WorldWideScience

Sample records for pulsed current transformer

  1. Coaxial pulse matching transformer

    International Nuclear Information System (INIS)

    Ledenev, V.V.; Khimenko, L.T.

    1986-01-01

    This paper describes a coaxial pulse matching transformer with comparatively simple design, increased mechanical strength, and low stray inductance. The transformer design makes it easy to change the turns ratio. The circuit of the device and an expression for the current multiplication factor are presented; experiments confirm the efficiency of the transformer. Apparatus with a coaxial transformer for producing high-power pulsed magnetic fields is designed (current pulses of 1-10 MA into a load and a natural frequency of 100 kHz)

  2. Structural and phase transformations in zinc and brass wires under heating with high-density current pulse

    Energy Technology Data Exchange (ETDEWEB)

    Pervikov, A. V. [Laboratory of Physical Chemistry of Ultrafine Materials, Institute of Strength Physics and Materials Science, 2/4, pr. Akademicheskii, 634021 Tomsk, Russia and Department of High Voltage Electrophysics and High Current Electronics, Tomsk Polytechnic University, 30 Lenin Avenue, 634050 Tomsk (Russian Federation)

    2016-06-15

    The work is focused on revealing the mechanism of structure and phase transformations in the metal wires under heating with a high-density current pulse (the electric explosion of wires, EEWs). It has been demonstrated on the example of brass and zinc wires that the transition of a current pulse with the density of j ≈ 3.3 × 10{sup 7} A/cm{sup 2} results in homogeneous heating of the crystalline structure of the metal/alloy. It has been determined that under heating with a pulse of high-density current pulse, the electric resistance of the liquid phases of zinc and brass decreases as the temperature increases. The results obtained allow for a conclusion that the presence of the particles of the condensed phase in the expanding products of EEW is the result of overheating instabilities in the liquid metal.

  3. Designs of pulsed power cryogenic transformers

    International Nuclear Information System (INIS)

    Singh, S.K.; Heyne, C.J.; Hackowrth, D.T.; Shestak, E.J.; Eckels, P.W.; Rogers, J.D.

    1988-01-01

    The Westinghouse Electric Corporation has completed designs of three pulsed power cryogenic transformers of three pulsed power cryogenic transformers for the Los Alamos National Laboratory. These transformers will be configured to transfer their stored energy sequentially to an electro-magnetic launcher and form a three-stage power supply. The pulse transformers will act as two winding energy storage solenoids which provide a high current and energy pulse compression by transforming a 50 kA power supply into a megamp level power supply more appropriate for the electromagnetic launcher duty. This system differs from more traditional transformer applications in that significant current levels do not exists simultaneously in the two windings of the pulse transformer. This paper describes the designs of the pulsed power cryogenic transformers

  4. Cryogenic pulsed power transformers

    International Nuclear Information System (INIS)

    Rogers, J.D.; Eckels, P.W.; Hackworth, D.T.; Shestak, E.J.; Singh, S.K.

    1988-01-01

    Three liquid nitrogen cooled transformers, two with 14.4 MJ and one with 33.5 MJ storage capacity, are being built to provide respective currents of 0.31 and 0.95 MA to drive a distributed rail gun and are designed to withstand respective voltages of 70 and 200 kV. The transformers are contained in fiberglass reinforced polyester plastic dewars to avoid eddy current coupling and lateral forces that would exist with a metal dewar. To improve the coupling between windings the secondary winding is made relatively thin and is supported structurally for magnetic loading against the outer primary winding. The coils are pool bath cooled. Normal and fault mode analyses indicated safe operation with some precautions for venting nitrogen gas provided

  5. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  6. Digitally compensated beam current transformer

    International Nuclear Information System (INIS)

    Kesselman, Martin

    2005-01-01

    The Spallation Neutron Source (SNS) is being built by a collaboration of six laboratories. Beam current monitors (BCMs) will be used to record the current of H-minus and H-plus beams ranging from 15 mA (tune-up in the Front End and Linac) to over 60A fully accumulated in the Ring and dumped to the load as a single pulse in the Ring to Beam Target (RTBT). The time structure of these beams ranges from 645 ns 'mini' bunches at the 1.05 MHz ring revolution rate, to an overall 1 ms long macro-pulse. The requirements for the BCMs will depend upon their location within the system. The need to measure individual mini-pulses, examine the characteristics of the chopper edge, as well as the longer average current pulse of the macropulse, or long duration pulses during Linac tuning place wide requirements upon the response of current transformers. To obtain the desired accuracy and resolution, current transformers must have <1 ns rise time and droops of 0.1%/ms. This places a significant design burden on the current transformer; such a design is almost impossible to achieve. Extremely large expensive cores are needed to meet the low droop, while leakage inductance increases with size, thereby reducing the achievable rise time. In this paper, I discuss a digital compensation approach [M. Kesselman, Spallation neutron source beam current monitor electronics, PAC2001 June 18-22, 2001, Chicago, IL.] that extends the lower cut-off frequency of the current transformer, optimized for high frequency response, so that it can be used in this application with improvements in droop of the order of 1000:1. Transformer saturation (current-time product) is a separate issue and the transformer must be designed to handle the current-time product of the signal to assure it does not saturate

  7. Current Extensions on PULSE

    Directory of Open Access Journals (Sweden)

    Sanda Dragos

    2010-09-01

    Full Text Available Using a learning management system (LMS is a common practise nowadays. Such instruments are used in educational institutions to enhance and support the teaching act as well as in industry for training purposes. In a computer science department of an university such instrument tends to be a basic requirement. That is because not only it allows a better management of courses and a better communication between students and professors, but can also serve as a perfect instrument for presenting teaching related materials for computer science subjects. During the years I have created and used several such instruments: a System with Interactive ackNowledgement and Evaluation of students work during laboratory sessions (SINE, a Php Utility used in Laboratories for Student Evaluation (PULSE, and PULSE Extended. The aim of this paper is to present the current enhancements of PULSE.

  8. Pulsed current generator

    International Nuclear Information System (INIS)

    Semenov, V.D.; Furman, Eh.G.

    1974-01-01

    The paper describes a current pulse generator with an auxiliary network consisting of a choke and diode in series designed to enlarge the range of pulse frequency control. One output of the network is connected to an adjustable valve cathode and via antoher auxiliary condenser to the point where the cathode of the main key unit is joined to the start of the magnetizing coil. A second output is connected to the anode of another adjustable valve and via another auxiliary condenser to the point where the anode of the other main key unit is joined to the end of the magnetizing coil. The generator can be used to excite the electromagnets of charged particle accelerators or in devices designed to produce magnetic fields. (author)

  9. Rapid testing of pulse transformers

    Science.gov (United States)

    Grillo, J.

    1980-01-01

    Quality-control testing of pulse transformers is speeded up by method for determining rise time and droop. Instead of using oscilloscope and square-wave generator to measure these characteristics directly, method uses voltmeter and sine-wave generator to measure them indirectly in about one-tenth time. Droop and rise time are determined by measuring input/output voltage ratio at just four frequencies.

  10. High current transistor pulse generator

    International Nuclear Information System (INIS)

    Nesterov, V.; Cassel, R.

    1991-05-01

    A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs

  11. Linear transformer driver for pulse generation

    Science.gov (United States)

    Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

    2015-04-07

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

  12. Development of the pulse transformer for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Koontz, R.; Krasnykh, A.

    1997-05-01

    We have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests are also presented

  13. Pulse transformer R and D for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

    1997-07-01

    The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented

  14. Quantitative pulsed eddy current analysis

    International Nuclear Information System (INIS)

    Morris, R.A.

    1975-01-01

    The potential of pulsed eddy current testing for furnishing more information than conventional single-frequency eddy current methods has been known for some time. However, a fundamental problem has been analyzing the pulse shape with sufficient precision to produce accurate quantitative results. Accordingly, the primary goal of this investigation was to: demonstrate ways of digitizing the short pulses encountered in PEC testing, and to develop empirical analysis techniques that would predict some of the parameters (e.g., depth) of simple types of defect. This report describes a digitizing technique using a computer and either a conventional nuclear ADC or a fast transient analyzer; the computer software used to collect and analyze pulses; and some of the results obtained. (U.S.)

  15. Design of pulse transformers for PFL charging

    International Nuclear Information System (INIS)

    Rohwein, G.J.

    1979-01-01

    Air core pulse transformers powered by low voltage capacitor banks can be simple efficient systems for charging high-voltage (0.5 to 3 MV), pulse forming transmission lines (PFL) such as those used in electron and ion beam accelerators. In these applications pulse transformers must have the combined capability of high voltage endurance and high energy transfer efficiency, particularly in repetitive pulse systems where these features are of primary importance. The design of shielded, high-voltage, spiral, strip transformers which fulfill these requirements is described in this paper. Transformers of this type have been tested in three systems which operate with greater than 90% transfer efficiency and have not failed in over 10 7 shots

  16. Neutron induced current pulses in fission chambers

    International Nuclear Information System (INIS)

    Taboas, A.L.; Buck, W.L.

    1978-01-01

    The mechanism of neutron induced current pulse generation in fission chambers is discussed. By application of the calculated detector transfer function to proposed detector current pulse shapes, and by comparison with actually observed detector output voltage pulses, a credible, semi-empirical, trapezoidal pulse shape of chamber current is obtained

  17. Optimum transformer design for a pulsed power system

    International Nuclear Information System (INIS)

    Broverman, A.Y.

    1987-11-01

    Electromagnetic forces resulting from peak pulsed current require special design consideration to prevent failure of the coils of the transformer. Procedures for interleaving transformer windings to reduce both electromagnetic short-circuit forces and reactive voltage drop while reducing procurement costs are described. The basics of transformer design principles and cost trade-offs are included to enhance understanding of the interleaving procedures. 3 refs., 3 figs

  18. The behavior of dissolution/passivation and the transformation of passive films during electrocoagulation: Influences of initial pH, Cr(VI) concentration, and alternating pulsed current

    International Nuclear Information System (INIS)

    Yang, Zhao-hui; Xu, Hai-yin; Zeng, Guang-ming; Luo, Yuan-ling; Yang, Xia; Huang, Jing; Wang, Li-ke; Song, Pei-pei

    2015-01-01

    Highlights: • Initial pH, Cr(VI) and APC could affect the behavior of dissolution/passivation in Fe-EC. • A dissolution/passivation region was constructed with different initial pH-Cr(VI). • The film was rich in Fe and Cr at high Cr(VI), whereas with lots of Fe but negligible of Cr at low Cr(VI). • The film was non-protective at long T APC , but became more stable and protective at short T APC . • Behavior of dissolution/passivation and passive film transformation in Fe-EC was elucidated. - Abstract: The passivation behavior of an iron anode for electrocoagulation (EC) was first investigated using response surface methodology (RSM). Tested initial pH range, Cr(VI) concentration and alternating pulsed current (APC) were 4.0 to 8.0, 52 to 520 mg L −1 and 10 to 590 s, respectively. The distance between electrodes was 25 mm, and K 2 SO 4 (1 g L −1 ) was used as the supporting electrolyte in a 2.5 L EC reactor. Results confirmed that initial pH, Cr(VI) concentration, and APC significantly influence the extent of passivation. Then, based on the interaction effect on passivation behavior between initial pH and Cr(VI) in RSM, a pH-Cr(VI)-dissolution/passivation diagram was constructed with galvanostatic measurements. The diagram showed an optimal dissolution region for EC operation. This optimum was characterized by a reasonable final pH for extended precipitation and little passivation. Results of the cyclic voltammetry and X-ray photoelectron spectroscopy revealed a significant difference in the composition and stability of oxide films in the region with more pronounced passivation. Interestingly, the APC had both positive and negative effect on the passivation behavior. Long period of APC (T APC = 590 s) produced a non-protective film, which favored the Fe 0 dissolution. However, a more stable and protective passive film with a uniform structure of Fe and Cr oxides was formed by short T APC (10 s). Based on the above results, this study elucidated the

  19. Modelling the pulse transformer in SPICE

    International Nuclear Information System (INIS)

    Godlewska, Malgorzata; Górecki, Krzysztof; Górski, Krzysztof

    2016-01-01

    The paper is devoted to modelling pulse transformers in SPICE. It shows the character of the selected models of this element, points out their advantages and disadvantages, and presents the results of experimental verification of the considered models. These models are characterized by varying degrees of complexity - from linearly coupled linear coils to nonlinear electrothermal models. The study was conducted for transformer with ring cores made of a variety of ferromagnetic materials, while exciting the sinusoidal signal of a frequency 100 kHz and different values of load resistance. The transformers operating conditions under which the considered models ensure the acceptable accuracy of calculations are indicated

  20. DC-Compensated Current Transformer.

    Science.gov (United States)

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-20

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.

  1. Pulse transformer for the AA lithium lens

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    The antiprotons emanating from the target were initially focused by a magnetic horn. Later on, a Li-lens was used during operation for the SPS collider, until 1992. A Li-rod (130 mm long, 34 mm in diameter) constituted the secondary of a 1:23 pulse-transformer. The half-sine pulse rose to 1000 kA in 900 microsec. The angular acceptance was 95 mrad. In operation after 1992, for LEAR only, a more modest Li-lens was used (155 mm long, diameter 20 mm, 480 kA, risetime 240 microsec, angular acceptance 75 mrad).

  2. High current high accuracy IGBT pulse generator

    International Nuclear Information System (INIS)

    Nesterov, V.V.; Donaldson, A.R.

    1995-05-01

    A solid state pulse generator capable of delivering high current triangular or trapezoidal pulses into an inductive load has been developed at SLAC. Energy stored in a capacitor bank of the pulse generator is switched to the load through a pair of insulated gate bipolar transistors (IGBT). The circuit can then recover the remaining energy and transfer it back to the capacitor bank without reversing the capacitor voltage. A third IGBT device is employed to control the initial charge to the capacitor bank, a command charging technique, and to compensate for pulse to pulse power losses. The rack mounted pulse generator contains a 525 μF capacitor bank. It can deliver 500 A at 900V into inductive loads up to 3 mH. The current amplitude and discharge time are controlled to 0.02% accuracy by a precision controller through the SLAC central computer system. This pulse generator drives a series pair of extraction dipoles

  3. High current pulsed positron microprobe

    International Nuclear Information System (INIS)

    Howell, R.H.; Stoeffl, W.; Kumar, A.; Sterne, P.A.; Cowan, T.E.; Hartley, J.

    1997-01-01

    We are developing a low energy, microscopically focused, pulsed positron beam for defect analysis by positron lifetime spectroscopy to provide a new defect analysis capability at the 10 10 e + s -l beam at the Lawrence Livermore National Laboratory electron linac. When completed, the pulsed positron microprobe will enable defect specific, 3-dimensional maps of defect concentrations with sub-micron resolution of defect location. By coupling these data with first principles calculations of defect specific positron lifetimes and positron implantation profiles we will both map the identity and concentration of defect distributions

  4. Local eddy current measurements in pulsed fields

    Energy Technology Data Exchange (ETDEWEB)

    Espina-Hernandez, J.H. [SEPI-Electronica, ESIME-IPN, UPALM Edif. ' Z' . Zacatenco, Mexico DF 07738 (Mexico)], E-mail: jhespina@gmail.com; Groessinger, R. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria); Hallen, J.M. [Departamento de Ingenieria Metalurgica, IPN-ESIQIE, UPALM Edif. 7, Zacatenco, Mexico DF 07738 (Mexico)

    2008-07-15

    This work presents new eddy current measurements in pulsed fields. A commercial point pick-up coil is used to detect the induction signal along the radius of Cu and Al samples with cylindrical shape and diameters between 5 and 35 mm. Local eddy current measurements were performed on the surface of conducting materials due to the small dimensions of the coil. A simple electrical circuit, used as a model, is proposed to describe the local eddy current effect in pulsed fields. The proposed model allows to calculate the phase shift angle between the signal proportional to eddy currents and the applied external field in a pulsed field magnetometer.

  5. Adjustable direct current and pulsed circuit fault current limiter

    Science.gov (United States)

    Boenig, Heinrich J.; Schillig, Josef B.

    2003-09-23

    A fault current limiting system for direct current circuits and for pulsed power circuit. In the circuits, a current source biases a diode that is in series with the circuits' transmission line. If fault current in a circuit exceeds current from the current source biasing the diode open, the diode will cease conducting and route the fault current through the current source and an inductor. This limits the rate of rise and the peak value of the fault current.

  6. Study of 18-Pulse Rectifier Utilizing Hexagon Connected 3-Phase to 9-Phase Transformer

    Directory of Open Access Journals (Sweden)

    Ahmad Saudi Samosir

    2008-04-01

    Full Text Available The 18-pulse converter, using Y or -connected differential autotransformer, is very interesting since it allows natural high power factor correction. The lowest input current harmonic components are the 17th and 19th. The Transformer is designed to feed three six-pulse bridge rectifiers displaced in phase by 200. This paper present a high power factor three-phase rectifier bases on 3-phase to 9-phase transformer and 18-pulse rectifier. The 9-phase polygon-connected transformer followed by 18-pulse diode rectifiers ensures the fundamental concept of natural power factor correction. Simulation results to verify the proposed concept are shown in this paper.

  7. High-current pulses from inductive energy stores

    International Nuclear Information System (INIS)

    Wipf, S.L.

    1981-01-01

    Superconducting inductive energy stores can be used for high power pulse supplies if a suitable current multiplication scheme is used. The concept of an inductive Marx generator is superior to a transformer. A third scheme, a variable flux linkage device, is suggested; in multiplying current it also compresses energy. Its function is in many ways analogous to that of a horsewhip. Superconductor limits indicate that peak power levels of TW can be reached for stored energies above 1 MJ

  8. Eddy currents in pulsed field measurements

    International Nuclear Information System (INIS)

    Kuepferling, M.; Groessinger, R.; Wimmer, A.; Taraba, M.; Scholz, W.

    2002-01-01

    Full text: One problem of pulsed field magnetometry is an error in magnetization, which appears in measurements of conducting samples. This error is due to eddy currents induced by a time varying field. To allow predictions how eddy currents exert influence on the hysteresis loop, systematic experimental and theoretical studies of pulsed field measurements of metallic samples were performed. The theoretical studies include analytical calculations as well as numerical ones using a 2D finite element software. In the measurements three physical parameters have been varied: i) the conductivity of the sample by using two different materials, in this case technical Cu and Al ii) size and shape of the sample by using cylinders, spheres and cuboids iii) the pulse duration of the external field by changing the capacitor battery from 8mF ( =9.1ms) to 24mF ( =15.7ms). The time dependence of the external field corresponds with a pulsed damped harmonic oscillation with a maximum value of 5.2T. The samples were studied in the as cast state (after machining) as well as after heat treatment. Theoretical calculations showed not only good agreement with the absolute values of the measured eddy current m agnetization , they also gave an explanation of the shape of the eddy current hysteresis and the dependence of the eddy current 'magnetization' on parameters as pulse duration of the external field and conductivity of the sample. (author)

  9. Influence of Current Transformer Saturation on Operation of Current Protection

    Directory of Open Access Journals (Sweden)

    F. A. Romaniouk

    2010-01-01

    Full Text Available An analysis of the influence of instrument current transformer errors on operation of current protection of power supply diagram elements has been carried out in the paper. The paper shows the influence of an aperiodic component of transient current and secondary load on current  transformer errors.Peculiar operational features of measuring elements of electromechanical and microprocessor current protection with their joint operation with electromagnetic current transformers have been analyzed in the paper.

  10. Current pulse shaping of the load current on PTS

    Directory of Open Access Journals (Sweden)

    Minghe Xia

    2016-02-01

    Full Text Available The typical rise time of PTS machine is ∼110 ns with about 10 MA peak current under short pulse mode when all 24 modules discharge simultaneously. By distributing the trigger times of 12 laser beams logically and adjusting the statues of the pulse output switches, longer rise-time pulse can be obtained on the PTS facility. Based on the required pulse shape, whole circuit simulations will be used to calculate the trigger times of each laser triggering gas switch and the status of the pulse output switches. The rise time of the current is determined by the time difference between the first and last trigged laser triggering gas switches. In order to trigger the laser triggering gas switch, sufficient laser power is needed to be sent into the gap of the gas switches. The gas pressure and voltage difference on the two electrodes of the gas switches also affect the triggering of the gas switches, and the voltage added on the gas switch is determined by its transition time. Traditionally the trigger time difference should be less than the transition time of the two neighboring modules. A new simulation model of PTS shows one can break this transition time limits. Series of current pulse shaping experiments have been investigated on the PTS (Primary Test Stand. As results, more than 5 MA peak current were successfully achieved on the load with a rise time of 600 ns. This study and experiments of the pulse shaping on PTS demonstrate the adaptable ability of the PTS for offering different waveform of mega ampere current pulse for different research purpose.

  11. Pulse current enhanced electrodialytic soil remediation

    DEFF Research Database (Denmark)

    Sun, Tian R.; Ottosen, Lisbeth M.; Jensen, Pernille E.

    2012-01-01

    Energy consumption is an important factor influencing the cost of electrodialytic soil remediation (EDR). It has been indicated that the pulse current (in low frequency range) could decrease the energy consumption during EDR. This work is focused on the comparison of energy saving effect at diffe......Energy consumption is an important factor influencing the cost of electrodialytic soil remediation (EDR). It has been indicated that the pulse current (in low frequency range) could decrease the energy consumption during EDR. This work is focused on the comparison of energy saving effect...

  12. Linear transformer driver for pulse generation with fifth harmonic

    Science.gov (United States)

    Mazarakis, Michael G.; Kim, Alexander A.; Sinebryukhov, Vadim A.; Volkov, Sergey N.; Kondratiev, Sergey S.; Alexeenko, Vitaly M.; Bayol, Frederic; Demol, Gauthier; Stygar, William A.; Leckbee, Joshua; Oliver, Bryan V.; Kiefer, Mark L.

    2017-03-21

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first, second, and third power delivery module. The first power delivery module sends a first energy in the form of a first pulse to the load. The second power delivery module sends a second energy in the form of a second pulse to the load. The third power delivery module sends a third energy in the form of a third pulse to the load. The linear transformer driver is configured to form a flat-top pulse by the superposition of the first, second, and third pulses. The first, second, and third pulses have different frequencies.

  13. CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

    Science.gov (United States)

    Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

    2010-02-01

    An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

  14. Development of 600 kV triple resonance pulse transformer.

    Science.gov (United States)

    Li, Mingjia; Zhang, Faqiang; Liang, Chuan; Xu, Zhou

    2015-06-01

    In this paper, a triple-resonance pulse transformer based on an air-core transformer is introduced. The voltage across the high-voltage winding of the air-core transformer is significantly less than the output voltage; instead, the full output voltage appears across the tuning inductor. The maximum ratio of peak load voltage to peak transformer voltage is 2.77 in theory. By analyzing pulse transformer's lossless circuit, the analytical expression for the output voltage and the characteristic equation of the triple-resonance circuit are presented. Design method for the triple-resonance pulse transformer (iterated simulation method) is presented, and a triple-resonance pulse transformer is developed based on the existing air-core transformer. The experimental results indicate that the maximum ratio of peak voltage across the load to peak voltage across the high-voltage winding of the air-core transformer is approximately 2.0 and the peak output voltage of the triple-resonance pulse transformer is approximately 600 kV.

  15. Frequency analysis of DC tolerant current transformers

    International Nuclear Information System (INIS)

    Mlejnek, P; Kaspar, P

    2013-01-01

    This article deals with wide frequency range behaviour of DC tolerant current transformers that are usually used in modern static energy meters. In this application current transformers must comply with European and International Standards in their accuracy and DC tolerance. Therefore, the linear DC tolerant current transformers and double core current transformers are used in this field. More details about the problems of these particular types of transformers can be found in our previous works. Although these transformers are designed mainly for power distribution network frequency (50/60 Hz), it can be interesting to understand their behaviour in wider frequency range. Based on this knowledge the new generations of energy meters with measuring quality of electric energy will be produced. This solution brings better measurement of consumption of nonlinear loads or measurement of non-sinusoidal voltage and current sources such as solar cells or fuel cells. The determination of actual power consumption in such energy meters is done using particular harmonics component of current and voltage. We measured the phase and ratio errors that are the most important parameters of current transformers, to characterize several samples of current transformers of both types

  16. Pulsed eddy currents: principle and applications

    International Nuclear Information System (INIS)

    Bernard, A.; Coutanceau, N.

    1993-04-01

    Eddy currents are widely used as a non destructive testing technique specially for heat exchanger testing. The specificities of pulsed eddy current testing are analyzed in terms of probe design and signal processing. The specific applications are detailed. They are divided in two parts. First part, deals with the two main applications of the high peak energy supplied to the probe. One concerns the design of focused probes used for the detection of small defects in irradiated fuel rods. The other concerns the saturation of ferromagnetic materials in order to test the full thickness of the exchanger tubes. Second part, deals with applications of the wide and low frequency spectrum generated by the pulse source. It enables the testing of thick materials, and the detection of sub-surface defects. It has been tested on austenitic steel (nuclear pressure vessel nozzle), multilayered structures of aluminium alloys (aeronautics) and sleeved structures (nuclear pressure vessel head penetrations through thermal sleeves)

  17. Electric fields in plasmas under pulsed currents

    International Nuclear Information System (INIS)

    Tsigutkin, K.; Doron, R.; Stambulchik, E.; Bernshtam, V.; Maron, Y.; Fruchtman, A.; Commisso, R. J.

    2007-01-01

    Electric fields in a plasma that conducts a high-current pulse are measured as a function of time and space. The experiment is performed using a coaxial configuration, in which a current rising to 160 kA in 100 ns is conducted through a plasma that prefills the region between two coaxial electrodes. The electric field is determined using laser spectroscopy and line-shape analysis. Plasma doping allows for three-dimensional spatially resolved measurements. The measured peak magnitude and propagation velocity of the electric field is found to match those of the Hall electric field, inferred from the magnetic-field front propagation measured previously

  18. Shaping the output pulse of a linear-transformer-driver module

    International Nuclear Information System (INIS)

    Long, Finis W.; McKee, G. Randall; Stoltzfus, Brian Scott; Woodworth, Joseph Ray; McKenney, John Lee; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John L.; Stygar, William A.; Savage, Mark Edward; LeChien, Keith R.; Van De Valde, David M.

    2008-01-01

    We demonstrate that a wide variety of current-pulse shapes can be generated using a linear-transformer-driver (LTD) module that drives an internal water-insulated transmission line. The shapes are produced by varying the timing and initial charge voltage of each of the module's cavities. The LTD-driven accelerator architecture outlined in (Phys. Rev. ST Accel. Beams 10, 030401 (2007)) provides additional pulse-shaping flexibility by allowing the modules that drive the accelerator to be triggered at different times. The module output pulses would be combined and symmetrized by water-insulated radial-transmission-line impedance transformers (Phys. Rev. ST Accel. Beams 11, 030401 (2008))

  19. Pulsed high current ion beam processing equipment

    International Nuclear Information System (INIS)

    Korenev, S.A.; Perry, A.

    1995-01-01

    A pulsed high voltage ion source is considered for use in ion beam processing for the surface modification of materials, and deposition of conducting films on different substrates. The source consists of an Arkad'ev-Marx high voltage generator, a vacuum ion diode based on explosive ion emission, and a vacuum chamber as substrate holder. The ion diode allows conducting films to be deposited from metal or allow sources, with ion beam mixing, onto substrates held at a pre-selected temperature. The main variables can be set in the ranges: voltage 100-700 kV, pulse length 0.3 μs, beam current 1-200 A depending on the ion chosen. The applications of this technology are discussed in semiconductor, superconductor and metallizing applications as well as the direction of future development and cost of these devices for commercial application. 14 refs., 6 figs

  20. Transformative Pulsed Power Science and Technology

    Science.gov (United States)

    2014-12-16

    al. eds. Plasma for Bio - Martin Gundersen 4 Decontamination, Medicine and Food Security, NATO Science for Peace and Security Series A: Chemistry...Pulsed Energy Field Treatments on White Wine Grapes," in Annual Meeting Poster Session, American Society for Enology and Viticulture , Napa...group at U.C. Davis Dept. of Enology and Viticulture . Martin Gundersen 10 Graduated  PhD  Students  2009-­‐2014     Electrical

  1. A compact high-voltage pulse generator based on pulse transformer with closed magnetic core.

    Science.gov (United States)

    Zhang, Yu; Liu, Jinliang; Cheng, Xinbing; Bai, Guoqiang; Zhang, Hongbo; Feng, Jiahuai; Liang, Bo

    2010-03-01

    A compact high-voltage nanosecond pulse generator, based on a pulse transformer with a closed magnetic core, is presented in this paper. The pulse generator consists of a miniaturized pulse transformer, a curled parallel strip pulse forming line (PFL), a spark gap, and a matched load. The innovative design is characterized by the compact structure of the transformer and the curled strip PFL. A new structure of transformer windings was designed to keep good insulation and decrease distributed capacitance between turns of windings. A three-copper-strip structure was adopted to avoid asymmetric coupling of the curled strip PFL. When the 31 microF primary capacitor is charged to 2 kV, the pulse transformer can charge the PFL to 165 kV, and the 3.5 ohm matched load can deliver a high-voltage pulse with a duration of 9 ns, amplitude of 84 kV, and rise time of 5.1 ns. When the load is changed to 50 ohms, the output peak voltage of the generator can be 165 kV, the full width at half maximum is 68 ns, and the rise time is 6.5 ns.

  2. Spatiotemporal optical pulse transformation by a resonant diffraction grating

    Energy Technology Data Exchange (ETDEWEB)

    Golovastikov, N. V.; Bykov, D. A., E-mail: bykovd@gmail.com; Doskolovich, L. L., E-mail: leonid@smr.ru; Soifer, V. A. [Russian Academy of Sciences, Image Processing Systems Institute (Russian Federation)

    2015-11-15

    The diffraction of a spatiotemporal optical pulse by a resonant diffraction grating is considered. The pulse diffraction is described in terms of the signal (the spatiotemporal incident pulse envelope) passage through a linear system. An analytic approximation in the form of a rational function of two variables corresponding to the angular and spatial frequencies has been obtained for the transfer function of the system. A hyperbolic partial differential equation describing the general form of the incident pulse envelope transformation upon diffraction by a resonant diffraction grating has been derived from the transfer function. A solution of this equation has been obtained for the case of normal incidence of a pulse with a central frequency lying near the guided-mode resonance of a diffraction structure. The presented results of numerical simulations of pulse diffraction by a resonant grating show profound changes in the pulse envelope shape that closely correspond to the proposed theoretical description. The results of the paper can be applied in creating new devices for optical pulse shape transformation, in optical information processing problems, and analog optical computations.

  3. DC-Compensated Current Transformer

    Science.gov (United States)

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-01

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830

  4. A novel approach to determine the interphase transformer inductance of 18 pulse rectifiers

    International Nuclear Information System (INIS)

    Sefa, Ibrahim; Altin, Necmi

    2009-01-01

    The interphase transformer inductance seriously affects the performance of 18 pulse rectifiers. Low inductance values cause non-characteristic harmonics whereas high inductance values increase the rectifier cost and size. Hence, determination of the interphase transformer inductance value is an important problem in the design of 18 pulse rectifiers. In this paper, an approach to determine the optimum inductance value of an interphase transformer is proposed and a practical formula is introduced. The proposed approach has been validated with simulation and experimental studies carried out with designed capacitive loaded autotransformer based 18 pulse rectifier for different IPT inductance values at different load levels. Experimental and simulation results show that cost effective interphase transformer inductance value can be determined with the proposed approach and this value reduces the line current harmonics and improves power factor drastically.

  5. Numerical modeling of transformer inrush currents

    Energy Technology Data Exchange (ETDEWEB)

    Cardelli, E. [Department of Industrial Engineering, University of Perugia, I-06125 Perugia (Italy); Center for Electric and Magnetic Applied Research (Italy); Faba, A., E-mail: faba@unipg.it [Department of Industrial Engineering, University of Perugia, I-06125 Perugia (Italy); Center for Electric and Magnetic Applied Research (Italy)

    2014-02-15

    This paper presents an application of a vector hysteresis model to the prediction of the inrush current due the arbitrary initial excitation of a transformer after a fault. The approach proposed seems promising in order to predict the transient overshoot in current and the optimal time to close the circuit after the fault.

  6. Electronic voltage and current transformers testing device.

    Science.gov (United States)

    Pan, Feng; Chen, Ruimin; Xiao, Yong; Sun, Weiming

    2012-01-01

    A method for testing electronic instrument transformers is described, including electronic voltage and current transformers (EVTs, ECTs) with both analog and digital outputs. A testing device prototype is developed. It is based on digital signal processing of the signals that are measured at the secondary outputs of the tested transformer and the reference transformer when the same excitation signal is fed to their primaries. The test that estimates the performance of the prototype has been carried out at the National Centre for High Voltage Measurement and the prototype is approved for testing transformers with precision class up to 0.2 at the industrial frequency (50 Hz or 60 Hz). The device is suitable for on-site testing due to its high accuracy, simple structure and low-cost hardware.

  7. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network.

    Science.gov (United States)

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

    2014-06-01

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  8. A compact bipolar pulse-forming network-Marx generator based on pulse transformers.

    Science.gov (United States)

    Zhang, Huibo; Yang, Jianhua; Lin, Jiajin; Yang, Xiao

    2013-11-01

    A compact bipolar pulse-forming network (PFN)-Marx generator based on pulse transformers is presented in this paper. The high-voltage generator consisted of two sets of pulse transformers, 6 stages of PFNs with ceramic capacitors, a switch unit, and a matched load. The design is characterized by the bipolar pulse charging scheme and the compact structure of the PFN-Marx. The scheme of bipolar charging by pulse transformers increased the withstand voltage of the ceramic capacitors in the PFNs and decreased the number of the gas gap switches. The compact structure of the PFN-Marx was aimed at reducing the parasitic inductance in the generator. When the charging voltage on the PFNs was 35 kV, the matched resistive load of 48 Ω could deliver a high-voltage pulse with an amplitude of 100 kV. The full width at half maximum of the load pulse was 173 ns, and its rise time was less than 15 ns.

  9. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang, E-mail: zhaoliang0526@163.com; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an, Shaanxi 710024 (China)

    2014-06-15

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  10. A distributed parameter model of transmission line transformer for high voltage nanosecond pulse generation.

    Science.gov (United States)

    Li, Jiangtao; Zhao, Zheng; Li, Longjie; He, Jiaxin; Li, Chenjie; Wang, Yifeng; Su, Can

    2017-09-01

    A transmission line transformer has potential advantages for nanosecond pulse generation including excellent frequency response and no leakage inductance. The wave propagation process in a secondary mode line is indispensable due to an obvious inside transient electromagnetic transition in this scenario. The equivalent model of the transmission line transformer is crucial for predicting the output waveform and evaluating the effects of magnetic cores on output performance. However, traditional lumped parameter models are not sufficient for nanosecond pulse generation due to the natural neglect of wave propagations in secondary mode lines based on a lumped parameter assumption. In this paper, a distributed parameter model of transmission line transformer was established to investigate wave propagation in the secondary mode line and its influential factors through theoretical analysis and experimental verification. The wave propagation discontinuity in the secondary mode line induced by magnetic cores is emphasized. Characteristics of the magnetic core under a nanosecond pulse were obtained by experiments. Distribution and formation of the secondary mode current were determined for revealing essential wave propagation processes in secondary mode lines. The output waveform and efficiency were found to be affected dramatically by wave propagation discontinuity in secondary mode lines induced by magnetic cores. The proposed distributed parameter model was proved more suitable for nanosecond pulse generation in aspects of secondary mode current, output efficiency, and output waveform. In depth, comprehension of underlying mechanisms and a broader view of the working principle of the transmission line transformer for nanosecond pulse generation can be obtained through this research.

  11. Pulse design for multilevel systems by utilizing Lie transforms

    Science.gov (United States)

    Kang, Yi-Hao; Chen, Ye-Hong; Shi, Zhi-Cheng; Huang, Bi-Hua; Song, Jie; Xia, Yan

    2018-03-01

    We put forward a scheme to design pulses to manipulate multilevel systems with Lie transforms. A formula to reverse construct a control Hamiltonian is given and is applied in pulse design in the three- and four-level systems as examples. To demonstrate the validity of the scheme, we perform numerical simulations, which show the population transfers for cascaded three-level and N -type four-level Rydberg atoms can be completed successfully with high fidelities. Therefore, the scheme may benefit quantum information tasks based on multilevel systems.

  12. The Roadmaker's algorithm for the discrete pulse transform.

    Science.gov (United States)

    Laurie, Dirk P

    2011-02-01

    The discrete pulse transform (DPT) is a decomposition of an observed signal into a sum of pulses, i.e., signals that are constant on a connected set and zero elsewhere. Originally developed for 1-D signal processing, the DPT has recently been generalized to more dimensions. Applications in image processing are currently being investigated. The time required to compute the DPT as originally defined via the successive application of LULU operators (members of a class of minimax filters studied by Rohwer) has been a severe drawback to its applicability. This paper introduces a fast method for obtaining such a decomposition, called the Roadmaker's algorithm because it involves filling pits and razing bumps. It acts selectively only on those features actually present in the signal, flattening them in order of increasing size by subtracing an appropriate positive or negative pulse, which is then appended to the decomposition. The implementation described here covers 1-D signal as well as two and 3-D image processing in a single framework. This is achieved by considering the signal or image as a function defined on a graph, with the geometry specified by the edges of the graph. Whenever a feature is flattened, nodes in the graph are merged, until eventually only one node remains. At that stage, a new set of edges for the same nodes as the graph, forming a tree structure, defines the obtained decomposition. The Roadmaker's algorithm is shown to be equivalent to the DPT in the sense of obtaining the same decomposition. However, its simpler operators are not in general equivalent to the LULU operators in situations where those operators are not applied successively. A by-product of the Roadmaker's algorithm is that it yields a proof of the so-called Highlight Conjecture, stated as an open problem in 2006. We pay particular attention to algorithmic details and complexity, including a demonstration that in the 1-D case, and also in the case of a complete graph, the Roadmaker

  13. Transformer current sensor for superconducting magnetic coils

    Science.gov (United States)

    Shen, S.S.; Wilson, C.T.

    1985-04-16

    The present invention is a current transformer for operating currents larger than 2kA (two kiloamps) that is capable of detecting a millivolt level resistive voltage in the presence of a large inductive voltage. Specifically, the present invention includes substantially cylindrical primary turns arranged to carry a primary current and substantially cylindrical secondary turns arranged coaxially with and only partially within the primary turns, the secondary turns including an active winding and a dummy winding, the active and dummy windings being coaxial, longitudinally separated and arranged to mutually cancel voltages excited by commonly experienced magnetic fields, the active winding but not the dummy winding being arranged within the primary turns.

  14. A 70 kV solid-state high voltage pulse generator based on saturable pulse transformer.

    Science.gov (United States)

    Fan, Xuliang; Liu, Jinliang

    2014-02-01

    High voltage pulse generators are widely applied in many fields. In recent years, solid-state and operating at repetitive mode are the most important developing trends of high voltage pulse generators. A solid-state high voltage pulse generator based on saturable pulse transformer is proposed in this paper. The proposed generator is consisted of three parts. They are charging system, triggering system, and the major loop. Saturable pulse transformer is the key component of the whole generator, which acts as a step-up transformer and main switch during working process of this generator. The circuit and working principles of the proposed pulse generator are introduced first in this paper, and the saturable pulse transformer used in this generator is introduced in detail. Circuit of the major loop is simulated to verify the design of the system. Demonstration experiments are carried out, and the results show that when the primary energy storage capacitor is charged to a high voltage, such as 2.5 kV, a voltage with amplitude of 86 kV can be achieved on the secondary winding. The magnetic core of saturable pulse transformer is saturated deeply and the saturable inductance of the secondary windings is very small. The switch function of the saturable pulse transformer can be realized ideally. Therefore, a 71 kV output voltage pulse is formed on the load. Moreover, the magnetic core of the saturable pulse transformer can be reset automatically.

  15. Calculation of secondary capacitance of compact Tesla pulse transformer

    International Nuclear Information System (INIS)

    Yu Binxiong; Liu Jinliang

    2013-01-01

    An analytic expression of the secondary capacitance of a compact Tesla pulse transformer is derived. Calculated result by the expression shows that two parts contribute to the secondary capacitance, namely the capacitance between inner and outer magnetic cores and the attached capacitance caused by the secondary winding. The attached capacitance equals to the capacitance of a coaxial line which is as long as the secondary coil, and whose outer and inner diameters are as large as the inner diameter of the outer magnetic and the outer diameter of the inner magnetic core respectively. A circuital model for analyzing compact Tesla transformer is built, and numeric calculation shows that the expression of the secondary capacitance is correct. Besides, a small compact Tesla transformer is developed, and related test is carried out. Test result confirms the calculated results by the expression derived. (authors)

  16. Study of pulse stretching in high current power supplies using multipulse techniques

    International Nuclear Information System (INIS)

    Trendler, R.C.

    1977-01-01

    Considerable interest exists at Fermilab to increase the pulse width of the Neutrino Focusing Horn to permit an increase in beam spill length from twenty (20) microseconds to one (1) millisecond. Two techniques to do this were examined: (1) a high current transformer, and (2) increased bank capacitance using the multi-power supply technique. The transformer is the most straightforward conceptually; it is, however, a complicated device requiring sizable changes to the existing horn power supply. This alternative is briefly reviewed. The second scheme involves pulsing a 20 kv 200 ka power supply to establish the required load current and then maintaining this current by the sequential pulsing of a number of low voltage high current power supplies. This alternative is discussed in detail with the results of tests performed on the Fermilab Focusing Horn System

  17. Current pulse generator of an induction accelerator electromagnet

    International Nuclear Information System (INIS)

    Baginskij, B.A.; Makarevich, V.N.; Shtejn, M.M.

    1987-01-01

    Thyristor generator forming in betatron electromagnet coil sinusoidal and quasisinusoidal current unipolar pulses, the field being deforced at the beginning of acceleration cycle, and with the pulse flat top in the cycle end, is described. The current amplitude is controlled by pulse-phase method. The current pulse time shift permitted to decrease the loss rate in the accumulating capacitor. The generator is used in systems with 1-10 ms pulse duration, electromagnet magnetic field maximal energy - 45-450 J, the voltage amplitude in the coil 960-1500 V and amplitude of the current passing the coil 100-500 A, the repetition frequency being 50-200 Hz. In particular, the generator is used to supply betatrons designed for defectoscopy in nonstationary conditions, the accelerated electron energy being 4, 6, 8 and 15 MeV

  18. Design criteria for pulse transformers used in neutron detector pulse counting channels

    International Nuclear Information System (INIS)

    Powler, E.P.

    1963-10-01

    The need for long cables between the detector and head amplifier in neutron pulse counting channels has led to the development of systems in which a transformer is used to 'match' the high impedance of a fission or proportional counter to the characteristic impedance of the cable. A further transformer can be used to match the cable to the input of a low noise pulse amplifier if this has a high impedance. This report is intended to give the designer sufficient information to optimise a system and predict the performance in terms of signal to noise ratio, resolving time and gain. Related problems are covered and include the use of balanced twin cables, the requirements of temperatures up to 500 deg. C and the need for high interference rejection. Two systems are described in some detail to emphasise the principles of design. (author)

  19. Reducing the beam current in Linac4 in pulse to pulse mode.

    CERN Document Server

    Lallement, JB; CERN. Geneva. BE Department

    2009-01-01

    In order to deliver different beam intensities to users, we studied the possibility of varying the Linac4 beam current at PS Booster injection in pulse to pulse mode. This report gives the possible configurations of Linac4 Low and Medium Energy Beam Transport lines (LEBT and MEBT) that lead to a consistent current reduction.

  20. A pulsed electron gun for the Plane Wave Transformer Linac

    Science.gov (United States)

    Mahadevan, S.; Gandhi, M. L.; Nandedkar, R. V.

    2003-01-01

    A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 μperv and the normalized emittance is within 5 π mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

  1. A pulsed electron gun for the Plane Wave Transformer Linac

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, S. E-mail: maharaja@cat.ernet.in; Gandhi, M.L. E-mail: mlg@cat.ernet.in; Nandedkar, R.V. E-mail: nrv@cat.ernet.in

    2003-01-01

    A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 {mu}perv and the normalized emittance is within 5{pi} mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

  2. A pulsed electron gun for the Plane Wave Transformer Linac

    CERN Document Server

    Mahadevan, S; Nandedkar, R V

    2003-01-01

    A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 mu perv and the normalized emittance is within 5 pi mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

  3. A pulsed electron gun for the Plane Wave Transformer Linac

    International Nuclear Information System (INIS)

    Mahadevan, S.; Gandhi, M.L.; Nandedkar, R.V.

    2003-01-01

    A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 μperv and the normalized emittance is within 5π mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance

  4. Effect of Electric-current Pulses on Grain-structure Evolution in Cryogenically Rolled Copper

    Science.gov (United States)

    2014-11-01

    severely deformed dilute aluminium alloy . Acta Mater. 56, 1619 (2008). 4. T. Konkova, S. Mironov, A. Korznikov, and S.L. Semiatin: Microstructural response...phase transformation and variant selection by electric current pulses in a Cu-Zn alloy . J. Mater. Res. 29, 975 (2014). 13. I.Sh. Valeev and Z.G

  5. Wavelength stabilisation during current pulsing of tapered laser

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin

    2009-01-01

    The use of external feedback to stabilise the frequency of a tapered laser during current pulsing is reported. Using this technique more than 20 W of peak power in 60 ns pulses from the tapered laser is obtained and owing to the external feedback, the laser is tunable in the 778-808 nm range...

  6. Modeling of Pulsed Direct-Current Glow Discharge

    International Nuclear Information System (INIS)

    Du Mu; Zheng Yaru; Fan Yujia; Zhang Nan; Liu Chengsen; Wang Dezhen

    2010-01-01

    A self-consistent model was adopted to study the time evolution of low-voltage pulsed DC glow discharge. The distributions of electric field, ion density and electron density in nitrogen were investigated in our simulation, and the temporal shape of the discharge current was also obtained. Our results show that the dynamic behaviors of the discharge depends strongly on the applied pulse voltage, and the use of higher pulse voltages results in a significantly increase of discharge current and a decrease of discharge delay time. The current-voltage characteristic calculated by adjusting secondary electron emission coefficient for different applied pulse voltage under the gas pressure of 1 Torr is found in a reasonable agreement with the experimental results.

  7. Pulse shaping using the optical Fourier transform technique - for ultra-high-speed signal processing

    DEFF Research Database (Denmark)

    Palushani, Evarist; Oxenløwe, Leif Katsuo; Galili, Michael

    2009-01-01

    This paper reports on the generation of a 1.6 ps FWHM flat-top pulse using the optical Fourier transform technique. The pulse is validated in a 320 Gbit/s demultiplexing experiment.......This paper reports on the generation of a 1.6 ps FWHM flat-top pulse using the optical Fourier transform technique. The pulse is validated in a 320 Gbit/s demultiplexing experiment....

  8. Research of long pulse high current diode radial insulation

    International Nuclear Information System (INIS)

    Tan Jie; Chang Anbi; Hu Kesong; Liu Qingxiang; Ma Qiaosheng; Liu Zhong

    2002-01-01

    A radial insulation structure which is used in long pulse high current diode is introduced. The theory of vacuum flashover and the idea of design are briefly introduced. In the research, cone-shaped insulator was used. The geometry structure parameters were optimized by simulating the static electrical field distribution. Experiment was done on a pulse power source with 200 ns pulse width. The maximum voltage 750 kV was obtained, and the average stand-off electrical field of insulator is about 50 kV/cm

  9. Wideband Precision Current Transformer for the Magnet Current of the Beam Extraction Kicker Magnet of the Large Hadron Collider

    CERN Document Server

    Gräwer, G

    2004-01-01

    The LHC beam extraction system is composed of 15 fast kicker magnets per beam to extract the particles in one turn of the collider and to safely dispose them on external absorbers. Each magnet is powered by a separate pulse generator. The generator produces a magnet current pulse with 3 us rise time, 20 kA amplitude and 1.8 ms fall time, of which 90 us are needed to dump the beam. The beam extraction system requires a high level of reliability. To detect any change in the magnet current characteristics, which might indicate a slow degradation of the pulse generator, a high precision wideband current transformer will be installed. For redundancy reasons, the results obtained with this device will be cross-checked with a Rogowski coil, installed adjacent to the transformer. A prototype transformer has been successfully tested at nominal current levels and showed satisfactory results compared with the output of a high frequency resistive coaxial shunt. The annular core of the ring type transformer is composed of...

  10. Novel Active Bouncer Topology for Klystron Modulators based on Pulsed Transformers

    CERN Document Server

    AUTHOR|(CDS)2079689; Aguglia, Davide; Viarouge, Philippe; Cros, Jérôme

    2015-01-01

    Active droop compensation systems, so called active bouncers, for klystron modulators based on monolithic pulse transformers perform the regulation of the output pulse voltage while simultaneously withstand all the primary current of the modulator. This imposes the utilization of high power semiconductors which can produce high switching losses and degrade the overall system efficiency. In order to overcome this issue, this paper proposes a new active bouncer topology based on the parallel connection of two different power converters: the first one is in charge of handling the majority of the primary current at high efficiency, and the second one is used to fine tune the bouncer voltage via a high bandwidth converter rated at a fraction of the first parallel connected converter. Detailed comparison between a classical active bouncer and two variants of the proposed topology are presented and based on numerical simulations.

  11. Low-Frequency Pulsed Current Versus Kilohertz-Frequency Alternating Current: A Scoping Literature Review.

    Science.gov (United States)

    Vaz, Marco Aurélio; Frasson, Viviane Bortoluzzi

    2018-04-01

    To compare the effectiveness of low-frequency pulsed current versus kilohertz-frequency alternating current in terms of evoked force, discomfort level, current intensity, and muscle fatigability; to discuss the physiological mechanisms of each neuromuscular electrical stimulation type; and to determine if kilohertz-frequency alternating current is better than low-frequency pulsed current for clinical treatment. Articles were obtained from PubMed, Scopus, Cochrane Central Register of Controlled Trials, CINAHL, MEDLINE, and SPORTSDiscus databases using the terms Russian current or kilohertz current or alternating current or pulsed current or Aussie current and torque or discomfort or fatigue or current intensity, and through citation tracking up to July 2017. Two independent reviewers selected studies comparing the use of the 2 neuromuscular electrical stimulation currents. Studies describing maximal current intensity tolerated and the main effects of the 2 different current types on discomfort, muscle force, and fatigability were independently reviewed. Data were systematized according to (1) methodology; (2) electrical current characteristics; and (3) outcomes on discomfort level, evoked force, current intensity, and muscle fatigability. The search revealed 15 articles comparing the 2 current types. Kilohertz-frequency alternated current generated equal or less force, similar discomfort, similar current intensity for maximal tolerated neuromuscular electrical stimulation, and more fatigue compared with low-frequency pulsed current. Similar submaximal levels of evoked force revealed higher discomfort and current intensity for kilohertz-frequency alternated current compared with low-frequency pulsed current. Available evidence does not support the idea that kilohertz-frequency alternated current is better than low-frequency pulsed current for strength training and rehabilitation. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier

  12. Effect of current pulsing on tensile properties of titanium alloy

    International Nuclear Information System (INIS)

    Balasubramanian, V.; Jayabalan, V.; Balasubramanian, M.

    2008-01-01

    Titanium and its alloys have been considered as one of the best engineering metals for industrial applications. This is due to the excellent combination of properties such as elevated strength to weight ratio, high toughness, excellent resistance to corrosion and good fatigue properties make them attractive for many industrial applications. Recently, considerable research has been performed on pulsed current gas tungsten arc welding process and reported advantages include improved bead contour, lower heat input requirements, reduced residual stresses and distortion. Metallurgical advantages of pulsed current welding frequently reported in literature include refinement of fusion zone grain size, reduced width of heat affected zone, etc. All these factors will help in improving the mechanical properties. Hence, in this investigation an attempt has been made to study the effect of pulsed current gas tungsten arc welding parameters on Ti-6Al-4V titanium alloy

  13. Effect of current pulsing on tensile properties of titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002 (India)], E-mail: visvabalu@yahoo.com; Jayabalan, V. [Department of Manufacturing Engineering, Anna University, Guindy, Chennai 600 025 (India)], E-mail: jbalan@annauniv.edu; Balasubramanian, M. [Department of Mechanical Engineering, Maamallan Institute of Technology, Sriperumpudur 602 105 (India)], E-mail: manianmb@rediffmail.com

    2008-07-01

    Titanium and its alloys have been considered as one of the best engineering metals for industrial applications. This is due to the excellent combination of properties such as elevated strength to weight ratio, high toughness, excellent resistance to corrosion and good fatigue properties make them attractive for many industrial applications. Recently, considerable research has been performed on pulsed current gas tungsten arc welding process and reported advantages include improved bead contour, lower heat input requirements, reduced residual stresses and distortion. Metallurgical advantages of pulsed current welding frequently reported in literature include refinement of fusion zone grain size, reduced width of heat affected zone, etc. All these factors will help in improving the mechanical properties. Hence, in this investigation an attempt has been made to study the effect of pulsed current gas tungsten arc welding parameters on Ti-6Al-4V titanium alloy.

  14. Pulse current gas metal arc welding characteristics, control and applications

    CERN Document Server

    Ghosh, Prakriti Kumar

    2017-01-01

    This monograph is a first-of-its-kind compilation on high deposition pulse current GMAW process. The nine chapters of this monograph may serve as a comprehensive knowledge tool to use advanced welding engineering in prospective applications. The contents of this book will prove useful to the shop floor welding engineer in handling this otherwise critical welding process with confidence. It will also serve to inspire researchers to think critically on more versatile applications of the unique nature of pulse current in GMAW process to develop cutting edge welding technology.

  15. New Pulsed Power Technology for High Current Accelerators

    International Nuclear Information System (INIS)

    Caporaso, G J

    2002-01-01

    Recent advances in solid-state modulators now permit the design of a new class of high current accelerators. These new accelerators will be able to operate in burst mode at frequencies of several MHz with unprecedented flexibility and precision in pulse format. These new modulators can drive accelerators to high average powers that far exceed those of any other technology and can be used to enable precision beam manipulations. New insulator technology combined with novel pulse forming lines and switching may enable the construction of a new type of high gradient, high current accelerator. Recent developments in these areas will be reviewed

  16. Development of optoelectronic-based pulsed current sensor to ...

    Indian Academy of Sciences (India)

    Anil S Nayak

    2017-08-03

    Aug 3, 2017 ... mitter–receiver HFBR, high-frequency current transformer, and fiber optic link. The CT has ... vacuum system, the atmospheric gases enter into the CVL, causing ..... tronics, Computer, Telecommunication and Information Tech-.

  17. Observation of dark pulses in 10 nm thick YBCO nanostrips presenting hysteretic current voltage characteristics

    Science.gov (United States)

    Ejrnaes, M.; Parlato, L.; Arpaia, R.; Bauch, T.; Lombardi, F.; Cristiano, R.; Tafuri, F.; Pepe, G. P.

    2017-12-01

    We have fabricated several 10 nm thick and 65 nm wide YBa2Cu3O7-δ (YBCO) nanostrips. The nanostrips with the highest critical current densities are characterized by hysteretic current voltage characteristics (IVCs) with a direct bistable switch from the zero-voltage to the finite voltage state. The presence of hysteretic IVCs allowed the observation of dark pulses due to fluctuations phenomena. The key role of the bistable behavior is its ability to transform a small disturbance (e.g. an intrinsic fluctuation) into a measurable transient signal, i.e. a dark pulse. On the contrary, in devices characterized by lower critical current density values, the IVCs are non-hysteretic and dark pulses have not been observed. To investigate the physical origin of the dark pulses, we have measured the bias current dependence of the dark pulse rate: the observed exponential increase with the bias current is compatible with mechanisms based on thermal activation of magnetic vortices in the nanostrip. We believe that the successful amplification of small fluctuation events into measurable signals in nanostrips of ultrathin YBCO is a milestone for further investigation of YBCO nanostrips for superconducting nanostrip single photon detectors and other quantum detectors for operation at higher temperatures.

  18. Protection of power transformers against geomagnetically induced currents

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2011-01-01

    Full Text Available The article examines the problem of saturation and failure of power transformers under geomagnetically induced currents and currents of the E3 component of high-altitude nuclear explosions. It also describes a special protective relay reacting on DC component in the transformer neutral current.

  19. Method for measuring the resistive transition and critical current in superconductors using pulsed current

    International Nuclear Information System (INIS)

    McGinnis, W.C.; Jones, T.E.

