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Sample records for emittance dc electron

  1. DC-SC Photoinjector with Low Emittance at Peking University

    CERN Document Server

    Xiang Rong; Hao, J; Huang, Senlin; Lu Xiang Yang; Quan, Shengwen; Zhang, Baocheng; Zhao, Kui

    2005-01-01

    High average power Free Electron Lasers require the high quality electron beams with the low emittance and the sub-picosecond bunches. The design of DC-SC photoinjector, directly combining a DC photoinjector with an SRF cavity, can produce high average current beam with moderate bunch charge and high duty factor. Because of the DC gun, the emittance increases quickly at the beginning, so a carefully design is needed to control that. In this paper, the simulation of an upgraded design has been done to lower the normalized emittance below 1.5mm·mrad. The photoinjector consists of a DC gap and a 2+1/2-cell SRF cavity, and it is designed to produce 4.2 MeV electron beams at 100pC bunch charge and 81.25MHz repetition rate (8 mA average current).

  2. Diamondoid monolayers as electron emitters

    Science.gov (United States)

    Yang, Wanli [El Cerrito, CA; Fabbri, Jason D [San Francisco, CA; Melosh, Nicholas A [Menlo Park, CA; Hussain, Zahid [Orinda, CA; Shen, Zhi-Xun [Stanford, CA

    2012-04-10

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  3. Emitter location errors in electronic recognition system

    Science.gov (United States)

    Matuszewski, Jan; Dikta, Anna

    2017-04-01

    The paper describes some of the problems associated with emitter location calculations. This aspect is the most important part of the series of tasks in the electronic recognition systems. The basic tasks include: detection of emission of electromagnetic signals, tracking (determining the direction of emitter sources), signal analysis in order to classify different emitter types and the identification of the sources of emission of the same type. The paper presents a brief description of the main methods of emitter localization and the basic mathematical formulae for calculating their location. The errors' estimation has been made to determine the emitter location for three different methods and different scenarios of emitters and direction finding (DF) sensors deployment in the electromagnetic environment. The emitter has been established using a special computer program. On the basis of extensive numerical calculations, the evaluation of precise emitter location in the recognition systems for different configuration alignment of bearing devices and emitter was conducted. The calculations which have been made based on the simulated data for different methods of location are presented in the figures and respective tables. The obtained results demonstrate that calculation of the precise emitter location depends on: the number of DF sensors, the distances between emitter and DF sensors, their mutual location in the reconnaissance area and bearing errors. The precise emitter location varies depending on the number of obtained bearings. The higher the number of bearings, the better the accuracy of calculated emitter location in spite of relatively high bearing errors for each DF sensor.

  4. Low Emittance Electron Beam Studies

    Energy Technology Data Exchange (ETDEWEB)

    Tikhoplav, Rodion [Univ. of Rochester, NY (United States)

    2006-01-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*01 mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  5. Electron sources with a plasma emitter

    Science.gov (United States)

    Kreindel, Iu. E.

    Papers are presented concerning electron guns which utilize plasma emitters involving low-pressure cold-cathode gas discharges. Particular attention is given to the development of high-brightness plasma emitters and the control of their parameters; experimental results on the operating conditions of various types of gas discharges used to obtain continuous and pulsed electron beams of large cross section; and the designs and characteristics of plasma-emitter electron guns. A number of applications are considered, including electron-beam welding, sintering, thin-film technology, and electron-beam diagnostics. No individual items are abstracted in this volume

  6. Emittance growth from electron beam modulation

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2009-12-01

    In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

  7. Electron Emission from Ultra-Large Area MOS Electron Emitters

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm

    2009-01-01

    Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1 cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (~5 nm), a Ti wetting layer (3–10 Å), and a Au top layer (5–60 nm). Electron emission from...

  8. Magnetic tunnel transistor with a silicon hot-electron emitter

    NARCIS (Netherlands)

    Le Minh, P.; Gökcan, H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    We report on a modified magnetic tunnel transistor having a silicon tunnel emitter. The device has the structure Si/Al2O3 /base/Si with a spin-valve metal base, a Schottky barrier collector, but a silicon emitter separated from the base by a thin tunnel oxide. The energy of the hot electrons

  9. Modified theoretical minimum emittance lattice for an electron storage ring with extreme-low emittance

    Directory of Open Access Journals (Sweden)

    Yi Jiao

    2011-05-01

    Full Text Available In the continuing efforts to reduce the beam emittance of an electron storage ring composed of theoretical minimum emittance (TME lattice, down to a level of several tens of picometers, nonlinear dynamics grows to be a great challenge to the performance of the storage ring because of the strong sextupoles needed to compensate for its large global natural chomaticities coupled with its small average dispersion function. To help in dealing with the challenge of nonlinear optimization, we propose a novel variation of theoretical minimum emittance (TME lattice, named as “modified-TME” lattice, with minimal emittance about 3 times of the exact theoretical minimum, while with more compact layout, lower phase advance per cell, smaller natural chromaticities, and more relaxed optical functions than that in a TME cell, by using horizontally defocusing quadrupole closer to the dipole or simply combined-function dipole with horizontally defocusing gradient. We present approximate scaling formulas to describe the relationships of the design parameters in a modified-TME cell. The applications of modified-TME lattice in the PEP-X storage ring design are illustrated and the proposed lattice appears a good candidate for synchrotron radiation light source with extremely low emittance.

  10. M11.4.1: Electron beam emittance meter finished

    CERN Document Server

    CORDE, S

    2011-01-01

    The method that we have successfully developed based on the X ray radiation emitted by betatronic motion of electrons in the plasma is reported here. We show here very preliminary experimental results that are very promising to determine in a single shot the electron beam emittance with a high resolution.

  11. Industrial application of electron sources with plasma emitters

    CERN Document Server

    Belyuk, S I; Rempe, N G

    2001-01-01

    Paper contains a description, operation, design and parameters of electron sources with plasma emitters. One presents examples of application of these sources as part of automated electron-beam welding lines. Paper describes application of such sources for electron-beam deposition of composite powders. Electron-beam deposition is used to rebuild worn out part and to increase strength of new parts of machines and tools. Paper presents some examples of rebuilding part and the advantages gained in this case

  12. Emittance Measurements from a Laser Driven Electron Injector

    Energy Technology Data Exchange (ETDEWEB)

    Reis, David A

    2003-07-28

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 {angstrom}, the LCLS requires an electron injector that can produce an electron beam with approximately 1 {pi} mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance-compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, s-band high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be {approx} 13 {pi} mm-mrad for 5 ps and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.5 {pi} mm-mrad.

  13. Electron Cloud at Low Emittance in CesrTA

    CERN Document Server

    Palmer, Mark; Billing, Michael; Calvey, Joseph; Conolly, Christopher; Crittenden, James; Dobbins, John; Dugan, Gerald; Eggert, Nicholas; Fontes, Ernest; Forster, Michael; Gallagher, Richard; Gray, Steven; Greenwald, Shlomo; Hartill, Donald; Hopkins, Walter; Kreinick, David; Kreis, Benjamin; Leong, Zhidong; Li, Yulin; Liu, Xianghong; Livezey, Jesse; Lyndaker, Aaron; Makita, Junki; McDonald, Michael; Medjidzade, Valeri; Meller, Robert; O'Connell, Tim; Peck, Stuart; Peterson, Daniel; Ramirez, Gabriel; Rendina, Matthew; Revesz, Peter; Rider, Nate; Rice, David; Rubin, David; Sagan, David; Savino, James; Schwartz, Robert; Seeley, Robert; Sexton, James; Shanks, James; Sikora, John; Smith, Eric; Strohman, Charles; Williams, Heather; Antoniou, Fanouria; Calatroni, Sergio; Gasior, Marek; Jones, Owain Rhodri; Papaphilippou, Yannis; Pfingstner, Juergen; Rumolo, Giovanni; Schmickler, Hermann; Taborelli, Mauro; Asner, David; Boon, Laura; Garfinkel, Arthur; Byrd, John; Celata, Christine; Corlett, John; De Santis, Stefano; Furman, Miguel; Jackson, Alan; Kraft, Rick; Munson, Dawn; Penn, Gregory; Plate, David; Venturini, Marco; Carlson, Benjamin; Demma, Theo; Dowd, Rohan; Flanagan, John; Jain, Puneet; Kanazawa, Ken-ichi; Kubo, Kiyoshi; Ohmi, Kazuhito; Sakai, Hiroshi; Shibata, Kyo; Suetsugu, Yusuke; Tobiyama, Makoto; Gonnella, Daniel; Guo, Weiming; Harkay, Katherine; Holtzapple, Robert; Jones, James; Wolski, Andrzej; Kharakh, David; Ng, Johnny; Pivi, Mauro; Wang, Lanfa; Ross, Marc; Tan, Cheng-Yang; Zwaska, Robert; Schachter, Levi; Wilkinson, Eric

    2010-01-01

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud’s effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results

  14. Intrinsic normalized emittance growth in laser-driven electron accelerators

    Directory of Open Access Journals (Sweden)

    M. Migliorati

    2013-01-01

    Full Text Available Laser-based electron sources are attracting strong interest from the conventional accelerator community due to their unique characteristics in terms of high initial energy, low emittance, and significant beam current. Extremely strong electric fields (up to hundreds of GV/m generated in the plasma allow accelerating gradients much higher than in conventional accelerators and set the basis for achieving very high final energies in a compact space. Generating laser-driven high-energy electron beam lines therefore represents an attractive challenge for novel particle accelerators. In this paper we show that laser-driven electrons generated by the nowadays consolidated TW laser systems, when leaving the interaction region, are subject to a very strong, normalized emittance worsening which makes them quickly unusable for any beam transport. Furthermore, due to their intrinsic beam characteristics, controlling and capturing the full beam current can only be achieved improving the source parameters.

  15. Electron Cloud at Low Emittance in CesrTA

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Mark; /Cornell U., CLASSE; Alexander, James; /Cornell U., CLASSE; Billing, Michael; /Cornell U., CLASSE; Calvey, Joseph; /Cornell U., CLASSE; Conolly, Christopher; /Cornell U., CLASSE; Crittenden, James; /Cornell U., CLASSE; Dobbins, John; /Cornell U., CLASSE; Dugan, Gerald; /Cornell U., CLASSE; Eggert, Nicholas; /Cornell U., CLASSE; Fontes, Ernest; /Cornell U., CLASSE; Forster, Michael; /Cornell U., CLASSE; Gallagher, Richard; /Cornell U., CLASSE; Gray, Steven; /Cornell U., CLASSE; Greenwald, Shlomo; /Cornell U., CLASSE; Hartill, Donald; /Cornell U., CLASSE; Hopkins, Walter; /Cornell U., CLASSE; Kreinick, David; /Cornell U., CLASSE; Kreis, Benjamin; /Cornell U., CLASSE; Leong, Zhidong; /Cornell U., CLASSE; Li, Yulin; /Cornell U., CLASSE; Liu, Xianghong; /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /CERN /CERN /CERN /CERN /CERN /CERN; /more authors..

    2012-07-06

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  16. Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters

    Science.gov (United States)

    Bocharov, Grigory S.; Eletskii, Alexander V.

    2013-01-01

    Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules. PMID:28348342

  17. Theory of Carbon Nanotube (CNT-Based Electron Field Emitters

    Directory of Open Access Journals (Sweden)

    Alexander V. Eletskii

    2013-07-01

    Full Text Available Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules.

  18. Emittance growth induced by electron cloud in proton storage rings

    CERN Document Server

    Benedetto, Elena; Coppa, G

    2006-01-01

    In proton and positron storage rings with many closely spaced bunches, a large number of electrons can accumulate in the beam pipe due to various mechanisms (photoemission, residual gas ionization, beam-induced multipacting). The so-formed electron cloud interacts with the positively charged bunches, giving rise to instabilities, emittance growth and losses. This phenomenon has been observed in several existing machines such as the CERN Super Proton Synchrotron (SPS), whose operation has been constrained by the electron-cloud problem, and it is a concern for the Large Hadron Collider (LHC), under construction at CERN. The interaction between the beam and the electron cloud has features which cannot be fully taken into account by the conventional and known theories from accelerators and plasma physics. Computer simulations are indispensable for a proper prediction and understanding of the instability dynamics. The main feature which renders the beam-cloud interactions so peculiar is that the the electron cloud...

  19. Field Emitter Arrays for a Free Electron Laser Application

    CERN Document Server

    Shing-Bruce-Li, Kevin; Ganter, Romain; Gobrecht, Jens; Raguin, Jean Yves; Rivkin, Leonid; Wrulich, Albin F

    2004-01-01

    The development of a new electron gun with the lowest possible emittance would help reducing the total length and cost of a free electron laser. Field emitter arrays (FEAs) are an attractive technology for electron sources of ultra high brightness. Indeed, several thousands of microscopic tips can be deposited on a 1 mm diameter area. Electrons are then extracted by applying voltage to a first grid layer close to the tip apexes, the so called gate layer, and focused by a second grid layer one micrometer above the tips. The typical aperture diameter of the gate and the focusing layer is in the range of one micrometer. One challenge for such cathodes is to produce peak currents in the ampere range since the usual applications of FEAs require less than milliampere. Encouraging peak current performances have been obtained by applying voltage pulses at low frequency between gate and tips. In this paper we report on different tip materials available on the market: diamond FEAs from Extreme Devices Inc., ZrC single ...

