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Sample records for high current high

  1. High PRF high current switch

    Science.gov (United States)

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.

  2. High current ion sources

    International Nuclear Information System (INIS)

    Brown, I.G.

    1989-06-01

    The concept of high current ion source is both relative and evolutionary. Within the domain of one particular kind of ion source technology a current of microamperers might be 'high', while in another area a current of 10 Amperes could 'low'. Even within the domain of a single ion source type, what is considered high current performance today is routinely eclipsed by better performance and higher current output within a short period of time. Within their fields of application, there is a large number of kinds of ion sources that can justifiably be called high current. Thus, as a very limited example only, PIGs, Freemen sources, ECR sources, duoplasmatrons, field emission sources, and a great many more all have their high current variants. High current ion beams of gaseous and metallic species can be generated in a number of different ways. Ion sources of the kind developed at various laboratories around the world for the production of intense neutral beams for controlled fusion experiments are used to form large area proton deuteron beams of may tens of Amperes, and this technology can be used for other applications also. There has been significant progress in recent years in the use of microwave ion sources for high current ion beam generation, and this method is likely to find wide application in various different field application. Finally, high current beams of metal ions can be produced using metal vapor vacuum arc ion source technology. After a brief consideration of high current ion source design concepts, these three particular methods are reviewed in this paper

  3. Cryogenic high current discharges

    International Nuclear Information System (INIS)

    Meierovich, B.E.

    1994-01-01

    Z-pinches formed from frozen deuterium fibers by a rapidly rising current have enhanced stability and high neutron yield. The efforts to understand the enhanced stability and neutron yield on the basis of classical picture of Bennett equilibrium of the current channel has not given satisfactory results. The traditional approach does not take into account the essential difference between the frozen deuterium fiber Z-pinches and the usual Z-pinches such as exploding wires or classical gas-puffed Z-pinches. The very low temperature of the fiber atoms (10 K), together with the rapidly rising current, result in the coexistence of a high current channel with unionized fiber atoms for a substantial period of time. This phenomena lasts during the risetime. This approach takes into account the difference of the breakdown in a dielectric deuterium fiber and the breakdown in a metallic wire. This difference is essential to the understanding of specific features of cryogenic high current discharges. Z-pinches in frozen deuterium fibers should be considered as a qualitatively new phenomenon on the boundary of cryogenic and high current physics. It is a start of a new branch in plasma physics: the physics of cryogenic high current discharges

  4. High current induction linacs

    International Nuclear Information System (INIS)

    Barletta, W.; Faltens, A.; Henestroza, E.; Lee, E.

    1994-07-01

    Induction linacs are among the most powerful accelerators in existence. They have accelerated electron bunches of several kiloamperes, and are being investigated as drivers for heavy ion driven inertial confinement fusion (HIF), which requires peak beam currents of kiloamperes and average beam powers of some tens of megawatts. The requirement for waste transmutation with an 800 MeV proton or deuteron beam with an average current of 50 mA and an average power of 40 MW lies midway between the electron machines and the heavy ion machines in overall difficulty. Much of the technology and understanding of beam physics carries over from the previous machines to the new requirements. The induction linac allows use of a very large beam aperture, which may turn out to be crucial to reducing beam loss and machine activation from the beam halo. The major issues addressed here are transport of high intensity beams, availability of sources, efficiency of acceleration, and the state of the needed technology for the waste treatment application. Because of the transformer-like action of an induction core and the accompanying magnetizing current, induction linacs make the most economic sense and have the highest efficiencies with large beam currents. Based on present understanding of beam transport limits, induction core magnetizing current requirements, and pulse modulators, the efficiencies could be very high. The study of beam transport at high intensities has been the major activity of the HIF community. Beam transport and sources are limiting at low energies but are not significant constraints at the higher energies. As will be shown, the proton beams will be space-charge-dominated, for which the emittance has only a minor effect on the overall beam diameter but does determine the density falloff at the beam edge

  5. High current and high power superconducting rectifiers

    International Nuclear Information System (INIS)

    Kate, H.H.J. ten; Bunk, P.B.; Klundert, L.J.M. van de; Britton, R.B.

    1981-01-01

    Results on three experimental superconducting rectifiers are reported. Two of them are 1 kA low frequency flux pumps, one thermally and magnetically switched. The third is a low-current high-frequency magnetically switched rectifier which can use the mains directly. (author)

  6. High current density ion source

    International Nuclear Information System (INIS)

    King, H.J.

    1977-01-01

    A high-current-density ion source with high total current is achieved by individually directing the beamlets from an electron bombardment ion source through screen and accelerator electrodes. The openings in these screen and accelerator electrodes are oriented and positioned to direct the individual beamlets substantially toward a focus point. 3 figures, 1 table

  7. High current plasma electron emitter

    International Nuclear Information System (INIS)

    Fiksel, G.; Almagri, A.F.; Craig, D.

    1995-07-01

    A high current plasma electron emitter based on a miniature plasma source has been developed. The emitting plasma is created by a pulsed high current gas discharge. The electron emission current is 1 kA at 300 V at the pulse duration of 10 ms. The prototype injector described in this paper will be used for a 20 kA electrostatic current injection experiment in the Madison Symmetric Torus (MST) reversed-field pinch. The source will be replicated in order to attain this total current requirement. The source has a simple design and has proven very reliable in operation. A high emission current, small size (3.7 cm in diameter), and low impurity generation make the source suitable for a variety of fusion and technological applications

  8. 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

  9. High current vacuum closing switch

    International Nuclear Information System (INIS)

    Dolgachev, G.I.; Maslennikov, D.D.; Romanov, A.S.; Ushakov, A.G.

    2005-01-01

    The paper proposes a powerful pulsed closing vacuum switch for high current commutation consisting of series of the vacuum diodes with near 1 mm gaps having closing time determined by the gaps shortening with the near-electrode plasmas [ru

  10. High current, high bandwidth laser diode current driver

    Science.gov (United States)

    Copeland, David J.; Zimmerman, Robert K., Jr.

    1991-01-01

    A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

  11. High temperature superconductor current leads

    International Nuclear Information System (INIS)

    Zeimetz, B.; Liu, H.K.; Dou, S.X.

    1996-01-01

    Full text: The use of superconductors in high electrical current applications (magnets, transformers, generators etc.) usually requires cooling with liquid Helium, which is very expensive. The superconductor itself produces no heat, and the design of Helium dewars is very advanced. Therefore most of the heat loss, i.e. Helium consumption, comes from the current lead which connects the superconductor with its power source at room temperature. The current lead usually consists of a pair of thick copper wires. The discovery of the High Temperature Superconductors makes it possible to replace a part of the copper with superconducting material. This drastically reduces the heat losses because a) the superconductor generates no resistive heat and b) it is a very poor thermal conductor compared with the copper. In this work silver-sheathed superconducting tapes are used as current lead components. The work comprises both the production of the tapes and the overall design of the leads, in order to a) maximize the current capacity ('critical current') of the superconductor, b) minimize the thermal conductivity of the silver clad, and c) optimize the cooling conditions

  12. High Critical Current Coated Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M. P.; Selvamanickam, V. (SuperPower, Inc.)

    2011-12-27

    One of the important critical needs that came out of the DOE’s coated conductor workshop was to develop a high throughput and economic deposition process for YBCO. Metal-organic chemical vapor deposition (MOCVD) technique, the most critical steps in high technical micro fabrications, has been widely employed in semiconductor industry for various thin film growth. SuperPower has demonstrated that (Y,Gd)BCO films can be deposited rapid with world record performance. In addition to high critical current density with increased film thickness, flux pinning properties of REBCO films needs to be improved to meet the DOE requirements for various electric-power equipments. We have shown that doping with Zr can result in BZO nanocolumns, but at substantially reduced deposition rate. The primary purpose of this subtask is to develop high current density MOCVD-REBCO coated conductors based on the ion-beam assisted (IBAD)-MgO deposition process. Another purpose of this subtask is to investigate HTS conductor design optimization (maximize Je) with emphasis on stability and protection issues, and ac loss for REBCO coated conductors.

  13. High current polarized electron source

    Science.gov (United States)

    Suleiman, R.; Adderley, P.; Grames, J.; Hansknecht, J.; Poelker, M.; Stutzman, M.

    2018-05-01

    Jefferson Lab operates two DC high voltage GaAs photoguns with compact inverted insulators. One photogun provides the polarized electron beam at the Continuous Electron Beam Accelerator Facility (CEBAF) up to 200 µA. The other gun is used for high average current photocathode lifetime studies at a dedicated test facility up to 4 mA of polarized beam and 10 mA of un-polarized beam. GaAs-based photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed facilities that must operate in excess of tens of mA of polarized average current. This contribution describes techniques to maintain good vacuum while delivering high beam currents, and techniques that minimize damage due to ion bombardment, the dominant mechanism that reduces photocathode yield. Advantages of higher DC voltage include reduced space-charge emittance growth and the potential for better photocathode lifetime. Highlights of R&D to improve the performance of polarized electron sources and prolong the lifetime of strained-superlattice GaAs are presented.

  14. High pressure, high current, low inductance, high reliability sealed terminals

    Science.gov (United States)

    Hsu, John S [Oak Ridge, TN; McKeever, John W [Oak Ridge, TN

    2010-03-23

    The invention is a terminal assembly having a casing with at least one delivery tapered-cone conductor and at least one return tapered-cone conductor routed there-through. The delivery and return tapered-cone conductors are electrically isolated from each other and positioned in the annuluses of ordered concentric cones at an off-normal angle. The tapered cone conductor service can be AC phase conductors and DC link conductors. The center core has at least one service conduit of gate signal leads, diagnostic signal wires, and refrigerant tubing routed there-through. A seal material is in direct contact with the casing inner surface, the tapered-cone conductors, and the service conduits thereby hermetically filling the interstitial space in the casing interior core and center core. The assembly provides simultaneous high-current, high-pressure, low-inductance, and high-reliability service.

  15. High resolution eddy current microscopy

    Science.gov (United States)

    Lantz, M. A.; Jarvis, S. P.; Tokumoto, H.

    2001-01-01

    We describe a sensitive scanning force microscope based technique for measuring local variations in resistivity by monitoring changes in the eddy current induced damping of a cantilever with a magnetic tip oscillating above a conducting sample. To achieve a high sensitivity, we used a cantilever with an FeNdBLa particle mounted on the tip. Resistivity measurements are demonstrated on a silicon test structure with a staircase doping profile. Regions with resistivities of 0.0013, 0.0041, and 0.022 Ω cm are clearly resolved with a lateral resolution of approximately 180 nm. For this range of resistivities, the eddy current induced damping is found to depend linearly on the sample resistivity.

  16. 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

  17. High current capacity electrical connector

    International Nuclear Information System (INIS)

    Bettis, E.S.; Watts, H.L.

    1976-01-01

    An electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like. The connector is arranged in a ''sandwiched'' configuration in which a conductor plate contacts the busses along major surfaces clamped between two stainless steel backing plates. The conductor plate is provided with contact buttons in a spaced array such that the caps of the buttons extend above the conductor plate surface to contact the busses. When clamping bolts provided through openings in the sandwiched arrangement are tightened, Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the busses' contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops. The contact area does not change with changing thermal or mechanical stresses applied to the coupled conductors

  18. High current superconductors for DEMO

    Energy Technology Data Exchange (ETDEWEB)

    Bruzzone, Pierluigi, E-mail: pierluigi.bruzzone@psi.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association Euratom – Confédération Suisse, CH-5232 Villigen PSI (Switzerland); Sedlak, Kamil; Stepanov, Boris [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association Euratom – Confédération Suisse, CH-5232 Villigen PSI (Switzerland)

    2013-10-15

    Highlights: ► Definition of requirement for TF coil based on the input of system code. ► A TF coil and conductor design for the European DEMO project. ► Use of React and Wind method opposite to Wind and React with related advantages. ► Hybridization of winding pack, Nb/Nb{sub 3}Sn, by graded layer winding. -- Abstract: In the assumption that DEMO will be an inductively driven tokamak, the number of load cycles will be in the range of several hundred thousands. The requirements for a new generation of Nb{sub 3}Sn based high current conductors for DEMO are drafted starting from the output of system code PROCESS. The key objectives include the stability of the DC performance over the lifetime of the machine and the effective use of the Nb{sub 3}Sn strand properties, for cost and reliability reasons. A preliminary layout of the winding pack and conductors for the toroidal field magnets is presented. To suppress the mechanism of reversible and irreversible degradation, i.e. to preserve in the cabled conductor the high critical current density of the strand, the thermal strain must be insignificant and no space for micro-bending under transverse load must be left in the strand bundle. The “react-and-wind” method is preferred here, with a graded, layer wound magnet, containing both Nb{sub 3}Sn and NbTi layers. The implications of the conductor choice on the coil design and technology are highlighted. A roadmap is sketched for the development of a full size prototype conductor sample and demonstration of the key technologies.

  19. High-voltage high-current triggering vacuum switch

    International Nuclear Information System (INIS)

    Alferov, D.F.; Bunin, R.A.; Evsin, D.V.; Sidorov, V.A.

    2012-01-01

    Experimental investigations of switching and breaking capacities of the new high current triggered vacuum switch (TVS) are carried out at various parameters of discharge current. It has been shown that the high current triggered vacuum switch TVS can switch repeatedly a current from units up to ten kiloampers with duration up to ten millisecond [ru

  20. High-current railgap studies

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R.; Gordon, L.; Hofer, W.; Wilson, M.

    1983-06-03

    Characteristics of a 40-kV, 750-kA, multichannel rail gap are presented. The gap is a three electrode, field-distortion-triggered design, with a total switch inductance of less than 10 nH. At maximum ratings, the gap typically switches 10 C per shot, at 700 kA, with a jitter of less than 2 ns. Image-converter streak photographs were used to study channel evolution and current division. Transient gas-pressure measurements were made to investigate the arc generated shocks and to detect single channel failure. Channel current sharing and simultaneity are described and their effects on the switch inductance and lifetime are discussed. Lifetime tests of the rail gap were performed. Degradation in the channel current-sharing and erosion measurements are discussed.

  1. High-current railgap studies

    Science.gov (United States)

    Druce, R.; Gordon, L.; Hofer, W.; Wilson, M.

    1983-06-01

    Characteristics of a 40-kV, 750-kA, multichannel rail gap are presented. The gap is a three electrode, field distortion triggered design, with a total switch inductance of less than 10 nH. At maximum ratings, the gap typically switches 10 C per shot, at 700 kA, with a jitter of less than 2 ns. Channel evolution and current division were studied on image converter streak photographs. Transient gas pressure measurements were made to investigate the arc generated shocks and to detect single channel failure. Channel current sharing and simultaneity are described and their effects on the switch inductance in the channel current sharing and erosion measurements are discussed.

  2. High bandwidth beam current monitor

    International Nuclear Information System (INIS)

    Baltrusaitis, R.M.; Ekdahl, C.A.; Cooper, R.G.; Peterson, E.; Warn, C.E.

    1993-01-01

    A stripline directional coupler beam current monitor capable of measuring the time structure of a 30-ps electron beam bunch has been developed. The time response performance of the monitor compares very well with Cherenkov light produced in quartz by the electron beam. The four-pickup monitor is now used on a routine basis for measuring the beam duration, tuning for optimized beam bunching, and centering the bunch in the beam pipe

  3. Properties of high current RFQ injectors

    International Nuclear Information System (INIS)

    Schempp, A.; Goethe, J.W.

    1996-01-01

    RFQ linacs are efficient, compact low energy ion structures, which have found numerous applications. They use electrical rf focusing and can capture, bunch and transmit high current ion beams. Some recent development and new projects like a heavy ion injectors for a cyclotron, and the status of the work on high current high duty factor RFQs will be discussed. (author)

  4. Properties of high current RFQ injectors

    Energy Technology Data Exchange (ETDEWEB)

    Schempp, A.; Goethe, J.W. [Frankfurt Univ. (Germany). Inst. fuer Angewandte Physik

    1996-12-31

    RFQ linacs are efficient, compact low energy ion structures, which have found numerous applications. They use electrical rf focusing and can capture, bunch and transmit high current ion beams. Some recent development and new projects like a heavy ion injectors for a cyclotron, and the status of the work on high current high duty factor RFQs will be discussed. (author) 2 refs.

  5. High-Average, High-Peak Current Injector Design

    CERN Document Server

    Biedron, S G; Virgo, M

    2005-01-01

    There is increasing interest in high-average-power (>100 kW), um-range FELs. These machines require high peak current (~1 kA), modest transverse emittance, and beam energies of ~100 MeV. High average currents (~1 A) place additional constraints on the design of the injector. We present a design for an injector intended to produce the required peak currents at the injector, eliminating the need for magnetic compression within the linac. This reduces the potential for beam quality degradation due to CSR and space charge effects within magnetic chicanes.

  6. A high current, high speed pulser using avalanche transistors

    International Nuclear Information System (INIS)

    Hosono, Yoneichi; Hasegawa, Ken-ichi

    1985-01-01

    A high current, high speed pulser for the beam pulsing of a linear accelerator is described. It uses seven avalanche transistors in cascade. Design of a trigger circuit to obtain fast rise time is discussed. The characteristics of the pulser are : (a) Rise time = 0.9 ns (FWHM) and (d) Life time asymptotically equals 2000 -- 3000 hr (at 50 Hz). (author)

  7. Measurement technology of RF interference current in high current system

    Science.gov (United States)

    Zhao, Zhihua; Li, Jianxuan; Zhang, Xiangming; Zhang, Lei

    2018-06-01

    Current probe is a detection method commonly used in electromagnetic compatibility. With the development of power electronics technology, the power level of power conversion devices is constantly increasing, and the power current of the electric energy conversion device in the electromagnetic launch system can reach 10kA. Current probe conventionally used in EMC (electromagnetic compatibility) detection cannot meet the test requirements on high current system due to the magnetic saturation problem. The conventional high current sensor is also not suitable for the RF (Radio Frequency) interference current measurement in high current power device due to the high noise level in the output of active amplifier. In this paper, a passive flexible current probe based on Rogowski coil and matching resistance is proposed that can withstand high current and has low noise level, to solve the measurement problems of interference current in high current power converter. And both differential mode and common mode current detection can be easily carried out with the proposed probe because of the probe's flexible structure.

  8. High current density ion beam measurement techniques

    International Nuclear Information System (INIS)

    Ko, W.C.; Sawatzky, E.

    1976-01-01

    High ion beam current measurements are difficult due to the presence of the secondary particles and beam neutralization. For long Faraday cages, true current can be obtained only by negative bias on the target and by summing the cage wall and target currents; otherwise, the beam will be greatly distorted. For short Faraday cages, a combination of small magnetic field and the negative target bias results in correct beam current. Either component alone does not give true current

  9. A new high performance current transducer

    International Nuclear Information System (INIS)

    Tang Lijun; Lu Songlin; Li Deming

    2003-01-01

    A DC-100 kHz current transducer is developed using a new technique on zero-flux detecting principle. It was shown that the new current transducer is of high performance, its magnetic core need not be selected very stringently, and it is easy to manufacture

  10. Development of a high current ion implanter

    International Nuclear Information System (INIS)

    Choi, Byung Ho; Kim, Wan; Jin, Jeong Tae

    1990-01-01

    A high current ion implanter of the energy of 100 Kev and the current of about 100 mA has been developed for using the high dose ion implantation, surface modification of steels and ceramics, and ion beam milling. The characteristics of the beam extraction and transportation are investigated. A duoPIGatron ion source compatible with gas ion extraction of about 100 mA, a single gap acceleration tube which is able to compensate the divergence due to the space charge effect, and a beam transport system with the concept of the space charge neutralization are developed for the high current machine. The performance of the constructed machine shows that nitrogen, argon, helium, hydrogen and oxygen ion beams are successfully extracted and transported at a beam divergence due to space charge effect is negligible in the operation pressure of 2 x 10 -5 torr. (author)

  11. High-current discharge channel contraction in high density gas

    International Nuclear Information System (INIS)

    Rutberg, Ph. G.; Bogomaz, A. A.; Pinchuk, M. E.; Budin, A. V.; Leks, A. G.; Pozubenkov, A. A.

    2011-01-01

    Research results for discharges at current amplitudes of 0.5-1.6 MA and current rise rate of ∼10 10 A/s are presented. The discharge is performed in the hydrogen environment at the initial pressure of 5-35 MPa. Initiation is implemented by a wire explosion. The time length of the first half-period of the discharge current is 70-150 μs. Under such conditions, discharge channel contraction is observed; the contraction is followed by soft x-ray radiation. The phenomena are discussed, which are determined by high density of the gas surrounding the discharge channel. These phenomena are increase of the current critical value, where the channel contraction begins and growth of temperature in the axis region of the channel, where the initial density of the gas increases.

  12. Development of high current electron beam generator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byeong Cheol; Lee, Jong Min; Kim, Sun Kook [and others

    1997-05-01

    A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs.

  13. Development of high current electron beam generator

    International Nuclear Information System (INIS)

    Lee, Byeong Cheol; Lee, Jong Min; Kim, Sun Kook

    1997-05-01

    A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs

  14. Highly efficient red electrophosphorescent devices at high current densities

    International Nuclear Information System (INIS)

    Wu Youzhi; Zhu Wenqing; Zheng Xinyou; Sun, Runguang; Jiang Xueyin; Zhang Zhilin; Xu Shaohong

    2007-01-01

    Efficiency decrease at high current densities in red electrophosphorescent devices is drastically restrained compared with that from conventional electrophosphorescent devices by using bis(2-methyl-8-quinolinato)4-phenylphenolate aluminum (BAlq) as a hole and exciton blocker. Ir complex, bis(2-(2'-benzo[4,5-α]thienyl) pyridinato-N,C 3' ) iridium (acetyl-acetonate) is used as an emitter, maximum external quantum efficiency (QE) of 7.0% and luminance of 10000cd/m 2 are obtained. The QE is still as high as 4.1% at higher current density J=100mA/cm 2 . CIE-1931 co-ordinates are 0.672, 0.321. A carrier trapping mechanism is revealed to dominate in the process of electroluminescence

  15. LASL high-current proton storage rings

    International Nuclear Information System (INIS)

    Lawrence, G.P.; Cooper, R.K.; Hudgings, D.W.; Spalek, G.; Jason, A.J.; Higgins, E.F.; Gillis, R.E.

    1980-01-01

    The Proton Storage Ring at LAMPF is a high-current accumulator designed to convert long 800-MeV linac pulses into very short high-intensity proton bunches ideally suited to driving a pulsed polyenergetic neutron source. The Ring, authorized for construction at $19 million, will operate in a short-bunch high-frequency mode for fast neutron physics and a long-bunch low-frequency mode for thermal neutron-scattering programs. Unique features of the project include charge-changing injection with initial conversion from H - to H 0 , a high repetition rate fast-risetime extraction kicker, and high-frequency and first-harmonic bunching system

  16. Simple, high current, antimony ion source

    International Nuclear Information System (INIS)

    Sugiura, H.

    1979-01-01

    A simple metal ion source capable of producing a continuous, uncontaminated, high current beam of Sb ions is presented. It produced a total ion current of 200 μA at 1 kV extraction voltage. A discharge occurred in the source at a pressure of 6 x 10 -4 Torr. The ion current extracted from the source increased with the 3/2 power of the extraction voltage. The perveance of the source and ion density in the plasma were 8 x 10 -9 and 1.8 x 10 11 cm -3 , respectively

  17. Compact high-current, subnanosecond electron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Shpak, V G; Shunajlov, S A; Ulmaskulov, M R; Yalandin, M I [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Electrophysics; Pegel, I V [Russian Academy of Sciences, Tomsk (Russian Federation). High-Current Electronics Inst.; Tarakanov, V P [Russian Academy of Sciences, Moscow (Russian Federation). High-Temperature Inst.

    1997-12-31

    A compact subnanosecond, high-current electron accelerator producing an annular electron beam of duration up to 300 - 400 ps, energy about 250 keV, and current up to 1 kA has been developed to study transient processes in pulsed power microwave devices. The measuring and recording techniques used to experimentally investigate the dynamics of the beam current pulse and the transformation of the electron energy during the transportation of the beam in a longitudinal magnetic field are described. The experimental data obtained are compared with the predictions of a numerical simulation. (author). 6 figs., 5 refs.

  18. Charged current weak interactions at high energy

    International Nuclear Information System (INIS)

    Cline, D.

    1977-01-01

    We review high energy neutrino and antineutrino charged current interactions. An overview of the experimental data is given, including a discussion of the experimental status of the y anomaly. Locality tests, μ-e universality and charge symmetry invariance tests are discussed. Charm production is discussed. The experimental status of trimuon events and possible phenomenological models for these events are presented. (orig.) [de

  19. Fast-response protection from high currents

    International Nuclear Information System (INIS)

    Novikov, A.A.

    1989-01-01

    Protection devices for power electronic equipment from shorting current are described. The device is shunted using spark gaps with minimal possible number of spark gaps to protect it. High fast-response (<100 ns) and operation voltage wide range (6-100 kV) are attained using Arkadiev-Marx generator-base trigger devices and air-core pulse transformer

  20. Research on high beam-current accelerators

    International Nuclear Information System (INIS)

    Keefe, D.

    1981-01-01

    In this review of research being undertaken at present in the US on accelerating devices and concepts of a novel nature, both non-collective systems, including high-current rf linacs and a variety of induction linacs, and also collective systems are considered. (U.K.)

  1. High current ion source development at Frankfurt

    Energy Technology Data Exchange (ETDEWEB)

    Volk, K.; Klein, H.; Lakatos, A.; Maaser, A.; Weber, M. [Frankfurt Univ. (Germany). Inst. fuer Angewandte Physik

    1995-11-01

    The development of high current positive and negative ion sources is an essential issue for the next generation of high current linear accelerators. Especially, the design of the European Spallation Source facility (ESS) and the International Fusion Material Irradiation Test Facility (IFMIF) have increased the significance of high brightness hydrogen and deuterium sources. As an example, for the ESS facility, two H{sup -}-sources each delivering a 70 mA H{sup -}-beam in 1.45 ms pulses at a repetition rate of 50 Hz are necessary. A low emittance is another important prerequisite. The source must operate, while meeting the performance requirements, with a constancy and reliability over an acceptable period of time. The present paper summarizes the progress achieved in ion sources development of intense, single charge, positive and negative ion beams. (author) 16 figs., 7 refs.

  2. High current ion source development at Frankfurt

    International Nuclear Information System (INIS)

    Volk, K.; Klein, H.; Lakatos, A.; Maaser, A.; Weber, M.

    1995-01-01

    The development of high current positive and negative ion sources is an essential issue for the next generation of high current linear accelerators. Especially, the design of the European Spallation Source facility (ESS) and the International Fusion Material Irradiation Test Facility (IFMIF) have increased the significance of high brightness hydrogen and deuterium sources. As an example, for the ESS facility, two H - -sources each delivering a 70 mA H - -beam in 1.45 ms pulses at a repetition rate of 50 Hz are necessary. A low emittance is another important prerequisite. The source must operate, while meeting the performance requirements, with a constancy and reliability over an acceptable period of time. The present paper summarizes the progress achieved in ion sources development of intense, single charge, positive and negative ion beams. (author) 16 figs., 7 refs

  3. Quench properties of high current superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Garber, M; Sampson, W B

    1980-01-01

    A technique has been developed which allows the simultaneous determination of most of the important parameters of a high current superconductor. The critical current, propagation velocity, normal state resistivity, magnetoresistance, and enthalpy are determined as a function of current and applied field. The measurements are made on non-inductive samples which simulate conditions in full scale magnets. For wide, braided conductors the propagation velocity was found to vary approximately quadratically with current in the 2 to 5 kA region. A number of conductors have been tested including some Nb/sub 3/Sn braids which have critical currents in excess of 10 kA at 5 T, 4.2 K.

  4. Critical current enhancement in high Tc superconductors

    International Nuclear Information System (INIS)

    Jin, S.; Graebner, J.E.; Tiefel, T.H.

    1990-01-01

    Progress toward major technological applications of the bulk, high T c superconductors has been hindered by two major barriers, i.e., the Josephson weak-links at grain boundaries and the lack of sufficient intragrain flux pinning. It has been demonstrated that the weak link problem can be overcome by extreme alignment of grains such as in melt-textured-growth (MTG) materials. Modified or improved processing by various laboratories has produced further increased critical currents. However, the insufficient flux pinning seems to limit the critical current density in high fields to about 10 4 --10 5 A/cm 2 at 77K, which is not satisfactory for many applications. In this paper, processing, microstructure, and critical current behavior of the MTG type superconductors are described, and various processing possibilities for flux pinning enhancement are discussed

  5. Physics issues of high bootstrap current tokamaks

    International Nuclear Information System (INIS)

    Ozeki, T.; Azumi, M.; Ishii, Y.

    1997-01-01

    Physics issues of a tokamak plasma with a hollow current profile produced by a large bootstrap current are discussed based on experiments in JT-60U. An internal transport barrier for both ions and electrons was obtained just inside the radius of zero magnetic shear in JT-60U. Analysis of the toroidal ITG microinstability by toroidal particle simulation shows that weak and negative shear reduces the toroidal coupling and suppresses the ITG mode. A hard beta limit was observed in JT-60U negative shear experiments. Ideal MHD mode analysis shows that the n = 1 pressure-driven kink mode is a plausible candidate. One of the methods to improve the beta limit against the kink mode is to widen the negative shear region, which can induce a broader pressure profile resulting in a higher beta limit. The TAE mode for the hollow current profile is less unstable than that for the monotonic current profile. The reason is that the continuum gaps near the zero shear region are not aligned when the radius of q min is close to the region of high ∇n e . Finally, a method for stable start-up for a plasma with a hollow current profile is describe, and stable sustainment of a steady-state plasma with high bootstrap current is discussed. (Author)

  6. Development of high temperature superconductors having high critical current density

    International Nuclear Information System (INIS)

    Hong, Gye Wong; Kim, C. J.; Lee, H.G.; Kwon, S. C.; Lee, H. J.; Kim, K. B.; Park, J. Y.; Jung, C. H.

    2000-08-01

    Fabrication of high T c superconductors and its applications for electric power device were carried out for developing superconductor application technologies. High quality YBCO superconductors was fabricated by melt texture growth, top-seeded melt growth process and multi-seeded melt growth process and the properties was compared. The critical current density of the melt processed YBCO superconductors was about few 10,000 A/cm 2 and the levitation force was 50 N. The processing time needed for the growth of the 123 single grain was greatly reduced by applying multi-seeding without no significant degradation of the levitation force. The multi-seeded melt growth process was confirmed as a time-saving and cost-effective method for the fabrication of bulk superconductors with controlled crystallographic orientation

  7. Development of high temperature superconductors having high critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Gye Wong; Kim, C. J.; Lee, H.G.; Kwon, S. C.; Lee, H. J.; Kim, K. B.; Park, J. Y.; Jung, C. H

    2000-08-01

    Fabrication of high T{sub c} superconductors and its applications for electric power device were carried out for developing superconductor application technologies. High quality YBCO superconductors was fabricated by melt texture growth, top-seeded melt growth process and multi-seeded melt growth process and the properties was compared. The critical current density of the melt processed YBCO superconductors was about few 10,000 A/cm{sup 2} and the levitation force was 50 N. The processing time needed for the growth of the 123 single grain was greatly reduced by applying multi-seeding without no significant degradation of the levitation force. The multi-seeded melt growth process was confirmed as a time-saving and cost-effective method for the fabrication of bulk superconductors with controlled crystallographic orientation.

  8. Surface ionization ion source with high current

    International Nuclear Information System (INIS)

    Fang Jinqing; Lin Zhizhou; Yu Lihua; Zhan Rongan; Huang Guojun; Wu Jianhua

    1986-04-01

    The working principle and structure of a surface ionization ion source with high current is described systematically. Some technological keypoints of the ion source are given in more detail, mainly including: choosing and shaping of the material of the surface ionizer, heating of the ionizer, distributing of working vapour on the ionizer surface, the flow control, the cooling problem at the non-ionization surface and the ion optics, etc. This ion source has been used since 1972 in the electromagnetic isotope separator with 180 deg angle. It is suitable for separating isotopes of alkali metals and rare earth metals. For instance, in the case of separating Rubidium, the maximum ion current of Rbsup(+) extracted from the ion source is about 120 mA, the maximum ion current accepted by the receiver is about 66 mA, the average ion current is more than 25 mA. The results show that our ion source have advantages of high ion current, good characteristics of focusing ion beam, working stability and structure reliability etc. It may be extended to other fields. Finally, some interesting phenomena in the experiment are disccused briefly. Some problems which should be investigated are further pointed out

  9. High stability, high current DC-power supplies

    International Nuclear Information System (INIS)

    Hosono, K.; Hatanaka, K.; Itahashi, T.

    1995-01-01

    Improvements of the power supplies and the control system of the AVF cyclotron which is used as an injector to the ring cyclotron and of the transport system to the ring cyclotron were done in order to get more high quality and more stable beam. The power supply of the main coil of the AVF cyclotron was exchanged to new one. The old DCCTs (zero-flux current transformers) used for the power supplies of the trim coils of the AVF cyclotron were changed to new DCCTs to get more stability. The potentiometers used for the reference voltages in the other power supplies of the AVF cyclotron and the transport system were changed to the temperature controlled DAC method for numerical-value settings. This paper presents the results of the improvements. (author)

  10. High current beam transport experiments at GSI

    International Nuclear Information System (INIS)

    Klabunde, J.; Schonlein, A.; Spadtke, P.

    1985-01-01

    The status of the high current ion beam transport experiment is reported. 190 keV Ar 1+ ions were injected into six periods of a magnetic quadrupole channel. Since the pulse length is > 0.5 ms partial space charge neutralization occurs. In our experiments, the behavior of unneutralized and partially space charge compensated beams is compared. With an unneutralized beam, emittance growth has been measured for high intensities even in case of the zero-current phase advance sigma 0 0 . This initial emittance growth at high tune depression we attribute to the homogenization effect of the space charge density. An analytical formula based on this assumption describes the emittance growth very well. Furthermore the predicted envelope instabilities for sigma 0 > 90 0 were observed even after 6 periods. In agreement with the theory, unstable beam transport was also experimentally found if a beam with different emittances in the two transverse phase planes was injected into the transport channel. Although the space charge force is reduced for a partially neutralized beam a deterioration of the beam quality was measured in a certain range of beam parameters. Only in the range where an unneutralized beam shows the initial emittance growth, the partial neutralization reduces this effect, otherwise the partially neutralized beam is more unstable

  11. Compilation of current high energy physics experiments

    International Nuclear Information System (INIS)

    1978-09-01

    This compilation of current high-energy physics experiments is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and the nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), KEK, Rutherford (RHEL), Serpukhov (SERP), and SLAC. Nominally, the compilation includes summaries of all high-energy physics experiments at the above laboratories that were approved (and not subsequently withdrawn) before about June 1978, and had not completed taking of data by 1 January 1975. The experimental summaries are supplemented with three indexes to the compilation, several vocabulary lists giving names or abbreviations used, and a short summary of the beams at each of the laboratories (except Rutherford). The summaries themselves are included on microfiche

  12. 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

  13. Versatile high current metal ion implantation facility

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1992-01-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. (orig)

  14. Highly sensitive detection of a current ripple

    International Nuclear Information System (INIS)

    Aoki, Takashi; Gushiken, Tutomu; Nishikigouri, Kazutaka; Kumada, Masayuki.

    1996-01-01

    In the HIMAC, there are six thyristor-controlled power sources for driving two synchrotrons. These power sources are the three-output terminal power sources which are equipped with positive output, negative output and neutral point for the common mode countermeasures. As electromagnet circuits are connected to the three-output terminal power sources, those are three-line type. In the inside of the power source circuits controlled by thyristors, there is the oscillation peculiar to the power sources, and the variation of voltage induces current spikes. This time, in order to assess the results of the common mode countermeasures in the power source and electromagnet circuits, as one method of cross-check, it is considered that since electromagnet current flows being divided to the bridging resistance and the coil, if attention is paid to the current on bridging resistance side, the ripple components of common mode and normal mode can be detected with high sensitivity, and this was verified. The present state of heightening the performance of synchrotron power sources is explained. The cross-check of the method of assessing the performance of electromagnet power sources is reported. The method of measuring ripple current and the results of the measurement are reported. (K.I.)

  15. Achromatic beam transport of High Current Injector

    International Nuclear Information System (INIS)

    Kumar, Sarvesh; Mandal, A.

    2016-01-01

    The high current injector (HCI) provides intense ion beams of high charge state using a high temperature superconducting ECR ion source. The ion beam is accelerated upto a final energy of 1.8 MeV/u due to an electrostatic potential, a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The ion beam has to be transported to superconducting LINAC which is around 50 m away from DTL. This section is termed as high energy beam transport section (HEBT) and is used to match the beam both in transverse and longitudinal phase space to the entrance of LINAC. The HEBT section is made up of four 90 deg. achromatic bends and interconnecting magnetic quadrupole triplets. Two RF bunchers have been used for longitudinal phase matching to the LINAC. The ion optical design of HEBT section has been simulated using different beam dynamics codes like TRACEWIN, GICOSY and TRACE 3D. The field computation code OPERA 3D has been utilized for hardware design of all the magnets. All the dipole and quadrupole magnets have been field mapped and their test results such as edge angles measurements, homogeneity and harmonic analysis etc. are reported. The whole design of HEBT section has been performed such that the most of the beam optical components share same hardware design and there is ample space for beam diagnostics as per geometry of the building. Many combination of achromatic bends have been simulated to transport the beam in HEBT section but finally the four 90 deg. achromatic bend configuration is found to be the best satisfying all the geometrical constraints with simplified beam tuning process in real time

  16. High-temperature superconducting current leads

    Science.gov (United States)

    Hull, J. R.

    1992-07-01

    The use of high-temperature superconductors (HTSs) for current leads to deliver power to devices at liquid helium temperature is near commercial realization. The use of HTSs in this application has the potential to reduce refrigeration requirements and helium boiloff to values significantly lower than the theoretical best achievable with conventional leads. Considerable advantage is achieved by operating these leads with an intermediate temperature heat sink. The HTS part of the lead can be made from pressed and sintered powder. Powder-in-tube fabrication is also possible, however, the normal metal part of the lead acts as a thermal short and cannot provide much stabilization without increasing the refrigeration required. Lead stability favors designs with low current density. Such leads can be manufactured with today's technology, and lower refrigeration results from the same allowable burnout time. Higher current densities result in lower boiloff for the same lead length, but bumout times can be very short. In comparing experiment to theory, the density of helium vapor needs to be accounted for in calculating the expected boiloff. For very low-loss leads, two-dimensional heat transfer and the state of the dewar near the leads may play a dominant role in lead performance.

  17. High current pelletron for ion implantation

    International Nuclear Information System (INIS)

    Schroeder, J.B.

    1989-01-01

    Since 1984, when the first production MeV ion implanter (an NEC model MV-T30) went on-line, interest in versatile electrostatic accelerator systems for MeV ion implantation has grown. The systems use a negative ion source to inject a tandem megavolt accelerator. In early systems the 0.4 mA of charging current from the two Pelletron charging chains in the accelerator was sufficient for the low intensity of beams from the ion source. This 2-chain system, however, is no longer adequate for the much higher beam intensities from today's improved ion sources. A 4-chain charging system, which delivers 1.3 mA to the high voltage terminal, was developed and is in operation in new models of NEC S Series Pelletron accelerators. This paper describes the latest beam performance of 1 MV and 1.7 MW Pelletron accelerators with this new 4-chain charging system. (orig.)

  18. Macrofilament simulation of high current beam transport

    International Nuclear Information System (INIS)

    Hayden, R.J.; Jakobson, M.J.

    1985-01-01

    Macrofilament simulation of high current beam transport through a series of solenoids has been used to investigate the sensitivity of such calculations to the initial beam distribution and to the number of filaments used in the simulation. The transport line was tuned to approximately 105 0 phase advance per cell at zero current with a tune depression of 65 0 due to the space charge. Input distributions with the filaments randomly uniform throughout a four dimensional ellipsoid and K-V input distributions have been studied. The behavior of the emittance is similar to that published for quadrupoles with like tune depression. The emittance demonstrated little growth in the first twelve solenoids, a rapid rate of growth for the next twenty, and a subsequent slow rate of growth. A few hundred filaments were sufficient to show the character of the instability. The number of filaments utilized is an order of magnitude fewer than has been utilized previously for similar instabilities. The previously published curves for simulations with less than a thousand particles show a rather constant emittance growth. If the solenoid transport line magnetic field is increased a few percent, emittance growth curves are obtained not unlike those curves. Collision growth effects are less important than indicated in the previously published results for quadrupoles

  19. Application of high speed photography for high current vacuum arcs

    NARCIS (Netherlands)

    Damstra, G.C.; Merck, W.F.H.; Vossen, J.W.G.L.; Janssen, M.F.P.; Bouwmeester, C.E.

    1998-01-01

    A high speed image detection system for 106 frames per second or 107 streaks per second has been developed for the testing of vacuum circuit breakers, using 10×16 optical fibres for light transfer to 160 fast photo diodes. The output of these diodes is multiplexed, AD converted in a 4 bit

  20. Current high-level waste solidification technology

    International Nuclear Information System (INIS)

    Bonner, W.F.; Ross, W.A.

    1976-01-01

    Technology has been developed in the U.S. and abroad for solidification of high-level waste from nuclear power production. Several processes have been demonstrated with actual radioactive waste and are now being prepared for use in the commercial nuclear industry. Conversion of the waste to a glass form is favored because of its high degree of nondispersibility and safety

  1. CURRENT MICROBIOLOGICAL ASPECTS IN HIGH MOUNTAIN

    OpenAIRE

    KURT HANSELMANN; MUNTI YUHANA

    2006-01-01

    Remote and normally unpolluted high mountain lakes provide habitats with no or very limited anthropogenic influences and, therefore, their hydrodynamics are mostly regulated by the natural c onditions. Researches in high mountain lakes deal with measuring and modeling the response of the habitats to environmental changes especially correlated to acid deposition, pollutants influx and climatic variability. The microbial world has also become a focus in many studies of these extreme ecosystem...

  2. Current situation on highly pathogenic avian influenza

    Science.gov (United States)

    Avian influenza is one of the most important diseases affecting the poultry industry worldwide. Avian influenza viruses can cause a range of clinical disease in poultry. Viruses that cause severe disease and mortality are referred to as highly pathogenic avian influenza (HPAI) viruses. The Asian ...

  3. Characterization of high-current, high-temperature superconductor current lead elements

    International Nuclear Information System (INIS)

    Niemann, R.C.; Evans, D.J.; Fisher, B.L.; Brockenborough, W.E.; Roberts, P.R.; Rodenbush, A.J.

    1996-08-01

    The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures

  4. High altitude observations of Birkeland currents

    International Nuclear Information System (INIS)

    Russell, C.T.

    1977-01-01

    Birkeland or field-aligned currents are thought to play a fundamental role in many magnetospheric processes. These roles are reviewed together with observations of Birkeland currents in the distant magnetosphere

  5. Cathode erosion in high-current high-pressure arc

    CERN Document Server

    Nemchinsky, V A

    2003-01-01

    Cathode erosion rate was experimentally investigated for two types of arcs: one with tungsten cathode in nitrogen atmosphere and one with hafnium cathode in oxygen atmosphere. Conditions were typical for plasma arc cutting systems: gas pressure from 2 to 5 atm, arc current from 200 to 400 A, gas flow rate from 50 to 130 litre min sup - sup 1. It was found that the actual cathode evaporation rate G is much lower than G sub 0 , the evaporation rate that follows from the Hertz-Knudsen formula: G = nu G sub 0. The difference is because some of the evaporated particles return back to the cathode. For conditions of our experiments, the factor nu could be as low as 0.01. It was shown experimentally that nu depends strongly on the gas flow pattern close to the cathode. In particular, swirling the gas increases nu many times. To explain the influence of gas swirling, model calculations of gas flows were performed. These calculations revealed difference between swirling and non-swirling flows: swirling the gas enhances...

  6. Design of high current bunching system and high power fast Faraday cup for high current LEBT at VECC

    International Nuclear Information System (INIS)

    Anuraag Misra, A.; Pandit, B.V.S.; Gautam Pal, C.

    2011-01-01

    A high current microwave ion source as described is currently operational at VECC. We are able to optimize 6.4 mA of proton current in the LEBT line of ion source. The cyclotron type of accelerators accept only a fraction of DC ion beam coming from ion source so a ion beam buncher is needed to increase the accepted current into the cyclotron. The buncher described in this paper is unique in its kind as it has to handle high beam loading power upto 400 W as it is designed to bunch few mA of proton beam currents at 80 keV beam energy. A sinusoidal quarter wave RF structure has been chosen to bunch the high current beam due to high Q achievable in comparison with other configurations. This buncher has been designed using CST Microwave studio 3D advanced code since the design frequency of our buncher is 42 MHz, we have provided the RF and vacuum window near the drift tube of buncher to avoid vacuum and multipacting problems and to keep maximum volume in air region. There is a provision of multipacting interlocks to shut off amplifier during multipacting. We have carried out a detailed electromagnetic and thermal design of the buncher in CST Microwave studio and simulated values of unloaded Q was calculated be 4000. We have estimated a power of 400 W to achieve gap (designed) voltage of 10 kV. This buncher is in advanced stage of fabrication. A high power fast Faraday cup is also designed to characterize the above mentioned high current bunching system. The fast Faraday cup is designed in 50 Ω coaxial geometry to transmit fast pulse of bunched ion beam. The design of Faraday cup was completed using ANSYS HFSS and a bandwidth of 1.75 GHz was achieved this faraday cup design was different from conventional Faraday cup design as we have designed the support and cooling lines at such a place on Faraday cup which do not disturb the electrical impedance of the cup. (author)

  7. Eddy current testing with high penetration

    International Nuclear Information System (INIS)

    Becker, R.; Kroening, M.

    1999-01-01

    The low-frequency eddy current testing method is used when penetration into very deep layers is required. The achievable penetration depth is determined among other parameters by the lowest testing frequency that can be realised together with the eddy current sensor. When using inductive sensors, the measuring effect declines proportional to the lowering frequency (induction effect). Further reduction of testing frequency requires other types of sensors, as e.g. the GMR (Giant Magnetic Resistance), which achieves a constant measuring sensitivity down to the steady field. The multi-frequency eddy current testing method MFEC 3 of IZFP described here can be operated using three different scanning frequencies at a time. Two variants of eddy current probes are used in this case. Both have an inductive winding at their emitters, of the type of a measuring probe. The receiver end is either also an inductive winding, or a magnetic field-responsive resistance (GMR). (orig./CB) [de

  8. Power transistor module for high current applications

    International Nuclear Information System (INIS)

    Cilyo, F.F.

    1975-01-01

    One of the parts needed for the control system of the 400-GeV accelerator at Fermilab was a power transistor with a safe operating area of 1800A at 50V, dc current gain of 100,000 and 20 kHz bandwidth. Since the commercially available discrete devices and power hybrid packages did not meet these requirements, a power transistor module was developed which performed satisfactorily. By connecting 13 power transistors in parallel, with due consideration for network and heat dissipation problems, and by driving these 13 with another power transistor, a super power transistor is made, having an equivalent current, power, and safe operating area capability of 13 transistors. For higher capabilities, additional modules can be conveniently added. (auth)

  9. ISAC target operation with high proton currents

    CERN Document Server

    Dombsky, M; Schmor, P; Lane, M

    2003-01-01

    The TRIUMF-ISAC facility target stations were designed for ISOL target irradiations with up to 100 mu A proton beam currents. Since beginning operation in 1998, ISAC irradiation currents have progressively increased from initial values of approx 1 mu A to present levels of up to 40 mu A on refractory metal foil targets. In addition, refractory carbide targets have operated at currents of up to 15 mu A for extended periods. The 1-40 mu A operational regime is achieved by tailoring each target to the thermal requirements dictated by material properties such as beam power deposition, thermal conductivity and maximum operating temperature of the target material. The number of heat shields on each target can be varied in order to match the effective emissivity of the target surface for the required radiative power dissipation. Targets of different thickness, surface area and volume have been investigated to study the effect of diffusion and effusion delays on the yield of radioisotopes. For yields of short-lived p...