    1993-01-01

    A method is described for measuring the intragranular critical current of a granular superconductive material, comprising the steps of: conducting a substantially rectangular electronic pulse through said material so as to conduct a current through said material such that when said intragranular critical current of said material is exceeded, any grains present in said material are in a superconducting state when said current is less than said intragranular critical current, said material having a critical temperature; measuring said current through said material while conducting said pulse; measuring a voltage difference across said material while conducting said pulse; and determining said intragranular critical current through said material by varying said current to discern a current level at which an electrical resistance of said material increases to that of a non-superconducting state as the grains of said material transition from said superconducting to said non-superconducting state

  20. Electrochemical synthesis of nanosized hydroxyapatite by pulsed direct current method

    Energy Technology Data Exchange (ETDEWEB)

    Nur, Adrian; Rahmawati, Alifah; Ilmi, Noor Izzati; Affandi, Samsudin; Widjaja, Arief [Departement of Chemical Engineering, Faculty of Industrial Technology, Sepuluh Nopember Institute of Technology, Kampus ITS Sukolilo, Surabaya 60111 (Indonesia)

    2014-02-24

    Synthesis of nanosized of hydroxyapatite (HA) by electrochemical pulsed direct current (PDC) method has been studied. The aim of this work is to study the influence of various PDC parameters (pH initial, electrode distance, duty cycle, frequency, and amplitude) on particle surface area of HA powders. The electrochemical synthesis was prepared in solution Ca{sup 2+}/EDTA{sup 4−}/PO{sub 4}{sup 3+} at concentration 0.25/0.25/0.15 M for 24 h. The electrochemical cell was consisted of two carbon rectangular electrodes connected to a function generator to produce PDC. There were two treatments for particles after electrosynthesized, namely without aging and aged for 2 days at 40 °C. For both cases, the particles were filtered and washed by demineralized water to eliminate the impurities and unreacted reactants. Then, the particles were dried at 100 °C for 2 days. The dried particles were characterized by X-ray diffraction, surface area analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectra and thermogravimetric and differential thermal analysis. HA particles can be produced when the initial pH > 6. The aging process has significant effect on the produced HA particles. SEM images of HA particles showed that the powders consisted of agglomerates composed of fine crystallites and have morphology plate-like and sphere. The surface area of HA particles is in the range of 25 – 91 m{sup 2}/g. The largest particle surface area of HA was produced at 4 cm electrode distance, 80% cycle duty, frequency 0.1 Hz, amplitude 9 V and with aging process.

  1. Pulsed transport critical currents of Bi2212 tapes in pulsed magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Rogacki, K [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland); Gilewski, A; Klamut, J [International Laboratory of High Magnetic Fields and Low Temperatures, Polish Academy of Sciences, Wroclaw (Poland); Newson, M; Jones, H [Clarendon Laboratory, University of Oxford, Oxford (United Kingdom); Glowacki, B A [IRC in Superconductivity and Department of Materials Science, University of Cambridge, Cambridge (United Kingdom)

    2002-07-01

    If high-T{sub C} superconductors are ever to be used in high-field applications, it is vital that the critical surfaces can be mapped under high-field conditions. However, the latest superconductors have high currents even at fields over 20 T, making accurate measurements very difficult due to the thermal and mechanical problems. In this paper, we compare measurements on BSCCO-2212 tape using a number of different methods, particularly an innovative pulsed transport current and pulsed field mode. We show how the analysis of the voltage signal from BSCCO-2212 tape in pulsed conditions may be used to extract the critical current in quasi-stationary conditions. The effect of a metallic substrate on the results is also briefly discussed. (author)

  2. Power Quality Problems Due to Transformer Inrush Current

    OpenAIRE

    Tokić, A.; Uglešić, I.

    2017-01-01

    Transformer energization can produce a large nonsinuoidal inrush current which contains both odd and higher order harmonic components that can put transformer winding under mechanical stress. Additionally, they can cause irregular tripping of harmonic protection relays. Furthermore, in relatively weak power systems, such as is the Bosnian system, the superposition of harmonic components with system resonance frequencies may produce temporary overvoltages (TOV). Transformer wind...

  3. Principles and applications of multiplane pulsed eddy currents

    International Nuclear Information System (INIS)

    David, B.; Champonnois, F.; Joffre, F.

    1989-01-01

    A pulsed device using eddy currents, producing 8 shape signals on the screen like a sine wave system, has been developed. The method has been applied to the well-known problem of defects in stainless claddings of PWR reactor vessels

  4. Electrodialytic soil remediation enhanced by low frequency pulse current

    DEFF Research Database (Denmark)

    Sun, Tian R.; Ottosen, Lisbeth M.; Mortensen, John

    2013-01-01

    The effect of low frequency pulse current on decreasing the polarization and energy consumption during the process of electrodialytic soil remediation was investigated in the present work. The results indicated that the transportation of cations through the cation exchange membrane was the rate...

  5. Numerical Analysis of Through Transmission Pulsed Eddy Current Testing and Effects of Pulse Width Variation

    International Nuclear Information System (INIS)

    Shin, Young Kil; Choi, Dong Myung

    2007-01-01

    By using numerical analysis methods, through transmission type pulsed eddy current (PEC) testing is modeled and PEC signal responses due to varying material conductivity, permeability, thickness, lift-off and pulse width are investigated. Results show that the peak amplitude of PEC signal gets reduced and the time to reach the peak amplitude is increased as the material conductivity, permeability, and specimen thickness increase. Also, they indicate that the pulse width needs to be shorter when evaluating the material conductivity and the plate thickness using the peak amplitude, and when the pulse width is long, the peak time is found to be more useful. Other results related to lift-off variation are reported as well

  6. Terrestrial gamma ray flash production by lightning current pulses

    OpenAIRE

    İnan, Umran Savaş; Carlson, B. E.; Lehtinen, N. G.

    2017-01-01

    Terrestrial gamma ray flashes (TGFs) are brief bursts of gamma rays observed by satellites, typically in coincidence with detectable lightning. We incorporate TGF observations and the key physics behind current TGF production theories with lightning physics to produce constraints on TGF production mechanisms. The combined constraints naturally suggest a mechanism for TGF production by current pulses in lightning leader channels. The mechanism involves local field enhancements due to charge re...

  7. Optimized transmission-line impedance transformers for petawatt-class pulsed-power accelerators

    Directory of Open Access Journals (Sweden)

    D. R. Welch

    2008-03-01

    Full Text Available We have developed 1D analytic and 2D fully electromagnetic models of radial transmission-line impedance transformers. The models have been used to quantify the power-transport efficiency and pulse sharpening of such transformers as a function of voltage pulse width and impedance profile. For the cases considered, we find that in the limit as Γ→0 (where Γ is the ratio of the pulse width to the one-way transit time of the transformer, the transport efficiency is maximized when the impedance profile is exponential. As Γ increases from zero, the optimum profile gradually deviates from an exponential. A numerical procedure is presented that determines the optimum profile for a given pulse shape and width. The procedure can be applied to optimize the design of impedance transformers used in petawatt-class pulsed-power accelerators.

  8. Electronic constant current and current pulse signal generator for nuclear instrumentation testing

    International Nuclear Information System (INIS)

    Brown, R.A.

    1994-01-01

    Circuitry is described for testing the ability of an intermediate range nuclear instrument to detect and measure a constant current and a periodic current pulse. The invention simulates the resistance and capacitance of the signal connection of a nuclear instrument ion chamber detector and interconnecting cable. An LED flasher/oscillator illuminates an LED at a periodic rate established by a timing capacitor and circuitry internal to the flasher/oscillator. When the LED is on, a periodic current pulse is applied to the instrument. When the LED is off, a constant current is applied. An inductor opposes battery current flow when the LED is on. 1 figures

  9. Design and performance of a pulse transformer based on Fe-based nanocrystalline core.

    Science.gov (United States)

    Yi, Liu; Xibo, Feng; Lin, Fuchang

    2011-08-01

    A dry-type pulse transformer based on Fe-based nanocrystalline core with a load of 0.88 nF, output voltage of more than 65 kV, and winding ratio of 46 is designed and constructed. The dynamic characteristics of Fe-based nanocrystalline core under the impulse with the pulse width of several microseconds were studied. The pulse width and incremental flux density have an important effect on the pulse permeability, so the pulse permeability is measured under a certain pulse width and incremental flux density. The minimal volume of the toroidal pulse transformer core is determined by the coupling coefficient, the capacitors of the resonant charging circuit, incremental flux density, and pulse permeability. The factors of the charging time, ratio, and energy transmission efficiency in the resonant charging circuit based on magnetic core-type pulse transformer are analyzed. Experimental results of the pulse transformer are in good agreement with the theoretical calculation. When the primary capacitor is 3.17 μF and charge voltage is 1.8 kV, a voltage across the secondary capacitor of 0.88 nF with peak value of 68.5 kV, rise time (10%-90%) of 1.80 μs is obtained.

  10. A high-current pulsed cathodic vacuum arc plasma source

    International Nuclear Information System (INIS)

    Oates, T.W.H.; Pigott, J.; Mckenzie, D.R.; Bilek, M.M.M.

    2003-01-01

    Cathodic vacuum arcs (CVAs) are well established as a method for producing metal plasmas for thin film deposition and as a source of metal ions. Fundamental differences exist between direct current (dc) and pulsed CVAs. We present here results of our investigations into the design and construction of a high-current center-triggered pulsed CVA. Power supply design based on electrolytic capacitors is discussed and optimized based on obtaining the most effective utilization of the cathode material. Anode configuration is also discussed with respect to the optimization of the electron collection capability. Type I and II cathode spots are observed and discussed with respect to cathode surface contamination. An unfiltered deposition rate of 1.7 nm per pulse, at a distance of 100 mm from the source, has been demonstrated. Instantaneous plasma densities in excess of 1x10 19 m -3 are observed after magnetic filtering. Time averaged densities an order of magnitude greater than common dc arc densities have been demonstrated, limited by pulse repetition rate and filter efficiency

  11. Fast switching thyristor applied in nanosecond-pulse high-voltage generator with closed transformer core.

    Science.gov (United States)

    Li, Lee; Bao, Chaobing; Feng, Xibo; Liu, Yunlong; Fochan, Lin

    2013-02-01

    For a compact and reliable nanosecond-pulse high-voltage generator (NPHVG), the specification parameter selection and potential usage of fast controllable state-solid switches have an important bearing on the optimal design. The NPHVG with closed transformer core and fast switching thyristor (FST) was studied in this paper. According to the analysis of T-type circuit, the expressions for the voltages and currents of the primary and secondary windings on the transformer core of NPHVG were deduced, and the theoretical maximum analysis was performed. For NPHVG, the rise-rate of turn-on current (di/dt) across a FST may exceed its transient rating. Both mean and maximum values of di/dt were determined by the leakage inductances of the transformer, and the difference is 1.57 times. The optimum winding ratio is helpful to getting higher voltage output with lower specification FST, especially when the primary and secondary capacitances have been established. The oscillation period analysis can be effectively used to estimate the equivalent leakage inductance. When the core saturation effect was considered, the maximum di/dt estimated from the oscillating period of the primary current is more accurate than one from the oscillating period of the secondary voltage. Although increasing the leakage inductance of NPHVG can decrease di/dt across FST, it may reduce the output peak voltage of the NPHVG.

  12. Several peaks of total current in Trichel pulse

    International Nuclear Information System (INIS)

    Bolotov, O.; Golota, V.; Kadolin, B.; Mankovskyi, S.; Ostroushko, V.; Pashchenko, I.; Taran, G.; Zavada, L.

    2015-01-01

    The numerical simulations of negative corona at constant voltage in Trichel pulse mode are carried out in assumptions of presence and absence of photoemission from cathode. In absence of photoemission two peaks of total current or the step before the main peak were obtained for very small values of ion-electron emission coefficient. In presence of photoemission there were observed several maximums, connected with instability development of the process based on radiation of photons, photoemission, and avalanche multiplication

  13. Very Fast Current Diagnostic for Linear Pulsed Beams

    Science.gov (United States)

    Nassisi, Vincenzo; Delle Side, Domenico; Turco, Vito

    2018-01-01

    Fast current pulses manage lasers and particle accelerators and require sophisticate systems to be detected. At today Rogowski coils are well known. They are designed and built with a toroidal structure. In recently application, flat transmission lines are imploded and for this reason we develop a linear Rogowski coil to detect current pulses inside flat conductors. To get deep information from the system, it was approached by means of the theory of the transmission lines. The coil we build presents a resistance but it doesn't influence the rise time of the response, instead the integrating time. We also studied the influence of the magnetic properties of coil support. The new device was able to record pulses of more hundred nanoseconds depending on the inductance, load impedance and resistance of the coil. Furthermore, its response was characterized by a sub-nanosecond rise time ( 100 ps), The attenuation coefficient depends mainly on the turn number of the coil, while the quality of the response depends both on the manufacture quality of the coil and on the magnetic core characteristics. In biophysical applications often, a double line is employed in order to have a sample as control and a sample stressed by a light source. So, in this case we build two equal plane lines by 100 Ω characteristic resistance connected in parallel. We diagnosed the current present in a line. The attenuation factor resulted to be 11,5 A/V.

  14. Very Fast Current Diagnostic for Linear Pulsed Beams

    Directory of Open Access Journals (Sweden)

    Nassisi Vincenzo

    2018-01-01

    Full Text Available Fast current pulses manage lasers and particle accelerators and require sophisticate systems to be detected. At today Rogowski coils are well known. They are designed and built with a toroidal structure. In recently application, flat transmission lines are imploded and for this reason we develop a linear Rogowski coil to detect current pulses inside flat conductors. To get deep information from the system, it was approached by means of the theory of the transmission lines. The coil we build presents a resistance but it doesn’t influence the rise time of the response, instead the integrating time. We also studied the influence of the magnetic properties of coil support. The new device was able to record pulses of more hundred nanoseconds depending on the inductance, load impedance and resistance of the coil. Furthermore, its response was characterized by a sub-nanosecond rise time (~100 ps, The attenuation coefficient depends mainly on the turn number of the coil, while the quality of the response depends both on the manufacture quality of the coil and on the magnetic core characteristics. In biophysical applications often, a double line is employed in order to have a sample as control and a sample stressed by a light source. So, in this case we build two equal plane lines by 100 Ω characteristic resistance connected in parallel. We diagnosed the current present in a line. The attenuation factor resulted to be 11,5 A/V.

  15. The high current, fast, 100ns, Linear Transformer Driver (LTD) developmental project at Sandia National Laboratories

    International Nuclear Information System (INIS)

    Ward, Kevin S.; Long, Finis W.; Sinebryukhov, Vadim A.; Kim, Alexandre A.; Wakeland, Peter Eric; McKee, G. Randall; Woodworth, Joseph Ray; McDaniel, Dillon Heirman; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John Larry Jr.; Struve, Kenneth William; Stygar, William A.; LeChien, Keith R.; Matzen, Maurice Keith

    2010-01-01

    Sandia National Laboratories, Albuquerque, N.M., USA, in collaboration with the High Current Electronic Institute (HCEI), Tomsk, Russia, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This technological approach can provide very compact devices that can deliver very fast high current and high voltage pulses straight out of the cavity with out any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. This is because the output pulse rise time and width can be easily tailored to the specific application needs. In this paper we briefly summarize the developmental work done in Sandia and HCEI during the last few years, and describe our new MYKONOS Sandia High Current LTD Laboratory.

  16. Flat-top pulse generation by the optical Fourier transform technique for ultrahigh speed signal processing

    DEFF Research Database (Denmark)

    Palushani, Evarist; Oxenløwe, Leif Katsuo; Galili, Michael

    2009-01-01

    This paper reports on the generation of 1.6-ps fullwidth at half-maximum flat-top pulses by the optical Fourier transform technique, and the utilization of these pulses in a 320-Gb/s demultiplexing experiment. It is demonstrated how a narrow pulse having a 15-nm wide third-order super-Gaussian sp......This paper reports on the generation of 1.6-ps fullwidth at half-maximum flat-top pulses by the optical Fourier transform technique, and the utilization of these pulses in a 320-Gb/s demultiplexing experiment. It is demonstrated how a narrow pulse having a 15-nm wide third-order super...

  17. Current measurement method for characterization of fast switching power semiconductors with Silicon Steel Current Transformer

    DEFF Research Database (Denmark)

    Li, Helong; Beczkowski, Szymon; Munk-Nielsen, Stig

    2015-01-01

    This paper proposes a novel current measurement method with Silicon Steel Current Transformer (SSCT) for the characterization of fast switching power semiconductors. First, the existing current sensors for characterization of fast switching power semiconductors are experimentally evaluated...

  18. Dynamic response of HTS composite tapes to pulsed currents

    International Nuclear Information System (INIS)

    Meerovich, V; Sokolovsky, V; Prigozhin, L; Rozman, D

    2006-01-01

    Dynamic voltage-current characteristics of an HTS Ag/BiSCCO composite tape are studied both experimentally and theoretically. The tape is subjected to pulsed currents with different shapes and magnitudes and voltage traces are measured using the four-point method with different locations of potential taps on the sample surface. Clockwise and anticlockwise hysteresis loops are obtained for the same sample depending on the location of the potential taps. The dynamic characteristics deviate substantially from the DC characteristic, especially in the range of low voltages where a criterion for the critical current value is usually chosen (1-10 μV cm -1 ). The critical current determined from dynamic characteristics and its change with the pulse magnitude depend on the location of the potential taps and on the curve branch chosen for the critical current determination (ascending or descending). The theoretical analysis is based on a model of the magnetic flux diffusion into a composite tape for a superconductor described by the flux creep characteristic. Numerical simulation based on this model gives results in good agreement with the experimental ones and explains the observed peculiarities of the dynamic characteristics of HTS composite tapes. The difference between the magnetic diffusion into a tape and a slab is discussed

  19. Volkov transform generalized projection algorithm for attosecond pulse characterization

    International Nuclear Information System (INIS)

    Keathley, P D; Bhardwaj, S; Moses, J; Laurent, G; Kärtner, F X

    2016-01-01

    An algorithm for characterizing attosecond extreme ultraviolet pulses that is not bandwidth-limited, requires no interpolation of the experimental data, and makes no approximations beyond the strong-field approximation is introduced. This approach fully incorporates the dipole transition matrix element into the retrieval process. Unlike attosecond retrieval methods such as phase retrieval by omega oscillation filtering (PROOF), or improved PROOF, it simultaneously retrieves both the attosecond and infrared (IR) pulses, without placing fundamental restrictions on the IR pulse duration, intensity or bandwidth. The new algorithm is validated both numerically and experimentally, and is also found to have practical advantages. These include an increased robustness to noise, and relaxed requirements for the size of the experimental dataset and the intensity of the streaking pulse. (paper)

  20. High current precision long pulse electron beam position monitor

    CERN Document Server

    Nelson, S D; Fessenden, T J; Holmes, C

    2000-01-01

    Precision high current long pulse electron beam position monitoring has typically experienced problems with high Q sensors, sensors damped to the point of lack of precision, or sensors that interact substantially with any beam halo thus obscuring the desired signal. As part of the effort to develop a multi-axis electron beam transport system using transverse electromagnetic stripline kicker technology, it is necessary to precisely determine the position and extent of long high energy beams for accurate beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs beam pulse, sub millimeter beam position accuracy.) The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (< 20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt position measurements.

  1. Transformer core modeling for magnetizing inrush current investigation

    Directory of Open Access Journals (Sweden)

    A.Yahiou

    2014-03-01

    Full Text Available The inrush currents generated during an energization of power transformer can reach very high values and may cause many problems in power system. This magnetizing inrush current which occurs at the time of energization of a transformer is due to temporary overfluxing in the transformer core. Its magnitude mainly depends on switching parameters such as the resistance of the primary winding and the point-on-voltage wave (switching angle. This paper describes a system for measuring the inrush current which is composed principally of an acquisition card (EAGLE, and LabVIEW code. The system is also capable of presetting various combinations of switching parameters for the energization of a 2 kVA transformer via an electronic card. Moreover, an algorithm for calculating the saturation curve is presented taking the iron core reactive losses into account, thereby producing a nonlinear inductance. This curve is used to simulate the magnetizing inrush current using the ATP-EMTP software.

  2. Interagency Functional Transformation Current and Emerging Departmental Relationships

    National Research Council Canada - National Science Library

    Beydler, William

    2003-01-01

    .... Transformation is clearly a priority of U.S. national leadership. A review of the history of that evolution and assessment of the current interagency relationships can suggest options to complete the process...

  3. Investigation on a new inducer of pulsed eddy current thermography

    Directory of Open Access Journals (Sweden)

    Min He

    2016-09-01

    Full Text Available In this paper, a new inducer of pulsed eddy current thermography (PECT is presented. The use of the inducer can help avoid the problem of blocking the infrared (IR camera’s view in eddy current thermography technique. The inducer can also provide even heating of the test specimen. This paper is concerned with the temperature distribution law around the crack on a specimen when utilizing the new inducer. Firstly, relative mathematical models are provided. In the following section, eddy current distribution and temperature distribution around the crack are studied using the numerical simulation method. The best separation distance between the inducer and the specimen is also determined. Then, results of temperature distribution around the crack stimulated by the inducer are gained by experiments. Effect of current value on temperature rise is studied as well in the experiments. Based on temperature data, temperature features of the crack are discussed.

  4. Study on pulsed current cathodic protection in a simulated system

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Milin; Li, Helin [Xi' an Jiao Tong Universitiy (China)]|[Tubular Goods Research Center of China National Petroleum Corp. (China); Qiu, Yubing; Guo, Xingpeng [Hua Zhong University of Science and Techonology (China)

    2004-07-01

    The pulsed current cathodic protection (PCCP) is a new cathodic protection (CP) technology and shows more advantages over the conventional DC cathodic protection (DCCP) in oil well casing system. However, little information about PCCP is reported. In this research, a simulated CP system was set up in a pool of 3.5 m x 2.0 m x 3.0 m size, in which the effects of the square wave pulsed current (SWPC) parameters (amplitude: IA, frequency: f, duty cycle: P), auxiliary anode distance (d) and media conductivity ({mu}) on the cathodic potential (E) distribution were studied, and the protection effects of PCCP and DCCP were compared. The results show that with increase of the square wave parameters (IA, f, P), the E distribution becomes more negative and the effects of each current parameter are relate closely to the cathode polarizing state. Only with suitable square wave parameters can the whole cathode be effectively protected. With increase of d and {mu}, the E distribution becomes more uniform. Compared with DCCP system, PCCP system has much more uniform E distribution, costs less average current, and gains much better protection effects. Further, the mechanism of PCCP was analyzed. (authors)

  5. Low-leakage, high-current power crowbar transformer

    International Nuclear Information System (INIS)

    Buck, R.T.; Galbraith, J.D.; Nunnally, W.C.

    1979-01-01

    The design, fabrication, and testing of two sizes of power crowbar transformers for the ZT-40 Toroidal Z-Pinch experiment at the Los Alamos Scientific Laboratory are described. Low-leakage transformers in series with the poloidal and the toroidal field coils are used to sustain magnetic field currents initially produced by 50-kV capacitor banks. The transformer primaries are driven by cost-effective, ignitron-switched, 10-kV high-density capacitor banks. The transformer secondaries, in series with the field coils, provide from 1,000 to 1,500 V to cancel the resistive voltage drop in the coil circuits. Prototype transformers, with a total leakage inductance measured in the secondary of 5 nH, have been tested with peak secondary currents in excess of 600 kA resulting from a 10-kV primary charge voltage. The test procedures and results and the mechanical construction details are presented

  6. Innovations in electrophoretic deposition: Alternating current and pulsed direct current methods

    International Nuclear Information System (INIS)

    Chávez-Valdez, Alejandra; Boccaccini, Aldo R.

    2012-01-01

    This review summarizes emerging developments in the field of alternating current (AC) and pulsed direct current (DC) electrophoretic deposition (EPD) in aqueous or organic media. Numerous applications of AC-EPD are discussed including two major groups of investigations: (i) AC-EPD to suppress water hydrolysis at high voltages in inorganic (ceramic) coatings and (ii) AC-EPD for deposition of biological entities. The deposition, purification and manipulation of carbon nanotubes and nanoparticles by AC-EPD to form specific arrays, for development of sensors and other electronic devices and the application of AC-EPD as method for separation of particles according to their shape or size are also presented. Other applications reviewed relate to the fabrication by AC-EPD of toxic gas sensors from oxides and superconducting layers. The main materials being examined by AC-EPD are inorganic, including carbon nanotubes, TiO 2 nanoparticles, Al 2 O 3 , Si, SnO 2 , ZnO and WO 3 and biological entities, e.g. bacteria cells. For pulsed EPD, the applications reviewed are divided in pulsed current and pulsed voltage EPD. Among the applications of pulsed EPD, the formation of thick films from aqueous suspensions without water decomposition, the fabrication of multilayer and composite materials and the size-selective deposition of ceramic nanoparticles are the most important investigated to date, based on the quality of the coatings and deposits obtained and their relevance for applications.

  7. A ns-pulsed high-current electron beam source

    International Nuclear Information System (INIS)

    Guan, Gexin; Li, Youzhi; Pan, Yuli

    1988-01-01

    The behaviour of a pulse electron beam source which is composed of a gun and pulse system depends on not only the time characteristics of the gun and the pulser, but also their combination. This point become apparent if effects of the electron tansit-time between electrodes are studied. A ferrite transmission line (FTL) pulser is used as a grid driver in this source. It has advantages of providing fast risetime, large peak power output and good loading characteristics. It is these advantages of the pulser that compensates the absence of some technological conditions of manufacturing gun and makes the source better. Our testing showed that the cooperation of both the gun and the pulser produced peak currents in the range of 1 to 9 amps with widths of 2 to 2.5 ns (FWHM) at cathode-to-anode potential of 60 to 82 kv, while the grid drives are about in the range of 1 to 3 kv. In addition, the results of the testing instructed that effects of electron transit-time cannot be ignored when the pulses with widths of several nanoseconds are used as a grid drive. Based on the results, electron transit-time effects on the design of the gun and the beam performances are briefly descussed in this paper. (author)

  8. High current pulsed linear ion accelerators for inertial fusion applications

    International Nuclear Information System (INIS)

    Humphries, S. Jr.; Yonas, G.; Poukey, J.W.

    1978-01-01

    Pulsed ion beams have a number of advantages for use as inertial fusion drivers. Among these are classical interaction with targets and good efficiency of production. As has been pointed out by members of the accelerator community, multistage accelerators are attractive in this context because of lower current requirements, low power flow per energy conversion stage and low beam divergence at higher ion energies. On the other hand, current transport limits in conventional accelerators constrain them to the use of heavy ions at energies much higher than those needed to meet the divergence requirements, resulting in large, costly systems. We have studied methods of neutralizing ion beams with electrons within the accelerator volume to achieve higher currents. The aim is to arrive at an inexpensive accelerator that can advantageously use existing pulsed voltage technology while being conservative enough to achieve a high repetition rate. Typical output parameters for reactor applications would be an 0 + beam of 30 kA at 300 MeV. We will describe reactor scaling studies and the physics of neutralized linear accelerators using magnetic fields to control the electron dynamics. Recent results are discussed from PULSELAC, a five stage multikiloampere device being tested at Sandia Laboratories

  9. Characterization of irradiated fuel rods using pulsed eddy current techniques

    International Nuclear Information System (INIS)

    Martin, M.R.; Francis, W.C.

    1975-11-01

    A number of irradiated fuel rods and unfueled zircaloy cladding tubes (''water tubes'') were obtained from the Saxton reactor through arrangements with the Westinghouse Electric Corporation for use in subsequent irradiation effects and fuel behavior programs. A comprehensive nondestructive and corroborative destructive characterization program was undertaken on these fuel rods and tubes by ANC to provide baseline data on their characteristics prior to further testing and for comparison against post-post data. This report deals primarily with one portion of the NDT program performed remotely in the hot cells. The portion of interest in this paper is the pulsed eddy current inspection used in the nondestructive phase of the work. 6 references

  10. Research on High Current Pulse Discharges at IPP ASci CR

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Schmidt, Jiří; Prukner, Václav; Štraus, Jaroslav; Frolov, Oleksandr; Martínková, M.

    2006-01-01

    Roč. 56, suppl. B (2006), s. 259-266 ISSN 0011-4626. [Symposium on Plasma Physics and Technology/22nd./. Praha, 26.6.2006-29.6.2006] R&D Projects: GA ČR GA202/06/1324; GA MŠk 1P04LA235 Institutional research plan: CEZ:AV0Z20430508 Keywords : Pulsed high current capillary discharge * amplified spontaneous emission * soft X-ray laser Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.568, year: 2006

  11. High-current pulsed ion source for metallic ions

    International Nuclear Information System (INIS)

    Gavin, B.; Abbott, S.; MacGill, R.; Sorensen, R.; Staples, J.; Thatcher, R.

    1981-03-01

    A new sputter-ion PIG source and magnet system, optimized for intermediate charge states, q/A of 0.02 to 0.03, is described. This source will be used with the new Wideroe-based injector for the SuperHILAC. Pulsed electrical currents of several emA of heavy metal ions have been produced in a normalized emittance area of .05π cm-mr. The source system is comprised of two electrically separate anode chambers, one in operation and one spare, which can be selected by remote control. The entire source head is small and quickly removable

  12. Hybrid Design Optimization of High Voltage Pulse Transformers for Klystron Modulators

    CERN Document Server

    Sylvain, Candolfi; Davide, Aguglia; Jerome, Cros

    2015-01-01

    This paper presents a hybrid optimization methodology for the design of high voltage pulse transformers used in klystron modulators. The optimization process is using simplified 2D FEA design models of the 3D transformer structure. Each intermediate optimal solution is evaluated by 3D FEA and correction coefficients of the 2D FEA models are derived. A new optimization process using 2D FEA models is then performed. The convergence of this hybrid optimal design methodology is obtained with a limited number of time consuming 3D FEA simulations. The method is applied to the optimal design of a monolithic high voltage pulse transformer for the CLIC klystron modulator.

  13. Pulsed currents carried by whistlers. IV. Electric fields and radiation excited by an electrode

    International Nuclear Information System (INIS)

    Stenzel, R.L.; Urrutia, J.M.; Rousculp, C.L.

    1995-01-01

    Electromagnetic properties of current pulses carried by whistler wave packets are obtained from a basic laboratory experiment. While the magnetic field and current density are described in the preceding companion paper (Part III), the present analysis starts with the electric field. The inductive and space charge electric field contributions are separately calculated in Fourier space from the measured magnetic field and Ohm's law along B 0 . Inverse Fourier transformation yields the total electric field in space and time, separated into rotational and divergent contributions. The space-charge density in whistler wave packets is obtained. The cross-field tensor conductivity is determined. The frozen-in condition is nearly satisfied, E+v e xB congruent 0. The dissipation is obtained from Poynting's theorem. The waves are collisionally damped; Landau damping is negligible. A radiation resistance for the electrode is determined. Analogous to Poynting's theorem, the transport of helicity is analyzed. Current helicity is generated by a flow of helicity between pulses traveling in opposite directions which carry opposite signs of helicity. Helicity is dissipated by collisions. These observations complete a detailed description of whistler/current pulses which can occur in various laboratory and space plasmas. copyright 1995 American Institute of Physics

  14. Integrated Current Balancing Transformer for Primary Parallel Isolated Boost Converter

    DEFF Research Database (Denmark)

    Sen, Gökhan; Ouyang, Ziwei; Thomsen, Ole Cornelius

    2011-01-01

    A simple, PCB compatible integrated solution is proposed for the current balancing requirement of the primary parallel isolated boost converter (PPIBC). Input inductor and the current balancing transformer are merged into the same core, which reduces the number of components allowing a cheaper...

  15. Transformation between divacancy defects induced by an energy pulse in graphene.

    Science.gov (United States)

    Xia, Jun; Liu, XiaoYi; Zhou, Wei; Wang, FengChao; Wu, HengAn

    2016-07-08

    The mutual transformations among the four typical divacancy defects induced by a high-energy pulse were studied via molecular dynamics simulation. Our study revealed all six possible mutual transformations and found that defects transformed by absorbing energy to overcome the energy barrier with bonding, debonding, and bond rotations. The reversibility of defect transformations was also investigated by potential energy analysis. The energy difference was found to greatly influence the transformation reversibility. The direct transformation path was irreversible if the energy difference was too large. We also studied the correlation between the transformation probability and the input energy. It was found that the transformation probability had a local maxima at an optimal input energy. The introduction of defects and their structural evolutions are important for tailoring the exceptional properties and thereby performances of graphene-based devices, such as nanoporous membranes for the filtration and desalination of water.

  16. Electrical and hydrodynamic characterization of a high current pulsed arc

    International Nuclear Information System (INIS)

    Sousa Martins, R; Chemartin, L; Zaepffel, C; Lalande, Ph; Soufiani, A

    2016-01-01

    High current pulsed arcs are of significant industrial interest and, aiming to reduce time and cost, there is progressively more and more need for computation tools that describe and predict the behaviour of these arcs. These simulation codes need inputs and validations by experimental databases, but accurate data is missing for this category of electric discharges. The principal lack of understanding is with respect to the transient phase of the current, which can reach thousands of amperes in a few microseconds. In this paper, we present the work realized on an experimental setup that simulates in the laboratory an arc column subjected to five levels of high pulsed current, ranging from 10 kA to 100 kA, with the last one corresponding to the standard lightning current waveform used in aircraft certification processes. This device was instrumented by high speed video cameras to assess the characteristic sizes of the arc channel and to characterize the shock wave generated by the arc expansion. The arc channel radius was measured over time during the axisymmetric phase and reached 3.2 cm. The position and velocity of the shock wave was determined during the first 140 μs. The background-oriented schlieren method was used to study the shock wave and a model for the light deflection inside the shock wave was developed. The mass density profile of the shock wave was estimated and showed good agreement with Rankine–Hugoniot relations at the wave front. Electrical measurements were also used to estimate the time-dependent resistance and conductivity of the arc for times lasting up to 50 μs. (paper)

  17. Electrical and hydrodynamic characterization of a high current pulsed arc

    Science.gov (United States)

    Sousa Martins, R.; Chemartin, L.; Zaepffel, C.; Lalande, Ph; Soufiani, A.

    2016-05-01

    High current pulsed arcs are of significant industrial interest and, aiming to reduce time and cost, there is progressively more and more need for computation tools that describe and predict the behaviour of these arcs. These simulation codes need inputs and validations by experimental databases, but accurate data is missing for this category of electric discharges. The principal lack of understanding is with respect to the transient phase of the current, which can reach thousands of amperes in a few microseconds. In this paper, we present the work realized on an experimental setup that simulates in the laboratory an arc column subjected to five levels of high pulsed current, ranging from 10 kA to 100 kA, with the last one corresponding to the standard lightning current waveform used in aircraft certification processes. This device was instrumented by high speed video cameras to assess the characteristic sizes of the arc channel and to characterize the shock wave generated by the arc expansion. The arc channel radius was measured over time during the axisymmetric phase and reached 3.2 cm. The position and velocity of the shock wave was determined during the first 140 μs. The background-oriented schlieren method was used to study the shock wave and a model for the light deflection inside the shock wave was developed. The mass density profile of the shock wave was estimated and showed good agreement with Rankine-Hugoniot relations at the wave front. Electrical measurements were also used to estimate the time-dependent resistance and conductivity of the arc for times lasting up to 50 μs.

  18. Pulsed eddy current inspection system for nondestructive examination of irradiated fuel rods

    International Nuclear Information System (INIS)

    Yancey, M.E.

    1979-01-01

    An inspection system has been developed for nondestructive examination of irradiated fuel rods utilizing pulsed eddy current techniques. The system employs an encircling type pulsed eddy current transducer capable of sensing small defects located on both the inner and outer diameter fuel rod surfaces during a single scan. Pulsed eddy current point probes are used to provide fuel rod wall thikness data and an indication of radial defect location. Two linear variable differential transformers are used to provide information on fuel rod diameter variation. A microprocessor based control system is used to automatically scan fuel rods up to 4.06 meters in length at predetermined radial locations. Defects as small as 0.005 cm deep by 0.254 cm long by 0.005 cm wide have been detected on outside diameter surfaces of a 1.43 cm outside diameter fuel rod cladding with a 0.094 cm wall thickness and 0.010 cm deep by 0.254 cm long by 0.005 cm wide on the inside diameter surface

  19. Pulsed negative hydrogen source for currents up to one ampere

    International Nuclear Information System (INIS)

    Prelec, K.; Sluyters, T.

    1975-01-01

    During the 2nd Symposium on Ion Sources and Formation of Ion Beams, the development of a Mk II pulsed double slit magnetron source for the production of negative hydrogen ions was discussed. The source was capable of yielding beam currents up to 125 milliamperes, corresponding to current densities of 1.25 A/cm 2 . In order to increase negative hydrogen beam intensities by an order of magnitude (this would be quite useful for initial high energy neutral injector systems on Tokamaks), a larger, Mk III magnetron has been constructed, with the number of slits increased up to six. The idea was to utilize in a more efficient way the plasma width. In addition, such a source geometry will be more adaptable for beam formation and acceleration than single slit structures. With three extraction slits, a negative hydrogen yield of 300 mA was obtained with current densities of 1.2 A/cm 2 ; preliminary results with six extraction slits showed beam currents in excess of half an ampere with averaged current densities in excess of 0.75 A/cm 2 . (U.S.)

  20. Generic functional modelling of multi-pulse auto-transformer rectifier units for more-electric aircraft applications

    Directory of Open Access Journals (Sweden)

    Tao YANG

    2018-05-01

    Full Text Available The Auto-Transformer Rectifier Unit (ATRU is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced kVA ratings. Indeed, the ATRU has become a preferred AC/DC solution to supply power to the electric environment control system on-board future aircraft. In this paper, a general modelling method for ATRUs is introduced. The developed model is based on the fact that the DC voltage and current are strongly related to the voltage and current vectors at the AC terminals of ATRUs. In this paper, we carry on our research in modelling symmetric 18-pulse ATRUs and develop a generic modelling technique. The developed generic model can study not only symmetric but also asymmetric ATRUs. An 18-pulse asymmetric ATRU is used to demonstrate the accuracy and efficiency of the developed model by comparing with corresponding detailed switching SABER models provided by our industrial partner. The functional models also allow accelerated and accurate simulations and thus enable whole-scale more-electric aircraft electrical power system studies in the future. Keywords: Asymmetric transformer, Functional modelling, More-Electric Aircraft, Multi-pulse rectifier, Transformer rectifier unit

  1. Transformational leadership in sport: current status and future directions.

    Science.gov (United States)

    Arthur, Calum A; Bastardoz, Nicolas; Eklund, Robert

    2017-08-01

    Borrowed from organizational psychology, the concept of transformational leadership has now been applied to a sport context for a decade. Our review covers and critically discusses empirical articles published on this growing topic. However, because the majority of studies used cross-sectional designs and single-source questionnaires to tap what has been a fuzzy construct, current theoretical and methodological issues impede understanding of whether transformational leadership matters for sport outcomes. To make a difference to applied practice and policy, the transformational leadership construct requires a refined definition and stronger empirical tests allowing for robust causal inference. We highlight avenues for advancing research on transformational leadership in the sport context. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  2. Development of high current beam ns pulsed system

    CERN Document Server

    Shen Guan Ren; Gao Fu; Guan Xia Ling; LiuNaiYi

    2001-01-01

    The development of high current beam ns pulsed system of CPNG and its characteristic, main technological performance and application are introduced. Firstly, important parameters of the system are calculated using theoretical model, the design requirements of some important parts are understood. Some mistakes in physics conception are corrected. Second, the chopper is designed for parallel plate deflector, chopping aperture and sine wave voltage sweeping device. It is emphasized that the conception of parallel plate load impedance is the capacitance load, but not the 50 ohm load impedance. The dynamic capacitance value has been measured. The output emphasizes the output voltage amplitude, but not the output power for sweeping device. The display system of output sweeping voltage was set up and it is sure that the maximum output voltage(V-V) is >=4000 V. The klystron buncher are re-designed. It is emphasized to overcome difficulty of support high voltage electrode in the klystron and insulator of input sine wa...

  3. Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in

    2015-12-31

    Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

  4. Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

    International Nuclear Information System (INIS)

    Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu

    2015-01-01

    Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

  5. Research on Digital Output Verification Technology of Electronic DC Current Transformer

    Science.gov (United States)

    Chen, Yuanjie; Wang, Bin; Hu, Haoliang; Xiong, Qianzhu; Yang, Chunyan

    2017-05-01

    Aiming at the error of calibration system when conducting field calibration by electronic DC current transformer’s digital calibration system, an electronic DC current transformer’s digital calibration system based on protocol conversion is proposed and researched. Data frames outputted from merging unit are collected and converted by the system, the digital synchronization is realized by using the synchronous clock device to trigger the second pulse, and it is verified by the virtual instrument design software. The field calibration is conducted to some converter station digital dc current transformer under the rated current of 500A by using the calibration system. By calibrating and analyzing errors, the error is less than 0.075% when tested current is more than 40% of the rated current. According the standard in literature[1], performance of the calibration system is perfect, measured results perfectly meet the requirements of design, and the calibration system has great practical application value.

  6. Modeling the Pulse Signal by Wave-Shape Function and Analyzing by Synchrosqueezing Transform.

    Science.gov (United States)

    Wu, Hau-Tieng; Wu, Han-Kuei; Wang, Chun-Li; Yang, Yueh-Lung; Wu, Wen-Hsiang; Tsai, Tung-Hu; Chang, Hen-Hong

    2016-01-01

    We apply the recently developed adaptive non-harmonic model based on the wave-shape function, as well as the time-frequency analysis tool called synchrosqueezing transform (SST) to model and analyze oscillatory physiological signals. To demonstrate how the model and algorithm work, we apply them to study the pulse wave signal. By extracting features called the spectral pulse signature, and based on functional regression, we characterize the hemodynamics from the radial pulse wave signals recorded by the sphygmomanometer. Analysis results suggest the potential of the proposed signal processing approach to extract health-related hemodynamics features.

  7. Modeling the Pulse Signal by Wave-Shape Function and Analyzing by Synchrosqueezing Transform.

    Directory of Open Access Journals (Sweden)

    Hau-Tieng Wu

    Full Text Available We apply the recently developed adaptive non-harmonic model based on the wave-shape function, as well as the time-frequency analysis tool called synchrosqueezing transform (SST to model and analyze oscillatory physiological signals. To demonstrate how the model and algorithm work, we apply them to study the pulse wave signal. By extracting features called the spectral pulse signature, and based on functional regression, we characterize the hemodynamics from the radial pulse wave signals recorded by the sphygmomanometer. Analysis results suggest the potential of the proposed signal processing approach to extract health-related hemodynamics features.

  8. Ultra fast shutter driven by pulsed high current

    International Nuclear Information System (INIS)

    Zeng Jiangtao; Sun Fengju; Qiu Aici; Yin Jiahui; Guo Jianming; Chen Yulan

    2005-01-01

    Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5 μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90 kA to 140 kA and discharging current periods of approximately 13.1 μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities. (authors)

  9. High current photoemission with 10 picosecond uv pulses

    International Nuclear Information System (INIS)

    Fischer, J.; Srinivasan-Rao, T.; Tsang, T.

    1990-06-01

    The quantum efficiency and the optical damage threshold of various metals were explored with 10 ps, 266 nm, UV laser pulses. Efficiencies for Cu, Y, and Sm were: 1.4, 5, and 7 x 10 -4 , with damage thresholds about 100, 10, and 30 mJ/cm 2 . This would permit over 1 μC/cm 2 or current densities exceeding 100 kA/cm 2 . High charge and current densities of up to 66 kA/cm 2 were obtained on 0.25 mm diam cathodes, and 21 kA/cm 2 on a 3 mm diam yttrium cathode. The maximum currents were limited by space charge and the dc field. The experiments with small area illumination indicate that the emitted electrons spread transversely due to Coulomb repulsion and their initial transverse velocity. This increases the effective area above the cathode, reduces the space charge effect and increases emission density on the cathode. The quantum efficiency can be increased substantially by enhancing the field on the surface by either a suitable electrode geometry or microstructures on it. 14 refs., 12 figs., 3 tabs

  10. Pulse processing in optical fibers using the temporal Radon-Wigner transform

    Energy Technology Data Exchange (ETDEWEB)

    Bulus-Rossini, L A; Costanzo-Caso, P A; Duchowicz, R [Centro de Investigaciones Opticas, CONICET La Plata - CIC, Camino Parque Centenario y 506, C.C. 3 (1897) La Plata (Argentina); Sicre, E E, E-mail: lbulus@ing.unlp.edu.ar [Instituto de Tecnologia, Facultad de Ingenieria y Ciencias Exactas, Universidad Argentina de la Empresa, Lima 717, C1073AAO Buenos Aires (Argentina)

    2011-01-01

    It is presented the use of the temporal Radon-Wigner transform (RWT), which is the squared modulus of the fractional Fourier transform (FRT) for a varying fractional order p, as a processing tool for pulses with FWHM of ps-tens of ps. For analysis purposes, the complete numerical generation of the RWT with 0 < p < 1 is proposed to select a particular pulse shape related to a determined value of p. To this end, the amplitude and phase of the signal to be processed are obtained using a pulse characterization technique. To synthesize the processed pulse, the selected FRT irradiance is optically produced employing a photonic device that combines phase modulation and dispersive transmission. The practical implementation of this device involves a scaling factor that depends on the modulation and dispersive parameters. It is explored the variation of this factor in order to obtain an enhancement of the particular characteristic sought in the pulse to be synthesized. To illustrate the implementation of the proposed method, numerical simulations of its application to compress signals commonly found in fiber optic transmission systems, are performed. The examples presented consider chirped Gaussian pulses and pulses distorted by group velocity dispersion and self-phase modulation.

  11. Improving sensitivity of residual current transformers to high frequency earth fault currents

    Directory of Open Access Journals (Sweden)

    Czapp Stanislaw

    2017-09-01

    Full Text Available For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.

  12. Conversion of continuous-direct-current TIG welder to pulse-arc operation

    Science.gov (United States)

    Lien, D. R.

    1969-01-01

    Electronics package converts a continuous-dc tungsten-inert gas welder for pulse-arc operation. Package allows presetting of the pulse rate, duty cycle, and current value, and enables welding of various alloys and thicknesses of materials.

  13. Analysis on current limiting characteristics of a transformer type SFCL with two triggering current levels

    International Nuclear Information System (INIS)

    Lim, Sung-Hun; Ko, Seckcheol; Han, Tae-Hee

    2013-01-01

    Highlights: ► We suggested the transformer type SFCL with two triggering current levels. ► The short-circuit tests for the suggested SFCL was executed. ► The fault angle as the fault conditions to verify its operation was selected. ► The usefulness of the suggested SFCL was confirmed through the short-circuit test. -- Abstract: In this paper, the transformer type superconducting fault current limiter (SFCL) with two triggering current levels was suggested and its current limiting characteristics were analyzed. The structure of the suggested transformer type SFCL with two triggering current levels largely consists of two parts. One is the transformer with two magnetically coupled coils, which correspond to the primary winding and the secondary one connected with one high-T C superconducting (HTSC) element. The other is third coil, or, another secondary winding with one HTSC element, which is wound on the same iron core together with two coils. This suggested transformer type SFCL can limit the fault current by generating its limiting impedance with two different amplitudes, which are dependent on the initial amplitude of the fault current in case of the fault occurrence. To confirm the usefulness of the proposed SFCL, the current limiting tests of the SFCL according to the fault angle, one of the effective fault conditions to affect the amplitude of the initial fault current, were carried out and its effective limiting operations were discussed

  14. Development of pulsed high current drivers for fast Z-pinch

    International Nuclear Information System (INIS)

    Sun Fengju; Qiu Aici; Zeng Zhengzhong; Zeng Jiangtao; Kuai Bin; Yang Hailiang

    2006-01-01

    It is required that the peak current of high power pulsed drive for fast Z-pinch reaches 60 MA to realize inertial confine fusion (ICF) and high yield (HY). With the conventional technological methods similar to the Z or Saturn apparatus, increasing driver current further is impractical and difficult according to the cost, structure complexity and reliability of the driver, so it is necessary to develop novel fast pulsed high current driver. The present art-of-state and trends of fast Z-pinch driver are summarized, and the typical conceptual designs and technological methods on ICF/HY PRS (plasma radiation source) and destroying-level super X-ray simulators in USA and Russia are outlined, such as HCEI's UGXX1 driver and new Saturn driver based on fast linear transformer driver (FLTD) and novel driver based on fast Marx generator (FMG) with current of 15 MA. The crucial technological problems and requirements to investigate in the future are presented. (authors)

  15. Amplification of S-1 Spheromak current by an inductive current transformer

    International Nuclear Information System (INIS)

    Jardin, S.C.; Janos, A.; Yamada, M.

    1985-11-01

    We attempt to predict the consequences of adding an inductive current transformer (OH Transformer) to the present S-1 Spheromak experiment. Axisymmetric modeling with only classical dissipation shows an increase of toroidal current and a shrinking and hollowing of the current channel, conserving toroidal flux. These unstable profiles will undergo helical reconnection, conserving helicity K = ∫ A-vector x B-vector d tau while increasing the toroidal flux and decreasing the poloidal flux so that the plasma relaxes toward the Taylor state. This flux rearrangement is modeled by a new current viscosity term in the mean-field Ohm's law which conserves helicity and dissipates energy

  16. Frequency-Domain Maximum-Likelihood Estimation of High-Voltage Pulse Transformer Model Parameters

    CERN Document Server

    Aguglia, D; Martins, C.D.A.

    2014-01-01

    This paper presents an offline frequency-domain nonlinear and stochastic identification method for equivalent model parameter estimation of high-voltage pulse transformers. Such kinds of transformers are widely used in the pulsed-power domain, and the difficulty in deriving pulsed-power converter optimal control strategies is directly linked to the accuracy of the equivalent circuit parameters. These components require models which take into account electric fields energies represented by stray capacitance in the equivalent circuit. These capacitive elements must be accurately identified, since they greatly influence the general converter performances. A nonlinear frequency-based identification method, based on maximum-likelihood estimation, is presented, and a sensitivity analysis of the best experimental test to be considered is carried out. The procedure takes into account magnetic saturation and skin effects occurring in the windings during the frequency tests. The presented method is validated by experim...

  17. Computation of the current density in nonlinear materials subjected to large current pulses

    International Nuclear Information System (INIS)

    Hodgdon, M.L.; Hixson, R.S.; Parsons, W.M.

    1991-01-01

    This paper reports that the finite element method and the finite difference method are used to calculate the current distribution in two nonlinear conductors. The first conductor is a small ferromagnetic wire subjected to a current pulse that rises to 10,000 Amperes in 10 microseconds. Results from the transient thermal and transient magnetic solvers of the finite element code FLUX2D are used to compute the current density in the wire. The second conductor is a metal oxide varistor. Maxwell's equations, Ohm's law and the varistor relation for the resistivity and the current density of p = αj -β are used to derive a nonlinear differential equation. The solutions of the differential equation are obtained by a finite difference approximation and a shooting method. The behavior predicted by these calculations is in agreement with experiments

  18. Effect of current pulses on Lithium intercalation batteries

    NARCIS (Netherlands)

    Jongh, de P.E.; Notten, P.H.L.

    2002-01-01

    The effect of (dis)charge pulses on lithium-ion batteries is evaluated using an electronic network model. Simulations give insight into the effect of the pulses on the internal processes such as diffusion, migration, electrochemical reactions, heat generation, etc. on time scales from microseconds

  19. History and current status of commercial pulsed laser deposition equipment

    International Nuclear Information System (INIS)

    Greer, James A

    2014-01-01

    This paper will review the history of the scale-up of the pulsed laser deposition (PLD) process from small areas ∼1 cm 2 up to 10 m 2 starting in about 1987. It also documents the history of commercialization of PLD as various companies become involved in selling fully integrated laser deposition tools starting in 1989. The paper will highlight the current state of the art of commercial PLD equipment for R and D that is available on the market today from mainstream vendors as well as production-oriented applications directed at piezo-electric materials for microelectromechanical systems and high-temperature superconductors for coated-conductor applications. The paper clearly demonstrates that considerable improvements have been made to scaling this unique physical vapour deposition process to useful substrate sizes, and that commercial deposition equipment is readily available from a variety of vendors to address a wide variety of technologically important thin-film applications. (paper)

  20. A high current, short pulse electron source for wakefield accelerators

    International Nuclear Information System (INIS)

    Ho, Ching-Hung.

    1992-01-01

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed

  1. Zero sequence blocking transformers for multi-pulse rectifier in aerospace applications

    DEFF Research Database (Denmark)

    Yao, Wenli; Blaabjerg, Frede; Zhang, Xiaobin

    2014-01-01

    The power electronics technology plays an even more important role in the aerospace applications of More Electric Aircrafts (MEA). AutoTransformer Rectifier Units (ATRU) have been widely adopted in aircrafts due to its simplicity and reliability. In this paper, Zero Sequence Blocking Transformers...... (ZSBT) are employed in the DC link to realize parallel rectifier bridges for ATRU, being the proposed 24-pulse rectifier. A star-connected autotransformer is used in this topology to divide the primary side voltage into four three-phase voltage groups, among which there is a phase shift of 15......°. The autotransformer then feeds the load through rectifier bridges, which are in parallel with ZSBTs. Compared to the traditional method that is using six interphase transformers to parallel the rectifier bridges; the proposed 24-pulse rectifier only requires four ZSBTs. This will contribute to a reduction of weight...

  2. The influence of capacitor banks on transformer load current

    Directory of Open Access Journals (Sweden)

    Jović Aleksandar S.

    2017-01-01

    Full Text Available This paper deals with the influence of capacitor banks used for reactive energy compensation on total load current of 10/0,4 kV/kV distribution transformers. The analysis regards distribution area of Leskovac which comprehends town Leskovac and nearby settlements. Differently from previously published references that treat excessively reactive energy consumption, the value of reactive power on low voltage side of transformer taking into account the presence of capacitor banks is observed primarily in this paper. Both theoretically possible cases are restated on the basis of measurements: the compensation is adequate or inadequate. The cases of insufficient compensation and overcompensation are regarded to be inadequate compensation. The adequate compensation is achieved when reactive power oscillates around 0 kvar. The special case of adequate compensation, called conditionally adequate compensation, is introduced. For all four cases that describe reactive energy compensation, the calculation results of relative change of low voltage transformer current in the presence of capacitor banks, in comparison to the current without installed banks are presented.

  3. Testing of quality of welded joints using heavy-current pulse X-ray apparatuses

    International Nuclear Information System (INIS)

    Gusev, E.A.; Firstov, V.G.

    1988-01-01

    The possibilities of carrying out of radiographic and electroradiographic testing of quality of welded joints using heavy-current pulse X-ray apparatuses under the mode of single pulses are shown. Basic quantitative characteristics of radiographic testing permitting to detect the focus distance, sensitivity behaviour and optical density of image are presented. Peculiarities of electroradiographic image formation under the mode of single pulses of nanosecond range are analysed. The outlook of heavy-current pulse X-ray apparatus application under the mode of single pulses in industry is estimated

  4. Control of the electrode metal transfer by means of the welding current pulse generator

    Science.gov (United States)

    Knyaz'kov, A.; Pustovykh, O.; Verevkin, A.; Terekhin, V.; Shachek, A.; Knyaz'kov, S.; Tyasto, A.

    2016-04-01

    The paper presents a generator of welding current pulses to transfer an electrode metal into the molten pool. A homogeneous artificial line is used to produce near rectangular pulses. The homogeneous artificial line provides the minimum heat input with in the pulse to transfer the electrode metal, and it significantly decreases the impact of disturbances affecting this transfer. The pulse frequency does not exceed 300 Hz, and the duration is 0.6 ÷ 0.9 ms.

  5. Square pulse current wave’s effect on electroplated nickel hardness

    Directory of Open Access Journals (Sweden)

    Bibian Alonso Hoyos

    2006-09-01

    Full Text Available The effects of frequency, average current density and duty cycle on the hardness of electroplated nickel were studied in Watts and sulphamate solutions by means of direct and square pulse current. The results in Watts’ solutions revealed greater hardness at low duty cycle, high average current density and high square pulse current frequency. There was little variation in hardness in nickel sulphamate solutions to changes in duty cycle and wave frequency. Hardness values obtained in the Watts’ bath with square pulse current were higher than those achieved with direct current at the same average current density; such difference was not significant in sulphamate bath treatment.

  6. The study of Zn–Co alloy coatings electrochemically deposited by pulse current

    Directory of Open Access Journals (Sweden)

    Tomić Milorad V.

    2012-01-01

    Full Text Available The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2.

  7. Investigating the performances of a 1 MV high pulsed power linear transformer driver: from beam dynamics to x radiation

    Science.gov (United States)

    Maisonny, R.; Ribière, M.; Toury, M.; Plewa, J. M.; Caron, M.; Auriel, G.; d'Almeida, T.

    2016-12-01

    The performance of a 1 MV pulsed high-power linear transformer driver accelerator were extensively investigated based on a numerical approach which utilizes both electromagnetic and Monte Carlo simulations. Particle-in-cell calculations were employed to examine the beam dynamics throughout the magnetically insulated transmission line which governs the coupling between the generator and the electron diode. Based on the information provided by the study of the beam dynamics, and using Monte Carlo methods, the main properties of the resulting x radiation were predicted. Good agreement was found between these simulations and experimental results. This work provides a detailed understanding of mechanisms affecting the performances of this type of high current, high-voltage pulsed accelerator, which are very promising for a growing number of applications.