  20. D11.4.1: Preliminary electron beam emittance measurement report

    CERN Document Server

    THAURY, C; MALKA, V

    2012-01-01

    We report on a new method for measuring the beam emittance in laser-plasma accelerator which is based on the observation of the X ray radiation emitted by betatronic motion of electrons in the plasma. We show here the first measurement of the emittance using this technique. The results indicate that emittance is comprised between .5 and 3 mm.mrad.

  1. Methods of measuring of the ion beam transversal emittance in the injection channel of the cyclotron DC-72

    CERN Document Server

    Kazarinov, N; Kalagin, I V; Kazacha, V I

    2002-01-01

    The methods of measuring of the transversal emittance of ion beams in the cyclotron DC-72 injection channel with the help of the 'pepper-pot' and gradient means are discussed in this work. Two ways for the reconstruction of the ion beam transversal emittance are proposed for the 'pepper-pot' method. The first one can be used for beams having the uniform distribution of particles in the phase space. At that the values of the Twiss matrix and the full beam emittance are reconstructed according to the measurement results with the help of the phase ellipse fitting by the least-squares method. The corresponding FORTRAN code was created. On simulation the beam emittance was reconstructed with accuracy of 5%. The second method of the beam emittance reconstruction can be used in the common case at the arbitrary particle distribution in the phase space. It is based on calculation of the mean-square parameters of the beam according to the measurement results in the plane of the 'pepper-pot' mask. The mean-square emitta...

  2. Extreme regimes of femtosecond photoemission from a copper cathode in a dc electron gun

    Directory of Open Access Journals (Sweden)

    P. L. E. M. Pasmans

    2016-10-01

    Full Text Available The femtosecond photoemission yield from a copper cathode and the emittance of the created electron beams has been studied in a 12  MeV/m, 100 keV dc electron gun over a wide range of laser fluence, from the linear photoemission regime until the onset of image charge limitations and cathode damaging. The measured photoemission curves can be described well with available theory which includes the Schottky effect, second-order photoemission, and image charge limitation. The second-order photoemission can be explained by thermally assisted one-photon photoemission (1PPE and by above-threshold two-photon photoemission (2PPE. Measurements with a fresh cathode suggest that the 2PPE process is dominant. The beam emittance has been measured for the entire range of initial surface charge densities as well. The emittance measurements of space-charge dominated beams can be described well by an envelope equation with generalized perveance. The dc gun produces 0.1 pC bunches with 25 nm rms normalized emittance, corresponding to a normalized brightness usually associated with rf photoguns. In this experimental study the limits of femtosecond photoemission from a copper cathode have been explored and analyzed in great detail, resulting in improved understanding of the underlying mechanisms.

  3. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

    Science.gov (United States)

    An, Weiming; Lu, Wei; Huang, Chengkun; Xu, Xinlu; Hogan, Mark J.; Joshi, Chan; Mori, Warren B.

    2017-06-01

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of less than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. The underlying physics that leads to the lower than expected emittance growth is elucidated.

  4. Brushless dc motor uses electron beam switching tube as commutator

    Science.gov (United States)

    Studer, P.

    1965-01-01

    Electron beam switching tube eliminates physical contact between rotor and stator in brushless dc motor. The tube and associated circuitry control the output of a dc source to sequentially energize the motor stator windings.

  5. High-efficient thermoemission electron source with emitter of lanthanum hexaboride

    Energy Technology Data Exchange (ETDEWEB)

    Iremashvili, D.V.; Sukhomlinov, V.V.; Ksenofontov, V.A.; Chanturidze, V.G.; Petrakov, V.E.; Avatinyan, G.A.

    1982-01-01

    A high-efficient thermoemission electron source with LaB/sub 6/ emitter and indirect heating is described. The design of cathode unit with 30 and 50 mm diameters of emitter is given. The technique for investigating the source operation is described. At high reliability of operation the cathode unit provides with approximately 2 kA current at approximately 2000 K working temperature of the emitter. Permissible time of heating is approximately 15 min. Operation life of the cathode unit is 500 h at 2000 K temperature of the emitter multiple depressurizing (> 100 times).

  6. Generation of low-emittance electron beams in electrostatic accelerators for FEL applications

    Science.gov (United States)

    Teng, Chen; Elias, Luis R.

    1995-02-01

    This paper reports results of transverse emittance studies and beam propagation in electrostatic accelerators for free electron laser applications. In particular, we discuss emittance growth analysis of a low current electron beam system consisting of a miniature thermoionic electron gun and a National Electrostatics Accelerator (NEC) tube. The emittance growth phenomenon is discussed in terms of thermal effects in the electron gun cathode and aberrations produced by field gradient changes occurring inside the electron gun and throughout the accelerator tube. A method of reducing aberrations using a magnetic solenoidal field is described. Analysis of electron beam emittance was done with the EGUN code. Beam propagation along the accelerator tube was studied using a cylindrically symmetric beam envelope equation that included beam self-fields and the external accelerator fields which were derived from POISSON simulations.

  7. Low-emittance tuning at the Cornell Electron Storage Ring Test Accelerator

    Directory of Open Access Journals (Sweden)

    J. Shanks

    2014-04-01

    Full Text Available In 2008 the Cornell Electron/Positron Storage Ring (CESR was reconfigured from an electron/positron collider to serve as a test bed for the International Linear Collider damping rings. One of the primary goals of the CESR Test Accelerator (CesrTA project is to develop a fast low-emittance tuning method which scales well to large rings such as the ILC damping rings, and routinely achieves a vertical emittance of order 10 pm at 2.085 GeV. This paper discusses the tuning methods developed at CesrTA to achieve low-emittance conditions. One iteration of beam-based measurement and correction requires about 10 min. A minimum vertical emittance of 10.3(+3.2/−3.4^{sys}(±0.2^{stat}  pm has been achieved at 2.085 GeV. In various configurations and beam energies the correction technique routinely achieves vertical emittance around 10 pm after correction, with rms coupling <0.5%. The measured vertical dispersion is dominated by beam position monitor systematics. The propagation of uncertainties in the emittance measurement is described in detail. Simulations modeling the effects of magnet misalignments, beam position monitor errors, and the emittance correction algorithm suggest the residual vertical emittance measured at the conclusion of the tuning procedure is dominated by sources other than optics errors and misalignments.

  8. Experimental optimization of the 6-dimentional electron beam emittance at the NSLS SDL

    Science.gov (United States)

    Qian, H. J.; Murphy, J. B.; Shen, Y.; Tang, C. X.; Wang, X. J.

    2011-08-01

    Experimental optimization of the 6-dimensional electron beam emittance generated by a Magnesium (Mg) photocathode RF gun is presented in this report. A new electron beam optimization algorithm for a low charge (<100 pC) beam was experimentally demonstrated; where the electron beam velocity bunching inside the RF gun plays a critical role, and the transverse emittance as a function of the laser-RF timing jitter was experimentally characterized for the first time. A 20 pC electron beam was optimized to have a normalized slice emittance of 0.15 mm mrad and a longitudinal projected emittance of 3.9 ps keV. Furthermore, the upper limit of the measured thermal emittance—0.5 mm mrad per mm of the rms laser size, is about 50% lower than the theoretical prediction for a Mg cathode (Qian et al., 2010) [1].

  9. Carbon Nanotube Electron Emitter for X-ray Imaging

    Directory of Open Access Journals (Sweden)

    Jung Su Kang

    2012-11-01

    Full Text Available The carbon nanotube field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP process. The shape of the carbon nanotube array is elliptical with 2.0 × 0.5 mm2 for an isotropic focal spot size at anode target. The field emission properties with triode electrodes show a gate turn-on field of 3 V/µm at an anode emission current of 0.1 mA. The author demonstrated the X-ray source with triode electrode structure utilizing the carbon nanotube emitter, and the transmitted X-ray image was of high resolution.

  10. Characterizing and Optimizing Photocathode Laser Distributions for Ultra-low Emittance Electron Beam Operations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Bohler, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ding, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gilevich, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Huang, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Loos, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ratner, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Vetter, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-12-07

    Photocathode RF gun has been widely used for generation of high-brightness electron beams for many different applications. We found that the drive laser distributions in such RF guns play important roles in minimizing the electron beam emittance. Characterizing the laser distributions with measurable parameters and optimizing beam emittance versus the laser distribution parameters in both spatial and temporal directions are highly desired for high-brightness electron beam operation. In this paper, we report systematic measurements and simulations of emittance dependence on the measurable parameters represented for spatial and temporal laser distributions at the photocathode RF gun systems of Linac Coherent Light Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.

  11. Transverse emittance and current of multi-GeV trapped electrons in a plasma wakefield accelerator

    Directory of Open Access Journals (Sweden)

    N. Kirby

    2009-05-01

    Full Text Available Multi-GeV trapped electron bunches in a plasma wakefield accelerator (PWFA are observed with normalized transverse emittance divided by peak current, ϵ_{N,x}/I_{t}, below the level of 0.2  μm/kA. A theoretical model of the trapped electron emittance, developed here, indicates that emittance scales inversely with the square root of the plasma density in the nonlinear “bubble” regime of the PWFA. This model and simulations indicate that the observed values of ϵ_{N,x}/I_{t} result from multi-GeV trapped electron bunches with emittances of a few  μm and multi-kA peak currents.

  12. Two new families of high-gain dc-dc power electronic converters for dc-microgrids

    Science.gov (United States)

    Prabhala, Venkata Anand Kishore

    Distributing the electric power in dc form is an appealing solution in many applications such as telecommunications, data centers, commercial buildings, and microgrids. A high gain dc-dc power electronic converter can be used to individually link low-voltage elements such as solar panels, fuel cells, and batteries to the dc voltage bus which is usually 400 volts. This way, it is not required to put such elements in a series string to build up their voltages. Consequently, each element can function at it optimal operating point regardless of the other elements in the system. In this dissertation, first a comparative study of dc microgrid architectures and their advantages over their ac counterparts is presented. Voltage level selection of dc distribution systems is discussed from the cost, reliability, efficiency, and safety standpoints. Next, a new family of non-isolated high-voltage-gain dc-dc power electronic converters with unidirectional power flow is introduced. This family of converters benefits from a low voltage stress across its switches. The proposed topologies are versatile as they can be utilized as single-input or double-input power converters. In either case, they draw continuous currents from their sources. Lastly, a bidirectional high-voltage-gain dc-dc power electronic converter is proposed. This converter is comprised of a bidirectional boost converter which feeds a switched-capacitor architecture. The switched-capacitor stage suggested here has several advantages over the existing approaches. For example, it benefits from a higher voltage gain while it uses less number of capacitors. The proposed converters are highly efficient and modular. The operating modes, dc voltage gain, and design procedure for each converter are discussed in details. Hardware prototypes have been developed in the lab. The results obtained from the hardware agree with those of the simulation models.

  13. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Yi-Ting [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Li, Kuan-Wei [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Honda, Shin-ichi [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Lin, Pao-Hung; Huang, Ying-Sheng [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Lee, Kuei-Yi, E-mail: kylee@mail.ntust.edu.tw [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China)

    2017-06-01

    Graphical abstract: The pattern design provides a new structure of surface-conduction electron-emitter display (SED). Delta-star shaped vertically aligned CNT (VACNT) arrays with 20o tips can simultaneously provide three emitters to bombard the sides of equilateral triangles pattern of VACNT, which produces numerous secondary electrons and enhance the SED efficiency. - Highlights: • The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. • The vertically aligned CNT (VACNT) arrays with 20° tips of the delta-star arrangement are used as cathodes that easily emit electrons. The cathode pattern simultaneously provides three emitters to bombard the sides of equilateral triangles pattern of VACNT. • The VACNT arrays were covered with magnesium oxide (MgO) nanostructures to promote the surface-conduction electron-emitter display (SED) efficiency (η). • The η was stably maintained in the 75–85% range. The proposed design provides a facile new method for developing SED applications. - Abstract: The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75–85% range. The proposed design provides a facile new method for

  14. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.

    2006-01-01

    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  15. Multiplexing and scaling-down of nanostructured photon-triggered silicon field emitter arrays for maximum total electron yield

    Science.gov (United States)

    Dong, Chen D.; Swanwick, Michael E.; Keathley, Phillip D.; Kärtner, Franz X.; Velásquez-García, Luis F.