  10. Current neutralization of nanosecond risetime, high-current electron beam

    International Nuclear Information System (INIS)

    Lidestri, J.P.; Spence, P.W.; Bailey, V.L.; Putnam, S.D.; Fockler, J.; Eichenberger, C.; Champney, P.D.

    1991-01-01

    This paper reports that the authors have recently investigated methods to achieve current neutralization in fast risetime (<3 ns) electron beams propagating in low-pressure gas. For this investigation, they injected a 3-MV, 30-kA intense beam into a drift cell containing gas pressures from 0.10 to 20 torr. By using a fast net current monitor (100-ps risetime), it was possible to observe beam front gas breakdown phenomena and to optimize the drift cell gas pressure to achieve maximum current neutralization. Experimental observations have shown that by increasing the drift gas pressure (P ∼ 12.5 torr) to decrease the mean time between secondary electron/gas collisions, the beam can propagate with 90% current neutralization for the full beam pulsewidth (16 ns)

  11. MAXILAC as a high current UNILAC injector

    International Nuclear Information System (INIS)

    Ungrin, J.; Klabunde, J.

    1984-08-01

    MAXILAC, an RFQ of split coaxial resonator design, will deliver heavy ion currents in the 20-30 mA range with energies in the 100-150 keV/u range. One proposed method of coupling this RFQ to UNILAC is to divide the first tank of the Wideroee section into two segments and to inject the MAXILAC beam for acceleration starting with the second segment. This injection scheme has been investigated in detail with the beam dynamics codes MIKRO, PARMT and PARMI. Other injection schemes are also considered. (orig.)

  12. High-voltage, high-current, solid-state closing switch

    Science.gov (United States)

    Focia, Ronald Jeffrey

    2017-08-22

    A high-voltage, high-current, solid-state closing switch uses a field-effect transistor (e.g., a MOSFET) to trigger a high-voltage stack of thyristors. The switch can have a high hold-off voltage, high current carrying capacity, and high time-rate-of-change of current, di/dt. The fast closing switch can be used in pulsed power applications.

  13. The physics of high current beams

    International Nuclear Information System (INIS)

    Lawson, J.D.

    1988-05-01

    An outline is presented of paraxial charged particle optics in the presence of self-fields arising from the space-charge and current carried by the beam. Solutions of the envelope equations for beams with finite emittance are considered for a number of specific situations, with the approximation that the density profile of the beam is uniform with a sharp edge, so that the focusing remains linear. More realistic beams are then considered, and the problems of matching, emittance growth and stability are discussed. An attempt is made to emphasize physical principles and physical ideas rather than to present the detailed mathematical techniques required for specific problems. The approach is a tutorial one, and several 'exercises' are included in the text. Most of the material is treated in more depth in the author's forthcoming book. (author)

  14. High-Current Plasma Electron Sources

    International Nuclear Information System (INIS)

    Gushenets, J.Z.; Krokhmal, V.A.; Krasik, Ya. E.; Felsteiner, J.; Gushenets, V.

    2002-01-01

    In this report we present the design, electrical schemes and preliminary results of a test of 4 different electron plasma cathodes operating under Kg h-voltage pulses in a vacuum diode. The first plasma cathode consists of 6 azimuthally symmetrically distributed arc guns and a hollow anode having an output window covered by a metal grid. Plasma formation is initiated by a surface discharge over a ceramic washer placed between a W-made cathode and an intermediate electrode. Further plasma expansion leads to a redistribution of the discharge between the W-cathode and the hollow anode. An accelerating pulse applied between the output anode grid and the collector extracts electrons from this plasma. The operation of another plasma cathode design is based on Penning discharge for preliminary plasma formation. The main glow discharge occurs between an intermediate electrode of the Penning gun and the hollow anode. To keep the background pressure in the accelerating gap at P S 2.5x10 4 Torr either differential pumping or a pulsed gas puff valve were used. The operation of the latter electron plasma source is based on a hollow cathode discharge. To achieve a sharp pressure gradient between the cathode cavity and the accelerating gap a pulsed gas puff valve was used. A specially designed ferroelectric plasma cathode initiated plasma formation inside the hollow cathode. This type of the hollow cathode discharge ignition allowed to achieve a discharge current of 1.2 kA at a background pressure of 2x10 4 Torr. All these cathodes were developed and initially tested inside a planar diode with a background pressure S 2x10 4 Torr under the same conditions: accelerating voltage 180 - 300 kV, pulse duration 200 - 400 ns, electron beam current - 1 - 1.5 kA, and cross-sectional area of the extracted electron beam 113 cm 2

  15. Reducing AC-Winding Losses in High-Current High-Power Inductors

    DEFF Research Database (Denmark)

    Nymand, Morten; Madawala, Udaya K.; Andersen, Michael Andreas E.

    2009-01-01

    Foil windings are preferable in high-current high-power inductors to realize compact designs and to reduce dc-current losses. At high frequency, however, proximity effect will cause very significant increase in ac resistance in multi-layer windings, and lead to high ac winding losses. This paper ...

  16. Stable superconducting magnet. [high current levels below critical temperature

    Science.gov (United States)

    Boom, R. W. (Inventor)

    1967-01-01

    Operation of a superconducting magnet is considered. A method is described for; (1) obtaining a relatively high current in a superconducting magnet positioned in a bath of a gas refrigerant; (2) operating a superconducting magnet at a relatively high current level without training; and (3) operating a superconducting magnet containing a plurality of turns of a niobium zirconium wire at a relatively high current level without training.

  17. Final report: High current capacity high temperature superconducting film based tape for high field magnets

    International Nuclear Information System (INIS)

    Ying Xin

    2000-01-01

    The primary goal of the program was to establish the process parameters for the continuous deposition of high quality, superconducting YBCO films on one meter lengths of buffered RABiTS tape using MOCVD and to characterize the potential utility of the resulting tapes in high field magnet applications

  18. High performance current controller for particle accelerator magnets supply

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Bidoggia, Benoit; Munk-Nielsen, Stig

    2013-01-01

    The electromagnets in modern particle accelerators require high performance power supply whose output is required to track the current reference with a very high accuracy (down to 50 ppm). This demands very high bandwidth controller design. A converter based on buck converter topology is used...

  19. High-current power supply for accelerator magnets

    International Nuclear Information System (INIS)

    Bourkland, K.R.; Winje, R.A.

    1978-01-01

    A power supply for controlling the current to accelerator magnets produces a high current at a precisely controlled time rate of change by varying the resonant frequency of an RLC circuit that includes the magnet and applying the current to the magnet during a predetermined portion of the waveform of an oscillation. The current is kept from going negative despite the reverse-current characteristics of thyristors by a quenching circuit

  20. High field, low current operation of engineering test reactors

    International Nuclear Information System (INIS)

    Schwartz, J.; Cohn, D.R.; Bromberg, L.; Williams, J.E.C.

    1987-06-01

    Steady state engineering test reactors with high field, low current operation are investigated and compared to high current, lower field concepts. Illustrative high field ETR parameters are R = 3 m, α ∼ 0.5 m, B ∼ 10 T, β = 2.2% and I = 4 MA. For similar wall loading the fusion power of an illustrative high field, low current concept could be about 50% that of a lower field device like TIBER II. This reduction could lead to a 50% decrease in tritium consumption, resulting in a substantial decrease in operating cost. Furthermore, high field operation could lead to substantially reduced current drive requirements and cost. A reduction in current drive source power on the order of 40 to 50 MW may be attainable relative to a lower field, high current design like TIBER II implying a possible cost savings on the order of $200 M. If current drive is less efficient than assumed, the savings could be even greater. Through larger β/sub p/ and aspect ratio, greater prospects for bootstrap current operation also exist. Further savings would be obtained from the reduced size of the first wall/blanket/shield system. The effects of high fields on magnet costs are very dependent on technological assumptions. Further improvements in the future may lie with advances in superconducting and structural materials

  1. High-current beam transport in electrostatic accelerator tubes

    International Nuclear Information System (INIS)

    Ramian, G.; Elais, L.

    1987-01-01

    The UCSB Free Electron Laser (FEL) has successfully demonstrated the use of a commercial 6 megavolt electrostatic accelerator as a high current beam source in a recirculating configuration. The accelerator, manufactured by National Electrostatics Corp. (NEC), Middleton WI, uses two standard high gradient accelerator tubes. Suppression of ion multiplication was accomplished by NEC with apertures and a shaped electrostatic field. This field shaping has fortuitously provided a periodically reversing radial field component with sufficient focusing strength to transport electron beams of up to 3 Amps current. Present two-stage FEL work requires a 20 Amp beam and proposed very high voltage FEL designs require currents as high as 100 Amps. A plan to permit transport of such high current beams by the addition of solenoidal focussing elements is described

  2. 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

  3. Oscillographic Chronopotentiometry with High and Low Frequency Current

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel electroanalytical method, oscillographic chronopotentiometry with high and low frequency current, is presented in this paper. With this method, the sensitivity of almost all kinds of oscillographic chronopotentiometry can be enhanced about one order.

  4. 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.

  5. New initiatives for producing high current electron accelerators

    International Nuclear Information System (INIS)

    Faehl, R.J.; Keinigs, R.K.; Pogue, E.W.

    1996-01-01

    New classes of compact electron accelerators able to deliver multi-kiloamperes of pulsed 10-50 MeV electron beams are being studied. One class is based upon rf linac technology with dielectric-filled cavities. For materials with ε/ε o >>1, the greatly increased energy storage permits high current operation. The second type is a high energy injected betatron. Circulating current limits scale as Β 2 γ 3

  6. High current betatron research at the University of New Mexico

    International Nuclear Information System (INIS)

    Humphries, S. Jr.; Len, L.K.

    1987-01-01

    Betatrons are among the simplest of high energy accelerators. Their circuit is equivalent to a step-up transformer; the electron beam forms a multi-turn secondary winding. Circulation of the beam around the flux core allows generation of high energy electrons with relatively small core mass. As with any transformer, a betatron is energy inefficient at low beam current; the energy balance is dominated by core losses. This fact has prompted a continuing investigation of high current betatrons as efficient, compact sources of beta and gamma radiation. A program has been supported at the University of New Mexico by the Office of Naval Research to study the physics of high current electron beams in circular accelerators and to develop practical technology for high power betatrons. Fabrication and assembly of the main ring was completed in January of this year. In contrast to other recent high current betatron experiments the UNM device utilizes a periodic focusing system to contain high current beams during the low energy phase of the acceleration cycle. The reversing cusp fields generated by alternating polarity solenoidal lenses cancel beam drift motions induced by machine errors. In consequence, they have found that the cusp geometry has had significantly better stability properties than a monodirectional toroidal field. In comparison to other minimum-Β geometries such as the Stelllatron cusps have open field lines which facilitate beam injection and neutralization

  7. Morphodynamics of supercritical high-density turbidity currents

    NARCIS (Netherlands)

    Cartigny, M.

    2012-01-01

    Seafloor and outcrop observations combined with numerical and physical experiments show that turbidity currents are likely 1) to be in a supercritical flow state and 2) to carry high sediment concentrations (being of high-density). The thesis starts with an experimental study of bedforms

  8. HOM frequency control of SRF cavity in high current ERLs

    Science.gov (United States)

    Xu, Chen; Ben-Zvi, Ilan

    2018-03-01

    The acceleration of high-current beam in Superconducting Radio Frequency (SRF) cavities is a challenging but essential for a variety of advanced accelerators. SRF cavities should be carefully designed to minimize the High Order Modes (HOM) power generated in the cavities by the beam current. The reduction of HOM power we demonstrate in a particular case can be quite large. This paper presents a method to systematically control the HOM resonance frequencies in the initial design phase to minimize the HOM power generation. This method is expected to be beneficial for the design of high SRF cavities addressing a variety of Energy Recovery Linac (ERL) applications.

  9. High-current electron accelerator for gas-laser pumping

    Energy Technology Data Exchange (ETDEWEB)

    Badaliants, G R; Mamikonian, V A; Nersisian, G Ts; Papanian, V O

    1978-11-26

    A high-current source of pulsed electron beams has been developed for the pumping of UV gas lasers. The parameters of the device are: energy of 0.3-0.7 MeV pulse duration of 30 ns and current density (in a high-pressure laser chamber) of 40-100 A/sq cm. The principal feature of the device is the use of a rectangular cold cathode with incomplete discharge along the surface of the high-permittivity dielectric. Cathodes made of stainless steel, copper, and graphite were investigated.

  10. Evidence for intrinsic critical current density in high Tc superconductors

    International Nuclear Information System (INIS)

    Freltoft, T.; Minnhagen, P.; Jeldtoft Jensen, H.

    1991-01-01

    We present measurements of the voltage-current characteristics of high quality epitaxial YBaCuO films in zero magnetic field. According to the predictions of a current induced vortex pair breaking picture the voltage should follow the functional form V∝I(I-I c ) a-1 . An analysis designed to test this functional behavior is carried out. Consistency is found. (orig.)

  11. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, Alexandra; Koster, Sander; Hogen-Koster, S.; Eijkel, Jan C.T.; van den Berg, Albert; Lucklum, F.; Verpoorte, E.; de Rooij, Nico F.

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-µm-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachined

  12. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, A; Koster, Sander; Eijkel, JCT; van den Berg, A; Lucklum, F; Verpoorte, E; de Rooij, NF

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-mu m-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a

  13. Critical current of high Tc superconducting Bi223/Ag tapes

    NARCIS (Netherlands)

    Huang, Y.; ten Haken, Bernard; ten Kate, Herman H.J.

    1998-01-01

    The magnetic field dependence of the critical current of various high Tc superconducting Bi2223/Ag tapes indicates that the transport current is carried through two paths: one is through weakly-linked grain boundaries (Josephson junctions); another is through well-connected grains. The critical

  14. Characteristics of a High Current Helicon Ion Source With High Monatomic Fraction

    International Nuclear Information System (INIS)

    Jung, Hwa-Dong; Chung, Kyoung-Jae; Hwang, Yong-Seok

    2006-01-01

    Applications of neutron need compact and high yield neutron sources as well as very intense neutron sources from giant devices such as accelerators. Ion source based neutron sources using nuclear fusion reactions such as D(d, 3He)n, D(t, 4He)n can meet the requirements. This type of neutron generators can be simply composed of an ion source and a target. High-performance neutron generators with high yield require ion sources with high beam current, high monatomic fraction and long lifetime. Helicon ion source can meet these requirements. To make high current ion source, characteristics of helicon plasma such as high plasma density can be utilized. Moreover, efficient plasma heating with RF power lead high fraction of monatomic ion beam. Here, Characteristics of helicon plasma sources are described. Design and its performances of a helicon ion source are presented

  15. Transmission Level High Temperature Superconducting Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Gary [SuperPower, Inc., Schenectady, NY (United States)

    2016-10-05

    The primary objective of this project was to demonstrate the feasibility and reliability of utilizing high-temperature superconducting (HTS) materials in a Transmission Level Superconducting Fault Current Limiter (SFCL) application. During the project, the type of high-temperature superconducting material used evolved from 1st generation (1G) BSCCO-2212 melt cast bulk high-temperature superconductors to 2nd generation (2G) YBCO-based high-temperature superconducting tape. The SFCL employed SuperPower's “Matrix” technology, that offers modular features to enable scale up to transmission voltage levels. The SFCL consists of individual modules that contain elements and parallel inductors that assist in carrying the current during the fault. A number of these modules are arranged in an m x n array to form the current-limiting matrix.

  16. High current density aluminum stabilized conductor concepts for space applications

    International Nuclear Information System (INIS)

    Huang, X.; Eyssa, Y.M.; Hilal, M.A.

    1989-01-01

    Lightweight conductors are needed for space magnets to achieve values of E/M (energy stored per unit mass) comparable to the or higher than advanced batteries. High purity aluminum stabilized NbTi composite conductors cooled by 1.8 K helium can provide a winding current density up to 15 kA/cm/sup 2/ at fields up to 10 tesla. The conductors are edge cooled with enough surface area to provide recovery following a normalizing disturbance. The conductors are designed so that current diffusion time in the high purity aluminum is smaller than thermal diffusion time in helium. Conductor design, stability and current diffusion are considered in detail

  17. Design of high current injector for SPring-8

    International Nuclear Information System (INIS)

    Yoshikawa, H.; Nakamura, N.; Mizuno, A.; Suzuki, S.; Hori, T.; Yanagida, K.; Mashiko, K.; Yokomizo, H.

    1992-01-01

    The linac of SPring-8, large synchrotron radiation facility of Japan, has the option which is positron operation modes. The electron gun of this linac is designed on base of the optimization for a high current beam to get positrons as many as possible. But otherwise this linac should be used as an accurate electron beam generator for commissioning on the whole facility. This report shows differences of the beam specification between a high current beam and a low current beam. The bunching section of this linac has just been constructed this summer at Tokai-Lab. of JAERI to be confirmed with the specification. (author). 3 refs., 1 tab., 4 figs

  18. Current voltage characteristics of composite superconductors with high contact resistance

    International Nuclear Information System (INIS)

    Akhmetov, A.A.; Baev, V.P.

    1984-01-01

    An experimental study has been made of current-voltage characteristics of composite superconductors with contact resistance between superconducting filaments and normal metal with high electrical conductivity. It is shown that stable resistive states exist in such conductors over a wide range of currents. The presence of resistive states is interpreted in terms of the resistive domain concept. The minimum and maximum currents of resistive states are found to be dependent on the electrical resistance of normal metal and magnetic field. (author)

  19. Hall probe for measuring high currents in superconducting coils

    International Nuclear Information System (INIS)

    Ferendeci, A.M.

    1986-01-01

    Constructional details of a compact Hall probe for measuring high currents in superconducting coils are given. The Hall probe is easy to assemble and can be inserted or removed from the system without breaking the superconducting loop. Upper current limit of the probe can be increased by using larger magnetic core material. Shielding becomes necessary if the probe holder is to be placed near large current dependent magnetic fields

  20. High dislocation density of tin induced by electric current

    International Nuclear Information System (INIS)

    Liao, Yi-Han; Liang, Chien-Lung; Lin, Kwang-Lung; Wu, Albert T.

    2015-01-01

    A dislocation density of as high as 10 17 /m 2 in a tin strip, as revealed by high resolution transmission electron microscope, was induced by current stressing at 6.5 x 10 3 A/ cm 2 . The dislocations exist in terms of dislocation line, dislocation loop, and dislocation aggregates. Electron Backscattered Diffraction images reflect that the high dislocation density induced the formation of low deflection angle subgrains, high deflection angle Widmanstätten grains, and recrystallization. The recrystallization gave rise to grain refining

  1. HIGH-CURRENT ERL-BASED ELECTRON COOLING FOR RHIC

    International Nuclear Information System (INIS)

    BEN-ZVI, I.

    2005-01-01

    The design of an electron cooler must take into account both electron beam dynamics issues as well as the electron cooling physics. Research towards high-energy electron cooling of RHIC is in its 3rd year at Brookhaven National Laboratory. The luminosity upgrade of RHIC calls for electron cooling of various stored ion beams, such as 100 GeV/A gold ions at collision energies. The necessary electron energy of 54 MeV is clearly out of reach for DC accelerator system of any kind. The high energy also necessitates a bunched beam, with a high electron bunch charge, low emittance and small energy spread. The Collider-Accelerator Department adopted the Energy Recovery Linac (ERL) for generating the high-current, high-energy and high-quality electron beam. The RHIC electron cooler ERL will use four Superconducting RF (SRF) 5-cell cavities, designed to operate at ampere-class average currents with high bunch charges. The electron source will be a superconducting, 705.75 MHz laser-photocathode RF gun, followed up by a superconducting Energy Recovery Linac (ERL). An R and D ERL is under construction to demonstrate the ERL at the unprecedented average current of 0.5 amperes. Beam dynamics performance and luminosity enhancement are described for the case of magnetized and non-magnetized electron cooling of RHIC

  2. Lattice Effects Due to High Currents in PEP-II

    International Nuclear Information System (INIS)

    Decker, F.-J.; Smith, H.; Turner, J.L.; SLAC

    2005-01-01

    The very high beam currents in the PEP-II B-Factory have caused many expected and unexpected effects: Synchrotron light fans move the beam pipe and cause dispersion; higher order modes cause excessive heating, e-clouds around the positron beam blow up its beam size. Here we describe an effect where the measured dispersion of the beam in the Low Energy Ring (LER) is different at high and at low beam currents. The dispersion was iteratively lowered by making anti-symmetric orbit bumps in many sextupole duplets, checking each time with a dispersion measurement where a dispersive kick is generated. This can be done parasitically during collisions. It was a surprise when checking the low current characterization data that there is a change. Subsequent high and low current measurements confirmed the effect. One source was believed to be located far away from any synchrotron radiation in the middle of a straight (PR12), away from sextupoles and skew quadrupoles and created a dispersion wave of about 70 mm at high current while at low current it is negligible

  3. High School Sport Specialization Patterns of Current Division I Athletes.

    Science.gov (United States)

    Post, Eric G; Thein-Nissenbaum, Jill M; Stiffler, Mikel R; Brooks, M Alison; Bell, David R; Sanfilippo, Jennifer L; Trigsted, Stephanie M; Heiderscheit, Bryan C; McGuine, Timothy A

    Sport specialization is a strategy to acquire superior sport performance in 1 sport but is associated with increased injury risk. Currently, the degree of high school specialization among Division I athletes is unknown. College athletes will display increased rates of specialization as they progress through their high school careers. Descriptive epidemiological study. Level 4. Three hundred forty-three athletes (115 female) representing 9 sports from a Midwest Division I University completed a previously utilized sport specialization questionnaire regarding sport participation patterns for each grade of high school. McNemar and chi-square tests were used to investigate associations of grade, sport, and sex with prevalence of sport specialization category (low, moderate, high) (a priori P ≤ 0.05). Specialization increased throughout high school, with 16.9% (n = 58) and 41.1% (n = 141) of athletes highly specialized in 9th and 12th grades, respectively. Football athletes were less likely to be highly specialized than nonfootball athletes for each year of high school ( P 0.23). The majority of Division I athletes were not classified as highly specialized throughout high school, but the prevalence of high specialization increased as athletes progressed through high school. Nonfootball athletes were more likely to be highly specialized than football athletes at each grade level. Most athletes who are recruited to participate in collegiate athletics will eventually specialize in their sport, but it does not appear that early specialization is necessary to become a Division I athlete. Athletes should be counseled regarding safe participation in sport during high school to minimize injury and maximize performance.

  4. Design considerations for high-current superconducting ion linacs

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.; Micklich, B.J.; Roche, C.T.; Sagalovsky, L.

    1993-01-01

    Superconducting linacs may be a viable option for high-current applications such as fusion materials irradiation testing, spallation neutron source, transmutation of radioactive waste, tritium production, and energy production. These linacs must run reliably for many years and allow easy routine maintenance. Superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs, respectively. However, cost-effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement. Key aspects of high-current cw superconducting linac designs are explored in this context

  5. A High-Current, Stable Nonaqueous Organic Redox Flow Battery

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiaoliang; Duan, Wentao; Huang, Jinhua; Zhang, Lu; Li, Bin; Reed, David; Xu, Wu; Sprenkle, Vincent; Wang, Wei

    2016-10-14

    Nonaqueous redox flow batteries are promising in pursuit of high-energy storage systems owing to the broad voltage window, but currently are facing key challenges such as poor cycling stability and lack of suitable membranes. Here we report a new nonaqueous all-organic flow chemistry that demonstrates an outstanding cell cycling stability primarily because of high chemical persistency of the organic radical redox species and their good compatibility with the supporting electrolyte. A feasibility study shows that Daramic® and Celgard® porous separators can lead to high cell conductivity in flow cells thus producing remarkable cell efficiency and material utilization even at high current operations. This result suggests that the thickness and pore size are the key performance-determining factors for porous separators. With the greatly improved flow cell performance, this new flow system largely addresses the above mentioned challenges and the findings may greatly expedite the development of durable nonaqueous flow batteries.

  6. Low energy current accumulator for high-energy proton rings

    International Nuclear Information System (INIS)

    Month, M.

    1977-01-01

    Building current in high-energy p-p colliding beam machines is most appropriately done in a low-energy (small circumference) current accumulator. Three significant factors favor such a procedure: First, large rings tend to be susceptible to unstable longitudinal density oscillations. These can be avoided by pumping up the beam in the accumulator. When the current stack is injected into the storage ring, potentially harmful instability is essentially neutralized. Second, high-field magnets characteristic of future high energy proton rings are designed with superconducting coils within the iron magnetic shield. This means coil construction and placement errors propagate rapidly within the beam aperture. An intermediate ''stacking ring'' allows the minimum use of the superconducting ring aperture. Finally, the coils are vulnerable to radiation heating and possible magnet quenching. By minimizing beam manipulaion in the superconducting environment and using only the central portion of the beam aperture, coil vulnerability can be put at a minimum

  7. Development of a high brightness, high current SRF photo-electron source for ERL applications

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Axel [Helmholtz-Zentrum Berlin (Germany); Collaboration: bERLinPro Team

    2016-07-01

    Energy recovery linacs (ERL) offer the potential to combine major beam properties of the two main domains of particle accelerators: The low emittance of linear accelerators and the high average beam current of storage rings, while also allowing to compress to short bunches below the ps regime. This makes among other applications ERLs an ideal candidate for future light sources. The beam properties of the ERL are given by the performance of the injection section and hence of the beam source. Helmholtz-Zentrum Berlin is currently designing and building a high average current all superconducting CW driven ERL as a prototype to demonstrate low normalized beam emittance of 1 mm*mrad at 100 mA and short pulses of about 2 ps. In this contribution we discuss the development of this class of a high brightness, high current SRF photo-electron source and present recent commissioning results. Also, alternative approaches at other laboratories are shortly reviewed.

  8. Preparation and characterization of high-Tc superconducting thin films with high critical current densities

    International Nuclear Information System (INIS)

    Vase, P.

    1991-08-01

    The project was carried out in relation to possible cable and electronics applications of high-T c materials. Laser ablation was used as the deposition technique because of its stoichiometry conservation. Films were made in the YBa 2 Cu 3 O 7 compound due to its relatively simple stoichiometry compared to other High-T c compounds. Much attention was paid to the critical current density. A very high critical current density was reached. By using texture analysis by X-ray diffraction, it was found that films with high critical current densities were epitaxial, while films with low critical current densities contained several crystalline orientations. Four techniques for patterning the films were used - photo lithography and wet etch, laser ablation lithography, laser writing and electron beam lithography and ion milling. Sub-micron patterning has been demonstrated without degradation of the superconducting properties. The achieved patterning resolution is sufficient for preparation of many superconducting components. (AB)

  9. Application of RF Superconductivity to High-Current Linac

    International Nuclear Information System (INIS)

    Chan, K.C.D.

    1998-01-01

    In 1997, the authors initiated a development program in Los Alamos for high-current superconducting proton-linac technology to build prototypes components of this linac to demonstrate the feasibility. The authors are building 700-MHz niobium cavities with elliptical shapes, as well as power couplers to transfer high RF power to these cavities. The cavities and power couplers will be integrated in cryostats as linac cryomodules. In this paper, they describe the linac design and the status of the development program

  10. High School Sport Specialization Patterns of Current Division I Athletes

    OpenAIRE

    Post, Eric G.; Thein-Nissenbaum, Jill M.; Stiffler, Mikel R.; Brooks, M. Alison; Bell, David R.; Sanfilippo, Jennifer L.; Trigsted, Stephanie M.; Heiderscheit, Bryan C.; McGuine, Timothy A.

    2016-01-01

    Background: Sport specialization is a strategy to acquire superior sport performance in 1 sport but is associated with increased injury risk. Currently, the degree of high school specialization among Division I athletes is unknown. Hypothesis: College athletes will display increased rates of specialization as they progress through their high school careers. Study Design: Descriptive epidemiological study. Level of Evidence: Level 4. Methods: Three hundred forty-three athletes (115 female) rep...

  11. Liquid metal current collectors for high-speed rotating machinery

    International Nuclear Information System (INIS)

    Carr, S.L.

    1976-01-01

    Recent interest in superconducting motors and generators has created a renewed interest in homopolar machinery. Homopolar machine designs have always been limited by the need for compact, high-current, low-voltage, sliding electrical curent collectors. Conventional graphite-based solid brushes are inadequate for use in homopolar machines. Liquid metals, under certain conditions of relative sliding velocities, electrical currents, and magnetic fields are known to be capable of performing well in homopolar machines. An effort to explore the capabilities and limits of a tongue-and-groove style current collector, utilizing sodium-potassium eutectic alloy (NaK) as the working fluid in high sliding speed operation is reported here. A double current collector generator model with a 14.5-cm maximum rotor diameter, 20,000 rpm rotational capability, and electrical current carrying ability was constructed and operated successfully at a peripheral velocity of 125 m/s. The limiting factor in these experiments was a high-speed fluid-flow instability resulting in the ejection of the working fluid from the operating portions of the collectors. The effects of collector size and geometry, working fluid (NaK or water), and cover gas pressure are reported. Hydrodynamic frictional torque-speed curves are given for the two fluids and for several geometries. Electrical resistances as a function of peripheral velocity at 60 amperes are reported, and the phenomenology of the high-speed fluid-flow instabilities is discussed. The possibility of long-term high-speed operation of current collectors of the tongue-and-groove type, along with experimental and theoretical hydrodynamic friction losses at high peripheral velocities, is considered

  12. A review of high beam current RFQ accelerators and funnels

    International Nuclear Information System (INIS)

    Schneider, J.D.

    1998-01-01

    The authors review the design features of several high-current (> 20-mA) and high-power (> 1-mA average) proton or H - injectors, RFQs, and funnels. They include a summary of observed performance and will mention a sampling of new designs, including the proposed incorporation of beam choppers. Different programs and organizations have chosen to build the RFQ in diverse configurations. Although the majority of RFQs are either low-current or very low duty-factor, several versions have included high-current and/or high-power designs for either protons or H - ions. The challenges of cooling, handling high space-charge forces, and coupling with injectors and subsequent accelerators are significant. In all instances, beam tests were a valuable learning experience, because not always did these as-built structures perform exactly as predicted by the earlier design codes. They summarize the key operational parameters, indicate what was achieved, and highlight what was learned in these tests. Based on this generally good performance and high promise, even more challenging designs are being considered for new applications that include even higher powers, beam funnels and choppers

  13. Electron gun for formation of two high-current beams

    International Nuclear Information System (INIS)

    Borisov, A.R.; Zherlitsyn, A.G.; Mel'nikov, G.V.; Shtejn, Yu.G.

    1982-01-01

    The design of the ''Tonus'' accelerator electron gun for formation of two high-current beams aiming at the production of the maximum beam power and density is described. The results of investigation of two modes of beam formation are presented. In the first variant the beams were produced by means of two plane diodes with 40 mm diameter cathodes made of stainless steel and anodes made of 50 μm thick titanium foil. In the second variant the beams were formed by means of two coaxial diodes with magnetic insulation. In one diode the cathode diameter equals to 74 mm, the anode diameter - 92 mm, in the other diode 16 and 44 mm respectively. Current redistribution in the diodes and its effect on accelerating voltage are investigated. It is shown that the gun permits formation of synchronized two high-current beams, iaving equal electron energied. Wide range current control of both beams is possible

  14. PV source based high voltage gain current fed converter

    Science.gov (United States)

    Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.

    2017-11-01

    This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.

  15. Use of high current density superconducting coils in fusion devices

    International Nuclear Information System (INIS)

    Green, M.A.

    1979-11-01

    Superconducting magnets will play an important role in fusion research in years to come. The magnets which are currently proposed for fusion research use the concept of cryostability to insure stable operation of the superconducting coils. This paper proposes the use of adiabatically stable high current density superconducting coils in some types of fusion devices. The advantages of this approach are much lower system cold mass, enhanced cryogenic safety, increased access to the plasma and lower cost

  16. 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

  17. A high-current, high-voltage power supply with special output current waveform for APS injector synchrotron dipole magnets

    International Nuclear Information System (INIS)

    Fathizadeh, M.; Despe, O.D.; McGhee, D.G.; Mills, F.E.; Turner, L.R.

    1991-01-01

    This paper describes a high-voltage, high-current power supply for the injector synchrotron dipole magnets at APS. In order to reset the dipole magnets in each cycle two different current waveforms are suggested. The first current waveform consists of three sections, namely: dc-reset, linear ramp, and recovery sections where injection is done ''on the fly''. The second current waveform consists of six different sections, dc-reset, transition to injection level, injection flat level, parabolic, linear ramp and recovery sections. The effect of such waveforms on the beam is discussed and the power supply limitations to follow such waveforms are given. The power supply limitations are due to the power components and control loops. The reference for the current loop is generated by a DAC which is discussed

  18. Design and application consideration of high temperature superconducting current leads

    International Nuclear Information System (INIS)

    Wu, J.L.

    1994-01-01

    As a potential major source of heat leak and the resultant cryogen boiloff, cryogenic current leads can significantly affect the refrigeration power requirement of cryogenic power equipment. Reduction of the heat leak associated with current leads can therefore contribute to the development and application of this equipment. Recent studies and tests have demonstrated that, due to their superconducting and low thermal conductivity properties, ceramic high temperature superconductor (HTSC) can be employed in current leads to significantly reduce the heat leak. However, realization of this benefit requires special design considerations pertaining to the properties and the fabrication technology of the relatively new ceramic superconductor materials. Since processing and fabrication technology are continuously being developed in the laboratories, data on material properties unrelated to critical states are quite limited. Therefore, design analysis and experiments have to be conducted in tandem to achieve a successful development. Due to the rather unique combination of superconducting and thermal conductivities which are orders of magnitude lower than copper, ceramic superconductors allow expansion of the operating scenarios of current leads. In addition to the conventional vapor-cooled lead type application, low heat leak conduction-cooled type current leads may be practical and are being developed. Furthermore, a current lead with an intermediate heat leak intercept has been successfully demonstrated in a multiple current lead assembly employing HTSC. These design and application considerations of high temperature superconducting current leads are addressed here

  19. Microstructures and critical currents in high-Tc superconductors

    International Nuclear Information System (INIS)

    Suenaga, Masaki

    1998-01-01

    Microstructural defects are the primary determining factors for the values of critical-current densities in a high T c superconductor after the electronic anisotropy along the a-b plane and the c-direction. A review is made to assess firstly what would be the maximum achievable critical-current density in YBa 2 Cu 3 O 7 if nearly ideal pinning sites were introduced and secondly what types of pinning defects are currently introduced or exist in YBa 2 Cu 3 O 7 and how effective are these in pinning vortices

  20. The design of high performance weak current integrated amplifier

    International Nuclear Information System (INIS)

    Chen Guojie; Cao Hui

    2005-01-01

    A design method of high performance weak current integrated amplifier using ICL7650 operational amplifier is introduced. The operating principle of circuits and the step of improving amplifier's performance are illustrated. Finally, the experimental results are given. The amplifier has programmable measurement range of 10 -9 -10 -12 A, automatic zero-correction, accurate measurement, and good stability. (authors)

  1. Observed currents at Bombay High during a winter

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A; Chandramohan, P.; Nayak, B.U.

    Ten day records of Aanderaa current meters (24 Dec 1981 to 2 Jan. 1982) at four depths, viz. 30, 45, 60 and 75 m at Bombay High (19˚24.5'N, 71˚2.5'E) off the west coast of India, in a water depth of 80 m have been subjected to spectral, cross...

  2. Observations of propagating double layers in a high current discharge

    International Nuclear Information System (INIS)

    Lindberg, L.

    1988-01-01

    Observations of current disruptions and strong electric fields along the magnetic field in a high-density (2 x 10 19 m - 3 , highly-ionized, moving, and expanding plasma column are reported. The electric field is interpreted in terms of propagating, strong electric double layers (3-5kV). An initial plasma column is formed in an axial magnetic field (0.1T) by means of a conical theta-pinch plasma gun. When an axial current (max 5kA, 3-5 kV) is drawn through the column spontaneous disruptions and double-layer formation occur within a few microseconds. Floating, secondary emitting Langmuir probes are used. They often indicate very high positive potential peaks (1-2 kV above the anode potential during a few μs) in the plasma on the positive side of the double layer. Short, intense bursts of HF radiation are detected at the disruptions

  3. Resistive current limiter with high-temperature superconductors. Final report

    International Nuclear Information System (INIS)

    Schubert, M.

    1995-12-01

    Fundamental results of the possibility of using high temperature superconductors (HTSC) in resistive fault current limiters are discussed. Measurement of the homogeneity of BSCCO-powder-in-tube materials were made. In addition, investigations of the transition from superconducting to normalconducting state under AC-current conditions were carried out. Based on these results, simulations of HTSC-materials on ceramic substrate were made and recent results are presented. Important results of the investigations are: 1. Current-limiting without external trigger only possible when the critical current density of HTSC exceeds 10 4 A/cm 2 . 2. Inhomogeneities sometimes cause problems with local destruction. This can be solved by parallel-elements or external trigger. 3. Fast current-limiting causes overvoltages which can be reduced by using parallel-elements. (orig.) [de

  4. Processing and critical currents of high-Tc superconductor wires

    International Nuclear Information System (INIS)

    Krauth, H.; Heine, K.; Tenbrink, J.

    1991-01-01

    High-Tc superconductors are expected to have a major impact on magnet and energy technology. For technical applications they have to fulfill the requirement of carrying sufficient current at a critical current density of the order of 10 5 A/cm 2 at operating temperature and magnetic field. At 77 K these values have not been achieved yet in bulk material or wires due to weak link problems and flux creep effects. Progress made so far and remaining problems will be discussed in detail concentrating on problems concerning development of technical wires. In Bi-based materials technically interesting critical current densities could be achieved at 4.2 K in fields above 20 T (1,2), rendering possible the use of such material for very high field application. (orig.)

  5. 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...

  6. High current density magnets for INTOR and TIBER

    International Nuclear Information System (INIS)

    Miller, J.R.; Henning, C.D.; Kerns, J.A.; Slack, D.S.; Summers, L.T.; Zbasnik, J.P.

    1986-12-01

    The adoption of high current density, high field, superconducting magnets for INTOR and TIBER would prove beneficial. When combined with improved radiation tolerance of the magnets to minimize the inner leg shielding, a substantial reduction in machine dimensions and capital costs can be achieved. Fortunately, cable-in-conduit conductors (CICC) which are capable of the desired enhancements are being developed. Because conductor stability in a CICC depends more on the trapped helium enthalpy, rather than the copper resistivity, higher current densities of the order of 40 A/mm 2 at 12 T are possible. Radiation damage to the copper stabilizer is less important because the growth in resistance is a second-order effect on stability. Such CICC conductors lend themselves naturally to niobium-tin utilization, with the benefits of the high current-sharing temperature of this material being taken to advantage in absorbing radiation heating. When the helium coolant is injected at near the critical pressure, Joule-Thompson expansion in the flow path tends to stabilize the fluid temperature at under 6 K. Thus, higher fields, as well as higher current densities, can be considered for INTOR or TIBER

  7. Energy confinement in a high-current reversed field pinch

    International Nuclear Information System (INIS)

    An, Z.G.; Lee, G.S.; Diamond, P.H.

    1985-07-01

    The ion temperature gradient driven (eta/sub i/) mode is proposed as a candidate for the cause of anomalous transport in high current reversed field pinches. A 'four-field' fluid model is derived to describe the coupled nonlinear evolution of resistive interchange and eta/sub i/ modes. A renormalized theory is discussed, and the saturation level of the fluctuations is analytically estimated. Transport scalings are obtained, and their implications discussed. In particular, these results indicate that pellet injection is a potentially viable mechanism for improving energy confinement in a high temperature RFP

  8. High-current Rhodotron for X-ray facility

    International Nuclear Information System (INIS)

    Umezu, Toru; Tsujiura, Yuichiro; Bol, Jean Louis

    2009-01-01

    The Rhodotron is a widely employed high-power industrial accelerator developed and exclusively distributed by IBA. Most early examples of the accelerator were optimized to operate at 10 MeV. A new Rhodotron configuration recently advanced produces a lower-energy higher-current beam dedicated with x-ray to sterilize and enhancement materials. Core elements of this system's evolution include a higher performance RF electron gun (operating range, response control, and cathode lifetime). This operational machine is now producing 100 mA at 7 MeV (700 kW of beam) and treat medical devices, thick cable and pipes with a high efficiency. (author)

  9. High current proton linear accelerators and nuclear power

    International Nuclear Information System (INIS)

    Tunnicliffe, P.R.; Chidley, B.G.; Fraser, J.S.

    1976-01-01

    This paper outlines a possible role that high-current proton linear accelerators might play as ''electrical breeders'' in the forthcoming nuclear-power economy. A high-power beam of intermediate energy protons delivered to an actinide-element target surrounded by a blanket of fertile material may produce fissile material at a competitive cost. Criteria for technical performance and, in a Canadian context, for costs are given and the major problem areas outlined not only for the accelerator and its associated rf power source but also for the target assembly. (author)

  10. Compilation of current high-energy-physics experiments

    International Nuclear Information System (INIS)

    Wohl, C.G.; Kelly, R.L.; Armstrong, F.E.

    1980-04-01

    This is the third edition of a compilation of current high energy physics experiments. It is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and ten participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), the Institute for Nuclear Study, Tokyo (INS), KEK, Rutherford (RHEL), Serpukhov (SERP), and SLAC. The compilation includes summaries of all high energy physics experiments at the above laboratories that (1) were approved (and not subsequently withdrawn) before about January 1980, and (2) had not completed taking of data by 1 January 1976

  11. Rf Gun with High-Current Density Field Emission Cathode

    International Nuclear Information System (INIS)

    Jay L. Hirshfield

    2005-01-01

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  12. Testing and evaluation of high temperature superconductor current leads

    International Nuclear Information System (INIS)

    Yadav, Anand; Puntambekar, Avinash; Manekar, M.A.

    2009-01-01

    National Institute for Inter-disciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research, Trivandrum (formerly Regional Research Laboratory) has accomplished a DAE-BRNS project with Raja Ramanna Centre for Advanced Technology (RRCAT) as principal collaborator for the development of high temperature superconductor (HTS) current leads. These HTS current leads have self-field critical currents (Ic) ranging from 50 A to 1000 A at liquid nitrogen (LN 2 ) temperature. These HTS are made out of silver sheathed Bismuth Strontium Calcium Copper Oxide (BSCCO-2223), for direct application in superconducting (SC) systems involving transportation of high electric currents from power sources at room temperature to superconducting devices at cryogenic temperatures. RRCAT has participated in this project by testing and evaluation of these HTS current leads and carried out actual load trials. In this paper, we will describe the HTS testing setup, tests performed with their testing procedure and the test results. The testing of these HTS has been done with joint effort of Materials Advanced Accelerator Science and Cryogenics Div. and Superconducting Technology Lab (SCT Lab), Advanced Accelerator Module Development Div., using the test facility available at the SCT Lab. (author)

  13. High-Current-Density Vertical-Tunneling Transistors from Graphene/Highly Doped Silicon Heterostructures.

    Science.gov (United States)

    Liu, Yuan; Sheng, Jiming; Wu, Hao; He, Qiyuan; Cheng, Hung-Chieh; Shakir, Muhammad Imran; Huang, Yu; Duan, Xiangfeng

    2016-06-01

    Scalable fabrication of vertical-tunneling transistors is presented based on heterostructures formed between graphene, highly doped silicon, and its native oxide. Benefiting from the large density of states of highly doped silicon, the tunneling transistors can deliver a current density over 20 A cm(-2) . This study demonstrates that the interfacial native oxide plays a crucial role in governing the carrier transport in graphene-silicon heterostructures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. High-speed radiography and x-ray cinematography by high-current betatrons

    International Nuclear Information System (INIS)

    Akimochkin, Yu.V.; Akulov, G.V.; Leunov, F.G.; Moskalev, V.A.; Ryabukhin, V.L.

    1979-01-01

    The paper provides a description of an equipment system comprising a pair of 25 MeV high-current betatrons and an X-ray drum-type cinecamera for high-speed radiography and X-ray cinematography for use when studying dynamics of objects moving at a rate of 0.5 - 3.0 km/s as well as in X-ray cinematography of processes at a rate of up to 1 m/s. (author)

  15. Stability of large orbit, high-current particle rings

    International Nuclear Information System (INIS)

    Lovelace, R.V.E.

    1994-01-01

    A review is made of theory of the low-frequency stability of large orbit, high-current particle rings which continue to be of interest for compact fusion systems. The precession mode was the first mode predicted by Furth and observed by Christofilos to be unstable under certain conditions. Subsequently, many detailed studies have been made of the stability of particle rings- different modes, different ring geometries, systems with/without a toroidal B field, and sytems with/without a current carrying plasma component. The possibly dangerous modes are still thought to include the precession mode, the tilting mode, and the low order kink modes. copyright American Institute of Physics

  16. Crane RF accelerator for high current radiation damage studies

    International Nuclear Information System (INIS)

    Whitham, K.; Anamkath, H.; Evans, K.; Lyons, S.; Palmer, D.; Miller, R.; Treas, P.; Zante, T.

    1992-01-01

    An electron accelerator was designed and built for the Naval Weapons Support Center for transient radiation effects on electronics experiments and testing. The Crane L Band RF Electron Linac was designed to provide high currents over a wide range of pulse widths and energies. The energy extends to 60 MeV and pulse widths vary from a few ns to 10 μsec. Beam currents range from 20 amps in the short pulse case to 1.5 amps in the long pulse case. This paper describes the linac, its architecture, the e-gun and pulser, waveguides, klystrons and modulator, vacuum system, beam transport, and control systems. fig., tab

  17. High-current proton accelerators-meson factories

    International Nuclear Information System (INIS)

    Dmitrievskij, V.P.

    1979-01-01

    A possibility of usage of accelerators of neutron as well as meson factories is considered. Parameters of linear and cyclic accelerators are given, which are employed as meson factories and as base for developing intense neutron generators. It is emphasized that the principal aim of developing neutron generators on the base of high current proton accelerators is production of intense neutron fluxes with a present energy spectrum. Production of tens-and-hundreds milliampere currents at the energy of 800-1000 MeV is considered at present for two types of accelerating facilities viz. linear accelerators under continuous operating conditions and cyclotrons with strong focusing. Quantitative evaluations of developing high-efficiency linear and cyclic accelerators are considered. The basic parameters of an ccelerating complex are given, viz. linear accelerator-injector and 800 MeV isochronous cyclotron. The main problems associated with their realization are listed [ru

  18. High performance current generator with one-picoampere resolution

    International Nuclear Information System (INIS)

    Grillo, L.; Manfredi, P.F.; Marchesini, R.