  8. Current status of pulse-power technology and applications at LBT, Nagaoka

    International Nuclear Information System (INIS)

    Yatsui, K.; Masuda, W.; Masugata, K.; Jiang, W.; Sekimoto, Y.; Imada, G.; Sonegawa, T.; Kang, X.D.

    1993-01-01

    Tight focusing of an ion beam was obtained by open-quotes Plasma Focus Diodeclose quotes. In addition to two-dimensionally line-focusing reported previously, the authors achieved point focusing of the proton beam. Quick charging Blumlein PFL was successfully developed. Using saturable cores as a charging inductor, the authors succeeded in the reduction of prepulse and quick charging of the Blumlein line. Output pulse of voltage ∼580 kV and current ∼24 kA with current rise time of less than 16 ns. Various thin films were quickly prepared by Ion-Beam Evaporation (IBE) such as ZnS, YBCO, BaTiO 3 , BN, B, C, ITO, apatite, etc. Basic characteristics were studied of ablation plasma produced by the irradiation of ion beam on the targets. Highly-repetitive excimer laser with subsonic gas flow is developed by Ludwieg charge tube. Basic characteristics of gas dynamics are studied by simulation. The authors developed a new circuit to excite highly-repetitive excimer lasers, where a saturable transformer is used in magnetic pulse compressor. To control lightning artificially, they studied basic plasma channel produced by TEA-CO 2 lasers in air

  9. High current, 0.5-MA, fast, 100-ns, linear transformer driver experiments

    Directory of Open Access Journals (Sweden)

    Michael G. Mazarakis

    2009-05-01

    Full Text Available The linear transformer driver (LTD is a new method for constructing high current, high-voltage pulsed accelerators. The salient feature of the approach is switching and inductively adding the pulses at low voltage straight out of the capacitors through low inductance transfer and soft iron core isolation. Sandia National Laboratories are actively pursuing the development of a new class of accelerator based on the LTD technology. Presently, the high current LTD experimental research is concentrated on two aspects: first, to study the repetition rate capabilities, reliability, reproducibility of the output pulses, switch prefires, jitter, electrical power and energy efficiency, and lifetime measurements of the cavity active components; second, to study how a multicavity linear array performs in a voltage adder configuration relative to current transmission, energy and power addition, and wall plug to output pulse electrical efficiency. Here we report the repetition rate and lifetime studies performed in the Sandia High Current LTD Laboratory. We first utilized the prototype ∼0.4-MA, LTD I cavity which could be reliably operated up to ±90-kV capacitor charging. Later we obtained an improved 0.5-MA, LTD II version that can be operated at ±100  kV maximum charging voltage. The experimental results presented here were obtained with both cavities and pertain to evaluating the maximum achievable repetition rate and LTD cavity performance. The voltage adder experiments with a series of double sized cavities (1 MA, ±100  kV will be reported in future publications.

  10. NMR pulse experiments data aquisition and Fast Fourier Transform assembler program for Mera-400 minicomputer

    International Nuclear Information System (INIS)

    Stachurowa, M.; Jasinski, A.

    1981-01-01

    An assembler program of NMR pulse experiments data acquisition digital signal filtering and Fast Fourier Transform (FFT) for the Mera-400 minicomputer interfaced to the pulsed NMR spectrometer is described. A phase correction subroutine of the program allows the phase correction to be made after the experiment. The program is run under the SOM-3 operating system. The program occupies 2.25 k 16 bit words of the computer memory, 3 k words are reserved for data. FFT computation time is 2.5 sec. for 1 k data points. (Author)

  11. Phase dependency of electrotonic spread of hyperpolarizing current pulses in the rabbit sinoatrial node

    NARCIS (Netherlands)

    Duivenvoorden, J. J.; Bouman, L. N.; Bukauskas, F. F.; Opthof, T.; Jongsma, H. J.

    1990-01-01

    Electrotonic current spread in the SA node of the rabbit was measured by means of hyperpolarizing current pulses (1 to 10 microA, 60 ms), which were injected intracellularly through a K(+)-perfused suction electrode. The pulses were applied at the beginning, middle or end of the diastolic

  12. Beam current transformer (BCT) for experiment WA1/2

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    In experiment WA1/2, a 400 GeV proton beam from the SPS was directed at a target, downstream of which a hadron line selected, in several narrow momentum bands, a beam of either pi+ and K+ or pi- and K-. These neutrino-parent particles, before entering a 292 m long decay tunnel, passed through a set of 2 BCTs of a design seen here. They measured the hadron intensity (10^10 to 10^11 particles/pulse) with a precision of the order of 1%. There were 2 of them, for enhanced precision and confidence. After the discovery of neutral currents in the Gargamelle-experiment, WA1/2 was the first follow-up, high-precision experiment (Z.Phys.C35, 443-452, 1987 and Z.Phys.C45, 361-379, 1990). See also 7706516X.

  13. Pulsed critical current measurements of NbTi in perpendicular and parallel pulsed magnetic fields using the new Cryo-BI-Pulse System

    International Nuclear Information System (INIS)

    Stehr, V; Tan, K S; Hopkins, S C; Glowacki, B A; Keyser, A De; Bockstal, L Van; Deschagt, J

    2006-01-01

    Rapid transport current versus high magnetic field characterisation of high-irreversibility type II superconductors is important to maximise their critical parameters. HTS conductors are already used to produce insert coils that increase the fields of conventional magnets made from NbTi (Nb, Ta) 3 Sn and Nb 3 Al wires. There is fundamental interest in the study of HTS tapes and wires in magnetic fields higher than 21T, the current limit of superconducting magnets producing a DC field. Such fields can be obtained by using pulse techniques. High critical currents cannot be routinely measured with a continuous current applied at liquid helium, hydrogen or neon temperatures because of thermal and mechanical effects. A newly developed pulsed magnetic field and pulsed current system which allows rapid J c (B, T) measurements of the whole range of superconducting materials was tested with a multifilamentary NbTi wire in perpendicular and parallel orientations

  14. Pulsed high-current electron source: Final report

    International Nuclear Information System (INIS)

    Spindt, C.A.

    1988-10-01

    The objective of this investigation was to investigate ways to realize the cathode's potential as a source for high power pulse operation. The questions that needed to be studied were those of large area coverage, maximum emission that the cathode arrays are capable of producing practically, uniformity of emission over large areas, and the ability to operate with high voltage anodes. 9 figs

  15. Effects of finite pulse width on two-dimensional Fourier transform electron spin resonance.

    Science.gov (United States)

    Liang, Zhichun; Crepeau, Richard H; Freed, Jack H

    2005-12-01

    Two-dimensional (2D) Fourier transform ESR techniques, such as 2D-ELDOR, have considerably improved the resolution of ESR in studies of molecular dynamics in complex fluids such as liquid crystals and membrane vesicles and in spin labeled polymers and peptides. A well-developed theory based on the stochastic Liouville equation (SLE) has been successfully employed to analyze these experiments. However, one fundamental assumption has been utilized to simplify the complex analysis, viz. the pulses have been treated as ideal non-selective ones, which therefore provide uniform irradiation of the whole spectrum. In actual experiments, the pulses are of finite width causing deviations from the theoretical predictions, a problem that is exacerbated by experiments performed at higher frequencies. In the present paper we provide a method to deal with the full SLE including the explicit role of the molecular dynamics, the spin Hamiltonian and the radiation field during the pulse. The computations are rendered more manageable by utilizing the Trotter formula, which is adapted to handle this SLE in what we call a "Split Super-Operator" method. Examples are given for different motional regimes, which show how 2D-ELDOR spectra are affected by the finite pulse widths. The theory shows good agreement with 2D-ELDOR experiments performed as a function of pulse width.

  16. Simulation investigation of thermal phase transformation and residual stress in single pulse EDM of Ti-6Al-4V

    Science.gov (United States)

    Tang, Jiajing; Yang, Xiaodong

    2018-04-01

    The thermal phase transformation and residual stress are ineluctable in the electrical discharge machining (EDM) process, and they will greatly affect the working performances of the machined surface. This paper presents a simulation study on the thermal phase transformation and residual stress in single-pulse EDM of Ti-6Al-4V, which is the most popular titanium alloy in fields such as aircraft engine and some other leading industries. A multi-physics model including thermal, hydraulic, metallography and structural mechanics was developed. Based on the proposed model, the thickness and metallographic structure of the recast layer and heat affected layer (HAZ) were investigated. The distribution and characteristics of residual stress around the discharge crater were obtained. The recast layer and HAZ at the center of crater are found to be the thinnest, and their thicknesses gradually increase approaching the periphery of the crater. The recast layer undergoes a complete α‧ (martensitic) transformation, while the HAZ is mainly composed by the α  +  β  +  α‧ three-phase microstructure. Along the depth direction of crater, the Von Mises stress increases first and then decreases, reaching its maximal value near the interface of recast layer and HAZ. In the recast layer, both compressive stress component and tensile stress component are observed. ANOVA results showed that the influence of discharge current on maximal tensile stress is more significant than that of pulse duration, while the pulse duration has more significant influence on average thickness of the recast layer and the depth location of the maximal tensile stress. The works conducted in this study will help to evaluate the quality and integrity of EDMed surface, especially when the non-destructive testing is difficult to achieve.

  17. Thirty-six pulse rectifier scheme based on zigzag auto-connected transformer

    Directory of Open Access Journals (Sweden)

    Xiao-Qiang Chen

    2016-03-01

    Full Text Available In this paper, a low kilo-volt-ampere rating zigzag connected autotransformer based 36-pulse rectifier system supplying vector controlled induction motor drives (VCIMD is designed, modeled and simulated. Detailed design procedure and magnetic rating calculation of the proposed autotransformer and interphase reactor is studied. Moreover, the design process of the autotransformer is modified to make it suitable for retrofit applications. Simulation results confirm that the proposed 36-pulse rectifier system is able to suppress less than 35th harmonics in the utility line current. The influence of load variation and load character is also studied to demonstrate the performance and effectiveness of the proposed 36-pulse rectifiers. A set of power quality indices at AC mains and DC link are presented to compare the performance of 6-, 24- and 36-pulse AC-DC converters.

  18. Novel design of high voltage pulse source for efficient dielectric barrier discharge generation by using silicon diodes for alternating current

    Science.gov (United States)

    Truong, Hoa Thi; Hayashi, Misaki; Uesugi, Yoshihiko; Tanaka, Yasunori; Ishijima, Tatsuo

    2017-06-01

    This work focuses on design, construction, and optimization of configuration of a novel high voltage pulse power source for large-scale dielectric barrier discharge (DBD) generation. The pulses were generated by using the high-speed switching characteristic of an inexpensive device called silicon diodes for alternating current and the self-terminated characteristic of DBD. The operation started to be powered by a primary DC low voltage power supply flexibly equipped with a commercial DC power supply, or a battery, or DC output of an independent photovoltaic system without transformer employment. This flexible connection to different types of primary power supply could provide a promising solution for the application of DBD, especially in the area without power grid connection. The simple modular structure, non-control requirement, transformer elimination, and a minimum number of levels in voltage conversion could lead to a reduction in size, weight, simple maintenance, low cost of installation, and high scalability of a DBD generator. The performance of this pulse source has been validated by a load of resistor. A good agreement between theoretically estimated and experimentally measured responses has been achieved. The pulse source has also been successfully applied for an efficient DBD plasma generation.

  19. Current indications and new applications of intense pulsed light.

    Science.gov (United States)

    González-Rodríguez, A J; Lorente-Gual, R

    2015-06-01

    Intense pulsed light (IPL) systems have evolved since they were introduced into medical practice 20 years ago. Pulsed light is noncoherent, noncollimated, polychromatic light energy emitted at different wavelengths that target specific chromophores. This selective targeting capability makes IPL a versatile therapy with many applications, from the treatment of pigmented or vascular lesions to hair removal and skin rejuvenation. Its large spot size ensures a high skin coverage rate. The nonablative nature of IPL makes it an increasingly attractive alternative for patients unwilling to accept the adverse effects associated with other procedures, which additionally require prolonged absence from work and social activities. In many cases, IPL is similar to laser therapy in effectiveness, and its versatility, convenience, and safety will lead to an expanded range of applications and possibilities in coming years. Copyright © 2014 Elsevier España, S.L.U. and AEDV. All rights reserved.

  20. Letter Report on 500 nA Pulsed Current from Field Ionization Source

    International Nuclear Information System (INIS)

    Ellsworth, Jennifer L.

    2013-01-01

    We recently produced a milestone 500 nA of pulsed current using 40 Ir field ionizer electrodes in our ion source. In conclusion, we have produced the milestone pulsed current of 500 nA using 40 electrochemically etched iridium tips in a field ionization source. The pulsed current output is repeatable and scales as expected with gas fill pressure and bias voltage. We expect these current will be sufficient to produce neutral yields of 1 · 10 7 DT n/s.

  1. Featuring of transient tunneling current by voltage pulse and application to an electrochemical biosensor

    Science.gov (United States)

    Yun, Jun Yeon; Lee, Won Cheol; Choi, Seong Wook; Park, Young June

    2018-03-01

    We suggest a voltage pulse method for detecting the transient tunneling current component (faradaic current component) in a metal/redox-active monolayer/electrolyte system. After applying the pulse to the metal electrode, the capacitive current prevails; therefore, it is difficult to extract the tunneling current, which carries information on the biochemical reactions occurring between the biomarkers in the electrolyte and the self-assembled monolayer (SAM) as the probe peptide system. Instead of waiting until the capacitive current diminishes, and thereby, the tunneling current also decreases, we try to extract the tunneling current in an early stage of the pulse. The method is based on the observation that the capacitive current becomes symmetrized in the positive and negative pulses after introducing the SAM on the metal electrode. When the energy level of the redox molecule is higher than the Fermi level of the metal under zero-bias condition, the tunneling current in the negative pulse can be extracted by subtracting the capacitive current obtained from the positive pulse, where the tunneling current is neglected. The experiment conducted for detecting trypsin as a biomarker shows that the method enhances the sensitivity and the specific-to-nonspecific ratio of the sensor device in the case of the nonspecific protein-abundant electrolyte solution, as evinced by cyclic voltammetry measurements in comparison.

  2. Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators

    International Nuclear Information System (INIS)

    Hu Yixiang; Qiu Aici; Sun Fengju; Huang Tao; Cong Peitian; Wang Liangping; Zeng Jiangtao; Li Yan; Zhang Xinjun; Lei Tianshi

    2011-01-01

    Based on the transmission line code TLCODE, a 1D circuit model for a transmission-line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy-transport and power-transport for a transmission-line impedance transformer as functions of ψ (the ratio of the output impedance to the input impedance of the transformer) and Γ (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in Γ, from 0 to ∞, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%. (fusion engineering)

  3. Fast and efficient STT switching in MTJ using additional transient pulse current

    Science.gov (United States)

    Pathak, Sachin; Cha, Jongin; Jo, Kangwook; Yoon, Hongil; Hong, Jongill

    2017-06-01

    We propose a profile of write pulse current-density to switch magnetization in a perpendicular magnetic tunnel junction to reduce switching time and write energy as well. Our simulated results show that an overshoot transient pulse current-density (current spike) imposed to conventional rectangular-shaped pulse current-density (main pulse) significantly improves switching speed that yields the reduction in write energy accordingly. For example, we could dramatically reduce the switching time by 80% and thereby reduce the write energy over 9% in comparison to the switching without current spike. The current spike affects the spin dynamics of the free layer and reduces the switching time mainly due to spin torque induced. On the other hand, the large Oersted field induced causes changes in spin texture. We believe our proposed write scheme can make a breakthrough in magnetic random access memory technology seeking both high speed operation and low energy consumption.

  4. Harp, a short pulse, high current electron beam accelerator

    International Nuclear Information System (INIS)

    Prestwich, K.R.

    1974-01-01

    A 3 MV, 800 kA, 24 ns electron beam accelerator is described and the results of initial switching experiments are discussed. The generator will provide a source for studying the physics of processes leading to electron beam driven, inertially confined fusion. The major components of the accelerator are two diodes with a common anode, twelve oil-dielectric Blumleins with low jitter (less than 2 ns) multichannel switches, three intermediate storage capacitors, a trigger pulse generator and two Marx generators. (U.S.)

  5. Submicrosecond linear pulse transformer for 800 kV voltage with modular low-inductance primary power supply

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, Yu. A.; Krastelev, E. G., E-mail: ekrastelev@yandex.ru; Popov, G. V.; Sedin, A. A.; Feduschak, V. F. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2016-12-15

    A pulsed power source with voltage amplitude up to 800 kV for fast charging (350–400 ns) of the forming line of a high-current nanosecond accelerator is developed. The source includes capacitive energy storage and a linear pulse transformer. The linear transformer consists of a set of 20 inductors with circular ferromagnetic cores surrounded by primary windings inside of which a common stock adder of voltage with film-glycerol insulation is placed. The primary energy storage consists of ten modules, each of which is a low-inductance assembly of two capacitors with a capacitance of 0.35 μF and one gas switch mounted in the same frame. The total energy stored in capacitors is 5.5 kJ at the operating voltage of 40 kV. According to test results, the parameters of the equivalent circuit of the source are the following: shock capacitance = 17.5 nF, inductance = 2 μH, resistance = 3.2 Ω.

  6. Thyristor current-pulse generator for betatron electromagnet with independent low-voltage supply

    International Nuclear Information System (INIS)

    Baginskii, B.A.; Makarevich, V.N.; Shtein, M.M.

    1989-01-01

    A thyristor generator is described that produces unipolar current pulses in the winding of a betatron electromagnet. The voltage on the electro-magnet is increased and the shape of the current pulses is improved by use of an intermediate inductive storage device. The current pulses have a duration of 11 msec, an amplitude of 190 A, and a repetition frequency of 50 Hz. The maximum magnetic-field energy is 450 J, the voltage on the electromagnet winding is 1.5 kV, and the supply voltage is 27 V

  7. Measurements of picosecond pulses of a high-current electron accelerator

    International Nuclear Information System (INIS)

    Zheltov, K.A.; Petrenko, A.N.; Turundaevskaya, I.G.; Shalimanov, V.F.

    1997-01-01

    The duration of a picosecond high-current accelerator electron beam pulse duration is measured and its shape is determined using a measuring line, comprising a Faraday cup, a radiofrequency cable of minor length and a wide-band SRG-7 oscillograph. The procedure of data reconstruction according to regularization method is applied to determine the actual shape of the pulse measured

  8. Saturation of subjective reward magnitude as a function of current and pulse frequency.

    Science.gov (United States)

    Simmons, J M; Gallistel, C R

    1994-02-01

    In rats with electrodes in the medial forebrain bundle, the upper portion of the function relating the experienced magnitude of the reward to pulse frequency was determined at currents ranging from 100 to 1,000 microA. The pulse frequency required to produce an asymptotic level of reward was inversely proportional to current except at the lowest currents and highest pulse frequencies. At a given current, the subjective reward magnitude functions decelerated to an asymptote over an interval in which the pulse frequency doubled or tripled. The asymptotic level of reward was approximately constant for currents between 200 and 1,000 microA but declined substantially at currents at or below 100 microA and pulse frequencies at or above 250 to 400 pulses per second. The results are consistent with the hypothesis that the magnitude of the experienced reward depends only on the number of action potentials generated by the train of pulses in the bundle of reward-relevant axons.

  9. A novel structure of transmission line pulse transformer with mutually coupled windings.

    Science.gov (United States)

    Yu, Binxiong; Su, Jiancang; Li, Rui; Zhao, Liang; Zhang, Xibo; Wang, Junjie

    2014-03-01

    A novel structure of transmission line transformer (TLT) with mutually coupled windings is described in this paper. All transmission lines except the first stage of the transformer are wound on a common ferrite core for the TLT with this structure. A referral method was introduced to analyze the TLT with this structure, and an analytic expression of the step response was derived. It is shown that a TLT with this structure has a significantly slower droop rate than a TLT with other winding structures and the number of ferrite cores needed is largely reduced. A four-stage TLT with this structure was developed, whose input and output impedance were 4.2 Ω and 67.7 Ω, respectively. A frequency response test of the TLT was carried out. The test results showed that pulse response time of the TLT is several nanoseconds. The TLT described in this paper has the potential to be used as a rectangle pulse transformer with very fast response time.

  10. Development of high current electron source using photoemission from metals with ultrashort laser pulses

    International Nuclear Information System (INIS)

    Tsang, T.; Srinivasan-Rao, T.; Fischer, J.

    1990-10-01

    We summarize the studies of photoemission from metal photocathodes using picosecond pulses in the UV (4.66 eV) wavelength and femtosecond laser pulses in the visible (2 eV) wavelengths. To achieve high current density yield from metal photocathodes, multiphoton photoemission using femtosecond laser pulses are suggested. Electron yield improvement incorporating surface photoemission and surface plasmon resonance in metals and metal films are demonstrated. We examine the possibility of the nonlinear photoemission process overtaking the linear process, and identity some possible complexity. To extract the large amount of electrons free of space charge, a pulsed high voltage is designed; the results of the preliminary test are presented. Finally, for the first time, the width of the electron temporal profiles are measured, utilizing the nonlinear photoelectric effect, to below 100 fsec time regime. The results indicated that the electron pulse duration follows the laser pulses and are not limited by the material. 8 refs., 15 figs

  11. The transformation of optical bistability effect and of generated pulses in operation of a DFB laser with two sections

    International Nuclear Information System (INIS)

    Nguyen Van Phu; Dinh Van Hoang

    2005-01-01

    In this paper is presented the transformation of characteristics of optical bistability effect and of generated pulses in operation of a DFB laser with two sections. By solving the rate equations describing the operation of this laser the appearance of optical bistability effect in stationary regime and of short pulses in transient regime is obtained. With the variation of dynamical laser parameter we can evaluate the transformation indicated above. The method of examination used here is simple for determining the influence of any dynamical laser parameter on characteristics of optical bistability effect and generated pulses. (author)

  12. A hybrid pulse combining topology utilizing the combination of modularized avalanche transistor Marx circuits, direct pulse adding, and transmission line transformer.

    Science.gov (United States)

    Li, Jiangtao; Zhao, Zheng; Sun, Yi; Liu, Yuhao; Ren, Ziyuan; He, Jiaxin; Cao, Hui; Zheng, Minjun

    2017-03-01

    Numerous applications driven by pulsed voltage require pulses to be with high amplitude, high repetitive frequency, and narrow width, which could be satisfied by utilizing avalanche transistors. The output improvement is severely limited by power capacities of transistors. Pulse combining is an effective approach to increase the output amplitude while still adopting conventional pulse generating modules. However, there are drawbacks in traditional topologies including the saturation tendency of combining efficiency and waveform oscillation. In this paper, a hybrid pulse combining topology was adopted utilizing the combination of modularized avalanche transistor Marx circuits, direct pulse adding, and transmission line transformer. The factors affecting the combining efficiency were determined including the output time synchronization of Marx circuits, and the quantity and position of magnetic cores. The numbers of the parallel modules and the stages were determined by the output characteristics of each combining method. Experimental results illustrated the ability of generating pulses with 2-14 kV amplitude, 7-11 ns width, and a maximum 10 kHz repetitive rate on a matched 50-300 Ω resistive load. The hybrid topology would be a convinced pulse combining method for similar nanosecond pulse generators based on the solid-state switches.

  13. Development of high-current pulsed heavy-ion-beam technology for applications to materials processing

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroaki; Ochiai, Yasushi; Masugata, Katsumi [University of Toyama, Toyama (Japan)

    2011-12-15

    Development of intense pulsed heavy ion beam technology for applications to materials processing is described. We have developed a magnetically insulated ion diode for the generation of intense pulsed metallic ion beams in which a vacuum arc plasma gun is used as the ion source. When the ion diode was successfully operated at a diode voltage of 220 kV and a diode current of 10 kA, an ion beam with an ion current density of >200 A/cm{sup 2} and a pulse duration of 40 ns was obtained. The ion composition was evaluated by using a Thomson parabola spectrometer, and the ion beam consisted of aluminum ions (Al{sup (1-3)+}) with an energy of 140 - 740 keV and protons with an energy of 160 - 190 keV; the purity was estimated to be 89%, which was much higher than that of the pulsed ion beam produced in a conventional ion diode. The development of a bipolar pulse accelerator (BPA) was reported in order to improve the purity of intense pulsed ion beams. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. When a bipolar pulse with a voltage of {+-}90 kV and a pulse duration of about 65 ns was applied to the drift tube of the BPA, the ion beam with an ion current density of 2 A/cm{sup 2} and a pulse duration of 30 ns was observed 25 mm downstream from the cathode surface, which suggested bipolar pulse acceleration.

  14. Multichannel computerized control system of current pulses in LIU-30 electron accelerator

    CERN Document Server

    Gerasimov, A I; Kulgavchuk, V V; Pluzhnikov, A V

    2002-01-01

    In LIU-30 power linear pulsed induction electron accelerator (40 MeV, 10 kA, 25 ns) 288 radial lines with water insulation serve as energy accumulators and shapers of accelerating voltage pulses. The lines are charged simultaneously up to 500 kV using a system comprising 72 Arkadiev-Marx screened generators. To control parameter of synchronous pulses of charging current with up to 60 kA amplitude and 0.85 mu s duration in every of 72 charging circuits one applies a computer-aided system. Current pulse is recorded at output of every generator using the Rogowski coil signal from which via a cable line is transmitted to an analog-digital converter, is processed with 50 ns sampling and is recorded to a memory unit. Upon actuation of accelerator the signals are sequentially or selectively displayed and are compared with pulse typical shape

  15. Eddy-current inspection of ferromagnetic tubing using pulsed magnetic saturation

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, C V; Deeds, W E

    1986-07-01

    A pulsed eddy-current system has been designed and developed for nondestructive evaluation of 2.25Cr-1Mo steam generator tubing from the bore side. Since the tubing is ferromagnetic, a large current pulse is sent through a driver coil to produce magnetic saturation all the way through the tube wall. A pickup coil produces an output pulse that is dependent upon the tube properties as well as the driving pulse. The output pulse heights at selected times are used as data that are computer-correlated with calibration data taken from machined standards. Performance data, circuit diagrams, and computer programs are given for the system, which has been demonstrated to detect small flaws located near the outside of a thick ferromagnetic tube.

  16. Nanosecond field emitted and photo-field emitted current pulses from ZrC tips

    International Nuclear Information System (INIS)

    Ganter, R.; Bakker, R.J.; Gough, C.; Paraliev, M.; Pedrozzi, M.; Le Pimpec, F.; Rivkin, L.; Wrulich, A.

    2006-01-01

    In order to find electron sources with low thermal emittance, cathodes based on single tip field emitter are investigated. Maximum peak current, measured from single tip in ZrC with a typical apex radius around 1 μm, are presented. Voltage pulses of 2 ns duration and up to 50 kV amplitude lead to field emission current up to 470 mA from one ZrC tip. Combination of high applied electric field with laser illumination gives the possibility to modulate the emission with laser pulses. Nanoseconds current pulses have been emitted with laser pulses at 1064 nm illuminating a ZrC tip under high-DC electric field. The dependence of photo-field emitted current with the applied voltage can be explained by the Schottky effect

  17. The effect of pulse current on energy saving during Electrochemical Chloride Extraction (ECE) in concrete

    DEFF Research Database (Denmark)

    Sun, Tian R.; Geiker, Mette R.; Ottosen, Lisbeth M.

    2012-01-01

    Energy consumption is a factor influencing the cost of Electrochemical Chloride Extraction (ECE) in concrete. The aims of this work were to investigate the possibility for energy saving when using a pulsed electric field during ECE and the effect of the pulsed current on removal of chloride. Four...... experiments with artificially polluted concrete under same charge transfer were conducted. Results showed that the energy consumption was decreased 15% by pulse current in experiments with 0.2 mA/cm2 current density, which was higher than that of 0.1 mA/cm2 experiments with a decrease of 9.6%. When comparing...... the voltage drop at different parts of the experimental cells, it was found that the voltage drop of the area across the concrete was the major contributor to energy consumption, and results indicated that the pulse current could decrease the voltage drop of this part by re-distribution of ions in pore fluid...

  18. Nanosecond field emitted and photo-field emitted current pulses from ZrC tips

    Energy Technology Data Exchange (ETDEWEB)

    Ganter, R. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland)]. E-mail: romain.ganter@psi.ch; Bakker, R.J. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Gough, C. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Paraliev, M. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Pedrozzi, M. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Le Pimpec, F. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Rivkin, L. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Wrulich, A. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland)

    2006-09-15

    In order to find electron sources with low thermal emittance, cathodes based on single tip field emitter are investigated. Maximum peak current, measured from single tip in ZrC with a typical apex radius around 1 {mu}m, are presented. Voltage pulses of 2 ns duration and up to 50 kV amplitude lead to field emission current up to 470 mA from one ZrC tip. Combination of high applied electric field with laser illumination gives the possibility to modulate the emission with laser pulses. Nanoseconds current pulses have been emitted with laser pulses at 1064 nm illuminating a ZrC tip under high-DC electric field. The dependence of photo-field emitted current with the applied voltage can be explained by the Schottky effect.

  19. Application-oriented research on plasma channeling of a large pulsed current

    International Nuclear Information System (INIS)

    Liu Jingye

    2000-01-01

    Utilizing the avalanche effect of plasma produced by the collision of energetic primary electrons with hydrogen molecules in a plasma, channeling of a large pulsed current is achieved, with the plasma acting as the carrier

  20. Experimental investigation of powerful pulse current generators based on capacitive storage and explosive magnetic generators

    Science.gov (United States)

    Shurupov, A. V.; Zavalova, V. E.; Kozlov, A. V.; Shurupov, M. A.; Povareshkin, M. N.; Kozlov, A. A.; Shurupova, N. P.

    2018-01-01

    Experimental models of microsecond duration powerful generators of current pulses on the basis of explosive magnetic generators and voltage impulse generator have been developed for the electromagnetic pulse effects on energy facilities to verify their stability. Exacerbation of voltage pulse carried out through the use of electro explosive current interrupter made of copper wires with diameters of 80 and 120 μm. Experimental results of these models investigation are represented. Voltage fronts about 100 ns and the electric field strength of 800 kV/m are registered.

  1. The detailed characteristics of positive corona current pulses in the line-to-plane electrodes

    Science.gov (United States)

    Xuebao, LI; Dayong, LI; Qian, ZHANG; Yinfei, LI; Xiang, CUI; Tiebing, LU

    2018-05-01

    The corona current pulses generated by corona discharge are the sources of the radio interference from transmission lines and the detailed characteristics of the corona current pulses from conductor should be investigated in order to reveal their generation mechanism. In this paper, the line-to-plane electrodes are designed to measure and analyze the characteristics of corona current pulses from positive corona discharges. The influences of inter-electrode gap and line diameters on the detail characteristics of corona current pulses, such as pulse amplitude, rise time, duration time and repetition frequency, are carefully analyzed. The obtained results show that the pulse amplitude and the repetition frequency increase with the diameter of line electrode when the electric fields on the surface of line electrodes are same. With the increase of inter-electrode gap, the pulse amplitude and the repetition frequency first decrease and then turn to be stable, while the rise time first increases and finally turns to be stable. The distributions of electric field and space charges under the line electrodes are calculated, and the influences of inter-electrode gap and line electrode diameter on the experimental results are qualitatively explained.

  2. Manipulation of high-current pulses for heavy-ion fusion

    International Nuclear Information System (INIS)

    Sharp, W.M.; Callahan, D.A.; Griedman, A.; Grote, D.P.

    1996-01-01

    For efficient induction-driven heavy-ion fusion, the current profile along a pulse must be modified in a non-selfsimilar manner between the accelerator and the target. In the accelerator, the pulse should have a duration of at least 50 ns in order to make efficient use of the induction cores, and the current should by nearly uniform along the pulse to minimize the aperture. In contrast, the optimal current profile on target consists of a main pulse of about 10 ns preceded by a longer low-current 'foot.' This pulse-shape manipulation must be carried out at the final pulse energy (5-10 GeV for 200 amu ions) in the presence of a large nonlinear longitudinal space-charge field. A straightforward method is presented here for doing the required pulse shaping. Induction-ceU voltages are generated using idealized beam profiles both in the accelerator and on target, and they are verified and checked for error sensitivity using the fluid/envelope code CIRCE

  3. Muscle oxygenation of vastus lateralis and medialis muscles during alternating and pulsed current electrical stimulation.

    Science.gov (United States)

    Aldayel, Abdulaziz; Muthalib, Makii; Jubeau, Marc; McGuigan, Michael; Nosaka, Kazunori

    2011-05-01

    This study compared between alternating and pulsed current electrical muscle stimulation (EMS) for muscle oxygenation and blood volume during isometric contractions. Nine healthy men (23-48 years) received alternating current EMS (2500 Hz) modulated at 75 Hz on the knee extensors of one leg, and pulsed current EMS (75 Hz) for the other leg separated by 2 weeks in a randomised, counter-balanced order. Pulse duration (400 μs), on-off ratio (5-15 s) and other stimulation parameters were matched between conditions and 30 isometric contractions were induced at the knee joint angle of 100° (0° full extension). Changes in tissue oxygenation index (∆TOI) and total hemoglobin volume (∆tHb) of vastus lateralis and medialis muscles over 30 contractions were assessed by a near-infrared spectroscopy, and were compared between conditions by a two-way repeated measures ANOVA. Peak torque produced during EMS increased over 30 contractions in response to the increase in the stimulation intensity for pulsed current, but not for the alternating current EMS. The torque during each isometric contraction was less stable in alternating than pulsed current EMS. The changes in ∆TOI amplitude during relaxation phases and ∆tHb amplitude were not significantly different between conditions. However, the decreases in ∆TOI amplitude during contraction phases from baseline were significantly (P < 0.05) greater for the pulsed current than alternating current from the 18th contraction (-15.6 ± 2.3 vs. -8.9 ± 1.8%) to 30th contraction (-10.7 ± 1.8 vs. -4.8 ± 1.5%). These results suggest that the muscles were less activated in the alternating current EMS when compared with the pulsed current EMS.

  4. Optimizing pulsed current micro plasma arc welding parameters to ...

    African Journals Online (AJOL)

    user

    The weld joints fabricated using peak current of 7 Amps, ... that would lead to excellent mechanical properties, different methods and approaches have been used. ... with an appropriate empirical model is approximated, being the function.

  5. SWITCH MODE PULSE WIDTH MODULATED DC-DC CONVERTER WITH MULTIPLE POWER TRANSFORMERS

    DEFF Research Database (Denmark)

    2009-01-01

    A switch mode pulse width modulated DC-DC power converter comprises at least one first electronic circuit on a input side (1) and a second electronic circuit on a output side (2). The input side (1) and the output side (2) are coupled via at least two power transformers (T1, T2). Each power...... transformer (T1, T2) comprises a first winding (T1a, T2a) arranged in a input side converter stage (3, 4) on the input side (1) and a second winding (T1 b, T2b) arranged in a output side converter stage (5) on the output side (2), and each of the windings (T1a, T1 b, T2a, T2b) has a first end and a second end....... The first electronic circuit comprises terminals (AO, A1) for connecting a source or a load, at least one energy storage inductor (L) coupled in series with at least one of the first windings (T1a, T2a) of the power transformers (T1, T2), and for each power transformer (T1, T2), an arrangement of switches...

  6. Electromagnetic pulse-driven spin-dependent currents in semiconductor quantum rings.

    Science.gov (United States)

    Zhu, Zhen-Gang; Berakdar, Jamal

    2009-04-08

    We investigate the non-equilibrium charge and spin-dependent currents in a quantum ring with a Rashba spin-orbit interaction (SOI) driven by two asymmetric picosecond electromagnetic pulses. The equilibrium persistent charge and persistent spin-dependent currents are investigated as well. It is shown that the dynamical charge and the dynamical spin-dependent currents vary smoothly with a static external magnetic flux and the SOI provides a SU(2) effective flux that changes the phases of the dynamic charge and the dynamic spin-dependent currents. The period of the oscillation of the total charge current with the delay time between the pulses is larger in a quantum ring with a larger radius. The parameters of the pulse fields control to a certain extent the total charge and the total spin-dependent currents. The calculations are applicable to nanometre rings fabricated in heterojunctions of III-V and II-VI semiconductors containing several hundreds of electrons.

  7. Low-induction pulse current generator with a volume bus arrangement

    International Nuclear Information System (INIS)

    Bocharov, Yu.N.; Krivosheev, S.I.; Lapin, N.G.; Shneerson, G.A.

    1993-01-01

    Pulse current generator (PC6) with 38 kj stored energy designed for up to 50 kV charging voltage used to obtain magnetic fields within megagauss range, is described. Space (volume) bus arrangement of its modules is used to reduce eigen inductance of PC6. Current is commutated by solid-body spark gaps. Under 3uH inductive load PC6 provides for formation of up to 2.25 MA current pulse with 3.3x10 12 A/s pulse rise time. Technique to determine low inductances as applied to PC6 elements is described. The described PC6 is used for experiments on generation of super-strong pulse magnetic fields in single-loop solenoid with volume occupied by magnetic field, 5-7 mm. Magnetic field with up to 350 T induction amplitude is obtained in these experiments

  8. Versatile Stimulation Back-End With Programmable Exponential Current Pulse Shapes for a Retinal Visual Prosthesis.

    Science.gov (United States)

    Maghami, Mohammad Hossein; Sodagar, Amir M; Sawan, Mohamad

    2016-11-01

    This paper reports on the design, implementation, and test of a stimulation back-end, for an implantable retinal prosthesis. In addition to traditional rectangular pulse shapes, the circuit features biphasic stimulation pulses with both rising and falling exponential shapes, whose time constants are digitally programmable. A class-B second generation current conveyor is used as a wide-swing, high-output-resistance stimulation current driver, delivering stimulation current pulses of up to ±96 μA to the target tissue. Duration of the generated current pulses is programmable within the range of 100 μs to 3 ms. Current-mode digital-to-analog converters (DACs) are used to program the amplitudes of the stimulation pulses. Fabricated using the IBM 130 nm process, the circuit consumes 1.5×1.5 mm 2 of silicon area. According to the measurements, the DACs exhibit DNL and INL of 0.23 LSB and 0.364 LSB, respectively. Experimental results indicate that the stimuli generator meets expected requirements when connected to electrode-tissue impedance of as high as 25 k Ω. Maximum power consumption of the proposed design is 3.4 mW when delivering biphasic rectangular pulses to the target load. A charge pump block is in charge of the upconversion of the standard 1.2-V supply voltage to ±3.3V.

  9. Effects of pulse current on energy consumption and removal of heavy metals during electrodialytic soil remediation

    DEFF Research Database (Denmark)

    Sun, Tian R.; Ottosen, Lisbeth M.

    2012-01-01

    industrially polluted soils were performed. At a current density of 0.1mA/cm2 in soil 1 and 0.2mA/cm2 in soil 2, there was no difference on energy consumption and removal of heavy metals between pulse current and constant current experiments, but at higher current experiments (i.e., 0.2mA/cm2 in soil 1 and 0......The aims of this paper were to investigate the possibility for energy saving when using a pulsed electric field during electrodialytic soil remediation (EDR) and the effect of the pulsed current on removal of heavy metals. Eight experiments with constant and pulse current in the different.......8mA/cm2 in soil 2) the energy was saved 67% and 60% and the removal of heavy metals was increased 17–76% and 31–51% by pulse current in soil 1 and soil 2, respectively. When comparing the voltage drop at different parts of EDR cells, it was found that the voltage drop of the area across cation...

  10. Surface modification of TA2 pure titanium by low energy high current pulsed electron beam treatments

    International Nuclear Information System (INIS)

    Gao Yukui

    2011-01-01

    Surface integrity changes of TA2 pure titanium including surface topography, microstructure and nanohardness distribution along surface layer were investigated by different techniques of low energy high current pulsed electron beam treatments (LEHCPEBTs). The surface topography was characterized by SEM. Moreover, the TEM observation and X-ray diffraction analysis were performed to reveal the surface modification mechanism of TA2 pure titanium by LEHCPEBTs. The surface roughness was modified by electron beam treatment and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM and TEM. The results show that the surface finish obtains good polishing quality and there is no phase transformation but the dislocations by LEHCPEBT. Furthermore, the nanohardness in the surface modified layer is improved. The remelt and fine-grain microstructure of surface layer caused by LEHCPEBTs are the main polishing mechanism and the reason of modification of surface topography and the increment in nanohardness is mainly due to the dislocations and fine grains in the modified layer induced by LEHCPEBT.

  11. Criterion of magnetic saturation and simulation of nonlinear magnetization for a linear multi-core pulse transformer

    International Nuclear Information System (INIS)

    Zeng Zhengzhong; Kuai Bin; Sun Fengju; Cong Peitian; Qiu Aici

    2002-01-01

    The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasm owing to its compact, relatively low-cost and easy-to-handle characteristics. The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design, because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation. This work proposes analytical formulas of the criterion of magnetic saturation for the cores when the transformer drives practical loads. Furthermore, an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores. The numerical simulation with the model is used to evaluate the validity of the criterion. Both the criterion and the model are found to be in agreement with the experimental data

  12. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, S.A.; Puzynin, I.V.; Samoilov, V.N.; Sissakian, A.N. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)

    1997-09-01

    The project of a high current pulsed linear ion accelerator is described in this paper. The accelerator consists of an ion injector, a system of charge and energy separation, an inductor accelerator and an output system. The ion source with explosive ion emission can produce all kinds of ions. The separation system includes a pulsed magnetic system. The inductors are based on amorphous iron with inside magnetic elements. 3 refs., 3 figs.

  13. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    International Nuclear Information System (INIS)

    Korenev, S.A.; Puzynin, I.V.; Samoilov, V.N.; Sissakian, A.N.

    1997-01-01

    The project of a high current pulsed linear ion accelerator is described in this paper. The accelerator consists of an ion injector, a system of charge and energy separation, an inductor accelerator and an output system. The ion source with explosive ion emission can produce all kinds of ions. The separation system includes a pulsed magnetic system. The inductors are based on amorphous iron with inside magnetic elements. 3 refs., 3 figs

  14. Understanding the molecular mechanism of pulse current charging for stable lithium-metal batteries

    Science.gov (United States)

    Li, Qi; Tan, Shen; Li, Linlin; Lu, Yingying; He, Yi

    2017-01-01

    High energy and safe electrochemical storage are critical components in multiple emerging fields of technologies. Rechargeable lithium-metal batteries are considered to be promising alternatives for current lithium-ion batteries, leading to as much as a 10-fold improvement in anode storage capacity (from 372 to 3860 mAh g−1). One of the major challenges for commercializing lithium-metal batteries is the reliability and safety issue, which is often associated with uneven lithium electrodeposition (lithium dendrites) during the charging stage of the battery cycling process. We report that stable lithium-metal batteries can be achieved by simply charging cells with square-wave pulse current. We investigated the effects of charging period and frequency as well as the mechanisms that govern this process at the molecular level. Molecular simulations were performed to study the diffusion and the solvation structure of lithium cations (Li+) in bulk electrolyte. The model predicts that loose association between cations and anions can enhance the transport of Li+ and eventually stabilize the lithium electrodeposition. We also performed galvanostatic measurements to evaluate the cycling behavior and cell lifetime under pulsed electric field and found that the cell lifetime can be more than doubled using certain pulse current waveforms. Both experimental and simulation results demonstrate that the effectiveness of pulse current charging on dendrite suppression can be optimized by choosing proper time- and frequency-dependent pulses. This work provides a molecular basis for understanding the mechanisms of pulse current charging to mitigating lithium dendrites and designing pulse current waveforms for stable lithium-metal batteries. PMID:28776039

  15. Follicular lymphomas and their transformation: Past and current research.

    Science.gov (United States)

    Mendez, Miriam; Torrente, Maria; Provencio, Mariano

    2017-06-01

    Follicular lymphoma (FL) is the second most common type of non-Hodgkin lymphoma (NHL). Histological transformation (HT) refers to the evolution of a clinically indolent NHL to a clinically aggressive one, defined as those lymphomas in which survival is limited to a few months when untreated. Areas covered: HT is associated with rapid progression of lymphadenopathy, infiltration of extranodal sites, development of systemic symptoms, and elevated serum level of lactate dehydrogenase (LDH). It is frequently related to a poor prognosis, and the median survival after transformation is less than 2 years. Transformation to diffuse large B cell lymphoma (DLBCL) in patients with FL occurs at an annual rate of approximately 3% for the first 15 years, after which the risk of HT falls for reasons that remain unclear. Expert commentary: Although it has long been assumed that transformation reflects the emergence of an aggressive subclone of cells from the primary FL, recent studies suggest that FL transformation might also arise by divergent evolution from a more immature common progenitor cell. Studies on genomic changes and DNA sequencing have shed some light onto the process of transformation. Nowadays, we know that HT is a complex process where several molecular pathways are involved.

  16. Non-Cyanide Electrodeposited Ag–PTFE Composite Coating Using Direct or Pulsed Current Deposition

    Directory of Open Access Journals (Sweden)

    Raymond Sieh

    2016-07-01

    Full Text Available The effects of FC-4 cationic surfactant on electrodeposited Ag–PTFE composite coating using direct or pulsed currents were studied using scanning electron microscope (SEM, energy dispersive X-ray (EDS, optical microscope, and a linear tribometer. FC-4:PTFE in various ratios were added to a non-cyanide succinimide silver complex bath. Direct or pulsed current method was used at a constant current density to enable comparison between both methods. A high incorporation rate of PTFE was successfully achieved, with pulsed current being highly useful in increasing the amount of PTFE in the composite coating. The study of coating wear under sliding showed that a large majority of the electrodeposited coatings still managed to adhere to the substrate, even after 10 wear cycles of sliding tests. Performance improvements were achieved on all the samples with a coefficient of friction (CoF between 0.06 and 0.12.

  17. Effects of spin-polarized current on pulse field-induced precessional magnetization reversal

    Directory of Open Access Journals (Sweden)

    Guang-fu Zhang

    2012-12-01

    Full Text Available We investigate effects of a small DC spin-polarized current on the pulse field-induced precessional magnetization reversal in a thin elliptic magnetic element by micromagnetic simulations. We find that the spin-polarized current not only broadens the time window of the pulse duration, in which a successful precessional reversal is achievable, but also significantly suppresses the magnetization ringing after the reversal. The pulse time window as well as the decay rate of the ringing increase with increasing the current density. When a spin-polarized current with 5 MA/cm2 is applied, the time window increases from 80 ps to 112 ps, and the relaxation time of the ringing decreases from 1.1 ns to 0.32 ns. Our results provide useful information to achieve magnetic nanodevices based on precessional switching.

  18. Effects of pulse current stimulation on the thermal fatigue crack propagation behavior of CHWD steel

    International Nuclear Information System (INIS)

    Lin, H.Q.; Zhao, Y.G.; Gao, Z.M.; Han, L.G.

    2008-01-01

    The fatigue crack propagating behaviors of cast hot working die (CHWD) steel untreated and treated by an electric current in the intermediate stage of thermal fatigue were investigated in the present study. The circle/elliptical heating affected zone (HAZ) was formed ahead of the notch tip on the fatigued specimens after pulse electric current stimulation. Both SEM observation and X-ray diffraction analysis revealed that pulse electric current stimulation refined grains/subgrains in the HAZs. With the prolonging of discharging duration, the grains/subgrains decreased in size and the dislocation density and microhardness increased gradually. The grain refinement and dislocation density increase played an important role in the material strengthening, which inevitably enhanced the propagation resistance and delayed the propagation of thermal fatigue cracks. Therefore, the pulse electric current stimulation was an effective method to improve the service lifetime of die material

  19. Pulse shape discrimination with silicon detectors using charge and current-sensitive preamplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Hamrita, H.; Rauly, E.; Blumenfeld, Y.; Borderie, B.; Chabot, M.; Edelbruck, P.; Lavergne, L.; Le Bris, J.; Le Neindre, N.; Richard, A.; Rivet, M.F.; Scarpaci, J.A.; Barbey, S.; Becheva, E.; Bzyl, F.R.; D' Esesquelles, P.; Galichet, E.; Lalu, G.; Martinet, G.; Pierre, S. [Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Legou, Th.; Tillier, J.; Bocage, F.; Bougault, R.; Carniol, B.; Cussol, D.; Etasse, D.; Grevy, S.; Lopez, O.; Tamain, B.; Vient, E. [Caen Univ., LPC, IN2P3-CNRS, ENSI, 14 - Caen (France); Galichet, E. [Conservatoire National des Arts et Metier, 75 - Paris (France); Guinet, D.; Lautesse, Ph. [Villeurbanne Univ., Institut de Physique Nucleaire, IN2P3-CNRS, 69 (France); Lanzalone, G. [Catania Univ., INFN, Laboratori Nazionali del Sud and Dipartimento di Fisica e Astronomia, (Italy); Politi, G. [Catania Univ., INFN, Sezione di Catania and Dipartimento di Fisica e Astronomia (Italy); Rosato, E. [Napoli, Univ., Dipt. di Scienze Fisiche e Sezione INFN (Italy)

    2003-07-01

    For the first time shapes of current pulses from light charged particles and carbon ions are presented. Capabilities for pulse shape discrimination techniques are demonstrated. In this work, charge and current-sensitive preamplifier prototypes for nuclear structure and dynamics experiments have been developed and tested with the aim of improving PSD (pulse shape discrimination) method by studying in detail current signal shapes from particles and ions over a large energy range. Note that current signal shapes have been recently used in atomic cluster studies to identify partitions of carbon cluster fragmentation. The paper is organized as follows. Section 2 is devoted to characterization of preamplifiers. In section 3, results of on beam tests will be presented, discussed and compared to a simple simulation.

  20. Investigation of protection problems due to geomagnetically induced currents (solar magnetic disturbances, transformers)

    International Nuclear Information System (INIS)

    1997-01-01

    The problems with geomagnetically induced currents (GIC) flowing in power systems during solar magnetic disturbances were studied. Transformers can overheat as a result of GIC because they can cause offset saturation of power system transformers. Harmonic currents can also be introduced into the system which then affect the relay and protection systems. Several studies have been conducted using simplified transformer core models to predict the transformer response to DC excitation. In this study, an accurate transformer core model was developed and validated by comparing the recorded waveforms during GIC events with simulated waveforms using the model. The new transformer core model was used to evaluate the performance of different protection schemes under GIC

  1. Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-03-15

    Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

  2. Transient voltage response of a superconducting strip to a supercritical current pulse

    International Nuclear Information System (INIS)

    Attekum, P.M.Th.M. van; Wouters, M.C.H.M.; Wolter, J.; Horstman, R.E.

    1981-01-01

    A superconductor subject to a supercritical current pulse displays a delay time between the onset of the current pulse and the onset of the corresponding voltage response. From the onset of the voltage response it takes a second (transient) time to reach the stationary state. It is shown that the transient time can be explained with inhomogeneities in the strip which give rise to a distribution of delay times. The transient time is thus not related to a characteristic time in the superconductor. For small supercritical currents also heating effects show up. (author)

  3. Sodium current inhibition by nanosecond pulsed electric field (nsPEF)--fact or artifact?

    NARCIS (Netherlands)

    Verkerk, Arie O.; van Ginneken, Antoni C. G.; Wilders, Ronald

    2013-01-01

    In two recent publications in Bioelectromagnetics it has been demonstrated that the voltage-gated sodium current (I(Na)) is inhibited in response to a nanosecond pulsed electric field (nsPEF). At the same time, there was an increase in a non-inactivating "leak" current (I(leak)), which was

  4. Characterization of a high-power/current pulsed magnetized arc discharge

    NARCIS (Netherlands)

    Zielinski, J. J.; van der Meiden, H. J.; Morgan, T. W.; D.C. Schram,; De Temmerman, G.

    2012-01-01

    A high-power pulsed magnetized arc discharge has been developed to allow the superimposition of a dc plasma and a high-power plasma impulse with a single plasma source. A capacitor bank (8400 mu F) is parallel-coupled to the current regulated power supply. The current is transiently increased from

  5. Characterization of a high-power/current pulsed magnetized arc discharge

    NARCIS (Netherlands)

    Zielinski, J.J.; Meiden, van der H.J.; Morgan, T.W.; Schram, D.C.; De Temmerman, G.C.

    2012-01-01

    A high-power pulsed magnetized arc discharge has been developed to allow the superimposition of a dc plasma and a high-power plasma impulse with a single plasma source. A capacitor bank (8400 µF) is parallel-coupled to the current regulated power supply. The current is transiently increased from its

  6. Quality assurance testing of acoustic doppler current profiler transform matrices

    Science.gov (United States)

    Armstrong, Brandy; Fulford, Janice M.; Thibodeaux, Kirk G.

    2015-01-01

    The U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility (HIF) is nationally responsible for the design, testing, evaluation, repair, calibration, warehousing, and distribution of hydrologic instrumentation in use within the USGS Water Mission Area (WMA). The HIF's Hydraulic Laboratory has begun routine quality assurance (QA) testing and documenting the performance of every USGS WMA acoustic Doppler current profiler (ADCP) used for making velocity and discharge measurements. All existing ADCPs are being registered and tracked in a database maintained by the HIF, and called for QA checks in the HIF's Hydraulic Laboratory on a 3- year cycle. All new ADCPs purchased directly from the manufacturer as well as ADCPs sent to the HIF or the manufacturer for repair are being registered and tracked in the database and QA checked in the laboratory before being placed into service. Meters failing the QA check are sent directly to the manufacturer for repairs and rechecked by HIF or removed from service. Although this QA program is specific to the SonTek1 and Teledyne RD Instruments1, ADCPs most commonly used within the WMA, it is the intent of the USGS Office of Surface Water and the HIF to expand this program to include all bottom tracking ADCPs as they become available and more widely used throughout the WMA. As part of the HIF QA process, instruments are inspected for physical damage, the instrument must pass the ADCP diagnostic self-check tests, the temperature probe must be within ± 2 degrees Celsius of a National Institute of Standards and Technology traceable reference thermometer and the distance made good over a fixed distance must meet the manufacturer's specifications (+/-0.25% or +/-1% difference). The transform matrix is tested by conducting distance-made-good (DMG) tests comparing the straight-line distance from bottom tracking to the measured tow-track distance. The DMG test is conducted on each instrument twice in the forward and reverse

  7. Effect of a superconducting coil as a fault current limiter on current density distribution in BSCCO tape after an over-current pulse

    International Nuclear Information System (INIS)

    Tallouli, M; Yamaguchi, S.; Shyshkin, O.

    2017-01-01

    The development of power transmission lines based on long-length high temperature superconducting (HTS) tapes is complicated and technically challenging task. A serious problem for transmission line operation could become HTS power cable damage due to over-current pulse conditions. To avoid the cable damage in any urgent case the superconducting coil technology, i.e. superconductor fault current limiter (SFCL) is required. Comprehensive understanding of the current density characteristics of HTS tapes in both cases, either after pure over-current pulse or after over-current pulse limited by SFCL, is needed to restart or to continue the operation of the power transmission line. Moreover, current density distribution along and across the HTS tape provides us with the sufficient information about the quality of the tape performance in different current feeding regimes. In present paper we examine BSCCO HTS tape under two current feeding regimes. The first one is 100A feeding preceded by 900A over-current pulse. In this case none of tape protection was used. The second scenario is similar to the fist one but SFCL is used to limit an over-current value. For both scenarios after the pulse is gone and the current feeding is set up at 100A we scan magnetic field above the tape by means of Hall probe sensor. Then the feeding is turned of and the magnetic field scanning is repeated. Using the inverse problem numerical solver we calculate the corresponding direct and permanent current density distributions during the feeding and after switch off. It is demonstrated that in the absence of SFCL the current distribution is highly peaked at the tape center. At the same time the current distribution in the experiment with SFCL is similar to that observed under normal current feeding condition. The current peaking in the first case is explained by the effect of an opposite electric field induced at the tape edges during the overcurrent pulse decay, and by degradation of

  8. Nanosecond electric pulses differentially affect inward and outward currents in patch clamped adrenal chromaffin cells.

    Directory of Open Access Journals (Sweden)

    Lisha Yang

    Full Text Available This study examined the effect of 5 ns electric pulses on macroscopic ionic currents in whole-cell voltage-clamped adrenal chromaffin cells. Current-voltage (I-V relationships first established that the early peak inward current was primarily composed of a fast voltage-dependent Na+ current (INa, whereas the late outward current was composed of at least three ionic currents: a voltage-gated Ca2+ current (ICa, a Ca2+-activated K+ current (IK(Ca, and a sustained voltage-dependent delayed rectifier K+ current (IKV. A constant-voltage step protocol was next used to monitor peak inward and late outward currents before and after cell exposure to a 5 ns pulse. A single pulse applied at an electric (E-field amplitude of 5 MV/m resulted in an instantaneous decrease of ~4% in peak INa that then declined exponentially to a level that was ~85% of the initial level after 10 min. Increasing the E-field amplitude to 8 or 10 MV/m caused a twofold greater inhibitory effect on peak INa. The decrease in INa was not due to a change in either the steady-state inactivation or activation of the Na+ channel but instead was associated with a decrease in maximal Na+ conductance. Late outward current was not affected by a pulse applied at 5 MV/m. However, for a pulse applied at the higher E-field amplitudes of 8 and 10 MV/m, late outward current in some cells underwent a progressive ~22% decline over the course of the first 20 s following pulse exposure, with no further decline. The effect was most likely concentrated on ICa and IK(Ca as IKV was not affected. The results of this study indicate that in whole-cell patch clamped adrenal chromaffin cells, a 5 ns pulse differentially inhibits specific voltage-gated ionic currents in a manner that can be manipulated by tuning E-field amplitude.