    2015-07-01

    Femtosecond ultrabright cathodes with spatially structured emission are a critical technology for applications such as free-electron lasers, tabletop coherent x-ray sources, and ultrafast imaging. In this work, the optimization of the total electron yield of ultrafast photon-triggered field emission cathodes composed of arrays of nanosharp, high-aspect-ratio, single-crystal silicon pillars is explored through the variation of the emitter pitch and height. Arrays of 6 nm tip radius silicon emitters with emitter densities between 1.2 and 73.9 million tips cm-2 (hexagonally packed arrays with emitter pitch between 1.25 and 10 μm) and emitter height between 2.0 and 8.5 μm were characterized using 35 fs 800 nm laser pulses. Three-photon electron emission for low-energy (1 μJ) light pulses was observed, in agreement with the literature. Of the devices tested, the arrays with emitter pitch equal to 2.5 μm produced the highest total electron yield; arrays with larger emitter pitch suffer area sub-utilization, and in devices with smaller emitter pitch the larger emitter density does not compensate the smaller per-emitter current due to the electric field shadowing that results from the proximity of the adjacent tips. Experimental data and simulations suggest that 2 μm tall emitters achieve practical optimal performance as shorter emitters have visibly smaller field factors due to the proximity of the emitter tip to the substrate, and taller emitters show marginal improvement in the electron yield at the expense of greater fabrication difficulty.

  16. Low emittance electron beam formation with a 17 GHz RF gun

    Directory of Open Access Journals (Sweden)

    W. J. Brown

    2001-08-01

    Full Text Available We report on electron beam quality measurement results from the Massachusetts Institute of Technology 17 GHz RF gun experiment. The 1.5 cell RF gun uses a solenoid for emittance compensation. It has produced bunch charges up to 0.1 nC with beam energies up to 1 MeV. The normalized rms emittance of the beam after 35 cm of transport from the gun has been measured by a slit technique to be 3π mm mrad for a 50 pC bunch. This agrees well with PARMELA simulations at these beam energies. At the exit of the electron gun, we estimate the emittance to be about 1π mm mrad, which corresponds to a beam brightness of about 80 A/(π mm mrad^{2}. Improved beam quality should be possible with a higher energy output electron beam from the gun.

  17. Electron injection and emittance control by transverse colliding pulses in a laser-plasma accelerator

    Directory of Open Access Journals (Sweden)

    M. Chen

    2014-05-01

    Full Text Available A method to inject electron beams with controllable transverse emittances in a laser-plasma accelerators is proposed and analyzed. It uses two colliding laser pulses that propagate transversely to the plasma wave. For colliding pulses with equal frequencies, a beam with very low emittance is generated when the collision is close to the density peak of the plasma wave. Electrons near the axis are accelerated longitudinally by the ponderomotive force of the colliding pulses, accelerated transversely by the beat wave, and subsequently injected into the second bucket of the wake. Ionization is used to increase the transverse injection area and the final trapped charge. Simulations show that the transverse emittance can be less than the 0.1 mm mrad level, which is important for many applications. For colliding laser pulses with different frequencies, the beat wave can produce asymmetric injection, which can enhance betatron radiation generated by the electron beam.

  18. On the focused beam parameters of an electron gun with a plasma emitter

    Science.gov (United States)

    Kornilov, S.; Rempe, N.; Beniyash, A.; Murray, N.

    2014-11-01

    The report presents the measurement results of the focused beam brightness in the electron gun with plasma emitter. The beam brightness was approximately 1010 A·m-2·sr-1 under the beam power up to 4 kW and an electron energy of 60 keV at the focal distance of 0.5 m. Qualitative assessment of the beam parameters was performed by welding test pieces. The results describing the possibility in principle of using the guns with a plasma emitter in nonvacuum technological devices are presented.

  19. On the focused beam parameters of an electron gun with a plasma emitter

    OpenAIRE

    S. Kornilov; Rempe, N.; Beniyash, Alexander; Murray, Nils

    2014-01-01

    The report presents the measurement results of the focused beam brightness in the electron gun with plasma emitter. The beam brightness was approximately 1010 A·m-2·sr-1 under the beam power up to 4 kW and an electron energy of 60 keV at the focal distance of 0.5 m. Qualitative assessment of the beam parameters was performed by welding test pieces. The results describing the possibility in principle of using the guns with a plasma emitter in nonvacuum technological devices are presented.

  20. Practical dc SQUID system: Devices and electronics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guofeng [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Joint Research Laboratory on Superconductivity and Bioelectronics, Collaboration between CAS-Shanghai and FZJ (Germany); Zhang, Yi, E-mail: y.zhang@fz-juelich.de [Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany); Joint Research Laboratory on Superconductivity and Bioelectronics, Collaboration between CAS-Shanghai and FZJ (Germany); Hong, Tao; Wang, Hai [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Joint Research Laboratory on Superconductivity and Bioelectronics, Collaboration between CAS-Shanghai and FZJ (Germany); University of Chinese Academy of Sciences, Beijing 100049 (China); Krause, Hans-Joachim [Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany); Joint Research Laboratory on Superconductivity and Bioelectronics, Collaboration between CAS-Shanghai and FZJ (Germany); Xie, Xiaoming [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Joint Research Laboratory on Superconductivity and Bioelectronics, Collaboration between CAS-Shanghai and FZJ (Germany)

    2015-11-15

    Highlights: • The current noise contribution in direct readout scheme for dc SQUID was analyzed. • A current feedback circuit for suppressing the current noise was introduced. • Two criteria to measure the suppression factor were introduced. • A practical SQUID system with acceptable noise performance was suggested. - Abstract: In order to set up a liquid helium-cooled practical dc SQUID system with acceptable noise figure, we employ a weakly damped dc SQUID with a large flux-to-voltage transfer coefficient ∂V/∂Φ in a direct readout scheme (DRS) without flux modulation. Two preamplifiers are utilized: (1) AD 797 for a so-called “single chip readout electronics” (SCRE); (2) 6 parallel-connected bipolar transistors (PCBT). The latter reduces the preamplifier voltage noise V{sub n} but increases its current noise I{sub n}, which plays a leading role in the system low-frequency noise. We introduce a current feedback circuit (CFC) consisting of an inductor L{sub i} coupled to the SQUID with mutual inductance M{sub i} to improve the noise performance. In this work, the preamplifier I{sub n} contribution and CFC are analyzed. To evaluate the I{sub n} suppression with CFC, two criteria are presented. Furthermore, we establish a dimensionless parameter ξ to describe CFC quantitatively. The system noise is compared with and without CFC using the two preamplifiers. For a dc SQUID with a loop inductance of 350 pH, an intrinsic noise of about 5 μΦ{sub 0}/√Hz and a corner frequency at 2 Hz are measured using PCBT with CFC.

  1. Emittance Measurements of the Jefferson Lab Free Electron Laser using optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Holloway, Michael Andrew [Univ. of Maryland, College Park, MD (United States)

    2007-05-01

    Charged particle accelerators, such as the ones that power Free Electron Lasers (FEL), require high quality (low emittance) beams for efficient operation. Accurate and reliable beam diagnostics are essential to monitoring beam parameters in order to maintain a high quality beam. Optical Transition Radiation Interferometry (OTRI) has shown potential to be a quality diagnostic that is especially useful for high brightness electron beams such as Jefferson Labs FEL energy recovery linac. The purpose of this project is to further develop OTRI beam diagnostic techniques. An optical system was designed to make beam size and divergence measurements as well as to prepare for experiments in optical phase space mapping. Beam size and beam divergence measurements were taken to calculate the emittance of the Jefferson Lab FEL. OTRI is also used to separate core and halo beam divergences in order to estimate core and halo emittance separately.

  2. Measurements of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes

    Directory of Open Access Journals (Sweden)

    Yosuke Honda

    2003-09-01

    Full Text Available We present the measurement results of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes. The measurements were carried out with an upgraded laser wire beam profile monitor. The monitor has now a vertical wire as well as a horizontal one and is able to make much faster measurements thanks to an increased effective laser power inside the cavity. The measured emittance shows no large bunch-to-bunch dependence in either the horizontal or vertical directions. The values of the vertical emittance are similar to those obtained in the single-bunch operation. The present results are an important step toward the realization of a high-energy linear collider.

  3. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Science.gov (United States)

    Shih, Yi-Ting; Li, Kuan-Wei; Honda, Shin-ichi; Lin, Pao-Hung; Huang, Ying-Sheng; Lee, Kuei-Yi

    2017-06-01

    The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75-85% range. The proposed design provides a facile new method for developing SED applications.

  4. Multi-field electron emission pattern of 2D emitter: Illustrated with graphene

    Science.gov (United States)

    Luo, Ma; Li, Zhibing

    2016-11-01

    The mechanism of laser-assisted multi-field electron emission of two-dimensional emitters is investigated theoretically. The process is basically a cold field electron emission but having more controllable components: a uniform electric field controls the emission potential barrier, a magnetic field controls the quantum states of the emitter, while an optical field controls electron populations of specified quantum states. It provides a highly orientational vacuum electron line source whose divergence angle over the beam plane is inversely proportional to square root of the emitter height. Calculations are carried out for graphene with the armchair emission edge, as a concrete example. The rate equation incorporating the optical excitation, phonon scattering, and thermal relaxation is solved in the quasi-equilibrium approximation for electron population in the bands. The far-field emission patterns, that inherit the features of the Landau bands, are obtained. It is found that the optical field generates a characteristic structure at one wing of the emission pattern.

  5. Quantum efficiency and thermal emittance of metal photocathodes

    Directory of Open Access Journals (Sweden)

    David H. Dowell

    2009-07-01

    Full Text Available Modern electron beams have demonstrated the brilliance needed to drive free electron lasers at x-ray wavelengths with major advances occurring since the invention of the photocathode gun and the realization of emittance compensation. These state-of-the-art electron beams are now becoming limited by the intrinsic thermal emittance of the cathode. In both dc and rf photocathode guns details of the cathode emission physics strongly influence the quantum efficiency and the thermal emittance. Therefore improving cathode performance is essential to increasing the brightness of beams. It is especially important to understand the fundamentals of cathode quantum efficiency and thermal emittance. This paper investigates the relationship between the quantum efficiency and the thermal emittance for metal cathodes using the Fermi-Dirac model for the electron distribution. We use a consistent theory to derive the quantum efficiency and thermal emittance, and compare our results to those of others.

  6. Ultra-low emittance electron beam generation using ionization injection in a plasma beatwave accelerator

    Science.gov (United States)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    Ultra-low emittance beams can be generated using ionization injection of electrons into a wakefield excited by a plasma beatwave accelerator. This all-optical method of electron beam generation uses three laser pulses of different colors. Two long-wavelength laser pulses, with frequency difference equal to the plasma frequency, resonantly drive a plasma wave without fully ionizing a gas. A short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the beating long-wavelength lasers, ionizes a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wakefield. Using the beating of long-wavelength pulses to generate the wakefield enables atomically-bound electrons to remain at low ionization potentials, reducing the required amplitude of the ionization pulse, and, hence, the initial transverse momentum and emittance of the injected electrons. An example is presented using two lines of a CO2 laser to form a plasma beatwave accelerator to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection. Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  7. Asymmetrical field emitter

    Science.gov (United States)

    Fleming, J.G.; Smith, B.K.

    1995-10-10

    A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

  8. Low-emittance thermionic-gun-based injector for a compact free-electron laser

    Science.gov (United States)

    Asaka, Takao; Ego, Hiroyasu; Hanaki, Hirohumi; Hara, Toru; Hasegawa, Taichi; Hasegawa, Teruaki; Inagaki, Takahiro; Kobayashi, Toshiaki; Kondo, Chikara; Maesaka, Hirokazu; Matsubara, Shinichi; Matsui, Sakuo; Ohshima, Takashi; Otake, Yuji; Sakurai, Tatsuyuki; Suzuki, Shinsuke; Tajiri, Yasuyuki; Tanaka, Shinichiro; Togawa, Kazuaki; Tanaka, Hitoshi

    2017-08-01

    A low-emittance thermionic-gun-based injector was developed for the x-ray free-electron laser (XFEL) facility known as the SPring-8 angstrom compact free-electron laser (SACLA). The thermionic-gun-based system has the advantages of maintainability, reliability, and stability over a photocathode radio-frequency (rf) gun because of its robust thermionic cathode. The basic performance of the injector prototype was confirmed at the SPring-8 compact self-amplified spontaneous emission source (SCSS) test accelerator, where stable FEL generation in an extreme ultraviolet wavelength range was demonstrated. The essential XFEL innovation is the achievement of a constant beam peak current of 3-4 kA, which is 10 times higher than that generated by the SCSS test accelerator, while maintaining a normalized-slice emittance below 1 mm mrad. Thus, the following five modifications were applied to the SACLA injector: (i) a nonlinear energy chirp correction; (ii) the optimization of the rf acceleration frequency; (iii) rf system stabilization; (iv) nondestructive beam monitoring; and (v) a geomagnetic field correction. The SACLA injector successfully achieved the target beam performance, which shows that a thermionic-gun-based injector is applicable to an XFEL accelerator system. This paper gives an overview of the SACLA injector and describes the physical and technical details, together with the electron beam performance obtained in the beam commissioning.

