WorldWideScience

Sample records for arc plasma melting

  1. Energy Balance in DC Arc Plasma Melting Furnace

    Institute of Scientific and Technical Information of China (English)

    ZHAO Peng; MENG Yuedong; YU Xinyao; CHEN Longwei; JIANG Yiman; NI Guohua; CHEN Mingzhou

    2009-01-01

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

  2. Energy Balance in DC Arc Plasma Melting Furnace

    Science.gov (United States)

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

    2009-04-01

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

  3. DC Arc Plasma Furnace Melting of Waste Incinerator Fly Ash

    Institute of Scientific and Technical Information of China (English)

    CHEN Mingzhou; MENG Yuedong; SHI Jiabiao; KUANG Jingan; NI Guohua; LIU Wei; JIANG Yiman

    2009-01-01

    Municipal solid waste incinerator (MSWI) fly ash was melted using a set of direct current (DC) arc plasma furnace system for the first time in China.At a feed-rate of flying ash of 80 kg/h,the temperature at the gas outlet was above 1300℃.Dioxins in the off-gas were recorded as 0.029 ng I-TEQ/Nm3 (international toxic equivalent,I-TEQ),well below 0.5 ng TEQ/Nm3 (toxic equivalent,TEQ),while those in the melted product(slag)were 0.00035 ng/g I-TEQ.Molten slag from the furnace showed excellent resistance against the leaching of heavy metals.These results prove that the plasma furnace is effective for the detoxification and stabilization of MSWI fly ash.

  4. Plasma arc melting treatment of low level radioactive waste with centrifugal hearth

    International Nuclear Information System (INIS)

    Plasma Arc Melting technology may possible be able to treat various kinds of waste streams through volume reduction and stabilization into a disposal waste form. The ability of other melting technologies to convert inorganic material in a single step, however, varies according to the characteristics of the materials. Plasma technology also can treat organic waste by selecting the oxidation atmosphere. The Japan Atomic Power Company (JAPC) has decided to construct a low level radioactive waste treatment facility using the Plasma Arc Centrifugal Treatment (PACT) process with an 8 ft rotating hearth and 1.2 MW transferred torch developed by Retech (Ukiah, CA. USA) in the Tsuruga power station. In Japan, the plasma technology has been developed for incineration ash treatment, but the JAPC plant will be the first treatment system using plasma technology for solid waste with various characteristics and shapes. (author)

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

  6. Arc Plasma Torch Modeling

    CERN Document Server

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

    2013-01-01

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

  7. Presentation of the Vulcano installation which uses a plasma transferred arc rotary furnace for corium melting

    International Nuclear Information System (INIS)

    In the case of loss coolant accident, the reactor core could melt and turn into a mixture of uranium oxides, zirconium, iron and steel called corium. A large experimental program has been launched to study corium behaviour, to qualify solutions to stabilize it and to confine it in the reactor containment. The Vulcano installation has been designed to that purpose. It is made up of: i) a plasma transferred arc rotary furnace, ii) a testing surface covered with refractory materials, iii) an induction heating system in order to simulate the residual power of corium, iv) instrumentation devices such as video cameras, thermocouples, infra-red pyrometers and flowmeters, and v) a laboratory to perform chemical analysis of corium samples. The first experimental results show that a mixture of corium and concrete spreads better than expected. It seems that a low initial height of matter can produce a great distance flowing while having a chaotic behaviour. This characteristic suggests that the mixture acts as a Bingham type threshold fluid. (A.C.)

  8. Development of melting and incinerating system using plasma arc heating for low level radioactive miscellaneous solid waste

    International Nuclear Information System (INIS)

    Various low level radioactive miscellaneous solid wastes are stored on sites of nuclear power plants and research laboratories. The volume of these wastes should be reduced before disposal. A wastes processing facility using plasma arc as the heat source is promising to reduce the volume of wastes. Incombustible wastes such as steels and concrete are melted, and non-combustible materials such as plastics and resins are simultaneously incinerated in it. The high energy density of plasma arc results in a short processing time and high volume reduction ratio. The authors have performed design and experimental studies on the facility. This paper describes the objectives and characteristics of the facility, and the major results of the studies. (author)

  9. Investigation of In-Flight Melting Behaviour of Granulated Glass Raw Material by Multi-Phase AC Arc Plasma and Hybrid Plasma

    International Nuclear Information System (INIS)

    An innovative in-flight glass melting technology was developed for a purpose of energy saving and environmental protection. Granulated glass raw materials with small diameter were treated by twelve-phase AC arc and that combined with an oxygen burner. The particle measurement was carried out to investigate the in-flight melting behavior of glass raw materials during the in-flight melting by twelve-phase AC arc. Obtained results show the mean particle velocity was about 9 m s-1 and mean temperature was about 2600 K. The high vitrification degree achieved within several milliseconds reveals that the new in-flight melting technology of hybrid plasma treating can reduce energy consumption and shorten the glass production cycle.

  10. Quality of steel melted in plasma-arc furnace with ceramic crucible

    International Nuclear Information System (INIS)

    The particular features are discussed involved in the melting of steels Kh18N10T, 000Kh18N11, Kh12M and some others in a plasmarc furnace with a ceramic crucible. Conditions are considered providing for the best metal deoxidation, nitrogen dissolving in a hot metal, removal of impurities. Examination of stainless, tool and other high-alloy steels produced in plasmarc furnaces has revealed that these steels, as far as oxygen and nonmetallics content is concerned, are purer than the metal obtained in open arc furnaces. Indications are presented for the higher technological plasticity of tool rapid and stainless steels, the better corrosion resistance of stainless steels and the enhanced durability of steels for electric heaters, the more favourable strength properties of the materials under consideration. The plasmarc melting in combination with the various forms of refining remelting is advisable for the steels which are to comply with particularly severe requirements

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

    International Nuclear Information System (INIS)

    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 O2+ ions and C, O, As, Cl, P and S by Cs+ 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 Pi/PCu > 102. On the other hand, removal of O, C, S and Se was expectedly dominated by vaporization in the form of H2O, CH4, H2S, and H2Se 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

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

    Science.gov (United States)

    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.

  13. STUDY ON THE PRESSURE IN PLASMA ARC

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The axial pressure in plasma arc is measured under different conditions. The effects of the parameters, such as welding current, plasma gas flow rate, electrode setback and arc length, on the pressure in plasma arc are investigated and quantitative analyzed to explain the relationship between the quality of weld and the matching of parameters in plasma arc welding process.

  14. Melting decontamination of radioactive scrap metal by graphite arc melter

    International Nuclear Information System (INIS)

    The partitioning phenomena of radioisotope cobalt-60 (60Co) and cesium-137 (137Cs) from a molten ingot, slag, and dust have been investigated for the effect of the slag type, slag concentration and basicity in a plasma arc melting process. A direct current plasma arc furnace was used to melt contaminated stainless steel, and mild steel with an acid, neutral, and basic slag (SiO2, CaO, Al2O3, Fe2O3, MgO) containing radioactive 60Co and 137Cs, to measure the partitioning phenomena. Calcium oxide and ferric oxide were added to provide an increase in the slag fluidity and oxidative potential, respectively. Most of the 60Co remained in the ingot phase and was barely present in the slag. 60Co decontamination factor was not highly dependent on the slag composition. The distribution ratio of 60Co the ingot and the slag phase showed that about 90% to 95% was recovered in the ingots. 137Cs was completely eliminated from the melt of the stainless steel as well as the carbon steel, and was distributed to the slag and dust phase. The partition remaining in the slag depended on whether the slag was basic or acidic and had a high oxidative flux (Fe2O3). A maximum of 52% of the 137Cs remained in the slag phase with an acid slag. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Mahrle, A; Schnick, M; Rose, S; Demuth, C; Beyer, E; Fuessel, U, E-mail: achim.mahrle@iws.fraunhofer.de [Dresden University of Technology, Institute of Surface and Manufacturing Technology, PO Box, D-01062 Dresden (Germany)

    2011-08-31

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

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

    Science.gov (United States)

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

    2011-08-01

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

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

    International Nuclear Information System (INIS)

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

  18. A rotating arc plasma invertor

    International Nuclear Information System (INIS)

    A device is described for the inversion of direct current to alternating current. The main feature is the use of a rotating plasma arc in crossed electric and magnetic fields as a switch. This device may provide an economic alternative to other inversion methods in some circumstances

  19. Modeling of Arc Force in Plasma Arc Welding

    Institute of Scientific and Technical Information of China (English)

    GAO Zhonglin; HU Shengsun; YIN Fengliang; WANG Rui

    2008-01-01

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

  20. Models of plasma arc welding

    International Nuclear Information System (INIS)

    A complex model of energy transfer from ionized gas through a weld-pool to a heat affected zone (HAZ) is considered here. The model consists of three sub-models: a model of the arc column with skin layers - sheaths coating electrodes, a model of liquid metal flow in a weld-pool, and a model of coupled thermo-mechanical-metallurgical processes in HAZ. These sub-models are descried in three reports. The first report is devoted to a short review of welding plasma models based mostly on the Magneto-Hydro-Dynamics (MHD) theory successfully applied to the simulation of welding process. This report is illustrated by arc models for TIG and PAW welding. The description of thermal energy transfer between three sub-regions of the complex welding domain refers to a large number of processes observed in gaseous electronics, thermodynamics of reacting gases, electro-dynamics of fluid, micro-metallurgy. (author)

  1. ARC length control for plasma welding

    Science.gov (United States)

    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.

  2. Simulation of Magnetically Dispersed Arc Plasma

    Institute of Scientific and Technical Information of China (English)

    白冰; 查俊; 张晓宁; 王城; 夏维东

    2012-01-01

    Magnetically dispersed arc plasma exhibits typically dispersed uniform arc column as well as diffusive cathode root and diffusive anode root. In this paper magnetically dispersed arc plasma coupled with solid cathode is numerically simulated by the simplified cathode sheath model of LOWKE . The numerical simulation results in argon show that the maximum value of arc root current density on the cathode surface is 3.5×10^7 A/m^2), and the maximum value of energy flux on the cathode surface is 3× 10^7 J/m^2, both values are less than the average values of a contracted arc, respectively.

  3. Electric arc furnace melting of simulated transuranic wastes

    International Nuclear Information System (INIS)

    As part of an interagency agreement between the Bureau of Mines, US Department of the Interior, and the US Department of Energy through its contractor, EG and G Idaho, Inc., the Bureau conducted six melting tests at its Albany Research Center to assess the feasibility of melting transuranic-containing wastes. The tests were conducted with simulated wastes in a conventional refractory-lined electric arc furnace. Charge materials included concrete, soil, metal, wood, CaO- and Na2O-containing chemical waste sludges, cement, and polyethylene mixed in various proportions in both unburned and partially incinerated forms. The investigation showed that it is possible to melt these materials in a 1-metric-ton conventional electric arc furnace and separate the slag and metal provided that suitable fluxes are added to condition the silicious slages. However, the electric arc furnace cannot be considered an efficient incinerator. The molten slags were poured into 210-liter steel drums having a 0.64-cm-thick steel chill plate on the bottom. All slags were tapped from the furnace satisfactorily. The concrete and sludge materials required the most energy for melting (2.2 to 2.6 kWhr/kg). The highest electrode consumption occurred when the sludges were melted (0.04 kg/kg product). A high alumina-chrome refractory is satisfactory for use as a furnace lining in melting these wastes. Offgases and particulates from all of the tests were sampled and analyzed. The greatest amounts of particulate matter in the offgas streams were obtained from melting sludges and incinerated wastes. It is recommended that if a conventional electric arc furnace is used to melt transuranic waste that it (1) be fed slowly to prevent excessive fumes and flames and (2) be operated continuously to minimize startup problems and improve efficiency

  4. Plasma arc cutting: speed and cut quality

    International Nuclear Information System (INIS)

    When cutting metal with plasma arc cutting, the walls of the cut are narrower at the bottom than at the top. This lack of squareness increases as the cutting speed increases. A model of this phenomenon, affecting cut quality, is suggested. A thin liquid layer, which separates the plasma from the solid metal to be melted, plays a key role in the suggested model. This layer decreases heat transfer from the plasma to the solid metal; the decrease is more pronounced the higher the speed and the thicker the liquid metal layer. Since the layer is thicker at the bottom of the cut, the heat transfer effectiveness is lower at the bottom. The decrease in heat transfer effectiveness is compensated by the narrowness of the cut. The suggested model allows one to calculate the profile of the cut. The result of the calculations of the cutting speeds for plates of various thicknesses, at which the squareness of the cut is acceptable, agrees well with the speeds recommended by manufacturers. The second effect considered in the paper is the deflection of the plasma jet from the vertical at a high cutting speed. A qualitative explanation of this phenomenon is given. We believe the considerations of this paper are pertinent to other types of cutting with moving heat sources.

  5. Plasma arc remelting of steels and nickel-based superalloys

    International Nuclear Information System (INIS)

    The IRC Plasma Arc Cold Hearth Remelting (PACHR) furnace has been used to produce 100mm and 150mm diameter ingots of alloy 718, M50 bearing steel and G110 maraging steel from VIM/VAR feedstocks. These trials highlighted the importance of accurately controlling the level of the melt pool surface in the crucible in order to produce an acceptable ingot finish. Chemical analysis of the ingots produced indicated no significant changes in the level of any element. Cleanness of the ingots has been assessed using the Electron Beam Button Melt (EBBM) technique. The results obtained are encouraging but highlight the necessity for careful control of the plasma remelting process. (orig.)

  6. Plasma Arc Augmented CO2 laser welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Andersen, Mikkel; Frederiksen, Niels;

    2001-01-01

    In order to reduce the hardness of laser beam welded 2.13 mm medium strength steel CMn 250, a plasma arc has been used simultaneously with a 2.6 kW CO2 laser source. In a number of systematic laboratory tests, the plasma arc current, plasma gas flow and distance to the laser source were varied with....... With the addition of a plasma arc, the hardness could overall be reduced to between 200 and 220 HV1, i.e. about 27 percent. In the seam middle, the reduction was 36 percent....

  7. Arc Magma Genesis from Melting of Mélange Diapirs

    Science.gov (United States)

    Cruz-Uribe, A. M.; Marschall, H.; Gaetani, G. A.

    2015-12-01

    Alkaline basalts occur in many subduction-related volcanic settings, including the Sunda, Izu-Bonin, Honshu, Aeolian, and Aleutian arcs, yet their origin continues to be debated. Recent studies have suggested that buoyant material (mélange) from the slab-wedge interface may rise into the hot corner of the mantle wedge as low-density plumes or diapirs, where it will melt or induce mantle melting due to dehydration. High-pressure mélange rocks represent a mixture of mafic, ultramafic, and sedimentary components, and are often dominated by chlorite. Mélange rocks are also enriched in accessory phases such as monazite, zircon, and rutile, which host a variety of trace elements. We present results from experimental melting of chlorite-rich mélange material at mantle wedge conditions that reproduce many of the compositional features of subduction-related lavas. Piston cylinder experiments were performed at conditions appropriate for mantle wedge diapirs (1030-1280 °C, 1.5-2.5 GPa) using natural mélange rocks from Syros, Greece. Experimental melts derived from omphacite-epidote-phengite bearing chlorite schists range in composition from basaltic trachyandesites to trachydacites to more alkaline melt compositions (50.7-60.73 wt% SiO2, 7.48-12.93 wt% Na2O+K2O). All of the experimental melts are characterized by high alumina contents (16.79-21.36 wt% Al2O3). Minerals coexisting with these melts include clinopyroxene, amphibole (at lower T) or olivine (at higher T), garnet (at higher P), ilmenite and/or rutile, and zircon. Trace element patterns in our experimentally produced melts are similar to those from arc volcanoes worldwide. Experimental melts are enriched in large ion lithophile elements (Cs, Rb, Ba, K, Pb, Sr) and depleted in high field strength elements (Nb, Ta, and Ti). Zirconium and Hf are enriched relative to the rare earth elements (REE), which show flat to heavy REE depleted patterns depending on the presence of residual garnet. Thorium is fractionated

  8. Melt decontamination of aluminum waste by electric arc melting

    International Nuclear Information System (INIS)

    In Korea, the decontamination and decommissioning of the retired TRIGA MARK II and III research reactors and a uranium conversion plant at the Korea Atomic Energy Research Institute (KAERI) has been under way. Hundreds of tons of metallic wastes are expected from the D and D of these facilities Therefore, prompt countermeasures should be taken to deal with the amount of wastes generated by dismantling the retired nuclear facilities. Most of the dismantled material is slightly contaminated. A recycle or volume reduction of the metallic wastes can be considered as one of the waste management options under the circumstances of the absence of a waste disposal site in Korea and the capacity limitation of the temporary waste storage facility at KAERI. The results of the XRD analysis showed that the surrogate nuclides move into the slag, which can be easily separated from the melt, and then they combine with the aluminum oxide to form a more stable compound. The distribution ratio of cobalt in the ingot was more than 40% according to the types of fluxes. A removal efficiency of more than 98% for the cesium and strontium from the ingot could be achieved due to their transportation from the ingot to the slag and the dust phase. Therefore, it can be expected that a greater part of the aluminum wastes generated from the retired research reactors can be recycled or their volumes reduced for a disposal by a melting

  9. Melt decontamination of aluminum waste by electric arc melting

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Wang Kyu; Song, Pyung Seob; Jung, Chong Hun; Oh, Won Zin [Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of); Min, Byung Youn [Chungnam National University, Taejeon (Korea, Republic of)

    2005-11-15

    In Korea, the decontamination and decommissioning of the retired TRIGA MARK II and III research reactors and a uranium conversion plant at the Korea Atomic Energy Research Institute (KAERI) has been under way. Hundreds of tons of metallic wastes are expected from the D and D of these facilities Therefore, prompt countermeasures should be taken to deal with the amount of wastes generated by dismantling the retired nuclear facilities. Most of the dismantled material is slightly contaminated. A recycle or volume reduction of the metallic wastes can be considered as one of the waste management options under the circumstances of the absence of a waste disposal site in Korea and the capacity limitation of the temporary waste storage facility at KAERI. The results of the XRD analysis showed that the surrogate nuclides move into the slag, which can be easily separated from the melt, and then they combine with the aluminum oxide to form a more stable compound. The distribution ratio of cobalt in the ingot was more than 40% according to the types of fluxes. A removal efficiency of more than 98% for the cesium and strontium from the ingot could be achieved due to their transportation from the ingot to the slag and the dust phase. Therefore, it can be expected that a greater part of the aluminum wastes generated from the retired research reactors can be recycled or their volumes reduced for a disposal by a melting.

  10. Thermal Plasma Generators with Water Stabilized Arc

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan

    2009-01-01

    Roč. 2, č. 1 (2009), s. 99-104. ISSN 1876-5343 R&D Projects: GA ČR GA202/08/1084 Institutional research plan: CEZ:AV0Z20430508 Keywords : Thermal plasma * plasma torch * Gerdien arc Subject RIV: BL - Plasma and Gas Discharge Physics http://www.bentham.org/open/toppj/openaccess2.htm

  11. Characterization of Mullite-Zirconia Composite Processed by Non-Transferred and Transferred Arc Plasma

    Institute of Scientific and Technical Information of China (English)

    S. YUGESWARAN; V. SELVARAJAN; L. LUSVARGHI; A. I. Y. TOK; D. SIVA RAMA KRISHNA

    2009-01-01

    The arc plasma melting technique is a simple method to synthesize high temperature reaction composites. In this study, mullite-zirconia composite was synthesized by transferred and non-transferred arc plasma melting, and the results were compared. A mixture of alumina and zircon powders with a mole ratio of 3 : 2 were ball milled for four hours and melted for two minutes in the transferred and non-transferred mode of plasma arcs. Argon and air were used as plasma forming gases. The phase and microstructural formation of melted samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The microstructure of the com-posites was found to be affected by the mode of melting. In transferred arc melting, zirconia flowers with uniform lines along with mullite whiskers were obtained. In the case of non-transferred arc plasma melting, mullite whiskers along with star shape zirconia were formed. Differential thermal analysis (DTA) of the synthesized mullite-zirconia composites provided a deeper understanding of the mechanisms of mullite formation during the two different processes.

  12. Plasma distribution of cathodic ARC deposition system

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  13. Surface treatment of 0Cr19Ni9 stainless steel SMAW jointby plasma melting

    Institute of Scientific and Technical Information of China (English)

    罗伟; 栾景飞; 严密

    2002-01-01

    Micro-plasma arc surface melting of 0Cr19Ni9 shielded metal arc welding joint with a micro-plasma arc welder produced a thin surface melted layer with a refined microstructure. The surface treatment changed the anodic polarization behavior in 0.5 mol/L H2SO4 solution. The polarization tests showed that for the as-welded joint both the heat-affected zone and the weld metal decreased in resistance to corrosion compared with the as-Received parent material while for the micro-plasma arc surface melted joint the corrosion resistance increased significantly. This increase in corrosion resistance is attributed to the rapid solidification of the melted layer. Rapid solidification of the melted layer refines its microstructure, decreases its microsegregation, and inhibits the precipitation of chromium carbides at the grain boundaries.received parent material while for the micro-plasma arc surface melted joint the corrosion resistance increased significantly. This increase in corrosion resistance is attributed to the rapid solidification of the melted layer. Rapid solidification of the melted layer refines its microstructure, decreases its microsegregation, and inhibits the precipitation of chromium carbides at the grain boundaries.

  14. Study on Expansion Process of EDM Arc Plasma

    Science.gov (United States)

    Natsu, Wataru; Shimoyamada, Mayumi; Kunieda, Masanori

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

  15. Melting Characteristics for Radioactive Aluminum Wastes in Electric Arc Furnace

    Energy Technology Data Exchange (ETDEWEB)

    Song, Pyung Seob; Ahn, Jun Hyung; Cho, Wang Kyu; Jung, Chong Hun; Oh, Won Zin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Min, Byung Youn; Kang, Yong [School of Chemical Emgineering, Chungnam National University, Daejeon (Korea, Republic of)

    2006-03-15

    The characteristics of the aluminum waste melting and the distribution of the radioactive nuclides have been investigated for the estimation on the volume reduction and the decontamination of the aluminum wastes from the decommissioning of the TRIGA MARK II and III research reactors at the Korea Atomic Energy Research Institute(KAERI). The aluminum wastes were melted with the use of the fluxes such as flux A : NaCl-KCl-Na{sub 3}AlF{sub 6}, flux B : NaCl-NaF-KF, flux C : CaF{sub 2}, and flux D : LiF-KCl-BaCl{sub 2} in the DC graphite arc furnace. For the assessment of the distribution of the radioactive nuclides during the melting of the aluminum, the aluminum materials were contaminated by the surrogate nuclides such as cobalt(Co), cesium(Cs) and strontium(Sr). The fluidity of aluminum melt was increased with the addition of the fluxes, which has slight difference according to the type of fluxes. The formation of the slag during the aluminum melting added the flux type C and D was larger than that with the flux A and B. The rate of the slag formation linearly increased with increasing the flux concentration. The results of the XRD analysis showed that the surrogate nuclide was transferred to the slag, which can be easily separated from the melt and then they combined with aluminum oxide to form a more stable compound. The distribution ratio of cobalt in ingot to that in slag was more than 40% at all types of fluxes. Since vapor pressures of cesium and strontium were higher than those that of the host metals at the melting temperature, their removal efficiency from the ingot phase to the slag and the dust phase was by up to 98%.

  16. Melting Characteristics for Radioactive Aluminum Wastes in Electric Arc Furnace

    International Nuclear Information System (INIS)

    The characteristics of the aluminum waste melting and the distribution of the radioactive nuclides have been investigated for the estimation on the volume reduction and the decontamination of the aluminum wastes from the decommissioning of the TRIGA MARK II and III research reactors at the Korea Atomic Energy Research Institute(KAERI). The aluminum wastes were melted with the use of the fluxes such as flux A : NaCl-KCl-Na3AlF6, flux B : NaCl-NaF-KF, flux C : CaF2, and flux D : LiF-KCl-BaCl2 in the DC graphite arc furnace. For the assessment of the distribution of the radioactive nuclides during the melting of the aluminum, the aluminum materials were contaminated by the surrogate nuclides such as cobalt(Co), cesium(Cs) and strontium(Sr). The fluidity of aluminum melt was increased with the addition of the fluxes, which has slight difference according to the type of fluxes. The formation of the slag during the aluminum melting added the flux type C and D was larger than that with the flux A and B. The rate of the slag formation linearly increased with increasing the flux concentration. The results of the XRD analysis showed that the surrogate nuclide was transferred to the slag, which can be easily separated from the melt and then they combined with aluminum oxide to form a more stable compound. The distribution ratio of cobalt in ingot to that in slag was more than 40% at all types of fluxes. Since vapor pressures of cesium and strontium were higher than those that of the host metals at the melting temperature, their removal efficiency from the ingot phase to the slag and the dust phase was by up to 98%.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, Valerian, E-mail: nemchinsky@bellsouth.ne [Keiser University, Fort Lauderdale, FL 33309 (United States)

    2009-10-21

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

  18. Radioactive waste combustion / vitrification under arc plasma: thermal and dynamic modelling

    International Nuclear Information System (INIS)

    This thesis concerns the thermal and dynamic modelling for a combustion/vitrification process of surrogate radioactive waste under transferred arc plasma. The writer presents the confinement processes for radioactive waste using arc plasma and the different software used to model theses processes. This is followed by a description of our experimental equipment including a plasma arc reactor and an inductive system allowing the homogenization of glass temperature. A combustion/vitrification test is described. Thermal and material balances were discussed. The temperature fields of plasma arc and the glass frit conductivity are measured. Finally, the writer describes and clarifies the equations solved for the simulations of the electrically plasma arc and the glass melting including the thin layer of glass frit coating the crucible cold walls. The modelling results are presented in the form of spatial distribution of temperature, velocity and volume power... (author)

  19. Plasma melting of miscellaneous solid waste containing rubber

    International Nuclear Information System (INIS)

    Miscellaneous solid waste contains burnable and/or non-burnable materials besides metallic waste. When non-metallic waste is treated by transferred arc plasma, plasma stability may be decreased by the low electrical conductivity of the materials. This paper describes the result of an experiment in which rubber as a typical burnable waste was fed into the crucible of an operating experimental plasma furnace. The power of the plasma was 20 to 50 kW. The base materials of the simulated waste were 10 kg of iron and 3 kg of fly-ash. Up to 10 g of rubber was fed after the base materials had melted. The voltage of the arc plasma increased just after the feed, and the increase was almost proportional to the weight of the fed rubber. The intrusion of thermally decomposed products of the rubber into the plasma dominated the voltage increase. The voltage increase was investigated for several operating conditions of the furnace. The increase of air injection into the furnace and that of arc current controlled the voltage increase during feeding, but the increase of plasma working gas aggravated it. (author)

  20. Electric-arc steam plasma generator

    Science.gov (United States)

    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.

  1. Experimental investigation of energy balance in plasma arc cutting process

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Tossens, S.; Mašláni, Alan; Konrád, Miloš; Pauser, H.; Stehrer, T.

    Vol. 511. Bristol: IOP Publishing, 2014, 012067-012067. (IoP. 511). ISSN 1742-6588. [International Congress on Plasma Physics (ICPP) / 13th Latin American Workshop on Plasma Physics (LAWPP)/15./. Santiago, CHILE (CL), 08.08.2010-13.08.2010] Institutional support: RVO:61389021 Keywords : plasma arc cutting * arc cutting * plasma arc Subject RIV: BL - Plasma and Gas Discharge Physics http://iopscience.iop.org/1742-6596/511/1/012067/pdf/1742-6596_511_1_012067.pdf

  2. CO2 laser-micro plasma arc hybrid welding for galvanized steel sheets

    Institute of Scientific and Technical Information of China (English)

    C. H. KIM; Y. N. AHN; J. H. KIM

    2011-01-01

    A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal. which is steel. In the autogenous laser welding,the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-heat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap.The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces.Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.

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

    Science.gov (United States)

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

    2016-08-01

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

  4. Dual Torch Plasma Arc Furnace for Medical Waste Treatment

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; M.KIKUCHI; LI Heping; T.IWAO; T.INABA

    2007-01-01

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

  5. Halo formation in arc-melted Cr-Nb alloys

    Science.gov (United States)

    Li, K. W.; Li, S. M.; Xue, Y. L.; Fu, H. Z.

    2012-10-01

    Haloes of Laves phase Cr2Nb around the primary dendrites Cr were observed in the arc-melted Cr-12% Nb hypoeutectic alloy, while no halo of non-faceted Cr phase around the Cr2Nb Laves phase occurred in the Cr-20% Nb hypereutectic alloy. This observation differs from the haloes formed in metal-intermetallic alloy systems. An explanation on the formation of Cr2Nb halo was presented by considering the solidification behavior of the leading phase and non-reciprocal nucleation characteristics of the Cr2Nb/Cr eutectic. In the Cr-12% Nb alloy, primary dendrites Cr worked as a good nucleant available for the occurrence of the halo Cr2Nb that subsequently solidified as the leading phase in the eutectic. For the Cr-20% Nb alloy, primary dendrites Cr2Nb first precipitated as the leading phase inducing the eutectic formation, resulting in no halo growth. In addition, the coupled zone of the Cr-Nb alloy was theoretically predicted in agreement with the experimental results.

  6. Radioactive waste combustion / vitrification under arc plasma: thermal and dynamic modelling; Combustion - vitrification de dechets radioactifs par plasma d'arc: modelisation de la thermique et de la dynamique

    Energy Technology Data Exchange (ETDEWEB)

    Barthelemy, B

    2003-07-01

    This thesis concerns the thermal and dynamic modelling for a combustion/vitrification process of surrogate radioactive waste under transferred arc plasma. The writer presents the confinement processes for radioactive waste using arc plasma and the different software used to model theses processes. This is followed by a description of our experimental equipment including a plasma arc reactor and an inductive system allowing the homogenization of glass temperature. A combustion/vitrification test is described. Thermal and material balances were discussed. The temperature fields of plasma arc and the glass frit conductivity are measured. Finally, the writer describes and clarifies the equations solved for the simulations of the electrically plasma arc and the glass melting including the thin layer of glass frit coating the crucible cold walls. The modelling results are presented in the form of spatial distribution of temperature, velocity and volume power... (author)

  7. Radioactive waste combustion-vitrification under arc plasma: thermal and dynamic modelling; Combustion - vitrification de dechets radioactifs par plasma d'arc: modelisation de la thermique et de la dynamique

    Energy Technology Data Exchange (ETDEWEB)

    Barthelemy, B

    2003-06-01

    This thesis concerns the thermal and dynamic modelling for a combustion/vitrification process of surrogate radioactive waste under transferred arc plasma. The writer presents the confinement processes for radioactive waste using arc plasma and the different software used to model theses processes. This is followed by a description of our experimental equipment including a plasma arc reactor and an inductive system allowing the homogenization of glass temperature. A combustion/vitrification test is described. Thermal and material balances were discussed. The temperature fields of plasma arc and the glass frit conductivity are measured. Finally, the writer describes and clarifies the equations solved for the simulations of the electrically plasma arc and the glass melting including the thin layer of glass frit coating the crucible cold walls. The modelling results are presented in the form of spatial distribution of temperature, velocity and voluminal power... (author)

  8. Modeling of thermal plasma arc technology FY 1994 report

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Modeling of thermal plasma arc technology FY 1994 report

    International Nuclear Information System (INIS)

    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

  10. Plasma-arc reactor for production possibility of powdered nano-size materials

    International Nuclear Information System (INIS)

    Nano-size materials of various chemical compositions find increasing application in life nowadays due to some of their unique properties. Plasma technologies are widely used in the production of a range of powdered nano-size materials (metals, alloys, oxides, nitrides, carbides, borides, carbonitrides, etc.), that have relatively high melting temperatures. Until recently, the so-called RF-plasma generated in induction plasma torches was most frequently applied. The subject of this paper is the developments of a new type of plasma-arc reactor, operated with transferred arc system for production of disperse nano-size materials. The new characteristics of the PLASMALAB reactor are the method of feeding the charge, plasma arc control and anode design. The disperse charge is fed by a charge feeding system operating on gravity principle through a hollow cathode of an arc plasma torch situated along the axis of a water-cooled wall vertical tubular reactor. The powdered material is brought into the zone of a plasma space generated by the DC rotating transferred plasma arc. The arc is subjected to Auto-Electro-Magnetic Rotation (AEMR) by an inductor serially connected to the anode circuit. The anode is in the form of a water-cooled copper ring. It is mounted concentrically within the cylindrical reactor, with its lower part electrically insulated from it. The electric parameters of the arc in the reactor and the quantity of processed charge are maintained at a level permitting generation of a volumetric plasma discharge. This mode enables one to attain high mean mass temperature while the processed disperse material flows along the reactor axis through the plasma zone where the main physico-chemical processes take place. The product obtained leaves the reactor through the annular anode, from where it enters a cooling chamber for fixing the produced nano-structure. Experiments for AlN synthesis from aluminium power and nitrogen were carried out using the plasma reactor

  11. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Science.gov (United States)

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

    2016-05-01

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

  12. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  13. Partitioning ratio of depleted uranium during a melt decontamination by arc melting

    International Nuclear Information System (INIS)

    In a study of the optimum operational condition for a melting decontamination, the effects of the basicity, slag type and slag composition on the distribution of depleted uranium were investigated for radioactively contaminated metallic wastes of iron-based metals such as stainless steel (SUS 304L) in a direct current graphite arc furnace. Most of the depleted uranium was easily moved into the slag from the radioactive metal waste. The partitioning ratio of the depleted uranium was influenced by the amount of added slag former and the slag basicity. The composition of the slag former used to capture contaminants such as depleted uranium during the melt decontamination process generally consists of silica (SiO2), calcium oxide (CaO) and aluminum oxide (Al2O3). Furthermore, calcium fluoride (CaF2), magnesium oxide (MgO), and ferric oxide (Fe2O3) were added to increase the slag fluidity and oxidative potential. The partitioning ratio of the depleted uranium was increased as the amount of slag former was increased. Up to 97% of the depleted uranium was captured between the ingot phase and the slag phase. The partitioning ratio of the uranium was considerably dependent on the basicity and composition of the slag. The optimum condition for the removal of the depleted uranium was a basicity level of about 1.5. The partitioning ratio of uranium was high, exceeding 5.5x103. The slag formers containing calcium fluoride (CaF2) and a high amount of silica proved to be more effective for a melt decontamination of stainless steel wastes contaminated with depleted uranium

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

    International Nuclear Information System (INIS)

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

  15. Study on treatment of miscellaneous solid waste by plasma melting. Melting characteristics of plasma heating method

    International Nuclear Information System (INIS)

    The melting treatment is of great promise as treatment technology of volume reduction and stabilization for low-level radioactive miscellaneous solid wastes generated from nuclear facilities. Japan Atomic Energy Research Institute (JAERI) has been developing plasma melting method and carrying out melting tests of simulated miscellaneous solid wastes by this method. This paper describes heating characteristic, distribution behavior of radioactive tracer and volatilization behavior of slag component n the plasma melting. Thermal property of waste material had a great influence on heating efficiency of plasma heating. Uniformity of molten products was confirmed by radioactivity measurements. Residual fraction of Cs-137 in solidified product decreased with increasing of heating times. On the contrary, almost all of Eu-152 remained in solidified product. Volatilization of chemical components from molten slag was observed. (author)

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

    Institute of Scientific and Technical Information of China (English)

    LI Tianming; Sooseok CHOI; Takayuki WATANABE

    2012-01-01

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

  17. Dependence of Arc Plasma Dispersion Capability on its Temperature

    Institute of Scientific and Technical Information of China (English)

    CHEN Yun-Yun; SONG Yang; HE An-Zhi; LI Zhen-Hua

    2008-01-01

    @@ The relationship between the dispersion capability and the temperature of argon arc plasma at Iatm is deduced in view of the plasma's refractive index equation.The results indicate that argon arc plasma has a normal dispersion and its dispersion capability is nonlinear to the plasma's temperature in a wide range of temperature and wavelength region.According to the results of numerical calculation, the preferred optical methods are believed to be suitable for the diagnosis of argon arc plasma in different temperature regions.

  18. Mantle Melting as a Function of Water Content beneath the Mariana Arc

    OpenAIRE

    Kelley, Katherine A.; Plank, Terry; Newman, Sally; Stolper, Edward M.; Grove, Timothy L.; Parman, Stephen; Erik H. Hauri

    2010-01-01

    Subduction zone magmas are characterized by high concentrations of pre-eruptive H_2O, presumably as a result of an H_2Oflux originating from the dehydrating, subducting slab. The extent of mantle melting increases as a function of increasing water content beneath back-arc basins and is predicted to increase in a similar manner beneath arc volcanoes. Here, we present new data for olivine-hosted, basaltic melt inclusions from the Mariana arc that reveal pre-eruptive H_2O c...

  19. Characteristics of uranium distribution during the metal melting in an electric arc furnace

    International Nuclear Information System (INIS)

    The distribution of cerium (Ce) and uranium (U) in the ingot, slag and dust phases has been investigated for the effects of the slag type, slag concentration and basicity in a plasma arc melting process. A direct current plasma arc furnace was used to melt contaminated stainless steel and real wastes from the uranium conversion plant in KAERI. The slag former used to remove the contaminants mainly consists of silica (SiO2), calcium oxide (CaO) and aluminum oxide (Al2O3). Calcium fluoride (CaF2), nickel oxide (NiO), and ferric oxide (Fe2O3) were added to provide an increase in the slag fluidity and oxidative potential respectively. The cerium was used as the surrogate of the uranium because the thermochemical and physical properties of the cerium were greatly similar to those of the uranium. The cerium was removed from ingot phase to slag phase by up to 99%. The removal ratio of the cerium was increased with an increase of the amount of the slag former. And maximum removal of the cerium occurred when the slag basicity was 0.82. The natural uranium (UO2) was partitioned from the ingot phase to the slag phase by up to 95%. The distribution of the natural uranium was considerably dependent on the basicity of the slag former and the composition of slag former. The optimum condition for the removal of the uranium was about 1.5 in basicity and 15wt% of slag former. According to the increase of the amount of the slag former, the distribution of uranium oxide linearly increased due to the increase of the capacity to capture uranium oxide within the slag. Through experiments with the various slag former, we verified that the slag formers containing calcium fluoride (CaF2) and high silica were more effective for the melting decontamination of stainless steel wastes contaminated with uranium. In the melting tests with stainless steel wastes from the uranium conversion plant in KAERI, we found that the results of the uranium decontamination were mostly similar to those of the

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

    Science.gov (United States)

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

    2005-03-01

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

  1. Physical and chemical consequences of crustal melting in fossil mature intra-oceanic arcs

    Science.gov (United States)

    Berger, J.; Burg, J.-P.

    2012-04-01

    Seismic velocity models of active intra-oceanic arcs show roots with densities and P-wave velocities intermediate to classical lower oceanic crust (density; ~3.0, Vp: ~7.0 km/s) and uppermost harzburgitic mantle (density: 3.2-3.3, Vp: 7.9-8.0 km/s). Most studies on active and fossil exhumed island arcs interpret the petrological nature of this root as ultramafic cumulates crystallized from primitive melts and/or as pyroxenites formed via basalt-peridotite reactions. Igneous cumulates and pyroxenites have densities close to or above that of uppermost mantle rocks; they can consequently undergo gravity-driven delamination, a process thought to drive the bulk composition of the arc toward an andesitic, continental crust-like composition. Dehydration and melting reactions are reported from exposed arc roots (Jijal complex in Kohistan; Amalaoulaou arc in Mali; Fiordland arc in New-Zealand). Intense influx of mantle-derived basaltic magmas at high pressure in a thickening island arc can enable lower crustal rocks to locally cross the dehydration-melting solidus of hydrous subalkaline basalts. Thermodynamic modeling using Perple_X, geochemical analysis and compilation of experimental and field data have been combined to constrain processes, conditions and consequences of intra-arc melting. The position of the solidus in a P-T grid is strongly dependent of the bulk water content: at 1 GPa, it is as low as 750 °C for water saturated hornblende-gabbros (>1 wt% H2O) and 830°C for gabbros with 0.1 wt% H2O. Incipient melting (F <10 %) near the solidus produces trondhjemitic melt and garnet granulites residue. The latter has composition very close to that of igneous precursors but is characterized by contrasted physical properties (density: 3.2-3.3, Vp: 6.9-7.4 km/s). Higher partial melting degrees (F: 10-20 %) lead to the formation of anorthositic melts in equilibrium with garnet-clinopyroxene-rutile residues (density: up to 3.45, Vp: up to 7.7 km/s). These melts are rich in

  2. Experimental Investigation of Energy Balance in Plasma Arc Cutting Process

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Tossens, S.; Mašláni, Alan; Konrád, Miloš; Pauser, G.; Stehrer, T.

    Santiago : The Pontificia Universidad Católica de Chile, 2010. s. 41-41. ISBN N. [Fifteenth International Congress on Plasma Physics (ICPP2010) and Thirteenth American Workshop on Plasma Physics (LAWPP). 08.08.2010-13.08.2010, Santiago] Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma arc cutting * energy balance Subject RIV: BL - Plasma and Gas Discharge Physics

  3. Spectral characteristics of arc plasma during laser-arc double-sided welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Kezhao Zhang; Zhenglong Lei; Xianglong Wang; Yanbin Chen; Yaobang Zhao

    2015-01-01

    In laser-arc double-sided welding,the spectral characteristics of the arc plasma are calculated and analyzed by spectroscopic diagnosis.The results show that,compared with conventional tungsten inert gas (TIG) welding,the introduction of a laser changes the physical characteristics of the arc plasma regardless of whether laser plasma penetration takes place,and that the influence of the laser mainly affects the near-anode region of the arc.When the laser power is relatively low,the arc column tends to compress,and the arc spectral characteristics show no significant difference.When the arc root constricts,compared with pure TIG arc,the electron density increases by ~2.7 times and the electron temperature decreases by ~3000 K.When the arc column expands,the intensities of spectral lines of both the metal and Ar atoms are the strongest.But it is also observed that the electron density reduces,whereas there is no obvious decrease of electron temperature.

  4. NTWV-based sensing keyhole dimension in plasma arc welding

    Institute of Scientific and Technical Information of China (English)

    Jia Chuanbao; Wu Chuansong; Zhang Yuming

    2008-01-01

    During stable keyhole plasma arc welding, the pilot arc and the transferred arc exist at the meantime, and the arcs can be considered as a composition of two parts inside and outside the nozzle, respectively. Under the mechanical constriction and thermal contraction effects, the inside arc has certain arc length, electron density and arc profile etc. Inducing constant tungsten-to-nozzle voltage. However, the arc outside the nozzle diverges at about 5 degrees and has certain characteristics similar to the free arcs. The nozzle-to-workpiece voltage (NTWV) depends mainly on the length of the arc, which gets bigger as increasing of the weld penetration and keyhole size. The NTWV sensor is developed for monitoring NTWV in real time. The welding experiments are designed to get different penetrations and keyhole sizes. It is found that as the weld penetration and the keyhole size increase, NTWV also increases linearly. The NTWV signals can be used as the feedback variable in automatic control of keyhole plasma arc welding.

  5. Thorium isotope evidence for melting of the mafic oceanic crust beneath the Izu arc

    Science.gov (United States)

    Freymuth, Heye; Ivko, Ben; Gill, James B.; Tamura, Yoshihiko; Elliott, Tim

    2016-08-01

    We address the question of whether melting of the mafic oceanic crust occurs beneath ordinary volcanic arcs using constraints from U-Series (238U/232Th, 230Th/232Th and 226Ra/230Th) measurements. Alteration of the top few hundred meters of the mafic crust leads to strong U enrichment. Via decay of 238U to 230Th, this results in elevated (230Th/232Th) (where brackets indicate activity ratios) over time-scales of ∼350 ka. This process leads to the high (230Th/232Th), between 2.6 and 11.0 in the mafic altered oceanic crust (AOC) sampled at ODP Sites 801 and 1149 near the Izu-Bonin-Mariana arc. Th activity ratios in the Izu arc lavas range from (230Th/232Th) = 1.2-2.0. These values are substantially higher than those in bulk sediment subducting at the Izu trench and also extend to higher values than in mid-ocean ridge basalts and the Mariana arc. We show that the range in Th isotope ratios in the Izu arc lavas is consistent with the presence of a slab melt from a mixed source consisting of AOC and subducted sediments with an AOC mass fraction of up to approximately 80 wt.% in the component added to the arc lava source. The oceanic plate subducting at the Izu arc is comparatively cold which therefore indicates that temperatures high enough for fluid-saturated melting of the AOC are commonly achieved beneath volcanic arcs. The high ratio of AOC/sediments of the slab melt component suggested for the Izu arc lavas requires preferential melting of the AOC. This can be achieved when fluid-saturated melting of the slab is triggered by fluids derived from underlying subducted serpentinites. Dehydration of serpentinites and migration of the fluid into the overlying crust causes melting to start within the AOC. The absence of a significant sediment melt component suggests there was insufficient water to flux both AOC and overlying sediments.

