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Sample records for carbon plasma gun

  1. Carbon plasma gun

    International Nuclear Information System (INIS)

    Mendel, C.W. Jr.; Zagar, D.M.; Mills, G.S.; Humphries, S. Jr.; Goldstein, S.A.

    1980-01-01

    A family of plasma guns supplying highly ionized carbon plasma is described. The guns are simple and inexpensive to construct and are pulsed by small capacitor banks of a few hundred joules. The output consists of 10 17 --10 18 multiply ionized carbon ions traveling at about 10 7 cm/s. Neutral output is very low and arrives well after the ionized carbon. The guns and pulsers are very reliable

  2. A novel carbon gun for use with plasma opening switches

    International Nuclear Information System (INIS)

    Stevenson, P.; Gregory, K.; Cliffe, R.J.; Smith, I.R.

    2001-01-01

    The carbon gun is probably the most common plasma source used in plasma opening switches. Nevertheless, it either produces a contaminated plasma, as the flashover surface erodes, or requires regular treatment with graphite paint. The novel form of the plasma gun described in this paper overcomes the disadvantages of existing designs and produces a cleaner plasma. Experimental results illustrate the performance of a prototype system. (author)

  3. Coaxial carbon plasma gun deposition of amorphous carbon films

    Science.gov (United States)

    Sater, D. M.; Gulino, D. A.; Rutledge, S. K.

    1984-01-01

    A unique plasma gun employing coaxial carbon electrodes was used in an attempt to deposit thin films of amorphous diamond-like carbon. A number of different structural, compositional, and electrical characterization techniques were used to characterize these films. These included scanning electron microscopy, scanning transmission electron microscopy, X ray diffraction and absorption, spectrographic analysis, energy dispersive spectroscopy, and selected area electron diffraction. Optical absorption and electrical resistivity measurements were also performed. The films were determined to be primarily amorphous, with poor adhesion to fused silica substrates. Many inclusions of particulates were found to be present as well. Analysis of these particulates revealed the presence of trace impurities, such as Fe and Cu, which were also found in the graphite electrode material. The electrodes were the source of these impurities. No evidence of diamond-like crystallite structure was found in any of the film samples. Details of the apparatus, experimental procedure, and film characteristics are presented.

  4. Coaxial carbon plasma gun deposition of amorphous carbon films

    International Nuclear Information System (INIS)

    Sater, D.M.; Gulino, D.A.

    1984-03-01

    A unique plasma gun employing coaxial carbon electrodes was used in an attempt to deposit thin films of amorphous diamond-like carbon. A number of different structural, compositional, and electrical characterization techniques were used to characterize these films. These included scanning electron microscopy, scanning transmission electron microscopy, X ray diffraction and absorption, spectrographic analysis, energy dispersive spectroscopy, and selected area electron diffraction. Optical absorption and electrical resistivity measurements were also performed. The films were determined to be primarily amorphous, with poor adhesion to fused silica substrates. Many inclusions of particulates were found to be present as well. Analysis of these particulates revealed the presence of trace impurities, such as Fe and Cu, which were also found in the graphite electrode material. The electrodes were the source of these impurities. No evidence of diamond-like crystallite structure was found in any of the film samples. Details of the apparatus, experimental procedure, and film characteristics are presented

  5. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  6. Ion plasma electron gun

    International Nuclear Information System (INIS)

    Wakalopulos, G.

    1976-01-01

    In the disclosed electron gun positive ions generated by a hollow cathode plasma discharge in a first chamber are accelerated through control and shield grids into a second chamber containing a high voltage cold cathode. These positive ions bombard a surface of the cathode causing the cathode to emit secondary electrons which form an electron beam having a distribution adjacent to the cathode emissive surface substantially the same as the distribution of the ion beam impinging upon the cathode. After passing through the grids and the plasma discharge chamber, the electron beam exits from the electron gun via a foil window. Control of the generated electron beam is achieved by applying a relatively low control voltage between the control grid and the electron gun housing (which resides at ground potential) to control the density of the positive ions bombarding the cathode

  7. Fueling by coaxial plasma guns

    International Nuclear Information System (INIS)

    Marshall, J.

    1978-01-01

    The operating principles of pulsed coaxial guns are reviewed. Some problems involved with the injection of plasma beams from these guns into containment fields are described. The injection during reactor operating conditions is then discussed

  8. Gas injected washer plasma gun

    International Nuclear Information System (INIS)

    Jain, K.K.; John, P.I.; Punithavelu, A.M.; Rao, P.P.

    1980-01-01

    A plasma gun similar in geometry to the washer plasma gun has been operated with gas injected externally. hydrogen, nitrogen and argon plasmas have been ionised and accelerated to velocities of the order of 10 7 mm s -1 and densities 10 11 mm -3 . Higher parameter range is possible with higher electrical input power. (author)

  9. Fueling by coaxial plasma guns

    International Nuclear Information System (INIS)

    Marshall, J.

    1977-01-01

    A review of the operational characteristics of ''snowplow'' and ''deflagration'' coaxial plasma guns is given. The injection of these plasmas into containment fields is discussed. The effect of a background plasma on low-beta injection is mentioned. The use of high-beta injection for reactor plasmas is described

  10. Plasma focusing in coaxial gun

    International Nuclear Information System (INIS)

    Soliman, H.M.; Masoud, M.M.; El-Khalafawy, T.

    1986-01-01

    A capacitor bank has been discharged between two coaxial electrodes of 6.6 cm outer diameter, 3.2 cm inner diameter and length of 31.5 cm. filled with hydrogen gas at pressure of 310 μHg. Results show that, the axial and radial plasma current reach a maximum value at a position adjacent to the gun muzzle, at which the plasma focus occurs. The measurement of the electron temperature and density and azimuthal electric field along the axis of the expansion chamber, gives a maximum value at z∼18 cm from the gun muzzle, while the axial plasma current and velocity has a minimum value at that position. These results indicate that a second point of a plasma focus has been formed at z∼18 cm from the gun muzzle, along the axis of the expansion chamber

  11. Development of coaxial rotating-plasma gun

    International Nuclear Information System (INIS)

    Ikehata, Takashi; Tanabe, Toshio; Mase, Hiroshi

    1985-01-01

    A rotating-plasma gun has been devised to produce plasma streams with higher rotational velocities. The working mechanism of the gun and the results of a preliminary experiment have been described. (author)

  12. Heavy duty plasma spray gun

    International Nuclear Information System (INIS)

    Irons, G.C.; Klein, J.F.; Lander, R.D.; Thompson, H.C.; Trapani, R.D.

    1984-01-01

    A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the plasma gas is introduced into the gun arc in a manner only defined by the gas distribution member. The gun has liquid cooling for the nozzle (anode) and the cathode. Double seals are provided between the coolant and the arc region and a vent is provided between the seals which provides an indication when a seal has failed. Some parts of the gun are electrically isolated from others by an intermediate member which is formed as a sandwich of two rigid metal face pieces and an insulator disposed between them. The metal face pieces provide a rigid body to attach the remaining parts in proper alignment therewith

  13. 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.

  14. Automatic targeting of plasma spray gun

    International Nuclear Information System (INIS)

    Abbatiello, L.A.; Neal, R.E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is described. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun

  15. Automatic targeting of plasma spray gun

    Science.gov (United States)

    Abbatiello, Leonard A.; Neal, Richard E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is provided. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun.

  16. Experimental studies of coaxial plasma gun current

    International Nuclear Information System (INIS)

    Price, D.W.

    1988-01-01

    In this investigation of a coaxial plasma gun, plasma sheath currents and related behavior are examined. Plasma behavior in the gun affects gun characteristics. Plasma gun applications are determined by the plasma behavior. The AFWL PUFF capacitor bank (72 μF, 29 nH, 120 kV) drives the plasma gun using a deuterium fill gas. The gas breakdown site is isolated from the dielectric/vacuum interface in the AFWL system. Two gas values deliver gas in the system. The first delivers gas from the gun breech and the second optional valve delivers gas to the gun muzzle. Currents and voltages are measured by Rogowski coils, B probes and capacitive voltage probes. A O-D slug model is used to predict the current, inductance, gun voltage and plasma sheath velocity. The slug model assumes the sheath transits the gun with all mass in the sheath. In the snowplow mode, the plasma sheath is thin with a sharp current rise and drop. Our system operated in a transition mode between the snowplow and deflagration modes with early snowplow behavior and late deflagration behavior. Neutrons are produced in a plasma pinch at the gun muzzle, indicating snowplow behavior. The slug theory models overall gun behavior to experimental accuracy. Experimental results are compared to four theories for plasma sheath velocities: the Alfven collisionally limited model, the Rosenbluth model, the Fishbine saturated model and a single particle drift model. Experimental velocities vary from 10 5 to 10 6 m/s. Only the single particle drift and the slug model calculations are of the right magnitude (8 x 10 5 m/s). The Fishbine and the Rosenbluth models predict slower velocities (2 x 10 5 m/s). The Alfven model is not applicable to this system

  17. Plasma-gun fueling for tokamak reactors

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1980-11-01

    In light of the uncertain extrapolation of gas puffing for reactor fueling and certain limitations to pellet injection, the snowplow plasma gun has been studied as a fueling device. Based on current understanding of gun and plasma behavior a design is proposed, and its performance is predicted in a tokamak reactor environment

  18. Field reversal produced by a plasma gun

    International Nuclear Information System (INIS)

    Hartman, C.W.; Condit, W.; Granneman, E.H.A.; Prono, D.; Smith, A.C. Jr.; Taska, J.; Turner, W.C.

    1980-01-01

    Experimental results are presented of the production of Field-Reversed Plasma with a high energy coaxial plasma gun. The gun is magnetized with solenoids inside the center electrode and outside the outer electrode so that plasma emerging from the gun entrains the radial fringer field at the muzzle. The plasma flow extends field lines propagating a high electrical conductivity, the flux inside the center electrode should be preserved. However, for low flux, the trapped flux exceeds by 2 or more the initial flux, possibly because of helical deformation of the current channel extending from the center electrode

  19. RF Electron Gun with Driven Plasma Cathode

    CERN Document Server

    Khodak, Igor

    2005-01-01

    It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

  20. Development of plasma cathode electron guns

    Science.gov (United States)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  1. Reconnection conditions for a coaxial plasma gun

    International Nuclear Information System (INIS)

    Berk, H.L.; Hammer, J.H.; Shearer, J.W.

    1982-01-01

    A fluid model for the flow conditions necessary to form a compact torus from the plasma ejected by a coaxial plasma gun is developed. This is done by finding the conditions for which the steady-flow equations break down. Results are found for two cases; variable external flux and variable outer-wall radius

  2. Modification of anisotropic plasma diffusion via auxiliary electrons emitted by a carbon nanotubes-based electron gun in an electron cyclotron resonance ion source.

    Science.gov (United States)

    Malferrari, L; Odorici, F; Veronese, G P; Rizzoli, R; Mascali, D; Celona, L; Gammino, S; Castro, G; Miracoli, R; Serafino, T

    2012-02-01

    The diffusion mechanism in magnetized plasmas is a largely debated issue. A short circuit model was proposed by Simon, assuming fluxes of lost particles along the axial (electrons) and radial (ions) directions which can be compensated, to preserve the quasi-neutrality, by currents flowing throughout the conducting plasma chamber walls. We hereby propose a new method to modify Simon's currents via electrons injected by a carbon nanotubes-based electron gun. We found this improves the source performances, increasing the output current for several charge states. The method is especially sensitive to the pumping frequency. Output currents for given charge states, at different auxiliary electron currents, will be reported in the paper and the influence of the frequency tuning on the compensation mechanism will be discussed.

  3. Characterisation of plasma in a rail gun

    Science.gov (United States)

    Ray, P. K.

    1986-01-01

    The mechanism of plasma and projectile acceleration in a DC rail gun is described from a microscopic point of view through the establishment of the Hall field. The plasma conductivity is shown to be a tensor, indicating that there is a small component of current parallel to the direction of acceleration. The plasma characteristics are evaluated in the experiment of Bauer et. al., as a function of plasma mass through a simple fluid mechanical analysis of the plasma. By equating the energy dissipatated in the plasma with the radiation heat loss, the properties of the plasma are determined.

  4. Trapping of gun-injected plasma by a tokamak

    International Nuclear Information System (INIS)

    Leonard, A.W.; Dexter, R.N.; Sprott, J.C.

    1986-01-01

    It is shown that a plasma produced by a Marshall gun can be injected into and trapped by a tokamak plasma. Gun injection raises the line-averaged density and peaks the density profile. Trapping of the gun-injected plasma is explainable in terms of a depolarization current mechanism

  5. Electrothermal plasma gun as a pellet injector

    International Nuclear Information System (INIS)

    Kincaid, R.W.; Bourham, M.A.

    1994-01-01

    The NCSU electrothermal plasma gun SIRENS has been used to accelerate plastic (Lexan polycarbonate) pellets, to determine the feasibility of the use of electrothermal guns as pellet injectors. The use of an electrothermal gun to inject frozen hydrogenic pellets requires a mechanism to provide protective shells (sabots) for shielding the pellet from ablation during acceleration into and through the barrel of the gun. The gun has been modified to accommodate acceleration of the plastic pellets using special acceleration barrels equipped with diagnostics for velocity and position of the pellet, and targets to absorb the pellet's energy on impact. The length of the acceleration path could be varied between 15 and 45 cm. The discharge energy of the electrothermal gun ranged from 2 to 6 kJ. The pellet velocities have been measured via a set of break wires. Pellet masses were varied between 0.5 and 1.0 grams. Preliminary results on 0.5 and 1.0 g pellets show that the exit velocity reaches 0.9 km/s at 6 kJ input energy to the source. Higher velocities of 1.5 and 2.7 km/s have been achieved using 0.5 and 1.0 gm pellets in 30 cm long barrel, without cleaning the barrel between the shots

  6. Long pulse, plasma cathode E-gun

    International Nuclear Information System (INIS)

    Goebel, D.M.; Schumacher, R.W.; Watkins, R.M.

    1993-01-01

    A unique, long-pulse E-gun has been developed for high-power tube applications. The Hollow-Cathode-Plasma (HCP) E-gun overcomes the limitations of conventional thermionic-cathode guns that have limited current density (typically ≤ 10 A/cm 2 ) or field-emission guns that offer high current density but suffer from short pulsewidth capability (typically 50 A/cm 2 ), long-pulse operation without gap closure, and also requires no cathode-heater power. The gun employs a low-pressure glow discharge inside a hollow cathode (HC) structure to provide a stable, uniform plasma surface from which a high current-density electron beam can be extracted. The plasma density is controlled by a low-voltage HC discharge pulser to produce the desired electron current density at the first grid of a multi-grid accelerator system. A dc high-voltage electron-beam supply accelerates the electrons across the gap, while the HC pulser modulates the beam current to generate arbitrary pulse waveforms. The electron accelerator utilizes a multi-aperture array that produces a large area, high perveance (>35 μpervs) beam consisting initially of many individual beamlets. The E-beam is normally operated without an applied magnetic field in the ion-focused regime, where the plasma produced by beam ionization of a background gas space-charge neutralizes the beam, and the Bennett self-pinch compresses the beamlets and increases the current density. The self-pinched beam has been observed to propagate over a meter without beam breakup or instabilities. The HCP E-gun has been operated at voltages up to 150 kV, currents up to 750 A, and pulse lengths of up to 120 μsec

  7. Alignment Fixtures For Vacuum-Plasma-Spray Gun

    Science.gov (United States)

    Woodford, William H.; Mckechnie, Timothy N.; Power, Christopher A.; Daniel, Ronald L., Jr.

    1993-01-01

    Fixtures for alignment of vacuum-plasma-spray guns built. Each fixture designed to fit specific gun and holds small, battery-powered laser on centerline of gun. Laser beam projects small red dot where centerline intersects surface of workpiece to be sprayed. After laser beam positioned on surface of workpiece, fixture removed from gun and spraying proceeds.

  8. Streaming metal plasma generation by vacuum arc plasma guns

    International Nuclear Information System (INIS)

    MacGill, R.A.; Dickinson, M.R.; Anders, A.; Monteiro, O.R.; Brown, I.G.

    1998-01-01

    We have developed several different embodiments of repetitively pulsed vacuum arc metal plasma gun, including miniature versions, multicathode versions that can produce up to 18 different metal plasma species between which one can switch, and a compact high-duty cycle well-cooled version, as well as a larger dc gun. Plasma guns of this kind can be incorporated into a vacuum arc ion source for the production of high-energy metal ion beams, or used as a plasma source for thin film formation and for metal plasma immersion ion implantation and deposition. The source can also be viewed as a low-energy metal ion source with ion drift velocity in the range 20 - 200 eV depending on the metal species used. Here we describe the plasma sources that we have developed, the properties of the plasma generated, and summarize their performance and limitations. copyright 1998 American Institute of Physics

  9. Experimental Studies of Electrothermal Plasma Gun

    International Nuclear Information System (INIS)

    Diab, F.B.A.

    2013-01-01

    The aim of the present work is to study the capillary plasma discharge dynamics and characteristics. The capillary plasma device is a new technology for producing high density plasma after ablating the capillary wall using a pulsed electric power. An Electrothermal Plasma Gun (ETG) is composed of a capillary discharge tube made of Teflon operated with simple RLC circuit. The device called Electrothermal Gun (ETG) which is composed of 4 capacitors (70 μF, 10 kV, 1.28 μH) connected in parallel to a plasma source by means of one high power supply. The gun was operated in open air at discharge energies between 35 J - 3.5 kJ according to charging voltage. The work presented in this thesis covers the following items, 1- Measurements of the basic parameters and characterizations of the pretest results of the electrical circuits and capillary plasma discharge using Rogowski coil, voltage probe and Photomultiplier. 2- Material processing including (physics of the surface modifications, the morphology of the surface by using Scanning Electron Microscope (SEM) at different conditions, compositions of the materials by using X-ray Fluorescence (XRF), Micro hardness test and material particle deposition.

  10. Electrical model of cold atmospheric plasma gun

    Science.gov (United States)

    Slutsker, Ya. Z.; Semenov, V. E.; Krasik, Ya. E.; Ryzhkov, M. A.; Felsteiner, J.; Binenbaum, Y.; Gil, Z.; Shtrichman, R.; Cohen, J. T.

    2017-10-01

    We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.

  11. Acceleration of solid pellets using a plasma gun

    International Nuclear Information System (INIS)

    Buller, T.L.; Turnbull, R.J.; Kim, K.

    1979-01-01

    The use of solid pellets of hydrogen isotopes to refuel thermonuclear fusion reactors based on the tokamak configuration will require that the pellets be accelerated to high velocities. One possible method of acceleration is to interact a fast plasma from a plasma gun with the pellets. In this paper preliminary results are given on the acceleration of solid pellets with a plasma gun. The plasma-gun requirements for successful acceleration to high velocities are discussed

  12. Momentum transfer to rotating magnetized plasma from gun plasma injection

    International Nuclear Information System (INIS)

    Shamim, Imran; Hassam, A. B.; Ellis, R. F.; Witherspoon, F. D.; Phillips, M. W.

    2006-01-01

    Numerical simulations are carried out to investigate the penetration and momentum coupling of a gun-injected plasma slug into a rotating magnetized plasma. An experiment along these lines is envisioned for the Maryland Centrifugal Experiment (MCX) [R. F. Ellis et al., Phys. Plasmas 8, 2057 (2001)] using a coaxial plasma accelerator gun developed by HyperV Technologies Corp. [F. D. Witherspoon et al., Bull. Am. Phys. Soc. 50, LP1 87 (2005)]. The plasma gun would be located in the axial midplane and fired off-axis into the rotating MCX plasma annulus. The numerical simulation is set up so that the initial momentum in the injected plasma slug is of the order of the initial momentum of the target plasma. Several numerical firings are done into the cylindrical rotating plasma. Axial symmetry is assumed. The slug is seen to penetrate readily and deform into a mushroom, characteristic of interchange deformations. It is found that up to 25% of the momentum in the slug can be transferred to the background plasma in one pass across a cylindrical chord. For the same initial momentum, a high-speed low density slug gives more momentum transfer than a low-speed high density slug. Details of the numerical simulations and a scaling study are presented

  13. Dynamics of a coaxial plasma gun

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1977-01-01

    The dynamics of an ionizing wave in a coaxial plasma gun with an azimuthal bias magnetic field is analysed in a theoretical model. Only the radial dependence is treated and instead of including a treatment of the energy balance two separate physical assumptions are made. In the first case it is assumed that the total internal electric field is given by the critical ionization velocity condition and in the second that the ionization rate is constant. For consistency wall sheaths are assumed to match the internal plasma potential to that of the walls. On the basis of momentum and particle balance the radial dependence of the electron density, current density, electric field and drift velocity are found. An electron source is required at the cathode and the relative contribution from ionization within the plasma is deduced. The assumption that there are no ion sources at the electrodes leads to a restriction on the possible values of the axial electric field. (Auth.)

  14. New approach to controlling impurity contamination of a plasma-gun-produced compact torus

    International Nuclear Information System (INIS)

    Post, R.F.; Turner, W.C.

    1982-01-01

    The presence of impurity ions, notably carbon and oxygen, has been determined to be a major factor limiting the lifetime of field-reversed plasma entities produced by coaxial plasma guns such as the Beta II gun at LLNL. Similar problems are encountered in other toroidal plasmas, e.g. those in tokamaks. However, the solution employed there, discharge cleaning, followed by initiation of the plasma at low density (where impurity radiation losses are exceeded by ohmic heating rates) is not applicable here. This note discusses a proposed means for drastically reducing the level of impurities. (These are believed to be evolved from the gun electrode surfaces as a result of thermal shock associated with UV emission from the gun plasma). The idea: take advantage of the UV pulse preferentially to release hydrogen from the electrode surfaces. These surfaces are to be coated with a few-micron-thick layer of titanium, outgassed by preheating and subsequently loaded with hydrogen

  15. A contoured gap coaxial plasma gun with injected plasma armature

    Energy Technology Data Exchange (ETDEWEB)

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard II; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond [HyperV Technologies Corp., Chantilly, Virginia 20151 (United States)

    2009-08-15

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 {mu}g of plasma with density above 10{sup 17} cm{sup -3} to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 {mu}g has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  16. A contoured gap coaxial plasma gun with injected plasma armature.

    Science.gov (United States)

    Witherspoon, F Douglas; Case, Andrew; Messer, Sarah J; Bomgardner, Richard; Phillips, Michael W; Brockington, Samuel; Elton, Raymond

    2009-08-01

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 microg of plasma with density above 10(17) cm(-3) to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 microg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  17. A contoured gap coaxial plasma gun with injected plasma armature

    International Nuclear Information System (INIS)

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard II; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond

    2009-01-01

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 μg of plasma with density above 10 17 cm -3 to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 μg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  18. The breakdown phase in a coaxial plasma gun

    International Nuclear Information System (INIS)

    Donges, A.; Herziger, G.; Krompholz, H.; Ruehl, F.; Schoenbach, K.

    1980-01-01

    The electrical breakdown in a coaxial plasma gun was investigated by means of optical and electrical measurements. The optimum start and operation conditions of the gun turned out to be strongly dependent on material and length of the cylindrical insulator. (orig.)

  19. Preventing Clogging In A Vacuum Plasma Spray Gun

    Science.gov (United States)

    Krotz, Phillip D.; Daniel, Ronald L., Jr.; Davis, William M.

    1994-01-01

    Modification of powder-injection ports enables lengthy, high-temperature deposition operations. Graphite inserts prevent clogging of ports through which copper powder injected into vacuum plasma spray (VPS) gun. Graphite liners eliminate need to spend production time refurbishing VPS gun, reducing cost of production and increasing productivity. Concept also applied to other material systems used for net-shape fabrication via VPS.

  20. Contoured-gap coaxial guns for imploding plasma liner experiments

    Science.gov (United States)

    Witherspoon, F. D.; Case, A.; Brockington, S.; Cassibry, J. T.; Hsu, S. C.

    2014-10-01

    Arrays of supersonic, high momentum flux plasma jets can be used as standoff compression drivers for generating spherically imploding plasma liners for driving magneto-inertial fusion, hence the name plasma-jet-driven MIF (PJMIF). HyperV developed linear plasma jets for the Plasma Liner Experiment (PLX) at LANL where two guns were successfully tested. Further development at HyperV resulted in achieving the PLX goal of 8000 μg at 50 km/s. Prior work on contoured-gap coaxial guns demonstrated an approach to control the blowby instability and achieved substantial performance improvements. For future plasma liner experiments we propose to use contoured-gap coaxial guns with small Minirailgun injectors. We will describe such a gun for a 60-gun plasma liner experiment. Discussion topics will include impurity control, plasma jet symmetry and topology (esp. related to uniformity and compactness), velocity capability, and techniques planned for achieving gun efficiency of >50% using tailored impedance matched pulse forming networks. Mach2 and UAH SPH code simulations will be included. Work supported by US DOE DE-FG02-05ER54810.

  1. Performance of a carbon nanotube field emission electron gun

    Science.gov (United States)

    Getty, Stephanie A.; King, Todd T.; Bis, Rachael A.; Jones, Hollis H.; Herrero, Federico; Lynch, Bernard A.; Roman, Patrick; Mahaffy, Paul

    2007-04-01

    A cold cathode field emission electron gun (e-gun) based on a patterned carbon nanotube (CNT) film has been fabricated for use in a miniaturized reflectron time-of-flight mass spectrometer (RTOF MS), with future applications in other charged particle spectrometers, and performance of the CNT e-gun has been evaluated. A thermionic electron gun has also been fabricated and evaluated in parallel and its performance is used as a benchmark in the evaluation of our CNT e-gun. Implications for future improvements and integration into the RTOF MS are discussed.

  2. Characterization of the C-2W Plasma Guns

    Science.gov (United States)

    Dubois, Ami; Sokolov, Vladimir; Korepanov, Sergey; Osin, Dima; Player, Gabriel; TAE Team

    2017-10-01

    Previous use of coaxial arc discharge plasma guns on the C-2U device exhibited great success in plasma stabilization and improved confinement. On the C-2W experiment, arc discharge plasma guns will again be used to facilitate the electrical connection between the plasma core and the divertor electrodes in order to maintain the electrode edge biasing and induce E x B shear to control plasma rotation. Each plasma gun contains an internal solenoid used to shape the plasma stream. Characterization of electron density (ne) , electron temperature (Te) , floating potential (Vf) , and total plasma flux in an arc discharge lasting 6 ms without the internal solenoid are presented. A Langmuir probe located 27 cm axially outside of the plasma gun anode measures a bell-like radial ne profile with peak ne 1018 m-3 and Te 2 - 10 eV. Observed spectral lines of impurity ions provide an estimate of Te, and Balmer series line ratios of the main ion component are used to evaluate ne at both the probe location and near the plasma gun anode. A calorimeter measures the plasma flux to be constant and equivalent to 1 kA.

  3. Plasma gun with coaxial powder feed and adjustable cathode

    Science.gov (United States)

    Zaplatynsky, Isidor (Inventor)

    1991-01-01

    An improved plasma gun coaxially injects particles of ceramic materials having high melting temperatures into the central portion of a plasma jet. This results in a more uniform and higher temperature and velocity distribution of the sprayed particles. The position of the cathode is adjustable to facilitate optimization of the performance of the gun wherein grains of the ceramic material are melted at lower power input levels.

  4. The PLX- α Plasma Guns: Progress and Plans

    Science.gov (United States)

    Witherspoon, F. D.; Brockington, S.; Case, A.; Cruz, E.; Luna, M.; Thio, Y. C. Francis; LANL PLX-α Team

    2017-10-01

    The ALPHA coaxial plasma guns are being developed to support a 60-gun scaling study of spherically imploding plasma liners as a standoff driver for plasma-jet-driven magneto-inertial fusion (PJMIF). Seven complete guns have been delivered to LANL with 6 guns currently undergoing simultaneous test firings on PLX. The guns are designed to operate over a range of parameters: 0.5-5.0 mg of Ar, Ne, N2, Kr, and Xe; 20-60 km/s; 2 × 1016 cm-3 muzzle density; and up to 7.5 kJ stored energy per gun. Each coaxial gun incorporates a fast dense gas injection and triggering system, a compact low-weight pfn with integral sparkgap switching, and a contoured coaxial gap to suppress the blow-by instability. Optimizing parameter scans performed at HyperV have achieved : 4 mg at >50 km/s and length of 10 cm. Peak axial density 30 cm from the muzzle is 2 ×1016 cm-3. We will provide an overview of the experimental results, along with plans for further improvements in reliability, maintainability, fabricability, and plasma jet performance, with the latter focused on further improvements in the fast gas valve and the ignitors. This work supported by the ARPA-E ALPHA Program under contract DE-AR0000566 and Strong Atomics, LLC.

  5. Coaxial plasma guns as injectors of high beta linear theta pinches

    International Nuclear Information System (INIS)

    Marshall, J.

    1975-01-01

    A brief review of research on coaxial plasma guns and their use is given. Some problems and possibilities of using this gun for beam injection experiments are pointed out. Some scaling laws for gun energy are described

  6. O2 Plasma Etching and Antistatic Gun Surface Modifications for CNT Yarn Microelectrode Improve Sensitivity and Antifouling Properties.

    Science.gov (United States)

    Yang, Cheng; Wang, Ying; Jacobs, Christopher B; Ivanov, Ilia N; Venton, B Jill

    2017-05-16

    Carbon nanotube (CNT) based microelectrodes exhibit rapid and selective detection of neurotransmitters. While different fabrication strategies and geometries of CNT microelectrodes have been characterized, relatively little research has investigated ways to selectively enhance their electrochemical properties. In this work, we introduce two simple, reproducible, low-cost, and efficient surface modification methods for carbon nanotube yarn microelectrodes (CNTYMEs): O 2 plasma etching and antistatic gun treatment. O 2 plasma etching was performed by a microwave plasma system with oxygen gas flow and the optimized time for treatment was 1 min. The antistatic gun treatment flows ions by the electrode surface; two triggers of the antistatic gun was the optimized number on the CNTYME surface. Current for dopamine at CNTYMEs increased 3-fold after O 2 plasma etching and 4-fold after antistatic gun treatment. When the two treatments were combined, the current increased 12-fold, showing the two effects are due to independent mechanisms that tune the surface properties. O 2 plasma etching increased the sensitivity due to increased surface oxygen content but did not affect surface roughness while the antistatic gun treatment increased surface roughness but not oxygen content. The effect of tissue fouling on CNT yarns was studied for the first time, and the relatively hydrophilic surface after O 2 plasma etching provided better resistance to fouling than unmodified or antistatic gun treated CNTYMEs. Overall, O 2 plasma etching and antistatic gun treatment improve the sensitivity of CNTYMEs by different mechanisms, providing the possibility to tune the CNTYME surface and enhance sensitivity.

  7. Trapping of gun-injected plasma by a tokamak

    International Nuclear Information System (INIS)

    Leonard, A.W.; Dexter, R.N.; Sprott, J.C.

    1986-10-01

    It is shown that a plasma produced by a Marshall gun can be injected into and trapped by a tokamak plasma. Gun injection raises the line-averaged density and peaks the density profile. Trapping of the gun-injected plasma is explainable in terms of a depolarization current mechanism. A model is developed which describes the slowing of a plasma beam crossing into the magnetic field of a tokamak. The slowing down time is shown to go as tau/sub s/ ∞ n -1 /sub b/T 3 /sub e/(α 0 /L) 2 , where n/sub b/ and T/sub e/ are the density and temperature of the plasma beam and α 0 /L is the pitch of the field lines per unit length in the direction in which the beam is traveling. Experimental tests of this model are consistent with the scaling predictions

  8. Study of the hollow cathode plasma electron-gun

    International Nuclear Information System (INIS)

    Zhang Yonghui; Jiang Jinsheng; Chang Anbi

    2003-01-01

    For developing a novel high-current, long pulse width electron source, the theoretics and mechanism of the hollow cathode plasma electron-gun are analyzed in detail in this paper, the structure and the physical process of hollow cathode plasma electron-gun are also studied. This gun overcomes the limitations of most high-power microwave tubes, which employ either thermionic cathodes that produce low current-density beams because of the limitation of the space charge, or field-emission cathodes that offer high current density but provide only short pulse width because of plasma closure of the accelerating gap. In the theories studying on hollow cathode plasma electron-gun, the characteristic of the hollow-cathode discharge is introduced, the action during the forming of plasma of the stimulating electrode and the modulating anode are discussed, the movement of electrons and ions and the primary parameters are analyzed, and the formulas of the electric field, beam current density and the stabilization conditions of the beam current are also presented in this paper. The numerical simulation is carried out based on Poisson's equation, and the equations of current continuity and movement. And the optimized result is reported. On this basis, we have designed a hollow-cathode-plasma electron-gun, whose output pulse current is 2 kA, and pulse width is 1 microsecond

  9. Analytical solution for a coaxial plasma gun: Weak coupling limit

    International Nuclear Information System (INIS)

    Dietz, D.

    1987-01-01

    The analytical solution of the system of coupled ODE's which describes the time evolution of an ideal (i.e., zero resistance) coaxial plasma gun operating in the snowplow mode is obtained in the weak coupling limit, i.e, when the gun is fully influenced by the driving (RLC) circuit in which it resides but the circuit is negligibly influenced by the gun. Criteria for the validity of this limit are derived and numerical examples are presented. Although others have obtained approximate, asymptotic and numerical solutions of the equations, the present analytical results seem not to have appeared previously in the literature

  10. Characterization of cable gun plasma with a charge collector array

    International Nuclear Information System (INIS)

    Chen Yulan; Zeng Zhengzhong; Sun Fengju; Kuai Bin; Qiu Aici; Yin Jiahui; Cong Peitian; Liang Tianxue

    2003-01-01

    The density, drift velocity and reproducibility of the plasma produced by a cable plasma gun array have been measured with a charge collector array. The plasma is used to prefill a coaxial plasma-opening switch with a conducting time approaching 0.4 μs. The reproducibility of the plasma source in subsequent shots is better than 5%. Near the gun nozzle and the opposite electrode, the plasma density amounts to 10 15 cm -3 , which is 2 times to 3 times that in the gap between the two coaxial electrodes. A plasma drift velocity of about 2.4 cm/μs is observed from the time of flight of the charged particles. Both plasma density and drift velocity increase almost linearly with the rise in charge voltage

  11. Formation of a compact torus using a toroidal plasma gun

    International Nuclear Information System (INIS)

    Levine, M.A.; Pincosy, P.A.

    1981-01-01

    Myers, Levine and Pincosy earlier reported results using a toroidal plasma gun. The device differs from the usual coaxial plasma gun in the use of a strong toroidal bias current for enhanced efficiency, a pair of disk-like accelerating electrodes for reduced viscosity and a fast pulsed toroidal gas valve for more effective use of the injected gas sample. In addition, a technique is used for generating a toroidal current in the plasma ring. The combination offers an opportunity to deliver a plasma with a large amount of energy and to vary the density and relative toroidal and poloidal magnetic field intensities over a range of values. It is the purpose of this paper to report further experimental results, to project the gun's applications to the formation of a compact torus, and to propose a simple modification of the present apparatus as a test

  12. Plasma-filled diode based on the coaxial gun

    Science.gov (United States)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

    2012-10-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  13. Plasma-filled diode based on the coaxial gun.

    Science.gov (United States)

    Zherlitsyn, A A; Kovalchuk, B M; Pedin, N N

    2012-10-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  14. Plasma-filled diode based on the coaxial gun

    Energy Technology Data Exchange (ETDEWEB)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N. [Institute of High Current Electronics, 2/3 Academichesky Avenue, 634055 Tomsk (Russian Federation)

    2012-10-15

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of {>=}1 MeV at the current of Almost-Equal-To 100 kA was obtained in the experiments with a plasma-filled diode. The energy of Almost-Equal-To 5 kJ with the peak power of {>=}100 GW dissipated in the diode.

  15. Plasma wave observations during electron and ion gun experiments

    International Nuclear Information System (INIS)

    Olsen, R.C.; Lowery, D.R.; Weddle, L.E.

    1988-01-01

    Plasma wave instruments with high temporal and frequency resolution in the 0-6 kHz frequency range have been used to monitor electron gun-employing charge control experiments with the USAF/NASA p78-2 satellite, in order to determine whether plasma wave signatures consistent with the previous inference of electron heating were present. Strong plasma waves were noted near the electron gyrofrequency; these waves can heat ambient low energy electrons, as previously inferred. Attention is given to the two distinct classes of behavior revealed by the ion gun experiments. 16 references

  16. Plasma-filled diode based on the coaxial gun

    International Nuclear Information System (INIS)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

    2012-01-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  17. Beta II plasma-gun mechanical design and construction

    International Nuclear Information System (INIS)

    Pedrotti, L.; Deis, G.; Wong, R.; Calderon, M.; Chargin, A.; Garner, D.

    1979-01-01

    The magnetized coaxial plasma gun (located on the east end of the Beta II facility at the Lawrence Livermore Laboratory) will be used to test a new method of initiating a field reversed mirror plasma. The field-reversed mirror is expected to improve the mirror-fusion reactor by enhancing the ratio of fusion power to injected power. This paper concentrates on the mechanical design and construction of the magnetized coaxial plasma gun and also discusses the diagnostic devices necessary to demonstrate the formation of field-reversed rings

  18. Quasi-steady carbon plasma source for neutral beam injector

    International Nuclear Information System (INIS)

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

    2014-01-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration

  19. Quasi-steady carbon plasma source for neutral beam injector.

    Science.gov (United States)

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

    2014-02-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  20. Magnetized Target Fusion Propulsion: Plasma Injectors for MTF Guns

    Science.gov (United States)

    Griffin, Steven T.

    2003-01-01

    To achieve increased payload size and decreased trip time for interplanetary travel, a low mass, high specific impulse, high thrust propulsion system is required. This suggests the need for research into fusion as a source of power and high temperature plasma. The plasma would be deflected by magnetic fields to provide thrust. Magnetized Target Fusion (MTF) research consists of several related investigations into these topics. These include the orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the gun as it relates to plasma initiation and repeatability are under investigation. One of the items under development is the plasma injector. This is a surface breakdown driven plasma generator designed to function at very low pressures. The performance, operating conditions and limitations of these injectors need to be determined.

  1. Trapping of gun-injected plasma by a tokamak

    International Nuclear Information System (INIS)

    Leonard, A.W.; Dexter, R.N.; Sprott, J.C.

    1987-01-01

    It has been seen that a plasma produced by a Marshall gun can be injected into and trapped by a tokamak plasma. This trapping of a gun-injected plasma is explained in terms of a depolarization current mechanism. A model is developed that describes the slowing of a plasma beam crossing into the magnetic field of a tokamak. The slowing down time is shown to go as tau/sub s/proportionalT/sup 3/2//sub e/L 2 /n/sub b/α 2 0 , where n/sub b/ and T/sub e/ are the density and temperature of the plasma beam and α 0 /L is the pitch of the field lines per unit length in the direction in which the beam is traveling. Experimental tests of this model are consistent with the scaling predictions

  2. Prestressed Carbon Fiber Composite Overwrapped Gun Tube

    National Research Council Canada - National Science Library

    Littlefield, Andrew; Hyland, Edward

    2006-01-01

    .... Using composite materials not only directly removes weight from the gun tube but, by better balancing the tube, allows the use of smaller drive systems, thus further enhancing the system weight loss...

  3. Electrical properties of a co-axial plasma gun

    International Nuclear Information System (INIS)

    Allam, T.M.Y.

    1997-01-01

    The main interest of this work is to study the power discharge of capacitor bank through a coaxial electrodes system. Such arrangement is called the coaxial gun or coaxial accelerator. It is used in jet propulsion and in triggering of discharge in turbo engines or in plasma combustion arrangement. The main goal is to find out the efficiency of the system in both cases. coaxial plasma gun system has been constructed for this course of study. The plasma gun system consists of the plasma gun tube and the discharge chamber, the capacitor bank, the triggering system the vacuum system, the power supply, and safety and dumping system. Simple and efficient diagnostic techniques were used to measure the different parameters concerning the coaxial discharge system such as the Rogowski loop, the voltage divider, the magnetic probes, the double electric probe. Results were obtained using argon gas with an operating pressure ranging from 0.1 torr to 1 torr. The peak discharge current in the first half cycle was 44 K A with rise time of 6.25 μs for a bank charging voltage of 10 kv and gas pressure of 0.9 torr. 4-26 figs., 4-8 tabs., 33 refs

  4. Decay of plasma cluster accelerated by coaxial gun

    International Nuclear Information System (INIS)

    Kubes, P.; Hruska, J.; Bacilek, J.

    1978-01-01

    The decay of an air cluster accelerated in a vacuum tube is studied. The time dependence of electron density and electron temperature is introduced and the effect of different recombination processes is discussed. The observed plasma decay shows an exponential law, is independent of the gun regime and may be explained by ambipolar diffusion to the tube walls. (author)

  5. Macroparticle acceleration from a modified mather-type plasma gun

    International Nuclear Information System (INIS)

    Hou, W.S.; Yeh, T.R.; Wen, M.; Yeh, C.K.; Shang, D.J.

    1987-01-01

    The use of electromagnetic force to accelerate projectiles of a few grams in a plasma-driven railgun device was described recently. Since then, subsequent research along this development has been exploited at many laboratories. As part of the plasma focus research project, an effort of modified Mather-type plasma gun has also been constructed at the Institute of Nuclear Energy Research (INER) for impact studies. The idea takes the advantage of accelerating plasmas with JxB force toward the muzzle of the gun and then strikes the projecticle to transfer their kinetic energy. Preliminary results indicate that the projecticle velocity of 1.1 km/sec can be achieved routinely with a 1.2-gram stainless steel projectile

  6. Characterization of a dielectric barrier plasma gun discharging at atmospheric pressure

    International Nuclear Information System (INIS)

    Zhang Guangqiu; Ge Yuanjing; Zhang Yuefei; Chen Guangliang

    2004-01-01

    The authors develop a plasma gun based on dielectric barrier discharge and working at atmospheric pressure. A theoretical model to predict the gun discharge voltage is built, which is in agreement with the experimental results. After investigating the characterization of discharging gun and utilizing it for polymerization, authors find that the gun can be used as a source to generate a stable uniform plasma for different plasma-processing technologies. (author)

  7. Numerical modeling of deflagration mode in coaxial plasma guns

    Science.gov (United States)

    Sitaraman, Hariswaran; Raja, Laxminarayan

    2012-10-01

    Pulsed coaxial plasma guns have been used in several applications in the field of space propulsion, nuclear fusion and materials processing. These devices operate in two modes based on the delay between gas injection and breakdown initiation. Larger delay led to the plasma detonation mode where a compression wave in the form of a luminous front propagates from the breech to the muzzle. Shorter delay led to the more efficient deflagration mode characterized by a relatively diffuse plasma with higher resistivity. The overall physics of the discharge in the two modes of operation and in particular the latter remain relatively unexplored. Here we perform a computational modeling study by solving the non-ideal Magneto-hydrodynamics equations for the quasi-neutral plasma in the coaxial plasma gun. A finite volume formulation on an unstructured mesh framework with an implicit scheme is used to do stable computations. The final work will present details of important species in the plasma, particle energies and Mach number at the muzzle. A comparison of the plasma parameters will be made with the experiments reported in ref. [1]. [4pt] [1] F. R. Poehlmann et al., Phys. Plasmas 17, 123508 (2010)

  8. A steady-state fluid model of the coaxial plasma gun

    International Nuclear Information System (INIS)

    Herziger, G.; Krompholz, H.; Schneider, W.; Schoenbach, K.

    1979-01-01

    The plasma layer in a coaxial plasma gun is considered as a shock front driven by expanding magnetic fields. Analytical steady-state solutions of the fluid equations yield the plasma properties, allowing the scaling of plasma focus devices. (Auth.)

  9. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhang, Jue, E-mail: zhangjue@pku.edu.cn; Fang, Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

    2015-10-15

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

  10. Spectral diagnostic of plasma in the coaxial gun

    International Nuclear Information System (INIS)

    Bacilek, J.; Hruska, J.; Kubes, P.

    1975-01-01

    Plasma ejected from a coaxial plasma gun was investigated spectroscopically. The coaxial gun consisted of two copper coaxial electrodes 57 and 100 mm in diameter, the length of the central electrode being 67 mm. The gun was fed by a 11 μF capacitor bank of 16 kV operating voltage. Hydrogen, helium and air were used as working gases. The emission spectra were recorded with spectrograph ISP-51 and with a monochromator-photomultiplier system. The plasma density reached its maximum of 4x10 15 cm -3 with the ejecting voltage applied some 20 to 30 μs after the gas injection. At this moment also the spectral lines of electrode material were most intensive. The electron temperature calculated from the presence of spectral lines of OII, CII and NII was about 2 eV. The velocity of fast hydrogen ions was 4x10 7 cmsec -1 calculated from the Hsub(β) line. (J.U.)

  11. High density plasma gun generates plasmas at 190 kilometers per second

    Science.gov (United States)

    Espy, P. N.

    1971-01-01

    Gun has thin metal foil disc which positions or localizes gas to be ionized during electrical discharge cycle, overcoming major limiting factor in obtaining such plasmas. Expanding plasma front travels at 190 km/sec, compared to plasmas of 50 to 60 km/sec previously achieved.

  12. Development of Field-Emission Electron Gun from Carbon Nanotubes

    CERN Document Server

    Hozumi, Y

    2004-01-01

    Aiming to use a narrow energy-spread electron beam easily and low costly on injector electron guns, we have been tested field emission cathodes of carbon nanotubes (CNTs). Experiments for these three years brought us important suggestions and a few rules of thumb. Now at last, anode current of 3.0 [A/cm2

  13. Plasma target output from a magnetically augmented, gas-injected, washer-stack plasma gun

    International Nuclear Information System (INIS)

    Osher, J.E.

    1982-01-01

    This article describes a new washer-stack gun design developed for the application of plasma target production for the startup of neutral-beam trapping in a fusion research magnetic confinement system. The gun is a Mo anode type that is D 2 injected and has an auxiliary pulsed magnet for control of plasma-flux mapping. One of the principal features of 2--10-ms duration pulses for gun operation in a suitable magnetic field is the formation of an arc column along magnetic field lines from the gun's central cathode electrode to the vacuum chamber walls (at common anode potential). The primary power output from a 5.0-cm-i.d. gun is typically carried along this arc column by a stream of approximately 2000 A of 50--250-eV electrons. This primary stream of relatively low-density energetic electrons efficiently ionizes the injected gas, forming a quasi-dc source of denser secondary plasma of approx.10 13 /cm 3 at a few eV, which is able to flow or diffuse away along a somewhat larger column of magnetic field lines. In plasma-target production tests on a test stand, a gun operated at a D 2 gas flow of 22 Torr ls -1 yielded 250 A of equivalent plasma flow

  14. Experimental investigation of plasma relaxation using a compact coaxial magnetized plasma gun in a background plasma

    Science.gov (United States)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott; University of New Mexico Collaboration; Los Alamos National Laboratory Collaboration

    2013-10-01

    A compact coaxial plasma gun is employed for experimental studies of plasma relaxation in a low density background plasma. Experiments are being conducted in the linear HelCat device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes within the intergalactic medium. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5-10 kV and ~100 kA. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities ~1.2Cs and densities ~1020 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

  15. Influence of plasma parameters in pulsed plasma gun on modification processes in exposed structural materials

    International Nuclear Information System (INIS)

    Byrka, O.V.; Bandura, A.N.; Chebotarev, V.V.; Garkusha, I.E.; Garkusha, V.V.; Makhai, V.A.; Tereshin, V.I.

    2011-01-01

    This paper is focused on investigation of helium, nitrogen and krypton plasma streams generated by pulsed plasma gun (PPA). The main objection of this study is adjustment of plasma treatment regimes for different materials that allows achieving optimal thickness of modified layer with simultaneously minimal value of surface roughness. Features of materials alloying from gas and metallic plasma as a result of the plasma ions mixing with the steel substrate in liquid phase are discussed also.

  16. Production of field-reversed mirror plasma with a coaxial plasma gun

    Science.gov (United States)

    Hartman, C.W.; Shearer, J.W.

    The use of a coaxial plasma gun to produce a plasma ring which is directed into a magnetic field so as to form a field-reversed plasma confined in a magnetic mirror. Plasma thus produced may be used as a target for subsequent neutral beam injection or other similarly produced and projected plasma rings or for direct fusion energy release in a pulsed mode.

  17. Production of field-reversed mirror plasma with a coaxial plasma gun

    International Nuclear Information System (INIS)

    Hartman, C.W.; Shearer, J.W.

    1982-01-01

    The use of a coaxial plasma gun to produce a plasma ring which is directed into a magnetic field so as to form a field-reversed plasma confined in a magnetic mirror. Plasma thus produced may be used as a target for subsequent neutral beam injection or other similarly produced and projected plasma rings or for direct fusion energy release in a pulsed mode

  18. Recent development in high energy plasma production techniques by the deflagration plasma gun

    International Nuclear Information System (INIS)

    Cheng, D.Y.; Chang, C.N.; Tripathi, P.P.

    1983-01-01

    This chapter reports experimental data and experience which establish the phenomenon of deflagration in plasma as unique and with quite different properties from the normal snowplow modes. Demonstrates that extremely high velocities and energies in plasma beams are possible with obvious applications in many field and, in particular, in fusion. Suggests that the potential of deflagration beams' scalability to very high energy quasi-neutral plasma beam is possible with present day technology. Discusses plasma deflagration in a T-tube; coaxial deflagration plasma guns; a typical deflagration gun and its operating procedures; electrical design considerations; kinetic theory point of view of the deflagration acceleration of particles; measurements and results; properties of the deflagration gun; applications; inertial confinement experiments; injection into magnetic confinement systems; interaction experiments; and highly energetic beams

  19. Velocity limitations in coaxial plasma gun experiments with gas mixtures

    International Nuclear Information System (INIS)

    Axnaes, I.

