversion system and apparatus which has the advantage of highly robust operation which provides complete or substantially complete conversion of a wide range of waste streams into useful gas and a stable, nonleachable solid product at a single location with greatly reduced air pollution to meet air quality standards. The system provides the capability for highly efficient conversion of waste into high quality combustible gas and for high efficiency conversion of the gas into electricity by utilizing a high efficiency gas turbine or by an internal combustion engine. The solid product can be suitable for various commercial applications. Alternatively, the solid product stream, which is a safe, stable material, may be disposed of without special considerations as hazardous material. In the preferred embodiment of the invention, the arc plasma furnace and joule heated melter are formed as a fully integrated unit with a common melt pool having circuit arrangements for the simultaneous independently controllable operation of both the arc plasma and the joule heated portions of the unit without interference with one another. The preferred configuration of this embodiment of the invention utilizes two arc plasma electrodes with an elongated chamber for the molten pool such that the molten pool is capable of providing conducting paths between electrodes. The apparatus may additionally be employed with reduced or without further use of the gases generated by the conversion process. The apparatus may be employed as a self-powered or net electricity producing unit where use of an auxiliary fuel provides the required level of electricity production.

  14. Photoelectron emission from metal surfaces induced by VUV-emission of filament driven hydrogen arc discharge plasma

    NASA Astrophysics Data System (ADS)

    Laulainen, J.; Kalvas, T.; Koivisto, H.; Komppula, J.; Tarvainen, O.

    2015-04-01

    Photoelectron emission measurements have been performed using a filament-driven multi-cusp arc discharge volume production H- ion source (LIISA). It has been found that photoelectron currents obtained with Al, Cu, Mo, Ta and stainless steel (SAE 304) are on the same order of magnitude. The photoelectron currents depend linearly on the discharge power. It is shown experimentally that photoelectron emission is significant only in the short wavelength range of hydrogen spectrum due to the energy dependence of the quantum efficiency. It is estimated from the measured data that the maximum photoelectron flux from plasma chamber walls is on the order of 1 A per kW of discharge power.

  15. Educational Outreach at the MIT Plasma Science and Fusion Center

    NASA Astrophysics Data System (ADS)

    Rivenberg, Paul; Thomas, Paul

    2006-10-01

    At the MIT PSFC, student and staff volunteers work together to increase the public's knowledge of fusion science and plasma technology. Seeking to generate excitement in young people about science and engineering, the PSFC hosts a number of educational outreach activities throughout the year, including Middle and High School Outreach Days. The PSFC also has an in-school science demonstration program on the theme of magnetism. The Mr. Magnet Program, headed by Mr. Paul Thomas, has been bringing lively demonstrations on magnetism into local elementary and middle schools for 15 years. This year Mr. Magnet presented the program to nearly 30,000 students at over 67 schools and other events, reaching kindergartners through college freshmen. In addition to his program on magnetism, he is offering an interactive lecture about plasma to high schools. The "Traveling Plasma Lab" encourages students to learn more about plasma science while having fun investigating plasma properties using actual laboratory techniques and equipment. Beyond the classroom, Paul Thomas has provided technical training for Boston Museum of Science staff in preparation for the opening of a Star Wars exhibit. His hands-on demos have also been filmed by the History Channel for a one-hour program about Magnetism, which aired in June 2006.

  16. Control of a shock wave-boundary layer interaction using localized arc filament plasma actuators

    NASA Astrophysics Data System (ADS)

    Webb, Nathan Joseph

    Supersonic flight is currently possible, but expensive. Inexpensive supersonic travel will require increased efficiency of high-speed air entrainment, an integral part of air-breathing propulsion systems. Although mixed compression inlet geometry can significantly improve entrainment efficiency, numerous Shock Wave-Boundary Layer Interactions (SWBLIs) are generated in this configuration. The boundary layer must therefore develop through multiple regions of adverse pressure gradient, causing it to thicken, and, in severe cases, separate. The associated increase in unsteadiness can have adverse effects on downstream engine hardware. The most severe consequence of these interactions is the increased aerodynamic blockage generated by the thickened boundary layer. If the increase is sufficient, it can choke the flow, causing inlet unstart, and resulting in a loss of thrust and high transient forces on the engine, airframe, and aircraft occupants. The potentially severe consequences associated with SWBLIs require flow control to ensure proper operation. Traditionally, boundary layer bleed has been used to control the interaction. Although this method is effective, it has inherent efficiency penalties. Localized Arc Filament Plasma Actuators (LAFPAs) are designed to generate perturbations for flow control. Natural flow instabilities act to amplify certain perturbations, allowing the LAFPAs to control the flow with minimal power input. LAFPAs also have the flexibility to maintain control over a variety of operating conditions. This work seeks to examine the effectiveness of LAFPAs as a separation control method for an oblique, impinging SWBLI. The low frequency unsteadiness in the reflected shock was thought to be the natural manifestation of a Kelvin-Helmholtz instability in the shear layer above the separation region. The LAFPAs were therefore placed upstream of the interaction to allow their perturbations to convect to the receptivity region (near the shear layer origin

  17. Proceedings of the Semiannual Meetings of the Plasma Science Committee

    SciTech Connect

    Plasma Science Committee

    2004-06-30

    Fall 2001: (September 29-30, 2001; Irvine, CA) This meeting focused on presentations and plans for two ad hoc projects sponsored by the committee?the burning plasma study and the partially ionized plasma proposals. Ongoing discussions with CHEDPP chair Ron Davidson were also included. Significant attention was given to FESAC and the Fusion Energy Snowmass meeting planned for Summer 2002. These discussions lead to continued development of the proposal for the burning plasma project. A science talk on plasma processing of materials from an industry perspective provided a backdrop for discussion of the partially ionized plasmas project. Spring 2002: (April 5-6, 2003; Washington, DC) This meeting included updates from the funding agencies (DOE, NSF, ONR, and NASA) and a discussion panel amongst them, a review of the burning plasma study proposal, and a discussion of the HED study?s progress. Future work items such as the plasma physics volume of the decadal physics survey and potential studies on computer modeling and simulation were also discussed. Fall 2002: (September 28-29, 2002; Irvine, CA) This meeting discussed the status of the then-recently started burning plasma study, heard the findings and recommendations of the HED study, and discussed the prospects for fusion in light of the Snowmass summer study and the FESAC sub-panel on burning plasma program options. A science talk addressed the role of plasmas in astrophysics and brought attention to the need for greater rapport between plasma physicists and NASA?s space sciences programs. The Plasma 2010 project was discussed in detail and a draft proposal was reviewed. Spring 2003: (April 4-5, 200; Washington, DC) This meeting centered on the activies of BPAC and discussion of the proposed Plasma 2010 project. Agency representatives discussed their program plans; they also commented on the possibilities of an ITER-future and discussed the status of the joint DOE/NSF funding program in basic plasma science. A

  18. Application of welding science to welding engineering: A lumped parameter gas metal arc welding dynamic process model

    SciTech Connect

    Murray, P.E.; Smartt, H.B.; Johnson, J.A.

    1997-12-31

    We develop a model of the depth of penetration of the weld pool in gas metal arc welding (GMAW) which demonstrates interaction between the arc, filler wire and weld pool. This model is motivated by the observations of Essers and Walter which suggest a relationship between droplet momentum and penetration depth. A model of gas metal arc welding was augmented to include an improved model of mass transfer and a simple model of accelerating droplets in a plasma jet to obtain the mass and momentum of impinging droplets. The force of the droplets and depth of penetration is correlated by a dimensionless linear relation used to predict weld pool depth for a range of values of arc power and contact tip to workpiece distance. Model accuracy is examined by comparing theoretical predictions and experimental measurements of the pool depth obtained from bead on plate welds of carbon steel in an argon rich shielding gas. Moreover, theoretical predictions of pool depth are compared to the results obtained from the heat conduction model due to Christensen et al. which suggest that in some cases the momentum of impinging droplets is a better indicator of the depth of the weld pool and the presence of a deep, narrow penetration.

  19. Tritium Plasma Experiment Upgrade for Fusion Tritium and Nuclear Sciences

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Taylor, Chase N.; Kolasinski, Robert D.; Buchenauer, Dean A.

    2015-11-01

    The Tritium Plasma Experiment (TPE) is a unique high-flux linear plasma device that can handle beryllium, tritium, and neutron-irradiated plasma facing materials, and is the only existing device dedicated to directly study tritium retention and permeation in neutron-irradiated materials [M. Shimada et.al., Rev. Sci. Instru. 82 (2011) 083503 and and M. Shimada, et.al., Nucl. Fusion 55 (2015) 013008]. Recently the TPE has undergone major upgrades in its electrical and control systems. New DC power supplies and a new control center enable remote plasma operations from outside of the contamination area for tritium, minimizing the possible exposure risk with tritium and beryllium. We discuss the electrical upgrade, enhanced operational safety, improved plasma performance, and development of tritium plasma-driven permeation and optical spectrometer system. This upgrade not only improves operational safety of the worker, but also enhances plasma performance to better simulate extreme plasma-material conditions expected in ITER, Fusion Nuclear Science Facility (FNSF), and Demonstration reactor (DEMO). This work was prepared for the U.S. Department of Energy, Office of Fusion Energy Sciences, under the DOE Idaho Field Office contract number DE-AC07-05ID14517.

  20. Novel Methods for Communicating Plasma Science to the General Public

    NASA Astrophysics Data System (ADS)

    Zwicker, Andrew; Merali, Aliya; Wissel, S. A.; Delooper, John

    2012-10-01

    The broader implications of Plasma Science remains an elusive topic that the general public rarely discusses, regardless of their relevance to energy, the environment, and technology. Recently, we have looked beyond print media for methods to reach large numbers of people in creative and informative ways. These have included video, art, images, and music. For example, our submission to the ``What is a Flame?'' contest was ranked in the top 15 out of 800 submissions. Images of plasmas have won 3 out of 5 of the Princeton University ``Art of Science'' competitions. We use a plasma speaker to teach students of all ages about sound generation and plasma physics. We report on the details of each of these and future videos and animations under development.

  1. Temporal evolution of ion energy distribution functions and ion charge states of Cr and Cr-Al pulsed arc plasmas

    SciTech Connect

    Tanaka, Koichi; Anders, André

    2015-11-15

    To study the temporal evolution of ion energy distribution functions, charge-state-resolved ion energy distribution functions of pulsed arc plasmas from Cr and Cr-Al cathodes were recorded with high time resolution by using direct data acquisition from a combined energy and mass analyzer. The authors find increases in intensities of singly charged ions, which is evidence that charge exchange reactions took place in both Cr and Cr-Al systems. In Cr-Al plasmas, the distributions of high-charge-state ions exhibit high energy tails 50 μs after discharge ignition, but no such tails were observed at 500 μs. The energy ratios of ions of different charge states at the beginning of the pulse, when less neutral atoms were in the space in front of the cathode, suggest that ions are accelerated by an electric field. The situation is not so clear after 50 μs due to particle collisions. The initial mean ion charge state of Cr was about the same in Cr and in Cr-Al plasmas, but it decreased more rapidly in Cr-Al plasmas compared to the decay in Cr plasma. The faster decay of the mean ion charge state and ion energy caused by the addition of Al into a pure Cr cathode suggests that the mean ion charge state is determined not only by ionization processes at the cathode spot but also by inelastic collision between different elements.

  2. Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

    NASA Astrophysics Data System (ADS)

    Frolov, V.; Ivanov, D.; Toropchin, A.

    2014-11-01

    Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying.

  3. Departures from local thermodynamic equilibrium in cutting arc plasmas derived from electron and gas density measurements using a two-wavelength quantitative Schlieren technique

    SciTech Connect

    Prevosto, L.; Mancinelli, B.; Artana, G.; Kelly, H.

    2011-03-15

    A two-wavelength quantitative Schlieren technique that allows inferring the electron and gas densities of axisymmetric arc plasmas without imposing any assumption regarding statistical equilibrium models is reported. This technique was applied to the study of local thermodynamic equilibrium (LTE) departures within the core of a 30 A high-energy density cutting arc. In order to derive the electron and heavy particle temperatures from the inferred density profiles, a generalized two-temperature Saha equation together with the plasma equation of state and the quasineutrality condition were employed. Factors such as arc fluctuations that influence the accuracy of the measurements and the validity of the assumptions used to derive the plasma species temperature were considered. Significant deviations from chemical equilibrium as well as kinetic equilibrium were found at elevated electron temperatures and gas densities toward the arc core edge. An electron temperature profile nearly constant through the arc core with a value of about 14000-15000 K, well decoupled from the heavy particle temperature of about 1500 K at the arc core edge, was inferred.

  4. A rotating two-phase gas/liquid flow for pressure reduction in underwater plasma arc welding

    SciTech Connect

    Steinkamp, H.; Creutz, M.; Mewes, D.; Bartzsch, J.

    1994-12-31

    Plasma arc welding processes are used in off-shore industry for the construction and maintenance in the wet surrounding of underwater structures and pipelines. In greater water depth the density of the plasma gas increase because of the greater hydrostatic pressure. This causes an increase of the conductive heat losses to the wet surrounding. To keep up the energy flux to the workpiece a pressure reduction is favorable against the surrounding. To keep up the energy flux to the workpiece a pressure reduction is favorable against the surrounding. The plasma arc has to burn in a locally dry area. This requirement can be fulfilled by a rotating disc placed above the workpiece. In the gap between the lower end of the cylinder and the workpiece a rotating two-phase flow is maintained. The flow around the rotating disc is experimentally investigated. The rotating disc is placed above the surface of the workpiece which is simulated by a flat plate. Water is forced out of the cylinder due to centrifugal forces set up by the rotating disc and flat plate. The velocity distribution in the flow is measured by Laser-Doppler-Anemometry. The phase distribution in the two-phase flow in the gap is measured by local electrical probes. The static pressure in the gaseous atmosphere is reduced in comparison to the hydrostatic pressure of the surrounding water. The pressure reduction is given by the void fraction, the phase distribution and the volume flow rates of both phases in the gap as well as by the speed of revolution and the design of the disc and the work surface. Apart from the investigations on the fluid dynamics, the method to reduce the pressure was technically proved. Experiments were carried out under water with a plasma MIG welder.

  5. Plasma-catalytic hybrid system using spouted bed with a gliding arc discharge: CH4 reforming as a model reaction

    NASA Astrophysics Data System (ADS)

    Lee, H.; Sekiguchi, H.

    2011-07-01

    A combination of a gliding arc discharge and a spouted catalytic bed was used to investigate a plasma-catalytic hybrid system using CH4 reforming as a model reaction. Alumina-supported catalysts that contained 0.5 wt% of Pt, Pd, Rh, and Ru (denoted as Pt/Al2O3, Pd/Al2O3, Rh/Al2O3 and Ru/Al2O3, respectively) were used. For comparison, active Al2O3 particles were also examined. The conversion of CH4 and the selectivity of the product were investigated by changing the feed flow rate and reaction time. The production of C2H2, H2 and soot was observed in the gliding arc discharge without a catalyst. Using Pt/Al2O3 and Pd/Al2O3with the gliding arc discharge, C2H4, C2H6 and C2H2 were produced. It is considered that C2H4 and C2H6 were formed by the hydrogenation of C2H2 on the active site of Pt/Al2O3 and Pd/Al2O3. A stronger resistance to deactivation was shown in the presence of Pd/Al2O3 than in the presence of Pt/Al2O3, whereas the selectivity of hydrocarbon using Rh/Al2O3 and Ru/Al2O3 showed a tendency similar to that in active Al2O3 and non-catalytic experiments. The proposed reactor has a potential to improve the selectivity of the plasma process.

  6. Investigations of some aspects of the spray process in a single wire arc plasma spray system using high speed camera.

    PubMed

    Tiwari, N; Sahasrabudhe, S N; Tak, A K; Barve, D N; Das, A K

    2012-02-01

    A high speed camera has been used to record and analyze the evolution as well as particle behavior in a single wire arc plasma spray torch. Commercially available systems (spray watch, DPV 2000, etc.) focus onto a small area in the spray jet. They are not designed for tracking a single particle from the torch to the substrate. Using high speed camera, individual particles were tracked and their velocities were measured at various distances from the spray torch. Particle velocity information at different distances from the nozzle of the torch is very important to decide correct substrate position for the good quality of coating. The analysis of the images has revealed the details of the process of arc attachment to wire, melting of the wire, and detachment of the molten mass from the tip. Images of the wire and the arc have been recorded for different wire feed rates, gas flow rates, and torch powers, to determine compatible wire feed rates. High speed imaging of particle trajectories has been used for particle velocity determination using time of flight method. It was observed that the ripple in the power supply of the torch leads to large variation of instantaneous power fed to the torch. This affects the velocity of the spray particles generated at different times within one cycle of the ripple. It is shown that the velocity of a spray particle depends on the instantaneous torch power at the time of its generation. This correlation was established by experimental evidence in this paper. Once the particles leave the plasma jet, their forward speeds were found to be more or less invariant beyond 40 mm up to 500 mm from the nozzle exit.

  7. FOREWORD: 23rd National Symposium on Plasma Science & Technology (PLASMA-2008)

    NASA Astrophysics Data System (ADS)

    Das, A. K.

    2010-01-01

    The Twentieth Century has been a defining period for Plasma Science and Technology. The state of ionized matter, so named by Irving Langmuir in the early part of twentieth century, has now evolved in to a multidisciplinary area with scientists and engineers from various specializations working together to exploit the unique properties of the plasma medium. There have been great improvements in the basic understanding of plasmas as a many body system bound by complex collective Coulomb interactions of charges, atoms, molecules, free radicals and photons. Simultaneously, many advanced plasma based technologies are increasingly being implemented for industrial and societal use. The emergence of the multination collaborative project International Thermonuclear Experimental Reactor (ITER) project has provided the much needed boost to the researchers working on thermonuclear fusion plasmas. In addition, the other plasma applications like MHD converters, hydrogen generation, advanced materials (synthesis, processing and surface modification), environment (waste beneficiation, air and water pollution management), nanotechnology (synthesis, deposition and etching), light production, heating etc are actively being pursued in governmental and industrial sectors. For India, plasma science and technology has traditionally remained an important area of research. It was nearly a century earlier that the Saha ionization relation pioneered the way to interpret experimental data from a vast range of near equilibrium plasmas. Today, Indian research contributions and technology demonstration capabilities encompass thermonuclear fusion devices, nonlinear plasma phenomena, plasma accelerators, beam plasma interactions, dusty and nonneutral plasmas, industrial plasmas and plasma processing of materials, nano synthesis and structuring, astrophysical and space plasmas etc. India's participation in the ITER programme is now reflected in increased interest in the research and development

  8. The influence of arc plasma parameters on the form of a welding pool

    NASA Astrophysics Data System (ADS)

    Frolov, V. Ya.; Toropchin, A. I.

    2015-07-01

    The influence of the Marangoni force on the form of a welding pool has been considered. Results of computer simulation of the processes of welding arc generation with a non-consumable tungsten electrode in inert gas are shown. The experimental results are reported and comparatively analyzed. The calculations were carried out in a package of applied programs at various currents.

  9. Study of the effect of low-power pulse laser on arc plasma and magnesium alloy target in hybrid welding by spectral diagnosis technique

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Hao, Xinfeng

    2008-10-01

    In order to study the effect of laser pulses on arc plasma and target metal in the hybrid welding process, the spectra of the plasmas in the welding process of magnesium alloys are analysed in this paper. The acquisition system of plasma spectra is set up and the spectral lines of welding plasma are acquired. Compared with tungsten-inert gas (TIG) welding, the intensities of the spectral lines of magnesium increase sharply while those of Ar decrease for strong evaporation and ionization of magnesium alloys in low-power laser/arc hybrid welding. The electron temperature and density are estimated by the Boltzmann plot method and the Stark broadening effect. The result shows that the electron temperature of arc plasma in the hybrid welding process is much lower than that in TIG welding, especially in the laser beam-affected zone. In contrast, the electron density of the plasma is enhanced. The influences of laser parameters on electron temperature are also studied. The changes in electron temperature and density indicate that the effect of laser pulse on the target metal is the dominant factor influencing the electron temperature and density in low-power laser/arc hybrid welding.

  10. Optical emission spectroscopy of carbon arc for nanomaterial synthesis

    NASA Astrophysics Data System (ADS)

    Vekselman, Vladislav; Stratton, Brentley; Raitses, Yevgeny

    2015-11-01

    Arc plasma assisted synthesis of carbon nanostructures is one of the most efficient and simple production methods. In spite of a long time use of this method in materials science research and industrial applications, the role of the plasma in nucleation and growth of nanostructures is not well understood. This is due to complexity of physico-chemical processes governing the plasma nanosynthesis. The objective of this work is to characterize the atmospheric pressure arc plasma used for synthesis of various carbon nanostructures. Optical emission spectroscopy was carried out to determine the distribution of temperature and density of carbon plasma in the synthesis zone as a function of arc discharge parameters. Accurate and detailed mapping of plasma parameters elucidate the general trend governing the formation of carbon nanostructures. This work was supported by DOE contract DE-AC02-09CH11466.

  11. Effects of arc current on the life in burner rig thermal cycling of plasma sprayed ZrOsub2-Ysub2Osub3

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Mcdonald, G.

    1982-01-01

    An analysis of thermal cycle life data for four sets of eight thermal barrier coated specimens representing arc currents (plasma gun power) of 525, 600, 800, or 950 amps is presented. The ZrO2-8Y2O3/NiCrAlY plasma spray coated Rene 41 rods were thermal cycled to 1040 C in a Mach 0.3-Jet A/air burner flame. The experimental results indicate the existance of a minimum or threshold power level which coating life expectancy is less than 500 cycles. Above the threshold power level, coating life expectancy more than doubles and increases with arc current.

  12. In Situ Synthesis of TiC-Fe Composite Overlays from Low Cost TiO2 Precursors Using Plasma Transferred Arc Deposition

    NASA Astrophysics Data System (ADS)

    Corujeira Gallo, Santiago; Alam, Nazmul; O'Donnell, Robert

    2014-02-01

    A direct conversion of TiO2 into TiC during plasma transferred arc deposition is a cheap and novel approach to produce wear resistant coatings. The present study explored the use of a low cost titanium ore as precursor for titanium carbide in metal matrix composite overlays. The deposited layers were characterized using optical microscopy, scanning electron microscopy, x-ray diffraction and microhardness testing. A carbothermic reduction of the titanium oxides took place during the deposition of the coating by plasma transferred arc. The overlays produced in this way consisted of fine titanium carbides evenly dispersed in an iron matrix. The opportunities and limitations of this approach are discussed.

  13. PREFACE: 23rd National Symposium on Plasma Science & Technology (PLASMA-2008)

    NASA Astrophysics Data System (ADS)

    Mago, V. K.; Ananthapadmanabhan, P. V.; Patil, D. S.; Das, A. K.

