WorldWideScience

Sample records for streamer tube wires

  1. Some properties of the streamer tube system of the charm neutrino detector

    International Nuclear Information System (INIS)

    Bergsma, F.; Dorenbosch, J.; Jonker, M.

    1982-01-01

    The fine-grain and low-density neutrino calorimeter of the CHARM Collaboration has been designed to measure the energy and the direction of particle showers. To further improve the spatial resolution the calorimeter has been upgraded by adding 20,000 aluminium tubes, working in the limited streamer mode. Each subunit is now equipped with crossed wire planes. Results of a new energy calibration of the upgraded detector using electron and pion beams from 5 to 140 GeV/c, and on the angular and spatial resolution are presented. The use of the streamer tube system to discriminate between electromagnetic and hadronic showers is discussed

  2. Self-quenching streamer discharge in a wire chamber

    International Nuclear Information System (INIS)

    Alekseev, G.D.; Kruglov, V.V.; Khazins, D.M.

    1982-01-01

    A summary is given of the investigation of a new mode of operation of a wire chamber involving a self-quenching streamer discharge. The history of the question is briefly discussed. The main characteristics of the self-quenching mode and the influence of the composition and pressure of the gas mixture and the geometrical parameters of the chamber on the characteristics are described. The mechanism of a self-quenching streamer discharge is analyzed. Detectors working in this mode are described, and the prospects for its future use are discussed

  3. Self-quenching streamers

    International Nuclear Information System (INIS)

    Atac, M.; Tollestrup, A.V.; Potter, D.

    1982-01-01

    Self quenching streamers in drift tubes have been observed both optically and electronically. The streamers of 150-200 μm width extend out from the anode wire to 1.5 to 3 mm at atmospheric pressures. Electronic measurements at a two atomsphere pressure show pulses into a 50 Ω load with a rise time of 5 ns, a decay time of 40 ns, and an amplitude of 30 mV. Details of the experiments are discussed. There was no detectable residue on an anode wire after exposing it to 2x10 9 streamers for a 1 mm section. (orig.)

  4. Wire- and cathode pulses in a counter of square cross section with a thin wire as central conductor operating in limited streamer mode

    Science.gov (United States)

    Carli, Ch.; Erd, Ch.; Leder, G.; Pernicka, M.; Regler, M.; Schnizer, B.

    1989-11-01

    Streamer tubes are becoming increasingly important in high-energy physics experiments. They are used as drift tubes for the localisation of charged-particle tracks, and also as sampling devices in sandwich calorimeters with cathode readout only. The streamer pulses carry charges which are several orders of magnitude larger than pulses from proportional chambers; this provides a good signal-to-noise ratio and makes them appropriate for a wide field of applications in highly compact detectors. The signals induced on the cathodes are also important for measuring — in addition to the anode wire - a second coordinate, and for resolving ambiguities in track recognition. When connecting the signals from two opposite cathodes to the two inputs of a differential amplifier, a left/right bit could be added after suitable buffering via the same signal line as used for time digitalisation. Another essential feature is the association of time information from the anode wire and the cathode. For the streamer tube used in this experiment the pulses induced on the cathode on either side of the particle, and on the anode, are measured by a fast analog-to-digital converter. A simple two-dimensional model ρ( r, θ) at t = 0, without any time-dependent effects other than a constant electron drift velocity of 50 μm/ns, is used to compare the charge distribution in a streamer with the measurements of the pulse lengths at the two opposite cathode strips. First the field generated by a static voltage is calculated. Then the effect of a "space charge" is evaluated. The Green's function of the square domain is a prerequisite for determining the field and the surface charge distribution on the electrodes. It is obtained from that of a concentric circular counter by a conformal mapping. Representations of Green's functions are calculated by series expansions.

  5. Properties of self-quenching streamer (SQS) tubes

    International Nuclear Information System (INIS)

    Koori, N.; Nohtomi, A.; Hashimoto, M.; Yoshioka, K.; Kumabe, I.

    1989-01-01

    The self-quenching streamer (SQS) mode of gas counters have been widely used for measuring high energy particles. The authors have very recently found that all the rare gas (He, Ne, Ar and Xe) mixtures with quenching gas of CH 4 , C 2 H 6 , C 3 H 8 , iso-C 4 H 10 or CO 2 can be used as gas mixtures for the SQS mode except Ne- and He-mixtures with CH 4 or CO 2 . Further studies on the properties of this mode are needed for its application to monitoring devices. Properties of a self-quenching tube are discussed here from this point of view. Gas multiplication properties, pulse shape of current signals, and dead zone are measured under several gas pressures equal to or less than one atomospheric pressure. Either the SQS or GM mode can be obtained by changing the gas pressure with a cylindrical gas counter. The operation mode of the counter may be correctly determined from the dead zone measurement. The measurements show that the SQS and GM modes are exclusive, even though SQS's can be simultaneously formed with a GM discharge. The counting rate capability of the SQS mode is higher than that of the GM mode by about one order of magnitude. Thus, SQS tubes are suitable for use in high flux radiation fields. (N.K.)

  6. A streamer tube detector for operation at high rates in the CPLEAR experiment at CERN

    International Nuclear Information System (INIS)

    Bennet, J.M.; Carroll, M.; Cawley, E.L.; Dodgson, M.; Fry, J.R.; Gabathuler, E.; Gamet, R.; Harrison, P.; Harrison, P.F.; Haselden, A.R.; Hayman, P.J.; King, D.; Maley, P.D.; Sacks, L.E.; Sanders, P.M.

    1996-01-01

    The design and instrumentation of a streamer tube detector for operation in the high rate environment of the CPLEAR experiment at CERN is described. A study of gas mixtures for use in the streamer tube is discussed. The final mixture of 46% argon, 50% isobutane, 4% methylal and 0.01% freon produces an axial resolution of 1.5 cm with an efficiency of 98% per layer. (orig.)

  7. High-voltage test and training of plastic streamer tubes for the DELPHI hadron calorimeter

    International Nuclear Information System (INIS)

    Alekseev, G.D.; Cellar, S.; Khomenko, B.A.; Korytov, A.V.; Kulinich, P.A.; Micelmacher, G.V.; Sedykh, Yu.V.; Toledo, R.

    1987-01-01

    The results of high-voltage test and training of plastic streamer tubes of the DELPHI hadron calorimeter are presented. The testing technique is considered in detail. The equipment for high-voltage training consists of a mini-computer, CAMAC-electronics, a controllable high-voltage supply and a digital ampermeter. The experimental results shows that high-voltage training of streamer tubes improves their characteristics. The value of dark current decreased up to 1 μA. The operational voltage range increased by a value more than 300 V

  8. Studies of the stability and sistematics of operation of the DELPHI plastic streamer tubes

    International Nuclear Information System (INIS)

    Alekseev, G.D.; Bilenky, M.S.; Bonyushkin, Yu.Ye.; Korrytov, A.V.

    1989-01-01

    The influeNce of gas pressure and temperature, slight changes in a gas mixture, self-sustaining discharge, aging, different deviations in the detector geometry on the operation of the DELPHI plastic streamer tubes is studied. The contribution of these factors to the DELPHI hadron calorimeter energy resolution is estimated. The major influence is found to be due to atmospheric pressure fluctuations (∼ ±1% streamer charge change per ±1 Torr). The question of the choice of a gas mixture is studied as well. Maximal streamer charge is shown to be independent of component concentrations in the Ar:CO 2 :i-C 4 H 10 ) or C 5 H 12 ) gas mixtures. 23 refs.; 21 figs.; 1 tab

  9. Electro-mechanics of drift tube wires

    International Nuclear Information System (INIS)

    Milburn, R.H.

    1997-01-01

    The position and stability of the sense wires in very long drift tubes are affected by both gravitational and electrostatic forces, as well as by the wire tension. For a tube to be used as an element of a high-resolution detector all these forces and their effects must be understood in appropriately precise detail. In addition, the quality control procedures applied during manufacture and detector installation must be adequate to ensure that the internal wire positions remain within tolerances. It may be instructive to practitioners to review the simple theory of a taut wire in the presence of anisotropic gravitational and electrostatic fields to illustrate the conditions for stability, the equilibrium wire displacement from straightness, and the effect of the fields on the mechanical vibration frequencies. These last may be used to monitor the wire configuration externally. A number of practical formulae result and these are applied to illustrative examples. (orig.)

  10. Streamer Evaporation

    Science.gov (United States)

    Suess, Steven T.; Wang, A. H.; Wu, Shi T.; Nerney, S.

    1998-01-01

    Evaporation is the consequence of slow plasma heating near the tops of streamers where the plasma is only weakly contained by the magnetic field. The form it takes is the slow opening of field lines at the top of the streamer and transient formation of new solar wind. It was discovered in polytropic model calculations, where due to the absence of other energy loss mechanisms in magnetostatic streamers, its ultimate endpoint is the complete evaporation of the streamer. This takes, for plausible heating rates, weeks to months in these models. Of course streamers do not behave this way, for more than one reason. One is that there are losses due to thermal conduction to the base of the streamer and radiation from the transition region. Another is that streamer heating must have a characteristic time constant and depend on the ambient physical conditions. We use our global Magnetohydrodynamics (MHD) model with thermal conduction to examine a few examples of the effect of changing the heating scale height and of making ad hoc choices for how the heating depends on ambient conditions. At the same time, we apply and extend the analytic model of streamers, which showed that streamers will be unable to contain plasma for temperatures near the cusp greater than about 2xl0(exp 6) K. Slow solar wind is observed to come from streamers through transient releases. A scenario for this that is consistent with the above physical process is that heating increases the near-cusp temperature until field lines there are forced open. The subsequent evacuation of the flux tubes by the newly forming slow wind decreases the temperature and heating until the flux tubes are able to reclose. Then, over a longer time scale, heating begins to again refill the flux tubes with plasma and increase the temperature until the cycle repeats itself. The calculations we report here are first steps towards quantitative evaluation of this scenario.

  11. A Barrel IFR Instrumented With Limited Streamer Tubes for BABAR Experiment

    International Nuclear Information System (INIS)

    Andreotti, M.; Ferrara U.; INFN, Ferrara

    2006-01-01

    The new barrel Instrumented Flux Return (IFR) of BABAR detector will be reported here. Limited Streamer Tubes (LSTs) have been chosen to replace the existing RPCs as active elements of the barrel IFR. The layout of the new detector will be discussed: in particular, a cell bigger than the standard one has been used to improve efficiency and reliability. The extruded profile is coated with a resistive layer of graphite having a typical surface resistivity between 0.2 and 0.4 MOhm/square. The tubes are assembled in modules and installed in 12 active layers of each sextant of the IFR detector. R and D studies to choose the final design and Quality Control procedure adopted during the tube production will be briefly discussed. Finally the performances of installed LSTs into 2/3 of IFR after 8 months of operations will be reported

  12. Method of detection of transition radiation by wire chambers operating in self-quenching streamer mode

    International Nuclear Information System (INIS)

    Akopdzhanov, G.A.; Bityukov, S.I.; Dzhelyadin, R.I.; Zaitsev, A.M.; Lapin, V.V.; Saraikin, A.I.

    1984-01-01

    A method for detecting X-ray transition radiation against the background of the signal from relativistic charged particles is suggested that is based on the use of peculiarities of the development of self-queenching streamer mode. The self-qunching streamer discharge in the Xe + isobutane mixture is experimentally registered. The effect of separation of signals from the relativistic particle and from soft X-ray, is obtained

  13. Tungsten wire and tubing joined by nickel brazing

    Science.gov (United States)

    1965-01-01

    Thin tungsten wire and tungsten tubing are brazed together using a contacting coil of nickel wire heated to its melting point in an inert-gas atmosphere. This method is also effective for brazing tungsten to tungsten-rhenium parts.

  14. Performance of the MACRO limited streamer tubes for estimates of muon energy

    CERN Document Server

    Giorgini, M

    2002-01-01

    The MACRO limited streamer tubes can be operated in drift mode by using the TDCs included in the QTP system. In this way a considerable improvement in the space resolution is obtained, allowing the analysis of muon tracks in terms of multiple scattering effects and the energy estimates of muons crossing the detector. We present the results of two dedicated tests, performed with the CERN PS-T9 and SPS-X7 beams, to provide a full check of the electronics and to exploit the feasibility of the analysis. Using a neural network, we are able to estimate the muon energies up to E/sub mu / approximately = 40 GeV. The test beam data provide then an absolute energy calibration, which allows to apply the method to the MACRO data. (5 refs).

  15. The limited streamer tubes system for the SLD warm iron calorimeter

    International Nuclear Information System (INIS)

    Benvenuti, A.C.; Camanzi, B.; Piemontese, L.; Zucchelli, P.; Calcaterra, A.; De Sangro, R.; De Simone, P.; De Simone, S.; Gallinaro, M.; Peruzzi, I.; Piccolo, M.; Bacchetta, N.; Bisello, D.; Castro, A.; Galvagni, S.; Loreti, M.; Pescara, L.; Wyss, J.; Battiston, R.; Biasini, M.; Bilei, G.M.; Checcucci, B; Mancinelli, G.; Mantovani, G.; Pauluzzi, M.; Santocchia, A.; Servoli, L.; Carpinelli, M.; Castaldi, R.; Cazzola, U.; Dell'Orso, R.; Pieroni, E.; Vannini, C.; Verdini, P.G.; Byers, B.L.; Escalera, J.; Kharakh, D.; Messner, R.L.; Zdarko, R.W.; Johnson, J.R.

    1992-01-01

    The SLD detector at the Stanford Linear Accelerator Center is a general purpose device for studying e + ε - interaction at the Z 0 . The SLD calorimeter system consists of two parts: a lead Liquid Argon Calorimeter (LAC) with both electromagnetic (22 radiation lengths) and hadronic sections (2.8 absorption lengths) housed inside the coil, and the Warm Ion limited streamer tubes Calorimeter (WIC) outside the coil which uses as radiator the iron of the flux return for the magnetic field. The WIC completes the measurement of the hadronic shower energy (∼85% on average is contained in the LAC) and it provides identification and tracking for muons over 99% of the solid angle. In this note we report on the construction, test and commissioning of such a large system

  16. Limited Streamer Tubes for the BaBar Instrumented Flux Return Upgrade

    International Nuclear Information System (INIS)

    Lu, C.

    2005-01-01

    Starting from the very beginning of their operation the efficiency of the RPC chambers in the BaBar Instrumented Flux Return (IFR) has suffered serious degradation. After intensive investigation, various remediation efforts had been carried out, but without success. As a result the BaBar collaboration decided to replace the dying barrel RPC chambers about two years ago. To study the feasibility of using the Limited Streamer Tube (LST) as the replacement of RPC we carried out an R and D program that has resulted in BaBar's deciding to replace the barrel RPC's with LST's. In this report we summarize the major detector R and D results, and leave other issues of the IFR system upgrade to the future publications

  17. Optimization of the Single Staggered Wire and Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Arsana I Made

    2016-01-01

    Full Text Available Wire and tube heat exchanger consists of a coiled tube, and wire is welded on the two sides of it in normal direction of the tube. Generally,wire and tube heat exchanger uses inline wire arrangement between the two sides, whereas in this study, it used staggered wire arrangement that reduces the restriction of convection heat transfer. This study performed the optimization of single staggered wire and tube heat exchanger to increase the capacity and reduce the mass of the heat exchanger. Optimization was conducted with the Hooke-Jeeves method, which aims to optimize the geometry of the heat exchanger, especially on the diameter (dw and the distance between wires (pw. The model developed to present heat transfer correlations on single staggered wire and tube heat exchanger was valid. The maximum optimization factor obtained when the diameter wire was 0.9 mm and the distance between wires (pw was 11 mm with the fref value = 1.5837. It means that the optimized design only using mass of 59,10 % and could transfer heat about 98,5 % from the basis design.

  18. Pressure Drop Versus Flow Rate Analysis of the Limited Streamer Tube Gas System of the BaBar Muon Detector Upgrade

    International Nuclear Information System (INIS)

    Yi, M.

    2004-01-01

    It has been proposed that Limited Streamer Tubes (LST) be used in the current upgrade of the muon detector in the BaBar detector. An LST consists of a thin silver plated wire centered in a graphite-coated cell. One standard LST tube consists of eight such cells, and two or three such tubes form an LST module. Under operation, the cells are filled with a gas mixture of CO 2 , argon and isobutane. During normal operation of the detector, the gas will be flushed out of the system at a constant low rate of one volume change per day. During times such as installation, however, it is often desired to flush and change the LST gas volumes very rapidly, leading to higher than normal pressure which may damage the modules. This project studied this pressure as a function of flow rate and the number of modules that are put in series in search of the maximal safe flow rate at which to flush the modules. Measurements of pressure drop versus flow rate were taken using a flow meter and a pressure transducer on configurations of one to five modules put in series. Minimal Poly-Flo tubing was used for all connections between test equipment and modules. They contributed less than 25% to all measurements. A ratio of 0.00022 ± 0.00001 mmHg per Standard Cubic Centimeter per Minute (SCCM) per module was found, which was a slight overestimate since it included the contributions from the tubing connections. However, for the purpose of finding a flow rate at which the modules can be safely flushed, this overestimate acts as a safety cushion. For a standard module with a volume of 16 liters and a known safe overpressure of 2 inches of water, the ratio translates into a flow rate of 17000 ± 1000SCCM and a time requirement of 56 ± 5 seconds to flush an entire module

  19. Thermal performance in circular tube fitted with coiled square wires

    International Nuclear Information System (INIS)

    Promvonge, Pongjet

    2008-01-01

    The effects of wires with square cross section forming a coil used as a turbulator on the heat transfer and turbulent flow friction characteristics in a uniform heat flux, circular tube are experimentally investigated in the present work. The experiments are performed for flows with Reynolds numbers ranging from 5000 to 25,000. Two different spring coiled wire pitches are introduced. The results are also compared with those obtained from using a typical coiled circular wire, apart from the smooth tube. The experimental results reveal that the use of coiled square wire turbulators leads to a considerable increase in heat transfer and friction loss over those of a smooth wall tube. The Nusselt number increases with the rise of Reynolds number and the reduction of pitch for both circular and square wire coils. The coiled square wire provides higher heat transfer than the circular one under the same conditions. Also, performance evaluation criteria to assess the real benefits in using both coil wires of the enhanced tube are determined

  20. Heat resistant wire and cable and heat shrinkable tubes

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Keiji [Sumitomo Electric Industries Ltd. (Japan)

    1994-12-31

    Radiation processes have been used in industrial fields (e.g. wire and cable, heat shrinkable tubes) for about 30 years. In Japan, 60 electron beam accelerators were used in R and D, 54 in wire and cable, 24 in tire rubber, 16 in paint curing, 14 in PE foam and 9 accelerators were used in heat shrinkable tubes in 1993. Many properties (e.g. solder resistance, thermal deformation, and solven resistance) of wire and cable are improved by using radiation processes, and many kinds of radiation crosslinked wire and cable are used in the consumer market (TV sets, VTR`s, audio disc players, etc.), automobiles (automobile wire harnesses, fusible link wires, sensor cables etc.), and the industrial market (computer cables, cables for keyboards, coaxial cables, etc.). Another important industrial application of E{beta} radiation process is heat shrinkable tubes. Heat shinkable tubes, heated by a hot gun, shrink 1/2 {approx} 1/3 of their inner diameters. Heat shrinkable tubes are used for covers of distributing line terminals, joint covers of telecommunication lines, protection of fuel pipe lines and so on. In this seminar, actual applications and characteristic properties of radiation crosslinked materials are presented.

  1. Heat resistant wire and cable and heat shrinkable tubes

    International Nuclear Information System (INIS)

    Keiji Ueno

    1994-01-01

    Radiation processes have been used in industrial fields (e.g. wire and cable, heat shrinkable tubes) for about 30 years. In Japan, 60 electron beam accelerators were used in R and D, 54 in wire and cable, 24 in tire rubber, 16 in paint curing, 14 in PE foam and 9 accelerators were used in heat shrinkable tubes in 1993. Many properties (e.g. solder resistance, thermal deformation, and solven resistance) of wire and cable are improved by using radiation processes, and many kinds of radiation crosslinked wire and cable are used in the consumer market (TV sets, VTR's, audio disc players, etc.), automobiles (automobile wire harnesses, fusible link wires, sensor cables etc.), and the industrial market (computer cables, cables for keyboards, coaxial cables, etc.). Another important industrial application of Eβ radiation process is heat shrinkable tubes. Heat shinkable tubes, heated by a hot gun, shrink 1/2 ∼ 1/3 of their inner diameters. Heat shrinkable tubes are used for covers of distributing line terminals, joint covers of telecommunication lines, protection of fuel pipe lines and so on. In this seminar, actual applications and characteristic properties of radiation crosslinked materials are presented

  2. Influence of gas mixture and primary ionization on the performance of limit streamer mode tubes

    International Nuclear Information System (INIS)

    An Jigang; Anderson, K.J.; Merritt, F.S.; Oreglia, M.; Pilcher, J.E.; Possoz, A.; Schappert, W.; Chicago Univ., IL

    1988-01-01

    We report a study of the dependence of limited streamer mode operation on gas composition. Results are given for the plateau onset voltage, plateau length, charge versus voltage, charge spectra and pulse width for various fractions of (Ar, CO 2 , pentane) and (Ar, isobutane). In addition, a series of argon-free strong quenching gas mixtures has been studied which have very attractive characteristics. Chamber lifetime tests for these are also reported. As part of a study of the nature of the limited streamer mode mechanism, the response to X-rays and minimum ionizing particles are compared and differences noted. The character of the primary ionization is found to have a clear effect on the chamber response even in the streamer region. (orig.)

  3. Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

    Science.gov (United States)

    Winands, G. J. J.; Liu, Z.; Pemen, A. J. M.; van Heesch, E. J. M.; Yan, K.; van Veldhuizen, E. M.

    2006-07-01

    In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh)-1. For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh)-1, still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second.

  4. Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

    Energy Technology Data Exchange (ETDEWEB)

    Winands, G J J [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Liu, Z [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Pemen, A J M [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Heesch, E J M van [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Yan, K [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Veldhuizen, E M van [EPG Group, Department of Applied Physics, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands)

    2006-07-21

    In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh){sup -1}. For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh){sup -1}, still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second.

  5. Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

    International Nuclear Information System (INIS)

    Winands, G J J; Liu, Z; Pemen, A J M; Heesch, E J M van; Yan, K; Veldhuizen, E M van

    2006-01-01

    In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh) -1 . For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh) -1 , still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second

  6. Triangular tube proportional wire chamber system

    Energy Technology Data Exchange (ETDEWEB)

    Badtke, D H; Bakken, J A; Barnett, B A; Blumenfeld, B J; Chien, C Y; Madansky, L; Matthews, J A.J.; Pevsner, A; Spangler, W J [Johns Hopkins Univ., Baltimore, MD (USA); Lee, K L [California Univ., Berkeley (USA). Lawrence Berkeley Lab.

    1981-10-15

    We report on the characteristics of the proportional tube chamber system which has been constructed for muon identification in the PEP-4 experiment at SLAC. The mechanical and electrical properties of the extruded aluminum triangular tubes allow these detectors to be used as crude drift chambers.

  7. Absorbed Dose Distributions in Irradiated Plastic Tubing and Wire Insulation

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1979-01-01

    Plastic tubing and wire insulation were simulated by radiochromic dye dosimeter films having electron absorbing properties similar to the materials of interest (polyethylene and PVC). A 400-keV electron accelerator was used to irradiate from 1, 2, 3 and 4 sides simulating possible industrial...

  8. Synthesis of Boron Nano wires, Nano tubes, and Nano sheets

    International Nuclear Information System (INIS)

    Patel, R.B.; Chou, T.; Iqbal, Z.

    2014-01-01

    The synthesis of boron nano wires, nano tubes, and nano sheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nano materials. The materials were made by using various combinations of MgB 2 , Mg(BH 4 ) 2 , MCM-41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nano wires, boron nano tubes, and boron nano sheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron-based materials have potential for electronic and hydrogen storage applications.

  9. Flow pattern assessment in tubes with wire coil inserts in laminar and transition regimes

    International Nuclear Information System (INIS)

    Garcia, A.; Solano, J.P.; Vicente, P.G.; Viedma, A.

    2007-01-01

    The paper presents an analysis of the flow mechanisms in tubes with wire coils using hydrogen bubble visualization and PIV techniques. Results have been contrasted with experimental data on pressure drop. The relation between the observed flow patterns and the friction factor has been analysed. The experimental analysis that has been carried out allows one to state that at low Reynolds numbers (Re < 400) the flow in tubes with wire coils is basically similar to the flow in smooth tubes. At Reynolds numbers between 500 and 700 and in short pitch wire coils a recirculating flow appears. The insertion of wires coils in a smooth tube accelerates significantly the transition to turbulence. This is produced at Reynolds numbers between 700 and 1000 depending on the wire pitch

  10. The effect of electrostatic and gravity force on offset wire inside tube

    Science.gov (United States)

    Oh, S. H.; Hazineh, D.; Wang, C.

    2018-04-01

    In a straw-tube detector, a wire that is offset with respect to the tube axis experiences a Coulomb force when high voltage is applied between the anode wire and the tube. This force results in a shifting of the wire and straw, in addition to the gravitational sag, and is a function of the tube and wire radius, initial offset, high voltage, tension and length. The presence of such effects is well known, but the precise magnitude of the shift for the anode wires under conditions of detector operation have not been previously documented with measurable confidence. In this work, we provide the first systematic measurements for the wire shift in straw-tube detectors due to gravity and the electrostatic force using an x-ray scanner developed for the Mu2e experiment. The data are compared to the solutions of the differential equations governing the system, and we find a good match between the two. The solutions can predict the final wire and straw positions from the initial positions measured without the high voltage, and the final wire and straw positions can then be used as an input to the track reconstruction software to improve the track position resolution.

  11. Apparatus for connecting an element attached to a metallic wire to an interior tube in a core drill

    Energy Technology Data Exchange (ETDEWEB)

    1970-04-17

    A locking device consists of at least one lever pivotable around an axis transversal to the axis of the core drill and mounted on the upper end of the core tube. A first arm oriented upward is intended to pivot during lowering of the wire line and to engage on the core tube, so that the core tube can be lifted by the wire line. A second arm prevents lifting of the core tube during drilling. The second arm also releases the core tube, after the wire line has been firmly attached and locked onto the core tube.

  12. Swirl flow analysis in a helical wire inserted tube using CFD code

    International Nuclear Information System (INIS)

    Park, Yusun; Chang, Soon Heung

    2010-01-01

    An analysis on the two-phase flow in a helical wire inserted tube using commercial CFD code, CFX11.0, was performed in bubbly flow and annular flow regions. The analysis method was validated with the experimental results of Takeshima. Bubbly and annular flows in a 10 mm inner diameter tube with varying pitch lengths and inserted wire diameters were simulated using the same analysis methods after validation. The geometry range of p/D was 1-4 and e/D was 0.08-0.12. The results show that the inserted wire with a larger diameter increased swirl flow generation. An increasing swirl flow was seen as the pitch length increased. Regarding pressure loss, smaller pitch lengths and inserted wires with larger diameters resulted in larger pressure loss. The average liquid film thickness increased as the pitch length and the diameter of the inserted wire increased in the annular flow region. Both in the bubbly flow and annular flow regions, the effect of pitch length on swirl flow generation and pressure loss was more significant than that of the inserted wire diameters. Pitch length is a more dominant factor than inserted wire diameter for the design of the swirl flow generator in small diameter tubes.

  13. AC magnetic transport on heterogeneous ferromagnetic wires and tubes

    International Nuclear Information System (INIS)

    Sinnecker, J.P.; Pirota, K.R.; Knobel, M.; Kraus, L.

    2002-01-01

    The AC current density radial distribution is calculated on heterogeneous composite materials with cylindrical geometry. The composites have an inner core and thin outer shell that can be either from the same material (homogenous material like simple wires) or from different materials with different physical properties. The case in which a non-magnetic inner core is surrounded by a magnetic layer, like electrodeposited wires, is mainly studied. The effect of frequency and applied magnetic field is simulated. The current density distribution as a function of frequency and applied field, as well as the total current over the inner core and outer shells are calculated. The results agree substantially well with the experimentally observed data for simple electrodeposited wires

  14. Pulsed positive corona streamer propagation and branching

    International Nuclear Information System (INIS)

    Veldhuizen, E.M. van; Rutgers, W.R.

    2002-01-01

    The propagation and branching of pulsed positive corona streamers in a short gap is observed with high resolution in space and time. The appearance of the pre-breakdown phenomena can be controlled by the electrode configuration, the gas composition and the impedance of the pulsed power circuit. In a point-wire gap the positive corona shows much more branching than in the parallel plane gap with a protrusion. In air, the branching is more pronounced than in argon. The pulsed power circuit appears to operate in two modes, either as an inductive circuit creating a lower number of thick streamers or as a resistive circuit giving a higher number of thin streamers. A possible cause for branching is electrostatic repulsion of two parts of the streamer head. The electric field at the streamer head is limited, the maximum values found are ∼170 kV cm -1 in air and ∼100 kV cm -1 in argon. At these maximum field strengths, the electrons have 5-10 eV energy, so the ionization is dominated by two-step processes. Differences between argon and ambient air in the field strength at which streamers propagate are ascribed to the difference in de-excitation processes in noble and molecular gases. The fact that the pulsed power circuit can control the streamer structure is important for applications, but this effect must also be taken into account in fundamental studies of streamer propagation and branching. (author)

  15. Pulsed positive corona streamer propagation and branching

    Energy Technology Data Exchange (ETDEWEB)

    Veldhuizen, E.M. van [Department of Physics, Technische Universiteit Eindhoven, Eindhoven (Netherlands)]. E-mail: e.m.v.veldhuizen@tue.nl; Rutgers, W.R. [Department of Physics, Technische Universiteit Eindhoven, Eindhoven (Netherlands)

    2002-09-07

    The propagation and branching of pulsed positive corona streamers in a short gap is observed with high resolution in space and time. The appearance of the pre-breakdown phenomena can be controlled by the electrode configuration, the gas composition and the impedance of the pulsed power circuit. In a point-wire gap the positive corona shows much more branching than in the parallel plane gap with a protrusion. In air, the branching is more pronounced than in argon. The pulsed power circuit appears to operate in two modes, either as an inductive circuit creating a lower number of thick streamers or as a resistive circuit giving a higher number of thin streamers. A possible cause for branching is electrostatic repulsion of two parts of the streamer head. The electric field at the streamer head is limited, the maximum values found are {approx}170 kV cm{sup -1} in air and {approx}100 kV cm{sup -1} in argon. At these maximum field strengths, the electrons have 5-10 eV energy, so the ionization is dominated by two-step processes. Differences between argon and ambient air in the field strength at which streamers propagate are ascribed to the difference in de-excitation processes in noble and molecular gases. The fact that the pulsed power circuit can control the streamer structure is important for applications, but this effect must also be taken into account in fundamental studies of streamer propagation and branching. (author)

  16. Mechanical properties of orthodontic wires covered with a polyether ether ketone tube.

    Science.gov (United States)

    Shirakawa, Nobukazu; Iwata, Toshio; Miyake, Shinjiro; Otuka, Takero; Koizumi, So; Kawata, Toshitugu

    2018-03-21

    To evaluate the esthetics and frictional force of an orthodontic wire passed through a newly designed tube made of a polyether ether ketone (PEEK) resin. Two types of standard PEEK tubes were prepared at 0.5 × 0.6ф and 0.8 × 0.9ф, and different archwires were passed through the tubes. Color values were determined according to brightness and hues. Friction was assessed with different bracket-wire combinations, and surface roughness was determined by stereomicroscopy before and after the application of friction. The PEEK tube showed a color difference that was almost identical to that of coated wires conventionally used in clinical practice, indicating a sufficient esthetic property. The result of the friction test showed that the frictional force was greatly reduced by passing the archwire through the PEEK tube in almost all of the archwires tested. Use of the new PEEK tube demonstrated a good combination of esthetic and functional properties for use in orthodontic appliances.

  17. AC dielectrophoresis alignment of single-walled carbon nano tubes (SWNTS) and palladium nano wires for hydrogen gas sensor

    International Nuclear Information System (INIS)

    Nur Ubaidah Saidin; Nur Ubaidah Saidin; Ying, K.K.; KKhuan, N.I.; Mohammad Hafizuddin Jumali

    2013-01-01

    Full-text: Using AC electric field, nano wires or nano tubes can be aligned, chained or accelerated in a direction parallel to the applied field, oriented or concentrated onto designated locations as well as dispersed in controlled manner under high efficiencies. In this work, systematic study on the alignment of nano wires/ nano tubes across the 3 μm-gaps between pairs of micro fabricated gold electrodes was carried out using AC dielectrophoresis technique. Densities and alignment of the nano wires/ nano tubes across the gaps of the electrodes were controlled by the applied AC field strengths and frequencies on the electrodes. Good alignments of SWNTs and Pd nano wires were achieved at an applied frequency of 5 MHz and a field strength as high as 25 V pp for Pd nano wires compared to only 2 V pp for SWNTs. The aligned nano wires/ nano tubes will be functioned as sensor elements for hydrogen gas sensing. (author)

  18. Anode wire in cylindrical cathode tube : destabilizing electrostatic force

    CERN Document Server

    Wertelaers, P

    2017-01-01

    A two-dimensional -- cross-sectional -- discussion suffices. The tube is offset, and the electrostatic potential is found analytically with perturbative methods. Then, the force is established with the Maxwell stress tensor. Alternatively, trying to find the force with energy methods, fails. Finally, finite element tests are performed in order to report on the degree of non-linearity for large offsets.

  19. The control of stainless steel tubes and wires of small diameter by the Eddy current method

    International Nuclear Information System (INIS)

    Stossel, A.; Gallet, G.

    1978-01-01

    Stainless steel tubes and wires with an outer diameter greater than 1 mm were studied by Eddy currents. The sensor characteristics and the detection of defects in function of frequency are presented together with the results obtained in the detection of dimensional and metallurgical defects [fr

  20. Preparation of Electrospun Polymer Fibers Using a Copper Wire Electrode in a Capillary Tube

    Science.gov (United States)

    Shinbo, Kazunari; Onozuka, Shintaro; Hoshino, Rikiya; Mizuno, Yoshinori; Ohdaira, Yasuo; Baba, Akira; Kato, Keizo; Kaneko, Futao

    2010-04-01

    Polymer fibers were prepared by an electrospinning method utilizing a copper wire electrode in a capillary tube. The morphology of electrospun poly(vinyl alcohol) (PVA) fibers was observed, and was found to be dependent on the wire electrode tip position in the capillary tube, the concentration of the polymer solution, the distance between the electrodes, and the applied voltage. By using the wire electrode, the experimental setup is simple and the distance between the electrodes and the applied voltage can be easily reduced. Furthermore, the preparation of poly(3-hexylthiophene) (P3HT) fibers was carried out. P3HT fibers were successfully prepared by mixing poly(ethylene oxide) (PEO) in P3HT solution. Orientation control was also carried out by depositing the fibers on a rotating collector electrode, and the alignment of the P3HT:PEO fibers was confirmed. Anisotropy of the optical absorption spectra was also observed for the aligned fibers.

  1. Drift tube with an electro-quadrupole magnet made with a conventional enamel wire for the proton engineering frontier project drift tube linac

    Science.gov (United States)

    Kim, Y. H.; Kwon, H. J.; Cho, Y. S.

    2006-12-01

    The proton engineering frontier project (PEFP) drift tube linac (DTL) chose the new type of electro-quadrupole magnet (EQM) using an enameled wire for a drift tube. By using this kind of EQM, we could simplify the drift tube structure. We verified the structural stability and thermal stability of this drift tube structure through a computational analysis and a simple experiment. We also verified the stability of the enameled wire regarding corrosion through a long period test of about 1 year. It was concluded that the design and fabrication of the drift tube and the EQM were successful.

  2. Drift tube with an electro-quadrupole magnet made with a conventional enamel wire for the proton engineering frontier project drift tube linac

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.H. [PEFP, KAERI, DaeJeon (Korea, Republic of)]. E-mail: yhkim72@kaeri.re.kr; Kwon, H.J. [PEFP, KAERI, DaeJeon (Korea, Republic of); Cho, Y.S. [PEFP, KAERI, DaeJeon (Korea, Republic of)

    2006-12-21

    The proton engineering frontier project (PEFP) drift tube linac (DTL) chose the new type of electro-quadrupole magnet (EQM) using an enameled wire for a drift tube. By using this kind of EQM, we could simplify the drift tube structure. We verified the structural stability and thermal stability of this drift tube structure through a computational analysis and a simple experiment. We also verified the stability of the enameled wire regarding corrosion through a long period test of about 1 year. It was concluded that the design and fabrication of the drift tube and the EQM were successful.

  3. Drift tube with an electro-quadrupole magnet made with a conventional enamel wire for the proton engineering frontier project drift tube linac

    International Nuclear Information System (INIS)

    Kim, Y.H.; Kwon, H.J.; Cho, Y.S.

    2006-01-01

    The proton engineering frontier project (PEFP) drift tube linac (DTL) chose the new type of electro-quadrupole magnet (EQM) using an enameled wire for a drift tube. By using this kind of EQM, we could simplify the drift tube structure. We verified the structural stability and thermal stability of this drift tube structure through a computational analysis and a simple experiment. We also verified the stability of the enameled wire regarding corrosion through a long period test of about 1 year. It was concluded that the design and fabrication of the drift tube and the EQM were successful

  4. Stress-strain effects on powder-in-tube MgB2 tapes and wires

    International Nuclear Information System (INIS)

    Katagiri, Kazumune; Takaya, Ryuya; Kasaba, Koichi; Tachikawa, Kyoji; Yamada, Yutaka; Shimura, Satoshi; Koshizuka, Naoki; Watanabe, Kazuo

    2005-01-01

    The effects of stress-strain on the critical current, I c , of ex situ powder-in-tube (PIT)-processed Ni-sheathed MgB 2 tapes and round wires as well as in situ PIT-processed Cu-sheathed wires at 4.2 K in a magnetic field up to 5 T have been studied. The effect of In powder addition on the Ni-sheathed MgB 2 wire was not so clear compared with that in the tape, in which the irreversible strain, ε irr , for the I c degradation onset increases significantly by the addition. This is attributed to the difference in the microstructure of the core associated with cold workings. A peak and gradual degradation behaviour of I c with strain beyond ε irr was found in the wire, whereas no evident peak and a steep degradation behaviour was found in the tape. As a possible reason, the difference in the triaxial residual stress state at 4.2 K due to the difference in geometry of the cross-section is suspected. The transverse compression tests revealed that I c of the wire did not degrade up to 270 MPa. Again, the effect of In addition was minimal. The Young's modulus of MgB 2 , 31-41 GPa, at room temperature was estimated by a tensile test of Cu sheath wire using a high-accuracy extensometer and the law of mixtures. The tensile strain dependence of I c in the Cu sheath wire was similar to that in the Ni-sheathed wire, ε irr being 0.4%. However, the stress corresponding to ε irr , 50 MPa, was about 1/10 of that for the Ni-sheath wire and the irreversible transverse compressive stress, 150 MPa, was also lower. The effect of bending strain on the I c in Cu-sheathed wire was compared with that of the tensile strain

  5. Semiconductor Nano wires and Nano tubes: From Fundamentals to Diverse Applications

    International Nuclear Information System (INIS)

    Xiong, Q.; Grimes, C.A.; Zacharias, M.; Morral, A.F.; Hiruma, K.; Shen, G.

    2012-01-01

    Research in the field of semiconductor nano wires (SNWs) and nano tubes has been progressing into a mature subject with several highly interdisciplinary sub areas such as nano electronics, nano photonics, nano composites, bio sensing, optoelectronics, and solar cells. SNWs represent a unique system with novel properties associated to their one-dimensional (1D) structures. The fundamental physics concerning the formation of discrete 1D subbands, coulomb blockade effects, ballistic transport, and many-body phenomena in 1D nano wires and nano tubes provide a strong platform to explore the various scientific aspects in these nano structures. A rich variety of preparation methods have already been developed for generating well-controlled 1D nano structures and from a broad range of materials. The present special issue focuses on the recent development in the mechanistic understanding of the synthesis, the studies on electrical/optical properties of nano wires and their applications in nano electronics, nano photonics, and solar-energy harvesting. In this special issue, we have several invited review articles and contributed papers that are addressing current status of the fundamental issues related to synthesis and the diverse applications of semiconducting nano wires and nano tubes. One of the papers reviews the progress of the top-down approach of developing silicon-based vertically aligned nano wires to explore novel device architectures and integration schemes for nano electronics and clean energy applications. Another paper reviews the recent developments and experimental evidences of probing the confined optical and acoustic phonon in nonpolar semiconducting (Si and Ge) nano wires using Raman spectroscopy. The paper by K. Hiruma et al. spotlights the III semiconductor nano wires and demonstrates selective-area metal organic vapor phase epitaxy grown GaAs/In(Al)GaAs and InP/InAs/InP nano wires with heterojunctions along their axial and radial directions. The paper

  6. Impact of different rectangular wires on torsional expression of different sizes of buccal tube.

    Science.gov (United States)

    Ajami, Shabnam; Boroujeni, Afshar-Rasti

    2018-01-01

    Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes. 60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups. The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube. The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle.

  7. 50 K anomalies in superconducting MgB{sub 2} wires in copper and silver tubes

    Energy Technology Data Exchange (ETDEWEB)

    Majoros, M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Glowacki, B A [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Cambridge (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom); Vickers, M E [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom)

    2002-02-01

    In situ and ex situ MgB{sub 2} wires were prepared by the powder-in-tube method. Copper and silver tubes were used as a cladding material. AC susceptibility measurements revealed a small anomalous decrease with onset around 50 K. This effect persisted also when the wires were ground into powders. Electron microscopy and x-ray studies were performed on copper clad samples. Spectroscopic measurements in a SEM showed that regions contained either Cu or Mg and B. X-ray diffraction gave the major crystalline phases as Cu, MgCu{sub 2} and MgB{sub 2}. Diffraction evidence for Cu substituting in the Mg position was inconclusive. (author)

  8. Catheters, wires, tubes and drains on postoperative radiographs of pediatric cardiac patients: the whys and wherefores

    Energy Technology Data Exchange (ETDEWEB)

    Teele, Sarah A.; Thiagarajan, Ravi R. [Children' s Hospital Boston, Department of Cardiology, Boston, MA (United States); Harvard Medical School, Department of Pediatrics, Boston, MA (United States); Emani, Sitaram M. [Children' s Hospital Boston, Department of Cardiac Surgery, Boston, MA (United States); Harvard Medical School, Department of Surgery, Boston, MA (United States); Teele, Rita L. [Harvard Medical School, Department of Radiology, Boston, MA (United States); Starship Children' s Hospital, Department of Radiology, Grafton (New Zealand)

    2008-10-15

    Surgical treatment of congenital heart disease has advanced dramatically since the first intracardiac repairs in the mid-20th century. Previously inoperable lesions have become the focus of routine surgery and patients are managed successfully in intensive care units around the world. As a result, increasing numbers of postoperative images are processed by departments of radiology in children's hospitals. It is important that the radiologist accurately documents and describes the catheters, wires, tubes and drains that are present on the chest radiograph. This article reviews the reasons for the placement and positioning of perioperative equipment in children who have surgical repair of atrial septal defect, ventricular septal defect or transposition of the great arteries. Also included are a brief synopsis of each cardiac anomaly, the surgical procedure for its correction, and an in-depth discussion of the postoperative chest radiograph including illustrations of catheters, wires, tubes and drains. (orig.)

  9. Catheters, wires, tubes and drains on postoperative radiographs of pediatric cardiac patients: the whys and wherefores

    International Nuclear Information System (INIS)

    Teele, Sarah A.; Thiagarajan, Ravi R.; Emani, Sitaram M.; Teele, Rita L.

    2008-01-01

    Surgical treatment of congenital heart disease has advanced dramatically since the first intracardiac repairs in the mid-20th century. Previously inoperable lesions have become the focus of routine surgery and patients are managed successfully in intensive care units around the world. As a result, increasing numbers of postoperative images are processed by departments of radiology in children's hospitals. It is important that the radiologist accurately documents and describes the catheters, wires, tubes and drains that are present on the chest radiograph. This article reviews the reasons for the placement and positioning of perioperative equipment in children who have surgical repair of atrial septal defect, ventricular septal defect or transposition of the great arteries. Also included are a brief synopsis of each cardiac anomaly, the surgical procedure for its correction, and an in-depth discussion of the postoperative chest radiograph including illustrations of catheters, wires, tubes and drains. (orig.)

  10. Stability of Streamer Chamber

    Science.gov (United States)

    Wada, Toshiaki; Ogawa, Masato; Takahashi, Kaoru; Sugiyama, Tsunetoshi; Kobayashi, Shigeharu; Kohno, Hirobumi

    1982-08-01

    The quality of tracks obtained from a streamer chamber is studied through the measurement of the streamer brightness. The stability of streamer tracks depends on the value of the high voltage applied and its shape. By using a single conical-type spark gap as the pulse shaper, stable brightness of the streamer tracks is attained. The data on the streamer brightness are compared with the result by Bulos et al. and it is found that the brightness is more strongly affected by field parameters than in their result.

  11. Stability of streamer chamber

    International Nuclear Information System (INIS)

    Wada, Toshiaki; Ogawa, Masato; Takahashi, Kaoru; Sugiyama, Tsunetoshi; Kobayashi, Shigeharu; Kohno, Hirobumi.

    1982-01-01

    The quality of tracks obtained from a streamer chamber is studied through the measurement of the streamer brightness. The stability of streamer tracks depends on the value of the high voltage applied and its shape. By using a single conical-type spark gap as the pulse shaper, stable brightness of the streamer tracks is attained. The data on the streamer brightness are compared with the result by Bulos et al. and it is found that the brightness is more strongly affected by field parameters than in their result. (author)

  12. Magnetic properties of multisegmented cylindrical nanoparticles with alternating magnetic wire and tube segments

    Energy Technology Data Exchange (ETDEWEB)

    Salazar-Aravena, D.; Corona, R.M. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Goerlitz, D.; Nielsch, K. [Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Escrig, J., E-mail: jescrigm@gmail.com [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2013-11-15

    The magnetic properties in multisegmented cylindrical nanostructures comprised of nanowire and nanotube segments are investigated numerically as a function of their geometry. In this work we report systematic changes in the coercivity and remanence in these systems. Besides, we have found the ideal conditions for a magnetic configuration with two antiparallel domains that could be used to help to stabilize magnetic nanoparticles inside ferromagnetic multisegmented cylindrical nanoparticles. This magnetic behavior is due to the fact that the tube segment reverses its magnetization before the wire segment, allowing the control of the magnetic domain walls motion between two segments. In this way, these magnetic nanoobjects can be an alternative to store information or even perform logic functions. - Highlights: • Magnetic states of wire/tube were investigated as a function of their geometry. • Multisegmented systems present two well-defined jumps in the hysteresis curve. • It is possible to prepare an antiparallel magnetic configuration. • The step width for the optimum condition reaches 60 mT. • The tube segments reverse their magnetization first than the wire segments.

  13. Structure of Polymer Fibers Fabricated by Electrospinning Method Utilizing a Metal Wire Electrode in a Capillary Tube

    Science.gov (United States)

    Onozuka, Shintaro; Hoshino, Rikiya; Mizuno, Yoshinori; Shinbo, Kazunari; Ohdaira, Yasuo; Baba, Akira; Kato, Keizo; Kaneko, Futao

    We fabricated electrospun poly (vinylalcohol) (PVA) fibers using a copper wire electrode in Teflon capillary tube, and the SEM images were observed. The apparatus in this method is reasonable, and needed volume of polymer solution and distance between the electrodes can be largely reduced compared to conventional method. The wire electrode tip position in the capillary tube is also important in this method and should be close to the polymer solution surface.

  14. Superconductivity of powder-in-tube MgB{sub 2} wires

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B A; Evetts, J E [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Majoros, M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Institute of Electrical Engineering, Slovak Academy of Science, Dubravska Cesta 9, Bratislava (Slovakia); Vickers, M [Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Shi, Y [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); McDougall, I [Oxford Instruments Plc, Eynsham, OX8 ITL (United Kingdom)

    2001-04-01

    A new class of 'powder-in-tube' Mg-B superconducting conductors has been prepared using two different methods: an in situ technique where an Mg + 2B mixture was used as a central conductor core and reacted in situ to form MgB{sub 2}, and an ex situ technique where fully reacted MgB{sub 2} powder was used to fill the metal tube. Conductors were prepared using silver, copper and bimetallic silver/stainless steel tubes. Wires manufactured by the in situ technique, diffusing Mg to B particles experienced {approx}25.5% decrease in density from the initial value after cold deformation, due to the phase transformation from Mg + 2({beta}-B){yields}MgB{sub 2} all with hexagonal structure. A comparative study of the intergranular current and grain connectivity in wires was conducted by AC susceptibility measurements and direct four point transport measurements. Using a SQUID magnetometer, magnetization versus magnetic field (M-H) curves of the round wires before and after sintering and reactive diffusion were measured at 5 K and in magnetic fields up to 5 T to define the J{sub cmag}. The direct current measurements were performed in self field at 4.2 K. A comparison between zero-field-cooled (ZFC) and field-cooled (FC) susceptibility measurements for sintered Ag/MgB{sub 2}, and reacted Cu/Mg + 2B conductors revealed systematic differences in the flux pinning in the wires which is in very good agreement with direct high transport current measurements. (author)

  15. Superconductivity of powder-in-tube MgB{sub 2} wires

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B.A.; Evetts, J.E. [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Majoros, M. [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); Institute of Electrical Engineering, Slovak Academy of Science, Dubravska Cesta 9, Bratislava (Slovakia); Vickers, M. [Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Shi, Y. [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge, CB3 OHE (United Kingdom); McDougall, I. [Oxford Instruments Plc, Eynsham, OX8 ITL (United Kingdom)

    2001-04-01

    A new class of 'powder-in-tube' Mg-B superconducting conductors has been prepared using two different methods: an in situ technique where an Mg + 2B mixture was used as a central conductor core and reacted in situ to form MgB{sub 2}, and an ex situ technique where fully reacted MgB{sub 2} powder was used to fill the metal tube. Conductors were prepared using silver, copper and bimetallic silver/stainless steel tubes. Wires manufactured by the in situ technique, diffusing Mg to B particles experienced {approx}25.5% decrease in density from the initial value after cold deformation, due to the phase transformation from Mg + 2({beta}-B){yields}MgB{sub 2} all with hexagonal structure. A comparative study of the intergranular current and grain connectivity in wires was conducted by AC susceptibility measurements and direct four point transport measurements. Using a SQUID magnetometer, magnetization versus magnetic field (M-H) curves of the round wires before and after sintering and reactive diffusion were measured at 5 K and in magnetic fields up to 5 T to define the J{sub cmag}. The direct current measurements were performed in self field at 4.2 K. A comparison between zero-field-cooled (ZFC) and field-cooled (FC) susceptibility measurements for sintered Ag/MgB{sub 2}, and reacted Cu/Mg + 2B conductors revealed systematic differences in the flux pinning in the wires which is in very good agreement with direct high transport current measurements. (author)

  16. Development of extruded resistive plastic tubes for proportional chamber cathodes

    International Nuclear Information System (INIS)

    Kondo, K.

    1982-01-01

    Carbon mixed plastic tubes with resistivity of 10 3 approx. 10 4 Ωcm have been molded with an extrusion method and used for the d.c. cathode of a proportional counter and a multi-wire proportional chamber. The signal by gas multiplication was picked up from a strip r.f. cathode set outside the tube. The characteristics of the counter in the proportional and limited streamer modes have been studied

  17. Proceedings of workshop on streamer chamber

    International Nuclear Information System (INIS)

    Itoh, Hidihiko; Takahashi, Kaoru; Hirose, Tachishige; Masaike, Akira

    1978-08-01

    For high accuracy observation of multiple-body reactions, a vertex detector of high efficiency is essential. A bubble chamber, though excellent for tracks detection, is problematic in statistics accuracy. The vertex detector with a wire chamber, while better in this respect, difficult in multiple-particle detection etc. The workshop has had several meetings on a streamer chamber as a detector combining features of both bubble chamber and counter, with emphasis on tracks observation in avalanche mode and recordings not using films. Contents are on streamer chamber gas, analytical photography, data processing, simulation program, etc. (Mori, K.)

  18. Heat transfer experiments in a wire-inserted tube at supercritical pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yoon Yeong; Kim, Hwan Yeol; Yoo, Tae Ho

    2009-07-15

    The hydraulic diameter of a subchannel in a core concept developed at KAERI is 6.5 mm. The sub-channel is much smaller than that of the conventional PWR, and naturally a helical wire was considered as one of the candidates for a spacer. For simplicity the subchannel is simulated by a commercially available Inconel 625 tube of 6.32 mm ID with a helically-coiled spring steel wire insert of 1.3 mm OD. The medium is CO{sub 2}. The test pressures are 7.75 and 8.12 MPa corresponding to 1.05 and 1.1 times the critical pressure of CO{sub 2}, respectively. The mass flux and heat flux, which were in the range of 400 {approx} 1200 kg/m{sup 2}s and 30 {approx} 90 kW/m{sup 2} respectively, were varied at a given system pressure. The corresponding Reynolds numbers at the inlet spans between 2.5 x 10{sup 4} and 7.5 x 10{sup 4}. It was observed that the heat transfer was enhanced by almost twice in most of the tested enthalpy range except for in the the region far from the pseudocritical point. The test results revealed that the wire effect was sustained in the downstream up to 40-60 times the wire diameter. The temperature decreased in the first half of the span between contact points and it increased in the second half of the span.