    1976-04-01

    The velocity limitations found in many crossed field plasma experiments with neutral gas present are studied for binary mixtures of H 2 , He, N 2 O 2 , Ne and Ar. The apparatus used is a coaxial plasma gun with an azimuthal magnetic bias field. The discharge parameters are chosen so that the plasma is weakly ionized. In some of the mixtures it is found that one of the components tends to dominate in the sense that only a small amount (regarding volume) of that component is needed for the discharge to adopt a limiting velocity close to that for the pure component. Thus in a mixture between a heavy and a light component having nearly equal ionization potentials the heavy component dominates. Also if there is a considerable difference in ionization potential between the components, the component with the lowest ionization potential tends to dominate. (author)

  20. Studies of the formation of field reversed plasma by a magnetized co-axial plasma gun

    International Nuclear Information System (INIS)

    Turner, W.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Smith, A.C. Jr.

    1980-01-01

    The gun injects axially into a drift tank followed by a magnetic mirror. For the experiments reported here, only the guide coils outside the vacuum vessel and solenoids on the plasma gun electrodes were used; the mirror coil was not energized. A stainless steel flux conserver is placed in the mirror throat to prevent the plasma from contacting the nonconducting vacuum wall in the region of the mirror. An axis encircling array of magnetic loop probes includes four diamagnetic loops and a loop which measures the azimuthally averaged outward pointing radial component of magnetic field. These loop probes are stainless steel jacketed and form a flux conserving boundary (at a radius = 30 cm) for plasma emitted from the gun. A five tip probe that can be positioned anywhere along the axis of the experiment is used to measure internal components of magnetic field

  1. A simple model of the plasma deflagration gun including self-consistent electric and magnetic fields

    International Nuclear Information System (INIS)

    Enloe, C.L.; Reinovsky, R.E.

    1985-01-01

    At the Air Force Weapons Laboratory, interest has continued for some time in energetic plasma injectors. A possible scheme for such a device is the plasma deflagration gun. When the question arose whether it would be possible to scale a deflagration gun to the multi-megajoule energy level, it became clear that a scaling law which described the fun as a circuit element and allowed one to confidently scale gun parameters would be required. The authors sought to develop a scaling law which self-consistently described the current, magnetic field, and velocity profiles in the gun. They based this scaling law on plasma parameters exclusively, abandoning the fluid approach

  2. Production of field-reversed plasma with a magnetized coaxial plasma gun

    International Nuclear Information System (INIS)

    Turner, W.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Smith, A.C. Jr.

    1981-01-01

    Experimental data are presented on the production of field-reversed deuterium plasma by a modified coaxial plasma gun. The coaxial gun is constructed with solenoid coils along the inner and outer electrodes that, together with an external guide field solenoid, form a magnetic cusp at the gun muzzle. The net flux inside the inner electrode is arranged to be opposite the external guide field and is the source of field-reversed flux trapped by the plasma. The electrode length is 145 cm, the diameter of the inner (outer) electrode is 15 cm (32 cm). The gun discharge is driven with a 232-μF 40-kV capacitor bank. Acceleration of plasma through the magnetic cusp at the gun muzzle results in entrainment of field-reversed flux that is detected by magnetic probes 75 cm from the gun muzzle. Field-reversed plasma has been produced for a variety of experimental conditions. In one typical case, the guide magnetic field was B 0 =4.8 kG and the change in axial magnetic field ΔB/sub z/ normalized to B 0 was ΔB/sub z/ /B 0 =-3.1. Total field-reversed flux (poloidal flux) obtained by integrating ΔB/sub z/ profiles is in the range 2 x 10 3 kG cm 2 . Measurement of the orthogonal field component indicates a sizable toroidal field peaked off axis at rapprox. =10 cm with a magnitude of roughly one-half the poloidal field component that is measured on magnetic axis. Reconnection of the poloidal field lines has not been established for the data reported in the paper and will be addressed in future experiments which attempt to trap and confine the field-reversed plasma in a magnetic mirror

  3. Investigation and optimisation of a plasma cathode electron beam gun for material processing applications

    OpenAIRE

    Del Pozo Rodriguez, Sofia

    2016-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University London. This thesis describes design, development and testing work on a plasma cathode electron beam gun as well as plasma diagnosis experiments and Electron Beam (EB) current measurements carried out with the aim of maximising the power of the EB extracted and optimising the electron beam gun system for material processing applications. The elements which influence EB gun design are described...

  4. Understanding plasma spraying process and characteristics of DC-arc plasma gun (PJ-100

    Directory of Open Access Journals (Sweden)

    Jovana Ružić

    2012-12-01

    Full Text Available The thermal spray processes are a group of coating processes used to apply metallic or non-metallic coatings. In these processes energy sources are used to heat the coating material (in the form of powder, wire, or rod form to a molten or semi-molten state and accelerated towards a prepared surface by either carrier gases or atomization jets. In plasma spraying process, the spraying material is generally in the form of powder and requires a carrier gas to feed the powder into the plasma jet, which is passing between the hot cathode and the cylindrical nozzle-shaped anode. The design of DC plasma gun (PJ - 100 is designed and manufactured in Serbia. Plasma spaying process, the powder injection with the heat, momentum and mass transfers between particles and plasma jet, and the latest developments related to the production of DC plasma gun are described in this article.

  5. 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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (author)

  7. Ion-plasma gun for ion-milling machine

    Science.gov (United States)

    Kaminsky, Manfred S.; Campana, Jr., Thomas J.

    1976-01-01

    An ion gun includes an elongated electrode with a hollow end portion closed by a perforated end plate. The end plate is positioned parallel to a perforated flat electrode of opposite electrical polarity. An insulated sleeve encompasses the elongated electrode and extends outwardly from the perforated end towards the flat electrode. The sleeve length is separated into two portions of different materials. The first is formed of a high-temperature material that extends over the hollow portion of the elongated electrode where the arc is initiated by a point source electrode. The second sleeve portion extending over the remainder of the elongated electrode is of a resilient material for enhanced seal-forming ability and retention of plasma gas. Perforations are arranged in the flat electrode in a mutually opposing triangular pattern to project a plasma beam having a generally flat current profile towards a target requiring precision milling.

  8. 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.

  9. 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.

  10. Counter-facing plasma guns for efficient extreme ultra-violet plasma light source

    Science.gov (United States)

    Kuroda, Yusuke; Yamamoto, Akiko; Kuwabara, Hajime; Nakajima, Mitsuo; Kawamura, Tohru; Horioka, Kazuhiko

    2013-11-01

    A plasma focus system composed of a pair of counter-facing coaxial guns was proposed as a long-pulse and/or repetitive high energy density plasma source. We applied Li as the source of plasma for improvement of the conversion efficiency, the spectral purity, and the repetition capability. For operation of the system with ideal counter-facing plasma focus mode, we changed the system from simple coaxial geometry to a multi-channel configuration. We applied a laser trigger to make synchronous multi-channel discharges with low jitter. The results indicated that the configuration is promising to make a high energy density plasma with high spectral efficiency.

  11. Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

    Science.gov (United States)

    Robert, E.; Sarron, V.; Riès, D.; Dozias, S.; Vandamme, M.; Pouvesle, J.-M.

    2012-06-01

    An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 107-108 cm s-1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications.

  12. Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

    International Nuclear Information System (INIS)

    Robert, E; Sarron, V; Riès, D; Dozias, S; Vandamme, M; Pouvesle, J-M

    2012-01-01

    An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 10 7 –10 8 cm s −1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications. (paper)

  13. Some experimental results of plasma cumulation in a rod plasma gun obtained by means of laser interferometry

    International Nuclear Information System (INIS)

    Appelt, J.; Kurzyna, J.

    1980-01-01

    Some experimental studies of the plasma gun with ''particle transparent'' electrodes are described. In order to ascertain whether a plasma cumulation occurred the laser interferometry and soft X-ray measurements have been applied. The filament shaped plasma formation was observed with densities of the order of 10 18 cm -3 . A strong correlation between the occurrence of a dense plasma and the voltage peak at the gun electrodes was established. (author)

  14. The Influence of the Axial Magnetic Field Upon-the Coaxial Plasma Gun Parameters

    International Nuclear Information System (INIS)

    El-Aragi, G.M.; EL-Demrdash, A.

    2001-01-01

    This study concerns with the influence of an applied axial magnetic field upon the electrical parameters of a coaxial plasma gun device. The experimental results are investigated with 0.5 KJ plasma gun device operated with argon gas at a pressure of 3.5 Torr. An axial time independent magnetic field with intensity of 550 G is introduced along the plasma current sheath axial region, within the annular space between the two coaxial electrodes. From the measurements of the discharge current I(t) and the voltage V(t), the electrical discharge parameters of the plasma gun device and the plasma current sheath implosion velocity are estimated, in normal mode of plasma gun operation and in the mode of presence external axial magnetic field. A comparison between these two modes is studied

  15. Formation of compact toroidal plasmas by magnetized coaxial plasma gun injection into an oblate flux conserver

    International Nuclear Information System (INIS)

    Turner, W.C.; Goldenbaum, G.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Smith, A.C. Jr.

    1980-01-01

    Initial results are reported on the formation of compact toroidal plasmas in an oblate shaped metallic flux conserver. A schematic of the experimental apparatus is shown. The plasma injector is a coaxial plasma gun with solenoid coils wound on the inner and outer electrodes. The electrode length is 100 cm, the diameter of the inner (outer) electrode is 19.3 cm (32.4 cm). Deuterium gas is puffed into the region between electrodes by eight pulsed valves located on the outer electrode 50 cm from the end of the gun. The gun injects into a cylindrically symmetrical copper shell (wall thickness = 1.6 mm) which acts as a flux conserver for the time scale of experiments reported here. The copper shell consists of a transition cylinder 30 cm long, 34 cm in diameter, a cylindrical oblate pill box 40 cm long, 75 cm in diameter and a downstream cylinder 30 cm long, 30 cm in diameter. The gap between the gun and transition cylinder is 6 cm. An axial array of coils outside the vacuum chamber can be used to establish an initial uniform bias field

  16. Low-energy plasma-cathode electron gun with a perforated emission electrode

    Science.gov (United States)

    Burdovitsin, Victor; Kazakov, Andrey; Medovnik, Alexander; Oks, Efim; Tyunkov, Andrey

    2017-11-01

    We describe research of influence of the geometric parameters of perforated electrode on emission parameters of a plasma cathode electron gun generating continuous electron beams at gas pressure 5-6 Pa. It is shown, that the emission current increases with increasing the hole diameters and decreasing the thickness of the perforated emission electrode. Plasma-cathode gun with perforated electron can provide electron extraction with an efficiency of up to 72 %. It is shown, that the current-voltage characteristic of the electron gun with a perforated emission electrode differs from that of similar guns with fine mesh grid electrode. The plasma-cathode electron gun with perforated emission electrode is used for electron beam welding and sintering.

  17. Use of coaxial plasma guns to start up field-reversed-mirror reactors

    International Nuclear Information System (INIS)

    Smith, A.C. Jr.; Carlson, G.A.; Eddleman, J.L.; Hartman, C.W.; Neef, W.S. Jr.

    1980-01-01

    Application of a magnetized coaxial plasma gun for start-up of a field-reversed-mirror reactor is considered. The design is based on preliminary scaling laws and is compared to the design of the start-up gun used in the Beta II experiment

  18. Time-dependent plasma behavior triggered by a pulsed electron gun under conditions of beam-plasma-discharge

    International Nuclear Information System (INIS)

    Szuszczewicz, E.P.; Lin, C.S.

    1982-01-01

    This chapter reports on experiments whose purpose was to simulate spaceborne applications of energetic electron guns while exploring the ''in situ'' diagnostics of time-dependent beam-plasma behavior under pulsed electron gun conditions. Beam-plasma-discharge (BPD), the BPD afterglow that exists after gun-pulse termination, and the plasma decay process are considered. It is concluded that there is a rapid enhancement in plasma density as the gas turns on; that during the pulse-ON time a quasi-steady-state BPD can be maintained with characteristics identical with its dc counterpart; that in the period immediately following gun-pulse termination the plasma loss process is dominated by cross-field radial diffusion; and that the afterglow plasma is within + or -10% of being an isodensity contour

  19. Startup of reversed-field mirror reactors using coaxial plasma guns

    International Nuclear Information System (INIS)

    Smith, A.C. Jr.; Hartman, C.W.; Carlson, G.A.; Neef, W.S. Jr.; Eddleman, J.L.

    1979-01-01

    Preliminary calculations are given that indicate that a coaxial plasma gun might scale reasonably to reactor-grade operating conditions. Ongoing experiments and numerical simulations should shed some light on the validity of the described scaling laws

  20. Design and experiment of high-current low-pressure plasma-cathode e-gun

    International Nuclear Information System (INIS)

    Xie Wenkai; Li Xiaoyun; Wang Bin; Meng Lin; Yan Yang; Gao Xinyan

    2006-01-01

    The preliminary design of a new high-power low pressure plasma-cathode e-gun is presented. Based on the hollow cathode effect and low-pressure glow discharge empirical formulas, the hollow cathode, the accelerating gap, and the working gas pressure region are given. The general experimental device of the low-pressure plasma cathode electron-gun generating high current density e-beam source is shown. Experiments has been done in continuous filled-in gases and gases-puff condition, and the discharging current of 150-200 A, the width of 60 μs and the collector current of 30-80 A, the width of 60 μs are obtained. The results show that the new plasma cathode e-gun can take the place of material cathode e-gun, especially in plasma filled microwave tubes. (authors)

  1. Injection of a coaxial-gun-produced magnetized plasma into a background helicon plasma

    Science.gov (United States)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott

    2014-10-01

    A compact coaxial plasma gun is employed for experimental investigation of plasma bubble relaxation into a lower density background plasma. Experiments are being conducted in the linear device HelCat at UNM. The gun is powered by a 120-uF ignitron-switched capacitor bank, which is operated in a range of 5 to 10 kV and 100 kA. Multiple diagnostics are employed to investigate the plasma relaxation process. Magnetized argon plasma bubbles with velocities 1.2Cs, densities 1020 m-3 and electron temperature 13eV have been achieved. The background helicon plasma has density 1013 m-3, magnetic field from 200 to 500 Gauss and electron temperature 1eV. Several distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. Additionally a B-dot probe array has been employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify plasma bubble configurations. Experimental data and analysis will be presented.

  2. Production of a rapidly rotating plasma by cross-field injection of gun-produced plasma

    International Nuclear Information System (INIS)

    Ohzu, Akira; Ikehata, Takashi; Tanabe, Toshio; Mase, Hiroshi

    1984-01-01

    Cross-field plasma injection with use of a JxB plasma gun is described as a method to produce rapidly rotating plasma in a crossed electric and magnetic field system. The rotational velocity of the plasma is seriously limited by neutrals surrounding the plasma through strong interactions at the boundary layer. The concentration of neutrals can be reduced by the injection of fully or partially ionized plasma into the discharge volume instead of filling the volume with an operating gas. With use of this method, it is observed that the rotational velocity increases by a factor of 2 to 3 when compared with the conventional method of stationary gas-filling. (author)

  3. Centrifugal mass separation in rotating plasmas produced by a coaxial plasma gun

    International Nuclear Information System (INIS)

    Ikehata, T.; Suzuki, M.; Tanabe, T.; Mase, H.

    1989-01-01

    Rotating Cu/Zn plasmas produced by a coaxial plasma gun have been applied to plasma centrifuge. A separation factor of up to 10 is measured over a radius of 4 cm when a current of 13 kA and an axial magnetic field of 2.5 kG are applied. Plasma parameters are: rotation frequency ω=1.1x10 6 rad/s, density n∼10 15 cm -3 , and ion temperature T i =10 eV. The separation factor of 2 is attained even in the plasma core where the density is higher than one-half of the peak value. This is attributed to the fact that a strong centrifugal force forms a hollow density profile which gives the density peak at a radius of 2 cm

  4. Counter-facing plasma guns for efficient extreme ultra-violet plasma light source

    Directory of Open Access Journals (Sweden)

    Kuroda Yusuke

    2013-11-01

    Full Text Available A plasma focus system composed of a pair of counter-facing coaxial guns was proposed as a long-pulse and/or repetitive high energy density plasma source. We applied Li as the source of plasma for improvement of the conversion efficiency, the spectral purity, and the repetition capability. For operation of the system with ideal counter-facing plasma focus mode, we changed the system from simple coaxial geometry to a multi-channel configuration. We applied a laser trigger to make synchronous multi-channel discharges with low jitter. The results indicated that the configuration is promising to make a high energy density plasma with high spectral efficiency.

  5. Efficient trap of a coaxial gun plasma in an axisymmetric mirror with an internal hoop

    International Nuclear Information System (INIS)

    Asano, Shiro; Ihara, Makoto; Fukao, Masayuki

    1989-01-01

    A method to trap a high temperature and high density plasma from a coaxial gun in a mirror machine is described. The method is to inject plasma parallel to the axis from a coaxial gun located off the axis. The validity of the method is experimentally demonstrated with an MHD-stabilized axisymmetric mirror with an internal hoop. Density, electron and ion temperatures and their time behaviors were measured and it was made clear that a high density high temperature plasma was well trapped in the mirror by the parallel off-axis injection while the plasma was little trapped by on-axis injection. The plasma parameters obtained were also compared with those of a conventional titanium washer gun plasma. The causes to restrict the maximum ion temperature and of its quick decay are discussed. (author)

  6. Deposition of SiOx on Metal Surface with a DBD Plasma Gun at Atmospheric Pressure for Corrosion Prevention

    International Nuclear Information System (INIS)

    Han Erli; Chen Qiang; Zhang Yuefei; Chen Fei; Ge Yuanjing

    2007-01-01

    In this study, SiO x films were deposited by a dielectric barrier discharge (DBD) plasma gun at an atmospheric pressure. The relationship of the film structures with plasma powers was investigated by Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). It was shown that an uniform and cross-linking structure film was formed by the DBD gun. As an application, the SiO x films were deposited on a carbon steel surface for the anti-corrosion purpose. The experiment was carried out in a 0.1 M NaCl solution. It was found that a very good anti-corrosive property was obtained, i.e., the corrosion rate was decreased c.a. 15 times in 5% NaCl solution compared to the non-SiO x coated steel, as detected by the potentiodynamic polarization measurement

  7. Enhancement of ECR performances by means of carbon nano-tubes based electron guns

    International Nuclear Information System (INIS)

    Odorici, F.; Cuffiani, M.; Malferrari, L.; Rizzoli, R.; Veronese, G.P.; Celona, L.; Gammino, S.; Mascali, D.; Miracoli, R.; Romano, F.P.; Gambino, N.; Castro, G.; Ciavola, G.; Serafino, T.

    2012-01-01

    The CANTES experiment at INFN-LNS tested the use of carbon nano-tubes (CNTs) to emit electrons by field emission effect, in order to provide additional electrons to the plasma core of an ECR ion source. This technique was used with the Caesar source, demonstrating that the total extracted ion current is increased and that a relevant reduction of the number of 'high energy' electrons (above 100 keV) may be observed. The injection of additional electrons inside the plasma increases the amount of cold and warm electrons, and then the number of ionizing collisions. Details of the construction of CNTs based electron gun and of the improvement of performances of the Caesar ECR ion source will be presented. The paper is followed by the associated poster. (authors)

  8. Coaxial Plasma Gun Development for the ARPA-E PLX- α Project

    Science.gov (United States)

    Witherspoon, F. Douglas; Case, Andrew; Brockington, Samuel

    2015-11-01

    We describe the renewed effort to design and build coaxial plasma guns appropriate for a scaling study of spherically imploding plasma liners as a standoff magneto-inertial-fusion driver under the ARPA-E Accelerating Low-Cost Plasma Heating And Assembly (ALPHA) program. HyperV joins LANL, UAH, UNM, BNL, and Tech-X to develop, build, operate and analyze a 60 plasma gun experiment using the existing PLX facility at LANL. The guns will be designed to operate over a scaling range of operating parameters: 0.5-5.0 mg of Ar, Ne, N2, Kr, and Xe; 20-60 km/s; 1016 -1017 cm-3 muzzle density; and up to 7.5 kJ stored energy per gun. Each gun is planned to incorporate contoured gaps, fast dense gas injection and triggering, and innovative integral sparkgap switching and pfn configurations to reduce inductance, cost, and complexity, and to increase efficiency and system reliability. We will describe the overall design approach for the guns and pulsed power systems. This work supported by the ARPA-E ALPHA Program.

  9. Studies of the ablated plasma from experimental plasma gun disruption simulations

    International Nuclear Information System (INIS)

    Rockett, P.D.; Hunter, J.A.; Bradley, J.T. III; Gahl, J.M.; Litunovsky, V.N.; Ovchinnokov, I.B.; Ljublin, B.V.; Kuznetsov, B.E.; Titov, V.A.; Zhitlukhin, A.; Arkhipov, K.; Bakhtin, V.; Toporkov, D.

    1995-01-01

    Extensive simulations of tokamak disruptions have provided a picture of material erosion that is limited by the transfer of energy from the incident plasma to the armor solid surface through a dense plasma shield. Radiation spectra were recorded in the VUV and in the visible at the Efremov Laboratories on VIKA using graphite targets. The VUV data were recorded with a Sandia Labs transmission grating spectrograph, covering 1-40 nm. Plasma parameters were evaluated with incident plasma energy densities varying from 10-100 MJ/m 2 . A second transmission grating spectrograph was taken to 2MK-200 at TRINITI to study the plasma-material interface in magnetic cusp plasma. Target materials included POCO graphite, ATJ graphite, boron nitride, and plasma-sprayed tungsten. Detailed spectra were recorded with a spatial resolution of similar 1 mm. Time-resolved data with 40-200 ns resolution was also recorded. The data from both plasma gun facilities demonstrated that the hottest plasma region was sitting several millimeters above the armor tile surface. ((orig.))

  10. Stimulation of plasma waves by electron guns on the ISEE-1 satellite

    International Nuclear Information System (INIS)

    Lebreton, J.P.; Anderson, R.; Harvey, C.; Torbert, R.

    1982-01-01

    This chapter describes typical observations of the waves stimulated during the electron injections, when the spacecraft is passing through the magnetosphere, the magnetosheath and the solar wind. Topics considered include orbits of gun electrons, an electric field antenna, gun operation in the magnetosphere, natural waves in the magnetosheath and the solar wind, gun operation magnetosheath, and gun operation in the solar wind. A coupling mechanism between the electron plasma mode and streaming electrons with energies higher than the thermal speed of the cold electron population is proposed to explain the observations above the electron plasma frequency. It is demonstrated that on board the ISEE-1 satellite, the injection of an electron beam current of the order of 10 to 60 251A with energies ranging from 0 to 40 eV produced enhancements in the electric wave spectrum

  11. Design and operation of a coaxial plasma gun at magnetic fields exceeding 0.5 megagauss

    International Nuclear Information System (INIS)

    Conte, D.; Bird, G.; Boyer, C.; Davis, J.; Seiler, S.; Turchi, P.

    1981-01-01

    The use of coaxial plasma guns to accumulate and concentrate electromagnetic and kinetic energy at high currents and power flux levels has been examined experimentally. For these studies, apparatus was designed to employ magnetic fields approaching 1MG, using the AFWL Shiva capacitor bank as the current source (1.9 MJ, 120 KV). The design divided the system into two major component regions: 1) a reusable cylindrical transition to the Shiva bank, an 2) disposable guns and feed plates

  12. Innocent Bystanders and Smoking Guns: Dwarf Carbon Stars

    Science.gov (United States)

    Green, Paul J.

    2014-01-01

    As far as we know, most carbon throughout the Universe is created and dispersed by AGB stars. So it was at first surprising to find that the carbon stars most prevalent in the Galaxy are in fact dwarfs. We suspect that dC stars are most likely innocent bystanders in post-mass transfer binaries, and may be predominantly metal-poor. Among 1200 C stars found in the SDSS (Green 2013), we confirm 724 dCs, of which a dozen are DA/dC stars in composite spectrum binaries, quadrupling the total sample of these "smoking guns" for AGB binary mass transfer. The dCs likely span absolute magnitudes M_i from about 6.5 to 10.5. G-type dC stars with weak CN and relatively blue colors are probably the most massive dCs still cool enough to show C_2 bands. Eleven very red C stars with strong red CN bands appear to be N-type AGB stars at large Galactocentric distances, one likely a new discovery in the dIrr galaxy Le A. Two such stars within 30arcmin of each other may trace a previously unidentified dwarf galaxy or tidal stream at ~40 kpc. We describe follow-up projects to study the spatial, kinematic, and binary properties of these C-enriched dwarfs.

  13. Investigations of the magnetic structure and the decay of a plasma-gun-generated compact torus

    International Nuclear Information System (INIS)

    Turner, W.C.; Goldenbaum, G.C.; Granneman, E.H.A.; Hammer, J.H.; Hartman, C.W.; Prono, D.S.; Taska, J.

    1983-01-01

    The results of a series of experimental measurements of compact toroidal (CT) plasmas produced by a magnetized coaxial plasma gun injecting into a flux-conserving metallic liner are reported. The experiments were performed on the Beta II facility at Lawrence Livermore National Laboratory. The magnetic equilibria are well described by a force-free eigenmode structure that results from an extension of Taylor's theory of the reversed-field pinch. Consideration of helicity conservation during relaxation of the composite plasma-gun flux-conserver system to the final state equilibrium yields theoretical expressions that are compared with the experiment

  14. Studies of the ablated plasma from experimental plasma gun disruption simulations

    International Nuclear Information System (INIS)

    Rockett, P.D.; Hunter, J.A.; Bradley, J.T.

    1994-01-01

    Extensive simulations of Tokamak disruptions have provided a picture of material erosion that is limited by the transfer of energy from the incident plasma to the armor solid surface through a dense vapor shield. Radiation spectra were recorded in the VUV and in the visible at the Efremov Laboratories on VIKA using graphite targets. The VUV data were recorded with a Sandia Labs transmission grating spectrograph, covering 1--40 nm. Plasma parameters were evaluated with incident plasma energy densities varying from 1--10 kJ/cm 2 . A second transmission grating spectrograph was taken to 2MK-200 at TRINITI to study the plasma-material interface in magnetic cusp plasma. Target materials included POCO graphite, ATJ graphite, boron nitride, and plasma-sprayed tungsten. Detailed spectra were recorded with a spatial resolution of ∼1 mm resolution. Time-resolved data with 40--200 ns resolution was also recorded. The data from both plasma gun facilities demonstrated that the hottest plasma region was sitting several millimeters above the armor tile surface

  15. The geomagnetic field - An explanation for the microturbulence in coaxial gun plasmas

    International Nuclear Information System (INIS)

    Mather, J.W.; Ahluwalia, H.S.

    1988-01-01

    The authors describe the complexity introduced by the geomagnetic field in several regions of a coaxial gun plasma device. It is shown that the annihilation of the swept-up geomagnetic flux, trapped within the highly compressed turbulent plasma, provides an explanation for varied performance and experimental results

  16. Results from AFWL 230 kJ coaxial plasma gun experiments

    International Nuclear Information System (INIS)

    Hall, D.J.; Baker, W.L.; Beason, J.D.; Clouse, C.J.; Degnan, J.H.; Dietz, D.; Hackett, K.E.; Higgins, P.L.; Holmes, J.L.; Price, D.W.

    1988-01-01

    A coaxial plasma gun has been operated on the AFWL 0.5 MJ capacitor bank. A Marshall valve actuated by an explosive detonator is used to puff hydrogen gas from a small high pressure plenum into the breech of the gun. After a set delay from the explosion the capacitor bank is discharged across the electrodes of the coaxial gun. The operating mode of the gun can be changed by varying the plenum pressure and the firing delay. Over 150 shots have been fired, varying delay, plenum pressure, and initial stored energy. Initial plenum pressures were varied from 250 to 750 psi, and firing delays ranged from 0.8 msec to 2.2 msec. Experiments were conducted at 90, 176, and 230 kJ of initial stored energy (50, 70, adn 80 kV charge). Rogowski coils were used to measure current and magnetic field within the plasma at 25 axial locations along the gun. The coils were installed in grooves on the inner surface of the outer conductor. Signals from the coils were passively integrated. Integrator time constants ranged from 95 to 114 μsec. Time histories of magnetic field profiles are presented. These are used to describe the operating mode of the gun

  17. Experimental investigation of vapor shielding effects induced by ELM-like pulsed plasma loads using the double plasma gun device

    Science.gov (United States)

    Sakuma, I.; Kikuchi, Y.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M.

    2015-08-01

    We have developed a unique experimental device of so-called double plasma gun, which consists of two magnetized coaxial plasma gun (MCPG) devices, in order to clarify effects of vapor shielding on material erosion due to transient events in magnetically confined fusion devices. Two ELM-like pulsed plasmas produced by the two MCPG devices were injected into a target chamber with a variable time difference. For generating ablated plasmas in front of a target material, an aluminum foil sample in the target chamber was exposed to a pulsed plasma produced by the 1st MCPG device. The 2nd pulsed plasma was produced with a time delay of 70 μs. It was found that a surface absorbed energy measured by a calorimeter was reduced to ∼66% of that without the Al foil sample. Thus, the reduction of the incoming plasma energy by the vapor shielding effect was successfully demonstrated in the present experiment.

  18. Experimental investigation of vapor shielding effects induced by ELM-like pulsed plasma loads using the double plasma gun device

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, I., E-mail: eu13z002@steng.u-hyogo.ac.jp; Kikuchi, Y.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M.

    2015-08-15

    We have developed a unique experimental device of so-called double plasma gun, which consists of two magnetized coaxial plasma gun (MCPG) devices, in order to clarify effects of vapor shielding on material erosion due to transient events in magnetically confined fusion devices. Two ELM-like pulsed plasmas produced by the two MCPG devices were injected into a target chamber with a variable time difference. For generating ablated plasmas in front of a target material, an aluminum foil sample in the target chamber was exposed to a pulsed plasma produced by the 1st MCPG device. The 2nd pulsed plasma was produced with a time delay of 70 μs. It was found that a surface absorbed energy measured by a calorimeter was reduced to ∼66% of that without the Al foil sample. Thus, the reduction of the incoming plasma energy by the vapor shielding effect was successfully demonstrated in the present experiment.

  19. New mode of operating a magnetized coaxial plasma gun for injecting magnetic helicity into a spheromak

    International Nuclear Information System (INIS)

    Woodruff, S.; Hill, D.N.; Stallard, B.W.; Bulmer, R.; Cohen, B.; Holcomb, C.T.; Hooper, E.B.; McLean, H.S.; Moller, J.; Wood, R.D.

    2003-01-01

    By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (∼1 kV) are produced, giving the highest sustained voltage ∼500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B-tilde)/B≥2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments

  20. New mode of operating a magnetized coaxial plasma gun for injecting magnetic helicity into a spheromak.

    Science.gov (United States)

    Woodruff, S; Hill, D N; Stallard, B W; Bulmer, R; Cohen, B; Holcomb, C T; Hooper, E B; McLean, H S; Moller, J; Wood, R D

    2003-03-07

    By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (approximately 1 kV) are produced, giving the highest sustained voltage approximately 500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B/B>/=2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments.

  1. Large density amplification measured on jets ejected from a magnetized plasma gun

    OpenAIRE

    Yun, Gunsu S.; You, Setthivoine; Bellan, Paul M.

    2007-01-01

    Observation of a large density amplification in the collimating plasma jet ejected from a coplanar coaxial plasma gun is reported. The jet velocity is ~30 km s^-1 and the electron density increases from ~10^20 to 10^(22–23) m^-3. In previous spheromak experiments, electron density of the order 10^(19–21) m^-3 had been measured in the flux conserver region, but no density measurement had been reported for the source gun region. The coplanar geometry of our electrodes permits direct observation...

  2. Direct morphological comparison of vacuum plasma sprayed and detonation gun sprayed hydroxyapatite coatings for orthopaedic applications.

    Science.gov (United States)

    Gledhill, H C; Turner, I G; Doyle, C

    1999-02-01

    Hydroxyapatite coatings on titanium substrates were produced using two thermal spray techniques vacuum plasma spraying and detonation gun spraying. X-ray diffraction was used to compare crystallinity and residual stresses in the coatings. Porosity was measured using optical microscopy in conjunction with an image analysis system. Scanning electron microscopy and surface roughness measurements were used to characterise the surface morphologies of the coatings. The vacuum plasma sprayed coatings were found to have a lower residual stress, a higher crystallinity and a higher level of porosity than the detonation gun coatings. It is concluded that consideration needs to be given to the significance of such variations within the clinical context.

  3. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    Science.gov (United States)

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

  4. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter

    International Nuclear Information System (INIS)

    Vizir, A. V.; Tyunkov, A. V.; Shandrikov, M. V.; Oks, E. M.

    2010-01-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10 9 cm -3 at an operating gas pressure in the vacuum chamber of less than 2x10 -2 Pa. The device features high power efficiency, design simplicity, and compactness.

  5. The electrical Discharge Characteristics of the 3.5 KJ Electrothermal Plasma Gun Experiment

    International Nuclear Information System (INIS)

    Diab, F.; El-Aragi, G.M.; El-Kashef, G.M.; Saudy, A.H.

    2013-01-01

    In order to better understand the operating characteristics of an electrothermal plasma gun and its design, a variety of operation characteristics including ( the length of the capillary, applied voltage, diameter of the capillary tube, circuit inductance) were investigated to determine performance effects and viability in a real system. An Electrothermal Plasma Gun (ETG) is composed of a capillary discharge tube made of Teflon operated with simple RLC circuit. The device called Electrothermal Gun (ETG) which is composed of 4 capacitors (70 μF, 10 kV, 1.3 μH) connected in parallel to a plasma source by means of one high power plane transmission line by mean of a switch triggered by negative pulse 360/385 V. For the present studies a simple RLC was chosen, which allowed the circuit parameters to be easily measure d. The electrothermal discharge characteristics of the plasma gun operated in open air, So that at atmospheric pressure the main parameters were measured. The gun voltage and discharge current are measured with voltage divider and Rogowiski coil respectively. From the results recorded we found that, the current lagged the voltage i-e the plasma source has an inductive reactivity. Moreover, the current value was changed by changing the circuit parameters, including the discharge voltage and circuit inductance, and the wire properties such as the length and diameter. The maximum gun current ranged between (5 - 50 KA) according to the charging voltage of capacitors between (1-7 KV), a typical discharge times are on the order r of 125 μS.

  6. Vacuum UV spectroscopy of armor erosion from plasma gun disruption simulation experiments

    International Nuclear Information System (INIS)

    Rockett, P.D.; Gahl, J.M.; Zhitlukhin, A.; Arkhipov, K.; Bakhtin, V.; Toporkov, D.; Ovchinnokov, I.; Kuznetsov, V.E.; Titov, V.A.

    1995-01-01

    Extensive simulations of tokamak disruptions have provided a picture of material erosion that is limited by the transfer of energy from the incident plasma to the armor solid surface through a dense vapor shield. Two transmission grating vacuum ultraviolet (VUV) spectrographs were designed and utilized to study the plasma-material interface in plasma gun simulation experiments. Target materials included POCO graphite, ATJ graphite, boron nitride and plasma-sprayed tungsten. Detailed spectra were recorded with a spatial resolution of ca. 0.7mm resolution on VIKA at Efremov and on 2MK-200 at Troitsk. Time-resolved data with 40-200ns resolution were then recorded along with the same spatial resolution on 2MK-200. The VIKA plasma gun directly illuminated a target with a high-intensity plasma pulse of 2-100MJm -2 with low-energy ions of ca. 100eV. The 2MK-200 plasma gun illuminated the target via a magnetic cusp that permitted only deuterium to pass with energies of ca. 1keV, but which produced a fairly low intensity of 2MJm -2 . Power densities on target ranged from 10 7 to 10 8 Wcm -2 . Emitted spectra were recorded from 15 to 450A over a distance from 0 to 7cm above the armor target surface. The data from both plasma gun facilities demonstrated that the hottest plasma region was sitting several millimeters above the armor tile surface. This apparently constituted the absorption region, which confirmed past computer simulations. Spectra indicated both the species and ionization level that were being ablated from the target, demonstrating impurity content, and showing plasma ablation velocity. Graphite samples clearly showed CV lines as well as impurity lines from O V and O VI. The BN tiles produced textbook examples of BIV and BV, and extensive NIV, V and VI lines. These are being compared with radiation-hydrodynamic calculations. (orig.)

  7. Design and experimental results of a new electron gun using a magnetic multipole plasma generator

    International Nuclear Information System (INIS)

    Tanaka, S.; Yokoyama, K.; Akiba, M.; Araki, M.; Dairaku, M.; Inoue, T.; Mizuno, M.; Okumura, Y.; Ohara, Y.; Seki, M.; Watanabe, K.

    1991-01-01

    A new electron gun utilizing a magnetic multipole plasma generator was designed and fabricated as the heat source of the high heat flux test facility, called JEBIS (JAERI electron beam irradiation stand). By changing the acceleration grids, this electron gun is able to produce a pencil to a sheetlike electron beams up to 4 A at 100 keV for 1 ms to continuous mode. In this electron gun, magnetic lens system is not adopted to focus the electron beam, but the space charge neutralization effect by the beam plasma produced downstream of the electron gun is utilized to prevent the blow-up of the electron beam. In addition, high permeability metal is embedded in the first and the second grids to magnetically shield the earth field and the stray field from the beam bending magnet. It was experimentally demonstrated that wide range of heat flux from 0.2 MW/m 2 to over 2000 MW/m 2 can be realized at the test sample position about 1.7 m downstream of the electron gun

  8. Plasma diagnostics by electron guns and electric field probes on ISEE-1

    International Nuclear Information System (INIS)

    Pedersen, A.

    1982-01-01

    The use of electron guns to control the potential of a satellite with conductive surfaces is discussed with reference to the results of the ISEE-1 satellite experiment. The two electron guns carried by the satellite can emit electrons with energies up to 48 eV, and the emitted electron current has a maximum value of 0.5-1.0 mA. The satellite potential, with or without gun operation, can be measured with reference to one or two spherical electric field probes positioned on booms at a distance of 36 m from the satellite. The probes are biased with a negative current from a high-impedance source to be slightly positive (0.5-1.0 V) relative to the plasma, and the spacecraft is normally several volts more positive and can be further positively charged by operating the electron gun. Plasma diagnostics can be carried out by appropriate sweeps of gun currents and energy of emitted electrons to obtain information about density and characteristic energy of ambient electrons. 9 references

  9. Fast-acting calorimeter measures heat output of plasma gun accelerator

    Science.gov (United States)

    Dethlefson, R.; Larson, A. V.; Liebing, L.

    1967-01-01

    Calorimeter measures the exhaust energy from a shot of a pulsed plasma gun accelerator. It has a fast response time and requires only one measurement to determine the total energy. It uses a long ribbon of copper foil wound around a glass frame to form a reentrant cavity.

  10. Application of electron beam equipment based on a plasma cathode gun in additive technology

    Science.gov (United States)

    Galchenko, N. K.; Kolesnikova, K. A.; Semenov, G. V.; Rau, A. G.; Raskoshniy, S. Y.; Bezzubko, A. V.; Dampilon, B. V.; Sorokova, S. N.

    2016-11-01

    The paper discusses the application of electron beam equipment based on a plasma cathode gun for three-dimensional surface modification of metals and alloys. The effect of substrate surface preparation on the adhesion strength of gas thermal coatings has been investigated.

  11. Rail gun performance and plasma characteristics due to wall ablation

    Science.gov (United States)

    Ray, P. K.

    1986-01-01

    The experiment of Bauer, et al. (1982) is analyzed by considering wall ablation and viscous drag in the plasma. Plasma characteristics are evaluated through a simple fluid-mechanical analysis considering only wall ablation. By equating the energy dissipated in the plasma with the radiation heat loss, the average properties of the plasma are determined as a function of time.

  12. Expansion of a plasma injected from an electrodeless gun along a magnetic field

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1978-04-01

    The dynamics of a plasma injected from an electrodeless plasma gun (conical theta pinch) into a longitudinal magnetic field is studied theoretically. For the experiments referred to, conditions are collisionless for the ions and range from collision dominated to collisionless for the electrons. During the expansion of the injected plasma the electrons are trapped by an ambipolar electric field maintaining charge neutrality and a magnetic mirror at the gun. The development of the ion and electron distribution functions for the completely collisionless case is considered in detail. Assuming that the acceleration of the ions is negligible and taking the action integral over an electron oscillation to be an adiabatic invariant self similar solutions are found. The electrons lose energy adiabatically as a result of the plasma expansion and it is suggested that a re-thermalisation process must operate in experimental situations to account for the observed electron energies

  13. Investigation of a washer-stack plasma gun on the Auburn torsatron

    International Nuclear Information System (INIS)

    Austin, M.E. Jr.

    1986-01-01

    A pulsed device for producing a highly-ionized plasma in the Auburn Torsatron is described and construction details given. A plasma is formed by discharging a 14 uF capacitor charged to 6 to 12 kV through a titanium washer impregnated with hydrogen. The ions and electrons are injected transversely into the Torsatron confinement field and the plasma is studied with an x-band microwave interferometer and H-alpha spectral-line detectors. The results of initial measurements to determine the optimal performance parameters for the gun, such as discharge voltage and position, are presented. Also, peak electron density and decay time of the guns plasma are given for different machine and souce conditions

  14. The geomagnetic field - An explanation for the microturbulence in coaxial gun plasmas

    Science.gov (United States)

    Mather, J. W.; Ahluwalia, H. S.

    1988-01-01

    The complexity introduced by the geomagnetic field in several regions of a coaxial gun plasma device is described. It is shown that the annihilation of the swept-up geomagnetic flux, trapped within the highly compressed turbulent plasma, provides an explanation for varied performance and experimental results. The results indicate that the device should be aligned along the direction of the local geomagnetic field or enclosed in a mu-metal shield.

  15. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode

    OpenAIRE

    Poehlmann, Flavio R.; Cappelli, Mark A.; Rieker, Gregory B.

    2010-01-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma def...

  16. Experimental investigation of coaxial-gun-formed plasmas injected into a background transverse magnetic field or plasma

    OpenAIRE

    Zhang, Yue; Fisher, Dustin M.; Gilmore, Mark; Hsu, Scott C.; Lynn, Alan G.

    2017-01-01

    Injection of coaxial-gun-formed magnetized plasmas into a background transverse vacuum magnetic field or into a background magnetized plasma has been studied in the helicon-cathode (HelCat) linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys.81, 345810104 (2015)]. Magnetized plasma jet launched into a background transverse magnetic field shows emergent kink stabilization of the jet due to the formation of a sheared flow in the jet above the kink-stabilizati...

  17. Investigation of the residue in an electric rail gun employing a plasma armature

    Science.gov (United States)

    Bauer, D. P.; Barber, J. P.

    1984-01-01

    The performance of dc electric rail guns using plasma-armature-accelerated projectiles was studied. It was found that the initial rail launcher acceleration profile was consistent with the simulation, but that after the projectile had traveled approximately 25 to 30 cm along the gun, a considerable portion of the current in the projectile armature commutated into a secondary current path. Also noted were the lower than expected muzzle velocities. It was proposed that the secondary current path was a relatively high conductivity layer of residue on the launcher bore.

  18. The Influence of the Axial Magnetic Field Upon- the Coaxial Plasma Gun Parameters

    International Nuclear Information System (INIS)

    El-Aragi, G.M.; El-Demardash, A.

    2001-01-01

    This study concerns with the influence of an applied axial magnetic field upon the electrical parameters and on the brightness (luminance) of argon plasma. The brightness was measured by with a photomultiplier type of IP28 RCA. The experimental results are investigated with plasma gun device operated with argon gas at a pressure of 3.5 Torr. An axial time independent magnetic field with intensity of 550 G is introduced along the plasma current sheath axial region, within the annular space between the two coaxial electrodes. From the measurements of the discharge current I(t) and the voltage V(t), the electrical discharge parameters of the plasma gun device and the plasma current sheath implosion velocity are estimated, in normal mode of plasma gun operation and in the mode of presence external axial magnetic field. A comparison between these two modes is studied. It was found that the thickness of skin-layer δ about 0.01 cm and the wavelength λ, of the perturbation about 1.3 cm i.e. the instability has been satisfied. The growth rate γ of the instability about 10 6 sec -1 . (author)

  19. Waves generated in the vicinity of an argon plasma gun in the ionosphere

    Science.gov (United States)

    Cahill, L. J., Jr.; Arnoldy, R. L.; Lysak, R. L.; Peria, W.; Lynch, K. A.

    1993-01-01

    Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.

  20. Schlieren method diagnostics of plasma compression in front of coaxial gun

    International Nuclear Information System (INIS)

    Kravarik, J.; Kubes, P.; Hruska, J.; Bacilek, J.

    1983-01-01

    The schlieren method employing a movable knife edge placed in the focal plane of a laser beam was used for the diagnostics of plasma produced by a coaxial plasma gun. When compared with the interferometric method reported earlier, spatial resolution was improved by more than one order of magnitude. In the determination of electron density near the gun orifice, spherical symmetry of the current sheath inhomogeneities and cylindrical symmetry of the compression maximum were assumed. Radial variation of electron density could be reconstructed from the photometric measurements of the transversal variation of schlieren light intensity. Due to small plasma dimensions, electron density was determined directly from the knife edge shift necessary for shadowing the corresponding part of the picture. (J.U.)

  1. Effects of the current boundary conditions at the plasma-gun gap on density in SSPX

    Science.gov (United States)

    Kolesnikov, Roman; Lodestro, L. L.; Meyer, W. H.

    2012-10-01

    The Sustained Spheromak Physics Experiment (SSPX) was a toroidal magnetic-confinement device without toroidal magnetic-field coils or a central transformer but which generated core-plasma currents by dynamo processes driven by coaxial plasma-gun injection into a flux-conserving vessel. Record electron temperatures in a spheromak (Te˜500eV) were achieved, and final results of the SSPX program were reported in [1]. Plasma density, which depended strongly on wall conditions, was an important parameter in SSPX. It was observed that density rises with Igun and that confinement improved as the density was lowered. Shortly after the last experiments, a new feature was added to the Corsica code's solver used to reconstruct SSPX equilibria. Motivated by n=0 fields observed in NIMROD simulations of SSPX, an insulating boundary condition was implemented at the plasma-gun gap. Using this option we will perform new reconstructions of SSPX equilibria and look for correlations between the location of the separatrix (which moves up the gun wall and onto the insulating gap as Igun increases) and plasma density and magnetic-flux amplification [2].[4pt] [1] H. S. McLean, APS, DPP, Dallas, TX, 2008.[0pt] [2] E. B. Hooper et al., Nucl. Fusion 47, 1064 (2007).

  2. Control of the Helicity Content of a Gun-Generated Spheromak by Incorporating a Conducting Shell into a Magnetized Coaxial Plasma Gun

    Science.gov (United States)

    Matsumoto, Tadafumi; Sekiguchi, Jun'ichi; Asai, Tomohiko

    In the formation of magnetized plasmoid by a magnetized coaxial plasma gun (MCPG), the magnetic helicity content of the generated plasmoid is one of the critical parameters. Typically, the bias coil to generate a poloidal flux is mounted either on the outer electrode or inside the inner electrode. However, most of the flux generated in the conventional method spreads even radially outside of the formation region. Thus, only a fraction of the total magnetic flux is actually exploited for helicity generation in the plasmoid. In the proposed system, the plasma gun incorporates a copper shell mounted on the outer electrode. By changing the rise time of the discharge bias coil current and the geometrical structure of the shell, the magnetic field structure and its time evolution can be controlled. The effect of the copper shell has been numerically simulated for the actual gun structure, and experimentally confirmed. This may increase the magnetic helicity content results, through increased poloidal magnetic field.

  3. Plasma Dynamics of the Arc-Driven Rail Gun

    Science.gov (United States)

    1980-09-01

    Authors’ unpublished calculations. 11. A.B. Cambel , Plasma Physics and Magnetofluidmechanics (McGraw-Hill New York, 1963), Chap. 8. ’ 16 k T P = (1 +cO...Energy, and Forces (Wiley, New York, 1960), Chap. 9. 10. Authors’ unpublished calculations. 11. A.B. Cambel , Plasma Physics and Magnetofluidmechanics

  4. Compact 5 x 1012 AMP/SEC rail-gun pulser for a laser plasma shutter

    International Nuclear Information System (INIS)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.

    1979-01-01

    We have developed a rail-gun plasma source to produce a plasma of 10 12 cm -3 particle density and project it with a velocity of 3.9 cm/μs. This device will be used in a output spatial filter of Nova to project a critical density plasma across an optical beam path and block laser retroreflected light. The object of this paper is to describe the design of a pulser appropriate to the Shiva laser fusion facility, and to describe the preliminary design of a higher current prototype pulser for Nova the laser fusion research facility under construction at Lawrence Livermore Laboratory

  5. Measurements of the neutron yield from a coaxial gun plasma

    International Nuclear Information System (INIS)

    Zolototrubov, I.M.; Krasnikov, A.A.; Kurishchenko, A.M.; Novikov, Yu.M.; Poryatuj, V.S.; Tolstolutskij, A.G.

    1977-01-01

    Neutron yield from deuterium plasma produced by a pulse coaxial accelerator was measured. The maximum neutron yield with 5 kj stored in a condenser battery is 3x10 6 neutron/pulse. The basis of the method of measuring neutron yield from the plasma was through the induced activity. It was shown that application of even a small uniform longitudinal magnetic field (up to 1 kOe) on the accelerator decreases several times the neutron yield. It is also shown that a small amount of stored discharge energy can produce high-temperature plasma at the output of pulse coaxial accelerator in the absense of the direct magnetic field. It is supposed that the reason for the reduction of neutron yield level in the case of applying the magnetic field is decreasing plasma density because of increasing the bunch cross-section

  6. Acceleration of compact torus plasma rings in a coaxial rail-gun

    International Nuclear Information System (INIS)

    Hartman, C.W.; Hammer, J.H.; Eddleman, J.