    2010-01-01

    It is our pleasure to present the proceedings of the 23rd National Symposium on Plasma Science and Technology (PLASMA-2008) held at Bhabha Atomic Research Center, Mumbai, 10- December 2008 in association with the Plasma Science Society of India. The Plasma Science Society of India has been holding regular symposia on general topics related to Plasma. The symposium was designed to provide a forum for young researchers in Plasma Science and Technology to interact with eminent plasma scientists from India and abroad and to present their work. The scope of the symposium included frontline research in Basic Plasma Physics as well as significant advances in Plasma Technology. In view of the ever-growing importance of Plasma Science and Technology to India's Nuclear Energy program, the focal theme of the symposium was chosen as 'Plasmas in Nuclear Fuel Cycle'. The scientific program of this four day symposium consisted of review talks, invited topical lectures, contributed oral and poster presentations in the following areas of Plasma Science & Technology. Basic Plasma Physics, simulations and modeling (BP) Nuclear fusion and Technology (NF) Space & Astrophysical Plasma(SA) Exotic Plasmas, Non-linear Dynamics(EP) Laser Plasma Interaction and Beam Physics (LP) Industrial applications of plasmas (IP) Plasma Diagnostics(PD) Plasmas and clean environment(PC) There was also a Special Session devoted to the focal theme Plasmas in Nuclear Fuel Cycle (PANFC) Applications in Nuclear Fusion Technology (ANFT) Physics and technology of Processing Plasmas in Nuclear Fuel Cycle (PPNFC). Plasma Technology finds wide applications not only in nuclear, space and defense-related industries but also in medical, nano-technology and semiconductor industries. Plasma technologies have distinguished themselves in terms of compactness, process efficiency, techno economics and innovative possibilities. As we advance into the new technology era, there is a need for evolving strategies to apply the

  14. The HelCat basic plasma science device

    NASA Astrophysics Data System (ADS)

    Gilmore, M.; Lynn, A. G.; Desjardins, T. R.; Zhang, Y.; Watts, C.; Hsu, S. C.; Betts, S.; Kelly, R.; Schamiloglu, E.

    2015-01-01

    The Helicon-Cathode(HelCat) device is a medium-size linear experiment suitable for a wide range of basic plasma science experiments in areas such as electrostatic turbulence and transport, magnetic relaxation, and high power microwave (HPM)-plasma interactions. The HelCat device is based on dual plasma sources located at opposite ends of the 4 m long vacuum chamber - an RF helicon source at one end and a thermionic cathode at the other. Thirteen coils provide an axial magnetic field B >= 0.220 T that can be configured individually to give various magnetic configurations (e.g. solenoid, mirror, cusp). Additional plasma sources, such as a compact coaxial plasma gun, are also utilized in some experiments, and can be located either along the chamber for perpendicular (to the background magnetic field) plasma injection, or at one of the ends for parallel injection. Using the multiple plasma sources, a wide range of plasma parameters can be obtained. Here, the HelCat device is described in detail and some examples of results from previous and ongoing experiments are given. Additionally, examples of planned experiments and device modifications are also discussed.

  15. The Future of Boundary Plasma and Material Science

    NASA Astrophysics Data System (ADS)

    Whyte, Dennis

    2012-03-01

    The boundary of magnetic confinement devices, from the pedestal through to the surrounding surfaces, encompasses an enormous range of plasma and material physics, and their integrated coupling. It is becoming clear that due to fundamental limits of plasma stability and material response the boundary will largely define the viability of an MFE reactor. However we face an enormous knowledge deficit in stepping from present devices and ITER towards a demonstration power plant. We outline the future of boundary research required to address this deficit. The boundary should be considered a multi-scale system of coupled plasma and material science regulated through the non-linear interface of the sheath. Measurement, theory and modeling across these scales are assessed. Dimensionless parameters, often used to organized core plasma transport on similarity arguments, can be extended to the boundary plasma, plasma-surface interactions and material response. This methodology suggests an intriguing way forward to prescribe and understand the boundary issues of an eventual reactor in intermediate devices. A particularly critical issue is that the physical chemistry of the material, which is mostly determined by the material temperature, has been too neglected; pointing to the requirement for boundary plasma experiments at appropriate material temperatures. Finally the boundary plasma requirements for quiescent heat exhaust and control of transient events, such as ELMs, will be examined.

  16. Dried plasma: state of the science and recent developments.

    PubMed

    Pusateri, Anthony E; Given, Michael B; Schreiber, Martin A; Spinella, Philip C; Pati, Shibani; Kozar, Rosemary A; Khan, Abdul; Dacorta, Joseph A; Kupferer, Kevin R; Prat, Nicolas; Pidcoke, Heather F; Macdonald, Victor W; Malloy, Wilbur W; Sailliol, Anne; Cap, Andrew P

    2016-04-01

    The early transfusion of plasma is important to ensure optimal survival of patients with traumatic hemorrhage. In military and remote or austere civilian settings, it may be impossible to move patients to hospital facilities within the first few hours of injury. A dried plasma product with reduced logistical requirements is needed to enable plasma transfusion where medically needed, instead of only where freezers and other equipment are available. First developed in the 1930s, pooled lyophilized plasma was widely used by British and American forces in WWII and the Korean War. Historical dried plasma products solved the logistical problem but were abandoned because of disease transmission. Modern methods to improve blood safety have made it possible to produce safe and effective dried plasma. Dried plasma products are available in France, Germany, South Africa, and a limited number of other countries. However, no product is available in the US. Promising products are in development that employ different methods of drying, pathogen reduction, pooling, packaging, and other approaches. Although challenges exist, the in vitro and in vivo data suggest that these products have great potential to be safe and effective. The history, state of the science, and recent developments in dried plasma are reviewed. PMID:27100749

  17. Current fundamental science challenges in low temperature plasma science that impact energy security and international competitiveness

    NASA Astrophysics Data System (ADS)

    Hebner, Greg

    2010-11-01

    Products and consumer goods that utilize low temperature plasmas at some point in their creation touch and enrich our lives on almost a continuous basis. Examples are many but include the tremendous advances in microelectronics and the pervasive nature of the internet, advanced material coatings that increase the strength and reliability of products from turbine engines to potato chip bags, and the recent national emphasis on energy efficient lighting and compact fluorescent bulbs. Each of these products owes their contributions to energy security and international competiveness to fundamental research investments. However, it would be a mistake to believe that the great commercial success of these products implies a robust understanding of the complicated interactions inherent in plasma systems. Rather, current development of the next generation of low temperature plasma enabled products and processes is clearly exposing a new set of exciting scientific challenges that require leaps in fundamental understanding and interdisciplinary research teams. Emerging applications such as liquid-plasma systems to improve water quality and remediate hazardous chemicals, plasma-assisted combustion to increase energy efficiency and reduce emissions, and medical applications promise to improve our lives and the environment only if difficult science questions are solved. This talk will take a brief look back at the role of low temperature plasma science in enabling entirely new markets and then survey the next generation of emerging plasma applications. The emphasis will be on describing the key science questions and the opportunities for scientific cross cutting collaborations that underscore the need for increased outreach on the part of the plasma science community to improve visibility at the federal program level. This work is supported by the DOE, Office of Science for Fusion Energy Sciences, and Sandia National Laboratories, a multi-program laboratory managed and operated

  18. Measurements of the Ion Species of Cathodic Arc Plasma in an Axial Magnetic Field

    SciTech Connect

    Oks, Efim; Anders, Andre

    2010-10-19

    Metal and gas ion species and their charge state distributions were measured for pulsed copper cathodic arcs in argon background gas in the presence of an axial magnetic field. It was found that changing the cathode position relative to anode and ion extraction system as well as increasing the gas pressure did not much affect the arc burning voltage and the related power dissipation. However, the burning voltage and power dissipation greatly increased as the magnetic field strength was increased. The fraction of metal ions and the mean ion charge state were reduced as the discharge length was increased. The observations can be explained by the combination of charge exchange collisions and electron impact ionization. They confirm that previously published data on characteristic material-dependent charge state distributions (e.g., Anders and Yushkov, J. Appl. Phys., Vol. 91, pp. 4824-4832, 2002) are not universal but valid for high vacuum conditions and the specifics of the applied magnetic fields.

  19. Frontiers in plasma science: a high energy density perspective

    NASA Astrophysics Data System (ADS)

    Remington, Bruce

    2015-11-01

    The potential for ground-breaking research in plasma physics in high energy density (HED) regimes is compelling. The combination of HED facilities around the world spanning microjoules to megajoules, with time scales ranging from femtoseconds to microseconds enables new regimes of plasma science to be experimentally probed. The ability to shock and ramp compress samples and simultaneously probe them allows dense, strongly coupled, Fermi degenerate plasmas relevant to planetary interiors to be studied. Shock driven hydrodynamic instabilities evolving into turbulent flows relevant to the dynamics of exploding stars are being probed. The physics and dynamics of magnetized plasmas relevant to astrophysics and inertial confinement fusion are also starting to be studied. High temperature, high velocity interacting flows are being probed for evidence of astrophysical collisionless shock formation. Turbulent, high magnetic Reynolds number flows are being experimentally generated to look for evidence of the turbulent magnetic dynamo effect. And new results from thermonuclear reactions in dense hot plasmas relevant to stellar interiors are starting to emerge. A selection of examples providing a compelling vision for frontier plasma science in the coming decade will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  20. Physical characteristics of gliding arc discharge plasma generated in a laval nozzle

    SciTech Connect

    Lu, S. Y.; Sun, X. M.; Li, X. D.; Yan, J. H.; Du, C. M.

    2012-07-15

    The dynamic behavior of gliding arc discharge generated in a Laval nozzle has been investigated by electrical diagnostics and a high-speed camera. The results show that the voltage waveform keeps the initial shape as the gas flow rate is small, while it becomes less stable with increasing flow rate. During the first half of a cycle, the voltage rises and after that it decreases. In nitrogen and oxygen, the break down voltage for the arc is between 3.3 and 5.5 kV, while it is between 3.3-7.5 kV in air. The waveform of current I remains almost stable; and for nitrogen and oxygen, the maximum value of current I is between 0.28 and 0.46 A. With increasing flow rate, the power consumption in air first increases and then decreases; it remains in the range of 110-217 W, and gradually increases in nitrogen and oxygen. The power consumption in oxygen is lower than that in nitrogen; the input of the energy density decreases with increasing flow rate for all the three gases. The development of the arc is tracked and recorded by a high-speed camera. The cycle is stable at 10 ms for flow rates up to 1 m{sup 3} h{sup -1}. At a higher flow rate, the cycle becomes unstable.

  1. Magnetic-field-dependent plasma composition of a pulsed aluminum arc in an oxygen ambient

    NASA Astrophysics Data System (ADS)

    Schneider, Jochen M.; Anders, André; Yushkov, George Yu.

    2001-01-01

    A variety of plasma-based deposition techniques utilize magnetic fields to affect the degree of ionization as well as for focusing and guiding of plasma beams. Here we use time-of-flight charge-to-mass spectrometry to describe the effect of a magnetic field on the plasma composition of a pulsed Al plasma stream in an ambient containing intentionally introduced oxygen as well as for high vacuum conditions typical residual gas. The plasma composition evolution was found to be strongly dependent on the magnetic field strength and can be understood by invoking two electron impact ionization routes: ionization of the intentionally introduced gas as well as ionization of the residual gas. These results are characteristic of plasma-based techniques where magnetic fields are employed in a high-vacuum ambient. In effect, the impurity incorporation during reactive thin-film growth pertains to the present findings.

  2. Increasing Plasma Science Interest among Underprivileged Students

    NASA Astrophysics Data System (ADS)

    Merali, Aliya; Wissel, Stephanie; Quinn, Maureen; Hamlet, Nicole; Zwicker, Andrew

    2012-10-01

    For the past three years, PPPL has partnered with NASA to study dusty plasmas, convective flows, and other related topics in μ-gravity. During the last year, we worked with a group of highly-motivated but underprivileged high school students to develop an experiment looking at the Rayleigh-Taylor instability in varying gravitational environments. The students were challenged to design, build and test the experiment to be flown aboard NASA's ``Weightless Wonder.'' Students met weekly with PPPL mentors over the course of the 9-month school year. The program provided students with long-term exposure to a scientific experiment, a sense of experimental ownership, and an opportunity to experience the scientific method outside of a classroom setting. Participants used inquiry-based learning techniques to design and build the experiment. We report on impact of the program and the outcome of the students' continued work.

  3. Numerical simulation of a multicomponent non-transferred constricted direct current arc with a supersonic plasma jet

    NASA Astrophysics Data System (ADS)

    George, Camille Marta

    1998-09-01

    Maximizing dissociated species transport in plasma assisted chemical vapor deposition (CVD) is important in many low-pressure plasma jet processes. To maximize atomic hydrogen transport to a substrate in the deposition of high quality diamond, a two-dimensional computational model of a supersonic contoured direct current (dc) torch anode nozzle and its subsequent high speed jet are examined. A multicomponent chemically reacting Ar-H2 plasma is modeled from the species generation in the high temperature arc through the species transport in the low-pressure chamber. The joule heating source term is implicitly coupled with the compressible-viscous fluid equations with a novel source term algorithm. The effect of the electrode sheath region is introduced in an atypical type of phenomenological boundary condition that allows the voltage to slip at the cathode and anode spots. To examine the anode attachment a forced or drift diffusion model and a corresponding implicit algorithm is introduced. Both diffusive fluxes, those due to ordinary mass and ambipolar diffusion, and those due to the electric field body forces are included. Unique implicit schemes are introduced to solve these diffusive fluxes. The computation of the source terms and the diffusive fluxes, are integrated into a modified flux-vector splitting finite volume formulation. It is shown that such high-speed gas flows are far from chemical equilibrium and it is necessary to include finite rate chemistry to get an accurate description of the species transport. Calculations confirm that high velocities and low pressures work favorably in the transport of precursor species. The diamond shock structure in the overexpanded jet converts kinetic energy to internal energy helping to further maintain the unstable transport. To predict an anode arc attachment, it is essential to resolve the drift diffusion to drive the charged particles through the strong axial bulk flow. Resultant fields bracketing the real three

  4. Very low pressure plasma sprayed alumina and yttria-stabilized zirconia thin dense coatings using a modified transferred arc plasma torch

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Zhang, Nannan; Zhang, Baicheng; Sun, Fu; Bolot, Rodolphe; Planche, Marie-Pierre; Liao, Hanlin; Coddet, Christian

    2011-12-01

    As a novel thermal spray process, very low pressure plasma spray (VLPPS) process has been significantly used to deposit thin, dense and homogenous ceramic coating materials for special application needs in recent years. In this study, in order to enhance low-energy plasma jet under very low pressure ambience, a home-made transferred arc nozzle was made and mounted on a low-power F100 plasma torch to fully melt or evaporate powder feedstock. As a result, thin and dense alumina (Al2O3) and yttria-stabilized zirconia (YSZ) ceramic coatings with an average thickness of 30-40 μm were successfully elaborated by the VLPPS process below 1 mbar. An optical emission spectroscopy (OES) was used to analyze the plasma jet properties. The microstructures of the coatings were observed by means of a scanning electron microscopy (SEM). It was found that the YSZ coatings displayed a bimodal microstructure which was composed of splats formed by melted particles and a little amount of vapor condensation from evaporated particles. However, vapor condensation could not be observed in the Al2O3 coatings, and only lamellar splats were found. The mechanical properties of both coatings were also evaluated.

  5. Parametric Study on Arc Behavior of Magnetically Diffused Arc

    NASA Astrophysics Data System (ADS)

    Chen, Tang; Li, Hui; Bai, Bing; Liao, Mengran; Xia, Weidong

    2016-01-01

    A model coupling the plasma with a cathode body is applied in the simulation of the diffuse state of a magnetically rotating arc. Four parametric studies are performed: on the external axial magnetic field (AMF), on the cathode shape, on the total current and on the inlet gas velocity. The numerical results show that: the cathode attachment focuses in the center of the cathode tip with zero AMF and gradually shifts off the axis with the increase of AMF; a larger cathode conical angle corresponds to a cathode arc attachment farther away off axis; the maximum values of plasma temperature increase with the total current; the plasma column in front of the cathode tip expands more severely in the axial direction, with a higher inlet speed; the cathode arc attachment shrinks towards the tip as the inlet speed increases. The various results are supposed to be explained by the joint effect of coupled cathode surface heating and plasma rotating flow. supported by National Natural Science Foundation of China (Nos. 11475174, 11035005 and 50876101)

  6. Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas

    NASA Technical Reports Server (NTRS)

    Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.

    1997-01-01

    We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.

  7. Experimental and theoretical investigation for the suppression of the plasma arc drop in the thermionic converter

    NASA Technical Reports Server (NTRS)

    Shaw, D. T.; Manikopoulos, C. N.; Chang, T.; Lee, C. H.; Chiu, N.

    1977-01-01

    Ion generation and recombination mechanisms in the cesium plasma as they pertain to the advanced mode thermionic energy converter were studied. The decay of highly ionized cesium plasma was studied in the near afterglow to examine the recombination processes. Very low recombination in such a plasma may prove to be of considerable importance in practical converters. The approaches of external cesium generation were vibrationally excited nitrogen as an energy source of ionization of cesium ion, and microwave power as a means of resonant sustenance of the cesium plasma. Experimental data obtained so far show that all three techniques - i.e., the non-LTE high-voltage pulsing, the energy transfer from vibrationally excited diatomic gases, and the external pumping with a microwave resonant cavity - can produce plasmas with their densities significantly higher than the Richardson density. The implication of these findings as related to Lam's theory is discussed.

  8. Effect of ion mass and charge state on transport of vacuum ARC plasmas through a biased magnetic filter

    SciTech Connect

    Byon, Eungsun; Kim, Jong-Kuk; Kwon, Sik-Chol; Anders, Andre

    2003-12-01

    The effect of ion mass and charge state on plasma transport through a 90{sup o}-curved magnetic filter is experimentally investigated using a pulsed cathodic arc source. Graphite, copper, and tungsten were selected as test materials. The filter was a bent copper coil biased via the voltage drop across a low-ohm, ''self-bias'' resistor. Ion transport is accomplished via a guiding electric field, whose potential forms a ''trough'' shaped by the magnetic guiding field of the filter coil. Evaluation was done by measuring the filtered ion current and determination of the particle system coefficient, which can be defined as the ratio of filter ion current, divided by the mean ion charge state, to the arc current. It was found that the ion current and particle system coefficient decreased as the mass-to-charge ratio of ions increased. This result can be qualitatively interpreted by a very simply model of ion transport that is based on compensation of the centrifugal force by the electric force associated with the guiding potential trough.

  9. Structural and Physical Characteristics of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Deposited Using a Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Yoshitake, Tsuyoshi; Nakagawa, You; Nagano, Akira; Ohtani, Ryota; Setoyama, Hiroyuki; Kobayashi, Eiichi; Sumitani, Kazushi; Agawa, Yoshiaki; Nagayama, Kunihito

    2010-01-01

    Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) films were formed without initial nucleation using a coaxial arc plasma gun. The UNCD crystallite diameters estimated from the X-ray diffraction peaks were approximately 2 nm. The Fourier transform infrared absorption spectrum exhibited an intense sp3-CH peak that might originate from the grain boundaries between UNCD crystallites whose dangling bonds are terminated with hydrogen atoms. A narrow sp3 peak in the photoemission spectrum implied that the film comprises a large number of UNCD crystallites. Large optical absorption coefficients at photon energies larger than 3 eV that might be due to the grain boundaries are specific to the UNCD/a-C:H films.

  10. Effect of non-uniform electron energy distribution function on plasma production in large arc driven negative ion source.

    PubMed

    Shibata, T; Koga, S; Terasaki, R; Inoue, T; Dairaku, M; Kashiwagi, M; Taniguchi, M; Tobari, H; Tsuchida, K; Umeda, N; Watanabe, K; Hatayama, A

    2012-02-01

    Spatially non-uniform electron energy distribution function (EEDF) in an arc driven negative ion source (JAEA 10A negative ion source: 10 A NIS) is calculated numerically by a three-dimensional Monte Carlo kinetic model for electrons to understand spatial distribution of plasma production (such as atomic and ionic hydrogen (H(0)∕H(+)) production) in source chamber. The local EEDFs were directly calculated from electron orbits including electromagnetic effects and elastic∕inelastic collision forces. From the EEDF, spatial distributions of H(0)∕H(+) production rate were obtained. The results suggest that spatial non-uniformity of H(0)∕H(+) productions is enhanced by high energy component of EEDF.

  11. Photoelectron emission from metal surfaces induced by VUV-emission of filament driven hydrogen arc discharge plasma

    SciTech Connect

    Laulainen, J.; Kalvas, T.; Koivisto, H.; Komppula, J.; Tarvainen, O.

    2015-04-08

    Photoelectron emission measurements have been performed using a filament-driven multi-cusp arc discharge volume production H{sup −} ion source (LIISA). It has been found that photoelectron currents obtained with Al, Cu, Mo, Ta and stainless steel (SAE 304) are on the same order of magnitude. The photoelectron currents depend linearly on the discharge power. It is shown experimentally that photoelectron emission is significant only in the short wavelength range of hydrogen spectrum due to the energy dependence of the quantum efficiency. It is estimated from the measured data that the maximum photoelectron flux from plasma chamber walls is on the order of 1 A per kW of discharge power.

  12. Recent Science Education Initiatives at the Princeton Plasma Physics Laboratory

    NASA Astrophysics Data System (ADS)

    Zwicker, Andrew; Dominguez, Arturo; Gershman, Sophia; Guilbert, Nick; Merali, Aliya; Ortiz, Deedee

    2013-10-01

    An integrated approach to program development and implementation has significantly enhanced a variety of Science Education initiatives for students and teachers. This approach involves combining the efforts of PPPL scientists, educators, research and education fellows, and collaborating non-profit organizations to provide meaningful educational experiences for students and teachers. Our undergraduate internship program continues to have outstanding success, with 72% of our participants going to graduate school and 45% concentrating in plasma physics. New partnerships have allowed us to increase the number of underrepresented students participating in mentored research opportunities. The number of participants in our Young Women's Conference increases significantly each year. Our Plasma Camp workshop, now in its 15th year, recruits outstanding teachers from around the country to create new plasma-centered curricula. Student research in the Science Education Laboratory concentrates on the development of a high-fidelity plasma speaker, a particle dropper for a dusty plasma experiment, microplasmas along liquid surfaces for a variety of applications, an Internet-controlled DC glow discharge source for students, and a Planeterrella for demonstrating the aurora and other space weather phenomenon for the general public.

  13. Assessment of secondary student attitudes and achievement in marine science using ArcViewRTM GIS technology

    NASA Astrophysics Data System (ADS)

    Healy, Genevieve F.

    This multi-disciplinary study explored the cognitive and pedagogical implications of integrating ArcViewRTM GIS technology into secondary science classrooms. Two middle and high school earth/environmental science teachers implemented an 8-week marine science unit into their curriculum by following an experimental design that incorporated two different instructional methods. Four hundred seven (407) students were introduced to marine science concepts using ArcViewRTM GIS technology and traditional methods of teaching at different times during implementation and then tested to identify significant effects on students' performance of content skills, cognitive skills, and spatial skills. Data were collected via the administration of pre-, mid-, and post-implementations of a 50-question multiple choice test and a 38-question attitude survey. The results of the repeated measures ANOVA analyses suggested that both teacher and condition showed statistically significant effects on middle school student performance of content, cognition, and spatial skills, but only the effect of teacher showed significance on high school student performance. Although condition showed significance in middle school performance, the similarities between condition patterns for both middle and high school groups suggested there was not enough convincing evidence to prove that either ArcViewRTM GIS or traditional instructional methods had any effect on middle or high school students' content, cognition or spatial skills. Attitude survey data indicated that high school group attitudes may have some relationship to shifts in content scores; again however, there was no convincing evidence that suggested that middle or high school student attitudes improved as a result of ArcViewRTM GIS implementation. Lack of implementation procedures, attrition rate and pre-existing group differences contributed to weaknesses in the validity of the study. The implications of this study include contributions to

  14. FOREWORD: 23rd National Symposium on Plasma Science & Technology (PLASMA-2008)

    NASA Astrophysics Data System (ADS)

    Das, A. K.