  9. Pulse Propagation Effects in Optical 2D Fourier-Transform Spectroscopy: Theory.

    Science.gov (United States)

    Spencer, Austin P; Li, Hebin; Cundiff, Steven T; Jonas, David M

    2015-04-30

    A solution to Maxwell's equations in the three-dimensional frequency domain is used to calculate rephasing two-dimensional Fourier transform (2DFT) spectra of the D2 line of atomic rubidium vapor in argon buffer gas. Experimental distortions from the spatial propagation of pulses through the sample are simulated in 2DFT spectra calculated for the homogeneous Bloch line shape model. Spectral features that appear at optical densities of up to 3 are investigated. As optical density increases, absorptive and dispersive distortions start with peak shape broadening, progress to peak splitting, and ultimately result in a previously unexplored coherent transient twisting of the split peaks. In contrast to the low optical density limit, where the 2D peak shape for the Bloch model depends only on the total dephasing time, these distortions of the 2D peak shape at finite optical density vary with the waiting time and the excited state lifetime through coherent transient effects. Experiment-specific conditions are explored, demonstrating the effects of varying beam overlap within the sample and of pseudo-time domain filtering. For beam overlap starting at the sample entrance, decreasing the length of beam overlap reduces the line width along the ωτ axis but also reduces signal intensity. A pseudo-time domain filter, where signal prior to the center of the last excitation pulse is excluded from the FID-referenced 2D signal, reduces propagation distortions along the ωt axis. It is demonstrated that 2DFT rephasing spectra cannot take advantage of an excitation-detection transformation that can eliminate propagation distortions in 2DFT relaxation spectra. Finally, the high optical density experimental 2DFT spectrum of rubidium vapor in argon buffer gas [J. Phys. Chem. A 2013, 117, 6279-6287] is quantitatively compared, in line width, in depth of peak splitting, and in coherent transient peak twisting, to a simulation with optical density higher than that reported.

  10. Investigation of switch designs for the dynamic load current multiplier scheme on the SPHYNX microsecond linear transformer driver

    International Nuclear Information System (INIS)

    Maysonnave, T.; Bayol, F.; Demol, G.; Almeida, T. d'; Lassalle, F.; Morell, A.; Grunenwald, J.; Chuvatin, A.S.; Pecastaing, L.; De Ferron, A.S.

    2014-01-01

    SPHINX is a microsecond linear transformer driver LTD, used essentially for implosion of Z-pinch loads in direct drive mode. It can deliver a 6-MA current pulse within 800 ns into a Z-pinch load. The dynamic load current multiplier concept enables the current pulse to be modified by increasing its amplitude while reducing its rise time before being delivered to the load. This compact system is made up of concentric electrodes (auto transformer), a dynamic flux extruder (cylindrical wire array), a vacuum convolute (eight post-holes), and a vacuum closing switch, which is the key component of the system. Several different schemes are investigated for designing a vacuum switch suitable for operating the dynamic load current multiplier on the SPHINX generator for various applications, including isentropic compression experiments and Z-pinch radiation effects studies. In particular, the design of a compact vacuum surface switch and a multichannel vacuum switch, located upstream of the load are studied. Electrostatic simulations supporting the switch designs are presented along with test bed experiments. Initial results from shots on the SPHINX driver are also presented. (authors)

  11. Primary power supply of repetitive pulsed intense current accelerator charged by capacitance of energy store

    International Nuclear Information System (INIS)

    Chen Jun; Yang Jianhua; Shu Ting; Zhang Jiande; Zhou Xiang; Wen Jianchun

    2008-01-01

    The primary power supply of repetitive pulsed intense current accelerator charged by capacitance of energy store is studied. The principle of primary power supply circuit and its time diagram of switches are presented. The circuit is analyzed and some expressions are got, especially, the usable voltage scope of capacitance of energy store, and the correlation between the parameters of circuit and time delay, which is between the turn-on of the charging circuit of capacitance of energy store and the circuit of recuperation. The time delay of 256 x 256 lookup table is made with the instruction of theory and the simulation of the actual parameters of circuits. The table is used by the control program to control the repetitive operating of the actual pulsed intense current accelerator. Finally, some conclusions of the primary power supply of repetitive pulsed intense current accelerator charged by capacitance of energy store are got. (authors)

  12. Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary.

    Science.gov (United States)

    Shukla, Rohit; Banerjee, Partha; Sharma, Surender K; Das, Rashmita; Deb, Pankaj; Prabaharan, T; Das, Basanta; Adhikary, Biswajit; Verma, Rishi; Shyam, Anurag

    2011-10-01

    The experimental results of an air-core pulse transformer are presented, which is very compact (capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.

  13. Modelling the transient behaviour of pulsed current tungsten-inert-gas weldpools

    Science.gov (United States)

    Wu, C. S.; Zheng, W.; Wu, L.

    1999-01-01

    A three-dimensional model is established to simulate the pulsed current tungsten-inert-gas (TIG) welding process. The goal is to analyse the cyclic variation of fluid flow and heat transfer in weldpools under periodic arc heat input. To this end, an algorithm, which is capable of handling the transience, nonlinearity, multiphase and strong coupling encountered in this work, is developed. The numerical simulations demonstrate the transient behaviour of weldpools under pulsed current. Experimental data are compared with numerical results to show the effectiveness of the developed model.

  14. Light electric transformer to transform the size of particles contained in a gas flow into electrical pulses

    Energy Technology Data Exchange (ETDEWEB)

    Berber, V.A.; Zolotenko, V.A.; Naguev, E.N.; Pavlov, V.V.; Sokolov, V.E.; Syromyatnikov, A.N.; Eremenko, A.I.

    1979-08-09

    The equipment measures the air dust. The aerosol flow is hence irradiated with a convergent light bundle. Using mirrors and mechanically operable screens, it is possible to divert part of the light onto a photo receiver to produce electric pulses of the dispersly composed aerosols and another part onto a former for standardized light pulses. The accuracy of the measurement is increased by the stability of the standardized light pulses.

  15. Transformation of irregular shaped silver nanostructures into nanoparticles by under water pulsed laser melting

    Science.gov (United States)

    Yadavali, S.; Sandireddy, V. P.; Kalyanaraman, R.

    2016-05-01

    The ability to easily manufacture nanostructures with a desirable attribute, such as well-defined size and shape, especially from any given initial shapes or sizes of the material, will be helpful towards accelerating the use of nanomaterials in various applications. In this work we report the transformation of discontinuous irregular nanostructures (DIN) of silver metal by rapid heating under a bulk fluid layer. Ag films were changed into DIN by dewetting in air and subsequently heated by nanosecond laser pulses under water. Our findings show that the DIN first ripens into elongated structures and then breaks up into nanoparticles. From the dependence of this behavior on laser fluence we found that under water irradiation reduced the rate of ripening and also decreased the characteristic break-up length scale of the elongated structures. This latter result was qualitatively interpreted as arising from a Rayleigh-Plateau instability modified to yield significantly smaller length scales than the classical process due to pressure gradients arising from the rapid evaporation of water during laser melting. These results demonstrate that it is possible to fabricate a dense collection of monomodally sized Ag nanoparticles with significantly enhanced plasmonic quality starting from the irregular shaped materials. This can be beneficial towards transforming discontinuous Ag films into nanostructures with useful plasmonic properties, that are relevant for biosensing applications.

  16. ECOLOGICAL TRANSFORMATIONS OF RIVERINE HYDROECOSYSTEMS AND CURRENT PROBLEMS OF FISHERIES

    Directory of Open Access Journals (Sweden)

    I. Sherman

    2013-12-01

    Full Text Available Purpose. To analyze permanent negative effect from transformation of riverine hydroecosystems on fish fauna of Azov-Black Sea Basin. Methodology. Materials on the abiotic parameters of hydro river, according to information received by the regional meteorological stations and their own observations. Industrial situation analyzed by official reports Statefishagency of Ukraine. Findings. The studies demonstrate that there is a gradual process of an increase of the number of components, which virtually exclude the significance of positive results of self-purification by natural way, in water mass of transformed riverine systems. Spontaneous fluctuation of water level, which is caused by volumes of daily discharges, often instantly changes water levels on spawning areas. Fertilized fish eggs is periodically flooded or periodically dried, aeration regime changes that results in mass fish kills at different stages and phases of embryogenesis. Ecological situation of transformed hydroecosystems demonstrates coupling of negative effect of hydrological regime autostaticity in time and space, deterioration of water chemical composition. There is a permanent trend of saturation of water with components, which are not natural that results in doubtfulness of effective reproduction puts in question the possibility of stable state of valuable commercial fish stocks. At the same time, transformed water areas of riverine hydroecosystems have high bioproductive potential, which having its own food resource, is ineffectively transformed into food base for valuable commercial fish species. Against the background of noted changes, the considered water areas lost their suitability of providing effective reproduction. As a consequence, primary valuable fish species form low-yield generations and this is reflected on qualitative indices of commercial fishing. There was found a permanent trend of sufficiently fast change of the ratio of valuable and low-valuable species

  17. TRANSFORMER

    Science.gov (United States)

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  18. Leakage current analysis of a single-phase transformer-less PV inverter connected to the grid

    DEFF Research Database (Denmark)

    Ma, Lin; Tang, F.; Zhou, F.

    2009-01-01

    Due to the large surface of the PV generator, its stray capacity with respect to the ground reaches values that can be quite high. When no transformer is used in a grid-connected PV system, common-mode current, which caused by the common mode voltage, can flow through the stray capacitance between...... the PV array and the ground. It is quite harmful to the body safety and PV system. In order to avoid leakage current, different inverter topologies that generate no varying common-mode voltages, such as bipolar pulse-width modulation (PWM) full-bridge topology, NPC topology have been proposed. From...... the safety and energy saving viewpoint, it is necessary to develop a higher efficiency topology. In this paper, the generation mechanism of common mode current is discussed. Then different methods used to eliminate the leakage current are compared. Finally, the full-bridge which generates no varying common...

  19. Surface modification of steels and magnesium alloy by high current pulsed electron beam

    Science.gov (United States)

    Hao, Shengzhi; Gao, Bo; Wu, Aimin; Zou, Jianxin; Qin, Ying; Dong, Chuang; An, Jian; Guan, Qingfeng

    2005-11-01

    High current pulsed electron beam (HCPEB) is now developing as a useful tool for surface modification of materials. When concentrated electron flux transferring its energy into a very thin surface layer within a short pulse time, superfast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved physico-chemical and mechanical properties. This paper presents our research work on surface modification of steels and magnesium alloy with HCPEB of working parameters as electron energy 27 keV, pulse duration ∼1 μs and energy density ∼2.2 J/cm2 per pulse. Investigations performed on carbon steel T8, mold steel D2 and magnesium alloy AZ91HP have shown that the most pronounced changes of phase-structure state and properties occurring in the near-surface layers, while the thickness of the modified layer with improved microhardness (several hundreds of micrometers) is significantly greater than that of the heat-affected zone. The formation mechanisms of surface cratering and non-stationary hardening effect in depth are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stresses formed during pulsed electron beam melting treatment. After the pulsed electron beam treatments, samples show significant improvements in measurements of wear and corrosion resistance.

  20. Surface modification of steels and magnesium alloy by high current pulsed electron beam

    International Nuclear Information System (INIS)

    Hao, Shengzhi; Gao, Bo; Wu, Aimin; Zou, Jianxin; Qin, Ying; Dong, Chuang; An, Jian; Guan, Qingfeng

    2005-01-01

    High current pulsed electron beam (HCPEB) is now developing as a useful tool for surface modification of materials. When concentrated electron flux transferring its energy into a very thin surface layer within a short pulse time, superfast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved physico-chemical and mechanical properties. This paper presents our research work on surface modification of steels and magnesium alloy with HCPEB of working parameters as electron energy 27 keV, pulse duration ∼1 μs and energy density ∼2.2 J/cm 2 per pulse. Investigations performed on carbon steel T8, mold steel D2 and magnesium alloy AZ91HP have shown that the most pronounced changes of phase-structure state and properties occurring in the near-surface layers, while the thickness of the modified layer with improved microhardness (several hundreds of micrometers) is significantly greater than that of the heat-affected zone. The formation mechanisms of surface cratering and non-stationary hardening effect in depth are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stresses formed during pulsed electron beam melting treatment. After the pulsed electron beam treatments, samples show significant improvements in measurements of wear and corrosion resistance

  1. Is there an Optimal Shape of the Defibrillation Shock: Constant Current vs. Pulsed Biphasic Waveforms

    Directory of Open Access Journals (Sweden)

    Ivan Dotsinsky

    2013-04-01

    Full Text Available Three waveforms for transthoracic defibrillation are assessed and compared: the Pulsed Biphasic Waveform (PBW, the Rectilinear Biphasic Waveform (RBW, and the "lossless" constant current (LLCC pulses. Two indices are introduced: 1 kf = W/W0 - the ratio between the delivered energy W and the energy W0 of a rectangular pulse with the same duration and electric charge; 2 ηC = W/WC0 - the level of utilizing the initially loaded capacitor energy WC0. The envisioned comparative study shows that ηC index is favorable for both PBW and LLCC, while kf of both RBW and LLCC demonstrates advantage over the PBW in the range of small inter-electrode thoracic impedances below 80 Ω. Some design considerations are also discussed. The attractive LLCC concept needs large and heavy inductive coil to support the constant current amplitude, besides it is capable to induce strong electromagnetic influences due to the complex current control. The RBW technology controls the delivery of current through a series of internal resistors which are, however, a source of high heat losses. The PBW implements controlled duty cycle of high-frequency chopped pulses to adapt the energy delivery in respect of the patient impedance measured at the beginning of the shock. PBW technology makes use of small capacitors which allows the construction of light weight and small-size portable devices for transthoracic defibrillation.

  2. 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.)

  3. Dynamic behavior of HTSC opening switch models controlled by short over-critical current pulses

    International Nuclear Information System (INIS)

    Agafonov, A.V.; Krastelev, E.G.; Voronin, V.S.

    1999-01-01

    We present results of experimental research of dynamical properties of thin films of YBa 2 Cu 3 O 7 HTSC-switch models under action of short overcritical current pulses to test this method of control of fast high-power opening switches for accelerator applications

  4. Current multiplier to improved generator-to-load coupling for pulse-power generators

    International Nuclear Information System (INIS)

    Chuvatin, A.S.; Rudakov, L.I.; Weber, B.V.; Bayol, F.; Cadiergues, R.

    2005-01-01

    The circuit presented improves the coupling of existing and future pulsed power generators to physical loads. The efficiency of the proposed current multiplication scheme could theoretically exceed the values for a typical direct load-to-generator circuit. The scheme could be beneficial for use in actual applications and two examples of such applications are given [ru

  5. The high current, fast, 100ns, Linear Transformer Driver (LTD) developmental project at Sandia Laboratories and HCEI

    International Nuclear Information System (INIS)

    Ward, Kevin S.; Long, Finis W.; Sinebryukhov, Vadim A.; Kim, Alexandre A.; Wakeland, Peter Eric; McKee, G. Randall; Woodworth, Joseph Ray; McDaniel, Dillon Heirman; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John Larry Jr.; Struve, Kenneth William; Savage, Mark Edward; Stygar, William A.; LeChien, Keith R.; Matzen, Maurice Keith

    2010-01-01

    Sandia National Laboratories, Albuquerque, N.M., USA, in collaboration with the High Current Electronic Institute (HCEI), Tomsk, Russia, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This technological approach can provide very compact devices that can deliver very fast high current and high voltage pulses straight out of the cavity with out any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. This is because the output pulse rise time and width can be easily tailored to the specific application needs. In this paper we briefly summarize the developmental work done in Sandia and HCEI during the last few years, and describe our new MYKONOS Sandia High Current LTD Laboratory. An extensive evaluation of the LTD technology is being performed at SNL and the High Current Electronic Institute (HCEI) in Tomsk Russia. Two types of High Current LTD cavities (LTD I-II, and 1-MA LTD) were constructed and tested individually and in a voltage adder configuration (1-MA cavity only). All cavities performed remarkably well and the experimental results are in full agreement with analytical and numerical calculation predictions. A two-cavity voltage adder is been assembled and currently undergoes evaluation. This is the first step towards the completion of the 10-cavity, 1-TW module. This MYKONOS voltage adder will be the first ever IVA built with a transmission line insulated with deionized water. The LTD II cavity renamed LTD III will serve as a test bed for evaluating a number of different types of switches, resistors, alternative capacitor configurations, cores

  6. Influence of pulse electric current on structure and superconducting properties of high temperature superconductor

    International Nuclear Information System (INIS)

    Rajchenko, A.I.; Flis, A.A.; Chernenko, L.I.; Kryuchkova, N.I.

    1998-01-01

    The influence of high-density pulse current treatment at room temperature on structure and superconducting properties of HTSC Y Ba 2 Cu 3 O x ceramics is studied. The structures of the samples are found to undergo appreciable changes as the density of pulse current is gradually increased from its minimum value; as a certain threshold value is attained, there occurs a melting-off of coarse grains with a partial destroying of intergrain contact areas followed by superconductivity loss. A further increase in the treatment current density results in a restoration of the superconducting properties probably due to the occurrence of aligned-with-current superconducting bridges between the melted-off grains. The superconducting transition temperature in the samples does not charge but subsequent thermal treatment causes this temperature to increase

  7. High-current relativistic klystron amplifier development for microsecond pulse lengths

    International Nuclear Information System (INIS)

    Fazio, M.V.; Carlsten, B.E.; Faehl, R.; Kwan, T.J.; Rickel, D.G.; Stringfield, R.M.; Tallerico, P.J.

    1991-01-01

    Los Alamos is extending the performance of the Friedman-type, high-current relativistic klystron amplifier (RKA) to the microsecond regime while attempting to achieve the gigawatt-level peak power capability that has been characteristic of the RKA at shorter pulse lengths. Currently the electron beam power into the device is about 1 GW in microsecond duration pulses, with an effort underway to increase the beam power to 2.5 GW. To data the device has yielded an rf modulated electron beam power of 350 MW, with up to 50 MW coupled into waveguide. Several aspects of RKA operation under investigation that affect RKA beam bunching efficiency and amplifier gain include cavity tuning, beam diameter, beam current, and input rf drive power, and the development of an output coupler that efficiently couples the microwave power from the low impedance beam into rectangular waveguide operating in the dominant mode. Current results from experimental testing and code modeling are presented

  8. Genetic transformation of fruit trees: current status and remaining challenges.

    Science.gov (United States)

    Gambino, Giorgio; Gribaudo, Ivana

    2012-12-01

    Genetic transformation has emerged as a powerful tool for genetic improvement of fruit trees hindered by their reproductive biology and their high levels of heterozygosity. For years, genetic engineering of fruit trees has focussed principally on enhancing disease resistance (against viruses, fungi, and bacteria), although there are few examples of field cultivation and commercial application of these transgenic plants. In addition, over the years much work has been performed to enhance abiotic stress tolerance, to induce modifications of plant growth and habit, to produce marker-free transgenic plants and to improve fruit quality by modification of genes that are crucially important in the production of specific plant components. Recently, with the release of several genome sequences, studies of functional genomics are becoming increasingly important: by modification (overexpression or silencing) of genes involved in the production of specific plant components is possible to uncover regulatory mechanisms associated with the biosynthesis and catabolism of metabolites in plants. This review focuses on the main advances, in recent years, in genetic transformation of the most important species of fruit trees, devoting particular attention to functional genomics approaches and possible future challenges of genetic engineering for these species in the post-genomic era.

  9. Development of a positive column pulsed capillary discharge source for use with high resolution Fourier transform spectrometer

    International Nuclear Information System (INIS)

    Syed, W A A

    2002-01-01

    We report the designing and application of a positive column pulsed capillary discharge with the Fourier transform spectrometer (FTS). The pulsed light source has been used for the first time with the ultraviolet FTS. The experiment has been carried out with the high energy pulsed discharge with energy of 2-3 J lasting about 300 ns. A system has been developed to trigger the discharge at about 600 Hz with the pulses directly taken from the FTS sampling system. The spectrum of Ar III has been recorded in the 19 000-50 000 cm -1 region with good signal to noise ratio. The results have opened a wide range of applications in spectroscopy of multiply ionized species

  10. Stellarator fields with small PS current at small rotational transform

    International Nuclear Information System (INIS)

    Herrnegger, F.

    2001-01-01

    One aspect of the optimization concept of stellarators is the reduction of the normalized Pfirsch-Schlueter current density p arallel 2 / j p erpendikular 2 > 1/2 to a reasonable level but obeying other side conditions, e.g., concerning small bootstrap currents, good stability properties, reasonable aspect ratio, etc. This problem is addressed in the present work. Various stellarator vacuum field are given analytically for M 2, 3, 5, 10, 12 (M is the number of field period around the torus) where the PS-current density is reduced by more than a factor of ten to rather small values around 0.3 even at small i-values

  11. Design of time-pulse coded optoelectronic neuronal elements for nonlinear transformation and integration

    Science.gov (United States)

    Krasilenko, Vladimir G.; Nikolsky, Alexander I.; Lazarev, Alexander A.; Lazareva, Maria V.

    2008-03-01

    In the paper the actuality of neurophysiologically motivated neuron arrays with flexibly programmable functions and operations with possibility to select required accuracy and type of nonlinear transformation and learning are shown. We consider neurons design and simulation results of multichannel spatio-time algebraic accumulation - integration of optical signals. Advantages for nonlinear transformation and summation - integration are shown. The offered circuits are simple and can have intellectual properties such as learning and adaptation. The integrator-neuron is based on CMOS current mirrors and comparators. The performance: consumable power - 100...500 μW, signal period- 0.1...1ms, input optical signals power - 0.2...20 μW time delays - less 1μs, the number of optical signals - 2...10, integration time - 10...100 of signal periods, accuracy or integration error - about 1%. Various modifications of the neuron-integrators with improved performance and for different applications are considered in the paper.

  12. Determination of diffusion coefficients in polypyrrole thin films using a current pulse relaxation method

    Science.gov (United States)

    Penner, Reginald M.; Vandyke, Leon S.; Martin, Charles R.

    1987-01-01

    The current pulse E sub oc relaxation method and its application to the determination of diffusion coefficients in electrochemically synthesized polypyrrole thin films is described. Diffusion coefficients for such films in Et4NBF4 and MeCN are determined for a series of submicron film thicknesses. Measurement of the double-layer capacitance, C sub dl, and the resistance, R sub u, of polypyrrole thin films as a function of potential obtained with the galvanostatic pulse method is reported. Measurements of the electrolyte concentration in reduced polypyrrole films are also presented to aid in the interpretation of the data.

  13. Negative corona current pulses in argon and in mixture argon with SF6

    International Nuclear Information System (INIS)

    Zahoranova, A.; Zahoran, M.; Bucek, A.; Cernak, M.; Bosko, J.

    2004-01-01

    Waveforms of the first negative current pulses in a short negative point-to plane gap in pure argon and argon with SF 6 admixture have been investigated with a nanosecond time resolution at a gas pressure 50 kPa as a function of applied gap voltage and content of SF 6 in the mixture. We have made an attempt to explain the differences in the discharge development in pure argon and in argon with admixture of SF 6 based on the observed changes of the pulse shape. The experimental results obtained will be discussed in context with existing computer simulation models (Authors)

  14. Thermomagnetic writing on deep submicron-patterned TbFe films by nanosecond current pulse

    International Nuclear Information System (INIS)

    You, Long; Kato, Takeshi; Tsunashima, Shigeru; Iwata, Satoshi

    2009-01-01

    This work studies the heating process for deep submicron-patterned TbFe films to be used in a thermally assisted perpendicular magnetic random access memory's writing scheme. The dependence of the heating power density with the current pulse width required for the successful writing was measured in the investigated range of 5-100 ns. In the case of long current pulse, the heat diffuses dominantly into substrate, which resulted in large variation of the required power/energy density with the patterned size. The power/energy densities required for writing increased as the junction area is reduced. While for the short current pulse width, the power/energy densities became rather independent on the size. The required power density for writing 0.38x0.28 μm 2 patterned films using the pulse width of 5 ns is experimentally estimated to be around P=4.7 mW/μm 2 , corresponding to the energy density of E=23 pJ/μm 2 , under an external field of 100 Oe

  15. Effect of pulsed current welding on fatigue behaviour of high strength aluminium alloy joints

    International Nuclear Information System (INIS)

    Balasubramanian, V.; Ravisankar, V.; Madhusudhan Reddy, G.

    2008-01-01

    High strength aluminium alloys (Al-Zn-Mg-Cu alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt%)) grade aluminium alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Fatigue properties of the welded joints have been evaluated by conducting fatigue test using rotary bending fatigue testing machine. Current pulsing leads to relatively finer and more equi-axed grain structure in gas tungsten arc (GTA) and gas metal arc (GMA) welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Grain refinement is accompanied by an increase in fatigue life and endurance limit

  16. Modelling and analysis of the transformer current resonance in dual active bridge converters

    DEFF Research Database (Denmark)

    Qin, Zian; Shen, Zhan; Blaabjerg, Frede

    2017-01-01

    Due to the parasitic capacitances of the transformer and inductor in Dual Active Bridge (DAB) converters, resonance happens in the transformer currents. This high frequency resonant current flowing into the full bridges will worsen their soft-switching performance and thereby reduce its efficiency....... In order to study the generation mechanism of this current resonance, the impedance of the transformer and inductor with parasitic components is modelled in this digest. Then, based on the impedance model, an approach is proposed to mitigate the current resonance. Finally, both the impedance model...

  17. Surface modification of TC4 titanium alloy by high current pulsed electron beam (HCPEB) with different pulsed energy densities

    International Nuclear Information System (INIS)

    Gao, Yu-kui

    2013-01-01

    Highlights: •The hardness changes were determined by nanoindention method. •The surface integrity changes were investigated by different techniques. •The mechanism was analyzed based on AFM and TEM investigations. -- Abstract: Surface changes including surface topography and nanohardness distribution along surface layer were investigated for TC4 titanium alloy by different energy densities of high current pulsed electron beam (HCPEB). The surface topography was characterized by SEM and AFM, and cross-sectional TEM observation was performed to reveal the surface modification mechanism of TC4 titanium alloy by HCPEB. The surface roughness was modified by HCPEB and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM. The fine grain structure inherited from the rapid solidification of the melted layer as well as the strain hardening of the sub-surface are two of the factors responsible the increase in nanohardness

  18. Characterization of interference thin films grown on stainless steel surface by alternate pulse current in a sulphochromic solution

    Directory of Open Access Journals (Sweden)

    Rosa Maria Rabelo Junqueira

    2008-12-01

    Full Text Available The aim of this work was to characterize thin interference films grown on the surface of AISI 304 stainless steel for decorative purposes. Films were grown in a sulphochromic solution at room temperature by an alternating pulse current method. The morphology and chemical state of the elements in the films were investigated by field emission scanning electron microscopy (FESEM, atomic force microscopy (AFM, glow discharge optical emission spectrometry (GDOES, and infrared Fourier transform spectroscopy (FTIR. Depth-sensing indentation (DSI experiments and wear abrasion tests were employed to assess the mechanical resistance of the films. The coloration process resulted in porous thin films which increased the surface roughness of the substrate. The interference films mainly consisted of hydrated chromium oxide containing iron. Increasing film thickness produced different colors and affected the mechanical properties of the coating-substrate system. Thicker films, such as those producing gold and green colors, were softer but more abrasion resistant.

  19. Surface Nano crystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    International Nuclear Information System (INIS)

    Han, Z.; Zou, H.; Wang, Z.; Ji, I.; Cai, J.; Guan, Q.

    2013-01-01

    The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB) technique. The structures of the nano crystallized surface were characterized by X-ray diffraction and electron microscopy. Two nano structures consisting of fine austenite grains (50-150 nm) and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that the dissolution of the carbides and the formation of the supersaturated Fe (C) solid solution play a determining role on the microstructure evolution. Additionally, the formation of fine austenite structure is closely related to the thermal stresses induced by the HCPEB irradiation. The effects of both high carbon content and high value of stresses increase the stability of the austenite, which leads to the complete suppression of martensitic transformation.

  20. Pulsed Direct Current Electrospray: Enabling Systematic Analysis of Small Volume Sample by Boosting Sample Economy.

    Science.gov (United States)

    Wei, Zhenwei; Xiong, Xingchuang; Guo, Chengan; Si, Xingyu; Zhao, Yaoyao; He, Muyi; Yang, Chengdui; Xu, Wei; Tang, Fei; Fang, Xiang; Zhang, Sichun; Zhang, Xinrong

    2015-11-17

    We had developed pulsed direct current electrospray ionization mass spectrometry (pulsed-dc-ESI-MS) for systematically profiling and determining components in small volume sample. Pulsed-dc-ESI utilized constant high voltage to induce the generation of single polarity pulsed electrospray remotely. This method had significantly boosted the sample economy, so as to obtain several minutes MS signal duration from merely picoliter volume sample. The elongated MS signal duration enable us to collect abundant MS(2) information on interested components in a small volume sample for systematical analysis. This method had been successfully applied for single cell metabolomics analysis. We had obtained 2-D profile of metabolites (including exact mass and MS(2) data) from single plant and mammalian cell, concerning 1034 components and 656 components for Allium cepa and HeLa cells, respectively. Further identification had found 162 compounds and 28 different modification groups of 141 saccharides in a single Allium cepa cell, indicating pulsed-dc-ESI a powerful tool for small volume sample systematical analysis.

  1. Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

    International Nuclear Information System (INIS)

    Nobusada, Katsuyuki; Yabana, Kazuhiro

    2007-01-01

    We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

  2. Pulse measurement of the hot spot current in a NbTiN superconducting filament

    Science.gov (United States)

    Harrabi, K.; Mekki, A.; Kunwar, S.; Maneval, J. P.

    2018-02-01

    We have studied the voltage response of superconducting NbTiN filaments to a step-pulse of over-critical current I > Ic. The current induces the destruction of the Cooper pairs and initiates different mechanisms of dissipation depending on the bath temperature T. For the sample investigated, and for T above a certain T*, not far from Tc, the resistance manifests itself in the form of a phase-slip center, which turns into a normal hot spot (HS) as the step-pulse is given larger amplitudes. However, at all temperatures below T*, the destruction of superconductivity still occurs at Ic(T), but leads directly to an ever-growing HS. By lowering the current amplitude during the pulse, one can produce a steady HS and thus define a threshold HS current Ih(T). That is achieved by combining two levels of current, the first and larger one to initiate an HS, the second one to search for constant voltage response. The double diagram of the functions Ic(T) and Ih(T) was plotted in the T-range Tc/2 < T < Tc, and their crossing found at T* = (8.07 ± 0.07) K.

  3. High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines.

    Science.gov (United States)

    Homma, Akira

    2011-07-01

    A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components.

  4. Creating Sustainable Societies: Developing Emerging Professionals through Transforming Current Mindsets

    Science.gov (United States)

    Griswold, Wendy

    2017-01-01

    Future professionals will bear the brunt of creating sustainable societies. Equipping them for the task is the challenge of current educators. Educational experiences facilitating the development of sustainable habits of mind are needed. This research reports on the experiences of developing scientists and engineers engaged in a sustainable energy…

  5. Transformation and Transformational Leadership: A Review of the Current and Relevant Literature for Academic Radiologists.

    Science.gov (United States)

    Thomson, Norman B; Rawson, James V; Slade, Catherine P; Bledsoe, Martin

    2016-05-01

    With the US healthcare system on an unsustainable course, change is inevitable. Changes in the healthcare landscape impacting radiology include changing payment models, rapid adoption of digital technology, changes in radiology resident certifying exams, and the rise of consumerism in health care. Academic Radiology will be part of that change with none of its missions spared. What matters is not that change is coming but how Academic Radiology responds to change. Do we ignore, adapt, adopt others' practices, or lead change? Change management or transformation is a management skill set that can be learned and developed. Transformational leadership is a leadership style defined by the relationships between the leaders and the followers and the results they are able to achieve together to meet organizational goals. In this paper, we provide a review of key change management theories, as well as practical advice for self-reflection and development of leadership behaviors that promote effective change management and organizational transformation, particularly in a complex industry like Academic Radiology. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  6. Investigating the performances of a 1 MV high pulsed power linear transformer driver: from beam dynamics to x radiation

    Directory of Open Access Journals (Sweden)

    R. Maisonny

    2016-12-01

    Full Text Available The performance of a 1 MV pulsed high-power linear transformer driver accelerator were extensively investigated based on a numerical approach which utilizes both electromagnetic and Monte Carlo simulations. Particle-in-cell calculations were employed to examine the beam dynamics throughout the magnetically insulated transmission line which governs the coupling between the generator and the electron diode. Based on the information provided by the study of the beam dynamics, and using Monte Carlo methods, the main properties of the resulting x radiation were predicted. Good agreement was found between these simulations and experimental results. This work provides a detailed understanding of mechanisms affecting the performances of this type of high current, high-voltage pulsed accelerator, which are very promising for a growing number of applications.

  7. Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

    Science.gov (United States)

    d'Almeida, T.; Lassalle, F.; Morell, A.; Grunenwald, J.; Zucchini, F.; Loyen, A.; Maysonnave, T.; Chuvatin, A. S.

    2013-09-01

    SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper, we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or magnetic

  8. Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

    Energy Technology Data Exchange (ETDEWEB)

    D' Almeida, T.; Lassalle, F.; Morell, A.; Grunenwald, J.; Zucchini, F.; Loyen, A. [CEA, DAM, GRAMAT, F-46500 Gramat (France); Maysonnave, T. [International Technologies for High Pulsed Power, F-46500 Thégra (France); Chuvatin, A. S. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-09-15

    SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper, we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or

  9. Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

    International Nuclear Information System (INIS)

    D'Almeida, T.; Lassalle, F.; Morell, A.; Grunenwald, J.; Zucchini, F.; Loyen, A.; Maysonnave, T.; Chuvatin, A. S.

    2013-01-01

    SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper, we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or magnetic

  10. Discrimination Between Inrush and Short Circuit Currents in Differential Protection of Power Transformer Based on Correlation Method Using the Wavelet Transform

    OpenAIRE

    M. Rasoulpoor; M. Banejad; A. Ahmadyfard

    2011-01-01

    This paper presents a novel technique for transformer differential protection to prevent incorrect operation due to inrush current. The proposed method in this paper is based on time-frequency transform known as the Wavelet transform. The discrete Wavelet transform is used for analysis the differential current signals in time and frequency domains. The investigation on the energy distribution of the signal on the discrete Wavelet transform components shows the difference distribution between ...

  11. Preparation of scanning tunneling microscopy tips using pulsed alternating current etching

    International Nuclear Information System (INIS)

    Valencia, Victor A.; Thaker, Avesh A.; Derouin, Jonathan; Valencia, Damian N.; Farber, Rachael G.; Gebel, Dana A.; Killelea, Daniel R.

    2015-01-01

    An electrochemical method using pulsed alternating current etching (PACE) to produce atomically sharp scanning tunneling microscopy (STM) tips is presented. An Arduino Uno microcontroller was used to control the number and duration of the alternating current (AC) pulses, allowing for ready optimization of the procedures for both Pt:Ir and W tips using a single apparatus. W tips prepared using constant and pulsed AC power were compared. Tips fashioned using PACE were sharper than those etched with continuous AC power alone. Pt:Ir tips were prepared with an initial coarse etching stage using continuous AC power followed by fine etching using PACE. The number and potential of the finishing AC pulses was varied and scanning electron microscope imaging was used to compare the results. Finally, tip quality using the optimized procedures was verified by UHV-STM imaging. With PACE, at least 70% of the W tips and 80% of the Pt:Ir tips were of sufficiently high quality to obtain atomically resolved images of HOPG or Ni(111)

  12. Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

    Science.gov (United States)

    Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

    2008-03-01

    Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

  13. Surface composite nanostructures of AZ91 magnesium alloy induced by high current pulsed electron beam treatment

    International Nuclear Information System (INIS)

    Li, M.C.; Hao, S.Z.; Wen, H.; Huang, R.F.

    2014-01-01

    High current pulsed electron beam (HCPEB) treatment was conducted on an AZ91 cast magnesium alloy with accelerating voltage 27 kV, energy density 3 J/cm 2 and pulse duration 2.5 μs. The surface microstructure was characterized by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). The surface corrosion property was tested with electrochemical method in 3.5 wt.% NaCl solution. It is found that after 1 pulse of HCPEB treatment, the initial eutectic α phase and Mg 17 Al 12 particles started to dissolve in the surface modified layer of depth ∼15 μm. When using 15 HCPEB pulses, the Al content in surface layer increased noticeably, and the phase structure was modified as composite nanostructures consisted of nano-grained Mg 3.1 Al 0.9 domains surrounded by network of Mg 17 Al 12 phase. The HCPEB treated samples showed an improved corrosion resistance with cathodic current density decreased by two orders of magnitude as compared to the initial AZ91 alloy.

  14. Preparation of scanning tunneling microscopy tips using pulsed alternating current etching

    Energy Technology Data Exchange (ETDEWEB)

    Valencia, Victor A.; Thaker, Avesh A.; Derouin, Jonathan; Valencia, Damian N.; Farber, Rachael G.; Gebel, Dana A.; Killelea, Daniel R., E-mail: dkillelea@luc.edu [Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W. Sheridan Rd., Chicago, Illinois 60660 (United States)

    2015-03-15

    An electrochemical method using pulsed alternating current etching (PACE) to produce atomically sharp scanning tunneling microscopy (STM) tips is presented. An Arduino Uno microcontroller was used to control the number and duration of the alternating current (AC) pulses, allowing for ready optimization of the procedures for both Pt:Ir and W tips using a single apparatus. W tips prepared using constant and pulsed AC power were compared. Tips fashioned using PACE were sharper than those etched with continuous AC power alone. Pt:Ir tips were prepared with an initial coarse etching stage using continuous AC power followed by fine etching using PACE. The number and potential of the finishing AC pulses was varied and scanning electron microscope imaging was used to compare the results. Finally, tip quality using the optimized procedures was verified by UHV-STM imaging. With PACE, at least 70% of the W tips and 80% of the Pt:Ir tips were of sufficiently high quality to obtain atomically resolved images of HOPG or Ni(111)

  15. Investigation of carbon cathode surface before and after the passage of combined dc vacuum arc with superimposed high-current arc pulses

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Moszynski, D.

    2016-01-01

    The paper presents the results of studies of carbon cathode surface before and after the passage of the combined DC vacuum-arc with superimposed high-current arc pulses. Investigations of surface morphology of carbon cathode showed, that secondary nuclei of high-density are formed after passing of the combined DC-pulse vacuum-arc, which results in the formation of a globular structures. The phase structure analysis by Raman spectroscopy showed that even at a minimum operation time (5 s) of the combined DC-pulse vacuum-arc broadening of the peaks 1355 and 1583 cm-1 occurs, which means that the carbon cathode surface undergo phase transformation. Results obtained by XPS spectroscopy demonstrate that the globular structures formed on the cathode surface are composed of sp 3 -bonded carbon atoms and carbon-oxygen bonds.

  16. The destruction influence of pulse and surge currents on overvoltage protection

    International Nuclear Information System (INIS)

    Glasa, M.; Huettner, L.

    2012-01-01

    This article deals about the influences caused during the active operation process of the surge arrester against the pulse and surge currents. It also refers about a lightning, the characteristic of lightning and about the lightning (surge) currents caused its influence. One parts of the article is focused on a total elimination of surge current energy, and on an ineffective operation, which leads to partially or totally destruction of a protection element. There is a comparison with two basic types of surge arresters (spark gap and varistor based arresters), and theirs re-effectiveness on prescribed level. (Authors)

  17. Advanced electrical current measurements of microdischarges: evidence of sub-critical pulses and ion currents in barrier discharge in air

    Science.gov (United States)

    Synek, Petr; Zemánek, Miroslav; Kudrle, Vít; Hoder, Tomáš

    2018-04-01

    Electrical current measurements in corona or barrier microdischarges are a challenge as they require both high temporal resolution and a large dynamic range of the current probe used. In this article, we apply a simple self-assembled current probe and compare it to commercial ones. An analysis in the time and frequency domain is carried out. Moreover, an improved methodology is presented, enabling both temporal resolution in sub-nanosecond times and current sensitivity in the order of tens of micro-amperes. Combining this methodology with a high-tech oscilloscope and self-developed software, a unique statistical analysis of currents in volume barrier discharge driven in atmospheric-pressure air is made for over 80 consecutive periods of a 15 kHz applied voltage. We reveal the presence of repetitive sub-critical current pulses and conclude that these can be identified with the discharging of surface charge microdomains. Moreover, extremely low, long-lasting microsecond currents were detected which are caused by ion flow, and are analysed in detail. The statistical behaviour presented gives deeper insight into the discharge physics of these usually undetectable current signals.

  18. Investigation of a pulsed current annealing method in reusing MOSFET dosimeters for in vivo IMRT dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Guang-Wen; Qi, Zhen-Yu, E-mail: qizhy@sysucc.org.cn; Deng, Xiao-Wu [Department of Radiation Oncology, Sun Yat-Sen University Cancer Center and State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center of Cancer Medicine, Guangzhou 510060 (China); Rosenfeld, Anatoly [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2014-05-15

    Purpose: To explore the feasibility of pulsed current annealing in reusing metal oxide semiconductor field-effect transistor (MOSFET) dosimeters forin vivo intensity modulated radiation therapy (IMRT) dosimetry. Methods: Several MOSFETs were irradiated atd{sub max} using a 6 MV x-ray beam with 5 V on the gate and annealed with zero bias at room temperature. The percentage recovery of threshold voltage shift during multiple irradiation-annealing cycles was evaluated. Key dosimetry characteristics of the annealed MOSFET such as the dosimeter's sensitivity, reproducibility, dose linearity, and linearity of response within the dynamic range were investigated. The initial results of using the annealed MOSFETs for IMRT dosimetry practice were also presented. Results: More than 95% of threshold voltage shift can be recovered after 24-pulse current continuous annealing in 16 min. The mean sensitivity degradation was found to be 1.28%, ranging from 1.17% to 1.52%, during multiple annealing procedures. Other important characteristics of the annealed MOSFET remained nearly consistent before and after annealing. Our results showed there was no statistically significant difference between the annealed MOSFETs and their control samples in absolute dose measurements for IMRT QA (p = 0.99). The MOSFET measurements agreed with the ion chamber results on an average of 0.16% ± 0.64%. Conclusions: Pulsed current annealing provides a practical option for reusing MOSFETs to extend their operational lifetime. The current annealing circuit can be integrated into the reader, making the annealing procedure fully automatic.

  19. Small-sized monitor of beam current and profile for the proton pulse electrostatic accelerator

    International Nuclear Information System (INIS)

    Getmanov, V.N.

    1985-01-01

    Design and principle of operation of current monitor and beam profile of range-coordinate type are described. Monitor operation peculiarities are discussed using diagnostics of a beam of 330-420 keV electrostatic pulse proton accelerator with a beam current of up to 20 mA, at a current density of up to 23 mA x cm -2 and wth pulse duraton of about 20 μs. The monitor consists of a vacuum-dense foil of 3.0+-0.1 μm in thickness (or 0.81+-0.0x- mg x cm -2 ) two grid electrodes, each containing 12 wires, and as solid copper bottom. Foil serves for chopping off background particles with a path lesser 3.0 μm and stands thermal pulse load up to 0.5 J/cm -2 . Grid electrode wires are oriented perpendicularly to lach other and form a two-coordinate secondary-emisson roughness indicator. The bothhom is used for measuring an absolute value of beam current

  20. Investigation of a pulsed current annealing method in reusing MOSFET dosimeters for in vivo IMRT dosimetry.

    Science.gov (United States)

    Luo, Guang-Wen; Qi, Zhen-Yu; Deng, Xiao-Wu; Rosenfeld, Anatoly

    2014-05-01

    To explore the feasibility of pulsed current annealing in reusing metal oxide semiconductor field-effect transistor (MOSFET) dosimeters for in vivo intensity modulated radiation therapy (IMRT) dosimetry. Several MOSFETs were irradiated at d(max) using a 6 MV x-ray beam with 5 V on the gate and annealed with zero bias at room temperature. The percentage recovery of threshold voltage shift during multiple irradiation-annealing cycles was evaluated. Key dosimetry characteristics of the annealed MOSFET such as the dosimeter's sensitivity, reproducibility, dose linearity, and linearity of response within the dynamic range were investigated. The initial results of using the annealed MOSFETs for IMRT dosimetry practice were also presented. More than 95% of threshold voltage shift can be recovered after 24-pulse current continuous annealing in 16 min. The mean sensitivity degradation was found to be 1.28%, ranging from 1.17% to 1.52%, during multiple annealing procedures. Other important characteristics of the annealed MOSFET remained nearly consistent before and after annealing. Our results showed there was no statistically significant difference between the annealed MOSFETs and their control samples in absolute dose measurements for IMRT QA (p = 0.99). The MOSFET measurements agreed with the ion chamber results on an average of 0.16% ± 0.64%. Pulsed current annealing provides a practical option for reusing MOSFETs to extend their operational lifetime. The current annealing circuit can be integrated into the reader, making the annealing procedure fully automatic.

  1. Investigation of a pulsed current annealing method in reusing MOSFET dosimeters for in vivo IMRT dosimetry

    International Nuclear Information System (INIS)

    Luo, Guang-Wen; Qi, Zhen-Yu; Deng, Xiao-Wu; Rosenfeld, Anatoly

    2014-01-01

    Purpose: To explore the feasibility of pulsed current annealing in reusing metal oxide semiconductor field-effect transistor (MOSFET) dosimeters forin vivo intensity modulated radiation therapy (IMRT) dosimetry. Methods: Several MOSFETs were irradiated atd max using a 6 MV x-ray beam with 5 V on the gate and annealed with zero bias at room temperature. The percentage recovery of threshold voltage shift during multiple irradiation-annealing cycles was evaluated. Key dosimetry characteristics of the annealed MOSFET such as the dosimeter's sensitivity, reproducibility, dose linearity, and linearity of response within the dynamic range were investigated. The initial results of using the annealed MOSFETs for IMRT dosimetry practice were also presented. Results: More than 95% of threshold voltage shift can be recovered after 24-pulse current continuous annealing in 16 min. The mean sensitivity degradation was found to be 1.28%, ranging from 1.17% to 1.52%, during multiple annealing procedures. Other important characteristics of the annealed MOSFET remained nearly consistent before and after annealing. Our results showed there was no statistically significant difference between the annealed MOSFETs and their control samples in absolute dose measurements for IMRT QA (p = 0.99). The MOSFET measurements agreed with the ion chamber results on an average of 0.16% ± 0.64%. Conclusions: Pulsed current annealing provides a practical option for reusing MOSFETs to extend their operational lifetime. The current annealing circuit can be integrated into the reader, making the annealing procedure fully automatic

  2. Elimination of the induced current error in magnetometers using superconducting flux transformers

    International Nuclear Information System (INIS)

    Dummer, D.; Weyhmann, W.

    1987-01-01

    The changing magnetization of a sample in a superconducting flux transformer coupled magnetometer induces a current in the transformer which in turn changes the field at the sample. This ''image'' field and the error caused by it can be eliminated by sensing the current in the loop and nulling it by feedback through a mutual inductance. We have tested the technique on the superconducting transition of indium in an applied magnetic field and shown that the observed width of the transition is greatly reduced by maintaining zero current in the flux transformer

  3. Current Transformations of the Eurozone Financial and Institutional Space

    Directory of Open Access Journals (Sweden)

    Kornіvska Valerіa O.

    2016-08-01

    Full Text Available The article presents the results of studying the processes of reforming the financial and institutional space of the eurozone, which in the long run creates the foundation for basic changes, which will result in not just a postcrisis “restart” of the system of financial institutions, but the creation of new mechanisms of liquidity circulation and in view of this the restructuring of the current model of investment process from mainly the banking into the market (stock one. On the basis of the analysis of the credit cooperation between banking institutions of the eurozone and the real sector there made conclusions about the limited effectiveness of the current model of investment support due to the inability of the dominant financial institutions (banks to enable economic recovery under conditions of the gap between the complementary interaction of banking institutions and the real sector of the economy. The paper justifies that the gap between the complementarity of the banking system and the real sector emerged also in connection with the formation of the negative in the general economic context complementarity of the state and the banking sector, which greatly distorts the competitive foundations of the European financial and institutional space, contributes to the banking lobby, hinders the process of reforming the banking space, which will be of limited effectiveness in the future

  4. AC over-current test results of YBCO conductor for YBCO power transformer with fault current limiting function

    International Nuclear Information System (INIS)

    Tomioka, A.; Otonari, T.; Ogata, T.; Iwakuma, M.; Okamoto, H.; Hayashi, H.; Iijima, Y.; Saito, T.; Gosho, Y.; Tanabe, K.; Izumi, T.; Shiohara, Y.

    2011-01-01

    The single-layer coils with a diameter of 250 mm and 12 turns were manufactured with YBCO tapes with a CuNi- or Cu-Tape. The AC over-current tests were carried out in subcooled liquid nitrogen at 66 K and 74 K to develop power transformers with current limiting function. The AC over-current was two to seven times larger than the I c of conductor and it was reduced to the same level of I c . The I c of model coils did not degrade. The test results showed the possibility of YBCO superconducting transformers with current limiting function. We are developing elemental technology for 66 kV/6.9 kV 20 MVA-class YBCO power transformer. The YBCO transformer is considered to have a possibility to stabilize the power system by improving function of fault current limiting. Current limiting behavior functions over critical current flows. There is a possibility that superconducting characteristic may be damaged due to increase in temperature of YBCO tapes. Therefore, we have taken a measure to combine YBCO tape with CuNi tape or Cu Tape. We manufactured model coils using these conductors and conducted the AC over-current tests. The test current was two to seven times larger than the I c of conductor and it was damped with time from its maximum value according to the generation of conductor resistance. We verified the effectiveness of current limiting characteristics. In these tests, the I c of model coil did not degrade. We consider this conductor to be able to withstand AC over-current with the function of current limiting.

  5. VME computer monitoring system of KEK-PS fast pulsed magnet currents and beam intensities

    International Nuclear Information System (INIS)

    Kawakubo, T.; Akiyama, A.; Kadokura, E.; Ishida, T.

    1992-01-01

    For beam transfer from the KEK-PS Linac to the Booster synchrotron ring and from the Booster to the Main ring, many pulse magnets have been installed. It is very important for the machine operation to monitor the firing time, rising time and peak value of the pulsed magnet currents. It is also very important for magnet tuning to obtain good injection efficiency of the Booster and the Main ring, and to observe the last circulating bunched beam in the Booster as well as the first circulating in the Main. These magnet currents and beam intensity signals are digitized by a digital oscilloscope with signal multiplexers, and then shown on a graphic display screen of the console via a VME computer. (author)

  6. Detection of wall thinning of carbon steel pipe covered with insulation using Pulsed Eddy Current technique

    International Nuclear Information System (INIS)

    Park, Duckgun; Kishore, M. B.; Lee, D. H.

    2013-01-01

    The test sample is a ferromagnetic carbon steel pipe having different thickness, covered with a 10 cm plastic insulation laminated by 0.4 mm Al plate to simulate the pipelines in NPPs. The PEC Probe used for the wall thinning detection consists of an excitation coil and a Hall sensor. The excitation coils in the probe is driven by a rectangular bipolar current pulse and the Hall-sensor will detects the resultant field. The Hall sensor output is considered as PEC signal. Results shows that the PEC system can detect wall thinning in an insulated pipeline of the NPPs. Local wall thinning in pipelines affects the structural integrity of industries like nuclear power plants (NPPs). In the present study a pulsed eddy current (PEC) technology to detect the wall thing of carbon steel pipe covered with insulation is developed

  7. Nickel coating on high strength low alloy steel by pulse current deposition

    Science.gov (United States)

    Nigam, S.; Patel, S. K.; Mahapatra, S. S.; Sharma, N.; Ghosh, K. S.

    2015-02-01

    Nickel is a silvery-white metal mostly used to enhance the value, utility, and lifespan of industrial equipment and components by protecting them from corrosion. Nickel is commonly used in the chemical and food processing industries to prevent iron from contamination. Since the properties of nickel can be controlled and varied over broad ranges, nickel plating finds numerous applications in industries. In the present investigation, pulse current electro-deposition technique has been used to deposit nickel on a high strength low alloy (HSLA) steel substrate.Coating of nickel is confirmed by X-ray diffraction (XRD) and EDAX analysis. Optical microscopy and SEM is used to assess the coating characteristics. Electrochemical polarization study has been carried out to study the corrosion behaviour of nickel coating and the polarisation curves have revealed that current density used during pulse electro-deposition plays a vital role on characteristics of nickel coating.

  8. Detection of the Thickness Variation of a Stainless Steel sample using Pulsed Eddy Current

    International Nuclear Information System (INIS)

    Cheong, Y. M.; Angani, C. S.; Park, D. G.; Jhong, H. K.; Kim, G. D.; Kim, C. G.

    2008-01-01

    The Pulsed Eddy Current (PEC) system has been developed for the detection of thickness variation of stainless steel. The sample was machined as step configuration using stainless steel for thickness variation from 1mm to 5mm step by step. The LabView computer program was developed to display the variation in the amplitude of the detected pulse by scanning the PECT probe on the flat side of the sample. The pickup Sensor measures the effective magnetic field on the sample, which is the sum of the incident field and the field reflected by the specimen due to the induced eddy currents in the sample. We use the hall sensor for the detection. Usage of hall sensor instead of coil as a field detector improves the detectability and special resolution. This technology can be used in detection of local wall thinning of the pipeline of nuclear power plant

  9. Charge and spin current oscillations in a tunnel junction induced by magnetic field pulses

    Energy Technology Data Exchange (ETDEWEB)

    Dartora, C.A., E-mail: cadartora@eletrica.ufpr.br [Electrical Engineering Department, Federal University of Parana (UFPR), C.P. 19011 Curitiba, 81.531-970 PR (Brazil); Nobrega, K.Z., E-mail: bzuza1@yahoo.com.br [Federal Institute of Education, Science and Technolgy of Maranhão (IFMA), Av. Marechal Castelo Branco, 789, São Luís, 65.076-091 MA (Brazil); Cabrera, G.G., E-mail: cabrera@ifi.unicamp.br [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas 13.083-970 SP (Brazil)

    2016-08-15

    Usually, charge and spin transport properties in tunnel junctions are studied in the DC bias regime and/or in the adiabatic regime of time-varying magnetic fields. In this letter, the temporal dynamics of charge and spin currents in a tunnel junction induced by pulsed magnetic fields is considered. At low bias voltages, energy and momentum of the conduction electrons are nearly conserved in the tunneling process, leading to the description of the junction as a spin-1/2 fermionic system coupled to time-varying magnetic fields. Under the influence of pulsed magnetic fields, charge and spin current can flow across the tunnel junction, displaying oscillatory behavior, even in the absence of DC bias voltage. A type of spin capacitance function, in close analogy to electric capacitance, is predicted.

  10. The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array

    International Nuclear Information System (INIS)

    Hu, J. T.; Liu, X. Y.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

    2012-01-01

    Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as “plasma bullet” is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.

  11. Numerical simulation and experiment of high-intensity current pulsed impact on the structure body

    International Nuclear Information System (INIS)

    Li Mintang; Yan Ping; Yuan Weiqun; Sun Yaohong; Sun Lianhua; Zhou Yuan; Liu Chuanpu

    2010-01-01

    To better understand the characteristics of the impulse force formed by pulse current of electromagnetic rail propulsion system, and to explore effective ways to improve the support structure of rails, a set of impulse force test system was designed, and the work-related test situation was numerically simulated. Several impulse force waveforms formed by different pulse current waveforms were achieved by using an armature as a source of impulse force in this test system, and two curves of waveform were comparatively analyzed. The armature existing in the environment of coupling fields including electric field and magnetic field and force field was carried out numerical calculation by using the software of ANSYS, and the coupling force field was emphatically analyzed to calculate the electromagnetic driving force and the electromagnetic clamping force acting on the armature, and the structure stress and deformation was also analyzed. The results showed that the curves of electromagnetic driving force computed by numerical simulation and the curves of impulse force obtained by experiment were basically the same, and the value of peak points' error was increasing along with the increase of pulse current, but the curves still showed some common characteristics. This verified that the test method we used in this paper was proper to capture the impulse force, and the method of calculation was also feasible and effective. (authors)

  12. Research on Harmonic Characteristic of Electronic Current Transformer Based on the Rogowski Coil

    Science.gov (United States)

    Shen, Diqiu; Hu, Bei; Wang, Xufeng; Zhu, Mingdong; Wang, Liang; Lu, Wenxing

    2017-05-01

    The nonlinear load present in the power system will cause the distortion of AC sine wave and generate the harmonic, which havea severe impact on the accuracy of energy metering and reliability of relay protection. Tosatisfy the requirements of energy metering and relay protection for the new generation of intelligent substation, based on the working principle of Rogowski coil current transformer, mathematical model and transfer characteristics of Rogowski coil sensors were studied in this paper, and frequency response characteristics of Rogowski coil current transformer system were analysed. Finally, the frequency response characteristics of the Rogowski coil current transformer at 2 to 13 harmonics was simulated and experimented. Simulation and experiments show that Rogowski coil current transformer couldmeet 0.2 accuracy requirements of harmonic power measurement of power system, and measure the harmonic components of the grid reliably.