    1985-01-01

    We discuss here theoretical studies of magnetic acceleration of Compact Torus plasma rings in a coaxial, rail-gun accelerator. The rings are formed using a magnetized coaxial plasma gun and are accelerated by injection of B/sub theta/ flux from an accelerator bank. After acceleration, the rings enter a focusing cone where the ring is decelerated and reduced in radius. As the ring radius decreases, the ring magnetic energy increases until it equals the entering kinetic energy and the ring stagnates. Scaling laws and numerical calculations of acceleration using a O-D numerical code are presented. 2-D, MHD simulations are shown which demonstrate ring formation, acceleration, and focusing. Finally, 3-D calculations are discussed which determine the ideal MHD stability of the accelerated ring

  7. Ignition Features of Plasma-Beam Discharge in Gas-Discharge Electron Gun Operation

    Directory of Open Access Journals (Sweden)

    Valery A. Tutyk

    2013-01-01

    Full Text Available The current paper presents the results of experimental researches to determine the mode features of plasma-beam discharge (PBD generation by an electron beam injected by a low-vacuum gasdischarge electron gun (LGEG with the cold cathode and hollow anode on the basis of the high-voltage glow discharge and in the range of helium pressure of P ? 10 ÷ 130 Pa. The PBD boundaries and their dependences on parameters of an electron beam are found. The influence of PBD on parameters of low-vacuum gas-discharge electron gun is revealed. It causes an avalanche increase of electron beam current and burning of plasma-beam discharge in the whole space of the vacuum chamber volume and generation of electromagnetic radiation is revealed. Achieved results will be used for implementation of various vacuum technologies in the medium of reaction gas and generated electromagnetic radiation.

  8. Acceleration of compact torus plasma rings in a coaxial rail-gun

    International Nuclear Information System (INIS)

    Hartman, C.W.; Hammer, J.H.; Eddleman, J.

    1986-01-01

    They discuss here theoretical studies of magnetic acceleration of Compact Torus plasma rings in a coaxial, rail-gun accelerator. The rings are formed using a magnetized coaxial plasma gun and are accelerated by injection of B/sub Theta/ flux from an accelerator bank. After acceleration, the rings enter a focusing cone where the ring is decelerated and reduced in radius. As the ring radius decreases, the ring magnetic energy increases until it equals the entering kinetic energy and the ring stagnates. Scaling laws and numerical calculations of acceleration using a O-D numerical code are presented. 2-D, MHD simulations are shown which demonstrate ring formation, acceleration, and focusing. Finally, 3-D calculations are discussed which determine the ideal MHD stability of the accelerated ring

  9. Density profile measurements from a two-gun plasma focus device

    International Nuclear Information System (INIS)

    Tzeng, C.C.; Yen, C.K.; Yeh, T.R.; Kuo, Y.Y.; Shang, D.J.; Yu, Y.Z.; Hou, W.S.

    1990-01-01

    The dynamics of the plasma evolution in a two-gun plasma focus device has been studied using the laser shadowgraphy as well as the laser interferometry. The experiments were carried out from a 700 kJ two-gun plasma focus device reported earlier, which consisted of a pair of Mather type coaxial electrodes connected muzzle to muzzle. Previous results indicated that the simultaneous formation of the two deuterium plasma foci occurred earlier and then after ∼ 100 ns a disk-shaped plasma of ∼ 1.5 cm in diameter appeared in the middle region between the anodes. It is, therefore, the authors' goal to study the density profiles in the plasma foci and the middle region in order to understand further the formation of the plasma foci and their time evolution. The laser shadowgraphy was done with a XeCl excimer pumped dye laser system which operated at 550 nm with pulse width of ∼ 10 ns. The laser interferometry, on the other hand, was carried out using a TEA-TEA oscillator-amplifier N 2 -laser system with 337.1 nm and subnano-second pulse width. Both results show that the maximum electron density is ≥2 x 10 19 cm -3 and, in addition, the growth of the hydrodynamic instabilities are observed. These results together with the detailed density profiles are presented and discussed

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

    Science.gov (United States)

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

    1998-01-01

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

  11. First experiments at the QSPA-Be plasma gun facility

    International Nuclear Information System (INIS)

    Kovalenko, D V; Klimov, N S; Podkovyrov, V L; Muzichenko, A D; Zhitlukhin, A M; Khimchenko, L N; Kupriyanov, I B; Giniyatulin, R N

    2011-01-01

    This paper presents preliminary results on the erosion of beryllium under hydrogen plasma flow. Two samples made of two types of beryllium, TGP-56PS and S-65C, were exposed to plasma heat loads up to 1 MJ m - 2 and a pulse duration of 0.5 ms at the QSPA-Be facility in Bochvar Institute, Russia. The melting threshold for both beryllium types was experimentally determined to be 0.5 MJ m - 2. The dependence of the specific mass loss and erosion rate on pulse number for both beryllium types was measured. The possibility of generating radiation fluxes with parameters corresponding to mitigated ITER disruptions by means of plasma flow shock braking on a solid bar is shown.

  12. First experiments at the QSPA-Be plasma gun facility

    Science.gov (United States)

    Kovalenko, D. V.; Klimov, N. S.; Podkovyrov, V. L.; Muzichenko, A. D.; Zhitlukhin, A. M.; Khimchenko, L. N.; Kupriyanov, I. B.; Giniyatulin, R. N.

    2011-12-01

    This paper presents preliminary results on the erosion of beryllium under hydrogen plasma flow. Two samples made of two types of beryllium, TGP-56PS and S-65C, were exposed to plasma heat loads up to 1 MJ m-2 and a pulse duration of 0.5 ms at the QSPA-Be facility in Bochvar Institute, Russia. The melting threshold for both beryllium types was experimentally determined to be 0.5 MJ m-2. The dependence of the specific mass loss and erosion rate on pulse number for both beryllium types was measured. The possibility of generating radiation fluxes with parameters corresponding to mitigated ITER disruptions by means of plasma flow shock braking on a solid bar is shown.

  13. A low aspect ratio electrothermal gun for metal plasma vapor discharge and ceramic nanopowder production

    International Nuclear Information System (INIS)

    Kim, Kyoung Jin; Peterson, Dennis R.

    2008-01-01

    Traditionally, the electrothermal gun design has the bore of a large aspect ratio: however, a low aspect ratio design with a shorter bore length has been employed for efficient production of metal plasma vapors and synthesis of nanomaterials. In a comparison of the arc resistance-current relationship, a low aspect ratio design is found to exhibit distinctively different characteristics compared to a high aspect ratio design, and this trend is explained by the scaling law of plasma properties including theory of plasma electrical conductivity. A one-dimensional isothermal model has been applied to the present experiments to confirm the scaling laws, and it was found that the present modification of the electrothermal gun is able to produce fully ionized metal plasma vapor, while the plasma vapor produced in a conventional design is partially ionized. Also, by reacting metal plasma vapors with the controlled gases in the reaction chamber, nanoscale materials such as aluminum oxide, aluminum nitride, and titanium oxide were synthesized successfully

  14. Characterization of plasma jet ejected from a parallel-plate rail gun for simulating edge localized mode

    International Nuclear Information System (INIS)

    Chung, K.S.; Chung, Kyoung-Jae; Jung, B.K.; Hwang, Y.S.

    2013-01-01

    Highlights: • A small plasma gun is constructed to study edge localized mode. • A plasma jet ejected from the gun is characterized with a quadruple Langmuir probe. • The device and diagnostics are suitable for research about the control of plasma jet. -- Abstract: A small plasma gun with parallel-plate configuration is fabricated to generate a bunch of plasma which is similar to ELM (edge localized mode) plasma, by taking advantages of its simplicity and cost-effectiveness. Prior to explore how to control the ELM-like plasma so as to relieve heat load on the divertor target, characteristics of a plasma jet ejected from the plasma gun are investigated using a quadruple Langmuir probe which is appropriate for measuring rapidly varying plasma parameters such as electron density, temperature, and ion velocity at the same time. The plasma density and ion velocity measured at 112 mm away from the exit are 3 × 10 19 m −3 and 11 km/s, respectively, which seem to be suitable for investigating next step research on the control of ELM-like plasma using various methods such as electromagnetic waves and high-voltage pulses. Also, the quadruple Langmuir probe is proven to be adequate for use in such experiments

  15. High quality ceramic coatings sprayed by high efficiency hypersonic plasma spraying gun

    International Nuclear Information System (INIS)

    Zhu Sheng; Xu Binshi; Yao JiuKun

    2005-01-01

    This paper introduced the structure of the high efficiency hypersonic plasma spraying gun and the effects of hypersonic plasma jet on the sprayed particles. The optimised spraying process parameters for several ceramic powders such as Al 2 O 3 , Cr 2 O 3 , ZrO 2 , Cr 3 C 2 and Co-WC were listed. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al 2 O 3 -TiO 2 ceramic coating sprayed by using the high efficiency hypersonic plasma spraying was also studied. Compared with the conventional air plasma spraying, high efficiency hypersonic plasma spraying improves greatly the ceramic coatings quality but at low cost. (orig.)

  16. Coaxial plasma gun in the high density regime and injection into a helical field

    Energy Technology Data Exchange (ETDEWEB)

    Schaer, S.F. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1994-02-01

    A modified coaxial gun in the high density regime of 20-70 mT of He restgas, energized by a 1200 HV sinusoidally damped capacitor discharge with peak currents of 86 kA in a potential range of 10-15 kV, was investigated. The acceleration of the current sheet inside the gun was studied, and an MHD current element model derived, in good agreement with experiment, indicating that thermal diffusion can be neglected during the acceleration phase and furthermore explains the sheet velocity limitation. At the muzzle the plasma is magnetized by inducing a toroidal current through a permanent radial field, generating poloidal field. The injection of the generated current-carrying plasma torus into the driftspace was studied by means of a diamagnetic probe array, for 1) toroidal bias field, and 2) helical bias field. The inner electrode (negative polarity) is continued into the driftspace by a considerably thinner, pyrex insulated central conductor, generating the toroidal bias. Quasi-Tokamak geometry is reached in the helical case. The necessary axial bias field strength was then calculated. Second half-period breakdown was observed, thus a positive electrode was present most of the time. This is a unique way to achieve autopreionisation. Plasma gun operation is very much breakdown dependent, specially in the region of the muzzle. This made it necessary to construct a special compensation coil for the axial field coil. The mean torus speed in the driftspace was 2.2 cm/{mu}sec. The tori were azimuthally homogeneous and exhibited enhanced stability. Transverse expansion at ejection and in the driftspace is prevented by a unique rarefaction wave-pattern resulting from the Mach 50 flow. The toroidal current was observed to decay continuously, not abruptly. No n type or oscillatory instabilities were encountered. These findings are important for future designs of guns where a stable and homogenous torus is needed, such as magnetic confinement injectors. (author) 39 figs., 38 refs.

  17. Coaxial plasma gun in the high density regime and injection into a helical field

    International Nuclear Information System (INIS)

    Schaer, S.F.

    1994-02-01

    A modified coaxial gun in the high density regime of 20-70 mT of He restgas, energized by a 1200 HV sinusoidally damped capacitor discharge with peak currents of 86 kA in the potential range of 10-15 kV, was investigated. The acceleration of the current sheet inside the gun was studied, and an MHD current element model derived, in good agreement with experiment, indicating that thermal diffusion can be neglected during the acceleration phase and furthermore explains the sheet velocity limitation. At the muzzle the plasma is magnetized by inducing a toroidal current through a permanent radial field, generating poloidal field. The injection of the generated current-carrying plasma torus into the driftspace was studied by means of a diamagnetic probe array, for 1) toroidal bias field, and 2) helical bias field. The inner electrode (negative polarity) is continued into the driftspace by a considerably thinner, pyrex insulated central conductor, generating the toroidal bias. Quasi-Tokamak geometry is reached in the helical case. The necessary axial bias field strength was then calculated. Second half-period breakdown was observed, thus a positive electrode was present most of the time. This is a unique way to achieve autopreionisation. Plasma gun operation is very much breakdown dependent, specially in the region of the muzzle. This made it necessary to construct a special compensation coil for the axial field coil. The mean torus speed in the driftspace was 2.2 cm/μsec. The tori were azimuthally homogeneous and exhibited enhanced stability. Transverse expansion at ejection and in the driftspace is prevented by a unique rarefaction wave-pattern resulting from the Mach 50 flow. The toroidal current was observed to decay continuously, not abruptly. No n type or oscillatory instabilities were encountered. These findings are important for future designs of guns where a stable and homogenous torus is needed, such as magnetic confinement injectors. (author) 39 figs., 38 refs

  18. Electron emission and plasma generation in a modulator electron gun using ferroelectric cathode

    International Nuclear Information System (INIS)

    Chen Shutao; Zheng Shuxin; Zhu Ziqiu; Dong Xianlin; Tang Chuanxiang

    2006-01-01

    Strong electron emission and dense plasma generation have been observed in a modulator electron gun with a Ba 0.67 Sr 0.33 TiO 3 ferroelectric cathode. Parameter of the modulator electron gun and lifetime of the ferroelectric cathode were investigated. It was shown that electron emission from Ba 0.67 Sr 0.33 TiO 3 cathode with a positive triggering pulse is a sort of plasma emission. Electrons were emitted by the co-effect of surface plasma and non-compensated negative polarization charges at the surface of the ferroelectric. The element analyses of the graphite collector after emission process was performed to show the ingredient of the plasma consist of Ba, Ti and Cu heavy cations of the ceramic compound and electrode. It was demonstrated the validity of the Child-Langmuir law by introducing the decrease of vacuum gap and increase of emission area caused by the expansion of the surface plasma

  19. Investigation of MHD Instabilities in Jets and Bubbles Using a Compact Coaxial Plasma Gun in a Background Magnetized Plasma

    Science.gov (United States)

    Zhang, Y.; Fisher, D. M.; Wallace, B.; Gilmore, M.; Hsu, S. C.

    2016-10-01

    A compact coaxial plasma gun is employed for experimental investigation of launching plasma into a lower density background magnetized plasma. Experiments are being conducted in the linear device HelCat at UNM. Four distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. For regime I plasma jet formation, a global helical magnetic configuration is determined by a B-dot probe array data. Also the m =1 kink instability is observed and verified. Furthermore, when the jet is propagating into background magnetic field, a longer length and lifetime jet is formed. Axial shear flow caused by the background magnetic tension force contributes to the increased stability of the jet body. In regime II, a spheromak-like plasma bubble formation is identified when the gun plasma is injected into vacuum. In contrast, when the bubble propagates into a background magnetic field, the closed magnetic field configuration does not hold anymore and a lateral side, Reilgh-Taylor instability develops. Detailed experimental data and analysis will be presented for these cases.

  20. Very low pressure plasma sprayed yttria-stabilized zirconia coating using a low-energy plasma gun

    International Nuclear Information System (INIS)

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

    2011-01-01

    In the present study, a more economical low-energy plasma source was used to perform a very low pressure plasma-spray (VLPPS) process. The plasma-jet properties were analyzed by means of optical emission spectroscopy (OES). Moreover, yttria-stabilized zirconia coating (YSZ) was elaborated by a F100 low-power plasma gun under working pressure of 1 mbar, and the substrate specimens were partially shadowed by a baffle-plate during plasma spraying for obtaining different coating microstructures. Based on the SEM observation, a column-like grain coating was deposited by pure vapor deposition at the shadowed region, whereas, in the unshadowed region, the coating exhibited a binary microstructure which was formed by a mixed deposition of melted particles and evaporated particles. The mechanical properties of the coating were also well under investigation. (orig.)

  1. A coaxial plasma gun with a controllable streaming velocity in the range of 2-90 km secsup(-1)

    International Nuclear Information System (INIS)

    Venkataramani, N.; Mattoo, S.K.

    1981-01-01

    A coaxial plasma gun capable of producing a plasma stream of velocity ranging between 2 and 90 km secsup(-1) is described. The velocity of the stream is controlled by a variable (0.2-25 Ω) NaCl salt solution resistor in the discharge path of the energy storage connected across the gun. The resistor dissipates an energy of 200 J in the gun discharge current pulse period of 25 μ sec and the consequent heating and dissociation of the electrolyte are insignificant. The electron density of the plasma stream ranges between 10 18 and 10 19 msup(-3) and the temperature is approximately 10 eV. The total number of ions per plasma pulse is approximately 10 18 . The energy transfer efficiency of the gun is approximately 10%. The low transfer efficiency is explained in terms of the experimental requirements and the performance of the valve which admits gas into the gun region. For evaluation of the performance of the gun, several diagnostics have been deployed. A specially designed high voltage capacitor probe is described. (author)

  2. Generation of Low-Energy High-Current Electron Beams in Plasma-Anode Electron Guns

    Science.gov (United States)

    Ozur, G. E.; Proskurovsky, D. I.

    2018-01-01

    This paper is a review of studies on the generation of low-energy high-current electron beams in electron guns with a plasma anode and an explosive-emission cathode. The problems related to the initiation of explosive electron emission under plasma and the formation and transport of high-current electron beams in plasma-filled systems are discussed consecutively. Considerable attention is given to the nonstationary effects that occur in the space charge layers of plasma. Emphasis is also placed on the problem of providing a uniform energy density distribution over the beam cross section, which is of critical importance in using electron beams of this type for surface treatment of materials. Examples of facilities based on low-energy high-current electron beam sources are presented and their applications in materials science and practice are discussed.

  3. Characterization and optimization of the HyperV PLX- α coaxial-gun plasma jet

    Science.gov (United States)

    Case, Andrew; Brockington, Sam; Cruz, Edward; Witherspoon, F. Douglas

    2017-10-01

    We present results from characterizing and optimizing performance of the contoured gap coaxial plasma guns under development for the ARPA-E Accelerating Low-Cost Plasma Heating And Assembly (ALPHA) program. Plasma jet diagnostics include fast photodiodes for velocimetry and interferometry for line integrated density. Additionally we present results from spectroscopy, both time resolved high resolution spectroscopy using a novel detector and time integrated survey spectroscopy, for measurements of velocity and temperature as well as impurities. Fast imaging gives plume geometry and time integrated imaging gives overall light emission. Results from a novel long record length camera developed by HyperV will also be presented. Experimental results are compared to the desired target parameters for the plasma jets. The target values for the plasmoid are velocity of 50 km/s, mass of 3.5 mg, and length of 10 cm. The best results so far from the exploration of parameter space for gun operation are: 4 mg at >50 km/s, with a length of 10 cm. Peak axial density 34 cm downstream from the muzzle is 2 ×1016 cm-3. This work supported by the ARPA-E ALPHA Program under contract DE-AR0000566.

  4. Development of intense pulsed heavy ion beam diode using gas puff plasma gun as ion source

    International Nuclear Information System (INIS)

    Ito, H.; Higashiyama, M.; Takata, S.; Kitamura, I.; Masugata, K.

    2006-01-01

    A magnetically insulated ion diode with an active ion source of a gas puff plasma gun has been developed in order to generate a high-intensity pulsed heavy ion beam for the implantation process of semiconductors and the surface modification of materials. The nitrogen plasma produced by the plasma gun is injected into the acceleration gap of the diode with the external magnetic field system. The ion diode is operated at diode voltage approx. =200 kV, diode current approx. =2 kA and pulse duration approx. =150 ns. A new acceleration gap configuration for focusing ion beam has been designed in order to enhance the ion current density. The experimental results show that the ion current density is enhanced by a factor of 2 and the ion beam has the ion current density of 27 A/cm 2 . In addition, the coaxial type Marx generator with voltage 200 kV and current 15 kA has been developed and installed in the focus type ion diode. The ion beam of ion current density approx. =54 A/cm 2 is obtained. To produce metallic ion beams, an ion source by aluminum wire discharge has been developed and the aluminum plasma of ion current density ∼70 A/cm 2 is measured. (author)

  5. Overview and Recent Results from the HyperV Plasma Gun

    Science.gov (United States)

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

    2007-11-01

    We present an overview of research at HyperV to develop high velocity dense plasma jets for application to fusion and HEDP. The approach uses symmetrical pulsed injection of high density plasma into a coaxial EM accelerator having a cross-section tailored to prevent formation of the blow-by instability. Two development paths are followed to accomplish this injection step: we compare large arrays of capillary discharges to sparkgaps arranged in a toroidal configuration. Experiments on three test fixtures are described: a 2pi configuration with 64 capillary injectors, a 32 injector prototype gun designed to drive rotation in the Maryland MCX experiment, and a second gun using 112 sparkgap electrodes for injection. Data is presented from visible light spectroscopy, fast optical imaging, Rogowski coils, pressure probes, Bdot probes, photodiodes, and a laser interferometer. Ballistic pendulum tests indicate plasma jets with mass 160 micrograms at 70 km/s have been achieved with plasma density above 10^15 cm-3.

  6. Plasma guns for controlled fussion at megagauss energy-densities

    International Nuclear Information System (INIS)

    Turchi, Peter J.; Roderick, Norman F.; Degnan, James H.; Frese, Michael H.

    2008-01-01

    Electron cyclotron current drive (ECCD) at a low power level has been used on Tore Supra to induce local perturbations of the current density profile. Regimes with strong MHD activity have been analysed, and compared with similar stable discharges, in order to investigate the possible causes of their instability and relate the evolution of the discharge to the localization of EC power deposition. Both co- and counter-current drive pulses have been applied to dominantly or fully non-inductive discharges, sustained by a lower hybrid current drive. Detailed reconstructions by current diffusion calculations have been performed and the error bars evaluated. This method has proved valuable for shedding light on the complex interplay between the evolutions of temperature and safety factor profiles in steady-state tokamak plasmas. The crucial role of the dynamic evolution of rational surfaces has been identified. Moreover, we demonstrate that the operational domain in which ECCD can be employed must cope with the overall current profile characteristics, in particular the position where the safety factor has a minimum.

  7. Diagnostics and results from coaxial plasma gun development for the PLX- α project

    Science.gov (United States)

    Case, A.; Brockington, S.; Cruz, E.; Witherspoon, F. D.

    2016-10-01

    We present results from the diagnostics used during development of the contoured gap coaxial plasma guns for the PLX- α project at LANL. Plasma-jet diagnostics include fast photodiodes for velocimetry, a ballistic pendulum for total plasmoid momentum, and interferometry for line integrated density. Deflectometry will be used for line integrated perpendicular density gradients. Time-resolved high-resolution spectroscopy using a novel detector and time-integrated survey spectroscopy are used for measurements of velocity and temperature, as well as impurities. We will also use a Faraday cup for density, fast imaging for plume geometry, and time-integrated imaging for overall light emission. Experimental results are compared to the desired target parameters for the plasma jets (up to n 2 ×1016cm-3 , v 50km / s , mass 5gm , radius = 4cm , and length 10cm). This work supported by the ARPA-E ALPHA Program.

  8. Critical ionisation velocity and the dynamics of a coaxial plasma gun

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1978-01-01

    The dynamics of an ionising wave in a coaxial plasma gun with an azimuthal bias magnetic field is analysed in a theoretical model. Only the radial dependence is treated and instead of including a treatment of the energy balance two separate physical assumptions are made. In the first case it is assumed that the total internal electric field is given by the critical ionisation velocity condition and in the second that the ionisation rate is constant. For consistency wall sheaths are assumed to match the internal plasma potential to that of the walls. On the basis of momentum and particle balance the radial dependence of the electron density, current density, electric field and drift velocity are found. An electron source is required at the cathode and the relative contribution from ionisation within the plasma is deduced. The assumption that there are no ion sources at the electrodes leads to a restriction on the possible values of the axial electric field. (author)

  9. Diagnostic Suite for HyperV Coaxial Plasma Gun Development for the PLX- α Project

    Science.gov (United States)

    Case, Andrew; Brockington, Sam; Witherspoon, F. Douglas

    2015-11-01

    We present the diagnostic suite to be used during development of the coaxial guns HyperV will deliver to LANL in support of the ARPA-E Accelerating Low-Cost Plasma Heating And Assembly (ALPHA) program. For plasma jet diagnostics this includes fast photodiodes for velocimetry, a ballistic pendulum for measuring total plasmoid momentum, interferometry for line integrated plasma density, deflectometry for line integrated perpendicular density gradient measurements, and spectroscopy, both time resolved high resolution spectroscopy using a novel detector developed by HyperV and time integrated survey spectroscopy, for measurements of velocity and temperature as well as impurities. In addition, we plan to use fast pressure probes for stagnation pressure, a Faraday cup for density, fast imaging for plume geometry and time integrated imaging for overall light emission. A novel low resolution long record length camera developed by HyperV will also be used for plume diagnostics. For diagnostics of gun operation, we will use Rogowski coils to measure current, voltage dividers for voltages, B-dot probes for magnetic field, and time resolved fast photodiodes to measure plasmoid velocity inside the accelerator. This work supported by the ARPA-E ALPHA program.

  10. In vitro fatigue behaviour of vacuum plasma and detonation gun sprayed hydroxyapatite coatings.

    Science.gov (United States)

    Gledhill, H C; Turner, I G; Doyle, C

    2001-06-01

    The fatigue behaviour of vacuum plasma sprayed (VPS) and detonation gun sprayed (DGUN) hydroxyapatite coatings on titanium substrates has been compared in air and in buffered Ringer's solution. There was an increase in the surface microcracking and bulk porosity of both types of coating tested in air. After 1 million cycles in Ringer's solution the VPS coatings had completely delaminated from their substrates. In contrast the DGUN coatings retained their integrity when tested up to 10 million cycles but were beginning to show signs of delamination at the interface.

  11. Magnetohydrodynamic simulation of kink instability and plasma flow during sustainment of a coaxial gun spheromak

    International Nuclear Information System (INIS)

    Kanki, Takashi; Nagata, Masayoshi; Kagei, Yasuhiro

    2010-01-01

    Kink instability and the subsequent plasma flow during the sustainment of a coaxial gun spheromak are investigated by three-dimensional nonlinear magnetohydrodynamic simulations. Analysis of the parallel current density λ profile in the central open column revealed that the n = 1 mode structure plays an important role in the relaxation and current drive. The toroidal flow (v t ≈ 37 km/s) is driven by magnetic reconnection occurring as a result of the helical kink distortion of the central open column during repetitive plasmoid ejection and merging. (author)

  12. Experimental and theoretical study of plasma-water interaction in electrothermal guns

    International Nuclear Information System (INIS)

    Arensburg, Alex.

    1993-05-01

    This thesis comprises an experimental and theoretical study of the plasma- jet-water interaction in electrothermal guns. In the present work the plasma jet was produced by high current pulsed discharge in a plasma injector consisting of polyethylene capillary, closed at one end by a metallic anode and supported at the other end with a hollow cathode. A thin aluminium fuse placed inside the capillary and connecting both electrodes, provided an initial conducting element. A pulse forming network delivering a high current pulse through the fuse, exploded it and produced an aluminium plasma. Subsequently, ablation of the capillary wall begun as a result of its exposure to radiation from the fuse plasma. The ablation products were heated by the pulse current until ionized, replacing the fuse plasma by a polyethylene plasma thus sustaining the ablation process. The experimental investigation reported here used x-ray shadowgraphy to observe the plasma-working fluid interaction process. The working fluid was an aqueous solution of 92% water and 8% lead acetate gelatinized with agar. The penetration of the plasma jet into the working fluid was exposed on films at successive time intervals by means of x-ray shadowgraphy. When the water interacts with the plasma it also ablated. This ablation rate was estimated from energy conservation considerations. Peak pressures up to 3.5*10 8 Pa were measured during the process. At such pressure water does not undergo phase transformation when heated. Thus the mass density at the plasma water interface should be regarded as a continuous function of temperature. The determination of the temperature profile at the interface between the capillary plasma and the water requires the solution of the heat transfer and radiative transfer equations under ablation conditions. This constituted the main theoretical part of the present work. 36 refs., 4 tabs., 29 figs

  13. Experimental investigation of coaxial-gun-formed plasmas injected into a background transverse magnetic field or plasma

    Science.gov (United States)

    Zhang, Yue; Fisher, Dustin M.; Gilmore, Mark; Hsu, Scott C.; Lynn, Alan G.

    2018-05-01

    Injection of coaxial-gun-formed magnetized plasmas into a background transverse vacuum magnetic field or into a background magnetized plasma has been studied in the helicon-cathode (HelCat) linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys. 81, 345810104 (2015)]. A magnetized plasma jet launched into a background transverse magnetic field shows emergent kink stabilization of the jet due to the formation of a sheared flow in the jet above the kink stabilization threshold 0.1kVA [Y. Zhang et al., Phys. Plasmas 24, 110702 (2017)]. Injection of a spheromak-like plasma into a transverse background magnetic field led to the observation of finger-like structures on the side with a stronger magnetic field null between the spheromak and the background field. The finger-like structures are consistent with magneto-Rayleigh-Taylor instability. Jets or spheromaks launched into a background, low-β magnetized plasma show similar behavior as above, respectively, in both cases.

  14. Neutron localization measurements from a two-gun plasma focus device

    International Nuclear Information System (INIS)

    Yeh, T.R.; Wen, M.; Tzeng, C.C.; Shang, D.J.; Yeh, C.K.; Wu, K.S.; Kuo, Y.Y.; Hou, W.S.

    1989-01-01

    The simultaneous formation of the two deuterium plasma foci has been reported recently by Hou, W.S., et al, in Procs I.E.E.E. Int. Conf. on Plasma Science, 1986, 87, in a Mather type two-gun plasma focus assembly with maximum bank energy of ∼700 kJ. In addition, these plasmas will evolve and then produce a disk-shaped plasma in the middle of the two plasma foci. Soft X-ray filter techniques which allow measurements of the electron temperature at both pinch points and the middle point yielded a few hundred eV for these three regions. Neutron localization measurements which were carried out with a collimator and a scintillator-fiber-photomultiplier assembly indicate that an enhancement of ∼80% in neutron yield is observed in the middle region as the separation between two electrodes is 9.1 cm. Further experimental evidence shows that the neutron production in the middle region is the result of the beam-beam interaction in nature. (author)

  15. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode.

    Science.gov (United States)

    Poehlmann, Flavio R; Cappelli, Mark A; Rieker, Gregory B

    2010-12-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 μF, 50 to 200 nH, and 1 to 3 kV, respectively.

  16. Experimental investigation of a 1 kA/cm² sheet beam plasma cathode electron gun.

    Science.gov (United States)

    Kumar, Niraj; Pal, Udit Narayan; Pal, Dharmendra Kumar; Prajesh, Rahul; Prakash, Ram

    2015-01-01

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm(2) from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field.

  17. Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch

    Energy Technology Data Exchange (ETDEWEB)

    Weber, T. E., E-mail: tweber@lanl.gov; Intrator, T. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Smith, R. J. [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States)

    2015-04-15

    Injection of plasma via an annular array of coaxial plasma guns during the pre-ionization phase of field-reversed configuration (FRC) formation is shown to catalyze the bulk ionization of a neutral gas prefill in the presence of a strong axial magnetic field and change the character of outward flux flow during field-reversal from a convective process to a much slower resistive diffusion process. This approach has been found to significantly improve FRC formation in a conical θ-pinch, resulting in a ∼350% increase in trapped flux at typical operating conditions, an expansion of accessible formation parameter space to lower densities and higher temperatures, and a reduction or elimination of several deleterious effects associated with the pre-ionization phase.

  18. Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch

    Science.gov (United States)

    Weber, T. E.; Intrator, T. P.; Smith, R. J.

    2015-04-01

    Injection of plasma via an annular array of coaxial plasma guns during the pre-ionization phase of field-reversed configuration (FRC) formation is shown to catalyze the bulk ionization of a neutral gas prefill in the presence of a strong axial magnetic field and change the character of outward flux flow during field-reversal from a convective process to a much slower resistive diffusion process. This approach has been found to significantly improve FRC formation in a conical θ-pinch, resulting in a ˜350% increase in trapped flux at typical operating conditions, an expansion of accessible formation parameter space to lower densities and higher temperatures, and a reduction or elimination of several deleterious effects associated with the pre-ionization phase.

  19. Laboratory Simulations of CME-Solar Wind Interactions Using a Coaxial Gun and Background Plasma

    Science.gov (United States)

    Wallace, B. H.; Zhang, Y.; Fisher, D.; Gilmore, M.

    2016-12-01

    Understanding and predicting solar coronal mass ejections (CMEs) is of critical importance for mitigating their disruptive behavior on ground- and space-based technologies. While predictive models of CME propagation and evolution have relied primarily on sparse in-situ data along with ground and satellite images for validation purposes, emerging laboratory efforts have shown that CME-like events can be created with parameters applicable to the solar regime that may likewise aid in predictive modeling. A modified version of the coaxial plasma gun from the Plasma Bubble Expansion Experiment (PBEX) [A. G. Lynn, Y. Zhang, S. C. Hsu, H. Li, W. Liu, M. Gilmore, and C. Watts, Bull. Amer. Phys. Soc. 52, 53 (2007)] will be used in conjunction with the Helicon-Cathode (HelCat) basic plasma science device in order to observe the magnetic characteristics of CMEs as they propagate through the solar wind. The evolution of these interactions will be analyzed using a multi-tip Langmuir probe array, a 33-position B-dot probe array, and a high speed camera. The results of this investigation will be used alongside the University of Michigan's BATS-R-US 3-D MHD numerical code, which will be used to perform simulations of the coaxial plasma gun experiment. The results of these two approaches will be compared in order to validate the capabilities of the BATS-R-US code as well as to further our understanding of magnetic reconnection and other processes that take place as CMEs propagate through the solar wind. The details of the experimental setup as well as the analytical approach are discussed.

  20. Characteristics of a wire ion plasma source and a secondary emission electron gun

    International Nuclear Information System (INIS)

    Hotta, Eiki; Osawa, Teruya; Urai, Hajime; Suzuki, Mitsuaki; Yasui, Hiroyuki; Tamagawa, Tohru

    1993-01-01

    Electrical characteristics of a wire ion plasma source (WIPS) and a secondary emission electron gun, for which the WIPS is used as an ion source, will be reported. The WIPS is a cold-cathode gaseous discharge device, in which a radial electron trapping permits an extremely low pressure gaseous discharge with very low applied voltages. The time evolutions of temperature and density of afterglow plasma were measured with a double probe. In the case of P 0 = 25 mTorr He and the maximum discharge current of 200 A, the temperature and density of electron were about 20 eV and of the order of 10 18 m -3 , respectively, just after the distinction of discharge. The ion current density measured by a biased ion collector (BIC) on the discharge tube wall was found to reach up to 300 mA/cm 2 . A secondary emission electron gun was set on the discharge tube wall opposite to the BIC. An earthed mesh net is installed at a height of 8 mm just in front of the cathode. The maximum negative bias voltage applied to the cathode is limited to -50 kV by the local breakdown in the gun, which occurred synchronously with the WIPS discharge. The electron beam current was measured by the BIC, in which an aluminum foil with a width of 2 μm was placed on instead of the earthed mesh net. At the cathode voltage of -30 kV, the measured beam current density was 220 mA/cm 2 . The extraporation of the resulted curve indicates that if the cathode voltage is -100 kV, the current density will reach to 1 A/cm 2 . The energy spectrum of the electron beam was measured with a magnetic energy analyzer, which was set in place of the BIC. The energy spread is about 300 eV at the central energy of 40 keV. Thus, they demonstrated the possibility of a high current density secondary emission electron gun, for which a WIPS is used as an ion source

  1. Understanding the Effect of Gas Dynamics in Plasma Gun Performance for Simulating Fusion Wall Response to Disruption Events

    Science.gov (United States)

    Riedel, Will; Underwood, Thomas; Righetti, Fabio; Cappelli, Mark

    2017-10-01

    In this work, the suitability of a pulsed coaxial plasma accelerator to simulate the interaction of edge-localized modes with plasma first wall materials is investigated. Experimental measurements derived from a suite of diagnostics are presented that focus on both the properties of the plasma flow and the manner in which such jets couple with material interfaces. Specific emphasis is placed on quantifying the variation in these properties using tungsten tokens exposed to the plasma plume as the gun volume is progressively filled with more neutral gas. These results are mapped to the operational dynamics of the gun via a time-resolved Schlieren cinematic visualization of the density gradient within the flow. Resulting videos indicate the existence of two distinct modes with vastly different characteristic timescales, spatial evolution, and plasma properties. Time resolved quantification of the associated plasma heat flux for both modes, including a range spanning 150 MW m-2 - 10 GW m-2, is presented using both a fast thermocouple gauge and an IR camera. Both diagnostics in conjunction with a heat transfer model provide an accurate description of the energy transfer dynamics and operational characteristics of plasma guns. This work is supported by the U.S. Department of Energy Stewardship Science Academic Program.

  2. Magnetic Ignition of Pulsed Gas Discharges in Air of Low Pressure in a Coaxial Plasma Gun

    Science.gov (United States)

    Thom, Karlheinz; Norwood, Joseph, Jr.

    1961-01-01

    The effect of an axial magnetic field on the breakdown voltage of a coaxial system of electrodes has been investigated by earlier workers. For low values of gas pressure times electrode spacing, the breakdown voltage is decreased by the application of the magnetic field. The electron cyclotron radius now assumes the role held by the mean free path in nonmagnetic discharges and the breakdown voltage becomes a function of the magnetic flux density. In this paper the dependence of the formative time lag as a function of the magnetic flux density is established and the feasibility of using a magnetic field for igniting high-voltage, high-current discharges is shown through theory and experiment. With a 36 microfarad capacitor bank charged to 48,000 volts, a peak current of 1.3 x 10( exp 6) amperes in a coaxial type of plasma gun was achieved with a current rise time of only 2 microseconds.

  3. ECR ion source with electron gun

    Science.gov (United States)

    Xie, Zu Q.; Lyneis, Claude M.

    1993-01-01

    An Advanced Electron Cyclotron Resonance ion source (10) having an electron gun (52) for introducing electrons into the plasma chamber (18) of the ion source (10). The ion source (10) has a injection enclosure (12) and a plasma chamber tank (14). The plasma chamber (18) is defined by a plurality of longitudinal magnets (16). The electron gun (52) injects electrons axially into the plasma chamber (18) such that ionization within the plasma chamber (18) occurs in the presence of the additional electrons produced by the electron gun (52). The electron gun (52) has a cathode (116) for emitting electrons therefrom which is heated by current supplied from an AC power supply (96) while bias potential is provided by a bias power supply (118). A concentric inner conductor (60) and Outer conductor (62) carry heating current to a carbon chuck (104) and carbon pusher (114) Which hold the cathode (116) in place and also heat the cathode (16). In the Advanced Electron Cyclotron Resonance ion source (10), the electron gun (52) replaces the conventional first stage used in prior art electron cyclotron resonance ion generators.

  4. Optimization of the Magnetic Field Structure for Sustained Plasma Gun Helicity Injection for Magnetic Turbulence Studies at the Bryn Mawr Plasma Laboratory

    Science.gov (United States)

    Cartagena-Sanchez, C. A.; Schaffner, D. A.; Johnson, H. K.; Fahim, L. E.

    2017-10-01

    A long-pulsed magnetic coaxial plasma gun is being implemented and characterized at the Bryn Mawr Plasma Laboratory (BMPL). A cold cathode discharged between the cylindrical electrodes generates and launches plasma into a 24cm diameter, 2m long chamber. Three separately pulsed magnetic coils are carefully positioned to generate radial magnetic field between the electrodes at the gun edge in order to provide stuffing field. Magnetic helicity is continuously injected into the flux-conserving vacuum chamber in a process akin to sustained slow-formation of spheromaks. The aim of this source, however, is to supply long pulses of turbulent magnetized plasma for measurement rather than for sustained spheromak production. The work shown here details the optimization of the magnetic field structure for this sustained helicity injection.

  5. Synthesis and characterization of carbon fibers obtained through plasma techniques

    International Nuclear Information System (INIS)

    Valdivia B, M.

    2005-01-01

    The study of carbon, particularly the nano technology is a recent field, the one which has important implications in the science of new materials. It investigation is of great interest for industries producers of ceramic, metallurgy, electronic, energy storage, biomedicine, among others. The diverse application fields are a reason at national as international level, so that many works are focused in the production of nano fibers of carbon. The Thermal plasma applications laboratory (LAPT) of the National Institute of Nuclear Research (ININ), it is carrying out works about carbon nano technology. The present work has as purpose to carry out the synthesis and characterization of the carbon nano fibers which are obtained by electric arch of alternating current (CA) to high frequencies and by a plasma gun of non transferred arch, where are used hydrocarbons like benzene, methane, acetylene like carbon source and ferrocene, nickel, yttrium and cerium oxide like catalysts. For both techniques its were thought about a relationship among hydrocarbon-catalyst that it favored to the nano fibers production. The obtained product of each experiment outlined it was analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD), analysis with those were obtained pictures and diffraction graphs, which were observed to arrive to one conclusion on the operation conditions, same analysis with those were characterized the tests carried out according to the nano structures formation of carbon. (Author)

  6. Robe Development for Electrical Conductivity Analysis in an Electron Gun Produced Helium Plasma

    Science.gov (United States)

    Bragg-Sitton, Shannon M.; Bitteker, Leo; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    The use of magnetohydrodynamic (MHD) power conversion systems, potentially coupled with a fission power source, is currently being investigated as a driver for an advanced propulsion system, such as a plasma thruster. The efficiency of a MHD generator is strongly dependent on the electrical conductivity of the fluid that passes through the generator; power density increases as fluid conductivity increases. Although traditional MHD flows depend on thermal ionization to enhance the electrical conductivity, ionization due to nuclear interactions may achieve a comparable or improved conductivity enhancement while avoiding many of the limitations inherent to thermal ionization. Calculations suggest that nuclear-enhanced electrical conductivity increases as the neutron flux increases; conductivity of pure He-3 greater than 10 mho/m may be achievable if exposed to a flux greater than 10(exp 12) neutrons/cm2/s.) However, this remains to be demonstrated experimentally. An experimental facility has been constructed at the Propulsion Research Center at the NASA Marshall Space Flight Center, using helium as the test fluid. High energy electrons will be used to simulate the effects of neutron-induced ionization of helium gas to produce a plasma. These experiments will be focused on diagnosis of the plasma in a virtually static system; results will be applied to future tests with a MHD system. Initial experiments will utilize a 50 keV electron gun that can operate at up to a current of 200 micro A. Spreading the electron beam over a four inch diameter window results in an electron flux of 1.5x 10(exp 13) e/sq cm/s. The equivalent neutron flux that would produce the same ionization fraction in helium is 1x10(exp 12) n/sq cm/s. Experiments will simulate the neutron generated plasma modeled by Bitteker, which takes into account the products of thermal neutron absorption in He-3, and includes various ion species in estimating the conductivity of the resulting plasma. Several

  7. Magnetized gun experiments

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Henins, I.; Hoida, H.W.; Marshall, J.; Sherwood, A.R.

    1981-01-01

    In the Los Alamos Magnetized Gun Experiment we are attempting to produce a compact torus in a manner similar to an earlier experiment of Alfven. In our experiment a solenoidal coil is placed inside the inner electrode of a coaxial plasma gun. This coil produces an axial magnetic field inside the inner electrode which diverges and becomes a largely radial field in front of the gun muzzle. The idea is that when the gun is fired, the plasma escaping from the gun stretches these radial fields along the axial direction away from the gun, and these field lines can reconnect behind the plasma forming the poloidal field of the compact torus. The magnetic field generated by the gun current becomes the toroidal field and the major axis of the compact torus will be the same as the axis of the coaxial gun. Recent interest in this possible method of compact torus generation was stimulated by C. Hartman, and the approach is also being pursued in the field-reversed plasma gun experiment at LLL

  8. A comparative study of tribological behavior of plasma and D-gun sprayed coatings under different wear modes

    International Nuclear Information System (INIS)

    Sundararajan, G.; Rao, D.S.; Prasad, K.U.M.; Joshi, S.V.

    1998-01-01

    In recent years, thermal sprayed protective coatings have gained widespread acceptance for a variety of industrial applications. A vast majority of these applications involve the use of thermal sprayed coatings to combat wear. While plasma spraying is the most versatile variant of all the thermal spray processes, the detonation gun (D-gun) coatings have been a novelty until recently because of their proprietary nature. The present study is aimed at comparing the tribological behavior of coatings deposited using the two above techniques by focusing on some popular coating materials that are widely adopted for wear resistant applications, namely, WC-12% Co, Al 2 O 3 , and Cr 3 C 2 -NiCr. To enable a comprehensive comparison of the above indicated thermal spray techniques as well as coating materials, the deposited coatings were extensively characterized employing microstructural evaluation, microhardness measurements, and XRD analysis for phase constitution. The behavior of these coatings under different wear modes was also evaluated by determining their tribological performance when subjected to solid particle erosion tests, rubber wheel sand abrasion tests, and pin-on-disk sliding wear tests. Among all the coating materials studied, D-gun sprayed WC-12% Co, in general, yields the best performance under different modes of wear, whereas plasma sprayed Al 2 O 3 shows least wear resistance to every wear mode

  9. Magnetic structure in the entrance region of spheromaks sustained by a magnetized coaxial plasma gun under long pulse operation

    International Nuclear Information System (INIS)

    Amemiya, Naoyuki; Takaichi, Kazuaki; Katsurai, Makoto

    1989-01-01

    The magnetic structure in coaxial-gun-sustained spheromaks has been investigated. The plasma gun has been operated with a small axial/radial bias magnetic flux as compared to the azimuthal magnetic flux produced by the discharge current. Stronger magnetic field is observed in the entrance region (ER) than in the flux conserver (FC). In both ER and FC, the magnetic structure is nearly axisymmetric. The axial magnetic field in ER is amplified up to about sixteen times as large as the bias magnetic field. This amplification is limited by the drastic change in the magnetic structure, which occurs when the discharge current becomes very large. The magnetic structure before the drastic change is interpreted with the Bessel function model. The μ estimation shows that the magnetic structure is mainly determined by the boundary geometry, not by the external magnetic flux and current. (author)

  10. DC-driven plasma gun: self-oscillatory operation mode of atmospheric-pressure helium plasma jet comprised of repetitive streamer breakdowns

    Science.gov (United States)

    Wang, Xingxing; Shashurin, Alexey

    2017-02-01

    This paper presents and studies helium atmospheric pressure plasma jet comprised of a series of repetitive streamer breakdowns, which is driven by pure DC high voltage (self-oscillatory behavior). The repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV cm-1. One type of the helium plasma gun designed using this operational principle is demonstrated. The gun operates on about 3 kV DC high voltage and is comprised of the series of the repetitive streamer breakdowns at a frequency of about 13 kHz.

  11. Carbon fiber manufacturing via plasma technology

    Science.gov (United States)

    Paulauskas, Felix L.; Yarborough, Kenneth D.; Meek, Thomas T.

    2002-01-01

    The disclosed invention introduces a novel method of manufacturing carbon and/or graphite fibers that avoids the high costs associated with conventional carbonization processes. The method of the present invention avoids these costs by utilizing plasma technology in connection with electromagnetic radiation to produce carbon and/or graphite fibers from fully or partially stabilized carbon fiber precursors. In general, the stabilized or partially stabilized carbon fiber precursors are placed under slight tension, in an oxygen-free atmosphere, and carbonized using a plasma and electromagnetic radiation having a power input which is increased as the fibers become more carbonized and progress towards a final carbon or graphite product. In an additional step, the final carbon or graphite product may be surface treated with an oxygen-plasma treatment to enhance adhesion to matrix materials.

  12. Measurements of line-averaged electron density of pulsed plasmas using a He-Ne laser interferometer in a magnetized coaxial plasma gun device

    Science.gov (United States)

    Iwamoto, D.; Sakuma, I.; Kitagawa, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    In next step of fusion devices such as ITER, lifetime of plasma-facing materials (PFMs) is strongly affected by transient heat and particle loads during type I edge localized modes (ELMs) and disruption. To clarify damage characteristics of the PFMs, transient heat and particle loads have been simulated by using a plasma gun device. We have performed simulation experiments by using a magnetized coaxial plasma gun (MCPG) device at University of Hyogo. The line-averaged electron density measured by a He-Ne interferometer is 2x10^21 m-3 in a drift tube. The plasma velocity measured by a time of flight technique and ion Doppler spectrometer was 70 km/s, corresponding to the ion energy of 100 eV for helium. Thus, the ion flux density is 1.4x10^26 m-2s-1. On the other hand, the MCPG is connected to a target chamber for material irradiation experiments. It is important to measure plasma parameters in front of target materials in the target chamber. In particular, a vapor cloud layer in front of the target material produced by the pulsed plasma irradiation has to be characterized in order to understand surface damage of PFMs under ELM-like plasma bombardment. In the conference, preliminary results of application of the He-Ne laser interferometer for the above experiment will be shown.

  13. Study of a plasma produced in a neutral gas chamber by the injection of a beam generated by a coaxial gun

    International Nuclear Information System (INIS)

    Castell, R.; Sanchez, A.; Mandelbaum, D.

    1982-01-01

    The design and operation of a plasma coaxial gun is described. The penetration and characteristics of the plasma emitted by the gun propagating in a expansion chamber with helium at 40 feBar is analyzed. The diagnostics is made with a double Langmuir probe observing the time variation of the electronic density along the propagation axis. Optical spectroscopy is used to measure one of the emission lines of the plasma radiation propaganting in the medium. The space-time description of the ion distribution function in a free-force field is made by the fit of an analytical model. (L.C.) [pt

  14. Gun Play

    Science.gov (United States)

    Mechling, Jay

    2008-01-01

    Biology and the particular gun culture of the United States come together to explain the persistent and powerful attraction of American boys to both real guns and toy guns. The 1990s saw adults begin to conflate "the gun problem" with "the boy problem," sparking attempts (largely failed) to banish toy guns from homes and…

  15. Development of a two-stage light gas gun to accelerate hydrogen pellets to high speeds for plasma fueling applications

    International Nuclear Information System (INIS)

    Combs, S.K.; Milora, S.L.; Foust, C.R.; Gouge, M.J.; Fehling, D.T.; Sparks, D.O.