    1975-01-01

    A high-performance current generator for the picoampere region is presented. Although it was primarily developed as a part of an automatic test system to calibrate charge integrators for accelerating machines. It can suit a wide range of applications. It consists basically of a positive feedback loop of controlled gain which includes a varactor bridge operational amplifier. The essential features of the instrument are a 1 pA resolution and a 10 15 Ω output impedance. The output is guarded and floating between - 120 V and + 120 V, and the voltage across the external loads is measured without affecting the delivered current by a digital panel meter on the front panel. The unit can therefore operate as a high-accuracy dc impedance meter. (Auth.)

  19. Generation of sheet currents by high frequency fast MHD waves

    Energy Technology Data Exchange (ETDEWEB)

    Núñez, Manuel, E-mail: mnjmhd@am.uva.es

    2016-07-01

    The evolution of fast magnetosonic waves of high frequency propagating into an axisymmetric equilibrium plasma is studied. By using the methods of weakly nonlinear geometrical optics, it is shown that the perturbation travels in the equatorial plane while satisfying a transport equation which enables us to predict the time and location of formation of shock waves. For plasmas of large magnetic Prandtl number, this would result into the creation of sheet currents which may give rise to magnetic reconnection and destruction of the original equilibrium. - Highlights: • Regular solutions of quasilinear hyperbolic systems may evolve into shocks. • The shock location is found for high frequency fast MHD waves. • The result is applied to static axisymmetric equilibria. • The previous process may lead to the formation of sheet currents and destruction of the equilibrium.

  20. Development of large high current density superconducting solenoid magnets for use in high energy physics experiments

    International Nuclear Information System (INIS)

    Green, M.A.

    1977-05-01

    The development of a unique type of large superconducting solenoid magnet, characterized by very high current density windings and a two-phase helium tubular cooling system is described. The development of the magnet's conceptual design and the construction of two test solenoids are described. The successful test of the superconducting coil and its tubular cooling refrigeration system is presented. The safety, environmental and economic impacts of the test program on future developments in high energy physics are shown. Large solid angle particle detectors for colliding beam physics will analyze both charged and neutral particles. In many cases, these detectors will require neutral particles, such as gamma rays, to pass through the magnet coil with minimum interaction. The magnet coils must be as thin as possible. The use of superconducting windings allows one to minimize radiation thickness, while at the same time maximizing charged particle momentum resolution and saving substantial quantities of electrical energy. The results of the experimental measurements show that large high current density solenoid magnets can be made to operate at high stored energies. The superconducting magnet development described has a positive safety and environmental impact. The use of large high current density thin superconducting solenoids has been proposed in two high energy physics experiments to be conducted at the Stanford Linear Accelerator Center and Cornell University as a result of the successful experiments described

  1. LTS and HTS high current conductor development for DEMO

    International Nuclear Information System (INIS)

    Bruzzone, Pierluigi; Sedlak, Kamil; Uglietti, Davide; Bykovsky, Nikolay; Muzzi, Luigi; De Marzi, Gainluca; Celentano, Giuseppe; Della Corte, Antonio; Turtù, Simonetta; Seri, Massimo

    2015-01-01

    Highlights: • Design and R&D for DEMO TF conductors. • Wind&react vs. react&wind options for Nb_3Sn high grade TF conductors. • Progress in the manufacture of short length Nb_3Sn proptotypes. • Design and prototype manufacture for high current HTS cabled conductors. - Abstract: The large size of the magnets for DEMO calls for very large operating current in the forced flow conductor. A plain extrapolation from the superconductors in use for ITER is not adequate to fulfill the technical and cost requirements. The proposed DEMO TF magnets is a graded winding using both Nb_3Sn and NbTi conductors, with operating current of 82 kA @ 13.6 T peak field. Two Nb_3Sn prototypes are being built in 2014 reflecting the two approaches suggested by CRPP (react&wind method) and ENEA (wind&react method). The Nb_3Sn strand (overall 200 kg) has been procured at technical specification similar to ITER. Both the Nb_3Sn strand and the high RRR, Cr plated copper wire (400 kg) have been delivered. The cabling trials are carried out at TRATOS Cavi using equipment relevant for long length production. The completion of the manufacture of the two 20 m long prototypes is expected in the end of 2014 and their test is planned in 2015 at CRPP. In the scope of a long term technology development, high current HTS conductors are built at CRPP and ENEA. A DEMO-class prototype conductor is developed and assembled at CRPP: it is a flat cable composed of 20 twisted stacks of coated conductor tape soldered into copper shells. The 10 kA conductor developed at ENEA consists of stacks of coated conductor tape inserted into a slotted and twisted Al core, with a central cooling channel. Samples have been manufactured in industrial environment and the scalability of the process to long production lengths has been proven.

  2. Ion beams from high-current PF facilities

    Energy Technology Data Exchange (ETDEWEB)

    Sadowski, M [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1997-12-31

    Pulsed beams of fast deuterons and impurity or admixture ions emitted from high-current PF-type facilities operated in different laboratories are dealt with. A short comparative analysis of time-integrated and time-resolved studies is presented. Particular attention is paid to the microstructure of such ion beams, and to the verification of some theoretical models. (author). 5 figs., 19 refs.

  3. [Extensive injuries due to high-tension electrical current].

    Science.gov (United States)

    Tomásek, D; Königová, R; Snupárek, Z

    1989-03-01

    The authors submit a case of severe injury with high tension electric current. They emphasize the necessity of prevention of this injury which occurs most frequently when transformer stations are not adequately safeguarded, in case of inadequate protection when approaching trolley wires on the railway track, and when safety principles are not respected during work on the railway. The authors draw attention to the importance of immediate resuscitation and multidisciplinary comprehensive care.

  4. 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.

  5. Current status of high energy nucleon-meson transport code

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Hiroshi; Sasa, Toshinobu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Current status of design code of accelerator (NMTC/JAERI code), outline of physical model and evaluation of accuracy of code were reported. To evaluate the nuclear performance of accelerator and strong spallation neutron origin, the nuclear reaction between high energy proton and target nuclide and behaviors of various produced particles are necessary. The nuclear design of spallation neutron system used a calculation code system connected the high energy nucleon{center_dot}meson transport code and the neutron{center_dot}photon transport code. NMTC/JAERI is described by the particle evaporation process under consideration of competition reaction of intranuclear cascade and fission process. Particle transport calculation was carried out for proton, neutron, {pi}- and {mu}-meson. To verify and improve accuracy of high energy nucleon-meson transport code, data of spallation and spallation neutron fragment by the integral experiment were collected. (S.Y.)

  6. Record high-average current from a high-brightness photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, Bruce; Barley, John; Bartnik, Adam; Bazarov, Ivan; Cultrera, Luca; Dobbins, John; Hoffstaetter, Georg; Johnson, Brent; Kaplan, Roger; Karkare, Siddharth; Kostroun, Vaclav; Li Yulin; Liepe, Matthias; Liu Xianghong; Loehl, Florian; Maxson, Jared; Quigley, Peter; Reilly, John; Rice, David; Sabol, Daniel [Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853 (United States); and others

    2013-01-21

    High-power, high-brightness electron beams are of interest for many applications, especially as drivers for free electron lasers and energy recovery linac light sources. For these particular applications, photoemission injectors are used in most cases, and the initial beam brightness from the injector sets a limit on the quality of the light generated at the end of the accelerator. At Cornell University, we have built such a high-power injector using a DC photoemission gun followed by a superconducting accelerating module. Recent results will be presented demonstrating record setting performance up to 65 mA average current with beam energies of 4-5 MeV.

  7. Double disordered YBCO coated conductors of industrial scale: high currents in high magnetic field

    International Nuclear Information System (INIS)

    Abraimov, D; Francis, A; Jaroszynski, J; McCallister, J; Polyanskii, A; Santos, M; Viouchkov, Y L; Ballarino, A; Bottura, L; Rossi, L; Barth, C; Senatore, C; Dietrich, R; Rutt, A; Schlenga, K; Usoskin, A; Majkic, G S; Selvamanickam, V

    2015-01-01

    A significant increase of critical current in high magnetic field, up to 31 T, was recorded in long tapes manufactured by employing a double-disorder route. In a double-disordered high-temperature superconductor (HTS), a superimposing of intrinsic and extrinsic disorder takes place in a way that (i) the intrinsic disorder is caused by local stoichiometry deviations that lead to defects of crystallinity that serve as pining centers in the YBa 2 Cu 3 O x−δ matrix and (ii) the extrinsic disorder is introduced via embedded atoms or particles of foreign material (e.g. barium zirconate), which create a set of lattice defects. We analyzed possible technological reasons for this current gain. The properties of these tapes over a wider field-temperature range as well as field anisotropy were also studied. Record values of critical current as high as 309 A at 31 T, 500 A at 18 Tm and 1200 A at 5 T were found in 4 mm wide tape at 4.2 K and B perpendicular to tape surface. HTS layers were processed in medium-scale equipment that allows a maximum batch length of 250 m while 22 m long batches were provided for investigation. Abnormally high ratios (up to 10) of critical current density measured at 4.2 K, 19 T to critical current density measured at 77 K, self-field were observed in tapes with the highest in-field critical current. Anisotropy of the critical current as well as angular dependences of n and α values were investigated. The temperature dependence of critical current is presented for temperatures between 4.2 and 40 K. Prospects for the suppression of the dog-bone effect by Cu plating and upscale of processing chain to >500 m piece length are discussed. (paper)

  8. Double disordered YBCO coated conductors of industrial scale: high currents in high magnetic field

    Science.gov (United States)

    Abraimov, D.; Ballarino, A.; Barth, C.; Bottura, L.; Dietrich, R.; Francis, A.; Jaroszynski, J.; Majkic, G. S.; McCallister, J.; Polyanskii, A.; Rossi, L.; Rutt, A.; Santos, M.; Schlenga, K.; Selvamanickam, V.; Senatore, C.; Usoskin, A.; Viouchkov, Y. L.

    2015-11-01

    A significant increase of critical current in high magnetic field, up to 31 T, was recorded in long tapes manufactured by employing a double-disorder route. In a double-disordered high-temperature superconductor (HTS), a superimposing of intrinsic and extrinsic disorder takes place in a way that (i) the intrinsic disorder is caused by local stoichiometry deviations that lead to defects of crystallinity that serve as pining centers in the YBa2Cu3O x-δ matrix and (ii) the extrinsic disorder is introduced via embedded atoms or particles of foreign material (e.g. barium zirconate), which create a set of lattice defects. We analyzed possible technological reasons for this current gain. The properties of these tapes over a wider field-temperature range as well as field anisotropy were also studied. Record values of critical current as high as 309 A at 31 T, 500 A at 18 Tm and 1200 A at 5 T were found in 4 mm wide tape at 4.2 K and B perpendicular to tape surface. HTS layers were processed in medium-scale equipment that allows a maximum batch length of 250 m while 22 m long batches were provided for investigation. Abnormally high ratios (up to 10) of critical current density measured at 4.2 K, 19 T to critical current density measured at 77 K, self-field were observed in tapes with the highest in-field critical current. Anisotropy of the critical current as well as angular dependences of n and α values were investigated. The temperature dependence of critical current is presented for temperatures between 4.2 and 40 K. Prospects for the suppression of the dog-bone effect by Cu plating and upscale of processing chain to >500 m piece length are discussed.

  9. MHD Modeling of Conductors at Ultra-High Current Density

    International Nuclear Information System (INIS)

    ROSENTHAL, STEPHEN E.; DESJARLAIS, MICHAEL P.; SPIELMAN, RICK B.; STYGAR, WILLIAM A.; ASAY, JAMES R.; DOUGLAS, M.R.; HALL, C.A.; FRESE, M.H.; MORSE, R.L.; REISMAN, D.B.

    2000-01-01

    In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator, the authors have revisited a problem first described in detail by Heinz Knoepfel. Unlike the 1-Tesla MITLs of pulsed power accelerators used to produce intense particle beams, Z's disc transmission line (downstream of the current addition) is in a 100--1,200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 they have been investigating the conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are (1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into the MHD computations. Certain features are strongly dependent on the details of the conductivity model

  10. Electronic Current Transducer (ECT) for high voltage dc lines

    Science.gov (United States)

    Houston, J. M.; Peters, P. H., Jr.; Summerayes, H. R., Jr.; Carlson, G. J.; Itani, A. M.

    1980-02-01

    The development of a bipolar electronic current transducer (ECT) for measuring the current in a high voltage dc (HVDC) power line at line potential is discussed. The design and construction of a free standing ECT for use on a 400 kV line having a nominal line current of 2000 A is described. Line current is measured by a 0.0001 ohm shunt whose voltage output is sampled by a 14 bit digital data link. The high voltage interface between line and ground is traversed by optical fibers which carry digital light signals as far as 300 m to a control room where the digital signal is converted back to an analog representation of the shunt voltage. Two redundant electronic and optical data links are used in the prototype. Power to operate digital and optical electronics and temperature controlling heaters at the line is supplied by a resistively and capacitively graded 10 stage cascade of ferrite core transformers located inside the hollow, SF6 filled, porcelain support insulator. The cascade is driven by a silicon controlled rectifier inverter which supplies about 100 W of power at 30 kHz.

  11. Testing of full size high current superconductors in SULTAN III

    Science.gov (United States)

    Blau, B.; Rohleder, I.; Vecsey, G.; Pasotti, G.; Ricci, M. V.; Sacchetti, N.; Bruzzone, P.; Katheder, H.; Mitchell, N.; Bessette, D.

    1994-07-01

    The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 mu V/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb3Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb3Sn conductors in the 8 - 11 T range for temperatures between 4.5 K and 11 K. Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb3Sn conductors after heat treatment is reported, together with some measurements of the joint resistance.

  12. Testing of full size high current superconductors in SULTAN III

    International Nuclear Information System (INIS)

    Blau, B.; Rohleder, I.; Vecsey, G.

    1994-01-01

    The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 μV/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb 3 Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb 3 Sn conductors in the 8--11 T range for temperatures between 4.5 K and 11 K Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb 3 Sn conductors after heat treatment is reported, together with some measurements of the joint resistance

  13. MHD Modeling of Conductors at Ultra-High Current Density

    International Nuclear Information System (INIS)

    Rosenthal, S.E.; Asay, J.R.; Desjarlais, M.P.; Douglas, M.R.; Frese, M.H.; Hall, C.A.; Morse, R.L.; Reisman, D.; Spielman, R.B.; Stygar, W.A.

    1999-01-01

    In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator we have revisited a problem first described in detail by Heinz Knoepfel. MITLs of previous pulsed power accelerators have been in the 1-Tesla regime. Z's disc transmission line (downstream of the current addition) is in a 100-1200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 we have been investigating conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are ( 1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into our MHD computations. Certain features are strongly dependent on the details of the conductivity model. Comparison with measurements on Z will be discussed

  14. High current density, cryogenically cooled sliding electrical joint development

    International Nuclear Information System (INIS)

    Murray, H.

    1986-09-01

    In the past two years, conceptual designs for fusion energy research devices have focussed on compact, high magnetic field configurations. The concept of sliding electrical joints in the large magnets allows a number of technical advantages including enhanced mechanical integrity, remote maintainability, and reduced project cost. The rationale for sliding electrical joints is presented. The conceptual configuration for this generation of experimental devices is highlghted by an ∼ 20 T toroidal field magnet with a flat top conductor current of ∼ 300 kA and a sliding electrical joint with a gross current density of ∼ 0.6 kA/cm 2 . A numerical model was used to map the conductor current distribution as a function of time and position in the conductor. A series of electrical joint arrangements were produced against the system code envelope constraints for a specific version of the Ignition Studies Project (ISP) which is designated as 1025

  15. Study of current instabilities in high resistivity gallium arsenide

    International Nuclear Information System (INIS)

    Barraud, A.

    1968-01-01

    We have shown the existence and made a study of the current oscillations produced in high-resistivity gallium arsenide by a strong electric field. The oscillations are associated with the slow travelling of a region of high electrical field across the whole sample. An experimental study of the properties of these instabilities has made it possible for us to distinguish this phenomenon from the Gunn effect, from acoustic-electric effects and from contact effects. In order to account for this type of instability, a differential trapping mechanism involving repulsive impurities is proposed; this mechanism can reduce the concentration of charge carriers in the conduction band at strong electrical fields and can lead to the production of a high-field domain. By developing this model qualitatively we have been able to account for all the properties of high-resistance gallium arsenide crystals subjected to a strong electrical field: increase of the Hall constant, existence of a voltage threshold for these oscillations, production of domains of high field, low rate of propagation of these domains, and finally the possibility of inverting the direction of the propagation of the domain without destroying the latter. A quantitative development of the model makes it possible to calculate the various characteristic parameters of these instabilities. Comparison with experiment shows that there is a good agreement, the small deviations coming especially from the lack of knowledge concerning transport properties in gallium arsenide subjected to high fields. From a study of this model, it appears that the instability phenomenon can occur over a wide range of repulsive centre concentrations, and also for a large range of resistivities. This is the reason why it appears systematically in gallium arsenide of medium and high resistivity. (authors) [fr

  16. Development and Testing of High Current Hollow Cathodes for High Power Hall Thrusters

    Science.gov (United States)

    Kamhawi, Hani; Van Noord, Jonathan

    2012-01-01

    NASA's Office of the Chief Technologist In-Space Propulsion project is sponsoring the testing and development of high power Hall thrusters for implementation in NASA missions. As part of the project, NASA Glenn Research Center is developing and testing new high current hollow cathode assemblies that can meet and exceed the required discharge current and life-time requirements of high power Hall thrusters. This paper presents test results of three high current hollow cathode configurations. Test results indicated that two novel emitter configurations were able to attain lower peak emitter temperatures compared to state-of-the-art emitter configurations. One hollow cathode configuration attained a cathode orifice plate tip temperature of 1132 degC at a discharge current of 100 A. More specifically, test and analysis results indicated that a novel emitter configuration had minimal temperature gradient along its length. Future work will include cathode wear tests, and internal emitter temperature and plasma properties measurements along with detailed physics based modeling.

  17. 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)

  18. 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.

  19. Development of high electrical resistance persistent current switch for high speed energization system

    International Nuclear Information System (INIS)

    Jizo, Y.; Furuta, Y.; Nakashima, H.

    1986-01-01

    Japanese National Railways is now developing a superconducting magnetically-levitated train system. A persistent current switch is incorporated in the super-conducting magnet used in the magnetically-levitated train. In recent years, the switch has been required to have higher electrical resistance during its off-state in order to realize the high speed energization/de-energization system of the superconducting magnets. The system aims to decrease evaporation volume of liquid helium during the energization/de-energization of the magnet, by means of energizing the superconducting magnet with high current increasing/decreasing rate. Consequently, it would be possible to decrease the dependence of the on-board magnet system upon the ground cooling system. Through the development of a stable superconductive wire material and a coil structure for the persistent current switch using many small model switches which were produced in order to improve their current carrying capacities, the authors have succeeded in manufacturing the high electrical resistance persistent current switch whose electrical resistance was 5 ohms. The switch, of cylindrical shape, has a diameter of about 100mm, a length of about 100mm. These 5 ohm PCSs are now functioning in stable conditions being incorporated in the superconducting magnets of No.2 vehicle of MLU001 at the JNR's Miyazaki test track. Further, the authors are now developing the PCS of still higher resistance values, such as 50 ohms, through studies for stabilization in structural aspects of the winding and obtaining results therefrom

  20. Superconducting fault current limiter using high-resistive YBCO tapes

    Energy Technology Data Exchange (ETDEWEB)

    Yazawa, T. [Power and Industrial System R and D Center, Toshiba Corporation, 2-4 Suehiro, Tsurumi, Yokohama 230-0045 (Japan)], E-mail: takashi.yazawa@toshiba.co.jp; Koyanagi, K.; Takahashi, M.; Ono, M.; Toba, K.; Takigami, H.; Urata, M. [Power and Industrial System R and D Center, Toshiba Corporation, 2-4 Suehiro, Tsurumi, Yokohama 230-0045 (Japan); Iijima, Y.; Saito, T. [Fujikura Ltd., 1-5-1 Kiba, Koto, Tokyo 135-0042 (Japan); Ameniya, N. [Yokohama National University, 79-1 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Shiohara, Y. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto, Tokyo 135-0062 (Japan)

    2008-09-15

    One of the programs in the Ministry of Economy and Trade and Industry (METI) project regarding R and D on YBCO conductor is to evaluate the applicability of the developed conductor toward several applications. This paper focuses on a fault current limiter (FCL) as one of the expected power applications. YBCO tape conductors with ion beam assisted deposition (IBAD) substrate are used in this work. In order to obtain high resistance of the conductor, which is preferable to an FCL, the thickness of the protecting layer made of silver was decreased as possible. Then high-resistive metal stabilizing layer is attached on the silver layer to improve stability. Obtaining the relevant current limiting performance on short sample experiments, model coils were developed to aim the 6.6 kV-class FCL. Short circuit experiments were implemented with a short circuit generator. The coil successfully restricted the short circuit current over 17 kA to about 700 A by the applied voltage of 3.8 kV, which is nominal phase-to-ground voltage. The experimental results show good agreement with computer analyses and show promising toward the application.

  1. What happens in Josephson junctions at high critical current densities

    Science.gov (United States)

    Massarotti, D.; Stornaiuolo, D.; Lucignano, P.; Caruso, R.; Galletti, L.; Montemurro, D.; Jouault, B.; Campagnano, G.; Arani, H. F.; Longobardi, L.; Parlato, L.; Pepe, G. P.; Rotoli, G.; Tagliacozzo, A.; Lombardi, F.; Tafuri, F.

    2017-07-01

    The impressive advances in material science and nanotechnology are more and more promoting the use of exotic barriers and/or superconductors, thus paving the way to new families of Josephson junctions. Semiconducting, ferromagnetic, topological insulator and graphene barriers are leading to unconventional and anomalous aspects of the Josephson coupling, which might be useful to respond to some issues on key problems of solid state physics. However, the complexity of the layout and of the competing physical processes occurring in the junctions is posing novel questions on the interpretation of their phenomenology. We classify some significant behaviors of hybrid and unconventional junctions in terms of their first imprinting, i.e., current-voltage curves, and propose a phenomenological approach to describe some features of junctions characterized by relatively high critical current densities Jc. Accurate arguments on the distribution of switching currents will provide quantitative criteria to understand physical processes occurring in high-Jc junctions. These notions are universal and apply to all kinds of junctions.

  2. Broad-beam, high current, metal ion implantation facility

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the 'seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs

  3. Modeling photo-desorption in high current storage rings

    International Nuclear Information System (INIS)

    Barletta, W.A.

    1991-01-01

    High luminosity flavor factories are characterized by high fluxes of synchrotron radiation that lead to thermal management difficulties. The associated photo-desorption from the vacuum chamber walls presents an additional design challenge, providing a vacuum system suitable for maintaining acceptable beam-gas lifetimes and low background levels of scattered radiation in the detector. Achieving acceptable operating pressures (1-10 nTorr) with practical pumping schemes requires the use of materials with low photodesorption efficiency operating in a radiation environment beyond that of existing storage rings. Extrapolating the existing photo-desorption data base to the design requirements of high luminosity colliders requires a physical model of the differential cleaning in the vacuum chamber. The authors present a simple phenomenological model of photodesorption that includes effects of dose dependence and diffuse photon reflection to compute the leveling of gas loads in beamlines of high current storage rings that typify heavy flavor factories. This model is also used to estimate chamber commissioning times

  4. Isotopic germanium targets for high beam current applications at GAMMASPHERE

    International Nuclear Information System (INIS)

    Greene, J. P.; Lauritsen, T.

    2000-01-01

    The creation of a specific heavy ion residue via heavy ion fusion can usually be achieved through a number of beam and target combinations. Sometimes it is necessary to choose combinations with rare beams and/or difficult targets in order to achieve the physics goals of an experiment. A case in point was a recent experiment to produce 152 Dy at very high spins and low excitation energy with detection of the residue in a recoil mass analyzer. Both to create the nucleus cold and with a small recoil-cone so that the efficiency of the mass analyzer would be high, it was necessary to use the 80 Se on 76 Ge reaction rather than the standard 48 Ca on 108 Pd reaction. Because the recoil velocity of the 152 Dy residues was very high using this symmetric reaction (5% v/c), it was furthermore necessary to use a stack of two thin targets to reduce the Doppler broadening. Germanium targets are fragile and do not withstand high beam currents, therefore the 76 Ge target stacks were mounted on a rotating target wheel. A description of the 76 Ge target stack preparation will be presented and the target performance described

  5. 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...

  6. Compilation of current high energy physics experiments - Sept. 1978

    Energy Technology Data Exchange (ETDEWEB)

    Addis, L.; Odian, A.; Row, G. M.; Ward, C. E. W.; Wanderer, P.; Armenteros, R.; Joos, P.; Groves, T. H.; Oyanagi, Y.; Arnison, G. T. J.; Antipov, Yu; Barinov, N.

    1978-09-01

    This compilation of current high-energy physics experiments is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and the nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), KEK, Rutherford (RHEL), Serpukhov (SERP), and SLAC. Nominally, the compilation includes summaries of all high-energy physics experiments at the above laboratories that were approved (and not subsequently withdrawn) before about June 1978, and had not completed taking of data by 1 January 1975. The experimental summaries are supplemented with three indexes to the compilation, several vocabulary lists giving names or abbreviations used, and a short summary of the beams at each of the laboratories (except Rutherford). The summaries themselves are included on microfiche. (RWR)

  7. Method for making a high current fiber brush collector

    Science.gov (United States)

    Scuro, S. J.

    1986-05-01

    An axial-type homopolar motor having high density, high current fiber brush collectors affording efficient, low contact resistance and low operating temperatures is discussed. The collectors include a ring of concentric row of brushes in equally spaced beveled holes soldered in place using a fixture for heating the ring to just below the solder melting point at a soldering iron for the local application of additional heat at each brush. Prior to soldering, an oxide film is formed on the surfaces of the brushes and ring, and the bevels are burnished to form a wetting surface. Flux applied with the solder at each bevel removes to an effective soldering depth the oxide film on the brushes and the holes.

  8. High-voltage direct-current circuit breakers

    International Nuclear Information System (INIS)

    Yoshioka, Y.; Hirasawa, K.

    1991-01-01

    This paper reports that in 1954 the first high-voltage direct-current (HVDC) transmission system was put into operation between Gotland and the mainland of Sweden. Its system voltage and capacity were 100 kV and 20 MW, respectively. Since then many HVDC transmission systems have been planned, constructed, or commissioned in more than 30 places worldwide, and their total capacity is close to 40 GW. Most systems commissioned to date are two-terminal schemes, and HVDC breakers are not yet used in the high-potential main circuit of those systems, because the system is expected to perform well using only converter/inverter control even at a fault stage of the transmission line. However, even in a two-terminal scheme there are not a few merits in using an HVDC breaker when the system has two parallel transmission lines, that is, when it is a double-circuit system

  9. 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

  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. Modeling of leakage currents in high-k dielectrics

    International Nuclear Information System (INIS)

    Jegert, Gunther Christian

    2012-01-01

    Leakage currents are one of the major bottlenecks impeding the downscaling efforts of the semiconductor industry. Two core devices of integrated circuits, the transistor and, especially, the DRAM storage capacitor, suffer from the increasing loss currents. In this perspective a fundamental understanding of the physical origin of these leakage currents is highly desirable. However, the complexity of the involved transport phenomena so far has prevented the development of microscopic models. Instead, the analysis of transport through the ultra-thin layers of high-permittivity (high-k) dielectrics, which are employed as insulating layers, was carried out at an empirical level using simple compact models. Unfortunately, these offer only limited insight into the physics involved on the microscale. In this context the present work was initialized in order to establish a framework of microscopic physical models that allow a fundamental description of the transport processes relevant in high-k thin films. A simulation tool that makes use of kinetic Monte Carlo techniques was developed for this purpose embedding the above models in an environment that allows qualitative and quantitative analyses of the electronic transport in such films. Existing continuum approaches, which tend to conceal the important physics behind phenomenological fitting parameters, were replaced by three-dimensional transport simulations at the level of single charge carriers. Spatially localized phenomena, such as percolation of charge carriers across pointlike defects, being subject to structural relaxation processes, or electrode roughness effects, could be investigated in this simulation scheme. Stepwise a self-consistent, closed transport model for the TiN/ZrO 2 material system, which is of outmost importance for the semiconductor industry, was developed. Based on this model viable strategies for the optimization of TiN/ZrO 2 /TiN capacitor structures were suggested and problem areas that may

  12. High-current Standing Wave Linac With Gyrocon Power Source

    CERN Document Server

    Karliner, M M; Makarov, I G; Nezhevenko, O A; Ostreiko, G N; Persov, B Z; Serdobintsev, G V

    2004-01-01

    A gyrocon together with high-voltage 1.5 MeV accelerator ELIT-3A represents a power generator at 430 MHz serving for linear electron accelerator pulse driving. The facility description and results of calorimetric measurements of ELIT-3A electron beam power and accelerated beam at the end of accelerator are presented in the paper. 2.2 amps of pulsed current have been obtained at electron energy of 20 MeV. The achieved energy conversion efficiency is about 55%.

  13. Modeling of leakage currents in high-k dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Jegert, Gunther Christian

    2012-03-15

    Leakage currents are one of the major bottlenecks impeding the downscaling efforts of the semiconductor industry. Two core devices of integrated circuits, the transistor and, especially, the DRAM storage capacitor, suffer from the increasing loss currents. In this perspective a fundamental understanding of the physical origin of these leakage currents is highly desirable. However, the complexity of the involved transport phenomena so far has prevented the development of microscopic models. Instead, the analysis of transport through the ultra-thin layers of high-permittivity (high-k) dielectrics, which are employed as insulating layers, was carried out at an empirical level using simple compact models. Unfortunately, these offer only limited insight into the physics involved on the microscale. In this context the present work was initialized in order to establish a framework of microscopic physical models that allow a fundamental description of the transport processes relevant in high-k thin films. A simulation tool that makes use of kinetic Monte Carlo techniques was developed for this purpose embedding the above models in an environment that allows qualitative and quantitative analyses of the electronic transport in such films. Existing continuum approaches, which tend to conceal the important physics behind phenomenological fitting parameters, were replaced by three-dimensional transport simulations at the level of single charge carriers. Spatially localized phenomena, such as percolation of charge carriers across pointlike defects, being subject to structural relaxation processes, or electrode roughness effects, could be investigated in this simulation scheme. Stepwise a self-consistent, closed transport model for the TiN/ZrO{sub 2} material system, which is of outmost importance for the semiconductor industry, was developed. Based on this model viable strategies for the optimization of TiN/ZrO{sub 2}/TiN capacitor structures were suggested and problem areas

  14. Velocity spread of REB generated by high current diode

    International Nuclear Information System (INIS)

    Vrba, P.

    1994-05-01

    A theoretical analysis and numerical simulations of the Relativistic Electron Beam (REB) generation in a high current diode immersed in an external magnetic field were performed. The calculations confirmed the generated beam to be homogeneous and monoenergetic in a broad central region. In the case of a cylindrical diode the mixing of electron trajectories was only observed in a narrow peripheral beam region. The angle between particle trajectories and the external longitudinal magnetic field varies chaotically form 0 to -25 deg. This phenomenon suppresses the excitation of the two-stream instability excited by REB in a plasma column. (author) 2 tabs., 12 figs., 7 refs

  15. High current beam transport with multiple beam arrays

    International Nuclear Information System (INIS)

    Kim, C.H.

    1985-05-01

    Highlights of recent experimental and theoretical research progress on the high current beam transport of single and multiple beams by the Heavy Ion Fusion Accelerator Research (HIFAR) group at the Lawrence Berkeley Laboratory (LBL) are presented. In the single beam transport experiment (SBTE), stability boundaries and the emittance growth of a space charge dominated beam in a long quadrupole transport channel were measured and compared with theory and computer simulations. Also, a multiple beam ion induction linac (MBE-4) is being constructed at LBL which will permit study of multiple beam transport arrays, and acceleration and bunch length compression of individually focused beamlets. Various design considerations of MBE-4 regarding scaling laws, nonlinear effects, misalignments, and transverse and longitudinal space charge effects are summarized. Some aspects of longitudinal beam dynamics including schemes to generate the accelerating voltage waveforms and to amplify beam current are also discussed

  16. Engineering design of a high-temperature superconductor current lead

    International Nuclear Information System (INIS)

    Niemann, R.C.; Cha, Y.S.; Hull, J.R.; Daugherty, M.A.; Buckles, W.E.

    1993-01-01

    As part of the US Department of Energy's Superconductivity Pilot Center Program, Argonne National Laboratory and Superconductivity, Inc., are developing high-temperature superconductor (HTS) current leads suitable for application to superconducting magnetic energy storage systems. The principal objective of the development program is to design, construct, and evaluate the performance of HTS current leads suitable for near-term applications. Supporting objectives are to (1) develop performance criteria; (2) develop a detailed design; (3) analyze performance; (4) gain manufacturing experience in the areas of materials and components procurement, fabrication and assembly, quality assurance, and cost; (5) measure performance of critical components and the overall assembly; (6) identify design uncertainties and develop a program for their study; and (7) develop application-acceptance criteria

  17. 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

  18. Heavy-Ion Injector for the High Current Experiment

    Science.gov (United States)

    Bieniosek, F. M.; Henestroza, E.; Kwan, J. W.; Prost, L.; Seidl, P.

    2001-10-01

    We report on progress in development of the Heavy-Ion Injector at LBNL, which is being prepared for use as an injector for the High Current Experiment (HCX). It is composed of a 10-cm-diameter surface ionization source, an extraction diode, and an electrostatic quadrupole (ESQ) accelerator, with a typical operating current of 0.6 A of potassium ions at 1.8 MeV, and a beam pulse length of 4.5 microsecs. We have improved the Injector equipment and diagnostics, and have characterized the source emission and radial beam profiles at the diode and ESQ regions. We find improved agreement with EGUN predictions, and improved compatibility with the downstream matching section. Plans are to attach the matching section and the initial ESQ transport section of HCX. Results will be presented and compared with EGUN and WARP simulations.

  19. Engineering design of a high-temperature superconductor current lead

    Science.gov (United States)

    Niemann, R. C.; Cha, Y. S.; Hull, J. R.; Daugherty, M. A.; Buckles, W. E.

    As part of the US Department of Energy's Superconductivity Pilot Center Program, Argonne National Laboratory and Superconductivity, Inc., are developing high-temperature superconductor (HTS) current leads suitable for application to superconducting magnetic energy storage systems. The principal objective of the development program is to design, construct, and evaluate the performance of HTS current leads suitable for near-term applications. Supporting objectives are to (1) develop performance criteria; (2) develop a detailed design; (3) analyze performance; (4) gain manufacturing experience in the areas of materials and components procurement, fabrication and assembly, quality assurance, and cost; (5) measure performance of critical components and the overall assembly; (6) identify design uncertainties and develop a program for their study; and (7) develop application-acceptance criteria.

  20. Survey of Digital Feedback Systems in High Current Storage Rings

    International Nuclear Information System (INIS)

    Teytelman, Dmitry

    2003-01-01

    In the last decade demand for brightness in synchrotron light sources and luminosity in circular colliders led to construction of multiple high current storage rings. Many of these new machines require feedback systems to achieve design stored beam currents. In the same time frame the rapid advances in the technology of digital signal processing allowed the implementation of these complex feedback systems. In this paper I concentrate on three applications of feedback to storage rings: orbit control in light sources, coupled-bunch instability control, and low-level RF control. Each of these applications is challenging in areas of processing bandwidth, algorithm complexity, and control of time-varying beam and system dynamics. I will review existing implementations as well as comment on promising future directions

  1. Double disordered YBCO coated conductors of industrial scale: high currents in high magnetic field

    OpenAIRE

    Abraimov D; Ballarino A; Barth C; Bottura L; Dietrich R; Francis A; Jaroszynski J; Majkic G S; McCallister J; Polyanskii A; Rossi L; Rutt A; Santos M; Schlenga K; Selvamanickam V

    2015-01-01

    A significant increase of critical current in high magnetic field up to 31 T was recorded in long tapes manufactured by employing a double disorder route. In a double disordered high temperature superconductor (HTS) a superimposing of intrinsic and extrinsic disorder takes place in a way that (i) the intrinsic disorder is caused by local stoichiometry deviations that lead to defects of crystallinity that serve as pining centers in the YBa2Cu3O x-d matrix and (ii) the extrinsic disorder is in...

  2. Current and field distribution in high temperature superconductors

    International Nuclear Information System (INIS)

    Johnston, M.D.

    1998-01-01

    The manufacture of wires from HTS materials containing copper-oxide planes is difficult because their physical and electrical properties are highly anisotropic. The electrical connectivity depends on the nearest-neighbour grain alignment and although a high degree of grain texture is achieved through processing, the tape microstructure is generally far from uniform, with weak links and porosity also complicating the picture. In order to optimise the processing, the microstructural features common to good tapes must be identified, requiring knowledge of the local properties. The preferential path taken by transport current is determined by the properties of the local microstructure and as such can be used to measure the variation in quality across the tape cross-section. By measuring the self-field profile generated by a current-carrying tape, it is possible to extract the associated current distribution. I have designed and built a Scanning Hall Probe Microscope to measure the normal field distribution above superconductor tapes carrying DC currents, operating at liquid nitrogen temperature and zero applied magnetic field. It has a spatial resolution of 50*50 μm and a field sensitivity of 5 μT, and can scan over a distance of 6 mm. The current extraction is performed by means of a deconvolution procedure based on Legendre functions. This allows a nondestructive, non-invasive method of evaluating the effects of the processing on the tapes - especially when correlated with transport and magnetisation measurement data. Conductors fabricated from Bi 2 Sr 2 Ca 2 Cu 3 O 10 , Bi 2 Sr 2 CaCu 2 O 8 and (Tl 0.78 Bi 0.22 )(Sr 0.8 Ba 0.2 ) 2 Ca 2 Cu 3 O x , have been investigated. I have confirmed the reports that in Bi-2223/Ag mono-core conductors produced by the oxide-powder-in-tube (OPIT) technique, the current flows predominantly at the edges of the tape, where the grains are long and well-aligned. This is in contrast to Bi-2212 ribbons, where the better microstructure

  3. A High Current Proton Linac with 352 MHz SC Cavities

    CERN Document Server

    Pagani, C; Pierini, P

    1996-01-01

    A proposal for a 10-120 mA proton linac employing superconducting beta-graded, CERN type, four cell cavities at 352 MHz is presented. The high energy part (100 MeV-1 GeV) of the machine is split in three beta-graded sections, and transverse focusing is provided via a periodic doublet array. All the parameters, like power in the couplers and accelerating fields in the cavities, are within the state of the art, achieved in operating machines. A first stage of operation at 30 mA beam current is proposed, while the upgrade of the machine to 120 mA operation can be obtained increasing the number of klystrons and couplers per cavity. The additional coupler ports, up to four, will be integrated in the cavity design. Preliminary calculations indicate that beam transport is feasible, given the wide aperture of the 352 MHz structures. A capital cost of less than 100 M$ at 10 mA, reaching up to 280 M$ for the 120 mA extension, has been estimated for the superconducting high energy section (100 MeV-1 GeV). The high effic...

  4. High volume tidal or current flow harnessing system

    Energy Technology Data Exchange (ETDEWEB)

    Gorlov, A.M.

    1984-08-07

    Apparatus permitting the utilization of large volumes of water in the harnessing and extracting of a portion of the power generated by the rise and fall of ocean tides, ocean currents, or flowing rivers includes the provision of a dam, and a specialized single cavity chamber of limited size as compared with the water head enclosed by the dam, and an extremely high volume gating system in which all or nearly all of the water between the high and low levels on either side of the dam is cyclically gated through the single chamber from one side of the dam to the other so as to alternately provide positive air pressure and a partial vacuum within the single chamber. In one embodiment, the specialized chamber has a barrier at the bottom which divides the bottom of the chamber in half, large ports at the bottom of the chamber to permit inflow and outflow of high volumes of water, and ganged structures having a higher total area than that of corresponding ports, in which the structures form sluice gates to selectively seal off and open different sets of ports. In another embodiment, a single chamber is used without a barrier. In this embodiment, vertical sluice gates are used which may be activated automatically by pressures acting on the sluice gates as a result of ingested and expelled water.

  5. The design of a new JET divertor for high triangularity and high current scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Chappuis, P. E-mail: philippe.chappuis@cea.fr; Damiani, C.; Guerin, C.; Hurd, F.; Loarte, A.; Lomas, P.; Lorenz, A.; Pamela, J.; Peacock, A.; Portafaix, C.; Rapp, J.; Riccardo, V.; Rimini, F.; Saibene, G.; Salavy, J.F.; Sauce, Y.; Sartori, R.; Solano, E.; Thomas, E.; Thomas, P.; Tsitrone, E.; Valeta, M.P

    2003-09-01

    A new divertor (MKII-HP) has been designed to be implemented in JET as part of a possible enhancement programme of the JET facility (JET EP). The aim is to handle up to 40 MW of injected power for 10 s with plasma triangularities up to 0.5 while keeping enough flexibility for other scenarios. The divertor is shaped to optimise the wetting fraction without exposing sharp edges or metallic parts and the general design allows for high halo currents.

  6. Proton-irradiation technology for high-frequency high-current silicon welding diode manufacturing

    International Nuclear Information System (INIS)

    Lagov, P B; Drenin, A S; Zinoviev, M A

    2017-01-01

    Different proton irradiation regimes were tested to provide more than 20 kHz-frequency, soft reverse recovery “snap-less” behavior, low forward voltage drop and leakage current for 50 mm diameter 7 kA/400 V welding diode Al/Si/Mo structure. Silicon diode with such parameters is very suitable for high frequency resistance welding machines of new generation for robotic welding. (paper)

  7. Proton-irradiation technology for high-frequency high-current silicon welding diode manufacturing

    Science.gov (United States)

    Lagov, P. B.; Drenin, A. S.; Zinoviev, M. A.

    2017-05-01

    Different proton irradiation regimes were tested to provide more than 20 kHz-frequency, soft reverse recovery “snap-less” behavior, low forward voltage drop and leakage current for 50 mm diameter 7 kA/400 V welding diode Al/Si/Mo structure. Silicon diode with such parameters is very suitable for high frequency resistance welding machines of new generation for robotic welding.

  8. High resolution modelling of the North Icelandic Irminger Current (NIIC

    Directory of Open Access Journals (Sweden)

    K. Logemann

    2006-01-01

    Full Text Available The northward inflow of Atlantic Water through Denmark Strait – the North Icelandic Irminger Current (NIIC – is simulated with a numerical model of the North Atlantic and Arctic Ocean. The model uses the technique of adaptive grid refinement which allows a high spatial resolution (1 km horizontal, 10 m vertical around Iceland. The model is used to assess time and space variability of volume and heat fluxes for the years 1997–2003. Passive tracers are applied to study origin and composition of NIIC water masses. The NIIC originates from two sources: the Irminger Current, flowing as part of the sub-polar gyre in 100–500 m depth along the Reykjanes Ridge and the shallow Icelandic coastal current, flowing north-westward on the south-west Icelandic shelf. The ratio of volume flux between the deep and shallow branch is around 2:1. The NIIC continues as a warm and saline branch northward through Denmark Strait where it entrains large amounts of polar water due to the collision with the southward flowing East Greenland Current. After passing Denmark Strait, the NIIC follows the coast line eastward being an important heat source for north Icelandic waters. At least 60% of the temporal temperature variability of north Icelandic waters is caused by the NIIC. The NIIC volume and heat transport is highly variable and depends strongly on the wind field north-east of Denmark Strait. Daily means can change from 1 Sv eastward to 2 Sv westward within a few days. Highest monthly mean transport rates occur in summer when winds from north are weak, whereas the volume flux is reduced by around 50% in winter. Summer heat flux rates can be even three times higher than in winter. The simulation also shows variability on the interannual scale. In particular weak winds from north during winter 2002/2003 combined with mild weather conditions south of Iceland led to anomalous high NIIC volume (+40% and heat flux (+60% rates. In this period, simulated north Icelandic

  9. Prototype high current, high duty factor negative hydrogen ion source for LAMPF

    International Nuclear Information System (INIS)

    Lawrence, G.P.; Hayward, T.D.; Jackson, J.A.

    1975-01-01

    Present plans for the high current proton storage ring at LAMPF incorporate charge changing (stripping) injection of H - ions in all modes of operation. Achievable stored current levels in this device will be strongly dependent on the maximum H - beam intensity which can be accelerated by the linac, consistent with acceptable beam spill. This requirement has stimulated a program to develop an H - ion source capable of providing a suitably high peak current (up to 25 mA) at high duty factor (up to 12 percent), with a normalized x,x' or y,y' emittance acceptable to the accelerating system. There are presently two main approaches which could lead to H - ion sources providing this kind of performance. These are (a) the charge exchange method, in which an intense proton beam is fractionally converted to H - beam in a suitable charge adding medium, and (b) the direct extraction method, in which H - ions are obtained by a surface emission process associated with a gas discharge plasma. While both approaches may eventually find optimum application in different situations, it is not obvious, at present, which scheme will turn out to be the most satisfactory for LAMPF. A prototype charge exchange H - ion source has been constructed as a first step in the development program and is presently being evaluated. Work on surface emission direct extraction techniques is in the planning stages. (U.S.)

  10. High current transport experiment for heavy ion inertial fusion

    Directory of Open Access Journals (Sweden)

    L. R. Prost

    2005-02-01

    Full Text Available The High Current Experiment at Lawrence Berkeley National Laboratory is part of the U.S. program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ∼0.2  μC/m over long pulse durations (4  μs in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo, and electron and gas cloud effects. We present the results for a coasting 1 MeV K^{+} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius for which the transverse phase space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (≈80% is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  11. Current status of high-T{sub c} wire

    Energy Technology Data Exchange (ETDEWEB)

    Vase, Per [Nordic Superconductor Technologies A/S, Priorparken 685, DK 2605 Broendby (Denmark); Fluekiger, Rene [Departement de Physique de la Matiere Condensee, Universite de Geneve (Switzerland); Leghissa, Martino [Siemens AG, Corporate Technology, Erlangen (Germany); Glowacki, Bartek [Department of Material Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2000-07-01

    This paper is the result of the work of a SCENET (The European Network for Superconductivity) material working group's efforts on giving values for present and future expected performance of high-temperature superconducting (HTS) wires and tapes. The purpose of the work is to give input to the design of HTS applications like power cables, motors, current leads, magnets, transformers and generators. The current status performance values are supposed to be used in the design of today's prototypes and the future values for the design of fully commercial HTS applications of the future. We focus on what is expected to be the relevant parameters for HTS application design. The most successful technique by far for making HTS tapes has been on the (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) material by the powder-in-tube (PIT) technique and this paper therefore focuses on giving the current status and expected future performance for Bi-2223 tapes. (author)

  12. 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)

  13. 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

  14. 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

  15. Two high accuracy digital integrators for Rogowski current transducers

    Science.gov (United States)

    Luo, Pan-dian; Li, Hong-bin; Li, Zhen-hua

    2014-01-01

    The Rogowski current transducers have been widely used in AC current measurement, but their accuracy is mainly subject to the analog integrators, which have typical problems such as poor long-term stability and being susceptible to environmental conditions. The digital integrators can be another choice, but they cannot obtain a stable and accurate output for the reason that the DC component in original signal can be accumulated, which will lead to output DC drift. Unknown initial conditions can also result in integral output DC offset. This paper proposes two improved digital integrators used in Rogowski current transducers instead of traditional analog integrators for high measuring accuracy. A proportional-integral-derivative (PID) feedback controller and an attenuation coefficient have been applied in improving the Al-Alaoui integrator to change its DC response and get an ideal frequency response. For the special design in the field of digital signal processing, the improved digital integrators have better performance than analog integrators. Simulation models are built for the purpose of verification and comparison. The experiments prove that the designed integrators can achieve higher accuracy than analog integrators in steady-state response, transient-state response, and temperature changing condition.