  6. Design and commissioning of a continuous transferred arc plasma melter for the vitrification of nuclear waste

    International Nuclear Information System (INIS)

    A 40-kW transferred arc plasma melter has been designed and constructed to test the potential of this type of system for the vitrification of high level nuclear waste. Present technology relies on joule or induction heaters which are limited in operating temperature and are characterized by large liquid holdup and long residence times. The use of a plasma melter allows the production of higher melting glasses and glass ceramics which are more durable and leach resistant in underground storage. The use of a plasma greatly decreases residence times in the heater and may even reduce the loss of volatiles by control of the melting atmosphere and continuous removal of the product as a solid ingot. Standard borosilicate glass has been melted with continuous withdrawal of product in a series of commissioning runs

  7. Fluctuation Phenomenon Analysis of an Arc Plasma Spraying Jet

    Institute of Scientific and Technical Information of China (English)

    赵文华; 田阔; 刘笛; 张冠忠

    2001-01-01

    The effects of three factors, including the power supply, the arc behaviour in the arc channel and the fluid dynamic process of the jet, on a plasma spraying jet have been experimentally detected by means of spectroscopic diagnostic techniques. The fast Fourier transform method has been applied to the analysis of the arc voltage and spectral line intensity of the jet. The three factors have been studied and distinguished from each other.

  8. Plasma and solar array arcing caused by space debris impact

    OpenAIRE

    Fukushige, Shinya; Akahoshi, Yasuhiro; Watanabe, Keiko; Nagasaki, Toshikazu; Sugawara, Kensho; Kora, Takao; 福重 進也; 赤星 保浩; 渡辺 圭子; 長崎 俊和; 菅原 賢尚; 高良 隆男; Cho, Mengu

    2008-01-01

    There is high possibility that space debris impacts to a solar array paddle in spacecraft parts, because the solar array paddle has large area. Space debris impact to the solar array causes not only mechanical damage but also electrical damage such as arcing on the solar array through local high density plasma created by hypervelocity impact. In the worst case, Joule heating of this arcing carbonizes insulation layer and permanent short-circuit path is created. This is permanent sustained arc...

  9. Arc generation from sputtering plasma-dielectric inclusion interactions

    International Nuclear Information System (INIS)

    Arcing during sputter deposition and etching is a significant cause of particle defect generation during device fabrication. In this article we report on the effect of aluminum oxide inclusion size, shape, and orientation on the propensity for arcing during sputtering of aluminum targets. The size, shape, and orientation of a dielectric inclusion plays a major role in determining the propensity for arcing and macroparticle emission. In previous studies we found that there is a critical inclusion size required for arcing to occur. In this article we used high-speed videos, electric arc detection, and measurements of particle defect density on wafers to study the effect of Al2O3 inclusion size, shape, and orientation on arc rate, intensity, and silicon wafer particle defect density. We found that the cross-sectional area of the inclusion exposed to the sputtering plasma is the critical parameter that determines the arc rate and rate of macroparticle emission. Analysis of the arc rate, particle defect density, and the intensity of the optical emission from the arcing plasma indicates that the critical aluminum oxide inclusion area for arcing is 0.22±0.1 mm2 when the sputtering plasma sheath dark-space λd, is 0.51 mm. Inclusions with areas greater than this critical value readily induce arcing and macroparticle ejection during sputtering. Inclusions below this critical size do not cause arcing or macroparticle ejection. When the inclusion major axis is longer than 2λd and lies perpendicular to the sputter erosion track tangent, the arcing activity increases significantly over the case where the inclusion major axis lies parallel to the erosion track tangent

  10. Variable-Polarity Plasma Arc Welding Of Alloy 2219

    Science.gov (United States)

    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.

  11. A plasma-arc pyrolysis system for hazardous waste treatment

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ A laboratory system for the treatment of medical and hazardous wastes via AC plasma-arc pyrolysis was recently built up by a research team led by Prof. SHENG Hongzhi at the CAS Institute of Mechanics (IMECH) in Beijing.

  12. Method for defect free keyhole plasma arc welding

    Science.gov (United States)

    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.

  13. Modeling of an argon cascaded arc plasma by ANSYS FLUENT

    International Nuclear Information System (INIS)

    In this work, an argon cascaded arc plasma is simulated by the business software ANSYS FLUENT. In fact, thus plasma is a high temperature arc (plasma window) with an average temperature of 12000 °C, which can be used as a medium between high pressure and vacuum mainly due to its characteristics of high temperature. According to the simulating results, the temperature can reach as high as 11500 °C which is in great agreement with that of other reports about plasma window.

  14. Synthesis of 2D materials in arc plasmas

    International Nuclear Information System (INIS)

    In this article we review recent efforts focused on synthesis of two-dimensional (2D) materials in an arc-plasma based process with particular focus on graphene. We present state-of-the-art experimental data on various attempts to employ the arc plasma technique for the graphene synthesis and consider growth mechanisms including precipitation, surface-catalyzed processes and a substrate-independent approach. The potential of arc synthesis for the growth of other types of 2D materials and future prospects are discussed. (review article)

  15. Kinetic Modeling of Plasma Methane Conversion Using Gliding Arc

    Institute of Scientific and Technical Information of China (English)

    Antonius Indarto; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

    2005-01-01

    Plasma methane (CH4) conversion in gliding arc discharge was examined. The result data of experiments regarding the performance of gliding arc discharge were presented in this paper. A simulation which is consisted some chemical kinetic mechanisms has been provided to analyze and describe the plasma process. The effect of total gas flow rate and input frequency refers to power consumption have been studied to evaluate the performance of gliding arc plasma system and the reaction mechanism of decomposition.Experiment results indicated that the maximum conversion of CH4 reached 50% at the total gas flow rate of 1 L/min. The plasma reaction was occurred at the atmospheric pressure and the main products were C (solid), hydrogen, and acetylene (C2H2). The plasma reaction of methane conversion was exothermic reaction which increased the product stream temperature around 30-50 ℃.

  16. An interchangeable-cathode vacuum arc plasma source

    International Nuclear Information System (INIS)

    A simplified vacuum arc design [based on metal vapor vacuum arc (MeVVA) concepts] is employed as a plasma source for a study of a 7Be 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 1012 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.

  17. Identification and characterization of volatile species produced by plasma arc vitrification of mixed waste surrogates

    International Nuclear Information System (INIS)

    Plasma arc vitrification testing was performed at Mississippi State University during Spring 1995 on mixed hazardous waste surrogates for the purpose of testing refractory materials. Because of the interest in partitioning of toxic and/or radioactive species between the melt and the gas phase, emission spectroscopy studies were performed to identify and characterize the volatile species present inside the primary thermal treatment chamber during plasma arc vitrification. The tests were conducted using a Plasma Energy Corporation PT-150 torch, operating in the transferred mode on air. The surrogate material was melted in a batch mode operation inside graphite crucibles. The torch was operated at an average power of 100 kW with an average air flow rate of 0.5 L/sec. The crucible was installed with four optical ports. One was used for a television camera to provide real-time images of the melt and two were used for emission spectroscopy as reported here and for two-color pyrometry. The last port was installed with a feed tube with a dual valve interlock system for dropping surrogate material into the crucible during testing. Results show that the plasma torch melted surrogate waste exhibits an emission spectra rich in gas phase atomic and diatomic species superimposed on a blackbody continuum. Rapid changes in intensities and spectral features alternated with relatively long periods of relatively stable spectra. Emission lines were positively identifies for Al, C, Ca, Ca+, Cu, Cr, Cs, Fe, K, Li, N, Na, O, Rb, and Si. Tentatively identified were Ni, Mn, and Ti. Intermittent spectral features have been tentatively identifies as N2, Cd, and Pb. From this study it appears that emission spectroscopy would be of use in monitoring the gas phase emissions above a plasma torch melt process

  18. Magneto-plasma-dynamic arc thruster

    Science.gov (United States)

    Burkhart, J. A. (Inventor)

    1973-01-01

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

  19. Radiation Transfer in SF6 and PTFE Arc Plasmas

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír; Bartlová, M.; de Hesselle, M.

    Brno : FEI VUT Brno, 2001, s. 12-17. ISBN 80-214-1600-9. [IVth Symposium on Physics of Switching Arc. Brno (CZ), 10.09.2001-14.09.2001] Grant ostatní: ÚT AV ČR(XC) PP52015 Keywords : plasma * radiation * SF6 +PTFE Subject RIV: BL - Plasma and Gas Discharge Physics

  20. Experimental study of anode processes in plasma arc cutting

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Chumak, Oleksiy; Šonský, Jiří; Heinrich, M.; Stehrer, T.; Pauser, H.

    2013-01-01

    Roč. 46, č. 6 (2013), 065202-065202. ISSN 0022-3727 R&D Projects: GA ČR GAP205/11/2070 Institutional support: RVO:61389021 ; RVO:61388998 Keywords : Arc cutting * anode attachment * pilot arc * steam plasma cutting * torch * fluctuations * JET Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (UT-L) Impact factor: 2.521, year: 2013 http://iopscience.iop.org/0022-3727/46/6/065202/pdf/0022-3727_46_6_065202.pdf

  1. Arc Plasma Gun With Coaxial Powder Feed

    Science.gov (United States)

    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.

  2. A highly reliable trigger for vacuum ARC plasma source

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  3. A unified model of transport phenomena in gas metal arc welding including electrode, arc plasma and molten pool

    International Nuclear Information System (INIS)

    This paper presents a theoretical model for describing globular transfer in gas metal arc welding. The heat and mass transfer in the electrode, arc plasma and molten pool are considered in one unified model. Using the volume of fluid method, the transport phenomena are dynamically studied in the following processes: droplet formation and detachment, droplet flight in arc plasma, impingement of droplets on the molten pool and solidification after the arc extinguishes. The simulation of heat and mass transfer in the arc plasma considers the developing surface profile of the electrode and molten pool and also the effect of the flying droplet inside the arc plasma. Furthermore, the heat inputs to the electrode and the molten pool result from the simulation of the arc plasma. In addition, a He-Ne laser in conjunction with the shadow-graphing technique is used to observe the metal-transfer process. The theoretical predictions and experimental results are shown to be in good agreement

  4. Plasma melting treatment method of radioactive solid waste and plasma melting facility for use in the method

    International Nuclear Information System (INIS)

    Radioactive solid wastes are preheated at 250degC or higher and at a temperature less than the boiling point of cesium (760degC), preferably from 300 to 400degC before plasma-melting treatment, and then plasma heat-melting treatment is applied. With such procedures, chlorine contained in vinyl chloride in the radioactive solid wastes can be removed as a gas ingredient. Accordingly, even if the plasma melting treatment is conducted without classification of the radioactive solid wastes, chlorine is not generated during the processing to reliably prevent the reaction of cesium oxide captured in a slug layer and chlorine thereby enabling to improve a capturing rate of cesium. In addition, since the facility for the plasma melting treatment comprises an exhaustion means for removing generated gases, the removing of chlorine by preheating and plasma melting treatment can be conducted successively. (T.M.) conducted successively. (T.M.)

  5. Development of Analysis Program for SF6 Arc Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong C; Ahn, Heui Sub; Choi, Jong Ung; Kim, Young Geun; Oh, Il Sung [Electrotechnology R and D Center, LG Industrial System (Korea)

    2002-07-01

    Because there is a strong interaction between the arc discharge and their surroundings, it is not easy to predict the characteristics of industrial arc plasma systems such as gas circuit breakers. The design procedure of these systems is still largely based on trial and error, although the situation is rapidly improving because of the available computational power at a cost in which is still coming down. The desire to predict the behavior of arc plasma systems, thus optimizing and reducing the development cost, has been the motivation of these arc researches. In this paper, we have simulated the switching operation of a gas circuit breaker during high current area using a computational fluid dynamics considered the electric field analysis, the radiation model and effects of turbulence. (author). 3 refs., 8 figs., 1 tab.

  6. Simple filtered repetitively pulsed vacuum arc plasma source

    International Nuclear Information System (INIS)

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

  7. Gas Contamination In Plasma-Arc-Welded Aluminum

    Science.gov (United States)

    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.

  8. Utilization of steel melting electric arc furnace slag for development of vitreous ceramic tiles

    Indian Academy of Sciences (India)

    Ritwik Sarkar; Nar Singh; Swapan Kumar Das

    2010-06-01

    Steel melting through electric arc furnace route is gaining popularity due to its many advantages, but generates a new waste, electric arc furnace slag, which is getting accumulated and land/mine filling and road construction are the only utilization. This slag has been tried to be value added and utilized to develop vitreous ceramic tiles. Slag, to the extent of 30–40 wt% with other conventional raw materials, were used for the development in the temperature range 1100–1150°C. The fired products showed relatively higher density with shorter firing range and good strength properties. Microstructural and EDAX studies were also done to evaluate the developed products.

  9. Erosion of melt layers developed during a plasma disruption

    International Nuclear Information System (INIS)

    Material erosion of plasma-facing components during a tokamak disruption is a serious problem that limits reactor operation and economical reactor lifetime. In particular, metallic low-Z components such as Be will be subjected to severe melting during disruptions and edge localized models (ELMs). Loss of the developed melt layer will critically shorten the lifetime of these components, severely contaminate the plasma, and seriously inhibit successful and reliable operation of the reactor. In this study mechanisms responsible for melt-layer loss during a disruption are modeled and evaluated. Implications of melt-layer loss on the performance of metallic facing components in the reactor environment are discussed

  10. Arc generation from sputtering plasma-dielectric inclusion interactions

    CERN Document Server

    Wickersham, C E J; Fan, J S

    2002-01-01

    Arcing during sputter deposition and etching is a significant cause of particle defect generation during device fabrication. In this article we report on the effect of aluminum oxide inclusion size, shape, and orientation on the propensity for arcing during sputtering of aluminum targets. The size, shape, and orientation of a dielectric inclusion plays a major role in determining the propensity for arcing and macroparticle emission. In previous studies we found that there is a critical inclusion size required for arcing to occur. In this article we used high-speed videos, electric arc detection, and measurements of particle defect density on wafers to study the effect of Al sub 2 O sub 3 inclusion size, shape, and orientation on arc rate, intensity, and silicon wafer particle defect density. We found that the cross-sectional area of the inclusion exposed to the sputtering plasma is the critical parameter that determines the arc rate and rate of macroparticle emission. Analysis of the arc rate, particle defect...

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

    Science.gov (United States)

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

    1972-01-01

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

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

    Science.gov (United States)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm2 at the peak of the pulse.

  13. Shunting arc plasma source for pure carbon ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y. [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2012-02-15

    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{sup 2} at the peak of the pulse.

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

    Science.gov (United States)

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse. PMID:22380206

  15. Spectroscopic measurement of hydrogen contamination in weld arc plasmas

    Science.gov (United States)

    Shea, J. E.; Gardner, C. S.

    1983-09-01

    The introduction of hydrogen into metals during welding is known to cause hydrogen assisted cracking and embrittlement in certain situations. It has been shown that the weld metal hydrogen content is directly related to hydrogen concentration in the weld arc plasma. In this paper we describe a simple spectroscopic technique for measuring the arc plasma hydrogen concentration in real time when an argon shield gas is used. This technique is based on the fact that the intensity ratio of the hydrogen Balmer Alpha emission line at 6563 Å and an argon emission line at 6965 Å was observed to be an approximately linear function of hydrogen concentration in the weld arc plasma. This technique was experimentally verified under a variety of welding conditions for gas metal arc welding and found to have an error of less than 10% when measuring hydrogen concentrations in the arc plasma as low as 0.25% by volume. This method of hydrogen measurement is also applicable when welding with shield gases not containing argon so long as a suitable ratioing line is available.

  16. Spectroscopic measurement of hydrogen contamination in weld arc plasmas

    International Nuclear Information System (INIS)

    The introduction of hydrogen into metals during welding is known to cause hydrogen assisted cracking and embrittlement in certain situations. It has been shown that the weld metal hydrogen content is directly related to hydrogen concentration in the weld arc plasma. In this paper we describe a simple spectroscopic technique for measuring the arc plasma hydrogen concentration in real time when an argon shield gas is used. This technique is based on the fact that the intensity ratio of the hydrogen Balmer Alpha emission line at 6563 A and an argon emission line at 6965 A was observed to be an approximately linear function of hydrogen concentration in the weld arc plasma. This technique was experimentally verified under a variety of welding conditions for gas metal arc welding and found to have an error of less than 10% when measuring hydrogen concentrations in the arc plasma as low as 0.25% by volume. This method of hydrogen measurement is also applicable when welding with shield gases not containing argon so long as a suitable ratioing line is available

  17. Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

    OpenAIRE

    Tsai De-Chang; Chiang Chen-Hsueh

    2015-01-01

    This study primarily involved using a vacuum arc remelting (VAR) process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%). An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processi...

  18. Plasma Processes : Arc root dynamics in high power plasma torches – Evidence of chaotic behavior

    Indian Academy of Sciences (India)

    A K Das

    2000-11-01

    Although plasma torches have been commercially available for about 50 years, areas such as plasma gun design, process efficiency, reproducibility, plasma stability, torch lives etc. have remained mostly unattended. Recent torch developments have been focusing on the basic understanding of the plasma column and its dynamics inside the plasma torch, the interaction of plasma jet and the powders, the interaction of the plasma jet with surroundings and the impingement of the jet on the substrate. Two of the major causes of erratic and poor performance of a variety of thermal plasma processes are currently identified as the fluctuations arising out of the arc root movement on the electrodes inside the plasma torch and the fluid dynamic instabilities arising out of entrainment of the air into the plasma jet. This paper reviews the current state of understanding of these fluctuations as well as the dynamics of arc root movement in plasma torches. The work done at the author’s laboratory on studying the fluctuations in arc voltage, arc current, acoustic emissions and optical emissions are also presented. These fluctuations are observed to be chaotic and interrelated. Real time monitoring and controlling the arc instabilities through chaos characterization parameters can greatly contribute to the understanding of electrode erosion as well as improvement of plasma torch lifetime.

  19. Arc plasma devices: Evolving mechanical design from numerical simulation

    Indian Academy of Sciences (India)

    S Ghorui; A K Das

    2013-04-01

    Wide ranges of technological applications involve arc plasma devices as the primary plasma source for processing work. Recent findings exhibit the existence of appreciable thermal non-equilibrium in these so-called thermal plasma devices. Commercially available magnetohydrodynamic codes are not capable of handling such systems due to unavailability of non-equilibrium thermodynamic and transport property data and self-consistent models. A recipe for obtaining mechanical design of arc plasma devices from numerical simulation incorporating two-temperature thermal non-equilibrium model is presented in this article with reference to the plasma of the mixture of molecular gases like nitrogen and oxygen. Such systems are technologically important as they correspond to the plasma devices operating with air, oxygen plasma torches in cutting industries and plasma devices using nitrogen as shielding gas. Temperature field, associated fluid dynamics and electrical characteristics of a plasma torch are computed in a systematic manner to evaluate the performance of a conceived design using a two-fluid CFD model coupled with a two-temperature thermodynamic and transport property code. Important effects of different nozzle designs and plasma gases obtained from the formalism are discussed. Non-equilibrium thermo-dynamic properties are computed using modified two-temperature Saha equations and transport properties are computed using standard Chapman–Enskog approach.

  20. Hydrogen-isotope separation in dc-arc plasma

    International Nuclear Information System (INIS)

    In an arc plasma (230 A) burning in an atmosphere of air and argon a vapor-probe mixture of D2O and H2O was introduced. Samples were taken with a Calprobe water-cooled probe from the plasma gas at the same axial position in the arc column, but at different radial distances. The results of mass-spectrometric analyses are presented in two groups: for the samples taken from arc regions having temperatures above 5900 K and for those taken below 3800 K. An isotope separation factor is found between these regions of higher and lower temperature: (D : H) (high temp.) : (D : H) (low temp.) =1.67 +- 12%

  1. Radiation in SF6 + PTFE Arc Plasmas

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír; Bartlová, M.

    Liverpool : University of Liverpool, 2002, s. 47-50. ISBN 0-9539105-1-2. [International Conference on Gas Discharges and their Applications GD 2002 /14./. Liverpool (GB), 02.09.2002-06.09.2002] Institutional research plan: CEZ:AV0Z2076919 Keywords : plasma * radiation * SF6 Subject RIV: BL - Plasma and Gas Discharge Physics

  2. A contribution to the study of arc melting in inert gas atmospheres of zirconium sponge

    International Nuclear Information System (INIS)

    Mettalic zirconium is a material of great interest in the nuclear industry due to its low thermal neutron cross section, high strength and corrosion resistance. The latter permits its use in the chemical industry. In this study, a critical bibliographic revision of the industrial processes used for the melting and consolidation of zirconium sponge has been carried out. A procedure for the melting of zirconium on a laboratory scale, has been established. An nonconsumable-electrode arc furnace have been used. The effect of process variables like atmosphere, melting current and getter, have been showed. The influence of sponge characteristics on the qualities of cast zirconium buttons have been studied. The present study is a contribution towards future investigations to obtain high purity cast zirconium and its alloys commercially known as zircaloy. (author)

  3. DC Arc Plasma Disposal of Printed Circuit Board

    Institute of Scientific and Technical Information of China (English)

    黄建军; 施嘉标; 孟月东; 刘正之

    2004-01-01

    A new solid waste disposal technology setup with DC arc plasma is presented. Being different from conventional combustion or burning such as incineration, it is based on a process called controlled high-temperature pyrolysis, the thermal destruction and recovery process. The results of vitrification of the circuit board is presented. The properties of vitrified product including hardness and leaching test results are presented. The final product (vitrified material) and air emission from the plasma treatment is environmentally acceptable.

  4. DC arc plasma disposal of printed circuit board

    International Nuclear Information System (INIS)

    A new solid waste disposal technology setup with DC arc plasma is presented. Being different from conventional combustion or burning such as incineration, it is based on a process called controlled high-temperature pyrolysis, the thermal destruction and recovery process. The results of vitrification of the circuit board are presented. The properties of vitrified product including hardness and leaching test results are presented. The final product (vitrified material) and air emission from the plasma treatment is environmentally acceptable. (authors)

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

    International Nuclear Information System (INIS)

    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

  6. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    International Nuclear Information System (INIS)

    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.

  8. A New Waste Disposal Technology-plasma arc Pyrolysis System

    Institute of Scientific and Technical Information of China (English)

    黄建军; 施嘉标; 梁荣庆; 刘正之

    2003-01-01

    This paper introduces a new waste disposal technology with plasma arc. Being different from conventional combustion or burning such as incineration, it is based on a process called controlled pyrolysis-thermal destruction and recovery process. It has four advantages, they are completely safe, clean, high-energy synthesis gas, non-toxic vitrified slag and metal.

  9. Fluid Flow Modeling of Arc Plasma and Bath Circulation in DC Electric Arc Furnace

    Institute of Scientific and Technical Information of China (English)

    WANG Feng-hua; JIN Zhi-jian; ZHU Zi-shu

    2006-01-01

    A mathematical model describing the flow field, heat transfer and the electromagnetic phenomenon in a DC electric arc furnace has been developed. First the governing equations in the arc plasma region are solved and the calculated results of heat transfer, current density and shear stresses on the anode surface are used as boundary conditions in a model of molten bath. Then a two-dimensional time-dependent model is used to describe the flow field and electromagnetic phenomenon in the molten bath. Moreover, the effect of bottom electrode diameter on the circulation of molten bath is studied.

  10. Effect of microwave oxygen plasma on melting glass

    International Nuclear Information System (INIS)

    In this study, some basic experiments have been carried out to investigate the effect of oxygen plasma irradiation on the melting glass, namely the oxygen dissolution and the change of chlorine concentration in glass. By the oxygen plasma irradiation, the chlorine concentration in glass decreases without depending on glass composition. By the plasma irradiation, the relative weight gain of glass is observed and it can be caused by dissolution of a large amount of oxygen into the melting glass. The amount of dissolved oxygen by plasma irradiation is about two orders larger than one estimated by using model supposed that oxygen molecules dissolve into glass melt. Then, it can be suggested that the oxygen dissolves by the specific mechanism due to plasma irradiation. (author)

  11. Effect of microwave oxygen plasma on melting glass

    Energy Technology Data Exchange (ETDEWEB)

    Ohsugi, Takeshi [Tokyo Inst. of Technology, Dept. of Nuclear Engineering, Tokyo (Japan); Kusumo, Sutowo; Suzuki, Masaaki [Tokyo Inst. of Technology, Dept. of Chemical Engineering, Tokyo (Japan); Kobayashi, Hiroaki [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works

    2002-05-01

    In this study, some basic experiments have been carried out to investigate the effect of oxygen plasma irradiation on the melting glass, namely the oxygen dissolution and the change of chlorine concentration in glass. By the oxygen plasma irradiation, the chlorine concentration in glass decreases without depending on glass composition. By the plasma irradiation, the relative weight gain of glass is observed and it can be caused by dissolution of a large amount of oxygen into the melting glass. The amount of dissolved oxygen by plasma irradiation is about two orders larger than one estimated by using model supposed that oxygen molecules dissolve into glass melt. Then, it can be suggested that the oxygen dissolves by the specific mechanism due to plasma irradiation. (author)

  12. Wide-angle seismic reflections as direct indictors of partial melt beneath an andesite arc

    Science.gov (United States)

    Stern, T. A.; Benson, A.; Stratford, W. R.; Gamble, J. A.

    2011-12-01

    Quasi-linear arcs of andesite volcanoes that erupt above 120 ± 40 km deep Waditi-Benioff zones are one of the most striking surface manifestations of plate tectonics. The prevailing view is that andesite magma that feed these arcs are an end-product of fluid-assisted melting in the mantle wedge1. Two key questions remain unresolved: why is the line of an active arc so sharply defined? and where do parental mantle-derived melts pool and differentiate into mafic restite and more felsic magma components that are so distinctive of continental magmatic arc systems ? Here we present seismic evidence from the MORC (mantle or crust?) project for a focused zone of melt below the andesite arc within northern New Zealand. Nine ~ 0.4 - 1.3 tonne dynamite shots were recorded on ~ 700 seismographs spaced along a 120 km long array across, and normal to the axis of the Taupo Volcanic Zone (TVZ). Two important features of the ray tracing solution are: (i) a lower-crustal, 10 km thick, "rift-pillow" of rocks where the P-wave seismic velocities (Vp) are ~ 6.8-7.1 km/s. Seismic reflections from top and bottom of the pillow are termed R1 and R2 respectively. (ii) Strong seismic reflections (termed R3 reflector) are recorded from a relatively short (12 -18 km-long) reflector at a depth of ~ 32 ± 2 km. An analysis of interval velocities between the R2 and R3 reflectors show a P-wave speed of 7.6 +/- 0.2 km/s, which is interpreted as anomalous upper mantle. Thus R3 is regarded as being a reflector within the upper mantle. Ray-tracing locates R3 beneath the eastern margin of the TVZ and directly beneath the active volcanic (andesite) front and geothermal fields. A causal relationship between the R3 reflector and the andesite arc is therefore implied. The amplitude ratio of the R3/R2 reflections along common traces is as high as 4-6 for incidence angles of reflection of 45-60 degrees. These data suggest R3 is best explained with numerical methods by an interface across which there is a

  13. Absorption characteristic of arc plasma in the infrared region

    Institute of Scientific and Technical Information of China (English)

    Chen Yun-Yun; Song Yang; Li Zhen-Hua; He An-Zhi

    2011-01-01

    In this paper, argon arc plasma is chosen as an example to study the absorption characteristics of arc plasma in the infrared region. Firstly, the phase and the attenuation constants are deduced for the given temperature, pressure and probe wavelength regions. Based on those constants, the dependence of the attenuation constant on the temperature and pressure in the vicinity of a certain probe wavelength is found. Then, theoretical analysis and discussion are conducted. Maximal absorption occurs at the position where the contributions of neutral particles and electrons come to a balance in a physical point of view, which may provide some measures to take for decreasing or controlling the plasma absorption of electromagnetic waves.

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Directory of Open Access Journals (Sweden)

    I. A. Ivanou

    2015-01-01

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

  16. Numerical and experimental study of heat transfers in an arc plasma. Application to TIG arc welding

    International Nuclear Information System (INIS)

    The arc welding is used for many industrial applications, especially GTA welding. Given the excellent quality of the produced welds, GTA welding is used for the majority of the interventions (repairs, joined sealing) on the French nuclear park. This work is part of a project carried out by EDF R and D which aims to simulate the whole process and builds a tool able to predict the welds quality. In this study, we focus on the development of a predictive model of the exchanged heat flux at the arc - work piece interface, responsible of the work piece fusion. The modeling of the arc plasma using the electric module of the hydrodynamics software Code Saturne R developed by EDF R and D is required. Two types of experimental tests are jointly carried out to validate this numerical model: i) on density and temperature measurements of plasma by atomic emission spectroscopy and ii) on the evaluation of the heat transfers on the work piece surface. This work also aims at demonstrate that the usual method of using an equivalent thermal source to model the welding process, can be replaced by our plasma model, without the numerous trials inherent to the usual method. (author)

  17. Experimental determination of the weld penetration evolution in keyhole plasma arc welding

    Institute of Scientific and Technical Information of China (English)

    Hu Qingxian; Wu Chuansong; Zhang Yuming

    2007-01-01

    Keyhole plasma arc welding experiments are conducted to measure the weld geometry and penetration at different moments during the initial phase from igniting arc to quasi-steady state. Indirect information on keyhole formation and evolution in plasma arc welding can be extracted based on the weld macrophotograph at cross section. It has laid foundation to verify the mathematical models of keyhole plasma arc welding.

  18. Using of Plasma Torch with Gerdien Arc for Plastic Treatment

    Czech Academy of Sciences Publication Activity Database

    Hlína, Michal; Kavka, Tetyana; Konrád, Miloš; Hrabovský, Milan; Kopecký, Vladimír

    Bratislava,: Department of Experimental Physics, Faculty of Mathematics,, 2011 - (Országh, J.; Papp, P.; Matejčík, Š.), s. 129-132. (SAPP. SAPP XVIII). ISBN 978-80-89186-77-8. [Symposium on Application of Plasma Processes Workshop on Plasmas as a Planetary Atmosphere Mimics/18./. Vrátna dolina (SK), 15.01.2011-20.01.2011] R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma * gasification * plastics * DC plasma torch * Gerdien arc Subject RIV: BL - Plasma and Gas Discharge Physics http://neon.dpp.fmph.uniba.sk/sapp/download/Book_of_Contributed_Papers_SAPP_XVIII.pdf

  19. Vacuum-arc plasma centrifuge applied to stable isotope separation

    International Nuclear Information System (INIS)

    This work describes the results of a vacuum-arc plasma centrifuge experiment. A plasma centrifuge is an apparatus where a plasma column is produced due to the interaction of an electric current with an externally applied magnetic field, sup(→)J x sup(→)B. Among the applications of a rotating plasma, this work deals particularly with its utilization in an isotope enrichment device. The main characteristics of the plasma produced in this experiment are presented, with special attention to the plasma column rotation and the isotope enrichment. The analysis of the results is performed using a fluid model for a completely ionized rigid body rotating plasma column in steady state equilibrium. The main results are: a) rotation frequency of the plasma column in the range 2 x 10 sup(4) to 3 x 10 sup(5) rad/s; b) enrichment of 10 to 30% for the magnesium isotopes, and of 290 to 490% for the carbon 13 isotope; c) rigid body rotation of the plasma column only for radii smaller than the characteristic radius of the plasma column. re; d) linear dependence of the rotation frequency upon the magnetic field strength only for r < re; e) existence of an optimum value of the magnetic field for maximum enrichment; and f) dependence of the rotation frequency upon the inverse of the atomic mass. (author)

  20. Simulation of the Effects of Several Factors on Arc Plasma Behavior in Low Voltage Circuit Breaker

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Taking into account the properties of the arc plasma and the electromagnetic, heat and radiative phenomena, commercial computational fluid dynamics software PHOENICS has been adapted and modified to develop the three-dimensional magneto-hydrodynamic (MHD)model of arc in a low voltage circuit breaker. The effects of the arc ignition location, venting size and gassing material on arc behavior have been investigated. The analysis of the results show that the arc velocity accelerates with the increase in the distance between arc ignition location and of the venting size, and the existence of the gassing material is beneficial to improving the arc voltage and reducing the arc temperature.

  1. Multigroup Approximation of Radiation Transfer in SF6 Arc Plasmas

    Directory of Open Access Journals (Sweden)

    Milada Bartlova

    2013-01-01

    Full Text Available The first order of the method of spherical harmonics (P1-approximation has been used to evaluate the radiation properties of arc plasmas of various mixtures of SF6 and PTFE ((C2F4n, polytetrafluoroethylene in the temperature range (1000 ÷ 35 000 K and pressures from 0.5 to 5 MPa. Calculations have been performed for isothermal cylindrical plasma of various radii (0.01 ÷ 10 cm. The frequency dependence of the absorption coefficients has been handled using the Planck and Rosseland averaging methods for several frequency intervals. Results obtained using various means calculated for different choices of frequency intervals are discussed.

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

    Science.gov (United States)

    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)

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

    International Nuclear Information System (INIS)

    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.

  4. Characteristics of Single Cathode Cascaded Bias Voltage Arc Plasma

    Science.gov (United States)

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

    2016-06-01

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

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

    International Nuclear Information System (INIS)

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

  6. Development of a plasma-arc-cutting technology like a mechanical saw for dismantling nuclear components of greater thickness under water

    International Nuclear Information System (INIS)

    1. Status of research: Cutting steel with the plasma-arc-saw (saw disk diameter 600 mm) with a thickness up to 100 mm is possible. The cutting process works discontinuously. For the ignition of the special constructed plasma torches it is necessary to stop the rotation of the saw disk so the cutting process works discontinuously. 2. Aim of research work: Plasma arc cutting technology should be developed to enable cutting component parts continuous and computer aided. 3. Method of research: Cutting results of the plasma-arc-saw (saw disk diameter 600 mm) gives design data for the construction of a plasma arc saw with a diameter of 850 mm and a diameter of 1000 mm. To develop and optimize the special nozzles of the plasma-arc-saw experiments with the submerged combustion burner have been performed. 4. Results: There are no problems of thermal cutting a plate of steel and a heat exchanger up to a thickness of 300 mm. The cuttable sheet thickness only depends on the diameter of the saw blade. The emission of dust and aerosol only depends on the melted material. Computer aided cutting is possible. 5. The plasma-arc-saw enables thermal cutting of component parts independent of their thickness in a water depth of 20 m without requiring a force. The remote control dismantling of a reactor vessel and other components with greater wall thickness is possible. (orig.) With 34 refs., 2 tabs., 101 figs

  7. Estimation of dynamic properties of attractors observed in hollow copper electrode atmospheric pressure arc plasma system

    Indian Academy of Sciences (India)

    S Ghorul; S N Sahasrabudhe; P S S Murthy; A K Das; N Venkatramani

    2002-07-01

    Understanding of the basic nature of arc root fluctuation is still one of the unsolved problems in thermal arc plasma physics. It has direct impact on myriads of thermal plasma applications being implemented at present. Recently, chaotic nature of arc root behavior has been reported through the analysis of voltages, acoustic and optical signals which are generated from a hollow copper electrode arc plasma torch. In this paper we present details of computations involved in the estimation process of various dynamic properties and show how they reflect chaotic behavior of arc root in the system.

  8. Effect of Mantle Wedge Hybridization by Sediment Melt on Geochemistry of Arc Magma and Arc Mantle Source - Insights from Laboratory Experiments at High Pressures and Temperatures

    Science.gov (United States)

    Mallik, A.; Dasgupta, R.; Tsuno, K.; Nelson, J. M.

    2015-12-01

    Generation of arc magmas involves metasomatism of the mantle wedge by slab-derived H2O-rich fluids and/or melts and subsequent melting of the modified source. The chemistry of arc magmas and the residual mantle wedge are not only regulated by the chemistry of the slab input, but also by the phase relations of metasomatism or hybridization process in the wedge. The sediment-derived silica-rich fluids and hydrous partial melts create orthopyroxene-rich zones in the mantle wedge, due to reaction of mantle olivine with silica in the fluid/melt [1,2]. Geochemical evidence for such a reaction comes from pyroxenitic lithologies coexisting with peridotite in supra-subduction zones. In this study, we have simulated the partial melting of a parcel of mantle wedge modified by bulk addition of sediment-derived melt with variable H2O contents to investigate the major and trace element chemistry of the magmas and the residues formed by this process. Experiments at 2-3 GPa and 1150-1300 °C were conducted on mixtures of 25% sediment-derived melt and 75% lherzolite, with bulk H2O contents varying from 2 to 6 wt.%. Partial reactive crystallization of the rhyolitic slab-derived melt and partial melting of the mixed source produced a range of melt compositions from ultra-K basanites to basaltic andesites, in equilibrium with an orthopyroxene ± phlogopite ± clinopyroxene ± garnet bearing residue, depending on P and bulk H2O content. Model calculations using partition coefficients (from literature) of trace elements between experimental minerals and silicate melt suggest that the geochemical signatures of the slab-derived melt, such as low Ce/Pb and depletion in Nb and Ta (characteristic slab signatures) are not erased from the resulting melt owing to reactive crystallization. The residual mineral assemblage is also found to be similar to the supra-subduction zone lithologies, such as those found in Dabie Shan (China) and Sanbagawa Belt (Japan). In this presentation, we will also

  9. Processing and transformation of TiAl-base alloys: reactive sintering and classical arc melting

    International Nuclear Information System (INIS)

    This work aims at optimizing processing and transformation of TiAl two-phased alloys using today's powder metallurgy development. It is completed by testing the mechanical behavior of the alloys elaborated at the lab. The first part deals with the different ways of producing these intermetallics: reactive sintering of elemental powders, sintering and extrusion of the pre-alloyed powder or classical arc melting of pure metal. The extrusion optimization of the sintered alloy and the rolling of the TiAl ingot is studied in the second part. The titanium aluminides microstructure is detailed after applying different thermomechanical and heat treatments. The last part of the study devoted to the mechanical properties is supplied by the different statistical analysis methods of the obtained data. (author)

  10. The kinetics of nitrogen dissolution in levitation and arc-melted Fe-C-Mn filler metals

    Directory of Open Access Journals (Sweden)

    A. Gruszczyk

    2008-06-01

    Full Text Available Purpose: The influence of melting method on the kinetics of nitrogen absorption by Fe-C-Mn filler metals has beenanalysed. The industrial heats of the Fe-C-Mn (SpG1 type welding filler metals were selected for own researches.Design/methodology/approach: The research of the nitrogen absorption kinetics was carried out in thelevitation and TIG arc-melting conditions in the Ar+N2 atmosphere. The conditions of experiments were madepossibly close to those existing in a molten metal drop in the welding processes.Findings: Based on the models of nitrogen absorption during levitation and arc melting of Fe-C-Mn filler metals,the time-dependent changes of nitrogen content were determined as well as the mass transfer coefficients b andthe rates of nitrogen absorption. Nitrogen absorption rate decreases along with the increase of oxygen content inthe Fe-C-Mn filler metals arc-melted in the Ar+N2 atmosphere.Research limitations/implications: Investigation of the Fe-C-Mn complex alloys with the specified amountof impurities makes the detailed analysis of the elementary stages of nitrogen dissolution more difficult, yet bringsthe experiment conditions closer to those occurring in the actual welding processes.Practical implications: Recognizing the mechanisms of nitrogen absorption under arc and non-arc melting tomake possible the control of nitrogen level in the welds.Originality/value: Obtained results explain the influence of oxygen and melting conditions on kinetics ofnitrogen dissolution in Fe-C-Mn alloys.

  11. The kinetics of nitrogen dissolution in levitation and arc-melted Fe-C-Mn filler metals

    Directory of Open Access Journals (Sweden)

    A. Gruszczyk

    2008-02-01

    Full Text Available Purpose: The influence of melting method on the kinetics of nitrogen absorption by Fe-C-Mn filler metals has been analysed. The industrial heats of the Fe-C-Mn (SpG1 type welding filler metals were selected for own researches.Design/methodology/approach: The research of the nitrogen absorption kinetics was carried out in the levitation and TIG arc-melting conditions in the Ar+N2 atmosphere. The conditions of experiments were made possibly close to those existing in a molten metal drop in the welding processes.Findings: Based on the models of nitrogen absorption during levitation and arc melting of Fe-C-Mn filler metals, the time-dependent changes of nitrogen content were determined as well as the mass transfer coefficients b and the rates of nitrogen absorption. Nitrogen absorption rate decreases along with the increase of oxygen content in the Fe-C-Mn filler metals arc-melted in the Ar+N2 atmosphere.Research limitations/implications: Investigation of the Fe-C-Mn complex alloys with the specified amount of impurities makes the detailed analysis of the elementary stages of nitrogen dissolution more difficult, yet brings the experiment conditions closer to those occurring in the actual welding processes.Practical implications: Recognizing the mechanisms of nitrogen absorption under arc and non-arc melting to make possible the control of nitrogen level in the welds.Originality/value: Obtained results explain the influence of oxygen and melting conditions on kinetics of nitrogen dissolution in Fe-C-Mn alloys.

  12. Platelet-cooled plasma arc torch. Final report

    International Nuclear Information System (INIS)

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

  13. Superalloy material test in a plasma arc tunnel

    Science.gov (United States)

    Land, D. W.

    1972-01-01

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

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

    Science.gov (United States)

    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.

  15. Power flow and efficiency in supplying systems of arc plasma generators

    International Nuclear Information System (INIS)

    An arc plasma generator requires a supplying system of several hundred kVA and with such operating characteristics as to ignite the discharge at a high voltage of 10 to 20 kV and then to maintain it at a voltage ten times lower. There are many various types of arc plasma generators and they differ considerably from one another depending on their application, construction and kind of discharge used for plasma generation. An arc plasma generator with a gliding arc and the supplying systems are discussed, this mainly from the point of view of power flow and efficiency. (author)

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

    Science.gov (United States)

    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.

  17. Dynamic processes and kinetic theory of plasma fluctuations: ARCS3

    International Nuclear Information System (INIS)

    Dynamic processes on the ARCS3 fight involve six related coordinate systems: Rocket System, Local Geographic System, Local Geomagnetic System, Global Geographic System, Wave Vector System and Artificial Argon Beam System. The present thesis has found the relationships needed to carry out coordinate transformations between all these six coordinate systems. These coordinate transformations are used to investigate ion trajectories and the directional response of the detector OCTO4. A technique to calculate the 3-component acceleration of the main payload was completed, and the trajectory of the main payload relative to the sub payload was given. A method to use the measured spin plane component of the electric field vector to construct the full 3 dimensional electric field vector in the Local Geomagnetic System has been provided. A model to simulate the artificial argon beam distribution is proposed, and used to calculate the beam's flux, density and evolution. Several kinds of plasma waves were observed by the University of Minnesota ACE detector. To explain the wave observations, a kinetic theory of plasma fluctuations was developed. This theory includes magnetized plasma species with or without parallel streaming. It is also valid for plasma including an unmagnetized two temperature plasma species that is streaming in any direction. As an application of the theory, the thermal fluctuations of the O+ acoustic wave mode was calculated and compared with observations. The O+ - He+ bihybrid mode is also evaluated and compared with the observed wave spectra

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

    Science.gov (United States)

    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.

  19. Finite Element Simulation of Plasma Transferred ARC Welding [PTAW] of Structural Steel

    Directory of Open Access Journals (Sweden)

    PV Senthiil

    2014-10-01

    Full Text Available Plasma transferred Arc welding is one of the most widely used welding process, in which the metals are fused just above the melting point, and makes the metal to fuse. It is employed in many applications like tool die and metal casting, strip metal welding etc. This investigation is to analyze temperature distribution residual stress and distortion by varying the heat source parameter in SYSWELD, and compared the results with ANSYS. The simulation of Plasma Transferred Arc welding was of structural steel plate performed using a non-linear transient heat transfer analysis. Heat losses due to convection and variation of material properties with temperature were considered in this analysis. To incorporate the heat developed the Gaussian distribution was considered. Finite element simulations were performed using ANSYS Parametric Design Language (APDL code and using SYSWELD. The temperatures obtained were compared with experimental results for validation. It was found that the predicted values of temperature agree very well with the experimental values. Residual Stress and Distortion were also predicted for various heat Input. The effect of heat input on residual stress and distortion was investigated.

  20. Plasma arc pyrolysis of radioactive ion exchange resin

    International Nuclear Information System (INIS)

    This paper reports on two ion exchange resins (IRN 77 and IRN 78) which were pyrolysed in a plasma-arc furnace. Both continuous and batch tests were performed. Volume reduction ratios of 10 to 1 and 10 to 3.5 were achieved for IRN 78 and IRN 77 respectively. The product of the resin pyrolysis was a char which contained the radioactive elements such as cobalt. The off-gases consisted of mainly hydrogen and carbon monoxide. There was a relatively small amount of dust in the off-gases. At the present time radioactive ion exchange resign is being kept in storage. The volume of this waste is increasing and it is important that the volume be reduce. The volume reduction ratio should be of the order of ten-to-one. Also, it is required that the radioactive elements can be collected or fixed in a form which could easily be disposed of. Plasma arc treatment offers considerable potential for the processing of the waste

  1. Numerical analysis of arc plasma behaviour during contact opening process in low-voltage switching device

    International Nuclear Information System (INIS)

    This paper focuses on the numerical investigation of low-voltage arc plasma behaviour with the contact opening process included. A flexible experimental setup with a rotating contact is designed to support this study. Based on the magnetohydrodynamic arc model, the elongation and the commutation behaviour of the arc plasma during the contact rotation progress are simulated. Under the given conditions of the external magnetic field and the contact rotating velocity, the arc motion is described in detail by the temperature distribution. The stagnation together with the following rapid jump of two arc roots is observed by both calculation and experiment. The rapid rise in the arc voltage is mainly caused by the increasing difference between the two arc roots displacement in the moving direction, and the jump instant of the arc root on the moving contact is according to the moment of the maximal voltage value

  2. Effects of the slag former on the metal melting and radionuclides distribution in an electric arc furnace

    Energy Technology Data Exchange (ETDEWEB)

    Song, Song Pyung; Min, Byung Youn; Choi, Wang Kyu; Chung, Chong Hun; Oh, Won Zin [Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of)

    2005-11-15

    The characteristics of the metal melting and radionuclide distribution of the radioactive has been investigated in a lab-scale arc furnace. The slag former based on the constituents of silica, calcium oxide, aluminum oxide, borate and calcium fluoride additions was used for melting of the stainless and carbon steel. In the melting of the stainless steel, the amount of slag formation increased with an increase of the concentration of the slag former. But the effects of the slag basicity on the amount of slag formation showed a local maximum value of the slag formation with an increase of the basicity index in the melting of the stainless steel as well as in the melting of the carbon steel. With an increase of the amount of slag former addition, the trends of the cobalt distribution into the ingot and the slag depended on the kind of slag former used in the melting of the stainless steel while the effect of the slag basicity on the distribution of the cobalt was not clarified in the melting of carbon steel. In the melting of the carbon steel, the strontium was captured at up to 50% into the slag phase. Cesium was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the dust phase.