    1988-01-01

    The development of a two-stage light gas gun to accelerate hydrogen isotope pellets to high speeds is under way at Oak Ridge National Laboratory. High velocities (>2 km/s) are desirable for plasma fueling applications, since the faster pellets can penetrate more deeply into large, hot plasmas and deposit atoms of fuel directly in a larger fraction of the plasma volume. In the initial configuration of the two-stage device, a 2.2-l volume (/ 3 for frozen hydrogen isotopes). However, the use of sabots to encase and protect the cryogenic pellets from the high peak pressures will probably be required to realize speeds of ∼3 km/s or greater. The experimental plan includes acceleration of hydrogen isotopes as soon as the gun geometry and operating parameters are optimized; theoretical models are being used to aid in this process. The hardware is being designed to accommodate repetitive operation, which is the objective of this research and is required for future applications. 25 refs., 6 figs., 1 tab

  16. Fast Plasma from a Coaxial Gun; Plasma Rapide Produit par un Canon Coaxial; Bystraya plazma iz koaksial'nogo inzhektora; Produccion de Plasma Rapido Mediante un Inyector Coaxial

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, J.; Henins, I. [Los Alamos Scientific Laboratory, Los Alamos, NM (United States)

    1966-04-15

    The coaxial gun in use here is a source or two different plasmas produced by separate mechanisms. Abundant slow ( Tilde-Operator 10{sup 7} cm/sec) deuterium plasma is produced directly by the j x B interaction of the radial plasma current and the magnetic field of the feed current along the centre electrode. The current disturbance moves through the injected gas toward the gun muzzle at Tilde-Operator 2.5 x 10{sup 7} cm/sec, storing energy behind it in magnetic field and plasma motion. The gun, with its stored energy, functions as a high power low impedance electrical generator to drive into the vacuum beyond the gun muzzle a jet of current which is the source of the fast plasma ( Tilde-Operator 5 x 10{sup 17} deuterons, Tilde-Operator 10{sup 8} cm/sec). The current jet and the plasma it produces are the subjects of these experiments. The mechanism of acceleration is complicated and imperfectly understood, but considerable insight has been gained by an extensive series of experiments, using as diagnostics the following: external diamagnetic pickup loops, intra vacuo Rogowsky loops, electric probes, external capacitive pickup electrodes, magnetic and electrostatic particle deflection analysis, spectroscopy, target light photography, time of flight with and without a guide field, d-d neutrons from the plasma volume and other methods. The picture which emerges is one of a complicated magneto-electric process taking place in front of the gun muzzle. The acceleration process depends on low gas density there as contrasted'with high density inside the gun. The fast plasma is largely derived from gas adsorbed on the electrodes. This makes necessary a clean vacuum so as to avoid contamination with highly ionized fast impurity ions (C{sup 5+}, 10{sup 8} cm/sec). Electrode material evaporates but appears not to be a serious contaminant because it comes late. The high voltage actually accelerating the ions is associated with the rapid expansion into vacuum of a magnetic flux

  17. 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.

  18. 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.

  19. Modeling electron beam parameters and plasma interface position in an anode plasma electron gun with hydrogen atmosphere

    Science.gov (United States)

    Krauze, A.; Virbulis, J.; Kravtsov, A.

    2018-05-01

    A beam glow discharge based electron gun can be applied as heater for silicon crystal growth systems in which silicon rods are pulled from melt. Impacts of high-energy charged particles cause wear and tear of the gun and generate an additional source of silicon contamination. A steady-state model for electron beam formation has been developed to model the electron gun and optimize its design. Description of the model and first simulation results are presented. It has been shown that the model can simulate dimensions of particle impact areas on the cathode and anode, but further improvements of the model are needed to correctly simulate electron trajectory distribution in the beam and the beam current dependence on the applied gas pressure.

  20. Development of a low-energy and high-current pulsed neutral beam injector with a washer-gun plasma source for high-beta plasma experiments.

    Science.gov (United States)

    Ii, Toru; Gi, Keii; Umezawa, Toshiyuki; Asai, Tomohiko; Inomoto, Michiaki; Ono, Yasushi

    2012-08-01

    We have developed a novel and economical neutral-beam injection system by employing a washer-gun plasma source. It provides a low-cost and maintenance-free ion beam, thus eliminating the need for the filaments and water-cooling systems employed conventionally. In our primary experiments, the washer gun produced a source plasma with an electron temperature of approximately 5 eV and an electron density of 5 × 10(17) m(-3), i.e., conditions suitable for ion-beam extraction. The dependence of the extracted beam current on the acceleration voltage is consistent with space-charge current limitation, because the observed current density is almost proportional to the 3/2 power of the acceleration voltage below approximately 8 kV. By optimizing plasma formation, we successfully achieved beam extraction of up to 40 A at 15 kV and a pulse length in excess of 0.25 ms. Its low-voltage and high-current pulsed-beam properties enable us to apply this high-power neutral beam injection into a high-beta compact torus plasma characterized by a low magnetic field.

  1. Vapor shielding effects on energy transfer from plasma-gun generated ELM-like transient loads to material surfaces

    Science.gov (United States)

    Kikuchi, Y.; Sakuma, I.; Asai, Y.; Onishi, K.; Isono, W.; Nakazono, T.; Nakane, M.; Fukumoto, N.; Nagata, M.

    2016-02-01

    Energy transfer processes from ELM-like pulsed helium (He) plasmas with a pulse duration of ˜0.1 ms to aluminum (Al) and tungsten (W) surfaces were experimentally investigated by the use of a magnetized coaxial plasma gun device. The surface absorbed energy density of the He pulsed plasma on the W surface measured with a calorimeter was ˜0.44 MJ m-2, whereas it was ˜0.15 MJ m-2 on the Al surface. A vapor layer in front of the Al surface exposed to the He pulsed plasma was clearly identified by Al neutral emission line (Al i) measured with a high time resolution spectrometer, and fast imaging with a high-speed visible camera filtered around the Al i emission line. On the other hand, no clear evaporation in front of the W surface exposed to the He pulsed plasma was observed in the present condition. Discussions on the reduction in the surface absorbed energy density on the Al surface are provided by considering the latent heat of vaporization and radiation cooling due to the Al vapor cloud.

  2. ION GUN

    Science.gov (United States)

    Dandl, R.A.

    1961-10-24

    An ion gun is described for the production of an electrically neutral ionized plasma. The ion gun comprises an anode and a cathode mounted in concentric relationship with a narrow annulus between. The facing surfaces of the rear portions of the anode and cathode are recessed to form an annular manifold. Positioned within this manifold is an annular intermediate electrode aligned with the an nulus between the anode and cathode. Gas is fed to the manifold and an arc discharge is established between the anode and cathode. The gas is then withdrawn from the manifold through the annulus between the anode and cathode by a pressure differential. The gas is then ionized by the arc discharge across the annulus. The ionized gas is withdrawn from the annulus by the combined effects of the pressure differential and a collimating magnetic field. In a 3000 gauss magnetic field, an arc voltage of 1800 volts, and an arc current of 0.2 amp, a plasma of about 3 x 10/sup 11/ particles/cc is obtained. (AEC)

  3. Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T. [College of Science and Technology, Nihon University, 1-8-14 Kanda, Chiyoda-ku, Tokyo 1018308 (Japan); Gota, H.; Garate, E.; Allfrey, I.; Valentine, T.; Morehouse, M.; Roche, T.; Kinley, J.; Aefsky, S.; Cordero, M.; Waggoner, W.; Binderbauer, M. [Tri Alpha Energy, Inc., P.O. Box 7010 Rancho Santa Margarita, California 92688 (United States); Tajima, T. [Tri Alpha Energy, Inc., P.O. Box 7010 Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

    2016-05-15

    A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10{sup 21} m{sup −3}, ∼40 eV, and 0.5–1.0 × 10{sup 19}, respectively.

  4. Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device.

    Science.gov (United States)

    Matsumoto, T; Sekiguchi, J; Asai, T; Gota, H; Garate, E; Allfrey, I; Valentine, T; Morehouse, M; Roche, T; Kinley, J; Aefsky, S; Cordero, M; Waggoner, W; Binderbauer, M; Tajima, T

    2016-05-01

    A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10(21) m(-3), ∼40 eV, and 0.5-1.0 × 10(19), respectively.

  5. Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device

    International Nuclear Information System (INIS)

    Matsumoto, T.; Sekiguchi, J.; Asai, T.; Gota, H.; Garate, E.; Allfrey, I.; Valentine, T.; Morehouse, M.; Roche, T.; Kinley, J.; Aefsky, S.; Cordero, M.; Waggoner, W.; Binderbauer, M.; Tajima, T.

    2016-01-01

    A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10"2"1 m"−"3, ∼40 eV, and 0.5–1.0 × 10"1"9, respectively.

  6. Design of a Compact Coaxial Magnetized Plasma Gun for Magnetic Bubble Expansion Experiments

    Science.gov (United States)

    2009-06-01

    a peak a current Igun~ 80 kA and gun voltages Vgun~1 kV utine operation at a bank voltage of 7.5 kV yiel plasm after breakdown. Typical Igun and...and D2 are power electronic diodes, SW is the dump relay and C is the bias flux capacitor bank. The SCR, controlled by a 1 kV Trigger Pulse...capacitor charging circuit is shown in Figure 8. Figure 8. Gas valve capacitor charging circuit diagram 0 kΩ. 1, D2 and D3 are power electronic

  7. Measurements of ion temperature and flow of pulsed plasmas produced by a magnetized coaxial plasma gun device using an ion Doppler spectrometer

    Science.gov (United States)

    Kitagawa, Y.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    It is important to know surface damage characteristics of plasma-facing component materials during transient heat and particle loads such as type I ELMs. A magnetized coaxial plasma gun (MCPG) device has been used as transient heat and particle source in ELM simulation experiments. Characteristics of pulsed plasmas produced by the MCPG device play an important role for the plasma material interaction. In this study, ion temperature and flow velocity of pulsed He plasmas were measured by an ion Doppler spectrometer (IDS). The IDS system consists of a light collection system including optical fibers, 1m-spectrometer and a 16 channel photomultiplier tube (PMT) detector. The IDS system measures the width and Doppler shift of HeII (468.58 nm) emission line with the time resolution of 1 μs. The Doppler broadened and shifted spectra were measured with 45 and 135 degree angles with respect to the plasmoid traveling direction. The observed emission line profile was represented by sum of two Gaussian components to determine the temperature and flow velocity. The minor component at around the wavelength of zero-velocity was produced by the stationary plasma. As the results, the ion velocity and temperature were 68 km/s and 19 eV, respectively. Thus, the He ion flow energy is 97 eV. The observed flow velocity agrees with that measured by a time of flight technique.

  8. Excitation of plasma waves by electron guns at the ISEE-1 satellite

    International Nuclear Information System (INIS)

    Lebreton, Zh.P.; Torbert, R.; Anderson, R.; Kharvi, K.

    1985-01-01

    Study of the effects resulting from excitation of plasma waves by electron beams injected from JSEE-1 satellite is carried out. Cases of the satellite traversing the magnetosphere magnetosheath and solar wind are considered. 10-60 μA and 0-40 V electron beam injection from the satellite increased electrostatic waves spectral intensity. The waves below ionic plasma frequency are interpreted as ion acoustic waves. To explain the-above-electron-plasma-frequency wave oscillation a communication system between electron plasma mode and electron flux with the velocities above the mean thermal velocity of plasma cold electrons is suggested

  9. Gun Safety

    Science.gov (United States)

    Many U.S. households have guns, but they can cause harm if not handled properly. Here are some things you can do to keep yourself and ... safe: Teach children that they shouldn't touch guns and that if they see a gun, to ...

  10. Analytical and experimental investigation of the coaxial plasma gun for use as a particle accelerator

    Science.gov (United States)

    Shriver, E. L.

    1972-01-01

    The coaxial plasma accelerator for use as a projectile accelerator is discussed. The accelerator is described physically and analytically by solution of circuit equations, and by solving for the magnetic pressures which are formed by the j cross B vector forces on the plasma. It is shown that the plasma density must be increased if the accelerator is to be used as a projectile accelerator. Three different approaches to increasing plasma density are discussed. When a magnetic field containment scheme was used to increase the plasma density, glass beads of 0.66 millimeter diameter were accelerated to 7 to 8 kilometers per second velocities. Glass beads of smaller diameter were accelerated to more than twice this velocity.

  11. The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

    Science.gov (United States)

    Cornish, S.; Khachan, J.

    2016-02-01

    A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required.

  12. The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

    International Nuclear Information System (INIS)

    Cornish, S.; Khachan, J.

    2016-01-01

    A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required. (paper)

  13. Prospects for deflagration guns

    International Nuclear Information System (INIS)

    Cheng, D.Y.; Tripathi, P.P.; Chang, C.N.

    1978-01-01

    Deflagration is a process of fluid expansion with energy addition. Its existence in plasma physics was first discovered in the back-strapped T-tube experiments. In the coaxial plasma gun configuration the operation can be simple and yet produce a clean, high density (5 x 10 15 cm -3 ), and high kinetic energy (10 to 50 keV) collimated plasma beam. Plasma acceleration mechanism was thought to be driven by J x B force. Tapered electrodes have been used to obtain plasma beams. Scaling of the gun can be performed according to simple theory based on momentum and energy balance. Proposed plasma fueling and injection to magnetic fusion systems will be discussed

  14. Pilot study of synchronization on a femtosecond scale between the electronic gun REGAE and a laser-plasma accelerator

    International Nuclear Information System (INIS)

    Titberidze, Mikheil

    2017-10-01

    Laser wakefield acceleration (LWFA) is a novel technique to accelerate charged particles. Acceleration is achieved by a high-power laser pulse transmitting a gas target where electrons and ions form a strong wakefield with gradients up to 100 GVm -1 . Hence, the size of the laser-plasma accelerator (LPA) is significantly smaller compared to conventional radio frequency (RF) accelerators, because its accelerating gradients are 3 orders of magnitude higher. At present, electron beams generated by LWFA do not satisfy all requirements to make them directly usable for applications such as LPA driven free-electron laser (FEL). Pointing stability and relatively high energy spread are the major limiting factors. Typically, plasma electrons are self-injected in the plasma wake which is created by a high-power laser. There is a lack of control for the injection process and there is no direct access for diagnostics. In order to overcome these challenges and better understand the overall LWFA process, external injection experiments are planned at Deutsches Elektronen-Synchrotron (DESY) in the framework of the Laboratory for Laser and beam-driven plasma Acceleration (LAOLA) collaboration. Thus, well characterized and ultrashort (< 10 fs) electron bunches from the conventional RF accelerator Relativistic Electron Gun for Atomic Exploration (REGAE) will be injected into the laser driven plasma wake. This approach allows to reconstruct and map the plasma wakefield by post diagnosing the injected electron bunches by measuring the energy spectra of it for different injection times. To conduct such a pump-probe type of experiment, synchronization with fs accuracy is required between the electron bunches from REGAE and the high-power driver laser. Two main aspects of the laser synchronization are presented in this thesis. First, a detailed experimental investigation of the conventional, fast photodiode based direct conversion laser-to-RF synchronization setup and its limitations are

  15. Pilot study of synchronization on a femtosecond scale between the electronic gun REGAE and a laser-plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Titberidze, Mikheil

    2017-10-15

    Laser wakefield acceleration (LWFA) is a novel technique to accelerate charged particles. Acceleration is achieved by a high-power laser pulse transmitting a gas target where electrons and ions form a strong wakefield with gradients up to 100 GVm{sup -1}. Hence, the size of the laser-plasma accelerator (LPA) is significantly smaller compared to conventional radio frequency (RF) accelerators, because its accelerating gradients are 3 orders of magnitude higher. At present, electron beams generated by LWFA do not satisfy all requirements to make them directly usable for applications such as LPA driven free-electron laser (FEL). Pointing stability and relatively high energy spread are the major limiting factors. Typically, plasma electrons are self-injected in the plasma wake which is created by a high-power laser. There is a lack of control for the injection process and there is no direct access for diagnostics. In order to overcome these challenges and better understand the overall LWFA process, external injection experiments are planned at Deutsches Elektronen-Synchrotron (DESY) in the framework of the Laboratory for Laser and beam-driven plasma Acceleration (LAOLA) collaboration. Thus, well characterized and ultrashort (< 10 fs) electron bunches from the conventional RF accelerator Relativistic Electron Gun for Atomic Exploration (REGAE) will be injected into the laser driven plasma wake. This approach allows to reconstruct and map the plasma wakefield by post diagnosing the injected electron bunches by measuring the energy spectra of it for different injection times. To conduct such a pump-probe type of experiment, synchronization with fs accuracy is required between the electron bunches from REGAE and the high-power driver laser. Two main aspects of the laser synchronization are presented in this thesis. First, a detailed experimental investigation of the conventional, fast photodiode based direct conversion laser-to-RF synchronization setup and its limitations

  16. Development of a double plasma gun device for investigation of effects of vapor shielding on erosion of PFC materials under ELM-like pulsed plasma bombardment

    Science.gov (United States)

    Sakuma, I.; Iwamoto, D.; Kitagawa, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    It is considered that thermal transient events such as type I edge localized modes (ELMs) could limit the lifetime of plasma-facing components (PFCs) in ITER. We have investigated surface damage of tungsten (W) materials under transient heat and particle loads by using a magnetized coaxial plasma gun (MCPG) device at University of Hyogo. The capacitor bank energy for the plasma discharge is 144 kJ (2.88 mF, 10 kVmax). Surface melting of a W material was clearly observed at the energy density of ˜2 MJ/m2. It is known that surface melting and evaporation during a transient heat load could generate a vapor cloud layer in front of the target material [1]. Then, the subsequent erosion could be reduced by the vapor shielding effect. In this study, we introduce a new experiment using two MCPG devices (MCPG-1, 2) to understand vapor shielding effects of a W surface under ELM-like pulsed plasma bombardment. The capacitor bank energy of MCPG-2 is almost same as that of MCPG-1. The second plasmoid is applied with a variable delay time after the plasmoid produced by MCPG-1. Then, a vapor cloud layer could shield the second plasma load. To verify the vapor shielding effects, surface damage of a W material is investigated by changing the delay time. In the conference, the preliminary experimental results will be shown.[4pt] [1] A. Hassanein et al., J. Nucl. Mater. 390-391, pp. 777-780 (2009).

  17. Stimulation of plasma waves by electron guns on the ISEE-1 satellite

    Science.gov (United States)

    Lebreton, J.-P.; Torbert, R.; Anderson, R.; Harvey, C.

    1982-01-01

    The results of the ISEE-1 satellite experiment relating to observations of the waves stimulated during electron injections, when the spacecraft is passing through the magnetosphere, the magnetosheath, and the solar wind, are discussed. It is shown that the injection of an electron beam current of the order of 10 to 60 microamperes with energies ranging from 0 to 40 eV produces enhancements in the electric wave spectrum. An attempt has been made to identify the low-frequency electrostatic wave observed below the ion plasma frequency as an ion acoustic mode, although the excitation mechanism is not clear. A coupling mechanism between the electron plasma mode and streaming electrons with energies higher than the thermal speed of the cold electron population has been proposed to explain the observations above the electron plasma frequency.

  18. Impulse electron gun with plasma cathode for realization of large diameter tube-shaped beams

    International Nuclear Information System (INIS)

    Antipov, V.S.; Karpukhin, V.I.; Kornilov, E.A.

    1999-01-01

    There are presented the results of investigations of a plasma electron source based on the gas discharge in a coaxial system of electrodes with longitudinal magnetic field. The examination is fulfilled from the viewpoint of applying the source as a plasma cathode for hybrid plasma-waveguide slow-wave structures on the basis of a disk-loaded coaxial. The source is optimized in order to get a powerful (up to 100 kW) nonrelativistic electron beam with the annular cross-section of a large diameter in the regime of relatively long current pulses (up to 0.2 ms) under the gas pressure ∼ 5 centre dot 10 -4 mm Hg in the area of the discharge burning

  19. Stimulation of plasma waves by electron guns on the ISEE-1 satellite

    International Nuclear Information System (INIS)

    Lebreton, J.P.; Torbert, R.; Anderson, R.; Harvey, C.

    1982-01-01

    The results of the ISEE-1 satellite experiment relating to observations of the waves stimulated during electron injections, when the spacecraft is passing through the magnetosphere, the magnetosheath, and the solar wind, are discussed. It is shown that the injection of an electron beam current of the order of 10 to 60 microamperes with energies ranging from 0 to 40 eV produces enhancements in the electric wave spectrum. An attempt has been made to identify the low-frequency electrostatic wave observed below the ion plasma frequency as an ion acoustic mode, although the excitation mechanism is not clear. A coupling mechanism between the electron plasma mode and streaming electrons with energies higher than the thermal speed of the cold electron population has been proposed to explain the observations above the electron plasma frequency. 9 references

  20. Results of the AFWL deflagration gun experiments

    International Nuclear Information System (INIS)

    Hackett, K.E.; Baker, W.L.; Beason, J.D.

    1987-01-01

    The snowplow and deflagration modes of coaxial plasma gun operation have been experimentally investigated and computationally simulated at the Air Force Weapons Laboratory. The snowplow mode occurs when the gun is prefilled to a uniform gas density. The initial breakdown forms near the insulator at the gun breech. It heats the gas and creates a shock wave that travels down the gun, ionizing gas and producing a thin current sheath that travels just behind the shock front. The shock front piles up the gas in front of itself as it moves down the gun - hence the name ''snowplow''. Deflagration occurs when gas is injected into an evacuated gun so that the initial breakdown forms as the gas fills the gun. The ionized gas is accelerated into the vacuum region carrying current and magnetic field with it. A quasi-stationary diffuse discharge develops. Gas still entering the gun is processed through the deflagrating discharge and accelerated out the gun muzzle

  1. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes.

    Science.gov (United States)

    Kumar, Niraj; Pal, Dharmendra Kumar; Jadon, Arvind Singh; Pal, Udit Narayan; Rahaman, Hasibur; Prakash, Ram

    2016-03-01

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ∼50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  2. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Niraj; Pal, Udit Narayan; Prakash, Ram [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan 333031 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-CEERI Campus, Pilani (India); Pal, Dharmendra Kumar; Jadon, Arvind Singh; Rahaman, Hasibur [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan 333031 (India)

    2016-03-15

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ∼50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  3. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes

    International Nuclear Information System (INIS)

    Kumar, Niraj; Pal, Udit Narayan; Prakash, Ram; Pal, Dharmendra Kumar; Jadon, Arvind Singh; Rahaman, Hasibur

    2016-01-01

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ∼50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  4. Theory of field-reversed mirrors and field-reversed plasma-gun experiments. Paper IAEA-CN-38/R-2

    International Nuclear Information System (INIS)

    Anderson, D.V.; Auerbach, S.P.; Berk, H.L.

    1980-01-01

    Experimental and theoretical studies of field reversal in a mirror machine are reported. Plasma-gun experiments demonstrate that reversed-field plasma layers are formed. Low energy plasma flowing behind the initially produced plasma front prevents tearing of the layer from the gun muzzle. MHD simulation shows that tearing can be obtained by impeding the slow plasma flow with a plasma divider. It is demonstrated theoretically that a field-reversed mirror imbedded in a multipole field can be sustained in steady state with neutral-beam injection even in the absence of impurities. MHD stability analysis shows that growth rates of elongated reversed-field theta-pinch configurations decrease with axial extension, which indicates the importance of including finite Larmor radius in the analysis. Tilting-mode criteria are improved by proper shaping, and a problimak shape is proposed. Tearing mode stability of reversed-field theta-pinches is greatly enhanced by flux exclusion. Self-consistent, 1-1/2-dimensional transport codes have been developed, and initial results are presented

  5. Theory of field-reversed mirrors and field-reversed plasma-gun experiments. Paper IAEA-CN-38/R-2

    International Nuclear Information System (INIS)

    Anderson, D.V.; Auerbach, S.P.; Berk, H.L.

    1980-01-01

    Experimental and theoretical studies of field reversal in a mirror machine are reported. Plasma-gun experiments demonstrate that reversed-field plasma layers are formed. Low energy plasma flowing behind the initially produced plasma front prevents tearing of the layer from the gun muzzle. MHD simulation shows that tearing can be obtained by impeding the slow plasma flow with a plasma divider. It is demonstrated theoretically that a field-reversed mirror imbedded in a multipole field can be sustained in steady state with neutral-beam injection even in the absence of impurities. MHD stability analysis shows that growth rates of elongated reversed-field theta-pinch configurations decrease with axial extension, which indicates the importance of including finite Larmor radius in the analysis. Tilting-mode criteria are dramatically improved by proper shaping, and a problimak shape is proposed. Tearing mode stability of reversed-field theta-pinches is greatly enhanced by flux exclusion. Self-consistent, 1-1/2-dimensional transport codes have been developed, and initial results are presented

  6. A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode

    OpenAIRE

    Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.

    2013-01-01

    Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spe...

  7. Performance improvement of magnetized coaxial plasma gun by magnetic circuit on a bias coil

    Science.gov (United States)

    Edo, Takahiro; Matsumoto, Tadafumi; Asai, Tomohiko; Kamino, Yasuhiro; Inomoto, Michiaki; Gota, Hiroshi

    2016-10-01

    A magnetized coaxial plasmoid accelerator has been utilized for compact torus (CT) injection to refuel into fusion reactor core plasma. Recently, CT injection experiments have been conducted on the C-2/C-2U facility at Tri Alpha Energy. In the series of experiments successful refueling, i.e. increased particle inventory of field-reversed configuration (FRC) plasma, has been observed. In order to improve the performance of CT injector and to refuel in the upgraded FRC device, called C-2W, with higher confinement magnetic field, magnetic circuit consisting of magnetic material onto a bias magnetic coil is currently being tested at Nihon University. Numerical work suggests that the optimized bias magnetic field distribution realizes the increased injection velocity because of higher conversion efficiency of Lorenz self force to kinetic energy. Details of the magnetic circuit design as well as results of the test experiment and field calculations will be presented and discussed.

  8. Isothermal oxidation of metallic coatings deposited by a water-stabilized plasma gun

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Nop, P.; Kopřiva, P.; Kolman, Blahoslav Jan; Dubský, Jiří

    2006-01-01

    Roč. 44, č. 1 (2006), s. 41-48 ISSN 0023-432X R&D Projects: GA ČR(CZ) GA106/03/0710 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma spraying * metallic coatings * oxidation tests * oxidation kinetics * oxide structure * element distribution Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.138, year: 2006

  9. Bibliography of Documents Related to the Theory, Operation, Performance and Applications of Coaxial Plasma Guns. Revision

    Science.gov (United States)

    1990-11-01

    V., Grunberger, L. and Prior, W., "Observation of Solar Flare Type Processes in the Laboratory," in Solar Magnetic Fields, Symposium No. 43 of the...RF/FUS/84/6, Associazione EURATOM--Comitato Nazionale Energia Nucleare sulla Fusione, Centro di Frascati, Rome, Italy, September 1984. Brzosko, J. S...Energy Deuteron Beam Generation in Plasma Focus," Report No. 80.5, Associazione EURATOM--Comitato Nazionale Energia Nucleare sulla Fusione, Centro di

  10. Gun Safety (For Kids)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Gun Safety KidsHealth / For Kids / Gun Safety What's in ... from guns outside the home. If You Have Guns in Your Home If your parents keep guns ...

  11. Sanoli Gun

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences. Sanoli Gun. Articles written in Proceedings – Mathematical Sciences. Volume 119 Issue 3 June 2009 pp 275-281. Remarks on some Zero-Sum Theorems · S D Adhikari Sanoli Gun Purusottam Rath · More Details Abstract Fulltext PDF. In the present paper, we give a ...

  12. Plasma electrolytic polishing of metalized carbon fibers

    Directory of Open Access Journals (Sweden)

    Falko Böttger-Hiller

    2016-02-01

    Full Text Available Efficient lightweight structures require intelligent materials that meet versatile functions. Especially, carbon-fiber-reinforced polymers (CFRPs are gaining relevance. Their increasing use aims at reducing energy consumption in many applications. CFRPs are generally very light in weight, while at the same time being extremely stiff and strong (specific strength: CFRPs: 1.3 Nm kg–1, steel: 0.27 Nm kg–1; specific stiffness: CFRPs: 100 Nm kg–1, steel: 25 Nm kg–1. To increase performance and especially functionality of CFRPs, the integration of microelectronic components into CFRP parts is aspired. The functionalization by sensors, actuators and electronics can enable a high lightweight factor and a new level of failure-safety. The integration of microelectronic components for this purpose requires a working procedure to provide electrical contacts for a reliable connection to energy supply and data interfaces. To overcome this challenge, metalized carbon fibers are used. Metalized fibers are, similar to the usual reinforcing fibers, able to be soldered and therefore easy to incorporate into CFRPs. Unfortunately, metalized fibers have to be pre-treated by flux-agents. Until now, there is no flux which is suitable for mass production without destroying the polymer of the CFRP. The process of plasma electrolytic polishing (PeP could be an option, but is so far not available for copper. Thus, in this study, plasma electrolytic polishing is transferred to copper and its alloys. To achieve this, electrolytic parameters as well as the electrical setup are adapted. It can be observed that the gloss and roughness can be adjusted by means of this procedure. Finally, plasma electrolytic polishing is used to treat thin copper layers on carbon fibers.

  13. Gun Control, Gun Ownership, and Suicide Prevention.

    Science.gov (United States)

    Lester, David

    1988-01-01

    Explored relationship between the extent of gun ownership and the strictness of gun control laws to suicide and homicide rates in the nine major geographic regions of the United States. Found gun ownership, rather than the strictness of gun control laws, was the strongest correlate of the rates of suicide and homicide by guns. (Author)

  14. Tritium Removal from Carbon Plasma Facing Components

    International Nuclear Information System (INIS)

    Skinner, C.H.; Coad, J.P.; Federici, G.

    2003-01-01

    Tritium removal is a major unsolved development task for next-step devices with carbon plasma-facing components. The 2-3 order of magnitude increase in duty cycle and associated tritium accumulation rate in a next-step tokamak will place unprecedented demands on tritium removal technology. The associated technical risk can be mitigated only if suitable removal techniques are demonstrated on tokamaks before the construction of a next-step device. This article reviews the history of codeposition, the tritium experience of TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) and the tritium removal rate required to support ITER's planned operational schedule. The merits and shortcomings of various tritium removal techniques are discussed with particular emphasis on oxidation and laser surface heating

  15. Synthesis and characterization of carbon fibers obtained through plasma techniques; Sintesis y caracterizacion de fibras de carbono obtenidas mediante tecnicas de plasma

    Energy Technology Data Exchange (ETDEWEB)

    Valdivia B, M

    2005-07-01

    The study of carbon, particularly the nano technology is a recent field, the one which has important implications in the science of new materials. It investigation is of great interest for industries producers of ceramic, metallurgy, electronic, energy storage, biomedicine, among others. The diverse application fields are a reason at national as international level, so that many works are focused in the production of nano fibers of carbon. The Thermal plasma applications laboratory (LAPT) of the National Institute of Nuclear Research (ININ), it is carrying out works about carbon nano technology. The present work has as purpose to carry out the synthesis and characterization of the carbon nano fibers which are obtained by electric arch of alternating current (CA) to high frequencies and by a plasma gun of non transferred arch, where are used hydrocarbons like benzene, methane, acetylene like carbon source and ferrocene, nickel, yttrium and cerium oxide like catalysts. For both techniques its were thought about a relationship among hydrocarbon-catalyst that it favored to the nano fibers production. The obtained product of each experiment outlined it was analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD), analysis with those were obtained pictures and diffraction graphs, which were observed to arrive to one conclusion on the operation conditions, same analysis with those were characterized the tests carried out according to the nano structures formation of carbon. (Author)

  16. Electron gun

    International Nuclear Information System (INIS)

    Chen, H.-Y.; Hughes, R.H.

    1979-01-01

    The invention described relates to cathode ray tubes, and particularly to color picture tubes of the type useful in home television receivers and therefore to electron guns. The invention is especially applicable to self-converging tube-yoke combinations with shadow mask tubes of the type having plural-beam in-line guns disposed in a horizontal plane, an apertured mask with vertically oriented slit-shaped apertures, and a screen with vertically oriented phosphor stripes. The invention is not, however, limited to use in such tubes and may in fact be used, e.g., in dot-type shadow mask tubes and index-type tubes. (Auth.)

  17. Microwave plasma CVD of NANO structured tin/carbon composites

    Science.gov (United States)

    Marcinek, Marek [Warszawa, PL; Kostecki, Robert [Lafayette, CA

    2012-07-17

    A method for forming a graphitic tin-carbon composite at low temperatures is described. The method involves using microwave radiation to produce a neutral gas plasma in a reactor cell. At least one organo tin precursor material in the reactor cell forms a tin-carbon film on a supporting substrate disposed in the cell under influence of the plasma. The three dimensional carbon matrix material with embedded tin nanoparticles can be used as an electrode in lithium-ion batteries.

  18. Spectrometer gun

    Science.gov (United States)

    Waechter, David A.; Wolf, Michael A.; Umbarger, C. John

    1985-01-01

    A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

  19. Carbon materials modified by plasma treatment as electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lota, Grzegorz; Frackowiak, Elzbieta [Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Piotrowo 3, 60-965 Poznan (Poland); Tyczkowski, Jacek; Kapica, Ryszard [Technical University of Lodz, Faculty of Process and Environmental Engineering, Division of Molecular Engineering, Wolczanska 213, 90-924 Lodz (Poland); Lota, Katarzyna [Institute of Non-Ferrous Metals Branch in Poznan, Central Laboratory of Batteries and Cells, Forteczna 12, 61-362 Poznan (Poland)

    2010-11-15

    The carbon material was modified by RF plasma with various reactive gases: O{sub 2}, Ar and CO{sub 2}. Physicochemical properties of the final carbon products were characterized using different techniques such as gas adsorption method and XPS. Plasma modified materials enriched in oxygen functionalities were investigated as electrodes for supercapacitors in acidic medium. The electrochemical measurements have been carried out using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The electrochemical measurements have confirmed that capacity characteristics are closely connected with a type of plasma exposition. Modification processes have an influence on the kind and amount of surface functional groups in the carbon matrix. The moderate increase of capacity of carbon materials modified by plasma has been observed using symmetric two-electrode systems. Whereas investigations made in three-electrode system proved that the suitable selection of plasma modification parameters allows to obtain promising negative and positive electrode materials for supercapacitor application. (author)

  20. Plasma effects in aligned carbon nanoflake growth by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Cheng, Q.J., E-mail: qijin.cheng@xmu.edu.cn [School of Energy Research, Xiamen University, Xiamen 361005 (China); Ostrikov, K. [Plasma Nanoscience Center Australia (PNCA), Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, PO Box 218, Lindfield 2070, NSW (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, QLD (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney 2006, NSW (Australia)

    2015-01-15

    Highlights: • Plasma-specific effects in the growth of carbon nanoflakes (CNFs) are studied. • Electic field in the plasma sheath promotes separation of CNFs from the substrate. • The orentention of GNFs is related to the combined electic force and growth effects. • The high growth grates of aligned GNFs are plasma-related. - Abstract: Carbon nanofilms are directly grown on silicon substrates by plasma-enhanced hot filament chemical vapor deposition in methane environment. It is shown that the nanofilms are composed of aligned carbon nanoflakes by extensive investigation of experimental results of field emission scanning electron microscopy, micro-Raman spectroscopy and transmission electron microscopy. In comparison with the graphene-like films grown without plasmas, the carbon nanoflakes grow in an alignment mode and the growth rate of the films is increased. The effects of the plasma on the growth of the carbon nanofilms are studied. The plasma plays three main effects of (1) promoting the separation of the carbon nanoflakes from the silicon substrate, (2) accelerating the motion of hydrocarbon radicals, and (3) enhancing the deposition of hydrocarbon ions onto the substrate surface. Due to these plasma-specific effects, the carbon nanofilms can be formed from the aligned carbon nanoflakes with a high rate. These results advance our knowledge on the synthesis, properties and applications of graphene-based materials.

  1. Characterization of a Carbon Nanotube Field Emission Electron Gun for the VAPoR Miniaturized Pyrolysis-Time-of-Flight Mass Spectrometer

    Science.gov (United States)

    Getty, Stephanie; Li, Mary; Costen, Nicholas; Hess, Larry; Feng, Steve; King, Todd; Brinckerhoff, William; Mahaffy, Paul; Glavin, Daniel

    2009-01-01

    We are developing the VAPoR (Volatile Analysis by Pyrolysis of Regolith) instrument towards studying soil composition, volatiles, and trapped noble gases in the polar regions of the Moon. VAPOR will ingest a soil sample and conduct analysis by pyrolysis and time-of-flight mass spectrometry (ToF-MS). Here, we describe miniaturization efforts within this development, including a carbon nanotube (CNT) field emission electron gun that is under consideration for use as the electron impact ionization source for the ToF-MS.

  2. Performance Improvement of a Magnetized Coaxial Plasma Gun by adopting Iron-core Bias Coil and New Pre-Ionization System

    Science.gov (United States)

    Edo, Takahiro; Asai, T.; Tanaka, F.; Yamada, S.; Hosozawa, A.; Gota, H.; Roche, T.; Allfrey, I.; Matsumoto, T.

    2017-10-01

    A magnetized coaxial plasma gun (MCPG) is a device used to generate a compact toroid (CT), which has a spheromak-like configuration. A typical MCPG consists of a set of axisymmetric cylindrical electrodes, bias coil, and gas-puff valves. In order to expand the CT operating range, the distributions of the bias magnetic field and neutral gas have been investigated. We have developed a new means of generating stuffing flux. By inserting an iron core into the bias coil, the magnetic field increases dramatically; even a small current of a few Amps produces a sufficient bias field. According to a simulation result, it was also suggested that the radial distribution of the bias field is easily controlled. The ejected CT and the target FRC are cooled by excess neutral gas that typical MCPGs require to initiate a breakdown; therefore, we have adopted a miniature gun as a new pre-ionization (PI) system. By introducing this PI system, the breakdown occurs at lower neutral gas density so that the amount of excess neutral gas can be reduced.

  3. Plasma cleaning and the removal of carbon from metal surfaces

    International Nuclear Information System (INIS)

    Baker, M.A.

    1980-01-01

    In an investigation of the plasma cleaning of metals and the plasma etching of carbon, a mass spectrometer was used as a sensitive process monitor. CO 2 produced by the plasma oxidation of carbon films or of organic contamination and occluded carbon at the surfaces of metals proved to be the most suitable gas to monitor. A good correlation was obtained between the measured etch rate of carbon and the resulting CO 2 partial pressure monitored continuously with the mass spectrometer. The rate of etching of carbon in an oxygen-argon plasma at 0.1 Torr was high when the carbon was at cathode potential and low when it was electrically isolated in the plasma, thus confirming the findings of previous workers and indicating the importance of ion bombardment in the etching process. Superficial organic contamination on the surfaces of the metals aluminium and copper and of the alloy Inconel 625 was quickly removed by the oxygen-argon plasma when the metal was electrically isolated and also when it was at cathode potential. Occluded carbon (or carbides) at or near the surfaces of the metals was removed slowly and only when the metal was at cathode potential, thus illustrating again the importance of ion bombardment. (Auth.)

  4. Water gun vs air gun: A comparison

    Science.gov (United States)

    Hutchinson, D.R.; Detrick, R. S.

    1984-01-01

    The water gun is a relatively new marine seismic sound source that produces an acoustic signal by an implosive rather than explosive mechanism. A comparison of the source characteristics of two different-sized water guns with those of conventional air guns shows the the water gun signature is cleaner and much shorter than that of a comparable-sized air gun: about 60-100 milliseconds (ms) for an 80-in3. (1.31-liter (I)) water gun compared with several hundred ms for an 80-in3. (1.31-1) air gun. The source spectra of water guns are richer in high frequencies (>200 Hz) than are those of air guns, but they also have less energy than those of air guns at low frequencies. A comparison between water gun and air gun reflection profiles in both shallow (Long Island Sound)-and deep (western Bermuda Rise)-water settings suggests that the water gun offers a good compromise between very high resolution, limited penetration systems (e.g. 3.5-kHz profilers and sparkers) and the large volume air guns and tuned air gun arrays generally used where significant penetration is required. ?? 1984 D. Reidel Publishing Company.

  5. Changes in plasma potassium concentration during carbon dioxide pneumoperitoneum

    DEFF Research Database (Denmark)

    Perner, A; Bugge, K; Lyng, K M

    1999-01-01

    Hyperkalaemia with ECG changes had been noted during prolonged carbon dioxide pneumoperitoneum in pigs. We have compared plasma potassium concentrations during surgery in 11 patients allocated randomly to undergo either laparoscopic or open appendectomy and in another 17 patients allocated randomly...... to either carbon dioxide pneumoperitoneum or abdominal wall lifting for laparoscopic colectomy. Despite an increasing metabolic acidosis, prolonged carbon dioxide pneumoperitoneum resulted in only a slight increase in plasma potassium concentrations, which was both statistically and clinically insignificant....... Thus hyperkalaemia is unlikely to develop in patients with normal renal function undergoing carbon dioxide pneumoperitoneum for laparoscopic surgery....

  6. Improved plasma accelerator

    Science.gov (United States)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  7. Hard-driven rail-gun tests

    International Nuclear Information System (INIS)

    Peterson, D.R.; Adams, D.F.; Cummings, C.E.; Fowler, C.M.; Kerrisk, J.F.; Marsh, S.P.; Parker, J.V.

    1983-01-01

    A number of prototype rail-gun designs have been tested, powered by explosive magnetic flux compression generators. Peak currents as high as 1.3 MA were delivered. Rail guns with 50-mm-thick Kevlar fiberwound structural shells were able to survive these high currents with minimum mechanical damage and were refired after enlarging the bores 0.2 to 0.4 mm to remove arc damage. In some tests, mechanical damage occurred that was apparently caused by the rebound of the gun after firing. Although the Kevlar shells had more than adequate strength, they appeared to lack sufficient stiffness, allowing excessive deflections. The use of a steel structural shell with a Kevlar sleeve was an improvement. Intrusion into the seams of the rail guns and condensation of material from the plasma armature were observed. Improved sealing of seams is indicated. In some cases, we suspect maldistribution of current within the gun; that is, not all the current delivered to the breech of the gun seemed to reach the plasma armature. Experiments are being designed to quantify the effects discussed. Rail guns of advanced design are being fabricated. An 18-g titanium projectile was accelerated to 2.4 km/s in a 16-mm-round-bore, 0.6-m-long gun, 4-6 g polycarbonate projectiles were accelerated to 3.5 km/s in 13-mm-square-bore, 1.2-m-long rail guns. All tests were conducted at atmospheric pressure

  8. A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode

    Energy Technology Data Exchange (ETDEWEB)

    Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A. [High Temperature Gasdynamics Laboratory, Stanford University, Stanford, California 94305 (United States)

    2013-07-15

    Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.

  9. A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode

    International Nuclear Information System (INIS)

    Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.

    2013-01-01

    Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions

  10. A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode

    Science.gov (United States)

    Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.

    2013-07-01

    Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.

  11. A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode.

    Science.gov (United States)

    Rieker, G B; Poehlmann, F R; Cappelli, M A

    2013-07-01

    Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.

  12. Atmospheric pressure plasma surface modification of carbon fibres

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Michelsen, Poul

    2008-01-01

    Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He...

  13. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    International Nuclear Information System (INIS)

    Fetterman, Abe; Raitses, Yevgeny; Keidar, Michael

    2008-01-01

    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.

  14. Atmospheric pressure plasma treatment of glassy carbon for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, Henrik Junge; Stenum, Bjarne

    2007-01-01

    density increased with the plasma treatments. Adhesion test of the treated glassy carbon covered with cured epoxy showed cohesive failure, indicating strong bonding after the treatments. This is in contrast to the adhesion tests of untreated samples where the epoxy readily peeled off the glassy carbon....

  15. Hypergravity synthesis of graphitic carbon nanomaterial in glide arc plasma

    NARCIS (Netherlands)

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

    2014-01-01

    A nanostructured carbon material was synthesized using a methane/helium glide arc plasma under standard and increased gravity. Material analysis performed on samples collected from an effluent gas filter showed that the deposited material was present in the form of carbon nanoparticles. They

  16. Low Energy Electron Gun on Board a Scientific Satellite GEOTAIL

    OpenAIRE

    TSUTSUI, Minoru; ONISHI, Yoshiaki; MATSUMOTO, Hiroshi; KIMURA, Iwane; 筒井, 稔; 大西, 嘉昭; 松本, 紘; 木村, 磐根

    1988-01-01

    A low energy electron gun to be used for beam-plasma interaction experiments by a scientific satellite GEOTAIL has been designed and manufactured. Electrodes of the gun have been modified from the Pierce type gun because of the use of a directly heated cathode. Spatial density distributions of beam electrons emitted from the new gun have been measured in a large vacuum chamber, and characteristic curves of emission currents for some beam energies and cathode powers have been checked repeatedl...

  17. Electro Thermal Chemical Gun Technology Study

    National Research Council Canada - National Science Library

    Diamond, P

    1999-01-01

    .... Michael Stroscio. Electro Thermal Chemical (ETC) gun technology refers to the use of plasma devices in place of traditional chemical ignitors to initiate the burning of high energy propellants in a controlled manner...

  18. Surface properties of activated carbon treated by cold plasma heating

    Energy Technology Data Exchange (ETDEWEB)

    Norikazu, Kurano [Shigematsu works Co. Ltd., 267 Yashita, Iwatsuki 3390046 (Japan); Yamada, Hiroshi [Shigematsu works Co. Ltd., 267 Yashita, Iwatsuki 3390046 (Japan); Yajima, Tatsuhiko [Faculty of Engineering, Saitama Institute of Technology, 1690 Fusoiji, Okabe 3690293 (Japan); Sugiyama, Kazuo [Faculty of Engineering, Saitama University, 255 Shimo-okubo, Sakura-Ku, Saitama 3388570 (Japan)]. E-mail: sugi@apc.saitama-u.ac.jp

    2007-03-12

    To modify the surface properties of activated carbon powders, we have applied the cold plasma treatment method. The cold plasma was used to be generated in the evacuated reactor vessel by 2.45 GHz microwave irradiation. In this paper, changes of surface properties such as distribution of acidic functional groups and roughness morphology were examined. By the cold plasma treatment, activated carbons with large specific surface area of ca. 2000 m{sup 2}/g or more could be prepared in a minute. The amount of every gaseous organic compound adsorbed on the unit gram of treated activated carbons was more increased that on the unit gram of untreated carbons. Especially, the adsorbed amount of carbon disulfide was remarkably increased even if it was compared by the amount per unit surface area. These results suggest that the surface property of the sample was modified by the plasma treatment. It became apparent by observing SEM photographs that dust and impure particles in macropores of activated carbons were far more reduced by the plasma treatment than by the conventional heating in an electric furnace under vacuum. In addition, a bubble-like surface morphology of the sample was observed by AEM measurement. The amount of acidic functional groups at the surface was determined by using the Boehm's titration method. Consequently, the increase of lactone groups and the decrease of carboxyl groups were also observed.

  19. 27.12 MHz plasma generation in supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Kawashima, Ayato; Toyota, Hiromichi; Nomura, Shinfuku; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro; Yamashita, Hiroshi

    2007-01-01

    An experiment was conducted for generating high-frequency plasma in supercritical carbon dioxide; it is expected to have the potential for applications in various types of practical processes. It was successfully generated at 6-20 MPa using electrodes mounted in a supercritical cell with a gap of 1 mm. Emission spectra were then measured to investigate the physical properties of supercritical carbon dioxide plasma. The results indicated that while the emission spectra for carbon dioxide and carbon monoxide could be mainly obtained at a low pressure, the emission spectra for atomic oxygen could be obtained in the supercritical state, which increased with the pressure. The temperature of the plasma in supercritical state was estimated to be approximately 6000-7000 K on the assumption of local thermodynamic equilibrium and the calculation results of thermal equilibrium composition in this state showed the increase of atomic oxygen by the decomposition of CO 2

  20. Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

    International Nuclear Information System (INIS)

    Bouanis, F.Z.; Bentiss, F.; Bellayer, S.; Vogt, J.B.; Jama, C.

    2011-01-01

    Highlights: → C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. → RF plasma treatment enables nitriding for non-heated substrates. → The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. → Nitrogen plasma active species diffuse into the samples and lead to the formation of Fe x N. → The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface. - Abstract: In this work, C38 carbon steel was plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge on non-heated substrates. General characterizations were performed to compare the chemical compositions, the microstructures and hardness of the untreated and plasma treated surfaces. The plasma nitriding was carried out on non-heated substrates at a pressure of 16.8 Pa, using N 2 gas. Surface characterizations before and after N 2 plasma treatment were performed by means of the electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Vickers microhardness measurements. The morphological and chemical analysis showed the formation of a uniform structure on the surface of the nitrided sample with enrichment in nitrogen when compared to untreated sample. The thickness of the nitride layer formed depends on the treatment time duration and is approximately 14 μm for 10 h of plasma treatment. XPS was employed to obtain chemical-state information of the plasma nitrided steel surfaces. The micromechanical results show that the surface microhardness increases as the plasma-processing time increases to reach, 1487 HV 0.005 at a plasma processing time of 8 h.