  19. Current-driven vortex domain wall motion in wire-tube nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Espejo, A. P. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Vidal-Silva, N. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); López-López, J. A. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Goerlitz, D.; Nielsch, K. [Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Av. Ecuador 3493, 9170124 Santiago (Chile)

    2015-03-30

    We have investigated the current-driven domain wall motion in nanostructures comprised of a pair of nanotube and nanowire segments. Under certain values of external magnetic fields, it is possible to pin a vortex domain wall in the transition zone between the wire and tube segments. We explored the behavior of this domain wall under the action of an electron flow applied in the opposite direction to the magnetic field. Thus, for a fixed magnetic field, it is possible to release a domain wall pinned simply by increasing the intensity of the current density, or conversely, for a fixed current density, it is possible to release the domain wall simply decreasing the magnetic external field. When the domain wall remains pinned due to the competition between the current density and the magnetic external field, it exhibits a oscillation frequency close to 8 GHz. The amplitude of the oscillations increases with the current density and decreases over time. On the other hand, when the domain wall is released and propagated through the tube segment, this shows the standard separation between a steady and a precessional regime. The ability to pin and release a domain wall by varying the geometric parameters, the current density, or the magnetic field transforms these wire-tube nanostructures in an interesting alternative as an on/off switch nano-transistor.

  20. Decompression Device Using a Stainless Steel Tube and Wire for Treatment of Odontogenic Cystic Lesions: A Technical Report.

    Science.gov (United States)

    Jung, Eun-Joo; Baek, Jin-A; Leem, Dae-Ho

    2014-11-01

    Decompression is considered an effective treatment for odontogenic cystic lesions in the jaw. A variety of decompression devices are successfully used for the treatment of keratocystic odontogenic tumors, radicular cysts, dentigerous cysts, and ameloblastoma. The purpose of these devices is to keep an opening between the cystic lesion and the oral environment during treatment. The aim of this report is to describe an effective decompression tube using a stainless steel tube and wire for treatment of jaw cystic lesions.

  1. Design and fabrication of Sn-Nb-Cu-Ta-C composites for multifilamentary superconducting Nb/sub 3/Sn wires by using the modified tube technique

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B A; Kosek, Z M

    1987-10-01

    The factors determining the design and fabrication of Nb/sub 3/Sn multifilamentary wires by the tube technique are discussed. New improved methods of obtaining multifilamentary Nb/sub 3/Sn wires on the basis of both external diffusion and internal diffusion processes, by using the tube technique in a simpler and less expensive way, are presented.

  2. Streamer chamber: pion decay

    CERN Multimedia

    1992-01-01

    The real particles produced in the decay of a positive pion can be seen in this image from a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. A magnetic field is added to cause the decay products to follow curved paths so that their charge and momentum can be measured.

  3. A study of bubbly flow characteristics in a vertical tube using wire mesh tomography

    International Nuclear Information System (INIS)

    Wangjiraniran, Weerin; Motegi, Yuichi; Kikura, Hiroshige; Aritomi, Masanori; Richter, Steffen; Yamamoto, Kazuhiko

    2003-01-01

    For the development of nuclear reactors and the assessment of their safety features, the development of computer code with the high quantity database from the measurement as well as the understanding of the multiphase flow physics are necessary. In this study, the characteristics of bubbly flow in a vertical tube are investigated using Wire Mesh Tomography (WMT). Void fraction is detected from the dependency of electrical conductivity on the local void fraction. The developed sensor is a circular type with two parallel measuring planes to have the capability of gas velocity and bubble size evaluation. The experiment is conducted in a 50 mm ID tube at the fully developed condition (93D). The mean bubble size is treated as a constant parameter independent from the superficial gas and liquid velocity by using the bubble generator with a water sub flow. The result shows the capability of WMT for bubbly flow characteristic study. The effects of superficial gas and liquid velocity and the additional bubble intensity on the void fraction distribution are presented. These effects are supposed to change the lateral lift force in both magnitude and directions which induce the bubble migrated toward to or depart from the wall. (author)

  4. Temperature and pressure effects on the properties of positive streamers in air

    NARCIS (Netherlands)

    Huiskamp, T.; Heesch, van E.J.M.; Beckers, F.J.C.M.; Hoeben, W.F.L.M.; Pemen, A.J.M.

    2012-01-01

    In this paper we present experimental results on how the properties of positive, pulsed streamers in air depend on E/n (E is the applied electric field and n is the gas density). Streamers are generated in a wire-cylinder reactor at constant voltage (so constant E). The density is changed either by

  5. Stress-strain effects in alumina-Cu reinforced Nb3Sn wires fabricated by the tube process

    International Nuclear Information System (INIS)

    Murase, Satoru; Nakayama, Shigeo; Masegi, Tamaki; Koyanagi, Kei; Nomura, Shunji; Shiga, Noriyuki; Kobayashi, Norio; Watanabe, Kazuo.

    1997-01-01

    In order to fabricate a large-bore, high-field magnet which achieves a low coil weight and volume, a high strength compound superconducting wire is required. For those demands we have developed the reinforced Nb 3 Sn wire using alumina dispersion strengthened copper (alumina-Cu) as a reinforcement material and the tube process of the Nb 3 Sn wire fabrication. The ductility study of the composites which consisted of the reinforcement, Nb tube, Cu, and Cu clad Sn brought a 1 km long alumina-Cu reinforced Nb 3 Sn wire successfully. Using fabricated wires measurements and evaluations of critical current density as parameters of magnetic field, tensile stress, tensile strain, and transverse compressive stress, and those of stress-strain curves at 4.2 K were performed. They showed superior performance such as high 0.3% proof stress (240 MPa at 0.3% strain) and high maximum tolerance stress (320 MPa) which were two times as large as those of conventional Cu matrix Nb 3 Sn wire. The strain sensitivity parameters were obtained for the reinforced Nb 3 Sn wire and the Cu matrix one using the scaling law. Residual stress of the component materials caused by cooling down to 4.2 K from heat-treatment temperature was calculated using equivalent Young's modulus, equivalent yield strength, thermal expansion coefficient and other mechanical parameters. Calculated stress-strain curves at 4.2 K for the reinforced Nb 3 Sn wire and the Cu matrix one based on calculation of residual stress, had good agreement with the experimental values. (author)

  6. Reconnection and merging of positive streamers in air

    Energy Technology Data Exchange (ETDEWEB)

    Nijdam, S; Geurts, C G C; Van Veldhuizen, E M; Ebert, U, E-mail: s.nijdam@tue.n [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2009-02-21

    Pictures show that streamer or sprite discharge channels emerging from the same electrode sometimes seem to reconnect or merge though their heads carry electric charge of the same polarity; one might therefore suspect that reconnections are an artefact of the two-dimensional projection in the pictures. Here we use stereo photography to investigate the full three-dimensional structure of such events. We analyse reconnection, possibly an electrostatic effect in which a late thin streamer reconnects to an earlier thick streamer channel, and merging, a suggested photoionization effect in which two simultaneously propagating streamer heads merge into one new streamer. We use four different anode geometries (one tip, two tips, two asymmetric protrusions in a plate and a wire), placed 40 mm above a flat cathode plate in ambient air. A positive high voltage pulse is applied to the anode, creating a positive corona discharge. This discharge is studied with a fast ICCD camera, in many cases combined with optics to enable stereoscopic imaging. We find that reconnections as defined above occur frequently. Merging on the other hand was only observed at a pressure of 25 mbar and a tip separation of 2 mm, i.e. for a reduced tip distance of p{center_dot}d = 50 {mu}m bar. In this case the full width at half maximum of the streamer channel is more than 10 times as large as the tip separation. At higher pressures or with a wire anode, merging was not observed.

  7. Reconnection and merging of positive streamers in air

    International Nuclear Information System (INIS)

    Nijdam, S; Geurts, C G C; Van Veldhuizen, E M; Ebert, U

    2009-01-01

    Pictures show that streamer or sprite discharge channels emerging from the same electrode sometimes seem to reconnect or merge though their heads carry electric charge of the same polarity; one might therefore suspect that reconnections are an artefact of the two-dimensional projection in the pictures. Here we use stereo photography to investigate the full three-dimensional structure of such events. We analyse reconnection, possibly an electrostatic effect in which a late thin streamer reconnects to an earlier thick streamer channel, and merging, a suggested photoionization effect in which two simultaneously propagating streamer heads merge into one new streamer. We use four different anode geometries (one tip, two tips, two asymmetric protrusions in a plate and a wire), placed 40 mm above a flat cathode plate in ambient air. A positive high voltage pulse is applied to the anode, creating a positive corona discharge. This discharge is studied with a fast ICCD camera, in many cases combined with optics to enable stereoscopic imaging. We find that reconnections as defined above occur frequently. Merging on the other hand was only observed at a pressure of 25 mbar and a tip separation of 2 mm, i.e. for a reduced tip distance of p·d = 50 μm bar. In this case the full width at half maximum of the streamer channel is more than 10 times as large as the tip separation. At higher pressures or with a wire anode, merging was not observed.

  8. A large streamer chamber muon tracking detector in a high-flux fixed-target application

    CERN Document Server

    Adams, D; Adeva, B; Arik, E; Arvidson, A; Badelek, B; Ballintijn, M K; Bardin, G; Baum, G; Berglund, P; Betev, L; Bird, I G; Birsa, R; Björkholm, P; Bonner, B E; De Botton, N R; Boutemeur, M; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Cavata, C; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Dyring, A; Eichblatt, S; Faivre, Jean-Claude; Fasching, D; Feinstein, F; Fernández, C; Forthmann, S; Frois, Bernard; Gallas, A; Garabatos, C; Garzón, J A; Gaussiran, T; Gilly, H; Giorgi, M A; von Goeler, E; Görtz, S; Golutvin, I A; Gómez-Tato, A; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Gülmez, E; Haft, K; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Karev, A G; Kessler, H J; Ketel, T; Kiryluk, J; Kiryushin, Yu T; Kishi, A; Kiselev, Yu F; Klostermann, L; Krämer, Dietrich; Kröger, W; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Lau, K; Layda, T; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Lindqvist, T; Litmaath, M; Loewe, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Meyer, W T; Van Middelkoop, G; Miller, D; Miyachi, Y; Mori, K; Moromisato, J H; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Parks, D P; Pereira, H; Penzo, Aldo L; Perrot-Kunne, F; Peshekhonov, V D; Piegaia, R; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Pussieux, T; Pyrlik, J; Rädel, G; Reyhancan, I; Reicherz, G; Rijllart, A; Roberts, J B; Rock, S E; Rodríguez, M; Rondio, Ewa; Rosado, A; Roscherr, B; Sabo, I; Saborido, J; Sandacz, A; Sanders, D; Savin, I A; Schiavon, R P; Schiller, A; Schüler, K P; Segel, R E; Seitz, R; Semertzidis, Y K; Sergeev, S; Sever, F; Shanahan, P; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Teichert, K M; Tessarotto, F; Thers, D; Tlaczala, W; Trentalange, S; Tripet, A; Tzamouranis, Yu; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Weinstein, R; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Zamiatin, N I; Zanetti, A M; Zaremba, K; Zhao, J

    1999-01-01

    Arrays of limited streamer tubes of the Iarocci type were deployed in our experiment at CERN as part of a forward muon detector system with provisions for the beam to pass through the center of each panel in the array. A total of sixteen 4 m x 4 m panels were assembled with inductive readout strips on both sides of each panel. An active feedback system was deployed to regulate the high voltage to the streamer tubes to insure a constant efficiency for minimum ionizing particles. The arrays were operated in this environment for over five years of data taking. Streamer tube track-reconstruction efficiencies and tube replacement rates are reported.

  9. Progress in Effect of Nano-modified Coatings and Welding Process Parameters on Wear of Contact Tube for Non-copper Coated Solid Wires

    Directory of Open Access Journals (Sweden)

    LI Zhuo-xin

    2017-12-01

    Full Text Available Environment-friendly non-copper coated solid wire is the main developing trend for gas shielded solid wires, whereas wear of contact tube limits their wide application. The effect of nano-modified coatings and welding process parameters on wear of contact tube for non-copper coated solid wires was reviewed. It was found that the wear of contact tube can be reduced due to the formation of tribo-films on the rubbing surfaces of welding wires against contact tube; it is feasible to decrease contact tube wear when non-copper coated solid wires are coated with nano-modified lubricants, thereby displaying excellent lubricating and thermal or electrical conduction characteristics. The wear of contact tube increases with the increase of welding current. The wear of contact tube is worse in direct-current electrode positive (DCEP than in direct-current electrode negative (DCEN. Arc ablation and electrical erosion are the dominant wear mechanisms of contact tube.

  10. Fabrication and properties of multifilamentary MgB 2 wires by in-situ powder-in-tube process

    Science.gov (United States)

    Wang, Q. Y.; Jiao, G. F.; Liu, G. Q.; Xiong, X. M.; Yan, S. C.; Zhang, P. X.; Sulpice, A.; Mossang, E.; Feng, Y.; Yan, G.

    2010-11-01

    We have fabricated the long TiC-doped MgB2 wires with 6 filaments by in-situ powder-in-tube method using Nb as the barrier and copper as the stabilizer. To improve the strength of wires, the Nb-core was used as the central filament. The transport engineering critical current density (Jce) of the samples sintered at different temperature were measured, which reaches 2.5 × 104 A/cm2 at 4.2 K, 5 T. 100 m MgB2 wires with different diameter were wound into coils and the transport critical current (Ic) of the coil were measured at 30 K in self-field. The Jce value 100 m coil achieves 1.1 × 104 A/cm2 in 1.2 mm wire. The reasons leading to the enhancement of high field Jce were discussed. The results show a good potential to fabricate high performance MgB2 wires and tapes at ambient pressure on an industrial scale.

  11. Influence of particle size of Mg powder on the microstructure and critical currents of in situ powder-in-tube processed MgB_2 wires

    International Nuclear Information System (INIS)

    Kumakura, Hiroaki; Ye, Shujun; Matsumoto, Akiyoshi; Nitta, Ryuji

    2016-01-01

    We fabricated in situ powder-in-tube(PIT) MgB_2 wires using three kinds of Mg powders with particle size of ∼45 μm, ∼150 μm and 212∼600 μm. Mg particles were elongated to filamentary structure in the wires during cold drawing process. Especially, long Mg filamentary structure was obtained for large Mg particle size of 212∼600 μm. Critical current density, J_c, increased with increasing Mg particle size for 1 mm diameter wires. This is due to the development of filamentary structure of high density MgB_2 superconducting layer along the wires. This MgB_2 structure is similar to that of the internal Mg diffusion (IMD) processed MgB_2 wires. However, J_c of the wires fabricated with 212∼600 μm Mg particle size decreased and the scattering of J_c increased with decreasing wire diameter, while the J_c of the wires with ∼45 μm Mg particle was almost independent of the wire diameter. The cross sectional area reduction of the Mg particles during the wire drawing is smaller than that of the wire. When using large size Mg particle, the number of Mg filaments in the wire cross section is small. These two facts statistically lead to the larger scattering of Mg areal fraction in the wire cross section with proceeding of wire drawing process, resulting in smaller volume fraction of MgB_2 in the wire and lower J_c with larger scattering along the wire. SiC nano powder addition is effective in increasing J_c for all Mg particle sizes. (author)

  12. A novel pulsed corona discharge reactor based on surface streamers for diesel exhaust remediation

    Energy Technology Data Exchange (ETDEWEB)

    Malik, M.A.; Schoenbach, K.H. [Old Dominion Univ., Norfolk, VA (United States). Frank Reidy Research Center for Bioelectrics

    2010-07-01

    Modelling of surface streamers along insulating surfaces to determine the dielectric strength of insulators in high voltage systems has shown that surface streamers consist of a positive streamer head followed by quasi-neutral plasma in the channel behind and surrounded by a layer of positive charges. This paper described a novel pulsed corona discharge reactor which utilized such surface streamers along insulating surfaces. The electrodes were comprised of a stainless steel wire anode of 150 mm in diameter stretched along the surface of a glass sheet and two parallel aluminum strips as cathodes. An eight-stage Marx bank, was used to produce the surface streamers in nitrogen-oxygen mixtures at atmospheric pressure. The paper described the experimental study with particular reference to the schematics of a surface streamer plasma reactor and the dimensions of discharge spaces of three reactors. The purpose of the study was to find the optimum conditions for energy yield and effective destruction of nitrogen oxides from diesel engine exhaust. It was concluded that surface streamers generate a more diffuse plasma. Energy costs for production of ozone or nitrogen dioxide that require reactions with bulk gas molecules were nearly the same in surface streamer discharges as in volume streamer discharges. 12 refs., 1 tab., 7 figs.

  13. The multiscale nature of streamers

    International Nuclear Information System (INIS)

    Ebert, U; Montijn, C; Briels, T M P; Hundsdorfer, W; Meulenbroek, B; Rocco, A; Veldhuizen, E M van

    2006-01-01

    Streamers are a generic mode of electric breakdown of large gas volumes. They play a role in the initial stages of sparks and lightning, in technical corona reactors and in high altitude sprite discharges above thunderclouds. Streamers are characterized by a self-generated field enhancement at the head of the growing discharge channel. We briefly review recent streamer experiments and sprite observations. Then we sketch our recent work on computations of growing and branching streamers, we discuss concepts and solutions of analytical model reductions and we review different branching concepts and outline a hierarchy of model reductions

  14. The multiscale nature of streamers

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, U [Centrum voor Wiskunde en Informatica (CWI), PO Box 94079, 1090GB Amsterdam (Netherlands); Faculty of Physics, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Montijn, C [Centrum voor Wiskunde en Informatica (CWI), PO Box 94079, 1090GB Amsterdam (Netherlands); Briels, T M P [Faculty of Physics, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Hundsdorfer, W [Centrum voor Wiskunde en Informatica (CWI), PO Box 94079, 1090GB Amsterdam (Netherlands); Meulenbroek, B [Centrum voor Wiskunde en Informatica (CWI), PO Box 94079, 1090GB Amsterdam (Netherlands); Rocco, A [Centrum voor Wiskunde en Informatica (CWI), PO Box 94079, 1090GB Amsterdam (Netherlands); University of Oxford, Department of Statistics, 1 South Parks Road, Oxford OX1 3TG (United Kingdom); Veldhuizen, E M van [Faculty of Physics, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands)

    2006-05-15

    Streamers are a generic mode of electric breakdown of large gas volumes. They play a role in the initial stages of sparks and lightning, in technical corona reactors and in high altitude sprite discharges above thunderclouds. Streamers are characterized by a self-generated field enhancement at the head of the growing discharge channel. We briefly review recent streamer experiments and sprite observations. Then we sketch our recent work on computations of growing and branching streamers, we discuss concepts and solutions of analytical model reductions and we review different branching concepts and outline a hierarchy of model reductions.

  15. Poly(ionic liquids)-coated stainless-steel wires packed into a polyether ether ketone tube for in-tube solid-phase microextraction.

    Science.gov (United States)

    Feng, Juanjuan; Wang, Xiuqin; Tian, Yu; Luo, Chuannan; Sun, Min

    2017-12-01

    An in-tube solid-phase microextraction device was developed by packing poly(ionic liquids)-coated stainless-steel wires into a polyether ether ketone tube. An anion-exchange process was performed to enhance the extraction performance. Surface properties of poly(ionic liquids)-coated stainless-steel wires were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. The extraction device was connected to high-performance liquid chromatography equipment to build an online enrichment and analysis system. Ten polycyclic aromatic hydrocarbons were used as model analytes, and important conditions including extraction time and desorption time were optimized. The enrichment factors from 268 to 2497, linear range of 0.03-20 μg/L, detection limits of 0.010-0.020 μg/L, extraction and preparation repeatability with relative standard deviation less than 1.8 and 19%, respectively were given by the established online analysis method. It has been used to detect polycyclic aromatic hydrocarbons in environmental samples, with the relative recovery (5, 10 μg/L) in the range of 85.1-118.9%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. The Effect of Condensate Inundation on Steam Condensation Heat Transfer to Wire-Wrapped Tubing.

    Science.gov (United States)

    1983-06-01

    my Thesis Advisor, for his support and patient guidance throughout the project. My sincere appreciation to Dr. A.S. Wanniarachchi, my Second Reader...and perforated tube installation. The tubes were positioned using nylon tube sheets that were attached to the exterior of the condenser end plates. To...Co Tco #5 014 Tt 015 Tsat 016 Tcond 017 T 018 vap 53 IV. PROCEDURES A. INSTALLATION AND OPERATING PROCEDURES 1. 2-r-eparat inDfCndes ubu Prior to

  17. Development of Powder-in-Tube Processed Iron Pnictide Wires and Tapes

    KAUST Repository

    Ma, Yanwei

    2011-06-01

    The development of PIT fabrication process of iron pnictide superconducting wires and tapes has been reviewed. Silver was found to be the best sheath material, since no reaction layer was observed between the silver sheath and the superconducting core. The grain connectivity of iron pnictide wires and tapes has been markedly improved by employing Ag or Pb as dopants. At present, critical current densities in excess of 3750 A /cm 2 (I c = 37.5 A) at 4.2 K have been achieved in Ag-sheathed SrKFeAs wires prepared with the above techniques, which is the highest value obtained in iron-based wires and tapes so far. Moreover, Ag-sheathed Sm-1111 superconducting tapes were successfully prepared by PIT method at temperatures as low as ̃ 900 °C, instead of commonly used temperatures of ̃ 1200 °C. These results demonstrate the feasibility of producing superconducting pnictide composite wires, even grain boundary properties require much more attention. © 2010 IEEE.

  18. Experimental analysis for heat transfer of nanofluid with wire coil turbulators in a concentric tube heat exchanger

    Science.gov (United States)

    Akyürek, Eda Feyza; Geliş, Kadir; Şahin, Bayram; Manay, Eyüphan

    2018-06-01

    Nanofluids are a novel class of heat transfer suspensions of metallic or nonmetallic nanopowders with a size of less than 100 nm in base fluids and they can increase heat transfer potential of the base fluids in various applications. In the last decade, nanofluids have become an intensive research topic because of their improved thermal properties and possible heat transfer applications. For comparison, an experiment using water as the working fluid in the heat exchanger without wire coils was also performed. Turbulent forced convection heat transfer and pressure drop characteristics of Al2O3-water nanofluids in a concentric tube heat exchanger with and without wire coil turbulators were experimentally investigated in this research. Experiments effected particle volume concentrations of 0.4-0.8 to 1.2-1.6 vol% in the Reynolds number range from 4000 to 20,000. Two turbulators with the pitches of 25 mm and 39 mm were used. The average Nusselt number increased with increasing the Reynolds number and particle concentrations. Moreover, the pressure drop of the Al2O3-water nanofluid showed nearly equal to that of pure water at the same Reynolds number range. As a result, nanofluids with lower particle concentrations did not show an important influence on pressure drop change. Nonetheless, when the wire coils used in the heat exchanger, it increased pressure drop as well as the heat transfer coefficient.

  19. Streamers and their applications

    Science.gov (United States)

    Pemen, A. J. M.

    2011-10-01

    In this invited lecture we give an overview of our 15 years of experience on streamer plasma research. Efforts are directed to integrating the competence areas of plasma physics, pulsed power technology and chemical processing. The current status is the development of a large scale pulsed corona system for gas treatment. Applications on biogas conditioning, VOC removal, odor abatement and control of traffic emissions have been demonstrated. Detailed research on electrical and chemical processes resulted in a boost of efficiencies. Energy transfer efficiency to the plasma was raised to above 90%. Simultaneous improvement of the plasma chemistry resulted in a highly efficient radical generation: O-radical production up to 50% of the theoretical maximum has been achieved. A major challenge in pulsed power driven streamers is to unravel, understand and ultimately control the complex interactions between the transient plasma, electrical circuits, and process. Even more a challenge is to yield electron energies that fit activation energies of the process. We will discuss our ideas on adjusting pulsed power waveforms and plasma reactor settings to obtain more controlled catalytic processing: the ``Chemical Transistor'' concept.

  20. Distribution of Energy Deposited in Plastic Tubing and Copper-Wire Insulation by Electron Beam Irradiation

    DEFF Research Database (Denmark)

    Pedersen, Walther Batsberg; Miller, Arne; Pejtersen, K.

    1978-01-01

    chloride insulation. Radiochromic dye films equivalent to the insulating materials were used as accurate dosimeters having a response independent of dose rate. Irradiations were in various geometries, wire and plastic thicknesses, positions along the beam scan, and with different backing materials near...

  1. Bacterial streamers in curved microchannels

    Science.gov (United States)

    Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard

    2009-11-01

    Biofilms, generally identified as microbial communities embedded in a self-produced matrix of extracellular polymeric substances, are involved in a wide variety of health-related problems ranging from implant-associated infections to disease transmissions and dental plaque. The usual picture of these bacterial films is that they grow and develop on surfaces. However, suspended biofilm structures, or streamers, have been found in natural environments (e.g., rivers, acid mines, hydrothermal hot springs) and are always suggested to stem from a turbulent flow. We report the formation of bacterial streamers in curved microfluidic channels. By using confocal laser microscopy we are able to directly image and characterize the spatial and temporal evolution of these filamentous structures. Such streamers, which always connect the inner corners of opposite sides of the channel, are always located in the middle plane. Numerical simulations of the flow provide evidences for an underlying hydrodynamic mechanism behind the formation of the streamers.

  2. Prediction of the heat transfer rate of a single layer wire-on-tube type heat exchanger using ANFIS

    Energy Technology Data Exchange (ETDEWEB)

    Hayati, Mohsen [Electrical Engineering Department, Faculty of Engineering, Razi University, Tagh-E-Bostan, Kermanshah 67149 (Iran); Computational Intelligence Research Center, Razi University, Tagh-E-Bostan, Kermanshah 67149 (Iran); Rezaei, Abbas; Seifi, Majid [Electrical Engineering Department, Faculty of Engineering, Razi University, Tagh-E-Bostan, Kermanshah 67149 (Iran)

    2009-12-15

    In this paper, we applied an Adaptive Neuro-Fuzzy Inference System (ANFIS) model for prediction of the heat transfer rate of the wire-on-tube type heat exchanger. Limited experimental data was used for training and testing ANFIS configuration with the help of hybrid learning algorithm consisting of backpropagation and least-squares estimation. The predicted values are found to be in good agreement with the actual values from the experiments with mean relative error less than 2.55%. Also, we compared the proposed ANFIS model to an ANN approach. Results show that the ANFIS model has more accuracy in comparison to ANN approach. Therefore, we can use ANFIS model to predict the performances of thermal systems in engineering applications, such as modeling heat exchangers for heat transfer analysis. (author)

  3. Endoscopically placed guide wire assisted nasogastric tube insertion for palliation of absolute dysphagia in patients with incurable esophageal cancer

    Directory of Open Access Journals (Sweden)

    Purkayastha Joydeep

    2006-01-01

    Full Text Available Carcinoma of the esophagus is a dreadful disease because it causes a lot of distress to the patient due to its adverse effects on swallowing. Many patients present with large incurable disease or undergo disease progression and become incurable. Such patients are advised palliative and symptomatic care. The most distressing symptom that requires palliation in such patients is dysphagia. Many procedures are available for relief of dysphagia, but these are not readily available or are costly. We describe a simple, safe, cost effective and easy to do procedure for palliation of malignant dysphagia by insertion of Ryle′s tube over a endoscopically placed guide wire especially suitable for patients of the poor socio-economic strata.

  4. Effects of drawing and high-pressure sintering on the superconducting properties of (Ba,K)Fe2As2 powder-in-tube wires

    International Nuclear Information System (INIS)

    Pyon, Sunseng; Yamasaki, Yuji; Tamegai, Tsuyoshi; Kajitani, Hideki; Koizumi, Norikiyo; Tsuchiya, Yuji; Awaji, Satoshi; Watanabe, Kazuo

    2015-01-01

    The evolution of the superconducting properties of round wires of (Ba,K)Fe 2 As 2 fabricated by the powder-in-tube (PIT) method is systematically studied. After establishing the method to obtain the largest transport critical current density (J c ) in round wires using the hot isostatic press technique, we investigated how the transition temperature (T c ), J c , and microstructures change at each step of the wire fabrication. Unexpectedly, we find that superconducting properties of the wire core are significantly damaged by the drawing process. Systematic measurements of J c and T c of the core superconductor after each drawing and sintering process clarified the evolution of degradation by the drawing process and recovery by heat treatment. (paper)

  5. Dependence of streamer density on electric field strength on positive electrode

    Science.gov (United States)

    Koki, Nakamura; Takahumi, Okuyama; Wang, Douyan; Takao, N.; Hidenori, Akiyama; Kumamoto University Collaboration

    2015-09-01

    Pulsed streamer discharge plasma, a type of non-thermal plasma, is known as generation method of reactive radicals and ozone and treatment of exhausted gas. From our previous research, the distance between electrodes has been considered a very important parameter for applications using pulsed streamer discharge. However, how the distance between electrodes affects the pulsed discharge hasn't been clarified. In this research, the propagation process of pulsed streamer discharge in a wire-plate electrode was observed using an ICCD camera for 4 electrodes having different distance between electrodes. The distance between electrodes was changeable at 45 mm, 40 mm, 35 mm, and 30 mm. The results show that, when the distance between electrodes was shortened, applied voltage with a pulse duration of 100 ns decreased from 80 to 60.3 kV. Conversely, discharge current increased from 149 to 190 A. Streamer head velocity became faster. On the other hand, Streamer head density at onset time of streamer head propagation didn't change. This is considered due to the electric field strength of streamer head at that time, in result, it was about 14 kV/mm under each distance between electrodes.

  6. Land Streamer Surveying Using Multiple Sources

    KAUST Repository

    Mahmoud, Sherif

    2014-12-11

    Various examples are provided for land streamer seismic surveying using multiple sources. In one example, among others, a method includes disposing a land streamer in-line with first and second shot sources. The first shot source is at a first source location adjacent to a proximal end of the land streamer and the second shot source is at a second source location separated by a fixed length corresponding to a length of the land streamer. Shot gathers can be obtained when the shot sources are fired. In another example, a system includes a land streamer including a plurality of receivers, a first shot source located adjacent to the proximal end of the land streamer, and a second shot source located in-line with the land streamer and the first shot source. The second shot source is separated from the first shot source by a fixed overall length corresponding to the land streamer.

  7. Land Streamer Surveying Using Multiple Sources

    KAUST Repository

    Mahmoud, Sherif; Schuster, Gerard T.

    2014-01-01

    are fired. In another example, a system includes a land streamer including a plurality of receivers, a first shot source located adjacent to the proximal end of the land streamer, and a second shot source located in-line with the land streamer and the first

  8. Effect of inhomogeneities on streamer propagation: II. Streamer dynamics in high pressure humid air with bubbles

    International Nuclear Information System (INIS)

    Babaeva, Natalia Yu; Kushner, Mark J

    2009-01-01

    The branching of electric discharge streamers in atmospheric pressure air, dense gases and liquids is a common occurrence whose origins are likely found with many causes, both deterministic and stochastic. One mechanism for streamer branching may be inhomogeneities in the path of a streamer which either divert the streamer (typically a region of lower ionization) or produce a new branch (a region of higher ionization). The propagation and branching of streamers in liquids is likely aided by low density inhomogeneities, bubbles; however, modeling of streamers in liquids is made difficult by the lack of transport coefficients. As a first step towards understanding the propagation and branching of streamers in liquids, we investigated the consequences of random inhomogeneities in the form of low pressure bubbles on the propagation of streamers in high pressure humid air. By virtue of their lower density, bubbles have larger E/N (electric field/gas number density) than the ambient gas with larger rates of ionization. The intersection of a streamer with a bubble will focus the plasma into the bubble by virtue of that higher rate of ionization but the details of the interaction depend on the relative sizes of the bubble and streamer. When a streamer intersects a field of bubbles, the large E/N in the bubble avalanches seed electrons produced by photoionization from the streamer. Each bubble then launches both a negative and positive going streamer that may link with those from adjacent bubbles or the original streamer. The total process then appears as streamer branching.

  9. Generating Carbon Tubes and Films from Lead and Cadmium Wires During Underwater Spark Discharges

    International Nuclear Information System (INIS)

    Taka-aki Matsumoto

    2000-01-01

    In general, no nuclear reactions between charged particles would be possible in a low-energy region. However, many experimental data of nuclear transmutation with low energy were recently reported related to so-called cold fusion. This paper describes some kinds of low-energy nuclear reactions (LENRs), which could be induced during an underwater spark discharge (USD) with only(approx)120 V. The mechanisms of the extraordinary nuclear transmutation can be explained by the Nattoh model. The electron bonding of sparks, which was a special state of atomic clusters, was so strong that multibody nuclear reactions such as nuclear collapse[called electro-nuclear collapse (ENC)] could take place in the spark. Because of ENC, completely broken materials could be again regenerated as conventional elements. The film product was considered to be made by a spherical explosion of a small black hole and the tube by a rotational eruption of a small white hole, both of which resulted from ENC

  10. Testing an hydrogen streamer chamber

    CERN Multimedia

    1975-01-01

    A 2x10 cm gap streamer chamber, 35x55 cm2 in surface, was built and tested at CERN. Good tracks of cosmic rays were obtained up to atmospheric pressure, see F. Rohrbach et al, CERN-LAL (Orsay) Collaboration, Nucl. Instr. Methods 141 (1977) 229. Michel Cathenoz stand on the center.

  11. Pulsed Streamer Discharge Characteristics of Ozone Production in Dry Air

    OpenAIRE

    Samaranayake, W.J.M.; Miyahara, Y.; Namihira, T.; Katsuki, S.; Sakugawa, T.; Hackam, R.; Akiyama, H.; ナミヒラ, タカオ; カツキ, スナオ; アキヤマ, ヒデノリ; 波平, 隆男; 勝木, 淳; 秋山, 秀典

    2000-01-01

    Experimental investigation of HV short pulsed streamer discharges in dry air-fed ozonizers under various operating conditions are reported. Ozone concentration, energy input and ozone production yield (efficiency) were measured at various voltages (14 to 37 kV), pulse repetition rates (25 to 400 pulses per second, pps), flow rates (1.5 to 3.0 1/min) and different gap spacings (10 to 20 mm) at a pressure of 1.01×105 Pa in dry air. A spiral copper wire (1 mm in diameter) made to a cylindrical c...

  12. Evolution of streamer groups in nonthermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Okubo, M., E-mail: mokubo@me.osakafu-u.ac.jp [Department of Mechanical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531 (Japan)

    2015-12-15

    Nonthermal plasmas (NTPs) induced by atmospheric nanosecond pulsed corona discharge have been studied for controlling pollution from combustors, such as boilers, incinerators, and diesel engines. In high-speed short-width high-voltage pulsed corona discharge-induced plasmas, primary streamer evolution is followed by secondary streamer evolution. Though this phenomenon is known experimentally, the details of the structures of the streamers and their evolution mechanisms have not been fully clarified. In this letter, we perform quasi two-dimensional numerical analysis of nonequilibrium NTP induced by a nanosecond positive pulsed corona discharge. The continuum fluid equations for two-temperature nonequilibrium NTP are used as governing equations. In this study, 197 gas phase reactions for 25 chemical species and 21 surface reactions on the inner glass wall surface are considered in an air plasma under atmospheric pressure. The simulated behavior of the streamer groups agrees with experimental observations. Soon after the voltage increases on the reactor, primary streamers are formed, which may transit the complete gap, disappearing near the peak voltage. Next, second streamers appear, disappearing at the end of the applied voltage pulse. The streamer wavelength and the distance between the streamers in the axial direction are determined. Moreover, ozone generation is shown to be more significant in the secondary streamer. This simulation will allow better predictions for nanosecond positive pulsed plasma systems.

  13. Evolution of streamer groups in nonthermal plasma

    Science.gov (United States)

    Okubo, M.

    2015-12-01

    Nonthermal plasmas (NTPs) induced by atmospheric nanosecond pulsed corona discharge have been studied for controlling pollution from combustors, such as boilers, incinerators, and diesel engines. In high-speed short-width high-voltage pulsed corona discharge-induced plasmas, primary streamer evolution is followed by secondary streamer evolution. Though this phenomenon is known experimentally, the details of the structures of the streamers and their evolution mechanisms have not been fully clarified. In this letter, we perform quasi two-dimensional numerical analysis of nonequilibrium NTP induced by a nanosecond positive pulsed corona discharge. The continuum fluid equations for two-temperature nonequilibrium NTP are used as governing equations. In this study, 197 gas phase reactions for 25 chemical species and 21 surface reactions on the inner glass wall surface are considered in an air plasma under atmospheric pressure. The simulated behavior of the streamer groups agrees with experimental observations. Soon after the voltage increases on the reactor, primary streamers are formed, which may transit the complete gap, disappearing near the peak voltage. Next, second streamers appear, disappearing at the end of the applied voltage pulse. The streamer wavelength and the distance between the streamers in the axial direction are determined. Moreover, ozone generation is shown to be more significant in the secondary streamer. This simulation will allow better predictions for nanosecond positive pulsed plasma systems.

  14. Ga N nano wires and nano tubes growth by chemical vapor deposition method at different NH{sub 3} flow rate

    Energy Technology Data Exchange (ETDEWEB)

    Li, P.; Liu, Y.; Meng, X. [Wuhan University, School of Physics and Technology, Key Laboratory of Artificial Micro and Nanostructures of Ministry of Education, Wuhan 430072 (China)

    2016-11-01

    Ga N nano wires and nano tubes have been successfully synthesized via the simple chemical vapor deposition method. NH{sub 3} flow rate was found to be a crucial factor in the synthesis of different type of Ga N which affects the shape and the diameter of generated Ga N nano structures. X-ray diffraction confirms that Ga N nano wires grown on Si(111) substrate under 900 degrees Celsius and with NH{sub 3} flow rate of 50 sc cm presents the preferred orientation growth in the (002) direction. It is beneficial to the growth of nano structure through catalyst annealing. Transmission electron microscopy and scanning electron microscopy were used to measure the size and structures of the samples. (Author)

  15. Wire-in-tube structure fabricated by single capillary electrospinning via nanoscale Kirkendall effect: the case of nickel-zinc ferrite.

    Science.gov (United States)

    Fu, Jiecai; Zhang, Junli; Peng, Yong; Zhao, Changhui; He, Yongmin; Zhang, Zhenxing; Pan, Xiaojun; Mellors, Nigel J; Xie, Erqing

    2013-12-21

    Wire-in-tube structures have previously been prepared using an electrospinning method by means of tuning hydrolysis/alcoholysis of a precursor solution. Nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4) nanowire-in-nanotubes have been prepared as a demonstration. The detailed nanoscale characterization, formation process and magnetic properties of Ni0.5Zn0.5Fe2O4 nanowire-in-nanotubes has been studied comprehensively. The average diameters of the outer tubes and inner wires of Ni0.5Zn0.5Fe2O4 nanowire-in-nanotubes are around 120 nm and 42 nm, respectively. Each fully calcined individual nanowire-in-nanotube, either the outer-tube or the inner-wire, is composed of Ni0.5Zn0.5Fe2O4 monocrystallites stacked along the longitudinal direction with random orientation. The process of calcining electrospun polymer composite nanofibres can be viewed as a morphologically template nucleation and precursor diffusion process. This allows the nitrates precursor to diffuse toward the surface of the nanofibres while the oxides (decomposed from hydroxides and nitrates) products diffuse to the core region of the nanofibres; the amorphous nanofibres transforming thereby into crystalline nanowire-in-nanotubes. In addition, the magnetic properties of the Ni0.5Zn0.5Fe2O4 nanowire-in-nanotubes were also examined. It is believed that this nanowire-in-nanotube (sometimes called core-shell) structure, with its uniform size and well-controlled orientation of the long nanowire-in-nanotubes, is particularly attractive for use in the field of nano-fluidic devices and nano-energy harvesting devices.

  16. Experimental investigations on the physics of streamers

    NARCIS (Netherlands)

    Nijdam, S.

    2011-01-01

    Streamers are rapidly extending ionized fingers that can appear in gasses, liquids and solids. They are generated by high electric fields but can penetrate into areas where the background electric field is below the ionization threshold. Streamers occur in nature as a precursor to sparks and

  17. Fast imaging of streamer propagation

    International Nuclear Information System (INIS)

    Veldhuizen, E.M. van; Baede, A.H.F.M.; Hayashi, D.; Rutgers, W.R.

    2001-01-01

    Recently measurement methods are becoming available to study the corona discharge in more detail. One of the most promising methods is laser-induced fluorescence to determine radical density. Recent improvements in CCD cameras makes it now possible to improve measurements of the discharge structure to a resolution of 1 ns in time and 10 μm in space. This paper shows the first results of the spontaneous emission of a point-to-plane corona discharge in air using such a camera. It clearly indicates that the 2-D approach for streamer propagation under these conditions is insufficient

  18. Fast imaging of streamer propagation

    Energy Technology Data Exchange (ETDEWEB)

    Veldhuizen, E.M. van; Baede, A.H.F.M.; Hayashi, D.; Rutgers, W.R. [Eindhoven Univ. of Technology (Netherlands). Dept. of Applied Physics

    2001-07-01

    Recently measurement methods are becoming available to study the corona discharge in more detail. One of the most promising methods is laser-induced fluorescence to determine radical density. Recent improvements in CCD cameras makes it now possible to improve measurements of the discharge structure to a resolution of 1 ns in time and 10 {mu}m in space. This paper shows the first results of the spontaneous emission of a point-to-plane corona discharge in air using such a camera. It clearly indicates that the 2-D approach for streamer propagation under these conditions is insufficient.

  19. Rectangular drift tube characteristics

    International Nuclear Information System (INIS)

    Denisov, D.S.; Musienko, Yu.V.

    1985-01-01

    Results on the study of the characteristics of a 50 x 100 mm aluminium drift tube are presented. The tube was filled with argon-methane and argon-isobutane mixtures. With 16 per cent methane concentration the largest deviation from a linear relation between the drift time and the drift path over 50 mm is less than 2 mm. The tube filled with argon-isobutane mixture is capable of operating in a limited streamer mode

  20. Magnetic field influence on the selfquenching streamer discharge

    International Nuclear Information System (INIS)

    Alekseev, G.D.; Korytov, A.V.

    1987-01-01

    The influence of the magnetic field on the selfquenching streamer discharge characteristics is investigated. In the field about 10 kGs streamer charge is decreased several per cent (change of charge is due to amplitude decreasing of signal). In the transition region from limited-proportional to streamer mode magnetic field results in increasing of probability of avalanche developing into a streamer

  1. Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

    Directory of Open Access Journals (Sweden)

    Xin Wen Zhang

    2015-07-01

    Full Text Available Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.

  2. Diameter-speed relation of sprite streamers

    International Nuclear Information System (INIS)

    Kanmae, T; Stenbaek-Nielsen, H C; McHarg, M G; Haaland, R K

    2012-01-01

    Propagation and splitting of sprite streamers has been observed at high temporal and spatial resolution using two intensified high-speed CMOS cameras recording at 10 000 and 16 000 frames per second. Concurrent video recordings from a remote site provided data for triangulation allowing us to determine accurate altitude scales for the sprites. Diameters and speeds of the sprite streamers were measured from the high-speed images, and the diameters were scaled to the reduced diameters based on the triangulated locations. The sprite streamers with larger reduced diameter move faster than those with smaller diameter; the relation between the reduced diameter and speed is roughly linear. The reduced diameters at ≈65-70 km altitude are larger than streamer diameters measured at ground pressure in laboratory discharges indicating a deviation from the similarity law possibly due to the effects of the photoionization and an expansion of the streamer head along its propagation over a long distance. The reduced diameter and speed of the sprite streamers agree well with the diameter-velocity relation proposed by Naidis (2009 Phys. Rev. E 79 057401), and the peak electric field of the sprite streamers is estimated to be approximately 3-5 times the breakdown threshold field. (paper)

  3. Two-coordinate mini drift chamber operating in a self-quenching streamer mode

    International Nuclear Information System (INIS)

    Chernenko, S.P.; Smykov, L.P.; Zanevskij, Yu.V.

    1993-01-01

    Two-coordinate mini drift chambers operating in a self-quenching streamer mode have been developed. The tests have demonstrated these chambers to possess an extended counting plateau, a high operating stability and a high uniformity of efficiency over detecting area. The space resolution along anode wires is not worse than 250μm; the expected space resolution for the second coordinate is about 100 μm

  4. Effect of Sintering Time and Diameter on Bi-Pb-Sr-Ca-Cu-O Superconducting Wire Formation with TiO2 Dopant by Silver (Ag Tube

    Directory of Open Access Journals (Sweden)

    Cindy Al Kindi

    2018-01-01

    Full Text Available Pengaruh waktu sintering dan diameter terhadap pembentukan kawat superkonduktor Bi-Pb-Sr-Ca-Cu-O dengan dopan TiO2 menggunakan tabung perak (Ag menjadi penting untuk dibahas karena hal ini berpengaruh terhadap adanya suhu kritis yang merupakan syarat penting superkonduktor. Pada penelitian ini ada beberapa tahap yang dilakukan yaitu preparasi bahan, proses permesinan, penarikan kawat dan proses perlakuan panas. Serbuk BPSCCO dengan dopan TiO2 dimasukkan ke dalam tabung perak (Ag dan dikalsinasi pada temperatur 820oC selama 20 jam, lalu proses penarikan (Rolling sampai diameter 6 mm dan 2,6 mm serta sintering dilakukan pada temperatur 850oC selama 9 jam dan 30 jam untuk masing-masing ukuran diameter dengan dua kali proses sintering. Hasil penelitian menunjukkan bahwa kawat superkonduktor memiliki suhu kritis yaitu Tc onset = 99 K dan Tc zero = 70 K. Waktu yang sangat berpengaruh pada pembentukan fasa superkonduktor yaitu sintering selama 9 jam sedangkan untuk ukuran diameter kawat yang memiliki suhu kritis yaitu 6 mm, sedangkan waktu sintering selama 30 jam dapat merubah fasa BPSCCO sehingga tidak terbentuk superkonduktor melainkan konduktor dan semikonduktor. Pada diameter 2,6 mm belum menjadi ukuran yang tepat pada pembentukan kawat superkonduktor.   The influence of sintering time and diameter on the formation of Bi-Pb-Sr-Ca-Cu-O superconducting wire with doped TiO2 by silver (Ag tube becomes important to be discussed because of the presence of critical temperature which is an essential condition in superconductors. In this research there are several steps must be done that is: material preparation, machine process, wire drawing and heat process. BPSCCO powder with dopant TiO2 filled into silver (Ag tube with calcination temperature at 820oC for 20 h, then rolling process to diameter 6 mm and 2,6 mm with sintering temperature at 850oC for 9 h and 30 h for each size of diameter by twice sintering process. The results showed that

  5. Streamers in water and other dielectric liquids

    International Nuclear Information System (INIS)

    Kolb, J F; Joshi, R P; Xiao, S; Schoenbach, K H

    2008-01-01

    Experimental results on the inception and propagation of streamers in water generated under the application of high electric fields are reviewed. Characteristic parameters, such as breakdown voltage, polarity of the applied voltage, propagation velocities and other phenomenological features, are compared with similar phenomena in other dielectric liquids and in gases. Consequently, parameters that are expected to influence the development of streamers in water are discussed with respect to the analogous well-established models and theories for the related mechanisms in gases. Most of the data support the notion that an initial low-density nucleation site or gas-filled bubble assists the initiation of a streamer. Details of this theory are laid out explaining the observed differences in the breakdown originating from the anode versus the cathode locations. The mechanisms can also be applied to streamer propagation, although some observations cannot be satisfactorily explained.

  6. Track photographing in 8-m streamer chamber

    International Nuclear Information System (INIS)

    Anisimova, N.Z.; Davidenko, V.A.; Kantserov, V.A.; Rybakov, V.G.; Somov, S.V.

    1981-01-01

    A system for obtaining data from a streamer chamber intended for measuring muon polarization is described. An optical scheme for photographing of tracks in the chamber is given. The photographing process is complicated at the expense of large dimensions and module structure of the chamber as well as due to insufficient for direct photographing brightness of streamers. The system described was tested during a long time in a physical experiment. More than 100 thousand photos have been taken by its means [ru

  7. Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes.

    Science.gov (United States)

    Enteshari Najafabadi, Marzieh; Bagheri, Habib

    2017-12-26

    This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS-ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC-MS. The limits of detection under optimized conditions range from 0.5 to 10 ng.L -1 . The intra- and inter-day relative standard deviations (RSDs) (for n = 10, 5 respectively) using a single fiber are 6-10 and 10-15%, respectively. The fiber-to-fiber RSDs (for n = 3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%. Graphical abstract A gradient coating of organoclay-Cu nanoclusters was fabricated on a copper wire by wireless electrofunctionalization. The oxidation of copper takes place at the anodic pole (red) while dissolved oxygen in ethanol solution is reduced at the cathodic pole (blue).

  8. Streamer knotwilg branching: sudden transition in morphology of positive streamers in high-purity nitrogen

    International Nuclear Information System (INIS)

    Heijmans, L C J; Clevis, T T J; Nijdam, S; Van Veldhuizen, E M; Ebert, U

    2015-01-01

    We describe a peculiar branching phenomenon in positive repetitive streamer discharges in high purity nitrogen. We name it knotwilg branching after the Dutch word for a pollard willow tree. In a knotwilg branching a thick streamer suddenly splits into many thin streamers. Under some conditions this happens for all streamers in a discharge at about the same distance from the high-voltage electrode tip. At this distance, the thick streamers suddenly bend sharply and appear to propagate over a virtual surface surrounding the high-voltage electrode, rather than following the background electric field lines. From these bent thick streamers many, much thinner, streamers emerge that roughly follow the background electric field lines, creating the characteristic knotwilg branching. We have only found this particular morphology in high purity nitrogen at pressures in the range 50 to 200 mbar and for pulse repetition rates above 1 Hz; the experiments were performed for an electrode distance of 16 cm and for fast voltage pulses of 20 or 30 kV. These observations clearly disagree with common knowledge on streamer propagation. We have analyzed the data of several tens of thousands of discharges to clarify the phenomena. We also present some thoughts on how the ionization of the previous discharges could concentrate into some pre-ionization region near the needle electrode and create the knotwilg morphology, but we present no final explanation. (paper)

  9. Feasibility of Shape-Memory Ni/Ti Alloy Wire Containing Tube Elevators for Transcrestal Detaching Maxillary Sinus Mucosa: Ex Vivo Study

    Directory of Open Access Journals (Sweden)

    Yanfeng Li

    2016-12-01

    Full Text Available Background: Osteotome sinus floor elevation is a less invasive approach to augment an insufficient alveolar bone at the posterior maxilla for dental implantation. However, this approach has some limitations due to the lack of sinus lift tools available for clinical use and the small transcrestal access to the maxillary sinus floor. We recently invented shape-memory Ni/Ti alloy wire containing tube elevators for transcrestal detaching maxillary sinus mucosa, and developed goat ex vivo models for direct visualizing the effectiveness of detaching sinus mucosa in real time during transcrestal maxillary sinus floor elevation. Methods: We evaluated our invented elevators, namely elevator 012 and elevator 014, for their effectiveness for transcrestal detaching maxillary sinus mucosa using the goat ex vivo models. We measured the length of sinus mucosa detached in mesial and distal directions or buccal and palatal directions, and the space volume created by detaching maxillary sinus mucosa in mesial, distal, buccal and palatal directions using the invented elevators. Results: Elevator 012 had a shape-memory Ni/Ti alloy wire with a diameter of 0.012 inch, while elevator 014 had its shape-memory Ni/Ti alloy wire with a diameter of 0.014 inch. Elevator 012 could detach the goat maxillary sinus mucosa in the mesial or distal direction for 12.1±4.3 mm, while in the buccal or palatal direction for 12.5±6.7 mm. The elevator 014 could detach the goat maxillary sinus mucosa for 23.0±4.9 mm in the mesial or distal direction, and for 19.0±8.1 mm in the buccal or palatal direction. An average space volume of 1.7936±0.2079 ml was created after detaching the goat maxillay sinus mucosa in both mesial/distal direction and buccal/palatal direction using elevator 012; while the average space volume created using elevator 014 was 1.8764±0.2366 ml. Conclusion: Both two newly invented tube elevators could effectively detach the maxillary sinus mucosa on the goat ex

  10. Feasibility of Shape-Memory Ni/Ti Alloy Wire Containing Tube Elevators for Transcrestal Detaching Maxillary Sinus Mucosa: Ex Vivo Study.