  13. Domain wall manipulation in magnetic nanotubes induced by electric current pulses

    International Nuclear Information System (INIS)

    Otálora, J A; López-López, J A; Landeros, P; Núñez, A S

    2012-01-01

    We propose that the injection of electric currents can be used to independently manipulate the position and chirality of vortex-like domain walls in metallic ferromagnetic nanotubes. We support this proposal upon theoretical and numerical assessment of the magnetization dynamics driven by such currents. We show that proper interplay between the tube geometry, magnitude of the electric current and the duration of a current pulse, can be used to manipulate the position, velocity and chirality of a vortex domain wall. Our calculations suggest that domain wall velocities greater than 1 km s -1 can be achieved for tube diameters of the order of 30 nm and increasing with it. We also find that the transition from steady to precessional domain wall motion occurs for very high electric current densities, of the order of 10 13 A m -2 . Furthermore, the great stability displayed by such chiral magnetic configurations, and the reduced Ohmic loses provided by the current pulses, lead to highly reproducible and efficient domain wall reversal mechanisms.

  14. A 6.4 kV pulse generator with transformations

    International Nuclear Information System (INIS)

    Bastein, W.L.

    1989-01-01

    The possibility has been investigated to perform a pulse generator which generates pulse for the cathode of the injector of the NIKHEF electron accelerator, which generates pulses of 6.4 kV with sides of 100 ns a duration of 2 to 50 microseconds and a frequency of 2500 Hz. The voltage ripple should be smaller than frequency part and one for the high-frequency part, it is possible to generate a pulse which fulfills the requirements with regard to the sides. However installing an tuning of circuits in order to obtain a sufficiently flat pulse will cost much time. Moreover the losses are such high that it deserves recommendation to investigate the possibility ot generate the pulse with a number of MOSFets connected in series. (author). 8 refs.; 8 figs.; 14 photos; 1 tab

  15. A dispersion-balanced Discrete Fourier Transform of repetitive pulse sequences using temporal Talbot effect

    Science.gov (United States)

    Fernández-Pousa, Carlos R.

    2017-11-01

    We propose a processor based on the concatenation of two fractional temporal Talbot dispersive lines with balanced dispersion to perform the DFT of a repetitive electrical sequence, for its use as a controlled source of optical pulse sequences. The electrical sequence is used to impart the amplitude and phase of a coherent train of optical pulses by use of a modulator placed between the two Talbot lines. The proposal has been built on a representation of the action of fractional Talbot effect on repetitive pulse sequences and a comparison with related results and proposals. It is shown that the proposed system is reconfigurable within a few repetition periods, has the same processing rate as the input optical pulse train, and requires the same technical complexity in terms of dispersion and pulse width as the standard, passive pulse-repetition rate multipliers based on fractional Talbot effect.

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

    International Nuclear Information System (INIS)

    Mendes, Luciano A.; Rodrigues, Jhonatam C.; Mafra, Marcio

    2012-01-01

    The glow-to-arc transition phenomena (arcing) observed in plasma reactors used in materials processing was studied through the arcs characteristic current and voltage waveforms. In order to capture these arcs signals, a LABVIEW based automated instrumentation system (ARCVIEW) was developed, including the integration of an oscilloscope equipped with proper current and voltage probes. The system also allows capturing the process parameters at the arc occurrence moments, which were used to map the arcs events conditions. Experiments in H 2 -Ar DC pulsed plasma returned signals data from 215 arcs events, which were analyzed through software routines. According to the results, an anti-arcing system should react in the time order of few microseconds to prevent most of the damage caused by the undesired arcing phenomena.

  17. Regression analysis of pulsed eddy current signals for inspection of steam generator tube support structures

    International Nuclear Information System (INIS)

    Buck, J.; Underhill, P.R.; Mokros, S.G.; Morelli, J.; Krause, T.W.; Babbar, V.K.; Lepine, B.

    2015-01-01

    Nuclear steam generator (SG) support structure degradation and fouling can result in damage to SG tubes and loss of SG efficiency. Conventional eddy current technology is extensively used to detect cracks, frets at supports and other flaws, but has limited capabilities in the presence of multiple degradation modes or fouling. Pulsed eddy current (PEC) combined with principal components analysis (PCA) and multiple linear regression models was examined for the inspection of support structure degradation and SG tube off-centering with the goal of extending results to include additional degradation modes. (author)

  18. Noncircular plasma shape analysis in long-pulse current drive experiment in TRIAM-1M

    International Nuclear Information System (INIS)

    Minooka, Mayumi; Kawasaki, Shoji; Jotaki, Eriko; Moriyama, Shin-ichi; Nagao, Akihiro; Nakamura, Kazuo; Hiraki, Naoji; Nakamura, Yukio; Itoh, Satoshi

    1991-01-01

    Plasma cross section was noncircularized and the plasma shape was analyzed in order to study the characteristics of the plasma in long-pulse current drive experiments in high-field superconducting tokamak TRIAM-1M. Filament approximation method was adopted, since on-line processing by data processing computer is possible. The experiments of the noncircularization were carried out during 30-to 60-sec discharges. As a result, it became clear that D-shape plasma of elongation ratio 1.4 was maintained stably. By the analysis the internal inductance and poloidal beta were assessed, and so informations about the plasma current profile and internal pressure were obtained. (author)

  19. Blind detection of isolated astrophysical pulses in the spatial Fourier transform domain

    Science.gov (United States)

    Schmid, Natalia A.; Prestage, Richard M.

    2018-04-01

    We present a novel approach for the detection of isolated transients in pulsar surveys and fast radio transient observations. Rather than the conventional approach of performing a computationally expensive blind DM search, we take the spatial Fourier transform (SFT) of short (˜ few seconds) sections of data. A transient will have a characteristic signature in the SFT domain, and we present a blind statistic which may be used to detect this signature at an empirical zero False Alarm Rate (FAR). The method has been evaluated using simulations, and also applied to two fast radio burst observations. In addition to its use for current observations, we expect this method will be extremely beneficial for future multi-beam observations made by telescopes equipped with phased array feeds.

  20. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Dian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Tang, Guangze, E-mail: oaktang@hit.edu.cn [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Gu, Le [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Mingren [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-10-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm{sup 2}. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm{sup 2}) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

  1. Pulsed eddy current differential probe to detect the defects in a stainless steel pipe

    Science.gov (United States)

    Angani, C. S.; Park, D. G.; Kim, C. G.; Leela, P.; Kishore, M.; Cheong, Y. M.

    2011-04-01

    Pulsed eddy current (PEC) is an electromagnetic nondestructive technique widely used to detect and quantify the flaws in conducting materials. In the present study a differential Hall-sensor probe which is used in the PEC system has been fabricated for the detection of defects in stainless steel pipelines. The differential probe has an exciting coil with two Hall-sensors. A stainless steel test sample with electrical discharge machining (EDM) notches under different depths of 1-5 mm was made and the sample was laminated by plastic insulation having uniform thickness to simulate the pipelines in nuclear power plants (NPPs). The driving coil in the probe is excited by a rectangular current pulse and the resultant response, which is the difference of the two Hall-sensors, has been detected as the PEC probe signal. The discriminating time domain features of the detected pulse such as peak value and time to zero are used to interpret the experimental results with the defects in the test sample. A feature extraction technique such as spectral power density has been devised to infer the PEC response.

  2. Mechanism for negative corona current pulse in CO sub 2 -SF sub 6 mixtures

    CERN Document Server

    Zahoranova, A; Simor, M; Cernak, M

    2003-01-01

    Current waveforms of first negative corona pulses have been measured in CO sub 2 -SF sub 6 mixtures over a pressure range extending from 6.65 to 50 kPa and various overvoltages. Effects of changing cathode secondary electron emission were studied using a copper cathode coated by CuI and graphite. For a given set of experimental conditions it is concluded that in the mixtures containing up to 30% of SF sub 6 the negative corona pulse is associated with the formation of a cathode-directed streamer-like ionizing wave in the immediate vicinity of the cathode. This is in contrast to the discharge behaviour in air-SF sub 6 and N sub 2 -SF sub 6 mixtures, where in similar conditions the discharge develops according to a multi-avalanche Townsend mechanism. (rapid communication)

  3. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, S A; Puzynin, I V; Samojlov, V N; Sissakyan, A N [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    1997-12-31

    A new high-current pulsed linear induction accelerator proposed for application in beam-driven transmutation technologies is described. The accelerator consists of an ion injector, of ion separation and induction accelerating systems, and of an output system for extracting an ion beam into open air. An ion source with explosive ion emission, capable of producing various kinds of ions, is used as an injector. The ion separator exploits a pulsed magnetic system. The induction acceleration structure includes inductors with amorphous iron cores. Imbedded magnetic elements assure the ion beam transport. Main parameters of the accelerator are given in the paper and the design of an ion injector is discussed in more detail. (J.U.). 3 figs., 3 refs.

  4. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    International Nuclear Information System (INIS)

    Korenev, S.A.; Puzynin, I.V.; Samojlov, V.N.; Sissakyan, A.N.

    1996-01-01

    A new high-current pulsed linear induction accelerator proposed for application in beam-driven transmutation technologies is described. The accelerator consists of an ion injector, of ion separation and induction accelerating systems, and of an output system for extracting an ion beam into open air. An ion source with explosive ion emission, capable of producing various kinds of ions, is used as an injector. The ion separator exploits a pulsed magnetic system. The induction acceleration structure includes inductors with amorphous iron cores. Imbedded magnetic elements assure the ion beam transport. Main parameters of the accelerator are given in the paper and the design of an ion injector is discussed in more detail. (J.U.). 3 figs., 3 refs

  5. Effect of pulse current on acidification and removal of Cu, Cd, and As during suspended electrodialytic soil remediation

    DEFF Research Database (Denmark)

    Sun, Tian Ran; Ottosen, Lisbeth M.; Jensen, Pernille Erland

    2013-01-01

    The effect of pulse current on the acidification process and the removal of heavy metals during suspended electrodialytic soil remediation were investigated in this work. Eight experiments with constant and pulse current in two polluted soils were conducted using a 3-compartment membrane cell......, predominately working under overlimiting current density conditions. Soil 1 was sampled from a pile of excavated soil at a site with mixed industrial pollution (Cu and Cd), and soil 2 was sampled from the top layer of a wood preservation site (Cu and As). Results showed that pulse current improved...... the acidification by supplying more reactive H+ ions (defined as the H+ ions causing release of heavy metals from soil particles). The molar ratio of reactive H+ ions to total produced H+ ions (RH+/PH+) was higher in every pulse current experiment than in the corresponding constant current experiment. In addition...

  6. Elemental redistribution in coloured films on SUS304 stainless steel produced by current pulse method

    International Nuclear Information System (INIS)

    Lin, C.J.; Duh, J.G.

    1996-01-01

    Coloured films are deposited on an SUS304 substrate by the square wave current pulse method in a 2.5 M CrO 3 + 5 M H 2 SO 4 solution at 75 C. The absolute ratio of anodic to cathodic charge density and the corresponding final value of cathodic potential provide an easy and appropriate approach to the control of colour in the current pulse colouring method. This is proved in this study for a frequency region lower than 1 Hz. The corresponding cathodic potential increases with increasing dwell time in the negative applied current region and is related to the colour tone of the deposited film. The total time required to obtain the same thickness of coloured film is shorter at lower frequency than at higher frequency, which takes more time to charge the double layer. The thickness of the coloured films is determined by both Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) depth profiling and is of submicron order. The film thickness is proportional to the introduced total charge per unit area in the current pulse colouring process. CrO + and FeO + ions are observed in the coloured films and their concentrations increase as the colouring time is increased. The Fe concentration in the coloured films is lower than that in the substrate and decreases with the colouring time. It is the iron species that first becomes involved in the anodic reaction and the spinel oxide structure of iron and chromium is present in the coloured films. (orig.)

  7. High-current relativistic klystron amplifier development for microsecond pulse lengths

    International Nuclear Information System (INIS)

    Fazio, M.V.; Carlsten, B.E.; Faehl, R.J.; Kwan, T.J.; Rickel, D.G.; Stringfield, R.M.; Tallerico, P.J.

    1991-01-01

    Los Alamos is extending the performance of the Friedman-type, high-current relativistic klystron amplifier (RKA) to the microsecond regime while attempting to achieve the gigawatt-level peak power capability that has been characteristic of the RKA at shorter pulse lengths. Currently the electron beam power into the device is about 1 GW in microsecond duration pulses, with an effort underway to increase the beam power to 2.5 GW. To date the device has yielded an rf modulated electron beam power of 350 MW, with up to 50 MW coupled into waveguide. Several aspects of RKA operation under investigation that affect RKA beam bunching efficiency and amplifier gain include cavity tuning, beam diameter, beam current, and input rf drive power, and the development of an output coupler that efficiently couples the microwave power from the low impedance beam into rectangular waveguide operating in the dominant mode. Current results from experimental testing and code modelling are presented. 5 refs., 5 figs

  8. Surface Crack Detection for Carbon Fiber Reinforced Plastic Materials Using Pulsed Eddy Current Based on Rectangular Differential Probe

    Directory of Open Access Journals (Sweden)

    Jialong Wu

    2014-01-01

    Full Text Available Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed eddy current detection method based on rectangular differential probe can effectively improve the sensitivity of surface defect detection of carbon fiber reinforced composite material.

  9. Propagation of ultrashort laser pulses in water: linear absorption and onset of nonlinear spectral transformation.

    Science.gov (United States)

    Sokolov, Alexei V; Naveira, Lucas M; Poudel, Milan P; Strohaber, James; Trendafilova, Cynthia S; Buck, William C; Wang, Jieyu; Strycker, Benjamin D; Wang, Chao; Schuessler, Hans; Kolomenskii, Alexandre; Kattawar, George W

    2010-01-20

    We study propagation of short laser pulses through water and use a spectral hole filling technique to essentially perform a sensitive balanced comparison of absorption coefficients for pulses of different duration. This study is motivated by an alleged violation of the Bouguer-Lambert-Beer law at low light intensities, where the pulse propagation is expected to be linear, and by a possible observation of femtosecond optical precursors in water. We find that at low intensities, absorption of laser light is determined solely by its spectrum and does not directly depend on the pulse duration, in agreement with our earlier work and in contradiction to some work of others. However, as the laser fluence is increased, interaction of light with water becomes nonlinear, causing energy exchange among the pulse's spectral components and resulting in peak-intensity dependent (and therefore pulse-duration dependent) transmission. For 30 fs pulses at 800 nm center wavelength, we determine the onset of nonlinear propagation effects to occur at a peak value of about 0.12 mJ/cm(2) of input laser energy fluence.

  10. Power crowbar system coupled by a current transformer with very low leakage inductance

    International Nuclear Information System (INIS)

    Kitagawa, S.; Hirano, K.I.

    1976-01-01

    A reliable, efficient power crowbar system has been developed for fast pinch experiments. In order to reduce the effective impedance of series capacitor system, a current transformer with extremely low leakage inductance has been designed and used. Primary and secondary windings of the transformer are alternately arranged as closely as possible. As a result, the leakage inductance is reduced to 2 nH. It is demonstrated that a current of 390 kA, the rise time of which is 4.5 μsec, is sustained for 100 μsec. Much larger system is being built, which maintains a current of 1 MA over 1 msec. The life of crowbar gap switches is prolonged by the aid of a mechanically-driven metal-to-metal contact switch. Another crowbar switch system with a high coulomb rating is under consideration, in which a gap switch is used together with a saturable reactor and a current transformer

  11. Laminar iridium coating produced by pulse current electrodeposition from chloride molten salt

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Li’an, E-mail: mr_zla@163.com; Bai, Shuxin; Zhang, Hong; Ye, Yicong

    2013-10-01

    Due to the unique physical and chemical properties, Iridium (Ir) is one of the most promising oxidation-resistant coatings for refractory materials above 1800 °C in aerospace field. However, the Ir coatings prepared by traditional methods are composed of columnar grains throughout the coating thickness. The columnar structure of the coating is considered to do harm to its oxidation resistance. The laminar Ir coating is expected to have a better high-temperature oxidation resistance than the columnar Ir coating does. The pulse current electrodeposition, with three independent parameters: average current density (J{sub m}), duty cycle (R) and pulse frequency (f), is considered to be a promising method to fabricate layered Ir coating. In this study, laminar Ir coatings were prepared by pulse current electrodeposition in chloride molten salt. The morphology, roughness and texture of the coatings were determined by scanning electron microscope (SEM), profilometer and X-ray diffraction (XRD), respectively. The results showed that the laminar Ir coatings were composed of a nucleation layer with columnar structure and a growth layer with laminar structure. The top surfaces of the laminar Ir coatings consisted of cauliflower-like aggregates containing many fine grains, which were separated by deep grooves. The laminar Ir coating produced at the deposition condition of 20 mA/cm{sup 2} (J{sub m}), 10% (R) and 6 Hz (f) was quite smooth (R{sub a} 1.01 ± 0.09 μm) with extremely high degree of preferred orientation of 〈1 1 1〉, and its laminar structure was well developed with clear boundaries and uniform thickness of sub-layers.

  12. High ion charge states in a high-current, short-pulse, vacuum ARC ion sources

    International Nuclear Information System (INIS)

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

    1996-01-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1-4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several μs) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution

  13. High ion charge states in a high-current, short-pulse, vacuum arc ion source

    International Nuclear Information System (INIS)

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

    1995-09-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1--4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several micros) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution

  14. A frequency domain approach to analyzing passive battery-ultracapacitor hybrids supplying periodic pulsed current loads

    International Nuclear Information System (INIS)

    Kuperman, Alon; Aharon, Ilan; Kara, Avi; Malki, Shalev

    2011-01-01

    Highlights: → Passive battery-ultracapacitor hybrids are examined. → Frequency domain analysis is employed. → The ultracapacitor branch operates as a low-pass filter for the battery. → The battery supplies the average load demand. → Design requirements are discussed. - Abstract: A Fourier-based analysis of passive battery-ultracapacitor hybrid sources is introduced in the manuscript. The approach is first introduced for a general load, and then is followed by a study for a case of periodic pulsed current load. It is shown that the ultracapacitor branch is perceived by the battery as a low-pass filter, which absorbs the majority of the high frequency harmonic current and letting the battery to supply the average load demand in addition to the small part of dynamic current. Design requirements influence on the ultracapacitor capacitance and internal resistance choice are quantitatively discussed. The theory is enforced by simulation and experimental results, showing an excellent agreement.

  15. Predictive Pulse Pattern Current Modulation Scheme for Harmonic Reduction in Three-Phase Multidrive Systems

    DEFF Research Database (Denmark)

    Davari, Pooya; Yang, Yongheng; Zare, Firuz

    2016-01-01

    at the rectification stage to synthesize sinusoidal input currents. The input voltage sensing is avoided in order to minimize the number of required sensors, and the grid synchronization also has been implemented based on a common Phase-Locked-Loop (PLL) using the DC-link capacitor voltage ripple. Experimental results......The majority of the industrial motor drive systems are equipped with the conventional line-commutated front-end rectifiers, and being one of the main sources of harmonics in the power line. While a parallel combination of these drive units elevates current quality issues, a proper arrangement...... of them can lead to the cancellation of specific harmonics. This paper proposes a new cost-effective harmonic mitigation solution for multi-drive systems using a predictive pulse pattern current modulation control strategy. The proposed technique applies suitable interaction among parallel drive units...

  16. Self-consistent model for pulsed direct-current N2 glow discharge

    International Nuclear Information System (INIS)

    Liu Chengsen

    2005-01-01

    A self-consistent analysis of a pulsed direct-current (DC) N 2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column). Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment. (authors)

  17. Influence of pulsed current on deformation mechanism of AZ31B sheets during tension

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kai [National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, 1954 Hua Shan Road, Shanghai 200030 (China); Dong, Xianghuai, E-mail: dongxh@sjtu.edu.cn [National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, 1954 Hua Shan Road, Shanghai 200030 (China); Xie, Huanyang [Shanghai Superior Die Technology Co., Ltd, 775 Jinsui Road, Shanghai 201209 (China); Wu, Yunjian; Peng, Fang [National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, 1954 Hua Shan Road, Shanghai 200030 (China)

    2016-08-15

    The tensile tests of AZ31B sheets were carried out under pulsed current (PC) of different frequencies, and then the deformation mechanism at different conditions was analyzed by X-Ray Diffraction. The results show that PC does not change the initial yield stress, but reduces the work hardening rate and induces softening effect. Furthermore, electroplasticity effect is controlled by thermal activation. When Z (Zener-Hollomon parameter) is high, the effect of PC is limited, causing a relatively weak electroplasticity effect. With the increasing of Z, the effect of PC strengthens. When Z reaches the critical condition, the activated slip systems obviously change because of PC, which induces the change of texture evolution and the discontinuous change of the intensity of electroplasticity. When Z is low, electroplasticity effect reaches a saturate condition and does not change with Z. Moreover, higher frequency contributes to the dislocation annihilation at all the slip systems, and then increasing frequency can strengthen the extra softening effect of PC. - Highlights: • Pulsed current does not change the initial yield stress, but reduce the work hardening rate and cause softening effect. • Increasing frequency can strengthen the softening effect. • The rules of the softening effect at different deformation condition are different. • The influence of current on deformation mechanism was analyzed by XRD.

  18. Extreme degree of ionization in homogenous micro-capillary plasma columns heated by ultrafast current pulses.

    Science.gov (United States)

    Avaria, G; Grisham, M; Li, J; Tomasel, F G; Shlyaptsev, V N; Busquet, M; Woolston, M; Rocca, J J

    2015-03-06

    Homogeneous plasma columns with ionization levels typical of megaampere discharges are created by rapidly heating gas-filled 520-μm-diameter channels with nanosecond rise time current pulses of 40 kA. Current densities of up to 0.3  GA cm^{-2} greatly increase Joule heating with respect to conventional capillary discharge Z pinches, reaching unprecedented degrees of ionization for a high-Z plasma column heated by a current pulse of remarkably low amplitude. Dense xenon plasmas are ionized to Xe^{28+}, while xenon impurities in hydrogen discharges reach Xe^{30+}. The unique characteristics of these hot, ∼300:1 length-to-diameter aspect ratio plasmas allow the observation of unexpected spectroscopic phenomena. Axial spectra show the unusual dominance of the intercombination line over the resonance line of He-like Al by nearly an order of magnitude, caused by differences in opacities in the axial and radial directions. These plasma columns could enable the development of sub-10-nm x-ray lasers.

  19. Electrocatalysis of the hydrogen evolution reaction by rhenium oxides electrodeposited by pulsed-current

    International Nuclear Information System (INIS)

    Vargas-Uscategui, Alejandro; Mosquera, Edgar; Chornik, Boris; Cifuentes, Luis

    2015-01-01

    Highlights: • Rhenium oxides were produced by means of pulsed current electrodeposition over ITO. • The electrocatalytic behavior of rhenium oxides electrodeposited over ITO was studied. • Electrodeposited rhenium oxides showed electrocatalytic behavior increasing the rate of the hydrogen evolution reaction. • The electrocatalysis behavior was explained considering the relative abundance of Re species on the surface of the electrodeposited material. - Abstract: Rhenium oxides are materials of interest for applications in the catalysis of reactions such as those occurring in fuel cells and photoelectrochemical cells. This research work was devoted to the production of rhenium oxide by means of pulsed current electrodeposition for the electrocatalysis of the hydrogen evolution reaction (HER). Rhenium oxides were electrodeposited over a transparent conductive oxide substrate (Indium Tin-doped Oxide – ITO) in an alkaline aqueous electrolyte. The electrodeposition process allowed the production of rhenium oxides islands (200–600 nm) with the presence of three oxidized rhenium species: Re"I"V associated to ReO_2, Re"V"I associated to ReO_3 and Re"V"I"I associated to H(ReO_4)H_2O. Electrodeposited rhenium oxides showed electrocatalytic behavior over the HER and an increase of one order of magnitude of the exchange current density was observed compared to the reaction taking place on the bare substrate. The electrocatalytic behavior varied with the morphology and relative abundance of oxidized rhenium species in the electrodeposits. Finally, two mechanisms of electrocatalysis were proposed to explain experimental results.

  20. Characterization of an electrochemical mercury sensor using alternating current, cyclic, square wave and differential pulse voltammetry

    International Nuclear Information System (INIS)

    Guerreiro, Gabriela V.; Zaitouna, Anita J.; Lai, Rebecca Y.

    2014-01-01

    Graphical abstract: -- Highlights: •An electrochemical Hg(II) sensor based on T–Hg(II)–T sensing motif was fabricated. •A methylene blue-modified DNA probe was used to fabricate the sensor. •Sensor performance was evaluated using ACV, CV, SWV, and DPV. •The sensor behaves as a “signal-off” sensor in ACV and CV. •The sensor behaves as either a “signal-on” or “signal-off” sensor in SWV and DPV. -- Abstract: Here we report the characterization of an electrochemical mercury (Hg 2+ ) sensor constructed with a methylene blue (MB)-modified and thymine-containing linear DNA probe. Similar to the linear probe electrochemical DNA sensor, the resultant sensor behaved as a “signal-off” sensor in alternating current voltammetry and cyclic voltammetry. However, depending on the applied frequency or pulse width, the sensor can behave as either a “signal-off” or “signal-on” sensor in square wave voltammetry (SWV) and differential pulse voltammetry (DPV). In SWV, the sensor showed “signal-on” behavior at low frequencies and “signal-off” behavior at high frequencies. In DPV, the sensor showed “signal-off” behavior at short pulse widths and “signal-on” behavior at long pulse widths. Independent of the sensor interrogation technique, the limit of detection was found to be 10 nM, with a linear dynamic range between 10 nM and 500 nM. In addition, the sensor responded to Hg 2+ rather rapidly; majority of the signal change occurred in 2+ , which has not been previously reported. More importantly, the observed “switching” behavior in SWV and DPV is potentially generalizable and should be applicable to most sensors in this class of dynamics-based electrochemical biosensors

  1. Research on Defects Inspection of Solder Balls Based on Eddy Current Pulsed Thermography

    Directory of Open Access Journals (Sweden)

    Xiuyun Zhou

    2015-10-01

    Full Text Available In order to solve tiny defect detection for solder balls in high-density flip-chip, this paper proposed feasibility study on the effect of detectability as well as classification based on eddy current pulsed thermography (ECPT. Specifically, numerical analysis of 3D finite element inductive heat model is generated to investigate disturbance on the temperature field for different kind of defects such as cracks, voids, etc. The temperature variation between defective and non-defective solder balls is monitored for defects identification and classification. Finally, experimental study is carried on the diameter 1mm tiny solder balls by using ECPT and verify the efficacy of the technique.

  2. Three-electrode pulse electron gun with currents up to 250 A

    International Nuclear Information System (INIS)

    Grigor'ev, Yu.V.; Shanturin, L.P.

    1977-01-01

    The design and operating conditions of a pulsed electron gun are described. The electron gun has three electrodes: a cathode, an anode and a control electrode in the form of a grid. The cathode is made from lanthanum hexaboride, which ensures its operation in a low vacuum at a temperature of 1,700 deg C. The control electrode and anode grid are fabricated from sheet tantalum. The anode-grid characteristics of the gun are given. It is shown that at an accelerating voltage of 100 kV, a temperature of 1,700 deg C and a zero control electrode potential the beam current is 250 A

  3. Description of current pulses induced by heavy ions in silicon detectors (II)

    Energy Technology Data Exchange (ETDEWEB)

    Hamrita, H. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette Cedex (France); Parlog, M. [LPC, CNRS/IN2P3, ENSICAEN, Universite de Caen, F-14050 Caen Cedex (France); National Institute for Physics and Nuclear Engineering, RO-76900 Bucharest-Magurele (Romania); Borderie, B., E-mail: borderie@ipno.in2p3.fr [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Lavergne, L. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Le Neindre, N. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); LPC, CNRS/IN2P3, ENSICAEN, Universite de Caen, F-14050 Caen Cedex (France); Rivet, M.F.; Barbey, S. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Bougault, R. [LPC, CNRS/IN2P3, ENSICAEN, Universite de Caen, F-14050 Caen Cedex (France); Chabot, M. [Inst. de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Chbihi, A. [GANIL (DSM-CEA/CNRS/IN2P3), F-14076 Caen Cedex (France); Cussol, D. [LPC, CNRS/IN2P3, ENSICAEN, Univ. de Caen, F-14050 Caen Cedex (France); Oliveira Santos, F. de [GANIL (DSM-CEA/CNRS/IN2P3), F-14076 Caen Cedex (France); Edelbruck, P. [Inst. de Physique Nucleaire, CNRS/IN2P3, Univ. Paris-Sud 11, F-91406 Orsay Cedex (France); Frankland, J.D. [GANIL (DSM-CEA/CNRS/IN2P3), F-14076 Caen Cedex (France); Galichet, E. [Inst. de Physique Nucleaire, CNRS/IN2P3, Univ. Paris-Sud 11, F-91406 Orsay Cedex (France); Conservatoire National des Arts et Metier, F-75141 Paris Cedex 03 (France); Guinet, D.; Lautesse, Ph. [Inst. de Physique Nucleaire, CNRS/IN2P3, Univ.e Claude Bernard Lyon I, F-69622 Villeurbanne Cedex (France); Lopez, O. [LPC, CNRS/IN2P3, ENSICAEN, Univ. de Caen, F-14050 Caen Cedex (France)

    2011-06-21

    Current pulses induced in a silicon detector by 10 different heavy ion species at known energies around 10 A MeV have been sampled in time at high frequency. Their individual average shapes are quite well reproduced by a fit procedure based on our recent charge carrier collection treatment which considers the progressive extraction of the electrons and holes from the high carrier density zone along the ionizing particle track. This region is assumed to present a supplementary dielectric polarization and consequently a disturbed electric field. The influence of the nature of the heavy ion on the values of the three fit parameters is analyzed.

  4. Thermal neutron measurements on electrolytic cells with deuterated palladium cathodes subjected to a pulsed current

    International Nuclear Information System (INIS)

    Granada, J.R.; Mayer, R.E.; Guido, G.; Florido, P.C.; Larreteguy, A.; Gillette, V.H.; Patino, N.E.; Converti, J.; Gomez, S.E.

    1990-01-01

    The present work describes the design of a high efficiency thermal neutron detection system and the measurements performed with it on electrolytic cells containing LiH dissolved in D 2 O with palladium cathodes. A procedure involving the use of a non-stationary (pulsed) current through the cell caused a correlated neutron production to be observed in a repeatable manner. These patterns are strongly dependent on the previous charging history of the cathodes. The technique employed seems to be very useful as a research tool for a systematic study of the different variables governing the phenomenon. (author)

  5. Ir-based refractory superalloys by pulse electric current sintering (PECS) process (II prealloyed powder)

    Science.gov (United States)

    Huang, C.; Yamabe-Mitarai, Y.; Harada, H.

    2002-02-01

    Five prealloyed powder samples prepared from binary Ir-based refractory superalloys were sintered at 1800 °C for 4 h by Pulse Electric Current Sintering (PECS). No metal loss was observed during sintering. The relative densities of the sintered specimens all exceeded 90% T.D. The best one was Ir-13% Hf with the density of 97.82% T.D. Phases detected in sintered samples were in accordance with the phase diagram as expected. Fractured surfaces were observed in two samples (Ir-13% Hf and Ir-15% Zr). Some improvements obtained by using prealloyed powders instead of elemental powders, which were investigated in the previous studies, were presented.

  6. Spectral and temporal characteristics of target current and electromagnetic pulse induced by nanosecond laser ablation

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; De Marco, Massimo; Cikhardt, Jakub; Pfeifer, Miroslav; Velyhan, Andriy; Klír, Daniel; Řezáč, Karel; Limpouch, J.; Krouský, Eduard; Dostál, Jan; Ullschmied, Jiří; Dudžák, Roman

    2017-01-01

    Roč. 59, č. 6 (2017), 1-8, č. článku 065007. ISSN 0741-3335 R&D Projects: GA MŠk EF15_008/0000162; GA ČR GA16-07036S EU Projects: European Commission(XE) 654148 - LASERLAB-EUROPE Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : laser-produced plasma * target current * electromagnetic pulse Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.392, year: 2016

  7. Prospective of Transformation of Current Models of the Global Pharmaceutical Market

    Directory of Open Access Journals (Sweden)

    Yuriy Solodkovskyy

    2012-02-01

    Full Text Available This article thoroughly analyzes the current state of the global pharmaceutical market, defines the key factors for its development and outlines the promising areas of transformation of existing business models of top companies. The forecasted data relating to the market development until 2015 have been investigated. The global, market, technological and organizational factors of transformation of modern model of the global pharmaceutical market have been identified.

  8. Thirty-six pulse rectifier scheme based on zigzag auto-connected transformer

    OpenAIRE

    Xiao-Qiang Chen; Chun-Ling Hao; Hao Qiu; Min Li

    2016-01-01

    In this paper, a low kilo-volt-ampere rating zigzag connected autotransformer based 36-pulse rectifier system supplying vector controlled induction motor drives (VCIMD) is designed, modeled and simulated. Detailed design procedure and magnetic rating calculation of the proposed autotransformer and interphase reactor is studied. Moreover, the design process of the autotransformer is modified to make it suitable for retrofit applications. Simulation results confirm that the proposed 36-pulse re...

  9. Limiting characteristics of the superconducting fault current limiter applied to the neutral line of conventional transformer

    International Nuclear Information System (INIS)

    Im, I.G.; Choi, H.S.; Jung, B.I.

    2013-01-01

    Highlights: •Fault current limiter was used a high-speed interrupter. •High-speed interrupter was operated to bypass to the current limiter line. •The size of the fault current was limited to about 80% after the fault occurred. •The fault current was limited quickly within a half-cycle after the fault occurred. -- Abstract: The increased electricity demands influenced by the recent industrial development make the electric power distribution system more comprehensive, and the risks are high to cause failures to steady state electric line due to the extended range of fault at the time of fault occurrence. Also, the high performance and the high precision electric appliances that sensitive to switching surge and fault current expose vulnerability of reduced life span and increased fault occurrence ratio. Therefore, this thesis analyzed the fault limiting characteristics by the fault types by applying the superconducting fault current limiter to the neutral line of the transformer in order to reduce the fault currents that flow such high performance appliances. A current transformer (CT) that detects the fault current in the simulated power distribution system, a switching control system that is self-developed and a transformer are used in constructing a circuit. When a fault occurs, the initial fault current is restricted by the superconducting fault current limiter and simultaneously detours the fault current by operating the SCR contact of the switching control system through the detection by CT. This thesis analyzed the limiting characteristics of the superconducting fault current limiter that are applied to the neutral line of the transformer by the fault types

  10. Limiting characteristics of the superconducting fault current limiter applied to the neutral line of conventional transformer

    Energy Technology Data Exchange (ETDEWEB)

    Im, I.G., E-mail: asiligo@gmail.com; Choi, H.S., E-mail: hyosang@chosun.ac.kr; Jung, B.I.

    2013-11-15

    Highlights: •Fault current limiter was used a high-speed interrupter. •High-speed interrupter was operated to bypass to the current limiter line. •The size of the fault current was limited to about 80% after the fault occurred. •The fault current was limited quickly within a half-cycle after the fault occurred. -- Abstract: The increased electricity demands influenced by the recent industrial development make the electric power distribution system more comprehensive, and the risks are high to cause failures to steady state electric line due to the extended range of fault at the time of fault occurrence. Also, the high performance and the high precision electric appliances that sensitive to switching surge and fault current expose vulnerability of reduced life span and increased fault occurrence ratio. Therefore, this thesis analyzed the fault limiting characteristics by the fault types by applying the superconducting fault current limiter to the neutral line of the transformer in order to reduce the fault currents that flow such high performance appliances. A current transformer (CT) that detects the fault current in the simulated power distribution system, a switching control system that is self-developed and a transformer are used in constructing a circuit. When a fault occurs, the initial fault current is restricted by the superconducting fault current limiter and simultaneously detours the fault current by operating the SCR contact of the switching control system through the detection by CT. This thesis analyzed the limiting characteristics of the superconducting fault current limiter that are applied to the neutral line of the transformer by the fault types.

  11. A study of direct- and pulse-current chromium electroplating on rotating cylinder electrode (RCE)

    International Nuclear Information System (INIS)

    Chang, J.H.; Hsu, F.Y.; Liao, M.J.; Huang, C.A.

    2007-01-01

    Direct- and pulse-current (DC and PC) chromium electroplating on Cr-Mo steel were performed in a sulfate-catalyzed chromic acid solution at 50 deg. C using a rotating cylinder electrode (RCE). The electroplating cathodic current densities were at 30, 40, 50 and 60 A dm -2 , respectively. The relationship between electroplating current efficiency and the rotating speed of the RCE was studied. The cross-sectional microstructure of Cr-deposit was examined by transmission electron microscope (TEM). Results showed that DC-plating exhibited higher current efficiency than the PC-plating under the same conditions of electroplating current density and the rotating speed. We found the critical rotating speed of RCE used in the chromium electroplating, above this rotating speed the chromium deposition is prohibited. At the same plating current density, the critical rotating speed for DC-plating was higher than that for PC-plating. The higher plating current density is, the larger difference in critical rotating speeds appears between DC- and PC-electroplating. Equiaxed grains, in a nanoscale size with lower dislocation density, nucleate on the cathodic surface in both DC- and PC-electroplating. Adjacent to the equiaxed grains, textured grains were found in other portion of chromium deposit. Fine columnar grains were observed in the DC-electroplated deposit. On the other hand, very long slender grains with high degree of preferred orientation were detected in PC-electroplated deposit

  12. Effect of pulse frequency and current density on anomalous composition and nanomechanical property of electrodeposited Ni-Co films

    Energy Technology Data Exchange (ETDEWEB)

    Chung, C.K., E-mail: ckchung@mail.ncku.edu.t [Department of Mechanical Engineering, and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, Taiwan 701 (China); Chang, W.T. [Department of Mechanical Engineering, and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, Taiwan 701 (China)

    2009-07-01

    Effect of pulse frequency and current density on the anomalous cobalt content and nanomechanical property of the electrodeposited nickel-cobalt (Ni-Co) films has been investigated. The composition, morphology, phase and hardness of the Ni-Co alloy films were examined by scanning electron microscope with an attached energy dispersive X-ray spectroscope, X-ray diffraction and nanoindentation techniques, respectively. The different Co composition of the Ni-Co films codeposited from the fixed sulfamate-chloride bath is subject to the pulse frequencies and current densities. The frequencies varied from 0 to 100 Hz and current densities varied from 1 to 20 ASD (ampere per square decimeter). The Co composition has no significant variation in pulse electrodeposition but it is greatly influenced by current densities from 22.53% at 1 ASD decreased to 13.39% at 20 ASD under DC codeposition. The mean hardness of Ni-Co films has no eminent change at a pulse frequency of 10-100 Hz but it decreases with current densities from 8.72 GPa (1 ASD) to 7.13 GPa (20 ASD). The smoother morphology can be obtained at higher pulse frequency or lower current density. Good Ni-Co films with high hardness and smooth morphology can be obtained by reducing current density and increasing pulse frequency.

  13. A HIGH CURRENT, HIGH VOLTAGE SOLID-STATE PULSE GENERATOR FOR THE NIF PLASMA ELECTRODE POCKELS CELL

    International Nuclear Information System (INIS)

    Arnold, P A; Barbosa, F; Cook, E G; Hickman, B C; Akana, G L; Brooksby, C A

    2007-01-01

    A high current, high voltage, all solid-state pulse modulator has been developed for use in the Plasma Electrode Pockels Cell (PEPC) subsystem in the National Ignition Facility. The MOSFET-switched pulse generator, designed to be a more capable plug-in replacement for the thyratron-switched units currently deployed in NIF, offers unprecedented capabilities including burst-mode operation, pulse width agility and a steady-state pulse repetition frequency exceeding 1 Hz. Capable of delivering requisite fast risetime, 17 kV flattop pulses into a 6 (Omega) load, the pulser employs a modular architecture characteristic of the inductive adder technology, pioneered at LLNL for use in acceleration applications, which keeps primary voltages low (and well within the capabilities of existing FET technology), reduces fabrication costs and is amenable to rapid assembly and quick field repairs

  14. The investigation of a compact auto-connected wire-wrapped pulsed transformer.

    Science.gov (United States)

    Wang, Yuwei; Zhang, Jiande; Chen, Dongqun; Cao, Shengguang; Li, Da; Zhang, Tianyang

    2012-05-01

    For the power conditioning circuit used to deliver power efficiently from flux compression generator (FCG) to the load with high impedance, an air-cored and wire-wrapped transformer convenient in coaxial connection to the other parts is investigated. To reduce the size and enhance the performance, an auto-connection is adopted. A fast and simple model is used to calculate the electrical parameters of the transformer. To evaluate the high voltage capability, the voltages across turns and the electric field distribution in the transformer are investigated. The calculated and the measured electrical parameters of the transformer show good agreements. And the safe operating voltage is predicted to exceed 500 kV. In the preliminary experiments, the transformer is tested in a power conditioning circuit with a capacitive power supply. It is demonstrated that the output voltage of the transformer reaches -342 kV under the input voltage of -81 kV.

  15. Effect of pulse current parameters on the mechanical and corrosion properties of anodized nanoporous aluminum coatings

    International Nuclear Information System (INIS)

    Mohammadi, Iman; Ahmadi, Shahab; Afshar, Abdollah

    2016-01-01

    In this study, the effects of pulse current parameters on corrosion resistance and mechanical properties of anodized coatings were evaluated. Hardness measurements, polarization and electrochemical impedance spectroscopy tests were employed to investigate the mechanical properties and corrosion behavior of these coatings. Also, field emission scanning electron microscopy (FE-SEM) was used to analyze the surface morphology and microstructure of the coatings. It was found that the properties of anodized coatings were dependent on various parameters, among which, time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were optimized. Analysis of Variance (ANOVA) was conducted in order to optimize the results of designed experiments for predicting the hardness of anodic Al_2O_3 coatings. Experimental results showed that the temperature and the interaction of quadratic behavior of minimum current density with frequency and duty cycle were the most important factors influencing the hardness of these coatings. It was indicated that the highest hardness value of 642 HV was attained at the maximum and minimum current densities of 4.4, 1.27 A/dm"2, respectively, a frequency of 82 Hz, procedure time of 27.2 min, duty cycle of 80.2% and the bath temperature of 13.5 °C. In addition, the FE-SEM micrographs showed that the highest density is obtained through the mentioned optimum conditions. Moreover, the electrochemical tests revealed that the highest polarization resistance obtained at optimum conditions was more than 20 times greater than the other samples. - Highlights: • Electrolyte temperature undesirably influences the hardness of anodized coatings. • Maximum hardness of coatings was evaluated by optimization of effective parameters. • The diameter of alumina nanotube considerably affects hardness of anodized coating. • R_P of the sample formed at optimum condition was at least 20 times more than others. • Porosity is the

  16. Effect of pulse current parameters on the mechanical and corrosion properties of anodized nanoporous aluminum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Iman, E-mail: imanmohammadi68@gmail.com; Ahmadi, Shahab; Afshar, Abdollah

    2016-11-01

    In this study, the effects of pulse current parameters on corrosion resistance and mechanical properties of anodized coatings were evaluated. Hardness measurements, polarization and electrochemical impedance spectroscopy tests were employed to investigate the mechanical properties and corrosion behavior of these coatings. Also, field emission scanning electron microscopy (FE-SEM) was used to analyze the surface morphology and microstructure of the coatings. It was found that the properties of anodized coatings were dependent on various parameters, among which, time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were optimized. Analysis of Variance (ANOVA) was conducted in order to optimize the results of designed experiments for predicting the hardness of anodic Al{sub 2}O{sub 3} coatings. Experimental results showed that the temperature and the interaction of quadratic behavior of minimum current density with frequency and duty cycle were the most important factors influencing the hardness of these coatings. It was indicated that the highest hardness value of 642 HV was attained at the maximum and minimum current densities of 4.4, 1.27 A/dm{sup 2}, respectively, a frequency of 82 Hz, procedure time of 27.2 min, duty cycle of 80.2% and the bath temperature of 13.5 °C. In addition, the FE-SEM micrographs showed that the highest density is obtained through the mentioned optimum conditions. Moreover, the electrochemical tests revealed that the highest polarization resistance obtained at optimum conditions was more than 20 times greater than the other samples. - Highlights: • Electrolyte temperature undesirably influences the hardness of anodized coatings. • Maximum hardness of coatings was evaluated by optimization of effective parameters. • The diameter of alumina nanotube considerably affects hardness of anodized coating. • R{sub P} of the sample formed at optimum condition was at least 20 times more than others

  17. Analytical Analysis and Case Study of Transient Behavior of Inrush Current in Power Transformer for Designing of Efficient Circuit Breakers

    Science.gov (United States)

    Harmanpreet, Singh, Sukhwinder; Kumar, Ashok; Kaur, Parneet

    2010-11-01

    Stability & security are main aspects in electrical power systems. Transformer protection is major issue of concern to system operation. There are many mall-trip cases of transformer protection are caused by inrush current problems. The phenomenon of transformer inrush current has been discussed in many papers since 1958. In this paper analytical analysis of inrush current in a transformer switched on dc and ac supply has been done. This analysis will help in design aspects of circuit breakers for better performance.

  18. Forward transformation for high resolution eddy current tomography using whitney elements

    International Nuclear Information System (INIS)

    Szewczyk, R.; Salach, J.; Nowicki, M.; Ruokolainen, J.; Raback, P.

    2014-01-01

    Tomographic methods are intensively developed field of non-destructive testing. The main advantage of this type of NDT method is 3D information concerning the shape of the discontinuities in investigated material. On the other hand, the most common tomography method utilizing X-rays creates the significant risks typical to X-ray technique. As a result, Xray tomography is difficult to use in industry. Introduced to the industry in 2007, the eddy current tomography is safe and cost effective. However, in opposite to X-ray tomography, eddy current tomography requires sophisticated and time consuming inverse transformation creating 2D or 3D view of discontinuities. For this reason solutions presented previously are focused on 2D inverse transformation and exhibit limited resolution. For eddy current tomography, the forward tomographic transformation is most important, which is the base of inverse transformation. This paper presents the novel, fast and cost-effective solution utilizing Whitney elements method for such forward transformation. As a result, new possibilities of development in the area of high resolution 3D eddy current tomography are created. (authors)

  19. Silicone Substrate with Collagen and Carbon Nanotubes Exposed to Pulsed Current for MSC Osteodifferentiation

    Directory of Open Access Journals (Sweden)

    Daniyal Jamal

    2017-01-01

    Full Text Available Autologous human adipose tissue-derived mesenchymal stem cells (MSCs have the potential for clinical translation through their induction into osteoblasts for regeneration. Bone healing can be driven by biophysical stimulation using electricity for activating quiescent adult stem cells. It is hypothesized that application of electric current will enhance their osteogenic differentiation, and addition of conductive carbon nanotubes (CNTs to the cell substrate will provide increased efficiency in current transmission. Cultured MSCs were seeded and grown onto fabricated silicone-based composites containing collagen and CNT fibers. Chemical inducers, namely, glycerol phosphate, dexamethasone, and vitamin C, were then added to the medium, and pulsatile submilliampere electrical currents (about half mA for 5 cycles at 4 mHz, twice a week were applied for two weeks. Calcium deposition indicative of MSC differentiation and osteoblastic activity was quantified through Alizarin Red S and spectroscopy. It was found that pulsed current significantly increased osteodifferentiation on silicone-collagen films without CNTs. Under no external current, the presence of 10% (m/m CNTs led to a significant and almost triple upregulation of calcium deposition. Both CNTs and current parameters did not appear to be synergistic. These conditions of enhanced osteoblastic activities may further be explored ultimately towards future therapeutic use of MSCs.

  20. Dynamic response of thermal neutron measurements in electrochemically produced cold fusion subject to pulsed current

    International Nuclear Information System (INIS)

    Granada, Jose; Converti, Jose; Mayer, Roberto; Guido, German; Florido, Pablo; Patino, Nestor; Sobehart, Leonardo; Gomez, Silvia; Larreteguy, Axel

    1988-01-01

    The present work shows the results of measurements performed on electrolytic cells using a high efficiency (22%) neutron detection system in combination with a procedure involving a non-stationary current through the cell's circuit. Cold fusion was produced in electrolytic cells containing LiH dissolved in heavy water with a palladium cathode. The dynamic response to low frequency current pulses was measured. Characteristic patterns showing one or two bumps were obtained in a repeatable fashion. These patterns are strongly dependent on the previous charging history of the cathode. The technique employed seems to be very convenient as a research tool for a systematic study of the different variables governing the phenomenon. (Author)

  1. Design of a Shielded Reflection Type Pulsed Eddy Current Probe for the Evaluation of Thickness

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Kil; Choi, Dong Myung [Kunsan National University, Gunsan (Korea, Republic of)

    2007-10-15

    For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation

  2. A new high current laboratory and pulsed homopolar generator power supply at the University of Texas

    Science.gov (United States)

    Floyd, J. E.; Aanstoos, T. A.

    1984-03-01

    The University of Texas at Austin is constructing a facility for research in pulse power technology for the Center for Electromechanics at the Balcones Research Center. The facility, designed to support high-current experiments, will be powered by six homopolar generators, each rated at 10 MJ and arranged to allow matching the requirements of resistive and inductive loads at various voltage and current combinations. Topics covered include the high bay, the power supply configuration and parameters, the speed and field control, and the magnetic circuit. Also considered are the removable air-cooled brushes, the water-cooled field coils, the hydraulic motor sizing and direct coupling, the low-impedance removable field coils, and the hydrostatic bearing design.

  3. The interaction of pulsed eddy current with metal surface crack for various coils

    International Nuclear Information System (INIS)

    Yang, H.-C.; Tai, C.-C.

    2002-01-01

    We study the interaction of pulsed eddy current (PEC) with metal surface cracks using various coils that have different geometric sizes. In the previous work, we have showed that the PEC technique can be used to inspect electrical-discharge-machined (EDM) notches with depth from 0.5 mm to 9 mm. The results showed that the relationship between PEC signals and crack depth is obvious. In this work, we further try a series of coils with different radii, heights, turns and shapes. We will discuss the effects of these coil parameters on the PEC signal. Some other critical problems of PEC measurements such as signal drift that caused by heating effect of coil currents will be studied. We also show more experiments on fatigue cracks to demonstrate the capability of PEC technique for cracks inspection

  4. Characterization of manganese dioxide electrodeposited by pulse and direct current for electrochemical capacitor

    International Nuclear Information System (INIS)

    Adelkhani, H.; Ghaemi, M.

    2010-01-01

    This paper describes the electrochemical capacitor behavior of manganese dioxide (MD, MnO 2 ) samples that were prepared by direct current (DCMD) and pulse current (PCMD) electrodeposition. The capacitive characteristics of the samples were studied in 0.5 M aqueous Na 2 SO 4 solution using the cyclic voltammetry (CV) method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), chemical composition analyses and the Barrett-Joyner-Halenda (BJH) method were employed to characterize the samples. In the study of the effect of scan rate on capacitance, it was revealed that PCMD displayed higher capacities than DCMD for all scan rates. The higher capacitive performance of PCMD was attributed to its porosity (specific surface area, pore volume, and pore-size distribution), chemical composition and structural properties.

  5. Electromagnetic characterization of current transformer with toroidal core under sinusoidal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Koprivica, Branko, E-mail: branko.koprivica@ftn.kg.ac.rs; Milovanovic, Alenka, E-mail: alenka.milovanovic@ftn.kg.ac.rs

    2016-04-01

    The aim of this paper is to present a new procedure for the electromagnetic analysis of a measuring current transformer under sinusoidal conditions in its electrical and magnetic circuit. The influence of the magnetic hysteresis has been taken into account using the measured inverse magnetization curve and phase lag between the time waveforms of the magnetic field and the magnetic induction. Using the proposed analysis, ratio and phase errors of the current transformer have been calculated. The results of the calculation have been compared with experimental results and a good agreement has been found.

  6. Leakage current analysis of single-phase transformer-less grid-connected PV inverters

    DEFF Research Database (Denmark)

    Ma, Lin; Kerekes, Tamas; Teodorescu, Remus

    2016-01-01

    Transformer-less string PV inverter is getting more and more widely utilized due to its higher efficiency, smaller volume and weight. However, without the galvanic isolation, the leakage current limitation and operation safety became the key issues of transformer-less inverters. This paper...... simplifies the leakage current generation circuit model and presents a leakage current estimation method both in real time and frequency domain. It shows that the leakage current is related to the circuit stray parameters, output filter and common mode voltage. Furthermore, with the proposed analysis method......, the leakage current generation of H-bridge with different modulation methods and HERIC inverter are discussed individually. At last, the presented method has been verified via simulation....

  7. Digital Signal Processing and Generation for a DC Current Transformer for Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Zorzetti, Silvia [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-01-01

    The thesis topic, digital signal processing and generation for a DC current transformer, focuses on the most fundamental beam diagnostics in the field of particle accelerators, the measurement of the beam intensity, or beam current. The technology of a DC current transformer (DCCT) is well known, and used in many areas, including particle accelerator beam instrumentation, as non-invasive (shunt-free) method to monitor the DC current in a conducting wire, or in our case, the current of charged particles travelling inside an evacuated metal pipe. So far, custom and commercial DCCTs are entirely based on analog technologies and signal processing, which makes them inflexible, sensitive to component aging, and difficult to maintain and calibrate.

  8. Low-noise pulse-mode current power supply for magnetic field measurements of magnets for accelerators

    International Nuclear Information System (INIS)

    Omel'yanenko, M.M.; Borisov, V.V.; Donyagin, A.M.; Kostromin, S.A.; Makarov, A.A.; Khodzhibagiyan, G.G.; Shemchuk, A.V.

    2017-01-01

    The described pulse-mode current power supply has been designed and fabricated for the magnetic field measurement system of superconducting magnets for accelerators. The power supply is based on a current regulator with pass transistor bank in linear mode. The output current pulses (0-100 A) are produced by using the energy of preliminary charged capacitor bank (5-40 V), which is charged additionally after each pulse. There is no AC-line frequency and harmonics ripple in the output current, the relative noise level is less than -100 dB (or 10 -5 ) of RMS value (it is defined as the ratio of output RMS noise current to the maximal output current 100 A within the operating bandwidth, expressed in dB).

  9. Effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded high strength aluminium alloy

    International Nuclear Information System (INIS)

    Balasubramanian, V.; Ravisankar, V.; Reddy, G. Madhusudhan

    2007-01-01

    This paper reveals the effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded AA7075 aluminium alloy. This alloy has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. As welded joint strength is much lower than the base metal strength and hence, a simple aging treatment has been given to improve the tensile strength of the joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Post weld aging treatment is accompanied by an increase in tensile strength and tensile ductility

  10. Suppression of vertical instability in elongated current-carrying plasmas by applying stellarator rotational transform

    International Nuclear Information System (INIS)

    ArchMiller, M. C.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Knowlton, S. F.; Ma, X.; Maurer, D. A.; Pandya, M. D.; Traverso, P.