  3. Effects of the slag former on the metal melting and radionuclides distribution in an electric arc furnace

    International Nuclear Information System (INIS)

    The characteristics of the metal melting and radionuclide distribution of the radioactive has been investigated in a lab-scale arc furnace. The slag former based on the constituents of silica, calcium oxide, aluminum oxide, borate and calcium fluoride additions was used for melting of the stainless and carbon steel. In the melting of the stainless steel, the amount of slag formation increased with an increase of the concentration of the slag former. But the effects of the slag basicity on the amount of slag formation showed a local maximum value of the slag formation with an increase of the basicity index in the melting of the stainless steel as well as in the melting of the carbon steel. With an increase of the amount of slag former addition, the trends of the cobalt distribution into the ingot and the slag depended on the kind of slag former used in the melting of the stainless steel while the effect of the slag basicity on the distribution of the cobalt was not clarified in the melting of carbon steel. In the melting of the carbon steel, the strontium was captured at up to 50% into the slag phase. Cesium was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the dust phase

  4. Hybrid furnace system for the plasma melting of radioactive waste

    International Nuclear Information System (INIS)

    A hybrid type plasma melting furnace has been designed for vitrification of medium and low level radioactive wastes. Refractory is used the bottom side of the furnace while the upper side consists of water-cooled metal plate. Such configuration takes the advantages of all refractory furnace (easy heating and tapping) and all water-cooled furnace (no additional waste production and reduced carry-over of volatile metals). The system uses two plasma torches - a main torch for the melting of incoming wastes and a subsidiary torch for the slag tapping. The torch will use air for the plasma medium and in order for the reduction of NOx, an appropriate amount of hydrocarbon gas will be supplied to the furnace at the time. A load-lock type feeder will be used together with a conveyer system. A water cooled baffle will be used at the off-gas exit to reduce the amount of carry-over of dust. The configuration and advantage of such hybrid type melting furnace is discussed

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

    Science.gov (United States)

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

    2004-06-01

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

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

    International Nuclear Information System (INIS)

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

  7. Comparison of laser induced plasma and arc discharge emission spectra of Al, Fe, Cu and C

    International Nuclear Information System (INIS)

    Emission spectra of laser induced plasma and arc discharge were measured and compared for Al, Fe, Cu and C. Such a comparison shows a higher presence of ionized transitions, but also a higher background in the emission spectra of laser induced plasma than in arc discharge. It can be concluded that in general it is not possible to predict laser induced plasma for material analysis purposes, calibration by reference laser induced plasma spectra of pure elements in vacuum will be necessary. (Authors)

  8. Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding

    OpenAIRE

    Koray Yurtisik; Suha Tirkes; Igor Dykhno; C. Hakan Gur; Riza Gurbuz

    2013-01-01

    Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex mi...

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

    International Nuclear Information System (INIS)

    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 (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 80-90 eV, which is confirmed by Langmuir electric probe measurements. Density ne of this metal plasma is shown to be in the range 4x1021-6x1021 m-3 and includes multiple ion charge states. The exit velocity of the plasma measured by a pair of Langmuir probes is close to 2.2x106 cm/s and matched well with the arc velocity determined by the B-dot probes and the results from simulation

  10. Prediction of radiative heat transfer in argon arc plasmas using the method of partial characteristics

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír

    Brno : VUT, 2003, s. 13-16 ISBN 80-214-2307-2. [Symposium on Physics of Switching Arc /15./. Brno (CZ), 22.09.2003-26.09.2003] R&D Projects: GA ČR GA102/03/0813 Institutional research plan: CEZ:AV0Z2076919 Keywords : plasma radiation * argon arc Subject RIV: BL - Plasma and Gas Discharge Physics

  11. Plasma plume characterization of a vacuum arc thruster

    Science.gov (United States)

    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

  12. Underwater cladding with laser beam and plasma arc welding

    International Nuclear Information System (INIS)

    Two welding processes, plasma arc (transferred arc) (PTA) and laser beam, were investigated to apply cladding to austenitic stainless steels and Inconel 600. These processes have long been used to apply cladding layers , but the novel feature being reported here is that these cladding layers were applied underwater, with a water pressure equivalent to 24 m (80 ft). Being able to apply the cladding underwater is very important for many applications, including the construction of off-shore oil platforms and the repair of nuclear reactors. In the latter case, being able to weld underwater eliminates the need for draining the reactor and removing the fuel. Welding underwater in reactors presents numerous challenges, but the ability to weld without having to drain the reactor and remove the fuel provides a huge cost savings. Welding underwater in reactors must be done remotely, but because of the radioactive corrosion products and neutron activation of the steels, remote welding would also be required even if the reactor is drained and the fuel removed. In fact, without the shielding of the water, the remote welding required if the reactor is drained might be even more difficult than that required with underwater welds. Furthermore, as shall be shown, the underwater welds that the authors have made were of high quality and exhibit compressive rather than tensile residual stresses

  13. Study of the plasma column in hollow-electrode arc

    International Nuclear Information System (INIS)

    A steady state hollow electrodes arc has been built. The density of the plasma column obtained varies between 1.5 1013 cm-3 and 8.1014 cm-3 when the argon feed rate is varied from 0.2 and 30 l/h S.T.P. and the corresponding values of the electron temperature vary from at least 15 eV to 1 eV. Three diagnostic methods have been utilized: electrostatic probes, far-infrared emission (wavelength between 10 and 0.1 mm) and microwave techniques utilizing either the transmitted or the reflected wave. The results obtained are described in detail and compared. Limits of utilization of the different techniques are given. (authors)

  14. Ion energy distribution and basic characteristics of plasma flows of nonself-sustained arc discharge

    International Nuclear Information System (INIS)

    Experimental results on study of the nonself-sustained arc discharge basic characteristics at currents up to 35 A are presented. The ion energy distributions and dynamics of the directed motion average energy of plasma flow ions are studied. Floating potentials in the plasma flows are measured. Ionization coefficients of the generated plasma flows and their dependence on the discharge current are studied. It is shown that at the discharge currents equal 20...30 A the vacuum arc discharge in anode material vapors can effectively create dropless and highly ionized plasma flows of different metals and provides films deposition rates, which are comparable to possibilities of the cathode vacuum arc discharge

  15. Technological plasma source equipped with combined system of vacuum-arc discharge initiation

    International Nuclear Information System (INIS)

    The construction and the operation principle of erosion plasma source with a three-stage system of vacuum-arc discharge excitation is described. As first two step was used the modified contactless start system with plasma injector, which was widely used in standard plasma sources of the ''Bulat'' systems. The operation principle of the third stage was based on the transition of glow discharge to arc discharge. Coordinated operation of three stages during various stages of coating deposition provided significant increasing of service life and reliability of the system of vacuum-arc discharge initiation and extended the functionality of the plasma source

  16. Nanostructured Bi2Te3 Prepared by a Straightforward Arc-Melting Method

    Science.gov (United States)

    Gharsallah, M.; Serrano-Sánchez, F.; Bermúdez, J.; Nemes, N. M.; Martínez, J. L.; Elhalouani, F.; Alonso, J. A.

    2016-03-01

    Thermoelectric materials constitute an alternative source of sustainable energy, harvested from waste heat. Bi2Te3 is the most utilized thermoelectric alloy. We show that it can be readily prepared in nanostructured form by arc-melting synthesis, yielding mechanically robust pellets of highly oriented polycrystals. This material has been characterized by neutron powder diffraction (NPD), scanning electron microscopy (SEM), and electronic and thermal transport measurements. A microscopic analysis from NPD data demonstrates a near-perfect stoichiometry of Bi2Te3 and a fair amount of anharmonicity of the chemical bonds. The as-grown material presents a metallic behavior, showing a record-low resistivity at 320 K of 2 μΩ m, which is advantageous for its performance as a thermoelectric material. SEM analysis shows a stacking of nanosized sheets, each of them presumably single-crystalline, with large surfaces perpendicular to the c crystallographic axis. This nanostructuration notably affects the thermoelectric properties, involving many surface boundaries that are responsible for large phonon scattering factors, yielding a thermal conductivity as low as 1.2 W m-1 K-1 around room temperature.

  17. Nanostructured Bi2Te3 Prepared by a Straightforward Arc-Melting Method.

    Science.gov (United States)

    Gharsallah, M; Serrano-Sánchez, F; Bermúdez, J; Nemes, N M; Martínez, J L; Elhalouani, F; Alonso, J A

    2016-12-01

    Thermoelectric materials constitute an alternative source of sustainable energy, harvested from waste heat. Bi2Te3 is the most utilized thermoelectric alloy. We show that it can be readily prepared in nanostructured form by arc-melting synthesis, yielding mechanically robust pellets of highly oriented polycrystals. This material has been characterized by neutron powder diffraction (NPD), scanning electron microscopy (SEM), and electronic and thermal transport measurements. A microscopic analysis from NPD data demonstrates a near-perfect stoichiometry of Bi2Te3 and a fair amount of anharmonicity of the chemical bonds. The as-grown material presents a metallic behavior, showing a record-low resistivity at 320 K of 2 μΩ m, which is advantageous for its performance as a thermoelectric material. SEM analysis shows a stacking of nanosized sheets, each of them presumably single-crystalline, with large surfaces perpendicular to the c crystallographic axis. This nanostructuration notably affects the thermoelectric properties, involving many surface boundaries that are responsible for large phonon scattering factors, yielding a thermal conductivity as low as 1.2 W m(-1) K(-1) around room temperature. PMID:26976428

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

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2011-12-18

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

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    Angeliki Lekatou; Athanasios K. Sfikas; Christina Petsa; Alexandros E. Karantzalis

    2016-01-01

    Hypereutectic Al-Co alloys of various Co contents (7–20 weight % (wt.%) Co) were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co) to coarse primary Al9Co2 predominance (20 wt.% Co). Co dissolution in Al far exceeded the negligible ...

  1. Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

    OpenAIRE

    Grégoire, M.; Jégo, Sébastien; Maury, René; Payot, Betchaida D.; Tamayo, Rodolfo A.; Yumul, Graciano P.

    2008-01-01

    The Monglo adakite contains mafic and ultramafic xenoliths, which probably originated from the mantle section of an Early Cretaceous supra-subduction zone ophiolitic complex located within the Luzon arc crust. Spinel-bearing dunites are dominant among this xenolith collection and display evidence for three episodes of subduction-related melt percolation. The first one is evidenced by an undeformed clinopyroxene characterized by convex-upwards REE pattern. This clinopyroxene crystallized from ...

  2. Plasma chemistry fluctuations in a reactive arc plasma in the presence of magnetic fields

    International Nuclear Information System (INIS)

    The effect of a magnetic field on the plasma chemistry and pulse-to-pulse fluctuations of cathodic arc ion charge state distributions in a reactive environment were investigated. The plasma composition was measured by time-of-flight charge-to-mass spectrometry. The fluctuation of the concentrations of Al+, Al2+, and Al3+ was found to increase with an increasing magnetic field strength. We suggest that this is caused by magnetic field dependent fluctuations of the energy input into cathode spots as seen through fluctuations of the cathode potential. These results are qualitatively consistent with the model of partial local Saha equilibrium and are of fundamental importance for the evolution of the structure of films deposited by reactive cathodic arc deposition

  3. Experimental Investigation of Biogas Reforming in Gliding Arc Plasma Reactors

    Directory of Open Access Journals (Sweden)

    P. Thanompongchart

    2014-01-01

    Full Text Available Biogas is an important renewable energy source. Its utilization is restricted to vicinity of farm areas, unless pipeline networks or compression facilities are established. Alternatively, biogas may be upgraded into synthetic gas via reforming reaction. In this work, plasma assisted reforming of biogas was investigated. A laboratory gliding arc plasma setup was developed. Effects of CH4/CO2 ratio (1, 2.33, 9, feed flow rate (16.67–83.33 cm3/s, power input (100–600 W, number of reactor, and air addition (0–60% v/v on process performances in terms of yield, selectivity, conversion, and energy consumption were investigated. High power inputs and long reaction time from low flow rates, or use of two cascade reactors were found to promote dry reforming of biogas. High H2 and CO yields can be obtained at low energy consumption. Presence of air enabled partial oxidation reforming that produced higher CH4 conversion, compared to purely dry CO2 reforming process.

  4. Stability and erosion of melt layers developed on plasma facing components of tokamaks

    International Nuclear Information System (INIS)

    Melting of metallic plasma facing components such as tungsten (W) divertor, macroscopic melt motion, and melt splashing due to edge localized modes and plasma disruptions is a major concern in fusion devices such as ITER. The viscous stability analysis and computational modelling of coupled W-melt-plasma flows are performed using the developed volume-of-fluid magnetohydrodynamic code. The effects of plasma velocity and magnetic field, whether parallel or perpendicular to the direction of W-melt flow, on melt motion and splashing from a melt pool are studied. The distributions of hydrodynamic and magnetic pressure as well as the vector fields of velocity and magnetic field are investigated. The development of waves with certain wavelengths on the W-melt surface and formation of W-melt blob on the pool's edge are observed in the absence and presence of an external magnetic field. For the investigated speeds of viscous plasma, the parallel magnetic field of 5 T does not suppress W-melt motion and splashing from the pool, plasma-induced surface waves, and ejection of molten droplets. However, the Lorentz force induced by a perpendicular magnetic field accelerates the splashing of W-melt from a melt pool but only when the stream of viscous plasma becomes well coupled to the melt motion. Under the plasma impact with high velocity of ∼5000 m s−1, the W-melt does not undergo a significant motion disintegrating quickly into droplets dragged away by the plasma wind, independent of the presence or absence of a magnetic field. This magnitude of plasma velocity is found to be in good agreement with that predicted by the viscous stability analysis. (paper)

  5. The Main Plasma Chemical Process of Nitric Oxide Production by Arc Discharge

    Science.gov (United States)

    Yang, Qi; Hu, Hui; Chen, Weipeng; Xu, Jie; Zhang, Jinli; Wu, Shuang

    2011-12-01

    By adopting the optical multi-channel analyzer combined with fourier transform infrared (FTIR) spectrometer, the dominant free radicals and products generated by arc discharge were measured and studied, and the main plasma chemical reaction process in the nitric oxide production by arc discharge was identified. Plasma chemical kinetic curves of O, O2, N2, N and NO were simulated by using CHEMKIN and MATLAB. The results show that the main plasma chemical reaction process of nitric oxide production by arc discharge is a replacement reaction between O and N2, where NO can be generated instantaneously when discharging reaches stable.

  6. The Main Plasma Chemical Process of Nitric Oxide Production by Arc Discharge

    International Nuclear Information System (INIS)

    By adopting the optical multi-channel analyzer combined with fourier transform infrared (FTIR) spectrometer, the dominant free radicals and products generated by arc discharge were measured and studied, and the main plasma chemical reaction process in the nitric oxide production by arc discharge was identified. Plasma chemical kinetic curves of O, O2, N2, N and NO were simulated by using CHEMKIN and MATLAB. The results show that the main plasma chemical reaction process of nitric oxide production by arc discharge is a replacement reaction between O and N2, where NO can be generated instantaneously when discharging reaches stable. (15th asian conference on electrical discharge)

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

    International Nuclear Information System (INIS)

    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

  8. Development of a thermally and chemically non-equilibrium model for decaying SF6 arc plasmas

    OpenAIRE

    Tanaka, Yasunori; Suzuki, Katsumi; Iijima, Takanori; Shinkai, Takeshi

    2013-01-01

    This paper describes the development of a model with both chemically and thermally non-equilibrium effects in an SF6 arc plasma during decaying phase with transient recovery voltage (TRV) application. The SF 6 arc plasma in decaying phase can be seen in a high voltage SF 6 gas circuit breaker during a large current interruption process. The TRV is often applied to the arc plasma, which may elevate the electron temperature Te than heavy particle temperature Th. This developed model solves ener...

  9. A study on the melting of metal wastes and the partitioning of the radionuclides in an arc furnace

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Wang-Kyu; Song, Pyung-Seob; Jung, Chong-Hun; Oh, Won-Zin [KAERI, Daejeon (Korea, Republic of); Min, Byung-Youn [Chungnam National Univ., Daejeon (Korea, Republic of)

    2005-11-15

    The distribution of the radioactive nuclides such as cobalt, cesium, and strontium has been investigated in a lab-scale d. c. arc furnace. The slag former for the melting of the stainless and carbon steel was based on the constituents of silica(SiO{sub 2}), calcium oxide(CaO), and aluminum oxide(Al{sub 2}O{sub 3}) and Borate(B{sub 2}O{sub 3}) and calcium fluoride (CaF{sub 2}) additions were included to provide an increased slag fluidity and oxidative potential. In the melting of the stainless steel, the amount of slag formation increased with an increase of the concentration of the slag former. But the effects of the slag basicity on the amount of slag formation showed a local maximum value of the slag formation by increasing the basicity index in the melting of the stainless steel as well as in the melting of the carbon steel. With an increase of the amount of slag former addition, the trends of the cobalt distribution into the ingot and slag depended on the king of slag former used in the melting of the stainless steel while the effect of the slag basicity on the distribution of the cobalt was not clarified in the melting of carbon steel. In the melting of stainless steel, only 20% of the strontium remained in the slag phase and it was barely present in the ingot. But, in the melting of the carbon steel, strontium was captured at up to 50% into the slag phase. Cesium was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the dust phase.

  10. A study on the melting of metal wastes and the partitioning of the radionuclides in an arc furnace

    International Nuclear Information System (INIS)

    The distribution of the radioactive nuclides such as cobalt, cesium, and strontium has been investigated in a lab-scale d. c. arc furnace. The slag former for the melting of the stainless and carbon steel was based on the constituents of silica(SiO2), calcium oxide(CaO), and aluminum oxide(Al2O3) and Borate(B2O3) and calcium fluoride (CaF2) additions were included to provide an increased slag fluidity and oxidative potential. In the melting of the stainless steel, the amount of slag formation increased with an increase of the concentration of the slag former. But the effects of the slag basicity on the amount of slag formation showed a local maximum value of the slag formation by increasing the basicity index in the melting of the stainless steel as well as in the melting of the carbon steel. With an increase of the amount of slag former addition, the trends of the cobalt distribution into the ingot and slag depended on the king of slag former used in the melting of the stainless steel while the effect of the slag basicity on the distribution of the cobalt was not clarified in the melting of carbon steel. In the melting of stainless steel, only 20% of the strontium remained in the slag phase and it was barely present in the ingot. But, in the melting of the carbon steel, strontium was captured at up to 50% into the slag phase. Cesium was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the dust phase

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

    Science.gov (United States)

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

    2015-09-01

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

  12. Powerful demolition techniques - plasma fusion cutting, contact arc metal cutting (CAMC), and contact arc metal grinding (CAMG); Leistungsfaehige Rueckbautechnologien - Plasmaschmelzschneiden, Kontakt-Lichtbogen-Metall-Schneiden (CAMC) und Kontakt-Lichtbogen-Metall-Trennschleifen (CAMG)

    Energy Technology Data Exchange (ETDEWEB)

    Bach, F.W.; Kremer, G.; Ruemenapp, T. [Leibniz Univ. Hannover, Inst. fuer Werkstoffkunde, Garbsen (Germany)

    2006-10-15

    One of the most complicated steps in the demolition of nuclear power plants is the disassembly of radiologically burdened large components. Most of this work must be performed remotely and under a cover of water. Moreover, dimensions, structures, and locations pose problems. Various techniques of disassembly are available which have specific pros and cons. Thermal cutting techniques, i.e. plasma fusion cutting, contact arc metal cutting (CAMC), and contact arc metal grinding (CAMG), can be used with comparatively simple handling systems even for large material thicknesses and complex geometries. These thermal cutting techniques have been advanced considerably at the Institute for Materials Technology of the University of Hanover in recent years. In plasma fusion cutting, the workpiece is molten, partly evaporated, and the melt is blown out of the kerf by the gas jet. CAMC and CAMG are based on the thermal abrasion of electrically conducting materials under water by means of repeated non-steady short-circuit high-current arcs resulting from contacts between the electrode and the workpiece. Unlike plasma or laser beam cutting, hollow structures and sandwich structures pose no problems. The performance capability of plasma fusion cutting and contact arc metal cutting has been demonstrated impressively in the disassembly of reactor internals of the Karlsruhe multi-purpose research reactor (MZFR). (orig.)

  13. Deliberation of arc plasma characteristics according to experimental results in a typical gas circuit-breaker

    International Nuclear Information System (INIS)

    One of the industrial plasma applications is in the gas circuit breakers (GCB) and switching processes. During GCB operation and opening of its two contacts, current flows through of the inter-electrode medium (generally SF6 or its mixture) and electric arc forms from the plasma that has been created between the contacts. The electric arc is a self-sustained discharge having low voltage drop and able to support great amplitudes of current. The technical basis of circuit breaker is: initiating arc plasma, flowing a large current, cooling it effectively to avoid re-ignition, and finally the transition from a well-conducting medium into insulating gas space in a very short time interval. In other words, for a successful interruption we need to know about power brought to the arc and that of removed. In this paper an attempt has been made to study, characterize and understand some arc behaviors such as arc conductance and its changes according to recorded current and voltage traces experimentally. From physical point of view, there are different phenomena that affect on arc behavior. According to methodology used here, we tried to understand some of arc behavior from experimental results and finally we extract some arc parameters. (author)

  14. Effect of pressure on behavior of anode attachment of dc arc plasma torch

    Czech Academy of Sciences Publication Activity Database

    Chumak, Oleksiy; Kopecký, Vladimír; Konrád, Miloš; Kavka, Tetyana; Hrabovský, Milan

    2005-01-01

    Roč. 9, č. 3 (2005), s. 391-400. ISSN 1093-3611 R&D Projects: GA ČR GA202/05/0669 Institutional research plan: CEZ:AV0Z20430508 Keywords : arc anode * dc arc jet * anode restrike * low pressure Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.136, year: 2005

  15. Life cycle cost analysis for the Plasma Arc Furnace

    Energy Technology Data Exchange (ETDEWEB)

    Barnes-Smith, P.

    1994-03-01

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

  16. Synthesis of aluminium nanoparticles by arc plasma spray under atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mandilas, Charalampos; Daskalos, Emmanouil [Aerosol and Particle Technology Laboratory (APTL), Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas (CERTH/CPERI), P.O. Box 361, 57001 Thermi, Thessaloniki (Greece); Karagiannakis, George, E-mail: gkarag@cperi.certh.gr [Aerosol and Particle Technology Laboratory (APTL), Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas (CERTH/CPERI), P.O. Box 361, 57001 Thermi, Thessaloniki (Greece); Konstandopoulos, Athanasios G., E-mail: agk@cperi.certh.gr [Aerosol and Particle Technology Laboratory (APTL), Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas (CERTH/CPERI), P.O. Box 361, 57001 Thermi, Thessaloniki (Greece); Department of Chemical Engineering, Aristotle University, P.O. Box 1517, 54006 Thessaloniki (Greece)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer A customized arc-plasma spraying based system has been designed and implemented. Black-Right-Pointing-Pointer The system is relatively simple, robust and operates at atmospheric pressure. Black-Right-Pointing-Pointer Preparation of aluminium nanoparticles from micron-sized powder was successful. Black-Right-Pointing-Pointer Various nano-sized distributions were possible depending on operating parameters. Black-Right-Pointing-Pointer Optimization of the proposed design will lead to higher efficiencies and throughput. - Abstract: The present study addresses the feasibility to synthesize aluminium nanoparticles (NPs) from micron-sized aluminium powder with the use of a customized atmospheric plasma spraying (APS) technique. Using APS, nanoparticle synthesis can be achieved via rapid melting and vaporization of the initial micrometric particles and their subsequent re-nucleation. A custom mantle system was designed and developed with the aid of relevant simplified CFD simulations. The mantle provided the necessary inert environment (argon), at ambient pressure, in order to avoid any oxidation of the metal during plasma spraying while promoted rapid quenching of the gasified metal. The particles formed were collected with the aid of a quartz filter downstream of the plasma flame and the production rate achieved was 2 g min{sup -1}. Ex situ post-characterization of the particles via X-ray diffraction, specific surface area measurement (BET), transmission electron microscopy (TEM) coupled with energy dispersive spectrometry (EDS) and thermogravimetric analysis (TGA) under air revealed that the powders obtained primarily comprised of monocrystalline metallic aluminium nanoparticles of almost spherical shape. The NPs possessed a 2-5 nm oxide coating layer. By regulating the conditions inside the mantle, a variety of different size distributions were obtained.

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

    Science.gov (United States)

    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.

  18. Computational study of flow dynamics from a dc arc plasma jet

    CERN Document Server

    Trelles, Juan Pablo

    2013-01-01

    Plasma jets produced by direct-current (DC) non-transferred arc plasma torches, at the core of technologies ranging from spray coating to pyrolysis, present intricate dynamics due to the coupled interaction of fluid flow, thermal, and electromagnetic phenomena. The flow dynamics from an arc discharge plasma jet are investigated using time-dependent three-dimensional simulations encompassing the dynamics of the arc inside the torch, the evolution of the jet through the discharge environment, and the subsequent impingement of the jet over a flat substrate. The plasma is described by a chemical equilibrium and thermodynamic nonequilibrium (two-temperature) model. The numerical formulation of the physical model is based on a monolithic and fully-coupled treatment of the fluid and electromagnetic equations using a Variational Multiscale Finite Element Method. Simulation results uncover distinct aspects of the flow dynamics, including the jet forcing due to the movement of the electric arc, the prevalence of deviat...

  19. Helium Arc Plasmas as an Efficient Source for Excitation of Spectra of Light Elements

    International Nuclear Information System (INIS)

    Spectroscopic properties of helium arc plasmas with small gaseous admixtures of CO2, N2, and O2 are discussed. From spectral line intensity measurements population densities of selected excited atomic levels are determined. (author)

  20. On the dynamics of cutting arc plasmas: the role of the power supply ripple

    Directory of Open Access Journals (Sweden)

    Leandro Prevosto

    2012-08-01

    Full Text Available The power sources used in cutting arc torches are usually poorly stabilized and have a large ripple factor. The strong oscillatory components in the voltage and arc current produce in turn, large fluctuations in the plasma quantities. Experimental observations on the dynamics of the non-equilibrium plasma inside the nozzle of a 30 A oxygen cutting torch with a 7 % ripple level of its power source are reported in this work.

  1. On the dynamics of cutting arc plasmas: the role of the power supply ripple

    OpenAIRE

    Leandro Prevosto

    2012-01-01

    The power sources used in cutting arc torches are usually poorly stabilized and have a large ripple factor. The strong oscillatory components in the voltage and arc current produce in turn, large fluctuations in the plasma quantities. Experimental observations on the dynamics of the non-equilibrium plasma inside the nozzle of a 30 A oxygen cutting torch with a 7 % ripple level of its power source are reported in this work.

  2. Modelization of plasma jets in an arc generator and study of instabilities

    International Nuclear Information System (INIS)

    The first results of the cooperation between the Poznan Polytechnic School and the CNRS Aerothermic Laboratory (Meudon), concerning the experimental analysis and modelization of plasma generators operating at low pressure and using an electric arc technique, are presented. The aim of the studies were a better understanding of these plasma sources, their operation hydrodynamic regimes and fluctuation characteristics (arc potential, pressure, electronic density). 23 fig., 6 ref

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

    International Nuclear Information System (INIS)

    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 ∼100kA, 15 μs period was propelled to ∼106cm/s as indicated in time-of-flight measurements and simulations. The voltage signal induced on a B 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 2cm, was established by unfolding the B 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. copyright 1997 American Institute of Physics

  4. Modeling and measurements of the arc plasma in a mixture of gases

    International Nuclear Information System (INIS)

    The wall-stabilized arc is a useful source of the radiation emitted by excited atoms and ions. This plasma has been widely applied in the spectroscopic research, e. g. for measurements of atomic and ionic structure data, such as spectral line strengths or Stark shifts and widths. The wall-stabilized arc and similar plasma sources are also used in many other industrial and scientific applications - especially as the plasma generators in various plasma torches and jets. In most of the applications the plasma is generated in a mixture of gases. As the wall-stabilized cascade arc exhibits the rather strong temperature gradients, the diffusion effects due to the temperature and molar gradients (in the cases of the molecular gases) are prominent, and strongly affect the arc parameters. In this work we present the comparison of the results of the measurements of the plasma parameters in the wall-stabilized arc working in the mixture of argon and nitrogen with the theoretical calculations of the plasma temperatures and molar ratios. The gas mixture is introduced uniformly along the arc column between each of the stabilizing plates. From measured lateral distribution of radiation (NI, HI, ArI line intensity and width measurements), after Abel inversion the radial temperature and species distributions were obtained at various positions of the arc column. As the atomic lines can be measured only close to the plasma axis (the Boltzmann plot of the atomic argon or nitrogen lines is reliable only if the sufficiently highly excited states are present), for the measurement of the fringe temperatures the molecular spectroscopy was also performed (measurements of the bands of nitrogen molecule and nitrogen molecular ion). The model consisted of one-dimensional calculations of all plasma parameters (both temperature and demixing), based on the theory developed by Murphy. The results show that even the relatively simple model can predict the molecular ratio distributions in the gas

  5. Application of Steenbeck's minimum principle for three-dimensional modelling of DC arc plasma torches

    International Nuclear Information System (INIS)

    In this paper, physical/mathematical models for the three-dimensional, quasi-steady modelling of the plasma flow and heat transfer inside a non-transferred DC arc plasma torch are described in detail. The Steenbeck's minimum principle (Finkelnburg W and Maecker H 1956 Electric arcs and thermal plasmas Encyclopedia of Physics vol XXII (Berlin: Springer)) is employed to determine the axial position of the anode arc-root at the anode surface. This principle postulates a minimum arc voltage for a given arc current, working gas flow rate, and torch configuration. The modelling results show that the temperature and flow fields inside the DC non-transferred arc plasma torch show significant three-dimensional features. The predicted anode arc-root attachment position and the arc shape by employing Steenbeck's minimum principle are reasonably consistent with experimental observations. The thermal efficiency and the torch power distribution are also calculated in this paper. The results show that the thermal efficiency of the torch always ranges from 30% to 45%, i.e. more than half of the total power input is taken away by the cathode and anode cooling water. The special heat transfer mechanisms at the plasma-anode interface, such as electron condensation, electron enthalpy and radiative heat transfer from the bulk plasma to the anode inner surface, are taken into account in this paper. The calculated results show that besides convective heat transfer, the contributions of electron condensation, electron enthalpy and radiation to the anode heat transfer are also important (∼30% for parameter range of interest in this paper). Additional effects, such as the non-local thermodynamic equilibrium plasma state near the electrodes, the transient phenomena, etc, need to be considered in future physical/mathematical models, including corresponding measurements

  6. Physics-Based Modeling of Electric Operation, Heat Transfer, and Scrap Melting in an AC Electric Arc Furnace

    Science.gov (United States)

    Opitz, Florian; Treffinger, Peter

    2016-04-01

    Electric arc furnaces (EAF) are complex industrial plants whose actual behavior depends upon numerous factors. Due to its energy intensive operation, the EAF process has always been subject to optimization efforts. For these reasons, several models have been proposed in literature to analyze and predict different modes of operation. Most of these models focused on the processes inside the vessel itself. The present paper introduces a dynamic, physics-based model of a complete EAF plant which consists of the four subsystems vessel, electric system, electrode regulation, and off-gas system. Furthermore the solid phase is not treated to be homogenous but a simple spatial discretization is employed. Hence it is possible to simulate the energy input by electric arcs and fossil fuel burners depending on the state of the melting progress. The model is implemented in object-oriented, equation-based language Modelica. The simulation results are compared to literature data.

  7. Boosting persistence time of laser-induced plasma by electric arc discharge for optical emission spectroscopy

    International Nuclear Information System (INIS)

    Plasma induced by nanosecond laser ablation is re-excited by a pulsed electric discharge and the parameters and optical emission of the plasma are measured. The discharge is a low-voltage and high-current electric arc that is triggered by the laser-induced plasma and slowly decaying with time. The optical emission of such combined plasma lasts up to several milliseconds which is much longer than without re-excitation (μs range). The emission spectra of re-excited plasma measured on different sample materials show higher line intensities than spectra measured by conventional laser-induced breakdown spectroscopy (LIBS). Moreover, emission lines of fluorine (spectral range 683–691 nm) and sulfur (range 520–550 nm) not detected by conventional LIBS become easily detectable with the combined plasma. The concentration of major components in metallurgical slags, as determined by calibration-free LIBS, agrees very well to the reference data evaluating the spectra taken from re-excited plasma. - Highlights: • Persistence time of laser-induced plasma in air is increased from ~ 10 μs to ~ 1 ms. • Laser-induced plasma triggers an electric arc discharge that boosts the plasma. • The combined laser-arc plasma is in LTE state over very long time (ms range). • CF-LIBS method delivers accurate results evaluating spectra of combined plasma. • Emission from S and F, not detected by LIBS, is detected with combined plasma

  8. Two-dimensional model of evolution in the DC arc plasma generator

    International Nuclear Information System (INIS)

    A time dependent, two-dimensional model for simulating the plasma evolution in the DC arc plasma generator is conducted. The governing equations of a set of electrostatic magneto hydrodynamic (MHD) equations are solved by employing an efficient finite difference method. Up-wind schemes and uniform meshes in space are used in numerical simulation. the distributions and evolution of the density, velocity, temperature, electric potential, current density, etc. of the arc plasmas of two kinds of cathode model are computed. The influence of the cathode shape in are plasma generator is investigated. The results show that the conical cathode produces bigger current density and ionizes more efficiently than rod cathode in same geometry and operating conditions. But the former easily bring on the computing instability. The simulating results can be used to address designing the device for big current arc plasma generator. (authors)

  9. Evaluation of characteristics of plasma generated in DC arc torch with gas-water stabilization of arc

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Mašláni, Alan; Hrabovský, Milan

    Bratislava : Department of Experimental Physics Comenius University, 2009 - (Papp, V.; Orshzágh, J.; Matúška, J.; Matejčík, Š.), s. 173-174 ISBN 978-80-89186-45-7. [Symposium on Application of Plasma Processes, SAPP/17th./. Liptovský Ján (SK), 17.01.2009-22.01.2009] R&D Projects: GA AV ČR KJB100430701 Institutional research plan: CEZ:AV0Z20430508 Keywords : DC arc torch Subject RIV: BL - Plasma and Gas Discharge Physics

  10. Plasma diagnostics in gas metal arc welding by optical emission spectroscopy

    International Nuclear Information System (INIS)

    The plasma column in a metal inert gas welding process is investigated by optical emission spectroscopy and high-speed imaging. The concentration and repartition of iron vapours are measured and correlated with the plasma and electrode geometric configuration. Plasma temperatures and electron densities are also measured for each studied position in the plasma. The temperatures are calculated using two different methods, allowing validation of the local thermodynamic equilibrium state of the plasma. The results show a maximum temperature of 12 500 K in the upper part of the arc, away from the arc axis. The iron concentration reaches a maximum of 0.3% close to the anode and strongly decreases along both the vertical and radial directions. The plasma thermophysical properties, calculated from this plasma composition, are then discussed regarding the metal transfer mode.

  11. Plasma diagnostics in gas metal arc welding by optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Valensi, F; Pellerin, S; Zielinska, S [GREMI, Universite d' Orleans (Site de Bourges)/CNRS, BP 4043, 18028 Bourges cedex (France); Boutaghane, A [Universite des Sciences et de la Technologie Houari Boumediene, Alger (Algeria); Dzierzega, K [Marian Smoluchowski Institute of Physics, Jagellonian University, Krakow (Poland); Pellerin, N [CNRS, UPR3079 CEMHTI, 1D av. de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Briand, F, E-mail: flavien.valensi@laplace.univ-tsle.f, E-mail: stephane.pellerin@univ-orleans.f, E-mail: aboutaghane@yahoo.f, E-mail: krzycho@netmail.if.uj.edu.p, E-mail: sylwia.zielinska@airliquide.co, E-mail: nadia.pellerin@univ-orleans.f, E-mail: francis.briand@airliquide.co [CTAS-Air Liquide Welding, Saint Ouen l' Aumone, 95315 Cergy-Pontoise cedex (France)

    2010-11-03

    The plasma column in a metal inert gas welding process is investigated by optical emission spectroscopy and high-speed imaging. The concentration and repartition of iron vapours are measured and correlated with the plasma and electrode geometric configuration. Plasma temperatures and electron densities are also measured for each studied position in the plasma. The temperatures are calculated using two different methods, allowing validation of the local thermodynamic equilibrium state of the plasma. The results show a maximum temperature of 12 500 K in the upper part of the arc, away from the arc axis. The iron concentration reaches a maximum of 0.3% close to the anode and strongly decreases along both the vertical and radial directions. The plasma thermophysical properties, calculated from this plasma composition, are then discussed regarding the metal transfer mode.

  12. A novel 300 kW arc plasma inverter system based on hierarchical controlled building block structure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To date, the high power arc plasma technology is widely used. A next generation high power arc plasma system based on building block structure is presented. The whole arc plasma inverter system is composed of 12 paralleled units to increase the system output capability. The hierarchical control system is adopted to improve the reliability and flexibility of the high power arc plasma inverter. To ensure the reliable turn on and off of the IGBT module in each building block unit, a special pulse drive circuit is designed by using pulse transformer. The experimental result indicates that the high power arc plasma inverter system can transfer 300 kW arc plasma energy reliably with high efficiency.

  13. Observation of HF Cathode and ARC Root Inside Cutting Plasma Torch

    Czech Academy of Sciences Publication Activity Database

    Šonský, Jiří; Gruber, Jan

    Brno : Brno university of Technology, 2013, s. 297-300. ISBN 978-80-214-4753-0. [Symposium on Physics of Switching Arc /20./. Nové Město na Moravě (CZ), 02.09.2013-06.09.2013] Institutional support: RVO:61388998 Keywords : plasma torch * fluctuations * FFT Subject RIV: BL - Plasma and Gas Discharge Physics

  14. Emission Spectroscopy of OH Radical in Water-Argon Arc Plasma Jet

    Czech Academy of Sciences Publication Activity Database

    Mašláni, Alan; Sember, Viktor

    2014-01-01

    Roč. 2014, April (2014), "952138"-"952138". ISSN 2314-4920 R&D Projects: GA ČR GAP205/11/2070 Institutional support: RVO:61389021 Keywords : Emission spectroscopy * OH radical * arc plasma jet Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.538, year: 2014 http://www.hindawi.com/journals/jspec/2014/952138/abs/

  15. Deposição por plasma com arco transferido Hardfacing by plasma transfer arc process

    Directory of Open Access Journals (Sweden)

    Víctor Vergara Díaz

    2010-03-01

    Full Text Available Em virtude do Processo de Soldagem Plasma com Alimentação de Pó ter similaridades com o Processo de Soldagem Plasma com Alimentação de Arame, foi realizado um estudo comparativo entre ambos os processos utilizando-se a liga a base de cobalto comercialmente conhecida como Stellite 6, como material de adição na forma de pó e arame. A pesquisa foi realizada com a expectativa de ser aplicada nas operações de revestimentos de superfícies, em especial em pás de turbinas hidráulicas desgastadas por cavitação. A seleção do material de adição a ser empregado depende da natureza do mecanismo de desgaste encontrado. No Labsolda, a liga Stellite 6 vem sendo uma das mais utilizadas, por apresentar uma excelente resistência ao desgaste erosivo por cavitação. Foi avaliada a influência da vazão de gás de plasma a partir dos valores de diluição, dimensões do cordão, dureza e microestrutura. O Processo de Soldagem Plasma com Alimentação de Pó foi o que produziu o melhor acabamento superficial, menor diluição, melhor molhamento e maior largura. Com isto abre-se uma nova perspectiva para revestimentos metálicos e neste contexto se insere a recuperação por soldagem de partes erodidas de turbinas hidráulicas.The Plasma powder transferred arc welding process, which uses feed stock in the powder form, has similarities with Plasma wire transferred arc welding. This work describes a comparative study of the two processes using a Cobalt-based alloy commercially known as Stellite 6. This Co-based alloy is recognized for its superior cavitation erosion resistance. The aim of this work is to investigate the potential of PTA coatings for the protection and refurbishiment hydraulic turbine blades. Coatings were evaluated for the influence of Plasma gas flow rate on coating dilution, geometry, hardness and microstructure. Coatings processed with the atomized Stellite 6 powder feestock showed a superior surface quality, lower dilution

  16. Plasma arc and cold crucible furnace vitrification for medium level waste: a review

    Energy Technology Data Exchange (ETDEWEB)

    Poitou, S.; Fiquet, O.; Bourdeloie, C.; Gramondi, P.; Rebollo, F. [CEA Cadarache, Dept. d' Etudes des Dechets, DED, 13 - Saint Paul lez Durance (France); Girold, C.; Charvillat, J.P.; Boen, R.; Jouan, A.; Ladirat, C.; Nabot, J.P.; Ochem, D. [CEA Marcoule, Dept. d' Ingenierie et d' Etudes des Confinements DIEC, 30 (France); Baronnet, J.M. [Limoges Univ., Lab. de Chimie des Plasma, 87 (France)

    2001-07-01

    Initially developed for high-level waste reprocessing, several vitrification processes have been under study since the 80's at the French Atomic Energy Commission (CEA) for other waste categories. According to the French law concerning waste management research passed on December 30, 1991, vitrification may be applied to mixed medium-level waste. A review of processes developed at CEA is presented: cold crucible furnace heated by induced current, refractory furnace heated by nitrogen transferred arc plasma torch, and coupling of cold crucible furnace with oxygen transferred plasma arc twin torch. Furthermore, gas post-combustion has been studied with an oxygen non-transferred plasma torch. (authors)

  17. Plasma arc and cold crucible furnace vitrification for medium level waste: a review

    International Nuclear Information System (INIS)

    Initially developed for high-level waste reprocessing, several vitrification processes have been under study since the 80's at the French Atomic Energy Commission (CEA) for other waste categories. According to the French law concerning waste management research passed on December 30, 1991, vitrification may be applied to mixed medium-level waste. A review of processes developed at CEA is presented: cold crucible furnace heated by induced current, refractory furnace heated by nitrogen transferred arc plasma torch, and coupling of cold crucible furnace with oxygen transferred plasma arc twin torch. Furthermore, gas post-combustion has been studied with an oxygen non-transferred plasma torch. (authors)

  18. Glow-to-arc transition events in H2-Ar direct current pulsed plasma: Automated measurement of current and voltage

    International Nuclear Information System (INIS)

    The glow-to-arc transition phenomena (arcing) observed in plasma reactors used in materials processing was studied through the arcs characteristic current and voltage waveforms. In order to capture these arcs signals, a LABVIEW based automated instrumentation system (ARCVIEW) was developed, including the integration of an oscilloscope equipped with proper current and voltage probes. The system also allows capturing the process parameters at the arc occurrence moments, which were used to map the arcs events conditions. Experiments in H2-Ar DC pulsed plasma returned signals data from 215 arcs events, which were analyzed through software routines. According to the results, an anti-arcing system should react in the time order of few microseconds to prevent most of the damage caused by the undesired arcing phenomena.

  19. Vacuum arc plasma thrusters with inductive energy storage driver

    Science.gov (United States)

    Krishnan, Mahadevan (Inventor)

    2009-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Angeliki Lekatou

    2016-02-01

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

  1. Optimization of Weld Bead Parameters of Nickel Based Overlay Deposited by Plasma Transferred Arc Surfacing with Adequacy Test

    OpenAIRE

    Bhaskarananda Dasgupta; Pinaky Bhadury

    2014-01-01

    Plasma Transferred Arc surfacing is a kind of Plasma Transferred Arc Welding process. Plasma Transferred Arc surfacing (PTA) is increasingly used in applications where enhancement of wear, corrosion and heat resistance of materials surface is required. The shape of weld bead geometry affected by the PTA Welding process parameters is an indication of the quality of the weld. In this paper the analysis and optimization of weld bead parameters, during deposition of a Nickel based...