    2010-01-01

    The Twentieth Century has been a defining period for Plasma Science and Technology. The state of ionized matter, so named by Irving Langmuir in the early part of twentieth century, has now evolved in to a multidisciplinary area with scientists and engineers from various specializations working together to exploit the unique properties of the plasma medium. There have been great improvements in the basic understanding of plasmas as a many body system bound by complex collective Coulomb interactions of charges, atoms, molecules, free radicals and photons. Simultaneously, many advanced plasma based technologies are increasingly being implemented for industrial and societal use. The emergence of the multination collaborative project International Thermonuclear Experimental Reactor (ITER) project has provided the much needed boost to the researchers working on thermonuclear fusion plasmas. In addition, the other plasma applications like MHD converters, hydrogen generation, advanced materials (synthesis, processing and surface modification), environment (waste beneficiation, air and water pollution management), nanotechnology (synthesis, deposition and etching), light production, heating etc are actively being pursued in governmental and industrial sectors. For India, plasma science and technology has traditionally remained an important area of research. It was nearly a century earlier that the Saha ionization relation pioneered the way to interpret experimental data from a vast range of near equilibrium plasmas. Today, Indian research contributions and technology demonstration capabilities encompass thermonuclear fusion devices, nonlinear plasma phenomena, plasma accelerators, beam plasma interactions, dusty and nonneutral plasmas, industrial plasmas and plasma processing of materials, nano synthesis and structuring, astrophysical and space plasmas etc. India's participation in the ITER programme is now reflected in increased interest in the research and development

  15. IEEE conference record -- Abstracts: 1996 IEEE international conference on plasma science

    SciTech Connect

    1996-12-31

    This meeting covered the following topics: space plasmas; non-equilibrium plasma processing; computer simulation of vacuum power tubes; vacuum microelectronics; microwave systems; basic phenomena in partially ionized gases -- gaseous electronics, electrical discharges; ball lightning/spherical plasma configuration; plasma diagnostics; plasmas for lighting; dense plasma focus; intense ion and electron beams; plasma, ion, and electron sources; flat panel displays; fast z-pinches and x-ray lasers; environmental/energy issues in plasma science; thermal plasma processing; computational plasma physics; magnetic confinement fusion; microwave-plasma interactions; space plasma engineering; EM and ETH launchers; fast wave devices; intense beam microwaves; slow wave devices; space plasma measurements; basic phenomena in fully ionized plasma -- waves, instabilities, plasma theory, etc; plasma closing switches; fast opening switches; and laser-produced plasma. Separate abstracts were prepared for most papers in this conference.

  16. Fusion Science Outreach at the MIT Plasma Science and Fusion Center

    NASA Astrophysics Data System (ADS)

    Censabella, V.; Rivenberg, P.; Granville, J.; Nachtrieb, R.; Gangadhara, S.

    1997-11-01

    Educational Outreach at the MIT Plasma Science and Fusion Center is organized and energized by volunteers working together to increase the public's knowledge of fusion and plasma-related experiments. The PSFC holds a number of outreach activities throughout the year, such as Middle and High School Outreach Days. Included in these days is a demonstration of how magnets affect plasma using the ``Plasma Demo," an educational tool which will be on display for the first time outside the MIT area. Also featured is ``C-Mod Jr.," a video game which helps students discover how computers manipulate magnetic pulses to keep a plasma confined in the C-Mod tokamak for as long as possible. The PSFC maintains a Home Page on the World Wide Web, which can be reached at HTTP://PFC.MIT.EDU.

  17. Plasma Science and Applications at the Intel International Science and Engineering Fair

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2005-10-01

    The Coalition for Plasma Science (CPS) has established a plasma prize at the Intel International Science and Engineering Fair (ISEF). This year's prize was awarded for projects in simulated ball lightning and plasma thrusters. 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 that are received by the CPS e-mail or toll-free number. The success of these activities depend on the voluntary labor of CPS members and associates. These volunteers include the ISEF judges, whom the APS/DPP and the IEEE/PSAC helped identify. 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.

  18. Plasma diagnostics in Hg-free short-arc lamps for automotive lighting

    NASA Astrophysics Data System (ADS)

    Kettlitz, M.; Wendt, M.; Schneidenbach, H.; Krylova, O.

    2007-07-01

    In the context of developing a mercury-free lamp for automotive lighting an optimization of lamp design and plasma radiation was performed. In contrast to existing quartz lamps, a new lamp design was chosen consisting of a sapphire capillary combined with ceramic parts and pure tungsten electrodes. The lamps consist of metal halides and between 1 and 20 bar of xenon. They were operated with an electronic ballast at input powers between 20 and 40 W. Besides an optimization of the tube materials, thermography and plasma diagnostics were performed to understand the processes inside the lamp and to find optimal operation conditions. In addition to experimental diagnostics, a simulation of self-reversed sodium spectral lines was performed to verify plasma parameters, particularly the xenon pressure which could not be determined from the experiment. Additionally, tendencies of the influence of single components could be estimated by modelling.

  19. Facility for high heat flux testing of irradiated fusion materials and components using infrared plasma arc lamps

    SciTech Connect

    Sabau, Adrian S; Ohriner, Evan Keith; Kiggans, Jim; Harper, David C; Snead, Lance Lewis; Schaich, Charles Ross

    2014-01-01

    A new high-heat flux testing facility using water-wall stabilized high-power high-pressure argon Plasma Arc Lamps (PALs) has been developed for fusion applications. It can handle irradiated plasma facing component materials and mock-up divertor components. Two PALs currently available at ORNL can provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over a heated area of 9x12 and 1x10 cm2, respectively, which are fusion-prototypical steady state heat flux conditions. The facility will be described and the main differences between the photon-based high-heat flux testing facilities, such as PALs, and the e-beam and particle beam facilities more commonly used for fusion HHF testing are discussed. The components of the test chamber were designed to accommodate radiation safety and materials compatibility requirements posed by high-temperature exposure of low levels irradiated tungsten articles. Issues related to the operation and temperature measurements during testing are presented and discussed.

  20. Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

    NASA Astrophysics Data System (ADS)

    Kim, J.-H.; Nishihara, M.; Adamovich, I. V.; Samimy, M.; Gorbatov, S. V.; Pliavaka, F. V.

    2010-08-01

    Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

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

    SciTech Connect

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

    2015-08-28

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

  2. Tokamak ARC damage

    SciTech Connect

    Murray, J.G.; Gorker, G.E.

    1985-01-01

    Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage.

  3. Plasma Science and Applications at the Intel International Science and Engineering Fair

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2007-11-01

    Three years ago, the Coalition for Plasma Science (CPS) established a plasma prize at the Intel International Science and Engineering Fair. The APS/DPP and the IEEE/PSAC have helped make this effort a success by helping to identify judges. Each year since then, the number of plasma-related projects has increased. This year's prize was awarded for an instrument that, based on the ratio of spectral emission in two bands, detects when a high-pressure street light is about to fail. This allows time for an, efficient, scheduled replacement rather that an emergency service call. The CPS is a broadly-based group of institutions and individuals whose goal is to increase the understanding of plasmas for non-technical audiences. 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 that are received by the CPS e-mail or toll-free number. The science fair prize and other CPS activities depend on the voluntary labor of CPS members and associates. New participants are needed to expand CPS activities and reach a larger audience. Send an e-mail to the CPS at CPS@plasmacoalition.org for information.

  4. Plasma-ARC spray-coatings of powders of self-fluxing iron-base alloys. 1. Estimation of the temperature and velocity of powder particles in the plasma flow

    SciTech Connect

    Nechiporenko, A.A.; Martsevoi, E.P.

    1995-07-01

    Mathematical simulation has been used to estimate the effect of technological factors on the variation of the temperature and velocity of particles of self-fluxing iron-base powder in a plasma flow of propane-butane combustion products. The influence of the plasma generator arc current, the flow rates of the plasma-forming gases and their relations, the powder particle size, the diameter of the plasma generator nozzle, the powder flow rate, and the spraying distance are analyzed. Optimal spraying conditions are determined for various powder fractions.

  5. Glow-to-arc transition in plasma-assisted combustion at 100 MPa

    NASA Astrophysics Data System (ADS)

    Larsson, A.; Andreasson, S.

    2015-04-01

    Electric energy can be added to the combustion of solid propellants in a gun in order to augment and to control parts of the internal ballistic cycle of the launch of a projectile. The pressure in the chamber and bore during launch is typically several hundred megapascal and the electric energy must be delivered to the flame at such a pressure level. To increase the understanding of the interaction between a flame and an electrical discharge at elevated pressure, experiments have been performed at 100 MPa in a combustion chamber where electric current has been conducted through the flame of a solid propellant. Pressure, voltage and current have been measured. The measured signals have been analysed and interpreted. The sequence of events has been interpreted as an initial formation of a glow-like discharge in the flame followed by a discharge mode transition to a filamentary arc discharge. The transition is shown to be dependent on the flame conductivity. For the test propellant used (Nzk5230 doped with 5% potassium nitrate), the flame conductivity is calculated to be 0.84 S m-1 and the discharge mode transition is found to occur after a dissipation of 0.2-0.4 kJ, or 11-22 kJ m-1 of electric energy, at an electric power of 0.1-0.5 MW.

  6. Hydrogen uptake in single-walled carbon nanotubes synthesized by the hydrogen arc plasma jet method.

    NASA Astrophysics Data System (ADS)

    Moreno-Ruiz, L. A.; Ortiz-Lopez, J.; de Ita de La Torre, A.; Arellano-Peraza, J. S.; Flores-Díaz, G.

    2006-03-01

    Carbon nanotubes were synthesized by a modified electric arc discharge method under hydrogen atmosphere using a catalytic mixture of powders with composition C/Ni/Co/Fe/FeS. The samples were characterized with transmission and scanning electron microscopy, Raman spectroscopy and thermo-gravimetric analysis. Unpurified samples contain 20 wt% of carbon nanotubes, 2 wt% of other forms of carbon and 78 wt% of catalytic metals. Adsorption/desorption of hydrogen in unpurified samples at atmospheric pressure measured with gravimetric methods was of the order of 2 wt%. Samples for these measurements were prepared with a three-step treatment: (i) oxidation in air for 30 min at 500 ^oC, (ii) ball- milling for 1 hr, and (iii) second oxidation in air for 30 min at 500 ^oC. This treatment was applied to eliminate other forms of carbon as well as to shorten the tubes and open their caps. Hydrogen desorption was also measured in degassed samples (400 ^oC for 20 min in vacuum) which adsorbed H2 while cooling to room temperature. Desorption in degassed/hydrogenated samples is a two-step process which we attribute to distinct desorption characteristics of nanotubes and of residual oxidized metal catalysts.

  7. Infrared fingerprints and periodic formation of nanoparticles in Ar/C2H2 plasmas

    NASA Astrophysics Data System (ADS)

    Kovačević, Eva; Stefanović, Ilija; Berndt, Johannes; Winter, Jörg

    2003-03-01

    The formation of dust particles in argon diluted C2H2 plasmas was studied by means of Fourier transform infrared absorption spectroscopy and mass spectroscopy. The detection limit for infrared absorption was significantly improved by the use of a multipass technique. Measuring the intensity of the Rayleigh/Mie scattering of the infrared signal we found a periodicity of dust formation/vanishing (period of about 35 min in our experimental conditions). The fast disappearance of the dust from the plasma region at the end of every period is the evidence of a narrow particle size distribution, as confirmed by secondary electron micrographs of the collected powder. Characteristic infrared absorption features have their origin in absorption within the dust particles. Besides the strong presence of aliphatic hydrocarbons characteristic for amorphous hydrocarbon films, a significant amount of aromatic structures was detected. Heavy positive ions measured by ion-mass spectroscopy originate from polyacetilenic (C2nH2) and aromatic compounds. Time resolved mass spectra gave insight into the plasma response to the dust formation.

  8. Simulation of radioelement volatility during the vitrification of radioactive wastes by arc plasma.

    PubMed

    Ghiloufi, Imed

    2009-04-15

    A computer model is used to simulate the volatility of some radioelements cesium ((137)Cs), cobalt ((60)Co), and ruthenium ((106)Ru) during the radioactive wastes vitrification by thermal plasma. This model is based on the calculation of system composition using the free enthalpy minimization method, coupled with the equation of mass transfer at the reactional interface. The model enables the determination of the effects of various parameters (e.g., temperature, plasma current, and matrix composition) on the radioelement volatility. The obtained results indicate that any increase in molten bath temperature causes an increase in the cobalt volatility; while ruthenium has a less obvious behavior. It is also found that the oxygen flux in the carrier gas supports the radioelement incorporations in the containment matrix, except in the case of the ruthenium which is more volatile under an oxidizing atmosphere. For electrolyses effects, an increase in the plasma current considerably increases both the vaporization speed and the vaporized quantities of (137)Cs and (60)Co. The increase of silicon percentage in the containment matrix supports the incorporation of (60)Co and (137)Cs in the matrix. The simulation results are compared favorably to the experimental measurements obtained by emission spectroscopy.

  9. Destruction of inorganic municipal solid waste incinerator fly ash in a DC arc plasma furnace.

    PubMed

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

    2010-09-15

    Due to the toxicity of dioxins, furans and heavy metals, there is a growing environmental concern on municipal solid waste incinerator (MSWI) fly ash in China. The purpose of this study is directed towards the volume-reduction of fly ash without any additive by thermal plasma and recycling of vitrified slag. This process uses extremely high-temperature in an oxygen-starved environment to completely decompose complex waste into very simple molecules. For developing the proper plasma processes to treat MSWI fly ash, a new crucible-type plasma furnace was built. The melting process metamorphosed fly ash to granulated slag that was less than 1/3 of the volume of the fly ash, and about 64% of the weight of the fly ash. The safety of the vitrified slag was tested. The properties of the slag were affected by the differences in the cooling methods. Water-cooled and composite-cooled slag showed more excellent resistance against the leaching of heavy metals and can be utilized as building material without toxicity problems.

  10. Internet and web projects for fusion plasma science and education. Final technical report

    SciTech Connect

    Eastman, Timothy E.

    1999-08-30

    The plasma web site at http://www.plasmas.org provides comprehensive coverage of all plasma science and technology with site links worldwide. Prepared to serve the general public, students, educators, researchers, and decision-makers, the site covers basic plasma physics, fusion energy, magnetic confinement fusion, high energy density physics include ICF, space physics and astrophysics, pulsed-power, lighting, waste treatment, plasma technology, plasma theory, simulations and modeling.

  11. Evaluation of Cooling Conditions for a High Heat Flux Testing Facility Based on Plasma-Arc Lamps

    SciTech Connect

    Charry, Carlos H.; Abdel-khalik, Said I.; Yoda, Minami; Sabau, Adrian S.; Snead, Lance Lewis

    2015-07-31

    The new Irradiated Material Target Station (IMTS) facility for fusion materials at Oak Ridge National Laboratory (ORNL) uses an infrared plasma-arc lamp (PAL) to deliver incident heat fluxes as high as 27 MW/m2. The facility is being used to test irradiated plasma-facing component materials as part of the joint US-Japan PHENIX program. The irradiated samples are to be mounted on molybdenum sample holders attached to a water-cooled copper rod. Depending on the size and geometry of samples, several sample holders and copper rod configurations have been fabricated and tested. As a part of the effort to design sample holders compatible with the high heat flux (HHF) testing to be conducted at the IMTS facility, numerical simulations have been performed for two different water-cooled sample holder designs using the ANSYS FLUENT 14.0 commercial computational fluid dynamics (CFD) software package. The primary objective of this work is to evaluate the cooling capability of different sample holder designs, i.e. to estimate their maximum allowable incident heat flux values. 2D axisymmetric numerical simulations are performed using the realizable k-ε turbulence model and the RPI nucleate boiling model within ANSYS FLUENT 14.0. The results of the numerical model were compared against the experimental data for two sample holder designs tested in the IMTS facility. The model has been used to parametrically evaluate the effect of various operational parameters on the predicted temperature distributions. The results were used to identify the limiting parameter for safe operation of the two sample holders and the associated peak heat flux limits. The results of this investigation will help guide the development of new sample holder designs.

  12. Evaluation of Cooling Conditions for a High Heat Flux Testing Facility Based on Plasma-Arc Lamps

    DOE PAGESBeta

    Charry, Carlos H.; Abdel-khalik, Said I.; Yoda, Minami; Sabau, Adrian S.; Snead, Lance Lewis

    2015-07-31

    The new Irradiated Material Target Station (IMTS) facility for fusion materials at Oak Ridge National Laboratory (ORNL) uses an infrared plasma-arc lamp (PAL) to deliver incident heat fluxes as high as 27 MW/m2. The facility is being used to test irradiated plasma-facing component materials as part of the joint US-Japan PHENIX program. The irradiated samples are to be mounted on molybdenum sample holders attached to a water-cooled copper rod. Depending on the size and geometry of samples, several sample holders and copper rod configurations have been fabricated and tested. As a part of the effort to design sample holders compatiblemore » with the high heat flux (HHF) testing to be conducted at the IMTS facility, numerical simulations have been performed for two different water-cooled sample holder designs using the ANSYS FLUENT 14.0 commercial computational fluid dynamics (CFD) software package. The primary objective of this work is to evaluate the cooling capability of different sample holder designs, i.e. to estimate their maximum allowable incident heat flux values. 2D axisymmetric numerical simulations are performed using the realizable k-ε turbulence model and the RPI nucleate boiling model within ANSYS FLUENT 14.0. The results of the numerical model were compared against the experimental data for two sample holder designs tested in the IMTS facility. The model has been used to parametrically evaluate the effect of various operational parameters on the predicted temperature distributions. The results were used to identify the limiting parameter for safe operation of the two sample holders and the associated peak heat flux limits. The results of this investigation will help guide the development of new sample holder designs.« less

  13. Education Outreach at MIT Plasma Science and Fusion Center

    NASA Astrophysics Data System (ADS)

    Censabella, V.; Rivenberg, P.

    1999-11-01

    Outreach at the MIT PSFC consists of volunteers working together to increase the public's knowledge of fusion and plasma-related experiments. Seeking to generate excitement about science, engineering and mathematics, the PSFC holds a number of outreach activities throughout the year, such as Middle and High School Outreach Days. Outreach also includes the Mr. Magnet Program, which uses an interactive strategy to engage elementary school children. The PSFC maintains a Home Page on the World Widee Web, which can be reached at http://psfc.mit.edu.

  14. Oxygen reduction reaction activity and structural stability of Pt-Au nanoparticles prepared by arc-plasma deposition.

    PubMed

    Takahashi, Shuntaro; Chiba, Hiroshi; Kato, Takashi; Endo, Shota; Hayashi, Takehiro; Todoroki, Naoto; Wadayama, Toshimasa

    2015-07-28

    The oxygen reduction reaction (ORR) activity and durability of various Au(x)/Pt100 nanoparticles (where x is the atomic ratio of Au against Pt) are evaluated herein. The samples were fabricated on a highly-oriented pyrolytic graphite substrate at 773 K through sequential arc-plasma depositions of Pt and Au. The electrochemical hydrogen adsorption charges (electrochemical surface area), particularly the characteristic currents caused by the corner and edge sites of the Pt nanoparticles, decrease with increasing Au atomic ratio (x). In contrast, the specific ORR activities of the Au(x)/Pt100 samples were dependent on the atomic ratios of Pt and Au: the Au28/Pt100 sample showed the highest specific activity among all the investigated samples (x = 0-42). As for ORR durability evaluated by applying potential cycles between 0.6 and 1.0 V in oxygen-saturated 0.1 M HClO4, Au28/Pt100 was the most durable sample against the electrochemical potential cycles. The results clearly showed that the Au atoms located at coordinatively-unsaturated sites, e.g. at the corners or edges of the Pt nanoparticles, can improve the ORR durability by suppressing unsaturated-site-induced degradation of the Pt nanoparticles. PMID:26118789

  15. Coating Bores of Light Metal Engine Blocks with a Nanocomposite Material using the Plasma Transferred Wire Arc Thermal Spray Process

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Ernst, F.; Zwick, J.; Schlaefer, T.; Cook, D.; Nassenstein, K.; Schwenk, A.; Schreiber, F.; Wenz, T.; Flores, G.; Hahn, M.

    2008-09-01

    Engine blocks of modern passenger car engines are generally made of light metal alloys, mostly hypoeutectic AlSi-alloys. Due to their low hardness, these alloys do not meet the tribological requirements of the system cylinder running surface—piston rings—lubricating oil. In order to provide a suitable cylinder running surface, nowadays cylinder liners made of gray cast iron are pressed in or cast into the engine block. A newer approach is to apply thermal spray coatings onto the cylinder bore walls. Due to the geometric conditions, the coatings are applied with specifically designed internal diameter thermal spray systems. With these processes a broad variety of feedstock can be applied, whereas mostly low-alloyed carbon steel feedstock is being used for this application. In the context of this work, an iron-based wire feedstock has been developed, which leads to a nanocrystalline coating. The application of this material was carried out with the Plasma Transferred Wire Arc system. AlMgSi0.5 liners were used as substrates. The coating microstructure and the properties of the coatings were analyzed.

  16. Hard coating of ultrananocrystalline diamond/nonhydrogenated amorphous carbon composite films on cemented tungsten carbide by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Naragino, Hiroshi; Egiza, Mohamed; Tominaga, Aki; Murasawa, Koki; Gonda, Hidenobu; Sakurai, Masatoshi; Yoshitake, Tsuyoshi

    2016-08-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were deposited on cemented carbide containing Co by coaxial arc plasma deposition. With decreasing substrate temperature, the hardness was enhanced accompanied by an enhancement in the sp3/(sp2 + sp3). Energy-dispersive X-ray and secondary ion mass spectrometry spectroscopic measurements exhibited that the diffusion of Co atoms from the substrates into the films hardly occurs. The film deposited at room temperature exhibited the maximum hardness of 51.3 GPa and Young's modulus of 520.2 GPa, which evidently indicates that graphitization induced by Co in the WC substrates, and thermal deformation from sp3 to sp2 bonding are suppressed. The hard UNCD/a-C films can be deposited at a thickness of approximately 3 μm, which is an order larger than that of comparably hard a-C films. The internal compressive stress of the 51.3-GPa film is 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. This is a reason for the thick deposition. The presence of a large number of grain boundaries in the film, which is a structural specific to UNCD/a-C films, might play a role in releasing the internal stress of the films.

  17. Magnetospheric and Plasma Science with Cassini-Huygens

    NASA Astrophysics Data System (ADS)

    Blanc, M.; Bolton, S.; Bradley, J.; Burton, M.; Cravens, T. E.; Dandouras, I.; Dougherty, M. K.; Festou, M. C.; Feynman, J.; Johnson, R. E.; Gombosi, T. G.; Kurth, W. S.; Liewer, P. C.; Mauk, B. H.; Maurice, S.; Mitchell, D.; Neubauer, F. M.; Richardson, J. D.; Shemansky, D. E.; Sittler, E. C.; Tsurutani, B. T.; Zarka, Ph.; Esposito, L. W.; Grün, E.; Gurnett, D. A.; Kliore, A. J.; Krimigis, S. M.; Southwood, D.; Waite, J. H.; Young, D. T.

    2002-07-01

    Magnetospheric and plasma science studies at Saturn offer a unique opportunity to explore in-depth two types of magnetospheres. These are an ‘induced’ magnetosphere generated by the interaction of Titan with the surrounding plasma flow and Saturn's ‘intrinsic’ magnetosphere, the magnetic cavity Saturn's planetary magnetic field creates inside the solar wind flow. These two objects will be explored using the most advanced and diverse package of instruments for the analysis of plasmas, energetic particles and fields ever flown to a planet. These instruments will make it possible to address and solve a series of key scientific questions concerning the interaction of these two magnetospheres with their environment. The flow of magnetospheric plasma around the obstacle, caused by Titan's atmosphere/ionosphere, produces an elongated cavity and wake, which we call an ‘induced magnetosphere’. The Mach number characteristics of this interaction make it unique in the solar system. We first describe Titan's ionosphere, which is the obstacle to the external plasma flow. We then study Titan's induced magnetosphere, its structure, dynamics and variability, and discuss the possible existence of a small intrinsic magnetic field of Titan. Saturn's magnetosphere, which is dynamically and chemically coupled to all other components of Saturn's environment in addition to Titan, is then described. We start with a summary of the morphology of magnetospheric plasma and fields. Then we discuss what we know of the magnetospheric interactions in each region. Beginning with the innermost regions and moving outwards, we first describe the region of the main rings and their connection to the low-latitude ionosphere. Next the icy satellites, which develop specific magnetospheric interactions, are imbedded in a relatively dense neutral gas cloud which also overlaps the spatial extent of the diffuse E ring. This region constitutes a very interesting case of direct and mutual coupling

  18. The Science on Saturday Program at Princeton Plasma Physics Laboratory

    NASA Astrophysics Data System (ADS)

    Bretz, N.; Lamarche, P.; Lagin, L.; Ritter, C.; Carroll, D. L.