  16. Online diagnoses of high current-density beams

    International Nuclear Information System (INIS)

    Gilpatrick, J.D.

    1994-01-01

    Los Alamos National Laboratory has proposed several CW-proton-beam facilities for production of tritium or transmutation of nuclear waste with beam-current densities greater than 5 mA/mm 2 . The primary beam-diagnostics-instrumentation requirement for these facilities is provision of sufficient beam information to understand and minimize beam-loss. To accomplish this task, the beam-diagnostics instrumentation must measure beam parameters such as the centroids and profiles, total integrated current, and particle loss. Noninterceptive techniques must be used for diagnosis of high-intensity CW beam at low energies due to the large quantity of power deposited in an interceptive diagnostic device by the beam. Transverse and longitudinal centroid measurements have been developed for bunched beams by measuring and processing image currents on the accelerator walls. Transverse beam-profile measurement-techniques have also been developed using the interaction of the particle beam with the background gases near the beam region. This paper will discuss these noninterceptive diagnostic Techniques

  17. The emittance of high current heavy ion beams

    International Nuclear Information System (INIS)

    White, N.R.; Devaney, A.S.

    1989-01-01

    Ion implantation is the main application for high current heavy ion beams. Transfer ratio is defined as the ratio of the total ion current leaving the ion source to the current delivered to the endstation. This ratio is monitored and logged and its importance is explained. It is also affected by other factors, such as the isotopic and molecular composition of the total ion beam. The transfer ratio reveals the fraction of ions which are intercepted by parts of the beamline system. The effects of these ions are discussed in two categories: processing purity and reliability. In discussing the emittance of ribbon beams, the two orthogonal planes are usually considered separately. Longitudinal emittance is determined by slot length and by plasma ion temperature. It has already been revealed that the longitudinal divergence of the beams from BF3 is perhaps double that of the beam from arsenic vapour or argon, at the same total perveance from the ion source. This poses the question: why is the ion temperature higher for BF3 than for As or Ar? The transverse emittance is in practical terms dominated by the divergence. It is the most fruitful area for improvement in most real-world systems. There is an intrinsic divergence arising from initial ion energies within the plasma, and there is emittance growth that can occur as a result of aberration in the beam extraction optics. (N.K.)

  18. High current vacuum arc ion source for heavy ion fusion

    International Nuclear Information System (INIS)

    Qi, N.; Schein, J.; Gensler, S.; Prasad, R.R.; Krishnan, M.; Brown, I.

    1999-01-01

    Heavy Ion fusion (HIF) is one of the approaches for the controlled thermonuclear power production. A source of heavy ions with charge states 1+ to 2+, in ∼0.5 A current beams with ∼20 micros pulse widths and ∼10 Hz repetition rates are required. Thermionic sources have been the workhorse for the HIF program to date, but suffer from sloe turn-on, heating problems for large areas, are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states, in short and long pulse bursts, with low emittance and high beam currents. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications is investigated. An existing ion source at LBNL was modified to produce ∼0.5 A, ∼60 keV Gd (A∼158) ion beams. The experimental effort concentrated on beam noise reduction, pulse-to-pulse reproducibility and achieving low beam emittance at 0.5 A ion current level. Details of the source development will be reported

  19. Development of high current injector for tandem accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Takashi; Iwamoto, Eiji [Nissin - High Voltage Co. Ltd., Kyoto (Japan); Kishimoto, Naoki; Saito, Tetsuya; Mori, Yoshiharu

    1997-02-01

    The development of the electrostatic type tandem accelerators has been carried out so far, but by the recent remarkable progress of negative ion sources, the beam current which was inconceivable so far has become obtainable, and the use as the electrostatic type tandem accelerators is expanding rapidly. The problem which must be solved in the development of a high energy, large current heavy ion injection device is the development of an injector. As to the generation of negative ions, by the development of plasma sputter negative ion sources, the almost satisfactory performance has been obtained in beam current, emittance, life and so on, but as for the transport and control of generated negative ion beam, there is the large problem of spatial charge effect. This time, the verifying test on this problem was carried out, therefore, its contents and results are reported. The equipment which was developed this time was delivered to the Institute for Materials Research. Its specifications are shown. The whole constitution, negative ion source, and beam transport system are described. Beam generation test and spatial charge effect test are reported. The test stand was made, and in the verifying test, the maximum beams of 4 mA in Cu and 3 mA in Ni were able to be generated and transported. The effect of the countermeasures to spatial charge effect was confirmed. (K.I.)

  20. 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

  1. 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

  2. A distributed current stimulator ASIC for high density neural stimulation.

    Science.gov (United States)

    Jeong Hoan Park; Chaebin Kim; Seung-Hee Ahn; Tae Mok Gwon; Joonsoo Jeong; Sang Beom Jun; Sung June Kim

    2016-08-01

    This paper presents a novel distributed neural stimulator scheme. Instead of a single stimulator ASIC in the package, multiple ASICs are embedded at each electrode site for stimulation with a high density electrode array. This distributed architecture enables the simplification of wiring between electrodes and stimulator ASIC that otherwise could become too complex as the number of electrode increases. The individual ASIC chip is designed to have a shared data bus that independently controls multiple stimulating channels. Therefore, the number of metal lines is determined by the distributed ASICs, not by the channel number. The function of current steering is also implemented within each ASIC in order to increase the effective number of channels via pseudo channel stimulation. Therefore, the chip area can be used more efficiently. The designed chip was fabricated with area of 0.3 mm2 using 0.18 μm BCDMOS process, and the bench-top test was also conducted to validate chip performance.

  3. Ultra-high current density thin-film Si diode

    Science.gov (United States)

    Wang, Qi [Littleton, CO

    2008-04-22

    A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

  4. Advanced power flow technologies for high current ICF accelerators

    International Nuclear Information System (INIS)

    VanDevender, J.P.; McDaniel, D.H.

    1978-01-01

    Two new technologies for raising the power density in high current, inertial confinement fusion accelerators have been developed in the past two years. Magnetic flashover inhibition utilizes the self-magnetic fields around the vacuum insulator surface to inhibit surface flashover; average electric fields of 40 Mv/m at magnetic fields of 1.1 T have been achieved. Self-magnetic insulation of long, vacuum transmission lines has been used to transport power at 1.6 x 10 14 W/m 2 over six meters and up to 1.6 x 10 15 W/m 2 over short distances in a radial anode-cathode feed. The recent data relevant to these new technologies and their implications for ICF will be explored

  5. Thermally stimulated current method applied to highly irradiated silicon diodes

    CERN Document Server

    Pintilie, I; Pintilie, I; Moll, Michael; Fretwurst, E; Lindström, G

    2002-01-01

    We propose an improved method for the analysis of Thermally Stimulated Currents (TSC) measured on highly irradiated silicon diodes. The proposed TSC formula for the evaluation of a set of TSC spectra obtained with different reverse biases leads not only to the concentration of electron and hole traps visible in the spectra but also gives an estimation for the concentration of defects which not give rise to a peak in the 30-220 K TSC temperature range (very shallow or very deep levels). The method is applied to a diode irradiated with a neutron fluence of phi sub n =1.82x10 sup 1 sup 3 n/cm sup 2.

  6. High current superconductors for tokamak toroidal field coils

    International Nuclear Information System (INIS)

    Fietz, W.A.

    1976-01-01

    Conductors rated at 10,000 A for 8 T and 4.2 K are being purchased for the first large coil segment tests at ORNL. Requirements for these conductors, in addition to the high current rating, are low pulse losses, cryostatic stability, and acceptable mechanical properties. The conductors are required to have losses less than 0.4 W/m under pulsed fields of 0.5 T with a rise time of 1 sec in an ambient 8-T field. Methods of calculating these losses and techniques for verifying the performance by direct measurement are discussed. Conductors stabilized by two different cooling methods, pool boiling and forced helium flow, have been proposed. Analysis of these conductors is presented and a proposed definition and test of stability is discussed. Mechanical property requirements, tensile and compressive, are defined and test methods are discussed

  7. 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

  8. Structured Cable for High-Current Coils of Tokamaks

    Science.gov (United States)

    Benson, Christopher; McIntyre, Peter; Sattarov, Akhdiyor; Mann, Thomas

    2011-10-01

    The 45 kA superconducting cable for the ITER central solenoid coil has yielded questionable results in two recent tests. In both cases the cable Tc increased after cycling only a fraction of the design life, indicating degradation due to fatigue and fracture among the superconducting strands. The Accelerator Research Lab at Texas A&M University is developing a design for a Nb3Sn structured cable suitable for such tokamak coils. The superconductor is configured in 6 sub-cables, and each subcable is supported within a channel of a central support structure within a high-strength armor sheath. The structured cable addresses two issues that are thought to compromise opposition at high current. The strands are supported without cross-overs (which produce stress concentration); and armor sheath and core structure bypass stress through the coil and among subcables so that the stress within each subcable is only what is produced directly upon it. Details of the design and plans for development will be presented.

  9. Enhanced performance on high current discharges in JET produced by ICRF heating during the current rise

    International Nuclear Information System (INIS)

    Bures, M.; Bhatnagar, V.; Cotrell, G.; Corti, S.; Christiansen, J.P.; Hellsten, T.; Jacquinot, J.; Lallia, P.; Lomas, P.; O'Rourke, J.; Taroni, A.; Tibone, F.; Start, D.F.H.

    1989-01-01

    The performance of high current discharges can be increased by applying central ICRF heating before or shortly after the onset of sawtooth activity in the plasma current rise phase. Sawtooth-free periods have been obtained resulting in the enhanced discharge performance. High T e (0) 9 - 10.5 keV with peaked profiles T e (0)/ e > = 3 - 4 were obtained giving values of n e (0)T e (0) up to 6x10 20 (keV m -3 ). Improvements in T i (0) and neutron production are observed. A 60 % enhancement in D-D reaction rate from 2nd harmonic deuterium (2ω CD ) heating appears to be present. In all current rise (CR) discharges radiation amounts to 25-50 % of total power. (author) 4 refs., 6 figs

  10. Quench propagation in High Temperature Superconducting materials integrated in high current leads

    CERN Document Server

    Milani, D

    2001-01-01

    High temperature superconductors (HTS) have been integrated in the high current leads for the Large Hadron Collider (LHC), under construction at CERN, in order to reduce the heat leak into the liquid helium bath due to the joule effect. The use of the HTS technology in the lower part of the current leads allowed to significantly reduce the heat charge on the cryogenic system. Hybrid current leads have been designed to fulfill the LHC requirements with respect to thermal load; several tests have been performed to study the lead behavior especially during a quench transient. Quench experiments have been performed at CERN on 13 kA prototypes to determine the adequate design and protection. In all the tests it is possible to know the temperature profile of the HTS only with the help of quench simulations that model the thermo-hydraulic processes during quench. The development of a theoretical model for the simulation allows reducing the number of test to perform and to scale the experimental result to other curre...

  11. The free recovery of a short duration, high current discharge

    International Nuclear Information System (INIS)

    Piejak, R.

    1984-01-01

    The hold-off voltage between stainless steel electrodes has been measured as a function of time after an initial discharge. The hold-off voltage is the highest voltage that the gap will withstand without appreciable current flow. A high current (600-1200 amp), short duration (170 nsec) discharge was initiated between Rogowski profile electrodes. After a pre-determined time delay, a second pulse was applied to the discharge gap. The hold-off voltage as a function to time was determined up to the Paschen breakdown voltage. Background gas pressure between 30 and 100 torr and electrode separation of 2mm and 4mm were employed. UV preionization was introduced in some tests to create various discharge modes (glow/arc). The findings indicate significantly higher recovery rates in air than in N 2 , presumably due to attachment processes. In addition, the presence of pre-breakdown UV was found to influence the discharge mode, thus affecting the recovery rate of the gap. Hold-off voltage curves for the previously mentioned gases, background pressures and electrode spacing will be presented along with open shutter photographs of the various discharge modes

  12. Improved Turn-on Characteristics of Fast High Current Thyristors

    CERN Document Server

    Ducimetière, L; Vossenberg, Eugène B

    1999-01-01

    The beam dumping system of CERN's Large Hadron Collider (LHC) is equipped with fast solid state closing switches, designed for a hold-off voltage of 30 kV and a quasi half sine wave current of 20 kA, with 3 ms rise time, a maximum di/dt of 12 kA/ms and 2 ms fall time. The design repetition rate is 20 s. The switch is composed of ten Fast High Current Thyristors (FHCT’s), which are modified symmetric 4.5 kV GTO thyristors of WESTCODE. Recent studies aiming at improving the turn-on delay, switching speed and at decreasing the switch losses, have led to test an asymmetric not fully optimised GTO thyristor of WESTCODE and an optimised device of GEC PLESSEY Semiconductor (GPS), GB. The GPS FHCT, which gave the best results, is a non irradiated device of 64 mm diameter with a hold-off voltage of 4.5 kV like the symmetric FHCT. Tests results of the GPS FHCT show a reduction in turn-on delay of 40 % and in switching losses of almost 50 % with respect to the symmetric FHCT of WESTCODE. The GPS device can sustain an i...

  13. Development of high current low energy H+ ion source

    International Nuclear Information System (INIS)

    Forrester, A.T.; Crow, J.T.; Goebel, D.M.

    1978-01-01

    The ultimate goal of this work is the development of an ion source suitable for double charge exchange of D + ions to D - ions in cesium or other vapor. Since the fraction of the D + which changes to D - may be as high as 0.35 in the energy below one keV, the process appears very favorable. What is desired is a source of several hundred cm 2 area, with a D + current density greater than, say 0.2A/cm 2 . Small angular spread is essential with up to about 0.1 radian being acceptable. A simple approach to this problem appears to be through fine mesh extraction electrodes. In this system a single grid facing the ion source plasma constitutes the entire extraction electrode system. If the potential difference between the grid and the source plasma is large compared to the ion energy at the plasma boundary, then the distance s 0 is just the Child-Langmuir distance corresponding to the ion current density J and the potential difference V 0 between the plasma and the grid

  14. 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

  15. Design of high-energy high-current linac with focusing by superconducting solenoids

    Energy Technology Data Exchange (ETDEWEB)

    Batskikh, G.I.; Belugin, V.M.; Bondarev, B.I. [Moscow Radiotechnical Institute (Russian Federation)] [and others

    1995-10-01

    The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac was presented in a previous report. In this new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channel features allow to decrease beam matched radius and increase a linac radiation purity without aperture growth. {open_quotes}Regotron{close_quotes} is used as high power generator in linac main part. But D&W cavities need not be divided into sections connected by RF-bridges which denuded them of high coupling factor.

  16. High current, high energy proton beams accelerated by a sub-nanosecond laser

    Czech Academy of Sciences Publication Activity Database

    Margarone, Daniele; Krása, Josef; Picciotto, A.; Torrisi, L.; Láska, Leoš; Velyhan, Andriy; Prokůpek, Jan; Ryc, L.; Parys, P.; Ullschmied, Jiří; Rus, Bedřich

    2011-01-01

    Roč. 653, č. 1 (2011), s. 159-163 ISSN 0168-9002 R&D Projects: GA ČR(CZ) GAP205/11/1165; GA AV ČR IAA100100715; GA MŠk(CZ) 7E09092 EU Projects: European Commission(XE) 212105 - ELI-PP Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : laser-acceleration * proton beam * high ion current * time -of-flight * proton energy distribution Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.207, year: 2011

  17. High-latitude Conic Current Sheets in the Solar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Khabarova, Olga V.; Obridko, Vladimir N.; Kharshiladze, Alexander F. [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN), Moscow (Russian Federation); Malova, Helmi V. [Scobeltsyn Nuclear Physics Institute of Lomonosov Moscow State University, Moscow (Russian Federation); Kislov, Roman A.; Zelenyi, Lev M. [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Warsaw (Poland); Tokumaru, Munetoshi; Fujiki, Ken’ichi [Institute for Space-Earth Environmental Research, Nagoya University (Japan); Sokół, Justyna M.; Grzedzielski, Stan [Space Research Centre of the Polish Academy of Sciences (CBK), Warsaw (Poland)

    2017-02-10

    We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2–3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/ nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk–Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.

  18. Enhanced performance of high current discharges in JET produced by ICRF heating during the current rise

    International Nuclear Information System (INIS)

    Bures, M.; Bhatnagar, V.; Christiansen, J.P.

    1989-01-01

    The performance of high current discharges can be improved by applying central ICRF heating before or shortly after the onset of sawtooth activity in the plasma current rise phase. Long sawtooth-free periods have been obtained which result in a transiently-enhanced discharge performance. High T c (0) = 9-10.5 keV with peaked profile T e (0)/ e > = 3-4 were obtained giving values of N e (0)T e (0) up to 6 x 10 20 (keV m -3 ). Improvements in T i (0) and neutron production are observed. A best value of n Dd (0)T i (0)τ E = 1.65 x 10 20 (m -3 keV s) was achieved. Local transport simulation shows that the electron and ion thermal diffusivities do not differ substantially in the two cases of current-rise (CR) and flat-top (FT) heating, the performance of the central plasma region being enhanced, in the case of current-rise, entirely by the elimination of the sawtooth instability. The maximum D-D reaction rate is enhanced by a factor of 2 compared to the flat-top value. An appreciable part of the reaction rate is attributed to 2nd harmonic deuterium (2ω CD ) heating. In all current-rise discharges radiation amounts to 25-50% of total power and Ζ eff remains roughly constant. (author)

  19. A PICTORIAL PRESENTATION OF ESOPHAGEAL HIGH RESOLUTION MANOMETRY CURRENT PARAMETERS.

    Science.gov (United States)

    Lafraia, Fernanda M; Herbella, Fernando A M; Kalluf, Julia R; Patti, Marco G

    2017-01-01

    High resolution manometry is the current technology used to the study of esophageal motility and is replacing conventional manometry in important centers for esophageal motility with parameters used on esophageal motility, following the Chicago Classification. This classification unifies high resolution manometry interpretation and classifies esophageal disorders. This review shows, in a pictorial presentation, the new parameters established by the Chicago Classification, version 3.0, aimed to allow an easy comprehension and interpretation of high resolution manometry. Esophageal manometries performed by the authors were reviewed to select illustrative tracings representing Chicago Classification parameters. The parameters are: Esophagogastric Morphology, that classifies this junction according to its physiology and anatomy; Integrated Relaxation Pressure, that measures the lower esophageal sphincter relaxation; Distal Contractile Integral, that evaluates the contraction vigor of each wave; and, Distal Latency, that measures the peristalsis velocity from the beginning of the swallow to the epiphrenic ampulla. Clinical applications of these new concepts is still under evaluation. Mostrar, de forma pictórica, os novos parâmetros compilados na versão 3.0 da Classificação de Chicago, buscando facilitar a compreensão e interpretação da manometria de alta resolução. Foram revistas as manometrias da casuística dos autores e selecionados os traçados representativos dos parâmetros da Classificação de Chicago. Entre os parâmetros apresentados foram considerados a Morfologia da Transição Gastroesofágica, que classifica o segmento de acordo com sua fisiologia e anatomia; a Integral da Pressão de Relaxamento, que mede o relaxamento do esfíncter esofagiano inferior; a Integral Contrátil Distal, que avalia o vigor contrátil da onda peristáltica; e, a Latência Distal, que mede o tempo da peristalse, desde o início da deglutição até a ampola epifr

  20. Large high current density superconducting solenoids for use in high energy physics experiments

    International Nuclear Information System (INIS)

    Green, M.A.; Eberhard, P.H.; Taylor, J.D.

    1976-05-01

    Very often the study of high energy physics in colliding beam storage-rings requires a large magnetic field volume in order to detect and analyze charged particles which are created from the collision of two particle beams. Large superconducting solenoids which are greater than 1 meter in diameter are required for this kind of physics. In many cases, interesting physics can be done outside the magnet coil, and this often requires that the amount of material in the magnet coil be minimized. As a result, these solenoids should have high current density (up to 10 9 A m -2 ) superconducting windings. The methods commonly used to stabilize large superconducting magnets cannot be employed because of this need to minimize the amount of material in the coils. A description is given of the Lawrence Berkeley Laboratory program for building and testing prototype solenoid magnets which are designed to operate at coil current densities in excess of 10 9 A m -2 with magnetic stored energies which are as high as 1.5 Megajoules per meter of solenoid length. The coils use intrinsically stable multifilament Nb--Ti superconductors. Control of the magnetic field quench is achieved by using a low resistance aluminum bore tube which is inductively coupled to the coil. The inner cryostat is replaced by a tubular cooling system which carries two phase liquid helium. The magnet coil, the cooling tubes, and aluminum bore tube are cast in epoxy to form a single unified magnet and cryogenic system which is about 2 centimeters thick. The results of the magnet coil tests are discussed

  1. 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

  2. Architecture and control of a high current ion implanter system

    International Nuclear Information System (INIS)

    Bayer, E.H.; Paul, L.F.; Kranik, J.R.

    1979-01-01

    The design of an ion implant system for use in production requires that special attention be given to areas of design which normally are not emphasized on research or development type ion implanters. Manually operated, local controls are replaced by remote controls, automatic sequencing, and digital displays. For ease of maintenance and replication the individual components are designed as simply as possible and are contained in modules of separate identities, joined only by the beam line and electrical interconnections. A production environment also imposes requirements for the control of contamination and maintainability of clean room integrity. For that reason the major portion of the hardware is separated from the clean operator area and is housed in a maintenance core area. The controls of a production system should also be such that relatively unskilled technicians are able to operate the system with optimum repeatability and minimum operator intervention. An extensive interlock system is required. Most important, for use in production the ion implant system has to have a relatively high rate of throughput. Since the rate of throughput at a given dose is a function of beam current, pumpdown time and wafer handling capacity, design of components affecting these parameters has been optimized. Details of the system are given. (U.K.)

  3. High-density matter: current status and future challenges

    Directory of Open Access Journals (Sweden)

    Stone J. R.

    2015-01-01

    Full Text Available There are many fascinating processes in the Universe which we observe in more and more in detail thanks to increasingly sophisticated technology. One of the most interesting phenomena is the life cycle of stars, their birth, evolution and death. If the stars are massive enough, they end their lives in the core-collapse supernova explosion, the one of the most violent events in the Universe. As the result, the densest objects in the Universe, neutron stars and/or black holes are created. Naturally, the physical basis of these events should be understood in line with observation. The current status of our knowledge of processes in the life of stars is far from adequate for their true understanding. We show that although many models have been constructed their detailed ability to describe observations is limited or non-existent. Furthermore the general failure of all models means that we cannot tell which are heading in the right direction. A possible way forward in modeling of high-density matter is outlined, exemplified by the quark-meson-coupling model (QMC. This model has a natural explanation for the saturation of nuclear forces and depends on very few adjustable parameters, strongly constrained by the underlying physics. Latest QMC results for compact objects and finite nuclei are presented.

  4. Crystalline-Amorphous Core−Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes

    KAUST Repository

    Cui, Li-Feng

    2009-01-14

    Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon\\'s large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline- amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li ions. We demonstrate here that these core-shell nanowires have high charge storage capacity (̃1000 mAh/g, 3 times of carbon) with ̃90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, ̃20 times of carbon at 1 h rate). © 2009 American Chemical Society.

  5. Valley current characterization of high current density resonant tunnelling diodes for terahertz-wave applications

    Science.gov (United States)

    Jacobs, K. J. P.; Stevens, B. J.; Baba, R.; Wada, O.; Mukai, T.; Hogg, R. A.

    2017-10-01

    We report valley current characterisation of high current density InGaAs/AlAs/InP resonant tunnelling diodes (RTDs) grown by metal-organic vapour phase epitaxy (MOVPE) for THz emission, with a view to investigate the origin of the valley current and optimize device performance. By applying a dual-pass fabrication technique, we are able to measure the RTD I-V characteristic for different perimeter/area ratios, which uniquely allows us to investigate the contribution of leakage current to the valley current and its effect on the PVCR from a single device. Temperature dependent (20 - 300 K) characteristics for a device are critically analysed and the effect of temperature on the maximum extractable power (PMAX) and the negative differential conductance (NDC) of the device is investigated. By performing theoretical modelling, we are able to explore the effect of typical variations in structural composition during the growth process on the tunnelling properties of the device, and hence the device performance.

  6. A review of currently available high performance interactive graphics systems

    International Nuclear Information System (INIS)

    Clark, S.A.; Harvey, J.

    1981-12-01

    A survey of several interactive graphics systems is given, all but one of which being based on calligraphic technology, which are being considered for a new High Energy Physics graphics facility at RAL. A brief outline of the system architectures is given, the detailed features being summarised in an appendix, and their relative merits are discussed. (U.K.)

  7. High Current Density Electrical Breakdown of TiS

    NARCIS (Netherlands)

    Molina-Mendoza, Aday J.; Island, J.O.; Paz, Wendel S.; Clamagirand, Jose Manuel; Ares, Josè Ramon; Flores, Eduardo; Leardini, Fabrice; Sánchez, Carlos; Agraït, Nicolás; Rubio-Bollinger, Gabino; van der Zant, H.S.J.; Ferrer, Isabel J.; Palacios, JJ; Castellanos-Gomez, Andres

    2017-01-01

    The high field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to

  8. Design studies of a high-current radiofrequency quadrupole for ...

    Indian Academy of Sciences (India)

    signed for the low-energy high-intensity proton accelerator (LEHIPA) project at BARC,. India. The beam ... In this generalized method, the focussing factor (B) and vane voltage ..... r0 and also power dissipation vary along the length of the RFQ.

  9. An evaluation of current high-performance networks

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Christian; Bonachea, Dan; Cote, Yannick; Duell, Jason; Hargrove, Paul; Husbands, Parry; Iancu, Costin; Welcome, Michael; Yelick, Katherine

    2003-01-25

    High-end supercomputers are increasingly built out of commodity components, and lack tight integration between the processor and network. This often results in inefficiencies in the communication subsystem, such as high software overheads and/or message latencies. In this paper we use a set of microbenchmarks to quantify the cost of this commoditization, measuring software overhead, latency, and bandwidth on five contemporary supercomputing networks. We compare the performance of the ubiquitous MPI layer to that of lower-level communication layers, and quantify the advantages of the latter for small message performance. We also provide data on the potential for various communication-related optimizations, such as overlapping communication with computation or other communication. Finally, we determine the minimum size needed for a message to be considered 'large' (i.e., bandwidth-bound) on these platforms, and provide historical data on the software overheads of a number of supercomputers over the past decade.

  10. High risk bladder cancer: current management and survival

    Directory of Open Access Journals (Sweden)

    Anna M. Leliveld

    2011-04-01

    Full Text Available PURPOSE: To evaluate the pattern of care in patients with high risk non muscle invasive bladder cancer (NMIBC in the Comprehensive Cancer Center North-Netherlands (CCCN and to assess factors associated with the choice of treatment, recurrence and progression free survival rates. MATERIALS AND METHODS: Retrospective analysis of 412 patients with newly diagnosed high risk NMIBC. Clinical, demographic and follow-up data were obtained from the CCCN Cancer Registry and a detailed medical record review. Uni and multivariate analysis was performed to identify factors related to choice of treatment and 5 year recurrence and progression free survival. RESULTS: 74/412 (18% patients with high risk NMIBC underwent a transurethral resection (TUR as single treatment. Adjuvant treatment after TUR was performed in 90.7% of the patients treated in teaching hospitals versus 71.8 % in non-teaching hospitals (p 80 years OR 0.1 p = 0.001 and treatment in non-teaching hospitals (OR 0.25; p < 0.001 were associated with less adjuvant treatment after TUR. Tumor recurrence occurred in 191/392 (49% and progression in 84 /392 (21.4% patients. The mean 5-years progression free survival was 71.6% (95% CI 65.5-76.8. CONCLUSION: In this pattern of care study in high risk NMIBC, 18% of the patients were treated with TUR as single treatment. Age and treatment in non-teaching hospitals were associated with less adjuvant treatment after TUR. None of the variables sex, age, comorbidity, hospital type, stage and year of treatment was associated with 5 year recurrence or progression rates.

  11. High-quality cardiopulmonary resuscitation: current and future directions.

    Science.gov (United States)

    Abella, Benjamin S

    2016-06-01

    Cardiopulmonary resuscitation (CPR) represents the cornerstone of cardiac arrest resuscitation care. Prompt delivery of high-quality CPR can dramatically improve survival outcomes; however, the definitions of optimal CPR have evolved over several decades. The present review will discuss the metrics of CPR delivery, and the evidence supporting the importance of CPR quality to improve clinical outcomes. The introduction of new technologies to quantify metrics of CPR delivery has yielded important insights into CPR quality. Investigations using CPR recording devices have allowed the assessment of specific CPR performance parameters and their relative importance regarding return of spontaneous circulation and survival to hospital discharge. Additional work has suggested new opportunities to measure physiologic markers during CPR and potentially tailor CPR delivery to patient requirements. Through recent laboratory and clinical investigations, a more evidence-based definition of high-quality CPR continues to emerge. Exciting opportunities now exist to study quantitative metrics of CPR and potentially guide resuscitation care in a goal-directed fashion. Concepts of high-quality CPR have also informed new approaches to training and quality improvement efforts for cardiac arrest care.

  12. Minimum component high frequency current mode rectifier | Sampe ...

    African Journals Online (AJOL)

    In this paper a current mode full wave rectifier circuit is proposed. The current mode rectifier circuit is implemented utilizing a floating current source (FCS) as an active element. The minimum component full wave rectifier utilizes only a single floating current source, two diodes and two grounded resistors. The extremely ...

  13. Proposal for a race-track microtron with high peak current

    NARCIS (Netherlands)

    Ernst, G.J.; Haselhoff, E.H.; Witteman, W.J.; Botman, J.I.M.; van Genderen, W.; Hagedoorn, H.L.; van der Heide, J.A.; Kleeven, W.J.G.M.

    1989-01-01

    In order to obtain high gain in a free electron laser a high-quality electron beam with high peak current is required. It is well-known that a microtron is able to produce a high-quality beam having low emittance and small energy spread (1%). Because a circular microtron has a limited high-current

  14. High-Current Cold Cathode Employing Diamond and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

    2014-10-22

    The essence of this project was for diamond films to be deposited on cold cathodes to improve their emission properties. Films with varying morphology, composition, and size of the crystals were deposited and the emission properties of the cathodes that utilize such films were studied. The prototype cathodes fabricated by the methods developed during Phase I were tested and evaluated in an actual high-power RF device during Phase II. These high-power tests used the novel active RF pulse compression system and the X-band magnicon test facility at US Naval Research Laboratory. In earlier tests, plasma switches were employed, while tests under this project utilized electron-beam switching. The intense electron beams required in the switches were supplied from cold cathodes embodying diamond films with varying morphology, including uncoated molybdenum cathodes in the preliminary tests. Tests with uncoated molybdenum cathodes produced compressed X-band RF pulses with a peak power of 91 MW, and a maximum power gain of 16.5:1. Tests were also carried out with switches employing diamond coated cathodes. The pulse compressor was based on use of switches employing electron beam triggering to effect mode conversion. In experimental tests, the compressor produced 165 MW in a ~ 20 ns pulse at ~18× power gain and ~ 140 MW at ~ 16× power gain in a 16 ns pulse with a ~ 7 ns flat-top. In these tests, molybdenum blade cathodes with thin diamond coatings demonstrated good reproducible emission uniformity with a 100 kV, 100 ns high voltage pulse. The new compressor does not have the limitations of earlier types of active pulse compressors and can operate at significantly higher electric fields without breakdown.

  15. High-dose irradiated food: Current progress, applications, and prospects

    Science.gov (United States)

    Feliciano, Chitho P.

    2018-03-01

    Food irradiation as an established and mature technology has gained more attention in the food industry for ensuring food safety and quality. Primarily used for phytosanitary applications, its use has been expanded for developing various food products for varied purposes (e.g. ready-to-eat & ready-to-cook foods, hospital diets, etc.). This paper summarized and analyzed the recent progress and application of high-dose irradiation and discussed its prospects in the field of food product development, its safety and quality.

  16. TOPICAL REVIEW: Development of high-current high-field conductors in Europe for fusion application

    Science.gov (United States)

    Duchateau, J.-L.; Spadoni, M.; Salpietro, E.; Ciazynski, D.; Ricci, M.; Libeyre, P.; della Corte, A.

    2002-06-01

    In the framework of the preparation for the realization of the international thermonuclear experimental reactor (ITER), the construction and test of relevant models of seven different parts of the reactor was decided. Two of them are related to the superconducting coils: the toroidal field model coil (TFMC) and the central solenoid model coil (CSMC). For these superconducting coils, due to the expected high values of the current (≥60 kA) and voltage (≥5 kV with respect to the ground) the adopted technology was that of cable in conduit conductor (CICC). Until recently, little experience of this technology existed. Therefore, an extensive research and development programme has been carried out, in the last 10 years, by the ITER partners and particularly in Europe, to design, industrialize and test these large conductors and their joints. The EURATOM associations CEA and ENEA played a leading part in this phase. The CICC concept is described and the results of the developments are presented. About 7 km of conductors were manufactured in the industry and for that more than 10 tonnes of Nb3Sn strands were produced in Europe. In this large programme, Europe is particularly in charge of the TFMC, which will be tested this summer at Forschung Zentrum Karlsruhe (Germany). In the framework of this programme, three full size conductors and joint samples were tested at the European Sultan test facility (Centre de Recherches de Physique des Plasmas, Villigen, Switzerland), to validate the technological choices and check that the ITER specifications were met. The results of these tests are presented in detail. Starting from the strand critical properties, the conductors made of about 1000 strands did reach their expected performance. The joints of these large conductors are very special and delicate components. Their behaviour was quite successful and the joint resistance of these samples (of the order of 1 nΩ) was well within the specifications.

  17. Emission mechanism in high current hollow cathode arcs

    International Nuclear Information System (INIS)

    Krishnan, M.

    1976-01-01

    Large (2 cm-diameter) hollow cathodes have been operated in a magnetoplasmadynamic (MPD) arc over wide ranges of current (0.25 to 17 kA) and mass flow (10 -3 to 8 g/sec), with orifice current densities and mass fluxes encompassing those encountered in low current steady-state hollow cathode arcs. Detailed cathode interior measurements of current and potential distributions show that maximum current penetration into the cathode is about one diameter axially upstream from the tip, with peak inner surface current attachment up to one cathode diameter upstream of the tip. The spontaneous attachment of peak current upstream of the cathode tip is suggested as a criterion for characteristic hollow cathode operation. This empirical criterion is verified by experiment

  18. Countercurrent in high-current microsecond diodes with magnetic insulation

    International Nuclear Information System (INIS)

    Bugaev, S.P.; Kim, A.A.; Koshelev, V.I.

    1979-01-01

    In order to increase the efficiency of the generation of tube electron beams in diodes and the efficiency of the electron beam current pulse duration studied is the formation of the electron counter current in microsecond diodes with magnetic insulation in dependence on the various geometry of the cathode joint. The experiments have been carried out at the accelerator with the following parameters: diode voltage from 400 to 600 kV, the front and duration of the pulse 75 ns and 1-2 μs respectively, beam current from 4 to 17 kA, magnetic field of 18 kGs. The current in the drift tube and the total current of the electron gun have been measured. Distributing resistance current of vacuum insulator has been controlled. Conclusions have been made, that, in the case when the diameters of cathode and cathode holder are equal, the electron current is being produced from the reverse side of cathode plasma, which expands across the magnetic field with the rate of (4-5)x10 5 sm/cs. The counter current value has constituted 15% of the total current at the use of reflector with the geometry repeating the shape of the magnetic field force lines, corresponding to the cathode radius. The counter current has not been present at the use of the flat reflector

  19. High-current magnetron discharge with magnetic insulation of anode

    International Nuclear Information System (INIS)

    Bizyukov, A.A.; Sereda, K.N.; Sleptsov, V.V.

    2008-01-01

    In magnetron discharge at currents higher then critical which magnitude is in the range of 15...30 A the transition from glow discharge in transverse magnetic field to arc discharge occurs. In the present time the problem of arc blowout is solved at the expense of pulse and HF power supply applying. In this paper the alternative method of limiting current of magnetron discharge increasing at the expense of increasing of discharge gap resistance by means of additional anode layer transverse magnetic field and arc current interruption by sectioning of current collector of anode surface is carrying out

  20. Tools for the design of high-current linacs

    International Nuclear Information System (INIS)

    Lagniel, J.M.

    1994-01-01

    With the programs usually employed to design linear accelerators, beam dynamics parameters are calculated from data describing the accelerator structure. The desired phase advances (with and without space charge) in the transverse and longitudinal planes are reached after several iterations on the structure parameters. Codes which use the opposite procedure have been written. The phase advances are first chosen thanks to a diagram which gives the tune depressions versus the phase advances without space charge. The structure parameters are then calculated. As shown, it can be applied to radiofrequency quadrupoles (RFQ), DTL and high-energy structures. Up to now, this method has been mainly used to design RFQ linear accelerators. 3 figs., 10 refs

  1. Stretchable electronics for wearable and high-current applications

    Science.gov (United States)

    Hilbich, Daniel; Shannon, Lesley; Gray, Bonnie L.

    2016-04-01

    Advances in the development of novel materials and fabrication processes are resulting in an increased number of flexible and stretchable electronics applications. This evolving technology enables new devices that are not readily fabricated using traditional silicon processes, and has the potential to transform many industries, including personalized healthcare, consumer electronics, and communication. Fabrication of stretchable devices is typically achieved through the use of stretchable polymer-based conductors, or more rigid conductors, such as metals, with patterned geometries that can accommodate stretching. Although the application space for stretchable electronics is extensive, the practicality of these devices can be severely limited by power consumption and cost. Moreover, strict process flows can impede innovation that would otherwise enable new applications. In an effort to overcome these impediments, we present two modified approaches and applications based on a newly developed process for stretchable and flexible electronics fabrication. This includes the development of a metallization pattern stamping process allowing for 1) stretchable interconnects to be directly integrated with stretchable/wearable fabrics, and 2) a process variation enabling aligned multi-layer devices with integrated ferromagnetic nanocomposite polymer components enabling a fully-flexible electromagnetic microactuator for large-magnitude magnetic field generation. The wearable interconnects are measured, showing high conductivity, and can accommodate over 20% strain before experiencing conductive failure. The electromagnetic actuators have been fabricated and initial measurements show well-aligned, highly conductive, isolated metal layers. These two applications demonstrate the versatility of the newly developed process and suggest potential for its furthered use in stretchable electronics and MEMS applications.

  2. High Precision Current Control for the LHC Main Power Converters

    CERN Document Server

    Thiesen, H; Hudson, G; King, Q; Montabonnet, V; Nisbet, D; Page, S

    2010-01-01

    Since restarting at the end of 2009, the LHC has reached a new energy record in March 2010 with the two 3.5 TeV beams. To achieve the performance required for the good functioning of the accelerator, the currents in the main circuits (Main Bends and Main Quadrupoles) must be controlled with a higher precision than ever previously requested for a particle accelerator at CERN: a few parts per million (ppm) of nominal current. This paper describes the different challenges that were overcome to achieve the required precision for the current control of the main circuits. Precision tests performed during the hardware commissioning of the LHC illustrate this paper.

  3. Large area dispenser cathode applied to high current linac

    International Nuclear Information System (INIS)

    Yang Anmin; China Academy of Engineering Physics, Mianyang; Wu Dengxue; Liu Chenjun; Xia Liansheng; Wang Wendou; Zhang Kaizhi

    2005-01-01

    The paper introduced a dispenser cathode (411 M) which was 55 mm in diameter. A 200 kV long pulsed power generator with 2 μs flattop based on Marx-PEN and system with heat and voltage insulation were built. A 52 A space charge limited current was gained, when the temperature was 1165 degree C and the filament current was 18 A on the cathode and the voltage of the pulse was 75 kV at the cathode test stand. Experimental results show that the current values are consistent with the numerical simulation. The experiment reveals that the deflated gas will influence the cathode emission ability. (authors)

  4. Adaptive slope compensation for high bandwidth digital current mode controller

    DEFF Research Database (Denmark)

    Taeed, Fazel; Nymand, Morten

    2015-01-01

    An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations...... in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter...

  5. Critical transport current in granular high temperature superconductors

    International Nuclear Information System (INIS)

    Bogolyubov, N.A.

    1999-01-01

    The temperature and size dependence of the critical current in a zero magnetic field of three bismuth-based ceramic samples with round cross section and one sample with rectangular triangle cross section have been studied by a contactless technique. It is shown that the critical current can be presented as a product of the temperature and size dependent factors. The temperature-dependent multiplier reflects the individual peculiarities of the Josephson net of each sample, while the size factor is a homogeneous function of the cross-section sizes. The index of this function is independent of the cross-section form, the temperature and individual properties of HTSC samples. The radial distribution of critical current density in round samples and dependence of the critical current density on the magnetic conduction in granular HTSC have been found from the analysis of experimental data

  6. Current and future applications of high nitrogen steels

    International Nuclear Information System (INIS)

    Stein, G.; Hucklenbroich, I.; Feichtinger, H.

    1999-01-01

    For any new development there are just two gateways into the market: either it does relevant things never done before - in this case the market is ready to pay a considerable price. Or it does the usual things, but at a very competitive price. And of course, there is any combination of these two prerequisites. With nitrogen steels both concepts apply. On one hand there is the idea of substitution, i.e. replacing the expensive nickel by nitrogen. On the other hand there is a production of steels with an unprecedented combination of usually conflicting properties such as superior strength, toughness and corrosion resistance, as represented by the austenitic Cr-Mn-steel P900, which is used for retaining rings. In a way, success of a material and its usages, which become feasible, can be explained by looking at two things: property potential of a new material and process technology for the production of such material. HNS steels are already indispensable in some fields and we can be sure that they will grow to further importance in the near future. This contribution just makes a little round trip through the field of HNS leads from the technology of large scale generators to the world of fashion, from high tech building and wear resistant aircraft bearings and finally even to the world of medicine. (orig.)

  7. Vacuum interrupters used for the interruption of high dc currents

    International Nuclear Information System (INIS)

    Warren, R.W.

    1977-01-01

    Conventional ac vacuum interrupters are being used to interrupt currents in pulsed energy storage systems. They have been tested with dc currents of up to 37 kA. The limit to the current which can be successfully interrupted has been measured as a function of various parameters. Among these are (1) the size of the interrupter, (2) the magnitude of the counterpulse current, (3) the nature and flux rating of the saturable reactor used, and (4) the kind of ''snubber'' circuit used. Fragmentary data have also been collected on electrode erosion rates and on mechanical failure of the bellows. A description is given of the circuits used in these tests and of the results found for a representative selection of the commercially available domestic interrupters. More recently efforts have been made to increase the values found for the maximum interruptible current. The techniques used have included connecting interrupters in parallel and operating them in an impressed axial magnetic field. The results of this work are discussed

  8. Analysis of Electric Vehicle DC High Current Conversion Technology

    Science.gov (United States)

    Yang, Jing; Bai, Jing-fen; Lin, Fan-tao; Lu, Da

    2017-05-01

    Based on the background of electric vehicles, it is elaborated the necessity about electric energy accurate metering of electric vehicle power batteries, and it is analyzed about the charging and discharging characteristics of power batteries. It is needed a DC large current converter to realize accurate calibration of power batteries electric energy metering. Several kinds of measuring methods are analyzed based on shunts and magnetic induction principle in detail. It is put forward power batteries charge and discharge calibration system principle, and it is simulated and analyzed ripple waves containing rate and harmonic waves containing rate of power batteries AC side and DC side. It is put forward suitable DC large current measurement methods of power batteries by comparing different measurement principles and it is looked forward the DC large current measurement techniques.

  9. Some high-current ion sources for materials modification

    International Nuclear Information System (INIS)

    Taylor, T.

    1989-01-01

    Ion sources for materials modification have evolved through three distinct generations. The first generation was adopted from research accelerators. These cold-cathode plasma-discharge devices generate beam currents of less than 100 μA. The hot-cathode plasma-discharge ion sources, originally developed for isotope separation, comprise the second generation. They produce between 100 μA and 10 mA of beam current. The third generation ion sources give beam currents in excess of 10 mA. This technology, transferred from industrial accelerators, has already made SIMOX (Separation by IMplanted OXygen) into a commercially viable semiconductor process and promises to do the same for ion implantation of metals and insulators. The author focuses on the third generation technology that will play a key role in the future of ion implantation. 10 refs.; 5 figs.; 2 tabs

  10. Experiments and simulation of high current operation at CEBAF

    International Nuclear Information System (INIS)

    Merminga, L.; Crawford, K.; Delayen, J.R.; Doolittle, L.; Hovater, C.; Kazimi, R.; Krafft, G.; Reece, C.; Simrock, S.; Tiefenback, M.; Wang, D.X.

    1996-01-01

    The superconducting rf, cw electron accelerator at CEBAF has achieved the design energy of 4 GeV using 5-pass recirculation through a pair of 400 MeV linacs. Stable beam current of 35 μA has been delivered to the Experimental Hall C. The total beam current that has been recirculated so far is 248 μA. Measurements of the performance of the rf control system have been made in both pulsed and cw mode, and a numerical model has been developed which describes the beam-cavity interaction, includes a realistic representation of low level controls, klystron characteristics and microphonic noise. Experimental data and simulation results on transient beam loading, klystron saturation, a new technique for cavity phasing, and heavy beam loading tests are described; in conclusion, an outlook on full current operation is presented

  11. Characteristics of a high current ion source operated with lithium

    International Nuclear Information System (INIS)

    Bay, H.L.; Dullni, E.; Leismann, P.

    1986-05-01

    A low pressure arc ion source has been tested for operation with lithium. Currents up to 120 mA could be extracted through a multiple aperture extraction system at energies of 30 keV. The ion beam was neutralized up to 70% in a charge exchange cell filled with lithium vapour. The beam divergence ranged from 20 to 25 mrad full angle deduced from the spatial distribution of the collision induced Li I resonance line. Current densities from 2 to 3 mA/m 2 at a distance of 1.9 m from the source were measured either by laser induced fluorescence or with a Faraday cup. (orig.)

  12. High-current beam dynamics and transport, theory and experiment

    International Nuclear Information System (INIS)

    Reiser, M.

    1986-01-01

    Recent progress in the understanding of beam physics and technology factors determining the current and brightness of ion and electron beams in linear accelerators will be reviewed. Topics to be discussed including phase-space density constraints of particle sources, low-energy beam transport include charge neutralization, emittance growth due to mismatch, energy exchange, instabilities, nonlinear effects, and longitudinal bunching

  13. Electron beam formation in high-current diode

    International Nuclear Information System (INIS)

    Korneev, S.A.

    1981-01-01

    The results of experimental investigation of the electron beam formation in diode with cathode on the base of incomplete discharge over the surface of dielectrics with dielectric penetration epsilon 2 . The measurement of current density distribution over transversal cross section reveals an efficient homogeneity [ru

  14. High voltage fault current limiter having immersed phase coils

    Science.gov (United States)

    Darmann, Francis Anthony

    2014-04-22

    A fault current limiter including: a ferromagnetic circuit formed from a ferromagnetic material and including at least a first limb, and a second limb; a saturation mechanism surrounding a limb for magnetically saturating the ferromagnetic material; a phase coil wound around a second limb; a dielectric fluid surrounding the phase coil; a gaseous atmosphere surrounding the saturation mechanism.