  2. Protection against arc erosion of 316 stainless steel by plasma source nitridation

    International Nuclear Information System (INIS)

    The effects of surface nitridation of 316 SS on protection against arc erosion and on suppression of plasma cooling were investigated by using thermal shock loading of 75 J/cm2. The volume loss by arcing was remarkably reduced by nitridation to about 1/6. Meanwhile, the mass loss increased by nitridation to about 4 times as much as for the non-nitrided sample. It was understood by XMA analysis of the nitrided sample before and after arcing that the increased mass loss was mainly due to nitrogens released from the nitrided sample by arcing. The nitrided to non-nitrided ratio of the total radiated power of impurities released from the samples by arcing was roughly estimated to be about 0.47 despite the increase of the mass loss by nitridation. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Keidar, Michael [George Washington University

    2013-06-23

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

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

    Science.gov (United States)

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

    2012-03-01

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

  5. Spectrographic determination of rare earth elements using a wall-stabilized plasma arc

    International Nuclear Information System (INIS)

    A wall-stabilized dc arc is used for the determination of rare earth elements (REEs). Solutions of REEs are mixed with potassium chloride and sprayed in an argon stream into the plasma of the arc. At the optimal excitation conditions, the spectrum of the arc has a very low background and contains no molecular bands in the visible region. Analytical curves and limits of detection for fourteen REEs are determined and the matrix effects are studied. The procedure is applied to the determination of REEs in a standard phosphate sample. (author)

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

    International Nuclear Information System (INIS)

    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. (author)

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

    Science.gov (United States)

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

    2015-07-01

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

  8. Influence of arc current modulation in plasma torch on jet oscillations

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan; Kopecký, Vladimír

    Karlsruhe : IEEE, 2008. s. 157-157. ISBN 978-1-4244-1930-2. ISSN 0730-9244. [IEEE International Conference on Plasma Science - ICOPS 2008 /35./. 15.06.2008-19.06.2008, Karlsruhe ] R&D Projects: GA ČR GA202/08/1084 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma torch * oscillations * arc current modulation * boundary jet instability Subject RIV: BL - Plasma and Gas Discharge Physics http://www.icops2008.org/

  9. Measurement of Temperature in the Steam Arcjet During Plasma Arc Cutting

    Czech Academy of Sciences Publication Activity Database

    Mašláni, Alan; Sember, Viktor; Stehrer, T.; Pauser, H.

    2013-01-01

    Roč. 33, č. 3 (2013), s. 593-604. ISSN 0272-4324 R&D Projects: GA ČR GAP205/11/2070 Institutional support: RVO:61389021 Keywords : Plasma arc cutting * Optical emission spectroscopy * Plasma temperature * Steam torch Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.599, year: 2013 http://link.springer.com/content/pdf/10.1007%2Fs11090-013-9443-y.pdf

  10. Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding

    Directory of Open Access Journals (Sweden)

    Koray Yurtisik

    2013-09-01

    Full Text Available Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex microstructure without compromising the welding efficiency. 11.1 mm-thick standard duplex stainless steel plates were joined in a single-pass using this novel technique. Same plates were also subjected to conventional gas metal arc and plasma arc welding processes, providing benchmarks for the investigation of the weldability of the material. In the first place, the hybrid welding process enabled us to achieve less heat input compared to gas metal arc welding. Consequently, the precipitation of secondary phases, which are known to be detrimental to the toughness and corrosion resistance of duplex stainless steels, was significantly suppressed in both fusion and heat affected zones. Secondly, contrary to other keyhole techniques, proper cooling time and weld metal chemistry were achieved during the process, facilitating sufficient reconstructive transformation of austenite in the ferrite phase.

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

    International Nuclear Information System (INIS)

    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. (paper)

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

    Science.gov (United States)

    Han, Wen; Yuan, Zhao; He, Junjia

    2016-07-01

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

  13. Hybrid radiofrequency/arc plasma jet for generation of singlet oxygen

    Czech Academy of Sciences Publication Activity Database

    Schmiedberger, Josef; Gregor, Jan; Čenský, Miroslav; Jirásek, Vít; Rohlena, Karel; Vodičková, A.

    Vol. 1. Orleans : CNRS, 2014 - (Hong, D.; Bauchire, J.; Mikikian, M.; Rabat, H.), s. 127-130 ISBN 978-2-9548207-2-9. [International Conference on Gas Discharges and Their Applications/20./. Orleans (FR), 06.07.2014-11.07.2014] R&D Projects: GA ČR GAP102/12/0723 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : singlet oxygen * fast plasma mixing * radio - frequency plasma jet * arc plasma jet * hybrid plasma jet * discharge oxygen-iodine laser * biomedicine Subject RIV: BL - Plasma and Gas Discharge Physics

  14. Elaboration of metallic and composite fillings by plasma transferred arc. Process analysis and tribological study

    International Nuclear Information System (INIS)

    The experimental part of this research thesis addresses the parametric study of two surface filling processes (by plasma transferred arc, and by plasma arc projection followed by a coating remelting by electron beam), the elaboration by plasma transferred arc and the metallurgical characterization of fillings of nickel base alloys and composite materials made of tungsten carbides dispersed in a nickel matrix, and the characterization of fretting wear of the so-elaborated fillings in aqueous environment. The results show that the plasma transferred arc filling technique allows coating quality and microstructure to be controlled by adjusting the mass energy of the transferred arc. Besides, this technique results in a very good control of nickel alloy coatings. The various studied composites show that it is better to use a matrix with very few alloying elements or pre-coated carbides in order to avoid any cracking phenomenon. The content of dispersed carbides must not be greater than 60 per cent in weight. The best wear behaviour is obtained with polyhedral tungsten carbides dispersed within a low alloyed nickel matrix

  15. Generation of thermal plasmas in torches with liquid stabilized arcs

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan

    ICHMT, 1999 - (Fauchais, P.). s. 8-9 [International Symposium on Heat and Mass Transfer under Plasma Conditions/2nd./. 19.04.1999-23.04.1999, Tekirova, Antalya ] Subject RIV: BL - Plasma and Gas Discharge Physics

  16. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Volokitin, Oleg, E-mail: volokitin-oleg@mail.ru; Volokitin, Gennady, E-mail: vgg-tomsk@mail.ru; Skripnikova, Nelli, E-mail: nks2003@mai.ru; Shekhovtsov, Valentin, E-mail: shehovcov2010@yandex.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Vlasov, Viktor, E-mail: rector@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Ave., 634050, Tomsk (Russian Federation)

    2016-01-15

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ r{sub p} ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ r{sub p} ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  17. Behaviour of melted tungsten plasma facing components under ITER-like transient heat loads

    International Nuclear Information System (INIS)

    Tungsten in the form of macrobrush structure is foreseen as one of the two candidate materials for the ITER divertor and the dome. Melting and thus melt motion and melt splashing are expected to be main mechanisms of metallic target damage that determine the lifetime of ITER plasma facing components. Experiments carried out at the plasma gun facility QSPA-T for ELM-like heat loads demonstrated a significant erosion of frontal and lateral brush edges, which was confirmed by further numerical simulations. In the experiments and numerical simulations a threshold of brush edge melting was determined. In this paper most important mechanisms of melt splashing and melt bridge formation under ITER transient heat loads are analyzed. Approximate criteria for droplet ejection are obtained and the range of transient events without significant droplet injection is calculated. The critical radius of brush edges rounding which prevents the bridge formation at the macrobrush edges is determined

  18. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Science.gov (United States)

    Volokitin, Oleg; Vlasov, Viktor; Volokitin, Gennady; Skripnikova, Nelli; Shekhovtsov, Valentin

    2016-01-01

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ rp ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ rp ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  19. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    International Nuclear Information System (INIS)

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ rp ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ rp ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature

  20. Surface treatment of 0Cr19Ni9 stainless steel SMAW joint by plasma melting

    Institute of Scientific and Technical Information of China (English)

    罗伟; 栾景飞; 严密

    2002-01-01

    Micro-plasma are surface melting of 0Crl9Ni9 shielded metal are welding joint with a micro-plasma are welder produced a thin surface melted layer with a refined microtructure. The surface treatment changed the anodie polarization behavior in 0.5 mol/L H2SO4 solution. The polarization tests showed that for the as-welded joint both the heat-affected zone and the weld metal decreased in resis-tance to corrosion compared with the as-received parent material while for the micro-plasma are surface melted joint the corrosion resistance increased significantly. This increase in corrosion resistance is attributed to the rapid solidification of the melted layer. Rapid solidification of the melted layer refines its mierostrueture, decreases its mierosegregation, and inhibits the precipitation of chromium carbides at the grain boundaries.

  1. Gasification of Biomass in Water-Stabilized DC Arc Plasma

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan; Kopecký, Vladimír; Konrád, Miloš; Hlína, Michal; Kavka, Tetyana; Oost, van G.; Beeckman, E.; Verstraeten, J.; Ledecký, J.; Balabánová, E.

    Toronto, 2005 - (Mostaghimi, J.), s. 1003-1010 [International Symposium on Plasma Chemistry/17th./. Toronto (CA), 07.08.2005-12.08.2005] R&D Projects: GA ČR GA202/05/0669 Keywords : pyrolysis * thermal plasma * synthetis gas Subject RIV: BL - Plasma and Gas Discharge Physics

  2. Pyrolysis of wood in arc plasma for syngas production

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan; Konrád, Miloš; Kopecký, Vladimír; Hlína, Michal

    2006-01-01

    Roč. 10, č. 4 (2006), s. 557-570. ISSN 1093-3611 R&D Projects: GA ČR GA202/05/0669 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma pyrolysis * gasfication * syngas * thermal plasma * biomass Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.343, year: 2006

  3. Axial ion charge state distribution in the vacuum arc plasma jet

    International Nuclear Information System (INIS)

    We report on our experimental studies of the ion charge state distribution (CSD) of vacuum arc plasmas using a time-of-flight diagnostic method. The dependence of the CSD on the axial distance from the plasma source region was measured for a titanium vacuum arc. It was found that the axial CSD profile is nonuniform. Generally, the mean charge state increases approximately linearly with axial distance from about 1.7 at 12 cm up to 1.9 at 25 cm from the plasma source. A model for ion transport in the free boundary plasma jet is proposed which is based on the existence of an electric field in the quasineutral plasma. This model qualitatively explains the experimental results. (c) 2000 American Institute of Physics

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

    International Nuclear Information System (INIS)

    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. This paper describes 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

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

    Science.gov (United States)

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

    2014-02-01

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

  6. Investigation of Anode Attachment Area in Water/Argon Stabilized Plasma Arc

    Czech Academy of Sciences Publication Activity Database

    Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan

    Prague: MATFYZPRESS, 2015 - (Šafránková, J.; Pavlů, J.), s. 245-251. (WDS). ISBN 978-80-7378-311-2. [WDS - 2015 - 24th Annual Conference of Doctoral Students/24./. Prague (CZ), 02.06.2015-04.06.2015] R&D Projects: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : Arc-anode * plasma arc Subject RIV: BL - Plasma and Gas Discharge Physics http://www.mff.cuni.cz/veda/konference/wds/proc/proc-contents.php?year=2015

  7. The vacuum-arc plasma motion in a toroidal magnetic field

    International Nuclear Information System (INIS)

    The separation of the vacuum-arc plasma from macro-particles in the curvilinear plasma filters allows obtaining coatings with especially high characteristics. However, inside such filters the significant plasma losses also have been occurred. At the same time, increasing in the filter's efficiency is a difficult task without an effective mathematical model that really would describe the vacuum-arc plasma motion in a toroidal magnetic field. The description based on the flax-tube model was in fact only the first approximation in the decision of this problem. According to detailed flax-tube analysis of ions passage through the quarter torus plasma guide, the efficiency of the filter should grow up to 85% as the positive potential U, applied to the body of the plasma guide, is on the increase. However, the experiment showed that maximum of transparency reach up to ∼ 12%, at potential about of +18 Volts, and comes down under the further increase in potential. Such big digression from experiment does not justify the use of flux-tube model for designing of curvilinear plasma filters. We offer the new approach to the description of the vacuum-arc plasma motion in a toroidal magnetic field based on the solutions of steady-state (∂/∂t=0) Vlasov-Maxwell equations for the long plasma column aligned parallel to a constant axial magnetic field. The relations for the self-consistent electric polarization fields, which appear due to displacement of the electron component from ionic one on the curvilinear part of motion, were derived within a framework of the drift approximation. The dynamics of the central part of the plasma flow in the electric polarization fields was considered in detail. The displacement of the plasma flow at the output of the plasma guide was calculated for the carbon and titanium plasmas. The good agreement with the experimental data was obtained. (author)

  8. Melting, Oxidation, Evaporation of Particle in-Flight in Plasma Spray Processes

    Institute of Scientific and Technical Information of China (English)

    H.B.Xiong; L.L.Zheng

    2003-01-01

    A comprehensive numerical model has been developed to investigate the transient behaviors of particle characteristics, such as temperature, melting, evaporation, and oxidation status during argon-hydrogen DC plasma spraying.This model includes heat, momen

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. PMID:22380128

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

    Science.gov (United States)

    Banas, C. M.

    1974-01-01

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

  12. Boundary layer plasmas as a source for high-latitude, early afternoon, auroral arcs

    International Nuclear Information System (INIS)

    Simultaneous measurements of hot boundary layer plasma from PROGNOZ-7 and particle precipitation from the TIROS/NOAA satellite in nearly magnetically conjugate regions have been used to study the dynamo process responsible for the formation of high latitude, early afternoon, auroral arcs. Characteristic for the PROGNOZ-7 observations in the dayside boundary layer at high latitudes is the frequent occurrence of regions with injected magnetosheath plasma embedded in a 'halo' of antisunward flowing magnetosphere plasma. The injected magnetosheath plasma have several features which indicate that it also acts as a local source of EMF in the boundary layer. The process resembles that of a local MHD dynamo driven by the excess drift velocity of the injected magnetosheath plasma relative to the background magnetospheric plasma. The dynamo region is capable of driving fielc-aligned currents that couple to the ionosphere, where the upward current is associated with the high latitude auroral arcs. We demonstrate that the large-scale morphology as well as the detailed data intercomparison between PROGNOZ-7 and TIROS-N both agree well with a local injection of magnetosheath plasma into the dayside boundary layer as the main dynamo process powering the high-latitude, early afternoon auroral arcs. (Author)

  13. Argon-dominated plasma beam generated by filtered vacuum arc and its substrate etching

    International Nuclear Information System (INIS)

    A new technique to etch a substrate as a pre-treatment prior to functional film deposition was developed using a filtered vacuum arc plasma. An Ar-dominated plasma beam was generated from filtered carbon arc plasma by introducing appropriate flow rate of Ar gas in a T-shape filtered arc deposition (T-FAD) system. The radiation spectra emitted from the filtered plasma beam in front of a substrate table were measured. The substrate was etched by the Ar-dominated plasma beam. The principal results are summarized as follows. At a high flow rate of Ar gas (50 ml/min), when the bias was applied to the substrate, the plasma was attracted toward the substrate table and the substrate was well etched without film formation on the substrate. Super hard alloy (WC), bearing steel (SUJ2), and Si wafer were etched by the Ar-dominated plasma beam. The etching rate was dependent on the kind of substrate. The roughness of the substrate increased, when the etching rate was high. A pulse bias etched the substrate without roughening the substrate surface excessively.

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

    Science.gov (United States)

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

    2016-03-01

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

  15. Radiation Fluxes in SF6 and Argon Arc Plasmas

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír; Bartlová, M.

    Vol. I. Minsk : Trovant (Trojsk), 2000, s. 212-215. ISBN 5-89513-04-8. [International Conference on Plasma Physics and Plasma Technology (PPPT-3) /3./. Minsk (BY), 18.09.2000-22.09.2000] R&D Projects: GA ČR GA102/00/1586 Institutional research plan: CEZ:MSM 262200010 Keywords : fluxes * radiation Subject RIV: BL - Plasma and Gas Discharge Physics

  16. Role of ionospheric effects and plasma sheet dynamics in the formation of auroral arcs

    Science.gov (United States)

    Prakash, Manju; Rankin, R.

    2001-01-01

    At the ionospheric level, the substorm onset (expansion phase) is marked by the initial brightening and subsequent breakup of a pre-existing auroral arc. According to the field line resonance (FLR) wave model, the substorm-related auroral arc is caused by the field-aligned current carried by FLRs. The FLRs are standing shear Alfvén wave structures that are excited along the dipole/quasi-dipole lines of the geomagnetic field. The FLRs (that can cause auroral arc) thread from the Earthward edge of the plasma sheet and link the auroral arc to the plasma sheet region of 6-15 R_E. The region is associated with magnetic fluctuations that result from the nonlinear wave-wave interactions of the cross-field current-instability. The instability (excited at the substorm onset) disrupts the cross-tail current which is built up during the growth phase of the substorms and results in magnetic fluctuations. The diversion of the current to polar regions can lead to auroral arc intensification. The current FLR model is based on the amplitude equations that describe the nonlinear space-time evolution of FLRs in the presence of ponderomotive forces exerted by large amplitude FLRs (excited during substorms). The present work will modify the FLR wave model to include the effects arising from magnetic fluctuations that result from current disruption near the plasma sheet (6-15 R_E). The nonlinear evolution of FLRs is coupled with the dynamics of plasma sheet through a momentum exchange term (resulting from magnetic fluctuations due to current disruption) in the generalized Ohm's law. The resulting amplitude equations including the effects arising from magnetic fluctuations can be used to study the structure of the auroral arcs formed during substorms. We have also studied the role of feedback mechanism (in a dipole geometry of the geomagnetic field) in the formation of the discrete auroral arc observed on the nightside magnetosphere. The present nonlinear dispersive model (NDM) is

  17. Plasma flow crisis and limiting electron temperature in a vacuum arc and in axial magnetic field

    International Nuclear Information System (INIS)

    One studied possibility of supersonic motion of cathode plasma in a weak-current vacuum arc placed in axial magnetic field. Increase of electron temperature is shown to result inevitably in reduction of plasma speed up to sonic speed, that is, flow crisis. One derived dependence of the boundary length of plasma stationary flow on magnetic field. The maximum attainable electron temperature of plasma was determined to be governed by ion initial energy and to be equal to the triple value of electron temperature within cathode spot range

  18. Thermal plasma of electric arc discharge in air between composite Cu-C electrodes

    International Nuclear Information System (INIS)

    The complex technique of plasma property studies is suggested. As the first step the radial profiles of temperature and electron density in plasma of free burning electric arc discharge in air between Cu-C composite and brass electrodes, as well as copper electrodes in air flow, were measured by optical emission spectroscopy techniques. As the next step the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. The electron density is obtained from electric conductivity by calculation in assumption of local thermodynamical equilibrium in plasma.

  19. Spectral and Equidensitometry Diagnostics of Electric Arc Plasma

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír; Gross, B.; Protasevich, E. T.

    Tomsk : Izdatelstvo Tomskogo politechnitcheskogo universiteta, 1999, s. 1-130. ISBN 1-89826-44-4 R&D Projects: GA ČR GA102/00/1586 Institutional research plan: CEZ:MSM 262200010 Keywords : optical diagnostics * spectroscopy * plasma Subject RIV: BL - Plasma and Gas Discharge Physics

  20. Radiative heat transfer in cylindrical SF6 arc plasma

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír; Barák, Josef

    Bratislava : JSMF a MFF UK, 1998, s. 19-22 ISBN 80-967454-7-6. [Symposium on Elementary processes and chemical reactions in low temperature plasma /11./. Nízké Tatry (SK), 22.06.1998-26.06.1998] Grant ostatní: ÚT AV(CZ) 11/04 Subject RIV: BL - Plasma and Gas Discharge Physics

  1. Radiative Transport of Energy in SF6 Arc Plasma

    Czech Academy of Sciences Publication Activity Database

    Aubrecht, Vladimír; Protasevich, E. T.

    Tomsk : Izdatelstvo Tomskogo politechnitschekogo universiteta, 1999, s. 1-100 R&D Projects: GA ČR GA102/00/1586; GA AV ČR KSK1076602 Institutional research plan: CEZ:MSM 262200010 Keywords : method of partial characteristics * plasma * radiative heat transfer Subject RIV: BL - Plasma and Gas Discharge Physics

  2. Numerical simulation of a novel non-transferred arc plasma torch operating with nitrogen

    International Nuclear Information System (INIS)

    High power plasma torches with higher electro-thermal efficiency are required for industrial applications. To increase the plasma power and electrothermal efficiency, conventional torches are being modified to operate with molecular gases such as air and nitrogen. Since increasing arc current enhances the heat loss to the anode, torches are being developed to operate under high voltage and low current. The plasma flow dynamics and electromagnetic coupling with plasma flow inside the torch etc. are highly complex and knowledge on the same is required to develop high torches with higher efficiency. Unfortunately detailed experimentation on the same is very difficult. Numerical modeling and simulation is one of the best tools to understand the physics involved in such complex processes. A 2D numerical model is developed to simulate the characteristics of the plasma inside the torch. Though plasma is not in local thermodynamic equilibrium (LTE) close to the electrodes, LTE is assumed everywhere in the plasma to avoid complex and time consuming calculations. Other valid assumptions used in the model are plasma flow is optically thin, laminar and incompressible. Flow, energy and electromagnetic equations are solved with appropriate boundary conditions and volume sources using SIMPLE algorithm with finite volume method. Temperature dependent thermophysical properties of nitrogen are used for the simulations. Simulations are carried out for different experimental conditions. The effects of arc current, gas flow rate of plasma generating gas and sheath gas injected above the bottom anode on the arc voltage, electrothermal efficiency of the torch, plasma temperature and plasma velocity are simulated. Predicted results are compared with experimental results. (author)

  3. Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Vladimír; Hrabovský, Milan

    2011-01-01

    Roč. 31, č. 6 (2011), s. 827-838. ISSN 0272-4324 R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : dc arc jet * plasma jet oscillations * boundary layer instability * frequency spectra Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.602, year: 2011 http://www.springerlink.com/content/v160841757161758/

  4. Experimental study of the effect of gas nature on plasma arc cutting of mild steel

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Mašláni, Alan; Hrabovský, Milan; Křenek, Petr; Stehrer, T.; Pauser, H.

    2013-01-01

    Roč. 46, č. 22 (2013), s. 224011-224011. ISSN 0022-3727 R&D Projects: GA ČR GAP205/11/2070 Institutional support: RVO:61389021 Keywords : Arc cutting * steam plasma cutting * energy balance Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.521, year: 2013 http://iopscience.iop.org/0022-3727/46/22/224011/pdf/0022-3727_46_22_224011.pdf

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

    International Nuclear Information System (INIS)

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

  6. Characterization of a Fabry--Perot interferometer and a dc arc plasma jet for spectrochemical analysis

    International Nuclear Information System (INIS)

    A system involving the use of a Fabry--Perot interferometer in combination with a dc arc plasma jet has been constructed and characterized for spectrochemical analysis. Parameters such as flow rate ratio, observation region, electrode composition and orifice size have been considered. Improvements such as noise reduction and dry aerosol introduction of samples were suggested

  7. Comparison of shear bond strength of orthodontic brackets bonded with halogen and plasma arc light curing

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein IndianJPsychiatry

    2012-01-01

    Conclusion: Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles.

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

    Science.gov (United States)

    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.

  9. Suppression of Instabilities in Thermal Plasma Jet by Additional Arc Current Modulation

    Czech Academy of Sciences Publication Activity Database

    Hlína, Jan; Gruber, Jan; Šonský, Jiří

    2014-01-01

    Roč. 42, č. 10 (2014), s. 2720-2721. ISSN 0093-3813 Institutional support: RVO:61388998 Keywords : arc current modulation * Fourier transform * phase portrait Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.101, year: 2014

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ruzic, David N. [University of Illinois at Urbana-Champaign, IL (United States)

    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.

  12. Vacuum induction melting and vacuum arc remelting of Co-Al-W-X gamma-prime superalloys

    Directory of Open Access Journals (Sweden)

    McDevitt Erin T.

    2014-01-01

    Full Text Available Co-Al-W alloys strengthened with the L12 gamma-prime phase have promise as next generation high temperature materials due to the ability to engineer a high gamma-prime content alloy with a higher gamma-prime solvus and higher melting point than many Ni-base gamma-prime strengthened alloys. Furthermore, these Co-Al-W gamma-prime alloys are interesting as potential cast-and-wrought alloys because they have a relatively narrow range of solidification temperature and large range of temperature between the gamma-prime solvus and the solidus, suggesting than manufacturing via an ingot metallurgy route would be feasible. However, since J. Sato et al discovered gamma-prime in the Co-Al-W alloy system in 2006, the focus in the literature has been on characterizing the structure and properties of these alloys and measuring and assessing the thermodynamics of the alloy system primarily for application as castings for turbine blade applications. To date the author is not aware of any publications describing the microstructure of vacuum induction melted, vacuum arc remelted ingots of a size more than about 2kg. Most work has been performed using small, laboratory-scale, cast-and-hot-rolled samples or samples cast as single crystals. This paper presents ATI's experience in assessing the feasibility of manufacturing a cast-and-wrought billet product in the Co-Al-W-X alloy system. Three 22 kg heats were produced to examine a small range of alloy compositions of potential commercial interest: Co-9Al-9W, Co-9Al-10W-2Ti, and Co-9Al-10W-2Ti-0.02B, respectively. Each heat was vacuum-induction-melted and vacuum-arc-remelted then open-die forged. The ingot microstructure has been characterized. Hot workability during billetizing will be described and microstructure and hardness of hot worked and heat treated product will be presented.

  13. Modeling Multi-Arc Spraying Systems

    Science.gov (United States)

    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.

  14. Application of In-Flight Melting Technology by RF Induction Thermal Plasmas to Glass Production

    International Nuclear Information System (INIS)

    An innovative in-flight glass melting technology with induced thermal plasmas was developed for the purpose of energy conservation and environmental protection. Two-dimensional modeling was used to simulate the thermofluid fields in the plasma torch. The in-flight melting behavior of glass raw material was investigated by various analysis methods. Results showed that the plasma temperature was up to 10000 K with a maximum velocity over 30 m/s, which made it possible to melt the granulated glass raw material within milliseconds. The carbonates in the raw material decomposed completely and the compounds in the raw material attainted 100% vitrification during the in-flight time from the nozzle exit to substrate. The particle melting process is similar to the unreacted-core shrinking model.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

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

    Science.gov (United States)

    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.

  17. Melting of 2D plasma crystals. Wake-mediated mode coupling instability

    International Nuclear Information System (INIS)

    Complete text of publication follows. There are several mechanisms of melting of two-dimensional (2D) plasma crystals. These mechanisms can generally be divided into two categories - generic and plasma-specific. Generic mechanisms are those operating in any (classical) system with a given (conservative) pair interactions between particles (prominent examples are the KTHNY or grain-boundary melting scenarios). Plasmaspecific melting mechanisms, which can only operate in complex plasmas, are associated with the energy exchange between charged microparticles and ambient plasma and can be considered as a result of the system openness. The most universal among the plasma-specific mechanisms is that associated with the wake-mediated interaction between microparticles: In the presence of strong plasma flow the screening cloud around each charged grain becomes highly asymmetric (along the flow, these clouds are usually referred to as plasma wakes) and starts playing the role of a 'third body' in the interparticle interaction, making it nonreciprocal. This provides effective conversion of the energy of flowing ions into the kinetic energy of microparticles. The theory of mode-coupling instability provides comprehensive picture of a plasma-specific melting scenario. It predicts a number of distinct fingerprints to be observed upon the instability onset, such as the emergence of a new hybrid mode, a critical angular dependence, a mixed polarization, and distinct thresholds. In this talk we summarize the key features of the instability and present their detailed discussion and comparison with experiments and numerical simulations.

  18. Vacuum arc anode phenomena

    International Nuclear Information System (INIS)

    A brief review of anode phenomena in vacuum arcs is presented. Discussed in succession are: the transition of the arc into the anode spot mode; the temperature of the anode before, during and after the anode spot forms; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the anode material and is a copious source of vapor and energetic ions. The dominant mechanism controlling the transition of the vacuum arc into the anode spot mode appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum arc being considered. Either magnetic constriction in the gap plasma or gross anode melting can trigger the transition; indeed, a combination of the two is a common cause of anode spot formation

  19. Dynamics of melting and crystallization of monocrystal silicon under exposure to compressed plasma fluxes

    International Nuclear Information System (INIS)

    The melting and crystallization of single-crystal silicon wafers exposed to compression plasma flows generated by quasi-stationary plasma accelerators are studied by numerical simulation. The results include the phase transition kinetics described on the basis of the Kolmogorov equation. The space-time characteristics of the melting and crystallization processes for variously shaped plasma pulses are discussed. Based on the experimental data and estimates, it is concluded that thermoelectric instability plays an essential role in the formation of three-dimensional periodic structures

  20. Ceramic plasma-sprayed coating of melting crucibles for casting metal fuel slugs

    International Nuclear Information System (INIS)

    Thermal cycling and melt reaction studies of ceramic coatings plasma-sprayed on Nb substrates were carried out to evaluate the performance of barrier coatings for metallic fuel casting applications. Thermal cycling tests of the ceramic plasma-sprayed coatings to 1450 °C showed that HfN, TiC, ZrC, and Y2O3 coating had good cycling characteristics with few interconnected cracks even after 20 cycles. Interaction studies by 1550 °C melt dipping tests of the plasma-sprayed coatings also indicated that HfN and Y2O3 do not form significant reaction layer between U–20 wt.% Zr melt and the coating layer. Plasma-sprayed Y2O3 coating exhibited the most promising characteristics among HfN, TiC, ZrC, and Y2O3 coating

  1. Spectroscopic investigation of vacuum-arc anode plasmas for thin film deposition

    International Nuclear Information System (INIS)

    A vacuum-arc plasma source has been designed and tested for fabrication of thin films, which are clear of droplets. In order to avoid these droplets, the source has been designed to produce pulsed plasmas generated by the anode, and to screen the substrate against the plasma streaming away from the cathode spot. We present here spectroscopic measurements and analyses carried out in order to characterize the electron population of this anode plasma. The vacuum arc was first operated with a carbon anode of diameter 0.5 mm and an arc current of 192 A. The visible and near-infrared spectra were recorded with various resolutions, in direct view of the anode spot, with an intensified CCD camera. Dominant C+ and C2+ lines were identified and the plasma parameters deduced from their relative intensities showed that local thermal equilibrium was reached, giving an electron temperature about 3.2 eV and an electron density around 2.5x1017 cm-3. The study was extended to lower currents of 140, 92 and 65 A. The temperature and the density monotonically decreased down to about 2 eV and 1.5x1015 cm-3

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

    Science.gov (United States)

    Nayak, B. B.

    2012-01-01

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

  3. Experimental and theoretical studies of recombination ionization and diffusion processes in an arc plasma

    International Nuclear Information System (INIS)

    We have experimentally determined the changes of the electron density and excited atom density in a wall-stabilized arc burning in argon at atmospheric pressure; we have deduced the changes of electronic temperature, and the difference between electronic temperature and gas temperature. Whe have found these parameters by means of two wavelengths laser interferometry and spectroscopy measurements. By means of collisional radiatif model, we have found ionization and recombination coefficients. Knowing electronic density profiles, we have determined the different plasma parameters and analysed the electronic energy losses using our model. Whe have studied the electronic loss processes during the early stages of arc extinction

  4. The biological effect of arc discharge plasma combined with gradual magnetic field on tomato seeds

    International Nuclear Information System (INIS)

    Using arc discharge plasma combined with gradual magnetic field to treat seeds is a new plasma biological technology. The biological effect and drought resistance of tomato seeds treated with different plasma parameters were compared. The increasing of proline content indicates that the drought resistance of tomato seedlings could be increased due to reduction of penetration potential of plant cell. Increased SOD, POD activity, root activity and ATP content show that water stress could be alleviated by eliminating the free radicle and increasing metabolism. (authors)

  5. Azo-dye Orange II degradation in plasma torch with Gerdien Arc

    Czech Academy of Sciences Publication Activity Database

    Hlína, Michal; Domlátil, J.; Brožek, V.; Hrabovský, Milan

    2010-01-01

    Roč. 14, 1-2 (2010), s. 89-94. ISSN 1093-3611. [European High Temperature Plasma Processes (HTPP)/10th./. Patras (Patras University), 07.07.2008-11.07.2008] R&D Projects: GA ČR GA202/08/1084 Institutional research plan: CEZ:AV0Z20430508 Keywords : Orange II * degradation * plasma * Gerdien arc * radiation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.189, year: 2010 http://www.begellhouse.com/journals/57d172397126f956,227c67f42b79464a,42cd14bc4e885ce6.html

  6. Aspects of plasma arc cutting process in the AISI 321 type stainless steel

    International Nuclear Information System (INIS)

    Some aspects of plasma arc cutting process in the AISI321 stainless steel, used in nuclear industry, are analysed. The maximum values of the velocity of cutting and, the minimum quantity of energy per unit of length necesary for the plasma were determined. The localization of irregularities in the cut surface in function of the velocity of cutting was investigated. The cut surfaces were evaluated by surface roughness, using as measurement parameter, the distance between the sharpest salience and the deepest reentrance of the sample profile. The width of layer from thermal action of the plasma was influenced by the velocity of cutting. (Author)

  7. Plasma source ion implantation of metal ions: Synchronization of cathodic-arc plasma production and target bias pulses

    International Nuclear Information System (INIS)

    An erbium cathodic-arc has been installed on a Plasma Source Ion Implantation (PSII) experiment to allow the implantation of erbium metal and the growth of adherent erbia (erbium oxide) films on a variety of substrates. Operation of the PSII pulser and the cathodic-arc are synchronized to achieve pure implantation, rather than the hybrid implantation/deposition being investigated in other laboratories. The relative phase of the 20 μs PSII and cathodic-arc pulses can to adjusted to tailor the energy distribution of implanted ions and suppress the initial high-current drain on the pulse modulator. The authors present experimental data on this effect and make a comparison to results from particle-in-cell simulations

  8. Dismantling of JPDR reactor internals by underwater plasma arc cutting technique using robotic manipulator

    International Nuclear Information System (INIS)

    The actual dismantling of JPDR started on December 4, 1986. As of now, equipment that surrounds the reactor has mostly been removed to provide working space in reactor containment prior to the dismantling of reactor internals. Some reactor internals have been successfully dismantled using the underwater arc cutting system with a robotic manipulator during the period of January to March 1988. The cutting system is composed of an underwater plasma arc cutting device and a robotic manipulator. The cut off reactor internals were core spray block, feedwater sparger and stabilizers for fuel upper grid tube. The plasma arc cutting device was developed to dismantle the reactor internals underwater. It mainly consists of a plasma torch, power and gas supply systems for the torch, and by-product treatment systems. It has the cutting ability of 130 mm thickness stainless steel underwater. The robotic manipulator has seven degrees of freedom of movement, enabling it to move in almost the same way as the arm of a human being. The arm of the robot is mounted on a supporting device which is suspended by three chains from the support structure set on a service floor. A plasma torch is griped by the robotic hand; its position to the structure to be cut is controlled from a remote control room, about 100 meters outside the reactor containment

  9. Vacuum arc velocity and erosion rate measurements on nanostructured plasma and HVOF spray coatings

    International Nuclear Information System (INIS)

    Arc velocity and erosion rate measurements were performed on nanostructured pure Cu cathodes in 10-5 Torr vacuum (1.3324 m Pa), in an external magnetic field of 0.04 T. Five different kinds of nanostructured cathodes were produced by spraying pure Cu powders of three different sizes, on Cu coupons by atmospheric pressure plasma spraying and high velocity oxygen fuel spraying techniques. The erosion rates of these electrodes were obtained by measuring the weight loss of the electrode after igniting as many as 135 arc pulses, each of which was 500 μs long at an arc current of 125 A. The arc erosion values measured on three kinds of nanostructured coatings were 50% lower than the conventional pure massive Cu cathodes. Microscopic analyses of the arc traces on these nanostructured coatings show that the craters formed on these coatings were smaller than those formed on conventional Cu (<1 μm in diameter compared with 7-12 μm diameter on conventional Cu). It was concluded that nanostructured cathodes had lower erosion rates than conventional pure Cu cathodes

  10. Numerical study of arc plasmas and weld pools for GTAW with applied axial magnetic fields

    International Nuclear Information System (INIS)

    A 3D numerical model containing the welding arc and the weld pool for gas tungsten arc welding (GTAW) with applied axial magnetic fields is established. The model is validated by comparing the calculated arc temperature with the measured ones. The influence of the magnetic field on the welding process is studied by changing the magnetic inductions, from 0 T to 0.06 T. For welding arcs, a radial spread is discovered, and a reverse flow appears over the anode. The distribution of temperature, heat flux, current density and pressure on the anode surface becomes double-peaked, while the voltage distributes in a double-valley type. For weld pools, the fluid flow cycle brings about a wide and shallow pool. In the circumferential direction, the fluid in the centre areas rotates in an opposite direction to that in the outer regions; in the axial direction, the fluid flows upwards at the centre while downwards in the edge area of the weld pool. All the driving forces including the surface tension, the shear stress from the arc plasma, the electromagnetic force and the buoyancy force that influence the fluid flow are analysed to explain these phenomena. The mechanism of how the applied axial magnetic field regulates the GTAW process is thus clarified. (paper)

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

    International Nuclear Information System (INIS)

    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

  12. Sheared magnetospheric plasma flows and discrete auroral arcs: a quasi-static coupling model

    Directory of Open Access Journals (Sweden)

    M. M. Echim

    2007-02-01

    Full Text Available We consider sheared flows in magnetospheric boundary layers of tangential discontinuity type, forming a structure that is embedded in a large-scale convergent perpendicular electric field. We construct a kinetic model that couples the magnetospheric structure with the topside ionosphere. The contribution of magnetospheric electrons and ionospheric electrons and ions is taken into account into the current-voltage relationship derived for an electric potential monotonically decreasing with the altitude. The solution of the current continuity equation gives the distribution of the ionospheric potential consistent with the given magnetospheric electric potential. The model shows that a sheared magnetospheric flow generates current sheets corresponding to upward field-aligned currents, field-aligned potential drops and narrow bands of precipitating energy, as in discrete auroral arcs. Higher velocity magnetospheric sheared flows have the tendency to produce brighter and slightly broader arcs. An increase in arc luminosity is also associated with enhancements of magnetospheric plasma density, in which case the structures are narrower. Finally, the model predicts that an increase of the electron temperature of the magnetospheric flowing plasma corresponds to slightly wider arcs but does not modify their luminosity.

  13. Metal-gas reactions in arc plasma spraying of Ag, Cu, Ni, Ti, TiC, W, Zn, and Zr

    International Nuclear Information System (INIS)

    Powders of Ag, Cu, Ni, Ti, TiC, W, Zn, and Zr were arc sprayed with the plasma gas mixtures Ar + 30% He, Ar + 10% N2, and Ar + 10% vol.% H2 in a closed chamber containing the same atmosphere and in air and the extents of gas-metal reaction were determined by X-ray analyses. Spraying in the Ar-N2 and Ar-H2 mixtures led to some N2 and H2 uptake by Ti and Zr coatings and to some reduction of oxygen impurity in the Cu, W, Zn, and probably, Ni coatings. Coatings sprayed in air contained appreciable amounts of the respective impurity phases Cu2O, NiO, TiN, TiO2, Ti(C,N), β-W, possibly ZnO, ZrN, and ZrO2. Samples of sprayed products collected at different distances show that metal-gas reactions occurring with the powder particles in flight is often a minor source of contamination compared to that stemming from gas uptake by the coating after the metal is deposited. Deviations from the Engelke difficulty of melting parameter occurs when a sufficiently intense chemical reaction takes place between the metal particles and the plasma gases. (orig.)

  14. Microstructural analyses of intermetallic TiAl(Nb)-compounds prepared by arc melting and by powder metallurgy

    International Nuclear Information System (INIS)

    Intermetallic compounds based on TiAl with Nb or V as alloying additions prepared by powder metallurgy (P/M) and arc melting (A/M) techniques have been investigated with respect to their potential as new high temperature materials. All the alloys with nominal Al-concentrations 34-36 wt% contain two phases, γ-TiAl and α2-Ti3Al, but significant differences in the distribution of γ and α2 were found between the P/M and A/M materials. The role of impurities during processing and the microstructural stability in the planned service temperature range 700-10000C are discussed. In the P/M TiAl alloys two carbide precipitates have been found, which are the cubic Perovskite-AlTi3C phase in the γ-matrix and the hexagonal H-AlTi2 (C, N) phase at grain boundaries. At high temperatures the AlTi3C phase dissolves and is replaced by more stable H-phase, and therefore no longer contributes to the high temperature strength of the material. Mechanical properties of both the P/M and A/M alloys are compared in association with the processing methods and the resulting microstructures. (orig.) With 71 figs., 22 tabs

  15. Diagnostics of plasma arc during the process of remelting of surface layer in 40Cr4 steel

    Directory of Open Access Journals (Sweden)

    Z. Nitkiewicz

    2007-06-01

    Full Text Available Purpose: The purpose of this work is to propose a research method for diagnostics and determination of temperature and shape of plasma arc used for surface treatment of 40Cr4 steel with TiO2 coating.Design/methodology/approach: The surfaces of samples, previously coated with ceramic coating, have been remelted with plasma arc. For investigations of arc shape the high-resolution modern visible light camera and thermovision camera have been used.Findings: The temperature distribution in plasma arc with percentage quantity of temperature fields has been determined. The arc limiting profiles with isotherms have also been determined.Research limitations/implications: Further research is aimed to assign the identified spatial points of the arc with the appropriate values of temperature.Practical implications: Selection of remelting parameters is performed by trial and error method, which is time-consuming and expensive. In-depth recognition of parameters, which characterise the source, will be useful in creation of the method of fast prognosis of parameters for the used source with the effects of remelting.Originality/value: The diagnostics of plasma arc which consists in estimation of the temperature and the shape of the arc by means of high-resolution visible light camera and the thermovision camera.

  16. The theoretical evaluation of powders transportation in plasma transferred-arc space under coaxial powder feeding condition

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The powders transportation in the plasma transferred-arc space during the coaxial powder-feeding surface depositing process was theoretical evaluated. The axial acceleration and velocity of various particles in the arc column were described. According to the results from theoretical calculations, it was found that: (1) The powder's transporting velocity is much lower than the plasma fluid's; (2) The powders axial transporting velocity presents "valley-shape distribution" along plasma arc column traverse section when surfacing current is greater than 100(¨)A. When the arc current exceeding 100(¨)A, the powders coming through the center field of arc column will transport slower than the powder through the outer-around field of arc column. It is in the field where the temperature is in the range of 9(¨)000(¨)K~11(¨)000(¨)K that the particles can achieve its maximum axial acceleration in the argon plasma space. (3) For the given powder mass density, the smaller its size is, the greater its acceleration and the greater its averaged transporting velocity will be in the arc space; (4) For the given powder size, the greater its mass density is, the smaller its acceleration and averaged velocity will be in the arc space.

  17. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    International Nuclear Information System (INIS)

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying

  18. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baldenebro-Lopez, F.J. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Herrera-Ramírez, J.M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Arredondo-Rea, S.P. [Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Gómez-Esparza, C.D. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico)

    2015-09-15

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

  19. Double plasma arc in a graphite tube - application of discharge atmospheres

    International Nuclear Information System (INIS)

    With a view to safety and economic efficiency element-specific limits are required for permissible impurities in reactor graphite. This leads to the necessity of developing suitable methods of analysis. Emission spectroscopy has proved to be a method of analysis featuring a high detection capability and offering the possibility of determining several elements simultaneously. A prolongation of the particle residence time in the plasma (and, thus, an increase in radiation intensity) was the objective when developing a novel spectrochemical source of excitation. The method uses two d.c. arcs burning in a horizontally arranged graphite tube. The double plasma arc in a graphite tube has proved to be an excellent source of excitation for the analysis of powder and solutions. (orig./IHOE)

  20. In-situ weld-alloying plasma arc welding of SiCp/Al MMC

    Institute of Scientific and Technical Information of China (English)

    LEI Yu-cheng; YUAN Wei-jin; CHEN Xi-zhang; ZHU Fei; CHENG Xiao-nong

    2007-01-01

    Plasma arc welding was used to join SiCp/Al composite with titanium as alloying filler material. Microstructure of the weld was characterized by an optical microscope. The results show that the harmful needle-like phase Al4C3 is completely eliminated in the weld of SiCp/Al metal matrix composite(MMC) by in-situ weld-alloying/plasma arc welding with titanium as the alloying element. The wetting property between reinforced phase and Al matrix is improved, a stable weld puddle is gotten and a novel composite-material welded joint reinforced by TiN, AlN and TiC is produced. And the tensile-strength and malleability of the welded joints are improved effectively because of the use of titanium.