    1996-11-01

    The Science on Saturday Program at Princeton Plasma Physics Laboratory consists of a series of Saturday morning lectures on various topics in science by scientists, engineers, educators, and others with an interesting story. This program has been in existence for over twelve years and has been advertised to and primarily aimed at the high school level. Topics ranging from superconductivity to computer animation and gorilla conservation to pharmaceutical design have been covered. Lecturers from the staff of Princeton, Rutgers, AT and T, Bristol Meyers Squibb, and many others have participated. Speakers have ranged from Nobel prize winners, astronauts, industrialists, educators, engineers, and science writers. Typically, there are eight to ten lectures starting in January. A mailing list has been compiled for schools, science teachers, libraries, and museums in the Princeton area. For the past two years AT and T has sponsored buses for Trenton area students to come to these lectures and an effort has been made to publicize the program to these students. The series has been very popular, frequently overfilling the 300 seat PPPL auditorium. As a result, the lectures are videotaped and broadcast to a large screen TV for remote viewing. Lecturers are encouraged to interact with the audience and ample time is provided for questions.

  19. Deposition of duplex Al 2O 3/aluminum coatings on steel using a combined technique of arc spraying and plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Gu, Weichao; Shen, Dejiu; Wang, Yulin; Chen, Guangliang; Feng, Wenran; Zhang, Guling; Fan, Songhua; Liu, Chizi; Yang, Size

    2006-02-01

    Plasma electrolytic oxidation (PEO) is a cost-effective technique that can be used to prepare ceramic coatings on metals such as Ti, Al, Mg, Nb, etc., and their alloys, but this promising technique cannot be used to modify the surface properties of steels, which are the most widely used materials in engineering. In order to prepare metallurgically bonded ceramic coatings on steels, a combined technique of arc spraying and plasma electrolytic oxidation (PEO) was adopted. In this work, metallurgically bonded ceramic coatings on steels were obtained using this method. We firstly prepared aluminum coatings on steels by arc spraying, and then obtained the metallurgically bonded ceramic coatings on aluminum coatings by PEO. The characteristics of duplex coatings were analyzed by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The corrosion and wear resistance of the ceramic coatings were also studied. The results show that, duplex Al 2O 3/aluminum coatings have been deposited on steel substrate after the combined treatment. The ceramic coatings are mainly composed of α-Al 2O 3, γ-Al 2O 3, θ-Al 2O 3 and some amorphous phase. The duplex coatings show favorable corrosion and wear resistance properties. The investigations indicate that the combination of arc spraying and plasma electrolytic oxidation proves a promising technique for surface modification of steels for protective purposes.

  20. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    PubMed Central

    Franz, Robert; Polcik, Peter; Anders, André

    2015-01-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings. PMID:26120236

  1. Plasma and trap-based techniques for science with positrons

    NASA Astrophysics Data System (ADS)

    Danielson, J. R.; Dubin, D. H. E.; Greaves, R. G.; Surko, C. M.

    2015-01-01

    In recent years, there has been a wealth of new science involving low-energy antimatter (i.e., positrons and antiprotons) at energies ranging from 102 to less than 10-3 eV . Much of this progress has been driven by the development of new plasma-based techniques to accumulate, manipulate, and deliver antiparticles for specific applications. This article focuses on the advances made in this area using positrons. However, many of the resulting techniques are relevant to antiprotons as well. An overview is presented of relevant theory of single-component plasmas in electromagnetic traps. Methods are described to produce intense sources of positrons and to efficiently slow the typically energetic particles thus produced. Techniques are described to trap positrons efficiently and to cool and compress the resulting positron gases and plasmas. Finally, the procedures developed to deliver tailored pulses and beams (e.g., in intense, short bursts, or as quasimonoenergetic continuous beams) for specific applications are reviewed. The status of development in specific application areas is also reviewed. One example is the formation of antihydrogen atoms for fundamental physics [e.g., tests of invariance under charge conjugation, parity inversion, and time reversal (the CPT theorem), and studies of the interaction of gravity with antimatter]. Other applications discussed include atomic and materials physics studies and the study of the electron-positron many-body system, including both classical electron-positron plasmas and the complementary quantum system in the form of Bose-condensed gases of positronium atoms. Areas of future promise are also discussed. The review concludes with a brief summary and a list of outstanding challenges.

  2. The statistical difference between bending arcs and regular polar arcs

    NASA Astrophysics Data System (ADS)

    Kullen, A.; Fear, R. C.; Milan, S. E.; Carter, J. A.; Karlsson, T.

    2015-12-01

    In this work, the Polar UVI data set by Kullen et al. (2002) of 74 polar arcs is reinvestigated, focusing on bending arcs. Bending arcs are typically faint and form (depending on interplanetary magnetic field (IMF) By direction) on the dawnside or duskside oval with the tip of the arc splitting off the dayside oval. The tip subsequently moves into the polar cap in the antisunward direction, while the arc's nightside end remains attached to the oval, eventually becoming hook-shaped. Our investigation shows that bending arcs appear on the opposite oval side from and farther sunward than most regular polar arcs. They form during By-dominated IMF conditions: typically, the IMF clock angle increases from 60 to 90° about 20 min before the arc forms. Antisunward plasma flows from the oval into the polar cap just poleward of bending arcs are seen in Super Dual Auroral Radar Network data, indicating dayside reconnection. For regular polar arcs, recently reported characteristics are confirmed in contrast to bending arcs. This includes plasma flows along the nightside oval that originate close to the initial arc location and a significant delay in the correlation between IMF By and initial arc location. In our data set, the highest correlations are found with IMF By appearing at least 1-2 h before arc formation. In summary, bending arcs are distinctly different from regular arcs and cannot be explained by existing polar arc models. Instead, these results are consistent with the formation mechanism described in Carter et al. (2015), suggesting that bending arcs are caused by dayside reconnection.

  3. Mechanical properties and platelet adhesion behavior of diamond-like carbon films synthesized by pulsed vacuum arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Leng, Y. X.; Chen, J. Y.; Yang, P.; Sun, H.; Wan, G. J.; Huang, N.

    2003-05-01

    Diamond-like carbon (DLC) is an attractive biomedical material due to its high inertness and excellent mechanical properties. In this study, DLC films were fabricated on Ti6Al4V and Si(1 0 0) substrates at room temperature by pulsed vacuum arc plasma deposition. By changing the argon flow from 0 to 13 sccm during deposition, the effects of argon flow on the characteristics of the DLC films were systematically examined to correlate to the blood compatibility. The microstructure and mechanical properties of the films were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) surface analysis, a nano-indenter and pin-on-disk tribometer. The blood compatibility of the films was evaluated using in vitro platelet adhesion investigation, and the quantity and morphology of the adherent platelets was investigated employing optical microscopy and scanning electron microscopy. The Raman spectroscopy results showed a decreasing sp 3 fraction (an increasing trend in ID/ IG ratio) with increasing argon flow from 0 to 13 sccm. The sp 3:sp 2 ratio of the films was evaluated from the deconvoluted XPS spectra. We found that the sp 3 fraction decreased as the argon flow was increased from 0 to 13 sccm, which is consistent with the results of the Raman spectra. The mechanical properties results confirmed the decreasing sp 3 content with increasing argon flow. The Raman D-band to G-band intensity ratio increased and the platelet adhesion behavior became better with higher flow. This implies that the blood compatibility of the DLC films is influenced by the sp 3:sp 2 ratio. DLC films deposited on titanium alloys have high wear resistance, low friction and good adhesion.

  4. Electrical properties of a-C:Mo films produced by dual-cathode filtered cathodic arc plasma deposition

    SciTech Connect

    Sansongsiri, Sakon; Anders, Andre; Yodsombat, Banchob

    2008-01-20

    Molybdenum-containing amorphous carbon (a-C:Mo) thin films were prepared using a dual-cathode filtered cathodic arc plasma source with a molybdenum and a carbon (graphite) cathode. The Mo content in the films was controlled by varying the deposition pulse ratio of Mo and C. Film sheet resistance was measured in situ at process temperature, which was close to room temperature, as well as ex situ as a function of temperature (300-515 K) in ambient air. Film resistivity and electrical activation energy were derived for different Mo and C ratios and substrate bias. Film thickness was in the range 8-28 nm. Film resistivity varied from 3.55x10-4 Omega m to 2.27x10-6 Omega m when the Mo/C pulse ratio was increased from 0.05 to 0.4, with no substrate bias applied. With carbon-selective bias, the film resistivity was in the range of 4.59x10-2 and 4.05 Omega m at a Mo/C pulse ratio of 0.05. The electrical activation energy decreased from 3.80x10-2 to 3.36x10-4 eV when the Mo/C pulse ratio was increased in the absence of bias, and from 0.19 to 0.14 eV for carbon-selective bias conditions. The resistivity of the film shifts systematically with the amounts of Mo and upon application of substrate bias voltage. The intensity ratio of the Raman D-peak and G-peak (ID/IG) correlated with the pre-exponential factor (sigma 0) which included charge carrier density and density of states.

  5. Purification of Cu by hydrogen plasma-arc zone melting and characterization of trace impurities by secondary ion mass spectrometry

    SciTech Connect

    Lalev, G.M.; Lim, J.-W. Munirathnam, N.R. Choi, G.-S.; Uchikoshi, M.; Mimura, K.; Isshiki, M.

    2009-01-15

    Purification of 4N (99.99%) and 6N (99.9999%) purity Cu rods by hydrogen plasma-arc zone melting was carried out. Weight loss in the 4N and 6N Cu rods as a function of number of zone refined passes revealed a higher rate of impurity removal by vaporization in 4N Cu when compared to 6N Cu. Purification effect was studied by analyzing major impurities like Mg, Si, Ca, Ti, Cr, Ni and Fe by O{sub 2}{sup +} ions and C, O, As, Cl, P and S by Cs{sup +} ion sources using secondary ion mass spectrometry. A remarkable decrease of Si, Ti and Fe impurity concentrations in Cu at x/L = 0.03 after 10 zone passes was observed, but no similar purification effect along the remaining length of the zone refined copper rod was observed. Mg, Se and Ca in the Cu rods were reduced faster by a high evaporation effect due to P{sub i}/P{sub Cu} > 10{sup 2}. On the other hand, removal of O, C, S and Se was expectedly dominated by vaporization in the form of H{sub 2}O, CH{sub 4,} H{sub 2}S, and H{sub 2}Se through thermodynamically favored reactions. The overall segregation rate of the individual impurity elements was decreased with an increase in the purity from 4N to 6N of Cu rods. SIMS analysis of trace impurities was successfully carried out on HPZM Cu for quantitative estimation.

  6. Microstructure and wear properties of WC particle reinforced composite coating on Ti6Al4V alloy produced by the plasma transferred arc method

    NASA Astrophysics Data System (ADS)

    Çelik, Osman Nuri

    2013-06-01

    The microstructure and wear properties of a WC particle reinforced composite coating produced by the plasma transferred arc (PTA) method on Ti6Al4V alloy were investigated in this study. PTA processing was carried out using argon as the plasma gas at arc current values of 70 A, 80 A and 90 A. Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterize the microstructure of the composite layer formed on the surface of a Ti6Al4V substrate. The results indicate that the WC, TiC and W2C carbide phases formed in the composite layers produced by PTA on the surface of the Ti6Al4V alloy. The distributions and volume fractions of these phases were found to vary with the arc current values. Wear tests were performed under dry sliding conditions using a linear ball-on-disc geometry. The microhardness and wear resistances of all of the composite layers produced by the PTA process were enhanced relative to those of the Ti6Al4V substrate. The homogeneity and volume fractions of the carbide phases in the composite layers were responsible for the improvement in the wear resistance of the alloy. The wear test results indicate that the alloy modified at 70 A shows better wear resistance than the alloys modified at 80 A and 90 A.

  7. Remote automatic plasma arc-closure welding of a dry-storage canister for spent nuclear fuel and high-level radioactive waste

    SciTech Connect

    Sprecace, R.P.; Blankenship, W.P.

    1982-12-31

    A carbon steel storage canister has been designed for the dry encapsulation of spent nuclear fuel assemblies or of logs of vitrified high level radioactive waste. The canister design is in conformance with the requirements of the ASME Code, Section III, Division 1 for a Class 3 vessel. The canisters will be loaded and sealed as part of a completely remote process sequence to be performed in the hot bay of an experimental encapsulation facility at the Nevada Test Site. The final closure to be made is a full penetration butt weld between the canister body, a 12.75-in O.D. x 0.25-in wall pipe, and a mating semiellipsoidal closure lid. Due to a combination of design, application and facility constraints, the closure weld must be made in the 2G position (canister vertical). The plasma arc welding system is described, and the final welding procedure is described and discussed in detail. Several aspects and results of the procedure development activity, which are of both specific and general interest, are highlighted; these include: The critical welding torch features which must be exactly controlled to permit reproducible energy input to, and gas stream interaction with, the weld puddle. A comparison of results using automatic arc voltage control with those obtained using a mechanically fixed initial arc gap. The optimization of a keyhole initiation procedure. A comparison of results using an autogenous keyhole closure procedure with those obtained using a filler metal addition. The sensitivity of the welding process and procedure to variations in joint configuration and dimensions and to variations in base metal chemistry. Finally, the advantages and disadvantages of the plasma arc process for this application are summarized from the current viewpoint, and the applicability of this process to other similar applications is briefly indicated.

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

    SciTech Connect

    Evans, P.J.; Noorman, J.T.; Watt, G.C.

    1996-08-01

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

  9. Education Outreach at MIT Plasma Science Fusion Center

    NASA Astrophysics Data System (ADS)

    Censabella, V.; Nachtrieb, R.; Rivenberg, P.

    1998-11-01

    Outreach at the MIT PSFC consists of volunteers working together to increase the public's knowledge of fusion and plasma-related experiments. Seeking to generate excitement about science, engineering and mathematics, the PSFC holds a number of outreach activities throughout the year, such as Middle and High School Outreach Days. Outreach also includes the Mr. Magnet Program, which uses an interactive strategy to engage elementary school children. Included in this year's presentation will be a live demo of a compressed-air bottle rocket (really a one-liter plastic soda bottle) for use in high school science classrooms that researchers at the Cambridge Physics Outlet (a PSFC spin-off company) have developed. To prepare the rocket for launch, the bottle is filled with compressed air at pressures up to 80 psi and the end is plugged. The rocket is released when the plug is pulled. The gas escapes at supersonic velocities and accelerates the bottle at over 1000 m/s^2. The velocity of the bottle is measured at many locations along its ``trajectory". A simple thermodynamic model predicts performance in excellent agreement with observation. The PSFC maintains a Home Page on the World Wide Web, which can be reached at http://pfc.mit.edu.

  10. Laboratory experiments on arc deflection and instability

    SciTech Connect

    Zweben, S.; Karasik, M.

    2000-03-21

    This article describes experiments on arc deflection instability carried out during the past few years at the Princeton University Plasma Physics Laboratory (PPPL). The approach has been that of plasma physicists interested in arcs, but they believe these results may be useful to engineers who are responsible for controlling arc behavior in large electric steel furnaces.

  11. Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe11.6Si1.4

    NASA Astrophysics Data System (ADS)

    Shamba, P.; Morley, N. A.; Cespedes, O.; Reaney, I. M.; Rainforth, W. M.

    2016-08-01

    LaFe11.6Si1.4 alloy has been synthesized in polycrystalline form using both arc melting and spark plasma sintering (SPS). The phase formation, hysteresis loss and magnetocaloric properties of the LaFe11.6Si1.4 alloys synthesized using the two different techniques are compared. The annealing time required to obtain the 1:13 phase is significantly reduced from 14 days (using the arc melting technique) to 30 min (using the SPS technique). The magnetic entropy change (Δ S M) for the arc-melted LaFe11.6Si1.4 compound, obtained for a field change of 5 - 0 T (decreasing field), was estimated to be 19.6 J kg-1 K-1. The effective RCP at 5 T of the arc-melted LaFe11.6Si1.4 compound was determined to be 360 J kg-1 which corresponds to about 88 % of that observed in Gd. A significant reduction in the hysteretic losses in the SPS LaFe11.6Si1.4 compound was observed. The Δ S M, obtained for a field change of 5 - 0 T (decreasing field), for the SPS LaFe11.6Si1.4 compound decreases to 7.4 J kg-1 K-1. The T C also shifts from 186 (arc-melted) to 230 K (SPS) and shifts the order of phase transition from first to second order, respectively. The MCE of the SPS LaFe11.6Si1.4 compound spreads over a larger temperature range with the RCP value at 5 T reaching 288 J kg-1 corresponding to about 70 % of that observed in Gd. At low fields, the effective RCP values of the arc-melted and spark plasma-sintered LaFe11.6Si1.4 compounds are comparable, thereby clearly demonstrating the potential of SPS LaFe11.6Si1.4 compounds in low-field magnetic refrigeration applications.

  12. Computation of emission characteristics of Ar-Fe arc plasma column during the synthesis of nano particles of Fe-oxides

    NASA Astrophysics Data System (ADS)

    Banerjee, I.; Sahasrabudhe, S. N.; Bhoraskar, S. V.; Das, A. K.

    2006-08-01

    The article reports the results of the computationally determined radiative emission characteristics of a transferred arc argon plasma source used in plasma-assisted nano particles synthesis of Fe-oxides. A thermodynamic code uses a spectroscopic database to compute internal partition functions and densities of various charged states in argon-iron vapor plasma system during the synthesis of Fe-oxides. The net amount of radiation emitted by the plasma at different axial positions along the column has been monitored by optical emission spectroscopy. It was also used to determine the amount of metal vapors mixing inside the plasma column during the synthesis process. The net emission coefficient estimated along a certain line of sight shows an effective increase even for a small inclusion of Fe vapors (0.11%) inside the column. It has been noticed that the radiations emitted by the plasma inside the reactor chamber might also be one of the factors, controlling the crystalline phase of Fe-oxide particles.

  13. Early surface microhardness of a resin composite exposed to a pulse-delayed curing exposure: a comparison of a tungsten halogen and a plasma arc lamp, in vitro.

    PubMed

    Ray, Noel J; Lynch, Christopher D; Burke, Francis M; Hannigan, Ailish

    2005-12-01

    Surface microhardness numbers of a commercial resin composite have been compared after exposure to a quartz tungsten halogen (QTH) and plasma arc (PAC) lamp respectively, using two exposure protocols. The effect of increased tip-to-composite distance has also been compared. Exposure with the PAC lamp tested is more appropriate to the early finishing of composite restorations after placement and curing than with the QTH. However both lamps were capable of producing comparable surface hardness, with appropriate exposure protocols. The effect of increased tip-to-composite distance was generally not significant between the lamps for continuous exposure. PMID:16411575

  14. Properties of the ZrO2 and TiO2 coatings deposited by plasma-assisted arc spraying onto an E110 zirconium alloy

    NASA Astrophysics Data System (ADS)

    Chernov, I. P.; Berezneeva, E. V.; Pushilina, N. S.; Kudiyarov, V. N.; Koval', N. N.; Krysina, O. V.; Shugurov, V. V.; Ivanova, S. V.; Nikolaeva, A. N.

    2015-02-01

    The structure, the physicomechanical properties, and the hydrogen penetration in the volume of an E110 alloy with a ZrO2 or TiO2 coating deposited by a vacuum-arc plasma-assisted method are studied. These coatings increase the wear resistance, the hardness, and the adhesion properties of the zirconium alloy. The ZrO2 coating is found to decrease the rate of hydrogen absorption by a Zr-1% Nb alloy as compared to the initial material at a hydrogenation temperature of 450°C.

  15. Organization by Gordon Research Conferences of the 2012 Plasma Processing Science Conference 22-27 July 2012

    SciTech Connect

    Chang, Jane

    2012-07-27

    The 2012 Gordon Research Conference on Plasma Processing Science will feature a comprehensive program that will highlight the most cutting edge scientific advances in plasma science and technology as well as explore the applications of this nonequilibrium medium in possible approaches relative to many grand societal challenges. Fundamental science sessions will focus on plasma kinetics and chemistry, plasma surface interactions, and recent trends in plasma generation and multi-phase plasmas. Application sessions will explore the impact of plasma technology in renewable energy, the production of fuels from renewable feedstocks and carbon dioxide neutral solar fuels (from carbon dioxide and water), and plasma-enabled medicine and sterilization.

  16. A Plasma Science Education Laboratory for K-16 Students and Teachers

    NASA Astrophysics Data System (ADS)

    Post Zwicker, Andrew; Hulse, R. A.; Gershman, Sophia

    2002-11-01

    In the Summer 2002, a major new science education laboratory was created at PPPL. The new laboratory significantly increasing our educational opportunities for teachers and students at all levels, both locally and nationally, especially for those that are underrepresented in math, science, and technology. Recent collaborations include partnerships with The Lewis School, a private school of grades 6-12 for "learning different" students (redesigning their physics and physical science curricula), Douglass College (programs designed for undergraduate and high school women interested in math, science, or engineering) and the science museum The Franklin Institute (creating teacher and student plasma workshops for their educational programs). The Plasma Science Education Laboratory is more than 3600 sq. ft. and is designed as a laboratory and a classroom, with the general lab space easily changed depending upon the type of use. The flexible layout allows for a unique combination of curricula design and direct plasma education. Small rooms are set aside for advanced projects. Other activities in the laboratory include research with small plasma sources, typically a DC glow discharge, that pairs an advanced high school student with an undergraduate physics major. Research topics include high speed video imagery and analysis of classroom plasmas (Jacob's ladder, plasma ball), investigations of plasmas that mimic biological systems, creation of new plasma sources for classroom use.

  17. Vacuum arc deposition devices

    NASA Astrophysics Data System (ADS)

    Boxman, R. L.; Zhitomirsky, V. N.

    2006-02-01

    The vacuum arc is a high-current, low-voltage electrical discharge which produces a plasma consisting of vaporized and ionized electrode material. In the most common cathodic arc deposition systems, the arc concentrates at minute cathode spots on the cathode surface and the plasma is emitted as a hypersonic jet, with some degree of contamination by molten droplets [known as macroparticles (MPs)] of the cathode material. In vacuum arc deposition systems, the location and motion of the cathode spots are confined to desired surfaces by an applied magnetic field and shields around undesired surfaces. Substrates are mounted on a holder so that they intercept some portion of the plasma jet. The substrate often provides for negative bias to control the energy of depositing ions and heating or cooling to control the substrate temperature. In some systems, a magnetic field is used to guide the plasma around an obstacle which blocks the MPs. These elements are integrated with a deposition chamber, cooling, vacuum gauges and pumps, and power supplies to produce a vacuum arc deposition system.

  18. Vacuum arc deposition devices

    SciTech Connect

    Boxman, R.L.; Zhitomirsky, V.N.