  9. Low-emittance thermionic-gun-based injector for a compact free-electron laser

    Directory of Open Access Journals (Sweden)

    Takao Asaka

    2017-08-01

    Full Text Available A low-emittance thermionic-gun-based injector was developed for the x-ray free-electron laser (XFEL facility known as the SPring-8 angstrom compact free-electron laser (SACLA. The thermionic-gun-based system has the advantages of maintainability, reliability, and stability over a photocathode radio-frequency (rf gun because of its robust thermionic cathode. The basic performance of the injector prototype was confirmed at the SPring-8 compact self-amplified spontaneous emission source (SCSS test accelerator, where stable FEL generation in an extreme ultraviolet wavelength range was demonstrated. The essential XFEL innovation is the achievement of a constant beam peak current of 3–4 kA, which is 10 times higher than that generated by the SCSS test accelerator, while maintaining a normalized-slice emittance below 1 mm mrad. Thus, the following five modifications were applied to the SACLA injector: (i a nonlinear energy chirp correction; (ii the optimization of the rf acceleration frequency; (iii rf system stabilization; (iv nondestructive beam monitoring; and (v a geomagnetic field correction. The SACLA injector successfully achieved the target beam performance, which shows that a thermionic-gun-based injector is applicable to an XFEL accelerator system. This paper gives an overview of the SACLA injector and describes the physical and technical details, together with the electron beam performance obtained in the beam commissioning.

  10. Precision Control of the Electron Longitudinal Bunch Shape Using an Emittance-Exchange Beam Line.

    Science.gov (United States)

    Ha, G; Cho, M H; Namkung, W; Power, J G; Doran, D S; Wisniewski, E E; Conde, M; Gai, W; Liu, W; Whiteford, C; Gao, Q; Kim, K-J; Zholents, A; Sun, Y-E; Jing, C; Piot, P

    2017-03-10

    We report on the experimental generation of relativistic electron bunches with a tunable longitudinal bunch shape. A longitudinal bunch-shaping (LBS) beam line, consisting of a transverse mask followed by a transverse-to-longitudinal emittance exchange (EEX) beam line, is used to tailor the longitudinal bunch shape (or current profile) of the electron bunch. The mask shapes the bunch's horizontal profile, and the EEX beam line converts it to a corresponding longitudinal profile. The Argonne wakefield accelerator rf photoinjector delivers electron bunches into a LBS beam line to generate a variety of longitudinal bunch shapes. The quality of the longitudinal bunch shape is limited by various perturbations in the exchange process. We develop a simple method, based on the incident slope of the bunch, to significantly suppress the perturbations.

  11. Multiobjective optimizations of a novel cryocooled dc gun based ultrafast electron diffraction beam line

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2016-09-01

    Full Text Available We present the results of multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line utilizing a 225 kV dc gun with a novel cryocooled photocathode system and buncher cavity. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed for three different sample radii: 50, 100, and 200  μm, for two final bunch charges: 10^{5} electrons (16 fC and 10^{6} electrons (160 fC. Example optimal solutions are analyzed, and the effects of disordered induced heating estimated. In particular, a relative coherence length of L_{c,x}/σ_{x}=0.27  nm/μm was obtained for a final bunch charge of 10^{5} electrons and final bunch length of σ_{t}≈100  fs. For a final charge of 10^{6} electrons the cryogun produces L_{c,x}/σ_{x}≈0.1  nm/μm for σ_{t}≈100–200  fs and σ_{x}≥50  μm. These results demonstrate the viability of using genetic algorithms in the design and operation of ultrafast electron diffraction beam lines.

  12. Numerical calculations of the electron beam emittance for laser acceleration experiments

    Science.gov (United States)

    Balascuta, Septimiu

    2017-06-01

    At the E6 experimental area at ELI-NP, two 10 PW Laser (pump and probe) pulses, with their directions making an 135° angle, will be used for the study of the radiation reaction, non-linear Thomson scattering, electron beam cooling and other QED phenomena in the relativistic regime. The pump 10 PW Laser beam focused in a gas-jet will generate a plasma wakefield that accelerate electrons by self-injection. The probe 10PW Laser pulse has to be synchronized and focused on the electron bunch. In order to maximize the flux of gamma rays produced in this collision, for a given Laser field intensity, the transversal area of the electron beam at the collision point has to be smaller than the focus of the probe pulse. This work presents the calculation of electron beam emittance and angular divergence, versus the distance traveled by electron bunch in vacuum. A configuration of dipole permanent magnets is proposed for the study of energy distribution of electrons and positrons.

  13. Monolayer graphene-insulator-semiconductor emitter for large-area electron lithography

    Science.gov (United States)

    Kirley, Matthew P.; Aloui, Tanouir; Glass, Jeffrey T.

    2017-06-01

    The rapid adoption of nanotechnology in fields as varied as semiconductors, energy, and medicine requires the continual improvement of nanopatterning tools. Lithography is central to this evolving nanotechnology landscape, but current production systems are subject to high costs, low throughput, or low resolution. Herein, we present a solution to these problems with the use of monolayer graphene in a graphene-insulator-semiconductor (GIS) electron emitter device for large-area electron lithography. Our GIS device displayed high emission efficiency (up to 13%) and transferred large patterns (500 × 500 μm) with high fidelity (<50% spread). The performance of our device demonstrates a feasible path to dramatic improvements in lithographic patterning systems, enabling continued progress in existing industries and opening opportunities in nanomanufacturing.

  14. Geometry Optimization of DC/RF Photoelectron Gun

    CERN Document Server

    Chen Ping; Yu, David

    2005-01-01

    Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

  15. Wide Temperature Range DC-DC Boost Converters for Command/Control/Drive Electronics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We shall develop wide temperature range DC-DC boost converters that can be fabricated using commercial CMOS foundries. The boost converters will increase the low...

  16. Experimental Development of Low-emittance Field-emission Electron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Lueangaranwong, A. [Northern Illinois Univ., DeKalb, IL (United States). Northern Illinois Center for Accelerator & Detector Development; Buzzard, C. [Northern Illinois Univ., DeKalb, IL (United States); Divan, R. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Korampally, V. [Northern Illinois Univ., DeKalb, IL (United States); Piot, P. [Northern Illinois Univ., DeKalb, IL (United States). Northern Illinois Center for Accelerator & Detector Development; Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-10-10

    Field emission electron sources are capable of extreme brightness when excited by static or time-dependent electro- magnetic fields. We are currently developing a cathode test stand operating in DC mode with possibility to trigger the emission using ultra-short (~ 100-fs) laser pulses. This contribution describes the status of an experiment to investigate field-emission using cathodes under development at NIU in collaboration with the Argonne’s Center for Nanoscale Materials.

  17. Design and characterization of the DC acceleration and transport system required for the FOM 1 MW free electron maser experiment

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M. [Lawrence Livermore National Lab., CA (United States); Urbanus, W.H.; Geer, C. van der [FOM-Institut voor Plasma Fysica, Nieuwegein (Netherlands)] [and others

    1995-12-31

    A Free Electron Maser (FEM) has been constructed and is soon to be tested at the FOM Institute (Rijnhuizen) Netherlands with the goal of producing 1 MW long pulse to CW microwave output in the range 130 GHz to 250 GHz. The design uses a DC beam system in a depressed collector configuration in order to make the overall wall plug efficiency 50%. The high voltage ({approximately} 2 MeV) power supply provides only the body interception current ({approximately} 30 mA) while the 12 amp beam current is supplied by the 100-200 keV collector supplies. Some of the design features to ensure low interception current, which is critical to long pulse (CW) operation are: (1) DC beam in-line transport and acceleration system, (2) emittance conserving solenoid focusing system, (3) halo suppression techniques at cathode edge, and (4) very low beam fill factor (<20%). A relativistic version of the Herman Optical theory developed for microwave tubes is used to determine current distribution functions everywhere along the beam from the electron gun, through the DC accelerator and transport system to the wiggler. This theory takes into account thermals far out on the gaussian tail which translates into beam current far outside the ideal beam edge. This theory is applied to the FOM beam line design to predict a series of beam envelope contours containing various percentages of total beam current up to 99.9%. Predictions of body interception current due to finite emittance (effective temperature) are presented and compared with measured experimental results.

  18. Flexible control of femtosecond pulse duration and separation using an emittance-spoiling foil in x-ray free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Behrens, C. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Coffee, R. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Decker, F. -J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Emma, P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Field, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Helml, W. [Technische Univ. Munchen, Garching (Germany); Huang, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Krejcik, P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Krzywinski, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Loos, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lutman, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Marinelli, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Maxwell, T. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Turner, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-06-22

    We report experimental studies of generating and controlling femtosecond x-ray pulses in free-electron lasers (FELs) using an emittance spoiling foil. By selectivity spoiling the transverse emittance of the electron beam, the output pulse duration or double-pulse separation is adjusted with a variable size single or double slotted foil. Measurements were performed with an X-band transverse deflector located downstream of the FEL undulator, from which both the FEL lasing and emittance spoiling effects are observed directly.

  19. Anisotropic electrical transport of flexible tungsten carbide nanostructures: towards nanoscale interconnects and electron emitters

    Science.gov (United States)

    Sun, Bo; Sun, Yong; Wang, Chengxin

    2017-11-01

    Due to the coexistence of metal- and ionic-bonds in a hexagonal tungsten carbide (WC) lattice, disparate electron behaviors were found in the basal plane and along the c-axial direction, which may create an interesting anisotropic mechanical and electrical performance. To demonstrate this, low-dimensional nanostructures such as nanowires and nanosheets are suitable for investigation because they usually grow in single crystals with special orientations. Herein, we report the experimental research regarding the anisotropic conductivity of [0001] grown WC nanowires and basal plane-expanded nanosheets, which resulted in a conductivity of 7.86 × 103 Ω-1 · m-1 and 7.68 × 104 Ω-1 · m-1 respectively. This conforms to the fact that the highly localized W d state aligns along the c direction, while there is little intraplanar directional bonding in the W planes. With advanced micro-manipulation technology, the conductivity of a nanowire was tested to be approximately constant, even under a considerable bending state. Moreover, the field electron emission of WC was evaluated based on large area emission and single nanowire (nanosheet) emission. A single nanowire exhibits a stable electron emission performance, which can output emission currents >3 uA before fusing. These results provide useful references to assess low-dimensional WC nanostructures as electronic materials in flexible devices, such as nanoscale interconnects and electron emitters.

  20. High stability electron field emitters made of nanocrystalline diamond coated carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, K. J.; Tai, N. H., E-mail: nhtai@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Srinivasu, K.; Leou, K. C. [Department of Engineering and System Science, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Lin, I. N., E-mail: inanlin@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

    2013-12-16

    We report enhanced life-time stability for the electron field emitters prepared by coating nanocrystalline diamond (NCD) on carbon nanotubes (CNTs). Upon overcoming the problem of poor stability in CNTs, the NCD-CNTs exhibit excellent life-time stability of 250 min tested at different applied voltages of 600 and 900 V. In contrast, the life-time stability of CNTs is only 33 min even at relatively low voltage of 360 V and starts arcing at 400 V. Hence, the NCD-CNTs with improved life-time stability have great potential for the applications as cathodes in flat panel displays and microplasma display devices.

  1. 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.

  2. Initial observations of high-charge, low-emittance electron beams at HIBAF (High Brightness Accelerator FEL)

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.; Feldman, R.B.; Carsten, B.E.; Feldman, D.W.; Sheffield, R.L.; Stein, W.E.; Johnson, W.J.; Thode, L.E.; Bender, S.C.; Busch, G.E.

    1990-01-01

    We report our initial measurements of bright (high-charge, low-emittance) electron beams generated at the Los Alamos High Brightness Accelerator FEL (HIBAF) Facility. Normalized emittance values of less than 50 {pi} mm-mrad for charges ranging from 0.7 to 8.7 nC were obtained for single micropulses at a y-waist and at an energy of 14.7 MeV. These measurements were part of the commissioning campaign on the HIBAF photoelectric injector. Macropulse measurements have also been performed and are compared with PARMELA simulations. 5 refs., 8 figs., 3 tabs.

  3. Emittance and Energy Diagnostics for Electron Beams with Large Momentum Spread

    CERN Document Server

    Olvegård, Maja; Thibaut, Lefevre; Enrico, Bravin

    Olvegård, M. 2013. Emittance and Energy Diagnostics for Electron Beams with Large Momentum Spread. Acta Universitatis Upsaliensis. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1036. 75 pp. Uppsala. ISBN 978-91-554-8646-4. Following the discovery of the Higgs-like boson at the Large Hadron Collider, there is demand for precision measurements on recent findings. The Compact Linear Collider, CLIC, is a candidate for a future linear electron-positron collider for such precision measurements. In CLIC, the beams will be brought to collisions in the multi-TeV regime through high gradient acceleration with high frequency RF power. A high intensity electron beam, the so-called drive beam, will serve as the power source for the main beam, as the drive beam is decelerated in special structures, from which power is extracted and transfered to the main beam. When the drive beam is decelerated the beam quality deteriorates and the momentum spread increases, which make...