  1. Operation reliability of plasma arc-welded joints for NPP pipings

    International Nuclear Information System (INIS)

    A technology has been developed of plasma-arc welding joints of pipe of steel 12Kh18N10T to replace the factory welding technology using the electrodes EA-400/10 t. It is established that the decisive influence of the formation and microcontinuity of the welded joint is produced by satisfying the optimum values of current and welding rate. Deviation from these values results in nonpenetrations and burnings. A study has been made of the welded joint strength properties at temperatures of 20, 200, 350 deg C and low-cycle fatigue at 350 deg C. The joints made by plasma-arc welding are shown to have higher cyclic strength and resistance to brittle fracture than those made by the former technology

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

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gu-Ling; YANG Si-Ze; WANG Jiu-Li; WU Xing-Fang; FENG Wen-Ran; CHEN Guang-Liang; GU Wei-Chao; NIU Er-Wu; FAN Song-Hua; LIU Chi-Zi

    2006-01-01

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

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

    Science.gov (United States)

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

    2006-05-01

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

  4. Investigation of Mixing of Plasma Species in the Hybrid-Stabilized Argon-Water Electric Arc

    Czech Academy of Sciences Publication Activity Database

    Jeništa, Jiří; Takana, H.; Uehara, S.; Nishiyama, H.; Hrabovský, Milan

    Sendai: Tohoku University, 2014, s. 52-53. ISSN 1344-2236. [International Symposium on Advanced Fluid Information (AFI 2014)/14./. Sendai (JP), 08.10.2014-10.10.2014] Institutional support: RVO:61389021 Keywords : hybrid-stabilized electric arc * combined diffusion coefficients * partial characteristics * Large-eddy simulation * the Smagorinsky sub-grid scale model Subject RIV: BL - Plasma and Gas Discharge Physics

  5. Origin of primitive ultra-calcic arc melts at crustal conditions - Experimental evidence on the La Sommata basalt, Vulcano, Aeolian Islands

    Science.gov (United States)

    Lanzo, Giovanni; Di Carlo, Ida; Pichavant, Michel; Rotolo, Silvio G.; Scaillet, Bruno

    2016-07-01

    To interpret primitive magma compositions in the Aeolian arc and contribute to a better experimental characterization of ultra-calcic arc melts, equilibrium phase relations have been determined experimentally for the La Sommata basalt (Som-1, Vulcano, Aeolian arc). Som-1 (Na2O + K2O = 4.46 wt.%, CaO = 12.97 wt.%, MgO = 8.78 wt.%, CaO/Al2O3 = 1.03) is a reference primitive ne-normative arc basalt with a strong ultra-calcic affinity. The experiments have been performed between 44 and 154 MPa, 1050 and 1150 °C and from NNO + 0.2 to NNO + 1.9. Fluid-present conditions were imposed with H2O-CO2 mixtures yielding melt H2O concentrations from 0.7 to 3.5 wt.%. Phases encountered include clinopyroxene, olivine, plagioclase and Fe-oxide. Clinopyroxene is slightly earlier than olivine in the crystallization sequence. It is the liquidus phase at 150 MPa, being joined by olivine on the liquidus between 44 and 88 MPa. Plagioclase is the third phase to appear in the crystallization sequence and orthopyroxene was not found. Experimental clinopyroxenes (Fs7-16) and olivines (Fo78-92) partially reproduce the natural phenocryst compositions (respectively Fs5-7 and Fo87-91). Upon progressive crystallization, experimental liquids shift towards higher SiO2 (up to ~ 55 wt.%), Al2O3 (up to ~ 18 wt.%) and K2O (up to ~ 5.5 wt.%) and lower CaO, MgO and CaO/Al2O3. Experimental glasses and natural whole-rock compositions overlap, indicating that progressive crystallization of Som-1 type melts can generate differentiated compositions such as those encountered at Vulcano. The low pressure cotectic experimental glasses reproduce glass inclusions in La Sommata clinopyroxene but contrast with glass inclusions in olivine which preserve basaltic melts more primitive than Som-1. Phase relations for the La Sommata basalt are identical in all critical aspects to those obtained previously on a synthetic ultra-calcic arc composition. In particular, clinopyroxene + olivine co-saturation occurs at very low

  6. Numerical Analysis of the Arc Plasma in a Simplified Low-voltage Circuit Breaker Chamber with Ferromagnetic Materials

    Institute of Scientific and Technical Information of China (English)

    Wu Yi; Rong Mingzhe; Yang Qian; Hu Guangxia

    2005-01-01

    This paper is devoted to the simulation of the arc plasma in a simplified low-voltage circuit breaker chamber. Based on a group of coupled governing equations, a three-dimensional (3-D) arc plasma model is built and solved by a modified commercial code. Firstly, this paper presents a solution of the stationary state of the arc plasma and discusses the distribution of some parameters throughout the chamber. Secondly, with the ferromagnetic materials included,the balance of the stationary state is broken and a transient course is calculated. In light of the simulation results, the temperature distribution sequence, the arc motion and the plasma jet are then described and analyzed in detail.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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.

  9. Role of substrate temperature at graphene synthesis in arc discharge

    CERN Document Server

    Fang, Xiuqi; Keidar, Michael

    2015-01-01

    Substrate temperature required for synthesis of graphene in arc discharge plasma was studied. It was shown that increase of the copper substrate temperature up to melting point leads to increase in the amount of graphene production and quality of graphene sheets. Favorable range of substrate temperatures for arc-based graphene synthesis was determined in relatively narrow range of about 1340-1360K which is near the melting point of copper.

  10. Generation of tonalitic and dioritic magmas by coupled partial melting of gabbroic and metasedimentary rocks within the deep crust of the famatinian magmatic Arc, Argentina

    OpenAIRE

    Juan E. Otamendi; Mihai N. Ducea; Alina M Tibaldi; Bergantz, Geoerge W.; Rosa Díaz, Jesús de la; Graciela I Vujovich

    2009-01-01

    The source regions of dioritic and tonalitic magmas have been identified in a deep crustal section of the Famatinian arc (Sierras Pampeanas of western Argentina). The source zones of intermediate igneous rocks are located at the transition between a gabbro-dominated mafic unit and a tonalite-dominated intermediate unit. In the upper levels of the mafic unit mafic magmas intruded into metasedimentary wall-rocks, crystallized mainly as amphibole gabbronorite and caused the partial melting of th...

  11. Wall-stabilised plasma arc applied to the determination of rare earth elements in phosphate samples

    International Nuclear Information System (INIS)

    A wall-stabilised plasma arc seeded with potassium chloride has been used as an excitation source for the spectrographic determination of rare earth elements in samples of phosphate deposits. The samples were treated with a mixture of HNO3 and HF in a Teflon decomposition vessel and then with H2SO4. The effect of the sample matrix on the excitation temperatures in the plasma and on the analytical curves obtained was studied. The results from the analysis of 12 samples, collected from the Abu Tartur plateau, Western Desert, Egypt, are given. The normalised rare earth patterns reveal a marine environment for deposition. (author)

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

    Science.gov (United States)

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

    2013-01-01

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

  13. Contribution to immersed arc plasma study: applications to organic aqueous effluent decontamination and gasification

    International Nuclear Information System (INIS)

    This work is concerned with decontamination and gasification of aqueous organic liquid waste by immersed thermal plasma technology. In this concept, the organic compounds are decomposed into gas by high temperature plasma. A quench of about 107-108 K/s, is obtained by immersion into a given effluent. Two kinds of arc plasma are studied. The first one is an immersed electrical arc stricken between two graphite electrodes. The second one is a plasma jet generated by a non-transferred plasma torch. For dilute liquid waste (1 g/L) containing molecules incompatible with conventional biological processes, the hydroxyl radicals (OH0) are continuously produced by the plasma jet directly into the solution allowing complete molecule mineralization into carbon dioxide and water. The hetero-atoms, if present, are converted into solvated ions. The decomposition of the molecules, such as chloro-phenols and aniline, are studied. Considering the identified intermediate products, a reaction mechanism is proposed. For each tested molecules, their concentration decreased at least of 90 percent. Based on the 'gasosiphon' phenomenon, the experimental reactor insures the simultaneous recirculation of both gas and liquid phases. The hydrodynamic was studied using in situ high frequency imaging technology. A CFD code was applied for numerical simulation of the observed recirculation phenomena. The results were compared with obtained experimental data. In the case of concentrated liquid waste (≥ 100 g/L), syngas was produced by thermal cracking of organic molecules. The best measured composition of the gas is about 45% v/v of H2 and 45 % v/v of CO when an electrical arc is used. The usability of both studied plasma types were investigated in this field. The experimental study was carried on using fructose and glucose solution (several hundreds g/L) as surrogated effluent. With a specific injection method, gasification rate is about 30 % with one way. Optical Emission Spectroscopy and

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

    Energy Technology Data Exchange (ETDEWEB)

    Davydenko, V. I., E-mail: V.I.Davydenko@inp.nsk.su; Ivanov, A. A., E-mail: A.A.Ivanov@inp.nsk.su; Shul’zhenko, G. I. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    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.

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

    Science.gov (United States)

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

    2015-11-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, O.M. Jr.

    1980-11-01

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

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

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas;

    2015-01-01

    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......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...

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Martins, D R; Verdonck, P; Brown, I G

    2002-01-01

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

  3. Plasma electrolytic treatment of products after selective laser melting

    Science.gov (United States)

    Kashapov, L. N.; Kashapov, N. F.; Kashapov, R. N.; Denisov, D. G.

    2016-01-01

    The aim of the work was to study the possibilities of plasma electrolytic treatment for cleaning surfaces of metal products obtained by the SLM-technology. We found that the most effective cleaning from the large alloy particles occurs in the "hydrodynamic" mode, when the occurrence of hydrodynamic pulses observed. Further smoothing of irregularities eliminated by a stable burning of discharge in vapor shell. Analysis the morphology of the surface of difficult specialized products, such as crown conical gears, after plasma hydrodynamic treatment showed efficiency and advantages in comparison to conventional methods of final cleaning such as shot blasting.

  4. Steam Plasma Flows Generated in Gerdien Arc: Environment for Energy Gas Production from Organics and for Surface Coatings

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan

    2011-01-01

    Roč. 6, č. 5 (2011), s. 792-801. ISSN 1880-5558. [Seventh International Conference on Flow Dynamics. Sendai, 01.11.2010-03.11.2010] R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : Thermal Plasma * Dc Arc Plasma Torch * Gerdien Arc * Plasma Gasification Subject RIV: BL - Plasma and Gas Discharge Physics http://www.jstage.jst.go.jp/article/jfst/6/5/792/_pdf

  5. Plasma arc cutting: Microstructural modifications of hafnium cathodes during first cycles

    International Nuclear Information System (INIS)

    In the present work, the microstructural modifications of the Hf insert in plasma arc cutting (PAC) electrodes operating at 250 A were experimentally investigated during first cycles, in order to understand those phenomena occurring on and under the Hf emissive surface and involved in the electrode erosion process. Standard electrodes were subjected to an increasing number of cutting cycles (CCs) on mild steel plates in realistic operative conditions, with oxygen/air as plasma/shield gas. Microstructural analysis was performed for each electrode at different erosion stages by means of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and Raman spectroscopy. Electrodes cross sections were also observed by means of optical microscopy (both in bright field and in reflected polarised light) after chemical etching. In the insert, three typical zones were found after cutting: monoclinic HfO2 layer; thermally-modified transition zone with O2–Hf solid solution; unmodified Hf. The erosion cavity and the oxide layer thickness increase with the number of cutting cycles. Macrocracking was observed in the oxide layer, while microcracking and grain growth were detected in the remelted Hf. Moreover, detachment was found at the Hf/Cu interface. Based on thermodynamics and kinetics of the Hf high temperature oxidation, conclusions can be drawn on the erosion mechanism involved. - Highlights: ► Hf microstructural modifications in cathodes after plasma arc cutting cycles investigated. ► 3 zones identified after cutting: HfO2 layer; remelted zone with O2–Hf solid solution; unmodified Hf. ► Hf-based ejections both in arc-on and arc-off phases; erosion cavity deepens with cutting cycles. ► Detachment at the Hf/Cu interfaces, worsening heat dissipation and oxidation/erosion phenomena. ► The use of a different current ramp at subsequent erosion stages is suggested.

  6. Destruction of tributylphosphate by cold plasma. Use of a gliding arc reactor

    International Nuclear Information System (INIS)

    The nuclear industry uses the Purex process for reprocessing spent nuclear fuel by plutonium and uranium separation. This process uses complexing properties of tributylphosphate. This solvent is aged by the high radioactivity and acidity of the medium and loses its extracting properties. Thus it becomes an highly radioactive liquid organic waste and it must be degraded before its conditioning. We have elaborated a new method for mineralizing TBP by exposure to the plasma produced by a wet air gliding arc. Electric discharges in wet air give rise to very reactive species like excited molecules and radicals. Such species can accelerate oxidation and degradation of organic compounds. The gliding arc discharge is obtained by applying high voltage between two divergent metal electrodes disposed around a blowing nozzle. The arc formed between the electrodes is blown by the air flow with growing in length. Thus a quenched wet air plasma trail is formed and licks an upper layer of TBP while the lower layer is water. Our device can degrade almost 40 percent of the treated TBP. The main degradation product is phosphoric acid for which we have monitored the production kinetics and suggested a model of a surface oxidation process to explain it. Another part of the TBP is converted into a phosphate layer found on the electrodes and phosphorus oxide white smokes present in exhaust fumes. By means of chromatography and spectroscopic analysis we have found the dibutyl-phosphoric acid as the main partial degradation product. The gliding arc device presents several advantages towards other plasma processes which are a low cost and especially for the present task i.e. an easy building and use, operating at atmospheric pressure and moderate temperature, and the possibility to use high powers (several kW for one unit). (author)

  7. Mechanism of plasma-arc formation of fullerenes from coal and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Pang, L.S.K.; Wilson, M.A.; Quezada, R.A. [CSIRO Petroleum, North Ryde (Australia)] [and others

    1995-12-31

    When an arc is struck across graphite or coal electrodes in a helium atmosphere several products are formed including soot containing fullerenes. The mechanism by which fullerenes and nanotubes are formed is not understood. At arc temperatures exceeding 3000{degrees}C, highly ordered fullerenes might be expected to be less stable than graphite, and hence fullerene production is believed to proceed in cooler regions at the edge of the arc. There is irrefutable evidence that [C{sub 60}]-fullerene grows in a plasma from atomic carbon vapour or equivalent. When {sup 13}C-labelled carbon powder is packed into the anode, the fullerenes as produced contain a statistical distribution of {sup 13}C atoms. This implies that graphite has split into small units, predominantly C{sub 1} or C{sub 2} in the plasma and these units are involved in fullerene formation. When coal or other organic materials are used in the anode, weaker bonds are present, which may break preferentially. As a result, larger fragments, other than C{sub 1} and C{sub 2} units can exist in the plasma. This paper demonstrates the existence of such larger fragments when various coals are used and this implies that fullerenes can be formed from larger units than C{sub 1} and C{sub 2}. The distribution of polycyclic hydrocarbons formed depends very much on the structure of the coal used for the arcing experiments. The distribution of the natural abundance of {sup 13}C/{sup 12}C ratios in the fullerene products further supports this evidence.

  8. Development of Energy Efficient, Multi-Channel, Pulsed Plasma Generator for High-Speed Flow Control by Localized Arc Filament Plasma Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The research team at The Ohio State University has been developing technologies to suppress jet noise using localized arc filament plasma actuators and are in the...

  9. Interaction between laser-induced plasma/vapor and arc plasma during fiber laser-MIG hybrid welding

    International Nuclear Information System (INIS)

    Hybrid plasma is an important physical phenomenon in fiber laser-MIG hybrid welding. It greatly affects the stability of the process, the quality of the weld, and the efficiency of energy coupling. In this paper, clear and direct proofs of these characteristics are presented through high-speed video images. Spectroscopic analysis is used to describe the characterization of hybrid plasma. The hybrid plasma forms a curved channel between the welding wire and the keyhole during the fiber laser-MIG hybrid welding process. The curved channel is composed of two parts. The laser-induced plasma/vapor expands due to the combined effect of the laser and the MIG arc, forming an ionization duct, which is one part of the curved channel. The resistance of the duct is smaller than that of other locations because of the rise in electrical conductivity. Consequently, the electrical arc is guided through the duct to the surface of the material, which is the other part of the curved channel. The spectral intensities of metal elements in laser-MIG hybrid welding are much stronger than those in MIGonly welding, whereas the spectral intensities of shielding gas element in laser-MIG hybrid welding are much weaker

  10. Surface modification of air plasma spraying WC-12%Co cermet coating by laser melting technique

    Science.gov (United States)

    Afzal, M.; Ajmal, M.; Nusair Khan, A.; Hussain, A.; Akhter, R.

    2014-03-01

    Tungsten carbide cermet powder with 12%Co was deposited on stainless steel substrate by air plasma spraying method. Two types of coatings were produced i.e. thick (430 µm) and thin (260 µm) with varying porosity and splat morphology. The coated samples were treated with CO2 laser under the shroud of inert atmosphere. A series of experimentation was done in this regard, to optimize the laser parameters. The plasma sprayed coated surfaces were then laser treated on the same parameters. After laser melting the treated surfaces were characterized and compared with as-sprayed surfaces. It was observed that the thickness of the sprayed coatings affected the melt depth and the achieved microstructures. It was noted that phases like Co3W3C, Co3W9C4 and W were formed during the laser melting in both samples. The increase in hardness was attributed to the formation of these phases.

  11. Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted Al{sub x}CoCrFeNi high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Jithin, E-mail: jithin@deakin.edu.au [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia); Jarvis, Tom; Wu, Xinhua [Monash Centre for Additive Manufacturing, Monash University, Clayton 3168 (Australia); Stanford, Nicole; Hodgson, Peter; Fabijanic, Daniel Mark [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia)

    2015-05-01

    High entropy alloys (HEA) are a relatively new metal alloy system that have promising potential in high temperature applications. These multi-component alloys are typically produced by arc-melting, requiring several remelts to achieve chemical homogeneity. Direct laser fabrication (DLF) is a rapid prototyping technique, which produces complex components from alloy powder by selectively melting micron-sized powder in successive layers. However, studies of the fabrication of complex alloys from simple elemental powder blends are sparse. In this study, DLF was employed to fabricate bulk samples of three alloys based on the Al{sub x}CoCrFeNi HEA system, where x was 0.3, 0.6 and 0.85 M fraction of Al. This produced FCC, FCC/BCC and BCC crystal structures, respectively. Corresponding alloys were also produced by arc-melting, and all microstructures were characterised and compared longitudinal and transverse to the build/solidification direction by x-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy (EDX and EBSD). Strong similarities were observed between the single phase FCC and BCC alloys produced by both techniques, however the FCC/BCC structures differed significantly. This has been attributed to a difference in the solidification rate and thermal gradient in the melt pool between the two different techniques. Room temperature compression testing showed very similar mechanical behaviour and properties for the two different processing routes. DLF was concluded to be a successful technique to manufacture bulk HEA's.

  12. Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted AlxCoCrFeNi high entropy alloys

    International Nuclear Information System (INIS)

    High entropy alloys (HEA) are a relatively new metal alloy system that have promising potential in high temperature applications. These multi-component alloys are typically produced by arc-melting, requiring several remelts to achieve chemical homogeneity. Direct laser fabrication (DLF) is a rapid prototyping technique, which produces complex components from alloy powder by selectively melting micron-sized powder in successive layers. However, studies of the fabrication of complex alloys from simple elemental powder blends are sparse. In this study, DLF was employed to fabricate bulk samples of three alloys based on the AlxCoCrFeNi HEA system, where x was 0.3, 0.6 and 0.85 M fraction of Al. This produced FCC, FCC/BCC and BCC crystal structures, respectively. Corresponding alloys were also produced by arc-melting, and all microstructures were characterised and compared longitudinal and transverse to the build/solidification direction by x-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy (EDX and EBSD). Strong similarities were observed between the single phase FCC and BCC alloys produced by both techniques, however the FCC/BCC structures differed significantly. This has been attributed to a difference in the solidification rate and thermal gradient in the melt pool between the two different techniques. Room temperature compression testing showed very similar mechanical behaviour and properties for the two different processing routes. DLF was concluded to be a successful technique to manufacture bulk HEA's

  13. The influence of the arc plasma treatment on the structure and microhardness C120U carbon tool steel

    Directory of Open Access Journals (Sweden)

    W. Bochnowski

    2010-01-01

    Full Text Available paper. They are compared with the properties obtained after conventional hardening. The GTAW (Gas Tungsten Arc Welding method was used. The remelted zone consists of dendritic cells and columnar crystals. Inside the columnar crystals dependent to current arc plasma intensity the martensite or lower bainite was observed. The cooling rate of the remelted zone is similar to the cooling rate obtained in the classical heat treatment. The maximum hardness 650 HV0,1 was measured in material after treatment with a smaller current intensity of arc plasma – 60A. Increases of the current intensity of arc plasma from 60 A to 110 A (for fixed speed rate of source lead to increases the depth of the remelted zone from 1,2 to 3,1 mm. Thickness of the heat affected zone in the all specimens was similar (1,9 to 2,1 mm.

  14. Measurements of secondary emissions from plasma arc and laser cutting in standard experiments

    International Nuclear Information System (INIS)

    As part of an inter-facility comparison of secondary emissions from plasma arc and laser-cutting techniques, standard cutting tests have been done by plasma arc underwater and in air, and by laser beam in air. The same team was commissioned to measure the secondary emissions (solid and gaseous) in each contractor's facility with the same measuring rig. 20 mm and 40 mm thick, grade 304 stainless-steel plates were cut by plasma-torch in three different facilities: Heriot Watt University of Edinburgh, Institut fuer Werkstoffkunde of Universitaet Hannover and CEA/CEN Cadarache. 10 mm and in some cases 20 mm thick, grade 304, stainless-steel plates were cut by laser beam in five different facilities: CEA-CEN Fontenay, CEA-CEN Saclay, Institut fuer Werkstoffkunde of Universitaet Hannover and ENEA/Frascati. The results obtained in the standard experiments are rather similar, and the differences that appear can be explained by the various scales of the involved facilities (semi-industrial and laboratory) and by some particularities in the cutting parameters (an additional secondary gas flow of oxygen in plasma cutting at Universitaet Hannover, for example)

  15. Properties of Coatings Deposited Using a Filtered Vacuum Arc Carbon Plasma Source

    International Nuclear Information System (INIS)

    A filtered vacuum arc plasma source with an adjustable cathode-anode gap was used to produce a carbon plasma for deposition of coatings on various substrates. The deposition apparatus consisted of a plasma gun, a toroidal plasma duct, a deposition chamber, and a cooled substrate holder. The plasma gun consisted of a cylindrical graphite cathode, an annular graphite anode, and a mechanism providing axial movement of the cathode to the anode. The arc was ignited in vacuum by momentarily contacting the cathode with the anode, while applying a D.C. current of 100 A between the cathode and the anode, and then withdrawing the cathode away from the anode in the axial direction, forming a cathode-anode gap of 12 mm. A carbon plasma jet passed through the anode into the toroidal duct and then to the substrate. The substrates were stainless steel and polycarbonate coupons, glass slides, and glass and polycarbonate substrates with a SnO2 coating. It was shown that the structure of the coatings deposited on stainless steel substrates depended on the negative bias voltage (Vbias) applied to the substrate. With Vbias=0, the coatings were not adherent, at Vbias =-10 V the coatings were porous, but the pore density decreased with increasing negative Vbias. At Vbias =-20-25 V the adhesion of the coating was good, and dense, hard (HV-34-60 GPa) DLC coatings were formed. At Vbias 235 V, the formation of graphite phase was observed whose area increased with increasing Vbias. Coatings deposited on polycarbonate surfaces were adherent without applying bias. However, the substrate surface was damaged due to heat flux to the substrate produced by the plasma, after a deposition duration which depended on the magnetic field strength

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

    Science.gov (United States)

    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.

  17. Hybrid (plasma + gas tungsten arc) weldability of modified 12% Cr ferritic stainless steel

    International Nuclear Information System (INIS)

    This paper deals with the hybrid (plasma + gas tungsten arc) welding properties of 12 mm thick modified 12% Cr ferritic stainless steel complying with EN 1.4003 and UNS S41003 steels with a carbon content of 0.01% to improve the weldability. The root passes of the butt welds were produced with plasma arc welding (PAW) without filler metal while gas tungsten arc welding (GTAW) was used to accomplish filler passes with 309 and 316 austenitic stainless steel type of consumables, respectively. The joints were subjected to tensile and bend tests as well as Charpy impact toughness testing at -20 oC, 0 oC and 20 oC. Examinations were carried out in terms of metallography, chemical analysis of the weld metal, ferrite content, grain size and hardness analyses. Although 309 consumables provided higher mean weld metal toughness values compared to 316 (90 J vs. 75 J), 316 type of consumables provided better mean HAZ toughness data for the joints (45 J vs. 20 J) at -20 oC. Toughness properties of the welds correspond with those of microstructural features including grain size and ferrite content.

  18. Ion spectra of vacuum arc plasma with compound and alloy cathodes

    International Nuclear Information System (INIS)

    We have carried out an experimental investigation of the charge state distribution of ions produced in the vacuum arc plasma for the case when the cathode is a compound or alloy. The plasma was generated in a metal vapor vacuum arc ion source, and the charge state spectra were measured using a time-of-flight method. We have compared these spectra to the spectra obtained from cathodes of the constituent elements. The cathode materials used and reported on here were the following groups: SiC/Si/C [i.e., we have compared the spectra obtained using a cathode of silicon carbide with the spectra obtained using (a) a silicon cathode and (b) a carbon cathode], TiC/TiN/TiO2/Ti/C, WC/W/C, (UC-ZrC)/UN/U/Zr/C, brass/Cu/Zn, and stainless steel/Fe/Cr/Ni. The arc current employed throughout was approximately 100 A. We find that the charge state distributions change depending on the elemental composition of the alloy or compound of which the cathode is fabricated

  19. Fatigue cracking of hybrid plasma gas metal arc welded 2205 duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Yurtisik, Koray; Tirkes, Suha [Middle East Technical Univ., Ankara (Turkey). Welding Technology and Nondestructive Testing Research/Application Center

    2014-10-01

    Contrary to other keyhole welding applications on duplex stainless steels, a proper cooling time and a dilution were achieved during hybrid plasma gas metal arc welding that provided sufficient reconstructive transformation of austenite without sacrificing its high efficiency and productivity. Simultaneous utilization of keyhole and metal deposition in the hybrid welding procedure enabled us to get an as-welded 11 mm-thick standard duplex stainless steel plate in a single pass. Metallographic examination on hybrid plasma-gas metal arc weldments revealed only primary austenite in ferrite matrix, whereas in addition to reconstructive transformation of primary austenite during solidification, secondary austenite was also transformed in a displacive manner due to successive thermal cycles during multi-pass gas metal arc welding. On the one hand, secondary austenite provided barriers and retarded the crack propagation during the tests in laboratory air. On the other hand, chromium and molybdenum depletion in the neighborhood of secondary austenite precipitates yielded relatively high crack propagation rates in multi-pass weldments under chloride attack.

  20. Fatigue cracking of hybrid plasma gas metal arc welded 2205 duplex stainless steel

    International Nuclear Information System (INIS)

    Contrary to other keyhole welding applications on duplex stainless steels, a proper cooling time and a dilution were achieved during hybrid plasma gas metal arc welding that provided sufficient reconstructive transformation of austenite without sacrificing its high efficiency and productivity. Simultaneous utilization of keyhole and metal deposition in the hybrid welding procedure enabled us to get an as-welded 11 mm-thick standard duplex stainless steel plate in a single pass. Metallographic examination on hybrid plasma-gas metal arc weldments revealed only primary austenite in ferrite matrix, whereas in addition to reconstructive transformation of primary austenite during solidification, secondary austenite was also transformed in a displacive manner due to successive thermal cycles during multi-pass gas metal arc welding. On the one hand, secondary austenite provided barriers and retarded the crack propagation during the tests in laboratory air. On the other hand, chromium and molybdenum depletion in the neighborhood of secondary austenite precipitates yielded relatively high crack propagation rates in multi-pass weldments under chloride attack.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ehiasarian, A P [Materials Research Institute, Sheffield Hallam University, Howard St., Sheffield, S1 1WB (United Kingdom); Hovsepian, P Eh [Materials Research Institute, Sheffield Hallam University, Howard St., Sheffield, S1 1WB (United Kingdom); New, R [Materials Research Institute, Sheffield Hallam University, Howard St., Sheffield, S1 1WB (United Kingdom); Valter, J [HVM Plasma Ltd, Na Hutmance 2, Prague 5, 158 00 (Czech Republic)

    2004-08-07

    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{sup -2} depending on the magnetic field shape. The magnetic field strongly influenced the relative optical emission from Cr{sup 0}, Cr{sup 1+} and Cr{sup 2+} 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.

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

    Science.gov (United States)

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

    2015-11-01

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

  4. Destruction of acenaphthene, fluorene, anthracene and pyrene by a dc gliding arc plasma reactor

    International Nuclear Information System (INIS)

    In this study, four kinds of PAHs (polycyclic aromatic hydrocarbons) i.e. acenaphthene, fluorene, anthracene and pyrene are used as targets for investigation of PAHs treatment process assisted by dc gliding arc discharge. The effects of carrier gas and external resistance on the PAHs decomposition process are discussed. The results indicate that the destruction rate can be achieved to the highest with the carrier gas of oxygen and the external resistance of 50 kΩ independent of type of PAHs. Furthermore, experimental results suggest that destruction energy efficiency of gliding arc plasma would be improved by treating higher concentration pollutants. Based on the analysis of experimental results, possible destruction mechanisms in different gas discharge are discussed.

  5. Contribution to the 3D time-dependent modeling of the arc dynamic behavior in a DC plasma spray torch

    International Nuclear Information System (INIS)

    This work is devoted to the tri-dimensional time-dependent modeling of the arc behavior in a plasma spray torch. It has been carried out in the fame of a collaboration with the Thermal Spray Laboratory of CEA-DAM, Le Ripault and the laboratory of Fluid Mechanics and Heat Transfers of EDF. After a summary of the operation modes of a DC plasma torch and the effect of anode erosion on the torch working, the structure of an electric arc is depicted as well as the main models of non-transferred electric arcs proposed in the literature. This review allows the determination of the main assumption and boundary conditions for a 'realistic' model of the electric arc. Then, the equations, assumptions and boundary conditions of the model we have developed are presented and, the CFD code ESTET 3.4 used to solve the model equations. The model is based on a specific value of the local electric field to predict the breakdown of the arc while its re-striking is favored by a hot gas column at the spot where the highest value of the electric field is calculated. This model gives a realistic prediction of the time-dependent arc behavior according to the plasma-forming gas nature and of the temperature and velocity of the gas flow at the nozzle exit. However, it overestimates the torch voltage and dimensions of the anode arc root attachment spot. (author)

  6. Numerical study on iron particles behaviour injected in an argon plasma from an electric transferred arc

    Energy Technology Data Exchange (ETDEWEB)

    Douce, A.; Flour, I.

    1995-11-01

    In the scope of the Research and Development Project `Control of Plasma/Product Interaction`, the aim of this study is to analyze the behaviour of iron particles injected in an argon plasma flow from an electric transferred arc. It includes particle trajectories and, heat and mass transfer (as the particle undergoes smelting and evaporation), using a 3 dimensional Lagrangian simulation with the numerical code ESTET. The plasma flow is a result of a calculation done using Melodie, a 2 dimensional axisymmetrical software, in the scope of a modelling bath heating with plasma transferred arc. The first step consists of an analysis on the forces applied to a single particle. Simulations show that equation of motion would reduce, finally, to the sum of the drag force and the gravitational effects. In a second step, special attention is given to the effect of steep temperature gradients (across the boundary layer around the particle) on the evaluation of the plasma properties, the drag coefficient, and the heat and mass transfer coefficients. The comparison of several correlations show that the definition of the mean temperature mainly controls the calculation of plasma properties across the boundary layer around the particle.At least, several particle injection conditions are tested on four different sizes particles (50, 100, 150 et 200{mu}m), showing that the 200 {mu}m particle is the only one falling into the bath, without being completely evaporated. However, taking into account the `blow-up effect`, induced by evaporation, leads to a decrease of the heat transfer coefficient which slow down the evaporation, and then modify the conclusion made before. (authors). 18 refs., 41 figs., 5 tabs., 4 appends.

  7. Oxygen-Plasma-Treated Indium-Tin-Oxide Films on Nonalkali Glass Deposited by Super Density Arc Plasma Ion Plating

    Science.gov (United States)

    Kim, Soo Young; Hong, Kihyon; Son, Jun Ho; Jung, Gwan Ho; Lee, Jong-Lam; Choi, Kyu Han; Song, Kyu Ho; Ahn, Kyung Chul

    2008-02-01

    The effects of O2 plasma treatment on both the chemical composition and work function of an indium-tin-oxide (ITO) film were investigated. ITO films were deposited on non-alkali glass substrate by super density arc plasma ion plating for application in active-matrix organic light-emitting diodes (OLEDs). The water contact angle decreased from 38 to 11° as the ITO films were treated with O2 plasma for 60 s at a plasma power of 150 W, indicating an increase in the hydrophilicity of the surface. It was found that there were no distinct changes in the microstructure or electrical properties of the ITO films with O2 plasma treatment. Synchrotron radiation photoemission spectroscopy data revealed that O2 plasma treatment decreased the amount of carbon contamination and increased the number of unscreened states of In3+ and (O2)2- peroxo species. This played the role of increasing the work function of the ITO films by 1.7 eV. As a result, the turn-on voltage of the OLED decreased markedly from 24 to 8 V and the maximum luminance value of the OLED increased to 2500 cd/m2.

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

    Science.gov (United States)

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

    2016-05-01

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

  9. Controlled-atmosphere plasma arc for emission spectrography of nonmetal elements

    Energy Technology Data Exchange (ETDEWEB)

    Heemstra, R.J.

    1970-01-01

    To estimate the weight percents of certain nonmetal elements in organic compounds found in petroleum reservoirs, the Bureau of Mines designed and constructed a controlled-atmosphere plasma arc which effectively excludes air from the plasma. Selected organic compounds that contained nonmetal elements were mixed with a solvent essentially free of those elements. The weight percents of the nonmetal elements were estimated from the produced diatomic spectral bands; results were reasonably accurate. Analytical working curves were prepared for nitrogen in the range from 15 to 450 ..mu..g for 100 mg samples using the analytical carbon-nitrogen band at 3883 A and the internal standard carbon--carbon band at 3607 A. Curves also were prepared for hydrogen, sulfur, and oxygen that had limited sensitivity to detection. Another indicated application of this plasma arc is for characterization of high-boiling petroleum fractions in liquid chromatographic effluents. The rates at which diatomic species are produced and destroyed directly influence the intensity of each corresponding band spectrum.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  13. Carbon Nanostructures Production by AC Arc Discharge Plasma Process at Atmospheric Pressure

    OpenAIRE

    Shenqiang Zhao; Ruoyu Hong; Zhi Luo; Haifeng Lu; Biao Yan

    2011-01-01

    Carbon nanostructures have received much attention for a wide range of applications. In this paper, we produced carbon nanostructures by decomposition of benzene using AC arc discharge plasma process at atmospheric pressure. Discharge was carried out at a voltage of 380 V, with a current of 6 A–20 A. The products were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), and Raman spectra. The results sho...

  14. Synthesis of Cubic Chromium Nitride Nanocrystals Powders by Arc Discharge Plasma Method

    OpenAIRE

    SHEN Long-Hai,CUI Qi-Liang

    2010-01-01

    Cubic CrN nanoparticles with the size less than 10 nm were synthesized through direct reaction of metal Cr with N2 by arc discharge plasma method. The products synthesized under different nitrogen gas pressure were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FT-IR). The effect of N2 pressure and accession of NH3 on the formation of cubic phase CrN were studied. The results indicate that it is beneficial for the conve...

  15. Production and Characterization of ZnO Coatings Using a Pulsed Arc Plasma

    International Nuclear Information System (INIS)

    We had used a pulsed arc plasma to produce ZnO coatings on glass substrates to obtain special electric properties. To find the best condition of pressure for these films, we had varied the pressure between 1.8 to 2.2 mb. The films obtained are characterized using AFM (Atomic Force Microscopy) and OES (Optical Emission Spectroscopy. Moreover, the resistivity was measured using the I-V curve. Then, we can observe the behavior of the coating resistivity with little changes in the pressure. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Environmental application research and future plans in plasma arc technology at the georgia institute of technology

    International Nuclear Information System (INIS)

    This paper summarizes the facilities and past, current, and future research efforts at the georgia institute of technology plasma Arc research facility established in 1992. This research facility was established specifically to develop and test applications related to waste management and various remediation concepts. The results of research programs in the vitrification of asbestos materials, municipal incinerator ash, and in situ testing programs, including soil remediation, waste to energy research, landfill remediation and capacity management. The presentation will also include conference and symposium announcements and invitations. 9 tabs

  18. Evolution of transiently melt damaged tungsten under ITER-relevant divertor plasma heat loading

    Energy Technology Data Exchange (ETDEWEB)

    Bardin, S., E-mail: s.bardin@differ.nl [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); Morgan, T.W. [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); Glad, X. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-les-Nancy (France); Pitts, R.A. [ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France); De Temmerman, G. [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Ass EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein (Netherlands); ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France)

    2015-08-15

    A high-repetition-rate ELM simulation system was used at both the Pilot-PSI and Magnum-PSI linear plasma devices to investigate the nature of W damage under multiple shallow melt events and the subsequent surface evolution under ITER relevant plasma fluence and high ELM number. First, repetitive shallow melting of two W monoblocks separated by a 0.5 mm gap was obtained by combined pulsed/steady-state hydrogen plasma loading at normal incidence in the Pilot-PSI device. Surface modifications including melting, cracking and strong net-reshaping of the surface are obtained. During the second step, the pre-damaged W sample was exposed to a high flux plasma regime in the Magnum-PSI device with a grazing angle of 35°. SEM analysis indicates no measurable change to the surface state after the exposure in Magnum-PSI. An increase in transient-induced temperature rise of 40% is however observed, indicating a degradation of thermal properties over time.

  19. Incineration/vitrification of radioactive wastes and combustion of pyrolysis gases in thermal plasmas; Incineration/vitrification de dechets radioactifs et combustion de gaz de pyrolyse en plasma d`arc

    Energy Technology Data Exchange (ETDEWEB)

    Girold, Ch. [CEA de la Vallee du Rhone, Departement de Retraitement des Dechets et du Demantelemnet, 30 - Marcoule (France)]|[Limoges Univ., 87 (France)

    1997-03-01

    Two thermal plasma processes used for incineration of radioactive technological wastes (cellulose, plastics, rubber...) have been investigated. First, the different types of radioactive wastes are presented, with a special attention to those which may benefit from a high temperature thermal treatment. The most significant thermal plasma processes, suitable for this goal, are described. Then, the author deals with the post-combustion, in an oxygen plasma jet reactor, of gases from burnable radioactive waste pyrolysis. An experimental planning method as been used to evaluate the combustion performances in the reactor, with a wide range of gas composition and running parameters such as oxygen excess and electrical power. The results of a modeling of kinetics, based on 116 chemicals reactions between 25 species, are compared with experimental values. Finally, an oxygen plasma reactor where the arc is transferred on a basalt melt is experimented. The efficiency of the combustion and the homogeneity of the glass are discussed. The volatility of some glass elements and tracers added to the wastes is also approached in two different ways: by post-trial material balance and by an optical emission spectroscopic method. The author built a diagnostic method that allows the following versus time of the metallic vapours above the melt. (author) 51 refs.

  20. Model and powder particle heating, melting, resolidification, and evaporation in plasma spraying processes

    International Nuclear Information System (INIS)

    A comprehensive model is developed to study the heating, melting, evaporation, and resolidification of powder particles in plasma flames. The well-established LAVA code for plasma flame simulation is used to predict the plasma gas field under given power plasma flame simulation is used to predict the plasma gas field under given power conditions, and provide inputs to the particle model. The particle is assumed to be a spherical and one-dimensional heat conduction equation with phase change within the particle is solved numerically using an appropriate coordinate transformation and finite difference method. Melting, vaporization, and resolidification interfaces are tracked and the particle vaporization is accounted for by the mass diffusion of vapor through the boundary layer around the particle. The effect of mass transfer on convective heat transfer is also included. Calculations have been carried out for a single particle injected into an Ar-H2 plasma jet. Zirconia and nickel are selected as solid particles because of their widespread industrial applications as well as significant differences in their thermal properties. Numerical results show strong nonisothermal effect of heating, especially for materials with low thermal conductivity, such as zirconia. The model also predicts strong evaporation of the material at high temperatures

  1. Geologic Map and Eruptive History of Veniaminof Volcano Record Aleutian Arc Processing of Mantle-Derived Melts

    Science.gov (United States)

    Bacon, C. R.; Sisson, T. W.; Calvert, A. T.; Nye, C. J.

    2009-12-01

    Mount Veniaminof, one of the largest volcanoes in the Aleutian arc, has a basal diameter of ~40 km, a volume of ~350 km3, an 8-km-diameter ice-filled caldera, and an active intracaldera cone. The geology of this tholeiitic basalt-to-dacite volcano has been mapped at 1:50,000 scale. Over 100 Quaternary volcanic map units are characterized by 600 chemical analyses of rocks and nearly 100 40Ar/39Ar and K-Ar ages. Throughout its history, lava flows from Veniaminof recorded alternately ice/melt-water chilling or ice-free conditions that are consistent with independent paleoclimatic records. Exposures from deep glacial valleys to the caldera rim reveal a long history dominated by basalt and basaltic andesite from ≥260 ka to 150 ka that includes compositions as primitive as 9.4% MgO and 130 ppm Ni at 50% SiO2. Basaltic andesite, common throughout Veniaminof's history, has low compatible-element contents that indicate an origin by fractionation of basaltic magma. Repeated eruption of more differentiated melts from a shallow intrusive complex, represented by granodiorite (crystallized dacitic magma) and cumulate gabbro and diorite xenoliths in pyroclastic deposits, has featured virtually aphyric andesite since 150 ka and dacite (to 69.5% SiO2) beginning ~110 ka. These variably differentiated liquids segregated from crystal mush, possibly by gas-driven filter pressing, and commonly vented but also solidified at depth. A large composite cone was present at least as early as 200 ka. Although asymmetric edifice morphology hints at early sector collapse to the southeast, coeval vents on northwest and southeast flanks and the distribution of extensive lava units indicate that a large cone (again) was present by 120 ka. Flank eruption of a wide variety of Veniaminof magmas was common from plate-convergence-parallel northwest-trending fissures from at least as early as ca. 80 ka. At 56 ka and at 46 ka, voluminous dacite lava erupted on both northwest and southeast flanks. A

  2. Numerical simulation for arc-plasma dynamics during contact opening process in electrical circuit-breakers

    Science.gov (United States)

    Gupta, D. N.; Patil, G. N.; Srinivas, D.; Kale, S. S.; Potnis, S. B.

    2010-02-01

    The high-energy, high-current thermal plasma that develops between electric contacts in a gas circuit-breaker during circuit interruption is an important phenomenon in the power transmission industry. The high temperature and pressure arc dissipates the tremendous amount of energy generated by the fault current. Simultaneously, this energy has to be transferred away from the contacts to build the dielectric strength level of the circuit-breaker. In order to interrupt the current, the arc must be weakened and finally extinguished. We model these phenomena by using a computer software code based on the solution of the unsteady Euler equations of gas dynamics. We consider the equations of fluid flows. These equations are solved numerically in complex circuit breaker geometries using a finite-volume method. The domain is initially filled with SF6 gas. We begin our simulations from cold mode, where the fault current is not present (hence no arc). An axis-symmetric geometry of a 145 kV gas circuit-breaker is considered to study the pressure, density, and temperature profile during contact opening process.

  3. Ti Coating on Magnesium Alloy by Arc-Added Glow Discharge Plasma Penetrating Technique

    Institute of Scientific and Technical Information of China (English)

    CUICai-e; MIAOQiang; PANJun-de; ZHANGPing-ze; ZHANGGao-hui

    2004-01-01

    Arc-added glow discharge plasma penetrating technique is a new surface coating method. With the help of vacuum arc discharge, a cold cathode arc source continually emits ion beams of coating elements with high currency density and high ionizing ratio. As the ion bombard and diffusion working on, the surface of the parts form deposited layer, penetrated layer and hybrid layer. Under lab condition, a commercial magnesium alloy Az91 had been coated with Ti film layer with the aim of improving its' anti-corrosion performance. This paper mainly summarized our studies on the testing and analyzing of the coating layer. The composition and microstructure of the coating layer had been analyzed by means of X-ray diffraction (XRD) and glow discharge spectrum (GDS), and the surface appearance had been surveyed by scanning electronic microscope (SEM). The adhesion strength between film and matrix had been evaluated by experiments of sticking-tearing. The results indicated that the coated layer on magnesium alloy were homogeneous, dense and robustly adhered.

  4. Numerical simulation for arc-plasma dynamics during contact opening process in electrical circuit-breakers

    International Nuclear Information System (INIS)

    The high-energy, high-current thermal plasma that develops between electric contacts in a gas circuit-breaker during circuit interruption is an important phenomenon in the power transmission industry. The high temperature and pressure arc dissipates the tremendous amount of energy generated by the fault current. Simultaneously, this energy has to be transferred away from the contacts to build the dielectric strength level of the circuit-breaker. In order to interrupt the current, the arc must be weakened and finally extinguished. We model these phenomena by using a computer software code based on the solution of the unsteady Euler equations of gas dynamics. We consider the equations of fluid flows. These equations are solved numerically in complex circuit breaker geometries using a finite-volume method. The domain is initially filled with SF6 gas. We begin our simulations from cold mode, where the fault current is not present (hence no arc). An axis-symmetric geometry of a 145 kV gas circuit-breaker is considered to study the pressure, density, and temperature profile during contact opening process.

  5. Investigation on the shockwave induced by surface arc plasma in quiescent air

    International Nuclear Information System (INIS)

    The shockwave induced by surface direct-current (DC) arc discharge is investigated both experimentally and numerically. In the experiment, the shockwave generated by rapid gas heating is clearly observed from Schlieren images. The peak velocity of the shockwave is measured to be over 410 m/s; during its upright movement, it gradually falls to about 340 m/s; no remarkable difference is seen after changing the discharge voltage and the pulse frequency. In the modeling of the arc plasma, the arc domain is not simulated as a boundary condition with fixed temperature or pressure, but a source term with a time-varying input power density, which could better reflect the influence of the heating process. It is found that with a reference power density of 2.8×1012 W/m3, the calculated peak velocity is higher than the measured one, but they quickly (in 30 μs) become agreed with each other. The peak velocity also rises while increasing the power density, the maximum velocity acquired in the simulation is over 468 m/s, which is expected to be effective for high speed flow control

  6. Test Plan: Phase 1 demonstration of 3-phase electric arc melting furnace technology for vitrifying high-sodium content low-level radioactive liquid wastes

    International Nuclear Information System (INIS)

    This document provides a test plan for the conduct of electric arc vitrification testing by a vendor in support of the Hanford Tank Waste Remediation System (TWRS) Low-Level Waste (LLW) Vitrification Program. The vendor providing this test plan and conducting the work detailed within it [one of seven selected for glass melter testing under Purchase Order MMI-SVV-384216] is the US Bureau of Mines, Department of the Interior, Albany Research Center, Albany, Oregon. This test plan is for Phase I activities described in the above Purchase Order. Test conduct includes feed preparation activities and melting of glass with Hanford LLW Double-Shell Slurry Feed waste simulant in a 3-phase electric arc (carbon electrode) furnace

  7. Test Plan: Phase 1 demonstration of 3-phase electric arc melting furnace technology for vitrifying high-sodium content low-level radioactive liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Eaton, W.C. [ed.