    2006-02-15

    The vacuum arc is a high-current, low-voltage electrical discharge which produces a plasma consisting of vaporized and ionized electrode material. In the most common cathodic arc deposition systems, the arc concentrates at minute cathode spots on the cathode surface and the plasma is emitted as a hypersonic jet, with some degree of contamination by molten droplets [known as macroparticles (MPs)] of the cathode material. In vacuum arc deposition systems, the location and motion of the cathode spots are confined to desired surfaces by an applied magnetic field and shields around undesired surfaces. Substrates are mounted on a holder so that they intercept some portion of the plasma jet. The substrate often provides for negative bias to control the energy of depositing ions and heating or cooling to control the substrate temperature. In some systems, a magnetic field is used to guide the plasma around an obstacle which blocks the MPs. These elements are integrated with a deposition chamber, cooling, vacuum gauges and pumps, and power supplies to produce a vacuum arc deposition system.

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

    NASA Astrophysics Data System (ADS)

    Lukas, Joseph Nicholas

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

  20. The Influence of Contact Space on Arc Commutation Process in Air Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Niu, Chunping; Ding, Juwen; Yang, Fei; Dong, Delong; Rong, Mingzhe; Xu, Dan

    2016-05-01

    In this paper, a 3D magneto-hydrodynamic (MHD) arc simulation model is applied to analyze the arc motion during current interruption in a certain air circuit breaker (ACB). The distributions of pressure, temperature, gas flow and current density of the arc plasma in the arc region are calculated, and the factors influencing the commutation process are analyzed according to the calculated results. Based on the airflow in the arc chamber, the causes of arc commutation asynchrony and the back commutation are investigated. It indicates that a reasonable contact space design is crucial to a successful arc commutation process. To verify the simulation results, the influence of contact space on arc voltage and arc commutation is tested. This research can provide methods and references to the optimization of ACB design. supported by National Key Basic Research Program of China (973 Program) (Nos. 2015CB251002, 6132620303) and National Natural Science Foundation of China (Nos. 51221005, 51377128, 51577144), and Science and Technology Project Through Grid State Corporation (No. SGSNKYOOKJJS1501564)

  1. Determination of the number densities of CH(X2Π) and CH(A2Δ) radicals in a DC cascaded arc discharge plasma

    NASA Astrophysics Data System (ADS)

    Wu, Xingwei; Li, Cong; Wang, Yong; Wang, Zhiwei; Feng, Chunlei; Ding, Hongbin

    2015-09-01

    A combination of optical emission spectroscopy (OES) and cavity ring-down spectroscopy (CRDS) has enabled to determinate the number densities of CH(A2Δ) and CH(X2Π) radicals simultaneously in a cascaded arc plasma reactor operating with a CH4/Ar mixture. It is found that the number density of CH(A2Δ) radical increases with discharge current at first and then decreases. However, the number density of CH(X2Π) radical decreases with discharge current when the rate of CH4 flow to total flow is lower than 1 %, while it increases slightly with discharge current when the rate is 1.5 %. The results reveal that CH radicals are deviation from excitation equilibrium. Although OES is the simplest and most straightforward means to investigate the CH radical behavior, it is not enough to provide the information of the CH(X2Π) number density, and additional methods, such as CRDS, are needed in the cascaded arc plasma jet.

  2. Effect of N{sub 2} and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes

    SciTech Connect

    Zhirkov, Igor Rosen, Johanna; Oks, Efim

    2015-06-07

    DC arc plasma from Ti, Al, and Ti{sub 1−x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N{sub 2} pressures in the range 10{sup −6} to 3 × 10{sup −2} Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. Introducing N{sub 2} above ∼5 × 10{sup −3} Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N{sub 2} atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.

  3. PREFACE: 11th Asia-Pacific Conference on Plasma Science and Technology (APCPST-11) and 25th Symposium on Plasma Science for Materials (SPSM-25)

    NASA Astrophysics Data System (ADS)

    Watanabe, Takayuki; Kaneko, Toshio; Sekine, Makoto; Tanaka, Yasunori

    2013-06-01

    The 11th Asia-Pacific Conference on Plasma Science and Technology (APCPST-11) was held in Kyoto, Japan on 2-5 October 2012 with the 25th Symposium on Plasma Science for Materials (SPSM-25). SPSM has been held annually since 1988 under the sponsorship of The 153rd Committee on Plasma Materials Science, Japan Society for the Promotion of Science (JSPS). This symposium is one of the major activities of the Committee, which is organized by researchers in academia and industry for the purpose of advancing intersectional scientific information exchange and discussion of science and technology of plasma materials processing. APCPST and SPSM are jointly held biennially to survey the current status of low temperature and thermal plasma physics and chemistry for industrial applications. The whole area of plasma processing was covered from fundamentals to applications. Previous meetings were held in China, Japan, Korea, and Australia, attended by scientists from the Asia-Pacific and other countries. The joint conference was organized in plenary lectures, invited, contributed oral presentations and poster sessions. At this meeting, we had 386 participants from 10 countries and 398 presentations, including 26 invited presentations. This year, we arranged special topical sessions that covered green innovation, life innovation, and technical reports from industry. This conference seeks to bring the plasma community together and to create a forum for discussing the latest developments and issues, the challenges ahead in the field of plasma research and applications among engineers and scientists in Asia, the Pacific Rim, as well as Europe. This volume presents 44 papers that were selected via a strict peer-review process from full papers submitted for the proceedings of the conference. The topics range from the basic physics and chemistry of plasma processing to a broad variety of materials processing and environmental applications. This volume offers an overview of recent

  4. Fluorocarbon assisted atomic layer etching of SiO2 and Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

    DOE PAGESBeta

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-11

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C4F8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C4F8 injection and synchronized plasma-based low energy Ar+ ion bombardment has been established for SiO2.1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF3 as a precursor is examined and compared to C4F8. CHF3 is shown to enable selective SiO2/Si etching using a fluorocarbon (FC) film build up. Othermore » critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

  5. Circuit model of surface arcing

    SciTech Connect

    Robiscoe, R.T.; Sui, Z.

    1988-11-01

    An electrical breakdown on a highly charged dielectric surface can result in a discharge along the surface, i.e., a flashover arc. We construct a simple circuit model for such an arc: the discharge of a capacitor C (related to the initial charged area) through a series inductor L and resistor R (related to the arc considered as a plasma). The arc current assumes a very simple form over most of its dynamic range, and such measured arc quantities as total charge transport, pulse width, peak current, and rise time are easily calculated. Moreover, straightforward a priori estimates of C, L, and R values give calculated arc quantities in good agreement with observation, for both typical magnitudes and areal scaling. We also analyze the effect on areal scaling of allowing the arc resistance R to ''switch'' during the evolution of the arc, from a small value characteristic of the arc plasma to a large value characteristic of the dielectric surface. Finally, we consider some aspects of the electromagnetic radiation generated by the arc.

  6. Alternating-Polarity Arc Welding

    NASA Technical Reports Server (NTRS)

    Schwinghamer, R. J.

    1987-01-01

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

  7. PREFACE: 26th Symposium on Plasma Science for Materials (SPSM-26)

    NASA Astrophysics Data System (ADS)

    2014-06-01

    26th Symposium on Plasma Science for Materials (SPSM-26) Takayuki Watanabe The 26th Symposium on Plasma Science for Materials (SPSM-26) was held in Fukuoka, Japan on September 23-24, 2013. SPSM has been held annually since 1988 under the sponsorship of The 153rd Committee on Plasma Materials Science, Japan Society for the Promotion of Science (JSPS). This symposium is one of the major activities of the Committee, which is organized by researchers in academia and industry for the purpose of advancing intersectional scientific information exchange and discussion of science and technology of plasma materials processing. Plasma processing have attracted extensive attention due to their unique advantages, and it is expected to be utilized for a number of innovative industrial applications such as synthesis of high-quality and high-performance nanomaterials. The advantages of plasmas including high chemical reactivity in accordance with required chemical reactions are beneficial for innovative processing. In recent years, plasma materials processing with reactive plasmas has been extensively employed in the fields of environmental issues and biotechnology. This conference seeks to bring different scientific communities together to create a forum for discussing the latest developments and issues. The conference provides a platform for the exploration of both fundamental topics and new applications of plasmas by the contacts between science, technology, and industry. The conference was organized in plenary lectures, invited, contributed oral presentations, and poster sessions. At this meeting, we had 142 participants from 10 countries and 104 presentations, including 11 invited presentations. This year, we arranged special topical sessions that cover Plasma Medicine and Biotechnologies, Business and Academia Cooperation, Plasma with Liquids, Plasma Processes for Nanomaterials, together with Basic, Electronics, and Thermal Plasma sessions. This special issue presents 28

  8. Capillary plasma jet: A low volume plasma source for life science applications

    NASA Astrophysics Data System (ADS)

    Topala, I.; Nagatsu, M.

    2015-02-01

    In this letter, we present results from multispectroscopic analysis of protein films, after exposure to a peculiar plasma source, i.e., the capillary plasma jet. This plasma source is able to generate very small pulsed plasma volumes, in kilohertz range, with characteristic dimensions smaller than 1 mm. This leads to specific microscale generation and transport of all plasma species. Plasma diagnosis was realized using general electrical and optical methods. Depending on power level and exposure duration, this miniature plasma jet can induce controllable modifications to soft matter targets. Detailed discussions on protein film oxidation and chemical etching are supported by results from absorption, X-ray photoelectron spectroscopy, and microscopy techniques. Further exploitation of principles presented here may consolidate research interests involving plasmas in biotechnologies and plasma medicine, especially in patterning technologies, modified biomolecule arrays, and local chemical functionalization.

  9. Capillary plasma jet: A low volume plasma source for life science applications

    SciTech Connect

    Topala, I. E-mail: tmnagat@ipc.shizuoka.ac.jp; Nagatsu, M. E-mail: tmnagat@ipc.shizuoka.ac.jp

    2015-02-02

    In this letter, we present results from multispectroscopic analysis of protein films, after exposure to a peculiar plasma source, i.e., the capillary plasma jet. This plasma source is able to generate very small pulsed plasma volumes, in kilohertz range, with characteristic dimensions smaller than 1 mm. This leads to specific microscale generation and transport of all plasma species. Plasma diagnosis was realized using general electrical and optical methods. Depending on power level and exposure duration, this miniature plasma jet can induce controllable modifications to soft matter targets. Detailed discussions on protein film oxidation and chemical etching are supported by results from absorption, X-ray photoelectron spectroscopy, and microscopy techniques. Further exploitation of principles presented here may consolidate research interests involving plasmas in biotechnologies and plasma medicine, especially in patterning technologies, modified biomolecule arrays, and local chemical functionalization.

  10. Variable polarity arc welding

    NASA Technical Reports Server (NTRS)

    Bayless, E. O., Jr.

    1991-01-01

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

  11. Unstable behavior of anodic arc discharge for synthesis of nanomaterials

    NASA Astrophysics Data System (ADS)

    Gershman, Sophia; Raitses, Yevgeny

    2016-09-01

    A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10‑3 s range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablation regime.

  12. Unstable behavior of anodic arc discharge for synthesis of nanomaterials

    NASA Astrophysics Data System (ADS)

    Gershman, Sophia; Raitses, Yevgeny

    2016-09-01

    A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10-3 s range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablation regime.

  13. Time-Resolved Spectroscopic Observation of Deposition Processes of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films by Using a Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Hanada, Kenji; Yoshitake, Tsuyoshi; Nishiyama, Takashi; Nagayama, Kunihito

    2010-08-01

    The deposition of ultrananocrystalline diamond (UNCD)/amorphous carbon composite films using a coaxial arc plasma gun in vacuum and, for comparison, in a 53.3 Pa hydrogen atmosphere was spectroscopically observed using a high-speed camera equipped with narrow-band-pass filters. UNCD crystallites with diameters of approximately 1.6 nm were formed even in vacuum. These extremely small crystallites imply that the formation is predominantly due to nucleation without the subsequent growth. Even in vacuum, emissions from C+ ions, C atoms, and C2 dimers lasted for approximately 100 µs, although the emission lifetimes of these species are generally 10 ns. We consider that the nucleation is due to the supersaturated environment containing excited carbon species with large number densities.

  14. An Overview of Recent Results from the Cassini Radio and Plasma Wave Science Investigation

    NASA Astrophysics Data System (ADS)

    Gurnett, D.; Kurth, W.; Hospodarsky, G.; Persoon, A.; Averkamp, T.; Cecconi, B.; Lecacheux, A.; Zarka, P.; Canu, P.; Cornilleau-Wehrlin, N.; Galopeau, P.; Roux, A.; Harvey, C.; Louarn, P.; Bostrom, R.; Gustafsson, G.; Wahlund, J.-E.; Desch, M.; Farrell, W.; Kaiser, M.; Kellogg, P.; Goetz, K.; Fischer, G.; Ladreiter, H.-P.; Rucker, H.; Alleyne, H.; Pedersen, A.

    2005-08-01

    The Radio and Plasma Wave Science (RPWS) investigation on the Cassini spacecraft provides measurements of radio emissions, plasma waves, and thermal plasma parameters in the vicinity of Saturn. This paper gives an overview of recent results from the RPWS. These include the most recent measurements of the rotational modulation period of radio emissions from Saturn (Saturn Kilometric Radiation), of impulsive radio bursts from atmospheric lightning (Saturn Electrostatic Discharges), of the distribution of small dust particles near the ring plane, and of the distribution and origin of plasma in the inner regions of the Saturnian system and near Titan.

  15. A comparison of tungsten-quartz-halogen, plasma arc and light-emitting diode light sources for the polymerization of an orthodontic adhesive.

    PubMed

    Thind, Bikram S; Stirrups, David R; Lloyd, Charles H

    2006-02-01

    This study investigated whether there were differences between the debond stress and adhesive remnant index (ARI) of an adhesive cured with three different orthodontic light sources. Sixty sound premolar teeth were divided into three groups of 20. A standard pre-adjusted edgewise premolar bracket (Victory Series) was bonded to each tooth using a light-cured orthodontic adhesive, Transbond X. Group 1 (control) specimens were cured with an Ortholux XT (tungsten-quartz-halogen bulb) light for 20 seconds, group 2 with an Ortho lite (plasma arc) for 6 seconds and group 3 with an Ortholux LED light-emitting diode for 10 seconds. The specimens were debonded 24 hours later using a universal mechanical testing machine, operating at a crosshead speed of 0.5 mm minute(-1). The Weibull modulus and a Logrank test showed no statistically significant differences between the three groups for debond stress. The ARI was assessed at x10 magnification. The ARI scores for group 2 were significantly different (P < 0.01) from those of groups 1 and 3 (between which there was no significant difference). For group 2 there was a greater tendency for failure to occur at the adhesive/tooth interface than for the other two groups. There appears to be no reason why any of the three types of light source cannot be used in orthodontics. Polymerization, as effective as that produced by conventional bulb light sources, was obtained with the short exposure times recommended for the plasma arc or light-emitting diode sources. PMID:16199410

  16. FOREWORD: International Workshop on Theoretical Plasma Physics: Modern Plasma Science. Sponsored by the Abdus Salam ICTP, Trieste, Italy

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.; Stenflo, L.

    2005-01-01

    The "International Workshop on Theoretical Plasma Physics: Modern Plasma Science was held at the Abdus Salam International Centre for Theoretical Physics (Abdus Salam ICTP), Trieste, Italy during the period 5 16 July 2004. The workshop was organized by P K Shukla, R Bingham, S M Mahajan, J T Mendonça, L Stenflo, and others. The workshop enters into a series of previous biennial activities that we have held at the Abdus Salam ICTP since 1989. The scientific program of the workshop was split into two parts. In the first week, most of the lectures dealt with problems concerning astrophysical plasmas, while in the second week, diversity was introduced in order to address the important role of plasma physics in modern areas of science and technology. Here, attention was focused on cross-disciplinary topics including Schrödinger-like models, which are common in plasma physics, nonlinear optics, quantum engineering (Bose-Einstein condensates), and nonlinear fluid mechanics, as well as emerging topics in fundamental theoretical and computational plasma physics, space and dusty plasma physics, laser-plasma interactions, etc. The workshop was attended by approximately hundred-twenty participants from the developing countries, Europe, USA, and Japan. A large number of participants were young researchers from both the developing and industrial countries, as the directors of the workshop tried to keep a good balance in inviting senior and younger generations of theoretical, computational and experimental plasma physicists to our Trieste activities. In the first week, there were extensive discussions on the physics of electromagnetic wave emissions from pulsar magnetospheres, relativistic magnetohydrodynamics of astrophysical objects, different scale sizes turbulence and structures in astrophysics. The scientific program of the second week included five review talks (60 minutes) and about thirty invited topical lectures (30 minutes). In addition, during the two weeks, there

  17. FOREWORD: International Workshop on Theoretical Plasma Physics: Modern Plasma Science. Sponsored by the Abdus Salam ICTP, Trieste, Italy

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.; Stenflo, L.

    2005-01-01

    The "International Workshop on Theoretical Plasma Physics: Modern Plasma Science was held at the Abdus Salam International Centre for Theoretical Physics (Abdus Salam ICTP), Trieste, Italy during the period 5 16 July 2004. The workshop was organized by P K Shukla, R Bingham, S M Mahajan, J T Mendonça, L Stenflo, and others. The workshop enters into a series of previous biennial activities that we have held at the Abdus Salam ICTP since 1989. The scientific program of the workshop was split into two parts. In the first week, most of the lectures dealt with problems concerning astrophysical plasmas, while in the second week, diversity was introduced in order to address the important role of plasma physics in modern areas of science and technology. Here, attention was focused on cross-disciplinary topics including Schrödinger-like models, which are common in plasma physics, nonlinear optics, quantum engineering (Bose-Einstein condensates), and nonlinear fluid mechanics, as well as emerging topics in fundamental theoretical and computational plasma physics, space and dusty plasma physics, laser-plasma interactions, etc. The workshop was attended by approximately hundred-twenty participants from the developing countries, Europe, USA, and Japan. A large number of participants were young researchers from both the developing and industrial countries, as the directors of the workshop tried to keep a good balance in inviting senior and younger generations of theoretical, computational and experimental plasma physicists to our Trieste activities. In the first week, there were extensive discussions on the physics of electromagnetic wave emissions from pulsar magnetospheres, relativistic magnetohydrodynamics of astrophysical objects, different scale sizes turbulence and structures in astrophysics. The scientific program of the second week included five review talks (60 minutes) and about thirty invited topical lectures (30 minutes). In addition, during the two weeks, there

  18. PARTICIPANT SUPPORT FOR THE 2010 GORDON RESEARCH CONFERENCE ON PLASMA PROCESSING SCIENCE (JULY 11-16,2010)

    SciTech Connect

    Uwe Kortshagen

    2011-06-14

    The 2010 Gordon Research Conference on Plasma Processing Science will feature a comprehensive program that will highlight the most cutting edge scientific advances in low temperature plasma science and will explore the applications of low temperature plasma technology relative to many grand societal challenges. Fundamental science sessions will focus on plasma kinetics, plasma surface interactions, and recent trends in plasma generation and multi-phase plasmas. Application sessions will explore the impact of plasma technology in renewable energy and the production of fuels from renewable feedstocks, plasma-enabled medicine and sterilization, and environmental remediation and waste treatment. The conference will bring together in an informal atmosphere leaders in the field with junior investigators and graduate students. The special format of the Gordon Conferences, with programmed discussion sessions and ample time for informal gatherings in the afternoons and evenings, will provide for a fertile atmosphere of brainstorming and creative thinking among the attendees.

  19. High repetition rate plasma mirror device for attosecond science

    SciTech Connect

    Borot, A.; Douillet, D.; Iaquaniello, G.; Lefrou, T.; Lopez-Martens, R.; Audebert, P.; Geindre, J.-P.

    2014-01-15

    This report describes an active solid target positioning device for driving plasma mirrors with high repetition rate ultra-high intensity lasers. The position of the solid target surface with respect to the laser focus is optically monitored and mechanically controlled on the nm scale to ensure reproducible interaction conditions for each shot at arbitrary repetition rate. We demonstrate the target capabilities by driving high-order harmonic generation from plasma mirrors produced on glass targets with a near-relativistic intensity few-cycle pulse laser system operating at 1 kHz. During experiments, residual target surface motion can be actively stabilized down to 47 nm (root mean square), which ensures sub-300-as relative temporal stability of the plasma mirror as a secondary source of coherent attosecond extreme ultraviolet radiation in pump-probe experiments.

  20. Graduate training in Earth science across borders and disciplines: ArcTrain -"Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic"

    NASA Astrophysics Data System (ADS)

    Stein, Rüdiger; Kucera, Michal; Walter, Maren; de Vernal, Anne

    2015-04-01

    Due to a complex set of feedback processes collectively known as "polar amplification", the Arctic realm is expected to experience a greater-than-average response to global climate forcing. The cascades of feedback processes that connect the Arctic cryosphere, ocean and atmosphere remain incompletely constrained by observations and theory and are difficult to simulate in climate models. Our capacity to predict the future of the region and assess the impacts of Arctic change processes on global and regional environments hinges on the availability of interdisciplinary experts with strong international experience and understanding of the science/society interface. This is the basis of the International Research Training Group "Processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic - ArcTrain", which was initiated in 2013. ArcTrain aims to educate PhD students in an interdisciplinary environment that combines paleoclimatology, physical oceanography, remote sensing and glaciology with comprehensive Earth system modelling, including sea-ice and ice-sheet components. The qualification program for the PhD students includes joint supervision, mandatory research residences at partner institutions, field courses on land and on sea (Floating University), annual meetings and training workshops and a challenging structured training in expert skills and transferrable skills. Its aim is to enhance the career prospects and employability of the graduates in a challenging international job market across academic and applied sectors. ArcTrain is a collaborative project at the University of Bremen and the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven. The German part of the project is designed to continue for nine years and educate three cohorts of twelve PhD students each. The Canadian partners comprise a consortium of eight universities led by the GEOTOP cluster at the Université du Québec à Montréal and including

  1. New approaches for the reduction of plasma arc drop in second-generation thermionic converters. Final report

    SciTech Connect

    Hatziprokopiou, M.E.; Shaw, D.T.

    1981-03-31

    Investigations of ion generation and recombination mechanisms in the cesium plasma as they pertain to the advanced mode thermionic energy converter are described. The changes in plasma density and temperature within the converter have been studied under the influence of several promising auxiliary ionization candidate sources. Three novel approaches of external cesium ion generation have been investigated in some detail, namely vibrationally excited N/sub 2/ as an energy source of ionization of Cs ions in a DC discharge, microwave power as a means of resonant sustenance of the cesium plasma, and ion generation in a pulse N/sub 2/-Cs mixture. The experimental data obtained and discussed show that all three techniques - i.e. the non-LTE high-voltage pulsing, the energy transfer from vibrationally excited diatomic gases, and the external pumping with a microwave power - have considerable promise as schemes in auxiliary ion generation applicable to the advanced thermionic energy converter.

  2. Characterization of atmospheric pressure H2O/O2 gliding arc plasma for the production of OH and O radicals

    NASA Astrophysics Data System (ADS)

    Roy, N. C.; Hafez, M. G.; Talukder, M. R.

    2016-08-01

    Atmospheric pressure H 2 O / O 2 gliding arc plasma is generated by a 88 Hz , 6 kV AC power supply. The properties of the produced plasma are investigated by optical emission spectroscopy. The relative intensity, rotational, vibrational, excitation temperatures and electron density are studied as a function of applied voltage, electrode spacing, and oxygen flow rate. The rotational and vibrational temperatures are determined simulating the OH ( A 2 Σ + ( v ″ = 0 ) → X 2 Π ( v ' = 0 ) ) bands with the aid of LIFBASE simulation software. The excitation temperature is obtained from the CuI transition taking non-thermal equilibrium condition into account employing intensity ratio method. The electron density is approximated from the H α Stark broadening using the Voigt profile fitting method. It is observed that the rotational and vibrational temperatures decrease with increasing electrode spacing and O 2 flow rate, but increase with the applied voltage. The excitation temperature is found to increase with increasing applied voltage and O 2 flow rate, but decrease with electrode spacing. The electron density increases with increasing applied voltage while it seems to be in a downward trend with increasing electrode spacing and O 2 flow rate.