    Science.gov (United States)

    Li, Yanfeng; Wang, Fuli; Hu, Pin; Fan, Jiadong; Han, Yishi; Liu, Bin; Liu, Tao; Yang, Chunhao; Gu, Xiangmin

    2016-01-01

    Osteotome sinus floor elevation is a less invasive approach to augment an insufficient alveolar bone at the posterior maxilla for dental implantation. However, this approach has some limitations due to the lack of sinus lift tools available for clinical use and the small transcrestal access to the maxillary sinus floor. We recently invented shape-memory Ni/Ti alloy wire containing tube elevators for transcrestal detaching maxillary sinus mucosa, and developed goat ex vivo models for direct visualizing the effectiveness of detaching sinus mucosa in real time during transcrestal maxillary sinus floor elevation. We evaluated our invented elevators, namely elevator 012 and elevator 014, for their effectiveness for transcrestal detaching maxillary sinus mucosa using the goat ex vivo models. We measured the length of sinus mucosa detached in mesial and distal directions or buccal and palatal directions, and the space volume created by detaching maxillary sinus mucosa in mesial, distal, buccal and palatal directions using the invented elevators. Elevator 012 had a shape-memory Ni/Ti alloy wire with a diameter of 0.012 inch, while elevator 014 had its shape-memory Ni/Ti alloy wire with a diameter of 0.014 inch. Elevator 012 could detach the goat maxillary sinus mucosa in the mesial or distal direction for 12.1±4.3 mm, while in the buccal or palatal direction for 12.5±6.7 mm. The elevator 014 could detach the goat maxillary sinus mucosa for 23.0±4.9 mm in the mesial or distal direction, and for 19.0±8.1 mm in the buccal or palatal direction. An average space volume of 1.7936±0.2079 ml was created after detaching the goat maxillay sinus mucosa in both mesial/distal direction and buccal/palatal direction using elevator 012; while the average space volume created using elevator 014 was 1.8764±0.2366 ml. Both two newly invented tube elevators could effectively detach the maxillary sinus mucosa on the goat ex vivo sinus models. Moreover, elevator 014 has advantages over

  11. Radio Frequency Electromagnetic Radiation From Streamer Collisions.

    Science.gov (United States)

    Luque, Alejandro

    2017-10-16

    We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz. We also investigate the fast penetration, after a collision, of electromagnetic fields into the streamer heads and show that these fields are capable of accelerating electrons up to about 100 keV. By substantiating the link between X-rays and high-frequency radio emissions and by describing a mechanism for the early acceleration of runaway electrons, our results support the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges.

  12. Study of Streamers in Gradient Density Air: Table Top Modeling of Red Sprites

    Science.gov (United States)

    Opaits, D. F.; Shneider, M. N.; Howard, P. J.; Miles, R. B.; Milikh, G. M.

    2009-12-01

    Sprites and blue jets develop in the upper atmosphere where ambient density changes drastically over their lengths. Theoretical analysis of Red Sprites [1] and Blue Jets [2,3] are based on the streamer tip parameters’ functional dependence on a local gas density N(h). At the moment there is a lack of experimental data for streamer propagation in a non-uniform ambient gas density. Small scale experiments in controllable conditions are important for validation of analytical models as well as numerical simulations, which can be used for the investigation of real scale plasma phenomena that develop above thunderclouds. Controllable, non-uniform gas density can be achieved in laboratory conditions in super sonic nozzles, fast centrifuges or gas filled tubes with a non-uniform temperature distribution along the axis. The latter approach was used in the present work. A quartz tube, approximately one foot in length, was filled with air at different pressures. A density gradient was created by heating up the top of the tube while keeping the bottom at room temperature. The discharge was initiated by applying a high voltage pulse to a pin electrode at the top of the tube while a flat electrode was grounded at the bottom. Similar to Red Sprites, the streamer propagates downwards into a region of higher density and stops before reaching the lower electrode while the top electrode remains under high potential. This work will present results of streamer propagation at different pressures and voltages. Measurements of current-voltage characteristics as well as integral images will be presented. 1. Y. P.Raizer, G. M. Milikh, M. N. Shneider, and S. V. Novakovski (1998), J. Phys. D: Appl. Phys. 31, 3255-3264. 2. Y. P.Raizer, G. M. Milikh, and M. N. Shneider (2006), Geophys. Res. Lett., 33, L23801 3. Y .P.Raizer, G. M. Milikh, and M. N. Shneider (2007), J. Atmos. & Solat-Terr. Phys, 69, 925-938

  13. ADS and CDS streamer generation as function of pulsed parameters

    NARCIS (Netherlands)

    Winands, G.J.J.; Liu, Z.; Heesch, van E.J.M.; Pemen, A.J.M.; Yan, K.

    2008-01-01

    Streamer plasmas can be used to remove pollutants from gases. As a result of the complex mechanisms involved during streamer initiation and propagation, the related knowledge is incomplete. During the last few years, extensive research was performed to determine typical streamer properties (such as

  14. Saffman-Taylor streamers: Mutual finger interaction in spark formation

    NARCIS (Netherlands)

    Luque, A.; Brau, F.; Ebert, U.

    2008-01-01

    Bunches of streamers form the early stages of sparks and lightning but theory presently concentrates on single streamers or on coarse approximations of whole breakdown trees. Here a periodic array of interacting streamer discharges in a strong homogeneous electric field is studied in density or

  15. Fluid and hybrid models for streamers

    Science.gov (United States)

    Bonaventura, Zdeněk

    2016-09-01

    Streamers are contracted ionizing waves with self-generated field enhancement that propagate into a low-ionized medium exposed to high electric field leaving filamentary trails of plasma behind. The widely used model to study streamer dynamics is based on drift-diffusion equations for electrons and ions, assuming local field approximation, coupled with Poisson's equation. For problems where presence of energetic electrons become important a fluid approach needs to be extended by a particle model, accompanied also with Monte Carlo Collision technique, that takes care of motion of these electrons. A combined fluid-particle approach is used to study an influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure. It is found that fluid-only model predicts substantially faster reignition dynamics compared to coupled fluid-particle model. Furthermore, a hybrid model can be created in which the population of electrons is divided in the energy space into two distinct groups: (1) low energy `bulk' electrons that are treated with fluid model, and (2) high energy `beam' electrons, followed as particles. The hybrid model is then capable not only to deal with streamer discharges in laboratory conditions, but also allows us to study electron acceleration in streamer zone of lighting leaders. There, the production of fast electrons from streamers is investigated, since these (runaway) electrons act as seeds for the relativistic runaway electron avalanche (RREA) mechanism, important for high-energy atmospheric physics phenomena. Results suggest that high energy electrons effect the streamer propagation, namely the velocity, the peak electric field, and thus also the production rate of runaway electrons. This work has been supported by the Czech Science Foundation research project 15-04023S.

  16. Vibration of signal wires in wire detectors under irradiation

    International Nuclear Information System (INIS)

    Bojko, I.R.; Shelkov, G.A.; Dodonov, V.I.; Ignatenko, M.A.; Nikolenko, M.Yu.

    1995-01-01

    Radiation-induced vibration of signal wires in wire detectors is found and explained. The phenomenon is based on repulsion of a signal wire with a positive potential and a cloud of positive ions that remains after neutralization of the electron part of the avalanche formed in the course of gas amplification. Vibration with a noticeable amplitude may arise from fluctuations of repulsive forces, which act on the wire and whose sources are numerous ion clusters. A formula is obtained which allows wire oscillations to be estimated for all types of wire detectors. Calculation shows that oscillations of signal wires can be substantial for the coordinate accuracy of a detector working in the limited streamer mode at fluxes over 10 5 particles per second per wire. In the proportional mode an average oscillation amplitude can be as large as 20-30 μm at some detector parameters and external radiation fluxes over 10 5 . The experimental investigations show that the proposed model well describes the main features of the phenomenon. 6 refs., 8 figs

  17. Stereo-photography of streamers in air

    International Nuclear Information System (INIS)

    Nijdam, S.; Moerman, J. S.; Briels, T. M. P.; Veldhuizen, E. M. van; Ebert, U.

    2008-01-01

    Standard photographs of streamer discharges show a two-dimensional projection. Here, we present stereophotographic images that resolve their three-dimensional structure. We describe the stereoscopic setup and evaluation, and we present results for positive streamer discharges in air at 0.2-1 bar in a point-plane geometry with a gap distance of 14 cm and a voltage pulse of 47 kV. In this case, an approximately Gaussian distribution of branching angles of 43 deg. ±12 deg. is found; these angles do not significantly depend on the distance from the needle or on the gas pressure

  18. Stochastic and deterministic causes of streamer branching in liquid dielectrics

    International Nuclear Information System (INIS)

    Jadidian, Jouya; Zahn, Markus; Lavesson, Nils; Widlund, Ola; Borg, Karl

    2013-01-01

    Streamer branching in liquid dielectrics is driven by stochastic and deterministic factors. The presence of stochastic causes of streamer branching such as inhomogeneities inherited from noisy initial states, impurities, or charge carrier density fluctuations is inevitable in any dielectric. A fully three-dimensional streamer model presented in this paper indicates that deterministic origins of branching are intrinsic attributes of streamers, which in some cases make the branching inevitable depending on shape and velocity of the volume charge at the streamer frontier. Specifically, any given inhomogeneous perturbation can result in streamer branching if the volume charge layer at the original streamer head is relatively thin and slow enough. Furthermore, discrete nature of electrons at the leading edge of an ionization front always guarantees the existence of a non-zero inhomogeneous perturbation ahead of the streamer head propagating even in perfectly homogeneous dielectric. Based on the modeling results for streamers propagating in a liquid dielectric, a gauge on the streamer head geometry is introduced that determines whether the branching occurs under particular inhomogeneous circumstances. Estimated number, diameter, and velocity of the born branches agree qualitatively with experimental images of the streamer branching

  19. Electron acceleration during streamer collisions in air

    DEFF Research Database (Denmark)

    Köhn, Christoph; Chanrion, Olivier; Neubert, Torsten

    2017-01-01

    charge fields, with a Monte Carlo scheme accounting for collisions and ionization. We present the electron density, the electric field, and the velocity distribution as functions of space and time. Assuming a background electric field 1.5 times the breakdown field, we find that the electron density......High-voltage laboratory experiments show that discharges in air, generated over a gap of one meter with maximal voltage of 1 MV, may produce X-rays with photon energies up to 1 MeV. It has been suggested that the photons are bremsstrahlung from electrons accelerated by the impulsive, enhanced field...... during collisions of negative and a positive streamers. To explore this process, we have conducted the first self-consistent particle simulations of streamer encounters. Our simulation model is a 2-D, cylindrically symmetric, particle-in-cell code tracing the electron dynamics and solving the space...

  20. Streamer model for high voltage water switches

    International Nuclear Information System (INIS)

    Sazama, F.J.; Kenyon, V.L. III

    1979-01-01

    An electrical switch model for high voltage water switches has been developed which predicts streamer-switching effects that correlate well with water-switch data from Casino over the past four years and with switch data from recent Aurora/AMP experiments. Preclosure rounding and postclosure resistive damping of pulseforming line voltage waveforms are explained in terms of spatially-extensive, capacitive-coupling of the conducting streamers as they propagate across the gap and in terms of time-dependent streamer resistance and inductance. The arc resistance of the Casino water switch and of a gas switch under test on Casino was determined by computer fit to be 0.5 +- 0.1 ohms and 0.3 +- 0.06 ohms respectively, during the time of peak current in the power pulse. Energy lost in the water switch during the first pulse is 18% of that stored in the pulseforming line while similar energy lost in the gas switch is 11%. The model is described, computer transient analyses are compared with observed water and gas switch data and the results - switch resistance, inductance and energy loss during the primary power pulse - are presented

  1. Streamer properties and associated x-rays in perturbed air

    Science.gov (United States)

    Köhn, C.; Chanrion, O.; Babich, L. P.; Neubert, T.

    2018-01-01

    Streamers are ionization waves in electric discharges. One of the key ingredients of streamer propagation is an ambient gas that serves as a source of free electrons. Here, we explore the dependence of streamer dynamics on different spatial distributions of ambient air molecules. We vary the spatial profile of air parallel and perpendicular to the ambient electric field. We consider local sinusoidal perturbations of 5%-100%, as induced from discharge shock waves. We use a cylindrically symmetric particle-in-cell code to simulate the evolution of bidirectional streamers and compare the electron density, electric field, streamer velocity and electron energy of streamers in uniform air and in perturbed air. In all considered cases, the motion is driven along in decreasing air density and damped along increasing air density. Perturbations of at most 5%-10% change the velocity differences by up to approximately 40%. Perturbations perpendicular to the electric field additionally squeeze or branch streamers. Air variations can thus partly explain the difference of velocities and morphologies of streamer discharges. In cases with large perturbations, electrons gain energies of up to 30 keV compared to 100 eV in uniformly distributed air. For such perturbations parallel to the ambient electric field, we see the spontaneous initiation of a negative streamer; for perpendicular perturbations, x-rays with energies of up to 20 keV are emitted within 0.17 ns.

  2. Extremely far from equilibrium: the multiscale dynamics of streamers

    Science.gov (United States)

    Ebert, Ute

    2012-10-01

    Streamers can emerge when high voltages are applied to gases. At their tips, the electric field is strongly enhanced, and electron energies locally reach distributions very far from equilibrium, with long tails at high energies. These exotic electron energies create radiation and chemical excitations at very low energy input, as the gas stays cold while the ionization front passes. Applications are multiple: highly efficient O* radical production in air for disinfection, combustion gas cleaning, plasma assisted combustion, plasma bullets in medicine etc. In that sense, streamers can be considered as very efficient converters of pulsed electric into chemical energy, in particular, if the electric circuits are optimized for the application. Streamers are also ubiquitous in nature, e.g., in the streamer corona of lightning leaders, in sprite discharges high above the clouds; and streamers also seem to contribute to generating gamma-ray flashes and even to electron-positron beams in active thunderstorms. Unravelling the intrinsic mechanisms of streamers is challenging: they can move with up to one tenth of the speed of light, and they have an intricate nonlinear structure with a hierarchy of scales. I will review how theory and experiment deal with these structures, and I will discuss the basic differences between positive and negative streamers, electron acceleration at streamer tips and the consecutive radiation and chemical reactions, the propagation mechanism of positive streamers in different gases, streamer velocities and diameters varying over at least two orders of magnitude, streamer branching and interaction, and their three-dimensional tree structure. Both theory and experiment work with a patchwork of methods, and geophysics can provide movies that cannot be taken in the lab. I will sketch the state and outline open questions.

  3. Optical Emissions of Sprite Streamers in Weak Electric Fields

    Science.gov (United States)

    Liu, N.; Pasko, V. P.

    2004-12-01

    Sprites commonly consist of large numbers of needle-shaped filaments of ionization [e.g., Gerken and Inan, JASTP, 65, 567, 2003] and typically initiate at altitudes 70-75 km in a form of upward and downward propagating streamers [Stanley et al., GRL, 26, 3201, 1999; Stenbaek-Nielsen et al., GRL, 27, 3829, 2000; McHarg et al., JGR, 107, 1364, 2002; Moudry et al., JASTP, 65, 509, 2003]. The strong electric fields E exceeding the conventional breakdown threshold field Ek are needed for initiation of sprite streamers from single electron avalanches and recent modeling studies indicate that streamers propagating in fields E>Ek experience strong acceleration and expansion in good agreement with the above cited observations [Liu and Pasko, JGR, 109, A04301, 2004]. The initiated streamers are capable of propagating in fields substantially lower than Ek [Allen and Ghaffar, J. Phys. D: Appl. Phys., 28, 331, 1995] and it is expected that a significant part of sprite optical output comes from regions with EEk). Additionally, the values of electric fields inside of the streamer channel are always well below Ek and since the excitation coefficients for optical emissions are very sensitive to the driving electric field magnitude most of the optical luminosity of streamers in this case arises from streamer tips, indicating that observed streamer filaments in many cases may be produced by time averaging of optical luminosity coming from localized regions around streamer tips as streamers move through an instrument's field of view. We will discuss pressure dependent differences of optical emissions at different sprite altitudes, and important similarities between observed sprite streamers and recent time resolved (van Veldhuizen et al., IEEE Trans. Plasma Sci., 30, 162, 2002; Yi and Williams, J. Phys. D. Appl. Phys., 35, 205, 2002].

  4. Parallel sparse direct solvers for Poisson's equation in streamer discharges

    NARCIS (Netherlands)

    M. Nool (Margreet); M. Genseberger (Menno); U. M. Ebert (Ute)

    2017-01-01

    textabstractThe aim of this paper is to examine whether a hybrid approach of parallel computing, a combination of the message passing model (MPI) with the threads model (OpenMP) can deliver good performance in streamer discharge simulations. Since one of the bottlenecks of almost all streamer

  5. Photoionization in negative streamers : fast computations and two propagation modes

    NARCIS (Netherlands)

    Luque, A.; Ebert, U.M.; Montijn, C.; Hundsdorfer, W.

    2007-01-01

    Streamer discharges play a central role in electric breakdown of matter in pulsed electric fields, both in nature and in technology. Reliable and fast computations of the minimal model for negative streamers in simple gases such as nitrogen have recently been developed. However, photoionization was

  6. Streamer head structure: role of ionization and photoionization

    International Nuclear Information System (INIS)

    Nudnova, M M; Starikovskii, A Yu

    2008-01-01

    Results from experiments and numerical modelling of streamer propagation are presented. The 2D hydrodynamic numerical description of the pulsed discharge based on the local ionization and photoionization models adequately describes the streamer shape and dynamics over a wide range of pressures and voltages. This work presents a method for imaging the instantaneous emission distribution in the streamer head. A method for restoring the electrodynamic radius of the streamer head was developed on the basis of the streamer head images that were obtained with subnanosecond exposure time. The electrodynamic radius has been determined as the distance between the maxima of the electric field at the position where the streamer head transforms into the streamer channel. The dependence of the electrodynamic radius on voltage and pressure has been determined. We show that a 2D numerical model using hydrodynamic approximation predicts the streamer characteristics with an accuracy of about 15% in the 0.5-1 atmosphere pressure range and up to 40% in the 0.2-0.3 atmosphere pressure range for a voltage of U from 20 kV up to 40 kV in the 30 and 40 mm discharge gap.

  7. Influences of the pulsed power supply on corona streamer appearance

    NARCIS (Netherlands)

    Veldhuizen, van E.M.; Briels, T.M.P.; Grabowski, L.R.; Pemen, A.J.M.; Ebert, U.M.

    2005-01-01

    Pulsed positive corona streamers in air are studied by images obtained with an intensified CCD camera. Using a switched capacitor power supply, thin streamers are observed that branch. A power supply consisting of a 4-stage transmission line transformer gives pulses of much higher current to the

  8. Streamer discharges can move perpendicularly to the electric field

    NARCIS (Netherlands)

    Nijdam, S.; Takahashi, E.; Teunissen, J.; Ebert, U.

    2014-01-01

    Streamer discharges are a primary mode of electric breakdown in thunderstorms and high voltage technology; they are generally believed to grow along electric field lines. However, we here give experimental and numerical evidence that streamers can propagate nearly perpendicularly to the background

  9. Structure of positive streamers inside gaseous bubbles immersed in liquids

    International Nuclear Information System (INIS)

    Babaeva, Natalia Yu; Kushner, Mark J

    2009-01-01

    Electric discharges and streamers in liquids typically proceed through vapour phase channels produced by the streamer or in gaseous bubbles. The bubbles can originate by enthalpy changes produced by the discharge or can be artificially injected into the liquid. Experiments on streamers in bubbles immersed in liquids have shown that the discharge propagates either along the surface of the bubble or through the volume of the bubble as in conventional streamer propagation in air. In this paper we report on results of a computational investigation of streamer propagation through bubbles immersed in liquids. We found that the dielectric constant of the liquid in large part determines the path the streamer takes. Streamers in bubbles immersed in a liquid with a high permittivity preferentially propagate along the surface of the bubble. Liquids with low permittivity can result in the streamer propagating along the axis of the bubble. The permittivity at which this transition occurs is a function of the applied voltage, size of the bubble and the conductivity of the liquid. (fast track communication)

  10. Quenching gases for limited-streamer operation

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, P

    1986-04-01

    Charge spectra and efficiencies of the limited-streamer mode are presented as a function of quencher fraction and high voltage for several gas mixes. The goal was to find a working gas of low hydrocarbon content in order to relieve safety concerns about the flammability of the large gas volume contained in the hadron calorimeter of the OPAL detector at LEP. No suitable low-hydrocarbon quenching mix is found. The charge spectra from these quenchers develop secondary peaks and long tails as full efficiency is approached, leading to catastrophic breakdown near the onset of full efficiency.

  11. Quenching gases for limited-streamer operation

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, P

    1986-04-01

    Charge spectra and efficiencies of the limited-streamer mode are presented as a function of quencher fraction and high voltage for several gas mixes. The goal was to find a working gas of low hydrocarbon content in order to relieve safety concerns about the flammability of the large gas volume contained in the hadron calorimeter of the OPAL detector at LEP. No suitable low-hydrocarbon quenching mix is found. The charge spectra from these quenchers develop secondary peaks and long tails as full efficiency is approached, leading to catastrophic breakdown near the onset of full efficiency. (orig.).

  12. Kinetics of a plasma streamer ionization front

    Science.gov (United States)

    Taccogna, Francesco; Pellegrini, Fabrizio

    2018-02-01

    A streamer is a non-linear and non-local gas breakdown mode. Its large-scale coherent structures, such as the ionization front, are the final results of a hierarchical cascade starting from the single particle dynamics. Therefore, this phenomenon covers, by definition, different space and time scales. In this study, we have reproduced the ionization front formation and development by means of a particle-based numerical methodology. The physical system investigated concerns of a high-voltage ns-pulsed surface dielectric barrier discharge. Different reduced electric field regimes ranging from 50 to 500 Td have been considered for two gases: pure atomic Ar and molecular N2. Results have shown the detailed structure of the negative streamer: the leading edge, the head, the interior and the tail. Its dynamical evolution and the front propagation velocity have been calculated for the different cases. Finally, the deviation of the electron energy distribution function from equilibrium behavior has been pointed out as a result of a fast and very localized phenomenon.

  13. Use of gas mixture electroluminescence for optical data readout from wire chambers

    International Nuclear Information System (INIS)

    Polyakov, V.A.; Rykalin, V.I.; Tskhadadze, Eh.G.

    1988-01-01

    The radiation spectra, the values of electroluminescence yield and coefficients of gas amplification of Ar and Ne mixture with inorganic and organic additions in a wire chamber operating under proportional and self-quenching streamer conditions are measured. Maximum light yield: 2x10 7 photons for Ar+acetone+white spirit gas mixture in a proportional regime and 1.1x10 7 photons for Ar+CO 2 + ethyl alcohol+ white spirit in self-quenching streamer regime is obtained. Three methods of optical data readout from the wire chambers are tested. The best results are obtained when spectrum shifting bands and fibers are placed behind the chamber cathode planes

  14. Runaway electrons from a ‘beam-bulk’ model of streamer: application to TGFs

    DEFF Research Database (Denmark)

    Chanrion, Olivier Arnaud; Bonaventura, Z.; Cinar, Deniz

    2014-01-01

    -energy electrons and ions. For a negative streamer discharge, we show how electrons are accelerated in the large electric field in the tip of the streamer and travel ahead of the streamer where they ionize the gas. In comparison to the results obtained with a classical fluid model for a negative streamer, the beam...

  15. Measuring of tube expansion

    International Nuclear Information System (INIS)

    Vogeleer, J. P.

    1985-01-01

    The expansion of the primary tubes or sleeves of the steam generator of a nuclear reactor plant are measured while the tubes or sleeves are being expanded. A primary tube or sleeve is expanded by high pressure of water which flows through a channel in an expander body. The water is supplied through an elongated conductor and is introduced through a connector on the shank connected to the conductor at its outer end. A wire extends through the mandrel and through the conductor to the end of the connector. At its inner end the wire is connected to a tapered pin which is subject to counteracting forces produced by the pressure of the water. The force on the side where the wire is connected to the conductor is smaller than on the opposite side. The tapered pin is moved in the direction of the higher force and extrudes the wire outwardly of the conductor. The tapered surface of the tapered pin engages transverse captive plungers which are maintained in engagement with the expanding tube or sleeve as they are moved outwardly by the tapered pin. The wire and the connector extend out of the generator and, at its outer end, the wire is connected to an indicator which measures the extent to which the wire is moved by the tapered pin, thus measuring the expansion of the tube or sleeve as it progresses

  16. Modeling of a new electron-streamer acceleration mechanism

    Science.gov (United States)

    Ihaddadene, K. M. A.; Dwyer, J. R.; Liu, N.; Celestin, S. J.

    2017-12-01

    Lightning stepped leaders and laboratory spark discharges in air are known to produce X-rays [e.g., Dwyer et al., Geophys. Res. lett., 32, L20809, 2005; Kochkin et al., J. Phys. D: Appl. Phys., 45, 425202, 2012]. However, the processes behind the production of these X-rays are still not very well understood. During discharges, encounters between streamers of different polarities are very common. For example, during the formation of a new leader step, the negative streamer zone around the tip of a negative leader and the positive streamers initiated from the posiive part of a bidirectional space leader strongly interact. In laboratory experiments, when streamers are approaching a sharp electrode, streamers with the opposite polarity are initiated from the electrode and collide with the former streamers. Recently, the encounter between negative and positive streamers has been proposed as a plausible mechanism for the production of X-rays by spark discharges [Cooray et la., JASTP, 71, 1890, 2009; Kochkin et al., J. Phys. D: Appl. Phys., 45, 425202, 2012], but modeling results have shown later that the increase of the electric field involved in this process, which is above the conventional breakdown threshold field, is accompanied by a strong increase of the electron density. The resulting increase in the conductivity, in turn, causes this electric field to collapse over a few tens of picoseconds, preventing the electrons reaching high energies and producing significant X-ray emissions [e.g., Ihaddadene and Celestin, Geophys. Res. Lett., 45, 5644, 2015]. In this work, we will present simulation results of a new electron acceleration mechanism for producing runaway electron energies above hundred keV. The mechanism couples multiple single streamers and streamer head-on collisions, similar to a laboratory discharge, and is suitable for explaining the high-energy X-rays produced by discharges in air and by lightning stepped leaders.

  17. Streamer properties and associated x-rays in perturbed air

    DEFF Research Database (Denmark)

    Köhn, C; Chanrion, O; Babich, L P

    2018-01-01

    Streamers are ionization waves in electric discharges. One of the key ingredients of streamerpropagation is an ambient gas that serves as a source of free electrons. Here, we explore thedependence of streamer dynamics on different spatial distributions of ambient air molecules. We varythe spatial...... profile of air parallel and perpendicular to the ambient electric field. We consider localsinusoidal perturbations of 5%–100%, as induced from discharge shock waves. We use acylindrically symmetric particle-in-cell code to simulate the evolution of bidirectional streamers andcompare the electron density...

  18. Plasma chemistry in wire chambers

    International Nuclear Information System (INIS)

    Wise, J.

    1990-05-01

    The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an 55 Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed

  19. Limited streamer chamber testing and quality evaluation in ASTRA

    International Nuclear Information System (INIS)

    Anzivino, G.; Bianco, S.; Casaccia, R.

    1991-01-01

    Limited streamer chambers are extensively used for high-energy and nuclear physics experiments in accelerator and underground laboratories. The tracking system of LVD, an underground experiment to study muons and nutrino astronomy, will use roughly 15000 limited streamer chambers and 100000 external pickup strips with digital readout electronics. In the article the different aspects of chamber operation that serve to establish a testing procedure and to define acceptance criteria for selecting reliable and long-life devices, are discussed. The procedures and the results obtained from a long-term test to evaluate streamer chamber quality, based upon a sample of 2900 items, are described. The selection tests and the long-term observations have been performed in the ASTRA laboratory, established at the Laboratori Nazionali di Frascati to carry out quality control procedures for streamer chambers on a large scale and in a controlled environment

  20. Wire Chamber

    CERN Multimedia

    Magnetoscriptive readout wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  1. Wire chamber

    CERN Multimedia

    1967-01-01

    Magnetoscriptive readout wire chamber.Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  2. wire chamber

    CERN Multimedia

    Proportional multi-wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle. Proportional wire chambers allow a much quicker reading than the optical or magnetoscriptive readout wire chambers.

  3. Avalanche and streamer mode operation of resistive plate chambers

    International Nuclear Information System (INIS)

    Cardarelli, R.; Makeev, V.; Santonico, R.

    1996-01-01

    A resistive plate chamber was operated at voltages increasing in steps of 200 V over a 3 kV interval and the transition between the avalanche and streamer modes was studied. The avalanche amplitude was observed to be exponentially dependent on the operating voltage up to a value, characteristic of the gas, where the avalanche saturation occurs and delayed streamer signals start to appear. Signal waveforms, charge and timing distributions are reported. (orig.)

  4. The dynamics of streamer formation and its growth mechanism

    International Nuclear Information System (INIS)

    Zalikhanov, B.Zh.

    2004-01-01

    We report the results of experimental studies of physical processes responsible for the transformation of the electron avalanche to the streamer and its growth towards the cathode. The new experimental data on the mechanism of formation and the structure of the streamer allow a more concrete understanding of the pattern of evolution of long spark discharges, including the lightning, and the interrelation of basic processes in such discharges. (author)

  5. Mechanisms important to later stages of streamer system development

    Science.gov (United States)

    Lehtinen, N. G.; Carlson, B.; Kochkin, P.; Østgaard, N.

    2017-12-01

    Typical streamer modeling focuses on the propagation of the streamer head and thus neglects processes such as electron detachment, electron energy relaxation, and thermalization of the electron energy distribution. These mechanisms, however, may become important at later stages of streamer system development, in particular following streamer collisions. We present a model of a later-stage streamer system development which includes these processes. A linear analysis suggests that these processes under some conditions can lead to new effects, such as excitation of waves similar to striations in the positive column of a glow discharge. Such instabilities do not occur if these mechanisms are neglected under the same conditions, although previous modeling suggested existence of wave-like phenomena during the streamer propagation [Luque et al, 2016, doi:10.1002/2015JA022234]. In the sea-level pressure air, the obtained striation-like waves may manifest as very high frequency range (>10 MHz) oscillations in plasma parameters and may have been detected in the electrode current and electromagnetic radiation measurements during laboratory spark experiments. We discuss whether the longitudinal electric field in such waves can efficiently transfer energy to charged particles, because such a process may play a role in production of x-rays.

  6. Stabilized superconductive wires

    International Nuclear Information System (INIS)

    Randall, R.N.; Wong, J.

    1976-01-01

    A stable, high field, high current conductor is produced by packing multiple, multi-layer rods of a bronze core and niobium or vanadium inner jacket and copper outer jacket into a pure copper tube or other means for forming a pure copper matrix, sealing, working the packed tube to a wire, and by diffusion, heat treating to form a type II superconducting, Beta-Wolfram structure, intermetallic compound as a layer within each of several filaments derived from the rods. The layer of Beta-Wolfram structure compound may be formed in less than 2 h of diffusion heat treatment in a thickness of 0.5--2μ

  7. Composite conductor containing superconductive wires

    Energy Technology Data Exchange (ETDEWEB)

    Larson, W.L.; Wong, J.

    1974-03-26

    A superconductor cable substitute made by coworking multiple rods of superconductive niobium--titanium or niobium--zirconium alloy with a common copper matrix to extend the copper and rods to form a final elongated product which has superconductive wires distributed in a reduced cross-section copper conductor with a complete metallurgical bond between the normal-conductive copper and the superconductor wires contained therein is described. The superconductor cable can be in the form of a tube.

  8. wire chamber

    CERN Multimedia

    1985-01-01

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  9. Wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  10. wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  11. wire chamber

    CERN Multimedia

    Was used in ISR (Intersecting Storage Ring) split field magnet experiment. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  12. Propagation of a plasma streamer in catalyst pores

    Science.gov (United States)

    Zhang, Quan-Zhi; Bogaerts, Annemie

    2018-03-01

    Although plasma catalysis is gaining increasing interest for various environmental applications, the underlying mechanisms are still far from understood. For instance, it is not yet clear whether and how plasma streamers can propagate in catalyst pores, and what is the minimum pore size to make this happen. As this is crucial information to ensure good plasma-catalyst interaction, we study here the mechanism of plasma streamer propagation in a catalyst pore, by means of a two-dimensional particle-in-cell/Monte Carlo collision model, for various pore diameters in the nm-range to μm-range. The so-called Debye length is an important criterion for plasma penetration into catalyst pores, i.e. a plasma streamer can penetrate into pores when their diameter is larger than the Debye length. The Debye length is typically in the order of a few 100 nm up to 1 μm at the conditions under study, depending on electron density and temperature in the plasma streamer. For pores in the range of ∼50 nm, plasma can thus only penetrate to some extent and at very short times, i.e. at the beginning of a micro-discharge, before the actual plasma streamer reaches the catalyst surface and a sheath is formed in front of the surface. We can make plasma streamers penetrate into smaller pores (down to ca. 500 nm at the conditions under study) by increasing the applied voltage, which yields a higher plasma density, and thus reduces the Debye length. Our simulations also reveal that the plasma streamers induce surface charging of the catalyst pore sidewalls, causing discharge enhancement inside the pore, depending on pore diameter and depth.

  13. Modeling the plasma chemistry of stratospheric Blue Jet streamers

    Science.gov (United States)

    Winkler, Holger; Notholt, Justus

    2014-05-01

    Stratospheric Blue Jets (SBJs) are upward propagating discharges in the altitude range 15-40 km above thunderstorms. The currently most accepted theory associates SBJs to the development of the streamer zone of a leader. The streamers emitted from the leader can travel for a few tens of kilometers predominantly in the vertical direction (Raizer et al., 2007). The strong electric fields at the streamer tips cause ionisation, dissociation, and excitation, and give rise to chemical perturbations. While in recent years the effects of electric discharges occurring in the mesosphere (sprites) have been investigated in a number of model studies, there are only a few studies on the impact of SBJs. However, chemical perturbations due to SBJs are of interest as they might influence the stratospheric ozone layer. We present results of detailed plasma chemistry simulations of SBJ streamers for both day-time and night-time conditions. Any effects of the subsequent leader are not considered. The model accounts for more than 500 reactions and calculates the evolution of the 88 species under the influence of the breakdown electric fields at the streamer tip. As the SBJ dynamics is outside the scope of this study, the streamer parameters are prescribed. For this purpose, electric field parameters based on Raizer et al. (2007) are used. The model is applied to the typical SBJ altitude range 15-40 km. The simulations indicate that SBJ streamers cause significant chemical perturbations. In particular, the liberation of atomic oxygen during the discharge leads to a formation of ozone. At the same time, reactive nitrogen and hydrogen radicals are produced which will cause catalytic ozone destruction. Reference: Raizer et al. (2007), J. Atmos. Solar-Terr. Phys., 69 (8), 925-938.

  14. Modeling of plasma chemistry in a corona streamer pulse series in air

    International Nuclear Information System (INIS)

    Nowakowska, H.; Stanco, J.; Dors, M.; Mizeraczyk, J.

    2002-01-01

    The aim of this study is to analyse the chemistry in air treated by a series of corona discharge streamers. Attention is focused on the conversion of ozone and nitrogen oxides. In the model it is assumed that the streamer head of relatively small geometrical dimensions propagates from the anode to the cathode, leaving the streamer channel behind. Any elemental gas volume in the streamer path is subjected first to the conditions of the streamer head, and next to those of the streamer channel. The kinetics of plasma-chemical processes occurring in the gas is modeled numerically for a single streamer and a series of streamers. The temporal evolution of 25 chemical compounds initially present or produced in air is calculated. (author)

  15. Particle-in-cell modeling of streamer branching in CO2 gas

    KAUST Repository

    Levko, Dmitry

    2017-07-07

    The mechanism of streamer branching remains one of the unsolved problems of low-temperature plasma physics. The understanding of this phenomenon requires very high-fidelity models that include, for instance, the kinetic description of electrons. In this paper, we use a two-dimensional particle-in-cell Monte Carlo collisional model to study the branching of anode-directed streamers propagating through short cathode-anode gap filled with atmospheric-pressure CO2 gas. We observe three key phenomena leading to the streamer branching at the considered conditions: flattening of the streamer head, the decrease of the streamer head thickness, and the generation at the streamer head of electrons having the energy larger than 50 eV. For the conditions of our studies, the non-homogeneous distribution of such energetic electrons at the streamer head is probably the primary mechanism responsible for the streamer branching.

  16. On increasing the efficiency of a streamer semiconductor laser

    International Nuclear Information System (INIS)

    Rusakov, K I; Parashchuk, V V

    2007-01-01

    The influence of intense electric and optical fields produced by a streamer discharge in wide-gap semiconductors on their spectroscopic properties is studied. The effect is manifested in the reversible change of the luminescence parameters of the active medium. Methods are proposed for increasing the service life and efficiency of a streamer laser in limiting regimes, which are based on the use of semiconductor protective layers of a certain crystallographic orientation and a crystal microrelief with the size of elements of the order of the wavelength of light. Streamer emission was observed and studied in new promising Eu:CaGa 2 S 4 and Eu:Ca 4 Ga 2 S 7 materials. (lasers)

  17. Reversal film development for streamer chamber track photographs

    International Nuclear Information System (INIS)

    Bahr, J.

    1982-01-01

    It is the aim of this work to create a method of photographic development specially adapted to streamer image recording, i.e., with high sensitivity, only two signal levels, low dependence of the track signal on image intensity having a great jitter and noise suppression. The method has to be suitable for machine development of high speed films. A reversal photographic development was used to realize these demands, whereby strong fogging in the first step negative development and a solving process for silver bromide after blackening are specially introduced process stages. This results in a step-function shaped characteristic curve with small transition region having only two signal levels, i. e., independence of streamer image density, good resolution, fine grain, suppression of flares and low noise in the signal of the clear streamer images

  18. Multipoint Ignition of a Gas Mixture by a Microwave Subcritical Discharge with an Extended Streamer Structure

    Science.gov (United States)

    Aleksandrov, K. V.; Busleev, N. I.; Grachev, L. P.; Esakov, I. I.; Ravaev, A. A.

    2018-02-01

    The results of experimental studies on using an electrical discharge with an extended streamer structure in a quasioptical microwave beam in the multipoint ignition of a propane-air mixture have been reported. The pulsed microwave discharge was initiated at the interior surface of a quartz tube that was filled with the mentioned flammable mixture and introduced into a microwave beam with a subbreakdown initial field. Gas breakdown was initiated by an electromagnetic vibrator. The dependence of the type of discharge on the microwave field strength was examined, the lower concentration threshold of ignition of the propane-air mixture by the studied discharge was determined, and the dynamics of combustion of the flammable mixture with local and multipoint ignition were compared.

  19. Use of a streamer chamber for low energy nuclear physics

    Energy Technology Data Exchange (ETDEWEB)

    Van Bibber, K.; Pang, W.; Avery, M.; Bloemhof, E.

    1979-10-01

    A small streamer chamber has been implemented for low energy heavy ion reaction studies at the LBL 88-inch cyclotron. The response of the chamber to light and heavy ions below 35 MeV/nucleon has been examined. The limited sensitivity of light output as a function of ionization works to advantage in recording a wide variety of tracks in the same photograph whose energy loss may vary considerably. Furthermore, as gas targets are attractive for several reasons, we have investigated the suitability of Ar and Xe for use in streamer chambers.

  20. Use of a streamer chamber for low energy nuclear physics

    International Nuclear Information System (INIS)

    Van Bibber, K.; Pang, W.; Avery, M.; Bloemhof, E.

    1979-10-01

    A small streamer chamber has been implemented for low energy heavy ion reaction studies at the LBL 88-inch cyclotron. The response of the chamber to light and heavy ions below 35 MeV/nucleon has been examined. The limited sensitivity of light output as a function of ionization works to advantage in recording a wide variety of tracks in the same photograph whose energy loss may vary considerably. Furthermore, as gas targets are attractive for several reasons, we have investigated the suitability of Ar and Xe for use in streamer chambers

  1. Evolution of the two-phase flow in a vertical tube-decomposition of gas fraction profiles according to bubble size classes using wire-mesh sensors

    Energy Technology Data Exchange (ETDEWEB)

    Prasser, H.M.; Krepper, E.; Lucas, D. [Forschungszentrum Rossendorf e.V., Dresden (Germany)

    2002-01-01

    The wire-mesh sensor developed by the Forschungszentrum Rossendorf produces sequences of instantaneous gas fraction distributions in a cross section with a time resolution of 1200 frames per second and a spatial resolution of about 2-3 mm. At moderate flow velocities (up to 1-2 m.s{sup -1}), bubble size distributions can be obtained, since each individual bubble is mapped in several successive distributions. The method was used to study the evolution of the bubble size distribution in a vertical two-phase flow. For this purpose, the sensor was placed downstream of an air injector, the distance between air injection and sensor was varied. The bubble identification algorithm allows to select bubbles of a given range of the effective diameter and to calculate partial gas fraction profiles for this diameter range. In this way, the different behaviour of small and large bubbles in respect to the action of the lift force was observed in a mixture of small and large bubbles. (authors)

  2. Application of elastic wave dispersion relations to estimate thermal properties of nanoscale wires and tubes of varying wall thickness and diameter

    International Nuclear Information System (INIS)

    Bifano, Michael F P; Kaul, Pankaj B; Prakash, Vikas

    2010-01-01

    This paper reports dependency of specific heat and ballistic thermal conductance on cross-sectional geometry (tube versus rod) and size (i.e., diameter and wall thickness), in free-standing isotropic non-metallic crystalline nanostructures. The analysis is performed using dispersion relations found by numerically solving the Pochhammer-Chree frequency equation for a tube. Estimates for the allowable phonon dispersion relations within the crystal lattice are obtained by modifying the elastic acoustic dispersion relations so as to account for the discrete nature of the material's crystal lattice. These phonon dispersion relations are then used to evaluate the specific heat and ballistic thermal conductance in the nanostructures as a function of the nanostructure geometry and size. Two major results are revealed in the analysis: increasing the outer diameter of a nanotube while keeping the ratio of the inner to outer tube radius (γ) fixed increases the total number of available phonon modes capable of thermal population. Secondly, decreasing the wall thickness of a nanotube (i.e., increasing γ) while keeping its outer diameter fixed, results in a drastic decrease in the available phonon mode density and a reduction in the frequency of the longitudinal and flexural acoustic phonon modes in the nanostructure. The dependency of the nanostructure's specific heat on temperature indicates 1D, 2D, and 3D geometric phonon confinement regimes. Transition temperatures for each phonon confinement regime are shown to depend on both the nanostructure's wall thickness and outer radius. Compared to nanowires (γ = 0), the frequency reduction of acoustic phonon modes in thinner walled nanotubes (γ = 0.96) is shown to elevate the ballistic thermal conductance of the thin-walled nanotube between 0.2 and 150 K. At 20 K, the ballistic thermal conductance of the thin-walled nanotube (γ = 0.96) becomes 300% greater than that of a solid nanowire. For temperatures above 150 K, the trend

  3. Pulsed and streamer discharges in air above breakdown electric field

    NARCIS (Netherlands)

    A.B. Sun (Anbang); H.J. Teunissen (Jannis); U. M. Ebert (Ute)

    2013-01-01

    htmlabstractA 3D particle model is developed to investigate the streamer formation in electric fields above the breakdown threshold, in atmospheric air (1bar, 300 Kelvin). Adaptive particle management, adaptive mesh refinement and parallel computing techniques are used in the code. Photoionization

  4. Hexagon and stripe patterns in dielectric barrier streamer discharge

    International Nuclear Information System (INIS)

    Dong Lifang; He Yafeng; Yin Zengqian; Chai Zhifang

    2004-01-01

    We present a specially designed dielectric barrier discharge (DBD) system for the study of pattern formation. Hexagon and stripe patterns have been observed in a streamer discharge in a DBD for the first time. The phase diagram of pattern types as a function of applied voltage is given

  5. Multisource waveform inversion of marine streamer data using normalized wavefield

    KAUST Repository

    Choi, Yun Seok

    2013-09-01

    Multisource full-waveform inversion based on the L1- and L2-norm objective functions cannot be applied to marine streamer data because it does not take into account the unmatched acquisition geometries between the observed and modeled data. To apply multisource full-waveform inversion to marine streamer data, we construct the L1- and L2-norm objective functions using the normalized wavefield. The new residual seismograms obtained from the L1- and L2-norms using the normalized wavefield mitigate the problem of unmatched acquisition geometries, which enables multisource full-waveform inversion to work with marine streamer data. In the new approaches using the normalized wavefield, we used the back-propagation algorithm based on the adjoint-state technique to efficiently calculate the gradients of the objective functions. Numerical examples showed that multisource full-waveform inversion using the normalized wavefield yields much better convergence for marine streamer data than conventional approaches. © 2013 Society of Exploration Geophysicists.

  6. Branching of positive discharge streamers in air at varying pressures

    NARCIS (Netherlands)

    Briels, T.M.P.; Veldhuizen, van E.M.; Ebert, U.M.

    2005-01-01

    The formation of positive streamers in a 17-mm gap in air is studied at pressures varying in the range from 1010 to 100 mbar. An intensified charge coupled device camera is used to image the discharge. At high pressures, the discharge shows many branches, while at low pressure, fewer branches arise.

  7. Pseudo-spectral 3D simulations of streamers

    NARCIS (Netherlands)

    A. Luque (Alejandro); U. M. Ebert (Ute); C. Montijn (Carolynne-Sireeh); W. Hundsdorfer (Willem); J. Schmidt; M. Simek; S. Pekarek; V. Prukner

    2007-01-01

    textabstractA three-dimensional code for the simulation of streamers is introduced. The code is based on a fluid model for oxygen-nitrogen mixtures that includes drift, diffusion and attachement of electrons and creation of new charge carriers through impact ionization and photo-ionization. The

  8. KELVIN-HELMHOLTZ INSTABILITY OF A CORONAL STREAMER

    Energy Technology Data Exchange (ETDEWEB)

    Feng, L.; Gan, W. Q. [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, 210008 Nanjing (China); Inhester, B., E-mail: lfeng@pmo.ac.cn [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Str.2, D-37191 Katlenburg-Lindau (Germany)

    2013-09-10

    Shear-flow-driven instability can play an important role in energy transfer processes in coronal plasma. We present for the first time the observation of a kink-like oscillation of a streamer that is probably caused by the streaming kink-mode Kelvin-Helmholtz instability (KHI). The wave-like behavior of the streamer was observed by the Large Angle and Spectrometric Coronagraph Experiment C2 and C3 on board the SOlar and Heliospheric Observatory. The observed wave had a period of about 70-80 minutes, and its wavelength increased from 2 R{sub Sun} to 3 R{sub Sun} in about 1.5 hr. The phase speeds of its crests and troughs decreased from 406 {+-} 20 to 356 {+-} 31 km s{sup -1} during the event. Within the same heliocentric range, the wave amplitude also appeared to increase with time. We attribute the phenomena to the MHD KHI, which occurs at a neutral sheet in a fluid wake. The free energy driving the instability is supplied by the sheared flow and sheared magnetic field across the streamer plane. The plasma properties of the local environment of the streamer were estimated from the phase speed and instability threshold criteria.

  9. Positive streamer initiation from raindrops in thundercloud fields

    DEFF Research Database (Denmark)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

    2016-01-01

    required for the streamer formation is larger than the measured thunderstorm fields. Therefore, the results of simulations suggest that second mechanisms must operate to amplify the local field. Such mechanisms could be electric field space variations via collective effects of many hydrometeors or runaway...

  10. Nongeometrically converted shear waves in marine streamer data

    NARCIS (Netherlands)

    Drijkoningen, G.G.; El Allouche, N.; Thorbecke, J.W.; Bada, G.

    2012-01-01

    Under certain circumstances, marine streamer data contain nongeometrical shear body wave arrivals that can be used for imaging. These shear waves are generated via an evanescent compressional wave in the water and convert to propagating shear waves at the water bottom. They are called

  11. Multisource waveform inversion of marine streamer data using normalized wavefield

    KAUST Repository

    Choi, Yun Seok; Alkhalifah, Tariq Ali

    2013-01-01

    Multisource full-waveform inversion based on the L1- and L2-norm objective functions cannot be applied to marine streamer data because it does not take into account the unmatched acquisition geometries between the observed and modeled data. To apply

  12. Particle based 3D modeling of positive streamer inception

    NARCIS (Netherlands)

    H.J. Teunissen (Jannis)

    2012-01-01

    htmlabstractIn this report we present a particle based 3D model for the study of streamer inception near positive electrodes in air. The particle code is of the PIC-MCC type and an electrode is included using the charge simulation method. An algorithm for the adaptive creation of super-particles is

  13. Pacemaker wires

    International Nuclear Information System (INIS)

    Fransson, S.G.

    1993-01-01

    Evaluation of pacemaker wires were performed by comparing Advanced Multiple Beam Equalization Radiography (AMBER) with conventional chest radiography. The scanning equalization technique of the AMBER unit makes it superior to conventional technique in the depiction of different structures in the mediastinum or in the pleural sinuses. So far motion artifacts have not been considered clinically important. The longer exposure time, however, may impair the assessment of pacemaker wires. The motion artifact described may not only make adequate evaluation impossible but may even give a false impression of a lead fracture. The difference between the two systems was significant. (orig.)

  14. Characteristics of rectangular drift tube for muon identifier

    International Nuclear Information System (INIS)

    Denisov, D.S.; Musienko, Yu.V.

    1987-01-01

    The results of a study of an aluminum drift tube with a cross section of 50 x 100 mm are presented. Argon-methane and argon-isobutane mixtures were used as fillers. For a 16% methane concentration, the nonlinearity of the time-coordinate dependence does not exceed 2 mm. The tube can operate in the self-quenched streamer mode when filled with a mixture of argon with isobutane

  15. Positive and negative streamers in ambient air: measuring diameter, velocity and dissipated energy

    Energy Technology Data Exchange (ETDEWEB)

    Briels, T M P; Kos, J; Van Veldhuizen, E M; Ebert, U [Department of Applied Physics, Technische Universiteit Eindhoven, PO Box 513, 5600 MB Eindhoven (Netherlands); Winands, G J J [Department of Electrical Engineering, Technische Universiteit Eindhoven, PO Box 513, 5600 MB Eindhoven (Netherlands)], E-mail: e.m.v.veldhuizen@tue.nl, E-mail: ebert@cwi.nl

    2008-12-07

    Positive and negative streamers are studied in ambient air at 1 bar; they emerge from a needle electrode placed 40 mm above a planar electrode. The amplitudes of the applied voltage pulses range from 5 to 96 kV; most pulses have rise times of 30 ns or shorter. Diameters, velocities and energies of the streamers are measured. Two regimes are identified; a low voltage regime where only positive streamers appear and a high voltage regime where both positive and negative streamers exist. Below 5 kV, no streamers emerge. In the range from 5 to 40 kV, positive streamers form, while the negative discharges only form a glowing cloud at the electrode tip, but no streamers. For 5-20 kV, diameters and velocities of the positive streamers have the minimal values of d = 0.2 mm and v {approx} 10{sup 5} m s{sup -1}. For 20-40 kV, their diameters increase by a factor of 6 while the voltage increases only by a factor of 2. Above the transition value of 40 kV, streamers of both polarities form; they strongly resemble each other, though the positive ones propagate further; their diameters continue to increase with applied voltage. For 96 kV, positive streamers attain diameters of 3 mm and velocities of 4 x 10{sup 6} m s{sup -1}; negative streamers are about 20% slower and thinner. An empirical fit formula for the relation between velocity v and diameter d is v = 0.5d{sup 2} mm{sup -1} ns{sup -1} for both polarities. Streamers of both polarities dissipate energies of the order of several millijoules per streamer while crossing the gap.

  16. Positive and negative streamers in ambient air: measuring diameter, velocity and dissipated energy

    International Nuclear Information System (INIS)

    Briels, T M P; Kos, J; Van Veldhuizen, E M; Ebert, U; Winands, G J J

    2008-01-01

    Positive and negative streamers are studied in ambient air at 1 bar; they emerge from a needle electrode placed 40 mm above a planar electrode. The amplitudes of the applied voltage pulses range from 5 to 96 kV; most pulses have rise times of 30 ns or shorter. Diameters, velocities and energies of the streamers are measured. Two regimes are identified; a low voltage regime where only positive streamers appear and a high voltage regime where both positive and negative streamers exist. Below 5 kV, no streamers emerge. In the range from 5 to 40 kV, positive streamers form, while the negative discharges only form a glowing cloud at the electrode tip, but no streamers. For 5-20 kV, diameters and velocities of the positive streamers have the minimal values of d = 0.2 mm and v ∼ 10 5 m s -1 . For 20-40 kV, their diameters increase by a factor of 6 while the voltage increases only by a factor of 2. Above the transition value of 40 kV, streamers of both polarities form; they strongly resemble each other, though the positive ones propagate further; their diameters continue to increase with applied voltage. For 96 kV, positive streamers attain diameters of 3 mm and velocities of 4 x 10 6 m s -1 ; negative streamers are about 20% slower and thinner. An empirical fit formula for the relation between velocity v and diameter d is v = 0.5d 2 mm -1 ns -1 for both polarities. Streamers of both polarities dissipate energies of the order of several millijoules per streamer while crossing the gap.

  17. Effect of Sintering Time on Superconducting Wire Bi-Pb-Sr-Ca-Cu-O With Dopant MgO Sheated Ag Using Powder in Tube Method

    Directory of Open Access Journals (Sweden)

    Hariyati Lubis

    2018-01-01

    , A., (2008, Production of YBCO Superconductor Sample by Powder-In-Tube Method (PITM; and Effect of Cd and Ga Doping on the System, University, Department of Physics, Malatya-Turkey Sharma, D., Kumar, R., Awana, V.P.S. 2013. DC and AC Susceptibility Study of Sol-Gel Synthesized Bi2Sr2CaCu2O8+x Superconductor. Ceramic International. 39:1143-1152

  18. Controlling branching in streamer discharge by laser background ionization

    International Nuclear Information System (INIS)

    Takahashi, E; Kato, S; Furutani, H; Sasaki, A; Kishimoto, Y

    2011-01-01

    Irradiation with a KrF laser controlled the positive streamer branching in atmospheric argon gas. This laser irradiation changed the amount of background ionization before the streamer discharge. Measuring the ionization current allowed us to evaluate the initial electron density formed by the KrF laser. We observed characteristic feather-like branching structure and found that it was only suppressed in the irradiated region. The threshold of ionization density which can influence the branching was evaluated to be 5 x 10 5 cm -3 . The relationship between the size of avalanche head and mean distance between initial electrons explained this suppression behaviour. These experimental results support that the feather-like structure originates from the branching model of Loeb-Meek, a probabilistic merging of individual avalanches.