    1995-05-31

    This document provides a test plan for the conduct of electric arc vitrification testing by a vendor in support of the Hanford Tank Waste Remediation System (TWRS) Low-Level Waste (LLW) Vitrification Program. The vendor providing this test plan and conducting the work detailed within it [one of seven selected for glass melter testing under Purchase Order MMI-SVV-384216] is the US Bureau of Mines, Department of the Interior, Albany Research Center, Albany, Oregon. This test plan is for Phase I activities described in the above Purchase Order. Test conduct includes feed preparation activities and melting of glass with Hanford LLW Double-Shell Slurry Feed waste simulant in a 3-phase electric arc (carbon electrode) furnace.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. Geochemical Evidence from the Kohistan Complex for Differentiation of Garnet Granulitic lower Crust in Island Arcs by Dehydration Melting of Amphibole-bearing Plutonics: Implications for the Andesite Model of Continental Crustal Growth

    Science.gov (United States)

    Garrido, C. J.; Bodinier, J.; Burg, J.; Zeilinger, G.; Hussain, S. S.; Dawood, H.; Gervilla, F.

    2005-12-01

    We report a geochemical study of the Jijal and Sarangar complexes constituting the lower crust of the Mesozoic Kohistan paleo-island arc (N. Pakistan). The Jijal complex is composed of basal peridotites topped by a gabbroic section made up of mafic garnet granulite-with minor lenses of garnet hornblendite and granite-grading up section to hornblende gabbronorite. The Sarangar complex is constituted by metagabbro. Sarangar gabbro and Jijal hornblende gabbronorite have melt-like, LREE-enriched REE patterns similar to those of island arc basalts. These rocks and Jijal garnet granulite define altogether negative covariations of LaN, YbN and (La/Sm)N with Eu* (=2xEuN/SmN+GdN; N= chondrite normalized), and positive covariations of (Yb/Gd)N with Eu*. REE modeling indicates that these covariations cannot be accounted for by high-pressure crystal fractionation of hydrous primitive or derivative andesites. They are consistent with formation of garnet granulites as plagioclase-garnet assemblages with variable trapped melt fractions via either high-pressure crystallization of primitive island arc basalts or dehydration melting of hornblende gabbronorite, providing that the amount of segregated or restitic garnet was low (hornblende gabbronorite. Similarly, Jijal garnet-bearing hornblendite lenses were most likely generated by coeval dehydration melting of hornblendites. Furthermore, melting models and geochronological data point to intrusive leucogranites in the overlying Metaplutonic complex as the melts generated by dehydration melting of the plutonic protoliths of Jijal garnet-bearing restites. Consistently with the metamorphic evolution of the Kohistan lower arc crust, dehydration melting occurred at the mature stage of this island arc when shallower hornblende-bearing plutonics were buried to depth exceeding 25-30 km and heated at temperatures above ca. 900 oC. Available experimental data on dehydration melting of amphibolitic sources imply that thickening of oceanic arcs

  11. Vaporization behavior of Cs in plasma melting of low level radioactive solid wastes

    International Nuclear Information System (INIS)

    In order to apply thermal plasma melting method to treatment of low level miscellaneous solid wastes, it is essential to understand effects of treatment conditions on the migration rate of Cs to the molten slag because Cs is an important nuclide for evaluating radioactivity in the waste before disposal. It was found in our previous studies that the effect of the waste composition on the migration rate of Cs could be evaluated by using basicity under the same heating condition. To establish a method for evaluating the effect of the melting conditions such as waste mass and heating power on the migration rate of Cs, the vaporization behavior of Cs is discussed by measuring the temporal change of molten bath form and concentration of Cs in the molten slag. The temporal change of concentration of Cs in the molten slag was expressed by a first-order type reaction rate formula when the samples were melted completely. The concentration of Cs in the molten slag were calculated from the rate constant and the result of temporal change of the molten slag form using the rate formula established from the molten bath formation model in a batch melting process. The calculated values were in good agreement with the experimental results. We found that the migration rate of Cs to the slag layers depends on the vaporization rate constant of Cs and the melting rate of the waste components forming slag. This result suggests that the effect of the melting conditions such as amount of inorganic waste materials and heating power on the migration rate of Cs to the slag layer can be evaluated by using the melting rate of the waste components forming slag. (author)

  12. Mathematical modeling of municipal solid waste plasma gasification in a fixed-bed melting reactor

    OpenAIRE

    Zhang, Qinglin

    2011-01-01

    The increasing yield of municipal solid waste (MSW) is one of the main by-products of modern society. Among various MSW treatment methods, plasma gasification in a fixed-bed melting reactor (PGM) is a new technology, which may provide an efficient and environmental friendly solution for problems related to MSW disposals. General objectives of this work are to develop mathematical models for the PGM process, and using these models to analyze the characteristics of this new technology. In this ...

  13. Combined plasma spray and in situ laser melting treatment of NiCrBSi powder

    OpenAIRE

    Serres, Nicolas; Hlawka, Françoise; Costil, Sophie; Langlade, Cécile; Machi, Frédérique; Cornet, Alain

    2010-01-01

    Recently, mechanical industry has been affected by many environmental regulations. For example, hexavalent chromium was prohibited due to its toxicity. Thus it is essential to find new coatings which are able to replace hard chromium plating. In this paper a technique, based on the association between APS (Atmospheric Plasma Spray) and laser melting using a 3kW diode laser is described. This process allows the production of denser coatings with finer structures than as-sprayed coatings. Depen...

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

    Science.gov (United States)

    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.

  15. Cladding nuclear steels - the application of plasma-arc hot wire surfacing

    International Nuclear Information System (INIS)

    The effect of one and two layer plasma-arc hot wire cladding on the HAZ microstructure of the fine grained structural steel 22 NiMoCr 3 7, which is similar to ASTM A 508, class 2, and steel 20 MnMoNi 5 5, similar to ASTM A 533, grade B, class 1 is determined. Attention is directed particularly to the behaviour of the susceptible region, and the consumables considered are cladding materials X 2 CrNiNb 19 9, similar to ER 347 Elc, and S-NiCr 20 Nb, similar to ER NiCr-3 (Inconel 82). Results of corrosion resistance tests show that this cladding technique can be recommended for manufacture of equipment for the chemical industry to avoid corrosion failure. Plasma-arc hot wire surfacing is also shown to be capable of depositing single or double clad layers to meet the highest safety requirements and could be applied to nuclear power plants for the special manufacture of wear resistant parts and for protection of equipment subject to a variety of corrosive environments. (U.K.)

  16. Modification of a metallic surface in a vacuum arc discharge plasma using thermally stimulated ion diffusion

    Science.gov (United States)

    Muboyadzhyan, S. A.

    2008-12-01

    A new process for modifying a metallic surface in a vacuum arc discharge plasma using thermally stimulated ion diffusion is considered. The effect of the bias voltage (negative substrate potential) on the processes that occur on the surface of a treated part is studied when the substrate material interacts with an accelerated metallic-ion flow. The phase and elemental compositions of the modified layer are studied for substrates made of nickel-based superalloys, austenitic and martensitic steels, and titanium-based alloys. The heat resistance, the salt corrosion resistance, and the corrosion cracking resistance of steels and titanium-based alloys are investigated after their modification in vacuum arc plasmas of pure metals (Ti, Zr, Al, Cr, Y) and related alloys. The surface modification caused by the thermally stimulated ion saturation of the surfaces of parts made from structural materials is shown to change the structural-phase states of their surfaces and, correspondingly, the properties of these materials in relation to the state of the surface.

  17. Application of low-temperature plasma generators for intensification of melting processes in induction furnaces

    International Nuclear Information System (INIS)

    Industrial plasmatrons are prospective heat sources for metallurgy. Especially when used for additional metal heating in induction furnaces, they could bring a substantial enhancement of the heating rate and acceleration of the melting processes. To determine the optimum metal heating conditions and to develop the method of calculating the parameters of plasma-induction furnaces, an experimental plasmatron (metallurgical plasma jet) was constructed and tested on a special calorimetric stand. The results are reported of studies of the dependence of heating efficiency on the plasmatron characteristics. (J.U.). 6 figs., 2 tabs., 6 refs

  18. Prompt response and durability of polymer ablation from synthetic fibers irradiated by thermal plasmas for arc resistant clothes

    International Nuclear Information System (INIS)

    Interactions between thermal plasmas and synthetic fibers such as polyamide, polyester, phenol and aramid were investigated by thermal plasma irradiation technique. Understanding the above interactions is crucial to design effective flame retardant synthetic fiber clothes with arc resistance to protect a human from arc flash accidents. To investigate the interactions, an Ar inductively coupled thermal plasma (ICTP) was used instead of the arc discharge because the ICTP has high controllability and no contamination. The ICTP irradiation raises polymer ablation in case of polyamide and polyester. Two features of the polymer ablation such as prompt response and durability were fundamentally investigated from viewpoint of shielding the heat flux. It was found that polyamide fiber has both a high prompt response and a long durability.

  19. Analysis of surface roughness and surface heat affected zone of steel S355J0 after plasma arc cutting

    International Nuclear Information System (INIS)

    This paper deals with thermal cutting technology of materials with plasma arc. In the first part of this paper the theoretical knowledge of the principles of plasma arc cutting and current use of this technology in industry are presented. The cut of products with this technology is perpendicular and accurate, but the use of this technology affects micro-structural changes and depth of the heat affected zone (HAZ). This article deals with the experimental evaluation of plasma arc cutting technological process. The influence of technological factors on the roughness parameter Ra of the steel surface EN S355J0 has been evaluated by using planned experiments. By using the factor experiment, the significance of the four process factors such as plasma burner feed speed, plasma gas pressure, nozzle diameter, distance between nozzle mouth and material has been analyzed. Regression models obtained by multiple linear regression indicate the quality level of observed factors function. The heat from plasma arc cutting affects the micro-structural changes of the material, too.

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

    CERN Document Server

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

    2001-01-01

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

  1. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  2. The investigation of an electric arc in the long cylindrical channel of the powerful high-voltage AC plasma torch

    International Nuclear Information System (INIS)

    The comparison of conductivity obtained in experiments with calculated values is made in this paper. Powerful stationary plasma torches with prolonged period of continuous work are popular for modern plasmachemical applications. The maximum electrode lifetime with the minimum erosion can be reached while working on rather low currents. Meanwhile it is required to provide voltage arc drop for the high power achievement. Electric field strength in the arc column of the high-voltage plasma torch, using air as a plasma-forming gas, does not exceed 15 V/cm. It is possible to obtain the high voltage drop in the long arc stabilized in the channel by the intensive gas flow under given conditions. Models of high voltage plasma torches with rod electrodes with power up to 50 kW have been developed and investigated. The plasma torch arcs are burning in cylindrical channels. Present investigations are directed at studying the possibility of developing long arc plasma torches with higher power. The advantage of AC power supplies usage is the possibility of the loss minimization due to the reactive power compensation. The theoretical maximum of voltage arc drop for power supplies with inductive current limitations is about 50 % of the no-load voltage for a single-phase circuit and about 30 % for the three-phase circuit. Burning of intensively blown arcs in the long cylindrical channel using the AC power supply with 10 kV no-load voltage is experimentally investigated in the work. Voltage drops close to the maximum possible had been reached in the examined arcs in single-phase and three-phase modes. Operating parameters for single-phase mode were: current −30 A, voltage drop −5 kV, air flow rate 35 g/s; for three-phase mode: current (40–85) A, voltage drop (2.5–3.2) kV, air flow rate (60–100) g/s. Arc length in the installations exceeded 2 m.

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

    Science.gov (United States)

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

    2012-02-01

    A method for generating high charge state heavy metal ion beams based on high power microwave heating of vacuum arc plasma confined in a magnetic trap under electron cyclotron resonance conditions has been developed. A feature of the work described here is the use of a cusp magnetic field with inherent "minimum-B" structure as the confinement geometry, as opposed to a simple mirror device as we have reported on previously. The cusp configuration has been successfully used for microwave heating of gas discharge plasma and extraction from the plasma of highly charged, high current, gaseous ion beams. Now we use the trap for heavy metal ion beam generation. Two different approaches were used for injecting the vacuum arc metal plasma into the trap--axial injection from a miniature arc source located on-axis near the microwave window, and radial injection from sources mounted radially at the midplane of the trap. Here, we describe preliminary results of heating vacuum arc plasma in a cusp magnetic trap by pulsed (400 μs) high power (up to 100 kW) microwave radiation at 37.5 GHz for the generation of highly charged heavy metal ion beams. PMID:22380156

  4. Modelling the position of analyte emission maxima in low temperature direct current arc plasma using statistical procedures

    International Nuclear Information System (INIS)

    In low temperature argon arc plasma, emission spectral lines of different analytes have characteristic radial distributions with emission maxima distributed over a wide plasma region, from the arc axis toward the arc periphery. It was assumed that the occurrence of emission maxima is a result of collective action of factors that control vaporization, dissociation, excitation, ionization and analyte transport. A statistical analysis was used to reveal a correlation between these various factors and a radial position of maximum emission. A regression analysis was used both for predictive and explanatory purposes: a model was built that successfully predicted analyte spatial emission characteristics, based on their physical properties and local plasma parameters, and a relative importance of proposed predictors was estimated. - Highlights: ► PCR analysis was used to model radial emission profiles in DC arc plasma. ► The main factors governing the radial distribution of atomic emission were analyzed. ► A model was built based on local plasma parameters and analyte physical properties.

  5. Experimental investigation of inhomogeneities, nanoscopic phase separation, and magnetism in arc melted Fe-Cu metals with equal atomic ratio of the constituents

    Science.gov (United States)

    Hassnain Jaffari, G.; Aftab, M.; Anjum, D. H.; Cha, Dongkyu; Poirier, Gerald; Ismat Shah, S.

    2015-12-01

    Composition gradient and phase separation at the nanoscale have been investigated for arc-melted and solidified with equiatomic Fe-Cu. Diffraction studies revealed that Fe and Cu exhibited phase separation with no trace of any mixing. Microscopy studies revealed that immiscible Fe-Cu form dense bulk nanocomposite. The spatial distribution of Fe and Cu showed existence of two distinct regions, i.e., Fe-rich and Cu-rich regions. Fe-rich regions have Cu precipitates of various sizes and different shapes, with Fe forming meshes or channels greater than 100 nm in size. On the other hand, the matrix of Cu-rich regions formed strips with fine strands of nanosized Fe. Macromagnetic response of the system showed ferromagnetic behavior with a magnetic moment being equal to about 2.13 μB/ Fe atom and a bulk like negligible value of coercivity over the temperature range of 5-300 K. Anisotropy constant has been calculated from various laws of approach to saturation, and its value is extracted to be equal to 1350 J/m3. Inhomogeneous strain within the Cu and Fe crystallites has been calculated for the (unannealed) sample solidified after arc-melting. Annealed sample also exhibited local inhomogeneity with removal of inhomogeneous strain and no appreciable change in magnetic character. However, for the annealed sample phase separated Fe exhibited homogenous strain.

  6. Experimental investigation of inhomogeneities, nanoscopic phase separation, and magnetism in arc melted Fe-Cu metals with equal atomic ratio of the constituents

    KAUST Repository

    Hassnain Jaffari, G.

    2015-12-16

    Composition gradient and phase separation at the nanoscale have been investigated for arc-melted and solidified with equiatomic Fe-Cu. Diffraction studies revealed that Fe and Cu exhibited phase separation with no trace of any mixing. Microscopy studies revealed that immiscible Fe-Cu form dense bulk nanocomposite. The spatial distribution of Fe and Cu showed existence of two distinct regions, i.e., Fe-rich and Cu-rich regions. Fe-rich regions have Cu precipitates of various sizes and different shapes, with Fe forming meshes or channels greater than 100 nm in size. On the other hand, the matrix of Cu-rich regions formed strips with fine strands of nanosized Fe. Macromagnetic response of the system showed ferromagnetic behavior with a magnetic moment being equal to about 2.13 μB/Fe atom and a bulk like negligible value of coercivity over the temperature range of 5–300 K. Anisotropy constant has been calculated from various laws of approach to saturation, and its value is extracted to be equal to 1350 J/m3. Inhomogeneous strain within the Cu and Fe crystallites has been calculated for the (unannealed) sample solidified after arc-melting. Annealed sample also exhibited local inhomogeneity with removal of inhomogeneous strain and no appreciable change in magnetic character. However, for the annealed sample phase separated Fe exhibited homogenous strain.

  7. 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

    Science.gov (United States)

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

    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.

  8. 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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

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

  10. ELECTRON-IMPACT BROADENING OF Cu IV LINES FOR THE DIAGNOSTIC OF THE ARC PLASMA OF ELECTRODYNAMIC MACRO-PARTICLE ACCELERATOR

    OpenAIRE

    Dimitrijevic, M.; Juric, Z.; Mihajlov, A.

    1989-01-01

    Using a model method of loss energy simulation on the boundary surfaces, temperature and composition of an electrodynamic macroparticle accelerator arc plasma created by the evaporation of a Cu foil, have been calculated. Stark widths for Cu IV lines of interest for the arc plasma diagnostic have been calculated also, by using the modified semiempirical method.

  11. Vitrification of MSWI Fly Ash by Thermal Plasma Melting and Fate of Heavy Metals

    Institute of Scientific and Technical Information of China (English)

    倪国华; 赵鹏; 江贻满; 孟月东

    2012-01-01

    Municipal solid waste incinerator (MSWI) fly ash with high basicity (about 1.68) was vitrified in a thermal plasma melting furnace system. Through the thermal plasma treatment, the vitrified product (slag) with amorphous dark glassy structure was obtained, and the leachability of hazardous metals in slag was significantly reduced. Meanwhile, it was found that the cooling rate affects significantly the immobility of heavy metals in slag. The mass distribution of heavy metals (Zn, Cd, Cr, Pb, As, Hg) was investigated in residual products (slag, secondary residues and flue gas), in order to analyze the behavior of heavy metals in thermal plasma atmosphere. Heavy metal species with low boiling points accounting for the major fraction of their input-mass were adsorbed in secondary residues by pollution abatement devices, while those with high boiling points tended to be encapsulated in slag.

  12. Interaction Studies of Ceramic Vacuum Plasma Spraying For The Melting Crucible Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Hwan [Univ., of Science and Technology, Daejeon (Korea, Republic of); Kim, Hyung Tae; Woo, Yoon Myung; Kim, Ki Hwan; Lee, Chan Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Fielding, R. S. [Idaho National Laboratory, Idaho (United States)

    2013-10-15

    Candidate coating materials for re-usable metallic nuclear fuel crucibles, TaC, TiC, ZrC, ZrO{sub 2}, and Y{sub 2}O{sub 3}, were plasma-sprayed onto a niobium substrate. The microstructure of the plasma-sprayed coatings and thermal cycling behavior were characterized, and U-Zr melt interaction studies were carried out. The TaC and Y{sub 2}O{sub 3} coating layers had a uniform thickness, and high density with only a few small closed pores showing good consolidation, while the ZrC, TiC, and ZrO{sub 2} coatings were not well consolidated with a considerable amount of porosity. Thermal cycling tests showed that the adhesion of the TiC, ZrC, and ZrO{sub 2} coating layers with niobium was relatively weak compared to the TaC and Y{sub 2}O{sub 3} coatings. The TaC and Y{sub 2}O{sub 3} coatings had better cycling characteristics with no interconnected cracks. In the interaction studies, ZrC and ZrO{sub 2} coated rods showed significant degradations after exposure to U-10 wt.% Zr melt at 1600 .deg. C for 15 min., but TaC, TiC, and Y{sub 2}O{sub 3} coatings showed good compatibility with U-Zr melt.

  13. Deposição por plasma com arco transferido Hardfacing by plasma transfer arc process

    OpenAIRE

    Víctor Vergara Díaz; Jair Carlos Dutra; Ana Sofia Clímaco Monteiro D´Oliveira

    2010-01-01

    Em virtude do Processo de Soldagem Plasma com Alimentação de Pó ter similaridades com o Processo de Soldagem Plasma com Alimentação de Arame, foi realizado um estudo comparativo entre ambos os processos utilizando-se a liga a base de cobalto comercialmente conhecida como Stellite 6, como material de adição na forma de pó e arame. A pesquisa foi realizada com a expectativa de ser aplicada nas operações de revestimentos de superfícies, em especial em pás de turbinas hidráulicas desgastadas por ...

  14. The influence of arc plasma electric and laser treatment on the structure and properties of the high speed steel

    Directory of Open Access Journals (Sweden)

    W. Bochnowski

    2009-07-01

    Full Text Available The examination of the structure, hardness and abrasion resistance of surface layer of high speed steel: HS 2-10-1-8, HS 6-5-2 and HS 10-2-5-8 after arc plasma and laser welding are presented in the paper. They are compared with the properties obtained after conventional hardening. Diode laser of continuous operation and GTAW (Gas Tungsten Arc Welding method were used. As a result of concentrated energy beam treatment applied to a steels surface layer, the structures characteristic of rapid solidification / crystallization process were obtained. The treatment of the steel by arc plasma electric with a single remelted track about 7 mm width does not lead to growth of the mechanical and tribological properties of high speed steels. The growth of microhardness as well as low the coefficient Archard of the high speed steel after remelting on the surface single track about 6 mm width by diode laser using can be obtained.

  15. US Bureau of Mines pilot-scale demonstration of electric arc furnace melting of multiple-source simulated low-level radioactive wastes

    International Nuclear Information System (INIS)

    The U.S. Bureau of Mines, in cooperation with Department of Energy (DOE) contractors Westinghouse Hanford Company (WHC) and Lockheed Idaho Technology Company (LITCO), conducted two extended melting campaigns in the electric arc furnace on radically different feeds. The WHC feed contained a high sodium, low-level radioactive liquid waste (LLW) simulant, and industrial glass-forming minerals designed to produce a final glass with 5 pct B2O3 and 20 pct Na2O. Preparation of dry furnace feed required absorbing the LLW simulant into the glass forniers and performing a low-temperature denitrification reaction. Nearly 22,000 lb of dry, denitrified feed, at feed rates from 250 to 750 lb/h, and average power of 400 kW, was melted producing over 18,000 lb of glass. The LITCO feeds were designed to simulate as-retrieved buried mixed wastes stored at the Idaho National Engineering Laboratory (INEL) Radioactive Waste Management Complex (RWMC). These feeds consisted of non-contaminated soil excavated from the RWMC, industrial mineral absorbents, scrap metals, oils, grease, and other combustible constituents, and lime added to the mix to produce a slag with molar basicity of 1.0. Over 18,000 lb of feed, with up to 25 pct combustible content, at feed rates up to 1,200 lb/h and average power of 230 kW, was melted producing over 10,000 lb of slag and 1,800 lb of metal. Material balances and facility operating conditions for each run are described. These tests demonstrated the flexibility and versatility of the electric arc furnace for the vitrification of the waste streams

  16. Preparation and particle size characterization of Cu nanopartides prepared by anodic arc plasma

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction (XRD), BET equation, transmission electron microscopy (TEM), and the corresponding selected area electron diffraction (SAED). The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m2/g, the particle size distribution is 30 to 90nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

  17. On the 'rocket' effect during plasma arc spraying

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, Valerian [ESAB Welding and Cutting Products, Florence, SC 29501 (United States) and Francis Marion University, Florence, SC 29501 (United States)

    2006-06-21

    A particle's surface is not heated uniformly during plasma arc spraying: the side of the surface that faces the torch is hotter than the opposite side. If the particle temperature is high enough for substantial evaporation to occur, the imbalance of the vapour pressure gives rise to a net recoil force accelerating the particle toward the substrate. Estimations show that if particle loss of mass due to evaporation {delta}M > M {radical}(2k{sub B}T/m)/U{sub d}, the suggested effect is as important for particle dynamics as aerodynamic drag. (M is the particle mass, U{sub d} is the particle speed and {radical}(2k{sub B}T/m) is the speed of the evaporating atom, m is its mass, and T is the particle surface temperature.)

  18. Preparation of photoluminescent single crystalline MgO nanobelts by DC arc plasma jet CVD

    International Nuclear Information System (INIS)

    Magnesium oxide (MgO) nanostructures were synthesized by DC arc plasma jet chemical vapor deposition, which possesses the advantages of being simple, economical, fast, effective and environmentally benign. The formation of “tadpole”-, dendrite-, belt- and rod-like MgO nanostructures was confirmed by scanning electron microscopy and high-resolution transmission electron microscopy. Powder X-ray diffraction analysis revealed that the nanostructures consist of cubic phase MgO. Nanobelts that were 30–50 nm wide with a width/thickness ratio of 1–2 were synthesized in just 5 min. Most of the nanobelts were connected to others, and the connected nanobelts possessed a single-crystal structure. A formation mechanism for MgO nanostructures was proposed. Fourier transform infrared spectra indicated the adsorption of water and CO2 on the MgO surface. The nanobelts exhibited relatively strong blue-green luminescence

  19. Steam Reforming of Dimethyl Ether by Gliding Arc Gas Discharge Plasma for Hydrogen Production

    Institute of Scientific and Technical Information of China (English)

    王保伟; 孙启梅; 吕一军; 杨美琳; 闫文娟

    2014-01-01

    Gliding arc gas discharge plasma was used for the generation of hydrogen from steam reforming of di-methyl ether (DME). A systemic procedure was employed to determine the suitable experimental conditions. It was found that DME conversion first increased up to the maximum and then decreased slightly with the increase of added water and air. The increase of total feed gas flow rate resulted in the decrease of DME conversion and hy-drogen yield, but hydrogen energy consumption dropped down to the lowest as total feed gas flow rate increased to 76 ml·min-1. Larger electrode gap and higher discharge voltage were advantageous. Electrode shape had an impor-tant effect on the conversion of DME and production of H2. Among the five electrodes, electrode 2# with valid length of 55 mm and the radian of 34 degrees of the top electrode section was the best option, which enhanced ob-viously the conversion of DME.

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

    Science.gov (United States)

    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.

  1. Dross and ultrafine particulate formation in underwater plasma-arc cutting

    International Nuclear Information System (INIS)

    Production rates and detailed chemical and physical characteristics of solid emissions from underwater plasma-arc cutting of non-active 304 grade stainless steel have been studied. Steel thicknesses to 40 mm have been cut in water depths of up to 10 metres. An hyperbaric vessel and a deep water test column and associated experimental equipment and techniques were developed for these studies. Concentrations and compositions of effluent by-product gases were also investigated. Part of the work done has been jointly with CEA Saclay and other institutions. Quantitative data, and possible mechanisms involved in the following aspects of the project were achieved: distribution, particle size and composition of solid emissions; composition and flowrates of effluent gases; effect of depth and other cutting conditions on solid and gaseous emissions; filtration resistance characteristics of water suspended particles; repeatability of cut quality and yields of emissions under standard cutting conditions

  2. Macroparticles in Ti-Si-N-coatings deposited from vacuum-arc plasma with ion implantation

    International Nuclear Information System (INIS)

    The results of experiments on research of macroparticles hitting TiSiN-coatings during vacuum-arc deposition from direct plasma stream with PBII and D method are presented. Sintered titanium-silicon powder composite was applied as a cathode material. The effect associated with the depression of macroparticles capture by growing TiSiN-coating as a result of increase of negative bias pulse on substrate simultaneous with periodic high-voltage negative potential pulses was found out. The depression of macroparticles capture at the increase of bias pulse with PBII and D technique takes a place under two factors. The main factor is electrostatic reflection of a large share of the negatively charged macroparticles stream. The second factor is the dispersion of macroparticles, surmounting electrostatic repulsion and 'stuck' to the coating surface.

  3. Effect of electron-neutral collisions on the satellites of the Thomson scattering spectrum in arc plasmas

    International Nuclear Information System (INIS)

    The effect of electron-neutral collisions on the high frequency spectrum of laser radiation scattered by the free electrons of a plasma is investigated for a partially ionized H2 arc plasma at atmospheric pressure. The calculations are carried out along Gorog's theory solving the linearized Boltzmann equation for electrons with a collision term. The collision integral is approximated by a Krook relaxation model with the collision frequency determined from experimental electron-atom scattering data. (orig./GG)

  4. Optimization of Weld Bead Parameters of Nickel Based Overlay Deposited by Plasma Transferred Arc Surfacing with Adequacy Test

    Directory of Open Access Journals (Sweden)

    Bhaskarananda Dasgupta

    2014-07-01

    Full Text Available Plasma Transferred Arc surfacing is a kind of Plasma Transferred Arc Welding process. Plasma Transferred Arc surfacing (PTA is increasingly used in applications where enhancement of wear, corrosion and heat resistance of materials surface is required. The shape of weld bead geometry affected by the PTA Welding process parameters is an indication of the quality of the weld. In this paper the analysis and optimization of weld bead parameters, during deposition of a Nickel based alloy Colmonoy on stainless steel plate by plasma transferred arc surfacing, are made and values of process parameters to produce optimal weld bead geometry are estimated. The experiments are conducted based on a five input process parameters and mathematical models are developed using multiple regression technique. The direct effects of input process parameters on weld bead geometry are discussed using graphs. Finally, optimization of the weld bead parameters, that is minimization of penetration and maximization of reinforcement and weld bead width, are made with a view to economize the input process parameters to achieve the desirable welding joint.

  5. Underwater plasma arc cutting of in-reactor tube of In-Pile Creep Test Facility

    International Nuclear Information System (INIS)

    The in-reactor tube of the In-Pile Creep Facility had been irradiated periodically for over 6 years in the Japan Materials Testing Reactor (JMTR) up to the end of 1978 under an operating condition of high temperature and high pressure identical to that of the Prototype Advanced Thermal Reactor, FUGEN, to gain the basic data for estimating the amount of creep which would occur in the pressure tubes of FUGEN. Following the removal of the in-reactor tube out of the JMTR, the test sections in the tube which were to be subjected to post irradiation examination were cut out. Underwater plasma arc cutting was employed to prevent the spread of contamination to the work area, to confine the heat affected zone in the test pieces to a minimum and to simplify disposal of the unneeded portions of the pressure tube. Setup of the cutting machine, cutting operations, radiological conditions during cutting of the highly radioactive portion of the tube and disassembly of the cutting equipment are described. In addition a brief description of the underwater plasma arc cutting machine is presented. The hot-cutting operations were done remotely to control personal exposure. The containment envelope prevented the spread of contamination to the environment and radioactive particles deposited on the cutting machine were removed without any difficulties. External exposure received by cutting personnel was small. Internal radionuclide deposit examinations were conducted, determining no crew member inhaled radioactive substances. Contamination spreads to the work area were minimal and release of radionuclide was well controlled. (author)

  6. Production mechanism of high proton ratio plasma in a hydrogen arc discharge ion source

    Energy Technology Data Exchange (ETDEWEB)

    Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi; Watanabe, Kazuhiro; Kashiwagi, Mieko; Taniguchi, Masaki; Hanada, Masaya; Imai, Tsuyoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Shimizu, Takashi [Doshisha Univ., Kyoto (Japan)

    2003-03-01

    Generally a large volume plasma generator with strong plasma confinement is suitable for production of a high proton yield of >90%. Recently a small ion source whose discharge volume is only 1.4 liter produced a high proton ratio of {approx}90% by applying transverse magnetic field. Mechanism of a high proton ration plasma production in such a small ion source has not been studied. The proton production mechanisms in a hydrogen arc discharge were numerically studied by solving rate equations to obtain H{sup +}, H{sub 2}{sup +}, H{sub 3}{sup +}, and H{sup 0} densities in various scales of ion sources. It was revealed that a main process of proton production depends strongly on a following process of H{sub 2}{sup +} + e {yields} H{sup +} + H + e in the small volume discharge. By applying the transverse magnetic field in the plasma volume, flow of primary electrons through the magnetic field is restrained, resulting in suppression of H{sub 2}{sup +} production near the plasma grid. In addition, H{sup +} is produced near the plasma grid from dissociation of H{sub 2}{sup +} due to the large cross section with low temperature electrons. Thus the proton yield is enhanced even in the small volume discharge by applying the magnetic field. Using the same numerical method, the plasma production mechanism was calculated for a large ion source. The high proton ratio and the high atomic hydrogen density can be easily obtained under the low-pressure discharge, where the contribution of proton production reaction H + e {yields} H{sup +} + 2e is comparable or higher than that of H{sub 2}{sup +} e {yields} H{sup +} + H + e. From the negative ion production point of view, experimentally obtained negative ion beam current was evaluated quantitatively from the numerical analysis. As a result, it was shown that the high atom flux to the plasma grid surface generates large amount of negative ion flux rather than that by the positive ions in Cs-seeded large ion sources. (author)

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

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Matějíček, Jiří; Ctibor, Pavel; Mašláni, Alan; Hrabovský, Milan

    2011-01-01

    Roč. 20, č. 4 (2011), s. 760-774. ISSN 1059-9630 R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : copper coatings * hybrid water-gas torch * metallic particle oxidation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.812, year: 2011 http://www.springerlink.com/content/78n3736855261197/fulltext.pdf

  8. Hydrous basalt-limestone interaction at crustal conditions: Implications for generation of ultracalcic melts and outflux of CO2 at volcanic arcs

    Science.gov (United States)

    Carter, Laura B.; Dasgupta, Rajdeep

    2015-10-01

    High degassing rates for some volcanoes, typically in continental arcs, (e.g., Colli Albani Volcanic District, Etna, Vesuvius, Italy; Merapi, Indonesia; Popocatepetl, Mexico) are thought to be influenced by magma-carbonate interaction in the crust. In order to constrain the nature of reaction and extent of carbonate breakdown, we simulated basalt-limestone wall-rock interactions at 0.5-1.0 GPa, 1100-1200 °C using a piston cylinder and equal mass fractions of calcite (CaCO3) and a hydrous (∼4 wt.% H2O) basalt in a layered geometry contained in AuPd capsules. All experiments produce melt + fluid + calcite ± clinopyroxene ± plagioclase ± calcic-scapolite ± spinel. With increasing T, plagioclase is progressively replaced by scapolite, clinopyroxene becomes CaTs-rich, and fluid proportion, as inferred from vesicle population, increases. At 1.0 GPa, 1200 °C our hydrous basalt is superliquidus, whereas in the presence of calcite, the experiment produces calcite + clinopyroxene + scapolite + melt. With the consumption of calcite with increasing T and decreasing P, melt, on a volatile-free basis, becomes silica-poor (58.1 wt.% at 1.0 GPa, 1100 °C to 34.9 wt.% at 0.5 GPa, 1200 °C) and CaO-rich (6.7 wt.% at 1.0 GPa, 1100 °C to 43.7 wt.% at 0.5 GPa, 1200 °C), whereas Al2O3 drops (e.g., 19.7 at 1100 °C to 12.8 wt.% at 1200 °C at 1.0 GPa) as clinopyroxene becomes more CaTs-rich. High T or low P melt compositions are 'ultracalcic,' potentially presenting a new hypothesis for the origin of ultracalcic melt inclusions in arc lava olivines. Wall-rock calcite consumption is observed to increase with increasing T and decreasing P. At 0.5 GPa, our experiments yield carbonate assimilation from 21.6 to 47.6% between 1100 and 1200 °C. Using measured CO2 outflux rates for Mts. Vesuvius, Merapi, Etna and Popocatepetl over a T variation of 1100 to 1200 °C at 0.5 GPa, we calculate 6-92% of magmatic input estimates undergo this extent of assimilation, suggesting that up to ∼3

  9. Hydrogen generation from water using Mg nanopowder produced by arc plasma method

    International Nuclear Information System (INIS)

    We report that hydrogen gas can be easily produced from water at room temperature using a Mg nanopowder (30–1000 nm particles, average diameter 265 nm). The Mg nanopowder was produced by dc arc melting of a Mg ingot in a chamber with mixed-gas atmosphere (20% N2–80% Ar) at 0.1 MPa using custom-built nanopowder production equipment. The Mg nanopowder was passivated with a gas mixture of 1% O2 in Ar for 12 h in the final step of the synthesis, after which the nanopowder could be safely handled in ambient air. The nanopowder vigorously reacted with water at room temperature, producing 110 ml of hydrogen gas per 1 g of powder in 600 s. This amount corresponds to 11% of the hydrogen that could be generated by the stoichiometric reaction between Mg and water. Mg(OH)2 flakes formed on the surface of the Mg particles as a result of this reaction. They easily peeled off, and the generation of hydrogen continued until all the Mg was consumed.

  10. Hydrogen generation from water using Mg nanopowder produced by arc plasma method

    Directory of Open Access Journals (Sweden)

    Masahiro Uda, Hideo Okuyama, Tohru S Suzuki and Yoshio Sakka

    2012-01-01

    Full Text Available We report that hydrogen gas can be easily produced from water at room temperature using a Mg nanopowder (30–1000 nm particles, average diameter 265 nm. The Mg nanopowder was produced by dc arc melting of a Mg ingot in a chamber with mixed-gas atmosphere (20% N2–80% Ar at 0.1 MPa using custom-built nanopowder production equipment. The Mg nanopowder was passivated with a gas mixture of 1% O2 in Ar for 12 h in the final step of the synthesis, after which the nanopowder could be safely handled in ambient air. The nanopowder vigorously reacted with water at room temperature, producing 110 ml of hydrogen gas per 1 g of powder in 600 s. This amount corresponds to 11% of the hydrogen that could be generated by the stoichiometric reaction between Mg and water. Mg(OH2 flakes formed on the surface of the Mg particles as a result of this reaction. They easily peeled off, and the generation of hydrogen continued until all the Mg was consumed.

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

    Science.gov (United States)

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

    2016-05-01

    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.

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

    Science.gov (United States)

    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.

  13. Reduced-order modeling of high-speed jets controlled by arc filament plasma actuators

    Science.gov (United States)

    Sinha, Aniruddha; Serrani, Andrea; Samimy, Mo

    2013-02-01

    Arc filament plasma actuators applied to high-speed and high Reynolds number jets have demonstrated significant mixing enhancement when operated near the jet column mode (JCM) frequency. A feedback-oriented reduced-order model is developed for this flow from experimental data. The existent toolkit of stochastic estimation, proper orthogonal decomposition, and Galerkin projection is adapted to yield a 35-dimensional model for the unforced jet. Explicit inclusion of a "shift mode" stabilizes the model. The short-term predictive capability of instantaneous flow fields is found to degrade beyond a single flow time step, but this horizon may be adequate for feedback control. Statistical results from long-term simulations agree well with experimental observations. The model of the unforced jet is augmented to incorporate the effects of plasma actuation. Periodic forcing is modeled as a deterministic pressure wave specified on the inflow boundary of the modeling domain. Simulations of the forced model capture the nonlinear response that leads to optimal mixing enhancement in a small range of frequencies near the JCM.

  14. Visualizing the influence of the process parameters on the keyhole dimensions in plasma arc welding

    International Nuclear Information System (INIS)

    The keyhole status and its dimensions are critical information determining both the process quality and weld quality in plasma arc welding (PAW). It is of great significance to measure the keyhole shape and size and to correlate them with the main process parameters. In this study, a low-cost vision system is developed to visualize the keyhole at the backside of the test-pieces in PAW. Three stages of keyhole evolution, i.e. initial blind stage (non-penetrated keyhole), unstable stage with momentarily disappeared keyhole and quasi-steady open keyhole stage (fully-penetrated keyhole), are measured in real-time during the PAW tests on stainless steel test-pieces of thickness 8 mm. Based on the captured images of keyhole under different welding conditions, the correlations of the main welding process parameters (welding current, welding speed, plasma gas flow rate) with the keyhole length, width and area are visualized through vision measurement. It lays a solid foundation for implementing keyhole stability control and process optimization in keyhole PAW. (paper)

  15. Preliminary Study of Mixing of Plasma Species in a Hybrid-Stabilized Argon-Water Electric Arc

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

    Roč. 2, č. 3 (2015), s. 316-319. ISSN 2336-2626. [Symposium on Physics of Switching Arc/21./. Nové Město na Moravě, 07.09.2015-11.09.2015] R&D Projects: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : arc discharge * combined diffusion coefficients * inhomogeneous mixing * mass fraction Subject RIV: BL - Plasma and Gas Discharge Physics https ://www.vutbr.cz/www_base/vutdisk.php?i=36809a9aa

  16. Characterization of solidified products yielded by plasma melting treatment of simulated non-metallic radioactive wastes

    International Nuclear Information System (INIS)

    As a part of an advanced volume reduction program for low level radioactive wastes in JAERI, melting tests of non-metallic solid wastes have been conducted with the aim of establishing the optimum melting condition for preparation of a stable solid that is suitable for disposal. Simulated non-metallic wastes containing 60Co, 137Cs and 152Eu tracers were melted with a plasma torch of a non-transferred type, and the examination was carried out on chemical composition and physical properties of solidified products and the distribution of tracers in each product. The products were almost homogeneous and possessed satisfactory mechanical strength for disposal. The radioactive nuclides were almost uniformly distributed in the products. The amount of 137Cs remaining in the products depended on the basicity of slag, while that of 60Co was not. A small amount of fine metal particles containing 60Co was observed in a slag. This was attributable to partial reduction of metal oxides under the relatively reductive atmosphere. (author)

  17. Degradation of solar cell electric performance due to arcing in LEO plasma environment

    OpenAIRE

    Okumura, Teppei; Hosoda, Satoshi; Kagawa, Hideshi; 奥村 哲平; 細田 聡史; Kim, Jeongho; Cho, Mengu; 香河 英史

    2005-01-01

    When we operate solar array at high voltage (greater than 100 V) in LEO environment, arcing occurs on the solar array surface. The solar cell can suffer degradation of electric performance due to only one arc with some probability. We performed degradation test of solar array coupons against arcing under simulated LEO environment in order to identify the threshold of arc energy to cause the solar cell degradation. The solar array coupons are made of silicon solar cells. The LCR circuit was at...

  18. Structural, magnetic, magneto-caloric and Mössbauer spectral study of Tb2Fe17 compound synthesized by arc melting

    Science.gov (United States)

    Charfeddine, S.; Zehani, K.; Bessais, L.; Korchef, A.

    2016-06-01

    We have synthesized the intermetallic Tb2Fe17 compound in hexagonal crystal structure by arc-melting without annealing. X-ray diffraction pattern has been refined by Rietveld method. The crystal structure is hexagonal with P63/mmc space group (Th2Ni17-type). The Mössbauer spectrum of Tb2Fe17 compound has been analyzed with seven magnetic sextets assigned to the inequivalent crystallographic sites. The temperature dependence of magnetization data revealed that Tb2Fe17 exhibits a second-order ferromagnetic to paramagnetic phase transition in the vicinity of Curie temperature (TC=412 K). The relative cooling power around the magnetic transition and the Arrott plots are also reported.

  19. High strength and ductile bulk Ti-Ni-Cu-Nb alloy with submicron-size structure units obtained by arc-melting

    International Nuclear Information System (INIS)

    The structure of an arc-melted ingot of the Ti50Ni20Cu20Nb10 alloy of about 30 mm diameter and 10 mm height was studied by X-ray diffractometry, transmission electron microscopy (TEM). Mechanical properties were tested by an Instron-type testing machine. The ingot sample has a disperse submicron-size complex eutectic structure (including ternary eutectic) consisting of a quaternary β-(Ti, Nb, Ni, Cu) solid solution, a monoclinic TiNi-type (Ti, Nb)(Ni, Cu) phase and a (Ti, Nb)2(Cu, Ni) phase which is a solution of Nb (replacing Ti) and Ni (replacing Cu) in the tetragonal Ti2Cu phase. The sample exhibits high mechanical properties and does not require additional mold injection casting procedure to obtain fine microstructure

  20. Vaporization behavior of Cs in plasma melting of simulated low-level miscellaneous solid waste. Pt. 2. Melting conditions for capturing cesium

    International Nuclear Information System (INIS)

    The melting conditions for capturing cesium at utility fraction level in the plasma melting process of the low level miscellaneous solid wastes have been investigating by examining the vaporization rate of Cs from the molten slag. The apparent vaporization rate of Cs was found to be follow the first-order rate equation with respect to Cs content in the molten slag, and its rate constant values were (3.5-20) X 10-6 (m/s) in the range of chemical composition of the miscellaneous solid wastes at the condition of the molten slag surface of 415 cm2 The rate constants were decreased with the increase of molten slag surface because the vaporization rate of Cs was affected by the high temperature region provided by a plasma attachment on the molten slag surface. By evaluating the rate constants with these treatment conditions, the melting conditions for achieving the migration ratio of Cs over 50 % was given. The melting conditions was validated by a comparison with the experimental results of the migration ratio of Cs. (author)

  1. Rapidly solidified titanium alloys by melt overflow

    Science.gov (United States)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III

    1989-01-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  2. Simultaneous melting of low level miscellaneous solid wastes by thermal plasma

    International Nuclear Information System (INIS)

    Metallic, incombustible and combustible materials simulating low level radioactive miscellaneous solid wastes generated form nuclear power plants are simultaneously melted by thermal plasma heating with non-radioactive tracers. The solidified products show the following excellent properties suitable for final disposal. The uni-axial compressive strength of slag layers are more than 500 kg f/cm2. These values are higher than that of cement waste forms. The cold tracers concentration and specific gravity are homogeneous in both metallic and slag layers of solidified products. This result indicates that it will be easy to measure radioactivity of the waste form before final disposal. The results of leaching test show that the solidified products have performance good enough to stabilize the radionuclides. Also cold tracers migrated into solidified products stably, especially even Cs with low boiling temperature could be captured in the slag layers more than 50%. From the above results, we concluded that plasma melting technology can be applied to simultaneous treatment of miscellaneous solid wastes. (author)

  3. Reduction in airborne contamination levels at the 9201-5 Arc Melt sawing operation. A Y-12 Plant 1982 ALARA goal

    Energy Technology Data Exchange (ETDEWEB)

    Beck, D.E.; West, C.M.