  15. RADLAC II high current electron beam propagation experiment

    International Nuclear Information System (INIS)

    Frost, C.A.; Shope, S.L.; Mazarakis, M.G.; Poukey, J.W.; Wagner, J.S.; Turman, B.N.; Crist, C.E.; Welch, D.R.; Struve, K.W.

    1993-01-01

    The resistive hose instability of an electron beam was observed to be convective in recent RADLAC II experiments for higher current shots. The effects of air scattering for these shots were minimal. These experiments and theory suggest low-frequency hose motion which does not appear convective may be due to rapid expansion and subsequent drifting of the beam nose

  16. High current DC negative ion source for cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Etoh, H., E-mail: Hrh-Etoh@shi.co.jp; Aoki, Y.; Mitsubori, H.; Arakawa, Y.; Sakuraba, J.; Kato, T.; Mitsumoto, T.; Hiasa, T.; Yajima, S. [Sumitomo Heavy Industries, Ltd., Tokyo 141-6025 (Japan); Onai, M.; Hatayama, A. [Graduate School of Science and Technology, Keio University, Kanagawa 223-8522 (Japan); Shibata, T. [High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Okumura, Y. [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Aomori 039-3212 (Japan)

    2016-02-15

    A filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In Cs-free operation, continuous H{sup −} beam of 10 mA and D{sup −} beam of 3.3 mA were obtained stably at an arc-discharge power of 3 kW and 2.4 kW, respectively. In Cs-seeded operation, H{sup −} beam current reached 22 mA at a lower arc power of 2.6 kW with less co-extracted electron current. The optimum gas flow rate, which gives the highest H{sup −} current, was 15 sccm in the Cs-free operation, while it decreased to 4 sccm in the Cs-seeded operation. The relationship between H{sup −} production and the design/operating parameters has been also investigated by a numerical study with KEIO-MARC code, which gives a reasonable explanation to the experimental results of the H{sup −} current dependence on the arc power.

  17. 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

  18. Fueling Requirements for Steady State high butane current fraction discharges

    International Nuclear Information System (INIS)

    R.Raman

    2003-01-01

    The CT injector originally used for injecting CTs into 1T toroidal field discharges in the TdeV tokamak was shipped PPPL from the Affiliated Customs Brokers storage facility in Montreal during November 2002. All components were transported safely, without damage, and are currently in storage at PPPL, waiting for further funding in order to begin advanced fueling experiments on NSTX. The components are currently insured through the University of Washington. Several technical presentations were made to investigate the feasibility of the CT injector installation on NSTX. These technical presentations, attached to this document, were: (1) Motivation for Compact Toroida Injection in NSTX; (2) Assessment of the Engineering Feasibility of Installing CTF-II on NSTX; (3) Assessment of the Cost for CT Installation on NSTX--A Peer Review; and (4) CT Fueling for NSTX FY 04-08 steady-state operation needs

  19. Peltier effect in multilayered nanopillars under high density charge current

    International Nuclear Information System (INIS)

    Gravier, L; Fukushima, A; Kubota, H; Yamamoto, A; Yuasa, S

    2006-01-01

    From the basic equations of thermoelectricity, we model the thermal regimes that develop in multilayered nanopillar elements experiencing continuous charge currents. The energy conservation principle was applied to all layer-layer and layer-electrode junctions. The obtained set of equations was solved to derive the temperature of each junction. The contribution of the Peltier effect is included in an effective resistance. This model gives satisfactory fits to experimental data obtained on a series of reference nanopillar elements

  20. Fast Kicker for High Current Beam Manipulation in Large Aperture

    CERN Document Server

    Gambaryan, V

    2017-01-01

    The pulsed deflecting magnet (kicker) project was worked out in Budker Institute of Nuclear Physics. The kicker design parameters are: impulsive force, 1 mT*m; pulse edge, 5 ns; impulse duration, 200 ns. The unconventional approach is that the plates must be replaced by a set of cylinders. The obtained magnet construction enables the field homogeneity to be controlled by changing current magnitudes in cylinders. Furthermore, we demonstrated the method of field optimization. In addition, measurement technique for the harmonic components was considered and the possibility of control harmonic components value was demonstrated.

  1. 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

  2. Design studies on high current and grid control electron gun

    International Nuclear Information System (INIS)

    Wang Jinnan; Lu Kun; Chi Yunlong; Zhou Zusheng

    2011-01-01

    Electron gun, the source of electrons, is a kind of ultrahigh vacuum device and plays an important role in different kind of accelerators. With the irradiation accelerator demands, describes the design studies on beam optics optimization. The simulation result shows that the beam current is above 5 A with cathode voltage of 80 kV and beam emittance, gun electric field and beam waist radius meet the accelerator needs. The electron gun manufactured and installed in the test stand, the conditioning and test will be done in the near future. (authors)

  3. Current Trends in High-Level Synthesis of Asynchronous Circuits

    DEFF Research Database (Denmark)

    Sparsø, Jens

    2009-01-01

    This paper is a survey paper presenting what the author sees as two major and promising trends in the current research in CAD-tools and design-methods for asynchronous circuits. One branch of research builds on top of existing asynchronous CAD-tools that perform syntax directed translation, e...... a conventional synchronous circuit as the starting point, and then adds some form of handshake-based flow-control. One approach keeps the global clock and implements discrete-time asynchronous operation. Another approach substitutes the clocked registers by asynchronous handshake-registers, thus creating truly...

  4. Study of high-energy neutrino neutral-current interactions

    International Nuclear Information System (INIS)

    Aderholz, M.; Aggarwal, M.M.; Akbari, H.; Allport, P.P.; Badyal, S.K.; Ballagh, H.C.; Barth, M.; Baton, J.P.; Bingham, H.H.; Brucker, E.B.; Burnstein, R.A.; Campbell, J.R.; Cence, R.J.; Chatterjee, T.K.; Clayton, E.F.; Corrigan, G.; Coutures, C.; DeProspo, D.; Devanand; De Wolf, E.A.; Faulkner, P.J.W.; Foeth, H.; Fretter, W.B.; Gupta, V.K.; Hanlon, J.; Harigel, G.; Harris, F.A.; Jabiol, M.A.; Jacques, P.; Jain, V.; Jones, G.T.; Jones, M.D.; Kafka, T.; Kalelkar, M.; Kasper, P.; Kohli, J.M.; Koller, E.L.; Krawiec, R.J.; Lauko, M.; Lys, J.E.; Marage, P.; Milburn, R.H.; Miller, D.B.; Mittra, I.S.; Mobayyen, M.M.; Moreels, J.; Morrison, D.R.O.; Myatt, G.; Nailor, P.; Naon, R.; Napier, A.; Neveu, M.; Passmore, D.; Peters, M.W.; Peterson, V.Z.; Plano, R.; Rao, N.K.; Rubin, H.A.; Sacton, J.; Sambyal, S.S.; Schmitz, N.; Schneps, J.; Singh, J.B.; Smart, W.; Stamer, P.; Varvell, K.E.; Verluyten, L.; Wachsmuth, H.; Wainstein, S.; Willocq, S.; Yost, G.P.

    1992-01-01

    From an exposure of the Fermilab 15-foot bubble chamber to the Tevatron quadrupole triplet neutrino beam, we have determined the ratio of neutral-current (NC) to charged-current (CC) interactions to be 0.288±0.032 for events with visible hadron momentum above 10 GeV/c. The mean ν(bar ν) event energy is 150 (110) GeV, which is higher than that for any previous beam. This result agrees with those from previous experiments at lower energies. The NC/CC ratio is derived for a combined sample of ν and bar ν events. A value of 0.274±0.038 is obtained for the dominant ν component assuming bar ν NC/CC=0.39±0.08. For events with visible hadron momentum above 25 GeV/c, where the neutral hadron contamination remaining in the NC sample is assumed to be negligible, the combined NC/CC is 0.323±0.025 and the K 0 production rates are 0.375±0.064 per CC and 0.322±0.073 per NC event. The corresponding Λ rates are 0.161±0.030 per CC and 0.113±0.030 per NC event. The K 0 and Λ distributions of the fractional hadron energy variable z in NC events are consistent with those in CC events

  5. Study of high-energy neutrino neutral-current interactions

    Science.gov (United States)

    Aderholz, M.; Aggarwal, M. M.; Akbari, H.; Allport, P. P.; Badyal, S. K.; Ballagh, H. C.; Barth, M.; Baton, J. P.; Bingham, H. H.; Brucker, E. B.; Burnstein, R. A.; Campbell, J. R.; Cence, R. J.; Chatterjee, T. K.; Clayton, E. F.; Corrigan, G.; Coutures, C.; Deprospo, D.; Devanand; de Wolf, E. A.; Faulkner, P. J.; Foeth, H.; Fretter, W. B.; Gupta, V. K.; Hanlon, J.; Harigel, G.; Harris, F. A.; Jabiol, M. A.; Jacques, P.; Jain, V.; Jones, G. T.; Jones, M. D.; Kafka, T.; Kalelkar, M.; Kasper, P.; Kohli, J. M.; Koller, E. L.; Krawiec, R. J.; Lauko, M.; Lys, J. E.; Marage, P.; Milburn, R. H.; Miller, D. B.; Mittra, I. S.; Mobayyen, M. M.; Moreels, J.; Morrison, D. R.; Myatt, G.; Nailor, P.; Naon, R.; Napier, A.; Neveu, M.; Passmore, D.; Peters, M. W.; Peterson, V. Z.; Plano, R.; Rao, N. K.; Rubin, H. A.; Sacton, J.; Sambyal, S. S.; Schmitz, N.; Schneps, J.; Singh, J. B.; Smart, W.; Stamer, P.; Varvell, K. E.; Verluyten, L.; Wachsmuth, H.; Wainstein, S.; Willocq, S.; Yost, G. P.

    1992-04-01

    From an exposure of the Fermilab 15-foot bubble chamber to the Tevatron quadrupole triplet neutrino beam, we have determined the ratio of neutral-current (NC) to charged-current (CC) interactions to be 0.288+/-0.032 for events with visible hadron momentum above 10 GeV/c. The mean ν(ν¯) event energy is 150 (110) GeV, which is higher than that for any previous beam. This result agrees with those from previous experiments at lower energies. The NC/CC ratio is derived for a combined sample of ν and ν¯ events. A value of 0.274+/-0.038 is obtained for the dominant ν component assuming ν¯ NC/CC=0.39+/-0.08. For events with visible hadron momentum above 25 GeV/c, where the neutral hadron contamination remaining in the NC sample is assumed to be negligible, the combined NC/CC is 0.323+/-0.025 and the K0 production rates are 0.375+/-0.064 per CC and 0.322+/-0.073 per NC event. The corresponding Λ rates are 0.161+/-0.030 per CC and 0.113+/-0.030 per NC event. The K0 and Λ distributions of the fractional hadron energy variable z in NC events are consistent with those in CC events.

  6. Current high-temperature superconducting coils and applications in Japan

    International Nuclear Information System (INIS)

    Matsushita, T.

    2000-01-01

    In Japan, four projects for the application of Bi-based superconducting magnets to practical apparatus are currently underway. These projects involve the development of an insert magnet for a 1 GHz nuclear magnetic resonance spectrometer, a magnet for a silicon single-crystal pulling apparatus, a magnet for a magnetic separation system, and a 1 T pulse magnet for a superconducting magnet energy storage system. For example, the magnet for the silicon single-crystal pulling apparatus is of the class with stored energy of 1 MJ to be operated at around 20 K. This review focuses on the present status of the development of these magnets, followed by a discussion of the problems of the present superconducting tapes that need to be overcome for future applications. (author)

  7. High current densities in superconducting films from magnetization

    International Nuclear Information System (INIS)

    McGuire, T.R.; Gupta, A.; Koren, G.; Gross, R.

    1990-01-01

    Epitaxial thin films of YBa 2 Cu 3 O 7-x made by laser ablation have the CuO planes parallel to the film surface. In the CuO planes critical currents of J C ∼40 x 10 6 amps/cm 2 are found at 5K in zero field. Multi-layered films with Gd replacing Y each .01μm in thickness have J C nearly 140 x 10 6 amps/cm 2 . This higher value is perhaps due to additional point defects. Perpendicular to the CuO planes magnetization studies indicate strong pinning effects attributed to the CuO planes acting as barriers to flux motion

  8. 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)

  9. High Current, High Density Arc Plasma as a New Source for WiPAL

    Science.gov (United States)

    Waleffe, Roger; Endrizzi, Doug; Myers, Rachel; Wallace, John; Clark, Mike; Forest, Cary; WiPAL Team

    2016-10-01

    The Wisconsin Plasma Astrophysics Lab (WiPAL) has installed a new array of nineteen plasma sources (plasma guns) on its 3 m diameter, spherical vacuum vessel. Each gun is a cylindrical, molybdenum, washer-stabilized, arc plasma source. During discharge, the guns are maintained at 1.2 kA across 100 V for 10 ms by the gun power supply establishing a high density plasma. Each plasma source is fired independently allowing for adjustable plasma parameters, with densities varying between 1018 -1019 m-3 and electron temperatures of 5-15 eV. Measurements were characterized using a 16 tip Langmuir probe. The plasma source will be used as a background plasma for the magnetized coaxial plasma gun (MCPG), the Terrestrial Reconnection Experiment (TREX), and as the plasma source for a magnetic mirror experiment. Temperature, density, and confinement results will be presented. This work is supported by the DoE and the NSF.

  10. Application of magnetically insulated transmission lines for high current, high voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Shope, S.L.; Mazarakis, M.G.; Frost, C.A.; Poukey, J.W.; Turman, B.N.

    1993-01-01

    Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently the authors used a MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (r b < 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v perpendicular/c = β perpendicular ≤ 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. The authors' success with the MITL technology led them to investigate the application to higher energy accelerator designs. They have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30-50-ns FWHM output pulse

  11. High energy, low inductance, high current fiberglass energy storage capacitor for the Atlas Machine Marx modules

    CERN Document Server

    Cooper, R A; Ennis, J B; Cochrane, J C; Reass, W A; Parsons, W M

    1999-01-01

    The Los Alamos National Laboratory's Atlas Marx design team envisioned a double ended plastic case 60 kV, 15 nH, 650 kA, energy storage capacitor. A design specification was established and submitted to various vendors. Maxwell Energy Products drew from its development of large fiberglass case, high voltage, low inductance "FASTCAP" capacitors manufactured for Maxwell Technologies' ACE II, ACE III and ACE IV machines. This paper discusses the LANL specification and Maxwell Energy Products' successful design, Model No. 39232, 34.1 mu F, 60 kV, 13*29*27", the only capacitor qualified by LANL for the 23 Mega Joule Atlas application. Maxwell's past experience in this type of capacitor is covered. The performance data is reviewed and the life test data compared to the original calculated design life. Challenges included Maxwell's "keep it simple " design goal which was maintained to minimize the effort required to create and manufacture a nearly 600 pound capacitor. (1 refs).

  12. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    International Nuclear Information System (INIS)

    Haseroth, Helmut; Hora, Heinrich; Regensburg Inst. of Tech.

    1996-01-01

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10 11 C 4+ ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ''hot'' electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author)

  13. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Haseroth, Helmut [European Organization for Nuclear Research, Geneva (Switzerland); Hora, Heinrich [New South Wales Univ., Kensington, NSW (Australia)]|[Regensburg Inst. of Tech. (Germany). Anwenderzentrum

    1996-12-31

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10{sup 11} C{sup 4+} ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ``hot`` electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author).

  14. Application of Magnetically Insulated Transmission Lines for high current, high voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Shope, S.L.; Mazarakis, M.G.; Frost, C.A.; Poukey, J.W.; Turman, B.N.

    1991-01-01

    Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently we used at MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (r ρ < 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v perpendicular/c = β perpendicular ≤ 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. Our success with the MITL technology led us to investigate the application to higher energy accelerator designs. We have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30--50 ns FWHM output pulse. 10 refs

  15. Application of magnetically insulated transmission lines for high current, high voltage electron beam accelerators

    Science.gov (United States)

    Shope, S. L.; Mazarakis, M. G.; Frost, C. A.; Poukey, J. W.; Turman, B. N.

    Self Magnetically Insulated Transmission Lines (MITL) adders were used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently we used at MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (r(sub rho) less than 2 cm), 11 - 15 MeV, 50 - 100-kA beams with a small transverse velocity v(perpendicular)/c = beta(perpendicular) less than or equal to 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. Our success with the MITL technology led us to investigate the application to higher energy accelerator designs. We have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30 - 50 ns FWHM output pulse.

  16. [Acoustic emission diagnostic techniques for high-field high current-density super inducting poles

    International Nuclear Information System (INIS)

    1990-01-01

    Acoustic emission technology was introduced in the late 1970's to monitor superconducting magnets. It has now been firmly established that acoustic signals in superconducting magnets are emitted principally by mechanical events such as conductor strain, conductor motion, frictional motion, and epoxy cracking. Despite earlier suggestions, flux motion, except during flux jumping, does not appear to be an important source of AE signals in superconducting magnets. Of these several potential sources of AE signals in superconducting magnets, mechanical disturbances have been identified to be most important in high-performance, ''adiabatic'' magnets such as the dipoles used in accelerators. These mechanical disturbances are transitory, each generating a packet of AE signals that can be located with sensors. Source identification and location has been achieved with a number of superconducting magnets. In this section, the basic principle for the operation of adiabatic magnets is discussed, followed by presentation of some of the important experimental results relevant to the question of premature quench obtained at MIT

  17. THE NIOBIUM-THORIUM EUTECTIC ALLOY AS A HIGH-FIELD, HIGH-CURRENT SUPERCONDUCTOR

    Energy Technology Data Exchange (ETDEWEB)

    Cline, H. E.; Rose, R. M.; Wulff, J.

    1963-03-15

    Niobium-thorium eutectic alloys having fine acicuiar microstructures were produced by fast cooling frorn a vacuum melt. Although the solidified material was normal, continuity between the superconducting niobium-rich phase, which was essentially pure niobium, was attained by plastic deformation at room temperature. The resulting wire was tested for critical current at 4.2 deg K, in transverse magnetic fields up to 82.5 kilogauss; at the highest field, critical current densities of slightly more than 10/sup 4/ amps per square centimeter were observed. The critical current density was independent of applied field from 20 kilogauss to the highest field used; the level of critical current density depended on diameter in a manner that suggested dependence on cold work. It was concluded that the cold work reduced the thickness of the needles of niobium below the superconducting penetration depth, and brought them sufficiently close together to allow the superconducting correlation to interconnect the niobium, in the manner suggested by Cooper; furthermore, the constant critical current region may possibly extend to considerably higher fields. (auth)

  18. Conductor of high electrical current at high temperature in oxygen and liquid metal environment

    Science.gov (United States)

    Powell, IV, Adam Clayton; Pati, Soobhankar; Derezinski, Stephen Joseph; Lau, Garrett; Pal, Uday B.; Guan, Xiaofei; Gopalan, Srikanth

    2016-01-12

    In one aspect, the present invention is directed to apparatuses for and methods of conducting electrical current in an oxygen and liquid metal environment. In another aspect, the invention relates to methods for production of metals from their oxides comprising providing a cathode in electrical contact with a molten electrolyte, providing a liquid metal anode separated from the cathode and the molten electrolyte by a solid oxygen ion conducting membrane, providing a current collector at the anode, and establishing a potential between the cathode and the anode.

  19. Functional model of a high-current high-voltage superconducting switches

    International Nuclear Information System (INIS)

    Menke, Kh.; Shishov, Yu.A.

    1977-01-01

    Considered are problems of superconducting switches (SS) for energy extraction from magnets at a current of several kiloamperes and a voltage of several kilovolts with a time for transition to the normal state of <0.5 ms. SS is made of a wire of 0.5 mm diameter containing 19 strands of Nb-Ti alloy of 65 μm diameter. The wire matrix was etched out, 19 wires of 4.5 m length were braided together. On each of three groups of wires a heater wire of constantan of 0.12 mm diameter and 6 m length was wound. A second heater intended for slow heating during current feeding into the magnet, is wound over the braid. The wires and heaters are parallel connected and impregnated by an epoxy compound. The following main parameters were obtained in SS testing: critical current of 920 A, resistance in the normal state of 2.5 Ohm, and minimum delay time of 0.2 ms at a nominal current of 0.8 of the critical one

  20. Recent DIII-D high power heating and current drive experiments

    International Nuclear Information System (INIS)

    Simonen, T.C.; Jackson, G.L.; Lazarus, E.A.; Mahdavi, M.A.; Petrie, T.W.; Politzer, P.A.; Taylor, T.S.

    1995-01-01

    This paper describes recent DIII-D high power heating and current drive experiments. Described are experiments with improved wall conditioning, divertor particle pumping, radiative divertor experiments, studies of plasma shape and high poloidal β. ((orig.))

  1. Recent DIII-D high power heating and current drive experiments

    International Nuclear Information System (INIS)

    Simonen, T.C.; Jackson, G.L.; Mahdavi, M.A.; Petrie, T.W.; Politzer, P.A.; Taylor, T.S.; Lazarus, E.A.

    1994-02-01

    This paper describes recent DIII-D high power heating and current drive experiments. Describes are experiments with improved wall conditioning, divertor particle pumping, radiative divertor experiments, studies of plasma shape and high poloidal beta

  2. Recent DIII-D high power heating and current drive experiments

    Energy Technology Data Exchange (ETDEWEB)

    Simonen, T.C. [General Atomics, San Diego, CA (United States); Jackson, G.L. [General Atomics, San Diego, CA (United States); Lazarus, E.A. [Oak Ridge National Lab., TN (United States); Mahdavi, M.A. [General Atomics, San Diego, CA (United States); Petrie, T.W. [General Atomics, San Diego, CA (United States); Politzer, P.A. [General Atomics, San Diego, CA (United States); Taylor, T.S. [General Atomics, San Diego, CA (United States); DIII-D Team

    1995-01-01

    This paper describes recent DIII-D high power heating and current drive experiments. Described are experiments with improved wall conditioning, divertor particle pumping, radiative divertor experiments, studies of plasma shape and high poloidal {beta}. ((orig.)).

  3. Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

    Science.gov (United States)

    Soderstrom, J. R.; Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Yao, J. Y.

    1991-01-01

    InAs/AlSb double-barrier resonant tunneling diodes with peak current densities up to 370,000 A/sq cm and high peak-to-valley current ratios of 3.2 at room temperature have been fabricated. The peak current density is well-explained by a stationary-state transport model with the two-band envelope function approximation. The valley current density predicted by this model is less than the experimental value by a factor that is typical of the discrepancy found in other double-barrier structures. It is concluded that threading dislocations are largely inactive in the resonant tunneling process.

  4. Test data on electrical contacts at high surface velocities and high current densities for homopolar generators

    International Nuclear Information System (INIS)

    Brennan, M.; Tolk, K.M.; Weldon, W.F.; Rylander, H.G.; Woodson, H.H.

    1977-01-01

    Test data is presented for one grade of copper graphite brush material, Morganite CMlS, over a wide range of surface velocities, atmospheres, and current densities that are expected for fast discharge (<100 ms) homopolar generators. The brushes were run on a copper coated 7075-T6 aluminum disk at surface speeds up to 277 m/sec. One electroplated copper and three flame sprayed copper coatings were used during the tests. Significant differences in contact voltage drops and surface mechanical properties of the copper coatings were observed

  5. Development techniques and electron optical studies of high voltage, high current electron guns

    International Nuclear Information System (INIS)

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

    1992-01-01

    The progress of the electron gun design, limiting to axially symmetric geometries is discussed here with a view to utilise such guns for electron accelerators. The mechanical design features leading to the physical configuration of the gun with stringent tolerances are outlined. Vacuum processing is done at pressures of 1.3x10 -5 Pa. The gun employs W-filament emitter or a cathode pellet with bombarder service. A water cooled compact faraday cup is used to measure the electron current. Electron gun geometries have been studied using the computer programme. The preveance of the gun is 0.7x10 -7 A/Vsup(1.5) at 80 kV. Developmental techniques of such pulsed electron guns are described. (author). 7 refs., 5 figs

  6. Adaptation to high current using low external resistances eliminates power overshoot in microbial fuel cells

    KAUST Repository

    Hong, Yiying; Call, Douglas F.; Werner, Craig M.; Logan, Bruce E.

    2011-01-01

    . Acclimation of the high external resistance reactors for a few cycles to low external resistance (5. Ω), and therefore higher current densities, eliminated power overshoot. MFCs initially acclimated to low external resistances exhibited both higher current

  7. Device for plasma confinement and heating by high currents and nonclassical plasma transport properties

    Science.gov (United States)

    Coppi, B.; Montgomery, D.B.

    1973-12-11

    A toroidal plasma containment device having means for inducing high total plasma currents and current densities and at the same time emhanced plasma heating, strong magnetic confinement, high energy density containment, magnetic modulation, microwaveinduced heating, and diagnostic accessibility is described. (Official Gazette)

  8. 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

  9. 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

  10. Ground Return Current Behaviour in High Voltage Alternating Current Insulated Cables

    Directory of Open Access Journals (Sweden)

    Roberto Benato

    2014-12-01

    Full Text Available The knowledge of ground return current in fault occurrence plays a key role in the dimensioning of the earthing grid of substations and of cable sealing end compounds, in the computation of rise of earth potential at substation sites and in electromagnetic interference (EMI on neighbouring parallel metallic conductors (pipes, handrails, etc.. Moreover, the ground return current evaluation is also important in steady-state regime since this stray current can be responsible for EMI and also for alternating current (AC corrosion. In fault situations and under some assumptions, the ground return current value at a substation site can be computed by means of k-factors. The paper shows that these simplified and approximated approaches have a lot of limitations and only multiconductor analysis can show the ground return current behaviour along the cable (not only the two end values both in steady-state regime and in short circuit occurrence (e.g., phase-to-ground and phase-to-phase-to-ground. Multiconductor cell analysis (MCA considers the cable system in its real asymmetry without simplified and approximated hypotheses. The sensitivity of ground return current on circuit parameters (cross-bonding box resistances, substation earthing resistances, soil resistivity is presented in the paper.

  11. Developmental activities of the 18 GHz high temperature superconducting ECR ion source, PKDELIS, for the high current injector at IUAC

    International Nuclear Information System (INIS)

    Rodrigues, G.; Lakshmy, P.S.; Mathur, Y.; Ahuja, R.; Dutt, R.N.; Rao, U.K.; Mandal, A.; Kanjilal, D.; Roy, A.

    2011-01-01

    Various developmental activities of the 18 GHz High Temperature Superconducting ECR Ion Source, PKDELIS have been carried out as a part of the High Current Injector programme. Emittance measurements using a simple technique has given important inputs for the design of downstream accelerators like RFQ, DTL and low beta cavities. The techniques allows for emittance matching by varying the emittance parameters to match with the acceptance of the accelerators. X-ray Beamstrahlung measurements from ECR plasma has shown that it is a diagnostic tool to optimize the production of highly charged ions. The ion optics through the low energy beam transport section has been benchmarked with various codes and given a handle to optimize the transmission. New techniques to improve the extraction efficiency of highly charged ions has been developed. (author)

  12. Highly efficient and reliable high power LEDs with patterned sapphire substrate and strip-shaped distributed current blocking layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengjun [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yuan, Shu; Liu, Yingce [Quantum Wafer Inc., Foshan 528251 (China); Guo, L. Jay [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 (United States); Liu, Sheng, E-mail: victor_liu63@126.com [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Ding, Han [State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TEM is used to characterize threading dislocation existing in GaN epitaxial layer. • Effect of threading dislocation on optical and electrical of LEDs is discussed. • Strip-shaped SiO{sub 2} DCBL is designed to improve current spreading performance of LEDs. - Abstract: We demonstrated that the improvement in optical and electrical performance of high power LEDs was achieved using cone-shaped patterned sapphire substrate (PSS) and strip-shaped SiO{sub 2} distributed current blocking layer (DCBL). We found through transmission electron microscopy (TEM) observation that densities of both the screw dislocation and edge dislocation existing in GaN epitaxial layer grown on PSS were much less than that of GaN epitaxial layer grown on flat sapphire substrate (FSS). Compared to LED grown on FSS, LED grown on PSS showed higher sub-threshold forward-bias voltage and lower reverse leakage current, resulting in an enhancement in device reliability. We also designed a strip-shaped SiO{sub 2} DCBL beneath a strip-shaped p-electrode, which prevents the current from being concentrated on regions immediately adjacent the strip-shaped p-electrode, thereby facilitating uniform current spreading into the active region. By implementing strip-shaped SiO{sub 2} DCBL, light output power of high power PSS-LED chip could be further increased by 13%.

  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. High Charge State Ions Extracted from Metal Plasmas in the Transition Regime from Vacuum Spark to High Current Vacuum Arc

    International Nuclear Information System (INIS)

    Yushkov, Georgy Yu.; Anders, A.

    2008-01-01

    Metal ions were extracted from pulsed discharge plasmas operating in the transition region between vacuum spark (transient high voltage of kV) and vacuum arc (arc voltage ∼ 20 V). At a peak current of about 4 kA, and with a pulse duration of 8 (micro)s, we observed mean ion charges states of about 6 for several cathode materials. In the case of platinum, the highest average charge state was 6.74 with ions of charge states as high as 10 present. For gold we found traces of charge state 11, with the highest average charge state of 7.25. At currents higher than 5 kA, non-metallic contaminations started to dominate the ion beam, preventing further enhancement of the metal charge states

  15. Current sharing effect on the current instability and allowable temperature rise of composite high-TC superconductors

    International Nuclear Information System (INIS)

    Romanovskii, V.R.; Watanabe, K.; Awaji, S.; Nishijima, G.; Takahashi, Ken-ichiro

    2004-01-01

    To understand the basic mechanisms of the thermal runaway phenomenon, the limiting margin of the current instability, which may spontaneously occur in composite high-T C superconductors like multifilament Bi-based wire or tape, is derived under DC magnetic field. The current sharing and allowable temperature rise effects were considered. A static zero-dimensional model was utilized to describe the basic formulae dealing with the peculiarities of the non-isothermal change of superconducting composite voltage-current characteristic. The boundary of allowable stable values of the temperature, electric field and current are derived analytically. It was shown that permissible values of the current and electric field might be higher than those determined by use of the standard critical current criterion. In consequence of this feature, the noticeable allowable temperature rise of the composite superconductor before its transition to the normal state may be seen. The criterion for complete thermal stability condition is written describing the state when temperature of the composite equals critical temperature of a superconductor and the transport current flows stably only in matrix. The performed analysis also proves the existence of value of the volume fraction of a superconductor in composite at which its current-carrying capacity has minimum. These peculiarities are due to the stable current redistribution between superconductor and stabilizing matrix. Therefore, the current sharing not only leads to the matrix/superconductor ratio effect on the stable operating characteristics of the composite high-T C superconductors but also becomes important in the adequate description of quench process in the high-T C superconducting magnets

  16. High Field Side Lower Hybrid Current Drive Simulations for Off- axis Current Drive in DIII-D

    Directory of Open Access Journals (Sweden)

    Wukitch S.J.

    2017-01-01

    Full Text Available Efficient off-axis current drive scalable to reactors is a key enabling technology for developing economical, steady state tokamak. Previous studies have focussed on high field side (HFS launch of lower hybrid current drive (LHCD in double null configurations in reactor grade plasmas and found improved wave penetration and high current drive efficiency with driven current profile peaked near a normalized radius, ρ, of 0.6-0.8, consistent with advanced tokamak scenarios. Further, HFS launch potentially mitigates plasma material interaction and coupling issues. For this work, we sought credible HFS LHCD scenario for DIII-D advanced tokamak discharges through utilizing advanced ray tracing and Fokker Planck simulation tools (GENRAY+CQL3D constrained by experimental considerations. For a model and existing discharge, HFS LHCD scenarios with excellent wave penetration and current drive were identified. The LHCD is peaked off axis, ρ∼0.6-0.8, with FWHM Δρ=0.2 and driven current up to 0.37 MA/MW coupled. For HFS near mid plane launch, wave penetration is excellent and have access to single pass absorption scenarios for variety of plasmas for n||=2.6-3.4. These DIII-D discharge simulations indicate that HFS LHCD has potential to demonstrate efficient off axis current drive and current profile control in DIII-D existing and model discharge.

  17. 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.

  18. The design of a five-cell high-current superconducting cavity

    International Nuclear Information System (INIS)

    Li Yongming; Zhu Feng; Quan Shengwen; Liu Kexin; Nassiri, Ali

    2012-01-01

    Energy recovery linacs are promising for achieving high average current with superior beam quality. The key component for accelerating such high-current beams is the superconducting radio-frequency cavity. The design of a 1.3 GHz five-cell high-current superconducting cavity has been carried out under cooperation between Peking University and the Argonne National Laboratory. The radio-frequency properties, damping of the higher order modes, multipacting and mechanical features of this cavity have been discussed and the final design is presented. (authors)

  19. A High-Sensitivity Current Sensor Utilizing CrNi Wire and Microfiber Coils

    Directory of Open Access Journals (Sweden)

    Xiaodong Xie

    2014-05-01

    Full Text Available We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 μm. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications.

  20. Current Sharing inside a High Power IGBT Module at the Negative Temperature Coefficient Operating Region

    CERN Document Server

    AUTHOR|(CDS)2084596; Papastergiou, Konstantinos; Bongiorno, M; Thiringer, T

    2016-01-01

    This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.

  1. Application of radiofrequency superconductivity to accelerators for high-current ion beams

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Roche, C.T.; Sagalovsky, L.

    1992-01-01

    A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high-current, high-brightness ion beam. During the last few years, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm) surface areas. Theoretical studies of beam halo, cumulative beam breakup and alternating-phase focusing have also yielded important results. This paper su-summarizes the recent progress and identifies current and future work in the areas of superconducting accelerator technology for high-current ion beams

  2. Characterization and control of wafer charging effects during high-current ion implantation

    International Nuclear Information System (INIS)

    Current, M.I.; Lukaszek, W.; Dixon, W.; Vella, M.C.; Messick, C.; Shideler, J.; Reno, S.

    1994-02-01

    EEPROM-based sense and memory devices provide direct measures of the charge flow and potentials occurring on the surface of wafers during ion beam processing. Sensor design and applications for high current ion implantation are discussed

  3. Network coupling via a current-limiting throttle with a high-Tc superconductor core

    International Nuclear Information System (INIS)

    Bochenek, E.; Fischer, R.; Lampen, U.; Voigt, H.

    1989-01-01

    A current-limiting concept is tested by means of a choke with a current-responsive inductivity for linking three-phase current supplies. The choke has a core of a material with a high transition point T c . In the case of nominal current, the core is superconductive and keeps the resulting inductance of the choke low by shield currents. In the case of overload, the core passes into the normal conductive state due to the increased magnetic field of the winding. The resulting inductance of the choke rises and, in doing so, effects current limitation. (orig.) [de

  4. High-energy tritium beams as current drivers in tokamak reactors

    International Nuclear Information System (INIS)

    Mikkelsen, D.R.; Grisham, L.R.

    1983-04-01

    The effect on neutral-beam design and reactor performance of using high-energy (approx. 3-10 MeV) tritium neutral beams to drive steady-state tokamak reactors is considered. The lower current of such beams leads to several advantages over lower-energy neutral beams. The major disadvantage is the reduction of the reactor output caused by the lower current-drive efficiency of the high-energy beams

  5. High-frequency, three-phase current controller implementation in an FPGA

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, M.; Round, S. D.; Kolar, J. W.

    2008-07-01

    Three phase rectifiers with switching frequencies of 500 kHz or more require high speed current controllers. At such high switching frequencies analog controllers as well as high speed digital signal processing (DSP) systems have limited performance. In this paper, two high speed current controller implementations using two different field-programmable gate arrays (FPGA) - one for switching frequencies up to 1 MHz and one for switching frequencies beyond 1 MHz - are presented to overcome this performance limitation. Starting with the digital system design all the blocks of the signal chain, containing analog-to-digital (A/D) interface, digital controller implementation using HW-multipliers and implementation of a novel high speed, high resolution pulse width modulation (PWM) are discussed and compared. Final measurements verify the performance of the controllers. (author)

  6. A high critical current density MOCVD coated conductor with strong vortex pinning centers suitable for very high field use

    International Nuclear Information System (INIS)

    Chen, Z; Kametani, F; Larbalestier, D C; Chen, Y; Xie, Y; Selvamanickam, V

    2009-01-01

    We have made extensive low temperature and high field evaluations of a recent 2.1 μm thick coated conductor (CC) grown by metal-organic chemical vapor deposition (MOCVD) with a view to its use for high field magnet applications, for which its very strong Hastelloy substrate makes it very suitable. This conductor contains dense three-dimensional (Y,Sm) 2 O 3 nanoprecipitates, which are self-aligned in planes tilted ∼7 deg. from the tape plane. Very strong vortex pinning is evidenced by high critical current density J c values of ∼3.1 MA cm -2 at 77 K and ∼43 MA cm -2 at 4.2 K, and by a strongly enhanced irreversibility field H irr , which reaches that of Nb 3 Sn (∼28 T at 1.5 K) at 60 K, even in the inferior direction of H parallel c axis. At 4.2 K, J c values are ∼15% of the depairing current density J d , much the highest of any superconductor suitable for magnet construction.

  7. A high critical current density MOCVD coated conductor with strong vortex pinning centers suitable for very high field use

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z; Kametani, F; Larbalestier, D C [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Chen, Y; Xie, Y; Selvamanickam, V [SuperPower Incorporated, Schenectady, NY 12304 (United States)], E-mail: zhijun@asc.magnet.fsu.edu

    2009-05-15

    We have made extensive low temperature and high field evaluations of a recent 2.1 {mu}m thick coated conductor (CC) grown by metal-organic chemical vapor deposition (MOCVD) with a view to its use for high field magnet applications, for which its very strong Hastelloy substrate makes it very suitable. This conductor contains dense three-dimensional (Y,Sm){sub 2}O{sub 3} nanoprecipitates, which are self-aligned in planes tilted {approx}7 deg. from the tape plane. Very strong vortex pinning is evidenced by high critical current density J{sub c} values of {approx}3.1 MA cm{sup -2} at 77 K and {approx}43 MA cm{sup -2} at 4.2 K, and by a strongly enhanced irreversibility field H{sub irr}, which reaches that of Nb{sub 3}Sn ({approx}28 T at 1.5 K) at 60 K, even in the inferior direction of H parallel c axis. At 4.2 K, J{sub c} values are {approx}15% of the depairing current density J{sub d}, much the highest of any superconductor suitable for magnet construction.

  8. High-performance supercapacitors using a nanoporous current collector made from super-aligned carbon nanotubes

    Science.gov (United States)

    Zhou, Ruifeng; Meng, Chuizhou; Zhu, Feng; Li, Qunqing; Liu, Changhong; Fan, Shoushan; Jiang, Kaili

    2010-08-01

    Nanoporous current collectors for supercapacitors have been fabricated by cross-stacking super-aligned carbon nanotube (SACNT) films as a replacement for heavy conventional metallic current collectors. The CNT-film current collectors have good conductivity, extremely low density (27 µg cm - 2), high specific surface area, excellent flexibility and good electrochemical stability. Nanosized active materials such as NiO, Co3O4 or Mn2O3 nanoparticles can be directly synthesized on the SACNT films by a straightforward one-step, in situ decomposition strategy that is both efficient and environmentally friendly. These composite films can be integrated into a pseudo-capacitor that does not use metallic current collectors, but nevertheless shows very good performance, including high specific capacitance (~500 F g - 1, including the current collector mass), reliable electrochemical stability (<4.5% degradation in 2500 cycles) and a very high rate capability (245 F g - 1 at 155 A g - 1).

  9. Conceptual design of a high current ISOL target area at TRIUMF

    International Nuclear Information System (INIS)

    Beveridge, J.L.; Buchmann, L.; Clark, G.S.; Sprenger, H.; Thorson, I.; Vincent, J.; D'Auria, J.M.; Dombsky, M.

    1993-05-01

    Two similar conceptual designs for the handling of highly activated components at the target area of a high current radioactive beam facility have been investigated. The proposed designs are sufficiently flexible that practical detailed designs could be realized. Personnel exposure to radiation during the handling procedures is expected to be minimal. (author) 3 refs., 4 figs

  10. Measurements of the reverse current of highly irradiated silicon sensors to determine the effective energy and current related damage rate

    Science.gov (United States)

    Wiehe, Moritz; Wonsak, S.; Kuehn, S.; Parzefall, U.; Casse, G.

    2018-01-01

    The reverse current of irradiated silicon sensors leads to self heating of the sensor and degrades the signal to noise ratio of a detector. Precise knowledge of the expected reverse current during detector operation is crucial for planning and running experiments in High Energy Physics. The dependence of the reverse current on sensor temperature and irradiation fluence is parametrized by the effective energy and the current related damage rate, respectively. In this study 18 n-in-p mini silicon strip sensors from companies Hamamatsu Photonics and Micron Semiconductor Ltd. were deployed. Measurements of the reverse current for different bias voltages were performed at temperatures of -32 ° C, -27 ° C and -23 ° C. The sensors were irradiated with reactor neutrons in Ljubljana to fluences ranging from 2 × 1014neq /cm2 to 2 × 1016neq /cm2. The measurements were performed directly after irradiation and after 10 and 30 days of room temperature annealing. The aim of the study presented in this paper is to investigate the reverse current of silicon sensors for high fluences of up to 2 × 1016neq /cm2 and compare the measurements to the parametrization models.

  11. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Y., E-mail: y.hirano@aist.go.jp, E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); College of Science and Technologies, Nihon University, Chiyodaku, Tokyo 101-0897 (Japan); Kiyama, S.; Koguchi, H. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Fujiwara, Y.; Sakakita, H. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Department of Engineering Mechanics and Energy, University of Tsukuba, Ibaraki 305-8577 (Japan)

    2015-11-15

    A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  12. A fast high-voltage current-peak detection system for the ALICE transition radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Verclas, Robert [Physikalisches Institut, Ruprecht-Karls-Universitaet Heidelberg (Germany); Collaboration: ALICE-Collaboration

    2016-07-01

    During LHC operation in run 1, the gaseous detectors of ALICE occasionally experienced simultaneous trips in their high voltage which affected the majority of the high voltage channels. These trips are caused by large anode currents in the detector and are potentially related to LHC machine operations. We developed and installed a fast current-peak detection system for the ALICE Transition Radiation Detector. This system is based on FPGA technology and monitors 144 out 522 high voltage channels minimally invasively at a maximum readout rate of 2 MHz. It is an integral part of the LHC beam monitoring system. We report on the latest status.

  13. A vacuum sealed high emission current and transmission efficiency carbon nanotube triode

    Energy Technology Data Exchange (ETDEWEB)

    Di, Yunsong [School of Electronic Science & Engineering, Southeast University, Nanjing 210096 (China); Jiangsu Key Laboratory of Optoelectronic Technology, Nanjing Normal University, Nanjing 210023 (China); Wang, Qilong; Zhang, Xiaobing, E-mail: bell@seu.edu.cn; Lei, Wei; Du, Xiaofei; Yu, Cairu [School of Electronic Science & Engineering, Southeast University, Nanjing 210096 (China)

    2016-04-15

    A vacuum sealed carbon nanotubes (CNTs) triode with a concave and spoke-shaped Mo grid is presented. Due to the high aperture ratio of the grid, the emission current could be modulated at a relatively high electric field. Totally 75 mA emission current has been obtained from the CNTs cathode with the average applied field by the grid shifting from 8 to 13 V/μm. Whilst with the electron transmission efficiency of the grid over 56%, a remarkable high modulated current electron beam over 42 mA has been collected by the anode. Also contributed by the high aperture ration of the grid, desorbed gas molecules could flow away from the emission area rapidly when the triode has been operated at a relative high emission current, and finally collected by a vacion pump. The working pressure has been maintained at ∼1 × 10{sup −7} Torr, seldom spark phenomena occurred. Nearly perfect I-V curve and corresponding Fowler-Nordheim (FN) plot confirmed the accuracy of the measured data, and the emission current was long term stable and reproducible. Thusly, this kind of triode would be used as a high-power electron source.

  14. Regimes of magnetic insulation in a high-current diodes and transmission lines of conical configuration

    International Nuclear Information System (INIS)

    Vasilenko, O.I.; Voronin, V.S.; Lebedev, A.N.

    1977-01-01

    A self-consistent kinematic model of a steady-state electron flow between two electrodes of a high-current diode has been considered with a tapered configuration. All the electrons have presumably been released from the cathode with a zero velocity and some portion of the total current flows along the cathode surface as the conduction current. A set of volt-ampere characteristics has been obtained for the tapered diode with a flat anode. At a preset cathode current the thickness and current of the electron layer increase as the voltage goes up. The considered kinematic model substantiates and specifies a model of the Brillouin parapotential flow

  15. Electron current generated in a toroidal plasma on injection of high-energy neutrals

    International Nuclear Information System (INIS)

    Kolesnichenko, Ya.I.; Reznik, S.N.

    1981-01-01

    Problem of generation of electron current in toroidal plasma with a high-energy ion beam produced during neutral injection has been considered. The analysis was performed on the assumption that plasma is in the regime of rare collisions (banana regime) and ion beam velocity is considerably lower than thermal velocity of plasma ions. Formulae establishing the relation between beam current and electron current have been derived. It follows from them that toroidal affect considerably plasma current generated with the beam and under certain conditions result in changing this current direction in an area remoted from magne-- tic axis [ru

  16. Transport and acceleration of the high-current ion beam in magneto-isolated gap

    International Nuclear Information System (INIS)

    Karas', V.I.; Kornilov, E.A.; Manuilenko, O.V.; Fedorovskaya, O.V.; Tarakanov, V.P.

    2015-01-01

    The possibility of transportation and acceleration of the high-current ion beam in the magneto-isolated gap has been demonstrated. Found the parameters of the system and beams (the magnetic field produced by the coils with opposing currents, the size of the system, and the parameters of the beams), under which the uniform acceleration of the high-current ion beam all along the gap length is realized. It is shown that the quality of the ion beam, during transport and acceleration, at the exit of the gap is acceptable for many technological applications.

  17. Properties of high-spin boson interaction currents and elimination of power divergences

    International Nuclear Information System (INIS)

    Kulish, Yu.V.; Rybachuk, E.V.

    2001-01-01

    The problem of the elimination of the power divergences for the interactions of the high-spin bosons (J ≥ 1) is investigated. It is proved that in the consistent theory the high-spin boson interaction currents and the field tensors must obey similar requirements. Therefore the momentum dependencies of the propagators for all the bosons are the same. The partial differential equations derived for some components include the derivatives of order 2J for the currents. Therefore the current components for the spin-J boson must decrease with the momentum Kombi scalar p v Kombi scalar → ∞ at least as Kombi scalar p v Kombi scalar -2J

  18. Method for controlling low-energy high current density electron beams

    International Nuclear Information System (INIS)

    Lee, J.N.; Oswald, R.B. Jr.

    1977-01-01

    A method and an apparatus for controlling the angle of incidence of low-energy, high current density electron beams are disclosed. The apparatus includes a current generating diode arrangement with a mesh anode for producing a drifting electron beam. An auxiliary grounded screen electrode is placed between the anode and a target for controlling the average angle of incidence of electrons in the drifting electron beam. According to the method of the present invention, movement of the auxiliary screen electrode relative to the target and the anode permits reliable and reproducible adjustment of the average angle of incidence of the electrons in low energy, high current density relativistic electron beams

  19. Ion production and bipolar fluxes in a high-current plasma-filled diode

    International Nuclear Information System (INIS)

    Ivanenkov, G.V.