  19. Double streamer phenomena in atmospheric pressure low frequency corona plasma

    International Nuclear Information System (INIS)

    Kim, Dan Bee; Jung, H.; Gweon, B.; Choe, Wonho

    2010-01-01

    Time-resolved images of an atmospheric pressure corona discharge, generated at 50 kHz in a single pin electrode source, show unique positive and negative corona discharge features: a streamer for the positive period and a glow for the negative period. However, unlike in previous reports of dc pulse and low frequency corona discharges, multistreamers were observed at the initial time stage of the positive corona. A possible physical mechanism for the multistreamers is suggested.

  20. Ionizing potential waves and high-voltage breakdown streamers.

    Science.gov (United States)

    Albright, N. W.; Tidman, D. A.

    1972-01-01

    The structure of ionizing potential waves driven by a strong electric field in a dense gas is discussed. Negative breakdown waves are found to propagate with a velocity proportional to the electric field normal to the wavefront. This causes a curved ionizing potential wavefront to focus down into a filamentary structure, and may provide the reason why breakdown in dense gases propagates in the form of a narrow leader streamer instead of a broad wavefront.

  1. Two-dimensional simulation of positive and negative streamers in air

    International Nuclear Information System (INIS)

    Babaeva, N.Yu.; Naidis, G.V.

    1998-01-01

    The paper deals with 2D numerical simulation of positive and negative streamers in air at atmospheric pressure. The dynamics of an axially symmetric streamer based on a charged sphere is described by a coupled system of equations for the electric field and the density of charged particles. The results of simulation show that the production rate of radicals in short sphere-plane gaps depends only weakly on the discharge conditions, that the streamer velocity in uniform field depends linearly on the streamer length, and the field corresponding to the negative streamer propagation with a constant velocity is 2-3 times greater than that obtained with a positive streamer. (J.U.)

  2. A Slow Streamer Blowout at the Sun and Ulysses

    Science.gov (United States)

    Seuss, S. T.; Bemporad, A.; Poletto, G.

    2004-01-01

    On 10 June 2000 a streamer on the southeast limb slowly disappeared from LASCO/C2 over approximately 10 hours. A small CME was reported in C2. A substantial interplanetary CME (ICME) was later detected at Ulysses, which was at quadrature with the Sun and SOHO at the time. This detection illustrates the properties of an ICME for a known solar source and demonstrates that the identification can be done even beyond 3 AU. Slow streamer blowouts such as this have long been known but are little studied. We report on the SOHO observation of a coronal mass ejection (CME) on the solar limb and the subsequent in situ detection at Ulysses, which was near quadrature at the time, above the location of the CME. SOHO-Ulysses quadrature was 13 June, when Ulysses was 3.36 AU from the Sun and 58.2 degrees south of the equator off the east limb. The slow streamer blowout was on 10 June, when the SOHO-Sun-Ulysses angle was 87 degrees.

  3. A nautical study of towed marine seismic streamer cable configurations

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Egil

    1996-12-31

    This study concerns marine seismic surveying and especially the towed in-sea hardware which is dominated by recording cables (streamers) that are extremely long compared to their diameter, neutrally buoyant and depth controlled. The present work aims to examine the operations from a nautical viewpoint, and the final objective is to propose improvements to the overall efficiency of marine seismic operations. Full-scale data were gathered from seismic vessels in order to identify which physical parameters affect the dynamic motion of the towing vessel and its in-sea hardware. Experimental test programmes have been carried out, and data bases with the hydrodynamic characteristics of the test equipment have been established at speeds comparable to those used in seismic operations. A basic analysis tool to provide dynamic simulations of a seismic streamer cable has been developed by tailoring the computer program system Riflex, and the validation and accuracy of this modified Riflex system are evaluated by performing uncertainty analyses of measurements and computations. Unexpected, low-frequency depth motions in towed seismic streamer cables occasionally take place when seismic data are being acquired. The phenomenon is analysed and discussed. 99 refs., 116 figs., 5 tabs.

  4. A nautical study of towed marine seismic streamer cable configurations

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Egil

    1997-12-31

    This study concerns marine seismic surveying and especially the towed in-sea hardware which is dominated by recording cables (streamers) that are extremely long compared to their diameter, neutrally buoyant and depth controlled. The present work aims to examine the operations from a nautical viewpoint, and the final objective is to propose improvements to the overall efficiency of marine seismic operations. Full-scale data were gathered from seismic vessels in order to identify which physical parameters affect the dynamic motion of the towing vessel and its in-sea hardware. Experimental test programmes have been carried out, and data bases with the hydrodynamic characteristics of the test equipment have been established at speeds comparable to those used in seismic operations. A basic analysis tool to provide dynamic simulations of a seismic streamer cable has been developed by tailoring the computer program system Riflex, and the validation and accuracy of this modified Riflex system are evaluated by performing uncertainty analyses of measurements and computations. Unexpected, low-frequency depth motions in towed seismic streamer cables occasionally take place when seismic data are being acquired. The phenomenon is analysed and discussed. 99 refs., 116 figs., 5 tabs.

  5. Probing photo-ionization: simulations of positive streamers in varying N2:O2 mixtures

    OpenAIRE

    Wormeester, G; Pancheshnyi, S; Luque, A A; Nijdam, S Sander; Ebert, UM Ute

    2010-01-01

    htmlabstractPhoto-ionization is the accepted mechanism for the propagation of positive streamers in air though the parameters are not very well known; the efficiency of this mechanism largely depends on the presence of both nitrogen and oxygen. But experiments show that streamer propagation is amazingly robust against changes of the gas composition; even for pure nitrogen with impurity levels below 1 ppm streamers propagate essentially with the same velocity as in air, but their minimal diame...

  6. Numerical modeling of positive streamer in air in nonuniform fields: Efficiency of radicals production

    International Nuclear Information System (INIS)

    Kulikovsky, A.A.

    2001-01-01

    The efficiency of streamer corona depends on a number of factors such as geometry of electrodes, voltage pulse parameters, gas pressure etc. In a past 5 years a two-dimensional models of streamer in nonuniform fields in air have been developed. These models allow to simulate streamer dynamics and generation of species and to investigate the influence of external parameters on species production. In this work the influence of Laplacian field on efficiency of radicals generation is investigated

  7. The influence of bremsstrahlung on electric discharge streamers in N2, O2 gas mixtures

    DEFF Research Database (Denmark)

    Köhn, Christoph; Chanrion, Olivier; Neubert, Torsten

    2017-01-01

    Streamers are ionization filaments of electric gas discharges. Negative polarity streamers propagate primarily through electron impact ionization, whereas positive streamers in air develop through ionization of oxygen by UV photons emitted by excited nitrogen; however, experiments show that posit...

  8. 2d axisymmetric "beam-bulk" modelling of the generation of runaway electrons by streamers.

    Science.gov (United States)

    Chanrion, Olivier; Bonaventura, Zdenek; Bourdon, Anne; Neubert, Torsten

    2017-04-01

    We present results from a 2d axisymmetric numerical model of streamers based on a "beam-bulk" approach which describes cold electrons with a fluid model and high energy electrons with a particle model. The interest is motivated by the generation of runaway electrons by streamers which may participate in the recently observed TGFs and which challenge the modelling. Runaway electrons are known to be generated from streamers when the electric field in its negative tip is of sufficient magnitude. After overtaking the streamer tip, runaways can affect the streamer propagation ahead and may produce high energy photons through the bremsstrahlung process. In conventional model of streamers, the evolution of the streamer discharge is mostly governed by cold electrons. By including runaway electrons, we model their production, their impact on the discharge propagation and can address their role in TGFs. Results of streamer propagation in leader electric field show that the runaway electrons accelerate the streamers, reduce the electric field in its tip and enlarge its radius by pre-ionizing the gas ahead. We observed that if we increase the electric field, the discharge is getting more diffuse, with a pattern driven by the increase in runaway induced ionisation.

  9. Evaluation of pulsed streamer corona experiments to determine the O* radical yield

    International Nuclear Information System (INIS)

    Van Heesch, E J M; Winands, G J J; Pemen, A J M

    2008-01-01

    The production of O* radicals in air by a pulsed streamer plasma is studied by integration of a large set of precise experimental data and the chemical kinetics of ozone production. The measured data comprise ozone production, plasma energy, streamer volume, streamer length, streamer velocity, humidity and gas-flow rate. Instead of entering input parameters into a kinetic model to calculate the end products the opposite strategy is followed. Since the amount of end-products (ozone) is known from the measurements the model had to be applied in the reverse direction to determine the input parameters, i.e. the O* radical concentration.

  10. Evaluation of pulsed streamer corona experiments to determine the O* radical yield

    Science.gov (United States)

    van Heesch, E. J. M.; Winands, G. J. J.; Pemen, A. J. M.

    2008-12-01

    The production of O* radicals in air by a pulsed streamer plasma is studied by integration of a large set of precise experimental data and the chemical kinetics of ozone production. The measured data comprise ozone production, plasma energy, streamer volume, streamer length, streamer velocity, humidity and gas-flow rate. Instead of entering input parameters into a kinetic model to calculate the end products the opposite strategy is followed. Since the amount of end-products (ozone) is known from the measurements the model had to be applied in the reverse direction to determine the input parameters, i.e. the O* radical concentration.

  11. Probing photo-ionization: experiments on positive streamers in pure gases and mixtures

    International Nuclear Information System (INIS)

    Nijdam, S; Van de Wetering, F M J H; Blanc, R; Van Veldhuizen, E M; Ebert, U

    2010-01-01

    Positive streamers are thought to propagate by photo-ionization; the parameters of photo-ionization depend on the nitrogen : oxygen ratio. Therefore we study streamers in nitrogen with 20%, 0.2% and 0.01% oxygen and in pure nitrogen as well as in pure oxygen and argon. Our new experimental set-up guarantees contamination of the pure gases to be well below 1 ppm. Streamers in oxygen are difficult to measure as they emit considerably less light in the sensitivity range of our fast ICCD camera than the other gases. Streamers in pure nitrogen and in all nitrogen-oxygen mixtures look generally similar, but become somewhat thinner and branch more with decreasing oxygen content. In pure nitrogen the streamers can branch so much that they resemble feathers. This feature is even more pronounced in pure argon, with approximately 10 2 hair tips cm -3 in the feathers at 200 mbar; this density can be interpreted as the free electron density creating avalanches towards the streamer stem. It is remarkable that the streamer velocity is essentially the same for similar voltage and pressure in all nitrogen-oxygen mixtures as well as in pure nitrogen, while the oxygen concentration and therefore the photo-ionization lengths vary by more than five orders of magnitude. Streamers in argon have essentially the same velocity as well. The physical similarity of streamers at different pressures is confirmed in all gases; the minimal diameters are smaller than in earlier measurements.

  12. Probing photo-ionization: experiments on positive streamers in pure gases and mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Nijdam, S; Van de Wetering, F M J H; Blanc, R; Van Veldhuizen, E M; Ebert, U, E-mail: s.nijdam@tue.n [Eindhoven University of Technology, Department Applied Physics, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2010-04-14

    Positive streamers are thought to propagate by photo-ionization; the parameters of photo-ionization depend on the nitrogen : oxygen ratio. Therefore we study streamers in nitrogen with 20%, 0.2% and 0.01% oxygen and in pure nitrogen as well as in pure oxygen and argon. Our new experimental set-up guarantees contamination of the pure gases to be well below 1 ppm. Streamers in oxygen are difficult to measure as they emit considerably less light in the sensitivity range of our fast ICCD camera than the other gases. Streamers in pure nitrogen and in all nitrogen-oxygen mixtures look generally similar, but become somewhat thinner and branch more with decreasing oxygen content. In pure nitrogen the streamers can branch so much that they resemble feathers. This feature is even more pronounced in pure argon, with approximately 10{sup 2} hair tips cm{sup -3} in the feathers at 200 mbar; this density can be interpreted as the free electron density creating avalanches towards the streamer stem. It is remarkable that the streamer velocity is essentially the same for similar voltage and pressure in all nitrogen-oxygen mixtures as well as in pure nitrogen, while the oxygen concentration and therefore the photo-ionization lengths vary by more than five orders of magnitude. Streamers in argon have essentially the same velocity as well. The physical similarity of streamers at different pressures is confirmed in all gases; the minimal diameters are smaller than in earlier measurements.

  13. High-resolution seismic reflection surveying with a land streamer

    Science.gov (United States)

    Cengiz Tapırdamaz, Mustafa; Cankurtaranlar, Ali; Ergintav, Semih; Kurt, Levent

    2013-04-01

    In this study, newly designed seismic reflection data acquisition array (land streamer) is utilized to image the shallow subsurface. Our acquisition system consist of 24 geophones screwed on iron plates with 2 m spacing, moving on the surface of the earth which are connected with fire hose. Completely original, 4.5 Kg weight iron plates provides satisfactory coupling. This land-streamer system enables rapid and cost effective acquisition of seismic reflection data due to its operational facilities. First test studies were performed using various seismic sources such as a mini-vibro truck, buffalo-gun and hammer. The final fieldwork was performed on a landslide area which was studied before. Data acquisition was carried out on the line that was previously measured by the seismic survey using 5 m geophone and shot spacing. This line was chosen in order to re-image known reflection patterns obtained from the previous field study. Taking penetration depth into consideration, a six-cartridge buffalo-gun was selected as a seismic source to achieve high vertical resolution. Each shot-point drilled 50 cm for gunshots to obtain high resolution source signature. In order to avoid surface waves, the offset distance between the source and the first channel was chosen to be 50 m and the shot spacing was 2 m. These acquisition parameters provided 12 folds at each CDP points. Spatial sampling interval was 1 m at the surface. The processing steps included standard stages such as gain recovery, editing, frequency filtering, CDP sorting, NMO correction, static correction and stacking. Furthermore, surface consistent residual static corrections were applied recursively to improve image quality. 2D F-K filter application was performed to suppress air and surface waves at relatively deep part of the seismic section. Results show that, this newly designed, high-resolution land seismic data acquisition equipment (land-streamer) can be successfully used to image subsurface. Likewise

  14. Sensitive and simple method for measuring wire tensions

    International Nuclear Information System (INIS)

    Atac, M.; Mishina, M.

    1982-08-01

    Measuring tension of wires in drift chambers and multiwire proportional chambers after construction is an important process because sometimes wires get loose after soldering, crimping or glueing. One needs to sort out wires which have tensions below a required minimum value to prevent electrostatic instabilities. There have been several methods reported on this subject in which the wires were excited either with sinusoidal current under magnetic field or with sinusoidal voltage electrostatically coupled to the wire, searching for a resonating frequency with which the wires vibrate mechanically. Then the vibration is detected either visually, optically or with magnetic pick-up directly touching the wires. Any of these is only applicable to the usual multiwire chamber which has open access to the wire plane. They also need fairly large excitation currents to induce a detectable vibration to the wires. Here we report a very simple method that can be used for any type of wire chamber or proportional tube system for measuring wire tension. Only a very small current is required for the wire excitation to obtain a large enough signal because it detects the induced emf voltage across a wire. A sine-wave oscillator and a digital voltmeter are sufficient devices aside from a permanent magnet to provide the magnetic field around the wire. A useful application of this method to a large system is suggested

  15. Problems associated with iridium-192 wire implants

    International Nuclear Information System (INIS)

    Arnott, S.J.; Law, J.; Ash, D.; Flynn, A.; Paine, C.H.; Durrant, K.R.; Barber, C.D.; Dixon-Brown, A.

    1985-01-01

    Three incidents are reported, from different radiotherapy centres, in which an implanted iridium-192 wire remained in the tissues of a patient after withdrawal of the plastic tubing in which it was contained. In each case the instrument used to cut the wire had probably formed a hook on the end of the wire which caused it to catch in the tissues. Detailed recommendations are made for avoiding such incidents in the future, the most important of which is that the patient should be effectively monitored after the supposed removal of all radioactive sources. (author)

  16. Study on the streamer inception characteristics under positive lightning impulse voltage

    Directory of Open Access Journals (Sweden)

    Zezhong Wang

    2017-11-01

    Full Text Available The streamer is the main process in an air gap discharge, and the inception characteristics of streamers have been widely applied in engineering. Streamer inception characteristics under DC voltage have been studied by many researchers, but the inception characteristics under impulse voltage, and particularly under lightning impulse voltage with a high voltage rise rate have rarely been studied. A measurement system based on integrated optoelectronic technology has been proposed in this paper, and the streamer inception characteristics in a 1-m-long rod-plane air gap that was energized by a positive lightning impulse voltage have been researched. We have also measured the streamer inception electric field using electrodes with different radii of curvature and different voltage rise rates. As a result, a modified empirical criterion for the streamer inception electric field that considers the voltage rise rate has been proposed, and the wide applicability of this criterion has been proved. Based on the streamer inception time-lag obtained, we determined that the field distribution obeys a Rayleigh distribution, which explains the change law of the streamer inception time-lag. The characteristic parameter of the Rayleigh distribution lies in the range from 0.6 to 2.5 when the radius of curvature of the electrode head is in the range from 0.5 cm to 2.5 cm and the voltage rise rate ranges from 80 kV/μs to 240kV/μs under positive lightning impulse voltage.

  17. Experiments on how photo- and background ionization affect positive streamers: oxygen concentration, repetition and radioactivity

    NARCIS (Netherlands)

    Nijdam, S.; Veldhuizen, van E.M.; Ebert, U.

    2011-01-01

    Positive streamers in air and other oxygen-nitrogen mixtures are generally believed to propagate against the electron drift direction due to photo-ionization. Photo-ionization is the non-local ionization of O2-molecules by UV radiation from excited N2-molecules. This facilitates the streamer

  18. Evaluation of a charged coupled device camera for streamer chamber applications

    International Nuclear Information System (INIS)

    Holmgren, D.; Wallick, W.; Kenyon, R.; Lubatti, H.J.

    1978-01-01

    The response of a charged coupled device to a Ne light source is studied and compared to the Kodak SO-143 film commonly used for streamer chamber applications. It is found that the CCD-202 cooled to -10 0 C is considerably more sensitive than the film. A test of a CCD-based measurement system observing a streamer chamber is described. 3 refs

  19. SYMPATHETIC FILAMENT ERUPTIONS FROM A BIPOLAR HELMET STREAMER IN THE SUN

    International Nuclear Information System (INIS)

    Yang Jiayan; Jiang Yunchun; Zheng Ruisheng; Bi Yi; Hong Junchao; Yang Bo

    2012-01-01

    On 2005 August 5, two solar filaments erupted successively from different confined arcades underlying a common overarching multiple-arcade bipolar helmet streamer. We present detailed observations of these two events and identify them as sympathetic filament eruptions. The first (F1) is a small active-region filament located near the outskirts of the streamer arcade. It underwent a nonradial eruption, initially moving in the interior of the streamer arcade and resulting in an over-and-out coronal mass ejection. The second filament (F2), a larger quiescent one far away from F1, was clearly disturbed during the F1 eruption. It then underwent a very slow eruption and finally disappeared completely and permanently. Because two belt-shaped diffuse dimmings formed along the footprints of the streamer arcade in the first eruption and persisted throughout the complete disappearance of F2, the eruption series are interpreted as sympathetic: the simple expansion of the common streamer arcade forced by the F1 eruption weakened magnetic flux overlying F2 and thus led to its slow eruption, with the dimming formation indicating their physical connection. Our observations suggest that multiple-arcade bipolar helmet-streamer configurations are appropriate to producing sympathetic eruptions. Combined with the recent observations of unipolar-streamer sympathetic events, it appears that a multiple-arcade unipolar or bipolar helmet streamer can serve as a common magnetic configuration for sympathetic eruptions.

  20. Circuit dependence of the diameter of pulsed positive streamers in air

    Energy Technology Data Exchange (ETDEWEB)

    Briels, T M P [Department of Applied Physics, Technische Universiteit Eindhoven, PO Box 513, 5600MB Eindhoven (Netherlands); Kos, J [Department of Applied Physics, Technische Universiteit Eindhoven, PO Box 513, 5600MB Eindhoven (Netherlands); Veldhuizen, E M van [Department of Applied Physics, Technische Universiteit Eindhoven, PO Box 513, 5600MB Eindhoven (Netherlands); Ebert, U [Department of Applied Physics, Technische Universiteit Eindhoven, PO Box 513, 5600MB Eindhoven (Netherlands)

    2006-12-21

    The diameter and branching structure of positive streamers in ambient air are investigated with a fast iCCD camera. We use different pulsed power circuits and find that they generate different spatial streamer structures. The electrodes have a point-plane geometry and a distance of 40 or 80 mm, and the peak voltages over the discharge gap are up to 60 kV. Depending on circuit and peak voltage, we observe streamers with diameters varying gradually between 0.2 and 2.5 mm. The streamer velocity increases with the diameter, ranging from 0.07 to 1.5 mm ns{sup -1}, while the current density within the streamers stays almost constant. The thicker streamers extend much further before they branch than the thinner ones. The pulsed power supplies are a switched capacitor supply with an internal resistance of 1 k{omega} and a transmission line transformer supply with an impedance of 200 {omega}; additional resistors change the impedance as well as the voltage rise time in the case of the capacitor supply. We observe that short rise times and low impedance create thick streamers close to the pointed electrode, while a longer rise time as well as a higher impedance create thinner streamers at the same peak voltage over the discharge.

  1. Circuit dependence of the diameter of pulsed positive streamers in air

    International Nuclear Information System (INIS)

    Briels, T M P; Kos, J; Veldhuizen, E M van; Ebert, U

    2006-01-01

    The diameter and branching structure of positive streamers in ambient air are investigated with a fast iCCD camera. We use different pulsed power circuits and find that they generate different spatial streamer structures. The electrodes have a point-plane geometry and a distance of 40 or 80 mm, and the peak voltages over the discharge gap are up to 60 kV. Depending on circuit and peak voltage, we observe streamers with diameters varying gradually between 0.2 and 2.5 mm. The streamer velocity increases with the diameter, ranging from 0.07 to 1.5 mm ns -1 , while the current density within the streamers stays almost constant. The thicker streamers extend much further before they branch than the thinner ones. The pulsed power supplies are a switched capacitor supply with an internal resistance of 1 kΩ and a transmission line transformer supply with an impedance of 200 Ω; additional resistors change the impedance as well as the voltage rise time in the case of the capacitor supply. We observe that short rise times and low impedance create thick streamers close to the pointed electrode, while a longer rise time as well as a higher impedance create thinner streamers at the same peak voltage over the discharge

  2. Positive streamers in air and nitrogen of varying density: experiments on similarity laws

    International Nuclear Information System (INIS)

    Briels, T M P; Van Veldhuizen, E M; Ebert, U

    2008-01-01

    Positive streamers in ambient air at pressures from 0.013 to 1 bar are investigated experimentally. The voltage applied to the anode needle ranges from 5 to 45 kV, the discharge gap from 1 to 16 cm. Using a 'slow' voltage rise time of 100-180 ns, the streamers are intentionally kept thin. For each pressure p, we find a minimal diameter d min . To test whether streamers at different pressures are similar, the minimal streamer diameter d min is multiplied by its pressure p; we find this product to be well approximated by p · d min = 0.20 ± 0.02 mm bar over two decades of air pressure at room temperature. The value also fits diameters of sprite discharges above thunderclouds at an altitude of 80 km when extrapolated to room temperature (as air density rather than pressure determines the physical behaviour). The minimal velocity of streamers in our measurements is approximately 0.1 mm ns -1 = 10 5 m s -1 . The same minimal velocity has been reported for tendrils in sprites. We also investigate the size of the initial ionization cloud at the electrode tip from which the streamers emerge, and the streamer length between branching events. The same quantities are also measured in nitrogen with a purity of approximately 99.9%. We characterize the essential differences with streamers in air and find a minimal diameter of p · d min = 0.12 ± 0.02 mm bar in our nitrogen.

  3. Study on the streamer inception characteristics under positive lightning impulse voltage

    Science.gov (United States)

    Wang, Zezhong; Geng, Yinan

    2017-11-01

    The streamer is the main process in an air gap discharge, and the inception characteristics of streamers have been widely applied in engineering. Streamer inception characteristics under DC voltage have been studied by many researchers, but the inception characteristics under impulse voltage, and particularly under lightning impulse voltage with a high voltage rise rate have rarely been studied. A measurement system based on integrated optoelectronic technology has been proposed in this paper, and the streamer inception characteristics in a 1-m-long rod-plane air gap that was energized by a positive lightning impulse voltage have been researched. We have also measured the streamer inception electric field using electrodes with different radii of curvature and different voltage rise rates. As a result, a modified empirical criterion for the streamer inception electric field that considers the voltage rise rate has been proposed, and the wide applicability of this criterion has been proved. Based on the streamer inception time-lag obtained, we determined that the field distribution obeys a Rayleigh distribution, which explains the change law of the streamer inception time-lag. The characteristic parameter of the Rayleigh distribution lies in the range from 0.6 to 2.5 when the radius of curvature of the electrode head is in the range from 0.5 cm to 2.5 cm and the voltage rise rate ranges from 80 kV/μs to 240kV/μs under positive lightning impulse voltage.

  4. Optical diagnostics of streamer discharges in atmospheric gases

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan

    2014-01-01

    Roč. 47, č. 46 (2014), s. 463001-463001 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GAP205/12/1709 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431201 Program:M Institutional support: RVO:61389021 Keywords : streamer * optical diagnostics * laser-induced fluorescence * LIF * TALIF * red-sprite Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.721, year: 2014 http://iopscience.iop.org/0022-3727/47/46/463001/pdf/0022-3727_47_46_463001.pdf

  5. CCD camera system for use with a streamer chamber

    International Nuclear Information System (INIS)

    Angius, S.A.; Au, R.; Crawley, G.C.; Djalali, C.; Fox, R.; Maier, M.; Ogilvie, C.A.; Molen, A. van der; Westfall, G.D.; Tickle, R.S.

    1988-01-01

    A system based on three charge-coupled-device (CCD) cameras is described here. It has been used to acquire images from a streamer chamber and consists of three identical subsystems, one for each camera. Each subsystem contains an optical lens, CCD camera head, camera controller, an interface between the CCD and a microprocessor, and a link to a minicomputer for data recording and on-line analysis. Image analysis techniques have been developed to enhance the quality of the particle tracks. Some steps have been made to automatically identify tracks and reconstruct the event. (orig.)

  6. Application of irradiated wire

    International Nuclear Information System (INIS)

    Uda, I.; Kozima, K.; Suzuki, S.; Tada, S.; Torisu, S.; Veno, K.

    1984-01-01

    Rubber insulated wires are still useful for internal wiring in motor vehicles and electrical equipment because of flexibility and toughness. Irradiated cross-linked rubber materials have been successfully introduced for use with fusible link wire and helically coiled cord

  7. Noncontextual Wirings

    Science.gov (United States)

    Amaral, Barbara; Cabello, Adán; Cunha, Marcelo Terra; Aolita, Leandro

    2018-03-01

    Contextuality is a fundamental feature of quantum theory necessary for certain models of quantum computation and communication. Serious steps have therefore been taken towards a formal framework for contextuality as an operational resource. However, the main ingredient of a resource theory—a concrete, explicit form of free operations of contextuality—was still missing. Here we provide such a component by introducing noncontextual wirings: a class of contextuality-free operations with a clear operational interpretation and a friendly parametrization. We characterize them completely for general black-box measurement devices with arbitrarily many inputs and outputs. As applications, we show that the relative entropy of contextuality is a contextuality monotone and that maximally contextual boxes that serve as contextuality bits exist for a broad class of scenarios. Our results complete a unified resource-theoretic framework for contextuality and Bell nonlocality.

  8. Wire winding increases lifetime of oxide coated cathodes

    Science.gov (United States)

    Kerslake, W.; Vargo, D.

    1965-01-01

    Refractory-metal heater base wound with a thin refractory metal wire increases the longevity of oxide-coated cathodes. The wire-wound unit is impregnated with the required thickness of metal oxide. This cathode is useful in magnetohydrodynamic systems and in electron tubes.

  9. Water-cooled grid ''wires'' for direct converters

    International Nuclear Information System (INIS)

    Schwer, C.J.

    1976-01-01

    A study was conducted to determine the feasibility of internal convective cooling of grid ''wires'' for direct converters. Detailed computer calculations reveal that the use of small diameter water cooled tubes as grid ''wires'' is feasible for a considerable range of lengths and thermal fluxes

  10. Fully kinetic particle simulations of high pressure streamer propagation

    Science.gov (United States)

    Rose, David; Welch, Dale; Thoma, Carsten; Clark, Robert

    2012-10-01

    Streamer and leader formation in high pressure devices is a dynamic process involving a hierarchy of physical phenomena. These include elastic and inelastic particle collisions in the gas, radiation generation, transport and absorption, and electrode interactions. We have performed 2D and 3D fully EM implicit particle-in-cell simulation model of gas breakdown leading to streamer formation under DC and RF fields. The model uses a Monte Carlo treatment for all particle interactions and includes discrete photon generation, transport, and absorption for ultra-violet and soft x-ray radiation. Central to the realization of this fully kinetic particle treatment is an algorithm [D. R. Welch, et al., J. Comp. Phys. 227, 143 (2007)] that manages the total particle count by species while preserving the local momentum distribution functions and conserving charge. These models are being applied to the analysis of high-pressure gas switches [D. V. Rose, et al., Phys. Plasmas 18, 093501 (2011)] and gas-filled RF accelerator cavities [D. V. Rose, et al. Proc. IPAC12, to appear].

  11. Effect of electric field configuration on streamer and partial discharge phenomena in a hydrocarbon insulating liquid under AC stress

    International Nuclear Information System (INIS)

    Liu, Z; Liu, Q; Wang, Z D

    2016-01-01

    This paper concerns pre-breakdown phenomena, including streamer characteristics from a fundamental perspective and partial discharge (PD) measurements from an industrial perspective, in a hydrocarbon insulating liquid. The aim was to investigate the possible changes of the liquid’s streamer and PD characteristics and their correlations when the uniformity of the AC electric field varies. In the experiments, a plane-to-plane electrode system incorporating a needle protrusion was used in addition to a needle-to-plane electrode system. When the applied electric field became more uniform, fewer radial branches occurred and streamer propagation towards the ground electrode was enhanced. The transition from streamer propagation dominated breakdown in divergent fields to streamer initiation dominated breakdown in uniform fields was evidenced. Relationships between streamer and PD characteristics were established, which were found to be electric field dependent. PD of the same apparent charge would indicate longer streamers if the electric field is more uniform. (paper)

  12. An adaptive grid refinement strategy for the simulation of negative streamers

    International Nuclear Information System (INIS)

    Montijn, C.; Hundsdorfer, W.; Ebert, U.

    2006-01-01

    The evolution of negative streamers during electric breakdown of a non-attaching gas can be described by a two-fluid model for electrons and positive ions. It consists of continuity equations for the charged particles including drift, diffusion and reaction in the local electric field, coupled to the Poisson equation for the electric potential. The model generates field enhancement and steep propagating ionization fronts at the tip of growing ionized filaments. An adaptive grid refinement method for the simulation of these structures is presented. It uses finite volume spatial discretizations and explicit time stepping, which allows the decoupling of the grids for the continuity equations from those for the Poisson equation. Standard refinement methods in which the refinement criterion is based on local error monitors fail due to the pulled character of the streamer front that propagates into a linearly unstable state. We present a refinement method which deals with all these features. Tests on one-dimensional streamer fronts as well as on three-dimensional streamers with cylindrical symmetry (hence effectively 2D for numerical purposes) are carried out successfully. Results on fine grids are presented, they show that such an adaptive grid method is needed to capture the streamer characteristics well. This refinement strategy enables us to adequately compute negative streamers in pure gases in the parameter regime where a physical instability appears: branching streamers

  13. Surface streamer propagations on an alumina bead: experimental observation and numerical modeling

    Science.gov (United States)

    Kang, Woo Seok; Kim, Hyun-Ha; Teramoto, Yoshiyuki; Ogata, Atsushi; Lee, Jin Young; Kim, Dae-Woong; Hur, Min; Song, Young-Hoon

    2018-01-01

    A surface streamer in a simplified packed-bed reactor has been studied both experimentally (through time-resolved ICCD imaging) and theoretically (through two-dimensional numerical modeling). The propagation of streamers on an alumina spherical bead without catalytic coating shows three distinct phases—the generation and propagation of a primary streamer (PS) with a moderate velocity and electric field, fast PS acceleration with an enhanced electric field, and slow secondary streamer (SS) propagation. The velocity of the streamer is less than that of propagation in a gaseous media. The electric field and velocity at the streamer front are maximized when a PS propagates during the interval from the midpoint of the bead to the bottom electrode. The SS exhibits a much lower velocity and electric field compared with the PS. The PS velocity is affected by an external applied voltage, especially when it approaches the ground electrode. However, that of the SS remains constant regardless of the voltage change. The simulation shows that the PS exhibits a high electric field mainly created by the space charge induced by electrons, whereas the SS relies on ion movement with electron decay in a charge-filled thin streamer body.

  14. Two-Dimensional Electron Density Measurement of Positive Streamer Discharge in Atmospheric-Pressure Air

    Science.gov (United States)

    Inada, Yuki; Ono, Ryo; Kumada, Akiko; Hidaka, Kunihiko; Maeyama, Mitsuaki

    2016-09-01

    The electron density of streamer discharges propagating in atmospheric-pressure air is crucially important for systematic understanding of the production mechanisms of reactive species utilized in wide ranging applications such as medical treatment, plasma-assisted ignition and combustion, ozone production and environmental pollutant processing. However, electron density measurement during the propagation of the atmospheric-pressure streamers is extremely difficult by using the conventional localized type measurement systems due to the streamer initiation jitters and the irreproducibility in the discharge paths. In order to overcome the difficulties, single-shot two-dimensional electron density measurement was conducted by using a Shack-Hartmann type laser wavefront sensor. The Shack-Hartmann sensor with a temporal resolution of 2 ns was applied to pulsed positive streamer discharges generated in an air gap between pin-to-plate electrodes. The electron density a few ns after the streamer initiation was 7*1021m-3 and uniformly distributed along the streamer channel. The electron density and its distribution profile were compared with a previous study simulating similar streamers, demonstrating good agreement. This work was supported in part by JKA and its promotion funds from KEIRIN RACE. The authors like to thank Mr. Kazuaki Ogura and Mr. Kaiho Aono of The University of Tokyo for their support during this work.

  15. Superconducting wire for the T-15 toroidal magnet

    International Nuclear Information System (INIS)

    Klimenko, E.Yu.; Kruglov, V.S.; Martovetskij, N.N.

    1987-01-01

    Main characteristics of a wire designed for the T-15 toroidal superconducting magnet production are given. The wire with circulation cooling is a twist of 11 niobium-tin wires 1.5 mm in diameter, joined electrolytically by two copper tubes with 3 mm inside diameter. The wire is capable to carry 10 kA current in the 8.5 T induction field. Wire features and structures promote to receive high structural current density in winding: diffuseness of superconducting-to-normal transition increases wire stability, screw symmetry od a current-carrying core provides wire resistance to pulse longitudinal field effect at plasma current disruption, low bronze thermal conductivity in a twist increases stability to outside pulse perturbations

  16. Probing background ionization: positive streamers with varying pulse repetition rate and with a radioactive admixture

    International Nuclear Information System (INIS)

    Nijdam, S; Van Veldhuizen, E M; Ebert, U; Wormeester, G

    2011-01-01

    Positive streamers need a source of free electrons ahead of them to propagate. A streamer can supply these electrons by itself through photo-ionization, or the electrons can be present due to external background ionization. Here we investigate the effects of background ionization on streamer propagation and morphology by changing the gas composition and the repetition rate of the voltage pulses, and by adding a small amount of radioactive 85 Kr. We find that the general morphology of a positive streamer discharge in high-purity nitrogen depends on background ionization: at lower background ionization levels the streamers branch more and have a more feather-like appearance. This is observed both when varying the repetition rate and when adding 85 Kr, though side branches are longer with the radioactive admixture. But velocities and minimal diameters of streamers are virtually independent of the background ionization level. In air, the inception cloud breaks up into streamers at a smaller radius when the repetition rate and therefore the background ionization level is higher. When measuring the effects of the pulse repetition rate and of the radioactive admixture on the discharge morphology, we found that our estimates of background ionization levels are consistent with these observations; this gives confidence in the estimates. Streamer channels generally do not follow the paths of previous discharge channels for repetition rates of up to 10 Hz. We estimate the effect of recombination and diffusion of ions and free electrons from the previous discharge and conclude that the old trail has largely disappeared at the moment of the next voltage pulse; therefore the next streamers indeed cannot follow the old trail.

  17. A study on the development of high-Tc superconducting wire

    International Nuclear Information System (INIS)

    Won, Dong Yeon; Chang, In Soon; Lee, Jong Min; Um, Tae Yoon; Hong, Kyae Won; Lee, Ho Jin; Lee, Hee Kwun; Kim, Chan Joong; Park, Soon Dong; Kim, Woo Gon; Kim, Ki Baek; Kwon, Sun Chil

    1992-10-01

    On this study Y-Ba-Cu-O was prepared by partial melt process and superconducting wire was fabricated by powder-in-tube method. First, mechancial properties, electrical properties, microstructure and oxygen diffusion behavior were observed. Second, through fabricated superconducting wire, conceptual design, composition and plasticity of filament superconducting wire were investigated. (Author)

  18. A study of the self-quenched streamer mode using a nitrogen laser

    International Nuclear Information System (INIS)

    An Jigang; Anderson, K.J.; Merritt, F.S.; Oreglia, M.; Pilcher, J.E.; Possoz, A.; Schappert, W.; Chicago Univ., IL

    1988-01-01

    The characteristics and mechanism of the self-quenched streamer mode have been explored using laser induced ionization. Both the size of the streamer signal and the transformation from proportional to streamer mode depend on high voltage and the primary ionization density. Two nearby tracks influence each other mainly by space charge effects. The zone of influence depends on relative drift time of the tracks but is less than 3 mm along the anode. The influence is less with argon-free strong quenching gas mixtures. (orig.)

  19. Vacuum surface flashover and high pressure gas streamers

    International Nuclear Information System (INIS)

    Elizondo, J.M.; Krogh, M.L.; Smith, D.; Stolz, D.; Wright, S.N.

    1997-07-01

    Pre-breakdown current traces obtained during high pressure gas breakdown and vacuum surface flashover show similar signatures. The initial pre-breakdown current spike, a flat constant current phase, and the breakdown phase with voltage collapse and current surge differ mostly in magnitude. Given these similarities, a model, consisting of the initial current spike corresponding to a fast precursor streamer (ionization wave led by a photoionizing front), the flat current stage as the heating or glow phase, and the terminal avalanche and gap closure, is applied to vacuum surface flashover. A simple analytical approximation based on the resistivity changes induced in the vacuum and dielectric surface is presented. The approximation yields an excellent fit to pre-breakdown time delay vs applied field for previously published experimental data. A detailed kinetics model that includes surface and gas contributions is being developed based in the initial approximation

  20. Diagnostics and modeling of high pressure streamer induced discharges

    International Nuclear Information System (INIS)

    Marode, E.; Dessante, P.; Deschamps, N.; Deniset, C.

    2001-01-01

    A great variety of diagnostic has been applied to gain information on basic parameter governing high pressure nonthermal filamentary plasmas (and namely streamer induced filamentary discharges). Apart from electrical diagnostics, gas discharge, in contrast with solid state physics, can greatly benefit from all optical techniques owing to its ''transparent'' state. Emission and absorption spectroscopy, as well as LIF or CARS (talk are given during this meeting on these two techniques) are among such specific possibilities. The figures gained from these diagnostic measurements has generally no meaning by itself. They must be worked out, by means of calibrated former results, and/or by using them as input in high pressure plasma modeling. Mixing experimental and modeling approach is necessary for reaching relevant physical knowledge of the high pressure filamentary discharges processes. It is shown that diffusion, and thermal space and time distribution, must fully be taken into account

  1. Wire breakage in SLC wire profile monitors

    International Nuclear Information System (INIS)

    Field, C.; McCormick, D.; Raimondi, P.; Ross, M.

    1998-05-01

    Wire scanning beam profile monitors are used at the Stanford Linear Collider (SLC) for emittance preservation control and beam optics optimization. Twenty such scanners have proven most useful for this purpose and have performed a total of 1.5 million scans in the 4 to 6 years since their installation. Most of the essential scanners are equipped with 20 to 40 microm tungsten wires. SLC bunch intensities and sizes often exceed 2 x 10 7 particles/microm 2 (3C/m 2 ). The authors believe that this has caused a number of tungsten wire failures that appear at the ends of the wire, near the wire support points, after a few hundred scans are accumulated. Carbon fibers, also widely used at SLAC, have been substituted in several scanners and have performed well. In this paper, the authors present theories for the wire failure mechanism and techniques learned in reducing the failures

  2. Local electron mean energy profile of positive primary streamer discharge with pin-plate electrodes in oxygen—nitrogen mixtures

    International Nuclear Information System (INIS)

    Sima Wen-Xia; Peng Qing-Jun; Yang Qing; Yuan Tao; Shi Jian

    2013-01-01

    Local electron mean energy (LEME) has a direct effect on the rates of collisional ionization of molecules and atoms by electrons. Electron-impact ionization plays an important role and is the main process for the production of charged particles in a primary streamer discharge. Detailed research on the LEME profile in a primary streamer discharge is extremely important for a comprehensive understanding of the local physical mechanism of a streamer. In this study, the LEME profile of the primary streamer discharge in oxygen-nitrogen mixtures with a pin-plate gap of 0.5 cm under an impulse voltage is investigated using a fluid model. The fluid model includes the electron mean energy density equation, as well as continuity equations for electrons and ions and Poisson's electric field equation. The study finds that, except in the initial stage of the primary streamer, the LEME in the primary streamer tip tends to increase as the oxygen-nitrogen mole ratio increases and the pressure decreases. When the primary streamer bridges the gap, the LEME in the primary streamer channel is smaller than the first ionization energies of oxygen and nitrogen. The LEME in the primary streamer channel then decreases as the oxygen-nitrogen mole ratio increases and the pressure increases. The LEME in the primary streamer tip is primarily dependent on the reduced electric field with mole ratios of oxygen-nitrogen given in the oxygen-nitrogen mixtures. (physics of gases, plasmas, and electric discharges)

  3. Fractal multiplication of electron avalanches and streamers: new mechanism of electrical breakdown?

    International Nuclear Information System (INIS)

    Ficker, T

    2007-01-01

    Long-lasting problems concerning peculiar statistical behaviour of high populated electron avalanches have been analysed. These avalanches are precursors of streamer breakdown in gases. The present streamer theory fails in explaining severe systematic deviations from the Furry statistics that is believed to be a governing statistical law. Such a deviated behaviour of high populated avalanches seems to be a consequence of a special pre-breakdown mechanism that is rather different from that known so far in discharge physics. This analysis tends towards formulating a modified theoretical concept supplementing the streamer theory by a new statistical view of pre-streamer states. The correctness of the concept is corroborated by a series of experiments

  4. Computational Studies of Positive and Negative Streamers in Bubbles Suspended in Distilled Water

    KAUST Repository

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L.

    2017-01-01

    We perform computational studies of nanosecond streamers generated in helium bubbles immersed in distilled water under high pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description

  5. Application of multi-source waveform inversion to marine streamer data using the global correlation norm

    KAUST Repository

    Choi, Yun Seok; Alkhalifah, Tariq Ali

    2012-01-01

    Conventional multi-source waveform inversion using an objective function based on the least-square misfit cannot be applied to marine streamer acquisition data because of inconsistent acquisition geometries between observed and modelled data

  6. Multi-source waveform inversion of marine streamer data using the normalized wavefield

    KAUST Repository

    Choi, Yun Seok; Alkhalifah, Tariq Ali

    2012-01-01

    Even though the encoded multi-source approach dramatically reduces the computational cost of waveform inversion, it is generally not applicable to marine streamer data. This is because the simultaneous-sources modeled data cannot be muted to comply

  7. Particle-in-cell modeling of streamer branching in CO2 gas

    KAUST Repository

    Levko, Dmitry; Pachuilo, Michael; Raja, Laxminarayan L

    2017-01-01

    The mechanism of streamer branching remains one of the unsolved problems of low-temperature plasma physics. The understanding of this phenomenon requires very high-fidelity models that include, for instance, the kinetic description of electrons

  8. Auroral streamers: characteristics of associated precipitation,convection and field-aligned currents

    Directory of Open Access Journals (Sweden)

    V. A. Sergeev

    2004-01-01

    Full Text Available During the long-duration steady convection activity on 11 December 1998, the development of a few dozen auroral streamers was monitored by Polar UVI instrument in the dark northern nightside ionosphere. On many occasions the DMSP spacecraft crossed the streamer-conjugate regions over the sunlit southern auroral oval, permitting the investigation of the characteristics of ion and electron precipitation, ionospheric convection and field-aligned currents associated with the streamers. We confirm the conjugacy of streamer-associated precipitation, as well as their association with ionospheric plasma streams having a substantial equatorward convection component. The observations display two basic types of streamer-associated precipitation. In its polewardmost half, the streamer-associated (field-aligned accelerated electron precipitation coincides with the strong (≥2–7μA/m2 upward field-aligned currents on the westward flank of the convection stream, sometimes accompanied by enhanced proton precipitation in the adjacent region. In the equatorward portion of the streamer, the enhanced precipitation includes both electrons and protons, often without indication of field-aligned acceleration. Most of these characteristics are consistent with the model describing the generation of the streamer by the narrow plasma bubbles (bursty bulk flows which are contained on dipolarized field lines in the plasma sheet, although the mapping is strongly distorted which makes it difficult to quantitatively interprete the ionospheric image. The convective streams in the ionosphere, when well-resolved, had the maximal convection speeds ∼0.5–1km/s, total field-aligned currents of a few tenths of MA, thicknesses of a few hundreds km and a potential drop of a few kV across the stream. However, this might represent only a small part of the associated flux transport in the equatorial plasma sheet.

    Key words. Ionosphere (electric fiels and

  9. Application of CA and NN for event recognition in experiments DISTO and STREAMER

    International Nuclear Information System (INIS)

    Bussa, M.P.; Ivanov, V.V.; Kisel, I.V.; Pontecorvo, G.B.

    1997-01-01

    An algorithm for charged particle recognition and event identification applying a cellular automaton (CA) model and a multi-layer neural network (NN) has been developed for the DISTO experiment under way at Saturne (Saclay, France). A further development of the model will be applied for particle recognition in the Dubna Streamer Chamber Spectrometer (DSCS) for studying pion-nucleus absorption (experiments DISTO and STREAMER). (orig.)

  10. Influence of Auroral Streamers on Rapid Evolution of Ionospheric SAPS Flows

    Science.gov (United States)

    Gallardo-Lacourt, Bea; Nishimura, Y.; Lyons, L. R.; Mishin, E. V.; Ruohoniemi, J. M.; Donovan, E. F.; Angelopoulos, V.; Nishitani, N.

    2017-12-01

    Subauroral polarization streams (SAPS) often show large, rapid enhancements above their slowly varying component. We present simultaneous observations from ground-based all-sky imagers and flows from the Super Dual Auroral Radar Network radars to investigate the relationship between auroral phenomena and flow enhancement. We first identified auroral streamers approaching the equatorward boundary of the auroral oval to examine how often the subauroral flow increased. We also performed the reverse query starting with subauroral flow enhancements and then evaluated the auroral conditions. In the forward study, 98% of the streamers approaching the equatorward boundary were associated with SAPS flow enhancements reaching 700 m/s and typically hundreds of m/s above background speeds. The reverse study reveals that flow enhancements associated with streamers (60%) and enhanced larger-scale convection (37%) contribute to SAPS flow enhancements. The strong correlation of auroral streamers with rapid evolution (approximately minutes) of SAPS flows suggests that transient fast earthward plasma sheet flows can often lead to westward SAPS flow enhancements in the subauroral region and that such enhancements are far more common than only during substorms because of the much more frequent occurrences of streamers under various geomagnetic conditions. We also found a strong correlation between flow duration and streamer duration and a weak correlation between SAPS flow velocity and streamer intensity. This result suggests that intense flow bursts in the plasma sheet (which correlate with intense streamers) are associated with intense SAPS ionospheric flows perhaps by enhancing the ring current pressure and localized pressure gradients when they are able to penetrate close enough to Earth.

  11. Streamer Motives and User-Generated Content on Social Live-Streaming Services

    OpenAIRE

    Friedlander, Mathilde B.

    2017-01-01

    Three most popular information services, Periscope, Ustream, and YouNow, vicarious for all Social Live-Streaming Services (SLSSs), are investigated to analyze their streamers' motivations and the user-generated content. Additionally, we collected demographic data (gender and age). More than 7,500 streams by users from the U.S., Germany, and Japan were observed. Main streamer motivations on SLSSs are boredom, socializing, the need to reach a specific group, the need to communicate, and fun. Im...

  12. Positive streamers in air and nitrogen of varying density: experiments on similarity laws

    Energy Technology Data Exchange (ETDEWEB)

    Briels, T M P; Van Veldhuizen, E M; Ebert, U [Department of Applied Physics, Technische Universiteit Eindhoven, P O Box 513, 5600 MB Eindhoven (Netherlands)], E-mail: ebert@cwi.nl, E-mail: e.m.v.veldhuizen@tue.nl

    2008-12-07

    Positive streamers in ambient air at pressures from 0.013 to 1 bar are investigated experimentally. The voltage applied to the anode needle ranges from 5 to 45 kV, the discharge gap from 1 to 16 cm. Using a 'slow' voltage rise time of 100-180 ns, the streamers are intentionally kept thin. For each pressure p, we find a minimal diameter d{sub min}. To test whether streamers at different pressures are similar, the minimal streamer diameter d{sub min} is multiplied by its pressure p; we find this product to be well approximated by p {center_dot} d{sub min} = 0.20 {+-} 0.02 mm bar over two decades of air pressure at room temperature. The value also fits diameters of sprite discharges above thunderclouds at an altitude of 80 km when extrapolated to room temperature (as air density rather than pressure determines the physical behaviour). The minimal velocity of streamers in our measurements is approximately 0.1 mm ns{sup -1} = 10{sup 5} m s{sup -1}. The same minimal velocity has been reported for tendrils in sprites. We also investigate the size of the initial ionization cloud at the electrode tip from which the streamers emerge, and the streamer length between branching events. The same quantities are also measured in nitrogen with a purity of approximately 99.9%. We characterize the essential differences with streamers in air and find a minimal diameter of p {center_dot} d{sub min} = 0.12 {+-} 0.02 mm bar in our nitrogen.

  13. Preparation of water-soluble carbon nanotubes using a pulsed streamer discharge in water

    International Nuclear Information System (INIS)

    Imasaka, Kiminobu; Suehiro, Junya; Kanatake, Yusuke; Kato, Yuki; Hara, Masanori

    2006-01-01

    A novel technique for the preparation of water-soluble carbon nanotubes was demonstrated using a pulsed streamer discharge generated in water. The technique involved chemical reactions between radicals generated by the pulsed streamer discharge and carbon nanotubes. The pulsed streamer-treated carbon nanotubes were homogeneously dispersed and well solubilized in water for a month or longer. The mechanism of solubilization of carbon nanotubes by the pulsed streamer discharge is discussed based on FTIR spectroscopy and optical emission spectra measurements. FTIR spectroscopy revealed that -OH groups, which are known to impart a hydrophilic nature to carbon material, were introduced on the carbon nanotube surface. Optical emission spectra from the pulsed streamer plasma showed that highly oxidative O * and H * radicals were generated in water. These results suggest that the functionalization of the carbon nanotube surface by -OH group can be attributed to the O * and H * radicals. An advantage of the proposed method is that there is no need for any chemical agents or additives for solubilization. Chemical agents for solubilization are generated from the water itself by the electrochemical reactions induced by the pulsed streamer discharge

  14. Spectral analysis of the light emitted from streamers in chlorinated alkane and alkene liquids

    International Nuclear Information System (INIS)

    Ingebrigtsen, S; Bonifaci, N; Denat, A; Lesaint, O

    2008-01-01

    We have studied the time-averaged optical emission from fast positive and negative non-breakdown streamers under pulsed divergent field conditions in five chlorocarbon liquids, namely, dichloromethane, 1,2-dichloroethane, tetrachloromethane, trichloroethene and tetrachloroethene. We have accumulated light emitted from the first 10-15 μm trail of a few thousand streamers. We have also briefly studied single breakdown arcs in tetrachloromethane. Atomic lines of hydrogen, chlorine and carbon as well as excited states of C 2 radicals (Swan bands) have been observed, with sufficient resolution for evaluating line and band-shapes. The characteristic broadening, shift and asymmetry of atomic lines varied significantly between the liquids. Differences between the two streamer polarities were comparatively small. Densities of electrons and neutrals in the illuminated phase have been deduced from broadening of atomic lines, atomic excitation temperatures from absolute line intensities and rotational and vibrational temperatures from the Swan bands. The gas densities of the propagating streamers were generally very high (∼10% of critical) and with a high degree of ionization (∼1 per mille ). Dichloromethane and 1,2-dichloroethane produced re-illuminating streamers with densities close to atmospheric conditions, in agreement with a rapid pressure relaxation. Rotational temperatures were high and in the range 2 x 10 3 -6 x 10 3 K for the different liquids. Results can be interpreted to suggest a partial local thermodynamic equilibrium in the streamer plasmas.