    2014-01-01

    The passive stability of vertically elongated current-carrying toroidal plasmas has been investigated in the Compact Toroidal Hybrid, a stellarator/tokamak hybrid device. In this experiment, the fractional transform f, defined as the ratio of the imposed external rotational transform from stellarator coils to the total rotational transform, was varied from 0.04 to 0.50, and the elongation κ was varied from 1.4 to 2.2. Plasmas that were vertically unstable were evidenced by motion of the plasma in the vertical direction. Vertical drifts are measured with a set of poloidal field pickup coils. A three chord horizontally viewing interferometer and a soft X-ray diode array confirmed the drifts. Plasmas with low fractional transform and high elongation are the most susceptible to vertical instability, consistent with analytic predictions that the vertical mode in elongated plasmas can be stabilized by the poloidal field of a relatively weak stellarator equilibrium

  11. A novel algorithm for discrimination between inrush current and internal faults in power transformer differential protection based on discrete wavelet transform

    Energy Technology Data Exchange (ETDEWEB)

    Eldin, A.A. Hossam; Refaey, M.A. [Electrical Engineering Department, Alexandria University, Alexandria (Egypt)

    2011-01-15

    This paper proposes a novel methodology for transformer differential protection, based on wave shape recognition of the discriminating criterion extracted of the instantaneous differential currents. Discrete wavelet transform has been applied to the differential currents due to internal fault and inrush currents. The diagnosis criterion is based on median absolute deviation (MAD) of wavelet coefficients over a specified frequency band. The proposed algorithm is examined using various simulated inrush and internal fault current cases on a power transformer that has been modeled using electromagnetic transients program EMTDC software. Results of evaluation study show that, proposed wavelet based differential protection scheme can discriminate internal faults from inrush currents. (author)

  12. Exponential current pulse generation for efficient very high-impedance multisite stimulation.

    Science.gov (United States)

    Ethier, S; Sawan, M

    2011-02-01

    We describe in this paper an intracortical current-pulse generator for high-impedance microstimulation. This dual-chip system features a stimuli generator and a high-voltage electrode driver. The stimuli generator produces flexible rising exponential pulses in addition to standard rectangular stimuli. This novel stimulation waveform is expected to provide superior energy efficiency for action potential triggering while releasing less toxic reduced ions in the cortical tissues. The proposed fully integrated electrode driver is used as the output stage where high-voltage supplies are generated on-chip to significantly increase the voltage compliance for stimulation through high-impedance electrode-tissue interfaces. The stimuli generator has been implemented in 0.18-μm CMOS technology while a 0.8-μm CMOS/DMOS process has been used to integrate the high-voltage output stage. Experimental results show that the rectangular pulses cover a range of 1.6 to 167.2 μA with a DNL and an INL of 0.098 and 0.163 least-significant bit, respectively. The maximal dynamic range of the generated exponential reaches 34.36 dB at full scale within an error of ± 0.5 dB while all of its parameters (amplitude, duration, and time constant) are independently programmable over wide ranges. This chip consumes a maximum of 88.3 μ W in the exponential mode. High-voltage supplies of 8.95 and -8.46 V are generated by the output stage, boosting the voltage swing up to 13.6 V for a load as high as 100 kΩ.

  13. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bo, E-mail: gaob@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Hu, Liang [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Li, Shi-wei [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Hao, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Yu-dong [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France); Tu, Gan-feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Grosdidier, Thierry [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France)

    2015-08-15

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1){sub Al}//(0 0 1){sub Si} with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys.

  14. Simulation of transformations of thin metal films heated by nanosecond laser pulses

    Science.gov (United States)

    Balandin, V. Yu.; Niedrig, R.; Bostanjoglo, O.

    1995-01-01

    The ablation of free-standing thin aluminum films by a nanosecond laser pulse was investigated by time-resolved transmission electron microscopy and numerical simulation. It was established that thin film geometry is particularly suited to furnish information on the mechanism of evaporation and the surface tension of the melt. In the case of aluminum the surface tension sigma as function of temperature can be approximated by two linear sections with a coefficient -0.3 x 10(exp -3) N/K m from the melting point 933 K up to 3000 K and -0.02 x 10(exp -3) N/K m above 3000 K, respectively, with sigma(993 K) = 0.9 N/m and sigma(8500 K) = 0. At lower pulse energies the films disintegrated predominantly by thermocapillary flow. Higher pulse energies produced volume evaporation, and a nonmonotonous flow, explained by recoil from evaporating atoms and thermocapillarity. The familiar equations of energy and motion, which presuppose separate and coherent vapor and liquid phases, were not adequate to describe the ablation of the hottest zone. Surface evaporation seemed to be marginal at all laser pulse energies used.

  15. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sung Hun [Dept. of Electrical Engineering, Soongsil University, Seoul (Korea, Republic of); Han, Tae Hee [Dept. of Aero Materials Engineering, Jungwon University, Goesan (Korea, Republic of)

    2017-06-15

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

  16. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    International Nuclear Information System (INIS)

    Lim, Sung Hun; Han, Tae Hee

    2017-01-01

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding

  17. Hot Deformation Behavior and Pulse Current Auxiliary Isothermal Forging of Hot Pressing Sintering TiAl Based Alloys.

    Science.gov (United States)

    Shi, Chengcheng; Jiang, Shaosong; Zhang, Kaifeng

    2017-12-16

    This paper focuses on the fabrication of as-forged Ti46.5Al2Cr1.8Nb-(W, B) alloy via pulse current auxiliary isothermal forging (PCIF). The starting material composed of near gamma (NG) microstructure was fabricated by adopting pre-alloyed powders via hot pressing sintering (HPS) at 1300 °C. Isothermal compression tests were conducted at a strain rate range of 0.001-0.1 s -1 and a temperature range of 1125-1275 °C to establish the constitutive model and processing map. The optimal hot deformation parameters were successfully determined (in a strain rate range of 10 -3 -2.5 × 10 -3 s -1 and temperature range of 1130-1180 °C) based on the hot processing map and microstructure observation. Accordingly, an as-forged TiAl based alloy without cracks was successfully fabricated by PCIF processing at 1175 °C with a nominal strain rate of 10 -3 s -1 . Microstructure observation indicated that complete dynamic recrystallization (DRX) and phase transformation of γ→α₂ occurred during the PCIF process. The elongation of as-forged alloy was 136%, possessing a good secondary hot workability, while the sintered alloy was only 66% when tested at 900 °C with a strain rate of 2 × 10 -4 s -1 .

  18. Stability of high current diode under 100-nanosecond-pulse voltage

    International Nuclear Information System (INIS)

    Lai Dingguo; Qiu Aici; Zhang Yongmin; Huang Jianjun; Ren Shuqing; Yang Li

    2012-01-01

    Stability of high current diode under pulse voltage with 80 ns and 34 ns rise time was studied on the flash Ⅱ accelerator. Influence of rise time of diode voltage on startup time and cathode emission uniformity and repeatability of diode impedance was analyzed by comparing the experimental results with numerically simulated results, and the influence mechanism was discussed. The startup time of diode increases with the increasing of rise time of voltage, and the repeatability of diode impedance decreases. Discal plane cathode is prone to emit rays intensely in the center area, the time that plasma covers the surface of the cathode increases and the shielding effect has more impact on cathode emission according to the increase of rise time. Local intense emission on the cathode increases expansion speed of plasma and reduces the effective emission area. The stability of characteristic impedance of diode under a pulse voltage with slow rise time is decreased by the combined action of expansion speed of plasma and the effective emission area. (authors)

  19. Pulsed Current-Voltage-Induced Perturbations of a Premixed Propane/Air Flame

    Directory of Open Access Journals (Sweden)

    Jacob. B. Schmidt

    2011-01-01

    Full Text Available The effect of millisecond wide sub-breakdown pulsed voltage-current induced flow perturbation has been measured in premixed laminar atmospheric pressure propane/air flame. The flame equivalence ratios were varied from 0.8 to 1.2 with the flow speeds near 1.1 meter/second. Spatio-temporal flame structure changes were observed through collection of CH (A-X and OH (A-X chemiluminescence and simultaneous spontaneous Raman scattering from N2. This optical collection scheme allows us to obtain a strong correlation between the measured gas temperature and the chemiluminescence intensity, verifying that chemiluminescence images provide accurate measurements of flame reaction zone structure modifications. The experimental results suggest that the flame perturbation is caused by ionic wind originating only from the radial positive space-charge distribution in/near the cathode fall. A net momentum transfer acts along the annular space discharge distribution in the reaction zone at or near the cathode fall which modifies the flow field near the cathodic burner head. This radially inward directed body force appears to enhance mixing similar to a swirl induced modification of the flame structure. The flame fluidic response exhibit a strong dependence on the voltage pulse width ≤10 millisecond.

  20. High rate deposition of thin film cadmium sulphide by pulsed direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Lisco, F., E-mail: F.Lisco@lboro.ac.uk [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Kaminski, P.M.; Abbas, A.; Bowers, J.W.; Claudio, G. [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Losurdo, M. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona 4, 70126 Bari (Italy); Walls, J.M. [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2015-01-01

    Cadmium Sulphide (CdS) is an important n-type semiconductor widely used as a window layer in thin film photovoltaics Copper Indium Selenide, Copper Indium Gallium (di)Selenide, Copper Zinc Tin Sulphide and Cadmium Telluride (CdTe). Cadmium Sulphide has been deposited using a number of techniques but these techniques can be slow (chemical bath deposition and Radio Frequency sputtering) or the uniformity and the control of thickness can be relatively difficult (close space sublimation). In this paper we report on the development of a process using pulsed Direct Current magnetron sputtering which allows nanometre control of thin film thickness using time only. The CdS thin films deposited in this process are highly uniform and smooth. They exhibit the preferred hexagonal structure at room temperature deposition and they have excellent optical properties. Importantly, the process is highly stable despite the use of a semi-insulating magnetron target. Moreover, the process is very fast. The deposition rate using 1.5 kW of power to a 6-inch circular magnetron was measured to be greater than 8 nm/s. This makes the process suitable for industrial deployment. - Highlights: • Pulsed DC magnetron sputtering of CdS • High deposition rate deposition • Uniform, pinhole free films.

  1. Study on Nanostructures Induced by High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2012-01-01

    Full Text Available Four techniques using high-current pulsed electron beam (HCPEB were proposed to obtain surface nanostructure of metal and alloys. The first method involves the distribution of several fine Mg nanoparticles on the top surface of treated samples by evaporation of pure Mg with low boiling point. The second technique uses superfast heating, melting, and cooling induced by HCPEB irradiation to refine the primary phase or the second phase in alloys to nanosized uniform distributed phases in the matrix, such as the quasicrystal phase Mg30Zn60Y10 in the quasicrystal alloy Mg67Zn30Y3. The third technique involves the refinement of eutectic silicon phase in hypereutectic Al-15Si alloys to fine particles with the size of several nanometers through solid solution and precipitation refinement. Finally, in the deformation zone induced by HCPEB irradiation, the grain size can be refined to several hundred nanometers, such as the grain size of the hypereutectic Al-15Si alloys in the deformation zone, which can reach ~400 nm after HCPEB treatment for 25 pulses. Therefore, HCPEB technology is an efficient way to obtain surface nanostructure.

  2. Influence of current pulse shape on directly modulated system performance in metro area optical networks

    Science.gov (United States)

    Campos, Carmina del Rio; Horche, Paloma R.; Martin-Minguez, Alfredo

    2011-03-01

    Due to the fact that a metro network market is very cost sensitive, direct modulated schemes appear attractive. In this paper a CWDM (Coarse Wavelength Division Multiplexing) system is studied in detail by means of an Optical Communication System Design Software; a detailed study of the modulated current shape (exponential, sine and gaussian) for 2.5 Gb/s CWDM Metropolitan Area Networks is performed to evaluate its tolerance to linear impairments such as signal-to-noise-ratio degradation and dispersion. Point-to-point links are investigated and optimum design parameters are obtained. Through extensive sets of simulation results, it is shown that some of these shape pulses are more tolerant to dispersion when compared with conventional gaussian shape pulses. In order to achieve a low Bit Error Rate (BER), different types of optical transmitters are considered including strongly adiabatic and transient chirp dominated Directly Modulated Lasers (DMLs). We have used fibers with different dispersion characteristics, showing that the system performance depends, strongly, on the chosen DML-fiber couple.

  3. High rate deposition of thin film cadmium sulphide by pulsed direct current magnetron sputtering

    International Nuclear Information System (INIS)

    Lisco, F.; Kaminski, P.M.; Abbas, A.; Bowers, J.W.; Claudio, G.; Losurdo, M.; Walls, J.M.

    2015-01-01

    Cadmium Sulphide (CdS) is an important n-type semiconductor widely used as a window layer in thin film photovoltaics Copper Indium Selenide, Copper Indium Gallium (di)Selenide, Copper Zinc Tin Sulphide and Cadmium Telluride (CdTe). Cadmium Sulphide has been deposited using a number of techniques but these techniques can be slow (chemical bath deposition and Radio Frequency sputtering) or the uniformity and the control of thickness can be relatively difficult (close space sublimation). In this paper we report on the development of a process using pulsed Direct Current magnetron sputtering which allows nanometre control of thin film thickness using time only. The CdS thin films deposited in this process are highly uniform and smooth. They exhibit the preferred hexagonal structure at room temperature deposition and they have excellent optical properties. Importantly, the process is highly stable despite the use of a semi-insulating magnetron target. Moreover, the process is very fast. The deposition rate using 1.5 kW of power to a 6-inch circular magnetron was measured to be greater than 8 nm/s. This makes the process suitable for industrial deployment. - Highlights: • Pulsed DC magnetron sputtering of CdS • High deposition rate deposition • Uniform, pinhole free films

  4. Operation of the DC current transformer intensity monitors at FNAL during run II

    Energy Technology Data Exchange (ETDEWEB)

    Crisp, J.; Fellenz, B.; Heikkinen, D.; Ibrahim, M.A.; Meyer, T.; Vogel, G.; /Fermilab

    2012-01-01

    Circulating beam intensity measurements at FNAL are provided by five DC current transformers (DCCT), one per machine. With the exception of the DCCT in the Recycler, all DCCT systems were designed and built at FNAL. This paper presents an overview of both DCCT systems, including the sensor, the electronics, and the front-end instrumentation software, as well as their performance during Run II.

  5. Characterization of an electrochemical mercury sensor using alternating current, cyclic, square wave and differential pulse voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Guerreiro, Gabriela V.; Zaitouna, Anita J.; Lai, Rebecca Y., E-mail: rlai2@unl.edu

    2014-01-31

    Graphical abstract: -- Highlights: •An electrochemical Hg(II) sensor based on T–Hg(II)–T sensing motif was fabricated. •A methylene blue-modified DNA probe was used to fabricate the sensor. •Sensor performance was evaluated using ACV, CV, SWV, and DPV. •The sensor behaves as a “signal-off” sensor in ACV and CV. •The sensor behaves as either a “signal-on” or “signal-off” sensor in SWV and DPV. -- Abstract: Here we report the characterization of an electrochemical mercury (Hg{sup 2+}) sensor constructed with a methylene blue (MB)-modified and thymine-containing linear DNA probe. Similar to the linear probe electrochemical DNA sensor, the resultant sensor behaved as a “signal-off” sensor in alternating current voltammetry and cyclic voltammetry. However, depending on the applied frequency or pulse width, the sensor can behave as either a “signal-off” or “signal-on” sensor in square wave voltammetry (SWV) and differential pulse voltammetry (DPV). In SWV, the sensor showed “signal-on” behavior at low frequencies and “signal-off” behavior at high frequencies. In DPV, the sensor showed “signal-off” behavior at short pulse widths and “signal-on” behavior at long pulse widths. Independent of the sensor interrogation technique, the limit of detection was found to be 10 nM, with a linear dynamic range between 10 nM and 500 nM. In addition, the sensor responded to Hg{sup 2+} rather rapidly; majority of the signal change occurred in <20 min. Overall, the sensor retains all the characteristics of this class of sensors; it is reagentless, reusable, sensitive, specific and selective. This study also highlights the feasibility of using a MB-modified probe for real-time sensing of Hg{sup 2+}, which has not been previously reported. More importantly, the observed “switching” behavior in SWV and DPV is potentially generalizable and should be applicable to most sensors in this class of dynamics-based electrochemical biosensors.

  6. Research of Measurement Circuits for High Voltage Current Transformer Based on Rogowski Coils

    Directory of Open Access Journals (Sweden)

    Yan Bing

    2014-02-01

    Full Text Available The electronic current transformer plays an irreplaceable position in the field of relay protection and current measurement of the power system. Rogowski coils are used as sensor parts, and in order to improve the measurement accuracy and reliability, the circuits at the high voltage system are introduced and improved in this paper, including the analog integral element, the filtering circuit and the phase shift circuit. Simulations results proved the reliability and accuracy of the improved circuits.

  7. A 1–2 GHz high linearity transformer-feedback power-to-current LNA

    NARCIS (Netherlands)

    Li, X.; Serdijn, W.A.; Woestenburg, B.E.M.; Bij de Vaate, J.G.

    2009-01-01

    This paper demonstrates that a double-loop transformer-feedback power-to-current low noise amplifier, to be implemented in a 0.2 lm GaAs p-HEMT IC process, is able to obtain a noise figure less than 0.8 dB, an input return loss less than -12 dB, a flat voltage-to-current signal transfer of 180 mS,

  8. Production of transform-limited X-ray pulses through self-seeding at the European X-ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-09-15

    An important goal for any advanced X-ray FEL is an option for providing Fourier-limited X-ray pulses. In this way, no monochromator is needed in the experimental hall. Self-seeding is a promising approach to significantly narrow the SASE bandwidth to produce nearly transform-limited pulses. These are important for many experiments including 3D diffraction imaging.We discuss the implementation of a single-crystal self-seeding scheme in the hard X-ray lines of the European XFEL. For this facility, transform-limited pulses are particularly valuable since they naturally support the extraction of more FEL power than at saturation by exploiting tapering in the tunable-gap baseline undulators. Tapering consists of a stepwise change of the undulator gap from segment to segment. Based on start-to-end simulations dealing with the up-to-date parameters of the European XFEL, we show that the FEL power reaches about 400 GW, or one order of magnitude higher power than the SASE saturation level (20 GW). This analysis indicates that our self-seeding scheme is not significantly affected by non-ideal electron phase-space distribution, and yields about the same performance as in the case for an electron beam with ideal parameters. The self-seeding scheme with a single crystal monochromator is extremely compact (about 5 m long), and cost estimations are low enough to consider adding it to the European XFEL capabilities from the very beginning of the operation phase. (orig.)

  9. Production of transform-limited X-ray pulses through self-seeding at the European X-ray FEL

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-09-01

    An important goal for any advanced X-ray FEL is an option for providing Fourier-limited X-ray pulses. In this way, no monochromator is needed in the experimental hall. Self-seeding is a promising approach to significantly narrow the SASE bandwidth to produce nearly transform-limited pulses. These are important for many experiments including 3D diffraction imaging.We discuss the implementation of a single-crystal self-seeding scheme in the hard X-ray lines of the European XFEL. For this facility, transform-limited pulses are particularly valuable since they naturally support the extraction of more FEL power than at saturation by exploiting tapering in the tunable-gap baseline undulators. Tapering consists of a stepwise change of the undulator gap from segment to segment. Based on start-to-end simulations dealing with the up-to-date parameters of the European XFEL, we show that the FEL power reaches about 400 GW, or one order of magnitude higher power than the SASE saturation level (20 GW). This analysis indicates that our self-seeding scheme is not significantly affected by non-ideal electron phase-space distribution, and yields about the same performance as in the case for an electron beam with ideal parameters. The self-seeding scheme with a single crystal monochromator is extremely compact (about 5 m long), and cost estimations are low enough to consider adding it to the European XFEL capabilities from the very beginning of the operation phase. (orig.)

  10. High Current Planar Transformer for Very High Efficiency Isolated Boost DC-DC Converters

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2014-01-01

    This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac-resistance a......This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac......-resistance and transformer leakage inductance. Design and optimization procedures are validated based on an experimental prototype of a 6 kW dcdc isolated full bridge boost converter developed on fully planar magnetics. The prototype is rated at 30-80 V 0-80 A on the low voltage side and 700-800 V on the high voltage side...... with a peak efficiency of 97.8% at 80 V 3.5 kW. Results highlights that thick copper windings can provide good performance at low switching frequencies due to the high transformer filling factor. PCB windings can also provide very high efficiency if stacked in parallel utilizing the transformer winding window...

  11. Nondestructive examination of irradiated fuel rods by pulsed eddy current techniques

    International Nuclear Information System (INIS)

    Francis, W.C.; Quapp, W.J.; Martin, M.R.; Gibson, G.W.

    1976-02-01

    A number of fuel rods and unfueled zircaloy cladding tubes which had been irradiated in the Saxton reactor have undergone extensive nondestructive and corroborative destructive examinations by Aerojet Nuclear Company as part of the Water Reactor Safety Research Program, Irradiation Effects Test Series. This report discusses the pulsed eddy current (PEC) nondestructive examinations on the fuel rods and tubing and the metallography results on two fuel rods and one irradiated zircaloy tube. The PEC equipment, designed jointly by Argonne National Laboratory and Aerojet, performed very satisfactorily the functions of diameter, profile, and wall thickness measurements and OD and ID surface defect detection. The destructive examination provided reasonably good confirmation of ''defects'' detected in the nondestructive examination

  12. Quantitative Evaluation of Defect in Stainless Steel 304 Tube Using Pulsed Eddy Current Technique

    International Nuclear Information System (INIS)

    Nurul Ain Ahmad Latif; Ilham Mukriz Zainal Abidin; Nurul Ain Ahmad Latif; Nordin Jamaludin; Zaredah Hashim; Norhayati Ramli

    2016-01-01

    Pulsed eddy current (PEC) is an advanced non-destructive testing (NDT) technique that operates based on electromagnetic principle. The excitation consists of broad frequency spectrum leading to be a potential in detecting defects that are deeply buried inside the specimen. In this paper, the experiment and simulation were conducted on stainless steel plate 304 fabricated with open surface defects having a different defect depth as an investigation towards the correlation between extracted signal feature and defect depth. Two common features; time to peak and peak value that corresponds to the location depth of defect and size of defect were used for signals analysis and evaluation. The results that acquired through finite element method (FEM) simulation were compared with experimental results for the signals evaluation and defect quantification. (author)

  13. Transverse emittance measurement of high-current single pulse beams using pepper-pot method

    International Nuclear Information System (INIS)

    Ke Jianlin; Zhou Changgeng; Qiu Rui

    2013-01-01

    A pepper pot-imaging plate system has been developed and used to measure the 4-D transverse emittance of a vacuum arc ion source. Single beam pulses of tens to hundreds milliamperes were extracted from the plasma with 64 kV high voltage. An imaging plate was laid after the pepper pot to visualize the ion beamlets passing though the holes on the pepper pot. An application program was developed to show the phase-space distribution and calculate the ellipse and RMS emittances. The normalized RMS emittances are about 6.41 π·mm·mrad in x-direction and 4.61 π·mm·mrad in y-direction. It is shown that the emittance of the vacuum arc ion source is much larger than that of other types of ion sources, which is mainly attributed to the high current and the convex meniscus of this source. (authors)

  14. Increase in operation safety of high-current pulsed accelerators by means of nonlinear resistances

    International Nuclear Information System (INIS)

    Demidov, B.A.; Ivkin, M.V.; Petrov, V.A.; Fanchenko, S.D.

    1975-01-01

    A circuit for connecting a shaping line through a nonlinear resistor in a high-current pulsed accelerator is proposed and investigated experimentally. For experimental purposes standard resistors are used as nonlinear resistors, they are made in the form of cylinders 100 mm in dia and 60 mm long. The results obtained show that if two resistors are connected in series, the reduction in an initial potential is less than 5% at the logarithmic damping coefficient equal to 1.3. It is also shown that such a method allows elimination of the reverse pumpover of energy to the storage device for untimely actuation of a spark gap that results in the prolongation of the time of potential applying thereby it permits a substantial increase in the reliability of a high-voltage insulation [ru

  15. Spatial-time-state fusion algorithm for defect detection through eddy current pulsed thermography

    Science.gov (United States)

    Xiao, Xiang; Gao, Bin; Woo, Wai Lok; Tian, Gui Yun; Xiao, Xiao Ting

    2018-05-01

    Eddy Current Pulsed Thermography (ECPT) has received extensive attention due to its high sensitive of detectability on surface and subsurface cracks. However, it remains as a difficult challenge in unsupervised detection as to identify defects without knowing any prior knowledge. This paper presents a spatial-time-state features fusion algorithm to obtain fully profile of the defects by directional scanning. The proposed method is intended to conduct features extraction by using independent component analysis (ICA) and automatic features selection embedding genetic algorithm. Finally, the optimal feature of each step is fused to obtain defects reconstruction by applying common orthogonal basis extraction (COBE) method. Experiments have been conducted to validate the study and verify the efficacy of the proposed method on blind defect detection.

  16. Model-Based Prediction of Pulsed Eddy Current Testing Signals from Stratified Conductive Structures

    International Nuclear Information System (INIS)

    Zhang, Jian Hai; Song, Sung Jin; Kim, Woong Ji; Kim, Hak Joon; Chung, Jong Duk

    2011-01-01

    Excitation and propagation of electromagnetic field of a cylindrical coil above an arbitrary number of conductive plates for pulsed eddy current testing(PECT) are very complex problems due to their complicated physical properties. In this paper, analytical modeling of PECT is established by Fourier series based on truncated region eigenfunction expansion(TREE) method for a single air-cored coil above stratified conductive structures(SCS) to investigate their integrity. From the presented expression of PECT, the coil impedance due to SCS is calculated based on analytical approach using the generalized reflection coefficient in series form. Then the multilayered structures manufactured by non-ferromagnetic (STS301L) and ferromagnetic materials (SS400) are investigated by the developed PECT model. Good prediction of analytical model of PECT not only contributes to the development of an efficient solver but also can be applied to optimize the conditions of experimental setup in PECT

  17. Development and contribution of rf heating and current drive systems to long pulse, high performance experiments in JT-60U

    International Nuclear Information System (INIS)

    Moriyama, Shinichi; Seki, Masami; Terakado, Masayuki; Shimono, Mitsugu; Ide, Shunsuke; Isayama, Akihiko; Suzuki, Takahiro; Fujii, Tsuneyuki

    2005-01-01

    To contribute to high performance long pulse (∼65 s) experiments in JT-60U, the target of the electron cyclotron (EC) operation in long pulse is 0.6 MW for 30 s with four gyrotrons, though 10 MJ (2.8 MW and 3.6 s) was achieved in high power operation before 2003. One of the critical issues for the long pulse operation is detuning due to decay in beam current of the gyrotron. This decay comes from the cathode cooling by continuous electron emission. As a countermeasure for this issue, active adjustments for the heater current and anode voltage during the pulse have successfully extended the duration of a good oscillation condition for the gyrotron. As a result, 0.4 MW for 16 s with one gyrotron to the dummy load and for 8.7 s to the plasma have been achieved up to now

  18. Transient current changes induced in pin-diodes by nanosecond electron pulses

    International Nuclear Information System (INIS)

    Leonhardt, J.W.; Goldner, R.; Bos, J.; Mehnert, R.

    1984-01-01

    The electron pulse technique can be applied as a diagnostic method to measure charge carrier lifetimes, diffusion length or junction width in semiconductor p + -i-n + diodes. The described effect of the pulse length dependence on the electron energy might be of importance as an energy monitor for pulsed electron accelerators. (author)

  19. A new method for compensation of the effect of charging transformer's leakage inductance on PFN voltage regulation in Klystron pulse modulators

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Akhil, E-mail: akhilpatel@rrcat.gov.in; Kale, Umesh; Shrivastava, Purushottam

    2017-04-21

    The Line type modulators have been widely used to generate high voltage rectangular pulses to power the klystron for high power RF generation. In Line type modulator, the Pulse Forming Network (PFN) which is a cascade combination of lumped capacitors and inductors is used to store the electrical energy. The charged PFN is then discharged into a klystron by firing a high voltage Thyratron switch. This discharge generates a high voltage rectangular pulse across the klystron electrodes. The amplitude and phase of Klystron's RF output is governed by the high voltage pulse amplitude. The undesired RF amplitude and phase stability issues arises at the klystron's output due to inter-pulse and during the pulse amplitude variations. To reduce inter-pulse voltage variations, the PFN is required to be charged at the same voltage after every discharge cycle. At present, the combination of widely used resonant charging and deQing method is used to regulate the pulse to pulse PFN voltage variations but the charging transformer's leakage inductance puts an upper bound on the regulation achievable by this method. Here we have developed few insights of the deQing process and devised a new compensation method to compensate this undesired effect of charging transformer's leakage inductance on the pulse to pulse PFN voltage stability. This compensation is accomplished by the controlled partial discharging of the split PFN capacitor using a low voltage MOSFET switch. Theoretically, very high values of pulse to pulse voltage stability may be achieved using this method. This method may be used in deQing based existing modulators or in new modulators, to increase the pulse to pulse voltage stability, without having a very tight bound on charging transformer's leakage inductance. Given a stable charging power supply, this method may be used to further enhance the inter-pulse voltage stability of modulators which employ the direct charging, after replacing the

  20. Structural transformations in MoOx thin films grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Camacho-Lopez, M.A.; Haro-Poniatowski, E.; Escobar-Alarcon, L.

    2004-01-01

    In this work, laser-induced crystallization in MoO x thin films (1.8≤x≤2.1) is reported. This transformation involves a MoO x oxidation and subsequently a crystallization process from amorphous MoO 3 to crystalline αMoO 3 . For comparison purposes crystallization is induced thermally, in an oven, as well. The crystallization kinetics is monitored by Raman spectroscopy; a threshold in the energy density necessary to induce the phase transformation is determined in the case of photo-crystallization. This threshold depends on the type of substrate on which the film is deposited. For the thin films deposited on glass substrates, the structural transformation is from amorphous MoO x to the thermodynamically stable αMoO 3 crystalline phase. For the thin films deposited on Si(100) the structural transformation is from amorphous MoO x to a mixture of αMoO 3 and the thermodynamically unstable βMoO 3 crystalline phases. The structural transformations are also characterized by scanning electron microscopy and light-transmission experiments. (orig.)

  1. Structural transformations in MoO{sub x} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, M.A.; Haro-Poniatowski, E. [Departamento de Fisica, Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, 09340, Mexico D. F. (Mexico); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, Mexico D. F. (Mexico)

    2004-01-01

    In this work, laser-induced crystallization in MoO{sub x} thin films (1.8{<=}x{<=}2.1) is reported. This transformation involves a MoO{sub x} oxidation and subsequently a crystallization process from amorphous MoO{sub 3} to crystalline {alpha}MoO{sub 3}. For comparison purposes crystallization is induced thermally, in an oven, as well. The crystallization kinetics is monitored by Raman spectroscopy; a threshold in the energy density necessary to induce the phase transformation is determined in the case of photo-crystallization. This threshold depends on the type of substrate on which the film is deposited. For the thin films deposited on glass substrates, the structural transformation is from amorphous MoO{sub x} to the thermodynamically stable {alpha}MoO{sub 3} crystalline phase. For the thin films deposited on Si(100) the structural transformation is from amorphous MoO{sub x} to a mixture of {alpha}MoO{sub 3} and the thermodynamically unstable {beta}MoO{sub 3} crystalline phases. The structural transformations are also characterized by scanning electron microscopy and light-transmission experiments. (orig.)

  2. Spectral transformations in the regime of pulse self-trapping in a nonlinear photonic crystal

    International Nuclear Information System (INIS)

    Novitsky, Denis V.

    2011-01-01

    We consider the interaction of a femtosecond light pulse with a one-dimensional photonic crystal with relaxing cubic nonlinearity in the regime of self-trapping. By use of numerical simulations, it is shown that, under certain conditions, the spectra of reflected and transmitted light possess the properties of narrowband (quasimonochromatic) or wideband (continuumlike) radiation. It is remarkable that these spectral features appear due to a significant frequency shift and occur inside a photonic band gap of the structure under investigation.

  3. Efficient ion heating of tokamak plasma by application of positive and negative current pulse in TRIAM-1

    International Nuclear Information System (INIS)

    Toi, Kazuo; Hiraki, Naoji; Nakamura, Kazuo; Mitarai, Osamu; Kawai, Yoshinobu

    1980-01-01

    The efficient heating of bulk ions of tokamak plasma is observed by application of the pulsed toroidal electric field much higher than the Dreicer field with the positive and negative polarities for the ohmic heating field. No deleterious effect on the confinement properties of tokamak plasma appears by the heating. The decay time of ion temperature raised by the heating pulse agrees well with the prediction by the neoclassical transport theory. The magnitude of the current induced by the pulsed electric field with the positive polarity is limited by the violent current disruption. In the case of the negative polarity, this is limited by lack of the MHD equilibrium due to vanishing the total plasma current. The ratio of drift velocity to electron thermal one / attains around 0.5, which suggests that the efficient ion heating may be due to the current-driven turbulence. (author)

  4. Efficient ion heating of tokamak plasma by application of positive and negative current pulse in TRIAM-1

    Energy Technology Data Exchange (ETDEWEB)

    Toi, K; Hiraki, N; Nakamura, K; Mitarai, O; Kawai, Y [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1980-02-01

    The efficient heating of bulk ions of tokamak plasma is observed by application of the pulsed toroidal electric field much higher than the Dreicer field with the positive and negative polarities for the ohmic heating field. No deleterious effect on the confinement properties of tokamak plasma appears by the heating. The decay time of ion temperature raised by the heating pulse agrees well with the prediction by the neoclassical transport theory. The magnitude of the current induced by the pulsed electric field with the positive polarity is limited by the violent current disruption. In the case of the negative polarity, this is limited by lack of the MHD equilibrium due to vanishing the total plasma current. The ratio of drift velocity to electron thermal one / attains around 0.5, which suggests that the efficient ion heating may be due to the current-driven turbulence.

  5. Determining Switched Reluctance Motor Current Waveforms Exploiting the Transformation from the Time to the Position Domain

    Directory of Open Access Journals (Sweden)

    Jakub Bernat

    2017-06-01

    Full Text Available This paper addresses the issue of estimating current waveforms in a switched reluctance motor required to achieve a desired electromagnetic torque. The methodology employed exploits the recently-developed method based on the transformation from the time to the position domain. This transformation takes account of nonlinearities caused by a doubly-salient structure. Owing to this new modelling technique it is possible to solve optimization problems with reference torque, constrained voltage, and parameter sensitivity accounted for. The proposed methodology is verified against published solutions and illustrated through simulations and experiments.

  6. Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

    International Nuclear Information System (INIS)

    Kaganovich, Igor D.; Shvets, Gennady; Startsev, Edward; Davidson, Ronald C.

    2001-01-01

    The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma

  7. Measuring Plasma Formation Field Strength and Current Loss in Pulsed Power Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Patel, Sonal G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Falcon, Ross Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Cartwright, Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Kiefer, Mark L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Cuneo, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Maron, Yitzhak [Weizmann Inst. of Science, Rehovot (Israel)

    2017-11-01

    This LDRD investigated plasma formation, field strength, and current loss in pulsed power diodes. In particular the Self-Magnetic Pinch (SMP) e-beam diode was studied on the RITS-6 accelerator. Magnetic fields of a few Tesla and electric fields of several MV/cm were measured using visible spectroscopy techniques. The magnetic field measurements were then used to determine the current distribution in the diode. This distribution showed that significant beam current extends radially beyond the few millimeter x-ray focal spot diameter. Additionally, shielding of the magnetic field due to dense electrode surface plasmas was observed, quantified, and found to be consistent with the calculated Spitzer resistivity. In addition to the work on RITS, measurements were also made on the Z-machine looking to quantify plasmas within the power flow regions. Measurements were taken in the post-hole convolute and final feed gap regions on Z. Dopants were applied to power flow surfaces and measured spectroscopically. These measurements gave species and density/temperature estimates. Preliminary B-field measurements in the load region were attempted as well. Finally, simulation work using the EMPHASIS, electromagnetic particle in cell code, was conducted using the Z MITL conditions. The purpose of these simulations was to investigate several surface plasma generations models under Z conditions for comparison with experimental data.

  8. Mechanism of formation of subnanosecond current front in high-voltage pulse open discharge

    Science.gov (United States)

    Schweigert, I. V.; Alexandrov, A. L.; Zakrevsky, Dm. E.; Bokhan, P. A.

    2014-11-01

    The mechanism of subnanosecond current front rise observed previously in the experiment in high-voltage pulse open discharge in helium is studied in kinetic particle-in-cell simulations. The Boltzmann equations for electrons, ions, and fast atoms are solved self-consistently with the Poisson equations for the electrical potential. The partial contributions to the secondary electron emission from the ions, fast atoms, photons, and electrons, bombarding the electrode, are calculated. In simulations, as in the experiment, the discharge glows between two symmetrical cathodes and the anode grid in the midplane at P =6 Torr and the applied voltage of 20 kV. The electron avalanche development is considered for two experimental situations during the last stage of breakdown: (i) with constant voltage and (ii) with decreasing voltage. For case (i), the subnanosecond current front rise is set by photons from the collisional excitation transfer reactions. For the case (ii), the energetic electrons swamp the cathode during voltage drop and provide the secondary electron emission for the subnanosecond current rise, observed in the experiment.

  9. Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Igor D. Kaganovich; Gennady Shvets; Edward Startsev; Ronald C. Davidson

    2001-01-30

    The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma.

  10. Characterization of carbon fiber polymer matrix composites subjected to simultaneous application of electric current pulse and low velocity impact

    Science.gov (United States)

    Hart, Robert James

    2011-12-01

    The use of composite materials in aerospace, electronics, and wind industries has become increasingly common, and these composite components are required to carry mechanical, electrical, and thermal loads simultaneously. A unique property of carbon fiber composites is that when an electric current is applied to the specimen, the mechanical strength of the specimen increases. Previous studies have shown that the higher the electric current, the greater the increase in impact strength. However, as current passes through the composite, heat is generated through Joule heating. This Joule heating can cause degradation of the composite and thus a loss in strength. In order to minimize the negative effects of heating, it is desired to apply a very high current for a very short duration of time. This thesis investigated the material responses of carbon fiber composite plates subjected to electrical current pulse loads of up to 1700 Amps. For 32 ply unidirectional IM7/977-3 specimens, the peak impact load and absorbed energy increased slightly with the addition of a current pulse at the time of an impact event. In 16 ply cross-ply IM7/977-2 specimens, the addition of the current pulse caused detrimental effects due to electrical arcing at the interface between the composite and electrodes. Further refinement of the experimental setup should minimize the risk of electrical arcing and should better elucidate the effects of a current pulse on the impact strength of the specimens.

  11. Transformer inrush current reduction through sequential energization for wind farm applications

    Energy Technology Data Exchange (ETDEWEB)

    Abdulsalam, S.; Xu, W. [Alberta Univ., Edmonton, AB (Canada)

    2008-07-01

    Wind power is considered as one of the fastest growing technologies in the power industry. The electrical configuration of a wind farm consists of long spans of medium voltage collector feeders. Each wind generator is connected to the collector circuit/feeder through either a pad mount oil filled, or a nacelle-mounted dry type transformer. All collector feeders connect to a single collector substation where the connection to the high-voltage transmission is established through a step up transformer. With a large number of wind generators per feeder, large inrush current will flow due to simultaneous transformer energization which can cause high voltage sag at the point of common coupling. Wind farms are generally located in unpopulated remote areas where no access to strong network connection is feasible. It is common to have the PCC on a relatively weak location on the sub-transmission/distribution network. In order to meet interconnection standards requirements, the amount of voltage sag due to the energization of a number of transformers needs to be evaluated. This paper presented an effective solution to the mitigation of inrush currents and associated voltage sag for wind farm applications. The paper presented a diagram of a typical configuration of a wind farm electrical distribution system and also described the analytical methodologies for the evaluation of inrush current level together with simulation results. A simplified analysis and sizing criteria for the associated neutral resistor size was presented. It was concluded that the scheme could significantly reduce inrush current level when a large number of transformers are simultaneously energized. The presented application eliminates the need to sectionalize feeders, thereby simplifying them for the energization process. 6 refs., 5 figs.

  12. A model of preliminary breakdown pulse peak currents and their relation to the observed electric-field pulses

    Czech Academy of Sciences Publication Activity Database

    Kašpar, Petr; Santolík, Ondřej; Kolmašová, Ivana; Farges, T.

    2017-01-01

    Roč. 44, č. 1 (2017), s. 596-603 ISSN 0094-8276 R&D Projects: GA ČR(CZ) GA14-31899S Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : lightning initiation * electromagnetic radiation * preliminary breakdown pulses Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 4.253, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016GL071483/pdf

  13. Post-tensioning tendon force loss detection using low power pulsed eddy current measurement

    Science.gov (United States)

    Kim, Ji-Min; Lee, Jun; Sohn, Hoon

    2018-04-01

    In the field of bridge engineering, pre-fabrication of a bridge member and its construction in site have been issued and studied, which achieves improved quality and rapid construction. For integration of those pre-fabricated segments into a structural member (i.e., a concrete slab, girder and pier), post-tensioning (PT) technique is adopted utilizing a high-strength steel tendon, and an effective investigation of the remaining PT tendon force is essential to assure an overall structural integrity. This study proposes a pulsed eddy current based tendon force loss detection system. A compact eddy current sensor is designed to be installed on the surface of an anchor holding a steel PT tendon. The intensity of the induced eddy current varies with PT tendon force alteration due to the magnetostriction effect of a ferromagnetic material. The advantages of the proposed system are as follows: (1) low power consumption, (2) rapid inspection, and (3) simple installation. Its performance was validated experimentally in a full-scale lab test of a 3.3-m long, 15.2-mm diameter mono-tendon that was tensioned using a universal testing machine. Tendon force was controlled from 20 to 180 kN with 20 kN interval, and eddy current responses were measured and analyzed at each force condition. The proposed damage index and the amount of force loss of PT tendon were monotonically related, and an excessive loss as much as 30 % of an initially-introduced tendon force was successfully predicted.

  14. Direct and pulsed current annealing of p-MOSFET based dosimeter: the "MOSkin".

    Science.gov (United States)

    Alshaikh, Sami; Carolan, Martin; Petasecca, Marco; Lerch, Michael; Metcalfe, Peter; Rosenfeld, Anatoly

    2014-06-01

    Contemporary radiation therapy (RT) is complicated and requires sophisticated real-time quality assurance (QA). While 3D real-time dosimetry is most preferable in RT, it is currently not fully realised. A small, easy to use and inexpensive point dosimeter with real-time and in vivo capabilities is an option for routine QA. Such a dosimeter is essential for skin, in vivo or interface dosimetry in phantoms for treatment plan verification. The metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector is one of the best choices for these purposes, however, the MOSFETs sensitivity and its signal stability degrade after essential irradiation which limits its lifespan. The accumulation of positive charge on the gate oxide and the creation of interface traps near the silicon-silicon dioxide layer is the primary physical phenomena responsible for this degradation. The aim of this study is to investigate MOSFET dosimeter recovery using two proposed annealing techniques: direct current (DC) and pulsed current (PC), both based on hot charged carrier injection into the gate oxide of the p-MOSFET dosimeter. The investigated MOSFETs were reused multiple times using an irradiation-annealing cycle. The effect of the current-annealing parameters was investigated for the dosimetric characteristics of the recovered MOSFET dosimeters such as linearity, sensitivity and initial threshold voltage. Both annealing techniques demonstrated excellent results in terms of maintaining a stable response, linearity and sensitivity of the MOSFET dosimeter. However, PC annealing is more preferable than DC annealing as it offers better dose response linearity of the reused MOSFET and has a very short annealing time.

  15. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    International Nuclear Information System (INIS)

    Ekdahl, Carl A.; Abeyta, Epifanio O.; Aragon, Paul; Archuleta, Rita; Cook, Gerald; Dalmas, Dale; Esquibel, Kevin; Gallegos, Robert A.; Garnett, Robert; Harrison, James F.; Johnson, Jeffrey B.; Jacquez, Edward B.; Mccuistian, Brian T.; Montoya, Nicholas A.; Nath, Subrato; Nielsen, Kurt; Oro, David; Prichard, Benjamin; Rowton, Lawrence; Sanchez, Manolito; Scarpetti, Raymond; Schauer, Martin M.; Seitz, Gerald; Schulze, Martin; Bender, Howard A.; Broste, William B.; Carlson, Carl A.; Frayer, Daniel K.; Johnson, Douglas E.; Tom, C.Y.; Williams, John; Hughes, Thomas; Anaya, Richard; Caporaso, George; Chambers, Frank; Chen, Yu-Jiuan; Falabella, Steve; Guethlein, Gary; Raymond, Brett; Richardson, Roger; Trainham, C.; Watson, Jim; Weir, John; Genoni, Thomas; Toma, Carsten

    2009-01-01

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 (micro)s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  16. Excitation of low-frequency residual currents at combination frequencies of an ionising two-colour laser pulse

    Science.gov (United States)

    Vvedenskii, N. V.; Kostin, V. A.; Laryushin, I. D.; Silaev, A. A.

    2016-05-01

    We have studied the processes of excitation of low-frequency residual currents in a plasma produced through ionisation of gases by two-colour laser pulses in laser-plasma schemes for THz generation. We have developed an analytical approach that allows one to find residual currents in the case when one of the components of a two-colour pulse is weak enough. The derived analytical expressions show that the effective generation of the residual current (and hence the effective THz generation) is possible if the ratio of the frequencies in the two-colour laser pulse is close to a rational fraction with a not very big odd sum of the numerator and denominator. The results of numerical calculations (including those based on the solution of the three-dimensional time-dependent Schrödinger equation) agree well with the analytical results.

  17. Application of Streaming Effect and Joule Heating Effect of Pulse Current in Crack Healing of Metal Materials

    Directory of Open Access Journals (Sweden)

    Jian Chu

    2017-06-01

    Full Text Available Remanufacture engineering is an emerging industry that saves resources as well as protects the environment. However, cracks on remanufactured components can result in serious trouble. Therefore, in order to avoid unnecessary waste of resources and energy, these cracks should be repaired radically in order to ensure the smooth progressing of the remanufacturing process. Consequently, the crack healing technique of metal materials is very important in the field of remanufacturing. In this study, the U-shape vane stainless steel of a centrifugal compressor which had cracks was processed by pulse current using a high pulse current discharge device, and the influence of the streaming effect and Joule heating effect of pulse current on the crack healing of metal materials was studied, aiming to provide references for the better application of this technology in the remanufacturing field in the future.

  18. Applications of pulsed Eddy Current (PEC) technique on defect and material assessment

    International Nuclear Information System (INIS)

    Nurul A'in Ahmad Latif; Noorhazleena Azaman; Ilham Mukriz Zainal Abidin

    2014-01-01

    The pulsed eddy current (PEC) is an emerging electromagnetic method and widely used in multiple field including aerospace, petrochemical, industry and transportation. PEC mainly depends on the multiple variables such as peak value and rising time to detect and quantify the defects. Apart of its advantage as non contacting technique, it has ability on conducting surface and subsurface detection. Additionally, PEC is high sensitive to variety parameters that are inherent in the flaws. Compare to conventional eddy current, PEC allows deeper penetration as it is a combination from multiple frequencies. This paper demonstrates the abilities of PEC technique performing multiple testing in various fields such as conducting conductivity testing, measuring the material thickness and identifying depth of the defects. The conductivity testing will be performed on multiple materials such as aluminium, stainless steel, copper, austenitic steel and titanium. To measure the material thicknesses, PEC testing will be conducted on the multi layered specimen with the different thickness. Meanwhile to identify depth of defects, the testing will be carried out using a stainless steel calibration block contains multiple length of defect. For the validation purposes, all the results generate through the experiments will be compared with simulation results produced using dedicated software, COMSOL. (author)

  19. Discrimination of Inrush from Fault Currents in Power Transformers Based on Equivalent Instantaneous Inductance Technique Coupled with Finite Element Method

    Directory of Open Access Journals (Sweden)

    M. Jamali

    2011-09-01

    Full Text Available The phenomenon of magnetizing inrush is a transient condition, which occurs primarily when a transformer is energized. The magnitude of inrush current may be as high as ten times or more times of transformer rated current that causes malfunction of protection system. So, for safe running of a transformer, it is necessary to distinguish inrush current from fault currents. In this paper, an equivalent instantaneous inductance (EII technique is used to discriminate inrush current from fault currents. For this purpose, a three-phase power transformer has been simulated in Maxwell software that is based on finite elements. This three-phase power transformer has been used to simulate different conditions. Then, the results have been used as inputs in MATLAB program to implement the equivalent instantaneous inductance technique. The results show that in the case of inrush current, the equivalent instantaneous inductance has a drastic variation, while it is almost constant in the cases of fault conditions.

  20. Development of response transforms from comparative study of commercial pulsed neutron capture logging systems

    International Nuclear Information System (INIS)

    Salaita, G.N.; Youngblood, W.E.

    1991-01-01

    This paper reports that the absence of a common calibration facility to ascertain the accuracy of commercial pulsed neutron capture logging systems, coupled with the desire for more accurate saturation determination from time-lapse logs, prompted Saudi Aramco to carry out this comparative study. Three generations of Schlumberger's Thermal Decay Time (TDT) logging devices, viz., TDT-K, TDT-M, and TDT-P along with Atlas Wireline PDK-100 system were run in an Aramco well. The wellbore 8-1/2 inch with 7-inch casing-penetrated clean sand, shaly sand, and shale streaks sequence as exhibited by the open hole natural gamma ray log. initially, the wellbore fluid was diesel. The fluid was then changed to brines of 42-kppm and 176-kppm NACl, respectively. Three repeat passes at a logging speed of 900 ft/hr were obtained by each device for each of the three borehole liquids. In the case of PDK-100, a second set of log runs was obtained at 1800 ft/hr. The results of this extensive comparative study have increased the author's understanding of the borehole liquid and the diffusion effects on the response of pulsed neutron capture logging systems and also on the relative accuracy and precision of measured formation thermal neutron capture cross section by each system

  1. An investigation for structure transformation in electric pulse modified liquid aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Qi Jingang, E-mail: Qijingang1974@sina.co [School of Material Science and Engineering, Liaoning University of Technology, Jinzhou 121001 (China); Wang Jianzhong; He Lijia; Zhao Zuofu; Du Huiling [School of Material Science and Engineering, Liaoning University of Technology, Jinzhou 121001 (China)

    2011-02-15

    The electric pulse (EP) modification of liquid metal is a novel method for grain refinement. In this work, the structure tests of EP-modified liquid aluminum were conducted and investigated using high-temperature X-ray diffractometer by virtue of the outstanding structural heredity of EP-modified liquid aluminum. The results show that the EP-modified liquid structure tends to be slack and unordered with increasing temperature similar to that of the unmodified. Nevertheless, the quantitative characterization denoted by the liquid structural parameters exhibits its discrepancy. At the modifying temperature of 750 {sup o}C, the order of degree of EP-modified liquid aluminum is remarkably strengthened and the value of average atomic number per cluster changes from 119 (no EP) up to 174 (EP) by an increase of 46%. These tests experimentally testified Wang's electric pulse modification (EPM) model that was built only by phenomenology, and hereby the mechanism of grain refinement resulting from EPM is further elucidated.

  2. Foundations of pulsed power technology

    CERN Document Server

    Lehr, Janet

    2018-01-01

    Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interferen...

  3. Wide-range bipolar pulse conductance instrument employing current and voltage modes with sampled or integrated signal acquisition

    Energy Technology Data Exchange (ETDEWEB)

    Calhoun, R K; Holler, F J [Kentucky Univ., Lexington, KY (United States). Dept. of Chemistry; Geiger, jr, R F; Nieman, T A [Illinois Univ., Urbana, IL (United States). Dept. of Chemistry; Caserta, K J [Procter and Gamble Co., Cincinnati, OH (United States)

    1991-11-05

    An instrument for measuring solution conductance using the bipolar pulse technique is described. The instrument is capable of measuring conductances in the range of 5x10{sup -9}-10{Omega}{sup -1} with 1% accuracy or better in as little as 32 {mu}s. Accuracy of 0.001-0.01% is achievable over the range 1x10{sup -6}-1{Omega}{sup -1}. Circuitry and software are described that allow the instrument to adjust automatically the pulse height, pulse duration, excitation mode (current or voltage pulse) and data acquisition mode (sampled or integrated) to acquire data of optimum accuracy and precision. The urease-catalyzed decomposition of urea is used to illustrate the versality of the instrument, and other applications are cited. (author). 60 refs.; 7 figs.; 2 tabs.

  4. Nanocrystalline material in toroidal cores for current transformer: analytical study and computational simulations

    Directory of Open Access Journals (Sweden)

    Benedito Antonio Luciano

    2005-12-01

    Full Text Available Based on electrical and magnetic properties, such as saturation magnetization, initial permeability, and coercivity, in this work are presented some considerations about the possibilities of applications of nanocrystalline alloys in toroidal cores for current transformers. It is discussed how the magnetic characteristics of the core material affect the performance of the current transformer. From the magnetic characterization and the computational simulations, using the finite element method (FEM, it has been verified that, at the typical CT operation value of flux density, the nanocrystalline alloys properties reinforce the hypothesis that the use of these materials in measurement CT cores can reduce the ratio and phase errors and can also improve its accuracy class.

  5. Influences of pulsed current tungsten inert gas welding parameters on the tensile properties of AA 6061 aluminium alloy

    International Nuclear Information System (INIS)

    Senthil Kumar, T.; Balasubramanian, V.; Sanavullah, M.Y.

    2007-01-01

    Medium strength aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. In any structural application of this alloy consideration its weldability is of utmost importance as welding is largely used for joining of structural components. The preferred welding process of aluminium alloy is frequently tungsten inert gas (TIG) welding due to its comparatively easier applicability and better economy. In the case of single pass TIG welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The use of pulsed current parameters has been found to improve the mechanical properties of the welds compared to those of continuous current welds of this alloy due to grain refinement occurring in the fusion zone. Many considerations come into the picture and one need to carefully balance various pulse current parameters to arrive at an optimum combination. Hence, in this investigation an attempt has been made to study the influence of pulsed current TIG welding parameters on tensile properties of AA 6061 aluminium alloy weldments

  6. Energy-Saving Sintering of Electrically Conductive Powders by Modified Pulsed Electric Current Heating Using an Electrically Nonconductive Die

    Science.gov (United States)

    Ito, Mikio; Kawahara, Kenta; Araki, Keita

    2014-04-01

    Sintering of Cu and thermoelectric Ca3Co4O9 was tried using a modified pulsed electric current sintering (PECS) process, where an electrically nonconductive die was used instead of a conventional graphite die. The pulsed electric current flowed through graphite punches and sample powder, which caused the Joule heating of the powder compact itself, resulting in sintering under smaller power consumption. Especially for the Ca3Co4O9 powder, densification during sintering was also accelerated by this modified PECS process.

  7. Investigation of electrodes under flow of a submicrosecond current pulse with linear density up to 3 MA/cm

    International Nuclear Information System (INIS)

    Branitskii, A. V.; Grabovskii, E. V.; Dzhangobegov, V. V.; Laukhin, Ya. N.; Mitrofanov, K. N.; Oleinik, G. M.; Sasorov, P. V.; Tkachenko, S. I.; Frolov, I. N.

    2016-01-01

    The states of current-carrying elements at the transmission of megaampere current into load are studied. It is determined that the expansion velocity of plasma generated at the outer surface of cylindrical tubes produced of stainless steel, at flowing through them of submicrosecond current pulses with linear density of 3 MA/cm is 5.5 km/s. The evolution of various modes of instability is analyzed.

  8. Determination of current and rotational transform profiles in a current-carrying stellarator using soft x-ray emissivity measurements

    Science.gov (United States)

    Ma, X.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Herfindal, J. L.; Howell, E. C.; Knowlton, S. F.; Maurer, D. A.; Traverso, P. J.

    2018-01-01

    Collimated soft X-ray (SXR) emissivity measurements from multi-channel cameras on the Compact Toroidal Hybrid (CTH) tokamak/torsatron device are incorporated in the 3D equilibrium reconstruction code V3FIT to reconstruct the shape of flux surfaces and infer the current distribution within the plasma. Equilibrium reconstructions of sawtoothing plasmas that use data from both SXR and external magnetic diagnostics show the central safety factor to be near unity under the assumption that SXR iso-emissivity contours lie on magnetic flux surfaces. The reconstruction results are consistent with those using the external magnetic data and a constraint on the location of q = 1 surfaces determined from the sawtooth inversion surface extracted from SXR brightness profiles. The agreement justifies the use of approximating SXR emission as a flux function in CTH, at least within the core of the plasma, subject to the spatial resolution of the SXR diagnostics. This improved reconstruction of the central current density indicates that the current profile peakedness decreases with increasing external transform and that the internal inductance is not a relevant measure of how peaked the current profile is in hybrid discharges.

  9. Current transformer model with hysteresis for improving the protection response in electrical transmission systems

    Science.gov (United States)

    Matussek, Robert; Dzienis, Cezary; Blumschein, Jörg; Schulte, Horst

    2014-12-01

    In this paper, a generic enhanced protection current transformer (CT) model with saturation effects and transient behavior is presented. The model is used for the purpose of analysis and design of power system protection algorithms. Three major classes of protection CT have been modeled which all take into account the nonlinear inductance with remanence effects. The transient short-circuit currents in power systems are simulated under CT saturation condition. The response of a common power system protection algorithm with respect to robustness to nominal parameter variations and sensitivity against maloperation is demonstrated by simulation studies.