  1. Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Bouanis, F.Z. [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Bentiss, F. [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Bellayer, S.; Vogt, J.B. [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Jama, C., E-mail: charafeddine.jama@ensc-lille.fr [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France)

    2011-05-16

    Highlights: {yields} C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. {yields} RF plasma treatment enables nitriding for non-heated substrates. {yields} The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. {yields} Nitrogen plasma active species diffuse into the samples and lead to the formation of Fe{sub x}N. {yields} The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface. - Abstract: In this work, C38 carbon steel was plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge on non-heated substrates. General characterizations were performed to compare the chemical compositions, the microstructures and hardness of the untreated and plasma treated surfaces. The plasma nitriding was carried out on non-heated substrates at a pressure of 16.8 Pa, using N{sub 2} gas. Surface characterizations before and after N{sub 2} plasma treatment were performed by means of the electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Vickers microhardness measurements. The morphological and chemical analysis showed the formation of a uniform structure on the surface of the nitrided sample with enrichment in nitrogen when compared to untreated sample. The thickness of the nitride layer formed depends on the treatment time duration and is approximately 14 {mu}m for 10 h of plasma treatment. XPS was employed to obtain chemical-state information of the plasma nitrided steel surfaces. The micromechanical results show that the surface microhardness increases as the plasma-processing time increases to reach, 1487 HV{sub 0.005} at a plasma processing time of 8 h.

  2. Plasma production in carbon-based materials

    Czech Academy of Sciences Publication Activity Database

    Giuffreda, E.; Delle Side, D.; Nassisi, V.; Krása, Josef

    2017-01-01

    Roč. 406, Sep (2017), s. 225-228 ISSN 0168-583X Institutional support: RVO:68378271 Keywords : laser-ablation * pulsed-laser * target current Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.109, year: 2016

  3. ELECTRON GUN

    Science.gov (United States)

    Christofilos, N.C.; Ehlers, K.W.

    1960-04-01

    A pulsed electron gun capable of delivering pulses at voltages of the order of 1 mv and currents of the order of 100 amperes is described. The principal novelty resides in a transformer construction which is disposed in the same vacuum housing as the electron source and accelerating electrode structure of the gun to supply the accelerating potential thereto. The transformer is provided by a plurality of magnetic cores disposed in circumferentially spaced relation and having a plurality of primary windings each inductively coupled to a different one of the cores, and a helical secondary winding which is disposed coaxially of the cores and passes therethrough in circumferential succession. Additional novelty resides in the disposition of the electron source cathode filament input leads interiorly of the transformer secondary winding which is hollow, as well as in the employment of a half-wave filament supply which is synchronously operated with the transformer supply such that the transformer is pulsed during the zero current portions of the half-wave cycle.

  4. Gun ownership and social gun culture.

    Science.gov (United States)

    Kalesan, Bindu; Villarreal, Marcos D; Keyes, Katherine M; Galea, Sandro

    2016-06-01

    We assessed gun ownership rates in 2013 across the USA and the association between exposure to a social gun culture and gun ownership. We used data from a nationally representative sample of 4000 US adults, from 50 states and District of Columbia, aged >18 years to assess gun ownership and social gun culture performed in October 2013. State-level firearm policy information was obtained from the Brady Law Center and Injury Prevention and Control Center. One-third of Americans reported owning a gun, ranging from 5.2% in Delaware to 61.7% in Alaska. Gun ownership was 2.25-times greater among those reporting social gun culture (PR=2.25, 95% CI 2.02 to 2.52) than those who did not. In conclusion, we found strong association between social gun culture and gun ownership. Gun cultures may need to be considered for public health strategies that aim to change gun ownership in the USA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  5. Encyclopedia of Gun Control and Gun Rights.

    Science.gov (United States)

    Utter, Glenn H.

    This reference volume provides information on gun control and gun rights, including resources on the debate surrounding the Second Amendment and individuals and organizations focused on gun issues, along with statutes, court cases, events, and publications surrounding this current topic. Highlighted are the important organizations and their…

  6. Electron beam induced emission from carbon plasmas

    International Nuclear Information System (INIS)

    Whetstone, S.; Kammash, T.

    1989-01-01

    Plasma use as a lasing medium has many potential advantages over conventional techniques including increased power levels and greater wavelength ranges. The basic concept is to heat and then rapidly cool a plasma forcing inversion through bottleneck creation between the recombination reaction populating a given energy level and the subsequent decay processes. Much effort has been devoted to plasmas heated by lasers and pinch devices. The authors are concerned here with electron beam heated plasmas focusing on the CIV 5g-4f transition occurring at 2530 Angstroms. These studies were initiated to provide theoretical support for experiments being performed at the University of Michigan using the Michigan Electron Long-Pulse Beam Accelerator (MELBA)

  7. Gun control saves lives

    African Journals Online (AJOL)

    gun control legislation. One study estimated that more than 4 500 lives were saved across five SA cities from 2001 to 2005.[5] Pro-gun interest groups seeking to promote gun ownership and diffusion have attacked these findings, suggesting that stricter gun control was only enacted in 2004 following the publication of ...

  8. Gun Sales. Firearm Facts.

    Science.gov (United States)

    Duker, Laurie, Ed.

    Minimal federal regulations on firearm sales have facilitated the proliferation of guns, gun owners, and gun dealers in the United States. This fact sheet offers data on the growing number of firearm dealers, the relative ease of obtaining and keeping a license to sell guns from the Federal Bureau of Alcohol, Tobacco, and Firearms, the lack of…

  9. Spectroscopic and corpuscular analysis of laser-produced carbon plasma

    International Nuclear Information System (INIS)

    Czarnecka, A.; Kubkowska, M.; Kowalska-Strzeciwilk, E.; Parys, P.; Sadowski, M.J.; Skladnik-Sadowska, E.; Malinowski, K.; Kwiatkowski, R.; Ladygina, M.

    2013-01-01

    The paper describes spectroscopic and corpuscular measurements of laser-produced carbon plasma, which was created at surfaces of three targets made of CFC of the Snecma-N11 type with different crystallographic orientations. In order to irradiate the investigated samples the use was made of a Nd:YAG laser. Experiments were performed in a vacuum chamber under the initial pressure equal to 5.10-5 mbar. A Mechelle 900 optical spectrometer equipped with a CCD detector was used to record spectra emitted from the produced carbon-plasma. The recorded optical spectra showed distinct carbon lines ranging from CI to CIV. Basing on the Stark broadening of the CII 426.7 nm line it was possible to estimate the electron density of plasma from each investigated sample. Corpuscular measurements of the emitted ions were carried out by means of an electrostatic ion-energy analyzer and ion collector.

  10. The formation of ethane from carbon dioxide under cold plasma

    International Nuclear Information System (INIS)

    Zhang Xiuling; Zhang Lin; Dai Bin; Gong Weimin; Liu Changhou

    2001-01-01

    Pulsed-corona plasma has been used as a new method for ethane dehydrogenation at low temperature and normal pressure using carbon dioxide as an oxidant. The effect of carbon dioxide content in the feed, power input, and flow rate of the reactants on the ethane dehydrogenation has been investigated. The experimental results show that the conversion of ethane increases with the increasing in the amount of carbon dioxide in the feed. The yield of ethylene and acetylene decreases with the increasing in the yield of carbon monoxide, indicating that the increased carbon dioxide leads to the part of ethylene and acetylene being oxidized to carbon monoxide. Power input is primarily an electrical parameter in pulsed-corona plasma, which plays an important role in reactant conversion and product formation. When the power input reaches 16 W, ethane conversion is 41.0% and carbon dioxide conversion is 26.3%. The total yield of ethylene and acetylene is 15.6%. The reduced flow rate of feed improves the conversion of ethane, carbon dioxide and the yield of acetylene, and induces carbon deposit as well

  11. Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, David R. [PPPL; Tanaka, K. [NIFS; Nunami, M. [NIFS; Watanabe, T-H. [Nagoya University; Sugama, H. [NIFS; Yoshinuma, M. [NIFS; Suzuki, Y. [NIFS; Goto, M. [NIFS; Morita, S. [NIFS; Wieland, B. [NIFS; Yamada, I. [NIFS; Yashura, R. [NIFS; Akiyama, T. [NIFS; Pablant, Novimir A. [PPPL

    2014-04-01

    Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-ITB and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient (ITG) modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    An electric-arc plasma installation operated in the hidden anode arrangement is constructed and used for the preparation of carbon nanostructures. A contracted plasma arc generated by a plasma torch using an inert gas is used as heat source. The average mass temperature of arc is higher than 10 4 K, while its power density, which is directly transferred onto the electrode (anode), is ∼ 2 kW/mm 2 . The anode contact area formed on the electrode moves against the arc by way of shifting the electrode and is hidden completely in the interior of plasma gas stream moving towards it. As a result of both the direct plasma attack and the opposite movement of streams in the hidden anode contact area, a temperature higher than 6000 K is reached. Thus, intensive vaporization takes place, which forms a saturated plasma-gas-aerosol phase of the initial material of electrode (anode). This gas phase is mixed in and carried by the plasma stream. Over that mixed plasma stream, a controlled process of quenching (fixation) is carried out by twisted turbulent fluid streams. After the fixation, the resultant carbon nano-structures are caught by a filter and collected in a bunker.

  13. Experimental study of matrix carbon field-emission cathodes and computer aided design of electron guns for microwave power devices, exploring these cathodes

    International Nuclear Information System (INIS)

    Grigoriev, Y.A.; Petrosyan, A.I.; Penzyakov, V.V.; Pimenov, V.G.; Rogovin, V.I.; Shesterkin, V.I.; Kudryashov, V.P.; Semyonov, V.C.

    1997-01-01

    The experimental study of matrix carbon field-emission cathodes (MCFECs), which has led to the stable operation of the cathodes with current emission values up to 100 mA, is described. A method of computer aided design of TWT electron guns (EGs) with MCFEC, based on the results of the MCFEC emission experimental study, is presented. The experimental MCFEC emission characteristics are used to define the field gain coefficient K and the cathode effective emission area S eff . The EG program computes the electric field upon the MCFEC surface, multiplies it by the K value and uses the Fowler Nordheim law and the S eff value to calculate the MCFEC current; the electron trajectories are computed as well. copyright 1997 American Vacuum Society

  14. Application of a magnetized coaxial plasma gun for formation of a high-beta field-reversed configuration

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, T. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Kiguchi, T. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Asai, T. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan)]. E-mail: asai@phys.cst.nihon-u.ac.jp; Takahashi, T. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Matsuzawa, Y. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Okano, T. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Nogi, Y. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan)

    2006-11-15

    We have tested a field-reversed configuration (FRC) formation with a spheromak injection for the first time. In this method, initial pre-ionized plasma is injected as a magnetized spheromak-like plasmoid into the discharge chamber prior to main field reversal. The FRC plasma with an electron density of 1.3 x 10{sup 21} m{sup -3}, a separatrix radius of 0.04 m and a plasma length of 0.8 m was produced successfully in initial background plasma of about 1.6 x 10{sup 19} m{sup -3} by spheromak injection. The density is about one third of the conventional formed by the z-ionized method.

  15. Transient effects in beam-plasma interactions in a space simulation chamber stimulated by a fast pulse electron gun

    Science.gov (United States)

    Raitt, W. J.; Banks, P. M.; Denig, W. F.; Anderson, H. R.

    1982-01-01

    Interest in the interaction of electron beams with plasma generated by ionization caused by the primary electron beam was stimulated by the need to develop special vacuum tubes to operate in the kMHz frequency region. The experiments of Getty and Smullin (1963) indicated that the interaction of an energetic electron beam with its self-produced plasma resulted in the emission of wave energy over a wide range of frequencies associated with cyclotron and longitudinal plasma instabilities. This enhanced the thermal plasma density in the vicinity of the beam, and the term Beam-Plasma Discharge (BPD) was employed to described this phenomenon. The present investigation is concerned with some of the transient phenomena associated with wave emission during the beam switch-on and switch-off periods. Results are presented on the changes in electron energy spectra on a time scale of tens of milliseconds following beam switch-on. The results are discussed in terms of the beam plasma discharge phenomenon.

  16. Transient effects in beam-plasma interactions in a space simulation chamber stimulated by a fast pulse electron gun

    International Nuclear Information System (INIS)

    Raitt, W.J.; Banks, P.M.

    1982-01-01

    Interest in the interaction of electron beams with plasma generated by ionization caused by the primary electron beam was stimulated by the need to develop special vacuum tubes to operate in the kMHz frequency region. The experiments of Getty and Smullin (1963) indicated that the interaction of an energetic electron beam with its self-produced plasma resulted in the emission of wave energy over a wide range of frequencies associated with cyclotron and longitudinal plasma instabilities. This enhanced the thermal plasma density in the vicinity of the beam, and the term Beam-Plasma Discharge (BPD) was employed to described this phenomenon. The present investigation is concerned with some of the transient phenomena associated with wave emission during the beam switch-on and switch-off periods. Results are presented on the changes in electron energy spectra on a time scale of tens of milliseconds following beam switch-on. The results are discussed in terms of the beam plasma discharge phenomenon. 5 references

  17. Plasma Treated Active Carbon for Capacitive Deionization of Saline Water

    Directory of Open Access Journals (Sweden)

    Aiping Zeng

    2017-01-01

    Full Text Available The plasma treatment on commercial active carbon (AC was carried out in a capacitively coupled plasma system using Ar + 10% O2 at pressure of 4.0 Torr. The RF plasma power ranged from 50 W to 100 W and the processing time was 10 min. The carbon film electrode was fabricated by electrophoretic deposition. Micro-Raman spectroscopy revealed the highly increased disorder of sp2 C lattice for the AC treated at 75 W. An electrosorption capacity of 6.15 mg/g was recorded for the carbon treated at 75 W in a 0.1 mM NaCl solution when 1.5 V was applied for 5 hours, while the capacity of the untreated AC was 1.01 mg/g. The plasma treatment led to 5.09 times increase in the absorption capacity. The jump of electrosorption capacity by plasma treatment was consistent with the Raman spectra and electrochemical double layer capacitance. This work demonstrated that plasma treatment was a potentially efficient approach to activating biochar to serve as electrode material for capacitive deionization (CDI.

  18. Irradiation-induced structure and property changes in tokamak plasma-facing, carbon-carbon composites

    International Nuclear Information System (INIS)

    Burchell, T.D.

    1994-01-01

    Carbon-carbon composites are an attractive choice for fusion reactor plasma-facing components because of their low atomic number, superior thermal shock resistance, and low neutron activation. Next generation plasma fusion reactors, such as the International Thermonuclear Experimental Reactor (ITER), will require advanced carbon-carbon composite materials possessing high thermal conductivity to manage the anticipated severe heat loads. Moreover, ignition machines such as ITER will produce large neutron fluxes. Consequently, the influence of neutron damage on the structure and properties of carbon-carbon composite materials must be evaluated. Data from two irradiation experiments are reported and discussed here. Carbon-carbon composite materials were irradiated in target capsules in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). A peak damage dose of 4.7 displacements per atom (dpa) at 600 degree C was attained. The carbon materials irradiated included uni-directional, two-directional, and three-directional carbon-carbon composites. Dimensional changes are reported for the composite materials and are related to single crystal dimensional changes through fiber and composite structural models. Moreover, the irradiation-induced dimensional changes are reported and discussed in terms of their architecture, fiber type, and graphitization temperature. The effect of neutron irradiation on thermal conductivity of two three-directional, carbon-carbon composites is reported and the recovery of thermal conductivity due to thermal annealing is discussed

  19. Nonmetallic inclusions in carbon steel smelted in plasma furnace

    Energy Technology Data Exchange (ETDEWEB)

    Shengelaya, I B; Kostyakov, V N; Nodiy, T K; Imerlishvili, V G; Gavisiani, A G [AN Gruzinskoj SSR, Tbilisi. Inst. Metallurgii

    1979-01-01

    A complex investigation on nonmetallic inclusions in carbon cast iron, smelted in plasma furnace in argon atmosphere and cast partly in the air and partly in argon atmosphere, has been carried out. As compared to open-hearth furnace carbon steel, the test metal was found to contain more oxide inclusions and nitrides; besides, in chromium-containing metal, chromium nitrides form the larger part of nitrides.

  20. Quantitative analysis of carbon radiation in edge plasmas of LHD

    International Nuclear Information System (INIS)

    Dong, C.F.; Morita, S.; Oishi, T.; Goto, M.; Murakami, I.; Wang, E.R.; Huang, X.L.

    2013-01-01

    It is of interest to compare the carbon radiation loss between LHD and tokamaks. Since the radiation from C"3"+ is much smaller than that from C"5"+, it is also interesting to examine the difference in the detached plasma. In addition, it is important to study quantitatively the radiation from each ionization stage of carbon which is uniquely the dominant impurity in most tokamaks and LHD. (J.P.N.)

  1. Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

    Science.gov (United States)

    Uchida, Masaki; Natsume, Hideshi; Kobayashi, Daisuke; Sugibayashi, Kenji; Morimoto, Yasunori

    2002-05-01

    We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

  2. Surface plasma functionalization influences macrophage behavior on carbon nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vizireanu, Sorin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Stancu, Claudia Elena [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Luculescu, Catalin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Dinescu, Gheorghe [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania)

    2015-03-01

    The surfaces of carbon nanowall samples as scaffolds for tissue engineering applications were treated with oxygen or nitrogen plasma to improve their wettability and to functionalize their surfaces with different functional groups. X-ray photoelectron spectroscopy and water contact angle results illustrated the effective conversion of the carbon nanowall surfaces from hydrophobic to hydrophilic and the incorporation of various amounts of carbon, oxygen and nitrogen functional groups during the treatments. The early inflammatory responses elicited by un-treated and modified carbon nanowall surfaces were investigated by quantifying tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha released by attached RAW 264.7 macrophage cells. Scanning electron microscopy and fluorescence studies were employed to investigate the changes in macrophage morphology and adhesive properties, while MTT assay was used to quantify cell proliferation. All samples sustained macrophage adhesion and growth. In addition, nitrogen plasma treatment was more beneficial for cell adhesion in comparison with un-modified carbon nanowall surfaces. Instead, oxygen plasma functionalization led to increased macrophage adhesion and spreading suggesting a more activated phenotype, confirmed by elevated cytokine release. Thus, our findings showed that the chemical surface alterations which occur as a result of plasma treatment, independent of surface wettability, affect macrophage response in vitro. - Highlights: • N{sub 2} and O{sub 2} plasma treatments alter the CNW surface chemistry and wettability. • Cells seeded on CNW scaffolds are viable and metabolically active. • Surface functional groups, independent of surface wettability, affect cell response. • O{sub 2} plasma treatment of CNW leads to a more activated macrophage phenotype.

  3. Evaporation of carbon using electrons of a high density plasma

    International Nuclear Information System (INIS)

    Muhl, S.; Camps, E.; Escobar A, L.; Garcia E, J.L.; Olea, O.

    1999-01-01

    The high density plasmas are used frequently in the preparation of thin films or surface modification, for example to nitridation. In these processes, are used mainly the ions and the neutrals which compose the plasma. However, the electrons present in the plasma are not used, except in the case of chemical reactions induced by collisions, although the electron bombardment usually get hot the work piece. Through the adequate polarization of a conductor material, it is possible to extract electrons from a high density plasma at low pressure, that could be gotten the evaporation of this material. As result of the interaction between the plasma and the electron flux with the vapor produced, this last will be ionized. In this work, it is reported the use of this novelty arrangement to prepare carbon thin films using a high density argon plasma and a high purity graphite bar as material to evaporate. It has been used substrates outside plasma and immersed in the plasma. Also it has been reported the plasma characteristics (temperature and electron density, energy and ions flux), parameters of the deposit process (deposit rate and ion/neutral rate) as well as the properties of the films obtained (IR absorption spectra and UV/Vis, elemental analysis, hardness and refractive index. (Author)

  4. Diagnosis of high-intensity pulsed heavy ion beam generated by a novel magnetically insulated diode with gas puff plasma gun.

    Science.gov (United States)

    Ito, H; Miyake, H; Masugata, K

    2008-10-01

    Intense pulsed heavy ion beam is expected to be applied to materials processing including surface modification and ion implantation. For those applications, it is very important to generate high-purity ion beams with various ion species. For this purpose, we have developed a new type of a magnetically insulated ion diode with an active ion source of a gas puff plasma gun. When the ion diode was operated at a diode voltage of about 190 kV, a diode current of about 15 kA, and a pulse duration of about 100 ns, the ion beam with an ion current density of 54 A/cm(2) was obtained at 50 mm downstream from the anode. By evaluating the ion species and the energy spectrum of the ion beam via a Thomson parabola spectrometer, it was confirmed that the ion beam consists of nitrogen ions (N(+) and N(2+)) of energy of 100-400 keV and the proton impurities of energy of 90-200 keV. The purity of the beam was evaluated to be 94%. The high-purity pulsed nitrogen ion beam was successfully obtained by the developed ion diode system.

  5. Carbon dust formation in a cold plasma from cathode sputtering

    International Nuclear Information System (INIS)

    Arnas, C.; Mouberi, A.; Hassouni, K.; Michau, A.; Lombardi, G.; Bonnin, X.; Benedic, F.; Pegourie, B.

    2009-01-01

    Nanoparticles are produced in argon glow plasmas where carbon is introduced by sputtering of a graphite cathode. A scaling law of growth is reported on as a function of the discharge time. Two successive stages of growth of concomitant agglomeration and carbon deposition are observed, followed by a final stage of growth by carbon deposition. A model of formation of molecular precursors by coagulation of neutral clusters on the one hand and of neutral-negative clusters on the other hand is presented, based on formation enthalpy and cluster geometry.

  6. Carbon dust formation in a cold plasma from cathode sputtering

    Science.gov (United States)

    Arnas, C.; Mouberi, A.; Hassouni, K.; Michau, A.; Lombardi, G.; Bonnin, X.; Bénédic, F.; Pégourié, B.

    2009-06-01

    Nanoparticles are produced in argon glow plasmas where carbon is introduced by sputtering of a graphite cathode. A scaling law of growth is reported on as a function of the discharge time. Two successive stages of growth of concomitant agglomeration and carbon deposition are observed, followed by a final stage of growth by carbon deposition. A model of formation of molecular precursors by coagulation of neutral clusters on the one hand and of neutral-negative clusters on the other hand is presented, based on formation enthalpy and cluster geometry.

  7. Plasma excitations in a single-walled carbon nanotube

    Indian Academy of Sciences (India)

    The effect of different uniform transverse external magnetic fields in plasma frequency when propagated parallel to the surface of the single-walled metallic carbon nanotubes is studied. The classical electrodynamics as well as Maxwell's equations are used in the calculations. Equations are developed for both short- and ...

  8. Microwave plasma deposition of diamond like carbon coatings

    Indian Academy of Sciences (India)

    Abstract. The promising applications of the microwave plasmas have been appearing in the fields of chemical processes and semiconductor manufacturing. Applications include surface deposition of all types including diamond/diamond like carbon (DLC) coatings, etching of semiconductors, promotion of organic reactions, ...

  9. European development of carbon armoured plasma facing components for ITER

    International Nuclear Information System (INIS)

    Merola, M.; Vieider, G.; Wu, C.; Schedler, B.; Chappuis, P.; Escourbiac, F.; Schlosser, J.; Duwe, R.; Roedig, M.; Febvre, M.; Grattarola, M.; Tahtinen, S.; Vesprini, R.

    2001-01-01

    After a brief description of the rationale of the material and geometry selection for each carbon armoured plasma facing components, this paper describes the European development of the two basic geometries, namely the monoblock and the flat tile. An overview of the non-destructive inspection techniques specifically developed for these components is also presented. (orig.)

  10. Plasma-induced field emission and plasma expansion of carbon nanotube cathodes

    International Nuclear Information System (INIS)

    Liao Qingliang; Zhang Yue; Qi Junjie; Huang Yunhua; Xia Liansheng; Gao Zhanjun; Gu Yousong

    2007-01-01

    High intensity electron emission cathodes based on carbon nanotube films have been successfully fabricated. An investigation of the explosive field emission properties of the carbon nanotube cathode in a double-pulse mode was presented and a high emission current density of 245 A cm -2 was obtained. The formation of the cathode plasma layer was proved and the production process of the electron beams from the cathode was explained. The time and space resolution of the electron beams flow from the cathode was investigated. The plasma expanded at a velocity of ∼8.17 cm μs -1 towards the anode and influenced on the intensity and distribution of electron beams obviously. The formation of cathode plasma had no preferential position and the local enhancement of electron beams was random. This carbon nanotube cathode appears to be suitable for high-power microwave device applications

  11. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  12. Synthesis of aluminum nitride films by plasma immersion ion implantation-deposition using hybrid gas-metal cathodic arc gun

    International Nuclear Information System (INIS)

    Shen Liru; Fu, Ricky K.Y.; Chu, Paul K.

    2004-01-01

    Aluminum nitride (AlN) is of interest in the industry because of its excellent electronic, optical, acoustic, thermal, and mechanical properties. In this work, aluminum nitride films are deposited on silicon wafers (100) by metal plasma immersion ion implantation and deposition (PIIID) using a modified hybrid gas-metal cathodic arc plasma source and with no intentional heating to the substrate. The mixed metal and gaseous plasma is generated by feeding the gas into the arc discharge region. The deposition rate is found to mainly depend on the Al ion flux from the cathodic arc source and is only slightly affected by the N 2 flow rate. The AlN films fabricated by this method exhibit a cubic crystalline microstructure with stable and low internal stress. The surface of the AlN films is quite smooth with the surface roughness on the order of 1/2 nm as determined by atomic force microscopy, homogeneous, and continuous, and the dense granular microstructures give rise to good adhesion with the substrate. The N to Al ratio increases with the bias voltage applied to the substrates. A fairly large amount of O originating from the residual vacuum is found in the samples with low N:Al ratios, but a high bias reduces the oxygen concentration. The compositions, microstructures and crystal states of the deposited films are quite stable and remain unchanged after annealing at 800 deg. C for 1 h. Our hybrid gas-metal source cathodic arc source delivers better AlN thin films than conventional PIIID employing dual plasmas

  13. Conference on electromagnetic guns and launchers, 1980

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    Proceedings includes 31 papers dealing with the physical principles and engineering technology associated with the development of electromagnetic propulsion, with emphasis on its use for guns, launchers as well as other military equipment. Topics covered include: rail guns, projectiles, mass accelerators, electric motors and generators, nuclear reactors, superconducting devices, plasma acceleration and confinement, traveling magnetic waves, aerospace propulsion, space shuttles, homopolar generators, fusion reactors, tokamaks, impact fusion, and electric power generation. All papers are abstracted and indexed separately

  14. Enhanced field emission from carbon nanotubes by hydrogen plasma treatment

    International Nuclear Information System (INIS)

    Zhi, C.Y.; Bai, X.D.; Wang, E.G.

    2002-01-01

    The field emission capability of the carbon nanotubes (CNTs) has been improved by hydrogen plasma treatment, and the enhanced emission mechanism has been studied systematically using Fourier-transform infrared spectroscopy, Raman, and transmission electron microscopy. The hydrogen concentration in the samples increases with increasing plasma treatment duration. A C δ- -H δ+ dipole layer may form on CNTs' surface and a high density of defects results from the plasma treatment, which is likely to make the external surface of CNTs more active to emit electrons after treatment. In addition, the sharp edge of CNTs' top, after removal of the catalyst particles, may increase the local electronic field more effectively. The present study suggests that hydrogen plasma treatment is a useful method for improving the field electron emission property of CNTs

  15. ORELA electron guns

    International Nuclear Information System (INIS)

    Christian, O.W.; Lewis, T.A.

    1981-09-01

    The most recent information concerning the production and performance of ORELA electron guns is presented. Included are descriptions of procedures for gun fabrication, cathode conditioning and high voltage processing. Highlights of the performance characteristics are also included

  16. Electron gun for SSRF

    International Nuclear Information System (INIS)

    Sheng Shugang; Lin Guoqiang; Gu Qiang; Li Deming

    2003-01-01

    A 100 kV triode-electron-gun has been designed and manufactured for the Linac of Shanghai Synchrotron Radiation Facility (SSRF). In this paper the performance of the gun and some key components are described

  17. Evaluation of surface fractal dimension of carbon for plasma-facing material damaged by hydrogen plasma

    International Nuclear Information System (INIS)

    Nishino, Nobuhiro

    1997-01-01

    The surface structure of the plasma facing materials (PFM) changes due to plasma-surface interaction in a nuclear fusion reactor. Usually B 4 C coated graphite block are used as PFM. In this report, the surface fractal was applied to study the surface structure of plasma-damaged PFM carbon. A convenient flow-type adsorption apparatus was developed to evaluate the surface fractal dimension of materials. Four branched alkanol molecules with different apparent areas were used as the probe adsorbates. The samples used here were B 4 C coated isotopic graphite which were subjected to hydrogen plasma for various periods of exposure. The monolayer capacities of these samples for alkanols were determined by applying BET theory. The surface fractal dimension was calculated using the monolayer capacities and molecular areas for probe molecules and was found to increase from 2 to 3 with the plasma exposure time. (author)

  18. Guns and Violence. Current Controversies.

    Science.gov (United States)

    Kim, Henny H., Ed.

    This book focuses on gun violence and gun control, presenting both sides of arguments about firearms ownership and gun control. Each of five chapters poses a question about gun control and provides answers for both sides of the question. The following essays are included: (1) "Gun Violence Is Becoming an Epidemic" (Bob Herbert); (2) "Gun Violence…

  19. Comparative Analysis of Carbon Plasma in Arc and RF Reactors

    International Nuclear Information System (INIS)

    Todorovic-Markovic, B.; Markovic, Z.; Mohai, I.; Szepvolgyi, J.

    2004-01-01

    Results on studies of molecular spectra emitted in the initial stages of fullerene formation during the processing of graphite powder in induction RF reactor and evaporation of graphite electrodes in arc reactor are presented in this paper. It was found that C2 radicals were dominant molecular species in both plasmas. C2 radicals have an important role in the process of fullerene synthesis. The rotational-vibrational temperatures of C2 and CN species were calculated by fitting the experimental spectra to the simulated ones. The results of optical emission study of C2 radicals generated in carbon arc plasma have shown that rotational temperature of C2 species depends on carbon concentration and current intensity significantly. The optical emission study of induction RF plasma and SEM analysis of graphite powder before and after plasma treatment have shown that evaporation of the processed graphite powder depends on feed rate and composition of gas phase significantly. Based on the obtained results, it was concluded that in the plasma region CN radicals could be formed by the reaction of C2 species with atomic nitrogen at smaller loads. At larger feed rate of graphite powder, CN species were produced by surface reaction of the hot carbon particles with nitrogen atoms. The presence of nitrogen in induction RF plasma reduces the fullerene yield significantly. The fullerene yield obtained in two different reactors was: 13% in arc reactor and 4.1% in induction RF reactor. However, the fullerene production rate was higher in induction RF reactor-6.4 g/h versus 1.7 g/h in arc reactor

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

    Science.gov (United States)

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

    2017-02-23

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

  1. Electrocatalytic reduction of carbon dioxide under plasma DBD process

    International Nuclear Information System (INIS)

    Amouroux, Jacques; Cavadias, Simeon

    2017-01-01

    Carbon dioxide can be converted, by reaction with hydrogen, into fine chemicals and liquid fuels such as methanol and DME. Methane production by the Sabatier reaction opens the way of carbon recycling for a circular economy of carbon resources. The catalytic process of methanation of carbon dioxide produces two molecules of water as a by-product. A current limitation in the CO 2 methanation is the ageing of catalysts, mainly due to water adsorption during the process. To avoid this adsorption, the process is operated at high temperature (300 °C–400 °C), leading to carbon deposition on the catalyst and its deactivation. To overcome this problem, a methanation plasma-catalytic process has been developed, which achieves high CO 2 conversion rate (80%), and a selectivity close to 100%, working from room temperature to 150 °C, instead of 300 °C–400 °C for the thermal catalytic process. The main characteristics of this process are high-voltage pulses of few nanoseconds duration, activating the adsorption of CO 2 in bent configuration and the polarization of the catalyst. The key step in this process is the desorption of water from the polarized catalyst. The high CO 2 conversion at low temperature could be explained by the creation of a plasma inside the nanopores of the catalyst. (paper)

  2. Electrocatalytic reduction of carbon dioxide under plasma DBD process

    Science.gov (United States)

    Amouroux, Jacques; Cavadias, Simeon

    2017-11-01

    Carbon dioxide can be converted, by reaction with hydrogen, into fine chemicals and liquid fuels such as methanol and DME. Methane production by the Sabatier reaction opens the way of carbon recycling for a circular economy of carbon resources. The catalytic process of methanation of carbon dioxide produces two molecules of water as a by-product. A current limitation in the CO2 methanation is the ageing of catalysts, mainly due to water adsorption during the process. To avoid this adsorption, the process is operated at high temperature (300 °C-400 °C), leading to carbon deposition on the catalyst and its deactivation. To overcome this problem, a methanation plasma-catalytic process has been developed, which achieves high CO2 conversion rate (80%), and a selectivity close to 100%, working from room temperature to 150 °C, instead of 300 °C-400 °C for the thermal catalytic process. The main characteristics of this process are high-voltage pulses of few nanoseconds duration, activating the adsorption of CO2 in bent configuration and the polarization of the catalyst. The key step in this process is the desorption of water from the polarized catalyst. The high CO2 conversion at low temperature could be explained by the creation of a plasma inside the nanopores of the catalyst.

  3. Laser-generated plasma by carbon nanoparticles embedded into polyethylene

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Ceccio, G.; Cutroneo, Mariapompea

    2016-01-01

    Roč. 375, MAY (2016), s. 93-99 ISSN 0168-583X R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk(CZ) LM2011019 Institutional support: RVO:61389005 Keywords : carbon nanoparticles * laser-generated plasma * Time-of-flight measurements * advanced targets Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

  4. Boron erosion and carbon deposition due to simultaneous bombardment with deuterium and carbon ions in plasmas

    International Nuclear Information System (INIS)

    Ohya, K.; Kawata, J.; Wienhold, P.; Karduck, P.; Rubel, M.; Seggern, J. von

    1999-01-01

    Erosion of boron out of a thin film exposed to deuterium edge plasmas and the simultaneous carbon deposition have been investigated in the tokamak TEXTOR-94 and simulated by means of a dynamic Monte Carlo code. The calculated results are compared with some observations (colorimetry, spectroscopy and AES) during and after the exposures. The implantation of carbon impurities strongly changes the effective boron sputtering yield of the film, which results into a lowering of the film erosion and a formation of thick carbon deposits. A strong decrease in the observed BII line emission around a surface location far from the plasma edge can be explained by a carbon deposition on the film. The calculated carbon depth profiles in the film, depending on the distance of the exposed surface from the plasma edge, are in reasonable agreement with measurements by AES after the exposures. Although simultaneous surface erosion and carbon deposition can be simulated, the calculated erosion rate is larger, by a factor of 2, than the observations by colorimetry at the early stage of the exposure

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

    Directory of Open Access Journals (Sweden)

    Grzegorz Raniszewski

    2017-02-01

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

  6. Gun Theft and Crime.

    Science.gov (United States)

    Cook, Philip J

    2018-06-01

    Some law enforcement officials and other observers have asserted that theft is the primary source of guns to crime. In fact, the role of theft in supplying the guns used in robbery, assault, and murder is unknown, and current evidence provides little guidance about whether an effective program to reduce gun theft would reduce gun violence. The current article analyzes publicly available national data on gun theft together with a unique data set for Chicago. The results tend to support a conclusion that stolen guns play only a minor role in crime. First, publicly available data are used to calculate that thefts are only about 1% of all gun transactions nationwide. Second, an analysis of original data from Chicago demonstrates that less than 3% of crime guns recovered by the police have been reported stolen to the Chicago Police Department (CPD). If a gun is reported stolen, there is a 20% chance that it will be recovered, usually in conjunction with an arrest for illegal carrying. Less than half of those picked up with a stolen gun have a criminal record that includes violent offenses. Third, results from surveys of convicted criminals, both nationally and in Chicago, suggest that it is rare for respondents to have stolen the gun used in their most recent crime. The data on which these results are based have various shortcomings. A research agenda is proposed that would provide more certainty about the role of theft.

  7. Description of the plasma diagnostics package (PDP) for the OSS-1 Shuttle mission and JSC plasma chamber test in conjunction with the fast pulse electron gun (FPEG)

    Science.gov (United States)

    Shawhan, S. D.

    1982-01-01

    The objectives, equipment, and techniques for the plasma diagnostics package (PDP) carried by the OSS-1 instrument payload of the STS-4 and scheduled for the Spacelab-2 mission are described. The goals of the first flight were to examine the Orbiter-magnetoplasma interactions by measuring the electric and magnetic field strengths, the ionized particle wakes, and the generated waves. The RMS was employed to lift the unit out of the bay in order to allow characterization of the fields, EM interference, and plasma contamination within 15 m of the Orbiter. The PDP will also be used to examine plasma depletion, chemical reaction rates, waves, and energized plasma produced by firing of the Orbiter thrusters. Operation of the PDP was carried out in the NASA Space Environment Simulation Laboratory test chamber, where the PDP was used to assay the fields, fluxes, wave amplitudes, and particle energy spectra. The PDP instrumentation is also capable of detecting thermal ions, thermal electrons suprathermal particles, VHF/UHF EMI levels, and the S-band field strength.

  8. Whose guns are stolen? The epidemiology of Gun theft victims.

    Science.gov (United States)

    Hemenway, David; Azrael, Deborah; Miller, Matthew

    2017-12-01

    Gun theft is an important source of guns used by criminals. Yet no empirical work has focused on the characteristics of gun owners that distinguish those who have had their guns stolen from those who have not. In this study, we examine the demographics and behavioral characteristics of gun owners who report having had a gun stolen. Data come from a nationally representative probability-based online survey conducted in April 2015, with a linked follow-up survey in November 2015 that asked gun owners about any theft of their guns in the past 5 years. Of 1,604 gun-owning respondents, 2.4% (95% CI 1.6,3.6) reported that one or more guns had been stolen, with a mean number of guns stolen per theft of 1.5 (95% CI 1.0,2.0]. Risk factors for having a gun stolen were owning 6 or more guns, owning guns for protection, carrying a gun in the past month, storing guns unsafely, and living in the South region of the United States. The South accounts for 37% of US households, 43% of gun owners, and two-thirds of all gun thefts. We estimate that there are approximately 250,000 gun theft incidents per year, with about 380,000 guns stolen. We find that certain types of gun owners-who own many guns, who carry guns, and who do not store guns safely-are at higher risk to have their guns stolen. Tracing data show that states in the South are exporters of crime guns used in other states. Our survey results find that the majority of guns stolen in the US come from the South.

  9. Filtration of Carbon Particulate Emissions from a Plasma Pyrolysis Assembly

    Science.gov (United States)

    Agui, Juan H.; Green, Robert; Vijayakumar, R.; Berger, Gordon; Greenwood, Zach; Abney, Morgan; Peterson, Elspeth

    2016-01-01

    NASA is investigating plasma pyrolysis as a candidate technology that will enable the recovery of hydrogen from the methane produced by the ISS Sabatier Reactor. The Plasma Pyrolysis Assembly (PPA) is the current prototype of this technology which converts the methane product from the Carbon Dioxide Reduction Assembly (CRA) to acetylene and hydrogen with 90% or greater conversion efficiency. A small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. We discuss developmental work on several options for filtering out the carbon particulate emissions from the PPA exit gas stream. The filtration technologies and concepts investigated range from fibrous media to monolithic ceramic and sintered metal media. This paper describes the different developed filter prototypes and characterizes their performance from integrated testing at the Environmental Chamber (E-Chamber) at MSFC. In addition, characterization data on the generated carbon particulates, that help to define filter requirements, are also presented.

  10. Conditionings for boron-carbon plasma facing wall

    International Nuclear Information System (INIS)

    Hino, Tomoaki; Yamauchi, Yuji; Yamashina, Toshiro

    1994-01-01

    For plasma facing material with components of boron and carbon, the method of conditionings due to He discharge cleaning and baking is considered. The conditioning time required to suppress the hydrogen recycling is discussed. It is shown that the hydrogen trapped by the boron can be relatively easily removed only by the baking at 300degC or only by He discharge cleaning with current density of 0.1 mA/cm 2 . It is not easy to remove the hydrogen trapped by the carbon by the baking since the temperature required becomes 500degC. The current density required also becomes high, 1 mA/cm 2 , for the reduction of the hydrogen trapped by the carbon. (author)

  11. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    Science.gov (United States)

    Cassell, Alan M.; Li, J.; Ye, Q.; Koehne, J.; Chen, H.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical biosensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  12. Role of carbon atoms in the remote plasma deposition of hydrogenated amorphous carbon

    International Nuclear Information System (INIS)

    Benedikt, J.; Wisse, M.; Woen, R.V.; Engeln, R.; Sanden, M.C.M. van de

    2003-01-01

    The aim of this article is to determine the role of carbon atoms in the growth of hydrogenated amorphous carbon (a-C:H) films by means of an argon/acetylene expanding thermal plasma. Cavity ring down absorption spectroscopy is used to detect metastable carbon atoms by probing the 1s 2 2s 2 2p 3s 1 P 1 2 2s 2 2p 2 1 S 0 electronic transition. In addition to absorption measurements, the emission of the same transition is monitored by means of optical emission spectroscopy. These two measurements provide information about the local production of the C atoms and about their reactivity in the gas phase. It will be shown that under growth conditions in an Ar/C 2 H 2 expanding thermal plasma, the metastable carbon density is also representative for the ground state carbon density. From obtained results it is concluded that the carbon atoms react rapidly with acetylene in the gas phase and therefore their contribution to the growth of hard diamond-like a-C:H films can be neglected. Only at low acetylene flows, the condition when soft polymer-like films are deposited, carbon atoms are detected close to the substrate and can possibly contribute to the film growth

  13. Tungsten and carbon surface change under high dose plasma exposure

    International Nuclear Information System (INIS)

    Martynenko, Y.V.; Khripunov, B.I.; Petrov, V.B.

    2009-01-01

    Study of surface composition dynamics has been made on the LENTA linear plasma simulator. Experiments have been made on tungsten and carbon materials subjected to steady-state plasma exposure. The achieved ion doses on the surface were 10 21 ion cm -2 . WL 10 tungsten containing 1% of La2O3 oxide and titanium-doped graphite RG-T were studied. The following experimental conditions were varied in these experiments: energy of ions, surface temperature, working gas. Irradiations of tungsten WL 10 were executed in deuterium plasma at low ion energies (about 20 eV) and at 200 eV for temperatures below 340 K. Graphite RG-T was exposed at 1300 K. Elevated surface temperature (about 1050K) was also characteristic of experiments on tungsten sample under nitrogen plasma impact (simulated inter-ELMs condition). Surface microstructure modification has been observed and surface composition changes were found on the materials showing influence of high dose plasma irradiations on element redistribution in the near surface layers. (author)

  14. Surface martensitization of Carbon steel using Arc Plasma Sintering

    Science.gov (United States)

    Wahyudi, Haris; Dimyati, Arbi; Sebayang, Darwin

    2018-03-01

    In this paper new technology of surface structure modification of steel by short plasma exposure in Arc Plasma Sintering (APS) device is presented. APS is an apparatus working based on plasma generated by DC pulsed current originally used for synthesizing materials via sintering and melting. Plasma exposure in APS was applied into the specimens for 1 and 3 seconds which generate temperature approximately about 1300-1500°C. The SUP9, pearlitic carbon steel samples were used. The hardness, hardening depth and microstructure of the specimens have been investigated by Vickers micro hardness test and Scanning Electron Microscopy (SEM) supported by Energy Dispersive X-Ray Spectroscopy (EDX). The results have showed that the mechanical property was significantly improved due to the formation of single martensitic structures as identified by SEM. The hardness of treated surface evaluated by Vickers hardness test showed significant improvement nearly three time from 190 VHN before to 524 VHN after treatment. Furthermore, EDX confirmed that the formation of martensite layer occurred without altering its composition. The APS also produced uniform hardened layer up to 250 μm. The experiment has demonstrated that arc plasma process was successfully improved the mechanical properties of steel in relatively very short time.

  15. Thermodynamic diagrams for high temperature plasmas of air, air-carbon, carbon-hydrogen mixtures, and argon

    CERN Document Server

    Kroepelin, H; Hoffmann, K-U

    2013-01-01

    Thermodynamic Diagrams for High Temperature Plasmas of Air, Air-Carbon, Carbon-Hydrogen Mixtures, and Argon provides information relating to the properties of equilibrium gas plasmas formed from hydrocarbons, from air without argon, from pure argon, and from mixtures of air and carbon at various compositions, temperatures and pressures. The data are presented in graphical rather than tabular form to provide a clearer picture of the plasma processes investigated. This book is composed of four chapters, and begins with the introduction to the characteristics of plasmas, with emphasis on their th

  16. CID thermionic gun system

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1981-10-01

    A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10 11 electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented

  17. CID thermionic gun system

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1982-01-01

    A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10 11 electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented

  18. Simplified pipe gun

    International Nuclear Information System (INIS)

    Sorensen, H.; Nordskov, A.; Sass, B.; Visler, T.

    1987-01-01

    A simplified version of a deuterium pellet gun based on the pipe gun principle is described. The pipe gun is made from a continuous tube of stainless steel and gas is fed in from the muzzle end only. It is indicated that the pellet length is determined by the temperature gradient along the barrel right outside the freezing cell. Velocities of around 1000 m/s with a scatter of +- 2% are obtained with a propellant gas pressure of 40 bar

  19. RF guns: a review

    International Nuclear Information System (INIS)

    Travier, C.

    1990-06-01

    Free Electron Lasers and future linear colliders require very bright electron beams. Conventional injectors made of DC guns and RF bunchers have intrinsic limitations. The recently proposed RF guns have already proven their capability to produce bright beams. The necessary effort to improve further these performances and to gain reliability is now undertaken by many laboratories. More than twenty RF gun projects both thermionic and laser-driven are reviewed. Their specific characteristics are outlined and their nominal performances are given

  20. CN emission spectroscopy study of carbon plasma in nitrogen environment

    International Nuclear Information System (INIS)

    Abdelli-Messaci, S.; Kerdja, T.; Bendib, A.; Malek, S.

    2005-01-01

    Spectroscopic emission diagnostics of a carbon plasma created by an excimer KrF laser pulse at three laser fluences (12, 25 and 32 J/cm 2 ) is performed under nitrogen ambient at pressures of 0.5 and 1 mbar. By following the time evolution of the radical CN spectral emission profiles, we notice, at a certain distance from the target surface, the existence of twin peaks for the time of flight distribution. This double structure depends on laser fluence and gas pressure parameters. The first peak moves forward in relation with the plasma expansion whereas the second peak moves backward and it is attributed to CN species undergoing oscillations or reflected shocks

  1. Carbon fiber composites application in ITER plasma facing components

    Science.gov (United States)

    Barabash, V.; Akiba, M.; Bonal, J. P.; Federici, G.; Matera, R.; Nakamura, K.; Pacher, H. D.; Rödig, M.; Vieider, G.; Wu, C. H.

    1998-10-01

    Carbon Fiber Composites (CFCs) are one of the candidate armour materials for the plasma facing components of the International Thermonuclear Experimental Reactor (ITER). For the present reference design, CFC has been selected as armour for the divertor target near the plasma strike point mainly because of unique resistance to high normal and off-normal heat loads. It does not melt under disruptions and might have higher erosion lifetime in comparison with other possible armour materials. Issues related to CFC application in ITER are described in this paper. They include erosion lifetime, tritium codeposition with eroded material and possible methods for the removal of the codeposited layers, neutron irradiation effect, development of joining technologies with heat sink materials, and thermomechanical performance. The status of the development of new advanced CFCs for ITER application is also described. Finally, the remaining R&D needs are critically discussed.

  2. Carbon fiber composites application in ITER plasma facing components

    International Nuclear Information System (INIS)

    Barabash, V.; Federici, G.; Matera, R.; Akiba, M.; Nakamura, K.; Bonal, J.P.; Pacher, H.D.; Roedig, M.; Vieider, G.; Wu, C.H.

    1998-01-01

    Carbon fiber composites (CFCs) are one of the candidate armour materials for the plasma facing components of the international thermonuclear experimental reactor (ITER). For the present reference design, CFC has been selected as armour for the divertor target near the plasma strike point mainly because of unique resistance to high normal and off-normal heat loads. It does not melt under disruptions and might have higher erosion lifetime in comparison with other possible armour materials. Issues related to CFC application in ITER are described in this paper. They include erosion lifetime, tritium codeposition with eroded material and possible methods for the removal of the codeposited layers, neutron irradiation effect, development of joining technologies with heat sink materials, and thermomechanical performance. The status of the development of new advanced CFCs for ITER application is also described. Finally, the remaining R and D needs are critically discussed. (orig.)

  3. Spheromak experiment using separate guns for formation and sustainment

    International Nuclear Information System (INIS)

    Brown, M.R.; Martin, A.

    1996-01-01

    An experiment is described that incorporates the use of separate magnetized plasma guns for formation and sustainment of a spheromak. It is shown that energy coupling efficiency approaches unity if the gun and spheromak are of comparable size. A large gun should be able to operate at lower current and therefore lower voltage. In addition, it is expected that a gun matched to the size of the spheromak will cause less perturbation to the equilibrium. It is proposed to use a smaller gun for spheromak formation and a large, efficient gun for sustainment. The theoretical basis for the experiment is developed, and the details of the experiment are described. A prediction of the equilibrium magnetic flux surfaces using the EFIT code is presented. 28 refs., 3 figs., 1 tab

  4. Electron guns for accelerators

    International Nuclear Information System (INIS)

    Rangarajan, L.M.; Mahadevan, S.; Ramamurthi, S.S.