  15. Analyses of electron runaway in front of the negative streamer channel

    Science.gov (United States)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.; Neubert, T.; Chanrion, O.

    2017-08-01

    X-ray and γ-ray emissions, observed in correlation with negative leaders of lightning and long sparks of high-voltage laboratory experiments, are conventionally connected with the bremsstrahlung of high-energy runaway electrons (REs). Here we extend a focusing mechanism, analyzed in our previous paper, which allows the electric field to reach magnitudes, required for a generation of significant RE fluxes and associated bremsstrahlung, when the ionization wave propagates in a narrow, ionized channel created by a previous streamer. Under such conditions we compute the production rate of REs per unit streamer length as a function of the streamer velocity and predict that, once a streamer is formed with the electric field capable of producing REs ahead of the streamer front, the ionization induced by the REs is capable of creating an ionized channel that allows for self-sustained propagation of the RE-emitting ionization wave independent of the initial electron concentration. Thus, the streamer coronas of the leaders are probable sources of REs producing the observed high-energy radiation. To prove these predictions, new simulations are planned, which would show explicitly that the preionization in front of the channel via REs will lead to the ionization wave propagation self-consistent with RE generation.

  16. Computational Studies of Positive and Negative Streamers in Bubbles Suspended in Distilled Water

    KAUST Repository

    Sharma, Ashish

    2017-01-05

    We perform computational studies of nanosecond streamers generated in helium bubbles immersed in distilled water under high pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the chemical kinetics of the discharge. We apply positive and negative trigger voltages much higher than the breakdown voltage and study the dynamic characteristics of the resulting discharge. We observe that, for high positive trigger voltages, the streamer moves along the surface of the gas bubble during the initial stages of the discharge. We also find a considerable difference in the evolution of the streamer discharge for positive and negative trigger voltages with more uniform volumetric distribution of species in the streamer channel for negative trigger voltages due to formation of multiple streamers. We also observe that the presence of water vapor does not influence the breakdown voltage of the discharge but greatly affects the composition of dominant species in the trail of the streamer channel.

  17. Flow Analysis of a Rising Crude Oil Micro-Droplet Affected by Attached Microbial Streamers

    Science.gov (United States)

    Amaro, Matthew; White, Andrew; Jalali, Maryam; Sheng, Jian

    2017-11-01

    Microfluidic experiments show bacteria flowing past a pinned crude oil droplet produce microbial aggregates and streamers on the oil-water interface. High speed DIC microscopy at 1000 fps for 1 sec with a sampling interval of 10 min captures the evolving flow and bacterial motility as well as adhesion, aggregation and streamer events. With bacteria as tracers, velocity measurements are acquired with in-house PIV-assisted PTV software. Flow fields with spatial resolution 2.5 μm are measured around an O(100) μm drop in a 700 ×700 μm window. Full budgets of the 2D Navier-Stokes equation are faithfully resolved to determine pressure gradients by performing the balance over a control volume enclosing the droplet. Pressure gradients are integrated over the border of the control region to obtain pressure profiles at the leading and trailing edges. A momentum balance can be used to determine the drag induced by the drop and any attached streamers. Cases with and without streamers and their differing flow features are presented. Additionally streamers produce nonzero curl in the pressure gradient field providing a tool for identifying the position of otherwise invisible streamers. Ongoing experiments and future applications of the tools presented here will be discussed. Funded by GoMRI, NSF, ARO.

  18. Base Information Transport Infrastructure Wired (BITI Wired)

    Science.gov (United States)

    2016-03-01

    2016 Major Automated Information System Annual Report Base Information Transport Infrastructure Wired (BITI Wired) Defense Acquisition Management...Combat Information Transport System program was restructured into two pre-Major Automated Information System (pre-MAIS) components: Information...Major Automated Information System MAIS OE - MAIS Original Estimate MAR – MAIS Annual Report MDA - Milestone Decision Authority MDD - Materiel

  19. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

  20. Tube plug

    International Nuclear Information System (INIS)

    Zafred, P. R.

    1985-01-01

    The tube plug comprises a one piece mechanical plug having one open end and one closed end which is capable of being inserted in a heat exchange tube and internally expanded into contact with the inside surface of the heat exchange tube for preventing flow of a coolant through the heat exchange tube. The tube plug also comprises a groove extending around the outside circumference thereof which has an elastomeric material disposed in the groove for enhancing the seal between the tube plug and the tube

  1. Water Desalination with Wires

    NARCIS (Netherlands)

    Porada, S.; Sales, B.B.; Hamelers, H.V.M.; Biesheuvel, P.M.

    2012-01-01

    We show the significant potential of water desalination using a novel capacitive wire-based technology in which anode/cathode wire pairs are constructed from coating a thin porous carbon electrode layer on top of electrically conducting rods (or wires). By alternately dipping an array of electrode

  2. Gastrostomy Tube (G-Tube)

    Science.gov (United States)

    ... any of these problems: a dislodged tube a blocked or clogged tube any signs of infection (including redness, swelling, or warmth at the tube site; discharge that's yellow, green, or foul-smelling; fever) excessive bleeding or drainage from the tube site severe abdominal pain lasting ...

  3. PS wire chamber

    CERN Multimedia

    1970-01-01

    A wire chamber used at CERN's Proton Synchrotron accelerator in the 1970s. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  4. Effect of wire shape on wire array discharge

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M. [University of Tokushima, Department of Electrical and Electronic Engineering, Tokushima (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto University, Department of Electrical and Computer Engineering, Kumamoto (Japan)

    2001-09-01

    Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

  5. Effect of wire shape on wire array discharge

    International Nuclear Information System (INIS)

    Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M.; Teramoto, Y.; Katsuki, S.; Akiyama, H.

    2001-01-01

    Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

  6. An Atlantic streamer in stratospheric ozone observations and SD-WACCM simulation data

    Science.gov (United States)

    Hocke, Klemens; Schranz, Franziska; Maillard Barras, Eliane; Moreira, Lorena; Kämpfer, Niklaus

    2017-03-01

    Observation and simulation of individual ozone streamers are important for the description and understanding of non-linear transport processes in the middle atmosphere. A sudden increase in mid-stratospheric ozone occurred above central Europe on 4 December 2015. The GROund-based Millimeter-wave Ozone Spectrometer (GROMOS) and the Stratospheric Ozone MOnitoring RAdiometer (SOMORA) in Switzerland measured an ozone enhancement of about 30 % at 34 km altitude (8.3 hPa) from 1 to 4 December. A similar ozone increase is simulated by the Specified Dynamics Whole Atmosphere Community Climate (SD-WACCM) model. Further, the global ozone fields at 34 km altitude (8.3 hPa) from SD-WACCM and the satellite experiment Aura/MLS show a remarkable agreement for the location and timing of an ozone streamer (large-scale tongue-like structure) extending from the subtropics in northern America over the Atlantic to central Europe. This agreement indicates that SD-WACCM can inform us about the wind inside the Atlantic ozone streamer. SD-WACCM shows an eastward wind of about 100 m s-1 inside the Atlantic streamer in the mid-stratosphere. SD-WACCM shows that the Atlantic streamer flows along the edge of the polar vortex. The Atlantic streamer turns southward at an erosion region of the polar vortex located above the Caspian Sea. The spatial distribution of stratospheric water vapour indicates a filament outgoing from this erosion region. The Atlantic streamer, the polar vortex erosion region and the water vapour filament belong to the process of planetary wave breaking in the so-called surf zone of the northern midlatitude winter stratosphere.

  7. Rare-gas dependence of the self-quenching streamer

    International Nuclear Information System (INIS)

    Yoshioka, K.; Hashimoto, M.; Koori, N.; Kumabe, I.; Ohgaki, H.; Matoba, M.

    1989-01-01

    The self-quenching streamer (SQS) mode is understood these days as one of the basic modes of gas counter operation. In the present work, the SQS transition is clearly observed for Ar-, Kr- and Xe-mixtures with CH 4 , C 2 H 6 , C 3 H 8 , isoC 4 H 10 and CO 2 , and for He- and Ne-mixtures with C 2 H 6 , C 3 H 8 and isoC 4 H 10 . For He- and Ne-mixtures with CH 4 or CO 2 , the GM discharge is developed instead of the SQS transition. The avalanche size at the transition voltage decreases, in the order of He-, Ne-, Ar-, Kr- and Xe-mixtures, except for He-mixtures with CH 4 or CO 2 . The mechanisms of the SQS transition proposed by Atac et al. and Zhang have disadvantages in explaining all these results. If the photo-ionization is assumed as in Atac's mechanism, energetic photons whose yield is sufficiently large are needed for the SQS transition. The interaction between metastable states of rare gases proposed by Zhang may be energetically capable of producing electrons for the transition; effects of quenching gas in mixtures cannot be explained by this mechanism. Further investigation is necessary for microscopic processes occurring in the avalanche development. More detailed information is required on the atomic reaction cross sections of photo-ionization, radiative recombination, etc. (N.K.)

  8. Test of the wire ageing induced by radiation for the CMS barrel muon chamber

    CERN Document Server

    Conti, Enrico

    2000-01-01

    We have carried out laboratory test to measure the ageing of a wire tube due to pollutant outgassed by various materials. The tested materials are those used in the muon barrel drift tubes. An X-ray gun irradiated the test tube to accelerate the ageing process. No ageing effect has been measured for a period equivalent to 10 years of operation at LHC.

  9. A new route to process diamond wires

    Directory of Open Access Journals (Sweden)

    Marcello Filgueira

    2003-06-01

    Full Text Available We propose an original route to process diamond wires, denominated In Situ Technology, whose fabrication involves mechanical conformation processes, such as rotary forging, copper tubes restacking, and thermal treatments, such as sintering and recrystallisation of a bronze 4 wt.% diamond composite. Tensile tests were performed, reaching an ultimate tensile strength (UTS of 230 MPa for the diameter of Æ = 1.84 mm. Scanning electron microscopy showed the diamond crystals distribution along the composite rope during its manufacture, as well as the diamond adhesion to the bronze matrix. Cutting tests were carried out with the processed wire, showing a probable performance 4 times higher than the diamond sawing discs, however its probable performance was about 5 to 8 times less than the conventional diamond wires (pearl system due to the low abrasion resistance of the bronze matrix, and low adhesion between the pair bronze-diamond due to the use of not metallised diamond single crystals.

  10. Longitudinal magnetic bistability of electroplated wires

    International Nuclear Information System (INIS)

    Kurlyandskaya, G.V.; Garcia-Miquel, H.; Vazquez, M.; Svalov, A.V.; Vas'kovskiy, V.O.

    2002-01-01

    Fe 20 Ni 74 Co 6 and Fe 20 Ni 64 Co 16 1 μm thick magnetic tubes electroplated onto Cu 98 Be 2 conductive wire have been investigated in as-deposited state, after heat treatment under longitudinal magnetic field for 1 h at 330 deg. C, and after rf-sputtering deposition of the additional 2 μm Fe 19 Ni 81 layer. Heat treatments and an additional layer deposition modify the shape of hysteresis loops. Magnetically bistable behaviour, observed after the field annealing at a temperature of 330 deg. C, is studied as a function of the length of the samples. This is the first report by our knowledge on the bistable behaviour of the electroplated wires. The bistability of these wires is promising for applications such as tagging or pulse generator applications

  11. Properties of stabilized MgB2 composite wire with Ti barrier

    International Nuclear Information System (INIS)

    Kovac, P; Husek, I; Melisek, T; Holubek, T

    2007-01-01

    Stabilized four-filament in situ MgB 2 /Ti/Cu/Monel composite wire was produced by the rectangular wire-in-tube (RWIT) technique. 10 wt% of nanosize SiC was added into the Mg-B powder mixture, which was packed into the Ti/Cu and Monel tubes, respectively. The assembled composite was two-axially rolled into wire and/or tape form and sintered at temperatures of 650-850 deg. C/0.5 h. Stabilized MgB 2 wire with Ti barrier is studied in terms of field-dependent transport critical current density, effects of filament size reduction and thermal stability

  12. A change in humidification system can eliminate endotracheal tube occlusion.

    Science.gov (United States)

    Doyle, Alex; Joshi, Manasi; Frank, Peter; Craven, Thomas; Moondi, Parvez; Young, Peter

    2011-12-01

    Inadequate airway humidification can result in endotracheal tube occlusion. There is evidence that heat and moisture exchangers (HMEs) are more prone to endotracheal tube occlusion than heated humidifiers (HHs) that contain a heated wire circuit. We aimed to compare the incidence of endotracheal tube occlusion while introducing a new dual-heated wire circuit HH in place of an established hydrophobic HME. This was a prospective observational study. All patients who required intubation were included in our analysis. Univariate statistical analysis was performed using a Fisher exact test. P humidification exclusively by HH. In the subsequent 18-month period, there were no further episodes of endotracheal tube occlusion. Our study demonstrates that there is a significant increase in the incidence of endotracheal tube occlusion when using a hydrophobic HME compared with an HH and that using a dual-heated wire circuit HH can eliminate endotracheal tube occlusion. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Multi-source waveform inversion of marine streamer data using the normalized wavefield

    KAUST Repository

    Choi, Yun Seok

    2012-01-01

    Even though the encoded multi-source approach dramatically reduces the computational cost of waveform inversion, it is generally not applicable to marine streamer data. This is because the simultaneous-sources modeled data cannot be muted to comply with the configuration of the marine streamer data, which causes differences in the number of stacked-traces, or energy levels, between the modeled and observed data. Since the conventional L2 norm does not account for the difference in energy levels, multi-source inversion based on the conventional L2 norm does not work for marine streamer data. In this study, we propose the L2, approximated L2, and L1 norm using the normalized wavefields for the multi-source waveform inversion of marine streamer data. Since the normalized wavefields mitigate the different energy levels between the observed and modeled wavefields, the multi-source waveform inversion using the normalized wavefields can be applied to marine streamer data. We obtain the gradient of the objective functions using the back-propagation algorithm. To conclude, the gradient of the L2 norm using the normalized wavefields is exactly the same as that of the global correlation norm. In the numerical examples, the new objective functions using the normalized wavefields generate successful results whereas conventional L2 norm does not.

  14. Electron densities and energies of a guided argon streamer in argon and air environments

    International Nuclear Information System (INIS)

    Hübner, S; Hofmann, S; Van Veldhuizen, E M; Bruggeman, P J

    2013-01-01

    In this study we report the temporally and spatially resolved electron densities and mean energies of a guided argon streamer in ambient argon and air obtained by Thomson laser scattering. The plasma is driven by a positive monopolar 3.5 kV pulse, with a pulse width of 500 ns and a frequency of 5 kHz which is synchronized with the high repetition rate laser system. This configuration enables us to use the spatial and temporal stability of the guided streamer to accumulate a multitude of laser/plasma shots by a triple grating spectrometer equipped with an ICCD camera and to determine the electron parameters. We found a strong initial n e -overshoot with a maximum of 7 × 10 19  m −3 and a mean electron energy of 4.5 eV. This maximum is followed by a fast decay toward the streamer channel. Moreover, a 2D distribution of the electron density is obtained which exhibits a peculiar mushroom-like shape of the streamer head with a diameter significantly larger than that of the emission profile. A correlation of the width of the streamer head with the expected pre-ionization channel is found. (paper)

  15. Numerical simulation for production of O and N radicals in an atmospheric-pressure streamer discharge

    International Nuclear Information System (INIS)

    Komuro, Atsushi; Ono, Ryo; Oda, Tetsuji

    2012-01-01

    A streamer discharge model is developed to analyse the characteristics of a pulsed positive streamer discharge in point-to-plane electrodes filled with oxygen-nitrogen mixed gas at room temperature and atmospheric pressure. In this paper we study the mechanisms of O and N radical production in an atmospheric-pressure streamer discharge. To confirm the validity of the simulation model, the discharge emission of light and the discharge current are compared with experimental data at several voltages in gas mixtures with 2-20% oxygen concentrations. The calculated streak picture and the axial distribution of streamer luminous intensity are in good agreement with our previous experimental results. After demonstrating the reliability of the model, we performed a numerical study on radical production by the streamer discharge. The experimentally obtained axial distributions of oxygen radical production in O 2 (20%)/N 2 and nitrogen radical production in O 2 (2%)/N 2 are successfully reproduced in our simulation. For the production of nitrogen radicals, two-step dissociation through the vibrationally excited states is predominant. (paper)

  16. DETECTORS: Vienna - beyond the wire

    International Nuclear Information System (INIS)

    Krammer, Manfred; Regler, Meinhard

    1995-01-01

    In 1986, at the fourth Vienna Wire Chamber Conference, Georges Charpak, the inventor of the multiwire proportional chamber, had confidently announced ''Les funérailles des chambres à fils''. Was this the writing on the wall for the conference series as well as this type of detector technology? The demand for detector innovation, coupled with imaginative thinking on the part of the organizers, have kept the Vienna venue at the forefront of the physics calendar. An additional boost to the success of the series was certainly the Nobel Prize awarded to Georges Charpak in 1992. While the major topic naturally is still wire chambers, alternative technologies are also covered. However in fields like calorimetry or ring imaging Cherenkovs, a sample of only a few prominent detectors were presented, giving some participants the impression of a biased selection. The fact that silicon detectors, electronics and track reconstruction strategies were, with the exception of the invited talks, restricted to poster presentations led to the same conclusion. As a result the organizing committee saw that it will have to revise its brief for the next conference. The conference opened with philosophical thoughts by Nobel Prizewinner Georges Charpak. The first day at Vienna is traditionally devoted to applications of gaseous detectors outside high energy physics. L. Shektman gave an overview of wire chambers for medical imaging. Further applications in medicine and in other fields like biology and space science were described by subsequent speakers. The exciting idea of flying a spectrometer on a balloon to study the fraction of electrons and positrons in cosmic rays attracted a lot of attention. The next day covered wire chambers in general. V. Polychronakos presented applications of cathode strip chambers in muon spectrometers for experiments at CERN's LHC proton-proton detector. Certainly the challenges of LHC for detector development dominated many

  17. Velocity distribution measurement in wire-spaced fuel pin bundle

    International Nuclear Information System (INIS)

    Mizuta, Hiroshi; Ohtake, Toshihide; Uruwashi, Shinichi; Takahashi, Keiichi

    1974-01-01

    Flow distribution measurement was made in the subchannels of a pin bundle in air flow. The present paper is interim because the target of this work is the decision of temperature of the pin surface in contact with wire spacers. The wire-spaced fuel pin bundle used for the experiment consists of 37 simulated fuel pins of stainless steel tubes, 3000 mm in length and 31.6 mm in diameter, which are wound spirally with 6 mm stainless steel wire. The bundle is wrapped with a hexagonal tube, 3500 mm in length and 293 mm in flat-to-flat distance. The bundle is fixed with knock-bar at the entrance of air flow in the hexagonal tube. The pitch of pins in the bundle is 37.6 mm (P/D=1.19) and the wrapping pitch of wire is 1100 mm (H/D=34.8). A pair of arrow-type 5-hole Pitot tubes are used to measure the flow velocity and the direction of air flow in the pin bundle. The measurement of flow distribution was made with the conditions of air flow rate of 0.33 m 3 /sec, air temperature of 45 0 C, and average Reynolds number of 15100 (average air velocity of 20.6 m/sec.). It was found that circular flow existed in the down stream of wire spacers, that axial flow velocity was slower in the subchannels, which contained wire spacers, than in those not affected by the wire, and that the flow angle to the axial velocity at the boundary of subchannels was two thirds smaller than wire wrapping angle. (Tai, I.)

  18. Towards plant wires

    OpenAIRE

    Adamatzky, Andrew

    2014-01-01

    In experimental laboratory studies we evaluate a possibility of making electrical wires from living plants. In scoping experiments we use lettuce seedlings as a prototype model of a plant wire. We approximate an electrical potential transfer function by applying direct current voltage to the lettuce seedlings and recording output voltage. We analyse oscillation frequencies of the output potential and assess noise immunity of the plant wires. Our findings will be used in future designs of self...

  19. Initiation of Positive Streamers near Uncharged Ice Hydrometeors in the Thundercloud Field

    Science.gov (United States)

    Babich, L. P.; Bochkov, E. I.

    2018-05-01

    Since the threshold electric field required for breakdown of air is much higher than the maximum field strength measured in thunderstorm clouds, the problem of lightning initiation still remains unsolved. According to the popular hypothesis, lightning can be initiated by a streamer discharge in the field enhanced near a hydrometeor. To verify the adequacy of this hypothesis, the development of a positive streamer propagating along the thunderstorm electric field in the vicinity of an ice needle at an air pressure corresponding to an altitude of 5 km (which is typical of the lightning initiation conditions) was simulated numerically. The hydrometeor dimensions are determined at which streamers can be initiated at different strengths of the thunderstorm electric field.

  20. Possibilities to improve sensitivity and rendering of detail of streamer chamber track photographs

    Energy Technology Data Exchange (ETDEWEB)

    Baehr, J

    1975-01-01

    Streamer chambers are increasingly used as effective particle detectors in the field of experimental elementary particle physics. The photographic recording of high energy events in streamer chambers is limited by performance of current photographic silver-halide layers. Similar limiting problems occur in other fields as well, e.g., in astronomy, x-ray medicine and photogrammetry; therefore methods have been developed to increase sensitivity and improve the information transfer of the emulsion. In this paper these methods have been classified and summarized under the aspect of their application to streamer image recording. Proposals for further investigations are given. Especially the applicability of these methods, their possibility of combination to large film lengths should be investigated The detective quantum efficiency (DQE) is proposed as criterion to estimate and compare the different methods.

  1. A PIC-MCC code for simulation of streamer propagation in air

    DEFF Research Database (Denmark)

    Chanrion, Olivier Arnaud; Neubert, Torsten

    2008-01-01

    A particle code has been developed to study the distribution and acceleration of electrons in electric discharges in air. The code can follow the evolution of a discharge from the initial stage of a single free electron in a background electric field to the formation of an electron avalanche...... and its transition into a streamer. The code is in 2D axi-symmetric coordinates, allowing quasi 3D simulations during the initial stages of streamer formation. This is important for realistic simulations of problems where space charge fields are essential such as in streamer formation. The charged...... particles are followed in a Cartesian mesh and the electric field is updated with Poisson's equation from the charged particle densities. Collisional processes between electrons and air molecules are simulated with a Monte Carlo technique, according to cross section probabilities. The code also includes...

  2. Simulation of subnanosecond streamers in atmospheric-pressure air: Effects of polarity of applied voltage pulse

    Energy Technology Data Exchange (ETDEWEB)

    Babaeva, N. Yu.; Naidis, G. V. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation)

    2016-08-15

    Results of simulation of subnanosecond streamer propagation in corona gap configuration, obtained in the framework of 2D fluid model, are presented. Effects related with the polarity of a voltage pulse applied to the stressed electrode are discussed. It is argued that these effects (dependence of the discharge current and propagation velocity on the polarity of applied voltage) observed in experiments can be attributed to the difference in initial (preceding the streamer formation) distributions of charged species inside the gap. This difference can be caused by preionization (at negative polarity) of the gas inside the discharge gap by runaway electrons. Calculated streamers have large widths (up to 1 cm) and move with velocities in the range of 10{sup 9}–10{sup 10 }cm s{sup −1}, similar to experimental data.

  3. Photovoltaic Wire, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will investigate a new architecture for photovoltaic devices based on nanotechnology: photovoltaic wire. The...

  4. Charpak hemispherical wire chamber

    CERN Multimedia

    1970-01-01

    pieces. Mesures are of the largest one. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  5. MHD Simulations of the Eruption of Coronal Flux Ropes under Coronal Streamers

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yuhong, E-mail: yfan@ucar.edu [High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Green Drive, Boulder, CO 80301 (United States)

    2017-07-20

    Using three-dimensional magnetohydrodynamic (MHD) simulations, we investigate the eruption of coronal flux ropes underlying coronal streamers and the development of a prominence eruption. We initialize a quasi-steady solution of a coronal helmet streamer, into which we impose at the lower boundary the slow emergence of a part of a twisted magnetic torus. As a result, a quasi-equilibrium flux rope is built up under the streamer. With varying streamer sizes and different lengths and total twists of the flux rope that emerges, we found different scenarios for the evolution from quasi-equilibrium to eruption. In the cases with a broad streamer, the flux rope remains well confined until there is sufficient twist such that it first develops the kink instability and evolves through a sequence of kinked, confined states with increasing height until it eventually develops a “hernia-like” ejective eruption. For significantly twisted flux ropes, prominence condensations form in the dips of the twisted field lines due to runaway radiative cooling. Once formed, the prominence-carrying field becomes significantly non-force-free due to the weight of the prominence, despite having low plasma β . As the flux rope erupts, the prominence erupts, showing substantial draining along the legs of the erupting flux rope. The prominence may not show a kinked morphology even though the flux rope becomes kinked. On the other hand, in the case with a narrow streamer, the flux rope with less than one wind of twist can erupt via the onset of the torus instability.

  6. Experimental Study on Branch and Diffuse Type of Streamers in Leader Restrike of Long Air Gap Discharge

    International Nuclear Information System (INIS)

    Chen She; Zeng Rong; Zhuang Chijie; Zhou Xuan; Ding Yujian

    2016-01-01

    One of the main problems in the Ultra High Voltage (UHV) transmission project is to choose the external insulation distance, which requires a deep understanding of the long air gap discharge mechanism. The leader-streamer propagation is one of most important stages in long air gap discharge. In the conductor-tower lattice configuration, we have measured the voltage, the current on the high voltage side and the electric field in the gap. While the streamer in the leader-streamer system presented a conical or hyperboloid diffuse shape, the clear branch structure streamer in front of the leader was firstly observed by a high speed camera in the experiment. Besides, it is found that the leader velocity, width and injected charge for the branch type streamer are greater than those of a diffuse type. We propose that the phenomenon results from the high humidity, which was 15.5-16.5 g/m 3 in our experiment. (paper)

  7. Development of environmental-friendly wire and cable

    International Nuclear Information System (INIS)

    Ueno, Keiji

    1996-01-01

    The electron beam technology has been used in many industrial fields as a method of conventional polymer modification or optimum processability. The main industrial fields of radiation crosslinking are wire and cable, heat shrinkable tubings, plastic foams, precuring of tires, floppy disk curing, foods packaging films, and so on. The radiation crosslinking of wire and cable was started in 1961 in Japan and 15 wire and cable companies are now using electron beam accelerators for production or R and D. The dominant characteristics of crosslinking of insulation materials are application at high temperature, good oil and chemical resistibility and high mechanical properties. These radiation crosslinking wire and cable are applied widely in electronics equipments and automobiles. Recently, electronics manufacturers have indicated deep concern over the effects on the environment. Wire and cable also are required to be applicable for environmental preservation. (J.P.N.)

  8. 1998 wire development workshop proceedings

    International Nuclear Information System (INIS)

    1998-04-01

    This report consists of vugraphs of the presentations at the conference. The conference was divided into the following sessions: (1) First Generation Wire Development: Status and Issues; (2) First Generation Wire in Pre-Commercial Prototypes; (3) Second Generation Wire Development: Private Sector Progress and Issues; (4) Second Generation Wire Development: Federal Laboratories; and (5) Fundamental Research Issues for HTS Wire Development

  9. 1998 wire development workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This report consists of vugraphs of the presentations at the conference. The conference was divided into the following sessions: (1) First Generation Wire Development: Status and Issues; (2) First Generation Wire in Pre-Commercial Prototypes; (3) Second Generation Wire Development: Private Sector Progress and Issues; (4) Second Generation Wire Development: Federal Laboratories; and (5) Fundamental Research Issues for HTS Wire Development.

  10. Recent developments in wire chamber tracking at SSC

    International Nuclear Information System (INIS)

    Ogren, H.

    1990-01-01

    All of the major SSC proposed detectors use wire chambers in their tracking systems. The feasibility of wire chambers in an SSC detector has now been established by a number of groups planning detectors at SSC. The major advances during the past year in understanding straw tube drift chambers are presented and several innovations in gaseous wire chambers are discussed. The R and D section will concentrate on progress in drift cell design, electronics and signal processing, and engineering aspects of the tracking designs

  11. Time characteristics of a self quenching streamer in the coexistence region

    International Nuclear Information System (INIS)

    Han Jiaxiang; Li Cheng; Xu Zizong; Chen Honfang

    1994-01-01

    Experimental studies on the time correlation between electrical signals in the primary avalanche and optical signals which are emitted in the avalanches of the limited proportional mode and the self quenching streamer (SQS) mode have demonstrated that there exists a weak optical emission which is almost simultaneous with the limited proportional avalanche, that a streamer pulse in the SQS mode has a few nanoseconds delay relative to the primary avalanche, and that the spread of the delay (FWHM) is also a few nanoseconds. ((orig.))

  12. The differences between storms driven by helmet streamer CIRs and storms driven by pseudostreamer CIRs

    OpenAIRE

    Borovsky, Joseph E.; Denton, Michael

    2013-01-01

    A corotating interaction region (CIR) is formed when fast coronal hole origin solar wind overtakes slow solar wind and forms a region of compressed plasma and magnetic field. The slow wind upstream of the coronal hole fast wind can be either of helmet streamer origin or pseudostreamer origin. For a collection of 125 CIR-driven geomagnetic storms, the slow wind ahead of each CIR is examined; for those storm not containing ejecta, each CIR is categorized as a helmet streamer CIR (74 of the 125 ...

  13. The FINUDA straw tube detector

    CERN Document Server

    Zia, A; Bertani, M; Bianco, S; Fabbri, Franco Luigi; Gianotti, P; Giardoni, M; Lucherini, V; Mecozzi, A; Pace, E; Passamonti, L; Qaiser, N; Russo, V; Tomassini, S; Sarwar, S; Serdyouk, V

    2001-01-01

    An array of 2424 2.6- m-long, 15- mm-diameter mylar straw tubes, arranged in two axial and four stereo layers, has been assembled at National Laboratories of Frascati of INFN for the FINUDA experiment. The array covers a cylindrical tracking surface of 18 m sup 2 and provides coordinate measurement in the drift direction and along the wire with a resolution of the order of 100 and 300 mu m, respectively. The array has finished the commissioning phase and tests with cosmic rays are underway. The status straw tubes array and a very preliminary result from cosmic rays test are summarized in this work.

  14. The FINUDA straw tube detector

    International Nuclear Information System (INIS)

    Zia, A.; Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F.L.; Gianotti, P.; Giardoni, M.; Lucherini, V.; Mecozzi, A.; Pace, E.; Passamonti, L.; Qaiser, N.; Russo, V.; Tomassini, S.; Sarwar, S.; Serdyouk, V.

    2001-01-01

    An array of 2424 2.6- m-long, 15- mm-diameter mylar straw tubes, arranged in two axial and four stereo layers, has been assembled at National Laboratories of Frascati of INFN for the FINUDA experiment. The array covers a cylindrical tracking surface of 18 m 2 and provides coordinate measurement in the drift direction and along the wire with a resolution of the order of 100 and 300 μm, respectively. The array has finished the commissioning phase and tests with cosmic rays are underway. The status straw tubes array and a very preliminary result from cosmic rays test are summarized in this work

  15. The FINUDA straw tube detector

    Science.gov (United States)

    Zia, A.; Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Gianotti, P.; Giardoni, M.; Lucherini, V.; Mecozzi, A.; Pace, E.; Passamonti, L.; Qaiser, N.; Russo, V.; Tomassini, S.; Sarwar, S.; Serdyouk, V.

    2001-04-01

    An array of 2424 2.6- m-long, 15- mm-diameter mylar straw tubes, arranged in two axial and four stereo layers, has been assembled at National Laboratories of Frascati of INFN for the FINUDA experiment. The array covers a cylindrical tracking surface of 18 m 2 and provides coordinate measurement in the drift direction and along the wire with a resolution of the order of 100 and 300 μm, respectively. The array has finished the commissioning phase and tests with cosmic rays are underway. The status straw tubes array and a very preliminary result from cosmic rays test are summarized in this work.

  16. Wire Array Photovoltaics

    Science.gov (United States)

    Turner-Evans, Dan

    Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

  17. Commercial and Industrial Wiring.

    Science.gov (United States)

    Kaltwasser, Stan; Flowers, Gary

    This module is the third in a series of three wiring publications, includes additional technical knowledge and applications required for job entry in the commercial and industrial wiring trade. The module contains 15 instructional units that cover the following topics: blueprint reading and load calculations; tools and equipment; service;…

  18. Some characteristics of the digitization pulses from high pressure neon-helium flash tubes

    International Nuclear Information System (INIS)

    Chan, D.S.K.; Leung, S.K.; Ng, L.K.

    1979-01-01

    Characteristics of the digitization output pulses from high pressure neon-helium flash tubes were studied under various operation conditions using square ultra-high voltage pulses. Properties reported by previous workers were compared. Two discharge mechanisms, the Townsend avalanche discharge and the streamer discharge, were observed to occur in sequence in some events. The output waveforms for both discharge mechanisms were studied in detail. The charge induced on a detecting probe was also estimated from the measured data. (Auth.)

  19. Cathode readout with stripped resistive drift tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhiltsov, V.E.

    1995-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. (orig.)

  20. Cathode readout with stripped resistive drift tubes

    Science.gov (United States)

    Bychkov, V. N.; Kekelidze, G. D.; Novikov, E. A.; Peshekhonov, V. D.; Shafranov, M. D.; Zhiltsov, V. E.

    1995-12-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented.

  1. Electrons in the solar corona. Pt. 3. Coronal streamers analysis from balloon-borne coronagraph

    Energy Technology Data Exchange (ETDEWEB)

    Dollfus, A; Mouradian, Z [Observatoire de Paris, Section de Meudon, 92 (France)

    1981-03-01

    During a balloon flight in France on September 13, 1971, at altitude 32 000 m, the solar corona was cinematographed from 2 to 5 Rsub(sun) during 5 hr, with an externally occulted coronagraph. Motions in coronal features, when they occur, exhibit deformations of structures with velocities not exceeding a few 10 km s/sup -1/; several streamers were often involved simultaneously; these variations are compatible with magnetic changes or sudden reorganizations of lines of forces. Intensity and polarization measurements give the electron density with height in the quiet corona above the equator. Electron density gradient for one of the streamers gives a temperature of 1.6 x 10/sup 6/ K and comparisons with the on-board Apollo 16 coronal observation of 31 July, 1971 are compatible with the extension of this temperature up to 25 Rsub(sun). Three-dimensional structures and localizations of the streamers are deduced from combined photometry, polarimetry and ground-based K coronametry. Three of the four coronal streamers analysed have their axis bent with height towards the direction of the solar rotation, as if the upper corona has a rotation slightly faster than the chromosphere.

  2. Numerical simulations and conformal analysis of growing and branching negative discharge streamers

    NARCIS (Netherlands)

    Montijn, C.; Meulenbroek, B.; Ebert, U.; Hundsdorfer, W.

    2005-01-01

    The dynamics of an anode-directed streamer can be described by advection-diffusion equations for the charged particles, including a local field-dependent impact ionization term, and coupled to the Poisson equation for the electric field. We present the results of new simulations that use a local

  3. Spatially hybrid computations for streamer discharges with generic features of pulled fronts: I. Planar fronts

    NARCIS (Netherlands)

    C. Li (Chao); U. M. Ebert (Ute); W. Hundsdorfer (Willem)

    2010-01-01

    textabstractStreamers are the first stage of sparks and lightning; they grow due to a strongly enhanced electric field at their tips: this field is created by a thin curved space charge layer. These multiple scales are already challenging when the electrons are approximated by densities. However,

  4. Experimental Investigation of Pulsed Nanosecond Streamer Discharges for CO2 Reforming

    Science.gov (United States)

    Pachuilo, Michael; Levko, Dima; Raja, Laxminarayan; Varghese, Philip

    2016-09-01

    Rapid global industrialization has led to an increase in atmospheric greenhouse gases, specifically carbon dioxide levels. Plasmas present a great potential for efficient reforming of greenhouse gases. There are several plasma discharges which have been reported for reforming process: dielectric barrier discharges (DBD), microwave discharges, and glide-arcs. Microwave discharges have CO2 conversion energy efficiency of up to 40% at atmospheric conditions, while glide-arcs have 43% and DBD 2-10%. In our study, we analyze a single nanosecond pulsed cathode directed streamer discharge in CO2 at atmospheric pressure and temperature. We have conducted time resolved imaging with spectral bandpass filters of a streamer discharge with an applied negative polarity pulse. The image sequences have been correlated to the applied voltage and current pulses. From the spectral filters we can determine where spatially and temporally excited species are formed. In this talk we report on spectroscopic studies of the discharge and estimate plasma properties such as temperature and density of excited species and electrons. Furthermore, we report on the effects of pulse polarity as well as anodic streamer discharges on the CO2 conversion efficiency. Finally, we will focus on the effects of vibrational excitation on carbon dioxide reforming efficiency for streamer discharges. Our experimental results will be compared with an accompanying plasma computational model studies.

  5. Numerical simulation of positive streamer development in thundercloud field enhanced near raindrops

    DEFF Research Database (Denmark)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

    2016-01-01

    As the threshold field strength for the breakdown in air significantly exceeds the maximum measured thundercloud strength 3 kV/cm/atm, the problem of lightning initiation remains unclear. According to the popular idea, lightning can be initiated from streamer discharges developed in the enhanced...

  6. Pseudo-spectral 3D simulations of streamers with adaptively refined grids

    NARCIS (Netherlands)

    Luque, A.; Ebert, U.; Montijn, C.; Hundsdorfer, W.; Schmidt, J.; Simek, M.; Pekarek, S.; Prukner, V.

    2007-01-01

    A three-dimensional code for the simulation of streamers is introduced. The code is based on a fluid model for oxygen-nitrogen mixtures that includes drift, diffusion and attachement of electrons and creation of new charge carriers through impact ionization and photo-ionization. The electric field

  7. Simulating streamer discharges in 3D with the parallel adaptive Afivo framework

    NARCIS (Netherlands)

    H.J. Teunissen (Jannis); U. M. Ebert (Ute)

    2017-01-01

    htmlabstractWe present an open-source plasma fluid code for 2D, cylindrical and 3D simulations of streamer discharges, based on the Afivo framework that features adaptive mesh refinement, geometric multigrid methods for Poisson's equation, and OpenMP parallelism. We describe the numerical

  8. TEMPERATURE AND EXTREME-ULTRAVIOLET INTENSITY IN A CORONAL PROMINENCE CAVITY AND STREAMER

    Energy Technology Data Exchange (ETDEWEB)

    Kucera, T. A. [NASA/GSFC, Code 671, Greenbelt, MD 20771 (United States); Gibson, S. E.; Schmit, D. J. [HAO/NCAR, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Landi, E. [Department of Atmospheric, Oceanic and Space Science, Space Research Building, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143 (United States); Tripathi, D. [Inter-University Centre for Astronomy and Astrophysics, Post Bag-4, Ganeshkhind, Pune University Campus, Pune 411 007 (India)

    2012-09-20

    We analyze the temperature and EUV line emission of a coronal cavity and surrounding streamer in terms of a morphological forward model. We use a series of iron line ratios observed with the Hinode Extreme-ultraviolet Imaging Spectrograph (EIS) on 2007 August 9 to constrain temperature as a function of altitude in a morphological forward model of the streamer and cavity. We also compare model predictions to the EIS EUV line intensities and polarized brightness (pB) data from the Mauna Loa Solar Observatory (MLSO) Mark 4 K-coronameter. This work builds on earlier analysis using the same model to determine geometry of and density in the same cavity and streamer. The fit to the data with altitude-dependent temperature profiles indicates that both the streamer and cavity have temperatures in the range 1.4-1.7 MK. However, the cavity exhibits substantial substructure such that the altitude-dependent temperature profile is not sufficient to completely model conditions in the cavity. Coronal prominence cavities are structured by magnetism so clues to this structure are to be found in their plasma properties. These temperature substructures are likely related to structures in the cavity magnetic field. Furthermore, we find that the model overestimates the EUV line intensities by a factor of 4-10, without overestimating pB. We discuss this difference in terms of filling factors and uncertainties in density diagnostics and elemental abundances.

  9. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Buntat, Z; Harry, J E; Smith, I R [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

    2003-07-07

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

  10. Loeb's and streamer-based mechanism for negative corona current pulses

    International Nuclear Information System (INIS)

    Vagnerova, L.; Skalny, J.D.; Cermak, M.

    1998-01-01

    The negative point-to-plane corona discharge in electronegative gaseous mixtures is studied experimentally and the basic mechanisms controlling the corona phenomena are discussed. The typical shapes of the current pulse waveforms observed in experiments with the nitrogen-freon mixtures are explained in terms of the theory by Loeb and of the positive-streamer-based model. (J.U.)

  11. Two-dimensional potential and charge distributions of positive surface streamer

    International Nuclear Information System (INIS)

    Tanaka, Daiki; Matsuoka, Shigeyasu; Kumada, Akiko; Hidaka, Kunihiko

    2009-01-01

    Information on the potential and the field profile along a surface discharge is required for quantitatively discussing and clarifying the propagation mechanism. The sensing technique with a Pockels crystal has been developed for directly measuring the potential and electric field distribution on a dielectric material. In this paper, the Pockels sensing system consists of a pulse laser and a CCD camera for measuring the instantaneous two-dimensional potential distribution on a 25.4 mm square area with a 50 μm sampling pitch. The temporal resolution is 3.2 ns which is determined by the pulse width of the laser emission. The transient change in the potential distribution of a positive surface streamer propagating in atmospheric air is measured with this system. The electric field and the charge distributions are also calculated from the measured potential profile. The propagating direction component of the electric field near the tip of the propagating streamer reaches 3 kV mm -1 . When the streamer stops, the potential distribution along a streamer forms an almost linear profile with the distance from the electrode, and its gradient is about 0.5 kV mm -1 .

  12. Application of multi-source waveform inversion to marine streamer data using the global correlation norm

    KAUST Repository

    Choi, Yun Seok

    2012-05-02

    Conventional multi-source waveform inversion using an objective function based on the least-square misfit cannot be applied to marine streamer acquisition data because of inconsistent acquisition geometries between observed and modelled data. To apply the multi-source waveform inversion to marine streamer data, we use the global correlation between observed and modelled data as an alternative objective function. The new residual seismogram derived from the global correlation norm attenuates modelled data not supported by the configuration of observed data and thus, can be applied to multi-source waveform inversion of marine streamer data. We also show that the global correlation norm is theoretically the same as the least-square norm of the normalized wavefield. To efficiently calculate the gradient, our method employs a back-propagation algorithm similar to reverse-time migration based on the adjoint-state of the wave equation. In numerical examples, the multi-source waveform inversion using the global correlation norm results in better inversion results for marine streamer acquisition data than the conventional approach. © 2012 European Association of Geoscientists & Engineers.

  13. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    CERN Document Server

    Buntat, Z; Smith, I R

    2003-01-01

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

  14. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    International Nuclear Information System (INIS)

    Buntat, Z; Harry, J E; Smith, I R

    2003-01-01

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings

  15. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    Science.gov (United States)

    Buntat, Z.; Harry, J. E.; Smith, I. R.

    2003-07-01

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

  16. Positive streamers in air of varying density : experiments on the scaling of the excitation density

    NARCIS (Netherlands)

    Dubrovin, D.; Nijdam, S.; Clevis, T.T.J.; Heijmans, L.C.J.; Ebert, U.; Yair, Y.; Price, C.

    2015-01-01

    Streamers are rapidly extending ionized finger-like structures that dominate the initial breakdown of large gas volumes in the presence of a sufficiently strong electric field. Their macroscopic parameters are described by simple scaling relations, where the densities of electrons and of excited

  17. Measurement of the wire tension and position of the muon detector in the CMS project

    International Nuclear Information System (INIS)

    Niu Weiping

    2004-01-01

    The Large Hadron Collider (LHC) is currently being constructed at CERN including the ATLAS (A Toroidal LHC Apparatus) and CMS. It this report, it is have a sample introduction of CMS Muon detector, the drift tube introduction and chamber construction. The scope of this report covers the drift tube design and technical description; measurement of the wire tension of the Muon detector and the quality control; measurement of the wire position of the Muon detector and the quality control and so on. (authors)

  18. Observations of electric discharge streamer propagation and capillary oscillations on the surface of air bubbles in water

    Energy Technology Data Exchange (ETDEWEB)

    Sommers, B S; Foster, J E [Department of Nuclear Engineering and Radiological Science, University of Michigan, Ann Arbor, MI, 48109 (United States); Babaeva, N Yu; Kushner, Mark J [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, 48109 (United States)

    2011-03-02

    The propagation of electric discharge streamers inside bubbles in liquids is of interest for the remediation of toxins in water and plasma-based surgical instruments. The manner of streamer propagation has an important influence on the production of reactive species that are critical to these applications. Streamer propagation along the surface of electrode-attached bubbles of air in water, previously predicted by numerical simulations, has been experimentally imaged using a fast frame-rate camera. The successive pulsing of the streamer discharge inside the bubbles produced oscillations along the air-water interface. Subsequent streamers were observed to closely follow surface distortions induced by such oscillations. The oscillations likely arise from the non-uniform perturbation of the bubble driven by the electric field of the streamer and were found to be consistent with Kelvin's equation for capillary oscillations. For a narrow range of applied voltage pulse frequencies, the oscillation amplitude increased over several pulse periods indicating, potentially, resonant behaviour. We also observed coupling between bubbles wherein oscillations in a second bubble without an internal discharge were induced by the presence of a streamer in a fixed bubble. (fast track communication)

  19. Recent development of drastically innovative BSCCO wire (DI-BISCCO)

    International Nuclear Information System (INIS)

    Kikuchi, M.; Kato, T.; Ohkura, K.; Ayai, N.; Fujikami, J.; Fujino, K.; Kobayashi, S.; Ueno, E.; Yamazaki, K.; Yamade, S.; Hayashi, K.; Sato, K.; Nagai, T.; Matsui, Y.

    2006-01-01

    Up to this day, Ag-sheathed Bi2223 superconducting wires have been widely investigated and the long wires about 1000 m have been produced by using powder-in-tube (PIT) method on a commercial basis in the various facilities or companies. Although the wires are used for some applications such as HTS cables, magnets, motor and so on, the Bi2223 wires not only require much more improvements of the superconducting properties such as critical current, mechanical properties, but also longer and more uniform wires. Recently, the performances of Bi2223 wires have been drastically improved by using Controlled Over Pressure (CT-OP) sintering process. CT-OP process increased critical current (I c ) by more than 60% at 77 K and self field and improved the mechanical strength by more than 70%. The maximum I c was increased up to 166 A. These drastic improvements were caused by the higher density of Bi2223 filament up to almost 100% and better connectivity of the Bi2223 grains. The dense structure of the Bi2223 filaments prevents the ballooning phenomenon which is caused by the gasification of the trapped liquid nitrogen during temperature rise. Additionally, higher uniformity and higher production yield of long length wire were also achieved by exterminating defects during sintering. These high performance levels in CT-OP wires have contributed commercial level applications. We call as Drastically Innovative BSCCO (DI-BSCCO)

  20. Radially and temporally resolved electric field of positive streamers in air and modelling of the induced plasma chemistry

    Science.gov (United States)

    Hoder, T.; Šimek, M.; Bonaventura, Z.; Prukner, V.; Gordillo-Vázquez, F. J.

    2016-08-01

    The initial stages of transient luminous events (TLEs) occurring in the upper atmosphere of the Earth are, in a certain pressure range, controlled by the streamer mechanism. This paper presents the results of the first laboratory experiments to study the TLE streamer phenomena under conditions close to those of the upper atmosphere. Spectrally and highly spatiotemporally resolved emissions originating from radiative states {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) (second positive system) and \\text{N}2+≤ft({{\\text{B}}2}Σu+\\right) (first negative system) have been recorded from the positive streamer discharge. Periodic ionizing events were generated in a barrier discharge arrangement at a pressure of 4 torr of synthetic air, i.e. simulating the pressure conditions at altitudes of ≃37 km. Employing Abel inversion on the radially scanned streamer emission and a 2D fitting procedure, access was obtained to the local spectral signatures within the over 106  m s-1 fast propagating streamers. The reduced electric field strength distribution within the streamer head was determined from the ratio of the \\text{N}2+/{{\\text{N}}2} band intensities with peak values up to 500 Td and overall duration of about 10 ns. The 2D profiles of the streamer head electric fields were used as an experimentally obtained input for kinetic simulations of the streamer-induced air plasma chemistry. The radial and temporal computed distribution of the ground vibrational levels of the radiative states involved in the radiative transitions analyzed (337.1 nm and 391.5 nm), atomic oxygen, nitrogen, nitric oxide and ozone concentrations are vizualized and discussed in comparison with available models of the streamer phase of Blue Jet discharges in the stratosphere.

  1. Towards plant wires.

    Science.gov (United States)

    Adamatzky, Andrew

    2014-08-01

    In experimental laboratory studies we evaluate a possibility of making electrical wires from living plants. In scoping experiments we use lettuce seedlings as a prototype model of a plant wire. We approximate an electrical potential transfer function by applying direct current voltage to the lettuce seedlings and recording output voltage. We analyse oscillation frequencies of the output potential and assess noise immunity of the plant wires. Our findings will be used in future designs of self-growing wetware circuits and devices, and integration of plant-based electronic components into future and emergent bio-hybrid systems. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. Radio-Frequency Emissions from Streamer Collisions: Implications for High-Energy Processes.

    Science.gov (United States)

    Luque, A.

    2017-12-01

    The production of energetic particles in a discharge corona is possibly linked to the collision of streamers of opposite polarities [Cooray et al. (2009), Kochkin et al. (2012), Østgaard et al. (2016)]. There is also experimental evidence linking it to radio-frequency emissions in the UHF frequency range (300 MHz-3 GHz) [Montanyà et al. (2015), Petersen and Beasley (2014)]. Here we investigate these two links by modeling the radio-frequency emissions emanating from an encounter between two counter-propagating streamers. Our numerical model combines self-consistently a conservative, high-order Finite-Volume scheme for electron transport with a Finite-Difference Time-Domain (FDTD) method for electromagnetic propagation. We also include the most relevant reactions for streamer propagation: impact ionization, dissociative attachment and photo-ionization. Our implementation benefits from massive parallelization by running on a General-Purpose Graphical Processing Unit (GPGPU). With this code we found that streamer encounters emit electromagnetic waves predominantly in the UHF range, supporting the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges. References Cooray, V., et al., J. Atm. Sol.-Terr. Phys., 71, 1890, doi:10.1016/j.jastp.2009.07.010 (2009). Kochkin, P. O., et al., J. Phys. D, 45, 425202, doi: 10.1088/0022-3727/45/42/425202 (2012). Montanyà, J., et al., J. Atm. Sol.-Terr. Phys., 136, 94, doi:10.1016/j.jastp.2015.06.009, (2015). Østgaard, N., et al., J. Geophys. Res. (Atmos.), 121, 2939, doi:10.1002/2015JD024394 (2016). Petersen, D., and W. Beasley, Atmospheric Research, 135, 314, doi:10.1016/j.atmosres.2013.02.006 (2014).

  3. Temperature and EUV Intensity in a Coronal Prominence Cavity and Streamer

    Science.gov (United States)

    Kucera, T. A.; Gibson, S.E.; Schmit, D. J.; Landi, E.; Tripathi, D.

    2012-01-01

    We analyze the temperature and EUV line emission of a coronal cavity and surrounding streamer in terms of a morphological forward model. We use a series of iron line ratios observed with the Hinode Extreme-ultraviolet Imaging Spectrograph (EIS) on 2007 Aug. 9 to constrain temperature as a function of altitude in a morphological forward model of the streamer and cavity. We also compare model prediction of the EIS EUV line intensities and polarized brightness (pB) data from the Mauna Loa Solar Observatory (MLSO) MK4. This work builds on earlier analysis using the same model to determine geometry of and density in the same cavity and streamer. The fit to the data with altitude dependent temperature profiles indicates that both the streamer and cavity have temperatures in the range 1.4-1.7 MK. However, the cavity exhibits substantial substructure such that the altitude dependent temperature profile is not sufficient to completely model conditions in the cavity. Coronal prominence cavities are structured by magnetism so clues to this structure are to be found in their plasma properties. These temperature substructures are likely related to structures in the cavity magnetic field. Furthermore, we find that the model overestimates the line intensities by a factor of 4-10, while overestimating pB data by no more than a factor of 1.4. One possible explanation for this is that there may be a significant amount of material at temperatures outside of the range log T(K) approximately equals 5.8 - 6.7 in both the cavity and the streamer.

  4. 3D streamers simulation in a pin to plane configuration using massively parallel computing

    Science.gov (United States)

    Plewa, J.-M.; Eichwald, O.; Ducasse, O.; Dessante, P.; Jacobs, C.; Renon, N.; Yousfi, M.

    2018-03-01

    This paper concerns the 3D simulation of corona discharge using high performance computing (HPC) managed with the message passing interface (MPI) library. In the field of finite volume methods applied on non-adaptive mesh grids and in the case of a specific 3D dynamic benchmark test devoted to streamer studies, the great efficiency of the iterative R&B SOR and BiCGSTAB methods versus the direct MUMPS method was clearly demonstrated in solving the Poisson equation using HPC resources. The optimization of the parallelization and the resulting scalability was undertaken as a function of the HPC architecture for a number of mesh cells ranging from 8 to 512 million and a number of cores ranging from 20 to 1600. The R&B SOR method remains at least about four times faster than the BiCGSTAB method and requires significantly less memory for all tested situations. The R&B SOR method was then implemented in a 3D MPI parallelized code that solves the classical first order model of an atmospheric pressure corona discharge in air. The 3D code capabilities were tested by following the development of one, two and four coplanar streamers generated by initial plasma spots for 6 ns. The preliminary results obtained allowed us to follow in detail the formation of the tree structure of a corona discharge and the effects of the mutual interactions between the streamers in terms of streamer velocity, trajectory and diameter. The computing time for 64 million of mesh cells distributed over 1000 cores using the MPI procedures is about 30 min ns-1, regardless of the number of streamers.