    1982-01-01

    The model and the evolution of behaviour of binary layers (BL) in expanding plasma of high current plasma-filled diode are described. The model estimates ion current and the laws of plasma expansion at the stage of BL intensive growth. The density range (10 12 -10 15 cm -3 ) is determined in which diode impedance growth takes place in connection with BL appearance. The density of ion current at the outlet of diode is 10 A/cm 2

  20. Realisation and instrumentation of high current power station for superconducting cables testing

    International Nuclear Information System (INIS)

    Regnaud, S.

    2000-05-01

    This report deals with the designing of a high current station able to test electric properties of superconductors. This test station will be used for testing the superconducting wires of large hadron collider detectors in CERN. The high current test station will have to generate high intensity continuous current in a magnetic field of 0 to 5 tesla and in temperature conditions of 4.2 K. The length of wire samples submitted to the uniform magnetic field is 300 mm and the installation is fitted with equipment able to measure the magnetic field perpendicular to either faces of the wire. The peculiarity of this station is to use a superconducting transformer in order to generate the high current. The first part of this work recalls important notions concerning superconductivity. The second part presents the high current station by describing the superconducting transformer and the sample-holder. We have studied the designing of a transformer able to yield a secondary current whose intensity reaches 100 kA, such intensity generates powerful electromagnetic forces (566 kN/m) in case of defect, so the sample-holder has to be carefully design to bear them. The third part presents the cryogenic component of the station, the instrumentation of the sample-holder and the method used to measure secondary currents. In the last part we present the performance of a prototype transformer, this prototype is able to deliver a 22 kA secondary current for a 160 A primary current, the uncertainty on the measured value of the secondary current is about 3%

  1. Limiting stable states of high-Tc superconductors in the alternating current modes

    International Nuclear Information System (INIS)

    Romanovskii, V.R.; Watanabe, K.; Awaji, S.

    2014-01-01

    The limiting current-carrying capacity of high-T c superconductor and superconducting tape has been studied in the alternating current states. The features that are responsible for their stable formation have been investigated under the conduction-cooled conditions when the operating peak values of the electric field and the current may essentially exceed the corresponding critical values of superconductor. Besides, it has been proved that these peak values are higher than the values of the electric field and the current, which lead to the thermal runaway phenomenon when the current instability onset occurs in the operating modes with direct current. As a result, the stable extremely high heat generation exists in these operating states, which can be called as overloaded states. The limiting stable peak values of charged currents and stability conditions have been determined taking into account the flux creep states of superconductors. The analysis performed has revealed that there exist characteristic times defining the corresponding time windows in the stable development of overloaded states of the alternating current. In order to explain their existence, the basic thermo-electrodynamics mechanisms have been formulated, which have allowed to explain the high stable values of the temperature and the induced electric field before the onset of alternating current instability. In general, it has been shown that the high-T c superconductors may stably operate in the overloaded alternating current states even under the not intensive cooling conditions at a very high level of heat generation, which is not considered in the existing theory of losses. (authors)

  2. Guiding effect of bent macroscopic quartz tube for high current electron beam

    International Nuclear Information System (INIS)

    Zhang Mingwu; Chen Jing; Wu Yehong; Yang Bian; Wang Wei; Xue Yingli; Yu Deyang; Cai Xiaohong

    2012-01-01

    By using an incident electron beam with the high current and high energy, the guiding effect of the bent macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self-organized charging effect on the surface of inner wall of quartz tube. (authors)

  3. Stationary, high bootstrap fraction plasmas in DIII-D without inductive current control

    International Nuclear Information System (INIS)

    Politzer, P.A.; Hyatt, A.W.; Luce, T.C.; Prater, R.; Turnbull, A.D.; Ferron, J.R.; Greenfield, C.M.; La Haye, R.J.; Petty, C.C.; Perkins, F.W.; Brennan, D.P.; Lazarus, E.A.; Jayakumar, J.; Wade, M.R.

    2005-01-01

    We have initiated an experimental program to address some of the questions associated with operation of a tokamak with high bootstrap current fraction under high performance conditions, without assistance from a transformer. In these discharges stationary (or slowly improving) conditions are maintained for > 3.7 s at β N ∼ β p ≤ 3.3. The achievable current and pressure are limited by a relaxation oscillation, involving growth and collapse of an ITB at ρ ≥ 0.6. The pressure gradually increases and the current profile broadens throughout the discharge. Eventually the plasma reaches a more stable, high confinement (H89P ∼ 3) state. Characteristically these plasmas have 65%-85% bootstrap current, 15%-30% NBCD, and 0%-10% ECCD. (author)

  4. Fault diagnosis and performance evaluation for high current LIA based on radial basis function neural network

    International Nuclear Information System (INIS)

    Yang Xinglin; Wang Huacen; Chen Nan; Dai Wenhua; Li Jin

    2006-01-01

    High current linear induction accelerator (LIA) is a complicated experimental physics device. It is difficult to evaluate and predict its performance. this paper presents a method which combines wavelet packet transform and radial basis function (RBF) neural network to build fault diagnosis and performance evaluation in order to improve reliability of high current LIA. The signal characteristics vectors which are extracted based on energy parameters of wavelet packet transform can well present the temporal and steady features of pulsed power signal, and reduce data dimensions effectively. The fault diagnosis system for accelerating cell and the trend classification system for the beam current based on RBF networks can perform fault diagnosis and evaluation, and provide predictive information for precise maintenance of high current LIA. (authors)

  5. MAGY: An innovative high voltage-low current power supply for gyrotron

    International Nuclear Information System (INIS)

    Siravo, Ugo; Alex, Juergen; Bader, Michael; Carpita, Mauro; Fasel, Damien; Gavin, Serge; Perez, Albert

    2011-01-01

    From the electrical point of view, the body and the anode of high power gyrotrons behave as capacitive loads. A highly dynamic power supply is, therefore, hard to achieve. The MAGY concept (Modulator for the Anode of a triode type GYrotron) embodies an innovative solution to manage the capacitive current ensuring a very low ripple on the output voltage. It consists of a series of independent, bi-directional and regulated DC sources. Compared to existing topologies, this solution requires a smaller number of power modules. It avoids internal high frequency modulation and simultaneously offers high resolution of the output voltage and a wide range of operating scenarios.

  6. Development of a high average current polarized electron source with long cathode operational lifetime

    Energy Technology Data Exchange (ETDEWEB)

    C. K. Sinclair; P. A. Adderley; B. M. Dunham; J. C. Hansknecht; P. Hartmann; M. Poelker; J. S. Price; P. M. Rutt; W. J. Schneider; M. Steigerwald

    2007-02-01

    Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory) require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2?105???C/cm2 and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  7. Operating modes of high-Tc composite superconductors and thermal runaway conditions under current charging

    International Nuclear Information System (INIS)

    Romanovskii, V R; Watanabe, K

    2006-01-01

    The operating thermal and electric modes of a high-T c superconducting composite in partially and fully penetrated states induced by the charging current are investigated. They were studied under conditions in which the current charging rate, the volume fraction of the superconductor in a composite or the temperature of the cooling bath were changed. The transient behaviour of the voltage-current dependence, which is characteristic during stable and unstable increases in electric field inside the composite under a continuous current charging, is discussed. Simulations were done using zero- and one-dimensional steady and unsteady thermoelectric models with a power equation describing the virgin voltage-current characteristic of a superconductor. It is found that some thermoelectric trends underlie the shape of the voltage-current characteristic of the high-T c superconducting composite. These have to be considered during experiments in which the critical or quench currents are defined. First, in the initial stage of the fully penetrated regime (in the low voltage range), the electric field distribution does not have a uniform character. These states depend on the volume fraction of the superconductor and the current charging rate: the higher these quantities, the higher the heterogeneity of the electric field. Second, during the stable over-critical regime (in the high voltage range) occurring in complete penetration modes, the evolution of the electric field may depend on the relevant temperature increase of a composite according to the corresponding increase in its temperature-dependent heat capacity. Consequently, the shape of the voltage-current characteristic of a composite high-T c superconductor during continuous current charging, both before and after thermal runaway, has only a positive slope. Moreover, it is proved that the growth of the fully penetrated part of the voltage-current characteristic becomes less intensive when the current charging rate or the

  8. Adherence to guidelines for cardiovascular screening in current high school preparticipation evaluation forms.

    Science.gov (United States)

    Rausch, Christopher M; Phillips, George C

    2009-10-01

    We compared the content of the cardiac screening questions on US state high school athletic association preparticipation evaluation forms with current consensus recommendations. We reviewed the high school athletic association's approved, recommended, or required sports preparticipation form from each of the 50 US states and the District of Columbia, and compared the content of the personal and family history components with current recommendations for cardiac screening questions. We found that 85% of the preparticipation forms in current use contain all elements of the formerly recommended guidelines, but only 17% contain all elements of the new consensus guidelines. We conclude that although there appears to be some improvement in the content of the preparticipation forms in current use compared with previous studies, the vast majority of these forms are incomplete compared with current consensus guidelines.

  9. The development of shock wave overpressure driven by channel expansion of high current impulse discharge arc

    Science.gov (United States)

    Xiong, Jia-ming; Li, Lee; Dai, Hong-yu; Wu, Hai-bo; Peng, Ming-yang; Lin, Fu-chang

    2018-03-01

    During the formation of a high current impulse discharge arc, objects near the discharge arc will be strongly impacted. In this paper, a high power, high current gas switch is used as the site of the impulse discharge arc. The explosion wave theory and the arc channel energy balance equation are introduced to analyze the development of the shock wave overpressure driven by the high current impulse discharge arc, and the demarcation point of the arc channel is given, from which the energy of the arc channel is no longer converted into shock waves. Through the analysis and calculation, it is found that the magnitude of the shock wave overpressure caused by impulse discharge arc expansion is closely related to the arc current rising rate. The arc shock wave overpressure will undergo a slow decay process and then decay rapidly. The study of this paper will perform the function of deepening the understanding of the physical nature of the impulse arc discharge, which can be used to explain the damage effect of the high current impulse discharge arc.

  10. Development of the High Current Ion Source for Neutral Beam Injection

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hun Ju; Kim, S. H.; Jang, D. H. [Jae Ju University, Jaeju (Korea, Republic of)

    1997-08-01

    The scope of the 1st year research is to design an 140keV deuterium ion source which has a beam current of 30-40A. According to the collected data, the model of an ion source for NBI of KSTAR was established. The negative ion source, which has good neutralization effecting in high energy, was selected. To generate a plasma, the thoriated tungsten filament was adopted. To increase the efficiency of plasma, the multi cusp type magnetic field was attached. The magnetic field was calculated by POISSON code. The extraction structure was designed with EGUN code, to extract the high quality ion beam. The design of a high current ion source for NBI was carried out. To develop the high current ion source with the high operational stability and the long lifetime, the parameters including an arc current, gas pressure and extraction voltage should be optimized. If designed ion source would be fabricated, its parameters could be optimized experimentally. Through the optimization of the ion source parameter, the core technology for NBI is established and the experiment of current drive in the fusion device can be performed. This technology also can be applied to the synthesis of new material and semiconductor industry. 18 refs., 11 tabs., 19 figs. (author)

  11. Study of surface leakage current of AlGaN/GaN high electron mobility transistors

    International Nuclear Information System (INIS)

    Chen, YongHe; Zhang, Kai; Cao, MengYi; Zhao, ShengLei; Zhang, JinCheng; Hao, Yue; Ma, XiaoHua

    2014-01-01

    Temperature-dependent surface current measurements were performed to analyze the mechanism of surface conductance of AlGaN/GaN channel high-electron-mobility transistors by utilizing process-optimized double gate structures. Different temperatures and electric field dependence have been found in surface current measurements. At low electric field, the mechanism of surface conductance is considered to be two-dimensional variable range hopping. At elevated electric field, the Frenkel–Poole trap assisted emission governs the main surface electrons transportation. The extracted energy barrier height of electrons emitting from trapped state near Fermi energy level into a threading dislocations-related continuum state is 0.38 eV. SiN passivation reduces the surface leakage current by two order of magnitude and nearly 4 orders of magnitude at low and high electric fields, respectively. SiN also suppresses the Frenkel–Poole conductance at high temperature by improving the surface states of AlGaN/GaN. A surface treatment process has been introduced to further suppress the surface leakage current at high temperature and high field, which results in a decrease in surface current of almost 3 orders of magnitude at 476 K

  12. Application of parallel connected power-MOSFET elements to high current d.c. power supply

    International Nuclear Information System (INIS)

    Matsukawa, Tatsuya; Shioyama, Masanori; Shimada, Katsuhiro; Takaku, Taku; Neumeyer, Charles; Tsuji-Iio, Shunji; Shimada, Ryuichi

    2001-01-01

    The low aspect ratio spherical torus (ST), which has single turn toroidal field coil, requires the extremely high d.c. current like as 20 MA to energize the coil. Considering the ratings of such extremely high current and low voltage, power-MOSFET element is employed as the switching device for the a.c./d.c. converter of power supply. One of the advantages of power-MOSFET element is low on-state resistance, which is to meet the high current and low voltage operation. Recently, the capacity of power-MOSFET element has been increased and its on-state resistance has been decreased, so that the possibility of construction of high current and low voltage a.c./d.c. converter with parallel connected power-MOSFET elements has been growing. With the aim of developing the high current d.c. power supply using power-MOSFET, the basic characteristics of parallel operation with power-MOSFET elements are experimentally investigated. And, the synchronous rectifier type and the bi-directional self commutated type a.c./d.c. converters using parallel connected power-MOSFET elements are proposed

  13. High magnetic field science and its application in the United States current status and future directions

    CERN Document Server

    National Research Council of the National Academies

    2013-01-01

    The Committee to Assess the Current Status and Future Direction of High Magnetic Field Science in the United States was convened by the National Research Council in response to a request by the National Science Foundation. This report answers three questions: (1) What is the current state of high-field magnet science, engineering, and technology in the United States, and are there any conspicuous needs to be addressed? (2) What are the current science drivers and which scientific opportunities and challenges can be anticipated over the next ten years? (3) What are the principal existing and planned high magnetic field facilities outside of the United States, what roles have U.S. high field magnet development efforts played in developing those facilities, and what potentials exist for further international collaboration in this area? A magnetic field is produced by an electrical current in a metal coil. This current exerts an expansive force on the coil, and a magnetic field is "high" if it challenges the str...

  14. Development of an IH-type linac for the acceleration of high current heavy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Haehnel, Jan Hendrik

    2017-07-20

    The Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt will provide unprecedented intensities of protons and heavy ions up to uranium at energies of up to 29 GeV for protons and 2.7 GeV/u for U{sup 28+}. To achieve high intensities in the synchrotron accelerators, high beam currents have to be provided by the injector linear accelerators. High current heavy ion beams are provided by the Universal Linear Accelerator (UNILAC), which in its current state will not be able to provide the required FAIR beam currents. This thesis deals with the development of upgrades for the UNILAC to ensure its high current capability. The first improvement is a matching section (MEBT) for the interface between the RFQ and the IH-DTL of the existing high current injector HSI at the UNILAC. With this new MEBT section, particle losses are eliminated and the overall beam quality is improved. As a second improvement, a complete replacement of the existing Alvarez-DTL is presented. A combination of efficient IH-type cavities and KONUS beam dynamics results in a reduction of the linac length from about 60 m (Alvarez) to just 23 m (new IH-DTL) while providing the same energy and fulfilling FAIR requirements of a high beam current and beam quality. This thesis contains a detailed beam dynamics design of the new linac including some fundamental investigations of the KONUS beam dynamics concept. A cross-check of the beam dynamics design was performed with two independent multi-particle simulation codes. Detailed error studies were conducted to investigate the influence of manufacturing, alignment and operating errors on the beam dynamics performance. Additionally, all five linac cavities were designed, optimized, and their RF parameters including power requirements calculated to provide a comprehensive linac design.

  15. Development of an IH-type linac for the acceleration of high current heavy ion beams

    International Nuclear Information System (INIS)

    Haehnel, Jan Hendrik

    2017-01-01

    The Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt will provide unprecedented intensities of protons and heavy ions up to uranium at energies of up to 29 GeV for protons and 2.7 GeV/u for U 28+ . To achieve high intensities in the synchrotron accelerators, high beam currents have to be provided by the injector linear accelerators. High current heavy ion beams are provided by the Universal Linear Accelerator (UNILAC), which in its current state will not be able to provide the required FAIR beam currents. This thesis deals with the development of upgrades for the UNILAC to ensure its high current capability. The first improvement is a matching section (MEBT) for the interface between the RFQ and the IH-DTL of the existing high current injector HSI at the UNILAC. With this new MEBT section, particle losses are eliminated and the overall beam quality is improved. As a second improvement, a complete replacement of the existing Alvarez-DTL is presented. A combination of efficient IH-type cavities and KONUS beam dynamics results in a reduction of the linac length from about 60 m (Alvarez) to just 23 m (new IH-DTL) while providing the same energy and fulfilling FAIR requirements of a high beam current and beam quality. This thesis contains a detailed beam dynamics design of the new linac including some fundamental investigations of the KONUS beam dynamics concept. A cross-check of the beam dynamics design was performed with two independent multi-particle simulation codes. Detailed error studies were conducted to investigate the influence of manufacturing, alignment and operating errors on the beam dynamics performance. Additionally, all five linac cavities were designed, optimized, and their RF parameters including power requirements calculated to provide a comprehensive linac design.

  16. The most intense current sheets in the high-speed solar wind near 1 AU

    Science.gov (United States)

    Podesta, John J.

    2017-03-01

    Electric currents in the solar wind plasma are investigated using 92 ms fluxgate magnetometer data acquired in a high-speed stream near 1 AU. The minimum resolvable scale is roughly 0.18 s in the spacecraft frame or, using Taylor's "frozen turbulence" approximation, one proton inertial length di in the plasma frame. A new way of identifying current sheets is developed that utilizes a proxy for the current density J obtained from the derivatives of the three orthogonal components of the observed magnetic field B. The most intense currents are identified as 5σ events, where σ is the standard deviation of the current density. The observed 5σ events are characterized by an average scale size of approximately 3di along the flow direction of the solar wind, a median separation of around 50di or 100di along the flow direction of the solar wind, and a peak current density on the order of 0.5 pA/cm2. The associated current-carrying structures are consistent with current sheets; however, the planar geometry of these structures cannot be confirmed using single-point, single-spacecraft measurements. If Taylor's hypothesis continues to hold for the energetically dominant fluctuations at kinetic scales 1current-carrying structures in high-speed wind occur at electron scales, although the peak current densities at kinetic and electron scales are predicted to be nearly the same as those found in this study.

  17. Highly Sensitive Measurements of the Dark Current of Superconducting Cavities for TESLA Using a SQUID Based Cryogenic Current Comparator

    CERN Document Server

    Vodel, W; Nietzsche, S

    2004-01-01

    This contribution presents a Cryogenic Current Comparator (CCC) as an excellent tool for detecting dark currents generated, e.g. by superconducting cavities for the upcoming TESLA project (X-FEL) at DESY. To achieve the maximum possible energy the gradient of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The undesired field emission of electrons (so-called dark current) of the superconducting RF cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a highly sensitive LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measu...

  18. Adaptation of superconducting fault current limiter to high-speed reclosing

    International Nuclear Information System (INIS)

    Koyama, T.; Yanabu, S.

    2009-01-01

    Using a high temperature superconductor, we constructed and tested a model superconducting fault current limiter (SFCL). The superconductor might break in some cases because of its excessive generation of heat. Therefore, it is desirable to interrupt early the current that flows to superconductor. So, we proposed the SFCL using an electromagnetic repulsion switch which is composed of a superconductor, a vacuum interrupter and a by-pass coil, and its structure is simple. Duration that the current flow in the superconductor can be easily minimized to the level of less than 0.5 cycle using this equipment. On the other hand, the fault current is also easily limited by large reactance of the parallel coil. There is duty of high-speed reclosing after interrupting fault current in the electric power system. After the fault current is interrupted, the back-up breaker is re-closed within 350 ms. So, the electromagnetic repulsion switch should return to former state and the superconductor should be recovered to superconducting state before high-speed reclosing. Then, we proposed the SFCL using an electromagnetic repulsion switch which employs our new reclosing function. We also studied recovery time of the superconductor, because superconductor should be recovered to superconducting state within 350 ms. In this paper, the recovery time characteristics of the superconducting wire were investigated. Also, we combined the superconductor with the electromagnetic repulsion switch, and we did performance test. As a result, a high-speed reclosing within 350 ms was proven to be possible.

  19. Prospects for Off-axis Current Drive via High Field Side Lower Hybrid Current Drive in DIII-D

    Science.gov (United States)

    Wukitch, S. J.; Shiraiwa, S.; Wallace, G. M.; Bonoli, P. T.; Holcomb, C.; Park, J. M.; Pinsker, R. I.

    2017-10-01

    An outstanding challenge for an economical, steady state tokamak is efficient off-axis current drive scalable to reactors. Previous studies have focused on high field side (HFS) launch of lower hybrid waves for current drive (LHCD) in double null configurations in reactor grade plasmas. The goal of this work is to find a HFS LHCD scenario for DIII-D that balances coupling, power penetration and damping. The higher magnetic field on the HFS improves wave accessibility, which allows for lower n||waves to be launched. These waves penetrate farther into the plasma core before damping at higher Te yielding a higher current drive efficiency. Utilizing advanced ray tracing and Fokker Planck simulation tools (GENRAY+CQL3D), wave penetration, absorption and drive current profiles in high performance DIII-D H-Mode plasmas were investigated. We found LH scenarios with single pass absorption, excellent wave penetration to r/a 0.6-0.8, FWHM r/a=0.2 and driven current up to 0.37 MA/MW coupled. These simulations indicate that HFS LHCD has potential to achieve efficient off-axis current drive in DIII-D and the latest results will be presented. Work supported by U.S. Dept. of Energy, Office of Science, Office of Fusion Energy Sciences, using User Facility DIII-D, under Award No. DE-FC02-04ER54698 and Contract No. DE-FC02-01ER54648 under Scientific Discovery through Advanced Computing Initiative.

  20. Controlling nonlinear longitudinal space charge oscillations for high peak current bunch train generation

    Directory of Open Access Journals (Sweden)

    P. Musumeci

    2013-10-01

    Full Text Available The evolution of picosecond modulations of the longitudinal profile of an electron beam generated in an rf photoinjector is analyzed and optimized with the goal of obtaining high peak current electron bunch trains at very high frequencies (≥THz. Taking advantage of nonlinear longitudinal space charge forces, it is found that more than 500 A peak current 1 THz bunch trains can be generated using a standard 1.6 cell SLAC/UCLA/BNL rf gun. Postacceleration is used to freeze the longitudinal phase space dynamics after one half plasma oscillation. Applications range from tunable narrow bandwidth THz radiation generation to drivers for high frequency high gradient accelerators.

  1. Electrodynamic wear of rails in high current density rail gun discharges

    International Nuclear Information System (INIS)

    Edwards, W.T.; Caldwell, S.G.

    1984-01-01

    Significant advances in high current, high speed power sources, has in recent years allowed rail guns to produce very high velocity (> 10 km/sec) macroscopic particles (> 1/10 grams). A continuing problem is the structural integrity of the components under these loadings and in particular, the rail wear due to the high current density plasma contacts. In this investigation a small bore rail gun (6x5 mm) was used with a 10.6 kjoule capacitor energy source to examine the modes of rail damage. The rails were constructed of 110 copper base material. These rails were used in an uncoated condition and also with plasma sprayed coatings of W and W/WC. The resulting surface wear was characterized by standard metallurgical techniques and analyzed for the various coatings

  2. Algorithm for evaluating the effectiveness of a high-rise development project based on current yield

    Science.gov (United States)

    Soboleva, Elena

    2018-03-01

    The article is aimed at the issues of operational evaluation of development project efficiency in high-rise construction under the current economic conditions in Russia. The author touches the following issues: problems of implementing development projects, the influence of the operational evaluation quality of high-rise construction projects on general efficiency, assessing the influence of the project's external environment on the effectiveness of project activities under crisis conditions and the quality of project management. The article proposes the algorithm and the methodological approach to the quality management of the developer project efficiency based on operational evaluation of the current yield efficiency. The methodology for calculating the current efficiency of a development project for high-rise construction has been updated.

  3. Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

    International Nuclear Information System (INIS)

    Wetteland, C. J.; Field, K. G.; Gerczak, T. J.; Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R.

    2013-01-01

    The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150μA of proton current from the source, with over 70μA on the target stage. However, beam fluxes above ∼1×10 17 /m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

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

    Science.gov (United States)

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

    2018-01-01

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

  5. Analytical study on discrete model of virtual cathode in a high-current diode

    International Nuclear Information System (INIS)

    Privezentsev, A.P.

    1988-01-01

    Interest in investigation of virtual cathode dynamics related to the development of high-current accelerator equipment is caused by the possibility of its application for ion collective acceleration in direct high-current electron beams and generation of power electromagnetic radiation. The Hamiltonian form of a plane sheet model for a high-current flux in a plane diode is investigated. Variables used permit to carry out the investigation of dynamics of the virtual cathode flux by the method of coordinate point transformations in a phase space. The necessity of numerical integration of sheet motion equations is dropped out in this case. Analytical solution of the suggested iterative circuit for total flux passage is presented as an example. The solution obtained is equivalent to the known results of the plane diode theory, obtained in the hydrodynamic approximation

  6. Effect of Abrikosov vortices on Josephson junction currents in high temperature superconductors

    International Nuclear Information System (INIS)

    Mitchell, E.; Mueller, K.-H.

    2000-01-01

    Full text: The current-carrying capacity of high temperature superconductors (HTS) is limited by the weak links which form between individual grains. We investigate the role of Abrikosov vortices (AV) and inhomogeneities at the intergrain boundary by examining the high magnetic field characteristics of HTS thin film grain boundary junctions. We model the effects of junction inhomogeneity, AV's and vortex pinning by solving the inhomogeneous London equation. The calculations show that both inhomogeneities and the presence of AV's improve the current-carrying capacity across grain boundaries at high magnetic fields. Our experimental measurements of the irreversibility of the junction critical current density J c (H a ) find good agreement with the model

  7. High-current heavy-ion accelerator system and its application to material modification

    International Nuclear Information System (INIS)

    Kishimoto, Naoki; Takeda, Yoshihiko; Lee, C.G.; Umeda, Naoki; Okubo, Nariaki; Iwamoto, Eiji

    2001-01-01

    A high-current heavy-ion accelerator system has been developed to realize intense particle fluxes for material modification. The facility of a tandem accelerator attained 1 mA-class ion current both for negative low-energy ions and positive high-energy ions. The negative ion source of the key device is of the plasma-sputter type, equipped with mutli-cusp magnets and Cs supply. The intense negative ions are either directly used for material irradiation at 60 keV or further accelerated up to 6 MeV after charge transformation. Application of negative ions, which alleviates surface charging, enables us to conduct low-energy high-current irradiation on insulating substrates. Since positive ions above the MeV range are irrelevant for Coulomb repulsion, the facility as a whole meets the needs of high-current irradiation onto insulators over a wide energy range. Application of high flux ions provides technological merits not only for efficient implantation but also for essentially different material kinetics, which may become an important tool of material modification. Other advantages of the system are co-irradiation by intense laser and in-situ detection of kinetic processes. For examples of material modifications, we present nanoparticle fabrication in insulators, and synergistic phenomena by co-irradiation due to ions and photons. (author)

  8. Low Overpotential and High Current CO2 Reduction with Surface Reconstructed Cu Foam Electrodess

    KAUST Repository

    Min, Shixiong

    2016-06-23

    While recent reports have demonstrated that oxide-derived Cu-based electrodes exhibit high selectivity for CO2 reduction at low overpotential, the low catalytic current density (<2 mA/cm2 at -0.45 V vs. RHE) still largely limits its applications for large-scale fuel synthesis. Here we report an extremely high current density for CO2 reduction at low overpotential using a Cu foam electrode prepared by air-oxidation and subsequent electroreduction. Apart from possessing three-dimensional (3D) open frameworks, the resulting Cu foam electrodes prepared at higher temperatures exhibit enhanced electrochemically active surface area and distinct surface structures. In particular, the Cu foam electrode prepared at 500 °C exhibits an extremely high geometric current density of ~9.4 mA/cm2 in CO2-satrurated 0.1 M KHCO3 aqueous solution and achieving ~39% CO and ~23% HCOOH Faradaic efficiencies at -0.45 V vs. RHE. The high activity and significant selectivity enhancement are attributable to the formation of abundant grain-boundary supported active sites and preferable (100) and (111) facets as a result of reconstruction of Cu surface facets. This work demonstrates that the structural integration of Cu foam with open 3D frameworks and the favorable surface structures is a promising strategy to develop an advanced Cu electrocatalyst that can operate at high current density and low overpotential for CO2 reduction.

  9. Recent results with a high-current, heavy-ion source system

    International Nuclear Information System (INIS)

    Keller, R.; Spaedtke, P.; Emig, H.

    1986-01-01

    In the last conference of this series, an improved high-current ion source for gases, CORDIS was presented. This source has been further developed to allow the processing of substances which are not volatile at room temperature. One of these modifications, HORDIS, incorporates an oven whereas the third version works at rather moderate temperatures and can be fed through a slightly heated external bottle. With this source system, high-current ion beams in the 100 mA range can be produced for a considerable part of the periodic table. Operation parameters and experiences with the sources are discussed, and the most recent results for all versions are given. (author)

  10. High Current Ionic Diode Using Homogeneously Charged Asymmetric Nanochannel Network Membrane.

    Science.gov (United States)

    Choi, Eunpyo; Wang, Cong; Chang, Gyu Tae; Park, Jungyul

    2016-04-13

    A high current ionic diode is achieved using an asymmetric nanochannel network membrane (NCNM) constructed by soft lithography and in situ self-assembly of nanoparticles with uniform surface charge. The asymmetric NCNM exhibits high rectified currents without losing a rectification ratio because of its ionic selectivity gradient and differentiated electrical conductance. Asymmetric ionic transport is analyzed with diode-like I-V curves and visualized via fluorescent dyes, which is closely correlated with ionic selectivity and ion distribution according to variation of NCNM geometries.

  11. Development of RF-linac and storage ring system for high-current experiments at GSI

    International Nuclear Information System (INIS)

    Hofmann, I.

    1986-08-01

    The heavy ion facility under construction at GSI is suitable for the generation of high-current beams. It consists of a new high-current injector into the Unilac and a synchrotron and storage ring. We discuss the capability of this system to produce short pulses of heavy ions with a specific energy of the order of 0.1 MJ/g. Under these conditions the system allows to perform a first generation of heavy ion driven target experiments and to test most of the critical issues of a large scale heavy ion fusion driver facility. (orig.)

  12. Generation and transportation of low-energy, high-current electron beams

    International Nuclear Information System (INIS)

    Ozur, G.E.; Proskurovskij, D.I.; Nazarov, D.S.

    1996-01-01

    Experimental data on the production of low-energy, high-current electron beams in a plasma-filled diode are presented. The highest beam energy density achieved is about 40 J/cm 2 , which makes it possible to treat materials in the mode of intense evaporation of the surface layer. It was shown that the use of a hollow cathode improves the beam homogeneity. The feasibility was demonstrated of the production of low-energy high-current electron beams in a gun with plasma anode based on the use of a reflective discharge. (author). 6 figs., 6 refs

  13. Eddy-current inspection of high flux isotope reactor nuclear control rods

    International Nuclear Information System (INIS)

    Smith, J.H.; Chitwood, L.D.

    1981-07-01

    Inner control rods for the High Flux Isotope Reactor were nondestructively inspected for defects by eddy-current techniques. During these examinations aluminum cladding thickness and oxide thickness on the cladding were also measured. Special application techniques were required because of the high-radiation levels (approx. 10 5 R/h at 30 cm) present and the relatively large temperature gradients that occurred on the surface of the control rods. The techniques used to perform the eddy-current inspections and the methods used to reduce the associated data are described

  14. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    International Nuclear Information System (INIS)

    Bouda, N. R.; Pritchard, J.; Weber, R. J.; Mina, M.

    2015-01-01

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG 1 ) and MOSFET circuits (HCMFG 2 ) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed

  15. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    Science.gov (United States)

    Bouda, N. R.; Pritchard, J.; Weber, R. J.; Mina, M.

    2015-05-01

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/-20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG1) and MOSFET circuits (HCMFG2) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  16. High-voltage integrated linear regulator with current sinking capabilities for portable ultrasound scanners

    DEFF Research Database (Denmark)

    Pausas, Guifre Vendrell; Llimos Muntal, Pere; Jørgensen, Ivan Harald Holger

    2017-01-01

    This paper presents a high-voltage integrated regulator capable of sinking current for driving pulse-triggered level shifters in drivers for ultrasound applications. The regulator utilizes a new topology with a feedback loop and a current sinking circuit to satisfy the requirements of the portable....... The proposed design has been implemented in high-voltage 0.18 μm process whithin an area of 0.11 mm2 and it is suitable for system-on-chip integration due to its low component count and the fully integrated design....

  17. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    Energy Technology Data Exchange (ETDEWEB)

    Bouda, N. R., E-mail: nybouda@iastate.edu; Pritchard, J.; Weber, R. J.; Mina, M. [Department of Electrical and Computer engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2015-05-07

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG{sub 1}) and MOSFET circuits (HCMFG{sub 2}) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  18. Generation and transportation of low-energy, high-current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Ozur, G E; Proskurovskij, D I; Nazarov, D S [Russian Academy of Sciences, Tomsk (Russian Federation). Institute of High Current Electronics

    1997-12-31

    Experimental data on the production of low-energy, high-current electron beams in a plasma-filled diode are presented. The highest beam energy density achieved is about 40 J/cm{sup 2}, which makes it possible to treat materials in the mode of intense evaporation of the surface layer. It was shown that the use of a hollow cathode improves the beam homogeneity. The feasibility was demonstrated of the production of low-energy high-current electron beams in a gun with plasma anode based on the use of a reflective discharge. (author). 6 figs., 6 refs.

  19. Design of Jet lower hybrid current drive generator and operation of high power test bed

    International Nuclear Information System (INIS)

    Dobbing, J.A.; Bosia, G.; Brandon, M.; Gammelin, M.; Gormezano, C.; Jacquinot, J.; Jessop, G.; Lennholm, M.; Pain, M.; Sibley, A.

    1989-01-01

    The JET Lower Hybrid Current Drive (LHCD) generator consists of 24 klystrons each rated for 650 KW operating at 3.7 GHz, giving a nominal generator power of 15.6 MW for 10 seconds or 12 MW for 20 seconds. This power will be transmitted through 24 waveguides to a phased array launcher on one of the main ports of the JET machine. In addition, two klystrons are currently being operated on a high power test bed to establish reliable operation of the generators components and test high power microwave components prior to their installation

  20. Quench protection and design of large high-current-density superconducting magnets

    International Nuclear Information System (INIS)

    Green, M.A.

    1981-03-01

    Although most large superconducting magnets have been designed using the concept of cryostability, there is increased need for large magnets which operate at current densities above the cryostable limit (greater than 10 8 Am -2 ). Large high current density superconducting magnets are chosen for the following reasons: reduced mass, reduced coil thickness or size, and reduced cost. The design of large high current density, adiabatically stable, superconducting magnets requires a very different set of design rules than either large cryostable superconducting magnets or small self-protected high current density magnets. The problems associated with large high current density superconducting magnets fall into three categories; (a) quench protection, (b) stress and training, and (c) cryogenic design. The three categories must be considered simultaneously. The paper discusses quench protection and its implication for magnets of large stored energies (this includes strings of smaller magnets). Training and its relationship to quench protection and magnetic strain are discussed. Examples of magnets, built at the Lawrence Berkeley Laboratory and elsewhere using the design guidelines given in this report, are presented

  1. High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

    Directory of Open Access Journals (Sweden)

    M. Drinovsky

    2015-12-01

    Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

  2. 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

  3. Choice of initial operating parameters for high average current linear accelerators

    International Nuclear Information System (INIS)

    Batchelor, K.

    1976-01-01

    Recent emphasis on alternative energy sources together with the need for intense neutron sources for testing of materials for CTR has resulted in renewed interest in high current (approximately 100 mA) c.w. proton and deuteron linear accelerators. In desinging an accelerator for such high currents, it is evident that beam losses in the machine must be minimized, which implies well matched beams, and that adequate acceptance under severe space charge conditions must be met. An investigation is presented of the input parameters to an Alvarez type drift-tube accelerator resulting from such factors. The analysis indicates that an accelerator operating at a frequency of 50 MHz is capable of accepting deuteron currents of about 0.4 amperes and proton currents of about 1.2 amperes. These values depend critically on the assumed values of beam emittance and on the ability to properly ''match'' this to the linac acceptance

  4. Coherent radiation from high-current electron beams of linear accelerators and its applications

    International Nuclear Information System (INIS)

    Okuda, Shuichi; Takanaka, Makoto; Nakamura, Mitsumi; Kato, Ryukou; Takahashi, Toshiharu; Nam, Soon-Kwon; Taniguchi, Ryouichi; Kojima, Takao

    2006-01-01

    The characteristics of the far-infrared light source using the coherent radiation emitted from a high-energy short electron bunch have been investigated. The coherent radiation has a continuous spectrum in a submillimeter to millimeter wavelength range and the brightness is relatively high. The spectrum of the radiation is determined by the longitudinal form factor of the electron bunch. The operational conditions of a high-current linear accelerator have been optimized using an electron bunch shape monitor. The coherent transition radiation light source has been applied to absorption spectroscopy for liquid water and to an imaging experiment for a leaf of rose

  5. Development of a high current 250 kV photocathode dc gun

    International Nuclear Information System (INIS)

    Nishimori, Nobuyuki; Nagai, Ryoji; Sawamura, Masaru; Hajima, Ryoichi

    2016-01-01

    We have developed a high current photocathode dc gun at JAEA for the next generation light sources such as an energy recovery linac and high-repetition rate X-ray free electron laser. The gun is equipped with a multialkali photocathode preparation system. Quantum efficiency of 0.37% at 532 nm was obtained for a Cs_3Sb photocathode. The gun was high voltage conditioned up to 230 kV with a cathode electrode. Beam generation test from the multialkali photocathode will be performed by the end of FY2015. (author)

  6. Stationary high confinement plasmas with large bootstrap current fraction in JT-60U

    International Nuclear Information System (INIS)

    Sakamoto, Y.; Fujita, T.; Ide, S.; Isayama, A.; Takechi, M.; Suzuki, T.; Takenaga, H.; Oyama, N.; Kamada, Y.

    2005-01-01

    This paper reports the results of the progress in stationary discharges with a large bootstrap current fraction in JT-60U towards steady-state tokamak operation. In the weak shear plasma regime, high-β p ELMy H-mode discharges have been optimized under nearly full non-inductive current drive conditions by the large bootstrap current fraction (f BS ∼ 45%) and the beam driven current fraction (f BD ∼ 50%), which was sustained for 5.8 s in the stationary condition. This duration corresponds to ∼26τ E and ∼2.8τ R , which was limited by the pulse length of negative-ion-based neutral beams. The high confinement enhancement factor H 89 ∼ 2.2 (HH 98y2 ∼ 1.0) was obtained and the profiles of current and pressure reached the stationary condition. In the reversed shear plasma regime, a large bootstrap current fraction (f BS ∼ 75%) has been sustained for 7.4 s under nearly full non-inductive current drive conditions. This duration corresponds to ∼16τ E and ∼2.7τ R . The high confinement enhancement factor H 89 ∼ 3.0 (HH 98y2 ∼ 1.7) was also sustained, and the profiles of current and pressure reached the stationary condition. The large bootstrap current and the off-axis beam driven current sustained this reversed q profile. This duration was limited only by the duration of the neutral beam injection

  7. Current measurement in high-performance frequency converters; Strommessung in Hochleistungsumrichtern

    Energy Technology Data Exchange (ETDEWEB)

    Marien, Jan; Hetzler, Ullrich [Isabellenhuette Heusler GmbH und Co. KG, Dillenburg (Germany); Hornung, Hans-Georg; Zwinger, Stefan [Sensor-Technik Wiedemann GmbH, Kaufbeuren (Germany)

    2011-04-15

    The load cycles (raising, lowering, accelerating, braking) of cranes, lift trucks and other off-road vehicles are ideally suited for the efficient deployment of hybrid or full electrical drive technology. Current measurement is a key technology for advancing electrification. Sensor Technik Wiedemann places by her frequency converters on a shunt-based current measurement module from Isabellenhuette Heusler which permits highly accurate measurements. (orig.)

  8. 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.

  9. Critical current measurements of high Tc superconductors in a scanning low temperature cryostat

    International Nuclear Information System (INIS)

    Telschow, K.L.; O'Brien, T.K.

    1991-01-01

    Maintaining uniformity of properties over long distances is one of the fabrication problems encountered with the new high T c superconductors. Uniform properties are crucial in long tapes or wires with high critical current since local nonuniformities can limit the current carrying capacity of the whole piece. Transport critical currents in high T c superconductors are conventionally measured with the contact 4-point probe DC current-voltage technique. This technique requires contact with the sample and and spatially averages over the region between the two voltage contacts. Two techniques have been used to infer the critical state model. The first uses the net magnetization of a suitably shaped sample in an external magnetic field. The second combines a DC magnetic field with AC induced currents to infer spatial flux profiles. The AC magnetization technique offers an advantage in that it is noncontacting; however, it also averages the measurement over a large area and requires that the sample be shaped and positioned such that it exhibits zero demagnetizing factor. This paper describes a measurement technique and a scanning cryostat assembly that are capable of determining local critical current in a tape or wire with high resolution and without any direct sample electrical contact. A small compensated coil was used to induce AC currents in slab-shaped samples. The coil was situated near the surface on one side of the slab. With this method, the AC probe can be used as a noncontacting dissipation probe, replacing the voltage probe in the 4-point contact method, when an externally driven transport current is used, or by itself as a local critical state generator and dissipation detector. The results are shown to be meaningful even when the internal magnetic field is not uniform due to shape demagnetizing effects. 10 refs., 5 figs

  10. Development of an intelligent high-voltage direct-current power supply for nuclear detectors

    International Nuclear Information System (INIS)

    Zhao Xiuliang

    1997-01-01

    The operation and performances of a new type direct-current high-voltage power supply are described. The power supply with intelligent feature is controlled by a single-chip microcomputer (8031), and various kinds of output voltage can be preset. The output-voltage is monitored and regulated by the single-chip microcomputer and displayed by LED. The output voltage is stable when the load current is within the allowable limits

  11. High-energy manifestations of heavy quarks in axial-vector neutral currents

    International Nuclear Information System (INIS)

    Kizukuri, Y.; Ohba, I.; Okano, K.; Yamanaka, Y.

    1981-01-01

    A recent work by Collins, Wilczek, and Zee has attempted to manifest the incompleteness of the decoupling theorem in the axial-vector neutral currents at low energies. In the spirit of their work, we calculate corrections of the axial-vector neutral currents by virtual-heavy-quark exchange in the high-energy e + e - processes and estimate some observable quantities sensitive to virtual-heavy-quark masses which may be compared with experimental data at LEP energies

  12. A high linearity current mode multiplier/divider with a wide dynamic range

    International Nuclear Information System (INIS)

    Liao Pengfei; Luo Ping; Zhang Bo; Li Zhaoji

    2012-01-01

    A high linearity current mode multiplier/divider (CMM/D) with a wide dynamic range is presented. The proposed CMM/D is based on the voltage—current characteristic of the diode, thus wide dynamic range is achieved. In addition, high linearity is achieved because high accuracy current mirrors are adopted and the output current is insensitive to the temperature and device parameters of the fabrication process. Furthermore, no extra bias current for all input signals is required and thus power saving is realized. With proper selection of establishing the input terminal, the proposed circuit can perform as a multifunction circuit to be operated as a multiplier/divider, without changing its topology. The proposed circuit is implemented in a 0.25 μm BCD process and the chip area is 0.26 × 0.24 mm 2 . The simulation and measurement results show that the maximum static linearity error is ±1.8% and the total harmonic distortion is 0.4% while the input current ranges from 0 to 200 μA. (semiconductor integrated circuits)

  13. Production of a high-current microsecond electron beam with a large cross section

    International Nuclear Information System (INIS)

    Abdullin, E.N.; Belomytsev, S.Ya.; Bugaev, S.P.; Gorbachev, S.I.; Zaslavskii, V.M.; Zorin, V.P.; Koval'chuk, B.M.; Loginov, S.V.; Matyukov, Yu.N.; Rasputin, R.M.; Tolkachev, V.S.; Shchanin, P.M.

    1991-01-01

    Obtaining high-current wide-aperture electron beams is an important problem in the development of laser technology for controlled nuclear fusion and for solving ecological and technological problems. The main scheme for producing such beams involves the use of generators with intermediate energy storage devices and burst-emission vacuum diodes. Beam pinching is prevented by using an external magnetic field or sectioning the diode into magnetically insulated diodes with currents lower than the limiting current. The length of the electron-current pulse varies from tens to hundreds of nano-seconds and is limited by the parameters of the intermediate storage device. Here the authors study the formation of a high-current electron beam with a square cross section and a current of the order of the limiting current of the diode in the absence of an external magnetic field as well as a 'fast' storage device in the power supply circuit. These conditions as a whole correspond to a simpler electron-source circuit, but the beam forming becomes more complicated. The reason for this is that there is no external magnetic field and that the role of plasma processes in the diode is enhanced by the greater length of the electron-current pulses

  14. The influence of conductivities consistent with field-aligned currents on high-latitude convection patterns

    International Nuclear Information System (INIS)

    Blomberg, L.G.; Marklund, G.T.