  4. Ion Emittance Growth Due to Focusing Modulation from Slipping Electron Bunch

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-02-17

    Low energy RHIC operation has to be operated at an energy ranging from γ = 4.1 to γ = 10. The energy variation causes the change of revolution frequency. While the rf system for the circulating ion will operate at an exact harmonic of the revolution frequency (h=60 for 4.5 MHz rf and h=360 for 28 MHz rf.), the superconducting rf system for the cooling electron beam does not have a frequency tuning range that is wide enough to cover the required changes of revolution frequency. As a result, electron bunches will sit at different locations along the ion bunch from turn to turn, i.e. the slipping of the electron bunch with respect to the circulating ion bunch. At cooling section, ions see a coherent focusing force due to the electrons’ space charge, which differs from turn to turn due to the slipping. We will try to estimate how this irregular focusing affects the transverse emittance of the ion bunch.

  5. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Directory of Open Access Journals (Sweden)

    Richard Talman

    2009-01-01

    Full Text Available Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004; R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006, Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes: (i Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel et al., Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000NIMAER0168-900210.1016/S0168-9002(0000729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]. All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance ϵ_{x} on beam width (as controlled by the lattice β_{x} function at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening et al., in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001, http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR. (ii A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the

  6. Simulation study of electron cloud induced instabilities and emittance growth for the CERN Large Hadron Collider proton beam

    CERN Document Server

    Benedetto, Elena; Schulte, Daniel; Rumolo, Giovanni

    2005-01-01

    The electron cloud may cause transverse single-bunch instabilities of proton beams such as those in the Large Hadron Collider (LHC) and the CERN Super Proton Synchrotron (SPS). We simulate these instabilities and the consequent emittance growth with the code HEADTAIL, which models the turn-by-turn interaction between the cloud and the beam. Recently some new features were added to the code, in particular, electric conducting boundary conditions at the chamber wall, transverse feedback, and variable beta functions. The sensitivity to several numerical parameters has been studied by varying the number of interaction points between the bunch and the cloud, the phase advance between them, and the number of macroparticles used to represent the protons and the electrons. We present simulation results for both LHC at injection and SPS with LHC-type beam, for different electron-cloud density levels, chromaticities, and bunch intensities. Two regimes with qualitatively different emittance growth are observed: above th...

  7. Quasiperiodicity and Torus Breakdown in a Power Electronic DC/DC Converter

    DEFF Research Database (Denmark)

    Zhusubaliyev, Zhanybai; Soukhoterin, Evgeniy; Mosekilde, Erik

    2007-01-01

    This paper discusses the mechanisms of torus formation and torus destruction in a dc/dc converter with relay control and hysteresis. We establish a chart of the dynamical modes in the input voltage versus load resistance parameter plane. This chart displays several different torus bifurcations al......). Particular emphasis is paid to following the changes of the stable and unstable manifolds in detail. (c) 2006 Published by Elsevier B.V. on behalf of IMACS....

  8. Reliability of Capacitors for DC-Link Applications in Power Electronic Converters

    DEFF Research Database (Denmark)

    Wang, Huai; Blaabjerg, Frede

    2014-01-01

    DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of dc link in power electronic converters...... from two aspects: 1) reliability-oriented dc-link design solutions; 2) conditioning monitoring of dc-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics...

  9. Resonant transition radiation in the X-ray region from a low emittance 855 MeV electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Backe, H. (Inst. fuer Physik, Univ. Mainz (Germany)); Gampert, S. (Inst. fuer Physik, Univ. Mainz (Germany)); Grendel, A. (Inst. fuer Physik, Univ. Mainz (Germany)); Hartmann, H.J. (Inst. fuer Physik, Univ. Mainz (Germany)); Lauth, W.; Weinheimer, C.; Zahn, R. (Inst. fuer Physik, Univ. Mainz (Germany)); Buskirk, F.R. (Inst. fuer Kernphysik, Univ. Mainz (Germany)); Euteneuer, H. (Inst. fuer Kernphysik, Univ. Mainz (Germany)); Kaiser, K.H. (Inst. fuer Kernphysik, Univ. Mainz (Germany)); Stephan, G. (Inst. fuer Kernphysik, Univ. Mainz (Germany)); Walcher, T. (Inst. fuer Kernphysik, Univ. Mainz (Germany))

    1994-07-01

    The interference of transition radiation coherently produced from a periodic stack of four polyimide foils of 7.2 [mu]m thickness and a separation of 162 [mu]m was investigated. This stack has been brought into the low emittance (3 [pi] nm rad) electron beam of the 855 MeV Mainz Microtron MAMI. Transition radiation was observed in the energy range from 2 to 15 keV with a LN[sub 2]-cooled pin photodiode. A good energy resolution of 0.8 keV and angular resolution of 0.15 mrad was achieved simultaneously allowing for the first time to quantitatively study the interference pattern. Good agreement with theoretical calculations is found. Prospects to exploit transition radiation in the x-ray region from a low emittance electron beam as a high brilliant radiation source are discussed. (orig.)

  10. Electron emission from MOS electron emitters with clean and cesium covered gold surface

    DEFF Research Database (Denmark)

    Nielsen, Gunver; Thomsen, Lasse Bjørchmar; Johansson, Martin

    2009-01-01

    characteristics have been investigated. It is known, that deposition of an alkali metal on the emitting surface lowers the work function and increases the emission efficiency. For increasing Cs coverages the surface has been characterized by X-ray Photoelectron Spectroscopy (XPS), Ion Scattering Spectroscopy (ISS......) and work function measurements. Energy spectra of electron emission from the devices under an applied bias voltage have been recorded for the clean Au surface and for two Cs coverages and simultaneous work function curves have been obtained. The electron emission onset is seen to appear at the surface work...... function. A method for cleaning the ex situ deposited Au top electrodes to a degree satisfactory to surface science studies has been developed, and a threshold for oxide damage by low-energy ion exposure between 0.5 and 1 keV has been determined....

  11. Current gain above 10 in sub-10 nm base III-Nitride tunneling hot electron transistors with GaN/AlN emitter

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhichao, E-mail: zcyang.phys@gmail.com; Zhang, Yuewei; Krishnamoorthy, Sriram; Nath, Digbijoy N. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Khurgin, Jacob B. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-05-09

    We report on a tunneling hot electron transistor amplifier with common-emitter current gain greater than 10 at a collector current density in excess of 40 kA/cm{sup 2}. The use of a wide-bandgap GaN/AlN (111 nm/2.5 nm) emitter was found to greatly improve injection efficiency of the emitter and reduce cold electron leakage. With an ultra-thin (8 nm) base, 93% of the injected hot electrons were collected, enabling a common-emitter current gain up to 14.5. This work improves understanding of the quasi-ballistic hot electron transport and may impact the development of high speed devices based on unipolar hot electron transport.

  12. Wide Temperature DC Link Capacitors for Aerospace Power Electronics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop advanced DC link capacitors using flexible ultrathin glass dielectric materials. The glass capacitor will be able to be operated in a broad...

  13. Investigation of slice emittance using an energy-chirped electron beam in a dispersive section for photo injector characterization at PITZ

    Energy Technology Data Exchange (ETDEWEB)

    Ivanisenko, Yevgeniy

    2012-06-15

    This work describes a transverse slice emittance diagnostics with an RMS temporal resolution down to 2 ps that was implemented at the Photo Injector Test facility in Zeuthen (PITZ). The measurements were performed for several bunch charges generated by a laser pulse that has a flat-top temporal profile of 21-22 ps FWHM duration. This diagnostics allows to study the beam projected emittance compensation with a solenoid magnetic field experimentally and therefore contributes to the beam emittance optimization for the needs of short wavelength linac-based FELs in particular. The diagnostics is based upon the usage of electron bunches which have a correlation between the longitudinal position and the momentum of the bunch particles. This property allows to convert the bunch longitudinal distribution into a transverse one in a dipole magnet. A slit with a narrow opening at the dipole exit selects a fraction of the particle ensemble, a slice, which emittance is analyzed at a screen downstream. Slit scan and quadrupole scan techniques can be used to measure the emittance of the slices. In the experiments it was found that the slice emittance values are 5-10% lower than the projected emittance values, indicating a good effectivity of the solenoid compensation. The emittance obtained using quadrupole scan technique has shown different results when compared to slit scan technique due to a beam halo. The observed beam halo in phase space contributes up to 40% of the emittance value while having only 10% of the bunch charge.

  14. Inexpensive robots used to teach dc circuits and electronics

    Science.gov (United States)

    Sidebottom, David L.

    2017-05-01

    This article describes inexpensive, autonomous robots, built without microprocessors, used in a college-level introductory physics laboratory course to motivate student learning of dc circuits. Detailed circuit descriptions are provided as well as a week-by-week course plan that can guide students from elementary dc circuits, through Kirchhoff's laws, and into simple analog integrated circuits with the motivational incentive of building an autonomous robot that can compete with others in a public arena.

  15. Development of DNA-based radiopharmaceuticals carrying Auger-electron emitters for anti-gene radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Panyutin, I.G.; Winters, T.A.; Feinendegen, L.E.; Neumann, R.D. [National Institutes of Health, Bethesda, MD (United States). Dept. of Nuclear Medicine

    2000-09-01

    Targeting of radiation damage to specific DNA sequences is the essence of antigen radiotherapy. This technique also provides a tool to study molecular mechanisms of DNA repair on a defined, single radio damaged site. It was achieved such sequence-specific radio damage by combining the highly localized DNA damage produced by the decay of Auger-electron-emitters such as {sup 125}I with the sequence-specific action of triplex-forming oligonucleotides (TFO). TFO complementary to polypurine-polypyrimidine regions of human genes were synthesized and labeled with {sup 125}I-dCTP by the primer extension method. {sup 125}I-TFO were delivered into cells with several delivery systems. In addition, human enzymes capable of supporting DNA single-strand-break repair were isolated and assessed for their role in the repair of this lesion. Also, the mutagenicity and repairability of {sup 125}I-TFO-induced double strand breaks (DSB) were assessed by repair of plasmid possessing a site-specific DSB lesion. Using plasmids containing target polypurine-polypyrimidine tracts, it was obtained the fine structure of sequence-specific DNA breaks produced by decay of {sup 125}I with single-nucleotide resolution. It was showed that the designed {sup 125}I-TFO in nanomolar concentrations could bind to and introduce double-strand breaks into the target sequences in situ, i.e., within isolated nuclei and intact digitonin-permeabilized cells. It was also showed {sup 125}I-TFO-induced DSB to be highly mutagenic lesions resulting in a mutation frequency of nearly 80%, with deletions comprising the majority of mutations. The results obtained demonstrate the ability of {sup 125}I-TFO to target specific sequences in their natural environment - within eukaryotic nucleus. Repair of {sup 125}I-TFO-induced DNA damage should typically result in mutagenic gene inactivation.

  16. Power Electronic Systems for Switched Reluctance Generator based Wind Farms and DC Networks

    DEFF Research Database (Denmark)

    Park, Kiwoo

    . Under these circumstances, research on dc network connection with a novel wind power generator system is presented in this thesis, which mainly consists of two major parts: control of a Switched Reluctance Generator (SRG) system and development of dc-dc converters for a dc network system in a wind farm...... components into the torque reference to compensate the ripples in the actual output torque. The effectiveness and resulting improvement in the performance of both the proposed speed controller and torque minimization technique are demonstrated by simulation results. The modern power electronic interfaces...

  17. Obtaining the high-current low-energy electron beams in the systems with a plasma emitter

    CERN Document Server

    Devyatkov, V N; Shchanin, P M

    2001-01-01

    Using gas filled diodes with arc and glow-discharge base plasma emitters one investigated into generation and transfer of high-current electron beams. Using a diode with arc discharge base plasma emitter at 15 kV accelerating voltage one obtained a space charge compensated with up to 1 kA current compressed by proper magnetic field from 8 cm diameter up to 1 cm and transported at over 20 cm distance with 70% efficiency. Using a diode with a glow-discharge one obtained a 80 A current and up to 100 A/cm current density beam. In a weak axial magnetic field with B=0.015 T induction such a beam is transported at 30 cm distance

  18. Double emittance exchanger as a bunch compressor for the MaRIE XFEL electron beam line at 1 GeV

    Science.gov (United States)

    Malyzhenkov, Alexander; Carlsten, Bruce E.; Yampolsky, Nikolai A.