  5. Laboratory experiments cannot be utilized to justify the action of early streamer emission terminals

    International Nuclear Information System (INIS)

    Becerra, Marley; Cooray, Vernon

    2008-01-01

    The early emission of streamers in laboratory long air gaps under switching impulses has been observed to reduce the time of initiation of leader positive discharges. This fact has been arbitrarily extrapolated by the manufacturers of early streamer emission devices to the case of upward connecting leaders initiated under natural lightning conditions, in support of those non-conventional terminals that claim to perform better than Franklin lightning rods. In order to discuss the physical basis and validity of these claims, a self-consistent model based on the physics of leader discharges is used to simulate the performance of lightning rods in the laboratory and under natural lightning conditions. It is theoretically shown that the initiation of early streamers can indeed lead to the early initiation of self-propagating positive leaders in laboratory long air gaps under switching voltages. However, this is not the case for positive connecting leaders initiated from the same lightning rod under the influence of the electric field produced by a downward moving stepped leader. The time evolution of the development of positive leaders under natural conditions is different from the case in the laboratory, where the leader inception condition is closely dependent upon the initiation of the first streamer burst. Our study shows that the claimed similarity between the performance of lightning rods under switching electric fields applied in the laboratory and under the electric field produced by a descending stepped leader is not justified. Thus, the use of existing laboratory results to validate the performance of the early streamer lightning rods under natural conditions is not justified

  6. The physics of pulsed streamer discharge in high pressure air and applications to engine techonologies

    Science.gov (United States)

    Lin, Yung-Hsu

    The goal of this dissertation is to study high pressure streamers in air and apply it to diesel engine technologies. Nanosecond scale pulsed high voltage discharges in air/fuel mixtures can generate radicals which in turn have been shown to improve combustion efficiency in gasoline fueled internal combustion engines. We are exploring the possibility to extend such transient plasma generation and expected radical species generation to the range of pressures encountered in compression-ignition (diesel) engines having compression ratios of ˜20:1, thereby improving lean burning efficiency and extending the range of lean combustion. At the beginning of this dissertation, research into streamer discharges is reviewed. Then, we conducted experiments of streamer propagation at high pressures, calculated the streamer velocity based on both optical and electrical measurements, and the similarity law was checked by analyzing the streamer velocity as a function of the reduced electric field, E/P. Our results showed that the similarity law is invalid, and an empirical scaling factor, E/√P, is obtained and verified by dimensional analysis. The equation derived from the dimensional analysis will be beneficial to proper electrode and pulse generator design for transient plasma assisted internal engine experiments. Along with the high pressure study, we applied such technique on diesel engine to improve the fuel efficiency and exhaust treatment. We observed a small effect of transient plasma on peak pressure, which implied that transient plasma has the capability to improve the fuel consumption. In addition, the NO can be reduced effectively by the same technique and the energy cost is 30 eV per NO molecule.

  7. Thermosonic wire bonding of IC devices using palladium wire

    International Nuclear Information System (INIS)

    Shze, J.H.; Poh, M.T.; Tan, R.M.

    1996-01-01

    The feasibility of replacing gold wire by palladium wire in thermosonic wire bonding of CMOS and bipolar devices are studied in terms of the manufacturability, physical, electrical and assembly performance. The results that palladium wire is a viable option for bonding the bipolar devices but not the CMOS devices

  8. Wire chambers: Trends and alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Regler, Meinhard

    1992-05-15

    The subtitle of this year's Vienna Wire Chamber Conference - 'Recent Trends and Alternative Techniques' - signalled that it covered a wide range of science and technology. While an opening Vienna talk by wire chamber pioneer Georges Charpak many years ago began 'Les funerailles des chambres a fils (the burial of wire chambers)', the contrary feeling this year was that wire chambers are very much alive!.

  9. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  10. Retrograde Intubation in Temporomandibular Joint Ankylosis-A Double Guide Wire Technique

    Directory of Open Access Journals (Sweden)

    Vitha K Dhulkhed

    2008-01-01

    Full Text Available Intubating a patient with temporomandibular joint ankylosis is always a challenge particularly when fibreoptic laryngo-scope is not available. In a 20-year-old male patient we successfully carried out endotracheal intubation with 7 mm portex cuffed PVC tube with the help of two flexible J tipped guide wires. One guide wire was passed into the airway from cricothyroid puncture site and another from subcricoid site. Both were brought out through the nose. The first guide wire was used for retracting the epiglottis and the second as a guide for passing the endotracheal tube.

  11. Feeding Tubes

    Science.gov (United States)

    ... feeding therapies have been exhausted. Please review product brand and method of placement carefully with your physician ... Total Parenteral Nutrition. Resources: Oley Foundation Feeding Tube Awareness Foundation Children’s Medical Nutrition Alliance APFED’s Educational Webinar ...

  12. Stepwise expansion of a surface dielectric barrier discharge as a result of alternation in formation of streamers and leaders

    International Nuclear Information System (INIS)

    Akishev, Yu; Aponin, G; Balakirev, A; Grushin, M; Petryakov, A; Karal'nik, V; Trushkin, N

    2013-01-01

    Spatial–temporal development of the plasma sheet structure in a surface dielectric barrier discharge (SDBD) powered with a single long pulse of negative polarity is traced. Ambient air and Ar at atmospheric pressure are used as plasma-forming gases. It is found that current regimes and spatial structures occurring at the development of a long-pulsed discharge differ cardinally as compared with those of a short-pulsed SDBD. In the case of long-pulsed SDBDs, the expansion of the barrier area covered by the plasma sheet and seeded with a surface negative charge occurs in a stepwise manner due to cyclic alternation (one after another) in generation of surface streamers and formation of hot surface leaders from the streamers due to streamer–leader transitions. Leaders, in their turn, initiate new streamers, which serve again as precursors for next-step leader formation, and so on. However, the crucial role in surface charge deposition is played not by streamers and leaders but by a diffusive plasma sheet (DPS), which slowly extends from the sides of streamers and leaders. The expansion of the DPS occurs due to the ionization wave propagating from the sides of the streamers and leaders. The difference in spatial structures of a single long-pulsed and a steady-state sin SDBD is studied. In high-frequency sin SDBDs at negative half-cycle there are only leaders and DPS, but there are no streamers. The reason is that there is no necessity for the formation of leaders due to streamer–leader transitions—leaders are formed at the previous cycle and do not decay strongly till the beginning of the next cycle, and they recover themselves without streamers. (paper)

  13. Drift chambers on the basis of Mylar tube blocks

    Science.gov (United States)

    Budagov, Yu.; Chirikov-Zorin, I.; Golovanov, L.; Khazins, D.; Kuritsin, A.; Pukhov, O.; Zhukov, V.

    1993-06-01

    Prototypes of drift chambers constructed of Mylar tube blocks were tested. The purpose of developing tube blocks technology was to create long chambers (up to 3-4 m). Counting and drift characteristics of the chambers for different values of the gas pressure and different diameters of sense wires are presented. The lifetime of the chambers is determined. A photoeffect in the visible spectrum on the surface of the thin film aluminium cathode, which covers the Mylar tubes was observed.

  14. Drift chambers on the basis of Mylar tube blocks

    International Nuclear Information System (INIS)

    Budagov, Yu.; Chirikov-Zorin, I.; Golovanov, L.; Khazins, D.; Kuritsin, A.; Pukhov, U.; Zhukov, V.

    1993-01-01

    Prototypes of drift chambers constructed of Mylar tube blocks were tested. The purpose of developing tube blocks technology was to create chambers (up to 3-4 m). Counting and drift chracteristics of the chambers for different values of the gas pressure and different diameters of sense wires are presented. The lifetime of the chambers is determined. A photoeffect in the visible spectrum on the surface of the thin film aluminium cathode, which covers the Mylar tubes was observed. (orig.)

  15. Feasibility study of an active soft catheter actuated by SMA wires

    Science.gov (United States)

    Konh, Bardia; Karimi, Saeed; Miller, Scott

    2018-03-01

    This study aims to assess the feasibility of using a combination of thin elastomer tubes and SMA wires to develop an active catheter. Cardiac catheters have been widely used in investigational and interventional procedures such as angiography, angioplasty, electro- physiology, and endocardial ablation. The commercial models manually steer inside the patient's body via internally installed pull wires. Active catheters, on the other hand, have the potential to revolutionize surgical procedures because of their computer-controlled and enhanced motion. Shape memory alloys have been used for almost a decade as a trustworthy actuator for biomedical applications. In this work, SMA wires were attached to a small pressurized elastomer tube to realize deflection. The tube was pressurized to maintain a constant stress on the SMA wires. The tip motion via actuation of SMA wires was then measured and reported. The results of this study showed that by adopting an appropriate training process for the SMA wires prior to performing the experiments and adopting an appropriate internal pressure for the elastomer tube, less external loads on SMA wires would be needed for a consistent actuation.

  16. A study on the equivalent electric circuit simulation model of DBD streamer and glow alternate discharge

    International Nuclear Information System (INIS)

    Yao, J; Zhang, Z T; Xu, S J; Yu, Q X; Yu, Z; Zhao, J S

    2013-01-01

    This paper presents a dynamic simulating model of the dielectric barrier discharge (DBD), structured as an equivalent electric circuit of the streamer and glow discharge generated alternately in DBD. The main parameters of DBD have been established by means of analysing the structural characteristics of a single discharge cell. An electrical comprehensive Simulink /MATLAB model was developed in order to reveal the interaction of the adjacent two discharge cell. A series of simulations was carried out in order to estimate the key structural parameters that affect the alternate streamer and glow discharge mode. The comparison results of experimental and simulate indicate that there exists a close similarity of the current waveforms graphic. Therefore, we can grasp a deep understanding mechanism of the dielectric barrier discharge and optimize the plasma reactor.

  17. High voltage pulse system for the streamer chamber supply of the GIBS spectrometer

    International Nuclear Information System (INIS)

    Aksinenko, V.D.; Glagoleva, N.S.; Dement'ev, E.A.; Kaminskij, N.I.; Matyushin, A.T.; Matyushin, V.T.; Rozhnyatovskaya, S.A.; Ryakhovskij, V.N.; Nurgozhin, N.N.; Khusainov, E.K.

    1987-01-01

    Results of development and testing of high voltage pulse system HVPS for the streamer chamber supply of the GIBS spectrometer are presented. HVPS consists of the following basic blocks: nanosecond pulse high voltage generator, high voltage charging supply, trigger generator, chamber parameter control devices, gas-oil vacuuming supply systems, auxiliary and fire-prevention devices. The system blocks are described. Experimental results of HVPC testing are presented. HVPC provides a reliable (10 5 operations) of streamer chamber supply with high voltage pulse parameters: amplitude - 500 kV, amplitude instability (0.5-1.5)%, pulse duration - 12 ns, delay time - 500 ns, delay instability (2.5-5)%, mean frequency of output a signals - 0.1 Hz

  18. Multisource full waveform inversion of marine streamer data with frequency selection

    KAUST Repository

    Huang, Yunsong; Schuster, Gerard T.

    2013-01-01

    Multisource migration with frequency selection is now extended to multisource full waveform inversion (FWI) of supergathers for marine streamer data. There are three advantages of this approach compared to conventional FWI for marine streamer data. 1. The multisource FWI method with frequency selection is computationally more efficient than conventional FWI. 2. A supergather requires more than an order of magnitude less storage than the the original data. 3. Frequency selection overcomes the acquisition mismatch between the observed data and the simulated multisource supergathers for marine data. This mismatch problem has prevented the efficient application of FWI to marine geometries in the space-time domain. Preliminary result of applying multisource FWI with frequency selection to a synthetic marine data set suggests it is at least four times more efficient than standard FWI.

  19. OBSERVATIONS OF A HYBRID DOUBLE-STREAMER/PSEUDOSTREAMER IN THE SOLAR CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Rachmeler, L. A.; Seaton, D. B. [Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Brussels (Belgium); Platten, S. J. [School of Mathematics and Statistics, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS (United Kingdom); Bethge, C. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg (Germany); Yeates, A. R., E-mail: rachmeler@oma.be [Department of Mathematical Sciences, Durham University, Science Laboratories, South Road, Durham DH1 3LE (United Kingdom)

    2014-05-20

    We report on the first observation of a single hybrid magnetic structure that contains both a pseudostreamer and a double streamer. This structure was originally observed by the SWAP instrument on board the PROBA2 satellite between 2013 May 5 and 10. It consists of a pair of filament channels near the south pole of the Sun. On the western edge of the structure, the magnetic morphology above the filaments is that of a side-by-side double streamer, with open field between the two channels. On the eastern edge, the magnetic morphology is that of a coronal pseudostreamer without the central open field. We investigated this structure with multiple observations and modeling techniques. We describe the topology and dynamic consequences of such a unified structure.

  20. Steam generator tube extraction

    International Nuclear Information System (INIS)

    Delorme, H.

    1985-05-01

    To enable tube examination on steam generators in service, Framatome has now developed a process for removing sections of steam generator tubes. Tube sections can be removed without being damaged for treating the tube section expanded in the tube sheet

  1. Streamer propagation velocity to anode and to cathode in He, Xe, N2 and SF6

    International Nuclear Information System (INIS)

    Yakovlenko, S.I.

    2004-01-01

    One studied mechanism of ionization propagation in a solid gas associated with propagation of background electrons in heterogenous electric field. The mentioned mechanism does not depend on the sign of field projection on ionization propagation direction. One derived analytical expression for ionization front rate. The mentioned expression conforms well with numerical calculations. Dependence of wave ionization front rate as a function of a field intensity on boundary of streamer for He, Xe, N 2 and SF 6 is tabulated [ru

  2. Streamer-induced emission and spectrometric determination of basic plasma parameters

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan

    2004-01-01

    Roč. 54, suppl.C (2004), C778-C783 ISSN 0011-4626. [Symposium on Plasma Physics and Technology /21./. Praha, 14.06.2004-17.06.2004] R&D Projects: GA AV ČR IAA1043403 Institutional research plan: CEZ:AV0Z2043910 Keywords : optical diagnostics * discharge * streamer Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.292, year: 2004

  3. Pulse shape of the self quenching streamer counter in the coexistence region

    International Nuclear Information System (INIS)

    Chen Hongfang; Han Jiaxiang; Li Cheng; Xu Zizong

    1996-01-01

    The pulse shape of the electrical signal out of the counter operating in the self-quenching streamer (SQS) mode is obtained and the time correlation between the primary avalanche and the SQS avalanche is measured and studied. The results yield more information in the coexistence region about the time jitters in the process of the SQS avalanche than that shown in our last paper. (orig.)

  4. An Extreme-ultraviolet Wave Generating Upward Secondary Waves in a Streamer-like Solar Structure

    Science.gov (United States)

    Zheng, Ruisheng; Chen, Yao; Feng, Shiwei; Wang, Bing; Song, Hongqiang

    2018-05-01

    Extreme-ultraviolet (EUV) waves, spectacular horizontally propagating disturbances in the low solar corona, always trigger horizontal secondary waves (SWs) when they encounter the ambient coronal structure. We present the first example of upward SWs in a streamer-like structure after the passing of an EUV wave. This event occurred on 2017 June 1. The EUV wave happened during a typical solar eruption including a filament eruption, a coronal mass ejection (CME), and a C6.6 flare. The EUV wave was associated with quasi-periodic fast propagating (QFP) wave trains and a type II radio burst that represented the existence of a coronal shock. The EUV wave had a fast initial velocity of ∼1000 km s‑1, comparable to high speeds of the shock and the QFP wave trains. Intriguingly, upward SWs rose slowly (∼80 km s‑1) in the streamer-like structure after the sweeping of the EUV wave. The upward SWs seemed to originate from limb brightenings that were caused by the EUV wave. All of the results show that the EUV wave is a fast-mode magnetohydrodynamic (MHD) shock wave, likely triggered by the flare impulses. We suggest that part of the EUV wave was probably trapped in the closed magnetic fields of the streamer-like structure, and upward SWs possibly resulted from the release of slow-mode trapped waves. It is believed that the interplay of the strong compression of the coronal shock and the configuration of the streamer-like structure is crucial for the formation of upward SWs.

  5. A Series of Jets that Drove Streamer-Puff CMEs from Giant Active Region of 2014

    Science.gov (United States)

    Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

    2016-01-01

    We investigate characteristics of solar coronal jets that originated from active region NOAA 12192 and produced coronal mass ejections (CMEs). This active region produced many non­-jet major flare eruptions (X and M class) that made no CME. A multitude of jets occurred from the southeast edge of the active region, and in contrast to the major-­flare eruptions in the core, six of these jets resulted in CMEs. Our jet observations are from SDO/AIA EUV channels and from Hinode/XRT, and CME observations are from the SOHO/LASCO C2 coronograph. Each jet-­driven CME was relatively slow-­moving (approx. 200 - 300 km/s) compared to most CMEs; had angular width (20deg - 50deg) comparable to that of the streamer base; and was of the "streamer­-puff" variety, whereby a pre-existing streamer was transiently inflated but not removed (blown out) by the passage of the CME. Much of the chromospheric-­temperature plasma of the jets producing the CMEs escaped from the Sun, whereas relatively more of the chromospheric plasma in the non-CME-producing jets fell back to the solar surface. We also found that the CME-producing jets tended to be faster in speed and longer in duration than the non-CME-­producing jets. We expect that the jets result from eruptions of mini-filaments. We further propose that the CMEs are driven by magnetic twist injected into streamer-­base coronal loops when erupting twisted mini-filament field reconnects with the ambient field at the foot of those loops.

  6. A compact multi-wire-layered secondary winding for Tesla transformer.

    Science.gov (United States)

    Zhao, Liang; Su, Jian-Cang; Li, Rui; Wu, Xiao-Long; Xu, Xiu-Dong; Qiu, Xu-Dong; Zeng, Bo; Cheng, Jie; Zhang, Yu; Gao, Peng-Cheng

    2017-05-01

    A compact multi-wire-layered (MWL) secondary winding for a Tesla transformer is put forward. The basic principle of this winding is to wind the metal wire on a polymeric base tube in a multi-layer manner. The tube is tapered and has high electrical strength and high mechanical strength. Concentric-circle grooves perpendicular to the axis of the tube are carved on the surface of the tube to wind the wire. The width of the groove is basically equal to the diameter of the wire so that the metal wire can be fixed in the groove without glue. The depth of the groove is n times of the diameter of the wire to realize the n-layer winding manner. All the concentric-circle grooves are connected via a spiral groove on the surface of the tube to let the wire go through. Compared with the traditional one-wire-layered (OWL) secondary winding for the Tesla transformer, the most conspicuous advantage of the MWL secondary winding is that the latter is compact with only a length of 2/n of the OWL. In addition, the MWL winding has the following advantages: high electrical strength since voids are precluded from the surface of the winding, high mechanical strength because polymer is used as the material of the base tube, and reliable fixation in the Tesla transformer as special mechanical connections are designed. A 2000-turn MWL secondary winding is fabricated with a winding layer of 3 and a total length of 1.0 m. Experiments to test the performance of this winding on a Tesla-type pulse generator are conducted. The results show that this winding can boost the voltage to 1 MV at a repetition rate of 50 Hz reliably for a lifetime longer than 10 4 pulses, which proves the feasibility of the MWL secondary winding.

  7. Wire core reactor for NTP

    International Nuclear Information System (INIS)

    Harty, R.B.

    1991-01-01

    The development of the wire core system for Nuclear Thermal Propulsion (NTP) that took place from 1963 to 1965 is discussed. A wire core consists of a fuel wire with spacer wires. It's an annular flow core having a central control rod. There are actually four of these, with beryllium solid reflectors on both ends and all the way around. Much of the information on the concept is given in viewgraph form. Viewgraphs are presented on design details of the wire core, the engine design, engine weight vs. thrust, a technique used to fabricate the wire fuel element, and axial temperature distribution

  8. Filaments in curved streamlines: rapid formation of Staphylococcus aureus biofilm streamers

    International Nuclear Information System (INIS)

    Kevin Kim, Minyoung; Drescher, Knut; Shun Pak, On; Stone, Howard A; Bassler, Bonnie L

    2014-01-01

    Biofilms are surface-associated conglomerates of bacteria that are highly resistant to antibiotics. These bacterial communities can cause chronic infections in humans by colonizing, for example, medical implants, heart valves, or lungs. Staphylococcus aureus, a notorious human pathogen, causes some of the most common biofilm-related infections. Despite the clinical importance of S. aureus biofilms, it remains mostly unknown how physical effects, in particular flow, and surface structure influence biofilm dynamics. Here we use model microfluidic systems to investigate how environmental factors, such as surface geometry, surface chemistry, and fluid flow affect biofilm development of S. aureus. We discovered that S. aureus rapidly forms flow-induced, filamentous biofilm streamers, and furthermore if surfaces are coated with human blood plasma, streamers appear within minutes and clog the channels more rapidly than if the channels are uncoated. To understand how biofilm streamer filaments reorient in flows with curved streamlines to bridge the distances between corners, we developed a mathematical model based on resistive force theory of slender filaments. Understanding physical aspects of biofilm formation of S. aureus may lead to new approaches for interrupting biofilm formation of this pathogen. (paper)

  9. Laboratory coupling tests for optimum land streamer design over sand dunes surface

    KAUST Repository

    Almalki, Hashim

    2012-02-26

    The cost of data acquisition in land is becoming a major issue as we strive to cover larger areas with seismic surveys at high resolution. Over sand dunes the problem is compounded by the week coupling obtain using geophones, which often forces us to bury the phone. A major challenge is designing such a land streamer system that combines durability, mobility and the required coupling. We share a couple of such designs and discuss the merits behind such designs and test their capability. The testing includes, the level of coupling, mobility and drag over sand surfaces. For specific designs loose sand can accumulate inside the steamer reducing its mobility. On the other hand, poor coupling will attenuate the high frequencies and cause an effective delay in the signal. The weight of the streamer is also an important factor in both mobility and coupling as it adds to the coupling it reduces the mobility of the streamer. We study the impact of weight and base plate surface area on the seismic signal quality, as well as the friction factor of different designs.

  10. Analysis and interpretation of the performance degradation of glass Resistive Plate Chambers operated in streamer mode

    CERN Document Server

    Calcaterra, A; Patteri, P; Piccolo, M; Della Mea, G; Restello, S; Ferri, F; Musella, P; Redaelli, N; Tabarelli de Fatis, T; Tinti, G; Mannocchi, G; Trinchero, G

    2007-01-01

    The long-term stability of Resistive Plate Chambers (RPCs) with glass electrodes was studied for one year with a dedicated test station hosting about 10 m2 of detectors. RPCs were operated in streamer mode with a ternary gas mixture containing argon (27%), isobutane (9%) and tetrafluoroethane (64%). Environmental conditions were kept under control and, in particular, the water pollution in the gas, deemed responsible for the degradation of glass RPC performance, was monitored never to exceed 30 ppm in the exhaust line. Evidence for a substantial aging of the detectors was observed, resulting in a loss of efficiency correlated to an increased rate of spurious streamers. This can be ascribed to the chemical attack of the glass surface by hydrofluoric acid formed in the streamer process, as confirmed by detailed morphological and chemical analyses of the electrode surface. Our results strengthen the indication that the instability of glass RPCs in the long term is related to the use of fluorocarbons as quenching...

  11. Wired to freedom

    DEFF Research Database (Denmark)

    Jepsen, Kim Sune Karrasch; Bertilsson, Margareta

    2017-01-01

    dimension of life science through a notion of public politics adopted from the political theory of John Dewey. We show how cochlear implantation engages different social imaginaries on the collective and individual levels and we suggest that users share an imaginary of being “wired to freedom” that involves...... new access to social life, continuous communicative challenges, common practices, and experiences. In looking at their lives as “wired to freedom,” we hope to promote a wider spectrum of civic participation in the benefit of future life science developments within and beyond the field of Cochlear...

  12. Electric wiring domestic

    CERN Document Server

    Coker, A J

    1992-01-01

    Electric Wiring: Domestic, Tenth Edition, is a clear and reliable guide to the practical aspects of domestic electric wiring. Intended for electrical contractors, installation engineers, wiremen and students, its aim is to provide essential up to date information on modern methods and materials in a simple, clear, and concise manner. The main changes in this edition are those necessary to bring the work into line with the 16th Edition of the Regulations for Electrical Installations issued by the Institution of Electrical Engineers. The book begins by introducing the basic features of domestic

  13. Modern wiring practice

    CERN Document Server

    Steward, W E

    2012-01-01

    Continuously in print since 1952, Modern Wiring Practice has now been fully revised to provide an up-to-date source of reference to building services design and installation in the 21st century. This compact and practical guide addresses wiring systems design and electrical installation together in one volume, creating a comprehensive overview of the whole process for contractors and architects, as well as electricians and other installation engineers. Best practice is incorporated throughout, combining theory and practice with clear and accessible explanation, all

  14. Test of the wire ageing induced by radiation for the CMS barrel muon chambers

    CERN Document Server

    Conti, E

    2001-01-01

    We have carried out laboratory tests to measure the ageing of a wire tube due to pollutants outgassed by various materials. The tested materials are those used in the barrel muon drift tubes of the CMS experiment at LHC. An X-ray gun irradiated the test tube to accelerate the ageing process. No ageing effect has been measured for a period equivalent to 10 years of operation at LHC. (15 refs).

  15. Electric field determination in streamer discharges in air at atmospheric pressure

    International Nuclear Information System (INIS)

    Bonaventura, Z; Bourdon, A; Celestin, S; Pasko, V P

    2011-01-01

    The electric field in streamer discharges in air can be easily determined by the ratio of luminous intensities emitted by N 2 (C 3 Π u ) and N 2 + (B 2 Σ u + ) if the steady-state assumption of the emitting states is fully justified. At ground pressure, the steady-state condition is not fulfilled and it is demonstrated that its direct use to determine the local and instantaneous peak electric field in the streamer head may overestimate this field by a factor of 2. However, when spatial and time-integrated optical emissions (OEs) are considered, the reported results show that it is possible to formulate a correction factor in the framework of the steady-state approximation and to accurately determine the peak electric field in an air discharge at atmospheric pressure. A correction factor is defined as Γ = E s /E e , where E e is the estimated electric field and E s is the true peak electric field in the streamer head. It is shown that this correction stems from (i) the shift between the location of the peak electric field and the maximum excitation rate for N 2 (C 3 Π u ) and N 2 + (B 2 Σ u + ) as proposed by Naidis (2009 Phys. Rev. E 79 057401) and (ii) from the cylindrical geometry of the streamers as stated by Celestin and Pasko (2010 Geophys. Res. Lett. 37 L07804). For instantaneous OEs integrated over the whole radiating plasma volume, a correction factor of Γ ∼ 1.4 has to be used. For time-integrated OEs, the reported results show that the ratio of intensities can be used to derive the electric field in discharges if the time of integration is sufficiently long (i.e. at least longer than the longest characteristic lifetime of excited species) to have the time to collect all the light from the emitting zones of the streamer. For OEs recorded using slits (i.e. a window with a small width but a sufficiently large radial extension to contain the total radial extension of the discharge) the calculated correction factor is Γ ∼ 1.4. As for OEs observed

  16. Wired vs. Wireless.

    Science.gov (United States)

    Fielding, Randall

    2000-01-01

    Presents a debate on which technology will be in tomorrow's classrooms and the pros and cons of wiring classrooms and using a wireless network. Concluding comments address the likelihood, and desirability, of placing computers throughout the entire educational process and what types of computers and capabilities are needed. (GR)

  17. A World without Wires

    Science.gov (United States)

    Panettieri, Joseph C.

    2006-01-01

    The wireless bandwagon is rolling across Mississippi, picking up a fresh load of converts and turning calamity into opportunity. Traditional wired school networks, many of which unraveled during Hurricane Katrina, are giving way to advanced wireless mesh networks that frequently include voice-over-IP (VoIP) capabilities. Vendor funding is helping…

  18. 3D Wire 2015

    DEFF Research Database (Denmark)

    Jordi, Moréton; F, Escribano; J. L., Farias

    This document is a general report on the implementation of gamification in 3D Wire 2015 event. As the second gamification experience in this event, we have delved deeply in the previous objectives (attracting public areas less frequented exhibition in previous years and enhance networking) and have...

  19. Wire chamber conference

    International Nuclear Information System (INIS)

    Bartl, W.; Neuhofer, G.; Regler, M.

    1986-02-01

    This booklet contains program and the abstracts of the papers presented at the conference, most of them dealing with performance testing of various types of wire chambers. The publication of proceedings is planned as a special issue of 'Nuclear instruments and methods' later on. All abstracts are in English. An author index for the book of abstracts is given. (A.N.)

  20. Wire EDM for Refractory Materials

    Science.gov (United States)

    Zellars, G. R.; Harris, F. E.; Lowell, C. E.; Pollman, W. M.; Rys, V. J.; Wills, R. J.

    1982-01-01

    In an attempt to reduce fabrication time and costs, Wire Electrical Discharge Machine (Wire EDM) method was investigated as tool for fabricating matched blade roots and disk slots. Eight high-strength nickel-base superalloys were used. Computer-controlled Wire EDM technique provided high quality surfaces with excellent dimensional tolerances. Wire EDM method offers potential for substantial reductions in fabrication costs for "hard to machine" alloys and electrically conductive materials in specific high-precision applications.

  1. Practical wiring in SI units

    CERN Document Server

    Miller, Henry A

    2013-01-01

    Practical Wiring, Volume 1 is a 13-chapter book that first describes some of the common hand tools used in connection with sheathed wiring. Subsequent chapters discuss the safety in wiring, cables, conductor terminations, insulating sheathed wiring, conductor sizes, and consumer's control equipments. Other chapters center on socket outlets, plugs, lighting subcircuits, lighting accessories, bells, and primary and secondary cells. This book will be very valuable to students involved in this field of interest.

  2. Wire chambers: Trends and alternatives

    International Nuclear Information System (INIS)

    Regler, Meinhard

    1992-01-01

    The subtitle of this year's Vienna Wire Chamber Conference - 'Recent Trends and Alternative Techniques' - signalled that it covered a wide range of science and technology. While an opening Vienna talk by wire chamber pioneer Georges Charpak many years ago began 'Les funerailles des chambres a fils (the burial of wire chambers)', the contrary feeling this year was that wire chambers are very much alive!

  3. Development of Fe-based superconducting wires for liquid-hydrogen level sensors

    Science.gov (United States)

    Ishida, S.; Tsuchiya, Y.; Mawatari, Y.; Eisaki, H.; Nakano, A.; Yoshida, Y.

    2017-07-01

    We developed liquid-hydrogen (LH2) level sensors with Ba(Fe1-x Co x )2As2 superconducting wires (Co-Ba122 wires) as their detection elements. We fabricated Co-Ba122 wires with different Co concentrations x by using the powder-in-tube method. The superconducting transition temperatures of the wires were successfully controlled in the range of 20-25 K by changing x from 0.06 to 0.10. The resistance-temperature curves of the wires exhibited sharp superconducting transitions with widths of 0.5-1.0 K. In addition, we performed an operation test of the Co-Ba122 level sensors with LH2. Close correspondence between the output resistance and the actual LH2 level was observed for a sensor equipped with x = 0.09 wire, demonstrating that this sensor can accurately measure LH2 levels.

  4. Progress in electrical and mechanical properties of rectangular MgB2 wires

    International Nuclear Information System (INIS)

    Kovac, P; Melisek, T; Kopera, L; Husek, I; Polak, M; Kulich, M

    2009-01-01

    Critical current densities and mechanical resistance of MgB 2 wires made by the rectangular wire-in-tube technique (RWIT) have been studied. Wires prepared from different precursor powders and variable sheath materials are compared. The best electrical performance (10 4 A cm -2 at 11.3 T) was measured for the wire with mechanically alloyed powder doped by SiC. While the critical current densities, J c , at 4.2 K are considerably influenced by the powder used, the differences at 20 K are much smaller. Flattened wires show different levels of critical current anisotropy influenced by the precursor powder used. Stress-strain characteristics and critical current degradation are strongly affected by the applied metallic materials and also by the filament's strength. The highest irreversible strain ε irr = 0.55% was measured for Ti/Cu/Monel sheathed wire with filaments from mechanically alloyed powder.

  5. Towards a fluid model for the streamer-to-leader transition in lightning channels.

    Science.gov (United States)

    Malagón, Alejandro; Luque, Alejandro

    2017-04-01

    Electric discharges are a very common phenomenon on Earth's atmosphere. However some of their features are still poorly understood. A sufficiently long electric discharge, such as a lightning channel, propagates along two phases. The first phase is known as "streamer phase" and consists in thin filaments of ionized air that advance due to a high electric field at their tip. The dominant process of ionization is impact ionization, involving electrons and the two major components in the air mass, which are nitrogen and oxygen. In the second phase called "leader phase", the electric current of the streamers has increased the air temperature highly enough so the thermal energy of the molecules present in the air is comparable to the ionization potential of nitrogen and oxygen. The underlying mechanism whereby the streamer-to-leader transition occurs is not precisely known. High-speed observations show that in negative discharges, comprising 90% of cloud-to-ground lightning, this transition is not smooth but mediated by the formation of a "space leader", that is, an isolated hot segment within the streamer region. This space leader is connected to the main leader in a sudden jump and therefore one speaks of a "stepped leader". However, the origin of the space leader is so far unknown. Here we present recent steps in the modeling of the streamer-to-leader transition, which requires coupling fluid mechanics, electromagnetism and air plasma chemistry. We discuss our work towards a model that solves Euler's equations (3 dimensions reduced to 2 by virtue of symmetry) coupled to electron drift using high-resolution finite volume methods for hyperbolic systems [1] implemented in the software package CLAWPACK. The drift of electrons is determined by a self-consistent electric field, which we obtain by solving Poisson's equation by means of off-the-shelf solvers. Our model also includes a selection of chemical reactions that have a relevant effect on the electron density in air

  6. Ear Tubes

    Science.gov (United States)

    ... of the ear drum or eustachian tube, Down Syndrome, cleft palate, and barotrauma (injury to the middle ear caused by a reduction of air pressure, ... specialist) may be warranted if you or your child has experienced repeated ... fluid in the middle ear, barotrauma, or have an anatomic abnormality that ...

  7. Demonstrating diamond wire cutting of the TFTR

    International Nuclear Information System (INIS)

    Rule, K.; Perry, E.; Larson, S.; Viola, M.

    2000-01-01

    The Tokamak Fusion Test Reactor (TFTR) ceased operation in April 1997 and decommissioning commenced in October 1999. The deuterium-tritium fusion experiments resulted in contaminating the vacuum vessel with tritium and activating the materials with 14 Mev neutrons. The total tritium content within the vessel is in excess of 7,000 Curies while dose rates approach 50 mRem/hr. These radiological hazards along with the size of the Tokamak (100 cubic meters) present a unique and challenging task for dismantling. Plasma arc cutting is the current baseline technology for the dismantlement of fission reactors. This technology is typically used because of its faster cutting times. Alternatively, an innovative approach for dismantlement of the TFTR is the use of diamond wire cutting technology. Recent improvements in diamond wire technology have allowed the cutting of carbon steel components such as pipe, plate, and tube bundles in heat exchangers. Some expected benefits of this technology include: significantly reduction in airborne contaminates, reduced personnel exposure, a reduced risk of spread of tritium contamination, and reduced overall costs as compared to using plasma arc cutting. This paper will provide detailed results of the diamond wire cutting demonstration that was completed in September of 1999, on a mock-up of this complex reactor. The results will identify cost, safety, industrial and engineering parameters, and the related performance of each situation

  8. Transport properties of different BSCCO wires

    International Nuclear Information System (INIS)

    Metra, P.; Gherardi, L.; Vellego, G.; Masini, R.; Zannella, S.

    1990-01-01

    This paper reports on two classes of solver sheathed BSCCO wires and laminates were prepared from 2223 (Pb substituted) and 2212 powders, respectively, by the powder in tube method. By suitable heat treatments (sintering and annealing below the melting temperature for 2223, melting + annealing for 2212), we obtained sample wires with Tc of ∼110 and ∼85 K respectively, comparable Jc at 77 K (∼10 3 A/cm 2 ), and dramatically different transport behavior. Measurements of critical current at different temperatures and as a function of applied magnetic field were carried out, to characterize the two classes of samples, together with other electrical testing (e.g. d.c. susceptibility) and structural analyses. The granular nature of the higher Tc BSCCO, qualitatively similar to the one of YBCO, was well documented. The melt-processed material showed no apparent granularity, but very strong field dependence of Jc at high temperature. The effect of mechanical deformation on Jc was also investigated by bending samples on different diameters before and after heat treatment. Wires and tapes with 2212 were found to be bendable on very small diameters before treatment, but also the 2223 filled samples were shown to accept significant deformation before sintering

  9. NA48: Wiring up for Change

    CERN Multimedia

    2001-01-01

    The NA48 Collaboration is rebuilding its drift chambers ready for the experiment to start up again this coming July. An intricate task involving the soldering of over 24,000 wires! The future of the NA48 experiment is coming right down to the wire, that is, the wires which the Collaboration is installing in the clean room of Hall 887 on the Prévessin site. Six days a week, technicians are working in shifts to rebuild the experiment's drift chambers. The original chambers were damaged when a section of a vacuum tube imploded at the end of 1999. A year ago, CERN gave the green light for this essential part of the spectrometer to be rebuilt, so the NA48 experiment, which studies CP violation (see box), still has a bright future ahead of it. Three years of data-taking ahead The NA48 experiment aims to penetrate the secrets of CP (Charge Parity) violation. Charge and parity are two parameters which distinguish a particle from an antiparticle. In other words, an electron possesses a negative electric ...

  10. Demonstrating diamond wire cutting of the TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Rule, K.; Perry, E.; Larson, S.; Viola, M. [and others

    2000-02-24

    The Tokamak Fusion Test Reactor (TFTR) ceased operation in April 1997 and decommissioning commenced in October 1999. The deuterium-tritium fusion experiments resulted in contaminating the vacuum vessel with tritium and activating the materials with 14 Mev neutrons. The total tritium content within the vessel is in excess of 7,000 Curies while dose rates approach 50 mRem/hr. These radiological hazards along with the size of the Tokamak (100 cubic meters) present a unique and challenging task for dismantling. Plasma arc cutting is the current baseline technology for the dismantlement of fission reactors. This technology is typically used because of its faster cutting times. Alternatively, an innovative approach for dismantlement of the TFTR is the use of diamond wire cutting technology. Recent improvements in diamond wire technology have allowed the cutting of carbon steel components such as pipe, plate, and tube bundles in heat exchangers. Some expected benefits of this technology include: significantly reduction in airborne contaminates, reduced personnel exposure, a reduced risk of spread of tritium contamination, and reduced overall costs as compared to using plasma arc cutting. This paper will provide detailed results of the diamond wire cutting demonstration that was completed in September of 1999, on a mock-up of this complex reactor. The results will identify cost, safety, industrial and engineering parameters, and the related performance of each situation.

  11. Radial dependence of surface streamer-channel luminosity: experimental evidence of Gaussian radiative profiles in Ar and N2

    International Nuclear Information System (INIS)

    Šimek, M; Ambrico, P F

    2012-01-01

    Radial distributions of electronically excited species produced during surface streamer propagation were obtained by applying the Abel inverse transform to projected luminosities of single streamers. The streamers were generated in an argon and nitrogen surface coplanar dielectric barrier discharge at atmospheric pressure and their magnified microscopic images were registered with high time resolution. Selected regions of the projected luminosities were processed by the Abel inverse transform procedure based on the Hankel–Fourier method assuming cylindrical symmetry of the streamer channel. Projected as well as Abel-inverted profiles were fitted by Gaussian functions. It is shown that the projected profiles, in addition to the Abel-inverted ones, can be well approximated by the sum of two coaxial Gaussians with two different half-widths and weights. The sharper Gaussian component with higher weight characterizes the radial dependence of the primary cathode-directed streamer-channel luminosity. The second (broader) Gaussian component probably originates either from the pre-breakdown Townsend phase or from the second wave propagating towards the anode. (paper)

  12. Effect of Fe{sub 3}O{sub 4} nanoparticles on positive streamer propagation in transformer oil

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yuzhen, E-mail: yzlv@ncepu.edu.cn [Beijing Key Laboratory of High Voltage and EMC, School of Electric and Electronic Engineering, North China Electric Power University, Beijing, 102206 (China); School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing, 102206 (China); Wang, Qi; Ge, Yang [Beijing Key Laboratory of High Voltage and EMC, School of Electric and Electronic Engineering, North China Electric Power University, Beijing, 102206 (China); Zhou, You [Hunan Province Key Laboratory of Smart Grids Operation and Control, Changsha University of Science and Technology, Changsha, 410076 (China); Li, Chengrong, E-mail: lcr@ncepu.edu.cn; Qi, Bo [Beijing Key Laboratory of High Voltage and EMC, School of Electric and Electronic Engineering, North China Electric Power University, Beijing, 102206 (China); State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206 (China)

    2016-03-15

    Fe{sub 3}O{sub 4} nanoparticles with an average diameter of 10 nm were prepared and used to modify streamer characteristic of transformer oil. It was found that positive streamer propagation velocity in transformer oil-based Fe{sub 3}O{sub 4} nanofluid is greatly reduced by 51% in comparison with that in pure oil. The evolution of streamer shape is also dramatically affected by the presence of nanoparticles, changing from a tree-like shape with sharp branches in pure oil to a bush-like structure with thicker and denser branches in nanofluid. The TSC results reveal that the modification of Fe{sub 3}O{sub 4} nanoparticle can greatly increase the density of shallow trap and change space charge distribution in nanofluid by converting fast electrons into slow electrons via trapping and de-trapping process in shallow traps. These negative space charges induced by nanoparticles greatly alleviate the electric field distortion in front of the positive streamer tip and significantly hinder the propagation of positive streamer.

  13. Numerical simulation of evolution of electron-hole avalanches and streamers in silicon in a uniform electric field

    International Nuclear Information System (INIS)

    Kyuregyan, A. S.

    2010-01-01

    Numerical simulation of origination and evolution of streamers in Si is performed for the first time. It is assumed that an external electric field E 0 is constant and uniform, the avalanche and streamer are axially symmetric, and background electrons and holes are absent. The calculations have been performed in the context of the diffusion-drift approximation with impact and tunneling ionization, Auger recombination, and electron-hole scattering taken into account. The most realistic values of the ionization and recombination rates, diffusion coefficients, and drift mobilities of electrons and holes have been used. It is shown that the features of evolution of avalanches and streamers are generally consistent with the result obtained previously for a hypothetic semiconductor with equal kinetic coefficients for electrons and holes. Asymmetry of these coefficients (mostly, the impact-ionization coefficients) manifests itself only at the initial stage of evolution. However, with time, two exponentially self-similar streamers are formed, differing only in the sign of charge of fronts and directions of their propagation. Empirical dependences of the main parameters of streamers on E 0 in the range of 0.34-0.75 MV/cm have been derived for this most important stage of evolution.

  14. Electron tube

    Science.gov (United States)

    Suyama, Motohiro [Hamamatsu, JP; Fukasawa, Atsuhito [Hamamatsu, JP; Arisaka, Katsushi [Los Angeles, CA; Wang, Hanguo [North Hills, CA

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  15. Reduction of Gas Bubbles and Improved Critical Current Density in Bi-2212 Round Wire by Swaging

    CERN Document Server

    Jiang, J; Huang, Y; Hong, S; Parrell, J; Scheuerlein, C; Di Michiel, M; Ghosh, A; Trociewitz, U; Hellstrom, E; Larbalestier, D

    2013-01-01

    Bi-2212 round wire is made by the powder-in-tube technique. An unavoidable property of powder-in-tube conductors is that there is about 30% void space in the as-drawn wire. We have recently shown that the gas present in the as-drawn Bi-2212 wire agglomerates into large bubbles and that they are presently the most deleterious current limiting mechanism. By densifying short 2212 wires before reaction through cold isostatic pressing (CIPping), the void space was almost removed and the gas bubble density was reduced significantly, resulting in a doubled engineering critical current density (JE) of 810 A/mm2 at 5 T, 4.2 K. Here we report on densifying Bi-2212 wire by swaging, which increased JE (4.2 K, 5 T) from 486 A/mm2 for as-drawn wire to 808 A/mm2 for swaged wire. This result further confirms that enhancing the filament packing density is of great importance for making major JE improvement in this round-wire magnet conductor.

  16. Chest tube insertion

    Science.gov (United States)

    Chest drainage tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... Be careful there are no kinks in your tube. The drainage system should always sit upright and be placed ...

  17. Penetrameter positioner for bore-side radiography of tubes

    International Nuclear Information System (INIS)

    Davis, E.V.; Foster, B.E.

    1983-01-01

    A positioner is provided for placing plaque or wire penetrameters, as used in radiographic inspection, in close proximity with the inner wall of tubing at any desired location along the tubing. The positioner head carrying the penetrameter is inflatable whereby it is positioned in the deflated condition, inflated to place the penetrameter against a weld to be inspected in the tubing wall, and then deflated during removal. If desired, the penetrameter holder may be used to center the radiographic source on the axis of the tube

  18. Vienna Wire Chamber Conference

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    After those of 1978 and 1980, a third Wire Chamber Conference was held from 15-18 February in the Technical University of Vienna. Eight invited speakers covered the field from sophisticated applications in biology and medicine, via software, to the state of the art of gaseous detectors. In some forty other talks the speakers tackled in more detail the topics of gaseous detectors, calorimetry and associated electronics and software

  19. The Micro Wire Detector

    International Nuclear Information System (INIS)

    Adeva, B.; Gomez, F.; Pazos, A.; Pfau, R.; Plo, M.; Rodriguez, J.M.; Vazquez, P.; Labbe, J.C.

    1999-01-01

    We present the performance of a new proportional gas detector. Its geometry consists of a cathode plane with 70x70 μm 2 apertures, crossed by 25 μm anode strips to which it is attached by 50 μm kapton spacers. In the region where the avalanche takes place, the anode strips are suspended in the gas mixture as in a standard wire chamber. This detector exhibits high rate capability and large gains, introducing very little material. (author)

  20. Superconducting magnet wire

    Science.gov (United States)

    Schuller, Ivan K.; Ketterson, John B.; Banerjee, Indrajit

    1986-01-01

    A superconducting tape or wire with an improved critical field is formed of alternating layers of a niobium-containing superconductor such as Nb, NbTi, Nb.sub.3 Sn or Nb.sub.3 Ge with a thickness in the range of about 0.5-1.5 times its coherence length, supported and separated by layers of copper with each copper layer having a thickness in the range of about 170-600 .ANG..

  1. Twisting wire scanner

    Energy Technology Data Exchange (ETDEWEB)

    Gharibyan, V.; Delfs, A.; Koruptchenkov, I.; Noelle, D.; Tiessen, H.; Werner, M.; Wittenburg, K.

    2012-11-15

    A new type of 'two-in-one' wire scanner is proposed. Recent advances in linear motors' technology make it possible to combine translational and rotational movements. This will allow to scan the beam in two perpendicular directions using a single driving motor and a special fork attached to it. Vertical or horizontal mounting will help to escape problems associated with the 45 deg scanners. Test results of the translational part with linear motors is presented.

  2. Twisting wire scanner

    International Nuclear Information System (INIS)

    Gharibyan, V.; Delfs, A.; Koruptchenkov, I.; Noelle, D.; Tiessen, H.; Werner, M.; Wittenburg, K.

    2012-11-01

    A new type of 'two-in-one' wire scanner is proposed. Recent advances in linear motors' technology make it possible to combine translational and rotational movements. This will allow to scan the beam in two perpendicular directions using a single driving motor and a special fork attached to it. Vertical or horizontal mounting will help to escape problems associated with the 45 deg scanners. Test results of the translational part with linear motors is presented.

  3. Wire chamber gases

    International Nuclear Information System (INIS)

    Va'vra, J.

    1992-04-01

    In this paper, we describe new developments in gas mixtures which have occurred during the last 3--4 years. In particular, we discuss new results on the measurement and modeling of electron drift parameters, the modeling of drift chamber resolution, measurements of primary ionization and the choice of gas for applications such as tracking, single electron detection, X-ray detection and visual imaging. In addition, new results are presented on photon feedback, breakdown and wire aging

  4. Improved drainage with active chest tube clearance.

    Science.gov (United States)

    Shiose, Akira; Takaseya, Tohru; Fumoto, Hideyuki; Arakawa, Yoko; Horai, Tetsuya; Boyle, Edward M; Gillinov, A Marc; Fukamachi, Kiyotaka

    2010-05-01

    This study was performed to evaluate the efficacy of a novel chest drainage system. This system employs guide wire-based active chest tube clearance to improve drainage and maintain patency. A 32 Fr chest tube was inserted into pleural cavities of five pigs. On the left, a tube was connected to the chest canister, and on the right, the new system was inserted between the chest tube and chest canister. Acute bleeding was mimicked by periodic infusion of blood. The amount of blood drained from each chest cavity was recorded every 15 min for 2 h. After completion of the procedure, all residual blood and clots in each chest cavity were assessed. The new system remained widely patent, and the amount of drainage achieved with this system (670+/-105 ml) was significantly (P=0.01) higher than that with the standard tube (239+/-131 ml). The amount of retained pleural blood and clots with this system (150+/-107 ml) was significantly (P=0.04) lower than that with the standard tube (571+/-248 ml). In conclusion, a novel chest drainage system with active tube clearance significantly improved drainage without tube manipulations. 2010 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.

  5. Scaleup of powder metallurgy processed Nb-Al multifilamentary wire

    International Nuclear Information System (INIS)

    Thieme, C.; Foner, S.; Otubo, J.; Pourrahimi, S.; Schwartz, B.; Zhang, H.

    1983-01-01

    Power metallurgy processed Nb-Al superconducting wires were fabricated from billets up to 45 mm o.d. with nominal areal reduction ratios, R, up to 2 X 10 5 , Nb powder sizes from 40 to 300 μm from various sources, Al powder sizes from 9 to 75 μm, Al concentrations from 3 to 25 wt % Al and with a wide range of heat treatments. All the compacts used tap density powder in a Cu tube and swaging and/or rod rolling and subsequent wire drawing. Both single strand and bundled wires were made. Overall critical current densities, J /SUB c/, of 2 X 10 4 A/cm 2 at 14 T and 10 4 A/cm 2 at 16 T were achieved for 6 to 8 wt % Al in Nb

  6. Breakdown processes in wire chambers, prevention and rate capability

    International Nuclear Information System (INIS)

    Atac, M.

    1983-01-01

    Breakdowns were optically and electronically observed in drift tubes and drift chambers. They occur at a critical gain for given intensity in a gas mixture when ultraviolet photons are not completely quenched. It was observed that the breakdowns depended critically on average current for a given gas mixture independent of the size of the drift tubes used. Using 4.6% ethyl alcohol vapor mixed into 50/50 argon ethane gas, breakdown are eliminated up to 7 /sub μ/A average current drawn by pulses on a 1 cm section of an anode wire under an intense source. Pulses with an avalanche size of 10 6 electron rates above 10 6 pulses per centimeter per wire may be obtained with the elimination of breakdowns

  7. Breakdown processes in wire chambers, prevention and rate capability

    International Nuclear Information System (INIS)

    Atac, M.

    1982-01-01

    Breakdowns were optically and electronically observed in drift tubes and drift chambers. They occur at a critical gain for given intensity in a gas mixture when ultraviolet photons are not completely quenched. It was observed that the breakdowns depended critically on average current for a given gas mixture independent of the size of the drift tubes used. Using 4.6% ethyl alcohol vapor mixed into 50/50 argon ethane gas, breakdowns are eliminated up to 7 μA average current drawn by pulses on a 1 cm section of an anode wire under an intense source. Pulses with an avalanche size of 10 6 electron rates above 10 6 pulses per centimeter per wire may be obtained with the elimination of breakdowns

  8. Formation of ball streamers at a subnanosecond breakdown of gases at a high pressure in a nonuniform electric field

    Science.gov (United States)

    Beloplotov, D. V.; Tarasenko, V. F.; Sorokin, D. A.; Lomaev, M. I.

    2017-11-01

    The formation of a diffuse discharge plasma at a subnanosecond breakdown of a "cone-plane" gap filled with air, nitrogen, methane, hydrogen, argon, neon, and helium at various pressures has been studied. Nanosecond negative and positive voltage pulses have been applied to the conical electrode. The experimental data on the dynamics of plasma glow at the stage of formation and propagation of a streamer have been obtained with intensified charge-coupled device and streak cameras. It has been found that the formation of ball streamers is observed in all gases and at both polarities. A supershort avalanche electron beam has been detected behind the flat foil electrode in a wide range of pressures in the case of a negatively charged conical electrode. A mechanism of the formation of streamers at breakdown of various gases at high overvoltages has been discussed.

  9. Cathode Readout with Stripped Resistive Drift Tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhil'tsov, V.E.

    1994-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with carbon layer of resistivity 0.5, 30 and 70 k Ohm/sq. The gas mixture used was Ar/CH 4 . Both the anode wire and cathode signals were detected in order to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. 7 refs., 11 figs., 1 tab

  10. Operating properties of straw-tube

    International Nuclear Information System (INIS)

    Alekseev, G.D.; Bonyushkin, Yu.E.; Korytov, A.V.; Malyshev, V.L.