    1983-02-01

    Lowering the uranium airborne contamination level at the two saws in the 9201-5 Arc Melt Area was chosen as a Y-12 Plant As-Low-As-Reasonably-Achievable (ALARA) goal for 1982. This priority was convincingly communicated to those involving by giving specific instructions to suspend saw operations any time there was evidence of a problem until that problem could be corrected. Using control charts on air flow rates into the saw enclosures and pressure drops across filters in the saw ventilation (Delta Phase I) exhaust system, it was possible to decide when filter changes or other adjustments were necessary to maintain the exhaust flow rates needed for improved airborne contamination control. The keeping of these charts, along with the actions taken on the basis of the data gathered, made it possible to meet the goal of reducing airborne contamination levels in 1982, as compared with 1981, although production in the Arc Melt Area increased significantly. These data also showed that use of one brand of filter in the prefilter system resulted in the need to change filters more frequently than when another brand was used. This fact triggered an investigation which revealed the cause for the shorter useful life of that filter and a request that only specifically approved filters be purchased for use in this system. Use of these control data also made it possible to establish that the exhaust system operated more effectively without the Roto-clone hydrostatic pecipitators because exhaust air flow was increased without reduction in filter life.

  4. Reduction in airborne contamination levels at the 9201-5 Arc Melt sawing operation. A Y-12 Plant 1982 ALARA goal

    International Nuclear Information System (INIS)

    Lowering the uranium airborne contamination level at the two saws in the 9201-5 Arc Melt Area was chosen as a Y-12 Plant As-Low-As-Reasonably-Achievable (ALARA) goal for 1982. This priority was convincingly communicated to those involving by giving specific instructions to suspend saw operations any time there was evidence of a problem until that problem could be corrected. Using control charts on air flow rates into the saw enclosures and pressure drops across filters in the saw ventilation (Delta Phase I) exhaust system, it was possible to decide when filter changes or other adjustments were necessary to maintain the exhaust flow rates needed for improved airborne contamination control. The keeping of these charts, along with the actions taken on the basis of the data gathered, made it possible to meet the goal of reducing airborne contamination levels in 1982, as compared with 1981, although production in the Arc Melt Area increased significantly. These data also showed that use of one brand of filter in the prefilter system resulted in the need to change filters more frequently than when another brand was used. This fact triggered an investigation which revealed the cause for the shorter useful life of that filter and a request that only specifically approved filters be purchased for use in this system. Use of these control data also made it possible to establish that the exhaust system operated more effectively without the Roto-clone hydrostatic pecipitators because exhaust air flow was increased without reduction in filter life

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

    Science.gov (United States)

    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.

  6. ELM-induced melting: assessment of shallow melt layer damage and the power handling capability of tungsten in a linear plasma device

    Czech Academy of Sciences Publication Activity Database

    Morgan, T.W.; van Eden, G.G.; de Kruif, T.M.; van den Berg, A.; Matějíček, Jiří; Chráska, Tomáš; De Temmerman, G.

    -, T159 (2014), 014022-014022. ISSN 0031-8949. [International Conference on Plasma-Facing Materials and Components for Fusion Applications/14./. Jülich, 13.05.2013-17.05.2013] Institutional support: RVO:61389021 Keywords : melting * tungsten * ELMs * divertor * ITER * DEMO Subject RIV: JG - Metallurgy Impact factor: 1.126, year: 2014 http://iopscience.iop.org/1402-4896/2014/T159/014022/pdf/1402-4896_2014_T159_014022.pdf

  7. Fracture behaviour of As fabricated and hydrogen charged Zr-2.5 wt % Nb pressure tubes made from double and quadruple vacuum arc melted ingots

    International Nuclear Information System (INIS)

    This article discusses the fracture behaviour of pressure tubes fabricated from quadruple vacuum arc remelted (QM) and double arc remelted (DM) Zr-2.5 wt % Nb ingots. The fracture behaviour of these alloys have been characterized using J-R curves over the temperature range of 27 to 300 deg C using single specimen test techniques and load normalization method. Effect of hydrogen ingress on the fracture properties have also been investigated. The acoustic emission (AE) activity was monitored during the tensile pull of precracked compact tension specimen to observe differences during the fracture process. Significant enhancement in the initiation and crack growth fracture toughness was found for quadruple melted alloys over the entire range of test temperature (ambient to 300 deg C). As fabricated pressure tubes when charged with different levels of hydrogen show sharp reduction in fracture toughness values at ambient temperature. The fracture toughness of hydrided material slowly increases with the increase in the test temperature and above 150 to 170 deg C a sharp increase in the toughness values are observed in the DM alloy. Hydrided QM alloy showed marginally better fracture properties than DM alloys, at low hydrogen levels (25 ppm), which is attributed to the inherently higher toughness of QM matrix. (author)

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

    Science.gov (United States)

    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

  9. Late Triassic Batang Group arc volcanic rocks in the northeastern margin of Qiangtang terrane, northern Tibet: partial melting of juvenile crust and implications for Paleo-Tethys ocean subduction

    Science.gov (United States)

    Zhao, Shao-Qing; Tan, Jun; Wei, Jun-Hao; Tian, Ning; Zhang, Dao-Han; Liang, Sheng-Nan; Chen, Jia-Jie

    2015-03-01

    The Batang Group (BTG) volcanic rocks in the Zhiduo area, with NW-trending outcrops along the northeastern margin of the Qiangtang terrane (northern Tibet), are mainly composed of volcaniclastic rocks, dacite and rhyolite. Major and trace element, Sr and Nd isotope, zircon U-Pb and Hf isotope data are presented for the BTG dacites. Laser ablation inductively coupled plasma mass spectrometry zircon U-Pb dating constrains the timing of volcanic eruption as Late Triassic (221 ± 1 Ma). Major and trace element geochemistry shows that the BTG volcanic rocks are classified as calc-alkaline series. All samples are enriched in large-ion lithophile elements and light rare earth elements with negative-slightly positive Eu anomalies (Eu/Eu* = 0.47-1.15), and depleted in high field strength elements and heavy rare earth elements. In addition, these rocks possess less radiogenic Sr [(87Sr/86Sr) i = 0.7047-0.7078], much radiogenic Nd (ɛNd( t) = -4.2 to -1.3) and Hf (ɛHf( t) = 4.0-6.6) isotopes, suggesting that they probably originated from partial melting of a crustal source containing a mantle-derived juvenile component. The inferred magma was assimilated by crustal materials during ascending and experienced significant fractional crystallization. By combining previously published and the new data, we propose that the BTG volcanic rocks were genetically related to southwestward subduction of the Ganzi-Litang ocean (a branch of Paleo-Tethys) in the northeastern margin of the Qiangtang terrane. Given the coeval arc-affinity magmatic rocks in the region, we envisage that the Ganzi-Litang ocean may extend from the Zhongdian arc through the Yidun terrane to the Zhiduo area, probably even further northwest to the Tuotuohe area.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  11. U-Th-Ra-Pa Disequilibria in the Kasuga Seamounts: recent "sediment" flux melting in the Mariana rear arc

    Science.gov (United States)

    Gill, J.; Holden, P.

    2002-12-01

    Mariana volcanic front lavas define a U-Th isotope mixing line with an apparent age of 30 Ka between U-enriched "basalt fluid"-dominated Guguan and "sediment melt"-dominated Uracas in 238U-230Th equilibrium (Elliott et al., 1997). However, new results for basalts collected by dredging and diving on the shoshonitic Kasuga Seamounts, 10-20 km behind the VF, require re-interpretation of both Mariana components. Kasuga basalts are the local "sediment" extreme, reaching La/Sm = 5, Th/Nb=0.75, and eNd=3 in the most K-rich samples. Despite this extremity, their U-Th disequilibria lie along the same mixing line as for the VF, but extend to 20 percent 230Th-enrichment and (230Th)/(232Th) lower than at the intersection with the equiline. This indicates deeper melting than at the VF, and that the source's Th/U ratio was higher than the intersection. (226Ra)/(230Th) ratios extend to 3.5 even though samples have unknown eruption ages and Ba/Th is only 100, much lower than at the VF. (231Pa)/(235U) is mostly 1.7, higher than at the VF. (231Pa)/(230Th) correlates positively with excess U, consistent with recent flux melting. However, the mantle being melted is more fertile than at the VF, and the flux is more "sedimentary" apart from its disequilibria. Disequilibria in the highest-K Kasuga are most like Kick-em-Jenny, the most sediment-rich part of the Antilles.

  12. Metasomatic interactions between slab-derived melts and depleted mantle : insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

    OpenAIRE

    Grégoire, M.; JEGO S.; Maury, R.C.; Polvé, Mireille; Payot, B.; Tamayo, R. A.; Yumul, G. P.

    2008-01-01

    The Monglo adakite contains mafic and ultramafic xenoliths, which probably originated from the mantle section of an Early Cretaceous supra-subduction zone ophiolitic complex located within the Luzon are crust. Spinel-bearing dunites are dominant among this xenolith collection and display evidence for three episodes of subduction-related melt percolation. The first one is evidenced by an undeformed clinopyroxene characterized by convex-upwards REE pattern. This clinopyroxene crystallized from ...

  13. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    Science.gov (United States)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-02-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  14. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    International Nuclear Information System (INIS)

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  15. Use of a Low-Pressure Non-Self-Sustained Arc Discharge for Plasma Ion Treatment of Materials

    International Nuclear Information System (INIS)

    An efficient method for producing low-temperature gas plasmas in large vacuum volumes is based on the initiation and operation of a low-pressure non-self-sustained arc discharge with a combined cathode including a hot cathode and a hollow cathode. For this type of a discharge, the inner walls of the working vacuum chamber play the role of a hollow anode. In the range from 10-1 to 1 Pa, this method makes it possible to produce plasmas of both inert and reactive gases of density 109 - 1010 cm-3 uniform within 20% with respect to the average value in volumes of about 1 m3. This paper describes major applications of this type of plasma in technological processes, such as: finish surface cleaning of materials and articles in vacuum; plasma ion nitriding of steels and alloys; plasma-assisted deposition of functional coatings on materials and articles. (author)

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

    Science.gov (United States)

    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.

  17. Simultaneous observation of keyhole and weld pool in plasma arc welding with a single cost-effective sensor

    Institute of Scientific and Technical Information of China (English)

    张国凯; 武传松; 刘新锋; 张晨

    2014-01-01

    The dynamic behaviors ofthe keyhole and weld pool are coupled together in plasma arc welding,and the geometric variations ofboth the keyhole and the weld pool determine the weld quality.It is ofgreat significance to simultaneously sense and monitor the keyhole and the weld pool behaviors by using a single low-cost vision sensor in plasma arc welding process.In this study,the keyhole and weld pool were observed and measured under different levels ofwelding current by using the near infrared sensing technology and the charge coupled device (CCD)sensing system.The shapes and relative position ofweld pool and keyhole under different conditions were compared and analyzed.The observation results lay solid foundation for controlling weld quality and understanding the underlying process mechanisms.

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

    Directory of Open Access Journals (Sweden)

    Zhu W

    2015-12-01

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

  19. Plasma arc and thermal lance techniques for cutting concrete and steel

    International Nuclear Information System (INIS)

    The plasma arc technique is used today in industrial practice for any metal, but mainly for cutting stainless steel, carbon steel and aluminium. In air the maximum thickness that was cut in the performed tests was 150 mm, both with ferritic and austenitic steel. Underwater the maximum thickness cut was 103 mm. The two types of torch used in the tests are those used today: the plasma-shaped electrode torch (WIPC) and the pointed electrode torch (DMC-GRUEN). Two different types of gas were compared: an argon-nitrogen mixture and an argon-hydrogen mixture. The second mixture adopted results in less dust emission. The production of dust and aerosols also depends on the cutting speed, on the kind of steel, but mainly on the environmental conditions; it is reduced up to 500 times under water. Dust and aerosols can, jeopardize the efficiency of the system; moreover, the ambient air can have high-level radiation fields. Indirect and direct protections are needed (shields, remote control, robots, etc.). Tentative procedures for dismantling two types of BWR reactor are examined. Two series of tests demonstrated the feasibility of cutting the most geometrically difficult parts of the reactor internals. The thermal lance technique is used in industrial practice mainly for dismantling large reinforced concrete structures. This technique can be applied to dismantle nuclear facilities, even though it can cause some problems due to the gases, fumes and lapilli produced. In addition, the cost of this technique seems to be generally higher than the cost of other techniques. From the analyses done, the conclusion seems that both the above techniques are feasible for dismantling a nuclear power plant (NPP). The best solution is probably to analyse the different dismantling possibilities and problems and problems of each case

  20. Microstructural Evolution and Mechanical Properties of Inconel 625 Alloy during Pulsed Plasma Arc Deposition Process

    Institute of Scientific and Technical Information of China (English)

    Fujia Xu; Yaohui Lv; Yuxin Liu; Fengyuan Shu; Peng He; Binshi Xu

    2013-01-01

    Pulsed plasma arc deposition (PPAD),which combines pulsed plasma cladding with rapid prototyping,is a promising technology for manufacturing near net shape components due to its superiority in cost and convenience of processing.In the present research,PPAD was successfully used to fabricate the Ni-based superalloy Inconel 625 components.The microstructures and mechanical properties of deposits were investigated by scanning electron microscopy (SEM),optical microscopy (OM),transmission electron microscopy (TEM) with energy dispersive spectrometer (EDS),microhardness and tensile testers.It was found that the as-deposited structure exhibited homogenous columnar dendrite structure,which grew epitaxially along the deposition direction.Moreover,some intermetallic phases such as Laves phase,minor MC (NbC,TiC) carbides and needle-like δ-Ni3Nb were observed in γ-Ni matrix.Precipitation mechanism and distribution characteristics of these intermetallic phases in the as-deposited 625 alloy sample were analyzed.In order to evaluate the mechanical properties of the deposits,microhardness was measured at various location (including transverse plane and longitudinal plane).The results revealed hardness was in the range of 260-285 HVo.2.In particular,microhardness at the interface region between two adjacent deposited layers was slightly higher than that at other regions due to highly refined structure and the disperse distribution of Laves particles.Finally,the influence of precipitation phases and fabrication strategies on the tensile properties of the as-deposited samples was investigated.The failure modes of the tensile specimens were analyzed with fractography.

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

    Science.gov (United States)

    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.

  2. Synthesis of SiO(x) powder using DC arc plasma.

    Science.gov (United States)

    Jung, Chan-Ok; Park, Dong-Wha

    2013-02-01

    SiO(x) was prepared by DC arc plasma and applied to the anode material of lithium ion batteries. A pellet of a mixture of Si and SiO2 was used as the raw material. The ratios of the silicon and silicon dioxide (SiO2) mixtures were varied by controlling the Si-SiO2 molar ratio (Si-SiO2 = 1-4). Hydrogen gas was used as the reduction atmosphere in the chamber. The prepared SiO(x) was collected on the chamber wall. The obtained SiO(x) was characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and TEM showed that the phase composition of the prepared particles was composed of amorphous SiO(x) and crystalline Si. The prepared SiO(x) showed wire and spherical morphology. XPS indicated the bonding state and 'x' value of the prepared SiO(x), which was close to one. The result of prepared SiO(x) is discussed from thermodynamic equilibrium calculations. The electrochemical behavior of the silicon monoxide anode was investigated. PMID:23646592

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

    Science.gov (United States)

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

    2015-01-01

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

  4. Influence of Calcination Temperature on Nano-TiO2 Photocatalyst Synthesized by Gliding Arc Plasma

    Directory of Open Access Journals (Sweden)

    LIU Shi-Xin, LI Xiao-Song, DENG Xiao-Qing, SUN Zhi-Guang, ZHU Ai-Min

    2015-02-01

    Full Text Available TiO2 nanopowders with different morphologies and initial anatase contents (fA were synthesized by gliding arc plasma. X-ray diffraction (XRD, transmission electron microscope (TEM and physisorption instruments were employed to investigate the effects of calcination temperature on phase composition, crystal size, morphology and specific surface area (SBET of the TiO2 nanopowders. Photocatalytic oxidation of methylene blue was utilized to evaluate the activities of calcined TiO2 nanopowders. The results indicate that the anatase-rutile transformation temperature of as-synthesized TiO2 nanopowders is around 650℃, and the anatase-rutile transformation rate depends on the calcination temperature, morphology and the initialfA. With the increase of calcination temperature, the anatase crystal size slightly increases and SBET slightly decreases for spherical particles, while for non-spherical particles, the anatase crystal size increases and SBET decreases rapidly. With the increase of fA, the variation of photocatalytic apparent rate constant (k of TiO2 nanopowder presents three profiles: whenfA is below 70%, k slowly increases; whenfA ranges from 70% to 85%, k rapidly increases; whenfA is beyond 85%, k rapidly decreases.

  5. Electrode Erosion in Pulsed Arc for Generating Air Meso-Plasma Jet under Atmospheric Pressure

    Science.gov (United States)

    Shiki, Hajime; Motoki, Junpei; Takikawa, Hirofumi; Sakakibara, Tateki; Nishimura, Yoshimi; Hishida, Shigeji; Okawa, Takashi; Ootsuka, Takeshi

    Various materials of the rod electrode were examined in pulsed arc of PEN-Jet (Plasma ENergized-Jet) with working gas of air, which can be used for the surface treatment under atmospheric pressure. The erosion of the rod electrode was measured and it surface was observed. The amount of erosion and surface appearance were found to be different for the materials, input power and energizing time. Tungsten (W) rod electrode was oxidized immediately after starting the discharge and tungsten oxide (WO3) powder was generated over the side surface of electrode tip. This powder contaminated the treating surface. Copper (Cu) rod electrode was also oxidized immediately and CuO/Cu2O multi-layer was formed on the electrode surface. However, the erosion of Cu electrode was quite small. Platinum (Pt) and iridium (20 wt%)-contained-platinum (Pt-Ir) rod electrode were not oxidized and their erosions were significantly small. This indicated that they could be employed for keeping the constant electrode-gap and processing the surface treatment without contamination due to electrode erosion.

  6. Effect of current and atomized grain size distribution on the solidification of Plasma Transferred Arc coatings

    Directory of Open Access Journals (Sweden)

    Danielle Bond

    2012-10-01

    Full Text Available Plasma Transferred Arc (PTA is the only thermal spray process that results in a metallurgical bond, being frequently described as a hardfacing process. The superior properties of coatings have been related to the fine microstructures obtained, which are finer than those processed under similar heat input with welding techniques using wire feedstock. This observation suggests that the atomized feedstock plays a role on the solidification of coatings. In this study a model for the role of the powders grains in the solidification of PTA coatings is put forward and discussed. An experiment was setup to discuss the model which involved the deposition of an atomized Co-based alloy with different grain size distributions and deposition currents. X ray diffraction showed that there were no phase changes due to the processing parameters. Microstructure analysis by Laser Confocal Microscopy, dilution with the substrate steel and Vickers microhardness were used the characterized coatings and enriched the discussion confirming the role of the powdered feedstock on the solidification of coatings.

  7. Particle Size and Pore Structure Characterization of Silver Nanoparticles Prepared by Confined Arc Plasma

    Directory of Open Access Journals (Sweden)

    Mingru Zhou

    2009-01-01

    Full Text Available In the protecting inert gas, silver nanoparticles were successfully prepared by confined arc plasma method. The particle size, microstructure, and morphology of the particles by this process were characterized via X-ray powder diffraction (XRD, transmission electron microscopy (TEM and the corresponding selected area electron diffraction (SAED. The N2 absorption-desorption isotherms of the samples were measured by using the static volumetric absorption analyzer, the pore structure of the sample was calculated by Barrett-Joyner-Halenda (BJH academic model, and the specific surface area was calculated from Brunauer-Emmett-Teller (BET adsorption equation. The experiment results indicate that the crystal structure of the samples is face-centered cubic (FCC structure the same as the bulk materials, the particle size distribution ranging from 5 to 65 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 23.81 m2/g, pore volumes are 0.09 cm3/g, and average pore diameter is 18.7 nm.

  8. Deign of Experiment and Optimization of Plasma Transferred Arc Hardfacing on Structural Steel with Titanium Carbide

    Directory of Open Access Journals (Sweden)

    S. Balamurugan

    2014-03-01

    Full Text Available The aim of the Plasma Transferred Arc (PTA hardfacing process is improving a technical surface locally with a dedicated material; Hardfacing became an issue of intense development related to wear resistant application. The hardfacing procedures can be differentiated by the intensity of mixture with the base body, which is usually increasing along with an increasing fusion efficiency rate. Nearly all kinds of weldable materials can be hardfaced and mostly all types of known wear resistant metals in combination can be used as hardfacing materials. The PTA hardfacing process has been widely employed due to several advantages such as higher volume of metal deposition rates and achieving very low dilution level. Heat input which influences dilution can be controlled by proper selection of PTA process parameters. In this study, an attempt has been made to analyze PTA hardfacing of IS: 2062 structural steel with Titanium Carbide (TiC. Experiments were conducted based on a fully replicable five-factor, five-level central composite rotatable design. Mathematical models were developed using response surface methodology to study the effects of PTA hardfacing process parameters such as welding current, welding speed ,powder feed rate, oscillation width and pre heat temperature on bead geometry parameters like penetration, reinforcement, bead width and dilution. Direct and interaction effects of PTA process parameters on bead geometry were analyzed. From mathematical model, the process parameters were optimized.

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

    Directory of Open Access Journals (Sweden)

    Ganhua Lu

    2006-01-01

    Full Text Available Miniaturized 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 (SnO2 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.

  10. Repair of power generation components by laser and plasma transferred arc processes: procedures and qualification

    International Nuclear Information System (INIS)

    The power generation industry in Australia recognises the need to develop procedure guidelines for metal deposition processes to protect valuable and critical components used in steam power plants. The components are typically used in boilers and regulating valves and can be subjected to a range of types of wear. Although many of the components examined were already deposited with specific alloys in specific areas, they still exhibited a high degree of wear. The project focused on worn components which were deemed to have reached the end of their operating life. The procedure guidelines and selection of materials for the deposition process are expected to provide the options for re-use of the critical components for additional and longer service life compared to the original design. Several metal deposition processes were initially identified as potential repair processes for the refurbishment of various components. Two processes, laser and plasma transferred arc (PTA) deposition, were selected for the study. Laboratory trials were carried out to examine the performance of the coating and then the actual parts were repaired based on the laboratory results. A company specialising in the laser cladding repair of engineering components carried out the repair of a number of power station components, which were subsequently returned to the relevant power stations for service evaluation. The paper discusses the research conducted and presents the procedures developed to assist local power generators in selection of the most appropriate materials and parameters for the repair of worn components.

  11. Ion charge state distributions of pulsed vacuum arc plasmas in strong magnetic fields

    International Nuclear Information System (INIS)

    Vacuum arc plasmas with discharge currents of 300 A and duration 250 μs have been produced in strong magnetic fields up to 4 T. Ion charge state distributions have been measured for C, Al, Ag, Ta, Pt, Ho, and Er with a time-of-flight charge-mass spectrometer. Our previous measurements have been confirmed which show that ion charge states can be considerably enhanced when increasing the magnetic field up to about 1 T. The new measurements address the question of whether or not the additional increase continues at even higher magnetic field strength. It has been found that the increase becomes insignificant for field strengths greater than 1 T. Ion charge state distributions are almost constant for magnetic field strengths between 2 and 4 T. The results are explained by comparing the free expansion length with the freezing length. The most significant changes of charge state distributions are observed when these lengths are similar. copyright 1998 American Institute of Physics

  12. Ion charge state distributions of pulsed vacuum arc plasmas in strong magnetic fields

    International Nuclear Information System (INIS)

    Vacuum arc plasmas with discharge currents of 300 A and duration 250 μs have been produced in strong magnetic fields up to 4 T. Ion charge state distributions have been measured for C, Al, Ag, Ta, Pt, Ho, and Er with a time-of-flight charge-mass-spectrometer. Our previous measurements have been confirmed which show that ion charge states can be considerably enhanced when increasing the magnetic field up to about 1 T. The new measurements address the question of whether or not the additional increase continues at even higher magnetic field strength. It has been found that the increase becomes insignificant for field strengths greater than 1 T. Ion charge state distributions are almost constant for magnetic field strengths between 2 and 4 T. The results are explained by comparing the free expansion length with the freezing length. The most significant changes of charge state distributions are observed when these lengths are similar. copyright 1998 American Institute of Physics

  13. Development of an encapsulation method using plasma arc welding to produce iodine-125 seeds for brachytherapy

    International Nuclear Information System (INIS)

    The prostate cancer, which is the second cause of death by cancer in men, overcome only by lung cancer is public health problem in Brazil. Brachytherapy is among the possible available treatments for prostate cancer, in which small seeds containing Iodine-125 radioisotope are implanted into the prostate gland. The seed consists of a titanium sealed capsule with 0.8 mm external diameter and 4.5 mm length, containing a central silver wire with adsorbed Iodine-125. The Plasma Arc Welding (PAW) is one of the viable techniques for sealing process. The equipment used in this technique is less costly than in other processes, such as, Laser Beam Welding (LBW). The main purpose of this work was the development of an encapsulation method using PAW. The development of this work has presented the following phases: cutting and cleaning titanium tube, determination of the welding parameters, development of a titanium tube holding device for PAW, sealed sources validation according to ISO 2919 - Sealed Radioactive Sources - General Requirements and Classification, and metallographic assays. The developed procedure to seal Iodine-125 seeds using PAW has shown high efficiency, satisfying all the established requirements of ISO 2919. The results obtained in this work will give the possibility to establish a routine production process according to the orientations presented in resolution RDC 17 - Good Manufacturing Practices to Medical Products defined by the ANVISA - National Agency of Sanitary Surveillance. (author)

  14. Development of an encapsulation method using plasma arc welding to produce iodine-125 seeds for brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Feher, Anselmo; Calvo, Wilson A.P.; Rostelato, Maria E.C.M.; Zeituni, Carlos A.; Somessari, Samir L.; Costa, Osvaldo L.; Moura, Joao A.; Moura, Eduardo S.; Souza, Carla D.; Rela, Paulo R., E-mail: afeher@ipen.b, E-mail: wapcalvo@ipen.b, E-mail: elisaros@ipen.b, E-mail: somessar@ipen.b, E-mail: olcosta@ipen.b, E-mail: esmoura@ipen.b, E-mail: cdsouza@ipen.b, E-mail: prela@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The prostate cancer, which is the second cause of death by cancer in men, overcome only by lung cancer is public health problem in Brazil. Brachytherapy is among the possible available treatments for prostate cancer, in which small seeds containing Iodine-125 radioisotope are implanted into the prostate gland. The seed consists of a titanium sealed capsule with 0.8 mm external diameter and 4.5 mm length, containing a central silver wire with adsorbed Iodine-125. The Plasma Arc Welding (PAW) is one of the viable techniques for sealing process. The equipment used in this technique is less costly than in other processes, such as, Laser Beam Welding (LBW). The main purpose of this work was the development of an encapsulation method using PAW. The development of this work has presented the following phases: cutting and cleaning titanium tube, determination of the welding parameters, development of a titanium tube holding device for PAW, sealed sources validation according to ISO 2919 - Sealed Radioactive Sources - General Requirements and Classification, and metallographic assays. The developed procedure to seal Iodine-125 seeds using PAW has shown high efficiency, satisfying all the established requirements of ISO 2919. The results obtained in this work will give the possibility to establish a routine production process according to the orientations presented in resolution RDC 17 - Good Manufacturing Practices to Medical Products defined by the ANVISA - National Agency of Sanitary Surveillance. (author)

  15. Effect of electron-neutral collisions on the satellites of the Thompson scattering spectrum in arc plasmas

    International Nuclear Information System (INIS)

    The influence of electron-neutral collisions on the high frequency electron satellites of the Thompson-scattered electromagnetic radiation in an hydrogen arc plasma is investigated. As the general evaluation procedure of experimental scattering data uses only normalized intensities, one is particlulary interested in the change of position and halfwidth of the electron satellites whereas the effect of collisions on their size is of minor importance. The calculations are carried out along Gorog's theory solving the linearized Boltzmann equation. (Auth.)

  16. Effect Of Pulsed Current Micro Plasma Arc Welding Process Parameters On Fusion Zone Grain Size And Ultimate Tensile

    OpenAIRE

    Kondapalli Siva Prasad; Chalamalasetti Srinivasa Rao; Damera Nageswara Rao

    2012-01-01

    AISI 304L is an austenitic Chromium-Nickel stainless steel offering the optimum combination of corrosion resistance, strength and ductility. These attributes make it a favorite for many mechanical components. The low carbon content reduces susceptibility to carbide precipitation during welding. In case of single pass welding of thinner section of this alloy, pulsed current micro plasma arc welding was found beneficial due to its advantages over the conventional continuous current process. The...

  17. An experimental research to study the microwaves transmission characteristics of ablating material in arc-heated plasma flow

    International Nuclear Information System (INIS)

    An experimental research about the effect of ablating material on the reflection and the transmission of microwaves in arc-heated plasma flow is presented by using the C band microwave measuring system. The results show that the ablating material with accidented surface and its high temperature have remarkably affected the reflection and the transmission of microwaves. The experiment proves that the system has outstanding precision and reliability

  18. Effect of Fast Curing Lights, Argon Laser, and Plasma Arc on Bond Strengths of Orthodontic Brackets: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    M. Hashem-Hoseini

    2008-12-01

    Full Text Available Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland, the argon laser unit (Bo-5, Iran , and the plasma arc unit (Remecure 15, Belgium. The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek. After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany.Results: The mean bond strengths was 17.344 MPa (SD=4.567 for halogen 19.172 MPa(SD=6.328 for laser and 19.322 MPa (SD=4.036 for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light.

  19. Numerical and Experimental Investigation on the In-Flight Melting Behaviour of Granulated Powders in Induction Thermal Plasmas

    International Nuclear Information System (INIS)

    An innovative in-flight glass melting technology with thermal plasmas was developed for the purpose of energy conservation and environment protection. In this study, modelling and experiments of argon-oxygen induction thermal plasmas were conducted to investigate the melting behaviour of granulated soda-lime glass powders injected into the plasma. A two-dimensional local thermodynamic equilibrium (LTE) model was performed to simulate the heat and momentum transfer between plasma and particle. Results showed that the particle temperature was strongly affected by the flow rate of carrier gas and the particle size of raw material. A higher flow rate of carrier gas led to lower particle temperature and less energy transferred to particles which resulted in lower vitrification. The incomplete melting of large particles was attributed to the lower central temperature of the particle caused by a larger heat capacity. The numerical analysis explained well the experimental results, which can provide valuable practical guidelines for the process control in the melting process for the glass industry. (plasma technology)

  20. A thermodynamic analysis of solid waste gasification in the Plasma Gasification Melting process

    International Nuclear Information System (INIS)

    Highlight: • A thermodynamic analysis was conducted to evaluate the characteristics of the PGM. • Energy recovery using gas furnaces is suggested due to high total energy and exergy. • Gas turbines are not recommended due to high tar yield. • Increasing heat to the PGM is beneficial for cold gas energy and exergy efficiencies. • A small steam addition is beneficial for PGM energy and exergy efficiencies. - Abstract: Plasma Gasification Melting is a promising technology for solid waste treatment. In this work, a thermodynamic analysis has been conducted to evaluate the advantages and limitations of the PGM technology. According to the characteristics of the PGM, the whole process was divided into four sections such as drying, pyrolysis, char gasification and inorganics melting. The energy and exergy in each section has been calculated. According to different usage of syngas, two kinds of energy and exergy efficiencies are defined. The results show that the PGM process produces a tar-rich syngas. When considering the raw syngas (syngas with tar), the energy and exergy efficiency of PGM process is very high. The effects of operating conditions on the thermodynamic performance of the PGM process have been analyzed. Considering the energy and exergy of clean syngas, it is beneficial to increase sensible heat input to the PGM system. However, high sensible heat input or high steam injection is not suggested when considering the energy and exergy efficiency of raw syngas

  1. Modeling Arcs

    CERN Document Server

    Insepov, Zeke; Veitzer, Seth; Mahalingam, Sudhakar

    2011-01-01

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

  2. Gasification of municipal solid waste in the Plasma Gasification Melting process

    International Nuclear Information System (INIS)

    Highlights: ► 6 tests are conducted to study the performance of a PGM reactor. ► For air gasification, increasing ER will decrease syngas LHV value. ► Increasing ER will increase syngas yield and energy efficiency. ► High-temperature steam injection can significantly increase syngas yield. ► High-temperature steam injection will also increase syngas LHV value. -- Abstract: A new waste-disposal technology named Plasma Gasification Melting (PGM) was developed. A pilot PGM reactor was constructed in northern Israel. The reactor is an updraft moving-bed gasifier, with plasma torches placed next to air nozzles to heat the incoming air to 6000 °C. The inorganic substances of the feedstock are melted by the high-temperature air to form a vitrified slag in which undesirable materials such as heavy metals are trapped. The residual heat in the air supplies additional heat for the gasification process. A series of tests were conducted to study the performance of PGM gasification. The plasma power was varied from 2.88 to 3.12 MJ/kg of municipal solid waste (MSW), and the equivalence ratio (ER) was varied from 0.08 to 0.12. For air and steam gasification, the maximum steam/MSW mass ratio reached 0.33. The composition of the syngas product was analyzed in all tests; the lower heating value (LHV) of the syngas varied from 6 to 7 MJ/Nm3. For air gasification, the syngas LHV decreased with increasing ER, whereas the gas yield and energy efficiency increased with ER. When high-temperature steam was fed into the reactor, the overall gas yield was increased significantly, and the syngas LHV also increased slightly. The positive effect may be attributed to the steam reforming of tar. In air and steam gasification, the influence of increased ER on syngas LHV was negative, while the effect of increased plasma power was positive. The maximum energy efficiency of the tests reached 58%. The main energy loss was due to the formation of tar.

  3. Synchronous Japan Sea opening Miocene fore-arc volcanism in the Abukuma Mountains, NE Japan: An advancing hot asthenosphere flow versus Pacific slab melting

    Science.gov (United States)

    Yamamoto, Takahiro; Hoang, Nguyen

    2009-10-01

    During Japan Sea back-arc opening between 21 and 15 Ma, low-K tholeiitic basalts erupted in the Abukuma Mountains on the trench side of NE Japan. The basaltic rocks in this region are divided into two units by a hiatus. The lower unit consists of the 20 Ma Tenmyosan volcanic rocks, including many monogenetic basaltic volcanoes whose vents occur throughout the district. The upper unit is the Ryozen Formation that occurred at about 16 Ma. This Formation is composed of a subaerial basaltic polygenetic volcanic edifice, with a diameter of ca. 30 km. Minor amounts of andesitic and dacitic gravels occur in the distal portion of the Ryozen edifice. Low-K tholeiitic basalts of the Tenmyosan volcanic rocks and the Ryozen Formation have similar in major and trace element compositions. Their MgO content decrease from 13.2 to 3.4 wt.% with increasing incompatible element abundances and more pronounced negative Nb and Ta anomalies. Nd, Sr and Pb isotopic compositions of the Tenmyosan basalt display a range of values for SrI (0.7040-0.7050), NdI (0.5127-0.5129) and 206Pb/ 204Pb (18.2-18.5). These features suggest that the Tenmyosan monogenetic volcanism at the early stage of the Japan Sea opening was generated by intermittent ascent of minor mafic melts from heterogeneous sources. Isotopic data for the Ryozen basalt define a binary mixing trend between a depleted and enriched crust-like source, varying with SiO 2 content. These chemical changes show that, as the opening progressed, the asthenospheric source of the Ryozen basalts became more homogeneous and depleted (SrI; 0.7043, Nd; 0.5129, 206Pb/ 204Pb; 18.2), and continuous ascent of the basaltic melt was able to make a large magma chamber that was associated with significant crustal assimilation. On the other hand, hornblende dacite in the Ryozen Formation has SiO 2 contents between 66 and 74 wt.%, high Mg# from 41.7 to 54.3. The dacite also shows high Sr (417-650 ppm) and Sr/Y (35-112), and high La/Yb (12-20). Compared with

  4. Crustal melting and magma mixing in a continental arc setting: Evidence from the Yaloman intrusive complex in the Gorny Altai terrane, Central Asian Orogenic Belt

    Science.gov (United States)

    Chen, Ming; Sun, Min; Buslov, Mikhail M.; Cai, Keda; Zhao, Guochun; Kulikova, Anna V.; Rubanova, Elena S.

    2016-05-01

    Granitoids and their hosted mafic enclaves may retain important information on crust-mantle interaction, and thus are significant for study of crustal growth and differentiation. An integrated petrological, geochronological and geochemical study on the granitoid plutons of the Yaloman intrusive complex from the Gorny Altai terrane, northwestern Central Asian Orogenic Belt, was conducted to determine their source nature, petrogenesis and geodynamics. Mafic enclaves are common in the plutons, and a zircon U-Pb age (389 Ma ± 4 Ma) indicates that they are coeval with their granitoid hosts (ca. 393-387 Ma). Petrographic observations reveal that these mafic enclaves probably represent magmatic globules commingled with their host magmas. The relatively low SiO2 contents (46.0-60.7 wt.%) and high Mg# (38.9-56.5) further suggest that mantle-derived mafic melts served as a crucial component in the formation of these mafic enclaves. The granitoid hosts, including quartz diorites and granodiorites, are I-type in origin, possessing higher SiO2 contents (60.2-69.9 wt.%) and lower Mg# (32.0-44.2). Their zircon Hf and whole-rock Nd isotopic compositions indicate that the magmas were dominated by remelting of Neoproterozoic (0.79-1.07 Ga) crustal materials. Meanwhile, the geochemical modeling, together with the common occurrence of igneous mafic enclaves and the observation of reversely zoned plagioclases, suggests that magma mixing possibly contributed significantly to the geochemical variation of the granitoid hosts. Our results imply that mafic magmas from the mantle not only provided substantial heat to melt the lower crust, but also mixed with the crust-derived melts to form the diverse granitoids. The oxidizing and water-enriched properties inferred from the mineral assemblages and compositions imply that the granitoid plutons of the Yaloman intrusive complex were possibly formed in a continental arc-related setting, which is also supported by their geochemistry. The

  5. Steam explosion triggering phenomena: stainless steel and corium-E simulants studied with a floodable arc melting apparatus

    International Nuclear Information System (INIS)

    Laboratory-scale experiments on the thermal interaction of light water reactor core materials with water have been performed. Samples (10--35 g) of Type 304 stainless steel and Corium-E simulants were each flooded with approximately 1.5 litres of water to determine whether steam explosions would occur naturally. Many of the experiments also employed artificially induced pressure transients in an attempt to initiate steam explosions. Vigorous interactions were not observed when the triggering pulse was not applied, and for stainless steel the triggering pulse initiated only coarse fragmentation. Two-stage, pressure-producing interactions were triggered for an ''oxidic'' Corium-E simulant. An impulse-initiated gas release theory has been simulated to explain the initial sample fragmentation. Although the delayed second stage of the event is not fully understood, it does not appear to be readily explained with classical vapor explosion theory. Rather, some form of metastability of the melt seems to be involved

  6. Melting Decontamination of the Aluminum Wastes generated from TRIGA MARK-III Research Reactor in the Electric Arc Furnace

    International Nuclear Information System (INIS)

    Recently, there has been growing interest in D and D (Decommissioning and decontamination) of the nuclear facilities around world. In Korea the TRIGA MARK III research reactor has been dismantled since 1997. These decommissioning works result in the various metal wastes such as stainless steel, carbon steel, aluminum and copper. Since the total amount of the steel (stainless steel, carbon steel) wastes from nuclear facilities was up to 70 ∼ 80%, considerable researches have been devoted to the radionuclides distribution and decontamination characteristics of the steel until now. But based on the report by Garbay and Chapuis, they concluded that a PWR contained 20 to 100 ton of aluminum, mostly as electrical cable. Therefore rather more study has been paid to the characteristics of the aluminum melting and the distribution of radionuclides

  7. Melting Decontamination of the Aluminum Wastes generated from TRIGA MARK-III Research Reactor in the Electric Arc Furnace

    Energy Technology Data Exchange (ETDEWEB)

    Min, Byung Youn; Kang, Yong [Chungnam National University, Taejon (Korea, Republic of); Song, Pyung Seob; Choi, Wang Kyu; Jung, Chong Hun; Oh, Won Zin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2006-07-01

    Recently, there has been growing interest in D and D (Decommissioning and decontamination) of the nuclear facilities around world. In Korea the TRIGA MARK III research reactor has been dismantled since 1997. These decommissioning works result in the various metal wastes such as stainless steel, carbon steel, aluminum and copper. Since the total amount of the steel (stainless steel, carbon steel) wastes from nuclear facilities was up to 70 {approx} 80%, considerable researches have been devoted to the radionuclides distribution and decontamination characteristics of the steel until now. But based on the report by Garbay and Chapuis, they concluded that a PWR contained 20 to 100 ton of aluminum, mostly as electrical cable. Therefore rather more study has been paid to the characteristics of the aluminum melting and the distribution of radionuclides.

  8. Study on the plasma texturing for increasing the conversion efficiency of a solar cell with a DC arc plasmatron

    International Nuclear Information System (INIS)

    A novel arc plasma source with a very low anode erosion rate (∼10-10 g/C), a spectrally clean plasma flow and a lifetime of 103 ∼ 104 hours, was developed. A texturing process was performed on a crystalline silicon (c-Si) wafer to increase the efficiency of a solar cell. A pyramid shape was etched on the wafer's surface by using a high durability DC arc plasma source at atmospheric pressure and low pressure. CF4 and SF6 were used as the reactive etching gases at flow rates 2 as the supporting gas in the range of the 5 - 15%. To survey the characteristics of the pyramid formation process, plasma texturing experiments were performed by varying the working time. The optimal operating conditions of the gas flow (Ar, O2, CF4, SF6), plasmatron current and processing time were determined. The pyramid angle was approximately 50 .deg. to 60 .deg. when a single-crystalline silicon surface was textured in a vacuum whereas it was approximately 75 .deg. to 90 .deg. when textured at atmospheric pressure. The pyramid angle is related to the reflectance. The reflectance decreases with decreasing pyramid angle. The reflectance of the bare silicon ranged from 40% to the 60% but that of the textured silicon was approximately 5% to 20%. This reflectance is quite low, approximately half that reported by other studies using wet and Reactive ion etching (RIE) texturing. These results confirm that this novel arc plasma source can be used to texture a Si surface for applications to photo-voltaic devices.

  9. Method of plasma-arc welding and properties of welded joints of the 12Kh18N10T steel tubes

    International Nuclear Information System (INIS)

    The aim of the work was to improve the plasma-arc welding of 12Kh18N10T steel pipes for service at temperatures up to 350 deg C under cyclic loading. The quality of welds was checked by metallographic means and by tests for tensile and impact strengths, small-cycle fatigue and hardness. A method was developed for plasma-arc welding of pivoting pipe joints with wall thicknesses of 6-10 mm in a single pass without bevelling of edges and without additive. Welds made by the above procedure possess a higher resistance to failure as compared to manual electric-arc welds

  10. Modern alchemy : plasma-arc conversion of garbage into energy, water and aggregate is the stuff of science fiction, and it may be coming soon to the Red Deer dump

    Energy Technology Data Exchange (ETDEWEB)

    Stastny, P.

    2009-10-15

    Plasco Energy Group will now need to win government support for the construction of a new waste facility in Red Deer, Alberta. The Ottawa-based company uses a plasma waste conversion technology to generate electricity by refining hydrogen and carbon monoxide produced during the gasification process into a synthetic gas. An 85 ton per day demonstration plant has been operating in Ottawa since 2007. The average ton of municipal waste contains 13,000 mega joules of energy. The Plasco process will also help to treat waste water for release into the environment. The garbage is reduced to 1 per cent of its original volume after the water and gases are stripped away. The remaining garbage is melted with plasma arc torches for use as clean aggregates. The process also yields one and a half kg per ton of heavy metals. It was concluded that many cities are now showing an interest in the waste treatment technology. 1 fig.