    1995-01-01

    The high voltage, high current electron guns developed elsewhere for Linacs are based on cathode pulsing with direct emitting cathodes. Our grid pulsed triode gun employs indirect emitting cathode pellet under electron bombardment or a direct cathode emitter. Electron beam from the gun is injected to the accelerator guide at 40 kV and pulse duration is 2.8μsec. The gun is limited to axially symmetric geometry and electron optical design is optimized by computer programming. The gun with a water cooled Faraday cup is connected to a vacuum system comprising of a sputter ion pump and sorption pump. Working pressure is 1x10 -6 Pa. Gun is designed to be baked as an assembly at temperatures of 400 degC while vacuum processing. Materials are therefore restricted to refractory metals, SS, OFHC copper and all the electrodes are housed inside a ceramic tube. Lower Z graphite is used as a base material of Faraday cup. Grid is non-intercepting modulator anode, a new feature introduced, as compared to meshed grid system by others. CAT gun delivers 160 mA current pulses at 40 kV and its working characteristics such as perveance, emittance and beam radius compare well with SLAC and Hermosa guns. The above guns can be used for electron beam machines such as medical Linacs, industrial accelerators and EB welding equipment. (author). 2 refs., 2 figs

  5. Measurement of population inversions and gain in carbon fiber plasmas

    International Nuclear Information System (INIS)

    Milchberg, H.; Skinner, C.H.; Suckewer, S.; Voorhees, D.

    1985-10-01

    A CO 2 laser (approx.0.5 kJ energy, 70 nsec pulse width) was focussed onto the end of an axially oriented, thick (35 to 350 μ) carbon fiber with or without a magnetic field present along the laser-fiber axis. We present evidence for axial-to-transverse enhancement of the CVI 182A (n = 3 → 2) transition, which is correlated with the appearance of a population inversion between levels n = 3 and 2. For the B = 0 kG, zero field case, the maximum gain-length product of kl approx. =3 (k approx. =6 cm -1 ) was measured for a carbon fiber coated with a thin layer of aluminum (for additional radiation cooling). The results are interpreted in terms of fast recombination due mostly to thermal conduction from the plasma to the cold fiber core

  6. Plasma-pulse formation and acceleration for fast high-power technology and switching applications

    International Nuclear Information System (INIS)

    Doucet, H.J.; Jones, W.D.; Moustaizis, S.; Lamain, H.; Rouille, C.

    1985-01-01

    A carbon plasma gun powered by a low-inductance capacitor bank and transmission line is used to produce μsec-length pulses of protons having densities of 10/sup 12/-10/sup 14/ cm/sup -3/ at distances of 0.3-1.5 m from the gun and velocities of 10-20 cm/μs. Essential features are a low-inductance surface switch and a nonlinear transmission grid

  7. Instantaneous current and field structure of a gun-driven spheromak for two gun polarities

    International Nuclear Information System (INIS)

    Woodruff, S; Nagata, M

    2002-01-01

    The instantaneous plasma structure of the SPHEX spheromak is determined here by numerically processing data from insertable Rogowski and magnetic field probes. Data is presented and compared for two modes of gun operation: with the central electrode biased positively and negatively. It is found that while the mean-, or even instantaneous-, field structure would give the impression of a roughly axisymmetric spheromak, the instantaneous current structure does not. Hundred per cent variations in J measured at the magnetic axis can be explained by the rotation of a current filament that has a width equal to half of the radius of the flux-conserving first wall. In positive gun operation, current leaves the filament in the confinement region leading to high wall current there. In negative gun operation, wall current remains low as all injected current returns to the gun through the plasma. The plasma, in either instance, is strongly asymmetric. We discuss evidence for the existence of the current filament in other gun-driven spheromaks and coaxial plasma thrusters

  8. A high current high frequency ions gun

    International Nuclear Information System (INIS)

    Coutant, J.; Prevot, F.; Vienet, R.

    1959-01-01

    A 10 mA protons gun has been developed for different purposes. The first part of the report studies the plasma production with a RF electromagnetic field. Then the ion extraction process is analysed with particular reference to space charge phenomena. The last part describes a three electrode electrostatic lens which focusses the beam. (author) [fr

  9. Gun Safety (For Parents)

    Science.gov (United States)

    ... from the home of a relative or friend. Teens should never be able to get to a gun and bullets without an adult being there. People of any age who are depressed are at increased risk of suicide. If someone in the family has depression, or has had thoughts of suicide, all guns ...

  10. Guns at College.

    Science.gov (United States)

    Miller, Matthew; Hemenway, David; Wechsler, Henry

    1999-01-01

    Surveyed undergraduate students nationwide concerning firearm possession. About 3.5% possessed working firearms. Students with guns were more likely to be male, White, or Native American; binge drink; live off-campus; and live with a spouse or significant other. Students with guns were more likely to engage in activities that put themselves and…

  11. Remotely controlled spray gun

    Science.gov (United States)

    Cunningham, William C. (Inventor)

    1987-01-01

    A remotely controlled spray gun is described in which a nozzle and orifice plate are held in precise axial alignment by an alignment member, which in turn is held in alignment with the general outlet of the spray gun by insert. By this arrangement, the precise repeatability of spray patterns is insured.

  12. Plasma-induced field emission study of carbon nanotube cathode

    Directory of Open Access Journals (Sweden)

    Yi Shen

    2011-10-01

    Full Text Available An investigation on the plasma-induced field emission (PFE properties of a large area carbon nanotube (CNT cathode on a 2 MeV linear induction accelerator injector is presented. Experimental results show that the cathode is able to emit intense electron beams. Intense electron beams of 14.9–127.8  A/cm^{2} are obtained from the cathode. The CNT cathode desorbs gases from the CNTs during the PFE process. The fast cathode plasma expansion affects the diode perveance. The amount of outgassing is estimated to be 0.06–0.49  Pa·L, and the ratio of outgassing and electron are roughly calculated to be within the range of 170–350 atoms per electron. The effect of the outgassing is analyzed, and the outgassing mass spectrum of the CNT cathode has been studied during the PFE. There is a significant desorption of CO_{2}, N_{2}(CO, and H_{2} gases, which plays an important role during the PFE process. All the experiments demonstrate that the outgassing plays an important role in the formation of the cathode plasma. Moreover, the characteristic turn-on time of the CNT cathode was measured to be 39 ns.

  13. Nanopattern formation using localized plasma for growth of single-standing carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Javadi, Mohammad; Abdi, Yaser, E-mail: y.abdi@ut.ac.ir [University of Tehran, Nanophysics Research Laboratory, Department of Physics (Iran, Islamic Republic of)

    2017-01-15

    We report a novel method for formation of self-organized single-standing carbon nanotubes by customizing a plasma-based process. The growth of carbon nanotubes by plasma-enhanced chemical vapor deposition provides suitable grounds to utilize plasma–solid interactions for nanopatterning. The bulk plasma is utilized to fabricate carbon nanotubes on the prepatterned Ni catalyst which in turn can confine the plasma to the growth region. The plasma localization leads to a dielectrophoretic force exerted on Ni atoms and can be engineered in order to grow a specific pattern of self-organized single-standing carbon nanotubes. Numerical simulations based on the plasma localization and dielectrophoretic force confirmed the experimental results. This method provides a simple and cost-effective approach to obtain nanopatterned arrays of carbon nanotubes which can be used for fabrication of photonic and phononic crystals, self-gated field emission-based transistors and displays.

  14. Carbon dioxide elimination and regeneration of resources in a microwave plasma torch

    International Nuclear Information System (INIS)

    Uhm, Han S.; Kwak, Hyoung S.; Hong, Yong C.

    2016-01-01

    Carbon dioxide gas as a working gas produces a stable plasma-torch by making use of 2.45 GHz microwaves. The temperature of the torch flame is measured by making use of optical spectroscopy and a thermocouple device. Two distinctive regions are exhibited, a bright, whitish region of a high-temperature zone and a bluish, dimmer region of a relatively low-temperature zone. The bright, whitish region is a typical torch based on plasma species where an analytical investigation indicates dissociation of a substantial fraction of carbon dioxide molecules, forming carbon monoxides and oxygen atoms. The emission profiles of the oxygen atoms and the carbon monoxide molecules confirm the theoretical predictions of carbon dioxide disintegration in the torch. Various hydrocarbon materials may be introduced into the carbon dioxide torch, regenerating new resources and reducing carbon dioxide concentration in the torch. As an example, coal powders in the carbon dioxide torch are converted into carbon monoxide according to the reaction of CO_2 + C → 2CO, reducing a substantial amount of carbon dioxide concentration in the torch. In this regards, the microwave plasma torch may be one of the best ways of converting the carbon dioxides into useful new materials. - Highlights: • Carbon dioxide gas produces a plasma-torch by making use of 2.45 GHz microwaves. • The temperature measurement of torch flame by optical spectroscopy. • Disintegration of carbon dioxide into carbon monoxide and oxygen atom. • Emission profiles of carbon monoxide confirm disintegration theory. • Conversion of carbon dioxide into carbon monoxide in the plasma torch. - This article presents carbon-dioxide plasma torch operated by microwaves and its applications to regeneration of new resources, eliminating carbon dioxide molecules.

  15. Formation of carbon nanostructures using acetylene, argon-acetylene and argon-hydrogen-acetylene plasmas

    International Nuclear Information System (INIS)

    Marcinauskas, L.; Grigonis, A.; Minialga, V.; Marcinauskas, L.; Valincius, V.

    2013-01-01

    The films prepared in argon-acetylene plasma are attributed to graphite-like carbon films. Addition of the hydrogen decreases growth rate and the surface roughness of the films and lead to the formation of nanocrystalline graphite. The carbon nanotubes were formed at low (≤ 450°C; p = 40 Pa) temperature in pure acetylene plasma. (authors)

  16. Atmospheric pressure DBD gun and its application in ink printability

    International Nuclear Information System (INIS)

    Chen Qiang; Zhang Yuefei; Han Erli; Ge Yuanjing

    2005-01-01

    In this paper, a plasma source discharging at atmospheric pressure and its characterization diagnosed by a Langmuir probe and a digital camera are presented. As an application the dielectric barrier discharge (DBD) gun modifying an ultraviolet cured resin surface for ink printability is reported. The results from the digital camera indicate the uniformity and homogeneity of the plasma generated from the gun in the downstream but depending on the input power, diameter of electrodes, gas flow rates and the distance between the substrates and the nozzle. The contact angle measurement proves the efficiency of gun during the surface modification. The ink printability following DBD gun processing described here was significantly improved. The performed surface analysis using Fourier transform infrared indicates that the polarity of surface grafted in plasma is responsible for the film printability

  17. Plasma Treatment to Remove Carbon from Indium UV Filters

    Science.gov (United States)

    Greer, Harold F.; Nikzad, Shouleh; Beasley, Matthew; Gantner, Brennan

    2012-01-01

    The sounding rocket experiment FIRE (Far-ultraviolet Imaging Rocket Experiment) will improve the science community fs ability to image a spectral region hitherto unexplored astronomically. The imaging band of FIRE (.900 to 1,100 Angstroms) will help fill the current wavelength imaging observation hole existing from approximately equal to 620 Angstroms to the GALEX band near 1,350 Angstroms. FIRE is a single-optic prime focus telescope with a 1.75-m focal length. The bandpass of 900 to 1100 Angstroms is set by a combination of the mirror coating, the indium filter in front of the detector, and the salt coating on the front of the detector fs microchannel plates. Critical to this is the indium filter that must reduce the flux from Lymanalpha at 1,216 Angstroms by a minimum factor of 10(exp -4). The cost of this Lyman-alpha removal is that the filter is not fully transparent at the desired wavelengths of 900 to 1,100 Angstroms. Recently, in a project to improve the performance of optical and solar blind detectors, JPL developed a plasma process capable of removing carbon contamination from indium metal. In this work, a low-power, low-temperature hydrogen plasma reacts with the carbon contaminants in the indium to form methane, but leaves the indium metal surface undisturbed. This process was recently tested in a proof-of-concept experiment with a filter provided by the University of Colorado. This initial test on a test filter showed improvement in transmission from 7 to 9 percent near 900 with no process optimization applied. Further improvements in this performance were readily achieved to bring the total transmission to 12% with optimization to JPL's existing process.

  18. Characterization of a capillary plasma reactor for carbon dioxide decomposition

    International Nuclear Information System (INIS)

    Mori, Shinsuke; Yamamoto, Aguru; Suzuki, Masaaki

    2006-01-01

    The decomposition of carbon dioxide in a plasma reactor was investigated experimentally, using capillary discharge tubes with a diameter of 0.5 or 3.0 mm and a length of 25, 50, 75, 100 or 150 mm. The chemical composition of the reaction products and the current-voltage characteristics were measured over a pressure range of 3.33-120 Torr, and the CO 2 conversion rates and reduced electric fields were calculated. The results show that the influence of downscaling on the reduced electric fields can be well evaluated by adjusting both the current density, i, and the products of the pressure and the tube diameter, pd. However, the characteristics of CO 2 decomposition cannot be determined based on i and pd; they are better characterized by i and p. It can be deduced from our experimental results that the CO 2 conversion rate is predominated by the electron impact CO 2 dissociation and gas phase reverse reactions even in a capillary plasma reactor

  19. Modification of glassy carbon surfaces by atmospheric pressure cold plasma torch

    DEFF Research Database (Denmark)

    Mortensen, Henrik Junge; Kusano, Yukihiro; Leipold, Frank

    2006-01-01

    The effect of plasma treatment on glassy carbon (GC) surfaces was studied with adhesion improvement in mind. A newly constructed remote plasma source was used to treat GC plates. Pure He and a dilute NH3/He mixture were used as feed gases. Optical emission spectroscopy was performed for plasma to...

  20. 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...

  1. Synthesis of carbon nano structures by plasma discharge

    International Nuclear Information System (INIS)

    Jimenez L, M.L.

    2007-01-01

    Due to the great quantity of applications of carbon neocarcinostatin (NEC) in diverse areas like: synthesis of super-resistant materials, hydrogen storage, nano sensors generation and nano catalysts, one has seen the necessity to generate new synthesis processes of these materials as well as to already improve those existent. The present work has as objective to optimize the NEC synthesis process by means of the electric arc method which uses alternating current to high frequencies (HF), obtaining relatively clean products; that is to say, it hardly presents amorphous material neither impurities. They stand out the obtaining of carbon nano fibers (NFC) by means of a luminescent-arc discharge, in a gas mixture He-CH 4 with 34% at.Ni/10.32%at.Y like catalyst; to a frequency of 42 k Hz and low power (300 W). This method benefits the agglomeration of the particles in both electrodes due to the high frequencies. The time of duration of the process oscillates between 5 and 20 minutes. The obtained product was characterized by scanning electron microscopy (MEB), transmission electron microscopy (MET) to determine the type of obtained NEC and by X-ray diffraction analysis and Raman spectroscopy to determine the purity of the samples. The NFC are relatively free of amorphous coal. The surface and structural analysis indicates that the fibers have a half diameter of 80 nm. It is also made, a study by optical emission spectroscopy of the plasma using the Swan band to determine the temperature. (Author)

  2. High Velocity Gas Gun

    Science.gov (United States)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  3. Gun Dynamics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Gun Dynamics Laboratory is a research multi-task facility, which includes two firing bays, a high bay area and a second floor laboratory space. The high bay area...

  4. Gun control saves lives.

    Science.gov (United States)

    Matzopoulos, Richard

    2016-05-19

    Reducing firearm mortality by means of stricter gun control is one of the most important short- to medium-term measures to address the burden of violence in South Africa, while longer-term interventions and policy measures take effect.

  5. Teen Suicide and Guns

    Science.gov (United States)

    ... Issues Listen Text Size Email Print Share Teen Suicide and Guns Page Content Article Body Protect Your ... of a passing problem, not the outcome! Teen Suicide—A Big Problem Suicide is one of the ...

  6. Microwave interferometry of PEOS plasma sources

    International Nuclear Information System (INIS)

    Weber, B.V.; Commisso, R.J.; Goodrich, P.J.; Hinshelwood, D.D.; Neri, J.M.

    1988-01-01

    A 70 GHz microwave interferometer is used to measure the electron density for various configurations of sources used in plasma erosion opening switch (PEOS) experiments. The interferometer is a phase quadrature system, so the density can be measured as a function of time without ambiguity. Measurements have been made for carbon guns and flashboards driven by a .6 μF. 25 kV capacitor. The plasma density from a gun rises to its peak value in about 10 μs. Then decays in the next 40 μs. A metal screen placed between the gun and the microwave beam attenuates the plasma density by a factor greater than the geometrical transparency of the screen. Density measurements as a function of distance from the gun are analyzed to give the plasma spatial dependence, and the particle flux density and flow velocity are calculated from the continuity equation. Density values used to model previous PEOS experiments are comparable to the values measured here. The flashboard sources produce a denser, faster plasma that is more difficult to diagnose with the interferometer than the gun plasma because of refractive bending of the microwave beam. Reducing the plasma length reduces the refractive bending enough that some measurements are possible. Direct comparison with Gamble II PEOS experiments that used these flashboard sources may not be possible at this frequency because of refraction, but estimates based on measurements at larger distances give reasonable agreement with values used to model these experiments. Other measurements that will be presented include the effects of plasma flow against metal walls, effects of changing the driving current waveform, measurements made in actual experimental configurations and comparisons with Faraday cup and electric probe measurements

  7. Erosion of pyrolytic carbon under high surface energy deposition from a pulsed hydrogen plasma

    International Nuclear Information System (INIS)

    Bolt, H.

    1992-01-01

    Carbon materials are widely applied as plasma facing materials in nuclear fusion devices and are also the prime candidate materials for the next generation of experimental fusion reactors. During operation these materials are frequently subjected to high energy deposition from plasma disruptions. The erosion of carbon materials is regarded as the main issue governing the operational lifetime of plasma facing components. Laboratory experiments have been performed to study the thermal erosion behaviour of carbon in a plasma environment. In the experiments the surface of pyrolytic carbon specimens was exposed to pulsed energy deposition of up to 3.8 MJ m -2 from a hydrogen plasma. The behaviour of the eroded carbon species in the plasma was measured by time-resolved and space-resolved spectroscopy. Intense line radiation of ionic carbon has been measured in the plasma in front of the carbon surface. The results show that the eroded carbon is immediately ionised in the vicinity of the material surface, with a fraction of it being ionised to the double-charged state. (Author)

  8. Gas gun dynamics

    International Nuclear Information System (INIS)

    Denny, Mark

    2013-01-01

    The mechanics and thermodynamics of one- and two-stage gas guns are developed. Very high projectile muzzle speed can be obtained by the two-stage version. The physics of simple gas guns, such as air rifles, is accessible to undergraduates and the same level of presentation is used here to understand more complex designs. Numerical solutions to the equations of motion are shown, along with insightful analytic approximations. (paper)

  9. Particle transport and gas feed during gun injection

    International Nuclear Information System (INIS)

    Fowler, T K.

    1999-01-01

    It is shown that ion and neutral transport during gun injection tends to equalize the density in the spheromak to that in the open-line current channel. Since a gun operating at or near the ion saturation current requires a minimum density, because of transport these gun requirements also determine a minimum density in the spheromak that increases as the field increases. Hence attaining high fields by gun injection sets lower limits on the density, which in turn limits the temperature of the plasma and increases its ohmic resistance. Estimates of these effects are given using 0-D models calibrated to CTX, as guidance to 2-D UEDGE calculations in progress. For gun power levels in SSPX and the Pulsed Spheromak reactor, we find that buildup persists to the highest field levels of interest

  10. Plasma Treatment of Carbon Nanotubes Applied to Improve the High Performance of Carbon Nanofiber Supercapacitors

    International Nuclear Information System (INIS)

    Chang, Wei-Min; Wang, Cheng-Chien; Chen, Chuh-Yung

    2015-01-01

    Graphical abstract: This article focused on improving conductivity of carbon nanofibers (CNFs) by added plasma-treatment carbon nanotubes (CNTs). The plasma modification method avoided the destruction of the length and structure of the CNTs and maintained their good electrical properties. Through this method, the relation between conductivity and surface activity site of CNFs was investigated. The results shown that he CNTs-MA added to the CNFs successfully maintained the activity sites on the surface of the CNFs and provide a good electric network to enhance the supercapacitor performance of the CNFs. - Highlights: • The plasma modification method avoided the destruction of the length and structure of the CNTs and maintained their good electrical properties. • The highest conductivity of the CNTs-MA/CNF was 5.2 s/cm at 2.5 wt.% of CNTs-MA addition. It was increased to 8.7 time. • The CNTs-MA added to the CNFs successfully maintained the activity sites on the surface of the CNFs and provide a good electric network to enhance the supercapacitor performance of the CNFs. The highest capacitance was 382 F/g. - Abstract: Plasma-treatment carbon nanotubes (CNTs) grafted with maleic anhydride (MA) were embedded in polyacryonitrile nanofibers via electrospinning and subsequently carbonizated at 800 °C to fabricate carbon nanofibers (CNFs). The grafted degree of MA on CNTs (CNTs-MA) was determined via Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The morphology, surface composition and conductivity of the CNTs-MA/CNF were characterized using electron microscopy, X-ray photoelectron and electrochemical impedance spectroscopy, respectively. CNTs-MA not only affected the conductivity of the CNFs but also the types of the nitrogen functional groups that could be represented as active sites on the CNFs to enhance the performance of the supercapacitors. When 2.5 wt.% CNTs-MA was embedded in the CNFs, the highest conductivity was obtained at

  11. Conversion of carbon dioxide to carbon monoxide by pulse dielectric barrier discharge plasma

    Science.gov (United States)

    Wang, Taobo; Liu, Hongxia; Xiong, Xiang; Feng, Xinxin

    2017-01-01

    The conversion of carbon dioxide (CO2) to carbon monoxide (CO) was investigated in a non-thermal plasma dielectric barrier discharge (DBD) reactor, and the effects of different process conditions on the CO2 conversion were investigated. The results showed that the increase of input power could optimize the conversion of CO2 to CO. The CO2 conversion and CO yield were negatively correlated with the gas flow rate, but there was an optimum gas flow rate, that made the CO selectivity best. The carrier gas (N2, Ar) was conducive to the conversion of CO2, and the effect of N2 as carrier gas was better than Ar. The conversion of CO2 to CO was enhanced by addition of the catalyst (5A molecular sieve).

  12. Growth of highly oriented carbon nanotubes by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.P.; Xu, J.W.; Ren, Z.F.; Wang, J.H. [Materials Synthesis Laboratory, Departments of Physics and Chemistry, and Center for Advanced Photonic and Electronic Materials (CAPEM), State University of New York at Buffalo, Buffalo, New York 14260 (United States); Siegal, M.P.; Provencio, P.N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1998-12-01

    Highly oriented, multiwalled carbon nanotubes were grown on polished polycrystalline and single crystal nickel substrates by plasma enhanced hot filament chemical vapor deposition at temperatures below 666 {degree}C. The carbon nanotubes range from 10 to 500 nm in diameter and 0.1 to 50 {mu}m in length depending on growth conditions. Acetylene is used as the carbon source for the growth of the carbon nanotubes and ammonia is used for dilution gas and catalysis. The plasma intensity, acetylene to ammonia gas ratio, and their flow rates, etc. affect the diameters and uniformity of the carbon nanotubes. {copyright} {ital 1998 American Institute of Physics.}

  13. Boron carbide-coated carbon material, manufacturing method therefor and plasma facing material

    International Nuclear Information System (INIS)

    Suzuki, Takayuki; Kikuchi, Yoshihiro; Hyakki, Yasuo.

    1997-01-01

    The present invention concerns a plasma facing material suitable to a thermonuclear device. The material comprises a carbon material formed by converting the surface of a carbon fiber-reinforced carbon material comprising a carbon matrix and carbon fibers to a boron carbide, the material has a surface comprising vertically or substantially vertically oriented carbon fibers, and the thickness of the surface converted to boron carbide is reduced in the carbon fiber portion than in the carbon matrix portion. Alternatively, a carbon fiber-reinforced carbon material containing carbon fibers having a higher graphitizing degree than the carbon matrix is converted to boron carbide on the surface where the carbon fibers are oriented vertically or substantially vertically. The carbon fiber-reinforced material is used as a base material, and a resin material impregnated into a shaped carbon fiber product is carbonized or thermally decomposed carbon is filled as a matrix. The material of the present invention has high heat conduction and excellent in heat resistance thereby being suitable to a plasma facing material for a thermonuclear device. Electric specific resistivity of the entire coating layer can be lowered, occurrence of arc discharge is prevented and melting can be prevented. (N.H.)

  14. Using hydrocarbon as a carbon source for synthesis of carbon nanotube by electric field induced needle-pulsed plasma

    International Nuclear Information System (INIS)

    Kazemi Kia, Kaveh; Bonabi, Fahimeh

    2013-01-01

    In this work different hydrocarbons are used as the carbon source, in the production of carbon nanotubes (CNTs) and nano onions. An electric field induced needle pulse arc-discharge reactor is used. The influence of starting carbon on the synthesis of CNTs is investigated. The production efficiency is compared for Acetone, Isopropanol and Naphthalene as simple hydrocarbons. The hydrocarbons are preheated and then pretreated by electric field before being exposed to plasma. The hydrocarbon vapor is injected into plasma through a graphite spout in the cathode assembly. The pulsed plasma takes place between two graphite rods while a strong electric field has been already established alongside the electrodes. The pulse width is 0.3 μs. Mechanism of precursor decomposition is discussed by describing three forms of energy that are utilized to disintegrate the precursor molecules: thermal energy, electric field and kinetic energy of plasma. Molecular polarity of a hydrocarbon is one of the reasons for choosing carbon raw material as a precursor in an electric field induced low power pulsed-plasma. The results show that in order to obtain high quality carbon nanotubes, Acetone is preferred to Isopropanol and Naphthalene. Scanning probe microscopy techniques are used to investigate the products. - Highlights: • We synthesized CNTs (carbon nano tubes) by needle pulsed plasma. • We use different hydrocarbons as carbon source in the production of CNTs. • We investigated the influence of starting carbon on the synthesis of CNTs. • Thermal energy, electric field and kinetic energy are used to break carbon bonds. • Polar hydrocarbon molecules are more efficient than nonpolar ones in production

  15. Electrical Characteristics of Carbon Nanotubes by Plasma and Microwave Surface Treatments

    International Nuclear Information System (INIS)

    Cho, Sangjin; Lee, Soonbo; Boo, Jinhyo; Shrestha, Shankar Prasad

    2014-01-01

    The plasma and microwave surface treatments of carbon nanotubes that loaded on plastic substrates were carried out with expecting a change of carbon nanotube dispersion by increasing treatment time. The microwave treatment process was undergone by commercial microwave oven (800 W). The electrical property was measured by hall measurement and resistance was increased by increasing O 2 flow rate of plasma, suggesting an improvement of carbon nanotube dispersion and a possibility of controlling the resistances of carbon nanotubes by plasma surface treatment. The resistance was increased in both polyethylene terephthalate and polyimide substrates by increasing O 2 flow rate. Resistance changes only slightly with different O 2 flow treatment in measure rho for all polyimide samples. Sheet resistance is lowest in polyimide substrate not due to high carbon nanotube loading but due to tendency to remain in elongated structure. O 2 or N 2 plasma treatments on both polyethylene terephthalate and polyimide substrates lead to increase in sheet resistance

  16. Patterned growth of carbon nanotubes obtained by high density plasma chemical vapor deposition

    Science.gov (United States)

    Mousinho, A. P.; Mansano, R. D.

    2015-03-01

    Patterned growth of carbon nanotubes by chemical vapor deposition represents an assembly approach to place and orient nanotubes at a stage as early as when they are synthesized. In this work, the carbon nanotubes were obtained at room temperature by High Density Plasmas Chemical Vapor Deposition (HDPCVD) system. This CVD system uses a new concept of plasma generation, where a planar coil coupled to an RF system for plasma generation was used with an electrostatic shield for plasma densification. In this mode, high density plasmas are obtained. We also report the patterned growth of carbon nanotubes on full 4-in Si wafers, using pure methane plasmas and iron as precursor material (seed). Photolithography processes were used to pattern the regions on the silicon wafers. The carbon nanotubes were characterized by micro-Raman spectroscopy, the spectra showed very single-walled carbon nanotubes axial vibration modes around 1590 cm-1 and radial breathing modes (RBM) around 120-400 cm-1, confirming that high quality of the carbon nanotubes obtained in this work. The carbon nanotubes were analyzed by atomic force microscopy and scanning electron microscopy too. The results showed that is possible obtain high-aligned carbon nanotubes with patterned growth on a silicon wafer with high reproducibility and control.

  17. Synthesis of Carbon nano structures by plasma discharge

    International Nuclear Information System (INIS)

    Jimenez L, M.L.

    2007-01-01

    Due to the great quantity of applications of the carbon nano structures (NEC) in diverse areas like: synthesis of super-resistant materials, hydrogen storage, nano sensors generation and nano catalysts, it has seen the necessity to generate new processes of synthesis of this materials as well as to already improve those existent. The present work has as objective to optimize the NEC synthesis process by means of the electric arc method which uses alternating current to high frequencies (HF), obtaining relatively clean products; that is to say, it hardly presents amorphous material neither sludges. They stand out the obtaining of carbon nano fibers (NFC) by means of a luminescent-arch discharge, in a gas mixture of He-CH 4 with 34% at. Ni/10.32% at.Y like catalyst; at a frequency of 42 kHz and low power (300 W). This method benefits the amass of the particles in both electrodes due to the high frequencies. The time of duration of the process oscillates between 5 and 20 minutes. The obtained product was characterized by scanning electron microscopy (MEB), transmission electron microscopy (MET) to determine the NEC type obtained and by X-ray diffraction analysis and Raman spectroscopy for determining the purity of the samples. The NFC is relatively free of amorphous coal. The surface and structural analysis indicates that the fibers have a half diameter of 80 nm. It is also made, a study by optical emission spectroscopy of plasma using the Swan band for determining the temperature. (Author)

  18. Evaporation and vapor shielding of CFC targets exposed to plasma heat fluxes relevant to ITER ELMs

    International Nuclear Information System (INIS)

    Safronov, V.M.; Arkhipov, N.I.; Landman, I.S.; Pestchanyi, S.E.; Toporkov, D.A.; Zhitlukhin, A.M.

    2009-01-01

    Carbon fibre composite NB31 was tested at plasma gun facility MK-200UG by plasma heat fluxes relevant to Edge Localised Modes in ITER. The paper reports the results obtained on the evaporation threshold of carbon fibre composite, the velocity of carbon vapor motion along and across the magnetic field lines, and the parameters of carbon plasma such as temperature, density and ionization state. First experimental results on investigation of the vapor shield onset conditions are presented also. The obtained experimental data are compared with the results of numerical modeling.

  19. Transition between laser absorption dominated regimes in carbon-based plasma

    Directory of Open Access Journals (Sweden)

    K. Hajisharifi

    2017-09-01

    Full Text Available In this work, we investigate the energy absorption enhancement of a laser by adding a variety of light ion species to a primarily carbon-based plasma during the high-power laser interaction with the finite size targets. A developed Particle-In-Cell simulation code is used to study the reduction of laser reflectivity (stimulated backward scatterings in both Brillouin- and Raman-dominated regimes. The simulation is performed in various Carbon-light ion plasmas such as Carbon-Hydrogen, Carbon-Helium, Carbon-Deuterium, and Carbon-Tritium. The results show that, in the optimized condition, the inclusion of light Hydrogen ions into the Carbon-based plasma up to 50%-50% mixture enhances the laser absorption exceeding 20% in the Brillouin regime due to the suppression of laser reflectivity in contract to 4% in the Raman-dominated regime. Moreover, the absorption dominated regime switches from Raman to Brillouin regime by adding 50% of Hydrogen ions to a purely carbon target. The results of this investigation will be applicable to the laser-plasma experiments so long as the laser energy absorption in the Carbon plasma target, the most readily available material in laboratory, is concerned.

  20. Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2013-01-01

    Full Text Available To open the end of carbon nanotubes and make these ends connect with functional carboxyl group, aligned carbon nanotubes (CNTs arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nanotubes array as electrode materials to build supercapacitor, we found that the capacity (32.2 F/g increased significantly than that of pure carbon nanotubes (6.7 F/g.

  1. Optical emission spectroscopy of carbon laser plasma ion source

    Science.gov (United States)

    Balki, Oguzhan; Rahman, Md. Mahmudur; Elsayed-Ali, Hani E.

    2018-04-01

    Carbon laser plasma generated by an Nd:YAG laser (wavelength 1064 nm, pulse width 7 ns, fluence 4-52 J cm-2) is studied by optical emission spectroscopy and ion time-of-flight. Up to C4+ ions are detected with the ion flux strongly dependent on the laser fluence. The increase in ion charge with the laser fluence is accompanied by observation of multicharged ion lines in the optical spectra. The time-integrated electron temperature Te is calculated from the Boltzmann plot using the C II lines at 392.0, 426.7, and 588.9 nm. Te is found to increase from ∼0.83 eV for a laser fluence of 22 J cm-2 to ∼0.90 eV for 40 J cm-2. The electron density ne is obtained from the Stark broadened profiles of the C II line at 392 nm and is found to increase from ∼ 2 . 1 × 1017cm-3 for 4 J cm-2 to ∼ 3 . 5 × 1017cm-3 for 40 J cm-2. Applying an external electric field parallel to the expanding plume shows no effect on the line emission intensities. Deconvolution of ion time-of-flight signal with a shifted Maxwell-Boltzmann distribution for each charge state results in an ion temperature Ti ∼4.7 and ∼6.0 eV for 20 and 36 J cm-2, respectively.

  2. Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

    Science.gov (United States)

    Zhang, Huanxia; Li, Wei

    2015-11-01

    Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid-base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as Csbnd O, Cdbnd O, and Osbnd Cdbnd O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the plasma-grafting treatments.

  3. Electromagnetic Guns versus Conventional Guns - a performance comparison

    NARCIS (Netherlands)

    Reus, N.M. de; Weijden, J. van der

    1993-01-01

    Performance improvement is one of the key issues of Electromagnetic gun systems compared to conventional gun systems. Due to higher muzzle velocities, the gun's fire control computer will be able to predict the target's future position more accurately because prediction time will be smaller. In this

  4. Cell adhesion and proliferation on poly(tetrafluoroethylene) with plasma-metal and plasma-metal-carbon interfaces

    Science.gov (United States)

    Reznickova, Alena; Kvitek, Ondrej; Kolarova, Katerina; Smejkalova, Zuzana; Svorcik, Vaclav

    2017-06-01

    The aim of this article is to investigate the effect of the interface between plasma activated, gold and carbon coated poly(tetrafluoroethylene) (PTFE) on in vitro adhesion and spreading of mouse fibroblasts (L929). Surface properties of pristine and modified PTFE were studied by several experimental techniques. The thickness of a deposited gold film is an increasing function of the sputtering time, conversely thickness of carbon layer decreases with increasing distance between carbon source and the substrate. Because all the used surface modification techniques take place in inert Ar plasma, oxidized degradation products are formed on the PTFE surface, which affects wettability of the polymer surface. Cytocompatibility tests indicate that on samples with Au/C interface, the cells accumulate on the part of sample with evaporated carbon. Number of L929 cells proliferated on the studied samples is comparable to tissue culture polystyrene standard.

  5. Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huanxia, E-mail: zhanghuanxia818@163.com [College of Materials and Textile Engineering, Jiaxing University, Jiaxing 314001, Zhejiang (China); Li, Wei [College of Textile Engineering, Donghua University, Shanghai 201620 (China); Key Laboratory of Textile Science and Technology, Ministry of Education, Shanghai 201620 (China)

    2015-11-30

    Graphical abstract: - Highlights: • A simple method to improve surface properties is applied to carbon fibers. • The maleic anhydride was grafted onto the carbon fiber with the FTIR spectra. • The plasma treatment time and polymerization condition affected on the grafting rate. • The carbon fibers exhibited excellent surface hydrophilicity and IFSS properties. - Abstract: Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid–base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR–ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as C−O, C=O, and O−C=O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the

  6. Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

    International Nuclear Information System (INIS)

    Zhang, Huanxia; Li, Wei

    2015-01-01

    Graphical abstract: - Highlights: • A simple method to improve surface properties is applied to carbon fibers. • The maleic anhydride was grafted onto the carbon fiber with the FTIR spectra. • The plasma treatment time and polymerization condition affected on the grafting rate. • The carbon fibers exhibited excellent surface hydrophilicity and IFSS properties. - Abstract: Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid–base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR–ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as C−O, C=O, and O−C=O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the

  7. PHERMEX electron gun development

    International Nuclear Information System (INIS)

    Builta, L.A.; Elliott, J.C.; Moir, D.C.; Starke, T.P.; Vecere, C.A.

    1983-01-01

    The PHERMEX facility is a 50-MHz standing-wave linear accelerator. Electrons are injected, accelerated, and transported to a tungsten target where bremsstrahlung x rays are generated for flash radiography of hydrodynamic systems. The purpose of this article is to describe the progress of PHERMEX electron gun development. The goal of this program is to generate and transport a 200-ns, 1-MV, 1-kA electron beam into the first PHERMEX accelerating cavity. The standard gun is operated at a pulse voltage of 550 kV, which is the limit determined by internal breakdown of the vacuum insulator. This insulator has been redesigned, and the gun has been pulsed at 750 kV without internal breakdown. At present, the current output is not limited by voltage but by a phenomenon called pulse shortening, which occurs at a pulse voltage of approximately 650 kV. The phenomenon has been investigated and the results are presented

  8. Unbalanced field RF electron gun

    Science.gov (United States)

    Hofler, Alicia

    2013-11-12

    A design for an RF electron gun having a gun cavity utilizing an unbalanced electric field arrangement. Essentially, the electric field in the first (partial) cell has higher field strength than the electric field in the second (full) cell of the electron gun. The accompanying method discloses the use of the unbalanced field arrangement in the operation of an RF electron gun in order to accelerate an electron beam.

  9. Properties of thermal air plasma with admixing of copper and carbon

    International Nuclear Information System (INIS)

    Fesenko, S; Veklich, A; Boretskij, V; Cressault, Y; Gleizes, A; Teulet, Ph

    2014-01-01

    This paper deals with investigations of air plasma with admixing of copper and carbon. Model plasma source unit with real breaking arc was used for the simulation of real discharges, which can be occurred during sliding of Cu-C composite electrodes on copper wire at electromotive vehicles. The complex technique of plasma property studies is developed. From one hand, the radial profiles of temperature and electron density in plasma of electric arc discharge in air between Cu-C composite and copper electrodes in air flow were measured by optical spectroscopy techniques. From another hand, the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. It was assumed that the thermal conductivity of air plasma is not depending on copper or carbon vapor admixtures. The electron density is obtained from electric conductivity profiles by calculation in assumption of local thermodynamic equilibrium in plasma. Computed in such way radial profiles of electron density in plasma of electric arc discharge in air between copper electrodes were compared with experimentally measured profiles. It is concluded that developed techniques of plasma diagnostics can be reasonably used in investigations of thermal plasma with copper and carbon vapors

  10. Carbon dioxide elimination and regeneration of resources in a microwave plasma torch.

    Science.gov (United States)

    Uhm, Han S; Kwak, Hyoung S; Hong, Yong C

    2016-04-01

    Carbon dioxide gas as a working gas produces a stable plasma-torch by making use of 2.45 GHz microwaves. The temperature of the torch flame is measured by making use of optical spectroscopy and a thermocouple device. Two distinctive regions are exhibited, a bright, whitish region of a high-temperature zone and a bluish, dimmer region of a relatively low-temperature zone. The bright, whitish region is a typical torch based on plasma species where an analytical investigation indicates dissociation of a substantial fraction of carbon dioxide molecules, forming carbon monoxides and oxygen atoms. The emission profiles of the oxygen atoms and the carbon monoxide molecules confirm the theoretical predictions of carbon dioxide disintegration in the torch. Various hydrocarbon materials may be introduced into the carbon dioxide torch, regenerating new resources and reducing carbon dioxide concentration in the torch. As an example, coal powders in the carbon dioxide torch are converted into carbon monoxide according to the reaction of CO2 + C → 2CO, reducing a substantial amount of carbon dioxide concentration in the torch. In this regards, the microwave plasma torch may be one of the best ways of converting the carbon dioxides into useful new materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Glue Guns: Aiming for Safety

    Science.gov (United States)

    Roy, Ken

    2010-01-01

    While glue guns are very useful, there are safety issues. Regardless of the temperature setting, glue guns can burn skin. The teacher should demonstrate and supervise the use of glue guns and have a plan should a student get burned. There should be an initial first aid protocol in place, followed by a visit to the school nurse. An accident report…

  12. Low emittance thermionic electron guns

    International Nuclear Information System (INIS)

    Herrmannsfeldt, W.B.

    1989-01-01

    The author discusses self-field effects and external field effects for electron guns. He also discusses designs of electron guns and their uses in electron cooling systems and as an injector for electrostatic free electron lasers. He closes by looking at electron guns for linear accelerators. 20 references, 3 figures

  13. A supercritical carbon dioxide plasma process for preparing tungsten oxide nanowires

    International Nuclear Information System (INIS)

    Kawashima, Ayato; Nomura, Shinfuku; Toyota, Hiromichi; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro

    2007-01-01

    A supercritical carbon dioxide (CO 2 ) plasma process for fabricating one-dimensional tungsten oxide nanowires coated with amorphous carbon is presented. High-frequency plasma was generated in supercritical carbon dioxide at 20 MPa by using tungsten electrodes mounted in a supercritical cell, and subsequently an organic solvent was introduced with supercritical carbon dioxide into the plasma. Electron microscopy and Raman spectroscopy investigations of the deposited materials showed the production of tungsten oxide nanowires with or without an outer layer. The nanowires with an outer layer exhibited a coaxial structure with an outer concentric layer of amorphous carbon and an inner layer of tungsten oxide with a thickness and diameter of 20-30 and 10-20 nm, respectively

  14. Carbon distribution during plasma detachment triggered by edge magnetic island formation in LHD

    International Nuclear Information System (INIS)

    Dong, C.F.; Morita, S.; Kobayashi, M.; Oishi, T.; Goto, M.; Wang, E.H.; Huang, X.L.

    2013-01-01

    The detached plasma has been successfully achieved by applying the edge 1/1 magnetic island in Large Helical Device (LHD). Carbon, which is uniquely the dominant intrinsic impurity in general LHD discharges, is considered to be the main radiating species in the island-triggered detached plasma. The vertical profile of CIV measured from general discharges of LHD is characterized by a single edge intensity peak. In detached plasmas triggered by the edge magnetic island formation, however, the vertical profile of CIV shows a significant difference. Double edge peaks of CIV are found during the plasma detachment and the CIV radiation is also remarkably enhanced in the vicinity of X-point, whereas the vertical profile of CVI does not show any significant difference in both the attached and detached plasmas. In this proceeding the carbon distribution during the plasma detachment is presented and the results are discussed with edge magnetic field structure. (author)

  15. Hard graphitelike hydrogenated amorphous carbon grown at high rates by a remote plasma

    DEFF Research Database (Denmark)

    Singh, Shailendra Vikram; Zaharia, T.; Creatore, M.

    2010-01-01

    Hydrogenated amorphous carbon (a-C:H) deposited from an Ar-C 2H2 expanding thermal plasma chemical vapor deposition (ETP-CVD) is reported. The downstream plasma region of an ETP is characterized by a low electron temperature (∼0.3 eV), which leads to an ion driven chemistry and negligible physical...

  16. Experimental investigations of driven Alfven wave resonances in a tokamak plasma using carbon dioxide laser interferometry

    International Nuclear Information System (INIS)

    Evans, T.E.

    1984-09-01

    The first direct observation of the internal structure of driven global Alfven eigenmodes in a tokamak plasma is presented. A carbon dioxide laser scattering/interferometer has been designed, built, and installed on the PRETEXT tokamak. By using this diagnostic system in the interferometer configuration, we have for the first time, thoroughly investigated the resonance conditions required for, and the spatial wave field structure of, driven plasma eigenmodes at frequencies below the ion cyclotron frequency in a confined, high temperature, tokamak plasma

  17. Raising the Corrosion Resistance of Low-Carbon Steels by Electrolytic-Plasma Saturation with Nitrogen and Carbon

    Science.gov (United States)

    Kusmanov, S. A.; Grishina, E. P.; Belkin, P. N.; Kusmanova, Yu. V.; Kudryakova, N. O.

    2017-05-01

    Structural features of the external oxide layer and internal nitrided, carbonitrided and carburized layers in steels 10, 20 and St3 produced by the method of electrolytic plasma treatment are studied. Specimens of the steels are tested for corrosion in a naturally aerated 1-N solution of sodium chloride. The condition of the metal/sodium chloride solution interface is studied by the method of electrochemical impedance spectroscopy. It is shown that the corrosion resistance of low-carbon steels can be raised by anode electrolytic-plasma saturation with nitrogen and carbon. Recommendations are given on the choice of carbonitriding modes for structural steels.

  18. Guns, Germs and Steel

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 1. Guns, Germs and Steel - A Short History of Everybody for the Last 13,000 years. Suri Venkatachalam. Book Review Volume 6 Issue 1 January 2001 pp 84-88. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. 120 Hz Gun Review

    Energy Technology Data Exchange (ETDEWEB)

    Colby, E.

    2005-01-31

    The review was held at SLAC on September 11 and 12, 2001. Presentations concerning the thermal analysis, mechanical design, integration with the laser and accelerator, general beam dynamics considerations, a load lock mechanism, and symmetric power feed options comprised the review. Slides from these presentations are available elsewhere. The review committee was charged with evaluating the 120 Hz gun design including proposed load lock and power feed options and recommending improvements. Broader evaluation of the injector as a whole (including focusing and diagnostic systems that do no impact the envelope of the gun itself) is expected to be covered in a future review and will not be commented on here. In general, the long operational experience with four generations of s-band RF guns at numerous labs worldwide has led to considerable experience in design, fabrication, and operation aspects, and provides an excellent base on which to design the higher duty factor LCLS injector. While open questions remain on obtaining the design performance from these injectors, the microwave design of the gun has reached a state of relative maturity.

  20. Gun Dealers, USA.

    Science.gov (United States)

    Duker, Laurie; And Others

    In the United States, more than 11,500 adolescents' and young adults' lives are taken each year by firearms. Although Federal law prohibits minors from purchasing handguns, they typically get them by asking someone of legal age (18 years or older) to purchase them from one of the 256,771 Federally licensed gun dealers. This pamphlet answers…

  1. Magnetron injection gun scaling

    International Nuclear Information System (INIS)

    Lawson, W.

    1988-01-01

    Existing analytic design equations for magnetron injection guns (MIG's) are approximated to obtain a set of scaling laws. The constraints are chosen to examine the maximum peak power capabilities of MIG's. The scaling laws are compared with exact solutions of the design equations and are supported by MIG simulations

  2. Plasma polymerization surface modification of Carbon black and its effect in elastomers

    NARCIS (Netherlands)

    Mathew, T.; Datta, Rabin; Dierkes, Wilma K.; Talma, Auke; Ooij, W.J.; Noordermeer, Jacobus W.M.

    2011-01-01

    Surface modification of carbon black by plasma polymerization was aimed to reduce its surface energy in order to compatibilize the filler with various elastomers. A fullerenic carbon black was used for the modification process. Thermogravimetric analysis, wetting behavior with liquids of known

  3. TRAIL: a tokamak rail gun limiter

    International Nuclear Information System (INIS)

    Yu, W.S.; Powell, J.R.; Usher, J.L.

    1980-01-01

    An attractive new limiter concept is investigated. The TRAIL (Tokamak Rail Gun Limiter) system impacts a stream of moderate velocity pellets (100 to 200 m/sec through the plasma edge region to absorb energy and define the plasma boundary. The pellets are recycled after cooling, to the injector of an E-M mass accelerator. Heat fluxes of approx. 30,000 W/cm 2 can be readily accommodated by the pellets, with very low recirculating power requirements (approx. 0.1%) for the accelerator. The mass accelerator velocity requirements are well within the present state of the art (several Km/sec). Accelerators injecting pellets at approx. 1 Km/sec can be used to control local plasma temperature and current profiles and to act as energy absorbers to shut down the plasma without damage to the first wall if a plasma disruption occurs

  4. Co-axial electrodes gun characteristics

    International Nuclear Information System (INIS)

    Masoud, M.M.; Soliman, H.M.

    1981-01-01

    A coaxial electrodes gun is constructed with inner electrode diameter of 3.2 cm; outer electrode diameter of 6.6 cm and length of 25 cm it is connected to a condenser bank which delivers 4 K joule stored energy. The maximum power of the discharge is equal to 4.5x10 4 K watt; for 5 KV charging voltage. The inductance showed two main peak values of 0.257μH and 0.27μH. Theoretical calculations using one-dimension-single fluid model is μ sed, which shows that the maximum acceleration is at 0.5 sec, and the gas breakdown takes place at the gun breech; at the start of the discharge, will leave the gun after 1.625μ sec, also the drift velocity, the force and the magnetic field are given. The measured results show quite reasonable agreement with the calculations for most of the results, and the position of the plasma sheath inside the gun slightly deviated from the theoretical calculations due to viscosity and wall interaction, as well as other parameters which did not be take into consideration. The plasma current density of the sheath has its maximum value at Z=18 cm, the plasma will leave the coaxial source after 1.5μ sec, from the start of the discharge, which conferms with the theoretical model. Resistance of the gas between the electrodes, changes with time according to the particle injected from this source, and the maximum efficiency of the installation for charging voltage 5kV and pressure 80μ Hg is at approx.=10μ sec and 20.5μ sec

  5. Branched carbon nanofiber network synthesis at room temperature using radio frequency supported microwave plasmas

    OpenAIRE

    Boskovic, BO; Stolojan, V; Zeze, DA; Forrest, RD; Silva, SRP; Haq, S

    2004-01-01

    Carbon nanofibers have been grown at room temperature using a combination of radio frequency and microwave assisted plasma-enhanced chemical vapor deposition. The nanofibers were grown, using Ni powder catalyst, onto substrates kept at room temperature by using a purposely designed water-cooled sample holder. Branched carbon nanofiber growth was obtained without using a template resulting in interconnected carbon nanofiber network formation on substrates held at room temperatur...