    1990-01-01

    The initial results of the study of thin-wall mylar tubes (called straws) made under the laboratory conditions are presented. The maximal avalanche charge allowing the reliable detector operation is ∼ 10 pC, the spatial accuracy σ x near the anode wire at 3 atm of pure isobutane is ≅ 45 μm. The good separation of charge signals from electrons and X-rays was obtained with the Xe:iso-C 4 H 10 = 94:6 gas mixture. Tubes 5 mm in diameter withstand the pressure of 8-12 atm. 11 refs.; 5 figs

  11. Gas sampling calorimeter studies in proportional, saturated avalanche, and streamer modes

    International Nuclear Information System (INIS)

    Atac, M.; Bedeschi, F.; Yoh, J.; Morse, R.; Procario, M.

    1982-01-01

    Recently, satisfactory new results were obtained at SLAC from gas sampling calorimeters running in the saturated avalanche mode within the energy range of 1.5 to 17.5 GeV. To study the higher energy behavior of this mode, more tests were carried out in the M4 beamline at Fermilab. This paper contains results obtained from the MAC prototype electromagnetic and hadronic calorimeters running in the proportional, saturated avalanche, and the streamer regions for energies between 12 and 150 GeV

  12. SIMUL - a program for the simulation of interactions in the streamer chamber RISK

    International Nuclear Information System (INIS)

    Friebel, W.; Gajewski, J.; Halm, I.

    1976-08-01

    A program for the simulation of interactions in the streamer chamber RISK is described. This program allows first investigations and tests for planning and preparing experiments. In the program the trajectories of all particles taking part in the interaction are computed. Selected points are projected onto film planes serving as measurement points for the use in the geometrical reconstruction. The program is used for testing a geometry program. But it also seems to be very helpful in investigating counter and trigger constellations and in the calculation of counting rates and trigger effectivities. (author)

  13. Dual wire welding torch and method

    Science.gov (United States)

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  14. Right wire in orthodontics: a review

    OpenAIRE

    Ali, Hashim

    2015-01-01

    Quality of orthodontic wire such as stiffness, hardness, resiliency, elasticity and working range are important determinants of the effectivenes of tooth movement. Commonly used types of orthodontic arch wire:1) stainless steel(ss) wire, 2) conventional nickel- titanium (NiTi)alloy wire,3) improved super elastic NiTi- alloy wire( also called low hysteresis(LH)wire), and titanium molybdenum alloy(TMA) wire.

  15. Barium fluoride crystals and self-quenching streamer chambers as a position sensitive gamma-ray detector

    International Nuclear Information System (INIS)

    Salomon, M.; DeMooy, S.; Ruggier, L.

    1985-01-01

    We have studied the possibility of using selfquenching streamer chambers to detect photoelectrons produced by a photoconverter in conjunction with Barium Fluoride scintillators. With the purpose to obtain a high efficiency detector, we attempted to combine a BaF 2 scintillator with a gas chamber operating at large electric fields and a high fraction of quenching gas like self-quenching streamer (SQS) chamber, as the electric fields at the cathode could be made larger than in the proportional mode. Furthermore, previous results indicated that in this mode, part of the large amplification was obtained through strong absorption of uv photons near the anode

  16. photomultiplier tubes

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  17. photomultiplier tube

    CERN Multimedia

    photomultiplier tubes. A device to convert light into an electric signal (the name is often abbreviated to PM). Photomultipliers are used in all detectors based on scintillating material (i.e. based on large numbers of fibres which produce scintillation light at the passage of a charged particle). A photomultiplier consists of 3 main parts: firstly, a photocathode where photons are converted into electrons by the photoelectric effect; secondly, a multiplier chain consisting of a serie of dynodes which multiply the number of electron; finally, an anode, which collects the resulting current.

  18. Evaluation of the effectiveness of light streamer tori-lines and characteristics of bait attacks by seabirds in the western North Pacific.

    Directory of Open Access Journals (Sweden)

    Noriyosi Sato

    Full Text Available To improve the effectiveness of tori-lines it is necessary to evaluate the ability of tori-lines to mitigate seabird bycatch and determine what kind of seabird species gather during line settings, attack the bait and are incidentally caught. We conducted two experiments in the western North Pacific and examined the effectiveness for seabird mitigation of light streamer tori-lines which have no long streamers but many light (short streamers and are mainly used in the North Pacific area. Firstly, the effectiveness of two different types of tori-line (light streamer (1 m and long streamer (up to 7 m tori-line and of two different colors (yellow and red of light streamers for seabird bycatch avoidance was evaluated using 567 sets based on data from 20 offshore surface commercial longliners. No significant difference in the bycatch number between the different tori-line types and streamer colors was found. Secondly, we investigated the characteristics of the seabird bycatch in the North Pacific and the effectiveness of three different types of streamers (light, hybrid and modified light types by detailed observations of seabird attacks using a chartered longline vessel. Although the appearance rate of albatrosses and shearwaters were 40.9% and 27.7%, Laysan albatross was the main seabird species that followed the vessel but shearwaters seldom followed the vessel and did not aggregate during line setting. In all attacks on bait observed during line settings, 81% and 7% were by albatrosses and shearwaters, respectively. In the number of primary attacks by Laysan albatrosses which attacked most aggressively of all seabirds, there were no significant differences among the tori-line types. No individuals of shearwater were caught. The results of both experiments indicated that light streamer tori-lines were as effective as tori-lines with long streamers for mitigating seabird bycatch in the North Pacific.

  19. Review of wire chamber aging

    International Nuclear Information System (INIS)

    Va'Vra, J.

    1986-02-01

    This paper makes an overview of the wire chamber aging problems as a function of various chamber design parameters. It emphasizes the chemistry point of view and many examples are drawn from the plasma chemistry field as a guidance for a possible effort in the wire chamber field. The paper emphasizes the necessity of variable tuning, the importance of purity of the wire chamber environment, as well as it provides a practical list of presently known recommendations. In addition, several models of the wire chamber aging are qualitatively discussed. The paper is based on a summary talk given at the Wire Chamber Aging Workshop held at LBL, Berkeley on January 16-17, 1986. Presented also at Wire Chamber Conference, Vienna, February 25-28, 1986. 74 refs., 18 figs., 11 tabs

  20. Wire communication engineering

    International Nuclear Information System (INIS)

    Son, Byeong Tae

    1997-02-01

    This book describes wire telecommunication engineering/ It is divided into eleven chapter, which deal with Introduction with development of telecommunication, voice and sound wave and communication network, Telegraphy with summary of telegraphy, code of telegraphy, communication speed, morse and telex, Telephone on structure, circuit and image telephone, Traffic on telecommunication traffic, transmission of line about theory, cable line and loaded cable, carrier communication with carrier telegraphy and carrier telephone, optical communication with types, structure, specialty, laser and equipment, DATA, Mobile telecommunication on summary, mobile telephone, radio paging and digital mobile telecommunication, ISDN with channel of ISDN, and service of ISDN, and design of telecommunication.

  1. The Micro Wire Detector

    Energy Technology Data Exchange (ETDEWEB)

    Adeva, B.; Gomez, F.; Pazos, A.; Pfau, R.; Plo, M. E-mail: maximo.plo@cern.ch; Rodriguez, J.M.; Vazquez, P.; Labbe, J.C

    1999-10-11

    We present the performance of a new proportional gas detector. Its geometry consists of a cathode plane with 70x70 {mu}m{sup 2} apertures, crossed by 25 {mu}m anode strips to which it is attached by 50 {mu}m kapton spacers. In the region where the avalanche takes place, the anode strips are suspended in the gas mixture as in a standard wire chamber. This detector exhibits high rate capability and large gains, introducing very little material. (author)

  2. Wiring regulations in brief

    CERN Document Server

    Tricker, Ray

    2012-01-01

    Tired of trawling through the Wiring Regs?Perplexed by Part P?Confused by cables, conductors and circuits?Then look no further! This handy guide provides an on-the-job reference source for Electricians, Designers, Service Engineers, Inspectors, Builders, Students, DIY enthusiastsTopic-based chapters link areas of working practice - such as cables, installations, testing and inspection, special locations - with the specifics of the Regulations themselves. This allows quick and easy identification of the official requirements relating to the situati

  3. Storm-time Convection Dynamics Viewed from Optical Auroras: from Streamer to Patchy Pulsating Aurora

    Science.gov (United States)

    Yang, B.; Donovan, E.; Liang, J.; Grono, E.

    2016-12-01

    In a series of statistical and event studies we have demonstrated that the motion of patches in regions of Patchy Pulsating Aurora (PPA) is very close to if not exactly convection. Thus, 2D maps of PPA motion provides us the opportunity to remote sense magnetospheric convection with relatively high space and time resolution, subject to uncertainties associated with mapping between the ionosphere and magnetosphere. In this study, we use THEMIS ASI aurora observations (streamers and patchy pulsating aurora) combined with SuperDARN convection measurements, Swarm ion drift velocity measurements, and RBSP electric field measurements to explore the convection dynamics in storm time. From 0500 UT to 0600 UT on March 19 2015, convection observations across 5 magnetic local time (MLT) inferred from the motion of PPA patches and SuperDARN measurements show that a westward SAPS (Subauroral Polarized Streams) enhancement occurs after an auroral streamer. This suggests that plasma sheet fast flows can affect the inner magnetospheric convection, and possibly trigger very fast flows in the inner magnetosphere.

  4. Streamer Motives and User-Generated Content on Social Live-Streaming Services

    Directory of Open Access Journals (Sweden)

    Friedlander, Mathilde B.

    2017-03-01

    Full Text Available Three most popular information services, Periscope, Ustream, and YouNow, vicarious for all Social Live-Streaming Services (SLSSs, are investigated to analyze their streamers' motivations and the user-generated content. Additionally, we collected demographic data (gender and age. More than 7,500 streams by users from the U.S., Germany, and Japan were observed. Main streamer motivations on SLSSs are boredom, socializing, the need to reach a specific group, the need to communicate, and fun. Important content categories on all three SLSSs are chatting, sharing information, 24/7, and 'slice of life.' We were able to identify differences between users from the U.S., Germany, and Japan as well as between the users of Periscope, Ustream, and YouNow. The main motive to stream in the U.S. is to reach a specific group, while in Japan it is socializing, and in Germany boredom. The top content category for both, YouNow as well as Periscope, is to chat; on Ustream it is 24/7 (i.e., webcams.

  5. Spatially hybrid computations for streamer discharges with generic features of pulled fronts: I. Planar fronts

    International Nuclear Information System (INIS)

    Li Chao; Ebert, Ute; Hundsdorfer, Willem

    2010-01-01

    Streamers are the first stage of sparks and lightning; they grow due to a strongly enhanced electric field at their tips; this field is created by a thin curved space charge layer. These multiple scales are already challenging when the electrons are approximated by densities. However, electron density fluctuations in the leading edge of the front and non-thermal stretched tails of the electron energy distribution (as a cause of X-ray emissions) require a particle model to follow the electron motion. But present computers cannot deal with all electrons in a fully developed streamer. Therefore, super-particle have to be introduced, which leads to wrong statistics and numerical artifacts. The method of choice is a hybrid computation in space where individual electrons are followed in the region of high electric field and low density while the bulk of the electrons is approximated by densities (or fluids). We here develop the hybrid coupling for planar fronts. First, to obtain a consistent flux at the interface between particle and fluid model in the hybrid computation, the widely used classical fluid model is replaced by an extended fluid model. Then the coupling algorithm and the numerical implementation of the spatially hybrid model are presented in detail, in particular, the position of the model interface and the construction of the buffer region. The method carries generic features of pulled fronts that can be applied to similar problems like large deviations in the leading edge of population fronts, etc.

  6. Stress response of Escherichia coli induced by surface streamer discharge in humid air

    International Nuclear Information System (INIS)

    Doležalová, Eva; Prukner, Václav; Lukeš, Petr; Šimek, Milan

    2016-01-01

    Inactivation of Escherichia coli by means of surface streamer discharge has been investigated to obtain new insights into the key mechanisms involved, with a particular emphasis placed on the microbial response to plasma-induced stress. The surface streamer discharge was produced in coplanar dielectric barrier discharge electrode geometry, and was driven by an amplitude-modulated ac high voltage in humid synthetic air at atmospheric pressure. The response to plasma-induced stress was evaluated by using conventional cultivation, sublethal injury and resazurin assay and the LIVE/DEAD ® BacLight ™ Bacterial Viability kit. Compared to conventional cultivation, the LIVE/DEAD ® test labels bacteria with damaged membranes, while resazurin assay tracks their metabolic activity. Our results clearly demonstrate that the treated bacteria partly lost their ability to grow properly, i.e. they became injured and culturable, or even viable but nonculturable (VBNC). The ability to develop colonies could have been lost due to damage of the bacterial membrane. Damage of the membranes was mainly caused by the lipid peroxidation, evidencing the key role of oxygen reactive species, in particular ozone. We conclude that the conventional cultivation method overestimates the decontamination efficiency of various plasma sources, and must therefore be complemented by alternative techniques capable of resolving viable but nonculturable bacteria. (paper)

  7. STUDENT AWARD FINALIST: Oxygen Pathways in Streamer Discharge for Transient Plasma Ignition

    Science.gov (United States)

    Pendleton, S. J.; Bowman, S.; Singleton, D.; Watrous, J.; Carter, C.; Lempert, W.; Gundersen, M. A.

    2011-10-01

    The use of streamers for the ignition of fuels, also known as transient plasma ignition (TPI), has been shown in a variety of engines to improve combustion through decreased ignition delay, increased lean burn capability and increased energy release relative to conventional spark ignition. The mechanisms behind these improvements, however, remain poorly understood. Temperature measurements by optical emission spectroscopy demonstrate that ignition by TPI is a nonthermal process, and thus is almost entirely dependent on the production and presence of electron impact-created active species in the discharge afterglow. Of particular interest are active oxygen species due to their relatively long lifetimes at high pressures and the pivotal role they play in combustion reactions. In order to elucidate the oxygen pathways, here we report the investigation of the temporal evolution of the populations of atomic oxygen and ozone by use of two-photon absorption laser induced fluorescence (TALIF) and UV absorption, respectively. Experimental results are presented and compared to kinetic modeling of the streamers. Future experiments are proposed to better understand the physics behind TPI. Supported by NSF, AFOSR, NumerEx-ONR, AFRL-WPAFB.

  8. Diagnostics for exploding wires (abstract)

    International Nuclear Information System (INIS)

    Moosman, B.; Bystritskii, V.; Wessel, F.J.; Van Drie, A.

    1999-01-01

    Two diagnostics, capable of imaging fast, high temperature, plasmas were used on exploding wire experiments at UC Irvine. An atmospheric pressure nitrogen laser (λ=337.1 nm) was used to generate simultaneous shadow and shearing interferogram images with a temporal resolution of ∼1 ns and a spatial resolution of 10 μm. An x-ray backlighter imaged the exploding wire 90 degree with respect to the laser and at approximately the same instant in time. The backlighter spatial resolution as determined by geometry and film resolution was 25 μm. Copper wires of diameters (25, 50, and 100 μm) and steel wire d=25 μm were exploded in vacuum (10 -5 Torr) at a maximum current level of 12 kA, by a rectified marx bank at a voltage of 50 kV and a current rise time (quarter period) of 900 ns. Copper wires which were cleaned and then resistively heated under vacuum to incandescence for several hours prior to high current initiation, exhibited greater expansion velocities at peak current than wires which had not been heated prior to discharge. Axial variations on the surface of the wire observed with the laser were found to correlate with bulk axial mass differences from x-ray backlighting. High electron density, measured near the opaque surface of the exploding wire, suggests that much of the current is shunted outward away from the bulk of the wire. copyright 1999 American Institute of Physics

  9. Reliability Criteria for Thick Bonding Wire.

    Science.gov (United States)

    Dagdelen, Turker; Abdel-Rahman, Eihab; Yavuz, Mustafa

    2018-04-17

    Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire.

  10. Reliability Criteria for Thick Bonding Wire

    Directory of Open Access Journals (Sweden)

    Turker Dagdelen

    2018-04-01

    Full Text Available Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al and aluminum coated copper (CucorAl wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire.

  11. Reliability Criteria for Thick Bonding Wire

    Science.gov (United States)

    Yavuz, Mustafa

    2018-01-01

    Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire. PMID:29673194

  12. Stress effects on multifilamentary Nb3Sn wire

    International Nuclear Information System (INIS)

    Bartlett, R.J.; Taylor, R.D.; Thompson, J.D.

    1979-01-01

    Critical current I/sub c/ measurements were obtained on highly stabilized mf Nb 3 Sn wires as a function of heat treatment, stress, temperature, and applied magnetic field. The ratio of the area of the copper to bronze core-niobium tube is about 8, and the filaments are concentrated in the inner 30% of the wire cross section. Values of I/sub c/ and T/sub c/ were determined for samples subjected to a wide range of heat treatments. Diffusion reaction times and temperatures in the ranges 16 to 128 hr and 700 to 750 0 C provided a number of mf Nb 3 Sn wires having similar I/sub c/ characteristics. To some extent the residual compressive loading on the Nb 3 Sn wires varied with the particular heat treatment. This loading arises primarily from the differential contraction of the remaining bronze and the Nb 3 Sn layer when cooled from the reaction temperature to the operating temperature. It was found that, by controlled bending or stretching of the wires, whereby some of the strain in the Nb 3 Sn is relieved, the I/sub c/ at 14 K is increased by as much as 30% and the critical temperature is increased by up to 1 K

  13. Synthesise of Zn O nano wires by direct oxidation method

    International Nuclear Information System (INIS)

    Farbod, M.; Ahangarpour, A.

    2007-01-01

    Zn O is a semiconductor which has a direct and wide energy band which is about 3.37 eV at room temperature. It has various applications from UV lasers, sensitive sensors, solar cells to photo catalysis applications. Zn O has different nano structures such as nanoparticles, nano wires, nano rods, nano tubes and nano belts. The one dimensional Zn O nano structures such as nano wires are very important because of their applications in nano electronics and nano photonics so different methods have been proposed to synthesize them. In this work large scale of Zn O nano wires are produced by direct oxidation a Zn substrate (which was cleaned by chemical methods) in air or oxygen atmosphere at 400 d eg C . Nano wires were investigated by scanning electron microscopy and energy dispersive x-ray measurements. Their diameter is about 30-150 nanometer and their length is about several micrometer. This method which acts without any catalyst is a convenient method to synthesis semiconductor nano wires.

  14. Low-field Instabilities in Nb$_{3}$Sn Multifilamentary Wires the Possible Role of Unreacted Nb

    CERN Document Server

    Devred, A; Celentano, G; Fabbricatore, P; Ferdeghini, C; Greco, M; Gambardella, U

    2007-01-01

    We report an experimental study aiming to demonstrate the not negligible role of unreacted Nb on the magnetic instabilities in superconducting Nb$_{3}$Sn multifilamentary wires, observable through partial flux jumps at magnetic field values below 0.5 T. The analysed wires were recently developed for use as dipoles required in future high-energy proton accelerators and are based on powder-in-tube technology. We studied both unreacted (only involving Nb filaments) and reacted wires, finding flux jump instabilities in both cases when performing magnetic measurements. The results can be interpreted on the basis of the critical state model and are coherent with the intrinsic stability criterion.

  15. Corrosion of Wires on Wooden Wire-Bound Packaging Crates

    Science.gov (United States)

    Samuel L. Zelinka; Stan Lebow

    2015-01-01

    Wire-bound packaging crates are used by the US Army to transport materials. Because these crates may be exposed to harsh environments, they are dip-treated with a wood preservative (biocide treatment). For many years, zinc-naphthenate was the most commonly used preservative for these packaging crates and few corrosion problems with the wires were observed. Recently,...

  16. Improved superconducting magnet wire

    Science.gov (United States)

    Schuller, I.K.; Ketterson, J.B.

    1983-08-16

    This invention is directed to a superconducting tape or wire composed of alternating layers of copper and a niobium-containing superconductor such as niobium of NbTi, Nb/sub 3/Sn or Nb/sub 3/Ge. In general, each layer of the niobium-containing superconductor has a thickness in the range of about 0.05 to 1.5 times its coherence length (which for Nb/sub 3/Si is 41 A) with each copper layer having a thickness in the range of about 170 to 600 A. With the use of very thin layers of the niobium composition having a thickness within the desired range, the critical field (H/sub c/) may be increased by factors of 2 to 4. Also, the thin layers of the superconductor permit the resulting tape or wire to exhibit suitable ductility for winding on a magnet core. These compositions are also characterized by relatively high values of critical temperature and therefore will exhibit a combination of useful properties as superconductors.

  17. Tracking chamber made of 15-mm mylar drift tubes

    Science.gov (United States)

    Kozhin, A.; Borisov, A.; Bozhko, N.; Fakhrutdinov, R.; Plotnikov, I.

    2017-05-01

    We are presenting a drift chamber composed from three layers of mylar drift tubes with outer diameter 15 mm. The pipe is made of strip of mylar film 125 micrometers thick covered with aluminium from the both sides. A strip of mylar is wrapped around the mandrel. Pipe is created by ultrasonic welding. A single drift tube is self-supported structure withstanding 350 g wire tension without supports and internal overpressure. About 400 such tubes were assembled. Design, quality control procedures of the drift tubes are described. Seven chambers were glued from these tubes of 560 mm length. Each chamber consists of 3 layers, 16 tubes per layer. Several chambers were tested with cosmic rays. Results of the tests, counting rate plateau and coordinate resolution are presented.

  18. Tracking chamber made of 15-mm mylar drift tubes

    International Nuclear Information System (INIS)

    Kozhin, A.; Borisov, A.; Bozhko, N.; Fakhrutdinov, R.; Plotnikov, I.

    2017-01-01

    We are presenting a drift chamber composed from three layers of mylar drift tubes with outer diameter 15 mm. The pipe is made of strip of mylar film 125 micrometers thick covered with aluminium from the both sides. A strip of mylar is wrapped around the mandrel. Pipe is created by ultrasonic welding. A single drift tube is self-supported structure withstanding 350 g wire tension without supports and internal overpressure. About 400 such tubes were assembled. Design, quality control procedures of the drift tubes are described. Seven chambers were glued from these tubes of 560 mm length. Each chamber consists of 3 layers, 16 tubes per layer. Several chambers were tested with cosmic rays. Results of the tests, counting rate plateau and coordinate resolution are presented.

  19. The effect of temperature on pulsed positive streamer discharges in air over the range 292 K–1438 K

    Science.gov (United States)

    Ono, Ryo; Ishikawa, Yuta

    2018-05-01

    The effect of temperature on pulsed positive streamer discharges in air is measured by comparing atmospheric-pressure, high-temperature discharges with low-pressure, room-temperature discharges at the same air densities n and discharge voltages. Both discharges have the same reduced electric field E/n, so the differences between the two discharges only depend on the temperature, which is varied from 292 K to 1438 K. Temperature affects the discharge pulse energy most significantly; at 1438 K, the energy of an atmospheric-pressure discharge pulse is approximately 30 times larger than that of the corresponding 20.5 kPa, room-temperature discharge. Temperature also affects the shapes of the streamers when K, but no significant effect is observed for K. There is also no significant temperature effect on the spatially integrated intensity of N2(C–B) emission. However, temperature strongly affects the ratio of the integrated emission intensity to the discharge energy. No effect of the temperature is observed on the propagation velocity of the primary streamer or on the length of the secondary streamer.

  20. Streamer discharge inception in a sub-breakdown electric field from a dielectric body with a frequency dependent dielectric permittivity

    NARCIS (Netherlands)

    A. A. Dubinova (Anna); C. Rutjes (Casper); U. M. Ebert (Ute)

    2015-01-01

    htmlabstractWe study positive streamer inception from the tip of an elongated ice particle. The dielectric permittivity of ice drops from 93 to 3 for electric fields changing on the millisecond timescale [1]. We demonstrate that this effect can be important on the nanosecond time scale of

  1. Tritons for the study of the charge-exchange reactions with the LHE streamer chamber: status and some possibilities

    International Nuclear Information System (INIS)

    Avramenko, S.A.; Belikov, Yu.A.; Golokhvastov, A.I.; Kirillov, A.D.; Khorozov, S.A.; Komolov, L.N.; Lukstin'sh, Yu.; Rukoyatkin, P.A.

    1997-01-01

    The 6 and 9 GeV/c secondary tritons, produced in the 4 He+A→ 3 H+X reaction, were used to study the charge-exchange reactions using a streamer chamber in magnetic field. The triton formation schemes, the beam parameters achieved as well as a way to reduce the beam momentum spread are given in the paper

  2. Comparison of Positive Streamers in Liquid Dielectrics with and without Nanoparticles Simulated with Finite-Element Software

    Directory of Open Access Journals (Sweden)

    Juan Velasco

    2018-02-01

    Full Text Available In this paper, a comparison of positive streamer diffusion propagation is carried out in three configurations of oil transformers: mineral transformer oil, mineral oil with solid dielectric barriers, and a nanofluid. The results have been solved using a finite-element method with a two-dimensional (2D axi-symmetric space dimension selected. Additionally, previous results from other research has been reviewed to compare the results obtained. As expected, it is confirmed that the nanoparticles improve the dielectric properties of the mineral oil. In addition, it is observed that the dielectric solid blocks the propagation of the streamer when it is submerged with a horizontal orientation, thus perpendicular to the applied electric field. The computer used, with four cores (each 3.4 GHz and 16 GB of RAM, was not sufficient for performing the simulations of the models with great precision. However, with these first models, the tendency of the dielectric behavior of the oil was obtained for the three cases in which the streamer was acting through the transformer oil. The simulation of these models, in the future, in a supercomputer with a high performance in terms of RAM memory may allow us to predict, as an example, the best concentration of nanoparticles to retard the streamer inception. Finally, other dielectric issues will be predicted using these models, such as to analyze the advantages and drawbacks of the presence of dielectrics inside the oil transformer.

  3. Twin-tubes: 3D tracking based on the ATLAS muon drift tubes

    International Nuclear Information System (INIS)

    Woudstra, M.; Bobbink, G.J.; Eldik, N. van; Graaf, H. van der; Kluit, P.; Koutsman, A.; Limper, M.; Linde, F.; Massaro, G.; Snuverink, J.; Vreeswijk, M.; Groenstege, H.; Koopstra, J.; Mos, S.; Rewiersma, P.; Timmermans, C.; Dijkema, J.

    2006-01-01

    The Monitored Drift Tubes (MDTs) of the ATLAS Muon Spectrometer have been paired to form so-called twin-tubes to measure the coordinate which runs along the wire direction. This modification endows the MDTs with full 3D track reconstruction using specially designed electronic boards. The performance of the twin-tubes has been measured for an equipped MDT chamber at the ATLAS Muon Cosmic Ray Test Stand at NIKHEF. The efficiency of a twin-tube has been determined to be 99.8%, and the measured resolution 17 cm per hit. By equipping one multilayer consisting of three layers and combining the measurements a resolution of 10 cm has been obtained

  4. Welding wire pressure sensor assembly

    Science.gov (United States)

    Morris, Timothy B. (Inventor); Milly, Peter F., Sr. (Inventor); White, J. Kevin (Inventor)

    1994-01-01

    The present invention relates to a device which is used to monitor the position of a filler wire relative to a base material being welded as the filler wire is added to a welding pool. The device is applicable to automated welding systems wherein nonconsumable electrode arc welding processes are utilized in conjunction with a filler wire which is added to a weld pool created by the electrode arc. The invention senses pressure deviations from a predetermined pressure between the filler wire and the base material, and provides electrical signals responsive to the deviations for actuating control mechanisms in an automatic welding apparatus so as to minimize the pressure deviation and to prevent disengagement of the contact between the filler wire and the base material.

  5. Forming Refractory Insulation On Copper Wire

    Science.gov (United States)

    Setlock, J.; Roberts, G.

    1995-01-01

    Alternative insulating process forms flexible coat of uncured refractory insulating material on copper wire. Coated wire formed into coil or other complex shape. Wire-coating apparatus forms "green" coat on copper wire. After wire coiled, heating converts "green" coat to refractory electrical insulator. When cured to final brittle form, insulating material withstands temperatures above melting temperature of wire. Process used to make coils for motors, solenoids, and other electrical devices to be operated at high temperatures.

  6. Control wiring diagrams

    International Nuclear Information System (INIS)

    McCauley, T.M.; Eskinazi, M.; Henson, L.L.

    1989-01-01

    This paper discusses the changes in electrical document requirements that occur when construction is complete and a generating station starts commercial operation. The needs of operations and maintenance (O and M) personnel are analyzed and contrasted with those of construction to illustrate areas in which the construction documents (drawings, diagrams, and databases) are difficult to use for work at an operating station. The paper discusses the O and M electrical documents that the Arizona Nuclear Power Project (ANPP) believes are most beneficial for the three operating units at Palo Verde; these are control wiring diagrams and an associated document cross-reference list. The benefits offered by these new, station O and M-oriented documents are weighted against the cost of their creation and their impact on drawing maintenance

  7. Eustachian tube patency

    Science.gov (United States)

    Eustachian tube patency refers to how much the eustachian tube is open. The eustachian tube runs between the middle ear and the throat. It controls the pressure behind the eardrum and middle ear space. This helps keep ...

  8. Feeding tube - infants

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007235.htm Feeding tube - infants To use the sharing features on this page, please enable JavaScript. A feeding tube is a small, soft, plastic tube placed ...

  9. Electroplated superconducting wire

    International Nuclear Information System (INIS)

    Peger, C.H.

    1991-01-01

    A hard chromium solution has been considered the least efficient of all plating solutions. This is not exactly true if the correct plating conditions are used. The accepted efficiency is only 12% but that is only true for the parameters that were used long ago to make the determination. At 12% efficiency it would be impossible to plate Superconductor wire. The world's chromium plating shops have been plating at a .001 (.025u) per hour rate since the turn of the century. Shops in the Cleveland, Ohio area have been limiting their plating rate to .006 (152u) since 1935. A few have used .012 (304u) to .030 (762u) per hour for specialized jobs. These figures would indicate the apparent efficiency of the old 100 to 1 chromium, sulfate solution can be higher than 60%. The industry uses a 3 bus bar tank with wide spacing between anode and cathode. This results in high solution resistance and high heat generation and consequently slow plating rates. The Reversible Rack 2 Bus Bar System uses very close anode to cathode spacings. This results in the high plating rates with improved quality deposits. When first asked to chromium plate pure nickel wire reel to reel in long lengths, companies making reel to reel machines were asked if chromium plating was practical. In every case, the answer was it couldn't be done. Gold, tin and zinc plating was being done reel to reel. Using the same parameters that were used to determine a chromium solution efficiency was only 12%, these other metal solutions check out close to 100%

  10. Tube holding system

    International Nuclear Information System (INIS)

    Cunningham, R.C.

    1978-01-01

    A tube holding rig is described for the lateral support of tubes arranged in tight parcels in a heat exchanger. This tube holding rig includes not less than two tube supporting assemblies, with a space between them, located crosswise with respect to the tubes, each supporting assembly comprising a first set of parallel components in contact with the tubes, whilst a second set of components is also in contact with the tubes. These two sets of parts together define apertures through which the tubes pass [fr

  11. Modelling of lightning streamer formation and propagation in wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Holbøll, Joachim; Madsen, Søren Find

    2013-01-01

    of the air termination in enhancing the electric field and attracting the lightning discharge, thus shielding the blade surface and preventing electrical breakdown of the blade material. However, the number and location of the discrete receptors may be difficult to establish, since their performance....... The present paper presents a method to investigate the origin and propagation of streamers from different conductive elements of the blade when exposed to a high electric field. The calculations are performed using dynamic simulations with the finite element method, and the results have been correlated...... with high voltage tests in the laboratory. The algorithms developed are intended to be a new and improved tool for the design of the blade lightning protection system, in particular to assess the effectiveness of the air termination system and the effects of internal conductive materials. The simulation...

  12. Speed of streamers in argon over a flat surface of a dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Sobota, A; Kramer, N J; Van Veldhuizen, E M; Stoffels, W W; Haverlag, M [Eindhoven University of Technology, Department of Applied Physics, PO Box 513, 5600MB Eindhoven (Netherlands); Lebouvier, A [Ecole Polytechnique de l' Universite d' Orleans, 12 rue de Blois, BP 6744, 45067 Orleans Cedex 2 (France); Manders, F [Advanced Development Lighting, Philips Lighting, Mathildelaan 1, 5611 BD, Eindhoven (Netherlands)], E-mail: a.sobota@tue.nl

    2009-01-07

    A pin-pin electrode geometry was used to study the velocities of streamers propagating over a flat dielectric surface and in gas close to the dielectric. The experiments were done in an argon atmosphere, at pressures from 0.1 to 1 bar, with repetitive voltage pulses. The dielectric surface played a noticeable role in discharge ignition and propagation. The average speed of the discharge decreased with higher pressure and lower voltage pulse rise rate. It was higher when the conductive channel between the electrodes was formed over the dielectric, rather than through the gas. Space resolved measurements revealed an increase in velocity of the discharge as it travelled towards the grounded electrode.

  13. The acceleration of electrons at a spherical coronal shock in a streamer-like coronal field

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Xiangliang, E-mail: kongx@sdu.edu.cn; Chen, Yao, E-mail: yaochen@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China); Guo, Fan, E-mail: guofan.ustc@gmail.com [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-03-25

    We study the effect of large-scale coronal magnetic field on the electron acceleration at a spherical coronal shock using a test-particle method. The coronal field is approximated by an analytical solution with a streamer-like magnetic field featured by partially open magnetic field and a current sheet at the equator atop the closed region. It shows that the closed field plays the role of a trapping agency of shock-accelerated electrons, allowing for repetitive reflection and acceleration, therefore can greatly enhance the shock-electron acceleration efficiency. It is found that, with an ad hoc pitch-angle scattering, electron injected in the open field at the shock flank can be accelerated to high energies as well. In addition, if the shock is faster or stronger, a relatively harder electron energy spectrum and a larger maximum energy can be achieved.

  14. Display of a proton-proton interaction as seen in the streamer chamber of NA5

    CERN Multimedia

    CERN PhotoLab

    1979-01-01

    This experiment was performed by the Bari-Cracow-Liverpool-Munich (MPI)-Nijmegen Collaboration using the unseparated H2 beam in the EHN1 hall. The setup consisted of a three-gap streamer chamber (2x1.4x0.72 m3) inside a superconducting vertex magnet, large magnetostrictive spark chambers, proportional chambers and beam defining counters. A large acceptance electron and hadron calorimeter completed the setup. Particles from beam interactions on a target, 36.5 cm long, 2 cm in diameter (for liquid hydrogen) located inside the chamber at its entrance were photographed. Multiplicities, rapidity distributions, and correlations were studied for interactions with a large value for the sum of the transverse momenta.

  15. Speed of streamers in argon over a flat surface of a dielectric

    International Nuclear Information System (INIS)

    Sobota, A; Kramer, N J; Van Veldhuizen, E M; Stoffels, W W; Haverlag, M; Lebouvier, A; Manders, F

    2009-01-01

    A pin-pin electrode geometry was used to study the velocities of streamers propagating over a flat dielectric surface and in gas close to the dielectric. The experiments were done in an argon atmosphere, at pressures from 0.1 to 1 bar, with repetitive voltage pulses. The dielectric surface played a noticeable role in discharge ignition and propagation. The average speed of the discharge decreased with higher pressure and lower voltage pulse rise rate. It was higher when the conductive channel between the electrodes was formed over the dielectric, rather than through the gas. Space resolved measurements revealed an increase in velocity of the discharge as it travelled towards the grounded electrode.

  16. Effect of streamer plasma air purifier on sbs symptoms and performance of office work

    DEFF Research Database (Denmark)

    Zhang, X.J.; Fang, Lei; Wargocki, Pawel

    2011-01-01

    Subjective experiments were conducted to evaluate the effect of a streamer plasma air purifier on perceived air quality, SBS symptoms and performance of office work during 5-hour exposure of 32 recruited subjects in field laboratory in which real materials were used to establishing a realistic...... level of air pollution. Intensity of SBS symptoms were indicated using visual-analogue scales. Subjects’ performance was evaluated with several computer tasks. The results show that operation of the air purifiers improved perceived air quality and reduced the odor intensity of indoor air. Eye dryness...... symptom was found significantly improved when the air purifiers were used but no other SBS symptoms or performance of office work were improved when the air purifiers were in operation compared to the condition when they were off....

  17. Development of (Nb,Ta3Sn multifilamentary superconductor wire for high current applications

    Directory of Open Access Journals (Sweden)

    Durval Rodrigues Jr.

    2000-10-01

    Full Text Available The optimization of the energy generated by a MagnetoHydroDynamic (MHD channel using a superconducting magnet demands the optimization of the magnetic field of the system and of the critical points on the magnet winding. This work must include the development of a high performance superconductor wire suitable for this system. Aiming to the construction of improved performance MHD channel, it was developed a low cost superconductor wire, with the required characteristics. The wire was made using a technology compatible with the assembling steps and heat treatment conditions of the MHD superconducting magnets fabrication. It was used the internal Sn method in Nb-7.5wt%Ta tube to fabricate a 271-filament wire with a diameter of 0.81 mm and a Cu/nonCu ratio of 2.3. The wire was heat treated at 200 °C to diffuse the Sn into the Cu shell, producing bronze, followed by the final reaction at temperatures ranging from 670 °C to 730 °C during 25 to 150 h, to produce (Nb,Ta3Sn. The superconducting wire characterization was made measuring the critical current Ic versus the applied magnetic field in the range of 5 to 20 T, the critical temperature Tc and the residual resistivity ratio (RRR. The wire transported critical currents above those available in commercial superconducting wires. These values of Ic are higher than the expected values for the optimization of the MHD channel.

  18. Development of Ti-sheathed MgB2 wires with high critical current density

    International Nuclear Information System (INIS)

    Liang, G; Fang, H; Hanna, M; Yen, F; Lv, B; Alessandrini, M; Keith, S; Hoyt, C; Tang, Z; Salama, K

    2006-01-01

    Working towards developing lightweight superconducting magnets for future space and other applications, we have successfully fabricated mono-core Ti-sheathed MgB 2 wires by the powder-in-tube method. The wires were characterized by magnetization, electrical resistivity, x-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry measurements. The results indicate that the Ti sheath does not react with the magnesium and boron, and the present wire rolling process can produce MgB 2 wires with a superconducting volume fraction of at least 64% in the core. Using the Bean model, it was found that at 5 K, the magnetic critical current densities, J c , measured in magnetic fields of 0, 5, and 8 T are about 4.2 x 10 5 , 3.6 x 10 4 , and 1.4 x 10 4 A cm -2 , respectively. At 20 K and 0 T, the magnetic J c is about 2.4 x 10 5 A cm -2 . These results show that at zero and low fields, the values of the magnetic J c for Ti-sheathed MgB 2 wires are comparable with the best results available for the Fe-sheathed MgB 2 wires. At high fields, however, the J c for Ti-sheathed MgB 2 wires appears higher than that for the Fe-sheathed MgB 2 wires

  19. Investigation of surface treatment of conductive wire in cylindrical atmospheric pressure plasmas

    International Nuclear Information System (INIS)

    Ye Rubin; Kagohashi, Tsutomu; Zheng Wei

    2009-01-01

    Polyethylene insulated electric wire was treated in He and Ar dielectric barrier discharge atmospheric pressure plasmas generated in a quartz tube wound with tubular electrodes. The wire was put penetrating through the high voltage and the grounded electrodes, improving the discharge and facilitating uniform surface treatment. In this work, the influences of conductivity of the wire on the effects of surface treatment and discharge behavior were investigated. Surface properties of the wire samples were analyzed by means of surface energy measurement and X-ray photoelectron spectroscopy. In order to reveal the mechanism for treating the conductive wire, I-V discharge waveforms were measured and time-resolved plasma images were taken. It was demonstrated that the conductive wire was involved in the discharge process, reducing the breakdown voltage significantly and enhancing the discharge. It shows that the discharge mode was strongly dependent on the conductivity of a wire. Intensive surface discharges developed along the conductive wire were found to be mainly responsible for noticeable improvement in the treatment effect.

  20. In situ ecophysiology of Aigarchaeota from an oxic, hot-spring filamentous 'streamer' community

    Science.gov (United States)

    Beam, J.; Jay, Z.; Tringe, S. G.; Glavina del Rio, T.; Rusch, D.; Schmid, M.; Wagner, M.; Inskeep, W.

    2014-12-01

    The candidate phylum Aigarchaeota contains thermophilic archaea from terrestrial, subsurface, and marine geothermal ecosystems. The phylogeny and metabolic potential of Aigarchaeota has been deduced from several recent single-cell amplified genomes; however, an accurate description of their metabolism, potential ecological interactions, and role in biogeochemical cycling is lacking. Here we report possible ecological interactions and the in situ metabolism of an uncultivated lineage of Aigarchaeota from an oxic, terrestrial hot-spring filamentous 'streamer' community (Octopus Spring, pH = 8; T = 78 - 84 °C, Yellowstone National Park, Wyoming, USA). Fluorescence in situ hybridization (FISH) was combined with detailed genomic and transcriptomic reconstruction to elucidate the ecophysiological role of Aigarchaeota in these streamer communities. This novel population of Aigarchaeota are filamentous (~500 nm diameter by ~10-30 μm length), which is consistent with the morphology predicted by the presence and transcription of a single actin-encoding gene. Aigarchaeota filaments are intricately associated with other community members, which include both thermophilic bacteria and archaea. Metabolic reconstruction suggests that this aigarchaeon is an aerobic, chemoorganotroph. A single heme copper oxidase complex was identified in de novo genome assemblies, and was highly transcribed in environmental samples. Potential electron donors include acetate, fatty acids, sugars, peptides, and aromatic compounds. Transcripts related to genes specific to each of these potential electron donors were identified, indicating that this population of Aigarchaeota likely utilizes a broad range of reduced carbon substrates. Potential electron donors for this population may include extracellular polymeric substances produced by other microorganisms in close proximity. Flagellum genes were also highly transcribed, which suggests a potential mechanism for motility and/or cell-cell attachment

  1. Globally Deghosting for Marine Streamer with Alternating Minimization Approach in Frequency-slowness Domain

    Science.gov (United States)

    Wang, C.; Zhu, Z.; Gu, H.; Liu, C.; Liu, Z.; Jiao, Z.

    2017-12-01

    The ghost effects of the sea surface can generate notch in marine towed-streamer data, which results in narrow bandwidth of seismic data. Currently, deghosting is widely utilized to increase the bandwidth of the seismic data or the images. However, most of the conventional deghosting algorithms havenot considered the error of streamer depth causing a biased ghost-delay time (τ) with respect to primary reflection and amplitude difference coefficient (r) between ghost and primary reflection varies with offset due to rugged seabed and target depth variation. We proposed a ghost filtering operator considering the protentional biases within the ghost-delay time (τ) and the amplitude difference coefficient (r). The up-going wavefield (u), ghost-delay time (τ) and amplitude difference coefficient (r) can be obtained by utilizing alternating minimization approach for minimizing the difference between actual wavefield and theoretical wavefield in frequency-slowness domain. The main idea is to alternatively updating u, τ and r in each iteration: we update u by least-squares when we keep τ and r constant; and we then keep u constant and optimize over τ and r with a closed-form solution which is closely related to matched filtering. The convergence of the proposed algorithm is guaranteed since we have closed-form solutions for each stage. The experiments on synthetic record confirmed the reliability of the proposed algorithm. We also demonstrate our proposed method in marine VDS shot acquisition. After migration stack processing, our ghosting method significantly increases the bandwidth of the average amplitude, amplitude energy of the medium and high frequency spectrum, improving resolution of medium and deep reflection and providing higher signal-to-noise ratio with clear break point. This research is funded by China Important National Science & Technology Specific Projects (2016ZX05026001-001).

  2. Difficulty with cuff deflation of reinforced tracheal tube caused by inflation line occlusion with silk thread ligation and fixation.

    Science.gov (United States)

    Gotoh, Sayoko; Sugiyama, Daisuke; Imai, Eriko; Kawamata, Mikito

    2015-03-05

    A reinforced tracheal tube, ligated with silk threads, was inserted into a tracheostomy orifice and fixed to the skin. The cuff inflation line of the reinforced tracheal tube became occluded. Reinforced 'armoured' tracheal tubes have a spiral of wire embedded into the wall of the tube to give strength and flexibility, and may be sharply bent without compromising the tube lumen. The tracheal cuff attached to the tube is inflated by injecting air through a narrow-diameter tube welded to the outside of the tracheal tube. When a reinforced tracheal tube is ligated and fixed with silk threads, it should be confirmed whether the tracheal tube cuff can be deflated and inflated after fixation. Moreover, because occlusion can be eliminated by removing all silk threads used to ligate a tracheal tube, they should be removed before extubation. 2015 BMJ Publishing Group Ltd.

  3. Release of metal ions from round and rectangular NiTi wires

    Directory of Open Access Journals (Sweden)

    Arash Azizi

    2016-04-01

    Full Text Available Abstract Background The aim of this study was to evaluate the amount of nickel and titanium ions released from two wires with different shapes and a similar surface area. Methods Forty round nickel-titanium (NiTi arch wires with the diameter of 0.020 in. and 40 rectangular NiTi arch wires with the diameter of 0.016 × 0.016 in. were immersed in artificial saliva during a 21-day period. The surface area of both wires was 0.44 in.2. Wires were separately dipped into polypropylene tubes containing 50 ml of buffer solution and were incubated and maintained at 37 °C. Inductively coupled plasma atomic emission spectrometry (ICP-AES was used to measure the amount of ions released after exposure lengths of 1 h, 24 h, 1 week, and 3 weeks. Repeated measures ANOVA and Tukey tests were used to evaluate the data. Results The results indicated that the amount of nickel and titanium concentrations was significantly higher in the rectangular wire group. The most significant release of all metals was measured after the first hour of immersion. In the rectangular wire group, 243 ± 4.2 ng/ml of nickel was released after 1 h, while 221.4 ± 1.7 ng/ml of nickel was released in the round wire group. Similarly, 243.3 ± 2.8 ng/ml of titanium was released in the rectangular wire group and a significantly lower amount of 211.9 ± 2.3 ng/ml of titanium was released in the round wire group. Conclusions Release of metal ions was influenced by the shape of the wire and increase of time.

  4. Mechanical behaviour of copper 15% volume niobium microcomposite wires

    Directory of Open Access Journals (Sweden)

    Marcello Filgueira

    2001-01-01

    Full Text Available Cu-Nb microcomposites are attractive in magnet pulsed field technology applications due to their anomalous mechanism of mechanical strength and high electrical conductivity. In this sense, recently it was conceived the use of Cu 15% vol. Nb wires to operate as a high tensile strength cable for a diamond cutting tool (diamond wires for marble and granite slabbing. The multifilamentary Cu 15% vol. Nb composite was obtained using a new processing route, starting with niobium bars bundled into copper tubes, without arc melting. Cold working techniques, such as swaging and wire drawing, combined with heat treatments such as sintering and annealing, and tube restacking were employed. The tensile property of the composite was measured as a function of the niobium filaments dimensions and morphology into the copper matrix, in the several processing steps. An ultimate tensile strength (UTS of 960 MPa was obtained for an areal reduction (R = Ao/A, with Ao-initial cross section area, and A-final cross section area of 4x10(8 X, in which the niobium filaments reached thickness less than 20 nm. The anomalous mechanical strength increase is attributed to the fact that the niobium filaments acts as a barrier to copper dislocations.

  5. Development of laser cladding system to repair wall thinning of 1-inch heat exchanger tube

    International Nuclear Information System (INIS)

    Terada, Takaya

    2013-01-01

    We developed a laser cladding system to repair the inner wall wastage of heat exchanger tubes. Our system, which is designed to repair thinning tube walls within 100 mm from the edge of a heat exchanger tube, consists of a fiber laser, a composite-type optical fiberscope, a coupling device, a laser processing head, and a wire-feeding device. All of these components were reconfigured from the technologies of FBR maintenance. The laser processing head, which has a 15-mm outer diameter, was designed to be inserted into a 1-inch heat exchanger tube. We mounted a heatproof broadband mirror for laser cladding and fiberscope observation with visible light inside the laser processing head. The wire-feeding device continuously supplied 0.4-mm wire to the laser irradiation spot with variable feeding speeds from 0.5 to 20 mm/s. We are planning to apply our proposed system to the maintenance of aging industrial plants. (author)

  6. Characterization of the frictional losses and heat transfer of oscillatory viscous flow through wire-mesh regenerators

    Directory of Open Access Journals (Sweden)

    A.A. Boroujerdi

    2015-12-01

    Full Text Available In this paper, new relations for calculating heat transfer and pressure drop characteristics of oscillatory flow through wire-mesh screen regenerator such as Darcy permeability, Forchheimer’s inertial coefficient, and heat transfer area per unit volume, as a function of the wire diameter are presented. According to the derived relations, thinner wires have higher pressure drop and higher heat transfer rate. The relations are applicable for all regenerative cryocoolers. Embedding the new relations into a numerical model, three Stirling-type orifice pulse tube cryocoolers with three regenerators different in length and diameter but same volume in a variety of wire diameters, have been modeled. The results achieved by the model reveal that the local heat transfer coefficient decreases with increase of the wire diameter and the length-to-diameter ratio. In addition, it was shown that the mean absolute gas–solid wire temperature difference is a linear function of wire diameter in the range investigated. The results show that for larger length-to-diameter ratios, Forchheimer’s effect will dominate frictional losses, and the variations of the frictional losses are proportional to the inverse of the wire diameter. Wire diameter has been optimized to maximize the coefficient of performance of the cryocooler. Shorter regenerators have thinner optimum wires.

  7. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L; Cha, Min

    2016-01-01

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble

  8. Analysis and regularization of the thin-wire integral equation with reduced kernel

    NARCIS (Netherlands)

    Beurden, van M.C.; Tijhuis, A.G.

    2007-01-01

    For the straight wire, modeled as a hollow tube, we establish a conditional equivalence relation between the integral equations with exact and reduced kernel. This relation allows us to examine the existence and uniqueness conditions for the integral equation with reduced kernel, based on a local

  9. Modeling birds on wires.

    Science.gov (United States)

    Aydoğdu, A; Frasca, P; D'Apice, C; Manzo, R; Thornton, J M; Gachomo, B; Wilson, T; Cheung, B; Tariq, U; Saidel, W; Piccoli, B

    2017-02-21

    In this paper we introduce a mathematical model to study the group dynamics of birds resting on wires. The model is agent-based and postulates attraction-repulsion forces between the interacting birds: the interactions are "topological", in the sense that they involve a given number of neighbors irrespective of their distance. The model is first mathematically analyzed and then simulated to study its main properties: we observe that the model predicts birds to be more widely spaced near the borders of each group. We compare the results from the model with experimental data, derived from the analysis of pictures of pigeons and starlings taken in New Jersey: two different image elaboration protocols allow us to establish a good agreement with the model and to quantify its main parameters. We also discuss the potential handedness of the birds, by analyzing the group organization features and the group dynamics at the arrival of new birds. Finally, we propose a more refined mathematical model that describes landing and departing birds by suitable stochastic processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Inhomogeneous wire explosion in water

    International Nuclear Information System (INIS)

    Hwangbo, C.K.; Kong, H.J.; Lee, S.S.

    1980-01-01

    Inhomogeneous processes are observed in underwater copper wire explosion induced by a condensed capacitor discharge. The wire used is 0.1 mm in diameter and 10 mm long, and the capacitor of 2 μF is charged to 5 KV. A N 2 laser is used for the diagnostic of spatial extension of exploding copper vapour. The photographs obtained in this experiment show unambiguously the inhomogeneous explosion along the exploding wire. The quenching of plasma by the surrounding water inhibits the expansion of the vapour. It is believed the observed inhomogeneous explosion along the wire is located and localized around Goronkin's striae, which was first reported by Goronkin and discussed by Froengel as a pre-breakdown phenomenon. (author)

  11. Topology Optimized Photonic Wire Splitters

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn; Borel, Peter Ingo; Jensen, Jakob Søndergaard

    2006-01-01

    Photonic wire splitters have been designed using topology optimization. The splitters have been fabricated in silicon-on-insulator material and display broadband low-loss 3dB splitting in a bandwidth larger than 100 nm.......Photonic wire splitters have been designed using topology optimization. The splitters have been fabricated in silicon-on-insulator material and display broadband low-loss 3dB splitting in a bandwidth larger than 100 nm....

  12. Bender/Coiler for Tubing

    Science.gov (United States)

    Stoltzfus, J. M.

    1983-01-01

    Easy-to-use tool makes coils of tubing. Tubing to be bend clamped with stop post. Die positioned snugly against tubing. Operator turns handle to slide die along tubing, pushing tubing into spiral groove on mandrel.

  13. Critical heat flux in tubes and tight hexagonal rod lattices

    International Nuclear Information System (INIS)

    Erbacher, F.J.; Cheng Xu; Zeggel, W.