  3. Temperature influence on deuterium retention for Be-W mixed thin films prepared by Thermionic Vacuum Arc method exposed to PISCES B plasma

    NASA Astrophysics Data System (ADS)

    Jepu, I.; Doerner, R. P.; Baldwin, M. J.; Porosnicu, C.; Lungu, C. P.

    2015-08-01

    Beryllium-tungsten thin films with well controlled elemental composition were prepared using Thermionic Vacuum Arc (TVA) technique and subsequently exposed to steady state, high ion flux (5.5 - 9.8 × 1022 ions m-2 s-1) deuterium (D) plasma in the PISCES-B facility to consistent fluences of 2.3 × 1026 m-2. Six types of layers were studied, ranging from pure Be, composite Be-W, having the atomic ratios of 9:1; 7:3; 1:1; 3:7; to pure W with a total deposited layer thickness of 2 μm. The sample exposure temperatures, namely 300 K, 473 K, 573 K and 773 K, respectively, were measured in situ with a thermocouple placed on the back of the sample. Morphological and structural examinations were undertaken before and after plasma exposure. Results show an influence of temperature on the subsequent morphology of the surface. Thermal Desorption Spectrometry (TDS) spectra showed a change in the D release behavior for different Be-W ratio for a certain exposure temperature.

  4. Research in space science and technology. [including X-ray astronomy and interplanetary plasma physics

    NASA Technical Reports Server (NTRS)

    Beckley, L. E.

    1977-01-01

    Progress in various space flight research programs is reported. Emphasis is placed on X-ray astronomy and interplanetary plasma physics. Topics covered include: infrared astronomy, long base line interferometry, geological spectroscopy, space life science experiments, atmospheric physics, and space based materials and structures research. Analysis of galactic and extra-galactic X-ray data from the Small Astronomy Satellite (SAS-3) and HEAO-A and interplanetary plasma data for Mariner 10, Explorers 47 and 50, and Solrad is discussed.

  5. The Science and Technology Challenges of the Plasma-Material Interface for Magnetic Fusion Energy

    NASA Astrophysics Data System (ADS)

    Whyte, Dennis

    2013-09-01

    The boundary plasma and plasma-material interactions of magnetic fusion devices are reviewed. The boundary of magnetic confinement devices, from the high-temperature, collisionless pedestal through to the surrounding surfaces and the nearby cold high-density collisional plasmas, encompasses an enormous range of plasma and material physics, and their integrated coupling. Due to fundamental limits of material response the boundary will largely define the viability of future large MFE experiments (ITER) and reactors (e.g. ARIES designs). The fusion community faces an enormous knowledge deficit in stepping from present devices, and even ITER, towards fusion devices typical of that required for efficient energy production. This deficit will be bridged by improving our fundamental science understanding of this complex interface region. The research activities and gaps are reviewed and organized to three major axes of challenges: power density, plasma duration, and material temperature. The boundary can also be considered a multi-scale system of coupled plasma and material science regulated through the non-linear interface of the sheath. Measurement, theory and modeling across these scales are reviewed, with a particular emphasis on establishing the use dimensionless parameters to understand this complex system. Proposed technology and science innovations towards solving the PMI/boundary challenges will be examined. Supported by US DOE award DE-SC00-02060 and cooperative agreement DE-FC02-99ER54512.

  6. Multihole Arc-Welding Orifice

    NASA Technical Reports Server (NTRS)

    Swaim, Benji D.

    1989-01-01

    Modified orifice for variable-polarity plasma-arc welding directs welding plume so it creates clean, even welds on both Inconel(R) and aluminum alloys. Includes eight holes to relieve back pressure in plasma. Quality of welds on ferrous and nonferrous alloys improved as result.

  7. An Experimental Study of Continuous Plasma Flows Driven by a Confined Arc in a Transverse Magnetic Field

    NASA Technical Reports Server (NTRS)

    Barger, R. L.; Brooks, J. D.; Beasley, W. D.

    1961-01-01

    A crossed-field, continuous-flow plasma accelerator has been built and operated. The highest measured velocity of the flow, which was driven by the interaction of the electric and magnetic fields, was about 500 meters per second. Some of the problems discussed are ion slip, stability and uniformity of the discharge, effect of the magnetic field on electron emission, use of preionization, and electrode contamination.

  8. Exploring turbulent energy dissipation and particle energization in space plasmas: the science of THOR mission

    NASA Astrophysics Data System (ADS)

    Retinò, Alessandro

    2016-04-01

    The Universe is permeated by hot, turbulent magnetized plasmas. They are found in active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, as well as in the solar corona, the solar wind and the Earth's magnetosphere. Turbulent plasmas are also found in laboratory devices such as e.g. tokamaks. Our comprehension of the plasma Universe is largely based on measurements of electromagnetic radiation such as light or X-rays which originate from particles that are heated and accelerated as a result of energy dissipation in turbulent environments. Therefore it is of key importance to study and understand how plasma is energized by turbulence. Most of the energy dissipation occurs at kinetic scales, where plasma no longer behaves as a fluid and the properties of individual plasma species (electrons, protons and other ions) become important. THOR (Turbulent Heating ObserveR - http://thor.irfu.se/) is a space mission currently in Study Phase as candidate for M-class mission within the Cosmic Vision program of the European Space Agency. The scientific theme of the THOR mission is turbulent energy dissipation and particle energization in space plasmas, which ties in with ESA's Cosmic Vision science. The main focus is on turbulence and shock processes, however areas where the different fundamental processes interact, such as reconnection in turbulence or shock generated turbulence, are also of high importance. The THOR mission aims to address fundamental questions such as how plasma is heated and particles are accelerated by turbulent fluctuations at kinetic scales, how energy is partitioned among different plasma components and how dissipation operates in different regimes of turbulence. To reach the goal, a careful design of the THOR spacecraft and its payload is ongoing, together with a strong interaction with numerical simulations. Here we present the science of THOR mission and we discuss implications of THOR observations for space

  9. Spectroscopic measurement of temperatures in pulsed TIG welding arcs

    NASA Astrophysics Data System (ADS)

    Ma, Shuiliang; Gao, Hongming; Zheng, Senmu; Wu, Lin

    2011-10-01

    Time resolved plasma temperatures in a pulsed tungsten-inert-gas (TIG) welding arc have been measured using optical emission spectroscopy. The peak and base pulse-averaged plasma temperatures both decrease with time after the arc ignition, and the plasma temperature decreases during the peak pulse period and increases during the base pulse period when the arc reaches the steady state. The decrease in the plasma temperature is associated with the increase in the cathode surface temperature and the decrease in the arc voltage and vice versa. The importance of the cathode surface temperature on the arc properties has been discussed.

  10. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

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

  11. Laser assisted arc welding for aluminum alloys

    SciTech Connect

    Fuerschbach, P.W.

    2000-01-01

    Experiments have been performed using a coaxial end-effector 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.

  12. An Overview of Science Education and Outreach Activities at the Princeton Plasma Physics Laboratory

    SciTech Connect

    J. DeLooper; A. DeMeo; P. Lucas; A. Post-Zwicker; C. Phillips; C. Ritter; J. Morgan; P. Wieser; A. Percival; E. Starkman; G. Czechowicz

    2000-11-07

    The U. S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) has an energetic science education program and outreach effort. This overview describes the components of the programs and evaluates the changes that have occurred in this effort during the last several years. Efforts have been expanded to reach more students, as well as the public in general. The primary goal is to inform the public regarding the fusion and plasma research at PPPL and to excite students so that they can appreciate science and technology. A student's interest in science can be raised by tours, summer research experiences, in-classroom presentations, plasma expos, teacher workshops and web-based materials. The ultimate result of this effort is a better-informed public, as well as an increase in the number of women and minorities who choose science as a vocation. Measuring the results is difficult, but current metrics are reviewed. The science education and outreach programs are supported by a de dicated core group of individuals and supplemented by other members of the PPPL staff and consultants who perform various outreach and educational activities.

  13. Catalytic Activity and Thermal Stability of Arc Plasma Deposited Pt Nano-Particles on CeO2-Al2O3.

    PubMed

    Jeong, Young Eun; Kumar, Pullur Anil; Choi, Hee Lack; Lee, Kwan-Young; Ha, Heon Phil

    2015-11-01

    In this study, catalytic activity and thermal stability of the arc plasma deposited (APD) Pt nano-particles on A12O3 and CeO2-Al2O3 were compared with that of the conventionally prepared Pt/Al2O3. All the catalysts were characterized by BET-surface area, transmission electron microscopy, X-ray photoelectron spectroscopy, CO-pulse chemisorption, H2-temperarture programmed reduction and X-ray absorption near edge spectroscopy. Through the quantum chemical calculations of different metal oxide support, CeO2 was identified as a suitable anchoring material with high energy level between the Pt species (Pt(0) and PtO(x)) on ceria. Subsequently, the results of XPS and XANES revealed the presence of abundant Pt(0) metal species in APD catalysts. The addition of ceria to Al2O3 support enhanced the dispersion of Pt nano-particles. The H2-TPR of Pt/CeO2-Al2O3 (APD) catalyst showed high-temperature reduction peaks corresponding to the interaction of Pt with ceria on alumina by Pt-O-Ce. Consequently, the Pt nano-particles deposited on CeO2-Al2O3 by APD attained strong thermal resistance at high temperatures. In addition, superior catalytic activities for CO and C3H6 oxidation and NO(x) reduction were obtained for the Pt/CeO2- Al2O3 (APD) catalyst.

  14. Hydrogenation effects on carrier transport in boron-doped ultrananocrystalline diamond/amorphous carbon films prepared by coaxial arc plasma deposition

    SciTech Connect

    Katamune, Yūki Takeichi, Satoshi; Ohmagari, Shinya; Yoshitake, Tsuyoshi

    2015-11-15

    Boron-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were deposited by coaxial arc plasma deposition with a boron-blended graphite target at a base pressure of <10{sup −3} Pa and at hydrogen pressures of ≤53.3 Pa. The hydrogenation effects on the electrical properties of the films were investigated in terms of chemical bonding. Hydrogen-scattering spectrometry showed that the maximum hydrogen content was 35 at. % for the film produced at 53.3-Pa hydrogen pressure. The Fourier-transform infrared spectra showed strong absorptions by sp{sup 3} C–H bonds, which were specific to the UNCD/a-C:H, and can be attributed to hydrogen atoms terminating the dangling bonds at ultrananocrystalline diamond grain boundaries. Temperature-dependence of the electrical conductivity showed that the films changed from semimetallic to semiconducting with increasing hydrogen pressure, i.e., with enhanced hydrogenation, probably due to hydrogenation suppressing the formation of graphitic bonds, which are a source of carriers. Carrier transport in semiconducting hydrogenated films can be explained by a variable-range hopping model. The rectifying action of heterojunctions comprising the hydrogenated films and n-type Si substrates implies carrier transport in tunneling.

  15. Microstructure and chemical homogeneity of plasma-arc cold-hearth melted Ti-48Al-2Mn-2Nb gamma titanium aluminide

    SciTech Connect

    Dowson, A.L.; Johnson, T.P.; Young, J.M.; Jacobs, M.H.

    1995-12-31

    The microstructure and chemical homogeneity of plasma-arc cold-hearth (PACH) melted Ti-48Al-2Mn-2Nb gamma-based titanium aluminide have been studied and potential correlation`s between compositional variations and changes in both the withdrawal rate and the crucible torch current have been explored. Periodic oscillations in composition have been identified both across the ingot cross section and down the length of the bar, and distinct regions involving both Al enrichment and depletion have been identified, primarily towards the edge and near central regions of the bar. These changes in composition were accompanied by a change in the microstructural morphology with the microstructure changing from a relatively fine, fully equiaxed gamma phase morphology at the surface, through coarse columnar, to a heavily cored dendritic-type structure on moving towards the centre of the bar. Micro-analytical studies of this dendritic region have shown the primary and secondary dendrite arms to consist of a fully transformed lamellar structure relatively rich in both Ti and Nb with Mn and Al tending to segregate preferentially to the interdendritic regions.

  16. Effects of nitrogen doping on the electrical conductivity and optical absorption of ultrananocrystalline diamond/hydrogenated amorphous carbon films prepared by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Zkria, Abdelrahman; Katamune, Yūki; Yoshitake, Tsuyoshi

    2016-07-01

    3 at. % nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were synthesized by coaxial arc plasma deposition. Optically, the films possess large absorption coefficients of more than 105 cm‑1 at photon energies from 3 to 5 eV. The optical band gap was estimated to be 1.28 eV. This value is smaller than that of undoped films, which might be attributable to increased sp2 fractions. The temperature dependence of the electrical conductivity implies that carrier transport follows a hopping conduction model. Heterojunctions with p-type Si substrates exhibited a typical rectifying action. From the capacitance–voltage characteristics that evidently indicated the expansion of a depletion region into the film side, the built-in potential and carrier concentration were estimated to be 0.51 eV and 7.5 × 1016 cm‑3, respectively. It was experimentally demonstrated that nitrogen-doped UNCD/a-C:H films are applicable as an n-type semiconductor.

  17. Prediction of Welded Joint Strength in Plasma Arc Welding: A Comparative Study Using Back-Propagation and Radial Basis Neural Networks

    NASA Astrophysics Data System (ADS)

    Srinivas, Kadivendi; Vundavilli, Pandu R.; Manzoor Hussain, M.; Saiteja, M.

    2016-09-01

    Welding input parameters such as current, gas flow rate and torch angle play a significant role in determination of qualitative mechanical properties of weld joint. Traditionally, it is necessary to determine the weld input parameters for every new welded product to obtain a quality weld joint which is time consuming. In the present work, the effect of plasma arc welding parameters on mild steel was studied using a neural network approach. To obtain a response equation that governs the input-output relationships, conventional regression analysis was also performed. The experimental data was constructed based on Taguchi design and the training data required for neural networks were randomly generated, by varying the input variables within their respective ranges. The responses were calculated for each combination of input variables by using the response equations obtained through the conventional regression analysis. The performances in Levenberg-Marquardt back propagation neural network and radial basis neural network (RBNN) were compared on various randomly generated test cases, which are different from the training cases. From the results, it is interesting to note that for the above said test cases RBNN analysis gave improved training results compared to that of feed forward back propagation neural network analysis. Also, RBNN analysis proved a pattern of increasing performance as the data points moved away from the initial input values.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  19. Deposition of silicon-carbon coatings from the plasma of a non-self-sustained arc discharge with a heated cathode

    NASA Astrophysics Data System (ADS)

    Grenadyorov, A. S.; Oskomov, K. V.; Solov'ev, A. A.; Rabotkin, S. V.

    2016-05-01

    Amorphous hydrogenated carbon doped with silicon oxide ( a-C:H:Si:O), which is referred to as silicon-carbon coatings in this work, consists of thin amorphous films, which are used as commercial solid lubricants due to their higher stability under extreme environmental conditions as compared to amorphous hydrogenated carbon. The deposition of silicon-carbon coatings from the plasma of a non-self-sustained arc discharge with a heated cathode is considered. Silicon-carbon coatings are deposited using polyphenul methylsiloxane as a precursor at a flow rate of 0.05 mL/min in an argon atmosphere at a pressure of 0.1 Pa. A high-frequency power supply is used to apply a high-frequency bias voltage to a substrate during deposition. After deposition, the mechanical properties of the coatings are studied. The maximum hardness of the coating is 20 GPa at a minimum friction coefficient of 0.16 and a wear rate of 1.3 × 10-5 mm3 N-1 m-1. Energy dispersive analysis shows that the coatings contain a significant content of carbon and oxygen (about 80 and 15%, respectively) and a low content of silicon (about 5%).

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

    PubMed

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

    2015-12-21

    We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications. The nitridization of terbium, dysprosium and holmium was obtained using a mixture of nitrogen and argon gas inside a discharge chamber with 4 kPa pressure. The structural and microstructural properties of these rare earth nitrides were investigated by using X-ray diffraction and transmission electron microscopy. The studied nitrides undergo a second-order ferromagnetic to paramagnetic phase transition at Curie temperatures of 35.7, 19.9 and 14.2 K for TbN, DyN and HoN, respectively. The magnetocaloric effects were estimated by calculating the magnetic entropy changes from the magnetization data sets measured at the different applied magnetic fields and temperatures. The changes in entropy -ΔSM were found to be 12.0, 13.6 and 24.5 J kg(-1) K(-1) at an applied magnetic field of 5 T. PMID:26492221

  1. Microstructure and high-temperature wear properties of in situ TiC composite coatings by plasma transferred arc surface alloying on gray cast iron

    NASA Astrophysics Data System (ADS)

    Zhao, Hang; Li, Jian-jun; Zheng, Zhi-zhen; Wang, Ai-hua; Huang, Qi-wen; Zeng, Da-wen

    2015-12-01

    In this work, an in situ synthesized TiC-reinforced metal matrix composite (MMC) coating of approximately 350-400 µm thickness was fabricated on a gray cast iron (GCI) substrate by plasma transferred arc (PTA) surface alloying of Ti-Fe alloy powder. Microhardness tests showed that the surface hardness increased approximately four-fold after the alloying treatment. The microstructure of the MMC coating was mainly composed of residual austenite, acicular martensite, and eutectic ledeburite. Scanning electron microscopy (SEM) and X-ray diffraction analyzes revealed that the in situ TiC particles, which were formed by direct reaction of Ti with carbon originally contained in the GCI, was uniformly distributed at the boundary of residual austenite in the alloying zone. Pin-on-disc high-temperature wear tests were performed on samples both with and without the MMC coating at room temperature and at elevated temperatures (473 K and 623 K), and the wear behavior and mechanism were investigated. The results showed that, after the PTA alloying treatment, the wear resistance of the samples improved significantly. On the basis of our analysis of the composite coatings by optical microscopy, SEM with energy-dispersive X-ray spectroscopy, and microhardness measurements, we attributed this improvement of wear resistance to the transformation of the microstructure and to the presence of TiC particles.

  2. Surface science studies on the interaction of nitrogen trifluoride ion beams and plasmas with silicon

    NASA Astrophysics Data System (ADS)

    Little, Thomas William

    As microelectronic dimensions continue to shrink, the role of plasma etching assumes greater importance. Recently, there has been considerable interest in using nitrogen trifluoride (NF3) to replace perfluorocarbon (PFC) etchants in some applications. Nitrogen trifluoride is capable of high etching rates, environmentally more tolerable than PFCs, and eliminates buildup of macroscopic carbonaceous surface layers. Literature exists on NF3 etch rate, selectivity and profiles during plasma etching, but very little has been done in the way of detailed surface science examinations of the interaction of NF3 with silicon (Si) surfaces. Scientifically, NF3 offers an ideal tool to probe the surface science of plasma-Si interaction during etching. Previous studies of fluorine (F) etching of Si have relied on either F2, atomic F, or an inert gas compound such as XeF2. The present work employs a gas in which both atoms (N, F) are chemically active, and is one of the first surface science examinations of NF3-Si interaction. Through the complementary use of ion beams and actual plasmas, the effects of ions and neutrals inherent in the plasma have been separated. X-ray photoelectron spectroscopy (XPS) shows that the neutrals are responsible for Si-F bonding while ions are incorporated in complex Si-N-F moieties. The results show for the first time that N is incorporated in Si during the initial stages of etching. Quantum mechanical calculations based on density functional theory (DFT) have been used to augment the XPS results. Finally, severe plasma etching produces anomalous XPS results which can be attributed to differential charging. Mechanistically, the charging is caused by ion bombardment damage during etching as evidenced by atomic force microscopy (AFM). The differential charging behavior has been studied, and it is suggested that the phenomenon may be utilized to quantify plasma etch damage.

  3. Thermal efficiency of arc welding processes

    SciTech Connect

    DuPont, J.N.; Marder, A.R.

    1995-12-01

    A study was conducted on the arc and melting efficiency of the plasma arc, gas tungsten arc, gas metal arc, and submerged arc welding processes. The results of this work are extended to develop a quantitative method for estimating weld metal dilution in a companion paper. Arc efficiency was determined as a function of current for each process using A36 steel base metal. Melting efficiency was evaluated with variations in arc power and travel speed during deposition of austenitic stainless steel filler metal onto A36 steel substrates. The arc efficiency did not vary significantly within a given process over the range of currents investigated. A semi-empirical relation was developed for the melting efficiency as a function of net arc power and travel speed, which described the experimental data well. An interaction was observed between the arc and melting efficiency. A low arc efficiency factor limits the power delivered to the substrate which, in turn, limits the maximum travel speed for a given set of conditions. High melting efficiency is favored by high arc powers and travel speeds. As a result, a low arc efficiency can limit the maximum obtainable melting efficiency.

  4. Mechanical and Chemical Characterization of a TiC/C System Synthesized Using a Focus Plasma Arc.

    PubMed

    Mahmoodian, Reza; Hamdi, M; Hassan, M A; Akbari, Abolghasem

    2015-01-01

    Titanium carbide-graphite (TiC/C) composite was successfully synthesized from Ti and C starting elemental powders using self-propagating high-temperature synthesis technique in an ultra-high plasma inert medium in a single stage. The TiC was exposed to a high-temperature inert medium to allow recrystallization. The product was then characterized using field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Rietveld refinement, nanoindentation, and micro-hardness to determine the product's properties. The recorded micro-hardness of the product was 3660 HV, which is a 14% enhancement and makes is comparable to TiC materials. PMID:26111217

  5. Mechanical and Chemical Characterization of a TiC/C System Synthesized Using a Focus Plasma Arc

    PubMed Central

    Mahmoodian, Reza; Hamdi, M.; Hassan, M. A; Akbari, Abolghasem

    2015-01-01

    Titanium carbide-graphite (TiC/C) composite was successfully synthesized from Ti and C starting elemental powders using self-propagating high-temperature synthesis technique in an ultra-high plasma inert medium in a single stage. The TiC was exposed to a high-temperature inert medium to allow recrystallization. The product was then characterized using field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Rietveld refinement, nanoindentation, and micro-hardness to determine the product’s properties. The recorded micro-hardness of the product was 3660 HV, which is a 14% enhancement and makes is comparable to TiC materials. PMID:26111217

  6. Solar cell arcing: The role of outgassing and contamination

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    The effect of outgassing, venting, and thruster firing events on spacecraft system performance has been a long standing issue. Recent laboratory measurements on negatively biased high voltage solar cells at Physical Sciences Inc. (PSI) suggest that some currently designed and certainly future space power systems must address/re-evaluate this issue. Our observations show that exposing these cells to moderate levels (10 exp -3 torr-min) of H2O vapor enhances the arcing frequency, while heating to 85 C to remove water vapor significantly reduces the arc frequency. The interaction of the adhesive used to attach the cover glass to the solar cell with ambient water vapor is the key factor in determining arcing rates. Elimination of adhesive exposed to the environmental plasma reduces the arc frequency more than two orders of magnitude, and eliminates any sensitivity to H2O exposure. The adhesive may also become a source of spacecraft contamination. Macroscopic amounts were observed to blow off some arc events, and (we assume) electrostatically precipitate at other negatively biased locations. Data, analysis, and potential impact for future space platforms are discussed.