    2017-03-01

    We demonstrate an alternative realization of a bunch compressor (specifically, the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space. We compare our results with a traditional bunch compressor realized via a chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beamline, and analyze the evolution of the eigen-emittances to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR effects in our scheme, resulting in critical emittance growth, and introduce an alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  19. Double Emittance Exchanger as a Bunch Compressor for the MaRIE XFEL electron beam line at 1GeV

    Energy Technology Data Exchange (ETDEWEB)

    Malyzhenkov, Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Northern Illinois Univ., DeKalb, IL (United States); Yampolsky, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carlsten, Bruce Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-22

    We demonstrate an alternative realization of a bunch compressor (specifically the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space.We compare our results with a traditional bunch compressor realized via chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beam line and analyze the eigen-emittances evolution to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR-effects in our scheme resulting in critical emittance growth and introduce alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  20. The X-Ray Beam Imager for Transversal Profiling of Low-Emittance Electron Beam at the SPring-8

    CERN Document Server

    Takano, S; Ohkuma, H

    2005-01-01

    We have developed the X-ray beam imager (XBI) at the accelerator diagnostics beamline I of the SPring-8 to observe transverse profiles of small electron beam of a low-emittance synchrotron light source. The XBI is based on a single Fresnel zone plate (FZP) and an X-ray zooming tube (XZT). The electron beam moving in a bending magnet is imaged by the FZP. Monochromatic X-ray is selected by a double crystal monochromator to avoid the effect of chromatic aberration of the FZP. The X-ray images of the electron beam obtained are converted by the XZT to enlarged images in visible light. The XBI has achieved a superior 1 σ spatial resolution in the micron range, and a fast time resolution of 1 ms. It has also realized a vignetting-free field of view larger than 1.5 mm in diameter on the coordinates of the electron beam, which is not easily obtained by imaging optics using two FZPs. With the XBI, we have successfully measured the profiles of the small electron beam having low vertical emittance in the pm ra...

  1. High reliability DC/DC converter module for electronic boards equipped with FPGAs

    Science.gov (United States)

    Viganò, W.; Boccardi, A.; Zamantzas, C.

    2015-01-01

    The Beam Instrumentation Group at CERN is designing a new general-purpose VME carrier module utilising several PTH04T230W DC/DC converters. These off-the-shelf converters are built with unshielded inductors and need to be mounted on the printed circuit board as stand-alone components. Thus, reducing the global manageability and increasing the total cost of the carrier module. The new design aims to develop a module with better power dissipation, efficiency and reliability. In the future, it should be also possible to be directly integrated on the mainboard. For this reason, a Buck DC/DC converter has been implemented with the following main characteristics: input range from 3.0 V to 5.5 V; output range from 0.6 V to 3.3 V, settable by means of an external resistor; output current protection at 6 A; maximum output ripple ± 50 mVpp; switching frequency of 300KHz; short circuit protection; On/Off function; EMI reduction with frequency spread spectrum; soft-start function and thermal shutdown, in a 16 × 19 mm compact size. The selected buck controller is the TPS40303 integrated circuit and drives the CSD16321 power MOSFET, both from Texas Instruments. All selected components have been used at a minimum derating of 50% to reduce component stress and increase the reliability of this module. The selected inductors, i.e. Bourns SRP1055, are the main contributor for the high efficiency (95%), due to their very low equivalent series resistance. On the 4-layer PCB comprising all the components of this module, a snubber circuit, for further reduction of the output ripple due to the MOSFET ringing, can be mounted optionally. It is left as an option due to its effect on the total efficiency. The board layout has been optimized for maximum heat transfer and it can be used without active cooling. The board can maintain the maximum temperature on its surface, while at maximum current output, below 55°C at 25°C ambient temperature. An example of the electrical performance

  2. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator.

    Science.gov (United States)

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper.

  3. Space Charge Correction on Emittance Measurement of Low Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Treado, Colleen J.; /Massachusetts U., Amherst

    2012-09-07

    The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.

  4. Frequency Domain Modeling and Simulation of DC Power Electronic Systems Using Harmonic State Space Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    . Through this method, the required computation time and CPU memory can be reduced, where this faster simulation can be an advantage of a large network simulation. Besides, the achieved results show the same results as the non-linear time-domain simulation. Furthermore, the HSS modeling can describe how...... with different switching frequency or harmonics from ac-dc converters makes that harmonics and frequency coupling are both problems of ac system and challenges of dc system. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling...

  5. DC power supplies power management and surge protection for power electronic systems

    CERN Document Server

    Kularatna, Nihal

    2011-01-01

    Modern electronic systems, particularly portable consumer electronic systems and processor based systems, are power hungry, compact, and feature packed. This book presents the most essential summaries of the theory behind DC-DC converter topologies of both linear and switching types. The text discusses power supply characteristics and design specifications based on new developments in power management techniques and modern semiconductors entering into the portable electronics market. The author also addresses off-the-line power supplies, digital control of power supply, power supply protection

  6. Biodistribution of modular nanotransporter carrying Auger electron emitter and targeted at melanoma cells in murine tumor model

    Science.gov (United States)

    Vorontsova, M. S.; Morozova, N. B.; Karmakova, T. A.; Rosenkranz, A. A.; Slastnikova, T. A.; Petriev, V. M.; Smoryzanova, O. A.; Tischenko, V. K.; Yakubovskaya, R. I.; Kaprin, A. D.; Sobolev, A. S.

    2017-09-01

    Recombinant modular nanotransporter containing α-melanocyte-stimulating hormone peptide sequence (MNT-MSH) as a ligand module was designed for nucleus-targeted delivery of cytotoxic agents into melanoma cells. MNT-MSH radiolabeled with Auger electron emitter (111In-NOTA-MNT-MSH) showed a high antitumor efficacy in mice bearing syngeneic melanoma after intratumoral (i.t.) injection. This study is aimed at evaluating the biodistribution of the radioconjugate in melanoma tumor model in vivo. 111In-NOTA-MNT-MSH was administered i.t. in C57Bl/6j mice bearing subcutaneously implanted B16-F1 murine melanoma cells, expressing high levels of MCR1. The tissue uptake of radioactivity was determined ex vivo by γ-counter measurements. The intravenous route of administration did not provide a desirable level of radioactivity accumulation in the tumor, possibly, due to a high uptake of the transporter in liver tissue. After i.t. administration 111In-NOTA-MNT-MSH provided a high local retention of radionuclide, ranged from 400 to 350 %ID/g within at least 48 hours post-injection. MNT containing Auger electron emitter and α-MSH peptide as vector ligand could be a promising basis for radiopharmaceutical preparations intended for melanoma treatment.

  7. Low emittance electron beam generation from a laser wakefield accelerator using two laser pulses with different wavelengths

    Directory of Open Access Journals (Sweden)

    X. L. Xu

    2014-06-01

    Full Text Available Ionization injection triggered by short wavelength laser pulses inside a nonlinear wakefield driven by a longer wavelength laser is examined via multidimensional particle-in-cell simulations. We find that very bright electron beams can be generated through this two-color scheme in either collinear propagating or transverse colliding geometry. For a fixed laser intensity I, lasers with longer/shorter wavelength λ have larger/smaller ponderomotive potential (∝Iλ^{2}. The two-color scheme utilizes this property to separate the injection process from the wakefield excitation process. Very strong wakes can be generated at relatively low laser intensities by using a longer wavelength laser driver (e.g., a 10  μm CO_{2} laser due to its very large ponderomotive potential. On the other hand, a short wavelength laser can produce electrons with very small residual momenta (p_{⊥}∼a_{0}∼sqrt[I]λ inside the wake, leading to electron beams with very small normalized emittances (tens of nm. Using particle-in-cell simulations we show that a ∼10  fs electron beam with ∼4  pC of charge and a normalized emittance of ∼50  nm can be generated by combining a 10  μm driving laser with a 400 nm injection laser, which is an improvement of more than 1 order of magnitude compared to the typical results obtained when a single wavelength laser is used for both the wake formation and ionization injection. With the transverse colliding geometry, simulations show that similarly low emittance and much lower slice energy spread (∼30  keV, comparing with the typical value of few MeV in the longitudinal injection scheme can be simultaneously obtained for electron beams with a few pC charge. Such low slice energy spread may have significant advantages in applications relevant to future coherent light sources driven by plasma accelerators.

  8. Modeling and Simulation of DC Power Electronics Systems Using Harmonic State Space (HSS) Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2015-01-01

    based on the state-space averaging and generalized averaging, these also have limitations to show the same results as with the non-linear time domain simulations. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling....... Through this method, the required computation time and CPU memory for large dc power electronics systems can be reduced. Besides, the achieved results show the same results as with the non-linear time domain simulation, but with the faster simulation time which is beneficial in a large network....

  9. Formation of compressed flat electron beams with high transverse-emittance ratios

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J. [Fermilab; Institute of Fluid Physics, CAEP, China; Piot, P. [Northern Illinois University; Fermilab; Mihalcea, D. [Northern Illinois University; Prokop, C. R. [Northern Illinois University

    2014-08-01

    Flat beams—beams with asymmetric transverse emittances—have important applications in novel light-source concepts and advanced-acceleration schemes and could possibly alleviate the need for damping rings in lepton colliders. Over the last decade, a flat beam generation technique based on the conversion of an angular-momentum-dominated beam was proposed and experimentally tested. In this paper we explore the production of compressed flat beams. We especially investigate and optimize the flat beam transformation for beams with substantial fractional energy spread. We use as a simulation example the photoinjector of Fermilab’s Advanced Superconducting Test Accelerator. The optimizations of the flat beam generation and compression at Advanced Superconducting Test Accelerator were done via start-to-end numerical simulations for bunch charges of 3.2 nC, 1.0 nC, and 20 pC at ~37 MeV. The optimized emittances of flat beams with different bunch charges were found to be 0.25 μm (emittance ratio is ~400), 0.13 μm, 15 nm before compression, and 0.41 μm, 0.20 μm, 16 nm after full compression, respectively, with peak currents as high as 5.5 kA for a 3.2-nC flat beam. These parameters are consistent with requirements needed to excite wakefields in asymmetric dielectric-lined waveguides or produce significant photon flux using small-gap micro-undulators.

  10. Time-Resolved Electron Paramagnetic Resonance and Theoretical Investigations of Metal-Free Room-Temperature Triplet Emitters.

    Science.gov (United States)

    Matsuoka, Hideto; Retegan, Marius; Schmitt, Lisa; Höger, Sigurd; Neese, Frank; Schiemann, Olav

    2017-09-20

    Utilization of triplets is important for preparing organic light-emitting diodes with high efficiency. Very recently, both electrophosphorescence and electrofluorescence could be observed at room temperature for thienyl-substituted phenazines without any heavy metals ( Ratzke et al. J. Phys. Chem. Lett. , 2016 , 7 , 4802 ). It was found that the phosphorescence efficiency depends on the orientation of fused thiophenes. In this work, the thienyl-substituted phenazines are investigated in more detail by time-resolved electron paramagnetic resonance (EPR) and quantum chemical calculations. Spin dynamics, zero-field splitting constants, and electron-spin structures of the excited triplet states for the metal-free room-temperature triplet emitters are correlated with phosphorescence efficiency. Complete active space self-consistent field (CASSCF) calculations clearly show that the electron spin density distributions of the first excited triplet states are strongly affected by the molecular geometry. For the phosphorescent molecules, the electron spins are localized on the phenazine unit, in which the sulfur atom of the fused thiophene points upward. The electron spins are delocalized onto the thiophene unit just by changing the orientation of the fused thiophenes from upward to downward, resulting in the suppression of phosphorescence. Time-resolved EPR measurements and time-dependent density functional theory (TD-DFT) calculations demonstrate that the electron spins delocalized onto the thiophene unit lead to the acceleration of nonradiative decays, in conjunction with the narrowing of the singlet-triplet energy gap.

  11. Formation of compressed flat electron beams with high transverse-emittance ratios

    Directory of Open Access Journals (Sweden)

    J. Zhu

    2014-08-01

    Full Text Available Flat beams—beams with asymmetric transverse emittances—have important applications in novel light-source concepts and advanced-acceleration schemes and could possibly alleviate the need for damping rings in lepton colliders. Over the last decade, a flat beam generation technique based on the conversion of an angular-momentum-dominated beam was proposed and experimentally tested. In this paper we explore the production of compressed flat beams. We especially investigate and optimize the flat beam transformation for beams with substantial fractional energy spread. We use as a simulation example the photoinjector of Fermilab’s Advanced Superconducting Test Accelerator. The optimizations of the flat beam generation and compression at Advanced Superconducting Test Accelerator were done via start-to-end numerical simulations for bunch charges of 3.2 nC, 1.0 nC, and 20 pC at ∼37  MeV. The optimized emittances of flat beams with different bunch charges were found to be 0.25  μm (emittance ratio is ∼400, 0.13   μm, 15 nm before compression, and 0.41  μm, 0.20  μm, 16 nm after full compression, respectively, with peak currents as high as 5.5 kA for a 3.2-nC flat beam. These parameters are consistent with requirements needed to excite wakefields in asymmetric dielectric-lined waveguides or produce significant photon flux using small-gap micro-undulators.

  12. Manipulating the Electronic Excited State Energies of Pyrimidine-Based Thermally Activated Delayed Fluorescence Emitters To Realize Efficient Deep-Blue Emission.