  10. Current transformer model with hysteresis for improving the protection response in electrical transmission systems

    International Nuclear Information System (INIS)

    Matussek, Robert; Dzienis, Cezary; Blumschein, Jörg; Schulte, Horst

    2014-01-01

    In this paper, a generic enhanced protection current transformer (CT) model with saturation effects and transient behavior is presented. The model is used for the purpose of analysis and design of power system protection algorithms. Three major classes of protection CT have been modeled which all take into account the nonlinear inductance with remanence effects. The transient short-circuit currents in power systems are simulated under CT saturation condition. The response of a common power system protection algorithm with respect to robustness to nominal parameter variations and sensitivity against maloperation is demonstrated by simulation studies

  11. Multiple current peaks in room-temperature atmospheric pressure homogenous dielectric barrier discharge plasma excited by high-voltage tunable nanosecond pulse in air

    Energy Technology Data Exchange (ETDEWEB)

    Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Tang, Kai; Liu, Zhi-jie; Wang, Sen [Key Lab of Materials Modification, Dalian University of Technology, Ministry of Education, Dalian 116024 (China)

    2013-05-13

    Room temperature homogenous dielectric barrier discharge plasma with high instantaneous energy efficiency is acquired by using nanosecond pulse voltage with 20-200 ns tunable pulse width. Increasing the voltage pulse width can lead to the generation of regular and stable multiple current peaks in each discharge sequence. When the voltage pulse width is 200 ns, more than 5 organized current peaks can be observed under 26 kV peak voltage. Investigation also shows that the organized multiple current peaks only appear in homogenous discharge mode. When the discharge is filament mode, organized multiple current peaks are replaced by chaotic filament current peaks.

  12. Initiation of ignition by the action of a high-current pulsed discharge on a gas

    NARCIS (Netherlands)

    Starikovskii, AY

    2003-01-01

    The possibility of nonthermal initiation of chemical reactions by a uniform pulsed nanosecond discharge is demonstrated. Dependences of variation of the ignition delay on initial conditions are obtained. It is shown that the main role in combustion initiation under conditions of a pulsed gas

  13. Pulse current electrodeposition of tungsten coatings on V–4Cr–4Ti alloy

    International Nuclear Information System (INIS)

    Jiang, Fan; Zhang, Yingchun; Li, Xuliang

    2015-01-01

    Highlights: • Tungsten coatings were successfully electroplated on vanadium alloy substrate. • Tungsten coatings consisted of two sub-layers. • Tungsten coatings plated at lower duty cycle has a better surface quality. • High heat flux property of tungsten coatings was investigated. • Helium ion irradiation property of tungsten coatings was investigated. - Abstract: Tungsten coatings with high (2 2 0)-orientation were formed on V alloy substrate by pulse current electrodeposition in air atmosphere. The coatings’ microstructure, crystal structure and adhesive strength between coatings and substrates were investigated. It could be observed the tungsten coatings consisted of two sub-layers with the inner tooth-like layer, and the outer columnar layer. The tungsten coatings deposited at lower duty cycle have a better surface quality with a little change in the adhesive strength. The tungsten coating was exposed to electron beam with power density of 200 MW/m 2 in the thermal shock test, the tungsten crystal grain surface melt, the microcracks are found among the crystal grains. Exfoliation, flaking and dense needle-like holes were observed on the tungsten coating after irradiation with helium ions at an energy of 65 keV and an implanted dose of 22.67 × 10 18 cm −2

  14. Design of shielded encircling send-receive type pulsed eddy current probe using numerical analysis method

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Kil [Dept. of Electircal Engineeirng, Kunsan National University, Kunsan (Korea, Republic of)

    2013-12-15

    An encircling send-receive type pulsed eddy current (PEC) probe is designed for use in aluminum tube inspection. When bare receive coils located away from the exciter were used, the peak time of the signal did not change although the distance from the exciter increased. This is because the magnetic flux from the exciter coil directly affects the receive coil signal. Therefore, in this work, both the exciter and the sensor coils were shielded in order to reduce the influence of direct flux from the exciter coil. Numerical simulation with the designed shielded encircling PEC probe showed the corresponding increase of the peak time as the sensor distance increased. Ferrite and carbon steel shields were compared and results of the ferrite shielding showed a slightly stronger peak value and a quicker peak time than those of the carbon steel shielding. Simulation results showed that the peak value increased as the defect size (such as depth and length) increased regardless of the sensor location. To decide a proper sensor location, the sensitivity of the peak value to defect size variation was investigated and found that the normalized peak value was more sensitive to defect size variation when the sensor was located closer to the exciter.

  15. Pulsed counter-current ultrasound-assisted extraction and characterization of polysaccharides from Boletus edulis.

    Science.gov (United States)

    You, Qinghong; Yin, Xiulian; Ji, Chaowen

    2014-01-30

    Four methods for extracting polysaccharides from Boletus edulis, namely, hot-water extraction, ultrasonic clearer extraction, static probe ultrasonic extraction, and pulsed counter-current probe ultrasonic extraction (CCPUE), were studied. Results showed that CCPUE has the highest extraction efficiency among the methods studied. Under optimal CCPUE conditions, a B. edulis polysaccharide (BEP) yield of 8.21% was obtained. Three purified fractions, BEP-I, BEP-II, and BEP-III, were obtained through sequential purification by DEAE-52 and Sephadex G-75 chromatography. The average molecular weights of BEP-I, BEP-II, and BEP-III were 10,278, 23,761, and 42,736 Da, respectively. The polysaccharides were mainly composed of xylose, mannose, galactose, and glucose; of these, mannose contents were the highest. The antioxidant activities of the BEPs were further investigated by measurement of their ability to scavenge DPPH and hydroxyl radicals as well as their reducing power. The results indicated that the BEPs have good antioxidant activity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Response transforms from comparative study of commercial pulsed-neutron-capture logging systems

    International Nuclear Information System (INIS)

    Salaita, G.N.

    1992-01-01

    This paper reports that three generations of Schlumberger's Thermal Decay Time (TDT SM ) logging devices - viz., TDT-K, TDT-M, and TDT-P - along with an Atlas Wireline PDK-100 SM system were run in a Saudi Aramco well. The wellbore (8 1/2 in. with 7-in. casing) penetrated a sequence of clean sand, shaly sand, and shale streaks as exhibited by the openhole natural gamma ray log. The initial wellbore fluid was diesel. The fluid was then changed to brines of 42,000 and 176,000 ppm NaCl, respectively. Three repeat passes at a logging speed of 900 ft/hr were obtained by each device for each borehole liquid. As a result of this extensive comparative study, a set of departure curves and mathematical transforms was developed primarily for standardizing the various Schlumberger tools to a common reference logging system and/or borehole environment. The transforms were used beneficially to determine residual oil saturation (ROS) from time-lapse logs in a Saudi Aramco reservoir

  17. Transformation

    DEFF Research Database (Denmark)

    Bock, Lars Nicolai

    2011-01-01

    Artiklen diskuterer ordet "transformation" med udgangspunkt i dels hvorledes ordet bruges i arkitektfaglig terminologi og dels med fokus på ordets potentielle indhold og egnethed i samme teminologi.......Artiklen diskuterer ordet "transformation" med udgangspunkt i dels hvorledes ordet bruges i arkitektfaglig terminologi og dels med fokus på ordets potentielle indhold og egnethed i samme teminologi....

  18. TRANSFORMATION

    Energy Technology Data Exchange (ETDEWEB)

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  19. Evaluation of machine learning tools for inspection of steam generator tube structures using pulsed eddy current

    Science.gov (United States)

    Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2017-02-01

    Degradation of nuclear steam generator (SG) tubes and support structures can result in a loss of reactor efficiency. Regular in-service inspection, by conventional eddy current testing (ECT), permits detection of cracks, measurement of wall loss, and identification of other SG tube degradation modes. However, ECT is challenged by overlapping degradation modes such as might occur for SG tube fretting accompanied by tube off-set within a corroding ferromagnetic support structure. Pulsed eddy current (PEC) is an emerging technology examined here for inspection of Alloy-800 SG tubes and associated carbon steel drilled support structures. Support structure hole size was varied to simulate uniform corrosion, while SG tube was off-set relative to hole axis. PEC measurements were performed using a single driver with an 8 pick-up coil configuration in the presence of flat-bottom rectangular frets as an overlapping degradation mode. A modified principal component analysis (MPCA) was performed on the time-voltage data in order to reduce data dimensionality. The MPCA scores were then used to train a support vector machine (SVM) that simultaneously targeted four independent parameters associated with; support structure hole size, tube off-centering in two dimensions and fret depth. The support vector machine was trained, tested, and validated on experimental data. Results were compared with a previously developed artificial neural network (ANN) trained on the same data. Estimates of tube position showed comparable results between the two machine learning tools. However, the ANN produced better estimates of hole inner diameter and fret depth. The better results from ANN analysis was attributed to challenges associated with the SVM when non-constant variance is present in the data.

  20. On-line Monitoring Device for High-voltage Switch Cabinet Partial Discharge Based on Pulse Current Method

    Science.gov (United States)

    Y Tao, S.; Zhang, X. Z.; Cai, H. W.; Li, P.; Feng, Y.; Zhang, T. C.; Li, J.; Wang, W. S.; Zhang, X. K.

    2017-12-01

    The pulse current method for partial discharge detection is generally applied in type testing and other off-line tests of electrical equipment at delivery. After intensive analysis of the present situation and existing problems of partial discharge detection in switch cabinets, this paper designed the circuit principle and signal extraction method for partial discharge on-line detection based on a high-voltage presence indicating systems (VPIS), established a high voltage switch cabinet partial discharge on-line detection circuit based on the pulse current method, developed background software integrated with real-time monitoring, judging and analyzing functions, carried out a real discharge simulation test on a real-type partial discharge defect simulation platform of a 10KV switch cabinet, and verified the sensitivity and validity of the high-voltage switch cabinet partial discharge on-line monitoring device based on the pulse current method. The study presented in this paper is of great significance for switch cabinet maintenance and theoretical study on pulse current method on-line detection, and has provided a good implementation method for partial discharge on-line monitoring devices for 10KV distribution network equipment.

  1. Ion energy spectrum just after the application of current pulse for turbulent heating in the TRIAM-1 tokamak

    International Nuclear Information System (INIS)

    Nakamura, Kazuo; Nakamura, Yukio; Hiraki, Naoji; Itoh, Satoshi

    1981-01-01

    Temporal evolution and spatial profile of ion energy spectrum just after the application of current pulse for turbulent heating are investigated experimentally in TRIAM-1 and numerically with a Fokker-Planck equation. Two-component ion energy spectrum formed by turbulent heating relaxes to single one within tau sub(i) (ion collision time). (author)

  2. Ion energy spectrum just after the application of current pulse for turbulent heating in the TRIAM-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K; Nakamura, Y; Hiraki, N; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1981-07-01

    Temporal evolution and spatial profile of ion energy spectrum just after the application of current pulse for turbulent heating are investigated experimentally in TRIAM-1 and numerically with a Fokker-Planck equation. Two-component ion energy spectrum formed by turbulent heating relaxes to single one within tau sub(i) (ion collision time).

  3. Application of lanthanide-shift reagents in pulsed Fourier-transform nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Zektzer, A.S.

    1986-01-01

    The application of lanthanide-shift reagents (LSR's) to pulsed NMR is presented. Several areas were investigated in which the information content of the data was enhanced through the use of an LSR. The problem first investigated combines the ability of LSR's to influence both the shift and relaxation times of the substrate nuclei. Adamantan-2-ol which has a second-order proton spectra was simplified to first-order by the addition of Eu(fod) 3 at which time the T 1 -relaxation times of each resonance were measured at several ratios of [LSR]/[sub] in order to calculate the T 1 's of the bound species by multiple linear regression. The second application involved using LSR's to cause shift changes in compounds not usually accessible to LSR's. Sulfur heterocycles, which show little if any shift with LSR's, were found to exhibit large shifts when silver organic salts were used in combination with an LSR such as Dy(fod) 3 or Ho(fod) 3 . The last application was the assignment of the 1 H and 13 C resonances of a thieno-pyridine and the comparison of these assignments to those from high-field two-dimensional NMR techniques

  4. Can the use of pulsed direct current induce oscillation in the applied pressure during spark plasma sintering?

    International Nuclear Information System (INIS)

    Salamon, David; Eriksson, Mirva; Nygren, Mats; Shen Zhijian

    2012-01-01

    The spark plasma sintering (SPS) process is known for its rapid densification of metals and ceramics. The mechanism behind this rapid densification has been discussed during the last few decades and is yet uncertain. During our SPS experiments we noticed oscillations in the applied pressure, related to a change in electric current. In this study, we investigated the effect of pulsed electrical current on the applied mechanical pressure and related changes in temperature. We eliminated the effect of sample shrinkage in the SPS setup and used a transparent quartz die allowing direct observation of the sample. We found that the use of pulsed direct electric current in our apparatus induces pressure oscillations with the amplitude depending on the current density. While sintering Ti samples we observed temperature oscillations resulting from pressure oscillations, which we attribute to magnetic forces generated within the SPS apparatus. The described current–pressure–temperature relations might increase understanding of the SPS process.

  5. Petawatt pulsed-power accelerator

    Science.gov (United States)

    Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  6. Electromotive force analysis of current transformer during lightning surge inflow using Fourier series expansion

    Directory of Open Access Journals (Sweden)

    Youngsun Kim

    2017-05-01

    Full Text Available The most common structure used for current transformers (CTs consists of secondary windings around a ferromagnetic core past the primary current being measured. A CT used as a surge protection device (SPD may experience large inrushes of current, like surges. However, when a large current flows into the primary winding, measuring the magnitude of the current is difficult because the ferromagnetic core becomes magnetically saturated. Several approaches to reduce the saturation effect are described in the literature. A Rogowski coil is representative of several devices that measure large currents. It is an electrical device that measures alternating current (AC or high-frequency current. However, such devices are very expensive in application. In addition, the volume of a CT must be increased to measure sufficiently large currents, but for installation spaces that are too small, other methods must be used. To solve this problem, it is necessary to analyze the magnetic field and electromotive force (EMF characteristics when designing a CT. Thus, we proposed an analysis method for the CT under an inrush current using the time-domain finite element method (TDFEM. The input source current of a surge waveform is expanded by a Fourier series to obtain an instantaneous value. An FEM model of the device is derived in a two-dimensional system and coupled with EMF circuits. The time-derivative term in the differential equation is solved in each time step by the finite difference method. It is concluded that the proposed algorithm is useful for analyzing CT characteristics, including the field distribution. Consequently, the proposed algorithm yields a reference for obtaining the effects of design parameters and magnetic materials for special shapes and sizes before the CT is designed and manufactured.

  7. Electromotive force analysis of current transformer during lightning surge inflow using Fourier series expansion

    Science.gov (United States)

    Kim, Youngsun

    2017-05-01

    The most common structure used for current transformers (CTs) consists of secondary windings around a ferromagnetic core past the primary current being measured. A CT used as a surge protection device (SPD) may experience large inrushes of current, like surges. However, when a large current flows into the primary winding, measuring the magnitude of the current is difficult because the ferromagnetic core becomes magnetically saturated. Several approaches to reduce the saturation effect are described in the literature. A Rogowski coil is representative of several devices that measure large currents. It is an electrical device that measures alternating current (AC) or high-frequency current. However, such devices are very expensive in application. In addition, the volume of a CT must be increased to measure sufficiently large currents, but for installation spaces that are too small, other methods must be used. To solve this problem, it is necessary to analyze the magnetic field and electromotive force (EMF) characteristics when designing a CT. Thus, we proposed an analysis method for the CT under an inrush current using the time-domain finite element method (TDFEM). The input source current of a surge waveform is expanded by a Fourier series to obtain an instantaneous value. An FEM model of the device is derived in a two-dimensional system and coupled with EMF circuits. The time-derivative term in the differential equation is solved in each time step by the finite difference method. It is concluded that the proposed algorithm is useful for analyzing CT characteristics, including the field distribution. Consequently, the proposed algorithm yields a reference for obtaining the effects of design parameters and magnetic materials for special shapes and sizes before the CT is designed and manufactured.

  8. Characterisation of an optimised high current MgO/Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8.21} composite conductor using pulsed transport currents with pulsed magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B A; Gilewski, A; Rogacki, K; Kursumovic, A; Evetts, J E; Jones, H; Henson, R; Tsukamoto, O

    2003-01-15

    High temperature superconducting conductors are already used in hybrid magnets to produce fields that enhance the performance of conventional magnets made from A-15 type low temperature superconducting wires. For such applications it is vital that the interdependence of the critical parameters such as critical current versus magnetic field can be mapped under high field and high current conditions. However these superconductors have high critical currents even at fields over 20 T, making accurate measurements difficult due to the thermal and mechanical problems. In this paper, we compare measurements on the fully optimised Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8.21} flat rigid conductors using an innovative pulsed high transport current and pulsed high field technique. We show how analysis of the voltage signal from Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8.21} tape in pulsed conditions may be used to extract the critical current under quasi-stationary conditions.

  9. Reduced timing Sensitivity in all-optical switching using flat-top control pulses obtained by the optical fourier transform technique

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2006-01-01

    into the time domain, referred to as the optical Fourier transform technique. A 3 ps flat-top pulse derived from a 3 nm wide square filter is obtained, and used to gate an all-optical OTDM demultiplexer, yielding an error-free timing jitter tolerance of 3 ps for 80 Gb/s and 160 Gb/s data signals.......For high-speed serial data, timing tolerance is crucial for switching and regeneration. We propose a novel scheme to generate flat-top pulses, for use as gating control pulses. The scheme relies on spectral shaping by a square-shaped filter, followed by a linear transformation of the spectral shape...

  10. Influence of current density on surface morphology and properties of pulse plated tin films from citrate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Ashutosh; Bhattacharya, Sumit; Das, Siddhartha; Das, Karabi, E-mail: karabi@metal.iitkgp.ernet.in

    2014-01-30

    Bulk polycrystalline tin films have been processed by pulse electrodeposition technique from a simple solution containing triammonium citrate and stannous chloride. The cathodic investigations have been carried out by galvanostatic methods. As deposited samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD analysis of the deposited films shows microcrystalline grains having β-Sn form. The surface morphology is very rough at lower current density, but becomes smooth at higher current density, and exhibits pyramid type morphology at all the current densities. The effect of current density on microhardness, melting behavior, and electrical resistivity are also reported here.

  11. Hardening of alloys in glow discharge with the use of pulsed electric current

    International Nuclear Information System (INIS)

    Shipko, M.N.; Pomel'nikova, A.S.; Solunin, A.M.; Solunin, M.A.

    2002-01-01

    The effect of ex/ternal pulsed electric field on the thickness of a hardened surface layer of a Nd-Fe-B system alloy during chemical heat treatment in a glow discharge is studied. The relationship is established between the hardened layer thickness and the frequency of external electric field which is verified by derived equations for the relation between electron energy and pulsed electric field frequency [ru

  12. Multiscale wind cycles and current pulses at the Black Sea eastern boundary

    Science.gov (United States)

    Melnikov, Vasiliy; Moskalenko, Lidija; Piotoukh, Vladimir; Zatsepin, Andrey

    2015-04-01

    quantified anomalies, associated with different frequency components of variability, such as sub-meso-scale eddies, marginal shelf waves, inertial oscillations, diurnal, semi-diurnal and short-period internal waves, long surface waves, were estimated. Based on estimates of the statistical relationships between the different parameters of hydro-meteorological system, including meteorological elements, sea level, sea temperature and flow fields, space/time scales of the observed fields variability were estimated. Several new features of the physical mechanisms of multiscale hydro-physical processes in the shelf zone of the Black Sea, have been revealed. In particular, it is shown, that there are wind self-similar cycles at different time scales, each cycle being consisted of a pair of northeast and then southeast winds, which corresponds to the alternative influences of the Azores and Siberian highs(in winter). In the range of decadal (10 years) scale and in macro space view, long-term wind cycles support basic Black Sea circulation(Rim Current).Wind cycles with a time scale of about 20 days give rise to distinct upwellings, appeared with the same frequency. Along with each upwelling, radical hydrological restructuring of the stratification is accompanied by intense advection with high velocities(up to 1 m/s). Kinetic energy is dominated by alongshore currents, the direction being reversed periodically. The vertical structure of currents is rather complicated. When the current speed exceeds some threshold value, the flow gives rise to relaxation oscillations with a period of about 24 hours with counterclockwise velocity vector rotation. All the above mentioned events and current pulses cause significant variations of air-sea fluxes. This research was jointly supported by Ministry of Education of the RF (Agreement №14.604.21.0044), Russian Academy of Sciences(Program No 23), RFBR grant 14-05-00159,contract No 10/2013 RGS-RFBR.

  13. Current Sheets in Pulsar Magnetospheres and Winds: Particle Acceleration and Pulsed Gamma Ray Emission

    Science.gov (United States)

    Arons, Jonathan

    electric current that separate regions of differing magnetization into the domain of highly relativistic magnetic fields - those with energy density large compared to the rest mass energy of the charged particles - the plasma - caught in that field. The investigators will create theoretical and computational models of the magnetic dissipation - a form of viscous flow in the thin sheets of electric current that form in the magnetized regions around the rotating stars - using Particle in-Cell plasma simulations. These simulations use a large computer to solve the equations of motion of many charged particles - millions to billions in the research that will be pursued - to unravel the dissipation of those fields and the acceleration of beams of particles in the thin sheets. The results will be incorporated into macroscopic MHD models of the magnetic structures around the stars which determine the location and strength of the current sheets, so as to model and analyze the pulsed gamma ray emission seen from hundreds of Rotation Powered Pulsars. The computational models will be assisted by ``pencil and paper'' theoretical modeling designed to motivate and interpret the computer simulations, and connect them to the observations.

  14. A Redundancy Mechanism Design for Hall-Based Electronic Current Transformers

    Directory of Open Access Journals (Sweden)

    Kun-Long Chen

    2017-03-01

    Full Text Available Traditional current transformers (CTs suffer from DC and AC saturation and remanent magnetization in many industrial applications. Moreover, the drawbacks of traditional CTs, such as closed iron cores, bulky volume, and heavy weight, further limit the development of an intelligent power protection system. In order to compensate for these drawbacks, we proposed a novel current measurement method by using Hall sensors, which is called the Hall-effect current transformer (HCT. The existing commercial Hall sensors are electronic components, so the reliability of the HCT is normally worse than that of the traditional CT. Therefore, our study proposes a redundancy mechanism for the HCT to strengthen its reliability. With multiple sensor modules, the method has the ability to improve the accuracy of the HCT as well. Additionally, the proposed redundancy mechanism monitoring system provides a condition-based maintenance for the HCT. We verify our method with both simulations and an experimental test. The results demonstrate that the proposed HCT with a redundancy mechanism can almost achieve Class 0.2 for measuring CTs according to IEC Standard 60044-8.

  15. Removing Eddy-current probe wobble noise from steam generator tubes testing using wavelet transform

    International Nuclear Information System (INIS)

    Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun; Upadhyaya, Belle R.

    2005-01-01

    One of the most import nondestructive evaluation (NDE) applied to steam generator tubes inspection is the electromagnetic Eddy-Current testing (ECT). The signals generated in this NDE, in general, contain many noises which make difficult the interpretation and analysis of ECT signals. One of the noises present in the signals is the probe wobble noise, which is caused by the existing slack between the probe and the tube. In this work, Wavelet Transform (WT) is used in the probe wobble de-noising. WT is a relatively recent mathematical tool, which allows local analysis of non stationary signals such as ECT signals. This is a great advantage of WT when compared with other analysis tools such as Fourier Transform. However, using WT involves wavelets and coefficients selection as well as choosing the number of decomposition level needed. This work presents a probe wobble de-noising method when used in conjunction with the traditional ECT evaluation. Comparative results using several WT applied do Eddy-Current signals are presented in a reliable way, in other words, without loss of inherent defect information. A stainless steel tube, with 2 artificial defects generated by electro-erosion, was inspected by a ZETEC MIZ-17ET ECT equipment. The signals were de-noised through several different WT and the results are presented. The method offer good results and is a promising method because allows for the removal of Eddy-Current signals probe wobble effect without loss of essential signal information. (author)

  16. A STUDY ABOUT CELL ACTIVITY ON ANODIZED Ti-6Al-4V BY MEANS OF PULSED CURRENT

    Directory of Open Access Journals (Sweden)

    LUANA M. R. VASCONCELLOS

    2017-05-01

    Full Text Available Titanium and some of its alloys exhibit excellent anti-corrosive and biocompatibility properties due to rapid formation of a passive film on their surfaces when exposed to the atmosphere. However, such materials presentpoor osteoindutive properties. Surfaces modified via anodization are being proposed in this study to promote a chemical interaction between implants and bone cells. For this purpose, samples in Ti-6Al-4V alloy discs were anodized in a phosphoric acid solution using pulsed current for being applied in orthopaedic implants. The pulsed current is based on duty cycle (DC, which was supplied by a square wave pulse rectifier at 100 Hz and maximum tension of 30 V. A scanning electron microscope was used to obtain images of the anodized surfaces, thus revealing the presence of uniformly distributed pores over the entire surface, measuring approximately 2 m in diameter. Osteogenic cells grown on the surface of the control and anodized samples were assayed for cytotoxicity and mineralized matrix formation. The anodized surfaces presented a higher rate of viable cells after 10 days, as well as a higher amount of nodules (p = 0.05. In conclusion, these results suggest that the nanotopography promoted by anodization using pulsed current induces beneficial modulatory effects on osteoblastic cells.

  17. Commissioning of the long-pulse fast wave current drive antennas for DIII-D

    International Nuclear Information System (INIS)

    Baity, F.W.; Barber, G.C.; Goulding, R.H.; Hoffman, D.J.; DeGrassie, J.S.; Pinsker, R.I.; Petty, C.C.; Cary, W.

    1995-01-01

    Two new four-element fast wave current drive antennas have been installed on DIII-D. These antennas are designed for 10-s pulses at 2 MW each in the frequency range of 30 to 120 MHz. Each element comprises two poloidal segments fed in parallel in order to optimize plasma coupling at the upper end of the frequency range. The antennas are mounted on opposite sides of the vacuum vessel, in ports designated 0 degrees and 180 degrees after their toroidal angle. Each antenna array is fed by a single transmitter. The power is first split two ways by means of a 3-dB hybrid coupler, then each of these lines feeds a resonant loop connecting a pair of array elements. The power transfer during asymmetric phasing is shunted between resonant loops by a decoupler. The resonant loops are fitted with line stretchers so that multiple frequencies of operation are possible without reconfiguring the transmission line. Commissioning of these antennas has been underway since June 1994. Several deficiencies in the transmission line system were uncovered during initial vacuum conditioning, including problems with the transmission line insulators and with the drive rods for the variable elements. The former was solved by replacing the original alumina insulators, and the latter has been avoided during operation to date by positioning the tuners to avoid high voltage appearing on the drive rods. A modified design for the drive rods will be implemented before RF operations resume operation June 1995. New transmitters were procured from ABB for the new antennas and were installed in parallel with the antenna installation. During initial vacuum conditioning of the antenna in the 180 degree port a fast digital oscilloscope was used to try to pinpoint the location of arcing by a time-of-flight technique and to develop an understanding of the typical arc signature in the system

  18. Mechanical and Thermal Properties of Pulsed Electric Current Sintered (PECS) Cu-Diamond Compacts

    Science.gov (United States)

    Ritasalo, Riina; Kanerva, Ulla; Ge, Yanling; Hannula, Simo-Pekka

    2014-04-01

    In this work, dispersion strengthening of copper by diamonds is explored. In particular, the influence of 50- and 250-nm diamonds at contents of 3 and 6 vol. pct on the mechanical and thermal properties of pulsed electric current sintered (PECS) Cu composites is studied. The composite powders were prepared by mechanical alloying in argon atmosphere using a high-energy vibratory ball mill. The PECS compacts prepared had high density (>97 pct of T.D.) with quite evenly distributed diamonds. The effectiveness of dispersoids in increasing the microhardness was more pronounced at a smaller particle size and larger volume fraction, explained by Hall-Petch and Orowan strengthening models. The microhardness of Cu with 6 and 3 vol. pct nanodiamonds and pure sm-Cu (submicron-sized Cu) was 1.77, 1.46, and 1.02 GPa, respectively. In annealing experiments at 623 K to 873 K (350 °C to 600 °C), the composites with 6 vol. pct dispersoids retained their hardness better than those with less dispersoids or sm-Cu. The coefficient of thermal expansion was lowered when diamonds were added, being the lowest at about 14 × 10-6 K-1 between 473 K and 573 K (200 °C and 300 °C). Good bonding between the copper and diamond was qualitatively demonstrated by nanoindentation. In conclusion, high-quality Cu-diamond composites can be produced by PECS with improved strength and better thermal stability than for sm-Cu.

  19. Nano-Pulse Stimulation induces immunogenic cell death in human papillomavirus-transformed tumors and initiates an adaptive immune response.

    Directory of Open Access Journals (Sweden)

    Joseph G Skeate

    Full Text Available Nano-Pulse Stimulation (NPS is a non-thermal pulsed electric field modality that has been shown to have cancer therapeutic effects. Here we applied NPS treatment to the human papillomavirus type 16 (HPV 16-transformed C3.43 mouse tumor cell model and showed that it is effective at eliminating primary tumors through the induction of immunogenic cell death while subsequently increasing the number of tumor-infiltrating lymphocytes within the tumor microenvironment. In vitro NPS treatment of C3.43 cells resulted in a doubling of activated caspase 3/7 along with the translocation of phosphatidylserine (PS to the outer leaflet of the plasma membrane, indicating programmed cell death activity. Tumor-bearing mice receiving standard NPS treatment showed an initial decrease in tumor volume followed by clearing of tumors in most mice, and a significant increase in overall survival. Intra-tumor analysis of mice that were unable to clear tumors showed an inverse correlation between the number of tumor infiltrating lymphocytes and the size of the tumor. Approximately half of the mice that cleared established tumors were protected against tumor re-challenge on the opposite flank. Selective depletion of CD8+ T cells eliminated this protection, suggesting that NPS treatment induces an adaptive immune response generating CD8+ T cells that recognize tumor antigen(s associated with the C3.43 tumor model. This method may be utilized in the future to not only ablate primary tumors, but also to induce an anti-tumor response driven by effector CD8+ T cells capable of protecting individuals from disease recurrence.

  20. Nano-Pulse Stimulation induces immunogenic cell death in human papillomavirus-transformed tumors and initiates an adaptive immune response.

    Science.gov (United States)

    Skeate, Joseph G; Da Silva, Diane M; Chavez-Juan, Elena; Anand, Snjezana; Nuccitelli, Richard; Kast, W Martin

    2018-01-01

    Nano-Pulse Stimulation (NPS) is a non-thermal pulsed electric field modality that has been shown to have cancer therapeutic effects. Here we applied NPS treatment to the human papillomavirus type 16 (HPV 16)-transformed C3.43 mouse tumor cell model and showed that it is effective at eliminating primary tumors through the induction of immunogenic cell death while subsequently increasing the number of tumor-infiltrating lymphocytes within the tumor microenvironment. In vitro NPS treatment of C3.43 cells resulted in a doubling of activated caspase 3/7 along with the translocation of phosphatidylserine (PS) to the outer leaflet of the plasma membrane, indicating programmed cell death activity. Tumor-bearing mice receiving standard NPS treatment showed an initial decrease in tumor volume followed by clearing of tumors in most mice, and a significant increase in overall survival. Intra-tumor analysis of mice that were unable to clear tumors showed an inverse correlation between the number of tumor infiltrating lymphocytes and the size of the tumor. Approximately half of the mice that cleared established tumors were protected against tumor re-challenge on the opposite flank. Selective depletion of CD8+ T cells eliminated this protection, suggesting that NPS treatment induces an adaptive immune response generating CD8+ T cells that recognize tumor antigen(s) associated with the C3.43 tumor model. This method may be utilized in the future to not only ablate primary tumors, but also to induce an anti-tumor response driven by effector CD8+ T cells capable of protecting individuals from disease recurrence.

  1. An EIS alternative for impedance measurement of a high temperature PEM fuel cell stack based on current pulse injection

    DEFF Research Database (Denmark)

    Jeppesen, Christian; Araya, Samuel Simon; Sahlin, Simon Lennart

    2017-01-01

    In this paper a method for estimating the fuel cell impedance is presented, namely the current pulse injection (CPI) method, which is well suited for online implementation. This method estimates the fuel cell impedance and unlike electrochemical impedance spectroscopy (EIS), it is simple...... to implement at a low cost. This makes it appealing as a characterization method for on-line diagnostic algorithms. In this work a parameter estimation method for estimation of equivalent electrical circuit (EEC) parameters, which is suited for on-line use is proposed. Tests on a 10 cell high temperature PEM...... fuel cell show that the method yields consistent results in estimating EEC parameters for different current pulse at different current loads, with a low variance. A comparison with EIS shows that despite its simplicity the response of CPI can reproduce well the impedance response of the high...

  2. Use of alternating and pulsed direct current electrified fields for zebra mussel control

    Science.gov (United States)

    Luoma, James A.; Dean, Jan C.; Severson, Todd J.; Wise, Jeremy K.; Barbour, Matthew

    2017-01-01

    Alternatives to chemicals for controlling dreissenid mussels are desirable for environmental compatibility, but few alternatives exist. Previous studies have evaluated the use of electrified fields for stunning and/or killing planktonic life stages of dreissenid mussels, however, the available literature on the use of electrified fields to control adult dreissenid mussels is limited. We evaluated the effects of sinusoidal alternating current (AC) and 20% duty cycle square-wave pulsed direct current (PDC) exposure on the survival of adult zebra mussels at water temperatures of 10, 15, and 22 °C. Peak voltage gradients of ~ 17 and 30 Vp/cm in the AC and PDC exposures, respectively, were continuously applied for 24, 48, or 72 h. Peak power densities ranged from 77,999 to 107,199 µW/cm3 in the AC exposures and 245,320 to 313,945 µW/cm3 in the PDC exposures. The peak dose ranged from 6,739 to 27,298 Joules/cm3 and 21,306 to 80,941 Joules/cm3 in the AC and PDC exposures, respectively. The applied power ranged from 16.6 to 68.9 kWh in the AC exposures and from 22.2 to 86.4 kWh in the PDC exposures. Mortality ranged from 2.7 to 92.7% in the AC exposed groups and from 24.0 to 98.7% in PDC exposed groups. Mortality increased with corresponding increases in water temperature and exposure duration, and we observed more zebra mussel mortality in the PDC exposures. Exposures conducted with AC required less of a peak dose (Joules/cm3) but more applied power (kWh) to achieve the same level of adult zebra mussel mortality as corresponding PDC exposures. The results demonstrate that 20% duty cycle square-wave PDC requires less energy than sinusoidal AC to inducing the same level of adult zebra mussel mortality.

  3. Analysis and Minimization of Output Current Ripple for Discontinuous Pulse-Width Modulation Techniques in Three-Phase Inverters

    Directory of Open Access Journals (Sweden)

    Gabriele Grandi

    2016-05-01

    Full Text Available This paper gives the complete analysis of the output current ripple in three-phase voltage source inverters considering the different discontinuous pulse-width modulation (DPWM strategies. In particular, peak-to-peak current ripple amplitude is analytically evaluated over the fundamental period and compared among the most used DPWMs, including positive and negative clamped (DPWM+ and DPWM−, and the four possible combinations between them, usually named as DPWM0, DPWM1, DPWM2, and DPWM3. The maximum and the average values of peak-to-peak current ripple are estimated, and a simple method to correlate the ripple envelope with the ripple rms is proposed and verified. Furthermore, all the results obtained by DPWMs are compared to the centered pulse-width modulation (CPWM, equivalent to the space vector modulation to identify the optimal pulse-width modulation (PWM strategy as a function of the modulation index, taking into account the different average switching frequency. In this way, the PWM technique providing for the minimum output current ripple is identified over the whole modulation range. The analytical developments and the main results are experimentally verified by current ripple measurements with a three-phase PWM inverter prototype supplying an induction motor load.

  4. Broadband Chirped-Pulse Fourier-Transform Microwave Spectroscopic Investigation of the Structures of Three Diethylsilane Conformers

    Science.gov (United States)

    Steber, Amanda L.; Obenchain, Daniel A.; Peebles, Rebecca A.; Peebles, Sean A.; Neill, Justin L.; Muckle, Matt T.; Pate, Brooks H.; Guirgis, Gamil A.

    2009-06-01

    The rotational spectrum of diethylsilane has been assigned using broadband chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy. Previously, Fourier-transform microwave rotational spectra were observed using a Balle-Flygare type instrument for the ^{28}Si isotopologues of the gauche-gauche, trans-gauche, and trans-trans conformers. In the present study, a broadband microwave spectrum was obtained at the University of Virginia, taking advantage of the ability to perform deep signal averaging to increase the measurement sensitivity. To obtain a full structural determination of the conformers of this molecule, spectra for the ^{29}Si, ^{30}Si, and single ^{13}C substitutions for the gauche-gauche, the trans-gauche, and the trans-trans species were assigned. Substitution (r_s) structures and inertial fit (r_0) structures were determined and a comparison between the experimental and ab initio structures will be presented. For the ^{28}Si isotopologues, the percent differences between the experimental and ab initio rotational constants are less than 1.5% for the trans-trans and trans-gauche and are between 2.0 and 5.0% for the gauche-gauche conformer. The structural parameters will be compared between this molecule, diethylgermane and other silicon containing molecules and the relative abundances of the three conformers will be discussed. S.A. Peebles, M.M. Serafin, R.A. Peebles, G.A. Guirgis, and H.D. Stidham J. Phys. Chem. A, (2009), DOI: 10.1021/jp811049n.

  5. Plasma erosion opening switch in the double-pulse operation mode of a high-current electron accelerator

    International Nuclear Information System (INIS)

    Isakov, I.F.; Lopatin, V.S.; Remnev, G.E.

    1987-01-01

    This paper reports the results of investigations of the operation of a fast current opening switch, with a 10/sup 13/-10/sup 16/ plasma density produced either by dielectric surface flashover or by explosive emission of graphite. A series of two pulses was applied to two diodes in parallel. The first pulse produced plasma in the first diode which closed that diode gap by the arrival time of the second pulse. The first, shorted, diode then acted as an erosion switch for the second pulse. A factor of 2.5-3 power multiplication was obtained under optimum conditions. The opening-switch resistance during the magnetic insulation phase, neglecting the electron losses between the switch and the generating diode, exceeded 100 Ω. The duration of the rapid opening phase was less than 5 ns under optimum conditions. This method of plasma production does not require external plasma sources, and permits a wide variation of plasma density, which in turn allows high inductor currents and stored energies

  6. Comments about the use of a Zig-Zag transformer to reduce the neutral current created by unbalanced nonlinear loads

    International Nuclear Information System (INIS)

    Beverly, L.; Hance, R.; Kristalinski, A.; Visser, A.

    1993-09-01

    The subject of AC line currents with high harmonic content and the potential for overloaded neutral wires caused by the non-linear loading of electronic power supplies has become one of the most popular and at the same time a very complex topic among electrical engineers. Different solutions are offered for this problem. Some examples are specially designed K-rated AC distribution transformers, delta connected primary windings, and L-C tuned filters. All of the above methods have some limitations. For instance, a K-rated transformer does not eliminate harmonics, but transmits them into the feeder. Neutral currents that flow from various loads to the K-rated transformer are still very high. These K-rated transformers are more expensive and are larger in physical size than conventional transformers. The delta connected primary of a power distribution transformer can only eliminate triplen harmonics for balanced loads. Neutral currents caused by the loads are not eliminated. The primary side circuit breaker may also not protect a transformer against overcurrents because the circuit breaker will not see the triplen harmonic current that is circulating in the primary of the transformer. L-C filters can create undesirable resonances, which will lead to an increase in harmonic currents. Another solution is to use a number of small Zig-Zag transformers to reduce the neutral current. This is attractive for the following reasons: relatively low cost, simplicity, ease of installation on existing distribution systems, ability to keep neutral currents local thus eliminating the need for larger neutral wires, and the ability to improve the fundamental load current balance as well

  7. Developing mathematical models to predict tensile properties of pulsed current gas tungsten arc welded Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Balasubramanian, M.; Jayabalan, V.; Balasubramanian, V.

    2008-01-01

    Titanium (Ti-6Al-4V) alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding process of titanium alloy is frequently gas tungsten arc (GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one need to carefully balance various pulse current parameters to arrive at an optimum combination. Hence, in this investigation an attempt has been made to develop mathematical models to predict tensile properties of pulsed current GTA welded titanium alloy weldments. Four factors, five level, central composite, rotatable design matrix is used to optimise the required number of experiments. The mathematical models have been developed by response surface method (RSM). The adequacy of the models has been checked by ANOVA technique. By using the developed mathematical models, the tensile properties of the joints can be predicted with 99% confidence level

  8. Developing mathematical models to predict tensile properties of pulsed current gas tungsten arc welded Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, M. [Department of Production Engineering, Sathyabama University, Old Mamallapuram Road, Chennai 600 119 (India)], E-mail: manianmb@rediffmail.com; Jayabalan, V. [Department of Manufacturing Engineering, Anna University, Guindy, Chennai 600 025 (India)], E-mail: jbalan@annauniv.edu; Balasubramanian, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002 (India)], E-mail: visvabalu@yahoo.com

    2008-07-01

    Titanium (Ti-6Al-4V) alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding process of titanium alloy is frequently gas tungsten arc (GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one need to carefully balance various pulse current parameters to arrive at an optimum combination. Hence, in this investigation an attempt has been made to develop mathematical models to predict tensile properties of pulsed current GTA welded titanium alloy weldments. Four factors, five level, central composite, rotatable design matrix is used to optimise the required number of experiments. The mathematical models have been developed by response surface method (RSM). The adequacy of the models has been checked by ANOVA technique. By using the developed mathematical models, the tensile properties of the joints can be predicted with 99% confidence level.

  9. A photocatalytic approach in micro arc oxidation of WO3-TiO2 nano porous semiconductors under pulse current

    International Nuclear Information System (INIS)

    Bayati, M.R.; Golestani-Fard, F.; Moshfegh, A.Z.; Molaei, R.

    2011-01-01

    Graphical abstract: WO3-TiO2 layers were fabricated via microarc oxidation process and effect of the electrical current type on their photocatalytic performance under UV and visible illuminations was investigated. Highlights: → WO3-TiO2 layers were grown by MAO under pulse current for the first time. → Effect of the frequency and duty cycle on properties of the layers was studied. → A correlation between catalytic performance and growth conditions was proposed. - Abstract: Since ultraviolet (UV) irradiation cannot be applied for a long time in practical applications, it is necessary to develop a narrow band gap photocatalyst to decompose environmental pollutants under visible irradiation. In this research, (WO 3 ) x -(TiO 2 ) 1-x nano-porous layers were fabricated by micro arc oxidation (MAO) and influence of the electrical current type on their physical and chemical properties was investigated. Morphological studies, performed by SEM technique, revealed that pore size and roughness decreased with the frequency and increased with the duty cycle. The pulse-grown layers had a finer structure when compared to those fabricated under direct current. XRD and XPS results showed that the layers consisted of anatase, rutile, and tungsten oxide phases. Applying pulse current resulted in higher anatase relative contents. Band gap energies of the MAO-grown TiO 2 and WO 3 -TiO 2 layers were respectively measured as 3.14 and 2.96 eV. The layers fabricated under pulse current exhibited higher photoactivity under ultraviolet and visible illuminations as compared to the layers grown under direct current. Methylene blue (MB) was used as a model material to examine photocatalytic performance of the layers. Maximum MB-photodegradation reaction rate constants over the pulse-synthesized WO 3 -TiO 2 layers were measured as 0.0269 and 0.0129 min -1 for ultraviolet and visible irradiations. For layers grown under direct current, the rate constants were lower, i.e. 0.0228 and 0

  10. Open-loop magneto-resistance sensor-based DC current transformer for FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, Eman; Hofmann, Klaus [Technical University Darmstadt (Germany); Reeg, Hansjoerg; Schwickert, Marcus [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)

    2016-07-01

    A Novel DC Current Transformer (N-DCCT) is currently under development for FAIR. The N-DCCT is going to be installed inside the SIS100 synchrotron. The proposed system is no longer based on magnetic modulation principle of the conventional DCCT. Instead, a Magneto-resistance sensor is utilized to detect the magnetic field of the ion-beam. For a first prototype the N-DCCT is realized as an open-loop system. It consists of a high permeability slotted ring core and up to two MR sensors. The maximum ion-beam current magnetic field is concentrated inside the ring core air gaps. MR sensors are placed inside the core air gaps. The sensor output voltage is directly proportional to the ion-beam current. The system is implemented using commercial Tunneling MR sensors. Measurements using one single sensor, as well as the application of two sensors are presented in this work. The sensitivity of the proposed N-DCCT is 0.566 [V/A] for one single MR sensor and 1.56 [V/A] when two sensors are implemented.

  11. Influence of magnetic arc oscillation and current pulsing on microstructure and high temperature tensile strength of alloy 718 TIG weldments

    International Nuclear Information System (INIS)

    Sivaprasad, K.; Ganesh Sundara Raman, S.; Mastanaiah, P.; Madhusudhan Reddy, G.

    2006-01-01

    The aim of the present work is to study the effect of magnetic arc oscillation and current pulsing on the microstructure and high temperature tensile strength of alloy 718 tungsten inert gas weldments. The magnetic arc oscillation technique resulted in refined Laves phase with lesser interconnectivity. The full benefits of current pulsing in breaking the dendrites could not be realized in the present study due to relatively higher heat input used in the welding process. In the direct aged condition weldments prepared using magnetic arc oscillation technique exhibited higher tensile strength due to the presence of refined and lesser-interconnected Laves particles. In the solution treated and aged condition, magnetic arc oscillated weldments exhibited lower tensile strength compared with the weldments made without arc oscillation due to the presence of large amounts of finer δ needles

  12. Use of time history speckle pattern and pulsed photoacoustic techniques to detect the self-accommodating transformation in a Cu-Al-Ni shape memory alloy

    International Nuclear Information System (INIS)

    Sanchez-Arevalo, F.M.; Aldama-Reyna, W.; Lara-Rodriguez, A.G.; Garcia-Fernandez, T.; Pulos, G.; Trivi, M.; Villagran-Muniz, M.

    2010-01-01

    Continuous and pulsed electromagnetic radiation was used to detect the self-accommodation mechanism on a polycrystalline Cu-13.83 wt.%Al-2.34 wt.%Ni shape memory alloy. Rectangular samples of this alloy were mechanically polished to observe the austenite and martensite phases. The samples were cooled in liquid nitrogen prior to the experiments to obtain the martensite phase. Using a dynamic speckle technique with a continuous wave laser we obtained the time history of the speckle pattern image and monitored the surface changes caused by the self-accommodation mechanism during the inverse (martensitic to austenitic) transformation. Using a photoacoustic technique based on a pulsed laser source it was also possible to detect the self-accommodation phenomena in a bulk sample. For comparison purposes, we used differential scanning calorimetry (DSC) to detect the critical temperatures of transformation and use these as reference to evaluate the performance of the optical and photoacoustical techniques. In all cases, the same range of temperature was obtained during the inverse transformation. From these results, we conclude that time history speckle pattern (THSP) and pulsed photoacoustic are complementary techniques; they are non-destructive and useful to detect surface and bulk martensitic transformation induced by a temperature change.

  13. Use of time history speckle pattern and pulsed photoacoustic techniques to detect the self-accommodating transformation in a Cu-Al-Ni shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Arevalo, F.M., E-mail: fsanchez@iim.unam.mx [CCADET - Universidad Nacional Autonoma de Mexico, A.P. 70-186, Mexico D.F., C.P. 04510 (Mexico); Aldama-Reyna, W. [Departamento Academico de Fisica, Universidad Nacional de Trujillo, Trujillo (Peru); Lara-Rodriguez, A.G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico); Garcia-Fernandez, T. [Universidad Autonoma de la Ciudad de Mexico (UACM), Prolongacion San Isidro 151, Col. San Lorenzo Tezonco, Mexico DF, C.P. 09790 (Mexico); Pulos, G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico); Trivi, M. [Centro de Investigaciones Opticas, Universidad de la Plata (Argentina); Villagran-Muniz, M. [CCADET - Universidad Nacional Autonoma de Mexico, A.P. 70-186, Mexico D.F., C.P. 04510 (Mexico)

    2010-05-15

    Continuous and pulsed electromagnetic radiation was used to detect the self-accommodation mechanism on a polycrystalline Cu-13.83 wt.%Al-2.34 wt.%Ni shape memory alloy. Rectangular samples of this alloy were mechanically polished to observe the austenite and martensite phases. The samples were cooled in liquid nitrogen prior to the experiments to obtain the martensite phase. Using a dynamic speckle technique with a continuous wave laser we obtained the time history of the speckle pattern image and monitored the surface changes caused by the self-accommodation mechanism during the inverse (martensitic to austenitic) transformation. Using a photoacoustic technique based on a pulsed laser source it was also possible to detect the self-accommodation phenomena in a bulk sample. For comparison purposes, we used differential scanning calorimetry (DSC) to detect the critical temperatures of transformation and use these as reference to evaluate the performance of the optical and photoacoustical techniques. In all cases, the same range of temperature was obtained during the inverse transformation. From these results, we conclude that time history speckle pattern (THSP) and pulsed photoacoustic are complementary techniques; they are non-destructive and useful to detect surface and bulk martensitic transformation induced by a temperature change.

  14. Design and study of photomultiplier pulse-shaping amplifier powered by the current flowing through a voltage divider

    International Nuclear Information System (INIS)

    Vladimir Popov

    2003-01-01

    A new version of Photomultiplier Tube (PMT) pulse amplifier, entirely powered by the current flowing through the base voltage divider, was designed and tested. This amplifier was designed for application in the JLAB G0 Experiment E00-006 as a part of high voltage base for XP2262 Photonis PMT. According to JLAB G0 experiment requirement, these PMT's operate with plastic scintillators at high counting rate (about MHz). Tests in JLAB experimental Hall C indicate that low energy gamma background cause up to 0.1 mA of PMT average anode current (without amplifier). At this radiation condition, PMT gain decreases by 50% within about 1 month of operation. The amplifier needs to reduce PMT anode current and to shape PMT anode pulse prior to sending it through a long cable line (more then 400 ft of RG-213 and RG-58 coax cables). Shaping of the PMT output pulse helps to reduce attenuation effect of the long cable line without significant reduction of timing accuracy. The results of this study of designed amplifier and PMT plus amplifier system are presented

  15. Analysis on fault current limiting and recovery characteristics of a flux-lock type SFCL with an isolated transformer

    International Nuclear Information System (INIS)

    Ko, Seckcheol; Lim, Sung-Hun; Han, Tae-Hee

    2013-01-01

    Highlights: ► Countermeasure to reduce the power burden of HTSC element consisting of the flux-lock type SFCL was studied. ► The power burden of HTSC element could be decreased by using the isolated transformer. ► The SFCL designed with the additive polarity winding could be confirmed to cause less power burden of the HTSC element. -- Abstract: The flux-lock type superconducting fault current limiter (SFCL) can quickly limit the fault current shortly after the short circuit occurs and recover the superconducting state after the fault removes. However, the superconducting element comprising the flux-lock type SFCL can be destructed when the high fault current passes through the SFCL. Therefore, the countermeasure to control the fault current and protect the superconducting element is required. In this paper, the flux-lock type SFCL with an isolated transformer, which consists of two parallel connected coils on an iron core and the isolated transformer connected in series with one of two coils, was proposed and the short-circuit experimental device to analyze the fault current limiting and the recovery characteristics of the flux-lock type SFCL with the isolated transformer were constructed. Through the short-circuit tests, the flux-lock type SFCL with the isolated transformer was confirmed to perform more effective fault current limiting and recovery operation compared to the flux-lock type SFCL without the isolated transformer from the viewpoint of the quench occurrence and the recovery time of the SFCL

  16. Analysis and Recognition of Traditional Chinese Medicine Pulse Based on the Hilbert-Huang Transform and Random Forest in Patients with Coronary Heart Disease

    Directory of Open Access Journals (Sweden)

    Rui Guo

    2015-01-01

    Full Text Available Objective. This research provides objective and quantitative parameters of the traditional Chinese medicine (TCM pulse conditions for distinguishing between patients with the coronary heart disease (CHD and normal people by using the proposed classification approach based on Hilbert-Huang transform (HHT and random forest. Methods. The energy and the sample entropy features were extracted by applying the HHT to TCM pulse by treating these pulse signals as time series. By using the random forest classifier, the extracted two types of features and their combination were, respectively, used as input data to establish classification model. Results. Statistical results showed that there were significant differences in the pulse energy and sample entropy between the CHD group and the normal group. Moreover, the energy features, sample entropy features, and their combination were inputted as pulse feature vectors; the corresponding average recognition rates were 84%, 76.35%, and 90.21%, respectively. Conclusion. The proposed approach could be appropriately used to analyze pulses of patients with CHD, which can lay a foundation for research on objective and quantitative criteria on disease diagnosis or Zheng differentiation.

  17. Analysis and Recognition of Traditional Chinese Medicine Pulse Based on the Hilbert-Huang Transform and Random Forest in Patients with Coronary Heart Disease

    Science.gov (United States)

    Wang, Yiqin; Yan, Hanxia; Yan, Jianjun; Yuan, Fengyin; Xu, Zhaoxia; Liu, Guoping; Xu, Wenjie

    2015-01-01

    Objective. This research provides objective and quantitative parameters of the traditional Chinese medicine (TCM) pulse conditions for distinguishing between patients with the coronary heart disease (CHD) and normal people by using the proposed classification approach based on Hilbert-Huang transform (HHT) and random forest. Methods. The energy and the sample entropy features were extracted by applying the HHT to TCM pulse by treating these pulse signals as time series. By using the random forest classifier, the extracted two types of features and their combination were, respectively, used as input data to establish classification model. Results. Statistical results showed that there were significant differences in the pulse energy and sample entropy between the CHD group and the normal group. Moreover, the energy features, sample entropy features, and their combination were inputted as pulse feature vectors; the corresponding average recognition rates were 84%, 76.35%, and 90.21%, respectively. Conclusion. The proposed approach could be appropriately used to analyze pulses of patients with CHD, which can lay a foundation for research on objective and quantitative criteria on disease diagnosis or Zheng differentiation. PMID:26180536

  18. Support time-dependent transformations for surveying and GIS : current status and upcoming challenges

    Science.gov (United States)

    Mahmoudabadi, H.; Lercier, D.; Vielliard, S.; Mein, N.; Briggs, G.

    2016-12-01

    The support of time-dependent transformations for surveying and GIS is becoming a critical issue. We need to convert positions from the realizations of the International Terrestrial Reference Frame to any national reference frame. This problem is easy to solve when all of the required information is available. But it becomes really complicated in a worldwide context. We propose an overview of the current ITRF-aligned reference frames and we describe a global solution to support time-dependent transformations between them and the International Terrestrial Reference Frame. We focus on the uncertainties of station velocities used. In a first approximation, we use a global tectonic plate model to calculate point velocities. We show the impact of the velocity model on the coordinate accuracies. Several countries, particularly in active regions, are developing semi-dynamic reference frames. These frames include local displacement models updated regularly and/or after major events (such as earthquakes). Their integration into surveying or GIS applications is an upcoming challenge. We want to encourage the geodetic community to develop and use standard formats.

  19. Partial discharge measurements on 110kV current transformers. Setting the control value. Case study

    Science.gov (United States)

    Dan, C.; Morar, R.

    2017-05-01

    The case study presents a series of partial discharge measurements, reflecting the state of insulation of 110kV CURRENT TRANSFORMERS located in Sibiu county substations. Measurements were performed based on electrical method, using MPD600: an acquisition and analysis toolkit for detecting, recording, and analyzing partial discharges. MPD600 consists of one acquisition unit, an optical interface and a computer with dedicated software. The system allows measurements of partial discharge on site, even in presence of strong electromagnetic interferences because it provides synchronous acquisition from all measurement points. Therefore, measurements, with the ability to be calibrated, do render: - a value subject to interpretation according to IEC 61869-1:2007 + IEC 61869-2:2012 + IEC 61869-3:2011 + IEC 61869-5:2011 and IEC 60270: 2000; - the possibility to determine the quantitative limit of PD (a certain control value) to which the equipment can be operated safely and repaired with minimal costs (relative to the high costs implied by eliminating the consequences of a failure) identified empirically (process in which the instrument transformer subjected to the tests was completely destroyed).

  20. Experience with on-line diagnostics for bushings and current transformers

    Energy Technology Data Exchange (ETDEWEB)

    Brusetti, R.

    2004-02-01

    The application of on-line diagnostic techniques is advocated as an alternative, under certain conditions, for the conventional off-line power factor test used to evaluate the condition of bushings and current transformers. Bushings which are tied to critical system apparatus or which cannot be readily removed from service are considered to be excellent candidates for on-line diagnostics. A case history involving 138-KV bushings is used to demonstrate the value of the on-line diagnostic system which, by taking into account power factor capacitance values along with the rate of change, not only detected the high power factor associated with the bushings, but allowed the high power factor bushings to continue operating with a known problem for over a year. With conventional testing, bushings that exhibited this level of power factor would typically be removed from service. 4 refs., 3 figs.

  1. Analytical Modeling Of The Steinmetz Coefficient For Single-Phase Transformer Eddy Current Loss Prediction

    Directory of Open Access Journals (Sweden)

    T. Aly Saandy

    2015-08-01

    Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.

  2. Design of a New Acceleration System for High-Current Pulsed Proton Beams from an ECR Source

    Science.gov (United States)

    Cooper, Andrew L.; Pogrebnyak, Ivan; Surbrook, Jason T.; Kelly, Keegan J.; Carlin, Bret P.; Champagne, Arthur E.; Clegg, Thomas B.