    1994-01-01

    The critical heat flux (CHF) in small-diameter tubes and in tight hexagonal 7-rod and 37-rod bundles was investigated in the KRISTA test facility, using Freon 12 as the working fluid. The measurements in tubes showed that the influence of the tube diameter on CHF cannot be described as suggested by earlier publications with sufficient accuracy. CHF in bundles is lower than in tubes under comparable conditions. The influence of spacers (grid spacers, wire wraps) on CHF was found to be governed by local steam qualities. A comparison of the test results with some CHF prediction methods showed that the look-up table method reproduces the test results in circular tubes most accurately. Combined with CHF look-up tables, subchannel analysis and Ahmad's fluid-to-fluid scaling law, Freon experiments have proven to be a suitable tool for CHF prediction in water-cooled rod bundles. (orig.) [de

  14. HTS Wire Development Workshop: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The 1994 High-Temperature Superconducting Wire Development Workshop was held on February 16--17 at the St. Petersburg Hilton and Towers in St. Petersburg, Florida. The meeting was hosted by Florida Power Corporation and sponsored by the US Department of Energy`s Superconductivity Program for Electric Power Systems. The meeting focused on recent high-temperature superconducting wire development activities in the Department of Energy`s Superconductivity Systems program. The meeting opened with a general discussion on the needs and benefits of superconductivity from a utility perspective, the US global competitiveness position, and an outlook on the overall prospects of wire development. The meeting then focused on four important technology areas: Wire characterization: issues and needs; technology for overcoming barriers: weak links and flux pinning; manufacturing issues for long wire lengths; and physical properties of HTS coils. Following in-depth presentations, working groups were formed in each technology area to discuss the most important current research and development issues. The working groups identified research areas that have the potential for greatly enhancing the wire development effort. These areas are discussed in the summary reports from each of the working groups. This document is a compilation of the workshop proceedings including all general session presentations and summary reports from the working groups.

  15. Wire Scanner Motion Control Card

    CERN Document Server

    Forde, S E

    2006-01-01

    Scientists require a certain beam quality produced by the accelerator rings at CERN. The discovery potential of LHC is given by the reachable luminosity at its interaction points. The luminosity is maximized by minimizing the beam size. Therefore an accurate beam size measurement is required for optimizing the luminosity. The wire scanner performs very accurate profile measurements, but as it can not be used at full intensity in the LHC ring, it is used for calibrating other profile monitors. As the current wire scanner system, which is used in the present CERN accelerators, has not been made for the required specification of the LHC, a new design of a wire scanner motion control card is part of the LHC wire scanner project. The main functions of this card are to control the wire scanner motion and to acquire the position of the wire. In case of further upgrades at a later stage, it is required to allow an easy update of the firmware, hence the programmable features of FPGAs will be used for this purpose. The...

  16. Sub-nanosecond delays of light emitted by streamer in atmospheric pressure air: Analysis of N2( C3Πu) and N2+(B2Σ u +) emissions and fundamental streamer structure

    Czech Academy of Sciences Publication Activity Database

    Hoder, T.; Bonaventura, Z.; Bourdon, A.; Šimek, Milan

    2015-01-01

    Roč. 117, č. 7 (2015), 073302-073302 ISSN 0021-8979 R&D Projects: GA ČR(CZ) GAP205/12/1709 Institutional support: RVO:61389021 Keywords : streamer * optical diagnostics * nitrogen * emission Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.101, year: 2015 http://scitation.aip.org/content/aip/journal/jap/117/7/10.1063/1.4913215

  17. 1 mil gold bond wire study.

    Energy Technology Data Exchange (ETDEWEB)

    Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.; Rutherford, Brian Milne

    2013-05-01

    In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, the gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.

  18. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish

    2016-09-08

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface. © 2016 IOP Publishing Ltd.

  19. Ignition and spread of electrical wire fires

    OpenAIRE

    Huang, Xinyan

    2012-01-01

    Ignition of electrical wires by external heating is investigated in order to gain a better understanding of the initiation of electrical-wire fires. An ignition-to- spread model is developed to systematically explain ignition and the following transition to spread. The model predicts that for a higher-conductance wire it is more difficult to achieve ignition and the weak flame may extinguish during the transition phase because of a large conductive heat loss along the wire core. Wires with tw...

  20. A southeastern Mediterranean PV streamer and its role in December 2001 case with torrential rains in Israel

    Directory of Open Access Journals (Sweden)

    S. O. Krichak

    2007-01-01

    Full Text Available A precipitation event of unprecedented intensity took place over northern part of Israel during 4 December 2001–5 December 2001. The case was associated with formation of a Cyprus Low cyclone over the Asia Minor. In the current study the synoptic developments over the eastern part of the Mediterranean region are simulated with the MM5 nonhydrostatic model and analyzed based on dynamic tropopause patterns calculated from the simulation results. According to the results, a powerful potential vorticity (PV streamer system played a major role in the process over the southeastern Mediterranean region. The PV streamer created conditions for seclusion of moist air masses from the equatorial East Africa and Atlantics during the cyclone development. Condensation of the moisture, associated with the latent heat release processes have contributed to the intense thunderstorm activity and heavy precipitation of the event.

  1. Towards User-Friendly Spelling with an Auditory Brain-Computer Interface: The CharStreamer Paradigm

    Science.gov (United States)

    Höhne, Johannes; Tangermann, Michael

    2014-01-01

    Realizing the decoding of brain signals into control commands, brain-computer interfaces (BCI) aim to establish an alternative communication pathway for locked-in patients. In contrast to most visual BCI approaches which use event-related potentials (ERP) of the electroencephalogram, auditory BCI systems are challenged with ERP responses, which are less class-discriminant between attended and unattended stimuli. Furthermore, these auditory approaches have more complex interfaces which imposes a substantial workload on their users. Aiming for a maximally user-friendly spelling interface, this study introduces a novel auditory paradigm: “CharStreamer”. The speller can be used with an instruction as simple as “please attend to what you want to spell”. The stimuli of CharStreamer comprise 30 spoken sounds of letters and actions. As each of them is represented by the sound of itself and not by an artificial substitute, it can be selected in a one-step procedure. The mental mapping effort (sound stimuli to actions) is thus minimized. Usability is further accounted for by an alphabetical stimulus presentation: contrary to random presentation orders, the user can foresee the presentation time of the target letter sound. Healthy, normal hearing users (n = 10) of the CharStreamer paradigm displayed ERP responses that systematically differed between target and non-target sounds. Class-discriminant features, however, varied individually from the typical N1-P2 complex and P3 ERP components found in control conditions with random sequences. To fully exploit the sequential presentation structure of CharStreamer, novel data analysis approaches and classification methods were introduced. The results of online spelling tests showed that a competitive spelling speed can be achieved with CharStreamer. With respect to user rating, it clearly outperforms a control setup with random presentation sequences. PMID:24886978

  2. LIF study of N2(A3+u, v=0-10) vibrational kinetics under nitrogen streamer conditions

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Ambrico, P. F.; Prukner, Václav

    2015-01-01

    Roč. 48, č. 26 (2015), s. 265202-265202 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GAP205/12/1709 Institutional support: RVO:61389021 Keywords : nitrogen metastable * streamer * optical diagnostics * laser-induced fluorescence * LIF Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.772, year: 2015 http://dx.doi.org/10.1088/0022-3727/48/26/265202

  3. Mapping the base of sand dunes using a new design of land-streamer for static correction applications

    KAUST Repository

    Almalki, H.

    2012-05-16

    The complex near-surface structure is a major problem in land seismic data. This is more critical when data acquisition takes place over sand dune surfaces, where the base of the sand acts as a trap for energy and, depending on its shape, can considerably distort conventionally acquired seismic data. Estimating the base of the sand dune surface can help model the sand dune and reduce its harmful influence on conventional seismic data. Among the current methods to do so are drilling upholes and using conventional seismic data to apply static correction. Both methods have costs and limitations. For upholes, the cost factor and their inability to provide a continuous model is well realized. Meanwhile, conventional seismic data lack the resolution necessary to obtain accurate modeling of the sand basement. We developed a method to estimate the sand base from land-streamer seismic acquisition that is developed and geared to sand surfaces. Seismic data acquisition took place over a sand surface in the Al-Thumamah area, where an uphole is located, using the developed land-streamer and conventional spiked geophone systems. Land-streamer acquisition not only provides a more efficient data acquisition system than the conventional spiked geophone approach, but also in our case, the land-streamer provided better quality data with a broader frequency bandwidth. Such data enabled us to do accurate near-surface velocity estimation that resulted in velocities that are very close to those measured using uphole methods. This fact is demonstrated on multiple lines acquired near upholes, and agreement between the seismic velocities and the upholes is high. The stacked depth seismic section shows three layers. The interface between the first and second layers is located at 7 m depth, while the interface between second and third layers is located at 68 m depth, which agrees with the uphole result. 2012 The Author(s).

  4. Behaviour of OH radicals in an atmospheric-pressure streamer discharge studied by two-dimensional numerical simulation

    International Nuclear Information System (INIS)

    Komuro, Atsushi; Ono, Ryo; Oda, Tetsuji

    2013-01-01

    The production process of OH radicals in an atmospheric-pressure streamer discharge is studied. A streamer discharge model is developed to analyse the characteristics of a pulsed positive streamer discharge in point-to-plane electrodes filled with humid air at atmospheric pressure. The results indicate that the behaviour of OH radicals in and after the discharge pulse is characterized by three reaction processes: ‘OH-production’, ‘OH-cycle’ and ‘OH-recombination’. The first process of OH-production includes dissociation reactions of H 2 O with O( 1 D) and N 2 (a' 1 Σ u - ), which are the main production processes of OH in the discharge. Immediately after the OH-production process, the OH radicals are destroyed by a reaction with O( 3 P) to form O 2 and H. Then the subsequent reactions produce OH again through the reaction of H + HO 2 , which is the OH-cycle process. Finally, the OH radicals are consumed by the OH-recombination process. (paper)

  5. Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms

    Directory of Open Access Journals (Sweden)

    C. Forsyth

    2008-02-01

    Full Text Available We present a multi-instrument study of a substorm bursty bulk flow (BBF and auroral streamer. During a substorm on 25 August 2003, which was one of a series of substorms that occurred between 00:00 and 05:00 UT, the Cluster spacecraft encountered a BBF event travelling Earthwards and duskwards with a velocity of ~500 km s−1 some nine minutes after the onset of the substorm. Coincident with this event the IMAGE spacecraft detected an auroral streamer in the substorm auroral bulge in the Southern Hemisphere near the footpoints of the Cluster spacecraft. Using FluxGate Magnetometer (FGM data from the four Cluster spacecraft, we determine the field-aligned currents in the BBF, using the curlometer technique, to have been ~5 mA km−2. When projected into the ionosphere, these currents give ionospheric field-aligned currents of ~18 A km−2, which is comparable with previously observed ionospheric field-aligned currents associated with BBFs and auroral streamers. The observations of the BBF are consistent with the plasma "bubble" model of Chen and Wolf (1993. Furthermore, we show that the observations of the BBF are consistent with the creation of the BBF by the reconnection of open field lines Earthward of a substorm associated near-Earth neutral line.

  6. Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms

    Directory of Open Access Journals (Sweden)

    C. Forsyth

    2008-02-01

    Full Text Available We present a multi-instrument study of a substorm bursty bulk flow (BBF and auroral streamer. During a substorm on 25 August 2003, which was one of a series of substorms that occurred between 00:00 and 05:00 UT, the Cluster spacecraft encountered a BBF event travelling Earthwards and duskwards with a velocity of ~500 km s−1 some nine minutes after the onset of the substorm. Coincident with this event the IMAGE spacecraft detected an auroral streamer in the substorm auroral bulge in the Southern Hemisphere near the footpoints of the Cluster spacecraft. Using FluxGate Magnetometer (FGM data from the four Cluster spacecraft, we determine the field-aligned currents in the BBF, using the curlometer technique, to have been ~5 mA km−2. When projected into the ionosphere, these currents give ionospheric field-aligned currents of ~18 A km−2, which is comparable with previously observed ionospheric field-aligned currents associated with BBFs and auroral streamers. The observations of the BBF are consistent with the plasma "bubble" model of Chen and Wolf (1993. Furthermore, we show that the observations of the BBF are consistent with the creation of the BBF by the reconnection of open field lines Earthward of a substorm associated near-Earth neutral line.

  7. Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng; Shao, Tao, E-mail: st@mail.iee.ac.cn; Wang, Ruixue; Yan, Ping [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Tarasenko, Viktor F.; Beloplotov, Dmitry V.; Lomaev, Mikhail I.; Sorokin, Dmitry A. [Institute of High Current Electronics, Russian Academy of Science, Tomsk 634055 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation)

    2015-03-15

    Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front.

  8. Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons

    International Nuclear Information System (INIS)

    Zhang, Cheng; Shao, Tao; Wang, Ruixue; Yan, Ping; Tarasenko, Viktor F.; Beloplotov, Dmitry V.; Lomaev, Mikhail I.; Sorokin, Dmitry A.

    2015-01-01

    Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front

  9. Technical innovation: Wire guided ductography

    International Nuclear Information System (INIS)

    Aslam, Muhammad Ovais; Ramadan, Salwa; Al-Adwani, Muneera

    2012-01-01

    To introduce an easy and improved technique for performing ductography using inexpensive easily available intravenous cannula. Guide wire: Prolene/Surgipro 3-0 (Polypropylene mono filament non-absorbable surgical suture). A plastic 26 G intravenous cannula. Disposable syringe 2 ml. Non-ionic contrast (low density like Omnipaque 240 mg I/I). The guide wire (Prolene 3-0) is introduced into the orifice of the duct heaving discharge and 26 G intravenous plastic cannula is then passed over the guide wire. The cannula is advanced in the duct over guide wire by spinning around it. When the cannula is in place the guide wire is removed. Any air bubbles present in the hub of the cannula can be displaced by filling the hub from bottom upwards with needle attached to contrast filled syringe. 0.2–0.4 ml non-ionic contrast is gently injected. Injection is stopped if the patient has pain or burning. Magnified cranio-caudal view is obtained with cannula tapped in place and gentle compression is applied with the patient sitting. If duct filling is satisfactory a 90* lateral view is obtained. A successful adaptation of the technique for performing ductography is presented. The materials required for the technique are easily available in most radiology departments and are inexpensive, thus making the procedure comfortable for the patient and radiologist with considerable cost effectiveness.

  10. Californium Recovery from Palladium Wire

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-08-01

    The recovery of 252Cf from palladium-252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, which ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.

  11. Numerical simulation of fluid flow and heat transfer in a concentric tube heat exchanger

    International Nuclear Information System (INIS)

    Mokamati, S.V.; Prasad, R.C.

    2003-01-01

    In this paper, numerical simulation of a concentric tube heat exchanger is presented to determine the convective heat transfer coefficient and friction factor in a smooth tube. Increasing the convective heat transfer coefficient can increase heat transfer rate in a concentric tube heat exchanger from a given tubular surface area. This can be achieved by using heat transfer augmentation devices. This work constitutes the initial phase of the numerical simulation of heat transfer from tubes employing augmentation devices, such as twisted tapes, wire-coil inserts, for heat transfer enhancement. A computational fluid dynamics (CFD) simulation tool was developed with CFX software and the results obtained from the simulations are validated with the empirical correlations for a smooth tube heat exchanger. The difficulties associated with the simulation of a heat exchanger augmented with wire-coil inserts are discussed. (author)

  12. Transfer of a cold atmospheric pressure plasma jet through a long flexible plastic tube

    International Nuclear Information System (INIS)

    Kostov, Konstantin G; Prysiazhnyi, Vadym; Honda, Roberto Y; Machida, Munemasa

    2015-01-01

    This work proposes an experimental configuration for the generation of a cold atmospheric pressure plasma jet at the downstream end of a long flexible plastic tube. The device consists of a cylindrical dielectric chamber where an insulated metal rod that serves as high-voltage electrode is inserted. The chamber is connected to a long (up to 4 m) commercial flexible plastic tube, equipped with a thin floating Cu wire. The wire penetrates a few mm inside the discharge chamber, passes freely (with no special support) along the plastic tube and terminates a few millimeters before the tube end. The system is flushed with Ar and the dielectric barrier discharge (DBD) is ignited inside the dielectric chamber by a low frequency ac power supply. The gas flow is guided by the plastic tube while the metal wire, when in contact with the plasma inside the DBD reactor, acquires plasma potential. There is no discharge inside the plastic tube, however an Ar plasma jet can be extracted from the downstream tube end. The jet obtained by this method is cold enough to be put in direct contact with human skin without an electric shock. Therefore, by using this approach an Ar plasma jet can be generated at the tip of a long plastic tube far from the high-voltage discharge region, which provides the safe operation conditions and device flexibility required for medical treatment. (paper)

  13. Low-mass X-ray binaries and globular clusters streamers and arcs in NGC 4278

    Energy Technology Data Exchange (ETDEWEB)

    D' Abrusco, R.; Fabbiano, G. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Brassington, N. J. [Center for Astrophysics Research, University of Hertfordshire, College Lane Campus, Hatfield, Hertordshire, AL10 9AB (United Kingdom)

    2014-03-01

    We report significant inhomogeneities in the projected two-dimensional spatial distributions of low-mass X-ray binaries (LMXBs) and globular clusters (GCs) of the intermediate mass elliptical galaxy NGC 4278. In the inner region of NGC 4278, a significant arc-like excess of LMXBs extending south of the center at ∼50'' in the western side of the galaxy can be associated with a similar overdensity of the spatial distribution of red GCs from Brassington et al. Using a recent catalog of GCs produced by Usher et al. and covering the whole field of the NGC 4278 galaxy, we have discovered two other significant density structures outside the D {sub 25} isophote to the W and E of the center of NGC 4278, associated with an overdensity and an underdensity, respectively. We discuss the nature of these structures in the context of the similar spatial inhomogeneities discovered in the LMXBs and GCs populations of NGC 4649 and NGC 4261, respectively. These features suggest streamers from disrupted and accreted dwarf companions.

  14. Composite film fabricated on biomedical material with corona streamer plasma processing to mitigate bacterial adhesion

    Science.gov (United States)

    Alhamarneh, Ibrahim; Pedrow, Patrick; Eskhan, Asma; Abu-Lail, Nehal

    2011-10-01

    Composite films might control bacterial adhesion and concomitant biofouling that afflicts biomedical materials. Different size molecules of polyethylene glycol (PEG) with nominal molecular weights 600, 2000, and 20000 g/mol were used to synthesize composite films with plasma processing and dip-coating procedures on surgical-grade 316L stainless steel. Before dip-coating, the substrate was pre-coated with plasma-polymerized di(ethylene glycol) vinyl ether (pp-EO2V) in an atmospheric pressure corona streamer plasma reactor. The PEG dip-coating step followed immediately in the same chamber due to the finite lifetime of radicals associated with freshly deposited pp-EO2V. Morphology of the composite film was investigated with an ESEM. FTIR confirmed incorporation of pp-EO2V and PEG species into the composite film. More investigations on the composite film were conducted by XPS measurements. Adhesion of the composite film was evaluated with a standard peel-off test. Stability of the composite film in buffer solution was evaluated by AFM. AFM was also used to measure the film roughness and thickness. Polar and non-polar contact angle measurements were included.

  15. NO-γ emissions from streamer discharges: direct electron impact excitation versus resonant energy transfer

    International Nuclear Information System (INIS)

    Liu Ningyu; Pasko, Victor P

    2010-01-01

    It has been established that production of NO-γ emission in pulsed corona discharges is dominated by the energy transfer from N 2 (A 3 Σ u + ) to the NO ground state NO(X 2 Π r ) while direct excitation by electron impact is negligible. However, recent studies suggest that the electron impact excitation plays a more important role. In this work, we report modelling results of NO-γ emission associated with streamer discharges using two cross section data sets available in the literature. The first set was originally reported by Mojarrabi et al (1996 Phys. Rev. A 54 2977-82) and later updated by Brunger et al (2000 J. Phys. B: At. Mol. Opt. Phys. 33 809-19); the second set was published by Hayashi (1990 Nonequilibrium Processes in Partially Ionized Gases (NATO Advanced Science Institutes Series, Series B, Physics vol 220) ed M Capitelli and J N Bardsley (New York: Plenum) pp 333-40). According to the results, the role played by the electron impact excitation in the production of NO-γ is drastically different when different cross sections are used. The results indicate that the first data set leads to better agreement with experimental measurements. (fast track communication)

  16. On the data compression at filmless readout of the streamer chamber information

    International Nuclear Information System (INIS)

    Bajla, I.; Ososkov, G.A.; Prikhod'ko, V.I.

    1980-01-01

    It is supposed that the system of filmless detecting and processing the visual information from ''RISK'' streamer chamber will comprise the effective on-line data compression algorithm. The role of the basic methodological principles of chamber image film processing in Righ Energy Physics for building up such system is analysed. On the basis of this analysis the main requirements are formulated that have to be fulfilled by the compression algorithm. The most important requirement consists in securing the possibility of the input data reprocessing, if problems in the off-line recognition occur. Using a vector system representation of primary data, the on-line data compression philosophy is proposed that embodies the following three principles: universality, parallelism and input data reconstructibility. Excluding of the recognition procedure from the on-line compression algorithm causes the compression factor reduction. The hierarchic structure of the compression algorithm consisting of (1) sorting, (2) filtering, (3) compression for an additional increasing of the compression ratio is proposed

  17. Three-dimensional magnetohydrodynamic simulations of in situ shock formation in the coronal streamer belt

    International Nuclear Information System (INIS)

    Zaliznyak, Yu.; Keppens, R.; Goedbloed, J.P.

    2003-01-01

    A numerical study of an idealized magnetohydrodynamic (MHD) configuration consisting of a planar wake flow embedded into a three-dimensional (3D) sheared magnetic field is presented. The simulations investigate the possibility for in situ development of large-scale compressive disturbances at cospatial current sheet-velocity shear regions in the heliosphere. Using a linear MHD solver, the systematical investigation of the destabilized wavenumbers, corresponding growth rates, and physical parameter ranges for dominant 3D sinuous-type instabilities in an equilibrium wake-current sheet system was done. Wakes bounded by sufficiently supersonic (Mach number M s >2.6) flow streams are found to support dominant fully 3D sinuous instabilities when the plasma beta is of order unity. Fully nonlinear, compressible 2.5D and 3D MHD simulations show the self-consistent formation of shock fronts of fast magnetosonic type. They carry density perturbations far away from the wake's center. Shock formation conditions are identified in sonic and Alfvenic Mach number parameter space. Depending on the wake velocity contrast and magnetic field magnitude, as well as on the initial perturbation, the emerging shock patterns can be plane-parallel as well as fully three-dimensionally structured. Similar large-scale transients could therefore originate at distances far above coronal helmet streamers or at the location of the ecliptic current sheet

  18. Radiation thickness gauge using beta particle sensitivity controlled open air corona streamer counter

    International Nuclear Information System (INIS)

    Fouad, L.; El-Hazek, S.; El-Araby, S.

    1999-01-01

    Beta particles have been used extensively in radio gauging applications when measurements of foil thicknesses are desired. Using beta particle open air corona streamer counter (point-grid-plane) as a thickness gauge is presented. This gauge consists of two similar counters with two similar Sr-90 beta sources. One counter-source combination is called standard unit, and the other counter-source combination is called measuring unit in which the required foil thickness can be measured by inserting it between the source and the counter. The signals from the counters are amplified with the same gain factor and the net difference between their responses is measured using specially designed electronic circuit. By this way any change that takes place in the operating medium (variation of parameters of open air i.e. temperature, humidity...etc) can similarly affect the two units, the errors in the measurements caused by them are cancelled, and the only response is due to the measured foil thickness. A theoretical model is suggested to explain and analyze the overall response of the gauge system and calculate the calibration thickness gauge constant. All theoretical findings are confirmed by experiments

  19. X-ray tubes

    International Nuclear Information System (INIS)

    Young, R.W.

    1979-01-01

    A form of x-ray tube is described which provides satisfactory focussing of the electron beam when the beam extends for several feet from gun to target. Such a tube can be used for computerised tomographic scanning. (UK)

  20. Pressure tube type reactors

    International Nuclear Information System (INIS)

    Komada, Masaoki.

    1981-01-01

    Purpose: To increase the safety of pressure tube type reactors by providing an additional ECCS system to an ordinary ECCS system and injecting heavy water in the reactor core tank into pressure tubes upon fractures of the tubes. Constitution: Upon fractures of pressure tubes, reduction of the pressure in the fractured tubes to the atmospheric pressure in confirmed and the electromagnetic valve is operated to completely isolate the pressure tubes from the fractured portion. Then, the heavy water in the reactor core tank flows into and spontaneously recycles through the pressure tubes to cool the fuels in the tube to prevent their meltdown. By additionally providing the separate ECCS system to the ordinary ECCS system, fuels can be cooled upon loss of coolant accidents to improve the safety of the reactors. (Moriyama, K.)

  1. Gastrostomy feeding tube - bolus

    Science.gov (United States)

    Feeding - gastrostomy tube - bolus; G-tube - bolus; Gastrostomy button - bolus; Bard Button - bolus; MIC-KEY - bolus ... KEY, 3 to 8 weeks after surgery. These feedings will help your child grow strong and healthy. ...

  2. Feeding tube insertion - gastrostomy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002937.htm Feeding tube insertion - gastrostomy To use the sharing features on this page, please enable JavaScript. A gastrostomy feeding tube insertion is the placement of a feeding ...

  3. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  4. Development of a helical-coil double wall tube steam generator for 4S reactor

    International Nuclear Information System (INIS)

    Kitajima, Yuko; Maruyama, Shigeki; Jimbo, Noboru; Hino, Takehisa; Sato, Katsuhiko

    2011-01-01

    The 4S, Super-Safe Small and Simple, is a small-sized sodium-cooled fast reactor. A fast reactor usually uses sodium as a coolant to transfer heat from core to turbine/generator system. The heat of the intermediate heat transport system and that of the water stream systems are exchanged by the steam generator (SG) tubes. If the tube failure occurs, a sodium/water reaction could be occurred. To prevent the reaction and enhance safety, a helical-coil-type double wall tube with wire mesh interlayer and continuous monitoring systems of tube failure are applied to the SG of the 4S. The development and general features of this type double wall tube were described in Ref. 1) and Ref. 2). Those paper summarized following results; The tubes studied in these references were straight type. To establish this SG, development of manufacturing method of helical-coil-type double wall tube and validation of the tube failure monitoring system are needed. In this study, three demonstration tests have been performed; welding test of the double wall tube to manufacture the tubes with 70-80m length, assembling test of the helical-coil tube, and confirmation test of the tube processing system using the fabricated helical-coil tubes. As a result, following technologies have been successfully established. (1) Development of the welding techniques for manufacturing of the helical-coil-type double wall tube with wire mesh interlayer. (2) The confirmation test for manufacturing the helical coil tube of the SG. (author)

  5. Heating device for thermal treatment of curred small diameter tubes and utilization of this device

    International Nuclear Information System (INIS)

    Jacquier, P.

    1988-01-01

    The heating device is made by a helical winding constituted from a resistance heating wire. The heating wire constituted the central core of a coaxial cable comprising an outer tubular metal envelope and an insulating layer interpolated between the central core and the outer envelope. The coaxial cable is wound in order to form a helical winding that forms the flexible element for introduction to the tube to be treated [fr

  6. Large-Scale Production of Monitored Drift Tube Chambers for the ATLAS Muon Spectrometer

    CERN Document Server

    Bauer, F.; Kortner, O; Kroha, H; Manz, A; Mohrdieck, S; Richter, R; Zhuravlov, V

    2016-01-01

    Precision drift tube chambers with a sense wire positioning accuracy of better than 20 microns are under construction for the ATLAS muon spectrometer. 70% of the 88 large chambers for the outermost layer of the central part of the spectrometer have been assembled. Measurements during chamber construction of the positions of the sense wires and of the sensors for the optical alignment monitoring system demonstrate that the requirements for the mechanical precision of the chambers are fulfilled.

  7. 21 CFR 868.5800 - Tracheostomy tube and tube cuff.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tracheostomy tube and tube cuff. 868.5800 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5800 Tracheostomy tube and tube cuff. (a) Identification. A tracheostomy tube and tube cuff is a device intended to be placed into a...

  8. Rodent Zic Genes in Neural Network Wiring.

    Science.gov (United States)

    Herrera, Eloísa

    2018-01-01

    The formation of the nervous system is a multistep process that yields a mature brain. Failure in any of the steps of this process may cause brain malfunction. In the early stages of embryonic development, neural progenitors quickly proliferate and then, at a specific moment, differentiate into neurons or glia. Once they become postmitotic neurons, they migrate to their final destinations and begin to extend their axons to connect with other neurons, sometimes located in quite distant regions, to establish different neural circuits. During the last decade, it has become evident that Zic genes, in addition to playing important roles in early development (e.g., gastrulation and neural tube closure), are involved in different processes of late brain development, such as neuronal migration, axon guidance, and refinement of axon terminals. ZIC proteins are therefore essential for the proper wiring and connectivity of the brain. In this chapter, we review our current knowledge of the role of Zic genes in the late stages of neural circuit formation.

  9. PADI ASIC for straw tube read-out

    Energy Technology Data Exchange (ETDEWEB)

    Pietraszko, Jerzy; Traeger, Michael; Fruehauf, Jochen; Schmidt, Christian [GSI, Darmstadt (Germany); Ciobanu, Mircea [ISS, Bucharest (Romania); Collaboration: CBM-Collaboration

    2016-07-01

    A prototype of the CBM MUCH straw tube detector consisting of six individual straws of 6mm inner diameter and 220 mm length filled with Ar/CO{sub 2} gas mixture has been tested at the COSY accelerator in Juelich. The straw tubes were connected to the FEET-PADI6-HDa PCB equipped with PADI-6 fast amplifier/discriminator ASIC. As a reference counter in this measurement the scCVD diamond detector has been used delivering excellent timing, time resolution below 100 ps (sigma), and very precise position information, below 50 μm. The demonstrated position resolution of about 160 μm of the straw tube read out with PADI-6 ASIC confirms the capability of the PADI chip and puts this development as a very attractive readout option for straw tubes and wire chambers.

  10. Transparency in nanophotonic quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada)

    2009-03-28

    We have studied the quantum optics of a photonic quantum nanowire doped with an ensemble of three-level nanoparticles. The wire is made from two photonic crystals A and B. Crystal A is embedded within crystal B and acts as a photonic nanowire. It is considered that the conduction band of crystal A lies below that of crystal B. As a result, photons are confined in crystal A and are reflected from crystal B. The bound states of the confined photons are calculated using the transfer matrix method. It is found that the number of bound states in the wire depends on the size of the wire and the energy difference between the conduction band extrema of crystals A and B. The absorption coefficient of the system has also been calculated using the Schroedinger equation method. It is considered that the nanoparticles interact with the photonic bound states. Numerical simulations show that when one of the resonance energies lies near the bound state, the system becomes transparent. However, when the resonance energy lies away from the bound state the crystal reverts to an absorbing state. Similarly, when the radius of the dielectric spheres is changed the location of the transparency peak is shifted. This means that the present system can be switched between two states by changing the size of the wire and the transition energy. These findings can be used to make new types of optical devices.

  11. Transparency in nanophotonic quantum wires

    International Nuclear Information System (INIS)

    Singh, Mahi R

    2009-01-01

    We have studied the quantum optics of a photonic quantum nanowire doped with an ensemble of three-level nanoparticles. The wire is made from two photonic crystals A and B. Crystal A is embedded within crystal B and acts as a photonic nanowire. It is considered that the conduction band of crystal A lies below that of crystal B. As a result, photons are confined in crystal A and are reflected from crystal B. The bound states of the confined photons are calculated using the transfer matrix method. It is found that the number of bound states in the wire depends on the size of the wire and the energy difference between the conduction band extrema of crystals A and B. The absorption coefficient of the system has also been calculated using the Schroedinger equation method. It is considered that the nanoparticles interact with the photonic bound states. Numerical simulations show that when one of the resonance energies lies near the bound state, the system becomes transparent. However, when the resonance energy lies away from the bound state the crystal reverts to an absorbing state. Similarly, when the radius of the dielectric spheres is changed the location of the transparency peak is shifted. This means that the present system can be switched between two states by changing the size of the wire and the transition energy. These findings can be used to make new types of optical devices.

  12. Fabrication of tungsten wire needles

    International Nuclear Information System (INIS)

    Roder, A.

    1983-02-01

    Fine point needles for field emissoin are conventionally produced by electrolytically or chemically etching tungsten wire. Points formed in this manner have a typical tip radius of about 0.5 microns and a cone angle of some 30 degrees. The construction of needle matrix detector chambers has created a need for tungsten needles whose specifications are: 20 mil tungsten wire, 1.5 inch total length, 3 mm-long taper (resulting in a cone angle of about 5 degrees), and 25 micron-radius point (similar to that found on sewing needles). In the process described here for producing such needles, tungsten wire, immersed in a NaOH solution and in the presence of an electrode, is connected first to an ac voltage and then to a dc supply, to form a taper and a point on the end of the wire immersed in the solution. The process parameters described here are for needles that will meet the above specifications. Possible variations will be discussed under each approprite heading

  13. Multifilamentary MgB2 wires fracture behavior during the drawing process

    International Nuclear Information System (INIS)

    Shan, D.; Yan, G.; Zhou, L.; Li, J.S.; Li, C.S.; Wang, Q.Y.; Xiong, X.M.; Jiao, G.F.

    2012-01-01

    The fracture behavior of 6 + 1 filamentary MgB 2 superconductive wires is presented here. The composite wires were fabricated by in situ Powder-in-Tube method using Nb as a barrier and copper as a stabilizer. The microstructure of the material has a great influence on its fracture behavior. The microstructural aspects of crack nucleation and propagation are discussed. It shows that there are complicated correlations between fracture behavior and the main influencing parameters, which contain specific drawing conditions (drawing velocity, reduction in area per pass), materials properties (strength, yield stress, microstructure) as well as the extent of bonding between the metal sheaths at their interface.

  14. ROOT Analysis of 2004 H8 Test Beam Data & Studies of MDT Sense Wire Displacements

    CERN Document Server

    2004-01-01

    Tests are being carried out at the CERN H8 Test Facility on the subdetectors of ATLAS. Using MUTRAK, a tool developed by Dan Levin, data from test muon beam runs are converted to PAW plots and ntuples for easy analysis. ROOT classes are currently being developed to convert the PAW output of MUTRAK to ROOT files for more detailed analysis. Also studies are currently underway to understand the effect of sense wire displacements in Monitored Drift Tubes on drift time spectra. Concurrent tests using simulations in GARFIELD and Cosmic Ray MDT experiments are underway to study wire sags which may be up to 480 micrometers due to gravitational and electrostatic forces .

  15. Defect structures in MgB2 wires introduced by hot isostatic pressing

    International Nuclear Information System (INIS)

    Liao, X Z; Serquis, A; Zhu, Y T; Civale, L; Hammon, D L; Peterson, D E; Mueller, F M; Nesterenko, V F; Gu, Y

    2003-01-01

    The microstructures of MgB 2 wires prepared by the powder-in-tube technique and subsequent hot isostatic pressing were investigated using transmission electron microscopy. A large amount of crystalline defects including small-angle twisting, tilting and bending boundaries, in which high densities of dislocations reside, was found forming sub-grains within MgB 2 grains. It is believed that these defects resulted from particle deformation during the hot isostatic pressing process and are effective flux pinning centres that contribute to the high critical current densities of the wires at high temperatures and at high fields

  16. [Mechanics analysis of fracture of orthodontic wires].

    Science.gov (United States)

    Wang, Yeping; Sun, Xiaoye; Zhang, Longqi

    2003-03-01

    Fracture problem of orthodontic wires was discussed in this paper. The calculation formulae of bending stress and tensile stress were obtained. All main factors that affect bending stress and tensile stress of orthodontic wires were analyzed and discussed. It was concluded that the main causes of fracture of orthodontic wires were fatigue and static disruption. Some improving proposals for preventing fracture of orthodontic wires were put forward.

  17. Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

    NARCIS (Netherlands)

    Winands, G.J.J.; Liu, Zhen; Pemen, A.J.M.; Heesch, van E.J.M.; Yan, K.; Veldhuizen, van E.M.

    2006-01-01

    In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of

  18. Heat exchanger tube tool

    International Nuclear Information System (INIS)

    Gugel, G.

    1976-01-01

    Certain types of heat-exchangers have tubes opening through a tube sheet to a manifold having an access opening offset from alignment with the tube ends. A tool for inserting a device, such as for inspection or repair, is provided for use in such instances. The tool is formed by a flexible guide tube insertable through the access opening and having an inner end provided with a connector for connection with the opening of the tube in which the device is to be inserted, and an outer end which remains outside of the chamber, the guide tube having adequate length for this arrangement. A flexible transport hose for internally transporting the device slides inside of the guide tube. This hose is long enough to slide through the guide tube, into the heat-exchanger tube, and through the latter to the extent required for the use of the device. The guide tube must be bent to reach the end of the heat-exchanger tube and the latter may be constructed with a bend, the hose carrying anit-friction elements at interspaced locations along its length to make it possible for the hose to negotiate such bends while sliding to the location where the use of the device is required

  19. 49 CFR 236.74 - Protection of insulated wire; splice in underground wire.

    Science.gov (United States)

    2010-10-01

    ... underground wire. 236.74 Section 236.74 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING... wire; splice in underground wire. Insulated wire shall be protected from mechanical injury. The...

  20. 49 CFR 234.241 - Protection of insulated wire; splice in underground wire.

    Science.gov (United States)

    2010-10-01

    ... underground wire. 234.241 Section 234.241 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION GRADE CROSSING SIGNAL SYSTEM SAFETY... of insulated wire; splice in underground wire. Insulated wire shall be protected from mechanical...

  1. Detection of a buried wire with two resistively loaded wire antennas

    NARCIS (Netherlands)

    Vossen, S.H.J.A.; Tijhuis, A.G.; Lepelaars, E.S.A.M.; Zwamborn, A.P.M.

    2002-01-01

    The use of two identical straight thin-wire antennas for the detection of a buried wire is analyzed with the aid of numerical calculations. The buried wire is located below an interface between two homogeneous half-spaces. The detection setup, which is formed by a transmitting and a receiving wire,

  2. One century of Kirschner wires and Kirschner wire insertion techniques : A historical review

    NARCIS (Netherlands)

    Franssen, Bas B. G. M.; Schuurman, Arnold H.; Van der Molen, Aebele Mink; Kon, Moshe

    A century ago, in 1909, Martin Kirschner (1879-942) introduced a smooth pin, presently known as the Kirschner wire (K-wire). The K-wire was initiallly used for skeletal traction and is now currently used for many different goals. The development of the K-wire and its insertion devices were mainly

  3. Pre-wired systems prove their worth.

    Science.gov (United States)

    2012-03-01

    The 'new generation' of modular wiring systems from Apex Wiring Solutions have been specified for two of the world's foremost teaching hospitals - the Royal London and St Bartholomew's Hospital, as part of a pounds sterling 1 billion redevelopment project, to cut electrical installation times, reduce on-site waste, and provide a pre-wired, factory-tested, power and lighting system. HEJ reports.

  4. 49 CFR 393.28 - Wiring systems.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Wiring systems. 393.28 Section 393.28 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY... NECESSARY FOR SAFE OPERATION Lamps, Reflective Devices, and Electrical Wiring § 393.28 Wiring systems...

  5. Getting "Wired" for McLuhan's Cyberculture.

    Science.gov (United States)

    McMurdo, George

    1995-01-01

    Examines the introduction of the computing magazine, "Wired", into the United Kingdom's (UK) market. Presents conversations with the founder and editorial staff of the UK edition, and discusses the accessibility of "Wired" via the World Wide Web. Describes 10 articles from United States "Wired" back-issues and…

  6. Intercostal drainage tube or intracardiac drainage tube?

    Directory of Open Access Journals (Sweden)

    N Anitha

    2016-01-01

    Full Text Available Although insertion of chest drain tubes is a common medical practice, there are risks associated with this procedure, especially when inexperienced physicians perform it. Wrong insertion of the tube has been known to cause morbidity and occasional mortality. We report a case where the left ventricle was accidentally punctured leading to near-exsanguination. This report is to highlight the need for experienced physicians to supervise the procedure and train the younger physician in the safe performance of the procedure.

  7. Intercostal drainage tube or intracardiac drainage tube?

    Science.gov (United States)

    Anitha, N; Kamath, S Ganesh; Khymdeit, Edison; Prabhu, Manjunath

    2016-01-01

    Although insertion of chest drain tubes is a common medical practice, there are risks associated with this procedure, especially when inexperienced physicians perform it. Wrong insertion of the tube has been known to cause morbidity and occasional mortality. We report a case where the left ventricle was accidentally punctured leading to near-exsanguination. This report is to highlight the need for experienced physicians to supervise the procedure and train the younger physician in the safe performance of the procedure.

  8. NEI You Tube Videos: Amblyopia

    Medline Plus

    Full Text Available ... YouTube Videos » NEI YouTube Videos: Amblyopia Listen NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration ... Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Embedded video for NEI YouTube Videos: ...

  9. State of the Art Power-in Tube Niobium-Tin Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Godeke, A.; Ouden, A. Den; Nijhuis, A.; ten Kate, H.H.J.

    2008-06-01

    Powder-in-Tube (PIT) processed Niobium-Tin wires are commercially manufactured for nearly three decades and have demonstrated a combination of very high current density (presently up to 2500 A mm{sup -2} non-Cu at 12 T and 4.2 K) with fine (35 {micro}m), well separated filaments. We review the developments that have led to the present state of the art PIT Niobium-Tin wires, discuss the wire manufacturing and A15 formation processes, and describe typical superconducting performance in relation to magnetic field and strain. We further highlight successful applications of PIT wires and conclude with an outlook on possibilities for further improvements in the performance of PIT Niobium-Tin wires.

  10. Drift chambers on the basis of mylar tubing blocks

    International Nuclear Information System (INIS)

    Budagov, Yu.A.; Golovanov, L.B.; Kuritsin, A.A.; Pukhov, O.E.; Khazins, D.M.; Chirikov-Zorin, I.E.; Joint Inst. for Nuclear Research, Dubna; Zhukov, V.Yu.

    1992-01-01

    We tested the models of the drift chambers, which are constructed of mylar tubing blocks. The purpose of the tubing block forming technology is to create long chambers (up to 3-4 meters). There are count and drift characteristics of the chambers for different gas pressures and different diameters of sense wires. The service time of the chambers is defined. We registered a photoeffect in the visible spectrum area, which is displayed on the surface of the mylar film cathode, covered by aluminium. 8 refs.; 5 figs

  11. Performance of a lead radiator, gas tube calorimeter

    International Nuclear Information System (INIS)

    Spiegel, L.; Arenton, M.; Chen, T.Y.

    1989-01-01

    Design and performance of a 4.2 radiation length lead-sandwich, gas tube hodoscope are discussed. The device, measuring 1 /times/ 2 m 2 in area and 12 cm in depth, was employed in Fermi National Accelerator Laboratory experiment 705. Multiple samplings of anode wires situated within three-walled aluminum tubes were used to generate an X coordinate; similarly, capacitively coupled copper-clad strips were ganged together to yield a Y coordinate. The results reviewed are based on an analysis of electron calibration data taken during a recent six-month running period. In particular, position resolution (in millimeters) is seen to be 0.8 + 3.3/√E + 31/E for the 9.92 mm spaced wires and 0.6 + 3.2/√E + 32/E for the 12.5 mm strips, where E represents the electron beam energy in GeV. 5 refs., 6 figs

  12. Method and device for demounting in a radiation detector a photomultiplier tube

    International Nuclear Information System (INIS)

    Persyk, D.E.; Stoub, E.W.

    1986-01-01

    A device is described for demounting in a radiation detector a photomultiplier tube which is bonded with its scintillation crystal assembly by means of an elastic light transparent adhesive, comprising: (a) a music wire of about 0.01 to 0.03 inch diameter which forms a noose between its wire ends, the noose being provided for being placed aroung the bond; and (b) twisting means connected with both wire ends for twisting them such that the noose becomes smaller thereby sharing the bond

  13. Multisource least-squares migration of marine streamer and land data with frequency-division encoding

    KAUST Repository

    Huang, Yunsong; Schuster, Gerard T.

    2012-01-01

    Multisource migration of phase-encoded supergathers has shown great promise in reducing the computational cost of conventional migration. The accompanying crosstalk noise, in addition to the migration footprint, can be reduced by least-squares inversion. But the application of this approach to marine streamer data is hampered by the mismatch between the limited number of live traces/shot recorded in the field and the pervasive number of traces generated by the finite-difference modelling method. This leads to a strong mismatch in the misfit function and results in strong artefacts (crosstalk) in the multisource least-squares migration image. To eliminate this noise, we present a frequency-division multiplexing (FDM) strategy with iterative least-squares migration (ILSM) of supergathers. The key idea is, at each ILSM iteration, to assign a unique frequency band to each shot gather. In this case there is no overlap in the crosstalk spectrum of each migrated shot gather m(x, ω i), so the spectral crosstalk product m(x, ω i)m(x, ω j) =δ i, j is zero, unless i=j. Our results in applying this method to 2D marine data for a SEG/EAGE salt model show better resolved images than standard migration computed at about 1/10 th of the cost. Similar results are achieved after applying this method to synthetic data for a 3D SEG/EAGE salt model, except the acquisition geometry is similar to that of a marine OBS survey. Here, the speedup of this method over conventional migration is more than 10. We conclude that multisource migration for a marine geometry can be successfully achieved by a frequency-division encoding strategy, as long as crosstalk-prone sources are segregated in their spectral content. This is both the strength and the potential limitation of this method. © 2012 European Association of Geoscientists & Engineers.

  14. Stable isotope labeling confirms mixotrophic nature of streamer biofilm communities at alkaline hot springs

    Directory of Open Access Journals (Sweden)

    Florence eSchubotz

    2015-02-01

    Full Text Available Streamer biofilm communities (SBC are often observed within chemosynthetic zones of Yellowstone hot spring outflow channels, where temperatures exceed those conducive to photosynthesis. Nearest the hydrothermal source (75-88°C SBC comprise thermophilic Archaea and Bacteria, often mixed communities including Desulfurococcales and uncultured Crenarchaeota, as well as Aquificae, Thermus, each carrying diagnostic membrane lipid biomarkers. We tested the hypothesis that SBC can alternate their metabolism between autotrophy and heterotrophy depending on substrate availability. Feeding experiments were performed at two alkaline hot springs in Yellowstone National Park: Octopus Spring and ‘Bison Pool’, using various 13C-labeled substrates (bicarbonate, formate, acetate and glucose to determine the relative uptake of these different carbon sources. Highest 13C uptake, at both sites, was from acetate into almost all bacterial fatty acids, particularly into methyl-branched C15, C17 and C19 fatty acids that are diagnostic for Thermus/Meiothermus and some Firmicutes as well as into universally common C16:0 and C18:0 fatty acids. 13C-glucose showed a similar, but a 10 to 30 times lower uptake across most fatty acids. 13C bicarbonate uptake, signifying the presence of autotrophic communities was only significant at ‘Bison Pool’ and was observed predominantly in non-specific saturated C16, C18, C20 and C22 fatty acids. Incorporation of 13C-formate occurred only at very low rates at ‘Bison Pool’ and was almost undetectable at Octopus Spring, suggesting that formate is not an important carbon source for SBC. 13C uptake into archaeal lipids occurred predominantly with 13C acetate, suggesting also that archaeal communities at both springs have primarily heterotrophic carbon assimilation pathways. We hypothesize that these communities are energy-limited and predominantly nurtured by input of exogenous organic material, with only a small fraction being

  15. Multisource least-squares migration of marine streamer and land data with frequency-division encoding

    KAUST Repository

    Huang, Yunsong

    2012-05-22

    Multisource migration of phase-encoded supergathers has shown great promise in reducing the computational cost of conventional migration. The accompanying crosstalk noise, in addition to the migration footprint, can be reduced by least-squares inversion. But the application of this approach to marine streamer data is hampered by the mismatch between the limited number of live traces/shot recorded in the field and the pervasive number of traces generated by the finite-difference modelling method. This leads to a strong mismatch in the misfit function and results in strong artefacts (crosstalk) in the multisource least-squares migration image. To eliminate this noise, we present a frequency-division multiplexing (FDM) strategy with iterative least-squares migration (ILSM) of supergathers. The key idea is, at each ILSM iteration, to assign a unique frequency band to each shot gather. In this case there is no overlap in the crosstalk spectrum of each migrated shot gather m(x, ω i), so the spectral crosstalk product m(x, ω i)m(x, ω j) =δ i, j is zero, unless i=j. Our results in applying this method to 2D marine data for a SEG/EAGE salt model show better resolved images than standard migration computed at about 1/10 th of the cost. Similar results are achieved after applying this method to synthetic data for a 3D SEG/EAGE salt model, except the acquisition geometry is similar to that of a marine OBS survey. Here, the speedup of this method over conventional migration is more than 10. We conclude that multisource migration for a marine geometry can be successfully achieved by a frequency-division encoding strategy, as long as crosstalk-prone sources are segregated in their spectral content. This is both the strength and the potential limitation of this method. © 2012 European Association of Geoscientists & Engineers.

  16. An investigation into preparation of silver sheathed superconducting wires with a high critical temperature

    International Nuclear Information System (INIS)

    Chaffron, Laurent

    1992-01-01

    We have shown that the critical current density of YBaCuO superconducting wires prepared using 'powder in tube' method is limited by the following principal factors: - cracks and porosity arising from the shrinkage of the powder during sintering, - irregularities in the wire section, - presence of secondary phases in the phase diagram of the three oxides, - incomplete re-oxidation at the centre of the wire, - insufficient, or complete lack of, texture in the wire, - presence of amorphous, non superconducting phase across the grains that blocks grain boundary migration. We have reduced the deleterious effects due to the first four factors by modifying prior nature of the powder, by reinforcing the sheath and by modifying the thermal treatments. We also used creep sintering to produce a strong texture; however, our study shows that texture, though necessary, is not a sufficient condition for a high current. This is because the latter is limited by the presence of the amorphous phase at too many grain boundaries. Finally, we have obtained wires in which grain boundaries are clean and which have very high critical currents by melting the wire in a thermal gradient and by passing it through the gradient very slowly. Such a technique, however, is too slow for producing superconductors. (author) [fr

  17. Control of core structure in MgB{sub 2} wire through tailoring boron powder

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Minoru, E-mail: maeda.minoru70@nihon-u.ac.jp [Department of Physics, College of Science and Technology, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Uchiyama, Daisuke [Department of Physics, College of Science and Technology, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Hossain, Md Shahriar Al; Ma, Zongqing [Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Shahabuddin, Mohammed [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Kim, Jung Ho, E-mail: jhk@uow.edu.au [Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia)

    2015-07-05

    Highlights: • The typical void structure in the wire is obtained by using large-sized B powder. • In contrast, void alignment can be achieved by using fine B powder. • The sintering at lower temperatures improves the critical current density in fields. - Abstract: A common fabrication process for MgB{sub 2} wire, namely, the in situ powder-in-tube process, forms numerous voids within the wire core, and void formation cannot be completely avoided. The orientation is, however, known to be aligned more or less along the current-flow direction when ductile coarse magnesium powder is used as a precursor, and further tailoring approaches could open up the way to improving the transport critical current density. Herein, we have used boron powders with different particle sizes, in combination with the coarse magnesium powder, and evaluated their size effects on the phase composition, microstructure, and transport properties. A mixture of the coarse magnesium powder with large-sized boron powder in the wire core, after cold working and sintering, forms a granular morphology. In contrast, an aligned core appears during the reduction process for wire which is prepared by using fine boron powder. The sintering process, especially at a low temperature, where magnesium evaporation hardly occurs, yields an aligned structure, mainly consisting of MgB{sub 2} phase, along the wire direction. These findings demonstrate that the initial size of the starting materials is critical for the tailored structure.

  18. Pediatric cuffed endotracheal tubes

    Directory of Open Access Journals (Sweden)

    Neerja Bhardwaj

    2013-01-01

    Full Text Available Endotracheal intubation in children is usually performed utilizing uncuffed endotracheal tubes for conduct of anesthesia as well as for prolonged ventilation in critical care units. However, uncuffed tubes may require multiple changes to avoid excessive air leak, with subsequent environmental pollution making the technique uneconomical. In addition, monitoring of ventilatory parameters, exhaled volumes, and end-expiratory gases may be unreliable. All these problems can be avoided by use of cuffed endotracheal tubes. Besides, cuffed endotracheal tubes may be of advantage in special situations like laparoscopic surgery and in surgical conditions at risk of aspiration. Magnetic resonance imaging (MRI scans in children have found the narrowest portion of larynx at rima glottides. Cuffed endotracheal tubes, therefore, will form a complete seal with low cuff pressure of <15 cm H 2 O without any increase in airway complications. Till recently, the use of cuffed endotracheal tubes was limited by variations in the tube design marketed by different manufacturers. The introduction of a new cuffed endotracheal tube in the market with improved tracheal sealing characteristics may encourage increased safe use of these tubes in clinical practice. A literature search using search words "cuffed endotracheal tube" and "children" from 1980 to January 2012 in PUBMED was conducted. Based on the search, the advantages and potential benefits of cuffed ETT are reviewed in this article.

  19. 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.

  20. Clinical bending of nickel titanium wires

    Directory of Open Access Journals (Sweden)

    Stephen Chain

    2015-01-01

    Full Text Available Since the evolution and the involvement of Nickel Titanium wires in the field of Orthodontics. The treatment plan has evolved with the use of low force Nickel Titanium wires. Because of their high springback, low stiffness, they are the key initial wires in leveling and alignment but have poor formability. Since poor formability limits its ability to create variable arch forms thus; limits the form of treatment. We have devised a method to bend the Nickel Titanium wires to help in our inventory but also customized the wire according to the treatment.