  6. Engineering design of the PLX- α coaxial gun

    Science.gov (United States)

    Cruz, E.; Brockington, S.; Case, A.; Luna, M.; Witherspoon, F. D.; Thio, Y. C. Francis; PLX-α Team

    2017-10-01

    We describe the engineering and technical improvements, as well as provide a detailed overview of the design choices, of the latest PLX- α coaxial gun designed for the 60-gun scaling study of spherically imploding plasma liners as a standoff driver for plasma-jet-driven magneto-inertial fusion. Each coaxial gun incorporates a fast, dense gas injection and triggering system, a compact low-weight pfn with integral sparkgap switching, and a contoured gap designed to suppress the blow-by instability. The evolution of the latest Alpha gun is presented with emphasis on its upgraded performance. Changes include a faster more robust gas valve, better-quality ceramic insulator material and enhancements to overall design layout. These changes result in a gun with increased repeatability, reduced potential failure modes, improved fault tolerance and better than expected efficiency. A custom 600- μF, 5-kV pfn and a set of six inline sparkgap switches operated in parallel are mounted directly to the back of the gun, and are designed to reduce inductance, cost, and complexity, maximize efficiency and system reliability, and ensure symmetric current flow. This work supported by the ARPA-E ALPHA Program under contract DE-AR0000566 and Strong Atomics, LLC.

  7. Growth of carbon nanotubes in arc plasma treated graphite disc: microstructural characterization and electrical conductivity study

    Science.gov (United States)

    Nayak, B. B.; Sahu, R. K.; Dash, T.; Pradhan, S.

    2018-03-01

    Circular graphite discs were treated in arc plasma by varying arcing time. Analysis of the plasma treated discs by field emission scanning electron microscope revealed globular grain morphologies on the surfaces, but when the same were observed at higher magnification and higher resolution under transmission electron microscope, growth of multiwall carbon nanotubes of around 2 nm diameter was clearly seen. In situ growth of carbon nanotube bundles/bunches consisting of around 0.7 nm tube diameter was marked in the case of 6 min treated disc surface. Both the untreated and the plasma treated graphite discs were characterized by X-ray diffraction, energy dispersive spectra of X-ray, X-ray photoelectron spectroscopy, transmission electron microscopy, micro Raman spectroscopy and BET surface area measurement. From Raman spectra, BET surface area and microstructure observed in transmission electron microscope, growth of several layers of graphene was identified. Four-point probe measurements for electrical resistivity/conductivity of the graphite discs treated under different plasma conditions showed significant increase in conductivity values over that of untreated graphite conductivity value and the best result, i.e., around eightfold increase in conductivity, was observed in the case of 6 min plasma treated sample exhibiting carbon nanotube bundles/bunches grown on disc surface. By comparing the microstructures of the untreated and plasma treated graphite discs, the electrical conductivity increase in graphite disc is attributed to carbon nanotubes (including bundles/bunches) growth on disc surface by plasma treatment.

  8. Removal of carbon contaminations by RF plasma generated reactive species and subsequent effects on optical surface

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, P. K., E-mail: praveenyadav@rrcat.gov.in; Rai, S. K.; Modi, M. H.; Nayak, M.; Lodha, G. S. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Kumar, M.; Chakera, J. A.; Naik, P. A. [Laser Plasma Laboratory, Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

    2015-06-24

    Carbon contamination on optical elements is a serious issue in synchrotron beam lines for several decades. The basic mechanism of carbon deposition on optics and cleaning strategies are not fully understood. Carbon growth mechanism and optimized cleaning procedures are worldwide under development stage. Optimized RF plasma cleaning is considered an active remedy for the same. In present study carbon contaminated optical test surfaces (carbon capped tungsten thin film) are exposed for 30 minutes to four different gases, rf plasma at constant power and constant dynamic pressure. Structural characterization (thickness, roughness and density) of virgin samples and plasma exposed samples was done by soft x-ray (λ=80 Å) reflectivity measurements at Indus-1 reflectivity beam line. Different gas plasma removes carbon with different rate (0.4 to 0.65 nm /min). A thin layer 2 to 9 nm of different roughness and density is observed at the top surface of tungsten film. Ar gas plasma is found more suitable for cleaning of tungsten surface.

  9. Experimental and theoretical investigation of radiation and dynamics properties in laser-produced carbon plasmas

    Science.gov (United States)

    Min, Qi; Su, Maogen; Wang, Bo; Cao, Shiquan; Sun, Duixiong; Dong, Chenzhong

    2018-05-01

    The radiation and dynamics properties of laser-produced carbon plasma in vacuum were studied experimentally with aid of a spatio-temporally resolved emission spectroscopy technique. In addition, a radiation hydrodynamics model based on the fluid dynamic equations and the radiative transfer equation was presented, and calculation of the charge states was performed within the time-dependent collisional radiative model. Detailed temporal and spatial evolution behavior about plasma parameters have been analyzed, such as velocity, electron temperature, charge state distribution, energy level population, and various atomic processes. At the same time, the effects of different atomic processes on the charge state distribution were examined. Finally, the validity of assuming a local thermodynamic equilibrium in the carbon plasma expansion was checked, and the results clearly indicate that the assumption was valid only at the initial (applicable near the plasma boundary because of a sharp drop of plasma temperature and electron density.

  10. The HART I augmented electric gun facility

    International Nuclear Information System (INIS)

    Fikse, D.A.; Ciesar, J.A.; Wehrli, H.A.; Rimersma, H.; Docherty, E.F.; Pipich, C.W.

    1991-01-01

    This paper reports on an augmented electric gun system that has been commissioned. This system, called HART I (Hypervelocity Augmented Railgun Test), is built around a double augmented rail arrangement with a 1.27-cm square bore. It is powered by the SUVAC II 5.6-MJ distributed capacitor power supply. This arrangement allows operation in a simple, series augmented, or transaugmented gun system configuration. The objective of this facility is to perform materials research augmentation studies, and armature development in the 10-km/s regime. Armature masses of 2 to 4 g will be accelerated in a 4-m long barrel. Baseline bore materials will begin with conventional G9/GlidCop systems and then move into pyrolytic boron nitride/refractory materials. Hybrids, plasma, and ablation stabilized armature systems are planned. The gun system is instrumented with plasma and rail B probes for inbore velocity measurements. In addition, breech and muzzle voltages, currents, and external velocities are measured. The HART I system is currently performing hypervelocity experiments to verify the augmentation models

  11. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization.

    Science.gov (United States)

    Struzzi, Claudia; Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

    2017-01-01

    The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF 4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  12. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization

    Directory of Open Access Journals (Sweden)

    Claudia Struzzi

    2017-08-01

    Full Text Available The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT is correlated to the CF4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  13. Practical XHV electron gun

    International Nuclear Information System (INIS)

    Urata, Tomohiro; Ishikawa, Tsuyoshi; Cho, Boklae; Oshima, Chuhei

    2008-01-01

    We have developed practical XHV chambers of a electron gun, of which the operating pressures are 1x10 -9 Pa in a stainless-steel one and 4x10 -9 Pa in a permalloy one. By mounting a noble single-atom electron source with high brightness and high spatial coherence on the electron gun including electron optics, we demonstrated highly collimated electron-beam emission: ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources. In XHV, in addition, we confirmed stable electron emission up to 20 nA, which results in the specimen current high enough for scanning electron microscopes. (author)

  14. RF Gun Optimization Study

    International Nuclear Information System (INIS)

    Alicia Hofler; Pavel Evtushenko

    2007-01-01

    Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. A genetic algorithm (GA) has been successfully used to optimize DC photo injector designs at Cornell University [1] and Jefferson Lab [2]. We propose to apply GA techniques to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize a system that has been benchmarked with beam measurements and simulation

  15. Thermographic analysis of plasma facing components covered by carbon surface layer in tokamaks

    International Nuclear Information System (INIS)

    Gardarein, Jean-Laurent

    2007-01-01

    Tokamaks are reactors based on the thermonuclear fusion energy with magnetic confinement of the plasma. In theses machines, several MW are coupled to the plasma for about 10 s. A large part of this power is directed towards plasma facing components (PFC). For better understanding and control the heat flux transfer from the plasma to the surrounding wall, it is very important to measure the surface temperature of the PFC and to estimate the imposed heat flux. In most of tokamaks using carbon PFC, the eroded carbon is circulating in the plasma and redeposited elsewhere. During the plasma operations, this leads at some locations to the formation of thin or thick carbon layers usually poorly attached to the PFC. These surface layers with unknown thermal properties complicate the calculation of the heat flux from IR surface temperature measurements. To solve this problem, we develop first, inverse method to estimate the heat flux using thermocouple (not sensitive to the carbon surface layers) temperature measurements. Then, we propose a front face pulsed photothermal method allowing an estimation of layers thermal diffusivity, conductivity, effusivity and the thermal contact resistance between the layer and the tile. The principle is to study with an infrared sensor, the cooling of the layer surface after heating by a short laser pulse, this cooling depending on the thermal properties of the successive layers. (author) [fr

  16. Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Cheng, Q.J. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Chen, X. [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Ostrikov, K., E-mail: kostya.ostrikov@csiro.au [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia)

    2011-09-22

    Highlights: > A new and custom-designed bias-enhanced hot-filament chemical vapor deposition system is developed to synthesize vertically aligned carbon nanotubes. > The carbon nanotubes are later treated with nitrogen plasmas. > The electron field emission characteristics of the carbon nanotubes are significantly improved after the nitrogen plasma treatment. > A new physical mechanism is proposed to interpret the improvement of the field emission characteristics. - Abstract: The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 {mu}A/cm{sup 2}) achieved at a low applied field (3.50 V/{mu}m) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.

  17. Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

    International Nuclear Information System (INIS)

    Wang, B.B.; Cheng, Q.J.; Chen, X.; Ostrikov, K.

    2011-01-01

    Highlights: → A new and custom-designed bias-enhanced hot-filament chemical vapor deposition system is developed to synthesize vertically aligned carbon nanotubes. → The carbon nanotubes are later treated with nitrogen plasmas. → The electron field emission characteristics of the carbon nanotubes are significantly improved after the nitrogen plasma treatment. → A new physical mechanism is proposed to interpret the improvement of the field emission characteristics. - Abstract: The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 μA/cm 2 ) achieved at a low applied field (3.50 V/μm) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.

  18. Mole gun injury.

    Science.gov (United States)

    Pistré, V; Rezzouk, J

    2013-09-01

    A mole gun is a weapon, which is used to trap and kill moles. This report provides an overview of the state of knowledge of mole gun injuries, comparable to blast injuries caused by fireworks, explosive or gunshot. Over a 2-year period, the authors reported their experience with ten hand injuries caused by mole gun. Radial side of the hand was often concerned, particularly the thumb. The authors explain their choices in the management of such lesions. Surgery was performed primarily and a large debridement currently seemed to offer the best outcome for the patient. Blast, crush, burns and lacerations may explain the higher rate of amputation to the digits. A long period of physiotherapy, specifically of the hand, was needed before the patient could return to work. This ballistic hand trauma encountered by surgeons requires knowledge and understanding of these injuries. It should be in accordance with firearms law because of severe injuries encountered and possible lethal wounds. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  19. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Effects of carbon wall on the behavior of Heliotron-E plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Noda, N; Mizuuchi, T; Akaishi, K; Senju, T; Kondo, K; Kaneko, H; Motojima, O; Baba, T; Besshou, S; Sato, M

    1989-04-01

    Carbonization was successfully applied to Heliotron-E. Iron-inpurity radiations were strongly reduced with the carbonized wall. Main impacts of the metal reduction on plasma behaviors are sustainment of stored energy during high power, long pulse heating by NBI, achievement of a quasi-steady discharge with a low helical field and high beta, and highest electron density with pellet injection in a quasi-steady state. Hydrogen recycling was very high with the carbonized wall and low density operation was impossible. Helium glow discharge was found to be effective to control the hydrogen recycling with a carbon-tiled wall. (orig.).

  1. Middle Ground on Gun Control

    Science.gov (United States)

    2016-12-01

    34 Australian Institute of Criminology, July 7, 2015, http://www.aic.gov.au/ statistics /homicide/weapon.html. 0 100 200 300 400 500 600 700 Total Gun...firearms is not the business of a single Australian , so it is immeasurably easier for politicians to categorically ban types of guns because there is...not an Australian version of Smith and Wesson that is going to be put out of business . Additionally, because all of the guns in Australia are

  2. Recent progress in solution plasma-synthesized-carbon-supported catalysts for energy conversion systems

    Science.gov (United States)

    Lun Li, Oi; Lee, Hoonseung; Ishizaki, Takahiro

    2018-01-01

    Carbon-based materials have been widely utilized as the electrode materials in energy conversion and storage technologies, such as fuel cells and metal-air batteries. In these systems, the oxygen reduction reaction is an important step that determines the overall performance. A novel synthesis route, named the solution plasma process, has been recently utilized to synthesize various types of metal-based and heteroatom-doped carbon catalysts. In this review, we summarize cutting-edge technologies involving the synthesis and modeling of carbon-supported catalysts synthesized via solution plasma process, followed by current progress on the electrocatalytic performance of these catalysts. This review provides the fundamental and state-of-the-art performance of solution-plasma-synthesized electrode materials, as well as the remaining scientific and technological challenges for this process.

  3. Formation of vertically aligned carbon nanostructures in plasmas: numerical modelling of growth and energy exchange

    Energy Technology Data Exchange (ETDEWEB)

    Denysenko, I; Azarenkov, N A, E-mail: idenysenko@yahoo.com [School of Physics and Technology, V N Karazin Kharkiv National University, 4 Svobody sq., 61077 Kharkiv (Ukraine)

    2011-05-04

    Results on modelling of the plasma-assisted growth of vertically aligned carbon nanostructures and of the energy exchange between the plasma and the growing nanostructures are reviewed. Growth of carbon nanofibres and single-walled carbon nanotubes is considered. Focus is made on studies that use the models based on mass balance equations for species, which are adsorbed on catalyst nanoparticles or walls of the nanostructures. It is shown that the models can be effectively used for the study and optimization of nanostructure growth in plasma-enhanced chemical vapour deposition. The results from these models are in good agreement with the available experimental data on the growth of nanostructures. It is discussed how input parameters for the models may be obtained.

  4. Synthesis and characterization of carbon coated nanoparticles produced by a continuous low-pressure plasma process

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, Vineet; Neergat, Manoj [Indian Institute of Technology Bombay, Department of Energy Science and Engineering (India); Bhandarkar, Upendra, E-mail: bhandarkar@iitb.ac.in [Indian Institute of Technology Bombay, Department of Mechanical Engineering (India)

    2011-09-15

    Core-shell nanoparticles coated with carbon have been synthesized in a single chamber using a continuous and entirely low-pressure plasma-based process. Nanoparticles are formed in an argon plasma using iron pentacarbonyl Fe(CO){sub 5} as a precursor. These particles are trapped in a pure argon plasma by shutting off the precursor and then coated with carbon by passing acetylene along with argon as the main background gas. Characterization of the particles was carried out using TEM for morphology, XPS for elemental composition and PPMS for magnetic properties. Iron nanoparticles obtained were a mixture of FeO and Fe{sub 3}O{sub 4}. TEM analysis shows an average size of 7-14 nm for uncoated particles and 15-24 nm for coated particles. The effect of the carbon coating on magnetic properties of the nanoparticles is studied in detail.

  5. Dynamics of C2 formation in laser-produced carbon plasma in helium environment

    International Nuclear Information System (INIS)

    Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.; Polek, M.

    2011-01-01

    We investigated the role of helium ambient gas on the dynamics of C 2 species formation in laser-produced carbon plasma. The plasma was produced by focusing 1064 nm pulses from an Nd:YAG laser onto a carbon target. The emission from the C 2 species was studied using optical emission spectroscopy, and spectrally resolved and integrated fast imaging. Our results indicate that the formation of C 2 in the plasma plume is strongly affected by the pressure of the He gas. In vacuum, the C 2 emission zone was located near the target and C 2 intensity oscillations were observed both in axial and radial directions with increasing the He pressure. The oscillations in C 2 intensity at higher pressures in the expanding plume could be caused by various formation zones of carbon dimers.

  6. Simulation calculations of physical sputtering and reflection coefficient of plasma-irradiated carbon surface

    International Nuclear Information System (INIS)

    Kawamura, T.; Ono, T.; Yamamura, Y.

    1994-08-01

    Physical sputtering yields from the carbon surface irradiated by the boundary plasma are obtained with the use of a Monte Carlo simulation code ACAT. The yields are calculated for many random initial energy and angle values of incident protons or deuterons with a Maxwellian velocity distribution, and then averaged. Here the temperature of the boundary plasma, the sheath potential and the angle δ between the magnetic field line and the surface normal are taken into account. A new fitting formula for an arrangement of the numerical data of sputtering yield is introduced, in which six fitting parameters are determined from the numerical results and listed. These results provide a way to estimate the erosion of carbon materials irradiated by boundary plasma. The particle reflection coefficients for deuterons and their neutrals from a carbon surface are also calculated by the same code and presented together with, for comparison, that for the case of monoenergetic normal incidence. (author)

  7. A Study of Atmospheric Plasma Treatment on Surface Energetics of Carbon Fibers

    International Nuclear Information System (INIS)

    Park, Soo Jin; Chang, Yong Hwan; Moon, Cheol Whan; Suh, Dong Hack; Im, Seung Soon; Kim, Yeong Cheol

    2010-01-01

    In this study, the atmospheric plasma treatment with He/O 2 was conducted to modify the surface chemistry of carbon fibers. The effects of plasma treatment parameters on the surface energetics of carbon fibers were experimentally investigated with respect to gas flow ratio, power intensity, and treatment time. Surface characteristics of the carbon fibers were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Zeta-potential, and contact angle measurements. The results indicated that oxygen plasma treatment led to a large amount of reactive functional groups onto the fiber surface, and these groups can form together as physical intermolecular bonding to improve the surface wettability with a hydrophilic polymer matrix

  8. The ALS gun electronics system

    International Nuclear Information System (INIS)

    Lo, C.C.

    1993-01-01

    The ALS Gun Electronics system has been designed to accommodate the gun with a custom made socket and a high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

  9. The ALS Gun Electronics system

    International Nuclear Information System (INIS)

    Lo, C.C.

    1993-05-01

    The ALS Gun Electronics system has been designed to accommodate gun with a custom made socket and high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

  10. Amorphous hydrogenated carbon films treated by SF{sub 6} plasma

    Energy Technology Data Exchange (ETDEWEB)

    Marins, N M S; Mota, R P; Santos, D C R; Honda, R Y; Kayama, M E; Kostov, K G; Algatti, M A [Laboratorio de Plasma, Faculdade de Engenharia, UNESP, Av. Dr. Ariberto Pereira da Cunha-333, 12516-410, Guaratingueta, SP (Brazil); Cruz, N C; Rangel, E C, E-mail: nazir@feg.unesp.b [Laboratorio de Plasmas Tecnologicos, Unidade Diferenciada Sorocaba/Ipero, UNESP, Av. Tres de Marco-511, 18085-180, Sorocaba, SP (Brazil)

    2009-05-01

    This work was performed to verify the chemical structure, mechanical and hydrophilic properties of amorphous hydrogenated carbon films prepared by plasma enhanced chemical vapor deposition, using acetylene/argon mixture as monomer. Films were prepared in a cylindrical quartz reactor, fed by 13.56 MHz radiofrequency. The films were grown during 5 min, for power varying from 25 to 125 W at a fixed pressure of 9.5 Pa. After deposition, all samples were treated by SF{sub 6} plasma with the aim of changing their hydrophilic character. Film chemical structure investigated by Raman spectroscopy, revealed the increase of sp{sup 3} hybridized carbon bonds as the plasma power increases. Hardness measurements performed by the nanoindentation technique showed an improvement from 5 GPa to 14 GPa following the increase discharge power. The untreated films presented a hydrophilic character, which slightly diminished after SF{sub 6} plasma treatment.

  11. Understanding and Predicting Gun Barrel Erosion

    National Research Council Canada - National Science Library

    Johnston, Ian A

    2005-01-01

    The Australian Defence Force will soon have to contend with gun barrel erosion issues arising from the use of new low-vulnerability gun propellants, the acquisition of new ammunition and gun systems...

  12. Influence of plasma treatment of carbon blacks on electrochemical activity of Pt/carbon blacks catalysts for DMFCs

    Science.gov (United States)

    Kim, Seok; Cho, Mi-Hwa; Lee, Jae-Rock; Park, Soo-Jin

    In this work, in order to improve the dispersion of platinum catalysts deposited on carbon materials, the effects of surface plasma treatment of carbon blacks (CBs) were investigated. The surface characteristics of the CBs were determined by fourier transformed-infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Boehm's titration method. The electrochemical properties of the plasma-treated CBs-supported Pt (Pt/CBs) catalysts were analyzed by linear sweep voltammetry (LSV) experiments. From the results of FT-IR and acid-base values, N 2-plasma treatment of the CBs at 300 W intensity led to a formation of a free radical on the CBs. The peak intensity increased with increase of the treatment time, due to the formation of new basic functional groups (such as C-N, C dbnd N, -NH 3 +, -NH, and dbnd NH) by the free radical on the CBs. Accordingly, the basic values were enhanced by the basic functional groups. However, after a specific reaction time, N 2-plasma treatment could hardly influence on change of the surface functional groups of CBs, due to the disappearance of free radical. Consequently, it was found that optimal treatment time was 30 s for the best electro activity of Pt/CBs catalysts and the N 2-plasma treated Pt/CBs possessed the better electrochemical properties than the pristine Pt/CBs.

  13. TNSA and ponderomotive plasma production in enriched carbon polyethylene foils

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Cutroneo, Mariapompea; Ullschmied, Jiří

    2017-01-01

    Roč. 24, č. 4 (2017), č. článku 043112. ISSN 1070-664X R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 ; RVO:68378271 Keywords : pulsed laser * ablation * nanotubes Subject RIV: BL - Plasma and Gas Discharge Physics; BH - Optics, Masers, Lasers (FZU-D) OBOR OECD: Fluids and plasma physics (including surface physics); Optics (including laser optics and quantum optics) (FZU-D) Impact factor: 2.115, year: 2016

  14. Surface and corrosion characteristics of carbon plasma implanted and deposited nickel-titanium alloy

    International Nuclear Information System (INIS)

    Poon, R.W.Y.; Liu, X.Y.; Chung, C.Y.; Chu, P.K.; Yeung, K.W.K.; Lu, W.W.; Cheung, K.M.C.

    2005-01-01

    Nickel-titanium shape memory alloys (NiTi) are potentially useful in orthopedic implants on account of their super-elastic and shape memory properties. However, the materials are prone to surface corrosion and the most common problem is out-diffusion of harmful Ni ions from the substrate into body tissues and fluids. In order to improve the corrosion resistance and related surface properties, we used the technique of plasma immersion ion implantation and deposition to deposit an amorphous hydrogenated carbon coating onto NiTi and implant carbon into NiTi. Both the deposited amorphous carbon film and carbon plasma implanted samples exhibit much improved corrosion resistances and surface mechanical properties and possible mechanisms are suggested

  15. Electrical Characteristics of Carbon Nanotubes by Plasma and Microwave Surface Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sangjin; Lee, Soonbo; Boo, Jinhyo [Sungkyunkwan Univ., Suwon (Korea, Republic of); Shrestha, Shankar Prasad [Tribhuvan Univ., Kathmandu (Nepal)

    2014-03-15

    The plasma and microwave surface treatments of carbon nanotubes that loaded on plastic substrates were carried out with expecting a change of carbon nanotube dispersion by increasing treatment time. The microwave treatment process was undergone by commercial microwave oven (800 W). The electrical property was measured by hall measurement and resistance was increased by increasing O{sub 2} flow rate of plasma, suggesting an improvement of carbon nanotube dispersion and a possibility of controlling the resistances of carbon nanotubes by plasma surface treatment. The resistance was increased in both polyethylene terephthalate and polyimide substrates by increasing O{sub 2} flow rate. Resistance changes only slightly with different O{sub 2} flow treatment in measure rho for all polyimide samples. Sheet resistance is lowest in polyimide substrate not due to high carbon nanotube loading but due to tendency to remain in elongated structure. O{sub 2} or N{sub 2} plasma treatments on both polyethylene terephthalate and polyimide substrates lead to increase in sheet resistance.

  16. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  17. Electromagnetic compression gun for hypervelocity projectile acceleration

    International Nuclear Information System (INIS)

    Woo, J.T.

    1987-01-01

    The rapid acceleration of projectiles to very high velocities has applications in many areas. The general requirements for an effective system is simplicity, reliability, compactness and good efficiency. The authors developed a concept by using electromagnetic forces to compressionally heat a plasma to high temperature and pressure to serve as the propellant for the acceleration of projectiles. The concept shares the simplicity of the light gas gun, but because of the high temperature of the propellant, is capable of significantly higher performance. Unlike the electrothermal gun approach to raise the propellant temperature by resistive heating, the electromagnetic concept is more efficient at higher temperatures. Operationally, the concept resembles a railgun in requiring a large pulsed current to drive the system. However, the current flow in this case is entirely external to the gun barrel and is axisymmetric. Therefore, many of the problems associated with railgun operations are avoided. Furthermore, because the current channel is external, there is also greater flexibility in the choice of load impedance to match to the power supply. The concept can also be generalized to a multi-stage regenerative system driven by a pulse forming network to resemble a coaxial accelerator

  18. Preparation of targets using electron gun systems

    International Nuclear Information System (INIS)

    Maier-Komor, P.

    1975-01-01

    Most targets of isotopes with very low vapor pressure can only be fabricated by vacuum deposition using an electron gun system or a heavy ion sputtering system. Heavy ion sputtering is a very new technique with many unsolved problems. Therefore it seems to be easier to work with an electron gun. Different commercially available electron guns, which are all designed for the high evaporation rates used in industry, are examined for their qualification in processing small amounts of material as used in fabrication of isotope targets. Electron backscattering and the associated efficiency of the electron beam power is strongly dependent on the atomic number Z of the evaporant and the incident angle of the electron beam on the surface of the evaporant. This dependence leads also to the undesired effects to the target layers from electrons and ions. Some precautions are necessary against the effects of the electrons and ions, which are formed in the plasma directly over the beam impact point. Beam power and beam density have to be chosen to get a constant evaporation rate and a low enough condensation rate in order not to overheat the target substrates. To evaporate some metals it may be helpful to pulse the electron beam

  19. Determination of the Basis for Temperature Compensation in ETC Ignited Solid Propellant Guns

    National Research Council Canada - National Science Library

    Pesce-Rodriguez, R. A; Beyer, R. A

    2004-01-01

    A series of experiments and reanalysis of previously published results has led to the discovery of the key interaction between the plasma of an electrothermal igniter and the gun propellant in large caliber cannon...

  20. Hydrogen retention in carbon-tungsten co-deposition layer formed by hydrogen RF plasma

    International Nuclear Information System (INIS)

    Katayama, K.; Kawasaki, T.; Manabe, Y.; Nagase, H.; Takeishi, T.; Nishikawa, M.

    2006-01-01

    Carbon-tungsten co-deposition layers (C-W layers) were formed by sputtering method using hydrogen or deuterium RF plasma. The deposition rate of the C-W layer by deuterium plasma was faster than that by hydrogen plasma, where the increase of deposition rate of tungsten was larger than that of carbon. This indicates that the isotope effect on sputtering-depositing process for tungsten is larger than that for carbon. The release curve of hydrogen from the C-W layer showed two peaks at 400 deg. C and 700 deg. C. Comparing the hydrogen release from the carbon deposition layer and the tungsten deposition layer, it is considered that the increase of the release rate at 400 deg. C is affected by tungsten and that at 700 deg. C is affected by carbon. The obtained hydrogen retention in the C-W layers which have over 60 at.% of carbon was in the range between 0.45 and 0.16 as H/(C + W)

  1. Platinum catalyst formed on carbon nanotube by the in-liquid plasma method for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Show, Yoshiyuki; Hirai, Akira; Almowarai, Anas; Ueno, Yutaro

    2015-12-01

    In-liquid plasma was generated in the carbon nanotube (CNT) dispersion fluid using platinum electrodes. The generated plasma spattered the surface of the platinum electrodes and dispersed platinum particles into the CNT dispersion. Therefore, the platinum nanoparticles were successfully formed on the CNT surface in the dispersion. The platinum nanoparticles were applied to the proton exchange membrane fuel cell (PEMFC) as a catalyst. The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method. - Highlights: • The platinum catalyst was successfully formed on the CNT surface in the dispersion by the in-liquid plasma method. • The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method.

  2. Gun Concerns Personal for Duncan

    Science.gov (United States)

    McNeil, Michele

    2013-01-01

    As U.S. Secretary of Education Arne Duncan works with other Obama administration officials on policy responses to the shootings at a Connecticut elementary school, he brings a personal and professional history that has acquainted him with the impact of gun violence. As schools chief in Chicago from 2001 to 2008, he was affected by the gun deaths…

  3. Carbon-enhanced inductively coupled plasma mass spectrometric detection of arsenic and selenium and its application to arsenic speciation

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Sturup, Stefan

    1994-01-01

    Addition of carbon as methanol or ammonium carbonate to the aqueous analyte solutions in combination with increased plasma power input enhanced the inductively coupled plasma mass spectrometry (ICP-MS) signal intensities of arsenic and selenium. In the presence of the optimum 3% v/v methanol...... (noise) was not increased. Therefore, the observed increase in analyte sensitivity led to a similar increase in signal-to-noise ratio. The addition of carbon as ammonium carbonate enhanced the arsenic signal by a similar factor but caused severe contamination of the ICP-MS instrument by carbon. In the 3....../nebulization efficiency. It is proposed that an increased population of carbon ions or carbon-containing ions in the plasma facilitates a more complete ionization of analytes lower in ionization energy than carbon itself. The enhanced detection power for arsenic was applied to arsenic speciation by high...

  4. Surface modification of polyester fabric with plasma pretreatment and carbon nanotube coating for antistatic property improvement

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.X., E-mail: cxwang@mail.dhu.edu.cn [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224051 (China); Collaborative Innovation Center for Ecological Building Materials and Environmental Protection Equipments, Jiangsu 224051 (China); Key Laboratory for Advanced Technology in Environmental Protection, Jiangsu 224051 (China); Lv, J.C. [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224051 (China); Ren, Y. [School of Textile and Clothing, Nantong University, Jiangsu 226019 (China); Zhi, T.; Chen, J.Y.; Zhou, Q.Q. [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224051 (China); Lu, Z.Q.; Gao, D.W. [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224051 (China); Collaborative Innovation Center for Ecological Building Materials and Environmental Protection Equipments, Jiangsu 224051 (China); Key Laboratory for Advanced Technology in Environmental Protection, Jiangsu 224051 (China); Jin, L.M. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)

    2015-12-30

    Graphical abstract: - Highlights: • PET was finished by plasma treatment and SWCNT coating to improve antistatic property. • Plasma modification had a positive effect on SWCNT coating on PET fiber surface. • O{sub 2} plasma was more effective in SWCNT coating than Ar plasma in the shorter time. • Antistatic enhanced and then declined with enhancing treatment time and output power. • Antistatic increased with increasing concentration, curing time, curing temperature. - Abstract: This study introduced a green method to prepare antistatic polyester (PET) fabrics by plasma pretreatment and single-walled carbon nanotube (SWCNT) coating. The influences of plasma conditions and SWCNT coating parameters on antistatic property of PET fabrics were investigated. PET fabrics were pretreated under various plasma conditions such as different treatment times, output powers and working gases, and then SWCNT coating on the plasma treated PET fabrics was carried out by coating-dry-cure using various coating parameters including different SWCNT concentrations, curing times and curing temperatures. PET fabrics were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and volume resistivity. SEM and XPS analysis of the plasma treated PET fabrics revealed the increase in surface roughness and oxygen/nitrogen containing groups on the PET fiber surface. SEM and XPS analysis of the plasma treated and SWCNT coated PET fabrics indicated the SWCNT coating on PET fiber surface. The plasma treated and SWCNT coated PET fabrics exhibited a good antistatic property, which increased and then decreased with the increasing plasma treatment time and output power. The antistatic property of the O{sub 2} plasma treated and SWCNT coated PET fabric was better and worse than that of N{sub 2} or Ar plasma treated and SWCNT coated PET fabric in the shorter treatment time and the longer treatment time, respectively. In addition, the antistatic property of the

  5. Surface modification of polyester fabric with plasma pretreatment and carbon nanotube coating for antistatic property improvement

    International Nuclear Information System (INIS)

    Wang, C.X.; Lv, J.C.; Ren, Y.; Zhi, T.; Chen, J.Y.; Zhou, Q.Q.; Lu, Z.Q.; Gao, D.W.; Jin, L.M.

    2015-01-01

    Graphical abstract: - Highlights: • PET was finished by plasma treatment and SWCNT coating to improve antistatic property. • Plasma modification had a positive effect on SWCNT coating on PET fiber surface. • O 2 plasma was more effective in SWCNT coating than Ar plasma in the shorter time. • Antistatic enhanced and then declined with enhancing treatment time and output power. • Antistatic increased with increasing concentration, curing time, curing temperature. - Abstract: This study introduced a green method to prepare antistatic polyester (PET) fabrics by plasma pretreatment and single-walled carbon nanotube (SWCNT) coating. The influences of plasma conditions and SWCNT coating parameters on antistatic property of PET fabrics were investigated. PET fabrics were pretreated under various plasma conditions such as different treatment times, output powers and working gases, and then SWCNT coating on the plasma treated PET fabrics was carried out by coating-dry-cure using various coating parameters including different SWCNT concentrations, curing times and curing temperatures. PET fabrics were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and volume resistivity. SEM and XPS analysis of the plasma treated PET fabrics revealed the increase in surface roughness and oxygen/nitrogen containing groups on the PET fiber surface. SEM and XPS analysis of the plasma treated and SWCNT coated PET fabrics indicated the SWCNT coating on PET fiber surface. The plasma treated and SWCNT coated PET fabrics exhibited a good antistatic property, which increased and then decreased with the increasing plasma treatment time and output power. The antistatic property of the O 2 plasma treated and SWCNT coated PET fabric was better and worse than that of N 2 or Ar plasma treated and SWCNT coated PET fabric in the shorter treatment time and the longer treatment time, respectively. In addition, the antistatic property of the plasma treated

  6. Preventing gun injuries in children.

    Science.gov (United States)

    Crossen, Eric J; Lewis, Brenna; Hoffman, Benjamin D

    2015-02-01

    Firearms are involved in the injury and death of a large number of children each year from both intentional and unintentional causes. Gun ownership in homes with children is common, and pediatricians should incorporate evidence-based means to discuss firearms and protect children from gun-related injuries and violence. Safe storage of guns, including unloaded guns locked and stored separately from ammunition, can decrease risks to children, and effective tools are available that pediatricians can use in clinical settings to help decrease children's access to firearms. Furthermore, several community-based interventions led by pediatricians have effectively reduced firearm-related injury risks to children. Educational programs that focus on children's behavior around guns have not proven effective. © American Academy of Pediatrics, 2015. All rights reserved.

  7. LCLS Gun Solenoid Design Considerations

    International Nuclear Information System (INIS)

    Schmerge, John

    2010-01-01

    The LCLS photocathode rf gun requires a solenoid immediately downstream for proper emittance compensation. Such a gun and solenoid have been operational at the SSRL Gun Test Facility (GTF) for over eight years. Based on magnetic measurements and operational experience with the GTF gun solenoid multiple modifications are suggested for the LCLS gun solenoid. The modifications include adding dipole and quadrupole correctors inside the solenoid, increasing the bore to accommodate the correctors, decreasing the mirror plate thickness to allow the solenoid to move closer to the cathode, cutouts in the mirror plate to allow greater optical clearance with grazing incidence cathode illumination, utilizing pancake coil mirror images to compensate the first and second integrals of the transverse fields and incorporating a bipolar power supply to allow for proper magnet standardization and quick polarity changes. This paper describes all these modifications plus the magnetic measurements and operational experience leading to the suggested modifications.

  8. Surprising synthesis of nanodiamond from single-walled carbon nanotubes by the spark plasma sintering process

    Science.gov (United States)

    Mirzaei, Ali; Ham, Heon; Na, Han Gil; Kwon, Yong Jung; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo

    2016-10-01

    Nanodiamond (ND) was successfully synthesized using single-walled carbon nanotubes (SWCNTs) as a pure solid carbon source by means of a spark plasma sintering process. Raman spectra and X-ray diffraction patterns revealed the generation of the cubic diamond phase by means of the SPS process. Lattice-resolved TEM images confirmed that diamond nanoparticles with a diameter of about ˜10 nm existed in the products. The NDs were generated mainly through the gas-phase nucleation of carbon atoms evaporated from the SWCNTs. [Figure not available: see fulltext.

  9. Growth of carbon allotropes and plasma characterization in linear antenna microwave plasma CVD system

    Czech Academy of Sciences Publication Activity Database

    Potocký, Štěpán; Babchenko, Oleg; Davydova, Marina; Ižák, Tibor; Čada, Martin; Kromka, Alexander

    2014-01-01

    Roč. 53, č. 5 (2014), "05FP04-1"-"05FP04-3" ISSN 0021-4922 R&D Projects: GA TA ČR TA01011740; GA ČR GAP205/12/0908 Grant - others:AVČR(CZ) M100100902 Institutional support: RVO:68378271 Keywords : antenna linear * CVD system * plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.127, year: 2014

  10. Electric arc welding gun

    Science.gov (United States)

    Luttrell, Edward; Turner, Paul W.

    1978-01-01

    This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

  11. Coaxial gun parameters and X-ray emission

    International Nuclear Information System (INIS)

    Soliman, H.M.; El-Aragi, G.M.; Saudy, A.H.; Masoud, M.M.

    1994-01-01

    The paper presents the results of investigation with 3 kJ coaxial plasma gun, which operated with argon gas at pressure 0.8 torr. The coaxial plasma gun parameters are investigated by pick up coils, double electric probe, and x-ray probe. The mean electron temperature and density of the ejected plasma are 25 eV and 10 15 cm -3 respectively. The maximum kinetic pressure of the ejected plasma in the expansion chamber appears after 10 μs from the start of the discharge current. The energetic electrons is detected by an x-ray probe which showed a single pulse of electrons with energy ≅ 3 Kev. (orig.)

  12. Microwave plasma induced surface modification of diamond-like carbon films

    Science.gov (United States)

    Rao Polaki, Shyamala; Kumar, Niranjan; Gopala Krishna, Nanda; Madapu, Kishore; Kamruddin, Mohamed; Dash, Sitaram; Tyagi, Ashok Kumar

    2017-12-01

    Tailoring the surface of diamond-like carbon (DLC) film is technically relevant for altering the physical and chemical properties, desirable for useful applications. A physically smooth and sp3 dominated DLC film with tetrahedral coordination was prepared by plasma-enhanced chemical vapor deposition technique. The surface of the DLC film was exposed to hydrogen, oxygen and nitrogen plasma for physical and chemical modifications. The surface modification was based on the concept of adsorption-desorption of plasma species and surface entities of films. Energetic chemical species of microwave plasma are adsorbed, leading to desorbtion of the surface carbon atoms due to energy and momentum exchange. The interaction of such reactive species with DLC films enhanced the roughness, surface defects and dangling bonds of carbon atoms. Adsorbed hydrogen, oxygen and nitrogen formed a covalent network while saturating the dangling carbon bonds around the tetrahedral sp3 valency. The modified surface chemical affinity depends upon the charge carriers and electron covalency of the adsorbed atoms. The contact angle of chemically reconstructed surface increases when a water droplet interacts either through hydrogen or van dear Waals bonding. These weak interactions influenced the wetting property of the DLC surface to a great extent.

  13. High throughput deposition of hydrogenated amorphous carbon coatings on rubber with expanding thermal plasma

    NARCIS (Netherlands)

    Pei, Y.T.; Eivani, A.R.; Zaharia, T.; Kazantis, A.V.; Sanden, van de M.C.M.; De Hosson, J.T.M.

    2014-01-01

    Flexible hydrogenated amorphous carbon (a-C:H) thin film coated on rubbers has shown outstanding protection of rubber seals from friction and wear. This work concentrates on the potential advances of expanding thermal plasma (ETP) process for a high throughput deposition of a-C:H thin films in

  14. Fast nanostructured carbon microparticle synthesis by one-step high-flux plasma processing

    NARCIS (Netherlands)

    Aussems, D. U. B.; Bystrov, K.; Dogan, I.; Arnas, C.; Cabié, M.; Neisius, T.; Rasinski, M.; Zoethout, E.; Lipman, P.; van de Sanden, M. C. M.; Morgan, T. W.

    2017-01-01

    This study demonstrates a fast one-step synthesis method for nanostructured carbon microparticles on graphite samples using high-flux plasma exposure. These structures are considered as potential candidates for energy applications such as Li-ion batteries and supercapacitors. The samples were

  15. Fast nanostructured carbon microparticle synthesis by one-step high-flux plasma processing

    NARCIS (Netherlands)

    Aussems, D.U.B.; Bystrov, K.E.; Doǧan, I.; Arnas, C.; Cabié, M.; Neisius, T.; Rasinski, M.; Lipman, P.J.L.; van de Sanden, M.C.M.; Morgan, T.W.

    This study demonstrates a fast one-step synthesis method for nanostructured carbon microparticles on graphite samples using high-flux plasma exposure. These structures are considered as potential candidates for energy applications such as Li-ion batteries and supercapacitors. The samples were

  16. Radiative losses and electron cooling rates for carbon and oxygen plasma impurities

    International Nuclear Information System (INIS)

    Marchand, R.; Bonnin, X.

    1992-01-01

    Radiative losses and electron cooling rates are calculated for carbon and oxygen ions under conditions relevant to fusion plasmas. Both rates are calculated with the most recent recommended atomic data. A modified coronal model which includes the effects of metastable states is described and used to calculate the rates. Comparisons with other approaches are also discussed. (author). 36 ref, figs

  17. Planarization of the diamond film surface by using the hydrogen plasma etching with carbon diffusion process

    International Nuclear Information System (INIS)

    Kim, Sung Hoon

    2001-01-01

    Planarization of the free-standing diamond film surface as smooth as possible could be obtained by using the hydrogen plasma etching with the diffusion of the carbon species into the metal alloy (Fe, Cr, Ni). For this process, we placed the free-standing diamond film between the metal alloy and the Mo substrate like a metal-diamond-molybdenum (MDM) sandwich. We set the sandwich-type MDM in a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system. The sandwich-type MDM was heated over ca. 1000 .deg. C by using the hydrogen plasma. We call this process as the hydrogen plasma etching with carbon diffusion process. After etching the free-standing diamond film surface, we investigated surface roughness, morphologies, and the incorporated impurities on the etched diamond film surface. Finally, we suggest that the hydrogen plasma etching with carbon diffusion process is an adequate etching technique for the fabrication of the diamond film surface applicable to electronic devices

  18. Controlled gas-liquid interfacial plasmas for synthesis of nano-bio-carbon conjugate materials

    Science.gov (United States)

    Kaneko, Toshiro; Hatakeyama, Rikizo

    2018-01-01

    Plasmas generated in contact with a liquid have been recognized to be a novel reactive field in nano-bio-carbon conjugate creation because several new chemical reactions have been yielded at the gas-liquid interface, which were induced by the physical dynamics of non-equilibrium plasmas. One is the ion irradiation to a liquid, which caused the spatially selective dissociation of the liquid and the generation of additive reducing and oxidizing agents, resulting in the spatially controlled synthesis of nanostructures. The other is the electron irradiation to a liquid, which directly enhanced the reduction action at the plasma-liquid interface, resulting in temporally controlled nanomaterial synthesis. Using this novel reaction field, gold nanoparticles with controlled interparticle distance were synthesized using carbon nanotubes as a template. Furthermore, nanoparticle-biomolecule conjugates and nanocarbon-biomolecule conjugates were successfully synthesized by an aqueous-solution contact plasma and an electrolyte plasma, respectively, which were rapid and low-damage processes suitable for nano-bio-carbon conjugate materials.

  19. Thermal Oxidation of a Carbon Condensate Formed in High-Frequency Carbon and Carbon-Nickel Plasma Flow

    Science.gov (United States)

    Churilov, G. N.; Nikolaev, N. S.; Cherepakhin, A. V.; Dudnik, A. I.; Tomashevich, E. V.; Trenikhin, M. V.; Bulina, N. G.

    2018-02-01

    We have reported on the comparative characteristics of thermal oxidation of a carbon condensate prepared by high-frequency arc evaporation of graphite rods and a rod with a hollow center filled with nickel powder. In the latter case, along with different forms of nanodisperse carbon, nickel particles with nickel core-carbon shell structures are formed. It has been found that the processes of the thermal oxidation of carbon condensates with and without nickel differ significantly. Nickel particles with the carbon shell exhibit catalytic properties with respect to the oxidation of nanosized carbon structures. A noticeable difference between the temperatures of the end of the oxidation process for various carbon nanoparticles and nickel particles with the carbon shell has been established. The study is aimed at investigations of the effect of nickel nanoparticles on the dynamics of carbon condensate oxidation upon heating in the argon-oxygen flow.

  20. Fabrication And Properties Of Silver Based Multiwall Carbon Nanotube Composite Prepared By Spark Plasma Sintering Method

    Directory of Open Access Journals (Sweden)

    Lis M.

    2015-06-01

    Full Text Available The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4. The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

  1. Deposition of diamond-like carbon films by plasma source ion implantation with superposed pulse

    International Nuclear Information System (INIS)

    Baba, K.; Hatada, R.

    2003-01-01

    Diamond-like carbon (DLC) films were prepared on silicon wafer substrate by plasma source ion implantation with superposed negative pulse. Methane and acetylene gases were used as working gases for plasma. A negative DC voltage and a negative pulse voltage were superposed and applied to the substrate holder. The DC voltage was changed in the range from 0 to -4 kV and the pulse voltage was changed from 0 to -18 kV. The surface of DLC films was very smooth. The deposition rate of DLC films increased with increasing in superposed DC bias voltage. Carbon ion implantation was confirmed for the DLC film deposited from methane plasma with high pulse voltage. I D /I G ratios of Raman spectroscopy were around 1.5 independent on pulse voltage. The maximum hardness of 20.3 GPa was observed for the film prepared with high DC and high pulse voltage

  2. Microwave plasma chemical synthesis of nanocrystalline carbon film structures and study their properties

    Science.gov (United States)

    Bushuev, N.; Yafarov, R.; Timoshenkov, V.; Orlov, S.; Starykh, D.

    2015-08-01

    The self-organization effect of diamond nanocrystals in polymer-graphite and carbon films is detected. The carbon materials deposition was carried from ethanol vapors out at low pressure using a highly non-equilibrium microwave plasma. Deposition processes of carbon film structures (diamond, graphite, graphene) is defined. Deposition processes of nanocrystalline structures containing diamond and graphite phases in different volume ratios is identified. The solid film was obtained under different conditions of microwave plasma chemical synthesis. We investigated the electrical properties of the nanocrystalline carbon films and identified it's from various factors. Influence of diamond-graphite film deposition mode in non-equilibrium microwave plasma at low pressure on emission characteristics was established. This effect is justified using the cluster model of the structure of amorphous carbon. It was shown that the reduction of bound hydrogen in carbon structures leads to a decrease in the threshold electric field of emission from 20-30 V/m to 5 V/m. Reducing the operating voltage field emission can improve mechanical stability of the synthesized film diamond-graphite emitters. Current density emission at least 20 A/cm2 was obtained. Nanocrystalline carbon film materials can be used to create a variety of functional elements in micro- and nanoelectronics and photonics such as cold electron source for emission in vacuum devices, photonic devices, cathodoluminescent flat display, highly efficient white light sources. The obtained graphene carbon net structure (with a net size about 6 μm) may be used for the manufacture of large-area transparent electrode for solar cells and cathodoluminescent light sources

  3. Spectroscopic investigation of plasma electrolytic borocarburizing on q235 low-carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Zhenjiang Watercraft College, Zhenjiang 212000, Jiangsu (China); Wang, Bin; Wu, Jie [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Jin, Xiaoyue; Du, Jiancheng; Hua, Ming [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-12-01

    Highlights: • The plasma discharge behaviors for PEB/C on steels were evaluated by OES. • Electron temperature, concentration, atomic ionization degree were calculated. • The decomposition mechanism of electrolyte and was analyzed. - Abstract: A plasma electrolytic borocarburizing process (PEB/C) in borax electrolyte with glycerin additive was employed to fabricate a hardening layer on Q235 low-carbon steel. Optical emission spectroscopy (OES) was utilized to investigate the spectroscopy characteristics of plasma discharge around the steel during PEB/C process. Some plasma parameters were calculated in terms of OES. The electron temperature and electron concentration in plasma discharge zone is about 3000–12,000 K and 2 × 10{sup 22} m{sup −3}–1.4 × 10{sup 23} m{sup −3}. The atomic ionization degrees of iron, carbon and boron are 10{sup −16}–10{sup −3}, and 10{sup −23}–10{sup −6}, 10{sup −19}–10{sup −4}, respectively, which depend on discharge time. The surface morphology and cross-sectional microstructure of PEB/C hardening layer were observed, and the electrolyte decomposition and plasma discharge behaviors were discussed.