  7. Progress of research on plasma facing materials in University of Science and Technology Beijing

    NASA Astrophysics Data System (ADS)

    Ge, Chang-Chun; Zhou, Zhang-Jian; Song, Shu-Xiang; Du, Juan; Zhong, Zhi-Hong

    2007-06-01

    In this paper, we report some new progress on plasma facing materials in University of Science and Technology Beijing (USTB), China. They include fabrication of tungsten coating with ultra-fine grain size by atmosphere plasma spraying; fabrication of tungsten with ultra-fine grain size by a newly developed method named as resistance sintering under ultra-high pressure; using the concept of functionally graded materials to join tungsten to copper based heat sink; joining silicon doped carbon to copper by brazing using a Ti based amorphous filler and direct casting.

  8. Modeling Multi-Arc Spraying Systems

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.

    2016-06-01

    The use of plasma as energy source in thermal spraying enables among others the processing of feed stock materials with very high melting temperatures as coating materials. New generation multi-arc plasma spraying systems are widely spread and promise several advantages in comparison to the conventional single-arc systems. Numerical modeling of multi-arc plasma spraying offers the possibility to increase the understanding about this process. This study focuses on the numerical modeling of three-cathode spraying systems, introducing the recent activities in this field and discussing the numerical aspects which influence the prediction power of the models.

  9. Low voltage arc formation in railguns

    DOEpatents

    Hawke, R.S.

    1985-08-05

    A low voltage plasma arc is first established across the rails behind the projectile by switching a low voltage high current source across the rails to establish a plasma arc by vaporizing a fuse mounted on the back of the projectile, maintaining the voltage across the rails below the railgun breakdown voltage to prevent arc formation ahead of the projectile. After the plasma arc has been formed behind the projectile a discriminator switches the full energy bank across the rails to accelerate the projectile. A gas gun injector may be utilized to inject a projectile into the breech of a railgun. The invention permits the use of a gas gun or gun powder injector and an evacuated barrel without the risk of spurious arc formation in front of the projectile.

  10. Low voltage arc formation in railguns

    DOEpatents

    Hawke, R.S.

    1987-11-17

    A low voltage plasma arc is first established across the rails behind the projectile by switching a low voltage high current source across the rails to establish a plasma arc by vaporizing a fuse mounted on the back of the projectile, maintaining the voltage across the rails below the railgun breakdown voltage to prevent arc formation ahead of the projectile. After the plasma arc has been formed behind the projectile a discriminator switches the full energy bank across the rails to accelerate the projectile. A gas gun injector may be utilized to inject a projectile into the breech of a railgun. The invention permits the use of a gas gun or gun powder injector and an evacuated barrel without the risk of spurious arc formation in front of the projectile. 2 figs.

  11. Low voltage arc formation in railguns

    DOEpatents

    Hawke, Ronald S.

    1987-01-01

    A low voltage plasma arc is first established across the rails behind the projectile by switching a low voltage high current source across the rails to establish a plasma arc by vaporizing a fuse mounted on the back of the projectile, maintaining the voltage across the rails below the railgun breakdown voltage to prevent arc formation ahead of the projectile. After the plasma arc has been formed behind the projectile a discriminator switches the full energy bank across the rails to accelerate the projectile. A gas gun injector may be utilized to inject a projectile into the breech of a railgun. The invention permits the use of a gas gun or gun powder injector and an evacuated barrel without the risk of spurious arc formation in front of the projectile.

  12. Commissioning of an ECR Plasma Source for Lithium Surface Science Studies and Initial Results

    NASA Astrophysics Data System (ADS)

    Norval, Ryan; Capece, Angie; Faroranti, Oluseyi; Skinner, Charles; Koel, Bruce

    2012-10-01

    Lithium-conditioned plasma facing components reduce hydrogen recycling in plasmas by readily forming hydride compounds, which results in improved plasma confinement and performance. A new ultrahigh vacuum (UHV)-compatible electron cyclotron resonance (ECR) plasma source, which allows surface spectroscopic studies, was recently commissioned at the Princeton Plasma Physics Laboratory to study the uptake of deuterium by lithium coatings on single crystal molybdenum as a precursor to NSTX experiments. The ECR plasma source is capable of delivering deuterium ions to the surface at energies of 50-2000 eV and current densities between 0.05 and 2.0 mA/cm^2. Surface science studies will be performed on clean Li films on Mo(100) substrates before and after D+ irradiation under UHV conditions at base pressures of 10-10 Torr. X-ray photoelectron spectroscopy will be used to determine the chemical state of lithium, and thermal desorption spectroscopy will be used to measure the amount of deuterium retained in the sample as a function of ion fluence and temperature.

  13. Effect of curing time on the bond strength of a bracket-bonding system cured with a light-emitting diode or plasma arc light.

    PubMed

    Dall'Igna, Carine Maccarini; Marchioro, Ernani Menezes; Spohr, Ana Maria; Mota, Eduardo Gonçalves

    2011-02-01

    The purpose of this study was to assess the influence of two light units, a light-emitting diode (LED) and a plasma arc light (PAC), on the shear bond strength (SBS) of brackets bonded to enamel. Ninety bovine teeth were divided into six groups, according to the light-curing unit and exposure times used. In the LED (Ortholux; 3M-Unitek) group, the specimens were light cured for 5, 10, and 15 seconds. In the PAC (Apollo 95E; DenMed Technologies) group, the specimens were light cured for 3, 6, and 9 seconds. The brackets were bonded with Transbond XT (3M-Unitek), stored in distilled water at 37 °C for 24 hours and then submitted to SBS testing in a universal testing machine. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the teeth. According to analysis of variance and Tukey multiple comparisons test, the highest mean SBS was obtained with the LED at 15 seconds (16.68 MPa), which did not significantly differ from the LED 10 (14.76 MPa) or 5 (13.92 MPa) second groups (P > 0.05). The LED 10 and 5 second groups were not significantly different from the PAC 9 second group (12.66 MPa) or from the PAC 6 second group (9.96 MPa). The lowest mean SBS was obtained with the PAC 3 second group (8.29 MPa), which did not differ significantly from the PAC 6 second group. The method of light curing did not influence the ARI, with score 3 predominant. The LED at 5 seconds and the PAC at 3 seconds provided sufficient mean SBS to resist either orthodontic or masticatory forces. PMID:20558589

  14. Effect of curing time on the bond strength of a bracket-bonding system cured with a light-emitting diode or plasma arc light.

    PubMed

    Dall'Igna, Carine Maccarini; Marchioro, Ernani Menezes; Spohr, Ana Maria; Mota, Eduardo Gonçalves

    2011-02-01

    The purpose of this study was to assess the influence of two light units, a light-emitting diode (LED) and a plasma arc light (PAC), on the shear bond strength (SBS) of brackets bonded to enamel. Ninety bovine teeth were divided into six groups, according to the light-curing unit and exposure times used. In the LED (Ortholux; 3M-Unitek) group, the specimens were light cured for 5, 10, and 15 seconds. In the PAC (Apollo 95E; DenMed Technologies) group, the specimens were light cured for 3, 6, and 9 seconds. The brackets were bonded with Transbond XT (3M-Unitek), stored in distilled water at 37 °C for 24 hours and then submitted to SBS testing in a universal testing machine. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the teeth. According to analysis of variance and Tukey multiple comparisons test, the highest mean SBS was obtained with the LED at 15 seconds (16.68 MPa), which did not significantly differ from the LED 10 (14.76 MPa) or 5 (13.92 MPa) second groups (P > 0.05). The LED 10 and 5 second groups were not significantly different from the PAC 9 second group (12.66 MPa) or from the PAC 6 second group (9.96 MPa). The lowest mean SBS was obtained with the PAC 3 second group (8.29 MPa), which did not differ significantly from the PAC 6 second group. The method of light curing did not influence the ARI, with score 3 predominant. The LED at 5 seconds and the PAC at 3 seconds provided sufficient mean SBS to resist either orthodontic or masticatory forces.

  15. Preparation of hydrogenated diamond-like carbon films using high-density pulsed plasmas of Ar/C2H2 and Ne/C2H2 mixture

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2016-07-01

    Hydrogenated diamond-like carbon films are prepared using reactive high-density pulsed plasmas of Ar/C2H2 and Ne/C2H2 mixture in the total pressure range from 0.5 to 2 Pa. The plasmas are produced using a reactive high-power impulse magnetron sputtering (HiPIMS) system. A negative pulse voltage of -500 V is applied to the substrate for a period of 15 µs in the afterglow mode. The growth rate does not strongly depend on the type of ambient gas but it markedly increases to about 2.7 µm/h at a C2H2 fraction of 10% and a total pressure of 2 Pa with increasing C2H2 fraction. The marked increase in the growth rate means that the HiPIMS system can be regarded as a plasma source for the chemical vapor deposition process. The hardness of the films prepared by Ne/C2H2 plasmas is somewhat higher than that of the films prepared by Ar/C2H2 plasmas under the same operating conditions, and the difference becomes larger as the pressure increases. The hardness of the films prepared by Ne/C2H2 plasmas ranges between 11 and 18 GPa. In the Raman spectra, two very broad overlapping bands are assigned as the G (graphite) and D (disorder) bands. The peak position of the G band is roughly independent of the total pressure, whereas the FWHM of the G peak decreases with increasing total pressure as a whole.

  16. Preparation of hydrogenated diamond-like carbon films using high-density pulsed plasmas of Ar/C2H2 and Ne/C2H2 mixture

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2016-07-01

    Hydrogenated diamond-like carbon films are prepared using reactive high-density pulsed plasmas of Ar/C2H2 and Ne/C2H2 mixture in the total pressure range from 0.5 to 2 Pa. The plasmas are produced using a reactive high-power impulse magnetron sputtering (HiPIMS) system. A negative pulse voltage of ‑500 V is applied to the substrate for a period of 15 µs in the afterglow mode. The growth rate does not strongly depend on the type of ambient gas but it markedly increases to about 2.7 µm/h at a C2H2 fraction of 10% and a total pressure of 2 Pa with increasing C2H2 fraction. The marked increase in the growth rate means that the HiPIMS system can be regarded as a plasma source for the chemical vapor deposition process. The hardness of the films prepared by Ne/C2H2 plasmas is somewhat higher than that of the films prepared by Ar/C2H2 plasmas under the same operating conditions, and the difference becomes larger as the pressure increases. The hardness of the films prepared by Ne/C2H2 plasmas ranges between 11 and 18 GPa. In the Raman spectra, two very broad overlapping bands are assigned as the G (graphite) and D (disorder) bands. The peak position of the G band is roughly independent of the total pressure, whereas the FWHM of the G peak decreases with increasing total pressure as a whole.

  17. Studies of hollow carbon nanospheres and grain boundary phase transitions in metals as examples of plasma material science

    SciTech Connect

    Skovoroda, A. A. Andreev, V. F.; Kas'yanova, N. V.; Spitsyn, A. V.

    2013-07-15

    Results are presented from studies of the material of hollow carbon nanospheres (nanocapsules) that form in tokamaks as a result of plasma interaction with the chamber wall and are similar in structure to meteorite onions. The possibility is demonstrated of studying the material properties in the grain boundary phase transitions in solid materials (metals) by using the plasma-stimulated permeability for hydrogen. The term 'plasma material science' is proposed for such material studies.

  18. Aerospatiale industrial thermal plasma activities

    NASA Astrophysics Data System (ADS)

    Labrot, Maxime

    Details of nontransferred arc torches, plasma systems in industrial use and operational plasma applications are listed. A plasma application on a foundry cupola is detailed. The setting up of a plasma system is described. Research and development activities are summarized.

  19. Arc-driven rail accelerator research

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1987-01-01

    Arc-driven rail accelerator research is analyzed by considering wall ablation and viscous drag in the plasma. Plasma characteristics are evaluated through a simple fluid-mechanical analysis considering only wall ablation. By equating the energy dissipated in the plasma with the radiation heat loss, the average properties of the plasma are determined as a function of time and rate of ablation. Locations of two simultaneously accelerating arcs were determined by optical and magnetic probes and fron streak camera photographs. All three measurements provide consistent results.

  20. Educating the next generation in the science and technology of plasmas, beams and accelerators

    NASA Astrophysics Data System (ADS)

    Barletta, Wiliam

    2007-11-01

    Accelerators are essential tools for discovery in fundamental physics, biology, and chemistry. Particle beam based instruments in medicine, industry and national security constitute a multi-billion dollar per year industry. More than 55,000 peer-reviewed papers having accelerator as a keyword are available on the Web. Yet only a handful of universities offer any formal training in accelerator science. Several reasons can be cited: 1) The science and technology of non-neutral plasmas cuts across traditional academic disciplines. 2) Electrical engineering departments have evolved toward micro- and nano-technology and computing science. 3) Nuclear physics departments have atrophied. 4) With few exceptions, interest at individual universities is not extensive enough to support a strong faculty line. The United States Particle Accelerator School (USPAS) is National Graduate Educational Program that has developed an educational paradigm that, over the past twenty-years, has granted more university credit in accelerator / beam science and technology than any university in the world. Governed and supported by a consortium of nine DOE laboratories and two NSF university laboratories, USPAS offers a responsive and balanced curriculum of science, engineering, and hands-on courses. Sessions are held twice annually, hosted by major US research universities that approve course credit, certify the USPAS faculty, and grant course credit. The USPAS paradigm is readily extensible to other rapidly developing, cross-disciplinary research areas such as high energy density physics.

  1. Dilution in single pass arc welds

    SciTech Connect

    DuPont, J.N.; Marder, A.R.

    1996-06-01

    A study was conducted on dilution of single pass arc welds of type 308 stainless steel filler metal deposited onto A36 carbon steel by the plasma arc welding (PAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and submerged arc welding (SAW) processes. Knowledge of the arc and melting efficiency was used in a simple energy balance to develop an expression for dilution as a function of welding variables and thermophysical properties of the filler metal and substrate. Comparison of calculated and experimentally determined dilution values shows the approach provides reasonable predictions of dilution when the melting efficiency can be accurately predicted. The conditions under which such accuracy is obtained are discussed. A diagram is developed from the dilution equation which readily reveals the effect of processing parameters on dilution to aid in parameter optimization.

  2. Near Real Time Tools for ISS Plasma Science and Engineering Applications

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Willis, Emily M.; Parker, Linda Neergaard; Shim, Ja Soon; Kuznetsova, Maria M.; Pulkkinen, Antti, A.

    2013-01-01

    The International Space Station (ISS) program utilizes a plasma environment forecast for estimating electrical charging hazards for crews during extravehicular activity (EVA). The process uses ionospheric electron density (Ne) and temperature (Te) measurements from the ISS Floating Potential Measurement Unit (FPMU) instrument suite with the assumption that the plasma conditions will remain constant for one to fourteen days with a low probability for a space weather event which would significantly change the environment before an EVA. FPMU data is typically not available during EVA's, therefore, the most recent FPMU data available for characterizing the state of the ionosphere during EVA is typically a day or two before the start of an EVA or after the EVA has been completed. Three near real time space weather tools under development for ISS applications are described here including: (a) Ne from ground based ionosonde measurements of foF2 (b) Ne from near real time satellite radio occultation measurements of electron density profiles (c) Ne, Te from a physics based ionosphere model These applications are used to characterize the ISS space plasma environment during EVA periods when FPMU data is not available, monitor for large changes in ionosphere density that could render the ionosphere forecast and plasma hazard assessment invalid, and validate the "persistence of conditions" forecast assumption. In addition, the tools are useful for providing space environment input to science payloads on ISS and anomaly investigations during periods the FPMU is not operating.

  3. Near Real Time Tools for ISS Plasma Science and Engineering Applications

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Willis, Emily M.; Parker, Linda Neergaard; Shim, Ja Soon; Kuznetsova, Maria; Pulkkinen, Antti A.

    2013-01-01

    The International Space Station (ISS) program utilizes a plasma environment forecast for estimating electrical charging hazards for crews during extravehicular activity (EVA). The process uses ionospheric electron density and temperature measurements from the ISS Floating Potential Measurement Unit (FPMU) instrument suite with the assumption that the plasma conditions will remain constant for one to fourteen days with a low probability for a space weather event which would significantly change the environment before an EVA. FPMU data is typically not available during EVA's, therefore, the most recent FPMU data available for characterizing the state of the ionosphere during EVA is typically a day or two before the start of an EVA or after the EVA has been completed. In addition to EVA support, information on ionospheric plasma densities is often needed for support of ISS science payloads and anomaly investigations during periods when the FPMU is not operating. This presentation describes the application of space weather tools developed by MSFC using data from near real time satellite radio occultation and ground based ionosonde measurements of ionospheric electron density and a first principle ionosphere model providing electron density and temperature run in a real time mode by GSFC. These applications are used to characterize the space environment during EVA periods when FPMU data is not available, monitor for large charges in ionosphere density that could render the ionosphere forecast and plasma hazard assessment invalid, and validate the assumption of "persistence of conditions" used in deriving the hazard forecast. In addition, the tools are used to provide space environment input to science payloads on ISS and anomaly investigations during periods the FPMU is not operating.

  4. Stability measurements of PPL atmospheric pressure arc

    SciTech Connect

    Roquemore, L.; Zweben, S.J.; Wurden, G.A.

    1997-12-31

    Experiments on the stability of atmospheric pressure arcs have been started at PPL to understand and improve the performance of arc furnaces used for processing applications in metallurgy and hazardous waste treatment. Previous studies have suggested that the violent instabilities in such arcs may be due to kink modes. A 30 kW, 500 Amp CW DC experimental arc furnace was constructed with a graphite cathode and a molten steel anode. The arc plasma is diagnosed with 4000 frames/sec digital camera, Hall probes, and voltage and current monitors. Under certain conditions, the arc exhibits an intermittent helical instability, with the helix rotating at {approx}600 Hz. The nature of the instability is investigated. A possible instability mechanism is the self-magnetic field of the arc, with saturation occurring due to inhomogeneous heating in a helical arc. The effect of external DC and AC magnetic fields on the instability is investigated. Additionally, arc deflection due to external transverse magnetic field is investigated. The deflection angle is found to be proportional to the applied field, and is in good agreement with a simple model of the {rvec J} x {rvec b} force on the arc jet.

  5. Stretched arc discharge in produced water.

    PubMed

    Cho, Y I; Wright, K C; Kim, H S; Cho, D J; Rabinovich, A; Fridman, A

    2015-01-01

    The objective of the present study was to investigate the feasibility of stretching an arc discharge in produced water to increase the volume of produced water treated by plasma. Produced water is the wastewater generated by hydraulic fracturing of shale during the production phase in shale-oil or shale-gas exploration. The electric conductivity of produced water is in the range of 50-200 mS/cm, which provides both a challenge and opportunity for the application of plasmas. Stretching of an arc discharge in produced water was accomplished using a ground electrode and two high-voltage electrodes: one positioned close to the ground electrode and the other positioned farther away from the ground. The benefit of stretching the arc is that the contact between the arc and water is significantly increased, resulting in more efficient plasma treatment in both performance and energy cost. PMID:25638080

  6. Stretched arc discharge in produced water

    NASA Astrophysics Data System (ADS)

    Cho, Y. I.; Wright, K. C.; Kim, H. S.; Cho, D. J.; Rabinovich, A.; Fridman, A.

    2015-01-01

    The objective of the present study was to investigate the feasibility of stretching an arc discharge in produced water to increase the volume of produced water treated by plasma. Produced water is the wastewater generated by hydraulic fracturing of shale during the production phase in shale-oil or shale-gas exploration. The electric conductivity of produced water is in the range of 50-200 mS/cm, which provides both a challenge and opportunity for the application of plasmas. Stretching of an arc discharge in produced water was accomplished using a ground electrode and two high-voltage electrodes: one positioned close to the ground electrode and the other positioned farther away from the ground. The benefit of stretching the arc is that the contact between the arc and water is significantly increased, resulting in more efficient plasma treatment in both performance and energy cost.

  7. Influence of metal vapour on arc temperatures in gas-metal arc welding: convection versus radiation

    NASA Astrophysics Data System (ADS)

    Murphy, Anthony B.

    2013-06-01

    The presence of metal vapour in gas-metal arc welding has been shown to have two strong effects on the arc plasma: a decrease in temperature throughout the arc, and the formation of a local temperature minimum near the arc axis. These effects have been attributed, on the basis of different computational models, to either the increased radiative emission associated with the presence of metal vapour in the arc plasma, or the influence of the metal vapour influx on convective flow in the arc. This question is investigated using a three-dimensional computational model in which the production and the transport of metal vapour are taken into account self-consistently. Parameters relevant to welding of thin sheets of aluminum are examined. For these conditions, it is found that the first effect (the decrease in temperature throughout the arc) is due to both the increased radiative emission and the influence of the metal vapour influx on flow. The second effect (the local temperature minimum, which in this case occurs just below the wire electrode) is a consequence of the influence of aluminum vapour produced from the wire electrode on flow in the arc. By examining published results and the energy balance in the plasma, it is shown that for welding of steel with higher arc currents, the increased radiative emission can lead to a local temperature minimum at a greater distance from the wire electrode.

  8. Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET

    SciTech Connect

    Clarke, C.I.; Adli, E.; Corde, S.; Decker, F.J.; England, R.J.; Erickson, R.; Fisher, A.; Gessner, S.; Hast, C.; Hogan, M.J.; Li, S.Z.; Lipkowitz, N.; Litos, M.; Nosochkov, Y.; Seeman, J.; Sheppard, J.C.; Tudosa, I.; White, G.; Wienands, U.; Woodley, M.; Wu, Z.; /SLAC /UCLA

    2012-09-14

    FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV, 3 nC electron beams, short (20 {micro}m) bunches and small (20 {micro}m wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. FACET is also a source of THz radiation for material studies. We present the FACET design, initial operating experience and first science from the facility.

  9. Having Fun with Physics at the MIT Plasma Science and Fusion Center

    NASA Astrophysics Data System (ADS)

    Rivenberg, P.; Thomas, P.; Censabella, V.; Granville, J.; Nachtrieb, R.; Gangadhara, S.

    1997-11-01

    MIT Plasma Science and Fusion Center staff and students are convinced that students learn best not by studying but by doing. This was the impetus behind a group of MIT graduate students who created Cambridge Physics Outlet, a PSFC spin-off company dedicated to creating hands-on experiments. The same impulse fostered the award-winning Mr. Magnet Program, a traveling presentation which uses a hands-on strategy to engage elementary school children. A number of ingenious experiments will be demonstrated. The PSFC maintains a Home Page on the World Wide Web, which can be reached at HTTP://PFC.MIT.EDU.

  10. Laser-induced fluorescence measurements on plasma science experiments at PPPL

    SciTech Connect

    Koepke, Mark

    2011-12-20

    Collaborative research between WVU and PPPL was carried out at WVU for the purpose of incorporating the sophisticated diagnostic technique known as laser-induced fluorescence (LIF) in the Paul-Trap Simulation Experiment (PTSX) at PPPL. WVU assembled a LIF system at WVU, transported it to PPPL, helped make LIF experiments on the PTSX device, participated in PTSX science, and trained PPPL staff in LIF techniques. In summary, WVU refurbished a non-operational LIF system being loaned from University of Maryland to PPPL and, by doing so, provided PPPL with additional diagnostic capability for its PTSX device and other General Plasma Science experiments. WVU students, staff, and faculty will visit PPPL to collaborate on PTSX experiments in the future.

  11. The technology and science of steady-state operation in magnetically confined plasmas

    NASA Astrophysics Data System (ADS)

    Bécoulet, A.; Hoang, G. T.