    1988-02-01

    The influence on the high-latitude ionospheric convection of conductivities associated with upward field-aligned currents is investigated. Potential patterns are calculated from a given distribution of field-aligned currents and a conductivity model. The resulting patterns are shown to be modified considerably by including a coupling term between the conductivity and the field-aligned current in the conductivity model. The clockwise rotation of the entire potential pattern is reduced when the conductivity enhancement coincides with the regions of upward field-aligned current. Also, the electric field within these regions turns out to be rather insensitive to change in the magnitude of the current. In regions of downward current or when the current-dependent conductivity is excluded there is on the other hand an almost linear relationship between current and electric field. Although the particles producing the conductivity enhancement may not be the same as those carrying the major part of the field-aligned current it is clear from observations that there is a positive correlation between upward current conductivity. Therefore, the simple relationship used in this study is believed to reflect rather well the principal features of the current-conductivity coupling, which is of im- portance to the modelling of ionospheric electrodynamics. (With 26 refs.) (authors)

  15. Method and system for a gas tube-based current source high voltage direct current transmission system

    Science.gov (United States)

    She, Xu; Chokhawala, Rahul Shantilal; Bray, James William; Sommerer, Timothy John; Zhou, Rui; Zhang, Di

    2017-08-29

    A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

  16. Theory and application of high temperature superconducting eddy current probes for nondestructive evaluation

    Science.gov (United States)

    Claycomb, James Ronald

    1998-10-01

    Several High-T c Superconducting (HTS) eddy current probes have been developed for applications in electromagnetic nondestructive evaluation (NDE) of conducting materials. The probes utilize high-T c SUperconducting Quantum Interference Device (SQUID) magnetometers to detect the fields produced by the perturbation of induced eddy currents resulting from subsurface flaws. Localized HTS shields are incorporated to selectively screen out environmental electromagnetic interference and enable movement of the instrument in the Earth's magnetic field. High permeability magnetic shields are employed to focus flux into, and thereby increase the eddy current density in the metallic test samples. NDE test results are presented, in which machined flaws in aluminum alloy are detected by probes of different design. A novel current injection technique performing NDE of wires using SQUIDs is also discussed. The HTS and high permeability shields are designed based on analytical and numerical finite element method (FEM) calculations presented here. Superconducting and high permeability magnetic shields are modeled in uniform noise fields and in the presence of dipole fields characteristic of flaw signals. Several shield designs are characterized in terms of (1) their ability to screen out uniform background noise fields; (2) the resultant improvement in signal-to-noise ratio and (3) the extent to which dipole source fields are distorted. An analysis of eddy current induction is then presented for low frequency SQUID NDE. Analytical expressions are developed for the induced eddy currents and resulting magnetic fields produced by excitation sources above conducting plates of varying thickness. The expressions derived here are used to model the SQUID's response to material thinning. An analytical defect model is also developed, taking into account the attenuation of the defect field through the conducting material, as well as the current flow around the edges of the flaw. Time harmonic

  17. The effects of high frequency current ripple on electric vehicle battery performance

    International Nuclear Information System (INIS)

    Uddin, Kotub; Moore, Andrew D.; Barai, Anup; Marco, James

    2016-01-01

    Highlights: • Experimental study into the impact of current ripple on li-ion battery degradation. • 15 cells exercised with 1200 cycles coupled AC–DC signals, at 5 frequencies. • Results highlight a greater spread of degradation for cells exposed to AC excitation. • Implications for BMS control, thermal management and system integration. - Abstract: The power electronic subsystems within electric vehicle (EV) powertrains are required to manage both the energy flows within the vehicle and the delivery of torque by the electrical machine. Such systems are known to generate undesired electrical noise on the high voltage bus. High frequency current oscillations, or ripple, if unhindered will enter the vehicle’s battery system. Real-world measurements of the current on the high voltage bus of a series hybrid electric vehicle (HEV) show that significant current perturbations ranging from 10 Hz to in excess of 10 kHz are present. Little is reported within the academic literature about the potential impact on battery system performance and the rate of degradation associated with exposing the battery to coupled direct current (DC) and alternating currents (AC). This paper documents an experimental investigation that studies the long-term impact of current ripple on battery performance degradation. Initial results highlight that both capacity fade and impedance rise progressively increase as the frequency of the superimposed AC current increases. A further conclusion is that the spread of degradation for cells cycled with a coupled AC–DC signal is considerably more than for cells exercised with a traditional DC waveform. The underlying causality for this degradation is not yet understood. However, this has important implications for the battery management system (BMS). Increased variations in cell capacity and impedance will cause differential current flows and heat generation within the battery pack that if not properly managed will further reduce battery life

  18. 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.

  19. High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

    CERN Document Server

    Jørgensen, H E; Dupaquier, A; Fernqvist, G

    1998-01-01

    The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

  20. Temperature calculations of heat loads in rotating target wheels exposed to high beam currents

    International Nuclear Information System (INIS)

    Greene, John P.; Gabor, Rachel; Neubauer, Janelle

    2001-01-01

    In heavy-ion physics, high beam currents can eventually melt or destroy the target. Tightly focused beams on stationary targets of modest melting point will exhibit short lifetimes. Defocused or 'wobbled' beams are employed to enhance target survival. Rotating targets using large diameter wheels can help overcome target melting and allow for higher beam currents to be used in experiments. The purpose of the calculations in this work is to try and predict the safe maximum beam currents which produce heat loads below the melting point of the target material

  1. Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2010-01-01

    In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring...... the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress...

  2. Temperature calculations of heat loads in rotating target wheels exposed to high beam currents

    International Nuclear Information System (INIS)

    Greene, J. P.; Gabor, R.; Neubauer, J.

    2000-01-01

    In heavy-ion physics, high beam currents can eventually melt or destroy the target. Tightly focused beams on stationary targets of modest melting point will exhibit short lifetimes. Defocused or wobbled beams are employed to enhance target survival. Rotating targets using large diameter wheels can help overcome target melting and allow for higher beam currents to be used in experiments. The purpose of the calculations in this work is to try and predict the safe maximum beam currents which produce heat loads below the melting point of the target material

  3. Measurements of high-current electron beams from X pinches and wire array Z pinches

    International Nuclear Information System (INIS)

    Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Bell, K. S.; Hammer, D. A.; Agafonov, A. V.; Romanova, V. M.; Mingaleev, A. R.

    2008-01-01

    Some issues concerning high-current electron beam transport from the X pinch cross point to the diagnostic system and measurements of the beam current by Faraday cups are discussed. Results of computer simulation of electron beam propagation from the pinch to the Faraday cup give limits for the measured current for beams having different energy spreads. The beam is partially neutralized as it propagates from the X pinch to a diagnostic system, but within a Faraday cup diagnostic, space charge effects can be very important. Experimental results show evidence of such effects.

  4. Braverman, Foucault and the Labor Process: Framing the Current High-Skills Debate

    Science.gov (United States)

    Lewis, Theodore

    2007-01-01

    This article examines the current high-skills discourse against the backdrop of labor process theory. It draws on the theoretical debate between Harry Braverman and Michael Foucault, supplementing the traditional treatment of the labor process with Foucauldian insights. The primary argument is that especially in the market-led economies, current…

  5. Low Overpotential and High Current CO2 Reduction with Surface Reconstructed Cu Foam Electrodess

    KAUST Repository

    Min, Shixiong; Yang, Xiulin; Lu, Ang-Yu; Tseng, Chien-Chih; Hedhili, Mohamed N.; Li, Lain-Jong; Huang, Kuo-Wei

    2016-01-01

    for large-scale fuel synthesis. Here we report an extremely high current density for CO2 reduction at low overpotential using a Cu foam electrode prepared by air-oxidation and subsequent electroreduction. Apart from possessing three-dimensional (3D) open

  6. Analysis and design of a charge pump circuit for high output current applications

    NARCIS (Netherlands)

    van Steenwijk, Gijs; van Steenwijk, Gijs; Hoen, Klaas; Hoen, Klaas; Wallinga, Hans

    1993-01-01

    A charge pump circuit has been developed that can deliver high currents even for a system supply voltage of 3 V. The circuit consists of capacitances, connected by MOS switches. The influence of the on-resistance of the switches on the circuit's output resistance has been analysed. The switches are

  7. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.

    2015-12-09

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  8. The Written-Pole{sup TM} motor: high efficiency - low start current

    Energy Technology Data Exchange (ETDEWEB)

    Beck, B. [C.Eng. Precise Power Corp., Bradenton, FL (United States); Friesen, D. [P.E. Manitoba Hydro, Winnipeg (Canada)

    2000-07-01

    Written-Pole{sup TM} technology is a patented machine technology, which changes the magnetic polarity of the rotor field in a rotating machine, while the machine is operating. The number of poles is thereby changed, resulting in a constant frequency - variable speed machine. When operating as a motor, a Written-Pole machine has inherently low starting current and high operating efficiency. (orig.)

  9. The current role of high-resolution ultrasonography of the hand and wrist in rheumatic diseases

    NARCIS (Netherlands)

    van Vugt, R. M.; van Dalen, A.; Bijlsma, J. W.

    1998-01-01

    To assess the current role of ultrasound in the diagnosis and treatment of pathological changes in the wrist and hand. 39 patients (14 male and 25 female, mean age 35 yrs.) with ill-defined pain and/or swelling of the wrist or hand were examined using a high-definition ultrasound (US) instrument. 18

  10. 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

  11. Developments in the area of high-current-superconductivity in the Kernforschungszentrum Karlsruhe

    International Nuclear Information System (INIS)

    Maurer, W.; Arendt, F.; Bruenner, N.; Erb, J.; Fessler, N.; Hartwig, G.; Heinz, W.; Hofmann, A.; Juengst, K.P.; Katheder, H.

    1976-05-01

    In this report the development work is presented which has been done from 1971 to 1975 on High-Current-Superconducticity at the institute IEKP III. The report deals with the development, construction and operation of superconducting magnets, with material investigations and with the pursued applications of superconducting Magnettechnology in research and industry. (orig.) [de

  12. The high current test facility injector operation to 40 mA dc

    International Nuclear Information System (INIS)

    Ungrin, J.; Ormrod, J.H.; Michel, W.L.

    1976-01-01

    The high current test facility injector is a 750 keV proton accelerator designed to investigate the problems involved in the acceleration of intense dc proton beams. The performance of the injector and the experience gained in operation with dc beams up to 40 mA are described. (author)

  13. On Leakage Current Measured at High Cell Voltages in Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Vadivel, Nicole R.; Ha, Seungbum; He, Meinan; Dees, Dennis; Trask, Steve; Polzin, Bryant; Gallagher, Kevin G.

    2017-01-01

    In this study, parasitic side reactions in lithium-ion batteries were examined experimentally using a potentiostatic hold at high cell voltage. The experimental leakage current measured during the potentiostatic hold was compared to the Tafel expression and showed poor agreement with the expected transfer coefficient values, indicating that a more complicated expression could be needed to accurately capture the physics of this side reaction. Here we show that cross-talk between the electrodes is the primary contribution to the observed leakage current after the relaxation of concentration gradients has ceased. This cross-talk was confirmed with experiments using a lithium-ion conducting glass ceramic (LICGC) separator, which has high conductance only for lithium cations. The cells with LICGC separators showed significantly less leakage current during the potentiostatic hold test compared to cells with standard microporous separators where cross-talk is present. In addition, direct-current pulse power tests show an impedance rise for cells held at high potentials and for cells held at high temperatures, which could be attributed to film formation from the parasitic side reaction. Based on the experimental findings, a phenomenological mechanism is proposed for the parasitic side reaction which accounts for cross-talk and mass transport of the decomposition products across the separator.

  14. High Order Voltage and Current Harmonic Mitigation Using the Modular Multilevel Converter STATCOM

    NARCIS (Netherlands)

    Kontos, E.; Tsolaridis, Georgios; Teodorescu, Remus; Bauer, P.

    2017-01-01

    Due to the increase of power electronic-based loads, the maintenance of high power quality poses a challenge in modern power systems. To limit the total harmonic distortion in the line voltage and currents at the point of the common coupling (PCC), active power filters are commonly employed. This

  15. Choice of initial operating parameters for high average current linear accelerators

    International Nuclear Information System (INIS)

    Batchelor, K.

    1976-01-01

    In designing an accelerator for high currents it is evident that beam losses in the machine must be minimized, which implies well matched beams, and that adequate acceptance under severe space charge conditions must be met. This paper investigates the input parameters to an Alvarez type drift-tube accelerator resulting from such factors

  16. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.; Lan, Yann Wen; Zeng, Caifu; Chen, Jyun Hong; Kou, Xufeng; Navabi, Aryan; Tang, Jianshi; Montazeri, Mohammad; Adleman, James R.; Lerner, Mitchell B.; Zhong, Yuan Liang; Li, Lain-Jong; Chen, Chii Dong; Wang, Kang L.

    2015-01-01

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  17. Lower hybrid current drive at ITER-relevant high plasma densities

    International Nuclear Information System (INIS)

    Cesario, R.; Amicucci, L.; Cardinali, A.; Castaldo, C.; Marinucci, M.; Panaccione, L.; Pericoli-Ridolfini, V.; Tuccillo, A. A.; Tudisco, O.; Calabro, G.

    2009-01-01

    Recent experiments indicated that a further non-inductive current, besides bootstrap, should be necessary for developing advanced scenario for ITER. The lower hybrid current drive (LHCD) should provide such tool, but its effectiveness was still not proved in operations with ITER-relevant density of the plasma column periphery. Progress of the LH deposition modelling is presented, performed considering the wave physics of the edge, and different ITER-relevant edge parameters. Operations with relatively high edge electron temperatures are expected to reduce the LH || spectral broadening and, consequently, enabling the LH power to propagate also in high density plasmas ( || is the wavenumber component aligned to the confinement magnetic field). New results of FTU experiments are presented, performed by following the aforementioned modeling: they indicate that, for the first time, the LHCD conditions are established by operating at ITER-relevant high edge densities.

  18. Transfer and focusing of high current relativistic electron beams on a target

    International Nuclear Information System (INIS)

    Baranchikov, E.I.; Gordeev, A.V.; Koba, Yu.V.; Korolev, V.D.; Penkina, V.S.; Rudakov, L.I.; Smirnov, V.P.; Sukhov, A.D.; Tarumov, E.Z.; Bakshaeev, Yu.L.

    Research is being conducted at the I. V. Kurchatov Atomic Energy Institute to investigate possibilities of creating a pulsed thermonuclear reactor based on REBs; this work involves the creation of a multimodel system using vacuum lines for transferring energy and an acute angled external magnetic field for transferring electron beams to the target. A field of this configuration can be used at the same time for accumulating a ''cloud'' of relativistic protons around the target for purposes of irradiating them. This alternative solution of the problem of target irradiation, instead of focusing beams directly on it, may prove to be highly promising. Experiments are described which were conducted recently on high current electron accelerators ''URAL'', ''MS'' and others and which were directed at investigating possibilities of transferring and focusing high current REBs, as well as effective transmission of electromagnetic energy using vacuum lines at considerable distances

  19. R and D status of high-current accelerators at IFP

    International Nuclear Information System (INIS)

    Deng, J. J.; Shi, J. S.; Xie, W. P.

    2011-01-01

    High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Z-pinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 x 60 ns) to be built will be presented briefly.

  20. 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

  1. Development of a high average current polarized electron source with long cathode operational lifetime

    Directory of Open Access Journals (Sweden)

    C. K. Sinclair

    2007-02-01

    Full Text Available Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2×10^{5}   C/cm^{2} and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  2. Design and Test of a Thermal Triggered Persistent Current System using High Temperature Superconducting Tapes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong Keun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Kang, Hyoungku [Electro-Mechanical Research Institute, Hyundai Heavy Industries, Yongin (Korea, Republic of); Ahn, Min Cheol [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yang, Seong Eun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yoon, Yong Soo [Department of Electrical Engineering, Ansan College of Technology, 671 Choji-Dong, Danwon-Gu, Ansan, 425-792 (Korea, Republic of); Lee, Sang Jin [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Ko, Tae Kuk [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

    2006-06-01

    A superconducting magnet which is operated in persistent current mode in SMES, NMR, MRI and MAGLEV has many advantages such as high uniformity of magnetic field and reduced thermal loss. A high temperature superconducting (HTS) persistent current switch (PCS) system was designed and tested in this research. The HTS PCS was optimally designed using two different HTS tapes, second generation coated conductor (CC) HTS tape and Bi-2223 HTS tape by the finite element method (FEM) in thermal quench characteristic view. The CC tape is more prospective applicable wire in these days for its high n value and critical current independency from external magnetic field than Bi-2223 tape. Also a prototype PCS system using Bi-2223 tape was manufactured and tested. The PCS system consists of a PCS part, a heater which induces the PCS to quench, and a superconducting magnet. The test was performed in various conditions of transport current. An initial current decay appeared when the superconducting magnet was energized in a PCS system was analyzed. This paper would be foundation of HTS PCS researches.

  3. The trend of the research and development for the upgrade of the high current energy system

    International Nuclear Information System (INIS)

    2010-01-01

    The high current energy technology ranges from a basic technology of the electric power field to a state-of-the-art technology and has been used extremely variously. In addition, as the energy technology advances, the expansion of applied field, such as the nuclear fusion and the exhaust thing processing, etc., requires a further upgrade of the large current technology. In this report, the trend of the research and development for the upgrade of the high current energy technology are summarized. In the following, the elemental technology including arc/plasma phenomena and the pulse power system is described in Chapter 2. In Chapter 3, the trend of the research and development for the upgrade of various equipments and devices such as the nuclear fusion development, the superconducting applications of SMES and the maglev transportation system, and the arc application of the exhaust processing for a medical waste, the radio active waste and a detrimental gas and the next generation lithography system. In Chapter 4, the analysis and the measurement technology of the arc phenomenon and the standardization of current shunt, etc are described. We hope this research report can contribute to the promotion of technical exchanges in different fields, and offer guidelines for future development in this high current energy technology. (author)

  4. High-performance supercapacitors using a nanoporous current collector made from super-aligned carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Ruifeng; Meng Chuizhou; Zhu Feng; Li Qunqing; Liu Changhong; Fan Shoushan; Jiang Kaili, E-mail: JiangKL@tsinghua.edu.cn [Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084 (China)

    2010-08-27

    Nanoporous current collectors for supercapacitors have been fabricated by cross-stacking super-aligned carbon nanotube (SACNT) films as a replacement for heavy conventional metallic current collectors. The CNT-film current collectors have good conductivity, extremely low density (27 {mu}g cm{sup -2}), high specific surface area, excellent flexibility and good electrochemical stability. Nanosized active materials such as NiO, Co{sub 3}O{sub 4} or Mn{sub 2}O{sub 3} nanoparticles can be directly synthesized on the SACNT films by a straightforward one-step, in situ decomposition strategy that is both efficient and environmentally friendly. These composite films can be integrated into a pseudo-capacitor that does not use metallic current collectors, but nevertheless shows very good performance, including high specific capacitance ({approx}500 F g{sup -1}, including the current collector mass), reliable electrochemical stability (<4.5% degradation in 2500 cycles) and a very high rate capability (245 F g{sup -1} at 155 A g{sup -1}).

  5. An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne; Lava, Val

    1994-08-01

    References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).

  6. HIGH-CURRENT COLD CATHODE FIELD EMISSION ARRAY FOR ELECTRON LENS APPLICATION

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L

    2012-12-28

    During Phase I, the following goals were achieved: (1) design and fabrication of a novel, nano-dimensional CNT field emitter assembly for high current density application, with high durability; (2) fabrication of a ceramic based micro channel plate (MCP) and characterization of its secondary electron emission; and (3) characterizing the CNT/MCP cathode for high field emission and durability. As a result of these achievements, a relatively high current density of ~ 1.2 A/cm2 from a CNT cathode and single channel MCP were measured. The emission current was also extremely stable with a peak-to-peak variation of only 1.8%. The emission current could be further enhanced to meet requirements for electron lens applications by increasing the number of MCP channels. A calculation for maximum possible current density with a 1200 channel/cm2 MCP, placed over a cathode with 1200 uniformly functioning CNTs, would be ~1.46 kA/cm2, neglecting space charge limitations. Clearly this level of emission is far greater than what is needed for the electron lens application, but it does offer a highly comforting margin to account for sub-standard emitters and/or to allow the lesser challenge of building a cathode with fewer channels/cm2. A satisfactory goal for the electron lens application would be a controllable emission of 2-4 mA per channel in an ensemble of 800-1200 uniformly-functioning channels/cm2, and a cathode with overall area of about 1 cm2.

  7. High voltage power supplies for ITER RF heating and current drive systems

    International Nuclear Information System (INIS)

    Gassmann, T.; Arambhadiya, B.; Beaumont, B.; Baruah, U.K.; Bonicelli, T.; Darbos, C.; Purohit, D.; Decamps, H.; Albajar, F.; Gandini, F.; Henderson, M.; Kazarian, F.; Lamalle, P.U.; Omori, T.; Parmar, D.; Patel, A.; Rathi, D.; Singh, N.P.

    2011-01-01

    The RF heating and current drive (H and CD) systems to be installed for the ITER fusion machine are the electron cyclotron (EC), ion cyclotron (IC) and, although not in the first phase of the project, lower hybrid (LH). These systems require high voltage, high current power supplies (HVPS) in CW operation. These HVPS should deliver around 50 MW electrical power to each of the RF H and CD systems with stringent requirements in terms of accuracy, voltage ripple, response time, turn off time and fault energy. The PSM (Pulse Step Modulation) technology has demonstrated over the past 20 years its ability to fulfill these requirements in many industrial facilities and other fusion reactors and has therefore been chosen as reference design for the IC and EC HVPS systems. This paper describes the technical specifications, including interfaces, the resulting constraints on the design, the conceptual design proposed for ITER EC and IC HVPS systems and the current status.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  9. Numerical calculation of high frequency fast wave current drive in a reactor grade tokamak

    International Nuclear Information System (INIS)

    Ushigusa, Kenkichi; Hamamatsu, Kiyotaka

    1988-02-01

    A fast wave current drive with a high frequency is estimated for a reactor grade tokamak by the ray tracing and the quasi-linear Fokker-Planck calculations with an assumption of single path absorption. The fast wave can drive RF current with the drive efficiency of η CD = n-bar e (10 19 m -3 )I RC (A)R(m)/P RF (W) ∼ 3.0 when the wave frequency is selected to be f/f ci > 7. A sharp wave spectrum and a ph|| >/υ Te ∼ 3.0 are required to obtain a good efficiency. A center peaked RF current profile can be formed with an appropriate wave spectrum even in the high temperature plasma. (author)

  10. Motion-induced eddy current thermography for high-speed inspection

    Directory of Open Access Journals (Sweden)

    Jianbo Wu

    2017-08-01

    Full Text Available This letter proposes a novel motion-induced eddy current based thermography (MIECT for high-speed inspection. In contrast to conventional eddy current thermography (ECT based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday’s law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

  11. Curious Case of Positive Current Collectors: Corrosion and Passivation at High Temperature.

    Science.gov (United States)

    Sayed, Farheen N; Rodrigues, Marco-Tulio F; Kalaga, Kaushik; Gullapalli, Hemtej; Ajayan, P M

    2017-12-20

    In the evaluation of compatibility of different components of cell for high-energy and extreme-conditions applications, the highly focused are positive and negative electrodes and their interaction with electrolyte. However, for high-temperature application, the other components are also of significant influence and contribute toward the total health of battery. In present study, we have investigated the behavior of aluminum, the most common current collector for positive electrode materials for its electrochemical and temperature stability. For electrochemical stability, different electrolytes, organic and room temperature ionic liquids with varying Li salts (LiTFSI, LiFSI), are investigated. The combination of electrochemical and spectroscopic investigations reflects the varying mechanism of passivation at room and high temperature, as different compositions of decomposed complexes are found at the surface of metals.

  12. A high-latitude, low-latitude boundary layer model of the convection current system

    International Nuclear Information System (INIS)

    Siscoe, G.L.; Lotko, W.; Sonnerup, B.U.O.

    1991-01-01

    Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer (∼1000 km), whereas thicknesses inferred from satellite data tend to be greater

  13. 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

  14. Application of Electron Bernstein Wave heating and current drive to high beta plasmas

    International Nuclear Information System (INIS)

    Efthimion, P.C.

    2002-01-01

    Electron Bernstein Waves (EBW) can potentially heat and drive current in high-beta plasmas. Electromagnetic waves can convert to EBW via two paths. O-mode heating, demonstrated on W-7AS, requires waves be launched within a narrow k-parallel range. Alternately, in high-beta plasmas, the X-mode cutoff and EBW conversion layers are millimeters apart, so the fast X-mode can tunnel to the EBW branch. We are studying the conversion of EBW to the X-mode by measuring the radiation temperature of the cyclotron emission and comparing it to the electron temperature. In addition, mode conversion has been studied with an approximate kinetic full-wave code. We have enhanced EBW mode conversion to ∼ 100% by encircling the antenna with a limiter that shortens the density scale length at the conversion layer in the scrape off of the CDX-U spherical torus (ST) plasma. Consequently, a limiter in front of a launch antenna achieves efficient X-mode coupling to EBW. Ray tracing and Fokker-Planck codes have been used to develop current drive scenarios in NSTX high-beta (∼ 40%) ST plasmas and a relativistic code will examine the potential synergy of EBW current drive with the bootstrap current. (author)

  15. 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)

  16. Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

    Science.gov (United States)

    Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.

    2017-12-01

    High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

  17. Characteristics of PEMFC operating at high current density with low external humidification

    International Nuclear Information System (INIS)

    Fan, Linhao; Zhang, Guobin; Jiao, Kui

    2017-01-01

    Highlights: • PEMFC with low humidity and high current density is studied by numerical simulation. • At high current density, water production lowers external humidification requirement. • A steady anode circulation status without external humidification is demonstrated. • The corresponding detailed internal water transfer path in the PEMFC is illustrated. • Counter-flow is superior to co-flow at low anode external humidification. - Abstract: A three-dimensional multiphase numerical model for proton exchange membrane fuel cell (PEMFC) is developed to study the fuel cell performance and water transport properties with low external humidification. The results show that the sufficient external humidification is necessary to prevent the polymer electrolyte dehydration at low current density, while at high current density, the water produced in cathode CL is enough to humidify the polymer electrolyte instead of external humidification by flowing back and forth between the anode and cathode across the membrane. Furthermore, a steady anode circulation status without external humidification is demonstrated in this study, of which the detailed internal water transfer path is also illustrated. Additionally, it is also found that the water balance under the counter-flow arrangement is superior to co-flow at low anode external humidification.

  18. Detection and clearing of trapped ions in the high current Cornell photoinjector

    Directory of Open Access Journals (Sweden)

    S. Full

    2016-03-01

    Full Text Available We have recently performed experiments to test the effectiveness of three ion-clearing strategies in the Cornell high intensity photoinjector: DC clearing electrodes, bunch gaps, and beam shaking. The photoinjector reaches a new regime of linac beam parameters where high continuous wave beam currents lead to ion trapping. Therefore ion mitigation strategies must be evaluated for this machine and other similar future high current linacs. We have developed several techniques to directly measure the residual trapped ions. Our two primary indicators of successful clearing are the amount of ion current removed by a DC clearing electrode, and the absence of bremsstrahlung radiation generated by beam-ion interactions. Measurements were taken for an electron beam with an energy of 5 MeV and continuous wave beam currents in the range of 1–20 mA. Several theoretical models have been developed to explain our data. Using them, we are able to estimate the clearing electrode voltage required for maximum ion clearing, the creation and clearing rates of the ions while employing bunch gaps, and the sinusoidal shaking frequency necessary for clearing via beam shaking. In all cases, we achieve a maximum ion clearing of at least 70% or higher, and in some cases our data is consistent with full ion clearing.

  19. Radiation of transient high-current arcs: energy measurements in the optical range

    International Nuclear Information System (INIS)

    Bauchire, J M; Hong, D; Rabat, H; Riquel, G

    2012-01-01

    When no protection is used, the radiation emitted by a high-power electric arc can be dangerous for the eyes and the skin of a person. To ensure effective protection, it is first necessary to know the energy emitted by such arcs. The aim of our work was to experimentally determine the energy emitted by high-current (from 4 to 40 kA) transient arcs, for two different (10 cm and 2 m) lengths and for electrodes in copper or steel. These experiments enabled the radiative energy of the arcs to be quantified and also showed the influence of metal vapors in the spectral distribution of the radiation.

  20. Migrational polarization in high-current density molten salt electrochemical devices

    Energy Technology Data Exchange (ETDEWEB)

    Braunstein, J.; Vallet, C.E.

    1977-01-01

    Electrochemical flux equations based on the thermodynamics of irreversible processes have been derived in terms of experimental transport coefficients for binary molten salt mixtures analogous to those proposed for high temperature batteries and fuel cells. The equations and some numerical solutions indicate steady state composition gradients of significant magnitude. The effects of migrational separation must be considered along with other melt properties in the characterization of electrode behavior, melt composition, operating temperatures and differences of phase stability, wettability and other physicochemical properties at positive and negative electrodes of high current density devices with mixed electrolytes.

  1. Improved High Current Liquid and Gas Targets for Cyclotron Produced Radioisotopes (Saudi Arabia)

    Energy Technology Data Exchange (ETDEWEB)

    Al Jammaz, Ibrahim; AlYanbawi, S.; Van-Heerden, W.; Miliebari, S.; Rahma, S.; Carrol, D. [King Faisal Specialist Hospital & Research Centre, Riyadh (Saudi Arabia)

    2009-07-01

    The development and improvement of target technology for reliable and higher production yields is described with respect to fluorine-18 and krypton-81. This report includes specific studies on: 1) beam degradation, distribution and diagnostic tools for monitoring the beam during irradiation; 2) targets that are capable of withstanding high current beam and consequently high specific activity radiopharmaceuticals; 3) greater understanding of in-target chemical and physical phenomena for the preparation of new radiolabeled species; and 4) recovery and characterization very expensive enriched material. (author)

  2. Microwave testing of high-Tc based direct current to a single flux quantum converter

    DEFF Research Database (Denmark)

    Kaplunenko, V. K.; Fischer, Gerd Michael; Ivanov, Z. G.

    1994-01-01

    Design, simulation, and experimental investigations of a direct current to a single flux quantum converter loaded with a Josephson transmission line and driven by an external 70 GHz microwave oscillator are reported. The test circuit includes nine YBaCuO Josephson junctions aligned on the grain...... boundary of a 0°–32° asymmetric Y-ZrO2 bicrystal substrate. The performance of such converters is important for the development of the fast Josephson samplers required for testing of high-Tc rapid single flux quantum circuits in high-speed digital superconducting electronics. Journal of Applied Physics...

  3. Improved High Current Liquid and Gas Targets for Cyclotron Produced Radioisotopes (Saudi Arabia)

    International Nuclear Information System (INIS)

    Al Jammaz, Ibrahim; AlYanbawi, S.; Van-Heerden, W.; Miliebari, S.; Rahma, S.; Carrol, D.

    2009-01-01

    The development and improvement of target technology for reliable and higher production yields is described with respect to fluorine-18 and krypton-81. This report includes specific studies on: 1) beam degradation, distribution and diagnostic tools for monitoring the beam during irradiation; 2) targets that are capable of withstanding high current beam and consequently high specific activity radiopharmaceuticals; 3) greater understanding of in-target chemical and physical phenomena for the preparation of new radiolabeled species; and 4) recovery and characterization very expensive enriched material. (author)

  4. Simple laser-driven, metal photocathodes as cold, high-current electron sources

    International Nuclear Information System (INIS)

    Saunders, J.D.; Ringler, T.J.; Builta, L.A.; Kauppila, T.J.; Moir, D.C.; Downey, S.W.

    1987-01-01

    Recent developments in excimer laser design have made near ultraviolet light intensities of several MWcm 2 possible in unfocused beams. These advances and recent experiments indicate that high-current, simple-metal photoemissive electron guns are now feasible. Producing more than 50 Acm 2 of illuminated cathode surface, the guns could operate at vacuums of 10 -6 torr with no complicated system components inside the vacuum enclosure. The electron beam produced by such photoemission guns would have very low emittance and high brightness. This beam would also closely follow the temporal characteristics of the laser pulse, making fast risetime, ultrashort electron beam pulses possible

  5. Sparking limits, cavity loading, and beam breakup instability associated with high-current rf linacs

    International Nuclear Information System (INIS)

    Faehl, R.J.; Lemons, D.S.; Thode, L.E.

    1982-01-01

    The limitations on high-current rf linacs due to gap sparking, cavity loading, and the beam breakup instability are studied. It appears possible to achieve cavity accelerating gradients as high as 35 MV/m without sparking. Furthermore, a linear analysis, as well as self-consistent particle simulations of a multipulsed 10 kA beam, indicated that only a negligible small fraction of energy is radiated into nonfundamental cavity modes. Finally, the beam breakup instability is analyzed and found to be able to magnify initial radial perturbations by a factor of no more than about 20 during the beam transit time through a 1 GeV accelerator

  6. High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod

    Science.gov (United States)

    Tinguely, R. A.; Granetz, R. S.; Berg, A.; Kuang, A. Q.; Brunner, D.; LaBombard, B.

    2018-01-01

    Halo currents generated during disruptions on Alcator C-Mod have been measured with Langmuir ‘rail’ probes. These rail probes are embedded in a lower outboard divertor module in a closely-spaced vertical (poloidal) array. The dense array provides detailed resolution of the spatial dependence (~1 cm spacing) of the halo current distribution in the plasma scrape-off region with high time resolution (400 kHz digitization rate). As the plasma limits on the outboard divertor plate, the contact point is clearly discernible in the halo current data (as an inversion of current) and moves vertically down the divertor plate on many disruptions. These data are consistent with filament reconstructions of the plasma boundary, from which the edge safety factor of the disrupting plasma can be calculated. Additionally, the halo current ‘footprint’ on the divertor plate is obtained and related to the halo flux width. The voltage driving halo current and the effective resistance of the plasma region through which the halo current flows to reach the probes are also investigated. Estimations of the sheath resistance and halo region resistivity and temperature are given. This information could prove useful for modeling halo current dynamics.

  7. A high linearity current mode second IF CMOS mixer for a DRM/DAB receiver

    International Nuclear Information System (INIS)

    Xu Jian; Zhou Zheng; Wu Yiqiang; Wang Zhigong; Chen Jianping

    2015-01-01

    A passive current switch mixer was designed for the second IF down-conversion in a DRM/DAB receiver. The circuit consists of an input transconductance stage, a passive current switching stage, and a current amplifier stage. The input transconductance stage employs a self-biasing current reusing technique, with a resistor shunt feedback to increase the gain and output impedance. A dynamic bias technique is used in the switching stage to ensure the stability of the overdrive voltage versus the PVT variations. A current shunt feedback is introduced to the conventional low-voltage second-generation fully balanced multi-output current converter (FBMOCCII), which provides very low input impedance and high output impedance. With the circuit working in current mode, the linearity is effectively improved with low supply voltages. Especially, the transimpedance stage can be removed, which simplifies the design considerably. The design is verified with a SMIC 0.18 μm RF CMOS process. The measurement results show that the voltage conversation gain is 1.407 dB, the NF is 16.22 dB, and the IIP3 is 4.5 dBm, respectively. The current consumption is 9.30 mA with a supply voltage of 1.8 V. This exhibits a good compromise among the gain, noise, and linearity for the second IF mixer in DRM/DAB receivers. (paper)

  8. Anodic Oxidation of Carbon Steel at High Current Densities and Investigation of Its Corrosion Behavior

    Science.gov (United States)

    Fattah-Alhosseini, Arash; Khan, Hamid Yazdani

    2017-06-01

    This work aims at studying the influence of high current densities on the anodization of carbon steel. Anodic protective coatings were prepared on carbon steel at current densities of 100, 125, and 150 A/dm2 followed by a final heat treatment. Coatings microstructures and morphologies were analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). The corrosion resistance of the uncoated carbon steel substrate and the anodic coatings were evaluated in 3.5 wt pct NaCl solution through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results showed that the anodic oxide coatings which were prepared at higher current densities had thicker coatings as a result of a higher anodic forming voltage. Therefore, the anodized coatings showed better anti-corrosion properties compared to those obtained at lower current densities and the base metal.

  9. High-current negative hydrogen ion beam production in a cesium-injected multicusp source

    International Nuclear Information System (INIS)

    Takeiri, Y.; Tsumori, K.; Kaneko, O.

    1997-01-01

    A high-current negative hydrogen ion source has been developed, where 16.2 A of the H - current was obtained with a current density of 31 mA/cm 2 . The ion source is a multicusp source with a magnetic filter for negative ion production, and cesium vapor is injected into the arc chamber, leading to enhancement of the negative ion yields. The cesium-injection effects are discussed, based on the experimental observations. Although the surface production of the negative ions on the cesium-covered plasma grid is thought to be a dominant mechanism of the H - current enhancement, the cesium effects in the plasma volume, such as the cesium ionization and the electron cooling, are observed, and could contribute to the improved operation of the negative ion source. (author)

  10. High performance current and spin diode of atomic carbon chain between transversely symmetric ribbon electrodes.

    Science.gov (United States)

    Dong, Yao-Jun; Wang, Xue-Feng; Yang, Shuo-Wang; Wu, Xue-Mei

    2014-08-21

    We demonstrate that giant current and high spin rectification ratios can be achieved in atomic carbon chain devices connected between two symmetric ferromagnetic zigzag-graphene-nanoribbon electrodes. The spin dependent transport simulation is carried out by density functional theory combined with the non-equilibrium Green's function method. It is found that the transverse symmetries of the electronic wave functions in the nanoribbons and the carbon chain are critical to the spin transport modes. In the parallel magnetization configuration of two electrodes, pure spin current is observed in both linear and nonlinear regions. However, in the antiparallel configuration, the spin-up (down) current is prohibited under the positive (negative) voltage bias, which results in a spin rectification ratio of order 10(4). When edge carbon atoms are substituted with boron atoms to suppress the edge magnetization in one of the electrodes, we obtain a diode with current rectification ratio over 10(6).

  11. 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

  12. 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

  13. Progressive current degradation and breakdown behavior in GaN LEDs under high reverse bias stress

    International Nuclear Information System (INIS)

    Zhao Linna; Yu Peihong; Yan Dawei; Zhou Hao; Wu Jinbo; Cui Zhiqiang; Gu Xiaofeng; Guo Zixiang; Sun Huarui

    2017-01-01

    The progressive current degradation and breakdown behaviors of GaN-based light emitting diodes under high reverse-bias stress are studied by combining the electrical, optical, and surface morphology characterizations. The current features a typical “soft breakdown” behavior, which is linearly correlated to an increase of the accumulative number of electroluminescence spots. The time-to-failure for each failure site approximately obeys a Weibull distribution with slopes of about 0.67 and 4.09 at the infant and wear-out periods, respectively. After breakdown, visible craters can be observed at the device surface as a result of transient electrostatic discharge. By performing focused ion beam cuts coupled with scan electron microscope, we observed a local current shunt path in the surface layer, caused by the rapid microstructure deterioration due to significant current heating effect, consistent well with the optical beam induced resistance change observations. (paper)

  14. High current density M-type cathodes for vacuum electron devices

    International Nuclear Information System (INIS)

    Li Ji; Yu Zhiqiang; Shao Wensheng; Zhang Ke; Gao Yujuan; Yuan Haiqing; Wang Hui; Huang Kaizhi; Chen Qilue; Yan Suqiu; Cai Shaolun

    2005-01-01

    We investigated high current density emission capabilities of M-type cathodes used for vacuum electron devices (VEDs). The experimental results of emission and lifetime evaluating in both close-spaced diode structure and electron gun testing vehicles are given. Emission current densities measured in the diode structure at 1020 deg. C Br in the CW mode were above 10 A/cm 2 ; while in electron gun testing vehicles, emission current densities were above 8 A/cm 2 in CW mode and above 32 A/cm 2 in pulsed mode, respectively. The current density above 94 A/cm 2 has been acquired in no. 0306 electron gun vehicle while the practical temperature is 1060 deg. C Br . For a comparison some of the data from I-scandate cathodes are presented. Finally, several application examples in practical travelling wave tubes (TWTs) and multi beam klystrons (MBKs) are also reported

  15. Run-away electrons and plasma pinching in a high-current diode

    International Nuclear Information System (INIS)

    Ivanenkov, G.V.

    1984-01-01

    The electrons run-away process in space-confined plasma with current is considered. It has been found that the effect of the proper magnetic field of a current leads to appearance, in add tion to the Dreicer mechanism, of other run-away mechanism in the process of radial oscillations of electrons accelerating near the axis. The appearance of run-away electrons from a thermal velocities region occurs in the course of collisions as well as radial drift. The thresholds of Dreicer run-away and drift are determined. The conditions of formation of Z-pinch current envelope and its collisionless compression by the ''snow plough'' type for the 10-100 ns of high-current accelerator pulse duration are elucidated

  16. Conceptual design of current lead for large scale high temperature superconducting rotating machine

    International Nuclear Information System (INIS)

    Le, T. D.; Kim, J. H.; Park, S. I.; Kim, H. M.

    2014-01-01

    High-temperature superconducting (HTS) rotating machines always require an electric current of from several hundreds to several thousand amperes to be led from outside into cold region of the field coil. Heat losses through the current leads then assume tremendous importance. Consequently, it is necessary to acquire optimal design for the leads which would achieve minimum heat loss during operation of machines for a given electrical current. In this paper, conduction cooled current lead type of 10 MW-Class HTS rotating machine will be chosen, a conceptual design will be discussed and performed relied on the least heat lost estimation between conventional metal lead and partially HTS lead. In addition, steady-state thermal characteristic of each one also is considered and illustrated.

  17. Filtering and Control of High Speed Motor Current in a Flywheel Energy Storage System

    Science.gov (United States)

    Kenny, Barbara H.; Santiago, Walter

    2004-01-01

    The NASA Glenn Research Center has been developing technology to enable the use of high speed flywheel energy storage units in future spacecraft for the last several years. An integral part of the flywheel unit is the three phase motor/generator that is used to accelerate and decelerate the flywheel. The motor/generator voltage is supplied from a pulse width modulated (PWM) inverter operating from a fixed DC voltage supply. The motor current is regulated through a closed loop current control that commands the necessary voltage from the inverter to achieve the desired current. The current regulation loop is the innermost control loop of the overall flywheel system and, as a result, must be fast and accurate over the entire operating speed range (20,000 to 60,000 rpm) of the flywheel. The voltage applied to the motor is a high frequency PWM version of the DC bus voltage that results in the commanded fundamental value plus higher order harmonics. Most of the harmonic content is at the switching frequency and above. The higher order harmonics cause a rapid change in voltage to be applied to the motor that can result in large voltage stresses across the motor windings. In addition, the high frequency content in the motor causes sensor noise in the magnetic bearings that leads to disturbances for the bearing control. To alleviate these problems, a filter is used to present a more sinusoidal voltage to the motor/generator. However, the filter adds additional dynamics and phase lag to the motor system that can interfere with the performance of the current regulator. This paper will discuss the tuning methodology and results for the motor/generator current regulator and the impact of the filter on the control. Results at speeds up to 50,000 rpm are presented.

  18. High beam current shut-off systems in the APS linac and low energy transfer line

    International Nuclear Information System (INIS)

    Wang, X.; Knott, M.; Lumpkin, A.

    1994-01-01

    Two independent high beam current shut-off current monitoring systems (BESOCM) have been installed in the APS linac and the low energy transport line to provide personnel safety protection in the event of acceleration of excessive beam currents. Beam current is monitored by a fast current transformer (FCT) and fully redundant supervisory circuits connected to the Access Control Interlock System (ACIS) for beam intensity related shutdowns of the linac. One FCT is located at the end of the positron linac and the other in the low energy transport line, which directs beam to the positron accumulator ring (PAR). To ensure a high degree of reliability, both systems employ a continuous self-checking function, which injects a test pulse to a single-turn test winding after each ''real'' beam pulse to verify that the system is fully functional. The system is designed to be fail-safe for all possible system faults, such as loss of power, open or shorted signal or test cables, loss of external trigger, malfunction of gated integrator, etc. The system has been successfully commissioned and is now a reliable part of the total ACIS

  19. RF heating and current drive on NSTX with high harmonic fast waves

    International Nuclear Information System (INIS)

    Ryan, P.M.; Swain, D.W.; Rosenberg, A.L.

    2003-01-01

    NSTX is a small aspect ratio tokamak (R = 0.85 m, a = 0.65 m). The High Harmonic Fast Wave (HHFW) system is a 30 MHz, 12-element array capable of launching both symmetric and directional wave spectra for plasma heating and non-inductive current drive. It has delivered up to 6 MW for short pulses and has routinely operated at ∼3 MW for 100-400 ms pulses. Results include strong, centrally-peaked electron heating in both D and He plasmas for both high and low phase velocity spectra. H-modes were obtained with application of HHFW power alone, with stored energy doubling after the L-H transition. Beta poloidal as large as unity has been obtained with significant fractions (0.4) of bootstrap current. Differences in the loop voltage are observed depending on whether the array is phased to drive current in the co- or counter-current directions. A fast ion tail with energies extending up to 140 keV has been observed when HHFW interacts with 80 keV neutral beams; neutron rate and lost ion measurements, as well as modeling, indicate significant power absorption by the fast ions. Radial rf power deposition and driven current profiles have been calculated with ray tracing and kinetic full-wave codes and compared with measurements. (author)

  20. High current electron beam acceleration in dielectric-filled RF cavities

    International Nuclear Information System (INIS)

    Faehl, R.J.; Keinigs, R.K.

    1996-01-01

    The acceleration of charged particles in radio frequency (RF) cavities is a widely used mode in high energy accelerators. Advantages include very high accelerating gradients and very stable phase control. A traditional limitation for such acceleration has been their use for intense, high current beam generation. This constraint arises from the inability to store a large amount of electromagnetic energy in the cavity and from loading effects of the beam on the cavity. The authors have studied a simple modification to transcend these limitations. Following Humphries and Huang, they have conducted analytic and numerical investigations of RF accelerator cavities in which a high dielectric constant material, such as water, replaces most of the cavity volume. This raises the stored energy in a cavity of given dimensions by a factor var-epsilon/var-epsilon 0 . For a water fill, var-epsilon/var-epsilon 0 ∼ 80, depending on the frequency. This introduction of high dielectric constant material into the cavity reduces the resonant frequencies by a factor of (var-epsilon/var-epsilon 0 ) 1/2 . This reduced operating frequency mans that existing high efficiency power supplies, at lower frequencies, can be used for an accelerator

  1. Design of a high-temperature superconductor current lead for electric utility SMES

    International Nuclear Information System (INIS)

    Niemann, R.C.; Cha, Y.S.; Hull, J.R.; Rey, C.M.; Dixon, K.D.

    1995-01-01

    Current leads that rely on high-temperature superconductors (HTSs) to deliver power to devices operating at liquid helium temperature have the potential to reduce refrigeration requirements to levels significantly below those achievable with conventional leads. The design of HTS current leads suitable for use in near-term superconducting magnetic energy storage (SMES) is in progress. The SMES system has an 0.5 MWh energy capacity and a discharge power of 30 MW. Lead-design considerations include safety and reliability, electrical and thermal performance, structural integrity, manufacturability, and cost. Available details of the design, including materials, configuration, and performance predictions, are presented

  2. Effect of welding current and speed on occurrence of humping bead in high-speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Chen Ji; Wu Chuansong

    2009-01-01

    The developed mathematical model of humping formation mechanism in high-speed gas metal arc welding (GMAW) is used to analyze the effects of welding current and welding speed on the occurrence of humping bead. It considers both the momentum and heat content of backward flowing molten jet inside weld pool. Three-dimensional geometry of weld pool, the spacing between two adjacent humps and hump height along humping weld bead are calculated under different levels of welding current and welding speed. It shows that wire feeding rate, power intensity and the moment of backward flowing molten jet are the major factors on humping bead formation.

  3. A simulation study on burning profile tailoring of steady state, high bootstrap current tokamaks

    International Nuclear Information System (INIS)

    Nakamura, Y.; Takei, N.; Tobita, K.; Sakamoto, Y.; Fujita, T.; Fukuyama, A.; Jardin, S.C.

    2007-01-01

    From the aspect of fusion burn control in steady state DEMO plant, the significant challenges are to maintain its high power burning state of ∝3-5 GW without burning instability, hitherto well-known as ''thermal stability'', and also to keep its desired burning profile relevant with internal transport barrier (ITB) that generates high bootstrap current. The paper presents a simulation modeling of the burning stability coupled with the self-ignited fusion burn and the structure-formation of the ITB. A self-consistent simulation, including a model for improved core energy confinement, has pointed out that in the high power fusion DEMO plant there is a close, nonlinear interplay between the fusion burnup and the current source of non-inductive, ITB-generated bootstrap current. Consequently, as much distinct from usual plasma controls under simulated burning conditions with lower power (<<1 GW), the selfignited fusion burn at a high power burning state of ∝3-5 GW becomes so strongly selforganized that any of external means except fuelling can not provide the effective control of the stable fusion burn.It is also demonstrated that externally applied, inductive current perturbations can be used to control both the location and strength of ITB in a fully noninductive tokamak discharge. We find that ITB structures formed with broad noninductive current sources such as LHCD are more readily controlled than those formed by localized sources such as ECCD. The physics of the inductive current is well known. Consequently, we believe that the controllability of the ITB is generic, and does not depend on the details of the transport model (as long as they can form an ITB for sufficiently reversed magnetic shear q-profile). Through this external control of the magnetic shear profile, we can maintain the ITB strength that is otherwise prone to deteriorate when the bootstrap current increases. These distinguishing capabilities of inductive current perturbation provide steady

  4. Transient characteristics of current lead losses for the large scale high-temperature superconducting rotating machine

    International Nuclear Information System (INIS)

    Le, T. D.; Kim, J. H.; Park, S. I.; Kim, D. J.; Kim, H. M.; Lee, H. G.; Yoon, Y. S.; Jo, Y. S.; Yoon, K. Y.