  4. Spectroscopic investigation of plasma electrolytic borocarburizing on q235 low-carbon steel

    International Nuclear Information System (INIS)

    Liu, Run; Wang, Bin; Wu, Jie; Xue, Wenbin; Jin, Xiaoyue; Du, Jiancheng; Hua, Ming

    2014-01-01

    Highlights: • The plasma discharge behaviors for PEB/C on steels were evaluated by OES. • Electron temperature, concentration, atomic ionization degree were calculated. • The decomposition mechanism of electrolyte and was analyzed. - Abstract: A plasma electrolytic borocarburizing process (PEB/C) in borax electrolyte with glycerin additive was employed to fabricate a hardening layer on Q235 low-carbon steel. Optical emission spectroscopy (OES) was utilized to investigate the spectroscopy characteristics of plasma discharge around the steel during PEB/C process. Some plasma parameters were calculated in terms of OES. The electron temperature and electron concentration in plasma discharge zone is about 3000–12,000 K and 2 × 10 22 m −3 –1.4 × 10 23 m −3 . The atomic ionization degrees of iron, carbon and boron are 10 −16 –10 −3 , and 10 −23 –10 −6 , 10 −19 –10 −4 , respectively, which depend on discharge time. The surface morphology and cross-sectional microstructure of PEB/C hardening layer were observed, and the electrolyte decomposition and plasma discharge behaviors were discussed

  5. Brazing and machining of carbon based materials for plasma facing components

    International Nuclear Information System (INIS)

    Brossa, M.; Guerreschi, U.; Rossi, M.

    1994-01-01

    Carbon based materials in the recent years have often been considered and used as armour material in plasma facing components for several fusion devices, because of their low Z and good high temperature characteristics that are compatible with the operation of nuclear reactors. These materials are often connected (mechanically or by brazing) to metals, that allow the support and the cooling functions (heat sink materials). In the following the experience of Ansaldo Ricerche about the study and the manufacturing of plasma facing components and mockups is described with reference to the influence of the carbon materials in performing brazing junction with metals. It is interesting to observe how the different characteristics of the carbon materials influence the brazing process. ((orig.))

  6. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    International Nuclear Information System (INIS)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-01-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012 © . RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance

  7. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    Energy Technology Data Exchange (ETDEWEB)

    Rimjaem, S., E-mail: sakhorn.rimjaem@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand); Kusoljariyakul, K.; Thongbai, C. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand)

    2014-02-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012{sup ©}. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.

  8. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    Science.gov (United States)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-02-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012©. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.

  9. Gun Shows and Gun Violence: Fatally Flawed Study Yields Misleading Results

    Science.gov (United States)

    Hemenway, David; Webster, Daniel; Pierce, Glenn; Braga, Anthony A.

    2010-01-01

    A widely publicized but unpublished study of the relationship between gun shows and gun violence is being cited in debates about the regulation of gun shows and gun commerce. We believe the study is fatally flawed. A working paper entitled “The Effect of Gun Shows on Gun-Related Deaths: Evidence from California and Texas” outlined this study, which found no association between gun shows and gun-related deaths. We believe the study reflects a limited understanding of gun shows and gun markets and is not statistically powered to detect even an implausibly large effect of gun shows on gun violence. In addition, the research contains serious ascertainment and classification errors, produces results that are sensitive to minor specification changes in key variables and in some cases have no face validity, and is contradicted by 1 of its own authors’ prior research. The study should not be used as evidence in formulating gun policy. PMID:20724672

  10. The Effects of Gun Ownership Rates and Gun Control Laws on Suicide Rates

    OpenAIRE

    Mark Gius

    2011-01-01

    The purpose of the present study is to determine the effects of gun control laws and gun ownership rates on state-level suicide rates. Using the most recent data on suicide rates, gun control measures, and gun ownership rates, the results of the present study suggest that states that require handgun permits have lower gun-related suicide rates, and states that have higher gun ownership rates have higher gun-related suicide rates. Regarding non-gun suicides, results suggest that stricter gun c...

  11. Gun violence trends in movies.

    Science.gov (United States)

    Bushman, Brad J; Jamieson, Patrick E; Weitz, Ilana; Romer, Daniel

    2013-12-01

    Many scientific studies have shown that the mere presence of guns can increase aggression, an effect dubbed the "weapons effect." The current research examines a potential source of the weapons effect: guns depicted in top-selling films. Trained coders identified the presence of violence in each 5-minute film segment for one-half of the top 30 films since 1950 and the presence of guns in violent segments since 1985, the first full year the PG-13 rating (age 13+) was used. PG-13-rated films are among the top-selling films and are especially attractive to youth. Results found that violence in films has more than doubled since 1950, and gun violence in PG-13-rated films has more than tripled since 1985. When the PG-13 rating was introduced, these films contained about as much gun violence as G (general audiences) and PG (parental guidance suggested for young children) films. Since 2009, PG-13-rated films have contained as much or more violence as R-rated films (age 17+) films. Even if youth do not use guns, these findings suggest that they are exposed to increasing gun violence in top-selling films. By including guns in violent scenes, film producers may be strengthening the weapons effect and providing youth with scripts for using guns. These findings are concerning because many scientific studies have shown that violent films can increase aggression. Violent films are also now easily accessible to youth (e.g., on the Internet and cable). This research suggests that the presence of weapons in films might amplify the effects of violent films on aggression.

  12. Argon plasma treatment to enhance the electrochemical reactivity of screen-printed carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ghamouss, F.; Luais, E. [Universite de Nantes, Faculte des Sciences et des Techniques, Chimie et Interdisciplinarite: Synthese, Analyse, Modelisation (CEISAM), UMR CNRS no 6230, 2, rue de la Houssiniere, BP 92208, 44322 NANTES Cedex 3 (France); Universite de Nantes, Institut des Materiaux Jean Rouxel IMN - CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 3 (France); Thobie-Gautier, C. [Universite de Nantes, Faculte des Sciences et des Techniques, Chimie et Interdisciplinarite: Synthese, Analyse, Modelisation (CEISAM), UMR CNRS no 6230, 2, rue de la Houssiniere, BP 92208, 44322 NANTES Cedex 3 (France); Tessier, P.-Y. [Universite de Nantes, Faculte des Sciences et des Techniques, Chimie et Interdisciplinarite: Synthese, Analyse, Modelisation (CEISAM), UMR CNRS no 6230, 2, rue de la Houssiniere, BP 92208, 44322 NANTES Cedex 3 (France); Universite de Nantes, Institut des Materiaux Jean Rouxel IMN - CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 3 (France); Boujtita, M. [Universite de Nantes, Faculte des Sciences et des Techniques, Chimie et Interdisciplinarite: Synthese, Analyse, Modelisation (CEISAM), UMR CNRS no 6230, 2, rue de la Houssiniere, BP 92208, 44322 NANTES Cedex 3 (France)], E-mail: mohammed.boujtita@univ-nantes.fr

    2009-04-15

    Radiofrequency argon plasma was used for screen-printed carbon electrodes (SPCE) surface treatment. The cyclic voltammetry of ferri/ferrocyanide as redox couple showed a remarkable improvement of the electrochemical reactivity of the SPCE after the plasma treatment. The effect of the plasma growth conditions on the efficiency of the treatment procedure was evaluated in term of electrochemical reactivity of the SPCE surface. The electrochemical study showed that the electrochemical reactivity of the treated electrodes was strongly dependant on radiofrequency power, treatment time and argon gas pressure. X-ray photoelectron spectroscopy (XPS) analysis showed a considerable evolution on the surface chemistry of the treated electrodes. Our results clearly showed that the argon plasma treatment induces a significant increase in the C{sub sp2}/C{sub sp3} ratio. The scanning electron micrograph (SEM) also showed a drastic change on the surface morphology of the treated SPCEs.

  13. Room-temperature aqueous plasma electrolyzing Al2O3 nano-coating on carbon fiber

    Science.gov (United States)

    Zhang, Yuping; Meng, Yang; Shen, Yonghua; Chen, Weiwei; Cheng, Huanwu; Wang, Lu

    2017-10-01

    A novel room-temperature aqueous plasma electrolysis technique has been developed in order to prepared Al2O3 nano-coating on each fiber within a carbon fiber bundle. The microstructure and formation mechanism of the Al2O3 nano-coating were systematically investigated. The oxidation resistance and tensile strength of the Al2O3-coated carbon fiber was measured at elevated temperatures. It showed that the dense Al2O3 nano-coating was relatively uniformly deposited with 80-120 nm in thickness. The Al2O3 nano-coating effectively protected the carbon fiber, evidenced by the slower oxidation rate and significant increase of the burn-out temperature from 800 °C to 950 °C. Although the bare carbon fiber remained ∼25 wt.% after oxidation at 700 °C for 20 min, a full destruction was observed, evidenced by the ∼0 GPa of the tensile strength, compared to ∼1.3 GPa of the Al2O3-coated carbon fiber due to the effective protection from the Al2O3 nano-coating. The formation mechanism of the Al2O3 nano-coating on carbon fiber was schematically established mainly based on the physic-chemical effect in the cathodic plasma arc zone.

  14. Superconducting augmented rail gun (SARG)

    International Nuclear Information System (INIS)

    Homan, C.G.; Cummings, C.E.; Fowler, C.M.

    1986-01-01

    Superconducting augmentation consists of a superconducting coil operating in the persistent mode closely coupled magnetically with a normally conducting rail gun. A theoretical investigation of the effect of this system on a rail gun has shown that two benefits occur. Projectile velocities and launch efficiencies increase significantly depending on the magnetic coupling between the rail and augmentation circuits. Previous work evaluated an idealized system by neglecting energy dissipation effects. In this paper, the authors extend the analysis to include the neglected terms and show improved actual launch efficiencies for the SARG configuration. In this paper, the authors discuss details of projectile design in depth and present preliminary results of rail gun performance

  15. Plural beam electron gun assembly

    International Nuclear Information System (INIS)

    Stratton, M.G.

    1977-01-01

    The invention relates to a cathode ray tube plural-beam-in-line bi-potential electron gun assembly, having applied beam currents of differing levels, manifests structurally modified gun structures to effect focused beam landings at the screen that are evidenced as substantially equi-sized spots thereby providing improved resolution and brightness of the screen imagery. The structural changes embody modifications of the related focusing and accelerator electrodes of the respective guns to provide a partial telescoping arrangement for effecting the discrete placement, forming and shielding of the final focusing lenses. The three lenses so formed are in different planes in partial overlapping axial relationship

  16. Gun barrel erosion - Comparison of conventional and LOVA gun propellants

    NARCIS (Netherlands)

    Hordijk, A.C.; Leurs, O.

    2006-01-01

    The research department Energetic Materials within TNO Defence, Security and Safety is involved in the development and (safety and insensitive munitions) testing of conventional (nitro cellulose based) and thermoplastic elastomer (TPE) based gun propellants. Recently our testing capabilities have

  17. Plasma-synthesized single-walled carbon nanotubes and their applications

    International Nuclear Information System (INIS)

    Hatakeyama, R; Kaneko, T; Kato, T; Li, Y F

    2011-01-01

    Plasma-based nanotechnology is a rapidly developing area of research ranging from physics of gaseous and liquid plasmas to material science, surface science and nanofabrication. In our case, nanoscopic plasma processing is performed to grow single-walled carbon nanotubes (SWNTs) with controlled chirality distribution and to further develop SWNT-based materials with new functions corresponding to electronic and biomedical applications. Since SWNTs are furnished with hollow inner spaces, it is very interesting to inject various kinds of atoms and molecules into their nanospaces based on plasma nanotechnology. The encapsulation of alkali-metal atoms, halogen atoms, fullerene or azafullerene molecules inside the carbon nanotubes is realized using ionic plasmas of positive and negative ions such as alkali-fullerene, alkali-halogen, and pair or quasipair ion plasmas. Furthermore, an electrolyte solution plasma with DNA negative ions is prepared in order to encapsulate DNA molecules into the nanotubes. It is found that the electronic and optical properties of various encapsulated SWNTs are significantly changed compared with those of pristine ones. As a result, a number of interesting transport phenomena such as air-stable n- and p-type behaviour, p-n junction characteristic, and photoinduced electron transfer are observed. Finally, the creation of an emerging SWNTs-based nanobioelectronics system is challenged. Specifically, the bottom-up electric-field-assisted reactive ion etching is proposed to control the chirality of SWNTs, unexplored SWNT properties of magnetism and superconductivity are aimed at being pioneered, and innovative biomedical-nanoengineering with encapsulated SWNTs of higher-order structure are expected to be developed by applying advanced gas-liquid interfacial plasmas.

  18. Preliminary analysis of a carbon/carbon-fiber-composite plasma direct converter

    International Nuclear Information System (INIS)

    Gurol, H.; Shuy, G.W.; Dabiri, A.E.; Dirling, R.B. Jr.; Eitman, D.

    1983-05-01

    The feasibility of a PDC that uses radiatively cooled grids and collector plate made of carbon/carbon fiber composite is presented. Elimination of the coolant makes a thin grid design possible. The advantages are increased direct conversion efficiency, no tritium permeation into grid tube coolant, and compact design

  19. Structural and tribological properties of carbon steels modified by plasma pulses

    International Nuclear Information System (INIS)

    Sartowska, B.; Walis, L.; Piekoszewski, J.; Senatorski, J.; Stanislawski, J.; Nowicki, L.; Ratajczak, R.; Barlak, M.; Kopcewicz, M.; Kalinowska, J.; Prokert, F.

    2006-01-01

    Carbon steels with different concentration of carbon and heat (Armco-iron, steels 20, 45, 65 and N9) were treated according to the standard procedures: they were irradiated with five intense (about 5 J/cm 2 ), short (μs range) argon or nitrogen plasma pulses generated in a rod plasma injector (RPI) type of plasma generator. Samples were characterized by the following methods: nuclear reaction analysis (NRA) 14 N(d,α) 12 C , scanning electron microscopy (SEM), conversion electron Moessbauer spectroscopy (CEMS), X-ray diffraction analysis (GXRD), and Amsler wear tests. SEM observations shown that the morphology of the pulse treated samples, both argon and nitrogen plasma are identical. It has been found, that nitrogen is much more efficient than argon in ausenitization of carbon steel. The craters and droplets are uniformly distributed over the surface, which is typical of melted and rapidly recrystallized top layers. The thickness of the modified layers is in the range of 1.2-1.6 μm

  20. Growth of carbon fibres, sheets and tubes on diamond films under high power plasma etching conditions

    Energy Technology Data Exchange (ETDEWEB)

    Villalpando, I. [Centro de Investigacion de los Recursos Naturales, Antigua Normal Rural, Salaices, Lopez, Chihuahua (Mexico); John, P.; Wilson, J. I. B., E-mail: isaelav@hotmail.com [School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14-4AS (United Kingdom)

    2017-11-01

    The application of diamond as a plasma facing material for fusion reactors can be limited by unknown reactions between diamond and the chamber materials transported by the plasma. Transformation of diamond to other structures can cause problems such as contamination of the plasma with loose particles or retention of gases. We have seen that diamond thin films are eroded under hydrogen plasma etching, but if silicon is present the growth of various carbon structures on diamond films is observed. We have produced carbon with different morphologies on diamond films including fibres, sheets with flower-like shapes and tubes and proposed growth mechanisms based on the results of scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Sample surfaces contain silicon and are oxidised having COO and CO groups as seen by XP S analysis. Raman analyses revealed a spectrum typical for graphite combined with that from diamond that remains on the surface after hydrogen bombardment. The results of this sturdy show the experimental conditions in which carbon fibres, sheets and tubes are produced under high-power hydrogen etching of diamond films and open the possibility to other applications such as catalysts, sensors and the production of electrodes. (Author)

  1. Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability.

    Science.gov (United States)

    Struzzi, Claudia; Scardamaglia, Mattia; Hemberg, Axel; Petaccia, Luca; Colomer, Jean-François; Snyders, Rony; Bittencourt, Carla

    2015-01-01

    Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

  2. Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability

    Directory of Open Access Journals (Sweden)

    Claudia Struzzi

    2015-12-01

    Full Text Available Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

  3. Growth of carbon fibres, sheets and tubes on diamond films under high power plasma etching conditions

    International Nuclear Information System (INIS)

    Villalpando, I.; John, P.; Wilson, J. I. B.

    2017-01-01

    The application of diamond as a plasma facing material for fusion reactors can be limited by unknown reactions between diamond and the chamber materials transported by the plasma. Transformation of diamond to other structures can cause problems such as contamination of the plasma with loose particles or retention of gases. We have seen that diamond thin films are eroded under hydrogen plasma etching, but if silicon is present the growth of various carbon structures on diamond films is observed. We have produced carbon with different morphologies on diamond films including fibres, sheets with flower-like shapes and tubes and proposed growth mechanisms based on the results of scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Sample surfaces contain silicon and are oxidised having COO and CO groups as seen by XP S analysis. Raman analyses revealed a spectrum typical for graphite combined with that from diamond that remains on the surface after hydrogen bombardment. The results of this sturdy show the experimental conditions in which carbon fibres, sheets and tubes are produced under high-power hydrogen etching of diamond films and open the possibility to other applications such as catalysts, sensors and the production of electrodes. (Author)

  4. Modeling plasma-assisted growth of graphene-carbon nanotube hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Tewari, Aarti [Department of Applied Physics, Delhi Technological University, Shahbad Daulatpur, Bawana Road, Delhi 110 042 (India)

    2016-08-15

    A theoretical model describing the growth of graphene-CNT hybrid in a plasma medium is presented. Using the model, the growth of carbon nanotube (CNT) on a catalyst particle and thereafter the growth of the graphene on the CNT is studied under the purview of plasma sheath and number density kinetics of different plasma species. It is found that the plasma parameter such as ion density; gas ratios and process parameter such as source power affect the CNT and graphene dimensions. The variation in growth rates of graphene and CNT under different plasma power, gas ratios, and ion densities is analyzed. Based on the results obtained, it can be concluded that higher hydrocarbon ion densities and gas ratios of hydrocarbon to hydrogen favor the growth of taller CNTs and graphene, respectively. In addition, the CNT tip radius reduces with hydrogen ion density and higher plasma power favors graphene with lesser thickness. The present study can help in better understanding of the graphene-CNT hybrid growth in a plasma medium.

  5. Effect of plasma pretreatment on the structure and emission characteristics of carbon nanotubes

    International Nuclear Information System (INIS)

    Uh, Hyung Soo; Lee, Soo Myun; Choi, Seok Rim; Park, Sang Sik; Cho, Euo Sik; Lee, Jong Duk; Kwon, Sang Jik

    2003-01-01

    Carbon nanotubes (CNTs) were grown on Ni-coated TiN/Si substrates by using microwave plasma chemical vapor deposition with a gas mixture of H 2 /CH 4 at a low temperature of 500 .deg. C. The effect of H 2 plasma pretreatment on the diameter of grown CNTs was investigated. We found that the average diameter of CNTs could be easily controlled by using the H 2 -plasma pretreatment time before CNTs growth and varied from 36 nm to 26 nm as the pretreatment time changed from 5 min to 15 min. However, any further increase in the pretreatment time gave rise to a rapid decrease in CNTs growth. After 25 min of the plasma pretreatment, scanning electron microscopy observation exhibited the destruction of the CNTs. The impact of the plasma pretreatment time on the emission behavior of CNTs was also investigated in a diode-type electron-emission configuration. The variation of the CNT diameter due to the plasma pretreatment caused a drastic change in emission properties. The turn-on voltages of CNT emitters varied from 3.5 V/μm to 9 V/μm, depending on the hydrogen-plasma pretreatment conditions. The close relationship between the electron-emission characteristics and the pretreatment time indicates that the pretreatment condition may be a key process parameter in CNTs growth for field-emission displays and should be optimized.

  6. Modeling plasma-assisted growth of graphene-carbon nanotube hybrid

    International Nuclear Information System (INIS)

    Tewari, Aarti

    2016-01-01

    A theoretical model describing the growth of graphene-CNT hybrid in a plasma medium is presented. Using the model, the growth of carbon nanotube (CNT) on a catalyst particle and thereafter the growth of the graphene on the CNT is studied under the purview of plasma sheath and number density kinetics of different plasma species. It is found that the plasma parameter such as ion density; gas ratios and process parameter such as source power affect the CNT and graphene dimensions. The variation in growth rates of graphene and CNT under different plasma power, gas ratios, and ion densities is analyzed. Based on the results obtained, it can be concluded that higher hydrocarbon ion densities and gas ratios of hydrocarbon to hydrogen favor the growth of taller CNTs and graphene, respectively. In addition, the CNT tip radius reduces with hydrogen ion density and higher plasma power favors graphene with lesser thickness. The present study can help in better understanding of the graphene-CNT hybrid growth in a plasma medium.

  7. Experimental Identification of the Kink Instability as a Poloidal Flux Amplification Mechanism for Coaxial Gun Spheromak Formation

    OpenAIRE

    Hsu, S. C.; Bellan, P. M.

    2003-01-01

    The magnetohydrodynamic kink instability is observed and identified experimentally as a poloidal flux amplification mechanism for coaxial gun spheromak formation. Plasmas in this experiment fall into three distinct regimes which depend on the peak gun current to magnetic flux ratio, with (I) low values resulting in a straight plasma column with helical magnetic field, (II) intermediate values leading to kinking of the column axis, and (III) high values leading immediately to a detached plasma...

  8. Characterization of Plasma Synthesized Vertical Carbon Nanofibers for Nanoelectronics Applications

    Science.gov (United States)

    Lee, Jaesung; Feng, Philip X.-L.; Kaul, Anupama B.

    2013-01-01

    We report on the material characterization of carbon nanofibers (CNFs) which are assembled into a three-dimensional (3D) configuration for making new nanoelectromechanical systems (NEMS). High-resolution scanning electron microscopy (SEM) and x-ray electron dispersive spectroscopy (XEDS) are employed to decipher the morphology and chemical compositions of the CNFs at various locations along individual CNFs grown on silicon (Si) and refractory nitride (NbTiN) substrates, respectively. The measured characteristics suggest interesting properties of the CNF bodies and their capping catalyst nanoparticles, and growth mechanisms on the two substrates. Laser irradiation on the CNFs seems to cause thermal oxidation and melting of catalyst nanoparticles. The structural morphology and chemical compositions of the CNFs revealed in this study should aid in the applications of the CNFs to nanoelectronics and NEMS.

  9. Challenges in process integration of catalytic DC plasma synthesis of vertically aligned carbon nanofibres

    International Nuclear Information System (INIS)

    Melechko, Anatoli V; Pearce, Ryan C; Hensley, Dale K; Simpson, Michael L; McKnight, Timothy E

    2011-01-01

    The ability to synthesize free-standing, individual carbon nanofibres (CNFs) aligned perpendicularly to a substrate has enabled fabrication of a large array of devices with nanoscale functional elements, including electron field emission sources, electrochemical probes, neural interface arrays, scanning probes, gene delivery arrays and many others. This was made possible by development of a catalytic plasma process, with DC bias directing the alignment of nanofibres. Successful implementation of prototypical devices has uncovered numerous challenges in the integration of this synthesis process as one of the steps in device fabrication. This paper is dedicated to these engineering and fundamental difficulties that hinder further device development. Relatively high temperature for catalytic synthesis, electrical conductivity of the substrate to maintain DC discharge and other difficulties place restrictions on substrate material. Balancing non-catalytic carbon film deposition and substrate etching, non-uniformity of plasma due to growth of the high aspect ratio structures, plasma instabilities and other factors lead to challenges in controlling the plasma. Ultimately, controlling the atomistic processes at the catalyst nanoparticle (NP) and the behaviour of the NP is the central challenge of plasma nanosynthesis of vertically aligned CNFs.

  10. Biosensor based on laccase immobilized on plasma polymerized allylamine/carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ardhaoui, Malika, E-mail: malika.ardhaoui@ucd.ie [Laboratoire de Génie des Procédés Plasma et Traitements de Surface, Université Pierre et Marie Curie-Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris (France); Laboratoire Charles Friedel, CNRS UMR 7223, Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Surface Engineering Research Group, School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4 (Ireland); Bhatt, Sudhir [Laboratoire de Génie des Procédés Plasma et Traitements de Surface, Université Pierre et Marie Curie-Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris (France); Zheng, Meihui [Laboratoire Charles Friedel, CNRS UMR 7223, Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Dowling, Denis [Surface Engineering Research Group, School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4 (Ireland); Jolivalt, Claude [Laboratoire Charles Friedel, CNRS UMR 7223, Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Khonsari, Farzaneh Arefi [Laboratoire de Génie des Procédés Plasma et Traitements de Surface, Université Pierre et Marie Curie-Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris (France)

    2013-08-01

    In this work, a simple and rapid method was used to functionalize carbon electrode in order to efficiently immobilize laccase for biosensor application. A stable allylamine coating was deposited using a low pressure inductively excited RF tubular plasma reactor under mild plasma conditions (low plasma power (10 W), few minutes) to generate high density amine groups (N/C ratio up to 0.18) on rough carbon surface electrodes. The longer was the allylamine plasma deposition time; the better was the surface coverage. Laccase from Trametes versicolor was physisorbed and covalently bound to these allylamine modified carbon surfaces. The laccase activities and current outputs measured in the presence of 2,2′-azinobis-(3-ethylbenzothiazole-6-sulfonic acid) (ABTS) showed that the best efficiency was obtained for electrode plasma coated during 30 min. They showed also that for all the tested electrodes, the activities and current outputs of the covalently immobilized laccases were twice higher than the physically adsorbed ones. The sensitivity of these biocompatible bioelectrodes was evaluated by measuring their catalytic efficiency for oxygen reduction in the presence of ABTS as non-phenolic redox substrate and 2,6-dimethoxyphenol (DMP) as phenolic one. Sensitivities of around 4.8 μA mg{sup −1} L and 2.7 μA mg{sup −1} L were attained for ABTS and DMP respectively. An excellent stability of this laccase biosensor was observed for over 6 months. - Highlights: • Low pressure plasma was used to generate stable allylamine coating. • Laccase from Trametes versicolor was physisorbed and covalently immobilized. • Best biosensor efficiency obtained for the covalently immobilized laccases • Sensitivities of 4.8 μA mg{sup −1} L and 2.7 μA mg{sup −1} L for ABTS and DMP respectively.

  11. Initial evaluation and comparison of plasma damage to atomic layer carbon materials using conventional and low T{sub e} plasma sources

    Energy Technology Data Exchange (ETDEWEB)

    Jagtiani, Ashish V.; Miyazoe, Hiroyuki; Chang, Josephine; Farmer, Damon B.; Engel, Michael; Neumayer, Deborah; Han, Shu-Jen; Engelmann, Sebastian U., E-mail: suengelm@us.ibm.com; Joseph, Eric A. [IBM, T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Boris, David R.; Hernández, Sandra C.; Walton, Scott G. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Lock, Evgeniya H. [Materials Science and Technology Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-01-15

    The ability to achieve atomic layer precision is the utmost goal in the implementation of atomic layer etch technology. Carbon-based materials such as carbon nanotubes (CNTs) and graphene are single atomic layers of carbon with unique properties and, as such, represent the ultimate candidates to study the ability to process with atomic layer precision and assess impact of plasma damage to atomic layer materials. In this work, the authors use these materials to evaluate the atomic layer processing capabilities of electron beam generated plasmas. First, the authors evaluate damage to semiconducting CNTs when exposed to beam-generated plasmas and compare these results against the results using typical plasma used in semiconductor processing. The authors find that the beam generated plasma resulted in significantly lower current degradation in comparison to typical plasmas. Next, the authors evaluated the use of electron beam generated plasmas to process graphene-based devices by functionalizing graphene with fluorine, nitrogen, or oxygen to facilitate atomic layer deposition (ALD). The authors found that all adsorbed species resulted in successful ALD with varying impact on the transconductance of the graphene. Furthermore, the authors compare the ability of both beam generated plasma as well as a conventional low ion energy inductively coupled plasma (ICP) to remove silicon nitride (SiN) deposited on top of the graphene films. Our results indicate that, while both systems can remove SiN, an increase in the D/G ratio from 0.08 for unprocessed graphene to 0.22 to 0.26 for the beam generated plasma, while the ICP yielded values from 0.52 to 1.78. Generally, while some plasma-induced damage was seen for both plasma sources, a much wider process window as well as far less damage to CNTs and graphene was observed when using electron beam generated plasmas.

  12. Liquid Phase Plasma Synthesis of Iron Oxide/Carbon Composite as Dielectric Material for Capacitor

    Directory of Open Access Journals (Sweden)

    Heon Lee

    2014-01-01

    Full Text Available Iron oxide/carbon composite was synthesized using a liquid phase plasma process to be used as the electrode of supercapacitor. Spherical iron oxide nanoparticles with the size of 5~10 nm were dispersed uniformly on carbon powder surface. The specific capacitance of the composite increased with increasing quantity of iron oxide precipitate on the carbon powder up to a certain quantity. When the quantity of the iron oxide precipitate exceeds the threshold, however, the specific capacitance was rather reduced by the addition of precipitate. The iron oxide/carbon composite containing an optimum quantity (0.33 atomic % of iron oxide precipitate exhibited the smallest resistance and the largest initial resistance slope.

  13. Crystalline and amorphous carbon nitride films produced by high-energy shock plasma deposition

    International Nuclear Information System (INIS)

    Bursilll, L.A.; Peng, Julin; Gurarie, V.N.; Orlov, A.V.; Prawer, S.

    1995-01-01

    High-energy shock plasma deposition techniques are used to produce carbon-nitride films containing both crystalline and amorphous components. The structures are examined by high-resolution transmission electron microscopy, parallel-electron-energy loss spectroscopy and electron diffraction. The crystalline phase appears to be face-centered cubic with unit cell parameter approx. a=0.63nm and it may be stabilized by calcium and oxygen at about 1-2 at % levels. The carbon atoms appear to have both trigonal and tetrahedral bonding for the crystalline phase. There is PEELS evidence that a significant fraction of the nitrogen atoms have sp 2 trigonal bonds in the crystalline phase. The amorphous carbon-nitride film component varies from essentially graphite, containing virtually no nitrogen, to amorphous carbon-nitride containing up to 10 at % N, where the fraction of sp 3 bonds is significant. 15 refs., 5 figs

  14. Calculation of opacities and emissivities for carbon plasmas under NLTE and LTE conditions

    International Nuclear Information System (INIS)

    Gil, J.M.; Rodriguez, R.; Florido, R.; Rubiano, J.G.; Martel, P.; Sauvan, P.; Minguez, E.

    2006-01-01

    We calculate different optical properties for carbon plasma in a wide range of temperatures and densities by using ATOM3R-OP code which has been recently developed. In this code we have implemented the rate equations, the Saha equation (for local thermodynamic equilibrium) and the coronal equilibrium model. We have calculated average ionizations, level populations, opacities and emissivities and we focus our study on the identification with our code of coronal equilibrium, non-local thermodynamic equilibrium and local thermodynamic equilibrium regions for this kind of plasma. Moreover, we analyse the differences in the optical properties when they are calculated in non-local thermodynamic equilibrium and local thermodynamic equilibrium. (authors)

  15. Deposition of coatings on Ti by sputtering of tableted carbonate-hydroxylapatite in HF discharge plasma

    International Nuclear Information System (INIS)

    Khamchukov, Y.D.; Klubovich, V.; Potapenko, I.

    2001-01-01

    The coatings of carbonate-hydroxyapatite (CHA) on materials suitable for implants must have, because of their shielding functions, sufficiently large thickness and good adhesion. For these reasons, the production of these coatings is a technological task whose solution may be obtained on the basis of the application of different ion-plasma technologies. Examination of the properties of the CHA coatings on the substrate of titanium and the effect on the materials of the coating and the substrate of ion-plasma technology with the application of high-frequency discharge was the aim of this investigation

  16. Particle balance analysis on carbon sheet pump applied to the GAMMA10 tandem mirror plasmas

    International Nuclear Information System (INIS)

    Ishimoto, Yuki; Nakashima, Yousuke; Ishinuki, Eiichi; Kobayashi, Shinji; Yoshikawa, Masayuki; Tamano, Teruo; Yatsu, Kiyoshi; Sagara, Akio

    2000-01-01

    Carbon Sheet Pump (CSP) is expected as a tool for reduction of hydrogen recycling. In this paper, particle balance in the CSP is described. The pumping efficiencies estimated from the time evolution of hydrogen pressures during plasma discharges and those estimated from the thermal desorption experiments have no remarkable difference between the cases of 30degC and 200degC within experimental errors. In cases that CSP is used in actual plasma conditions, we established a method which reduces adsorbed gases on the CSP surface with sustaining a sufficient pumping efficiency by continuously heating CSP. (author)

  17. Dielectronic recombination of carbon, oxygen and iron in low-density and high-temperature plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yukiharu; Kasai, Satoshi; Tazima, Teruhiko

    1977-03-01

    The coefficient of dielectronic recombination, which is one of the important atomic processes in tokamak plasmas, is evaluated by a semiclassical method neglecting the effects of the density and the radiation fields. Those of carbon, oxygen and iron, which play important roles in such as plasma resistivity and energy losses, are calculated numerically in the range of the electron temperature of 10 eV - 10 keV. Compared with the results obtained from Burgess equation, which is most useful for the ions with effective nuclear charge z 25 such as molybdenum. (auth.)

  18. Plasma treatment of multiwall carbon nanotubes for dispersion improvement in water

    International Nuclear Information System (INIS)

    Chen Changlun; Ogino, Akihisa; Nagatsu, Masaaki; Wang Xiangke

    2010-01-01

    Microwave excited Ar/H 2 O surface-wave plasma was used to treat multiwall carbon nanotubes (MWCNTs) to modify their surface characteristics and thus improve their dispersion capability in water. Changes in the atom composition and structure properties of MWCNTs were analyzed using x-ray photoelectron spectroscopy and Raman spectroscopy, and the surface morphology of MWCNTs was observed by field emission scanning electron microscopy and scanning transmission electron microscopy. The results indicated that Ar/H 2 O plasma treatment greatly enhanced the content of oxygen, and modified surface microstructure properties. The integrity of nanotube patterns, however, was not damaged.

  19. Calculation of opacities and emissivities for carbon plasmas under NLTE and LTE conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gil, J.M.; Rodriguez, R.; Florido, R.; Rubiano, J.G.; Martel, P. [Las Palmas de Gran Canaria Univ., Dept. de Fisica (Spain); Sauvan, P. [Universidad Nacional de Educacion a Distancia, Dept. de Ingenieria Energetica, Madrid (Spain); Minguez, E. [Madrid Univ. Politecnica, Instituto de Fusion Nuclear-DENIM (Spain)

    2006-06-15

    We calculate different optical properties for carbon plasma in a wide range of temperatures and densities by using ATOM3R-OP code which has been recently developed. In this code we have implemented the rate equations, the Saha equation (for local thermodynamic equilibrium) and the coronal equilibrium model. We have calculated average ionizations, level populations, opacities and emissivities and we focus our study on the identification with our code of coronal equilibrium, non-local thermodynamic equilibrium and local thermodynamic equilibrium regions for this kind of plasma. Moreover, we analyse the differences in the optical properties when they are calculated in non-local thermodynamic equilibrium and local thermodynamic equilibrium. (authors)

  20. Reverse Ballistic Air Gun Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This custom-designed facility houses a suite of three air guns capable of generating accelerations up to 100,000 Gs and velocities up to 2,000 ft/s. In addition to a...

  1. Temporal association between federal gun laws and the diversion of guns to criminals in Milwaukee.

    Science.gov (United States)

    Webster, Daniel W; Vernick, Jon S; Bulzacchelli, Maria T; Vittes, Katherine A

    2012-02-01

    The practices of licensed gun dealers can threaten the safety of urban residents by facilitating the diversion of guns to criminals. In 2003, changes to federal law shielded gun dealers from the release of gun trace data and provided other protections to gun dealers. The 14-month period during which the dealer did not sell junk guns was associated with a 68% reduction in the diversion of guns to criminals within a year of sale by the dealer and a 43% increase in guns diverted to criminals following sales by other dealers. The laws were associated with a 203% increase in the number of guns diverted to criminals within a year of sale by the gun store, which was the focus of this study. Policies which affect gun dealer accountability appeared to influence the diversion of guns to criminals.

  2. Rf Gun with High-Current Density Field Emission Cathode

    International Nuclear Information System (INIS)

    Jay L. Hirshfield

    2005-01-01

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  3. NASA-Ames vertical gun

    Science.gov (United States)

    Schultz, P. H.

    1984-01-01

    A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

  4. Plasma radiation in tokamak disruption simulation experiments

    International Nuclear Information System (INIS)

    Arkhipov, N.; Bakhtin, V.; Safronov, V.; Toporkov, D.; Vasenin, S.; Zhitlukhin, A.; Wuerz, H.

    1995-01-01

    Plasma impact results in sudden evaporation of divertor plate material and produces a plasma cloud which acts as a protective shield. The incoming energy flux is absorbed in the plasma shield and is converted mainly into radiation. Thus the radiative characteristics of the target plasma determine the dissipation of the incoming energy and the heat load at the target. Radiation of target plasma is studied at the two plasma gun facility 2MK-200 at Troitsk. Space- and time-resolved spectroscopy and time-integrated space-resolved calorimetry are employed as diagnostics. Graphite and tungsten samples are exposed to deuterium plasma streams. It is found that the radiative characteristics depend strongly on the target material. Tungsten plasma arises within 1 micros close to the surface and shows continuum radiation only. Expansion of tungsten plasma is restricted. For a graphite target the plasma shield is a mixture of carbon and deuterium. It expands along the magnetic field lines with a velocity of v = (3--4) 10 6 cm/s. The plasma shield is a two zone plasma with a hot low dense corona and a cold dense layer close to the target. The plasma corona emits intense soft x-ray (SXR) line radiation in the frequency range from 300--380 eV mainly from CV ions. It acts as effective dissipation system and converts volumetrically the incoming energy flux into SXR radiation

  5. Modeling of Plasma-Induced Ignition and Combustion

    National Research Council Canada - National Science Library

    Boyd, Iain D; Keidar, Michael

    2008-01-01

    .... Phenomena that must be considered in an electrothermal chemical gun model include the initial capillary plasma properties, the plasma-air interaction, plasma sheath effects, and the plasma-propellant interaction itself...

  6. Observations of non-collective x-ray scattering in warm dense carbon plasma

    International Nuclear Information System (INIS)

    Bao Lihua; Zhang Jiyan; Zhao Yang; Ding Yongkun; Zhang Xiaoding

    2012-01-01

    An experiment for observing the spectrally resolved non-collective x-ray scattering in warm dense carbon plasma is presented in this paper. The experiment used Ta M-band x-rays to heat a foamed carbon cylinder sample isochorically and measured the scattering spectrum with a HOPG crystal spectrometer. The spectrum was compared with the calculation results using a Born-Mermin-approximation model. The best fitting was found at an electron temperature of T e =34 eV and an electron density of n e =1.6×10 23 cm −3 .

  7. Carbon nanosheets by microwave plasma enhanced chemical vapor deposition in CH4-Ar system

    International Nuclear Information System (INIS)

    Wang Zhipeng; Shoji, Mao; Ogata, Hironori

    2011-01-01

    We employ a new gas mixture of CH 4 -Ar to fabricate carbon nanosheets by microwave plasma enhanced chemical vapor deposition at the growth temperature of less than 500 deg. C. The catalyst-free nanosheets possess flower-like structures with a large amount of sharp edges, which consist of a few layers of graphene sheets according to the observation by transmission electron microscopy. These high-quality carbon nanosheets demonstrated a faster electron transfer between the electrolyte and the nanosheet surface, due to their edge defects and graphene structures.

  8. State Gun Law Environment and Youth Gun Carrying in the United States.

    Science.gov (United States)

    Xuan, Ziming; Hemenway, David

    2015-11-01

    Gun violence and injuries pose a substantial threat to children and youth in the United States. Existing evidence points to the need for interventions and policies for keeping guns out of the hands of children and youth. (1) To examine the association between state gun law environment and youth gun carrying in the United States, and (2) to determine whether adult gun ownership mediates this association. This was a repeated cross-sectional observational study design with 3 years of data on youth gun carrying from US states. The Youth Risk Behavior Survey comprises data of representative samples of students in grades 9 to 12 from biennial years of 2007, 2009, and 2011. We hypothesized that states with more restrictive gun laws have lower rates of youth gun carrying, and this association is mediated by adult gun ownership. State gun law environment as measured by state gun law score. Youth gun carrying was defined as having carried a gun on at least 1 day during the 30 days before the survey. In the fully adjusted model, a 10-point increase in the state gun law score, which represented a more restrictive gun law environment, was associated with a 9% decrease in the odds of youth gun carrying (adjusted odds ratio [AOR], 0.91 [95% CI, 0.86-0.96]). Adult gun ownership mediated the association between state gun law score and youth gun carrying (AOR, 0.94 [ 95% CI, 0.86-1.01], with 29% attenuation of the regression coefficient from -0.09 to -0.07 based on bootstrap resampling). More restrictive overall gun control policies are associated with a reduced likelihood of youth gun carrying. These findings are relevant to gun policy debates about the critical importance of strengthening overall gun law environment to prevent youth gun carrying.

  9. State Gun Policy and Cross-State Externalities: Evidence from Crime Gun Tracing

    OpenAIRE

    Brian Knight

    2013-01-01

    This paper provides a theoretical and empirical analysis of cross-state externalities associated with gun regulations in the context of the gun trafficking market. Using gun tracing data, which identify the source state for crime guns recovered in destination states, we find that firearms in this market tend to flow from states with weak gun laws to states with strict gun laws, satisfying a necessary condition for the existence of cross-state externalities in the theoretical model. We also fi...

  10. Negative-ion production on carbon materials in hydrogen plasma : influence of the carbon hybridization state and the hydrogen content on H- yield

    NARCIS (Netherlands)

    Ahmad, A.; Pardanaud, C.; Carrère, M.; Layet, J.M.; Gicquel, A.; Kumar, P.; Eon, D.; Jaoul, C.; Engeln, R.A.H.; Cartry, G.

    2014-01-01

    Highly oriented polycrystalline graphite (HOPG), boron-doped diamond (BDD), nanocrystalline diamond, ultra-nanocrystalline diamond and diamond-like carbon surfaces are exposed to low-pressure hydrogen plasma in a 13.56 MHz plasma reactor. Relative yields of surface-produced H- ions due to

  11. Catalytic Effect of Activated Carbon and Activated Carbon Fiber in Non-Equilibrium Plasma-Based Water Treatment

    Science.gov (United States)

    Zhang, Yanzong; Zheng, Jingtang; Qu, Xianfeng; Yu, Weizhao; Chen, Honggang

    2008-06-01

    Catalysis and regeneration efficiency of granular activated carbon (GAC) and activated carbon fiber (ACF) were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange (MO) by the combined treatment can increase 22% (for GAC) and 24% (for ACF) respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H2O2 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.

  12. Catalytic Effect of Activated Carbon and Activated Carbon Fiber in Non-Equilibrium Plasma-Based Water Treatment

    International Nuclear Information System (INIS)

    Zhang Yanzong; Zheng Jingtang; Qu Xianfeng; Yu Weizhao; Chen Honggang

    2008-01-01

    Catalysis and regeneration efficiency of granular activated carbon (GAC) and activated carbon fiber (ACF) were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange (MO) by the combined treatment can increase 22% (for GAC) and 24% (for ACF) respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H 2 O 2 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.

  13. Application of laser-produced-plasmas to determination of carbon content in steel

    International Nuclear Information System (INIS)

    Ortiz, M.; Aragon, C.; Aguilera, J.A.; Campos, J.

    1994-01-01

    This paper describes an analytical method to determine carbon content in solid and molten steel. It is based on the study of the emission spectrum from a Nd-YAG laser produced plasma. The light emitted from the plasma is focused to the entrance slit of a spectrometer and detected by an OMA III system. For every laser pulse an spectral range of 100 A are recorded. With the use of time-resolved spectroscopy a precision of 1.6% and a detection limit of 65 ppm of carbon content in steel have been obtained. These values are similar to those of other accurate conventional techniques but using optics fiber and laser excitation it is possible to made sample calibrations in hostile environments. Also, as the analysis are made in real time changes in sample composition can be measured without stopping production processes. (Author) 26 refs

  14. Application of laser-produced-plasmas to determination of carbon content in steel

    International Nuclear Information System (INIS)

    Ortiz, M.; Aragon, C.; Aguilera, J. A.; Campos, J.

    1994-01-01

    This paper describes an analytical method to determine carbon content in solid and molten steel. It is based on the study of the emission spectrum from a Nd-YAG laser produced plasma. The light emitted from the plasma is focused to the entrance slit of a spectrometer and detected by an OMA III system. For every laser pulse an spectral range of 100 A are recorded. With the use of time-resolved spectroscopy a precision of 1.6 % and a detection limit of 65 ppm of carbon content in steel have been obtained. These values are similar to those of other accurate conventional techniques but using optics fiber and laser excitation it is possible to made sample calibrations in hostile environments. Also, as the analysis are made in real time changes in sample composition can be measured without stopping production processes. (Author) 26 refs

  15. Plasma Treated Multi-Walled Carbon Nanotubes (MWCNTs for Epoxy Nanocomposites

    Directory of Open Access Journals (Sweden)

    Jie Lian

    2011-12-01

    Full Text Available Plasma nanocoating of allylamine were deposited on the surfaces of multi-walled carbon nanotubes (MWCNTs to provide desirable functionalities and thus to tailor the surface characteristics of MWCNTs for improved dispersion and interfacial adhesion in epoxy matrices. Plasma nanocoated MWCNTs were characterized using scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HR-TEM, surface contact angle, and pH change measurements. Mechanical testing results showed that epoxy reinforced with 1.0 wt % plasma coated MWCNTs increased the tensile strength by 54% as compared with the pure epoxy control, while epoxy reinforced with untreated MWCNTs have lower tensile strength than the pure epoxy control. Optical and electron microscopic images show enhanced dispersion of plasma coated MWCNTs in epoxy compared to untreated MWCNTs. Plasma nanocoatings from allylamine on MWCNTs could significantly enhance their dispersion and interfacial adhesion in epoxy matrices. Simulation results based on the shear-lag model derived from micromechanics also confirmed that plasma nanocoating on MWCNTs significantly improved the epoxy/fillers interface bonding and as a result the increased composite strength.

  16. Adhesion enhancement of Al coatings on carbon/epoxy composite surfaces by atmospheric plasma

    International Nuclear Information System (INIS)

    Coulon, J.F.; Tournerie, N.; Maillard, H.

    2013-01-01

    Adhesion strengths between aluminium thin film coatings and manufactured carbon/epoxy composite surfaces were measured by assessing fracture tensile strengths using pull-off tests. The effect of the substrate roughness (nm to μm) of these composite surfaces on adhesion was studied by examining the surface free energies and adhesion strengths. The adhesion strengths of the coatings varied significantly. To improve the coating adhesion, each composite surface was treated with atmospheric plasma prior to deposition, which resulted in an increase in the surface free energy from approximately 40 mJ/m 2 to 70 mJ/m 2 because the plasma pretreatment led to the formation of hydrophilic C-O and C=O bonds on the composite surfaces, as demonstrated by X-ray photoelectron spectroscopy analyses. The adhesion strengths of the coatings were enhanced for all surface roughnesses studied. In our study, the effect of mechanical adhesion due to roughness was separated from the effect of modifying the chemical bonds with plasma activation. The adhesion ability of the pure resin was relatively weak. Increasing the surface roughness largely improved the adhesion of the resin surface. Plasma treatment of the pure resin also increased the surface adhesion. Our study shows that plasma activation effectively enhances the adhesion of manufactured composites, even when the surface roughness is on the order of microns. The ageing of the surface activation was also investigated, and the results demonstrate that atmospheric plasma has potential for use in the pretreatment of composite materials.

  17. Interactions between plasma-treated carbon nanotubes and electrically neutral materials

    Science.gov (United States)

    Ogawa, Daisuke; Nakamura, Keiji

    2014-10-01

    A plasma treatment can create dangling bonds on the surface of carbon nanotubes (CNTs). The dangling bonds are so reactive that the bonds possibly interact with other neutral species even out of the plasma if the lifetime of the bonds is effectively long. In order to have good understandings with the interactions, we placed multi-wall CNTs (MWCNTs) in atmospheric dielectric barrier discharge that was created in a closed environment with the voltage at 5 kV. We set 50 W for the operating power and 15 minutes for the process time for this plasma treatment. Our preliminary results showed that the reaction between dangling bonds and neutrals likely occurred in the situation when CNTs were treated with argon plasma, and then exposed in a nitrogen-rich dry box. We did Fourier transform infrared (FTIR) spectroscopy after the treatments. The measurement showed that the spectrum with plasma-treated CNTs was different from pristine CNTs. This is an indication that the plasma-treated CNTs have reactive cites on the surface even after the discharge (~ minutes), and then the CNTs likely reacted with the neutral species that causes the different spectrum. In this poster, we will show more details from our results and further progresses from this research.

  18. Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

    Science.gov (United States)

    Qu, Guangzhou; Liang, Dongli; Qu, Dong; Huang, Yimei; Li, Jie

    2014-06-01

    In this study, two regeneration methods (dielectric barrier discharge (DBD) plasma and ozone (O3) regeneration) of saturated granular activated carbon (GAC) with pentachlorophenol (PCP) were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with O3 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after O3 regeneration. O3 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cycles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after O3 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that O3 regeneration has a lower weight loss than DBD plasma regeneration.

  19. Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

    International Nuclear Information System (INIS)

    Qu Guangzhou; Liang Dongli; Qu Dong; Huang Yimei; Li Jie

    2014-01-01

    In this study, two regeneration methods (dielectric barrier discharge (DBD) plasma and ozone (O 3 ) regeneration) of saturated granular activated carbon (GAC) with pentachlorophenol (PCP) were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with O 3 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after O 3 regeneration. O 3 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cycles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after O 3 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that O 3 regeneration has a lower weight loss than DBD plasma regeneration

  20. Study of hard diamond-like carbon films deposited in an inductively coupled plasma source

    International Nuclear Information System (INIS)

    Yu Shiji; Ma Tengcai

    2003-01-01

    Chemical vapor deposition of the hard diamond-like carbon (DLC) films was achieved using an inductively coupled plasma source (ICPS). The microscopy, microhardness, deposition rate and structure characteristic of the DLC films were analyzed. It is shown that the ICPS is suitable for the hard DLC film deposition at relatively low substrate negative bias voltage, and the substrate negative bias voltage greatly affects chemical vapor deposition of the DLC film and its quality