    Science.gov (United States)

    Komatsu, Ryutaro; Ohsawa, Tatsuya; Sasabe, Hisahiro; Nakao, Kohei; Hayasaka, Yuya; Kido, Junji

    2017-02-08

    The development of efficient and robust deep-blue emitters is one of the key issues in organic light-emitting devices (OLEDs) for environmentally friendly, large-area displays or general lighting. As a promising technology that realizes 100% conversion from electrons to photons, thermally activated delayed fluorescence (TADF) emitters have attracted considerable attention. However, only a handful of examples of deep-blue TADF emitters have been reported to date, and the emitters generally show large efficiency roll-off at practical luminance over several hundreds to thousands of cd m-2, most likely because of the long delayed fluorescent lifetime (τd). To overcome this problem, we molecularly manipulated the electronic excited state energies of pyrimidine-based TADF emitters to realize deep-blue emission and reduced τd. We then systematically investigated the relationships among the chemical structure, properties, and device performances. The resultant novel pyrimidine emitters, called Ac-XMHPMs (X = 1, 2, and 3), contain different numbers of bulky methyl substituents at acceptor moieties, increasing the excited singlet (ES) and triplet state (ET) energies. Among them, Ac-3MHPM, with a high ET of 2.95 eV, exhibited a high external quantum efficiency (ηext,max) of 18% and an ηext of 10% at 100 cd m-2 with Commission Internationale de l'Eclairage chromaticity coordinates of (0.16, 0.15). These efficiencies are among the highest values to date for deep-blue TADF OLEDs. Our molecular design strategy provides fundamental guidance to design novel deep-blue TADF emitters.

  13. Nonequilibrium interpretation of DC properties of NbN superconducting hot electron bolometers

    NARCIS (Netherlands)

    Shcherbatenko, M; Tretyakov, I; Lobanov, Yu; Maslennikov, S. N.; Kaurova, N; Finkel, M.; Voronov, B; Goltsman, G; Klapwijk, T.M.

    2016-01-01

    We present a physically consistent interpretation of the dc electrical properties of niobiumnitride (NbN)-based superconducting hot-electron bolometer mixers, using concepts of nonequilibrium superconductivity. Through this, we clarify what physical information can be extracted from the resistive

  14. Extraction simulations and emittance measurements of a Holifield Radioactive Ion Beam Facility electron beam plasma source for radioactive ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, A. J. II; Liu, Y. [Holifield Radioactive Ion Beam Facility, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2010-02-15

    The Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory has a variety of ion sources used to produce radioactive ion beams (RIBs). Of these, the workhorse is an electron beam plasma (EBP) ion source. The recent addition of a second RIB injector, the Injector for Radioactive Ion Species 2 (IRIS2), for the HRIBF tandem accelerator prompted new studies of the optics of the beam extraction from the EBP source. The source was modeled using SIMION V8.0, and results will be presented, including comparison of the emittances as predicted by simulation and as measured at the HRIBF offline ion source test facilities. Also presented will be the impact on phase space shape resulting from extraction optics modifications implemented at IRIS2.

  15. A deep-blue emitter with electron transporting property to improve charge balance for organic light-emitting device.

    Science.gov (United States)

    Xing, Xing; Zhang, Lipei; Liu, Rui; Li, Suyue; Qu, Bo; Chen, Zhijian; Sun, Wenfang; Xiao, Lixin; Gong, Qihuang

    2012-06-27

    Highly efficient deep-blue organic light-emitting devices (OLEDs) have been fabricated using 2,7-di(2,2':6',2″-terpyridin-4-yl)-9,9-dioctyl-9H-fluorene (DTPF) as the emitter, which has a wide energy gap, high emission quantum yield (Φf = 0.88), and high electron transporting property to improve the charge balance. A high efficiency of 2.55 cd/A and 2.67 lm/W are obtained in OLED. The device also exhibits a low turn-on voltage of 3.0 V and Commission Internationale de l'Éclairage (CIE) coordinates of (0.16, 0.09).

  16. Effects of electron blocking and hole trapping of the red guest emitter materials on hybrid white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Lin-Ann; Vu, Hoang-Tuan [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Juang, Fuh-Shyang, E-mail: fsjuang@seed.net.tw [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Lai, Yun-Jr [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Yeh, Pei-Hsun [Raystar Optronics, Inc., 5F No. 25, Keya Rd. Daya Township, Taichung County, Taiwan (China); Tsai, Yu-Sheng [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China)

    2013-10-01

    Hybrid white organic light emitting diodes (HWOLEDs) with fluorescence and phosphorescence hybrid structures are studied in this work. HWOLEDs were fabricated with blue/red emitting layers: fluorescent host material doped with sky blue material, and bipolar phosphorescent host emitting material doped with red dopant material. An electron blocking layer is applied that provides hole red guest emitter hole trapping effects, increases the charge carrier injection quantity into the emitting layers and controls the recombination zone (RZ) that helps balance the device color. Spacer layers were also inserted to expand the RZ, increase efficiency and reduce energy quenching along with roll-off effects. The resulting high efficiency warm white OLED device has the lower highest occupied molecule orbital level red guest material, current efficiency of 15.9 cd/A at current density of 20 mA/cm{sup 2}, and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39)

  17. Emittance Reduction between EBIS LINAC and Booster by Electron Beam Cooling; Is Single Pass Cooling Possible?

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch,A.

    2008-04-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in less than one meter.

  18. Electromagnetic microwaves in metal films with electron-phonon interaction and a dc magnetic field

    DEFF Research Database (Denmark)

    Hasselberg, L.E.

    1976-01-01

    A quantum-mechanical treatment of electromagnetic microwaves is performed for a metal film. The directions of the exterior ac and dc fields are taken to be arbitrary and boundary conditions for the electrons are assumed to be specular. The relation between the current and the electromagnetic fiel...... in the transmission spectrum can perhaps be obtained by assuming a finite Debye temperature and specular reflections of the electrons at the boundary surfaces. A sharp peak entirely caused by the finite electron-phonon interaction is also discussed....

  19. Electron Emitter for small-size Electrodynamic Space Tether using MEMS Technology

    DEFF Research Database (Denmark)

    Fleron, René A. W.; Blanke, Mogens

    2004-01-01

    Adjustment of the orbit of a spacecraft using the forces created by an electro-dynamic space-tether has been shown as a theoretic possibility in recent literature. Practical implementation is being pursued for larger scale missions where a hot filament device controls electron emission and the cu......Adjustment of the orbit of a spacecraft using the forces created by an electro-dynamic space-tether has been shown as a theoretic possibility in recent literature. Practical implementation is being pursued for larger scale missions where a hot filament device controls electron emission...... and other orbit parameters can be controlled for small sized missions, without on-board propulsion....

  20. Comparison of dc and superconducting rf photoemission guns for high brightness high average current beam production

    Directory of Open Access Journals (Sweden)

    Ivan V. Bazarov

    2011-07-01

    Full Text Available A comparison of the two most prominent electron sources of high average current high brightness electron beams, dc and superconducting rf photoemission guns, is carried out using a large-scale multivariate genetic optimizer interfaced with space charge simulation codes. The gun geometry for each case is varied concurrently with laser pulse shape and parameters of the downstream beam line elements of the photoinjector to obtain minimum emittance as a function of bunch charge. Realistic constraints are imposed on maximum field values for the two gun types. The superconducting rf and dc gun emittances and beam envelopes are compared for various values of photocathode thermal emittance. The performance of the two systems is found to be largely comparable for up to 154 pC per bunch at 1.3 GHz or 200 mA provided low intrinsic emittance photocathodes can be employed.

  1. DNA double strand breaks as predictor of efficacy of the alpha-particle emitter Ac-225 and the electron emitter Lu-177 for somatostatin receptor targeted radiotherapy.

    Directory of Open Access Journals (Sweden)

    Franziska Graf

    Full Text Available RATIONALE: Key biologic effects of the alpha-particle emitter Actinium-225 in comparison to the beta-particle emitter Lutetium-177 labeled somatostatin-analogue DOTATOC in vitro and in vivo were studied to evaluate the significance of γH2AX-foci formation. METHODS: To determine the relative biological effectiveness (RBE between the two isotopes (as - biological consequence of different ionisation-densities along a particle-track, somatostatin expressing AR42J cells were incubated with Ac-225-DOTATOC and Lu-177-DOTATOC up to 48 h and viability was analyzed using the MTT assay. DNA double strand breaks (DSB were quantified by immunofluorescence staining of γH2AX-foci. Cell cycle was analyzed by flow cytometry. In vivo uptake of both radiolabeled somatostatin-analogues into subcutaneously growing AR42J tumors and the number of cells displaying γH2AX-foci were measured. Therapeutic efficacy was assayed by monitoring tumor growth after treatment with activities estimated from in vitro cytotoxicity. RESULTS: Ac-225-DOTATOC resulted in ED50 values of 14 kBq/ml after 48 h, whereas Lu-177-DOTATOC displayed ED50 values of 10 MBq/ml. The number of DSB grew with increasing concentration of Ac-225-DOTATOC and similarly with Lu-177-DOTATOC when applying a factor of 700-fold higher activity compared to Ac-225. Already 24 h after incubation with 2.5-10 kBq/ml, Ac-225-DOTATOC cell-cycle studies showed up to a 60% increase in the percentage of tumor cells in G2/M phase. After 72 h an apoptotic subG1 peak was also detectable. Tumor uptake for both radio peptides at 48 h was identical (7.5%ID/g, though the overall number of cells with γH2AX-foci was higher in tumors treated with 48 kBq Ac-225-DOTATOC compared to tumors treated with 30 MBq Lu-177-DOTATOC (35% vs. 21%. Tumors with a volume of 0.34 ml reached delayed exponential tumor growth after 25 days (44 kBq Ac-225-DOTATOC and after 21 days (34 MBq Lu-177-DOTATOC. CONCLUSION: γH2AX-foci formation, triggered

  2. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    CERN Document Server

    Talman, Richard; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004); N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using trafic4* [A. Kabel et al., Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)] and elegant [M. Borland, Argonne National Laboratory...

  3. Emittance evolution of a tightly focused electron bunch with high energy spread

    CERN Document Server

    Rossi, A R

    2011-01-01

    The production of a self injected high energy electron beam from laser-plasma interaction is one of the goals at the LI2FE infrastructure at LNF. The formation and acceleration of a beam produced with the experimental setting available in Frascati has been simulated by C. Benedetti et al. by means of the code AlaDyn [1]; the results, shown in Figure 1, foresee that the bunch should have a total charge of about 3.5 nC, a transverse size of few microns and a very broad spectrum, ranging from a few MeV up to about 1 GeV, in agreement with other numerical and experimental results produced world wide. In particular, a neatly separated charge portion at high energy is present (Figure 2), whose main parameters are reported in Table 1, which constitutes the most interesting product of the plasma based accelerator.

  4. Emittance measurements at PITZ

    Energy Technology Data Exchange (ETDEWEB)

    Vashchenko, Grygorii; Asova, Galina; Baehr, Juergen; Grabosch, Hans Juergen; Hakobyan, Levon; Haenel, Marc; Ivanisenko, Yevgeniy; Khojoyan, Martin; Krasilnikov, Mikhail; Mahgoub, Mahmoud; Nozdrin, Mikhail; O' Shea, Brendon; Otevrel, Marek; Petrosyan, Bagrat; Richter, Dieter; Riemann, Sabine; Rimjaem, Sakhorn; Roensch, Juliane; Shapovalov, Andrey; Spesyvtsev, Roman; Staykov, Lazar; Stephan, Frank [DESY, 15738 Zeuthen (Germany); Floettmann, Klaus; Lederer, Sven; Schreiber, Siegfried [DESY, 22607 Hamburg (Germany); Klemz, Guido; Will, Ingo [Max-Born-Institute, Berlin(Germany)

    2010-07-01

    The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) has an aim to develop and optimize high brightness electron sources for Free Electron Lasers like FLASH and the European XFEL. The new laser system allows to produce trains of laser pulses with flat-top temporal profiles of about 20 ps FWHM and rise/fall time of about 2 ps had been commissioned at PITZ in late autumn 2008. Photo electrons emitted from the Cs{sub 2}Te cathode are accelerated by a 1.6-cell L band RF gun cavity operated at 60 MV/m maximum accelerating gradient at the cathode. For measuring of transverse projected emittance the so called single slit scan technique is used at PITZ. This procedure is discussed. Recent results on measured emittance of electron beam are presented.

  5. High voltage threshold for stable operation in a dc electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Masahiro, E-mail: masahiro@post.kek.jp [High Energy Accelerator Research Organization (KEK), Oho, Tsukuba, Ibaraki 305-0801 (Japan); Nishimori, Nobuyuki, E-mail: n-nishim@tagen.tohoku.ac.jp [National Institutes for Quantum and Radiological Science and Technology (QST), Tokai, Naka, Ibaraki 319-1195 (Japan)

    2016-07-04

    We report clear observation of a high voltage (HV) threshold for stable operation in a dc electron gun. The HV hold-off time without any discharge is longer than many hours for operation below the threshold, while it is roughly 10 min above the threshold. The HV threshold corresponds to the minimum voltage where discharge ceases. The threshold increases with the number of discharges during HV conditioning of the gun. Above the threshold, the amount of gas desorption per discharge increases linearly with the voltage difference from the threshold. The present experimental observations can be explained by an avalanche discharge model based on the interplay between electron stimulated desorption (ESD) from the anode surface and subsequent secondary electron emission from the cathode by the impact of ionic components of the ESD molecules or atoms.