    2014-03-01

    A primary objective for accelerators at TUNL's Laboratory for Experimental Nuclear Astrophysics (LENA) is to maximize target beam intensity to ensure a high rate of nuclear events during each experiment. Average proton target currents of several mA are needed from LENA's electron cyclotron resonance (ECR) ion source because nuclear cross sections decrease substantially at energies of interest tube structures; and provide better heat dissipation by using deionized water to provide the current drain needed to establish the accelerating tube's voltage gradient. Details of beam optical modeling calculations, proposed accelerating tube design, and initial beam pulsing tests will be described. Work supported in part by USDOE Office of HE and Nuclear Physics.

  3. System for verification in situ of current transformers in high voltage substations; Sistema para verificacao in situ de transformadores de corrente em substacoes de alta tensao

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Pedro Henrique; Costa, Marcelo M. da; Dahlke, Diogo B.; Ikeda, Minoru [LACTEC - Instituto de Tecnologia para o Desenvolvimento, Curitiba, PR (Brazil)], Emails: pedro.henrique@lactec.org.br, arinos@lactec.org.br, diogo@lactec.org.br, minoru@lactec.org.br, Celso.melo@copel.com; Carvalho, Joao Claudio D. de [ELETRONORTE, Belem, PR (Brazil)], E-mail: marcelo.melo@eln.gov.br; Teixeira Junior, Jose Arinos [ELETROSUL, Florianopolis, SC (Brazil)], E-mail: jclaudio@eletrosul.gov.br; Melo, Celso F. [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil)], E-mail: Celso.melo@copel.com

    2009-07-01

    This work presents an alternative proposal to the execute the calibration of conventional current transformer at the field, using a verification system composed by a optical current transformer as a reference standard, able to installation in extra high voltage bars.

  4. Development and application of network virtual instrument for emission spectrum of pulsed high-voltage direct current discharge

    Science.gov (United States)

    Gong, X.; Wu, Q.

    2017-12-01

    Network virtual instrument (VI) is a new development direction in current automated test. Based on LabVIEW, the software and hardware system of VI used for emission spectrum of pulsed high-voltage direct current (DC) discharge is developed and applied to investigate pulsed high-voltage DC discharge of nitrogen. By doing so, various functions are realized including real time collection of emission spectrum of nitrogen, monitoring operation state of instruments and real time analysis and processing of data. By using shared variables and DataSocket technology in LabVIEW, the network VI system based on field VI is established. The system can acquire the emission spectrum of nitrogen in the test site, monitor operation states of field instruments, realize real time face-to-face interchange of two sites, and analyze data in the far-end from the network terminal. By employing the network VI system, the staff in the two sites acquired the same emission spectrum of nitrogen and conducted the real time communication. By comparing with the previous results, it can be seen that the experimental data obtained by using the system are highly precise. This implies that the system shows reliable network stability and safety and satisfies the requirements for studying the emission spectrum of pulsed high-voltage discharge in high-precision fields or network terminals. The proposed architecture system is described and the target group gets the useful enlightenment in many fields including engineering remote users, specifically in control- and automation-related tasks.

  5. Differential Hall-sensor Pulsed Eddy Current Probe for the Detection of Wall thinning in an Insulated Stainless Steel Pipe

    International Nuclear Information System (INIS)

    Park, D. G.; Angani, Chandra S.; Cheong, Y. M.; Kim, C. G.

    2010-01-01

    The local wall thinning is one of the most important factors to limit the life-extension of large structures, such as the pipe lines in the NPPs. The pipelines are covered with a thermal insulator for low thermal loss. The PEC testing is the promising technological approach to the NDT, and it has been principally developed for the measurement of surface flaws, subsurface flaws and corrosion. In the pulsed eddy current (PEC) technique, the excitation coil is driven by repeated pulses. According to the skin - depth relationship multiple frequency components penetrate to different depths, hence the PEC technique has the potential for bringing up deeper information about the tested sample. Because of the potential advantages of the PEC, prevalent investigations on this technique have been done. In the present study a differential probe which is used in the Pulsed Eddy Current (PEC) system has been fabricated for the detection of wall thinning of insulated pipelines in a nuclear power plant (NPP). This technique can be used as a potential tool to detect the corrosion or the wall thinning of the pipelines without removing the insulation

  6. Thermal-mechanical simulation of high-current pulsed electron beam surface modification process of pure aluminum

    International Nuclear Information System (INIS)

    Zou Jianxin; Qin Ying; Wu Aimin; Hao Shengzhi; Wang Xiaogang; Dong Chuang

    2004-01-01

    A mathematical physics model is established to describe the surface modification process of High Current Pulsed Electron Beams (HCPEB) of pure aluminum alloy. Computer simulation is used to reveal the phenomena of fast heating and cooling, melting, solidification, evaporation, and thermal stress wave associated with the HCPEB bombardment. The calculated melting depth is about 1-10 μm, which is close to the experimental results. The evaporated layer is at nanometer level, which can be omitted in the calculation of temperature field. The thermal stress wave, though as weak as about 0.1 MPa in peak amplitude (proportional to pulsed energy density), has strong impacts on material's structure and properties. (authors)

  7. Direct transformation of solar energy into three-phase current for technical uses

    Energy Technology Data Exchange (ETDEWEB)

    von Hacht, G [Ingenieurbuero Opto-Sensor-Technik, Frankfurt am Main (Germany, F.R.)

    1977-08-01

    The author proposes a method which may increase the 15% efficiency of present solar plants. In principle, the device consists of an optical waveguide tube containing a chain of solar elements. The tube serves as conductive wire for the primary coil of an a.c. or three-phase current transformer. The 50 Hz cycle of the a.c. or three-phase current is generated by rotor or cylindrical diaphragms and/or electronic pilot/thyristor control. The solar energy is focussed axially and/or vertically to the axis of the optical waveguide tube. The light going through the optical waveguide tube makes it possible for solar elements to be equipped with light-sensitive layers on both sides instead of just on one side, as until now. This means a higher efficiency than for conventional solar elements exposed to light only on one side. In addition, the optical waveguide tube is designed in its length as Fabry-Perot resonator. This way, it may also be used as a gas laser. The light generated in this gas laser would multiply the luminous intensity which again acts on the two light-sensitive sides of the solar elements, thus again increasing their efficiency.

  8. Dead time of different neutron detectors associated with a pulsed electronics with current collection

    International Nuclear Information System (INIS)

    Bacconnet, Eugene; Duchene, Jean; Duquesne, Henry; Schmitt, Andre

    1968-01-01

    After having outlined that the development of fast neutron reactor physics, notably kinetics, requires highly efficient neutron detectors and pulse measurement chains able to cope with high counting rates, the authors report the measurement of dead time of various neutron detectors which are used in the experimental study of fast neutron reactors. They present the SAITB 1 electronic measurement set, its components, its general characteristics, the protected connection between the detector and the electronics. They present and report the experiment: generalities about detector location and measurements, studied detectors (fission chambers, boron counters), and report the exploitation of the obtained results (principle, data, high-threshold counting gain) [fr

  9. Generation efficiency of single-photon current pulses in the Geiger mode of silicon avalanche photodiodes

    International Nuclear Information System (INIS)

    Verkhovtseva, A. V.; Gergel, V. A.

    2009-01-01

    Statistical fluctuations of the avalanche's multiplication efficiency were studied as applied to the single-photon (Geiger) mode of avalanche photodiodes. The distribution function of partial multiplication factors with an anomalously wide (of the order of the average) dispersion was obtained. Expressions for partial feedback factors were derived in terms of the average gain and the corresponding dependences on the diode's overvoltage were calculated. Final expressions for the photon-electric pulse's conversion were derived by averaging corresponding formulas over the coordinate of initiating photoelectron generation using the functions of optical photon absorption in silicon.

  10. Domino Platform: PVD Coaters for Arc Evaporation and High Current Pulsed Magnetron Sputtering

    International Nuclear Information System (INIS)

    Vetter, J; Müller, J; Erkens, G

    2012-01-01

    AlTiN and CrN coatings were deposited in hybrid DOMINO platforms by magnetron sputtering (DC-MS, DC-MS+HCP-MS, HCP-MS) and vacuum arc evaporation. The ion cleaning was done by the AEGD process. The coating rates and the energy efficiency of both deposition processes were compared. The roughness effects of the different coating types were discussed. Preliminary results of the change of pulse characteristics during simultaneously running of HCP-MS plus vacuum arc evaporation are shown.

  11. Electromagnetic analysis of a superconducting transformer for high current characterization of cable in conduit conductors in background magnetic field

    Science.gov (United States)

    Wu, Xiangyang; Tan, Yunfei; Fang, Zhen; Jiang, Donghui; Chen, Zhiyou; Chen, Wenge; Kuang, Guangli

    2017-10-01

    A large cable-in-conduit-conductor (CICC) test facility has been designed and fabricated at the High Magnetic Field Laboratory of the Chinese Academy of Sciences (CHMFL) in order to meet the test requirement of the conductors which are applied to the future fusion reactor. The critical component of the test facility is an 80 kA superconducting transformer which consists of a multi-turn primary coil and a minor-turn secondary coil. As the current source of the conductor samples, the electromagnetic performance of the superconducting transformer determines the stability and safety of the test facility. In this paper, the key factors and parameters, which have much impact on the performance of the transformer, are analyzed in detail. The conceptual design and optimizing principles of the transformer are discussed. An Electromagnetic-Circuit coupled model built in ANSYS Multiphysics is successfully used to investigate the electromagnetic characterization of the transformer under the dynamic operation condition.

  12. Influence of sintering temperature on the properties of pulsed electric current sintered hybrid coreshell powders

    Czech Academy of Sciences Publication Activity Database

    Mahmed, N.; Larismaa, J.; Heczko, Oleg; Cura, M.E.; Hannula, S.-P.

    2013-01-01

    Roč. 33, č. 12 (2013), s. 2233-2239 ISSN 0955-2219 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional support: RVO:68378271 Keywords : sintering * silver * iron oxide * SiO 2 * phase transformation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.307, year: 2013 http://dx.doi.org/10.1016/j.jeurceramsoc.2012.12.023

  13. An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers.

    Science.gov (United States)

    Li, Zhen-hua; Li, Hong-bin; Zhang, Zhi

    2013-07-01

    Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Based on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class.

  14. An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

    International Nuclear Information System (INIS)

    Li, Zhen-hua; Li, Hong-bin; Zhang, Zhi

    2013-01-01

    Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Based on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class

  15. Electrochemically enhanced reduction of hexavalent chromium in contaminated clay: Kinetics, energy consumption, and application of pulse current

    DEFF Research Database (Denmark)

    Sun, Tian Ran; Pamukcu, Sibel; Ottosen, Lisbeth M.

    2015-01-01

    the dependency of reaction rate on energy consumption. A modified electrophoresis cell with platinum wires as working electrodes was used to run experiments. Results showed that the reduction rate of Cr(VI) was significantly increased by application of current with the pseudo-first-order rate constant kpse from......,Fe)(OH)3] precipitates. XRD analysis suggested that the [(Cr,Fe)(OH)3] formed at the clay surface and grew into the pore fluid. SEM-EDX results indicated that the overall Fe(III):Cr(III) ratio of the precipitates was approximately 1.26:1. Application of pulse current decreased the non-productive energy......Electrochemically enhanced reduction of Cr(VI) in clay medium is a technique based on inputting extra energy into the clay to drive the favorable redox reaction. In this study, the reducing reagent Fe(II) was transported into Cr(VI) spiked kaolinite clay by direct current to investigate...

  16. Ozone and dinitrogen monoxide production in atmospheric pressure air dielectric barrier discharge plasma effluent generated by nanosecond pulse superimposed alternating current voltage

    Science.gov (United States)

    Takashima, Keisuke; Kaneko, Toshiro

    2017-06-01

    The effects of nanosecond pulse superposition to alternating current voltage (NS + AC) on the generation of an air dielectric barrier discharge (DBD) plasma and reactive species are experimentally studied, along with measurements of ozone (O3) and dinitrogen monoxide (N2O) in the exhausted gas through the air DBD plasma (air plasma effluent). The charge-voltage cycle measurement indicates that the role of nanosecond pulse superposition is to induce electrical charge transport and excess charge accumulation on the dielectric surface following the nanosecond pulses. The densities of O3 and N2O in NS + AC DBD are found to be significantly increased in the plasma effluent, compared to the sum of those densities generated in NS DBD and AC DBD operated individually. The production of O3 and N2O is modulated significantly by the phase in which the nanosecond pulse is superimposed. The density increase and modulation effects by the nanosecond pulse are found to correspond with the electrical charge transport and the excess electrical charge accumulation induced by the nanosecond pulse. It is suggested that the electrical charge transport by the nanosecond pulse might result in the enhancement of the nanosecond pulse current, which may lead to more efficient molecular dissociation, and the excess electrical charge accumulation induced by the nanosecond pulse increases the discharge coupling power which would enhance molecular dissociation.

  17. Dilution and Ferrite Number Prediction in Pulsed Current Cladding of Super-Duplex Stainless Steel Using RSM

    Science.gov (United States)

    Eghlimi, Abbas; Shamanian, Morteza; Raeissi, Keyvan

    2013-12-01

    Super-duplex stainless steels have an excellent combination of mechanical properties and corrosion resistance at relatively low temperatures and can be used as a coating to improve the corrosion and wear resistance of low carbon and low alloy steels. Such coatings can be produced using weld cladding. In this study, pulsed current gas tungsten arc cladding process was utilized to deposit super-duplex stainless steel on high strength low alloy steel substrates. In such claddings, it is essential to understand how the dilution affects the composition and ferrite number of super-duplex stainless steel layer in order to be able to estimate its corrosion resistance and mechanical properties. In the current study, the effect of pulsed current gas tungsten arc cladding process parameters on the dilution and ferrite number of super-duplex stainless steel clad layer was investigated by applying response surface methodology. The validity of the proposed models was investigated by using quadratic regression models and analysis of variance. The results showed an inverse relationship between dilution and ferrite number. They also showed that increasing the heat input decreases the ferrite number. The proposed mathematical models are useful for predicting and controlling the ferrite number within an acceptable range for super-duplex stainless steel cladding.

  18. Sputter crater formation in the case of microsecond pulsed glow discharge in a Grimm-type source. Comparison of direct current and radio frequency modes

    Science.gov (United States)

    Efimova, Varvara; Hoffmann, Volker; Eckert, Jürgen

    2012-10-01

    Depth profiling with pulsed glow discharge is a promising technique. The application of pulsed voltage for sputtering reduces the sputtering rate and thermal stress and hereby improves the analysis of thin layered and thermally fragile samples. However pulsed glow discharge is not well studied and this limits its practical use. The current work deals with the questions which usually arise when the pulsed mode is applied: Which duty cycle, frequency and pulse length must be chosen to get the optimal sputtering rate and crater shape? Are the well-known sputtering effects of the continuous mode valid also for the pulsed regime? Is there any difference between dc and rf pulsing in terms of sputtering? It is found that the pulse length is a crucial parameter for the crater shape and thermal effects. Sputtering with pulsed dc and rf modes is found to be similar. The observed sputtering effects at various pulsing parameters helped to interpret and optimize the depth resolution of GD OES depth profiles.

  19. Metallurgical characterization of pulsed current gas tungsten arc, friction stir and laser beam welded AZ31B magnesium alloy joints

    International Nuclear Information System (INIS)

    Padmanaban, G.; Balasubramanian, V.

    2011-01-01

    This paper reports the influences of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on mechanical and metallurgical properties of AZ31B magnesium alloy. Optical microscopy, scanning electron microscopy, transmission electron microscopy and X-Ray diffraction technique were used to evaluate the metallurgical characteristics of welded joints. LBW joints exhibited superior tensile properties compared to FSW and PCGTAW joints due to the formation of finer grains in weld region, higher fusion zone hardness, the absence of heat affected zone, presence of uniformly distributed finer precipitates in weld region.

  20. Ventricular repolarization time, location of pacing stimulus and current pulse amplitude conspire to determine arrhythmogenicity in mice

    DEFF Research Database (Denmark)

    Speerschneider, T; Grubb, Søren Jahn; Olesen, S P

    2017-01-01

    ) were measured in isolated hearts using floating microelectrodes. RESULTS: Proarrhythmia in WT and KChIP2(-/-) was not sensitive to changes in refractory periods. Action potentials were longer in KChIP2(-/-) hearts compared to WT hearts. Isolated WT hearts had large apico-basal dispersion...... of repolarization time, whereas hearts from KChIP2(-/-) mice had large left-to-right ventricular dispersion of repolarization time. Pacing from the right ventricle in KChIP2(-/-) mice in vivo revealed significant lower current pulse amplitudes needed to induce arrhythmias in these mice. CONCLUSION: Large...

  1. Outlook for the use of microsecond plasma opening switches to generate high-power nanosecond current pulses

    International Nuclear Information System (INIS)

    Dolgachev, G.I.; Maslennikov, D.D.; Ushakov, A.G.

    2006-01-01

    Paper deals with a phenomenon of current breaking in a conducting plasma volume of plasma opening switchers with a nanosecond time of energy initiation and their application in high-power generators. One determined the conditions to ensure megavolt voltages under the erosion mode making use of external applied magnetic field to ensure magnetic insulation of gap of plasma opening switchers. One studied the peculiar features of application of plasma opening switchers under 5-6 MV voltages to ensure X-ray and gamma-radiation pulses [ru

  2. Behavior of impurity ion velocities during the pulsed poloidal current drive in the Madison symmetric torus reversed-field pinch

    International Nuclear Information System (INIS)

    Sakakita, Hajime; Craig, Darren; Anderson, Jay K.; Chapman, Brett E.; Den-Hartog, Daniel J.; Prager, Stewart C.; Biewer, Ted M.; Terry, Stephen D.

    2003-01-01

    We report on passive measurements of impurity ion velocities during the pulsed poloidal current drive (PPCD) in the Madison Symmetric Torus reversed-field pinch. During PPCD, the electron temperature increased and a sudden reduction of magnetic fluctuations was observed. For this change, we have studied whether plasma velocity is affected. Plasma rotation is observed to decrease during PPCD. From measurements of line intensities for several impurities at 10 poloidal chords, it is found that the impurity line emission shifts outward. The ion temperature of impurities is reasonably connected to that measured by charge exchange recombination spectroscopy from core to edge. (author)

  3. High precision electron beam diagnostic system for high current long pulse beams

    International Nuclear Information System (INIS)

    Chen, Y J; Fessenden, T; Holmes, C; Nelson, S D; Selchow, N.

    1999-01-01

    As part of the effort to develop a multi-axis electron beam transport system using stripline kicker technology for DARHT II applications, it is necessary to precisely determine the position and extent of long high energy beams (6-40 MeV, 1-4 kA, 2 microseconds) for accurate position control. The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (<20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt measurements performed using capacitive pick-off probes. Likewise, transmission line traveling wave probes have problems with multi-bounce effects due to these longer pulse widths. Finally, the high energy densities experienced in these applications distort typical foil beam position measurements

  4. Current regimen of pulse therapy for pemphigus: Minor modifications, improved results

    Directory of Open Access Journals (Sweden)

    Pasricha J

    2008-01-01

    Full Text Available Background: If administered properly, dexamethasone cyclophosphamide pulse (DCP therapy has the potential to effect lifelong recovery from pemphigus. Aims: The objective of this paper is to highlight various parameters of DCP therapy and also, to report the effects of a few modifications in the regimen. Methods: An analysis of 123 patients treated with the DCP/DP regimen over a period of five years (1998 to 2002 is presented here. Seventeen patients who did not start/continue the treatment and three patients who died during the treatment have been excluded from the analysis. Twenty patients who had not yet started families were given only dexamethasone pulses (DPs while 103 patients received DCPs. Low dose (50 mg/day cyclophosphamide was used as in the standard regimen. The three modifications introduced into the regimen were: (1 an additional daily dose of oral betamethasone sufficient to control the disease activity during phase I, which was progressively tapered off completely as the patient recovered, (2 use of systemic antibiotics if the patient had skin lesions, and oral anti-candida drugs if the patient had oral ulcers until complete healing, and (3 insistence on thorough cleaning of the skin and scalp with a normal soap and shampoo, and proper maintenance of oral hygiene in spite of skin/mucosal lesions. The regimen consisted of DCP/DP repeated in exactly 28-day cycles, along with 50 mg cyclophosphamide per day, insistence on completing the treatment and avoiding irregular pulses in all patients. The number of DCPs/DPs during phase I varied in different patients depending upon the dose of betamethasone used and the rate of recovery, but phase II (nine DCPs/DPs in exactly 28-day cycles along with 50 mg cyclophosphamide per day and phase III (only 50 mg cyclophosphamide per day was fixed at nine months each. This was followed by posttreatment follow-up (phase IV. Results: At present, all the patients are in complete remission. The

  5. Modelling and Optimization of Four-Segment Shielding Coils of Current Transformers.

    Science.gov (United States)

    Gao, Yucheng; Zhao, Wei; Wang, Qing; Qu, Kaifeng; Li, He; Shao, Haiming; Huang, Songling

    2017-05-26

    Applying shielding coils is a practical way to protect current transformers (CTs) for large-capacity generators from the intensive magnetic interference produced by adjacent bus-bars. The aim of this study is to build a simple analytical model for the shielding coils, from which the optimization of the shielding coils can be calculated effectively. Based on an existing stray flux model, a new analytical model for the leakage flux of partial coils is presented, and finite element method-based simulations are carried out to develop empirical equations for the core-pickup factors of the models. Using the flux models, a model of the common four-segment shielding coils is derived. Furthermore, a theoretical analysis is carried out on the optimal performance of the four-segment shielding coils in a typical six-bus-bars scenario. It turns out that the "all parallel" shielding coils with a 45° starting position have the best shielding performance, whereas the "separated loop" shielding coils with a 0° starting position feature the lowest heating value. Physical experiments were performed, which verified all the models and the conclusions proposed in the paper. In addition, for shielding coils with other than the four-segment configuration, the analysis process will generally be the same.

  6. Current and future prospects for the use of pulsed electric field in the meat industry.

    Science.gov (United States)

    Bhat, Zuhaib F; Morton, James D; Mason, Susan L; Bekhit, Alaa El-Din A

    2018-02-02

    Pulsed electric field (PEF) is a novel non-thermal technology that has recently attracted the attention of meat scientists and technologists due to its ability to modify membrane structure and enhance mass transfer. Several studies have confirmed the potential of pulsed electric field for improving meat tenderness in both pre-rigor and post-rigor muscles during aging. However, there is a high degree of variability between studies and the underlying mechanisms are not clearly understood. While some studies have suggested physical disruption as the main cause of PEF induced tenderness, enzymatic nature of the tenderization seems to be the most plausible mechanism. Several studies have suggested the potential of PEF to mediate the tenderization process due to its membrane altering properties causing early release of calcium ions and early activation of the calpain proteases. However, experimental research is yet to confirm this postulation. Recent studies have also reported increased post-mortem proteolysis in PEF treated muscles during aging. PEF has also been reported to accelerate curing, enhance drying and reduce the numbers of both pathogens and spoilage organisms in meat, although that demands intense processing conditions. While tenderization, meat safety and accelerated curing appears to be the areas where PEF could provide attractive options in meat processing, further research is required before the application of PEF becomes a commercial reality in the meat industry. It needs to deal with carcasses which vary biochemically and in composition (muscle, fat, and bones). This review critically evaluates the published reports on the topic with the aim of reaching a clear understanding of the possible applications of PEF in the meat sector in addition to providing some insight on critical issues that need to be addressed for the technology to be a practical option for the meat industry.

  7. Current signal processing-based techniques\\ud for transformer protection

    OpenAIRE

    Etumi, Adel

    2016-01-01

    Transformer is an expensive device and one of the most important parts in a power\\ud system. Internal faults can cause a transformer to fail and thus, it is necessary for it\\ud to be protected from these faults. Protection doesn’t mean that it prevents damage to\\ud the protected transformer but it is to minimize the damage to the transformer as\\ud much as possible, which consequently minimizes the subsequent outage time and\\ud repair cost. Therefore, fast and reliable protection system should...

  8. Optimization of Experimental Conditions of the Pulsed Current GTAW Parameters for Mechanical Properties of SDSS UNS S32760 Welds Based on the Taguchi Design Method

    Science.gov (United States)

    Yousefieh, M.; Shamanian, M.; Saatchi, A.

    2012-09-01

    Taguchi design method with L9 orthogonal array was implemented to optimize the pulsed current gas tungsten arc welding parameters for the hardness and the toughness of super duplex stainless steel (SDSS, UNS S32760) welds. In this regard, the hardness and the toughness were considered as performance characteristics. Pulse current, background current, % on time, and pulse frequency were chosen as main parameters. Each parameter was varied at three different levels. As a result of pooled analysis of variance, the pulse current is found to be the most significant factor for both the hardness and the toughness of SDSS welds by percentage contribution of 71.81 for hardness and 78.18 for toughness. The % on time (21.99%) and the background current (17.81%) had also the next most significant effect on the hardness and the toughness, respectively. The optimum conditions within the selected parameter values for hardness were found as the first level of pulse current (100 A), third level of background current (70 A), first level of % on time (40%), and first level of pulse frequency (1 Hz), while they were found as the second level of pulse current (120 A), second level of background current (60 A), second level of % on time (60%), and third level of pulse frequency (5 Hz) for toughness. The Taguchi method was found to be a promising tool to obtain the optimum conditions for such studies. Finally, in order to verify experimental results, confirmation tests were carried out at optimum working conditions. Under these conditions, there were good agreements between the predicted and the experimental results for the both hardness and toughness.

  9. Pulse width modulated buck-boost five-level current source inverters

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Gao, F.; Loh, P.C.

    2008-01-01

    , resulting in the natural balance of input current. For maintaining the normalized volt-sec average unchanged, the alternative phase opposition disposition (APOD) modulation scheme with typical gating signal mapping technique from voltage source inverter (VSI) to CSI can be assumed to control the five......This paper presents new five-level current source inverters (CSIs) with voltage/current buck-boost capability. Being different from the existing multilevel CSI, the proposed CSIs were first designed to regulate the flowing path of dc input current by controlling two additional active switches......-level buck-boost CSIs. Next by observing the hidden current charging path during inductive charging interval under APOD modulation, it is noted that the buck-boost five-level CSI can then be further modified with lesser active component without degrading output performance. To verify the theoretical findings...

  10. Transient interaction model of electromagnetic field generated by lightning current pulses and human body

    International Nuclear Information System (INIS)

    Iváncsy, T; Kiss, I; Tamus, Z Á; Szücs, L

    2015-01-01

    The lightning current generates time-varying magnetic field near the down-conductor and the down-conductors are mounted on the wall of the buildings where residential places might be situated. It is well known that the rapidly changing magnetic fields can generate dangerous eddy currents in the human body.The higher duration and gradient of the magnetic field can cause potentially life threatening cardiac stimulation. The coupling mechanism between the electromagnetic field and the human body is based on a well-known physical phenomena (e.g. Faradays law of induction). However, the calculation of the induced current is very complicated because the shape of the organs is complex and the determination of the material properties of living tissues is difficult, as well. Our previous study revealed that the cardiac stimulation is independent of the rising time of the lightning current and only the peak of the current counts.In this study, the authors introduce an improved model of the interaction of electromagnetic fields of lighting current near down-conductor and human body. Our previous models are based on the quasi stationer field calculations, the new improved model is a transient model. This is because the magnetic field around the down-conductor and in the human body can be determined more precisely, therefore the dangerous currents in the body can be estimated. (paper)

  11. Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin-orbit coupling.

    Science.gov (United States)

    Sun, Dali; van Schooten, Kipp J; Kavand, Marzieh; Malissa, Hans; Zhang, Chuang; Groesbeck, Matthew; Boehme, Christoph; Valy Vardeny, Z

    2016-08-01

    Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics applications. Owing to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation. This strong ISHE enables us to investigate a variety of OSECs ranging from π-conjugated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the curvature of the molecule's surface. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin currents at room temperature, and paves the way for spin orbitronics in plastic materials.

  12. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  13. Long pulse FRC sustainment with enhanced edge driven rotating magnetic field current drive

    International Nuclear Information System (INIS)

    Hoffman, A.L.; Guo, H.Y.; Miller, K.E.; Milroy, R.D.

    2005-01-01

    FRCs have been formed and sustained for up to 50 normal flux decay times by Rotating Magnetic Fields (RMF) in the TCS experiment. For these longer pulse times a new phenomenon has been observed: switching to a higher performance mode delineated by shallower RMF penetration, higher ratios of generated poloidal to RMF drive field, and lower overall plasma resistivity. This global data is not explainable by previous RMF theory based on uniform electron rotational velocities or by numerical calculations based on uniform plasma resistivity, but agrees in many respects with new calculations made using strongly varying resistivity profiles. In order to more realistically model RMF driven FRCs with such non-uniform resistivity profiles, a double rigid rotor model has been developed with separate inner and outer electron rotational velocities and resistivities. The results of this modeling suggest that the RMF drive results in very high resistivity in a narrow edge layer, and that the higher performance mode is characterized by a sharp reduction in resistivity over the bulk of the FRC. (author)

  14. Improved corrosion behavior of nanocrystalline zinc produced by pulse-current electrodeposition

    International Nuclear Information System (INIS)

    Youssef, Kh.M.S.; Koch, C.C.; Fedkiw, P.S.

    2004-01-01

    Pulse electrodeposition was used to produce nanocrystalline (nc) zinc from zinc chloride electrolyte with polyacrylamide and thiourea as additives. Field emission scanning electron microscopy (FESEM) was used to study the grain size and surface morphology of the deposits and X-ray diffraction was used to examine their preferred orientation. Corrosion behavior of the electrodeposited nc zinc in comparison with electrogalvanized (EG) steel in de-aerated 0.5 N NaOH solution was studied using potentiodynamic polarization and impedance measurements. A scanning electron microscope (SEM) was used to characterize the surface morphology of the EG steel before corrosion testing. Surface morphologies of nc zinc deposits and EG steel were also studied after potentiondynamic polarization by SEM. Nanocrystalline zinc (56 nm) with random orientation was produced. The estimated corrosion rate of nc zinc was found to be about 60% lower than that of EG steel, 90 and 229 μA/cm 2 , respectively. The surface morphology of corroded nc zinc was characterized by discrete etch pits, however, uniform corrosion was obtained after potentiodynamic polarization of EG steel. The passive film formed on the nc zinc surface seems to be a dominating factor for the corrosion behavior observed

  15. Method of measuring the current density distribution and emittance of pulsed electron beams

    International Nuclear Information System (INIS)

    Schilling, H.B.

    1979-07-01

    This method of current density measurement employs an array of many Faraday cups, each cup being terminated by an integrating capacitor. The voltages of the capacitors are subsequently displayed on a scope, thus giving the complete current density distribution with one shot. In the case of emittance measurements, a moveable small-diameter aperture is inserted at some distance in front of the cup array. Typical results with a two-cathode, two-energy electron source are presented. (orig.)

  16. High-current-density electrodeposition using pulsed and constant currents to produce thick CoPt magnetic films on silicon substrates

    Science.gov (United States)

    Ewing, Jacob; Wang, Yuzheng; Arnold, David P.

    2018-05-01

    This paper investigates methods for electroplating thick (>20 μm), high-coercivity CoPt films using high current densities (up to 1 A/cm2) and elevated bath temperatures (70 °C). Correlations are made tying current-density and temperature process parameters with plating rate, elemental ratio and magnetic properties of the deposited CoPt films. It also investigates how pulsed currents can increase the plating rate and film to substrate adhesion. Using 500 mA/cm2 and constant current, high-quality, dense CoPt films were successfully electroplated up to 20 μm thick in 1 hr on silicon substrates (0.35 μm/min plating rate). After standard thermal treatment (675°C, 30 min) to achieve the ordered L10 crystalline phase, strong magnetic properties were measured: coercivities up 850 kA/m, remanences >0.5 T, and maximum energy products up to 46 kJ/m3.

  17. High-temperature performance of MoS{sub 2} thin-film transistors: Direct current and pulse current-voltage characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C.; Samnakay, R.; Balandin, A. A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory (NDL), Department of Electrical Engineering, Bourns College of Engineering, University of California—Riverside, Riverside, California 92521 (United States); Phonon Optimized Engineered Materials (POEM) Center, Materials Science and Engineering Program, University of California—Riverside, Riverside, California 92521 (United States); Rumyantsev, S. L. [Department of Electrical, Computer, and Systems Engineering, Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Shur, M. S. [Department of Electrical, Computer, and Systems Engineering, Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-02-14

    We report on fabrication of MoS{sub 2} thin-film transistors (TFTs) and experimental investigations of their high-temperature current-voltage characteristics. The measurements show that MoS{sub 2} devices remain functional to temperatures of at least as high as 500 K. The temperature increase results in decreased threshold voltage and mobility. The comparison of the direct current (DC) and pulse measurements shows that the direct current sub-linear and super-linear output characteristics of MoS{sub 2} thin-films devices result from the Joule heating and the interplay of the threshold voltage and mobility temperature dependences. At temperatures above 450 K, a kink in the drain current occurs at zero gate voltage irrespective of the threshold voltage value. This intriguing phenomenon, referred to as a “memory step,” was attributed to the slow relaxation processes in thin films similar to those in graphene and electron glasses. The fabricated MoS{sub 2} thin-film transistors demonstrated stable operation after two months of aging. The obtained results suggest new applications for MoS{sub 2} thin-film transistors in extreme-temperature electronics and sensors.

  18. Observation of bulk-ion heating in a tokamak plasma by application of positive and negative current pulses in TRIAM-1

    Energy Technology Data Exchange (ETDEWEB)

    Toi, K; Hiraki, N; Nakamura, K; Mitarai, O; Kawai, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1980-09-01

    A positive of negative current pulse induced by a pulsed toroidal electric field much higher than the Dreicer field increases the bulk-ion temperature of the plasma centre two to three times, without macroscopic plasma destruction. The decay time of the raised ion temperature agrees well with the prediction from neoclassical transport theory. The magnitude of the positive current pulse is limited by violent current disruption, and that of the negative current by a lack of MHD equilibrium which is due to a marked reduction of the total plasma current. The relevant current-driven instabilities in the turbulent heating of a tokamak plasma, skin heating and inward transfer of the energy deposition in the skin layer are briefly discussed.

  19. Application in low level counting of corona counters operating in voltage or current pulse recording modes

    International Nuclear Information System (INIS)

    Oravec, J.; Usacev, S.; Duka-Zojomi, A.; Sitar, B.; Benovic, D.; Holy, K.

    1977-01-01

    The advantages of current or voltage modes of recording are discussed. It appears that the current mode is more advantageous in measurements of rare events caused by highly ionizing particles on a high background of weakly ionizing particles. A 2.3 litre multiwire corona counter was used for the determination of 226 Ra content in drinking water. The 226 Ra content was estimated by measuring 222 Rn activity. The minimum measurable activity of the system was 0.07 pCi/l of water. (author)

  20. Control algorithms based on the active and non-active currents for a UPQC without series transformers

    OpenAIRE

    Correa Monteiro, Luis Fernando; Aredes, Mauricio; Pinto, J. G.; Exposto, Bruno; Afonso, João L.

    2016-01-01

    This study presents control algorithms for a new unified power quality conditioner (UPQC) without the series transformers that are frequently used to make the insertion of the series converter of the UPQC between the power supply and the load. The behaviour of the proposed UPQC is evaluated in presence of voltage imbalances, as well as under non-sinusoidal voltage-and current conditions. The presented algorithms derive from the concepts involving the active and non-active currents, together w...

  1. A Trinity of Transformation, Europeanisation, and Democratisation? Current Research on Citizenship Education in Europe

    OpenAIRE

    Reinhold Hedtke; Tatjana Zimenkova; Thorsten Hippe

    2008-01-01

    Although a lot of stock-taking research on citizenship education in European countries has already be done, some key features  of citizenship education especially in transformation countries are not understood as yet. The authors briefly outline the state of the art and criticize its main shortcomings. As a result, they suggest a research agenda to enhance the knowledge about citizenship education with respect to its interconnectedness with processes of transformation and to its embeddedness ...

  2. Simulation of High-current Pulse Effect on the Electrode with Nonlinear Material Characteristics and Phase Transitions Taken into Account

    Directory of Open Access Journals (Sweden)

    R. V. Arutjunjan

    2016-01-01

    Full Text Available The article investigates the thermal and electrical processes when heating the metal electrode by a high current pulse. The aim is to understand an impact nature of the nonlinearities of thermal parameters, the phase transitions of melting and evaporation, and the type of boundary conditions in the current spot. To solve the problem was formulated a mathematical model, and were also developed a finite-difference method and computer programmes which allow an effective computer simulations of thermal and electrical processes under the high current pulse impact on the metal electrodes. The Stefan problem is solved by the through "enthalpy" method. Calculation of the electric field is performed by Seidel iteration. Thermal and current balance and comparison with solution results of model problems allow computer error monitoring.The work involved a series of calculations for an informative case of iron. It enabled to find a significant influence of the nonlinearities of thermal parameters, the phase transitions of melting and evaporation, the type of boundary conditions on the values of the temperature and electric fields, especially in the vicinity of the current spot. The presence of high current density and temperature, respectively, in the vicinity of the current spot edge confirms the well-known hypothesis about the causes of contact welding on the edges of the contact area. It has been found that the impact of losses on radiation and convection cooling is negligible. The article continues and complements the well-known research in the theory of electrical contacts and welding processes based on detailed consideration of the electrode material properties, the nonlinearities, and a type of boundary conditions for temperature and electric fields.The results can be used in the practice in research and design of electrical machines and other electrical devices.The study has revealed the need to improve the enthalpy finite- difference method for

  3. Optimization of the pulsed current gas tungsten arc welding (PCGTAW) parameters for corrosion resistance of super duplex stainless steel (UNS S32760) welds using the Taguchi method

    International Nuclear Information System (INIS)

    Yousefieh, M.; Shamanian, M.; Saatchi, A.

    2011-01-01

    Research highlights: → Among the four factors and three levels tested, it was concluded that the pulse current had the most significant effect on the pitting potential and the background current had the next most significant effect. The effects of pulse frequency and % on time are less important when compared to the other factors. → The percentage contributions of the pulse current, the background current, % on time, and pulse frequency to the corrosion resistance are 66.28%, 25.97%, 2.71% and 5.04%, respectively. → The optimum conditions within the selected parameter values were found as the second level of pulse current (120 A), second level of background current (60 A), third level of % on time (80%) and third level of pulse frequency (5 Hz). → The confirmation test was carried out at optimum working conditions. Pitting potential was increased to 1.06 V SCE by setting the control factors. Predicted (1.04 V SCE ) and observed (1.06 V SCE ) pitting potential values are close to each other, which are the highest values obtained in the present study. - Abstract: In the present work, a design of experiment (DOE) technique, the Taguchi method, has been used to optimize the pulsed current gas tungsten arc welding (PCGTAW) parameters for the corrosion resistance of super duplex stainless steel (UNS S32760) welds. A L 9 (3 4 ) orthogonal array (OA) of Taguchi design which involves nine experiments for four parameters (pulse current, background current, % on time, pulse frequency) with three levels was used. Corrosion resistance in 3.5%NaCl solution was evaluated by anodic polarization tests at room temperature. Analysis of variance (ANOVA) is performed on the measured data and S/N (signal to noise) ratios. The higher the better response category was selected to obtain optimum conditions. The optimum conditions providing the highest pitting potential were estimated. The optimum conditions were found as the second level of pulse current (120 A), second level of

  4. Preliminary results of a battery-based, multi megawatt 200 kA pulsed power supply.

    NARCIS (Netherlands)

    Karthaus, W.; Kolkert, W.J.; Nowee, J.

    1989-01-01

    A pulsed power supply consisting of a fast discharge battery, a switch based on silicon-controlled-rectifier SCR technology, and an energy storage/pulse transformer is discussed. Preliminary results indicate that the battery is capable of discharging current pulses with reproducible peak values of

  5. Neutron measurements in deuterated palladium cathodes subjected to pulsed electrolytic currents

    International Nuclear Information System (INIS)

    Granada, J.R.; Mayer, R.E.; Guido, G.; Florido, P.C.; Patino, N.E.; Gillette, V.H.; Sobehart, L.; Gomez, S.; Larreteguy, A.; Universidad Nacional de Cuyo, San Carlos de Bariloche

    1989-01-01

    We report on neutron measurements performed on electrolytic cells using a high efficiency (22%) detection system in combination with a procedure involving a non-stationary current through the cell's circuit. Under these conditions, neutron production was observed in cells containing LiH dissolved in heavy water with a Palladium cathode. Characteristic patterns showing one or two bumps were obtained in a repeatable fashion, depending on the previous charging history of the cathode. (orig.)

  6. Singularities of current-voltage characteristics of GaAs films fabricated by pulsed ions ablation

    International Nuclear Information System (INIS)

    Kabyshev, A.V.; Konusov, F.V.; Lozhnikov, S.N.; Remnev, G.E.; Saltymakov, M.S.

    2009-01-01

    A singularities and advantages of the optical, photoelectric and electrical properties of GaAs in comparison with other available materials for electronics, for example, silicon allow to manufacture on it base the devices having an advanced characteristics. The GaAs for electronics, obtained from the dense ablation plasma, possess some preferences as compared to material manufactured by traditional methods of vacuum deposition. The electrical characteristics of GaAs produced by chemical deposition were extensively studied. Purpose of this work is investigation the current-voltage characteristics of thin films of GaAs, deposited on polycrystalline corundum (polycor) from plasma forming the power ions bunch and determination of the thermal vacuum annealing effect on photoelectric and electrical properties of films. Peculiarities of optical, photoelectric and current-voltage characteristics of films obtained by ions ablation are determined by deposition conditions and resistance of initial target GaAs. The transitions between the states with low- and high conduction were revealed directly after deposition in films having the optical properties similar to amorphous materials and/or after annealing in films with properties similar to initial target GaAs. Behavior of current-voltage characteristics at vacuum annealing correlates with Schottky barrier height and photosensitivity and is accompanies of the transport mechanism change. The stable properties of films are formed at its dark conduction 10 -10 -10 -8 s and after annealing at T an =600-700 K. (authors)

  7. Pulse radiolysis studies on the formation and transformation of the one-electron reduced intermediate of Kalafungin and an analogue solution

    International Nuclear Information System (INIS)

    Anderson, R.F.; Packer, J.E.; Brimble, A.; Nairn, M.R.

    1996-01-01

    Kalafungin 1 is a member of the pyranonaphthoquinone family of antibiotics which are produced various species of Streptomyces and have in common the benzoisochromanquinone skeleton. Apart from their already documented activity against Gram-positive bacteria, fungi, and mycoplasmas, it has been suggested that in vivo reduction causes a transformation to an active hydroquinone form which functions as a bis-alkylating agent. 2 Moore 2 , 3 has suggested that these pyranonaphthoquinones may exhibit antitumour activity since the proposed mechanism of action resembles that of the anticancer agent mitomycin C 3. 2 . Rapid one-electron reduction of kalafungin 1 and a closely related analogue 2 has been carried out using The University of Auckland's pulse radiolysis facility. Pulsed electrons (4 Gy in 200 ns from a 4 MeV linear accelerator) were delivered to de-aerated aqueous solutions (10 mmol.L -1 phosphate, pH 7.0) containing 0.1 mol.L -1 sodium formate and 50 - 200 μmol.L -1 kalafungin 1 or lactol 2. Radical formation and transformations were followed by time-resolved uv/visible spectrophotometry. The transformations observed are independent of both the concentration of the parent compound and radiation doses (i.e. semiquinone concentration). The accompanying changes in absorption are consistent with the radical centre of the semiquinone species undergoing intramolecular rearrangement onto the fused non-aromatic ring structure of the compound. Possible ring opening mechanisms and the position of radical relocalisation will be discussed, as well as the involvement of radical transformation and redox chemistry in the biological activity of kalafungin1

  8. Effects of a longitudinal magnetic field on current pulses and fast ionization-wave structure

    International Nuclear Information System (INIS)

    Asinovskii, E.I.; Lagar'kov, A.N.; Markovets, V.V.; Rutkevich, I.M.; Ul'yanov, A.M.; Filyugin, I.V.

    1988-01-01

    A longitudinal magnetic field affects the fast ionization-wave structure in a discharge tube surrounded by a metal screen. The field does not alter the wave speed, but the current amplitude is increased. This is explained from a theory for fast-wave propagation in a cylindrical guide containing an axial field. Numerical solutions have been obtained for the stationary nonlinear waves, which are compared with measurements. A theoretical study has been made on the ionization-wave features for large values of the Hall parameter

  9. Formation Mechanism of Micropores on the Surface of Pure Aluminum Induced by High-Current Pulsed Electron Beam Irradiation

    International Nuclear Information System (INIS)

    Zou Yang; Cai Jie; Wan Ming-Zhen; Lv Peng; Guan Qing-Feng

    2011-01-01

    The mechanism of micropores formed on the surface of polycrystalline pure aluminum under high-current pulsed electron beam (HCPEB) irradiation is explained. It is discovered that dispersed micropores with sizes of 0.1–1 μm on the irradiated surface of pure aluminum can be successfully fabricated after HCPEB irradiation. The dominant formation mechanism of the surface micropores should be attributed to the formation of supersaturation vacancies within the near surface during the HCPEB irradiation and the migration of vacancies along grain boundaries and/or dislocations towards the irradiated surface. It is expected that the HCPEB technique will become a new method for the rapid synthesis of surface porous materials. (condensed matter: structure, mechanical and thermal properties)

  10. Simulating the effects of plasma disruption with a 1 MA current pulse in a coaxial test fixture

    International Nuclear Information System (INIS)

    Praeg, W.F.

    1985-01-01

    A test fixture for simulating plasma disruptions, comprising two coaxial cylinders, has been designed for use with Argonne's electromagnetic test facility FELIX. A pulsed power supply drives a half cycle sine wave current of 10 0 A through the test fixture generating fields of -1 . The coaxial structure is 140 cm long, has an outer cylinder with an OD of 78 cm and an inner cylinder with an OD of 8.3 cm. It is surrounded by the FELIX solenoid field of 1 T. This proposed upgrade of the FELIX facility should be useful for testing the effect of plasma disruption on First Wall-Blanket-Shield (FWBS) structures; a future upgrade of the solenoid field to 4 T will allow to simulate reactor conditions even better

  11. Isotopic identification using Pulse Shape Analysis of current signals from silicon detectors: Recent results from the FAZIA collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Pastore, G., E-mail: pastore@fi.infn.it [Dipartimento di Fisica, Università di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); INFN Sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); Gruyer, D. [INFN Sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); Ottanelli, P. [Dipartimento di Fisica, Università di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); INFN Sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); Le Neindre, N. [LPC Caen, Normandie Univ, ENSICAEN, UNICAEN, CNRS/IN2P3, LPC Caen, 14000 Caen (France); Pasquali, G. [Dipartimento di Fisica, Università di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); INFN Sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); Alba, R. [INFN LNS, Via S.Sofia 62, 95123 Catania (Italy); Barlini, S.; Bini, M. [Dipartimento di Fisica, Università di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); INFN Sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); Bonnet, E. [SUBATECH, EMN-IN2P3/CNRS-Université de Nantes, Nantes (France); GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076 Caen Cedex (France); Borderie, B. [Institut de Physique Nucléaire, CNRS-IN2P3, Univ. Paris-Sud, Université Paris-Saclay, F-91406 Orsay Cedex (France); Bougault, R. [LPC Caen, Normandie Univ, ENSICAEN, UNICAEN, CNRS/IN2P3, LPC Caen, 14000 Caen (France); Bruno, M. [INFN, Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy); Casini, G. [INFN Sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Italy); Chbihi, A. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076 Caen Cedex (France); and others

    2017-07-11

    The FAZIA apparatus exploits Pulse Shape Analysis (PSA) to identify nuclear fragments stopped in the first layer of a Silicon-Silicon-CsI(Tl) detector telescope. In this work, for the first time, we show that the isotopes of fragments having atomic number as high as Z∼20 can be identified. Such a remarkable result has been obtained thanks to a careful construction of the Si detectors and to the use of low noise and high performance digitizing electronics. Moreover, optimized PSA algorithms are needed. This work deals with the choice of the best algorithm for PSA of current signals. A smoothing spline algorithm is demonstrated to give optimal results without requiring too much computational resources.

  12. Stress and piezoelectric properties of aluminum nitride thin films deposited onto metal electrodes by pulsed direct current reactive sputtering

    International Nuclear Information System (INIS)

    Dubois, Marc-Alexandre; Muralt, Paul

    2001-01-01

    Polycrystalline aluminum nitride thin films were deposited onto platinum, aluminum, and titanium electrodes by reactive magnetron sputtering in the pulsed direct current mode. The films exhibited all a columnar microstructure and a c-axis texture. The built-in stress and the piezoelectric properties of these films were studied as a function of both the processing conditions and the electrode material. Stress was found to be very much dependent on the growth conditions, and values ranging from strong compression to high tension were observed. The piezoelectric d 33,f coefficient was shown to rely on substrate quality and ionic bombardment: The nucleation surface must be stable with regard to the nitrogen plasma and present a hexagonal symmetry and, on the other hand, enough energy must be delivered to the growing film through ionic bombardment. [copyright] 2001 American Institute of Physics

  13. Simulating the effects of plasma disruption with A 1 MA current pulse in a coaxial test fixture

    International Nuclear Information System (INIS)

    Praeg, W.F.

    1985-01-01

    A test fixture for simulating plasma disruptions, comprising two coaxial cylinders, has been designed for use with Argonne's electromagnetic test facility FELIX. A pulsed power supply drives a half cycle sine wave current of 10 0 A through the test fixture generating fields of -1 . The coaxial structure is 140 cm long, has an outer cylinder with an OD of 78 cm and an inner cylinder with an OD of 8.3 cm. It is surrounded by the FELIX solenoid field of 1 T. This proposed upgrade of the FELIX facility should be useful for testing the effect of plasma disruption on First Wall-Blanket-Shield (FWBS) structures; a future upgrade of the solenoid field to 4 T will allow to simulate reactor conditions even better

  14. Feasibility study of current pulse induced 2-bit/4-state multilevel programming in phase-change memory

    Science.gov (United States)

    Liu, Yan; Fan, Xi; Chen, Houpeng; Wang, Yueqing; Liu, Bo; Song, Zhitang; Feng, Songlin

    2017-08-01

    In this brief, multilevel data storage for phase-change memory (PCM) has attracted more attention in the memory market to implement high capacity memory system and reduce cost-per-bit. In this work, we present a universal programing method of SET stair-case current pulse in PCM cells, which can exploit the optimum programing scheme to achieve 2-bit/ 4state resistance-level with equal logarithm interval. SET stair-case waveform can be optimized by TCAD real time simulation to realize multilevel data storage efficiently in an arbitrary phase change material. Experimental results from 1 k-bit PCM test-chip have validated the proposed multilevel programing scheme. This multilevel programming scheme has improved the information storage density, robustness of resistance-level, energy efficient and avoiding process complexity.

  15. Fabrication and Mechanical Properties of Nanostructured TiC-TiAl by the Pulsed Current Activated Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Bong-Won; Shon, In-Jin [Chonbuk National University, Chonbuk (Korea, Republic of); Kim, Byung-Su [Korea Institute of Geoscience and Mineral Resources, Daejeon (Korea, Republic of); Yoon, Jin-Kook; Hong, Kyung-Tae [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2016-08-15

    TiC-Co or TiC-Ni hard materials have been used for cutting tools. However, the high cost and the low hardness of Ni or Co, and the low corrosion resistance of the TiC-Ni and TiC-Co cermets have generated interest in recent years in using them as alternative binder phases. In this study, TiAl was used as a novel binder and consolidated by the pulsed current activated sintering(PCAS) method. Nanopowders of TiC and TiAl were fabricated using high energy ball milling. Highly dense TiC-TiAl hard materials with a relative density of up to 99.5% were sintered within three min by PCAS. Not only the hardness but also the fracture toughness of the TiC-10 vol%TiAl were better than those of TiC-10 vol%Ni or TiC-10 vol%Co.

  16. Fabrication and Mechanical Properties of Nanostructured TiC-TiAl by the Pulsed Current Activated Sintering

    International Nuclear Information System (INIS)

    Kwak, Bong-Won; Shon, In-Jin; Kim, Byung-Su; Yoon, Jin-Kook; Hong, Kyung-Tae

    2016-01-01

    TiC-Co or TiC-Ni hard materials have been used for cutting tools. However, the high cost and the low hardness of Ni or Co, and the low corrosion resistance of the TiC-Ni and TiC-Co cermets have generated interest in recent years in using them as alternative binder phases. In this study, TiAl was used as a novel binder and consolidated by the pulsed current activated sintering(PCAS) method. Nanopowders of TiC and TiAl were fabricated using high energy ball milling. Highly dense TiC-TiAl hard materials with a relative density of up to 99.5% were sintered within three min by PCAS. Not only the hardness but also the fracture toughness of the TiC-10 vol%TiAl were better than those of TiC-10 vol%Ni or TiC-10 vol%Co.

  17. High-current negative-ion sources for pulsed spallation neutron sources: LBNL workshop, October 1994

    International Nuclear Information System (INIS)

    Alonso, J.R.

    1995-09-01

    The neutron scattering community has endorsed the need for a high-power (1 to 5 MW) accelerator-driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (sub-microsecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 kW source in the UK), and call for a high-current (approx. 100 mA peak) H- source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The I to 5 GeV proton beam is extracted in a single turn and brought to the target-moderator stations. The high current, high duty-factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. The Workshop reported on here, held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H- source technologies, and identified necessary R ampersand D efforts to bridge the gap

  18. Study on lower hybrid current drive efficiency at high density towards long-pulse regimes in Experimental Advanced Superconducting Tokamak

    International Nuclear Information System (INIS)

    Li, M. H.; Ding, B. J.; Zhang, J. Z.; Gan, K. F.; Wang, H. Q.; Zhang, L.; Wei, W.; Li, Y. C.; Wu, Z. G.; Ma, W. D.; Jia, H.; Chen, M.; Yang, Y.; Feng, J. Q.; Wang, M.; Xu, H. D.; Shan, J. F.; Liu, F. K.; Peysson, Y.

    2014-01-01

    Significant progress on both L- and H-mode long-pulse discharges has been made recently in Experimental Advanced Superconducting Tokamak (EAST) with lower hybrid current drive (LHCD) [J. Li et al., Nature Phys. 9, 817 (2013) And B. N. Wan et al., Nucl. Fusion 53, 104006 (2013).]. In this paper, LHCD experiments at high density in L-mode plasmas have been investigated in order to explore possible methods of improving current drive (CD) efficiency, thus to extend the operational space in long-pulse and high performance plasma regime. It is observed that the normalized bremsstrahlung emission falls much more steeply than 1/n e-av (line-averaged density) above n e-av  = 2.2 × 10 19  m −3 indicating anomalous loss of CD efficiency. A large broadening of the operating line frequency (f = 2.45 GHz), measured by a radio frequency (RF) probe located outside the EAST vacuum vessel, is generally observed during high density cases, which is found to be one of the physical mechanisms resulting in the unfavorable CD efficiency. Collisional absorption of lower hybrid wave in the scrape off layer (SOL) may be another cause, but this assertion needs more experimental evidence and numerical analysis. It is found that plasmas with strong lithiation can improve CD efficiency largely, which should be benefited from the changes of edge parameters. In addition, several possible methods are proposed to recover good efficiency in future experiments for EAST

  19. Effect of eddy currents in the toroidal field coils of a tokamak with an air-core transformer

    International Nuclear Information System (INIS)

    Tani, Keiji; Kobayashi, Tomofumi; Tamura, Sanae

    1975-02-01

    The effect of eddy currents in the copper parts of the toroidal field coils is evaluated for a tokamak with the air-core transformer windings located inside the bore of the toroidal field coils. By introducing appropriate weights to the solutions obtained for a simplified cylindrical model, calculation is made of the induction toroidal electric field on the plasma axis in the presence of the eddy currents. The result shows that, to reduce the influence of the eddy currents on the induction one-turn voltage to the permissible level, it is necessary to choose the optimal number of turns and shape of the single conductor of the toroidal field coil. (auth.)

  20. Current pulse: can a production system reduce medical errors in health care?

    Science.gov (United States)

    Printezis, Antonios; Gopalakrishnan, Mohan

    2007-01-01

    One of the reasons for rising health care costs is medical errors, a majority of which result from faulty systems and processes. Health care in the past has used process-based initiatives such as Total Quality Management, Continuous Quality Improvement, and Six Sigma to reduce errors. These initiatives to redesign health care, reduce errors, and improve overall efficiency and customer satisfaction have had moderate success. Current trend is to apply the successful Toyota Production System (TPS) to health care since its organizing principles have led to tremendous improvement in productivity and quality for Toyota and other businesses that have adapted them. This article presents insights on the effectiveness of TPS principles in health care and the challenges that lie ahead in successfully integrating this approach with other quality initiatives.