  11. Search for novel amorphous alloys with high crystallization temperature by combinatorial arc plasma deposition

    International Nuclear Information System (INIS)

    This paper describes a combinatorial search for novel amorphous alloys with high crystallization temperatures (Tx) using combinatorial arc plasma deposition (CAPD). The CAPD technique can deposit 1089 (33 x 33) thin film samples with different compositions on a substrate at one time. These 1089 samples on the substrate are individually referred to as CAPD samples and collectively referred to as a thin film library. Thin film libraries of Ir-Zr-Fe, Ir-Zr-Al, Mo-Zr-Al, Mo-Zr-Si, Ru-Zr-Fe and Ru-Zr-Si were deposited by CAPD. The compositions and phases of the CAPD samples were measured by energy dispersive X-ray fluorescence spectrometry and X-ray diffractometry, respectively. The results revealed that each library included amorphous CAPD samples. Since it is impossible to measure the Tx, fracture strength, fracture strain and Young's modulus of the CAPD samples by conventional measurement methods, larger samples having the same compositions as the amorphous CAPD samples were fabricated by a sputtering system. Since all CAPD samples of Ir-Zr-Fe and Ir-Zr-Al were too brittle, their corresponding sputter-deposited samples were not prepared. Sputter-deposited Mo-Zr-Al, Mo-Zr-Si, Ru-Zr-Fe and Ru-Zr-Si samples with ∼50 at.% Mo- or Ru-content were fabricated, and Tx and mechanical properties of these sputter-deposited samples were evaluated. All the sputter-deposited samples of Mo-Zr-Al and Mo-Zr-Si showed high Tx exceeding 973 K and as well as brittle characteristics. Ru50Zr35Fe10 samples showed high Tx exceeding 1273 K and a low fracture strength of 0.26 GPa. Samples of Ru51Zr5Si44 showed a high Tx of 923 K and a high fracture strength of 1.25 GPa

  12. Adding high time resolution to charge-state-specific ion energy measurements for pulsed copper vacuum arc plasmas

    CERN Document Server

    Tanaka, Koichi; Zhou, Xue; Anders, André

    2015-01-01

    Charge-state-resolved ion energy-time-distributions of pulsed Cu arc plasma were obtained by using direct (time dependent) acquisition of the ion detection signal from a commercial ion mass-per-charge and energy-per-charge analyzer. We find a shift of energies of Cu2+, Cu3+ and Cu4+ ions to lower values during the first few hundred microseconds after arc ignition, which is evidence for particle collisions in the plasma. The generation of Cu1+ ions in the later part of the pulse, measured by the increase of Cu1+ signal intensity and an associated slight reduction of the mean charge state point to charge exchange reactions between ions and neutrals. At the very beginning of the pulse, when the plasma expands into vacuum and the plasma potential strongly fluctuates, ions with much higher energy (over 200 eV) were observed. Early in the pulse, the ion energies observed are approximately proportional to the ion charge state, and we conclude that the acceleration mechanism is primarily based on acceleration in an e...

  13. Plasma synthesis of titanium nitride, carbide and carbonitride nanoparticles by means of reactive anodic arc evaporation from solid titanium

    International Nuclear Information System (INIS)

    Plasma methods using the direct evaporation of a transition metal are well suited for the cost-efficient production of ceramic nanoparticles. In this paper, we report on the development of a simple setup for the production of titanium-ceramics by reactive anodic arc evaporation and the characterization of the aerosol as well as the nanopowder. It is the first report on TiCXN1 − X synthesis in a simple anodic arc plasma. By means of extensive variations of the gas composition, it is shown that the composition of the particles can be tuned from titanium nitride over a titanium carbonitride phase (TiCXN1 − X) to titanium carbide as proven by XRD data. The composition of the plasma gas especially a very low concentration of hydrocarbons around 0.2 % of the total plasma gas is crucial to tune the composition and to avoid the formation of free carbon. Examination of the particles by HR-TEM shows that the material consists mostly of cubic single crystalline particles with mean sizes between 8 and 27 nm

  14. Calculation of net emission coefficient of electrical discharge machining arc plasmas in mixtures of nitrogen with graphite, copper and tungsten

    Science.gov (United States)

    Adineh, V. R.; Coufal, O.; Bartlova, M.

    2015-10-01

    This work reports theoretical calculations of electrical discharge machining (EDM) radiative properties for mixture systems of N2-C, N2-Cu and N2-W arc plasmas, in the temperature range of 3000-10 000 K, and at 1 and 10 bar pressures. Radiative properties are computed for various plasma sizes as well as vapour proportions. Calculations consider line overlapping with spectrum coverage from 30 to 10 000 nm. Doppler, Natural, Van-der-Waals, Resonance and Stark broadening are taken into account as the line broadening mechanisms. Besides, continuum calculations consider bound-free and free-free emissions along with molecular bands radiation for selected molecular systems. Results show that contamination vapours of EDM electrode have strong influence on the amount of EDM plasma radiation to the surrounding environment. However, comparison of impurities from workpiece with electrode one indicates that Fe vapour has stronger impact on modifying the EDM arc plasma radiative properties, compared to the C, Cu and W species studied in this research.

  15. Steam explosion triggering phenomena: stainless steel and corium-E simulants studied with a floodable arc melting apparatus. [BWR; PWR

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, L.S.; Buxton, L.D.

    1978-05-01

    Laboratory-scale experiments on the thermal interaction of light water reactor core materials with water have been performed. Samples (10--35 g) of Type 304 stainless steel and Corium-E simulants were each flooded with approximately 1.5 litres of water to determine whether steam explosions would occur naturally. Many of the experiments also employed artificially induced pressure transients in an attempt to initiate steam explosions. Vigorous interactions were not observed when the triggering pulse was not applied, and for stainless steel the triggering pulse initiated only coarse fragmentation. Two-stage, pressure-producing interactions were triggered for an ''oxidic'' Corium-E simulant. An impulse-initiated gas release theory has been simulated to explain the initial sample fragmentation. Although the delayed second stage of the event is not fully understood, it does not appear to be readily explained with classical vapor explosion theory. Rather, some form of metastability of the melt seems to be involved.

  16. Development of a plasma-arc-cutting technology like a mechanical saw for atmosphere and under water for dismantling nuclear components of greater thickness

    International Nuclear Information System (INIS)

    Status of research: With the plasma arc cutting it is until now not possible to cut steel under water which is thicker than 100 mm. In a depth of water of 20 m it is only possible to cut steel up to 80 mm. This is not enough for the dismantling technology. Aim of research work: Plasma arc cutting technology should be developed to enable cutting a plate independent of its thickness. Method of research: A plasma-arc-saw has been developed for a thermal cutting of materials, similar to a mechanical saw. To develop and optimize the special nozzles of the plasma-arc-saw the submerged combustion burner has been developed parallel by the arc-saw. Results: There are no problems of thermal cutting a steel independent of its thickness. The thickness of the plate depends only on the diameter of the saw disc. The water depth of 20 m reduced the cutting speed of 10%. The plasma-arc-saw enables thermal cutting of a plate independent of its thickness in a water depth of 20 m without requiring a force. The remote controlled dismantling of a reactor vessel and other components with greater wall thickness is possible. (orig./HP) With 21 refs., 6 tabs., 87 figs

  17. Correlation between microstructure, magnetic and electronic properties of Fe1-xAlx (0.2 ≤ x ≤ 0.6) alloys produced by arc melting

    International Nuclear Information System (INIS)

    In the present manuscript the authors have systematically investigated the structural, magnetic and electronic properties of a series of arc melted Fe1-xAlx (0.2 ≤ x ≤ 0.6) alloys using XRD, VSM, resistivity and XPS techniques. Structural studies show that all the samples are textured mainly along (1 1 0) direction, the crystallize size decreases with increase in Al content and also that the samples are not uniformly alloyed even though they have been annealed at 600 deg. C for 120 h. The corresponding magnetic measurements show that the saturation magnetization decreases with x. This is attributable to a competition between nearest neighbour Fe-Fe ferromagnetic exchange and an indirect FeAl anti-ferromagnetic interaction. On the other hand resistivity increases with x and found to be maximum at x = 0.4. Further addition of Al leads to a decrease in the electrical resistivity. The corresponding XPS measurements also show modification in the core level as well as VB spectra of the samples. The observed changes can be attributed to the continuous change in electronic structure due to constant increase of Fe 3d and Al 3sp hybridization near Fermi level accompanied by an increased delocalization of the d-electrons participating in the strong bonding of Fe with Al.

  18. Application of wall-stabilized plasma arc for the spectrometric determination of impurity elements in uranium yellow cake

    International Nuclear Information System (INIS)

    The application of a seeded wall-stabilized argon plasma arc as an excitation source for the emission spectrometric determination of some impurity elements in a sample of uranium yellow cake has been investigated. The sample was dissolved in nitric acid. Uranium was extracted from the sample solution using tributyl phosphate (TBP), and the aqueous solution was injected into the arc. The elements determined were Al, Ca, Fe, Mg, Mn, Mo, Sr and Zr. Limits of detection and precision of the technique are presented. The study of the influence of residual uranium in the nebulized solution on the intensity of spectral lines revealed that uranium concentrations up to 100 μg mL-1 have no significant interfering effect

  19. Three-phase plasma arc atomic-emission spectrometric analysis of environmental samples using an ultrasonic nebulizer

    Energy Technology Data Exchange (ETDEWEB)

    Ghatass, Zekry F. [Institute of Graduate Studies and Research, Alexandria University, 163 El-Horreya Avenue, P.O. Box 832, Chatby 21526, Alexandria (Egypt); Roston, Gamal D. [Department of Physics, Faculty of Science, Alexandria University, Alexandria (Egypt); Mohamed, Moustafa M. [Medical Research Institute, Alexandria University, Alexandria (Egypt)

    2003-06-01

    Combination of an ultrasonic nebulizer and plasma excitation sources for spectrochemical analysis offers desirable features of low detection limits, high sample throughput, wide dynamic range of operation, acceptable precision and accuracy, and simultaneous quantitative analytical capabilities. Moreover, the ultrasonic nebulizer does not require sample preconcentration. Recently we have developed a three-phase plasma arc (TPPA) for atomic emission spectrochemical analysis. In the present work, to increase the analytical utility of the three-phase plasma system, an ultrasonic nebulizer was used for sample introduction. The effects of the argon gas flow rate, current, excitation temperature have been studied. The analytical calibration curves are obtained for Ca, Cr, Fe, Mg and Mn, and detection limits have been calculated. The present technique is used to determine the concentration of the elements Ca, Cr, Fe, Mg and Mn in airborne samples. (orig.)

  20. Surface properties of plasma-functionalized graphite-encapsulated gold nanoparticles prepared by a direct current arc discharge method

    Science.gov (United States)

    Yang, Enbo; Chou, Han; Tsumura, Shun; Nagatsu, Masaaki

    2016-05-01

    The graphite-encapsulated gold nanoparticles (Au@C NPs) fabricated by a direct current arc discharge method were surface-functionalized by an inductively-coupled radio frequency ammonia plasma with a particle explosion technique for enhancing surface modification efficiency. To investigate the structural and surface properties of Au@C NPs, characterizations using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscopy have been conducted on the untreated and plasma treated Au@C NPs. Based on the experimental results, we give insight into the possible formation of Au ions in the interface between the graphite layers and gold core particles of the Au@C NPs. Finally, the role of the plasma treatment on the surface functionalization of Au@C NPs with amino groups is discussed.

  1. On local thermal equilibrium and potential gradient vs current characteristic in wall-stabilized argon plasma arc at 0.1 atm pressure

    International Nuclear Information System (INIS)

    In wall-stabilized arc which is a very useful means for determining the transport characteristics of high temperature gases, it is the premise that the inside of arc column is in complete local thermal equilibrium (LTE). In general, the higher the gas pressure, the easier the establishment of LTE, accordingly the experimental investigations on the characteristics of arc discharge as well as the transport characteristics so far were limited to the region of relatively high pressure. However, the authors have found that the theoretical potential vs. current characteristic obtained by the transport characteristic was greatly different from the actually measured one in low pressure region, as the fundamental characteristic of wall-stabilized argon plasma arc below atmospheric pressure. This time, they have clarified this discrepancy at 0.1 atm using the plasma parameters obtained through the spectroscopic measurements. The spectroscopic measurements have been performed through the side observation window at the position 5.5 cm away from the cathode, when arc was ignited vertically at the electrodes distant by 11 cm. Arc radius was 0.5 cm. Electron density and temperature, gas temperature and the excitation density of argon neutral atoms have been experimentally measured. The investigations showed that, in the region of low arc current, where the ratio of current to arc radius is less than 200 A/cm, the fall of gas temperature affected greatly on the decrease of axial electric field of arc column. The non-equilibrium between electron temperature and gas temperature decreased with the increase of arc current, and it was concluded that LTE has been formed at the center portion of arc column above I/R = 300 A/cm. (Wakatsuki, Y.)

  2. Deposition of thin layers of boron nitrides and hydrogenated microcrystalline silicon assisted by high current direct current arc plasma

    International Nuclear Information System (INIS)

    In the frame of this thesis, a high current direct current arc (HCDCA) used for the industrial deposition of diamond, has been adapted to study the deposition of two types of coatings: a) boron nitride, whose cubic phase is similar to diamond, for tribological applications, b) hydrogenated microcrystalline silicon, for applications in the semiconductor fields (flat panel displays, solar cells,...). For the deposition of these coatings, the substrates were placed in the diffusion region of the arc. The substrate heating is mainly due to atomic species recombining on its surface. The deposition temperature, varying from 300 to 900 oC according to the films deposited, is determined by the substrate position, the arc power and the injected gas fluxes, without the use of any external heating or cooling system. Measurements performed on the arc plasma show that the electronic temperature is around 2 eV (23'000 K) while the gas temperature is lower than 5500 K. Typical electronic densities are in the range of 1012-101'3 cm-3. For the deposition of boron nitride films, different boron precursors were used and a wide parameter range was investigated. The extreme difficulty of synthesising cubic boron nitride films by chemical vapour deposition (CVD) did not allow to stabilize the cubic phase of boron nitride in HCDCA. Coatings resulted in hexagonal or amorphous boron nitride with a chemical composition close to stoichiometric. The presence of hydrogen leads to the deposition of rough and porous films. Negative biasing of the samples, for positive ion bombardment, is commonly used to stabilize the cubic phase. In HCDCA and in our biasing range, only a densification of the films could be observed. A boron nitride deposition plasma study by infrared absorption spectroscopy in a capacitive radio frequency reactor has demonstrated the usefulness of this diagnostic for the understanding of the various chemical reactions which occur in this kind of plasma. Diborane dissociation

  3. NUMERICAL MODELING OF HEAT TRANSFER AND FLUID FLOW IN KEYHOLE PLASMA ARC WELDING OF DISSIMILAR STEEL JOINTS

    Directory of Open Access Journals (Sweden)

    M. A. Daha

    2012-02-01

    Full Text Available The evolution of temperature profiles and weld pool geometry during dissimilar welding between 2205 duplex stainless steel and A36 low carbon steel using keyhole plasma arc welding has been simulated using a three dimensional numerical heat transfer and fluid flow model. An adaptive heat source is proposed as a heat source model for performing a non-linear transient thermal analysis, based on the configuration feature of keyhole plasma arc welds. Temperature profiles and solidified weld pool geometry are presented for three different welding heat input. The reversed bugle shape parameters (width of fusion zone at both top and bottom surfaces of the weld pool geometry features for a dissimilar 2205–A36 weld joint are summarized to successfully explain the observations. The model was also applied to keyhole plasma welding of 6.8 mm thick similar 2205 duplex stainless steel joint for validation. The simulation results were compared with independently obtained experimental data and good agreements have been obtained.

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

    International Nuclear Information System (INIS)

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

  5. Performance analysis of municipal solid waste gasification with steam in a Plasma Gasification Melting reactor

    International Nuclear Information System (INIS)

    Highlights: ► A process simulation model was used to simulate the PGM. ► Heat supply from both plasma and internal combustion is beneficial for PGM due to favored tar cracking. ► Steam injection has positive effects on syngas yield and LHV. ► The optimal syngas LHV can be obtained at PER = 0.14, SAMR = 0.8 and ER = 0.055. -- Abstract: Plasma Gasification Melting (PGM) is a novel gasification technology which offers a promising treatment of low-heating-value fuels like municipal solid waste (MSW), medical waste (MW) and other types of waste. By considering the differences in pyrolysis characteristics between cellulosic fractions and plastics in MSW, a semi-empirical model was developed to predict the performance of the PGM process. The measured results of MSW air and steam gasification in a PGM demo-reactor are demonstrated and compared with the model predicted results. Then, the effects of dimensionless operation parameters (ER, PER, and SAMR) are discussed. It was found that all three numbers have positive effects on system cold gas efficiency (CGE). The reasons can be attributed to promoted tar cracking by enhanced heat supply. The effects of PER and ASME on syngas LHV are also positive. The influence of ER on syngas pyrolysis can be divided into two parts. When 0.04 < ER < 0.065, the effect of ER is on LHV positive; when 0.065 < ER < 0.08, the effect of ER is positive. This phenomenon was explained by two contradictory effects of ER. It is also found that interactions exist between operation parameters. For example, increasing PER narrows the possible range of ER while increasing SAMR broadens possible ER range. Detail extents for those operation parameters are demonstrated and discussed in this paper. Finally, the optimal point aiming at obtaining maximum syngas LHV and system CGE are given.

  6. Photoelectron Emission from Metal Surfaces Induced by VUV-emission of Filament Driven Hydrogen Arc Discharge Plasma

    CERN Document Server

    Laulainen, J; Koivisto, H; Komppula, J; Tarvainen, O

    2015-01-01

    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.

  7. Application of Response Surface Methodolody to Prediction of Dilution in Plasma Transferred Arc Hardfacing of Stainless Steel on Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    V Balasubramanian; A K Lakshminarayanan; R Varahamoorthy; S Babu

    2009-01-01

    The application of.response surface methodology was highlighted to predict and optimize the percentage of dilution of iron-based hardfaced surface produced by the PTA (plasma transferred arc welding) process.The experiments were conducted based on five-factor five-level central composite rotatable design with full replication technique and a mathematical model was developed using response surface methodology.Furthermore,the response surface methodology was also used to optimize the process parameters that yielded the lowest percentage of dilution.

  8. Integrated parametric study of a hybrid-stabilized argon–water arc under subsonic, transonic and supersonic plasma flow regimes

    Czech Academy of Sciences Publication Activity Database

    Jeništa, Jiří; Takana, H.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; Křenek, Petr; Hrabovský, Milan; Kavka, Tetyana; Sember, Viktor; Mašláni, Alan

    2011-01-01

    Roč. 44, č. 43 (2011), s. 435204-435204. ISSN 0022-3727 R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : hybrid-stabilized electric arc * mass flow rate * net emission coefficients * partial characteristics * Mach number * shock diamonds Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.544, year: 2011 http://iopscience.iop.org/0022-3727/44/43/435204/pdf/0022-3727_44_43_435204.pdf

  9. Entrainment of Ambient Air into H2O/ArDC Arc Plasma Jet

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Hrabovský, Milan; Konrád, Miloš; Kopecký, Vladimír; Sember, Viktor

    Bari : Department of Chemistry, University of Bari, 2003 - (d'Agostino, R.; Favia, P.; Fracassi, F.; Palumbo, F.). s. 99 [International Symposium on Plasma Chemistry/16th./. 22.06.2003-27.06.2003, Taormina] Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma jet, thermal plasma Subject RIV: BL - Plasma and Gas Discharge Physics

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Koichi, E-mail: tanak@mmc.co.jp [Central Research Institute, Mitsubishi Materials Corporation, 1002-14 Mukohyama, Naka-shi, Ibaraki 311-0102 (Japan); Anders, André [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 53, Berkeley, California 94720 (United States)

    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.

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

    International Nuclear Information System (INIS)

    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.

  13. Bioactivity of CaO-MgO-SiO2 glass ceramics synthesized using transferred arc plasma (TAP) process

    International Nuclear Information System (INIS)

    Glass ceramic with a nominal composition of 35.6% CaO, 12.8% MgO and 51.6% SiO2 was prepared by transferred arc plasma processing. The in vitro bioactivity of the plasma synthesized CaO-MgO-SiO2 glass ceramic was examined for its biomedical applicability which was evaluated by immersion in simulated body fluid at 36.5 deg. C for several days. The apatite particles were found to be formed on the surface of the glass ceramic and grew with the passage of soaking time. The simulated body fluid test results showed the formation of carbonated hydroxyapatite like layer on the surface of the glass ceramic. The cytocompatibility was evaluated through human fibroblast proliferation. The fibroblasts adhere, spread, and proliferate on the CaO-MgO-SiO2 glass ceramic, and the cell proliferation was more obvious.

  14. Application of a wall-stabilized argon plasma arc for the determination of some volatile hydride-forming elements

    Energy Technology Data Exchange (ETDEWEB)

    Eid, M.A. [Spectroscopy Department, National Research Centre, Dokki, Cairo (Egypt)]. E-mail: profmaeid@yahoo.com; Moustafa, H.R. [Physics Department, Faculty of Science, Girls Branch, Al Azhar University, Cairo (Egypt); Al Ashkar, E.A. [Spectroscopy Department, National Research Centre, Dokki, Cairo (Egypt); Ali, S.S. [Spectroscopy Department, National Research Centre, Dokki, Cairo (Egypt)

    2006-04-15

    Volatile hydrides of As, Se, Sb and Sn, produced by a continuous manifold hydride generator, have been swept with argon and injected into the plasma of home-made direct current wall-stabilized argon plasma arc via one of its stabilizing segments. The arc burns in argon with an arc current of 20 A and a cathode-anode voltage of 40 V. Measurements were carried out using a 1 m focal length computer-controlled monochromator (Jobin Yvon 1000R) equipped with a holographic grating having 2400 grooves mm{sup -1}. Optimal values of the experimental variables that give the highest value of intensity ratio of line-to-background were determined. These are: plasma gas flow rate 1.0 l min{sup -1}, carrier gas flow rate 0.35 l min{sup -1} for As and Sb and 0.6 l min{sup -1} for Se and Sn, concentration of nitric acid used for acidification of the sample 2 M for As and Sb, 0.5 M for Se and 0.1 M for Sn and sodium borohydride concentration: 1.5% for As and Se and 2% for Sb and Sn. Chemical interference of some transition elements that affect the hydride generation process and a trial to mask their interference effect were investigated. Calibration curves were linear and limits of detection calculated on the base of 3{sigma} of the background were found to be as low as 3.9, 6.8, 9.8 and 13.2 ng ml{sup -1} for As, Se, Sb and Sn, respectively. Finally, the analytical applicability of the arc device was tested by the determination of As in four lake sediment samples, LKSD 1, LKSD 2, LKSD 3 and LKSD 4, of the Centre for Mineral and Energy Technology, Ottawa, Ontario, Canada, which have been analyzed for As using atomic absorption spectrometry (AAS). The results were in good agreement with those obtained by AAS.

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

    Science.gov (United States)

    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.

  16. Electric arc hydrogen heaters

    International Nuclear Information System (INIS)

    The experimental data on the electric arc burning in hydrogen are presented. Empirical and semiempirical dependences for calculating the arc characteristics are derived. An engineering method of calculating plasma torches for hydrogen heating is proposed. A model of interaction of a hydrogen arc with a gas flow is outlined. The characteristics of plasma torches for heating hydrogen and hydrogen-bearing gases are described. (author)

  17. In situ multi-element analysis of the Mount Pinatubo quartz-hosted melt inclusions by NIR femtosecond laser ablation-inductively coupled plasma-mass spectrometry

    OpenAIRE

    A. Y. Borisova; Freydier, R.; Polvé, Mireille; Salvi, S; F. Candaudap; Aigouy, T.

    2008-01-01

    Microscopic melt inclusions found in magmatic minerals are undoubtedly one of the most important sources of information on the chemical composition of melts. This paper reports on the successful application of near-infrared (NIR) femtosecond laser ablation (LA) - inductively coupled plasma-mass spectrometry to in situ determination of incompatible trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Ta, Th, U) and ore metals (As, Mo, Pb) in individual melt inclusions hosted in quartz from the ...

  18. Behaviour of radionuclides during accidental melting of orphan sources in electric arc furnaces by means of C.F.D. gas flow modeling

    International Nuclear Information System (INIS)

    The appearance of orphan sources in steelmaking facilities has become a fact nowadays. Radiation sources, hidden within the scrap, may come into the scrap yard and become part of the melting. As a result, dispersion of the radioactive material that makes up the source takes place throughout the facility. The University of the Basque Country (U.P.V.-E.H.U.), in collaboration with the Empresa Nacional de Residuos Radiactivos, S.A. (E.N.R.E.S.A.) and the Consejo de Seguridad Nuclear (C.S.N.), has carried out a Research Project to analyze this accidental melting of radioactive sources in electric arc furnaces (E.A.F.). The whole steelmaking process can be analyzed in several discrete phases. Radioactive sources that may be incorporated to this process will be exposed to the different critical conditions prevailing during each phase. In this sense, Computational Fluid Dynamics (C.F.D.) has been used in order to recreate such conditions and so, determine the characteristics of the dispersion of radioactivity. Two different situations have been studied in detail using C.F.D. techniques: thermal conditions around a scrap-basket that contains the source just before entering the furnace and the deposition of steelmaking dust containing 137Cs on the inner surface of flue pipes. Before entering the furnace, scrap is usually placed inside a basket that remains above the furnace during some time. Once the furnace is open the scrap is dropped into the furnace to complete the loading process. C.F.D. techniques have been used to analyze the thermal conditions around the basket in order to assess the possibility of a break of the radioactive source hidden within the scrap, concluding that commercial sources will maintain their integrity during the whole loading process. On the other hand, after entering the furnace dispersion of the radioactive material will take place. Physical and chemical properties of the active elements (chemical form, composition, melting point, etc.) together

  19. Behaviour of radionuclides during accidental melting of orphan sources in electric arc furnaces by means of C.F.D. gas flow modeling

    Energy Technology Data Exchange (ETDEWEB)

    Penalva, I.; Damborenea, J.; Legarda, F. [University of the Basque Country, Nuclear Engineering and Fluids Mechanics (Spain); Zuloaga, P.; Ordonez, M. [Empresa Nacional de Residuos Radiactivos, SA (ENRESA), Madrid (Spain); Serrano, I. [Consejo de Seguridad Nuclear, Madrid (Spain)

    2006-07-01

    The appearance of orphan sources in steelmaking facilities has become a fact nowadays. Radiation sources, hidden within the scrap, may come into the scrap yard and become part of the melting. As a result, dispersion of the radioactive material that makes up the source takes place throughout the facility. The University of the Basque Country (U.P.V.-E.H.U.), in collaboration with the Empresa Nacional de Residuos Radiactivos, S.A. (E.N.R.E.S.A.) and the Consejo de Seguridad Nuclear (C.S.N.), has carried out a Research Project to analyze this accidental melting of radioactive sources in electric arc furnaces (E.A.F.). The whole steelmaking process can be analyzed in several discrete phases. Radioactive sources that may be incorporated to this process will be exposed to the different critical conditions prevailing during each phase. In this sense, Computational Fluid Dynamics (C.F.D.) has been used in order to recreate such conditions and so, determine the characteristics of the dispersion of radioactivity. Two different situations have been studied in detail using C.F.D. techniques: thermal conditions around a scrap-basket that contains the source just before entering the furnace and the deposition of steelmaking dust containing {sup 137}Cs on the inner surface of flue pipes. Before entering the furnace, scrap is usually placed inside a basket that remains above the furnace during some time. Once the furnace is open the scrap is dropped into the furnace to complete the loading process. C.F.D. techniques have been used to analyze the thermal conditions around the basket in order to assess the possibility of a break of the radioactive source hidden within the scrap, concluding that commercial sources will maintain their integrity during the whole loading process. On the other hand, after entering the furnace dispersion of the radioactive material will take place. Physical and chemical properties of the active elements (chemical form, composition, melting point, etc

  20. Effects of arc current modulation on dominant oscillations in plasma jet

    Czech Academy of Sciences Publication Activity Database

    Gruber, Jan; Hlína, Jan; Šonský, Jiří

    Orleans: University of Orleans, 2014, s. 418-421. ISBN 978-2-9548207-3-6. [International Conference on Gas Discharges and their Applications /20./. Orleans (FR), 06.07.2014-11.07.2014] Institutional support: RVO:61388998 Keywords : thermal plasma jets * current modulation * plasma torch Subject RIV: BL - Plasma and Gas Discharge Physics

  1. INFLUENCE OF SHROUD GAS ON DC ARC PLASMA JET AND INJECTED PARTICLES

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Chumak, Oleksiy; Kopecký, Vladimír; Hrabovský, Milan

    Bruges, 2005, s. 89-92. ISBN 908086692X. [International Workshop on Cold Atmospheric Pressure Plasmas: Sources and Applications/2nd./. Bruges (BE), 03.08.2005-02.09.2005] Institutional research plan: CEZ:AV0Z20430508 Keywords : thermal plasma jet * entrainment * shroud gas * particles oxidation Subject RIV: BL - Plasma and Gas Discharge Physics

  2. Study of Nanodispersed Iron Oxides Produced in Steel Drilling by Contracted Electric-Arc Air Plasma Torch

    Institute of Scientific and Technical Information of China (English)

    P. STEFANOV; D. GALANOV; G. VISSOKOV; D. PANEVA; B. KUNEV; I. MITOV

    2008-01-01

    The optimal conditions on the plasma-forming gas flowrate, discharge current and voltage, distance between the plasma-torch nozzle and the metal plate surface for the process of penetration in and vaporization of steel plates by the contracted electric-arc air plasma torch accompanied by water quenching, were determined. The X-ray structural and phase studies as well as M6ssbauer and electron microscope studies on the samples treated were performed. It was demonstrated that the vaporized elemental iron was oxidized by the oxygen present in the air plasma jet to form iron oxides (wiistite, magnetite, hematite), which, depending on their mass ra-tios, determined the color of the iron oxide pigments, namely, beginning from light yellow, through deep yellow, light brown, deep brown, violet, red-violet, to black. A high degree of dispersity of the iron oxides is thus produced, with an averaged diameter of the particles below 500 nm, and their defective crystal structure form the basis of their potential application as components of iron-containing catalysts and pigments.

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

    Science.gov (United States)

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

    2016-06-01

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

  4. Surface cracking and melting of different tungsten grades under transient heat and particle loads in a magnetized coaxial plasma gun

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y., E-mail: ykikuchi@eng.u-hyogo.ac.jp [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Sakuma, I.; Iwamoto, D.; Kitagawa, Y.; Fukumoto, N.; Nagata, M. [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Ueda, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2013-07-15

    Surface damage of pure tungsten (W), W alloys with 2 wt.% tantalum (W–Ta) and vacuum plasma spray (VPS) W coating on a reduced activation material of ferritic steel (F82H) due to repetitive ELM-like pulsed (∼0.3 ms) deuterium plasma irradiation has been investigated by using a magnetized coaxial plasma gun. Surface cracks appeared on a pure W sample exposed to 10 plasma pulses of ∼0.3 MJ m{sup −2}, while a W–Ta sample did not show surface cracks with similar pulsed plasma irradiation. The energy density threshold for surface cracking was significantly increased by the existence of the alloying element of tantalum. No surface morphology change of a VPS W coated F82H sample was observed under 10 plasma pulses of ∼0.3 MJ m{sup −2}, although surface melting and cracks in the resolidification layer occurred at higher energy density of ∼0.9 MJ m{sup −2}. There was no indication of exfoliation of the W coating from the substrate of F82H after the pulsed plasma exposures.

  5. Surface cracking and melting of different tungsten grades under transient heat and particle loads in a magnetized coaxial plasma gun

    Science.gov (United States)

    Kikuchi, Y.; Sakuma, I.; Iwamoto, D.; Kitagawa, Y.; Fukumoto, N.; Nagata, M.; Ueda, Y.

    2013-07-01

    Surface damage of pure tungsten (W), W alloys with 2 wt.% tantalum (W-Ta) and vacuum plasma spray (VPS) W coating on a reduced activation material of ferritic steel (F82H) due to repetitive ELM-like pulsed (˜0.3 ms) deuterium plasma irradiation has been investigated by using a magnetized coaxial plasma gun. Surface cracks appeared on a pure W sample exposed to 10 plasma pulses of ˜0.3 MJ m-2, while a W-Ta sample did not show surface cracks with similar pulsed plasma irradiation. The energy density threshold for surface cracking was significantly increased by the existence of the alloying element of tantalum. No surface morphology change of a VPS W coated F82H sample was observed under 10 plasma pulses of ˜0.3 MJ m-2, although surface melting and cracks in the resolidification layer occurred at higher energy density of ˜0.9 MJ m-2. There was no indication of exfoliation of the W coating from the substrate of F82H after the pulsed plasma exposures.

  6. Surface cracking and melting of different tungsten grades under transient heat and particle loads in a magnetized coaxial plasma gun

    International Nuclear Information System (INIS)

    Surface damage of pure tungsten (W), W alloys with 2 wt.% tantalum (W–Ta) and vacuum plasma spray (VPS) W coating on a reduced activation material of ferritic steel (F82H) due to repetitive ELM-like pulsed (∼0.3 ms) deuterium plasma irradiation has been investigated by using a magnetized coaxial plasma gun. Surface cracks appeared on a pure W sample exposed to 10 plasma pulses of ∼0.3 MJ m−2, while a W–Ta sample did not show surface cracks with similar pulsed plasma irradiation. The energy density threshold for surface cracking was significantly increased by the existence of the alloying element of tantalum. No surface morphology change of a VPS W coated F82H sample was observed under 10 plasma pulses of ∼0.3 MJ m−2, although surface melting and cracks in the resolidification layer occurred at higher energy density of ∼0.9 MJ m−2. There was no indication of exfoliation of the W coating from the substrate of F82H after the pulsed plasma exposures

  7. Evaluation of the three-phase, electric arc melting furnace for treatment of simulated, thermally oxidized radioactive and mixed wastes. Part 1: Design criteria and description of integrated waste treatment facility

    International Nuclear Information System (INIS)

    The US Bureau of Mines and the Department of Energy (DOE), through its contractor EG and G Idaho Inc., are collaborating on a multiyear research project to evaluate the applicability of three-phase, electric-arc furnace melting technology to vitrify materials simulating low-level radioactive and mixed wastes buried or stored at the Idaho National Engineering Laboratory and other DOE sites. The melter is sealed, 1-t (1.1-st), three-phase, 800-kV · A electric arc melting furnace with 10.2-cm- (4-in-) diameter graphite electrodes, water-cooled roof and sidewalls, and four water-cooled feed tubes. A water-cooled copper fixture provides for continuous tapping of slag. An instrumented air pollution control system (APCS) with access ports for analysis and a feeder based on screw conveyors and a bucket elevator are dedicated to the facility. Test data are provided by an arc furnace analyzer and by sensors indicating feed rate; slag temperature; and temperature, pressure, and velocity in the APCS. These data are received by a data logger, digitized, and transmitted to a personal computer for storage and display. This unique waste treatment facility is available for public and private use on a cost-sharing basis

  8. Order Reduction of the Radiative Heat Transfer Model for the Simulation of Plasma Arcs

    CERN Document Server

    Fagiano, Lorenzo

    2015-01-01

    An approach to derive low-complexity models describing thermal radiation for the sake of simulating the behavior of electric arcs in switchgear systems is presented. The idea is to approximate the (high dimensional) full-order equations, modeling the propagation of the radiated intensity in space, with a model of much lower dimension, whose parameters are identified by means of nonlinear system identification techniques. The low-order model preserves the main structural aspects of the full-order one, and its parameters can be straightforwardly used in arc simulation tools based on computational fluid dynamics. In particular, the model parameters can be used together with the common approaches to resolve radiation in magnetohydrodynamic simulations, including the discrete-ordinate method, the P-N methods and photohydrodynamics. The proposed order reduction approach is able to systematically compute the partitioning of the electromagnetic spectrum in frequency bands, and the related absorption coefficients, tha...

  9. Analysis of products of arc discharge plasma synthesis with a graphite cathode and a composite anode

    Science.gov (United States)

    Podgornyi, V. I.; Belashev, B. Z.; Kolodei, V. A.; Osaulenko, R. N.

    2015-01-01

    The composition, structure, and morphology of compounds formed in an argon arc discharge with a graphite cathode and a composite anode are studied by the methods of Raman scattering, X-ray diffraction analysis, X-ray microanalysis, and electron microscopy. Among the synthesis produces, graphite-like substances and metal carbides dominate; metal microcrystallites, fullerenes, and carbon nanotubes are present in some cases. It is found that carbides are not formed when anodes with a nickel admixture are used. The Raman spectra indicate the synthesis of single-wall carbon nanotubes in arcs with the C-Fe and C-Ni-V anodes. In the case of C-Ni and C-V anodes, electron microscopy data indicate the existence of micrometer-size carbon fiber structures in the synthesis products.

  10. Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

    Directory of Open Access Journals (Sweden)

    K. Kobylańska–Szkaradek

    2009-03-01

    Full Text Available Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying method on super-alloys which function as TBC (Thermal Barriers Coatings.Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings deposited by plasma spraying method should contribute to the improvement of their density and durability as thermal barriers. In order to prove the assumptions made in the paper, coatings featuring varied porosity and deposited upon the nickel base super-alloys surface with the initially sprayed NiCrAlY bond coat have been subjected to laser melting and then their structure, thermal conductivity and thermal life prediction in the conditions of cyclic temperature changes from 20 to 1200ºC have been examined.Findings: It has been revealed that the coatings featuring low porosity laser melted on part of their thickness and heated up to about 700ºC demonstrate the highest thermal life prediction under the conditions mentioned and at slightly lower thermal conductivity. Heating is intended to lower the structural stresses which are connected with the change of ceramic volume at crystallization as well as thermal stresses resulting from varied expansion of coating and metal substrate.Research limitations/implications: Low wettability of metal by ceramic which results from various surface tensions of these materials is the cause of their lower adhesion to the substrate during laser melting all through their thickness. It is so because delaminations occur between phases the boundary and cracks.Practical implications: The worked out conditions of laser melting might be used in the process of creation of ZrO2 - Y2O3 coats which feature high working durability upon super-alloy elements.Originality/value: It has been found that homogenization of chemical composition of coatings occurs during

  11. Mantle peridotite xenoliths in andesite lava at El Peñon, central Mexican Volcanic Belt: Isotopic and trace element evidence for melting and metasomatism in the mantle wedge beneath an active arc

    Science.gov (United States)

    Mukasa, Samuel B.; Blatter, Dawnika L.; Andronikov, Alexandre V.

    2007-08-01

    Peridotites in the mantle wedge and components added to them from the subducting slab are thought to be the source of most arc magmas. However, direct sampling of these materials, which provides a glimpse into the upper mantle beneath an active margin, is exceedingly rare. In the few arc localities where found, peridotite xenoliths are usually brought to the surface by basaltic magmas. Remarkably, the hornblende-bearing ultramafic xenoliths and clinopyroxene megaxenocrysts from El Peñon in the central Mexican Volcanic Belt were brought to the surface by a Quaternary high-Mg siliceous andesite, a rock type usually considered too evolved to be a direct product of mantle melting. The xenoliths and megaxenocrysts from El Peñon represent lithospheric mantle affected by significant subduction of oceanic lithosphere since as early as the Permian. Trace element and radiogenic isotope data we report here on these materials suggest a history of depletion by melt extraction, metasomatism involving a fluid phase, and finally, limited reaction between the ultramafic materials and the host andesite, probably during transport. They also show that high-Mg siliceous andesite can be a direct product of 1-5% melting of H 2O-bearing spinel lherzolite.

  12. Contribution to the 3D time-dependent modeling of the arc dynamic behavior in a DC plasma spray torch; Contribution a la modelisation instationnaire et tridimensionnelle du comportement dynamique de l'arc dans une torche de projection plasma

    Energy Technology Data Exchange (ETDEWEB)

    Baudry, C

    2003-11-15

    This work is devoted to the tri-dimensional time-dependent modeling of the arc behavior in a plasma spray torch. It has been carried out in the fame of a collaboration with the Thermal Spray Laboratory of CEA-DAM, Le Ripault and the laboratory of Fluid Mechanics and Heat Transfers of EDF. After a summary of the operation modes of a DC plasma torch and the effect of anode erosion on the torch working, the structure of an electric arc is depicted as well as the main models of non-transferred electric arcs proposed in the literature. This review allows the determination of the main assumption and boundary conditions for a 'realistic' model of the electric arc. Then, the equations, assumptions and boundary conditions of the model we have developed are presented and, the CFD code ESTET 3.4 used to solve the model equations. The model is based on a specific value of the local electric field to predict the breakdown of the arc while its re-striking is favored by a hot gas column at the spot where the highest value of the electric field is calculated. This model gives a realistic prediction of the time-dependent arc behavior according to the plasma-forming gas nature and of the temperature and velocity of the gas flow at the nozzle exit. However, it overestimates the torch voltage and dimensions of the anode arc root attachment spot. (author)

  13. Dynamics of macroparticles in a magnetic filter for a vacuum arc plasma sources

    International Nuclear Information System (INIS)

    The possibility of transportation of charged macroparticles (MPs) through a magnetic filter is studied. It is shown that when MPs moves through the curved magnetic filter its can be charged either positively or negatively. The trajectories of charged MPs are changed due to the negative space charge in the plasma duct. It is found that positively charged MPs may be retained in plasma duct, depending on the parameters of plasma and MPs. The conditions determining their transportation through the filter are obtained

  14. Investigation of supercapacitors with carbon electrodes obtained from argon-acetylene arc plasma

    OpenAIRE

    Kavaliauskas, Žydrūnas

    2010-01-01

    The dissertation examines topics related to the formation of supercapacitors using plasma technology and their analysis. Plasma spray technology was used to form supercapacitors electrodes. Carbon was deposited on stainless steel surface using the atmospheric pressure argon-acetylene plasma. The deposition of nickel oxide on the surface of carbon electrodes was made using magnetron sputtering method. The influence of acetylene amount to the supercapacitors electrodes and the electrical charac...

  15. Entrainment of Ambient air into H2O/Ar Arc Plasma Jet

    Czech Academy of Sciences Publication Activity Database

    Kavka, Tetyana; Hrabovský, Milan; Konrád, Miloš; Kopecký, Vladimír; Sember, Viktor; Chumak, Oleksiy

    Bari : Department of Chemistry, University of Bari, 2003 - (d'Agostino, R.; Favia, P.; Fracassi, F.; Palumbo, F.), s. - [International Symposium on Plasma Chemistry/16th./. Taormina (IT), 22.06.2003-27.06.2003] R&D Projects: GA ČR GA202/01/1563 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma jet, entrainment , enthalpy probe Subject RIV: BL - Plasma and Gas Discharge Physics

  16. Spectroscopic analysis of the plasma continuum radiation for on-line arc-welding defect detection

    International Nuclear Information System (INIS)

    When plasma optical spectroscopy is applied to on-line welding quality monitoring, the plasma electronic temperature is commonly selected as the spectroscopic parameter to determine. However, several processing stages have to be considered in this case, including plasma emission line identification, which is significantly costly in terms of computational performance. In this paper, the wavelength associated with the maximum intensity of the plasma background emission is proposed as the new monitoring signal, as it will be demonstrated that there is a clear correlation between this parameter and the welding quality. The resulting processing scheme is clearly simpler, and experimental and field tests will prove the feasibility of the proposed technique

  17. Emission Spectroscopy of OH Radical in Water-Argon Arc Plasma Jet

    OpenAIRE

    Alan Mašláni; Viktor Sember

    2014-01-01

    Emission spectra of OH radical are studied in the plasma jet generated by a plasma torch with hybrid water-argon stabilization. Plasma jet is located in a chamber with pressures 4 kPa and 10 kPa. In spite of high temperatures of produced plasma, OH spectra are observed in a large area of the jet. OH spectra are used to obtain rotational temperatures from the Boltzmann plots of resolved rotational lines. Due to line-of-sight integration of radiation, interpretation of the temperatures is not s...

  18. Tailoring nanomaterial products through electrode material and oxygen partial pressure in a mini-arc plasma reactor

    International Nuclear Information System (INIS)

    Nanomaterials with controllable morphology and composition are synthesized by a simple one-step vapor condensation process using a mini-arc plasma source. Through systematic investigation of mini-arc reactor parameters, the roles of carrier gas, electrode material, and precursor on producing diverse nanomaterial products are revealed. Desired nanomaterial products, including tungsten oxide nanoparticles (NPs), tungsten oxide nanorods (NRs), tungsten oxide and tin oxide NP mixtures and pure tin dioxide NPs can thus be obtained by tailoring reaction conditions. The amount of oxygen in the reactor is critical to determining the final nanomaterial product. Without any precursor material present, a lower level of oxygen in the reactor favors the production of W18O49 NRs with tungsten as cathode, while a high level of oxygen produces more round WO3 NPs. With the presence of a precursor material, amorphous particles are favored with a high ratio of argon:oxygen. Oxygen is also found to affect tin oxide crystallization from its amorphous phase in the thermal annealing. Results from this study can be used for guiding gas phase nanomaterial synthesis in the future.

  19. Surface modification of compressor steels using thermally assisted ionic diffusion in the titanium plasma of a vacuum arc discharge

    Science.gov (United States)

    Muboyadzhyan, S. A.; Azarovskii, E. N.

    2015-11-01

    The thermally stimulated ionic diffusion (ionic modification) of titanium ions at the surfaces of EP866 and EI961 compressor steels is considered in the plasma of the high-current vacuum-arc discharge (VAD) in an ion-plasma MAP-3 plant. The dependences of the sample temperature in the sputtering chamber of the ion-plasma MAP-3 plant and the rate of specific change of the sample mass on the bias voltage at a VAD current of 300 A are obtained. The elemental composition of the surface layers of the samples subjected to ion treatment is studied. It is shown that, at a VAD current of 300 A and a bias voltage up to 400 V, the compressor steel sample temperature does not exceed 440°C and the inversion voltage, which determines the transition from coating condensation to ion etching of a substrate, is ~360 V for EP866 steel and ~390 V for EI961 steel. The corrosion resistance of the compressor steels modified at a VAD current of 300 A is investigated.

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

    CERN Document Server

    Franz, Robert; Hawranek, Gerhard; Polcik, Peter

    2015-01-01

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