    2008-12-01

    The steady-state operation of magnetically confined fusion plasmas is considered as one of the 'grand challenges' of future decades, if not the ultimate goal of the research and development activities towards a new source of energy. Reaching such a goal requires the high-level integration of both science and technology aspects of magnetic fusion into self-consistent plasma regimes in fusion-grade devices. On the physics side, the first constraint addresses the magnetic confinement itself which must be made persistent. This means to either rely on intrinsically steady-state configurations, like the stellarator one, or turn the inductively driven tokamak configuration into a fully non-inductive one, through a mix of additional current sources. The low efficiency of the external current drive methods and the necessity to minimize the re-circulating power claim for a current mix strongly weighted by the internal 'pressure driven' bootstrap current, itself strongly sensitive to the heat and particle transport properties of the plasma. A virtuous circle may form as the heat and particle transport properties are themselves sensitive to the current profile conditions. Note that several other factors, e.g. plasma rotation profile, magneto-hydro-dynamics activity, also influence the equilibrium state. In the present tokamak devices, several examples of such 'advanced tokamak' physics research demonstrate the feasibility of steady-state regimes, though with a number of open questions still under investigation. The modelling activity also progresses quite fast in this domain and supports understanding and extrapolation. This high level of physics sophistication of the plasma scenario however needs to be combined with steady-state technological constraints. The technology constraints for steady-state operation are basically twofold: the specific technologies required to reach the steady-state plasma conditions and the generic technologies linked to the long pulse operation of a

  12. Solar Array Module Plasma Interaction Experiment (SAMPIE): Technical requirements document

    NASA Technical Reports Server (NTRS)

    Hillard, G. Barry; Ferguson, Dale C.

    1992-01-01

    The Solar Array Module Plasma Interactions Experiment (SAMPIE) is a NASA shuttle space flight experiment scheduled for launch in early 1994. The SAMPIE experiment will investigate plasma interactions of high voltage space power systems in low earth orbit. Solar cell modules, representing several technologies, will be biased to high voltages to characterize both arcing and plasma current collection. Other solar modules, specially modified in accordance with current theories of arcing and breakdown, will demonstrate the possibility of arc suppression. Finally, several test modules will be included to study the basic nature of these interactions. The science and technology goals for the project are defined in the Technical Requirements Document (TRD) which is presented here.

  13. Increasing the Number of Women and Underrepresented Minorities in the Plasma Science-A Case Study

    NASA Astrophysics Data System (ADS)

    Lucas, Pamela R.; Post-Zwicker, Andrew

    2000-10-01

    The number of women and underrepresented minorities in plasma science is woefully small.The Princeton Plasma Physics Laboratory (PPPL), for example, consists of 2% women and underrepresented minorities. The historical reasons for this specific case as well as the overall circumstances involving pipeline inclusion are beyond the scope of this paper. The answer, however, is clearly NOT a lack of qualified women and minorities as evidenced by the numbers in other SEM disciplines such as computer science where women earn 27% of the doctoral degrees, African Americans 10% and Hispanics 5%. Over the past five years the number of underrepresented minorities earning degrees in physics and engineering has risen. Since 1995, in an effort to reach this population, PPPL has actively recruited women and underrepresented minority students to its various undergraduate research programs, in particular the National Undergraduate Fellowship Program (NUF) and the Energy Research Undergraduate Laboratory Fellowship (ERULF). The results are encouraging. The details of our efforts, our future plans, and ways of introducing our methods to other laboratories will be discussed.

  14. Flow Dynamics in Arc Welding

    SciTech Connect

    Lowke, John J.; Tanaka, Manabu

    2008-02-21

    The state of the art for numerical computations has now advanced so that the capability is within sight of calculating weld shapes for any arc current, welding gas, welding material or configuration. Inherent in these calculations is 'flow dynamics' applied to plasma flow in the arc and liquid metal flow in the weld pool. Examples of predictions which are consistent with experiment, are discussed for (1) conventional tungsten inert gas welding, (2) the effect of a fraction of a percent of sulfur in steel, which can increase weld depth by more than a factor of two through changes in the surface tension, (3) the effect of a flux, which can produce increased weld depth due to arc constriction, (4) use of aluminium instead of steel, when the much larger thermal conductivity of aluminium greatly reduces the weld depth and (5) addition of a few percent of hydrogen to argon, which markedly increases weld depth.

  15. Flow Dynamics in Arc Welding

    NASA Astrophysics Data System (ADS)

    Lowke, John J.; Tanaka, Manabu

    2008-02-01

    The state of the art for numerical computations has now advanced so that the capability is within sight of calculating weld shapes for any arc current, welding gas, welding material or configuration. Inherent in these calculations is "flow dynamics" applied to plasma flow in the arc and liquid metal flow in the weld pool. Examples of predictions which are consistent with experiment, are discussed for (1) conventional tungsten inert gas welding (2) the effect of a fraction of a percent of sulfur in steel, which can increase weld depth by more than a factor of two through changes in the surface tension (3) the effect of a flux, which can produce increased weld depth due to arc constriction (4) use of aluminium instead of steel, when the much larger thermal conductivity of aluminium greatly reduces the weld depth and (5) addition of a few percent of hydrogen to argon, which markedly increases weld depth.

  16. Technical issues in the conduct of large space platform experiments in plasma physics and geoplasma sciences

    NASA Technical Reports Server (NTRS)

    Szuszczewicz, Edward P.

    1986-01-01

    Large, permanently-manned space platforms can provide exciting opportunities for discoveries in basic plasma and geoplasma sciences. The potential for these discoveries will depend very critically on the properties of the platform, its subsystems, and their abilities to fulfill a spectrum of scientific requirements. With this in mind, the planning of space station research initiatives and the development of attendant platform engineering should allow for the identification of critical science and technology issues that must be clarified far in advance of space station program implementation. An attempt is made to contribute to that process, with a perspective that looks to the development of the space station as a permanently-manned Spaceborne Ionospheric Weather Station. The development of this concept requires a synergism of science and technology which leads to several critical design issues. To explore the identification of these issues, the development of the concept of an Ionospheric Weather Station will necessarily touch upon a number of diverse areas. These areas are discussed.

  17. SAFE II: Large systems space plasma evaluation experiment

    NASA Astrophysics Data System (ADS)

    Carruth, M. R., Jr.; Young, L. E.; Purvis, C. K.; Stevens, N. J.

    1983-05-01

    A shuttle flight experiment, the purpose of which is to obtain space data on the interaction of a high voltage solar array with the ambient space plasma is addressed. This flight experiment is a reflight of the solar array flight experiment, SAFE, except that three active solar array panels, electron release devices and plasma diagnostics are added. This experiment, SAFE 2, evaluates power loss due to parasitic current collected by the solar array, arcing on the solar array and perturbations to the plasma which may increase power loss and disturb plasma and charged particle science acquisition.

  18. Nonthermal Biological Treatments Using Discharge Plasma Produced by Pulsed Power 5. Inactivation of Cryptosporidium Oocysts by UV Emission Generated from Pulsed Arc Discharge in Water

    NASA Astrophysics Data System (ADS)

    Kunitomo, Shinta

    Cryptosporidium contaminates most surface waters around the world. It is difficult to remove through conventional treatment processes, and is extremely resistant to the method of chemical disinfection typically used to inactivate these microorganisms. We have developed a new technology for inactivating Cryptosporidium oocysts by using a pulsed arc discharge in water, which creates shock waves, UV emissions, and radicals. The pulsed arc is generated between two cylindrical stainless steel rod electrodes, 6 mm in diameter, and 2 mm apart. We applied this method to the inactivation of oocysts in backwash water from a sand-filter unit of a drinking water plant. The results indicate that the major factor influencing inactivation is UV emissions, and that more than 99% of the oocysts in the high turbidity backwash water (80 NTU) are inactivated with an energy of 0.24 kWh/m3.

  19. Arc tracks on nanostructured surfaces after microbreakdowns

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  20. Arc-shock interaction inside a supersonic nozzle

    SciTech Connect

    Fang, M.T.C.; Kwan, S.; Hall, W.

    1996-02-01

    Arcs burning in supersonic nozzles have wide technical applications. They are commonly used in high-voltage circuit breakers, arc heaters, and arc plasma processing systems. The present investigation is aimed at an understanding of the arc behavior inside a modern high-voltage puffer circuit breaker where a high pressure necessary for the generation of a gas blast is produced by the compression of a piston inside the puffer chamber. Flow separation in the thermal layer between the high-temperature arc core and cold flow generates large vortices which deform the shape of the arc core. For the current range investigated, the center of the shock is not sensitive to the current, but is moved upstream relative to that without the arc. The computed features of the interaction are in agreement with the experimental observations of [2] and [3]. The arcing gas is SF{sub 6}.

  1. Analysis of pre-flight modulator voltage calibration data for the Voyager plasma science experiment

    NASA Technical Reports Server (NTRS)

    Nastov, Ognen

    1988-01-01

    The Voyager Plasma Science (PLS) modulator calibration (MVM) data analysis was undertaken in order to check the correctness of the fast A/D converter formulas that connect low voltage monitor signals (MV) with digital outputs (DN), to determine the proportionality constants between the actual modulator grid potential (V) and the monitor voltage (MV), and to establish an algorithm to link the digitized readouts (DN) with the actual grid potential (V). The analysis results are surprising in that the derived conversion constants deviate by fairly significant amounts from their nominal values. However, it must be kept in mind that the test results which were used for analysis may be very imprecise. Even if it is assumed that the test result errors are very large, they do no appear to be capable to account for all discrepancies between the theoretical expectations and the results of the analysis. Measurements with the flight spare instrument appear to be the only means of investigating these effects further.

  2. Polar cap arcs: Sun-aligned or cusp-aligned?

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Paxton, L. J.; Zhang, Qinghe; Xing, Zanyang

    2016-08-01

    Polar cap arcs are often called sun-aligned arcs. Satellite observations reveal that polar cap arcs join together at the cusp and are actually cusp aligned. Strong ionospheric plasma velocity shears, thus field aligned currents, were associated with polar arcs and they were likely caused by Kelvin-Helmholtz waves around the low-latitude magnetopause under a northward IMF Bz. The magnetic field lines around the magnetopause join together in the cusp region so are the field aligned currents and particle precipitation. This explains why polar arcs are cusp aligned.

  3. Temperature measurement of an atmospheric pressure arc discharge plasma jet using the diatomic CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}, violet system) molecular spectra

    SciTech Connect

    Moon, Se Youn; Kim, D. B.; Gweon, B.; Choe, W.

    2009-03-01

    The CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}) molecular emission spectrum is used to measure both the vibrational and rotational temperatures in atmospheric pressure arc jet discharges. The vibrational and rotational temperature effects on the synthetic diatomic molecular spectra were investigated from the (v{sup '},v{sup ''})=(0,0) band to the (5,5) band. The temperatures obtained from the synthetic spectra compared with the experimental result of a low-frequency arc discharge show a vibrational temperature of (4250-5010) K and a rotational temperature of (3760-3980) K for the input power in the range of (80-280) W. As the (0,0) band is isolated from other vibrational transition bands, determination of the rotational temperature is possible based only on the (0,0) band, which simplifies the temperature measurement. From the result, it was found that the CN molecular spectrum can be used as a thermometer for atmospheric pressure plasmas containing carbon and nitrogen.

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

    PubMed

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

    2016-03-01

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

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

    PubMed

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

    2016-03-01

    As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius. PMID:26558995

  6. Critical Length Criterion and the Arc Chain Model for Calculating the Arcing Time of the Secondary Arc Related to AC Transmission Lines

    NASA Astrophysics Data System (ADS)

    Cong, Haoxi; Li, Qingmin; Xing, Jinyuan; Li, Jinsong; Chen, Qiang

    2015-06-01

    The prompt extinction of the secondary arc is critical to the single-phase reclosing of AC transmission lines, including half-wavelength power transmission lines. In this paper, a low-voltage physical experimental platform was established and the motion process of the secondary arc was recorded by a high-speed camera. It was found that the arcing time of the secondary arc rendered a close relationship with its arc length. Through the input and output power energy analysis of the secondary arc, a new critical length criterion for the arcing time was proposed. The arc chain model was then adopted to calculate the arcing time with both the traditional and the proposed critical length criteria, and the simulation results were compared with the experimental data. The study showed that the arcing time calculated from the new critical length criterion gave more accurate results, which can provide a reliable criterion in term of arcing time for modeling and simulation of the secondary arc related with power transmission lines. supported by National Natural Science Foundation of China (Nos. 51277061 and 51420105011)

  7. Portable rotating discharge plasma device

    NASA Astrophysics Data System (ADS)

    Dwyer, B. L.; Brooks, N. H.; Lee, R. L.

    2011-10-01

    We constructed two devices for the purpose of educational demonstration: a rotating tube containing media of two densities to demonstrate axial confinement and a similar device that uses pressure variation to convert a long plasma glow discharge into a long straight arc. In the first device, the buoyant force is countered by the centripetal force, which confines less dense materials to the center of the column. Similarly, a plasma arc heats the gas through which it passes, creating a hot gaseous bubble that is less dense than the surrounding medium. Rotating its containment envelope stabilizes this gas bubble in an analogous manner to an air bubble in a rotating tube of water. In addition to stabilization, the rotating discharge also exhibits a decrease in buoyancy-driven convection currents. This limits the power loss to the walls, which decreases the field strength requirement for maintaining the arc. These devices demonstrate principles of electrodynamics, plasma physics, and fluid mechanics. They are portable and safe for classroom use. Work supported by US DOE under DE-FC02-04ER54698 and the National Undergraduate Fellowship in Fusion Science and Engineering.

  8. Solar Array Arcing in LEO How Much Charge is Discharged?

    NASA Technical Reports Server (NTRS)

    Ferguson, D. C.; Vayner, B. V.; Galofaro, J. T.

    2004-01-01

    It is often said that only the solar array or spacecraft surface that can be reached by an arc plume are discharged in a solar array arc in LEO (Low Earth Orbit). We present definitive results from ground test experiments done in the National Plasma Interactions (N-PI) facility at the NASA Glenn Research Center that this idea is mistaken. All structure surfaces in contact with the surrounding plasma and connected to spacecraft ground are discharged, whether the arc plasma can reach them or not. Implications from the strength and damaging effects of areas on LEO spacecraft are discussed, and mitigation techniques are proposed.

  9. Degradation of Verapamil hydrochloride in water by gliding arc discharge.

    PubMed

    Krishna, Syam; Maslani, Alan; Izdebski, Tomasz; Horakova, Marta; Klementova, Sarka; Spatenka, Petr

    2016-06-01

    This study investigated the influence of gliding arc plasma discharge on the degradation of Verapamil hydrochloride in water. The plasma discharge was characterized by means of optical emission spectroscopy. Spectra of various atomic and molecular species were observed. Aqueous solution of Verapamil hydrochloride was exposed to gliding arc discharge operated in continuous discharge at atmospheric pressure and room temperature. The identification of Verapamil, the degradation mechanisms of Verapamil and its transformation products were performed using liquid chromatography - mass spectrometry (HPLC-MS). Experimental results indicate that the atmospheric pressure gliding arc plasma treatment has noticeable effects on Verapamil with satisfactory degradation efficiency. Plausible mechanisms of the degradation were discussed. PMID:26953731

  10. A burning plasma program strategy to advance fusion energy. Report of the Fusion Energy Sciences Advisory Committee, Burning Plasma Strategy Panel

    SciTech Connect

    None, None

    2002-09-01

    Fusion energy shows great promise to contribute to securing the energy future of humanity. The risk of conflicts arising from energy shortages and supply cutoffs, as well as the risk of severe environmental impacts from existing methods of energy production, are strong reasons to pursue fusion energy now. The world effort to develop fusion energy is at the threshold of a new stage in its research: the investigation of burning plasmas. This investigation, at the frontier of the physics of complex systems, would be a huge step in establishing the potential of magnetic fusion energy to contribute to the world’s energy security. The defining feature of a burning plasma is that it is self-heated: the 100 million degree temperature of the plasma is maintained mainly by the heat generated by the fusion reactions themselves, as occurs in burning stars. The fusion-generated alpha particles produce new physical phenomena that are strongly coupled together as a nonlinear complex system. Understanding all elements of this system poses a major challenge to fundamental plasma physics. The technology needed to produce and control a burning plasma presents challenges in engineering science similarly essential to the development of fusion energy.

  11. Rotating arc spark plug

    DOEpatents

    Whealton, John H.; Tsai, Chin-Chi

    2003-05-27

    A spark plug device includes a structure for modification of an arc, the modification including arc rotation. The spark plug can be used in a combustion engine to reduce emissions and/or improve fuel economy. A method for operating a spark plug and a combustion engine having the spark plug device includes the step of modifying an arc, the modifying including rotating the arc.

  12. Low Temperature Plasma Science: Not Only the Fourth State of Matter but All of Them. Report of the Department of Energy Office of Fusion Energy Sciences Workshop on Low Temperature Plasmas, March 25-57, 2008

    SciTech Connect

    2008-09-01

    Low temperature plasma science (LTPS) is a field on the verge of an intellectual revolution. Partially ionized plasmas (often referred to as gas discharges) are used for an enormous range of practical applications, from light sources and lasers to surgery and making computer chips, among many others. The commercial and technical value of low temperature plasmas (LTPs) is well established. Modern society would simply be less advanced in the absence of LTPs. Much of this benefit has resulted from empirical development. As the technology becomes more complex and addresses new fields, such as energy and biotechnology, empiricism rapidly becomes inadequate to advance the state of the art. The focus of this report is that which is less well understood about LTPs - namely, that LTPS is a field rich in intellectually exciting scientific challenges and that addressing these challenges will result in even greater societal benefit by placing the development of plasma technologies on a solid science foundation. LTPs are unique environments in many ways. Their nonequilibrium and chemically active behavior deviate strongly from fully ionized plasmas, such as those found in magnetically confined fusion or high energy density plasmas. LTPs are strongly affected by the presence of neutral species-chemistry adds enormous complexity to the plasma environment. A weakly to partially ionized gas is often characterized by strong nonequilibrium in the velocity and energy distributions of its neutral and charged constituents. In nonequilibrium LTP, electrons are generally hot (many to tens of electron volts), whereas ions and neutrals are cool to warm (room temperature to a few tenths of an electron volt). Ions and neutrals in thermal LTP can approach or exceed an electron volt in temperature. At the same time, ions may be accelerated across thin sheath boundary layers to impact surfaces, with impact energies ranging up to thousands of electron volts. These moderately energetic electrons

  13. DC arc weld starter

    DOEpatents

    Campiotti, Richard H.; Hopwood, James E.

    1990-01-01

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

  14. Of Eggs and Arcs

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    New scenarios for the origins of Saturn’s rings/interior moons have directed scientific attention to the region just exterior to Saturn’s main rings. Four satellites (Aegaeon = Ae; Anthe = An; Methone = Me; Pallene = Pa) discovered by the Cassini mission on either side of Mimas’s orbit perhaps comprise a distinct class of ring-moon. They are tiny (R = 0.3-2.5 km); three (AeAnMe) are trapped in co-rotation resonances with Mimas and reside within ring-arcs; and at least two (MePa) have remarkably regular shapes. Images with pixel scales as fine as 27 m taken in May 2012 reveal Methone to be ovoid within 10 m (from sub-pixel limb detection) and devoid of any craters (>130 m) across its 9 km2 of surface; Pallene and even tiny Aegaeon have similar appearances in lesser-quality images. Numerical simulations demonstrate that particles comprising the surrounding ring-arcs populate the same resonances as their embedded moons; escape speeds from the moons are < 0.5 m/s, smaller than the 2 m/s that dynamically characterize the resonant well. We investigate the gentle transfer of particles back and forth between the ring-arcs and any embedded bodies. In this environment, the moons’ shapes are smooth equipotentials; electrostatic effects may also determine how grains settle to surfaces. Considering these shapes to represent equipotential surfaces for rotating, tidally distorted, homogeneous bodies, we infer mean satellite densities of 250+/-60 (Pa), 310+/-30 (Me), and 540+/-120 (Ae) kg m-3. About half of Methone’s leading hemisphere is covered by a sharply bounded, lemon-shaped, relatively dark region, having a form reminiscent of Mimas’s thermal anomaly (Howett et al. 2011). Its (601 nm) albedo is 13% lower than the bounding brighter material. An irregularly shaped, even-darker (by 4%) blotch straddles the apex of the moon’s motion. Impacts with circum-planetary meteoroids and plasma are likely responsible for these features.

  15. Arcing in LEO: Does the Whole Array Discharge?

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Vayner, Boris V.; Galofaro, Joel T.; Hillard, G. Barry

    2005-01-01

    The conventional wisdom about solar array arcing in LEO is that only the parts of the solar array that are swept over by the arc-generated plasma front are discharged in the initial arc. This limits the amount of energy that can be discharged. Recent work done at the NASA Glenn Research Center has shown that this idea is mistaken. In fact, the capacitance of the entire solar array may be discharged, which for large arrays leads to very large and possibly debilitating arcs, even if no sustained arc occurs. We present the laboratory work that conclusively demonstrates this fact by using a grounded plate that prevents the arc-plasma front from reaching certain array strings. Finally, we discuss the dependence of arc strength and arc pulse width on the capacitance that is discharged, and provide a physical mechanism for discharge of the entire array, even when parts of the array are not accessible to the arc-plasma front. Mitigation techniques are also presented.

  16. Arcing in LEO - Does the Whole Array Discharge?

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Vayner, Boris V.; Galofaro, Joel T.; Hillard, G. Barry

    2005-01-01

    The conventional wisdom about solar array arcing in LEO is that only the parts the solar array that are swept over by the arc-generated plasma front are discharged in the initial arc. This limits the amount of energy that can be discharged. Recent work done at the NASA Glenn Research Center has shown that this idea is mistaken. In fact, the capacitance of the entire solar array may be discharged, which for large arrays leads to very large and possibly debilitating arcs, even if no sustained arc occurs. We present the laboratory work that conclusively demonstrates this fact by using a grounded plate that prevents the arc-plasma front from reaching certain array strings. Finally, we discuss the dependence of arc strength and arc pulse width on the capacitance that is discharged, and provide a physical mechanism for discharge of the entire array, even when parts of the array are not accessible to the arc-plasma front. Mitigation techniques are also presented.

  17. Acoustic characteristics of electric arc furnaces

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  18. Model/observational data cross analysis in planetary plasma sciences with IMPEx

    NASA Astrophysics Data System (ADS)

    Genot, V. N.; Khodachenko, M.; Kallio, E. J.; Al-Ubaidi, T.; Alexeev, I. I.; Gangloff, M.; Bourrel, N.; andre, N.; Modolo, R.; Hess, S.; Topf, F.; Perez-Suarez, D.; Belenkaya, E. S.; Kalegaev, V. V.; Hakkinen, L. V.

    2013-12-01

    This presentation details how the FP7 IMPEx (http://impex-fp7.oeaw.ac.at/) infrastructure helps scientists in inter-comparing observational and model data in planetary plasma sciences. Within the project, data originate from multiple sources : large observational databases (CDAWeb, AMDA at CDPP, CLWeb at IRAP), simulation databases for hybrid and MHD codes (FMI, LATMOS), planetary magnetic field models database and online services (SINP). To navigate in this large data ensemble, IMPEx offers a distributed framework in which these data may be visualized, analyzed, and shared thanks to a set of interoperable tools (AMDA, 3DView, CLWeb). A simulation data model, based on SPASE, has been designed to ease data exchange within the infrastructure. On the communication point of view, the Virtual Observatory paradigm is followed and the architecture is based on web services and the IVOA protocol SAMP. These choices enabled a high level versatility with the goal to allow other model or data providers to distribute their own resources via the IMPEx infrastructure. A detailed use case based on Mars data and hybrid models will be proposed showing how the tools may be operated synchronously to manipulate heterogeneous data sets. Facilitating the analysis of the future MAVEN observations is one possible application of the IMPEx infrastructure.

  19. Development of circuit model for arcing on solar panels

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  20. Filtered cathodic arc deposition apparatus and method

    DOEpatents

    Krauss, Alan R.

    1999-01-01

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