    2014-01-01

    To minimize most heat loss of current lead for high-temperature superconducting (HTS) rotating machine, the choice of conductor properties and lead geometry - such as length, cross section, and cooling surface area - are one of the various significant factors must be selected. Therefore, an optimal lead for large scale of HTS rotating machine has presented before. Not let up with these trends, this paper continues to improve of diminishing heat loss for HTS part according to different model. It also determines the simplification conditions for an evaluation of the main flux flow loss and eddy current loss transient characteristics during charging and discharging period.

  5. Improvement of automatic control system for high-speed current collectors

    Science.gov (United States)

    Sidorov, O. A.; Goryunov, V. N.; Golubkov, A. S.

    2018-01-01

    The article considers the ways of regulation of pantographs to provide quality and reliability of current collection at high speeds. To assess impact of regulation was proposed integral criterion of the quality of current collection, taking into account efficiency and reliability of operation of the pantograph. The study was carried out using mathematical model of interaction of pantograph and catenary system, allowing to assess contact force and intensity of arcing at the contact zone at different movement speeds. The simulation results allowed us to estimate the efficiency of different methods of regulation of pantographs and determine the best option.

  6. Experimental study of collective effects in BEP storage ring with high stored current

    International Nuclear Information System (INIS)

    Danilov, V.; Koop, I.; Lysenko, A.; Militsyn, B.; Nesterenko, I.; Perevedentsev, E.; Pozdeev, E.; Ptitsin, V.; Shatunov, Yu.; Vasserman, I.

    1993-01-01

    The results of extensive investigation of beam dynamics with high current in BEP booster are presented. Strong bunch lengthening due to the potential well distortion by the inductive impedance was observed on the background of the multiple intrabeam scattering and of the ion accumulation (in the e - beam). The octupole and sextupole corrections enabled control of collective damping of the head-tail modes. Fast damping is also observed at zero chromaticity, this is attributed to the injection kickers acting as transmission lines. The proper tuning of the nonlinearity corrections cures the transverse instabilities and enables capability to store up to 0.8A current in a single bunch

  7. Observation of a very high electron current extraction mode in a hollow cathode discharge

    International Nuclear Information System (INIS)

    Hershcovitch, A.

    1993-01-01

    Earlier results by Hershcovitch, Kovarik, and Prelec in J. Appl. Phys. 67, 671 (1990) proved that, in a low-pressure operating mode, hollow cathode discharges can have a two-component electron population, one of which is that of ''fast'' electrons having an energy corresponding to the cathode potential and a thermal spread of about 0.13 eV, which could form a basis for an excellent electron gun. Investigations of extracted electron currents in this low pressure mode indicate the existence of a narrow pressure range characterized by very high electron current extraction

  8. High current relativistic beam propagates stably in gas surrounded by nonconducting walls

    International Nuclear Information System (INIS)

    Clark, J.C.

    1977-01-01

    LLL has been studying the propagation of high current electron beams for a number of years to understand their behavior for use in a variety of experimental uses. Our latest experiments have shown that a mildly relativistic electron beam of 10 to 15 kA and a pulse width of 30 to 40 ns can propagate stably and with no net current transfer in insulating tubes filled with neutral gases. These experiments have been performed in the Magnetic Fusion Energy program where Electronics Engineering has been operating an electron beam accelerator, designing some of the diagnostics, such as laser interferometers, and performing the experiments. This article briefly describes our experimental observations

  9. Progress on the high-current 704 MHz superconducting RF cavity at BNL

    International Nuclear Information System (INIS)

    Xu, W.; Astefanous, C.; Belomestnykh, S.; Ben-Zvi, I.

    2012-01-01

    The 704 MHz high current superconducting cavity has been designed with consideration of both performance of fundamental mode and damping of higher order modes. A copper prototype cavity was fabricated by AES and delivered to BNL. RF measurements were carried out on this prototype cavity, including fundamental pass-band and HOM spectrum measurements, HOM studies using bead-pull setup, prototyping of antenna-type HOM couplers. The measurements show that the cavity has very good damping for the higher-order modes, which was one of the main goals for the high current cavity design. 3D cavity models were simulated with Omega3P code developed by SLAC to compare with the measurements. The paper describes the cavity design, RF measurement setups and results for the copper prototype. The progress with the niobium cavity fabrication will also be described.

  10. Establishment of design space for high current gain in III-N hot electron transistors

    Science.gov (United States)

    Gupta, Geetak; Ahmadi, Elaheh; Suntrup, Donald J., III; Mishra, Umesh K.

    2018-01-01

    This paper establishes the design space of III-N hot electron transistors (HETs) for high current gain by designing and fabricating HETs with scaled base thickness. The device structure consists of GaN-based emitter, base and collector regions where emitter and collector barriers are implemented using AlN and InGaN layers, respectively, as polarization-dipoles. Electrons tunnel through the AlN layer to be injected into the base at a high energy where they travel in a quasi-ballistic manner before being collected. Current gain increases from 1 to 3.5 when base thickness is reduced from 7 to 4 nm. The extracted mean free path (λ mfp) is 5.8 nm at estimated injection energy of 1.5 eV.

  11. Morphological features of the copper surface layer under sliding with high density electric current

    Energy Technology Data Exchange (ETDEWEB)

    Fadin, V. V., E-mail: fvv@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Aleutdinova, M. I., E-mail: aleut@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Seversk Technological Institute, Branch of State Autonomous Educational Institution of Higher Professional Education “National Research Nuclear University “MEPhI”, Seversk, 636036 (Russian Federation); Rubtsov, V. Ye., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Aleutdinova, V. A., E-mail: valery-aleut@yandex.ru [National Research St. Petersburg State Polytechnical University, St. Petersburg, 195251 (Russian Federation)

    2015-10-27

    Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm{sup 2} are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.

  12. 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.

  13. Critical currents and superconductivity ferromagnetism coexistence in high-Tc oxides

    CERN Document Server

    Khene, Samir

    2016-01-01

    The book comprises six chapters which deal with the critical currents and the ferromagnetism-superconductivity coexistence in high-Tc oxides. It begins by gathering key data for superconducting state and the fundamental properties of the conventional superconductors, followed by a recap of the basic theories of superconductivity. It then discusses the differences introduced by the structural anisotropy on the Ginzburg-Landau approach and the Lawrence-Doniach model before addressing the dynamics of vortices and the ferromagnetism-superconductivity coexistence in high-Tc oxides, and provides an outline of the pinning phenomena of vortices in these materials, in particular the pinning of vortices by the spins. It elucidates the methods to improve the properties of superconducting materials for industrial applications. This optimization aims at obtaining critical temperatures and densities of critical currents at the maximum level possible. Whereas the primary objective is the basic mechanisms pushing the superco...

  14. A battery-powered high-current power supply for superconductors

    CERN Document Server

    Wake, M; Suda, K

    2002-01-01

    Since superconductors do not require voltages, a high-current power supply could run with low power if the voltage is sufficiently reduced. Even a battery-powered power supply could give as much as 2,000A for a superconductor. To demonstrate this hypothesis, a battery-powered 2,000A power supply was constructed. It uses an IGBT chopper and Schottky diode together with a specially arranged transformer to produce a high current with low voltage. Testing of 2,000A operation was performed for about 1.5 hr using 10 car batteries. Charging time for this operation was 8 hr. Ramping control was smooth and caused no trouble. Although the IGBT frequency ripple of 16.6 kHz was easily removed using a passive filter, spike noise remained in the output voltage. This ripple did not cause any trouble in operating a pancake-type inductive superconducting load. (author)

  15. Visualisation of the high-current e-beams on solid surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, V I; Osipov, V V; Mikhajlov, S G; Lipchak, A I [Russian Academy of Sciences, Ural Division, Ekaterinburg (Russian Federation). Institute of Electrophysics

    1997-12-31

    Natural minerals such as spodumen, calcite, and Mn-doped apatite crystals may serve as suitable low-cost materials for visualization of high-current electron beams. High-intensity luminescence lasting several tens of minutes has been observed when irradiating natural specimen by electron beams with the current density of 10-1000 A/sq.cm, with energy of 100-300 keV, and pulse duration of 2-50 ns. The luminescent images of the beam cross-section provide information on the beam density profiles, while the images taken in the plane parallel to the beam axis make it possible to estimate the beam penetration depth and, therefore, the beam energy. The method is illustrated by examples of luminescent images taken from the experiment. (J.U.).

  16. Confinement studies of a high current density RFP in the Extrap T1 Upgrade device

    International Nuclear Information System (INIS)

    Drake, J.R.; Brzozowski, J.H.; Brunsell, P.; Hellblom, G.; Karlsson, P.; Mazur, S.; Nordlund, P.; Welander, A.; Zastrow, K.D.

    1992-01-01

    Confinement studies have been carried out on the Extrap T1 device operated in the reversed field pinch (RFP) mode. Extrap T1 is a small device with a major radius of R=0.5 m and a high aspect ratio, R/a=8.9. For these experiments, the device has been operated with a resistive shell with measured, toroidally-averaged flux penetration times of τ sv = 500μs (vertical) and τ sR =300μs (radial). The pulse lengths are about 600 μs, which is slightly longer than the shell penetration time. The purpose of these experiments is to study energy confinement in a high aspect-ratio, high current-density RFP device with a resistive shell. The device can be operated with high current densities which exceed 20 MAm -2 on axis. For these discharges, the average electron density is relatively high, ≅ 1x10 20 m -3 . Therefore, although the average current density exceeds 5 MAm -2 , the important parameter / ≅ I/N is maintained less than 1x10 -13 Am, where N is the line density. The plasma diagnostics for the device include a single chord CO 2 laser interferometer ( ), single point Thomson scattering (T e , n o ), VUV and visible spectroscopy (T e , Z eff ) surface barrier diodes for soft X-ray measurements (T e ), bolometry (P rad ), surface probes (Γ p ,T i ) and comprehensive magnetic diagnostics for both equilibrium and magnetic fluctuation studies. (author) 5 refs., 1 fig., 1 tab

  17. Effects of Birkeland current limitation on high-latitude convection patterns

    International Nuclear Information System (INIS)

    Marklund, G.T.; Raadu, M.A.; Lindqvist, P.-A.

    1984-12-01

    It is shown how the high-latitude convection pattern may be mo- dified by substorm-enhanced polarization electric fields. These are generated whenever the flow of those Birkeland currents which are associated with ionospheric conductivity gradients is limited. Such Birkeland currents are fed mainly by the enhanced Pedersen current in the evening and morning sectors of the auro- ral oval and by the enhanced Hall current around local midnight. As the current limitation increases, the ionospheric potential, represented here by a symmetric two-cell pattern, will rotate clockwise and deform, just as the associated Birkeland current distribution. The resulting patterns are shown to agree well with observations. A pronounced westward intrusion of the equi- potential contours occurs in the auroral oval, and may be asso- ciated with the Westward Travelling Surge. This feature does not however require any assumed longitudinal conductivity gradi- ents. Rather it falls out naturally when the limitation of the enhanced Pedersen current is taken into account. (Author)

  18. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinzhen; Li, Gang; Lin, Ling, E-mail: linling@tju.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People' s Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin (China); Qiao, Xiaoyan [College of Physics and Electronic Engineering, Shanxi University, Shanxi (China); Wang, Mengjun [School of Information Engineering, Hebei University of Technology, Tianjin (China); Zhang, Weibo [Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing (China)

    2014-05-15

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  19. Magnetic insulation regimes in high-current diodes and transmission lines of conical configuration

    International Nuclear Information System (INIS)

    Vasilenko, O.I.; Voronin, V.S.; Lebedev, A.N.

    1977-01-01

    Steady states of the electron current in a high-voltage diode and of the transmission line of conical configuration at emission current restriction by the space are considered on the basis of the self-consistant kinetic description in connection with the prospects of controlled thermonuclear synthesis. Proceeding from the magnetic self-insulation principle solved are the problems of controling the emission electron current in the double-electron geometry to prevent it from being present on the anode in the line regime and to achieve its maximum focusing in the diode regime. The motion of plasma boundaries as well as the probable contribution of the ion component of the current were not taken into consideration. It is shown that the beam focusing on the system axis takes place at sufficiently strong currents. It is connected with the fact that some part of the full diode current runs on the cathode surface. The results were compared with existing approximate diode models and with the experimetal data on focusien of strong-current beams

  20. Enhanced D-T supershot performance at high current using extensive lithium conditioning in TFTR

    International Nuclear Information System (INIS)

    Mansfield, D.K.; Strachan, J.D.; Bell, M.G.; Scott, S.D.; Budny, R.; Bell, R.E.; Bitter, M.; Darrow, D.S.; Fredrickson, E.; Grek, B.

    1995-05-01

    A substantial improvement in supershot fusion plasma performance has been realized by combining the enhanced confinement due to tritium fueling with the enhanced confinement due to extensive Li conditioning of the TFTR limiter. This combination has resulted in not only significantly higher global energy confinement times than had previously been obtained in high current supershots, but also the highest ratio of central fusion output power to input power observed to date

  1. Real time data acquisition system for the High Current Test Facility proton accelerator

    International Nuclear Information System (INIS)

    Langlais, C.E.; Erickson, P.D.; Caissie, L.P.

    1975-01-01

    A real time data acquisition system was developed to monitor and control the High Current Test Facility Proton Accelerator. It is a PDP-8/E computer system with virtual memory capability that is fully interrupt driven and operates under a real-time, multi-tasking executive. The application package includes mode selection to automatically modify programs and optimize operation under varying conditions. (U.S.)

  2. Simulation of electron and ion bipolar flow in high current diode with magnetic insulation

    International Nuclear Information System (INIS)

    Vrba, P.; Engelko, V.I.

    1990-08-01

    Numerical simulation of the formation of the collector ion flow in a magnetically insulated ion diode (MID) with a hollow cylindrical and cone-shaped cathode was studied. Such cathodes are often used for the production of tubular high current microsecond electron beams. The ions, emitted by the collector and born as a result of ionization of the residual gas by the electron beam, are focused into the cathode plasma region. This effect can adversely influence the diode operation

  3. The charge deposition in the numerical simulation of high-current beam

    International Nuclear Information System (INIS)

    Wang Shijun

    1987-01-01

    A new method of charge deposition of high-current beam, conservation-map method, is given. THe advantages of Neil's and other various methods are adopted. The mistake of Neil's method and the limitation of other various methods is discarded. So the method is accurate without additional assumption. The method not only applies to the case of steady laminar flow but also applies to the case of steady non-laminar flow

  4. The Effect of Twins on Critical Currents of High Tc Superconductors

    Science.gov (United States)

    1989-01-01

    particles to stick together due to electrostatic forces. To overcome this we have formed a slurry of the material in liquid nitrogen and flash...can use and the liquid convection tends to counteract the separation process. We have-now designed a magnetic track which particles will slide down with...Currents of High Tc Superconductors" - A.M. Campbell and M.F. Ashby The initial work on levitation forces and separation of superconducting powders has

  5. Characterisation Of The Beam Plasma In High Current, Low Energy Ion Beams For Implanters

    International Nuclear Information System (INIS)

    Fiala, J.; Armour, D. G.; Berg, J. A. van der; Holmes, A. J. T.; Goldberg, R. D.; Collart, E. H. J.

    2006-01-01

    The effective transport of high current, positive ion beams at low energies in ion implanters requires the a high level of space charge compensation. The self-induced or forced introduction of electrons is known to result in the creation of a so-called beam plasma through which the beam propagates. Despite the ability of beams at energies above about 3-5 keV to create their own neutralising plasmas and the development of highly effective, plasma based neutralising systems for low energy beams, very little is known about the nature of beam plasmas and how their characteristics and capabilities depend on beam current, beam energy and beamline pressure. These issues have been addressed in a detailed scanning Langmuir probe study of the plasmas created in beams passing through the post-analysis section of a commercial, high current ion implanter. Combined with Faraday cup measurements of the rate of loss of beam current in the same region due to charge exchange and scattering collisions, the probe data have provided a valuable insight into the nature of the slow ion and electron production and loss processes. Two distinct electron energy distribution functions are observed with electron temperatures ≥ 25 V and around 1 eV. The fast electrons observed must be produced in their energetic state. By studying the properties of the beam plasma as a function of the beam and beamline parameters, information on the ways in which the plasma and the beam interact to reduce beam blow-up and retain a stable plasma has been obtained

  6. 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.

  7. 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

  8. 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.

  9. Quasistationary model of high-current relativistic electron beam. 1. Exact solution of Poisson equations

    International Nuclear Information System (INIS)

    Brenner, S.E.; Gandyl', E.M.; Podkopaev, A.P.

    1995-01-01

    The dynamics of high-current relativistic electron beam moving trough the cylindrical drift space has been modelled by the large particles, the shape of which allows to solve the Poisson equations exactly, and in such a way to avoid the linearization being usually used in those problems. The expressions for the components of own electric field of electron beam passing through the cylindrical drift space have been obtained. (author). 11 refs., 1 fig

  10. Current R and D Status on High-Level Radioactive Waste Disposal in Selected Countries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youn Myoung; Hwang, Yong Soo

    2008-11-15

    Current R and D status of such countries moving forward as the United States, Sweden, France, Japan and a few other countries for high-level radioactive waste (HLW) disposal in deep geological formation has been reviewed. Even though no HLW repositories have not practically constructed nor operated yet, lots of related R and D are being proceeded in many countries as well as in Korea. Through this brief review further progress is anticipated in this related R and D area in Korea.

  11. Overview of superconducting RF technology and its application to high-current linacs

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.

    1994-01-01

    Superconducting linacs may be a viable option for high-current applications such as copious neutron production like that needed for transmutation of radioactive waste. These linacs must run reliably for many years and allow easy routine maintenance. superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs. However, cost effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement

  12. The potential of large critical currents in the high Tc oxides

    International Nuclear Information System (INIS)

    Deutcher, G.

    1993-01-01

    The potential for high critical current densities is examined. on a thermodynamical basis, the energy scale for vortex pinning can be derived for instance from a measurement of the width of the critical region. This energy scale is of the order of 0.2 eV in YBCO, which is sufficient for practical applications. Another important parameter is the short coherence length. The inner plane length, of the order of a few lattice spacing, is favorable for pinning by point defects. But the very short outer plane length gives rise to anomalous magnetic behavior, unfavorable for high-field applications at high temperature; this is true in particular in most anisotropic oxides, such as the Bi compounds (author)

  13. Beam physics design strategy for a high-current rf linac

    Energy Technology Data Exchange (ETDEWEB)

    Reiser, M. [Univ. of Maryland, College Park, MD (United States)

    1995-10-01

    The high average beam power of an rf linac system for transmutation of nuclear waste puts very stringent requirements on beam quality and beam control. Fractional beam losses along the accelerator must be kept at extremely low levels to assure {open_quotes}hands-on{close_quotes} maintenance. Hence, halo formation and large-amplitude tails in the particle distribution due to beam mismatch and equipartitioning effects must be avoided. This implies that the beam should ideally be in near-perfect thermal equilibrium from injection to full energy - in contrast to existing rf linacs in which the transverse temperature, T {sub {perpendicular}}, is higher than the longitudinal temperature, T{sub {parallel}}. The physics and parameter scaling for such a system will be reviewed using the results of recent work on high-intensity bunched beams. A design strategy for a high-current rf linac with equilibrated beam will be proposed.

  14. 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.

  15. Design of an end station for a high current ion implantation system

    International Nuclear Information System (INIS)

    Kranik, J.R.

    1979-01-01

    During the last 4 to 5 years IBM has been involved in an effort to develop a high current Ion Implantation system with pre-deposition capabilities. The system is dedicated to Arsenic implants, involving doses > 1 x 10 15 ions/cm 2 in the energy range of 30 to 60 keV. A major portion of this effort involved the design of an associated end station capable of producing high uniformity implants with beam currents in the 0.5 to 6.0 mA range. The end station contains all components from the exit of the analyzing magnet, including the exit beamline, process chamber, scan system, wafer handling system, high vacuum pumping package, beam optics, dosimetry system, and associated electronic controls. The unit was restricted to a six wafer (82 mm) batch size to maintain process line compatibility. In addition, implant dose non-uniformity objectives were established at +- 3% (2σ) within a wafer and +- 2% (2σ) wafer-to-wafer. Also, the system was to be capable of implanting 24 wafers/hour at a dose of 7.5 x 10 15 ions/cm 2 . Major consideration in the design was afforded to high reliability, ease of maintenance and production level throughput capabilities. The rationale and evolution of the final end station design is described. (author)

  16. High current table-top setup for femtosecond gas electron diffraction

    Directory of Open Access Journals (Sweden)

    Omid Zandi

    2017-07-01

    Full Text Available We have constructed an experimental setup for gas phase electron diffraction with femtosecond resolution and a high average beam current. While gas electron diffraction has been successful at determining molecular structures, it has been a challenge to reach femtosecond resolution while maintaining sufficient beam current to retrieve structures with high spatial resolution. The main challenges are the Coulomb force that leads to broadening of the electron pulses and the temporal blurring that results from the velocity mismatch between the laser and electron pulses as they traverse the sample. We present here a device that uses pulse compression to overcome the Coulomb broadening and deliver femtosecond electron pulses on a gas target. The velocity mismatch can be compensated using laser pulses with a tilted intensity front to excite the sample. The temporal resolution of the setup was determined with a streak camera to be better than 400 fs for pulses with up to half a million electrons and a kinetic energy of 90 keV. The high charge per pulse, combined with a repetition rate of 5 kHz, results in an average beam current that is between one and two orders of magnitude higher than previously demonstrated.

  17. High Performance Carbon Nanotube Yarn Supercapacitors with a Surface-Oxidized Copper Current Collector.

    Science.gov (United States)

    Zhang, Daohong; Wu, Yunlong; Li, Ting; Huang, Yin; Zhang, Aiqing; Miao, Menghe

    2015-11-25

    Threadlike linear supercapacitors have demonstrated high potential for constructing fabrics to power electronic textiles (eTextiles). To improve the cyclic electrochemical performance and to produce power fabrics large enough for practical applications, a current collector has been introduced into the linear supercapcitors to transport charges produced by active materials along the length of the supercapacitor with high efficiency. Here, we first screened six candidate metal filaments (Pt, Au, Ag, AuAg, PtCu, and Cu) as current collectors for carbon nanotube (CNT) yarn-based linear supercapacitors. Although all of the metal filaments significantly improved the electrochemical performance of the linear supercapacitor, two supercapacitors constructed from Cu and PtCu filaments, respectively, demonstrate far better electrochemical performance than the other four supercapacitors. Further investigation shows that the surfaces of the two Cu-containing filaments are oxidized by the surrounding polymer electrolyte in the electrode. While the unoxidized core of the Cu-containing filaments remains highly conductive and functions as a current collector, the resulting CuO on the surface is an electrochemically active material. The linear supercapacitor architecture incorporating dual active materials CNT + Cu extends the potential window from 1.0 to 1.4 V, leading to significant improvement to the energy density and power density.

  18. RIKEN 200 kV high current implanter for metal surface modification

    International Nuclear Information System (INIS)

    Iwaki, M.; Yoshida, K.; Sakudo, N.

    1985-01-01

    A high current, metal ion implanter was constructed in order to aid the formation of a new metastable surface alloy. This implanter, called a RIKEN 200 kV high current implanter, is a modified Lintott high current machine (Series III), which has the advantages of having its own microwave ion source and an extra target chamber. The microwave discharge ion source without a hot-filament has a comparatively long lifetime because the chloride ions and radicals in a plasma during discharge of metal chlorides might prevent metal to deposit on the inner walls of the discharge chamber by bombarding and chemically cleaning them. An extra target chamber for metal modification is able to control the surface composition by utilizing the sputtering effect of the ion beam during ion implantation. The use of this ion source and the extra target chamber is suggested to be suitable for the production of metallic ions and for the implantation into metals. The case study will be introduced for TI implantation into Fe. (orig.)

  19. High-Definition transcranial direct current stimulation in early onset epileptic encephalopathy: a case study.

    Science.gov (United States)

    Meiron, Oded; Gale, Rena; Namestnic, Julia; Bennet-Back, Odeya; David, Jonathan; Gebodh, Nigel; Adair, Devin; Esmaeilpour, Zeinab; Bikson, Marom

    2018-01-01

    Early onset epileptic encephalopathy is characterized by high daily seizure-frequency, multifocal epileptic discharges, severe psychomotor retardation, and death at infancy. Currently, there are no effective treatments to alleviate seizure frequency and high-voltage epileptic discharges in these catastrophic epilepsy cases. The current study examined the safety and feasibility of High-Definition transcranial direct current stimulation (HD-tDCS) in reducing epileptiform activity in a 30-month-old child suffering from early onset epileptic encephalopathy. HD-tDCS was administered over 10 intervention days spanning two weeks including pre- and post-intervention video-EEG monitoring. There were no serious adverse events or side effects related to the HD-tDCS intervention. Frequency of clinical seizures was not significantly reduced. However, interictal sharp wave amplitudes were significantly lower during the post-intervention period versus baseline. Vital signs and blood biochemistry remained stable throughout the entire study. These exploratory findings support the safety and feasibility of 4 × 1 HD-tDCS in early onset epileptic encephalopathy and provide the first evidence of HD-tDCS effects on paroxysmal EEG features in electroclinical cases under the age of 36 months. Extending HD-tDCS treatment may enhance electrographic findings and clinical effects.

  20. Computer programmes for high current ion trajectories in a magnetic sector-type mass separator

    International Nuclear Information System (INIS)

    Nakai, Akira

    1988-01-01

    According to theoretical calculations previously proposed by the author, a new programme 'MALT' for electronic computers has been developed for numerical calculations of ion trajectories of a high current ion beam traversing a magnetic sector-type mass separator. In the programme, both effects of the fringing field and the space charge are taken into account in an analytical way, so that numerical calculations can be done straightforwardly. Furthermore, it becomes also possible to analyze and cotrol the trajectories of the high current ion beam. The programme MALT contains several subroutine programmes which are separated individually for the convenience of various calculations with respect to the high current ion beam. To demonstrate the calculations by the use of these subroutine programmes, a main programme for the calculation of the trajectories in the whole region of the separator is shown, which also makes it possible to draw the traces of the trajectories. The trajectories calculated by the proposed programme have been compared with the images of the ion beams recorded on novel dry plates developed by the author: the comparison enables us to evaluate the effective space charge and the effective space charge potential, and to analyze the behaviour of the beam of neutral particles accompanying the ion beam. (author)

  1. Critical current density and wire fabrication of high-TC superconductors

    International Nuclear Information System (INIS)

    Schlabach, T.D.; Jin, S.; Sherwood, R.C.; Tiefel, T.H.

    1989-01-01

    In this paper, some of the recent investigations of wire fabrication techniques and critical current behavior in high T c superconductors will be reviewed. In spite of the tremendous interest and research effort, the progress toward major applications of the bulk high-temperature superconductors has been impeded by, among other thins, the low critical currents and their severe deterioration in weak magnetic fields. Significant advances, however, have been made in understanding the causes of the problem as well as in improving the current-carrying capacity through proper microstructural control such as the melt-textured-growth in Y-Ba-Cu-O. The low density of effective flux-pinning sites in bulk Y-Ba-Cu-O limits J c at 77K in high magnetic fields to about 10 4 A/cm 2 even in the absence of weak links. Magnetization measurements on Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O at 77K by various researchers indicate even weaker flux pinning capabilities in these materials than in Y-Ba-Cu-O. The challenge in the future is to obtain suitable flux-pinning defects by choosing the right processing and chemistry changes

  2. Development of movable mask system to cope with high beam current

    International Nuclear Information System (INIS)

    Suetsugu, Y.; Shibata, K.; Sanami, T.; Kageyama, T.; Takeuchi, Y.

    2003-01-01

    The KEK B factory (KEKB), a high current electron-positron collider, has a movable mask (or collimator) system to reduce the background noise in the BELLE detector coming from spent particles. The early movable masks, however, had severe problems of heating, arcing, and vacuum leaks over the stored beam current of several hundred mA. The cause is intense trapped higher order modes (HOMs) excited at the mask head, where the cross section of the beam chamber changed drastically. The mask head, made of copper-tungsten alloy or pure copper, was frequently damaged by hitting of the high energy beam at the same time. Since the problems of the mask were revealed, several kinds of improved masks have been designed employing rf technologies in dealing with the HOM and installed to the ring step by step. Much progress has come from adopting a trapped-mode free structure, where the mask was a bent chamber itself. Recently the further improved mask with a reduced HOM design or HOM dampers was developed to suppress the heating of vacuum components near the mask due to the HOM traveling from the mask. To avoid damage to the mask head, on the other hand, a titanium mask head was tried. The latest masks are working as expected now at the stored beam current of 1.5 A. Presented are the problems and experiences on the movable mask system for the KEKB, which are characteristic of and common in a high intensity accelerator

  3. Acceleration of a high-current single bunch in a linear accelerator

    International Nuclear Information System (INIS)

    Takeda, Seishi

    1984-01-01

    Some problems associated with the feasibility of an electron-positron linear collider with colliding energy of about 1x1 TeV are discussed. The first problem is related to the generation of high-current single bunch. A quasi-relativistic electron beam from an electron gun is injected into one bucket of the accelerating fields, in opposition to the longitudinal defocusing due to the space-charge effect. For generating a high-current single bunch, the beam bunching by means of the velocity modulation with a subharmonic prebuncher (SHPB) is indispensable. Three existing second generation single bunch electron linear accelerators (SLC, ANL and ISLR-Osaka Univ.) are briefly described. The results of the simulation of subharmonic-bunching is also reported. The second problem is associated with the physics of accelerating high-current single bunch. The longitudinal and transverse wake fields generated by a bunch-cavity interaction and the energy spread of the single bunch are analyzed and discussed. (Aoki, K.)

  4. Towards a 20 kA high temperature superconductor current lead module using REBCO tapes

    Science.gov (United States)

    Heller, R.; Bagrets, N.; Fietz, W. H.; Gröner, F.; Kienzler, A.; Lange, C.; Wolf, M. J.

    2018-01-01

    Most of the large fusion devices presently under construction or in operation consisting of superconducting magnets like EAST, Wendelstein 7-X (W7-X), JT-60SA, and ITER, use high temperature superconductor (HTS) current leads (CL) to reduce the cryogenic load and operational cost. In all cases, the 1st generation HTS material Bi-2223 is used which is embedded in a low-conductivity matrix of AgAu. In the meantime, industry worldwide concentrates on the production of the 2nd generation HTS REBCO material because of the better field performance in particular at higher temperature. As the new material can only be produced in a multilayer thin-film structure rather than as a multi-filamentary tape, the technology developed for Bi-2223-based current leads cannot be transferred directly to REBCO. Therefore, several laboratories are presently investigating the design of high current HTS current leads made of REBCO. Karlsruhe Institute of Technology is developing a 20 kA HTS current lead using brass-stabilized REBCO tapes—as a further development to the Bi-2223 design used in the JT-60SA current leads. The same copper heat exchanger module as in the 20 kA JT-60SA current lead will be used for simplicity, which will allow a comparison of the newly developed REBCO CL with the earlier produced and investigated CL for JT-60SA. The present paper discusses the design and accompanying test of single tape and stack REBCO mock-ups. Finally, the fabrication of the HTS module using REBCO stacks is described.

  5. Effect of high-voltage impulse current on the structure and function of rabbit heart

    Directory of Open Access Journals (Sweden)

    Xin-ping XU

    2011-06-01

    Full Text Available Objective To explore the effect of high-voltage impulse current(HVIC on the structure and function of rabbit heart.Methods Sixty healthy male rabbits were involved in present study and divided into 6 groups randomly(n=10.The rabbits were then shocked using a high-voltage pulse generator with current intensity of 0,50,100,150,250 and 500mA(pulse width 100μs,duration 5s respectively.The heart rate and electrocardiogram(ECG of rabbits were detected before and 0,1,3,7,14 and 28 days after the electric shock.Moreover,the myocardial tissue of rabbits was obtained immediately and 28 days after shock to observe the pathological changes.Results Immediately after electric shock of 50 to 500mA,the heart rate of rabbit increased by different degree,and the ECG showed arrhythmia,myocardial ischemia,atrial fibrillation and atrioventricular block,and the changes recovered gradually one day later.The pathological observation showed cell swelling,separation of myofibril and sarcoplasmic condensation of Purkinje fibers immediately after electric shock of 50 to 500mA,and the changes recovered 28 days after shock.The cardiac injuries aggravated with the increasing of current intensity,especially when it exceeded 150mA,and the recovery time prolonged.Conclusion High-voltage impulse current may induce recoverable injuries on heart structure and function,and the damage effect shows a correlation with the current intensity.

  6. High-temperature current conduction through three kinds of Schottky diodes

    International Nuclear Information System (INIS)

    Fei, Li; Xiao-Ling, Zhang; Yi, Duan; Xue-Song, Xie; Chang-Zhi, Lü

    2009-01-01

    Fundamentals of the Schottky contacts and the high-temperature current conduction through three kinds of Schottky diodes are studied. N-Si Schottky diodes, GaN Schottky diodes and AlGaN/GaN Schottky diodes are investigated by I–V–T measurements ranging from 300 to 523 K. For these Schottky diodes, a rise in temperature is accompanied with an increase in barrier height and a reduction in ideality factor. Mechanisms are suggested, including thermionic emission, field emission, trap-assisted tunnelling and so on. The most remarkable finding in the present paper is that these three kinds of Schottky diodes are revealed to have different behaviours of high-temperature reverse currents. For the n-Si Schottky diode, a rise in temperature is accompanied by an increase in reverse current. The reverse current of the GaN Schottky diode decreases first and then increases with rising temperature. The AlGaN/GaN Schottky diode has a trend opposite to that of the GaN Schottky diode, and the dominant mechanisms are the effects of the piezoelectric polarization field and variation of two-dimensional electron gas charge density. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Microstructure and critical current density in high-Tc metal oxide superconductors

    International Nuclear Information System (INIS)

    Johnson, S.M.; Gusman, M.I.

    1992-03-01

    Superconductor powders in the U-Ba-Cu-O (YBCO) and Bi-Pb-Sr-Ca-Cu-O (BSCCO) systems were synthesized by freeze-drying. Powders were characterized, and processed into samples for evaluation of superconducting behavior. Freeze-drying is attractive because the powders have high purity, are homogeneous, have a small size and are active. YBCO powders can be sintered to high density at 890 degrees C. Many compositions, processing approaches and heat treatments were explored in an effort to understand relations between microstructure and critical density, and to improve the critical current density. Powders were also formed into sputtering targets for coating preparation at Stanford University. The highest critical current density achieved with the YBCO powders was ∼15,000 A/cm 2 at 4.2K and 0.5T using powders treated to prevent carbon contamination. The BSCCO materials with the highest critical current density, ∼30,000 A/cm 2 at the same conditions were formed by heat treating melted and quenched samples. All critical current density measurements were made by Stanford University, a subcontractor to this effort. Stanford University also prepared coatings by off-axis magnetron sputtering

  8. Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

    Science.gov (United States)

    Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

    2012-01-01

    We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.

  9. High Current Plasma Electrolytic Oxidation Coating Processes for Wear and Corrosion Prevention of Al 2024

    Science.gov (United States)

    Wang, Rui

    Plasma electrolytic oxidation (PEO) treatments have been used in the aerospace and automotive industries because the coating formed on light metals or alloys has great hardness, high wear, corrosion, and oxidation resistance, and a low friction coefficient that improves lifetime length and provide a higher surface quality. However, the PEO treatments that are presently used for industrial applications require a long period of time to confirm the quality of the coating. For this reason, the present study seeks to increase the current density of PEO treatments to improve their efficiency and explore the performance of the obtained coatings. It was found that for high current density (0.18A/cm2) PEO treatments, smaller ratio, such as 50% and 70%, is beneficial to obtaining a better performance coating. When compared with the coating of a "normal" (current density: 0.09A/cm2) PEO treatment, it had better wear resistance; however, for corrosion resistance, it had a lower performance than the coatings obtained by the "normal" current density PEO treatment which was attributed to the negative influence of porosity increase.

  10. The most intense electric currents in turbulent high speed solar wind

    Science.gov (United States)

    Podesta, J. J.

    2017-12-01

    Theory and simulations suggest that dissipation of turbulent energy in collisionless astrophysical plasmas occurs most rapidly in spatial regions where the current density is most intense. To advance understanding of plasma heating by turbulent dissipation in the solar corona and solar wind, it is of interest to characterize the properties of plasma regions where the current density takes exceptionally large values and to identify the operative dissipation processes. In the solar wind, the curl of the magnetic field cannot be measured using data from a single spacecraft, however, a suitable proxy for this quantity can be constructed from the spatial derivative of the magnetic field along the flow direction of the plasma. This new approach is used to study the properties of the most intense current carrying structures in a high speed solar wind stream near 1 AU. In this study, based on 11 Hz magnetometer data from the WIND spacecraft, the spatial resolution of the proxy technique is approximately equal to the proton inertial length. Intense current sheets or current carrying structures were identified as events where the magnitude of the current density exceeds μ+5σ, where μ and σ are the mean and standard deviation of the magnitude of the current density (or its proxy), respectively. Statistical studies show (1) the average size of these 5σ events is close to the smallest resolvable scale in the data set, the proton inertial length; (2) the linear distance between neighboring events follows a power law distribution; and (3) the average peak current density of 5σ events is around 1 pA/cm2. The analysis techniques used in these studies have been validated using simulated spacecraft data from three dimensional hybrid simulations which show that results based on the analysis of the proxy are qualitatively and quantitatively similar to results based on the analysis of the true current density.

  11. High Voltage, Fast-Switching Module for Active Control of Magnetic Fields and Edge Plasma Currents

    Science.gov (United States)

    Ziemba, Timothy; Miller, Kenneth; Prager, James; Slobodov, Ilia

    2016-10-01

    Fast, reliable, real-time control of plasma is critical to the success of magnetic fusion science. High voltage and current supplies are needed to mitigate instabilities in all experiments as well as disruption events in large scale tokamaks for steady-state operation. Silicon carbide (SiC) MOSFETs offer many advantages over IGBTs including lower drive energy requirements, lower conduction and switching losses, and higher switching frequency capabilities; however, these devices are limited to 1.2-1.7 kV devices. As fusion enters the long-pulse and burning plasma eras, efficiency of power switching will be important. Eagle Harbor Technologies (EHT), Inc. developing a high voltage SiC MOSFET module that operates at 10 kV. This switch module utilizes EHT gate drive technology, which has demonstrated the ability to increase SiC MOSFET switching efficiency. The module will allow more rapid development of high voltage switching power supplies at lower cost necessary for the next generation of fast plasma feedback and control. EHT is partnering with the High Beta Tokamak group at Columbia to develop detailed high voltage module specifications, to ensure that the final product meets the needs of the fusion science community.

  12. Current status of high level radioactive waste disposal in Japan and foreign countries

    International Nuclear Information System (INIS)

    Tanaka, Satoru; Tanabe, Hiromi; Inagaki, Yusuke; Ishida, Hisahiro; Kato, Osamu; Kurata, Mitsuyuki; Yamachika, Hidehiko

    2002-01-01

    At a time point of 2002, there is no country actually disposing high level radioactive wastes into grounds, but in most of countries legislative preparation and practicing agents are carried out and site selection is promoted together with energetic advancement of its R and Ds. As disposal methods of the high level radioactive wastes, various methods such as space disposal, oceanic bottom disposal, ice bed disposal, ground disposal, and so on have been examined. And, a processing technology called partitioning and transmutation technology separating long-lived radionuclides from liquid high level radioactive waste and transmutation into short-lived or harmless radionuclides has also been studied. Here was introduced their wrestling conditions in Japan and main foreign countries, as a special issue of the Current status of high level radioactive waste disposal in Japan and foreign countries'. The high level radioactive wastes (glassification solids or spent nuclear fuels) are wastes always formed by nuclear power generation and establishment of technologies is an important subject for nuclear fuel cycle. (G.K.)

  13. Transport measurements in superconductors: critical current of granular high TC ceramic superconductor samples

    International Nuclear Information System (INIS)

    Passos, W.A.C.

    2016-01-01

    This work presents a method to obtain critical current of granular superconductors. We have carried out transport measurements (ρxT curves and VxI curves) in a YBa_2Cu_3O_7_-_δ sample to determine critical current density of it. Some specimens reveal a 'semiconductor-like' behavior (electrical resistivity decreases with increasing temperatures above critical temperature T_c of material) competing with superconductor behavior. Due to high granular fraction of the sample, these competition is clearly noted in ρxT curves. Measurements carried out from 0 to 8500 Oe of applied field show the same behavior, and the critical current density of the samples is shown. (author)

  14. Virtual cathode regime in nonstationary electric high-current discharge in hydrogen

    International Nuclear Information System (INIS)

    Baksht, F.G.; Borodin, V.S.; Zhuravlev, V.N.

    1988-01-01

    Virtual cathode (VC) regime in a non-stationary high-current hydrogen arch is constructed. Basic calculational characteristics of the near-the-cathode layer are presented. The calculation was conducted for a 1 cm long cathode under 2x10 4 A/cm 2 current density in pulse and 10 atm. pressure. A rectangular current pulse was considered. It is shown that VC formation is caused by electron temperature reduction in the near-the-cathode area. This results in the reduction of ion flux from plasma to the cathode surface and finally in the change of a sign of space charge and field intensity near the surface. Under the transition to VC regime only the cathode temperature and its effective work function are practically changed, while the rest of parameters remain approximately constant

  15. Thermal Impact Analysis of Circulating Current in High Power Modular Online Uninterruptible Power Supplies Application

    DEFF Research Database (Denmark)

    Zhang, Chi; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    In modular uninterruptible power supplies (UPSs), several DC/AC modules are required to work in parallel. This structure allows the system to be more reliable and flexible. These DC/AC modules share the same DC bus and AC critical bus. Module differences, such as filter inductor, filter capacitor......, control parameters, and so on, will make it possible for the potential zero sequence current to flow among the modules. This undesired type of circulating current will bring extra losses to the power semiconductor devices in the system, which should be paid special attention in high power application...... scenarios. In this paper, plug’n’play modules and cycle control are discussed and validated through experimental results. Moreover, potential zero sequence circulating current impact on power semiconductor devices thermal performance is also analyzed in this paper....

  16. High current pulser for experiment No. 225, neutrino electron elastic scattering

    International Nuclear Information System (INIS)

    Dalton, C.; Krausse, G.; Sarjeant, J.

    1979-01-01

    With the advent of low-cost honeycomb extrusions of polypropylene sheets, flash chambers have become very attractive for large nuclear particle detector arrays. This has brought about the need for a pulse power system that will provide high peak currents and low levels of spurious radiation. Each module of 10 flash chambers will require a peak current of 70 KA with a rise time (tau/sub r/) of <50 ns, giving a maximum rate of current rise di/dt of 400 KA/μs. The pulser output must develop 7 KV across a load of 0.36 Ω with a pulse width of 500 ns. The repetition rate will be one per second. The paper describes the development of such a system and the impact of the physical limitations of present component technology on lifetime and pulse fidelity

  17. High temperature superconducting current lead test facility with heat pipe intercepts

    International Nuclear Information System (INIS)

    Blumenfeld, P.E.; Prenger, C.; Roth, E.W.; Stewart, J.A.

    1998-01-01

    A high temperature superconducting (HTS) current lead test facility using heat pipe thermal intercepts is under development at the Superconducting Technology Center at Los Alamos National Laboratory. The facility can be configured for tests at currents up to 1,000 A. Mechanical cryocoolers provide refrigeration to the leads. Electrical isolation is maintained by intercepting thermal energy from the leads through cryogenic heat pipes. HST lead warm end temperature is variable from 65 K to over 90 K by controlling heat pipe evaporator temperature. Cold end temperature is variable up to 30 K. Performance predictions in terms of heat pipe evaporator temperature as a function of lead current are presented for the initial facility configuration, which supports testing up to 200 A. Measurements are to include temperature and voltage gradient in the conventional and HTS lead sections, temperature and heat transfer rate in the heat pipes. as well as optimum and off-optimum performance of the conventional lead sections

  18. Fast commutation of high current in double wire array Z-pinch loads

    International Nuclear Information System (INIS)

    Davis, J.; Gondarenko, N.A.; Velikovich, A.L.

    1997-01-01

    A dynamic model of multi-MA current commutation in a double wire array Z-pinch load is proposed and studied theoretically. Initially, the load is configured as nested concentric wire arrays, with the current driven through the outer array and imploding it. Once the outer array or the annular plasma shell formed from it approaches the inner array, the imploded plasma might penetrate through the gaps between the wires, but the azimuthal magnetic field is trapped due to both the high conductivity of the inner wires and the inductive coupling between the two parts of the array, causing a rapid switching of the total current to the inner part of the array. copyright 1997 American Institute of Physics

  19. The production of high poloidal tokamak equilibria in Versator II by means of RF current drive

    International Nuclear Information System (INIS)

    Luckhardt, S.C.; Chen, K.-I.; Kesner, J.; Kirkwood, R.; Lane, B.; Porkolab, M.; Squire, J.

    1989-01-01

    Experiments on the Versator II device have been carried out in a regime of low plasma current with the aim of reaching high poloidal beta, β p . Lower-Hybrid RF current drive is used to produce an energetic electron population which carries the plasma current and pressure. In this mode of operation, plasmas with εβ p approaching unity appear attainable. Data from equilibrium magnetic analysis, hard x-ray, and density profiles display an outward magnetic axis shift in agreement with equilibrium theory, and further indicate that q(O) is in the range of 4-6. PEST code modeling of these experiments suggests that some of these plasmas may be near or beyond the transition to the second stability region for ballooning modes. (author)

  20. The high peak current polarized electron source of the Stanford Linear Collider

    International Nuclear Information System (INIS)

    Schultz, D.; Alley, R.; Aoyagi, H.; Clendenin, J.; Frisch, J.; Garden, C.; Hoyt, E.; Kirby, R.; Klaisner, L.; Kulikov, A.; Mulhollan, G.; Prescott, C.; Saez, P.; Tang, H.; Turner, J.; Woods, M.; Yeremian, D.; Zolotorev, M.

    1994-01-01

    The Stanford Linear Collider injector requires two 2 ns pulses of 4.5-5.5 x 10 10 electrons, separated by 61 ns at 120 Hz, from its source. Since 1992, these currents have been provided by a polarized electron source based on GaAs photocathodes. A beam polarization of 76±4% has been measured at the end of the 50 GeV linac. At low photocathode quantum efficiencies, and for excitation near threshold, the maximum current delivered by the source is constrained, not by the space charge limit of the gun, but by a ''charge limit'' of the photocathode. The charge limited current is proportional to the photocathode quantum efficiency, but the proportionality varies for different photocathode types. Experience with high polarization strained GaAs photocathodes on a test beamline and on the SLC is presented. (orig.)