  6. Electronic structure of an anticancer drug DC81 and its interaction with DNA base pairs

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Gargi, E-mail: gargi.tiwari@rediffmail.com; Sharma, Dipendra, E-mail: d-11sharma@rediffmail.com; Dwivedi, K. K., E-mail: dwivedikarunesh4@gmail.com [Department of Physics, DDU Gorakhpur University, Gorakhpur (India); Dwivedi, M. K., E-mail: dwivedi-ji@rediffmail.com [Department of Physics, Banaras Hindu University, Varanasi (India)

    2016-05-06

    The drug, 8-Hydroxy-7-methoxy-pyrrolo-[2,1-c][1,4] benzodiazepine-5-one, commonly christened as DC81 belongs to the pyrrolo-[2,1-c][1,4]benzodiazepine (PBDs) family. It is a member of the group of naturally occurring antitumour antibiotics produced by various Streptomyces species. The antitumour activity of DC81 is attributed to its sequence specific interaction with G-C rich DNA region in particular, for Pu-G-Pu motifs. In the present paper, physico-chemical properties DC81 have been carried out using an ab-initio method, HF/6-31G(d,p) with GAMESS program. MEP, HOMO and LUMO surfaces have been scanned. Ionization potential, electron affinity, electronegativity, global hardness and softness of the drug have been calculated. Further, drug-DNA interactions have been examined using modified second order perturbation theory along with multicentred-multipole expansion technique. Results have been discussed in the light of other theoretical and experimental observations. Efforts have been made to elucidate the binding patterns and thereby biological properties of the drug.

  7. High voltage performance of a dc photoemission electron gun with centrifugal barrel-polished electrodes

    Science.gov (United States)

    Hernandez-Garcia, C.; Bullard, D.; Hannon, F.; Wang, Y.; Poelker, M.

    2017-09-01

    The design and fabrication of electrodes for direct current (dc) high voltage photoemission electron guns can significantly influence their performance, most notably in terms of maximum achievable bias voltage. Proper electrostatic design of the triple-point junction shield electrode minimizes the risk of electrical breakdown (arcing) along the insulator-cable plug interface, while the electrode shape is designed to maintain interior surface of superconducting radio frequency cavities but implemented here for the first time to polish electrodes for dc high voltage photoguns. The technique reduced polishing time from weeks to hours while providing surface roughness comparable to that obtained with diamond-paste polishing and with unprecedented consistency between different electrode samples. We present electrode design considerations and high voltage conditioning results to 360 kV (˜11 MV/m), comparing barrel-polished electrode performance to that of diamond-paste polished electrodes. Tests were performed using a dc high voltage photogun with an inverted-geometry ceramic insulator design.

  8. Ion Back-Bombardment of GaAs Photocathodes Inside DC High Voltage Electron Guns

    CERN Document Server

    Grames, Joseph M; Brittian, Joshua; Charles, Daniel; Clark, Jim; Hansknecht, John; Lynn Stutzman, Marcy; Poelker, Matthew; Surles-Law, Kenneth E

    2005-01-01

    The primary limitation for sustained high quantum efficiency operation of GaAs photocathodes inside DC high voltage electron guns is ion back-bombardment of the photocathode. This process results from ionization of residual gas within the cathode/anode gap by the extracted electron beam, which is subsequently accelerated backwards to the photocathode. The damage mechanism is believed to be either destruction of the negative electron affinity condition at the surface of the photocathode or damage to the crystal structure by implantation of the bombarding ions. This work characterizes ion formation within the anode/cathode gap for gas species typical of UHV vacuum chambers (i.e., hydrogen, carbon monoxide and methane). Calculations and simulations are performed to determine the ion trajectories and stopping distance within the photocathode material. The results of the simulations are compared with test results obtained using a 100 keV DC high voltage GaAs photoemission gun and beamline at currents up to 10 mA D...

  9. The role of electron-emitting radiopharmaceuticals in the palliative treatment of metastatic bone pain and for radiosynovectomy: applications of conversion electron emitter Tin-117m

    Directory of Open Access Journals (Sweden)

    Suresh C. Srivastava

    2007-09-01

    Full Text Available A variety of radionuclides continue to be investigated and/or clinically used for different therapeutic applications in nuclear medicine. The choice of a particular radionuclide with regard to appropriate emissions, linear energy transfer (LET, and physical half-life, etc., is dictated to a large extent by the character of the disease (e.g., solid tumor or metastatic disease, and by the carrier to selectively transport the radionuclide to the desired site. An impressive body of information has appeared in the recent literature that addresses many of these considerations. This article summarizes and discusses the role of high-LET electron emitters and their advantage in the treatment of cancer or for other disorders in specific situations. Areas such as bone pain palliation, bone malignancy therapy, and radiation synovectomy are covered in greater detail. Projections are made as to the future directions and progress in these areas. A discussion of the various issues related to the selection criteria that are useful for choosing the appropriate radionuclide for a particular application is included. Use of high-LET electron emitters is discussed in greater detail, with particular emphasis on the use of conversion electron emitter tin-117m for various therapeutic applications.Uma variedade de radionuclídeos continua a ser investigada e/ou clinicamente utilizada para diferentes aplicações terapêuticas em medicina nuclear. A escolha de um radionuclídeo, considerando-se sua emissão apropriada, transferência linear de energia (LET e meia-vida física é determinada na maior parte pelo caráter da doença (p.ex., tumor sólido ou doença metastática, e pelo carreador que transporta o radionuclídeo seletivamente para o sítio desejado. Um notável conjunto de informações voltadas para essas considerações tem aparecido na literatura recente. Esse trabalho resume e discute o papel de emissores de elétrons de alta-LET e sua vantagem no

  10. Feedback model of secondary electron emission in DC gas discharge plasmas

    Science.gov (United States)

    Saravanan, ARUMUGAM; Prince, ALEX; Suraj, Kumar SINHA

    2018-01-01

    Feedback is said to exist in any amplifier when the fraction of output power in fed back as an input. Similarly, in gaseous discharge ions that incident on the cathode act as a natural feedback element to stabilize and self sustain the discharge. The present investigation is intended to emphasize the feedback nature of ions that emits secondary electrons (SEs) from the cathode surface in DC gas discharges. The average number of SEs emitted per incident ion and non ionic species (energetic neutrals, metastables and photons) which results from ion is defined as effective secondary electron emission coefficient (ESEEC,{γ }{{E}}). In this study, we derive an analytic expression that corroborates the relation between {γ }{{E}} and power influx by ion to the cathode based on the feedback theory of an amplifier. In addition, experimentally, we confirmed the typical positive feedback nature of SEE from the cathode in argon DC glow discharges. The experiment is done for three different cathode material of same dimension (tungsten (W), copper (Cu) and brass) under identical discharge conditions (pressure: 0.45 mbar, cathode bias: ‑600 V, discharge gab: 15 cm and operating gas: argon). Further, we found that the {γ }{{E}} value of these cathode material controls the amount of feedback power given by ions. The difference in feedback leads different final output i.e the power carried by ion at cathode ({P}{{i}}{\\prime }{| }{{C}}). The experimentally obtained value of {P}{{i}}{\\prime }{| }{{C}} is 4.28 W, 6.87 W and 9.26 W respectively for W, Cu and brass. In addition, the present investigation reveals that the amount of feedback power in a DC gas discharges not only affect the fraction of power fed back to the cathode but also the entire characteristics of the discharge.

  11. An overview of power electronics applications in fuel cell systems: DC and AC converters.

    Science.gov (United States)

    Ali, M S; Kamarudin, S K; Masdar, M S; Mohamed, A

    2014-01-01

    Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter.

  12. Effect of external static magnetic field on the emittance and total charge of electron beams generated by laser-Wakefield acceleration.

    Science.gov (United States)

    Hosokai, Tomonao; Kinoshita, Kenichi; Zhidkov, Alexei; Maekawa, Akira; Yamazaki, Atsushi; Uesaka, Mitsuru

    2006-08-18

    Significant enhancement of emittance and an increase of the total charge of femtosecond electron beams produced by a 12 TW, 40 fs laser pulse, tightly focused in a He gas jet, are observed after applying a static magnetic field, B> or =0.2 T, directed along the axis of laser pulse propagation. The effect appears when plasma produced by a laser prepulse becomes magnetized in the vicinity of the focus point: the electron Larmor frequency exceeds the collisional frequency, while periphery of the plasma remains unmagnetized. The entailed change in the shape of the plasma suppresses the diffraction of the main laser pulse that results in a much higher charge of electrons self-injected during the longitudinal wave breaking of the laser wake as well as the excellent stability of the beams.

  13. Status of and Future Plans for the CERN Linac4 Emittance Meter based on Laser Electron-detachment and a Diamond Strip-detector

    CERN Document Server

    Bravin, E; Raich, U; Roncarolo, F; Zocca, F; Gibson, S; Kruchinin, KO; Bosco, A; Boorman, G; Griesmayer, E

    2014-01-01

    LINAC4 has started its staged commissioning at CERN. After completion it will accelerate high brightness H- beams to 160 MeV. To measure the transverse profile and emittance of the beam, a non-destructive method based on electron photo detachment is proposed, using a pulsed, fibre-coupled laser to strip electrons from the H- ions. The laser can be focused and scanned through the H- beam, acting like a conventional slit. A downstream dipole separates the neutral H0 beamlet, created by the laser interaction, from the main H- beam, so that it can be measured by a diamond stripdetector. Combining the H0 beamlet profiles with the laser position allows the transverse emittance to be reconstructed. A prototype of this instrument was tested while commissioning the LINAC4 at 3 and 12 MeV. In this paper we shall describe the experimental setup, challenges and results of the measurements, and also address the characteristics and performance of the diamond strip-detector subsystem. In addition, the proposal for a permane...

  14. Effective secondary electron emission coefficient in DC abnormal glow discharge plasmas

    Science.gov (United States)

    Arumugam, Saravanan; Alex, Prince; Sinha, Suraj Kumar

    2017-11-01

    In this work, a self-consistent model has been used to estimate the effective secondary electron emission coefficient (γE) of the cathode in typical abnormal dc glow discharge conditions. Using this model, the value of γE has been obtained for tungsten (W), copper (Cu), and stainless steel (SS304) cathode samples for argon (Ar) and nitrogen (N2) discharges. The γE for W is lower than the Cu cathode under identical operating conditions. The results show possible dependence of γE on the Fermi energy of the cathode material since it influences the probability of electron to be emitted by the incident ion. In addition to this, we found, significant contribution of cathode directed species other than ion to γE. Further, the effect of pressure on γE for the N2 discharge has been investigated in the pressure range of 0.5 mbar to 2.0 mbar and its value increases from 0.38 to 0.47 with pressure for the SS304 cathode. The knowledge of γE successfully explains the governing processes in abnormal glow discharge plasma that cannot be explained by the value of the ion induced secondary electron emission coefficient γi. The measurement of the γE value of the cathode material in typical abnormal glow discharge plasma conditions presents possibilities of exciting advancement in various applications by accurate estimation of discharge characteristics including flux of species, fraction of power carried by ions and electrons, plasma density, discharge current density, etc.

  15. Single-Event Transient Testing of the Crane Aerospace and Electronics SMHF2812D Dual DC-DC Converter

    Science.gov (United States)

    Casey, Megan

    2015-01-01

    The purpose of this testing was to characterize the Crane Aerospace & Electronics (Crane) Interpoint SMHF2812D for single-event transient (SET) susceptibility. These data shall be used for flight lot evaluation, as well as qualification by similarity of the SMHF family of converters, all of which use the same active components.

  16. Stability of an emittance-dominated sheet-electron beam in planar wiggler and periodic permanent magnet structures with natural focusing

    Science.gov (United States)

    Carlsten, B. E.; Earley, L. M.; Krawczyk, F. L.; Russell, S. J.; Potter, J. M.; Ferguson, P.; Humphries, S.

    2005-06-01

    A sheet-beam traveling-wave amplifier has been proposed as a high-power generator of rf from 95 to 300 GHz, using a microfabricated rf slow-wave structure [Carlsten et al., IEEE Trans. Plasma Sci. 33, 85 (2005), ITPSBD, 0093-3813, 10.1109/TPS.2004.841172], for emerging radar and communications applications. The planar geometry of microfabrication technologies matches well with the nearly planar geometry of a sheet beam, and the greater allowable beam current leads to high-peak power, high-average power, and wide bandwidths. Simulations of nominal designs using a vane-loaded waveguide as the slow-wave structure have indicated gains in excess of 1 dB/mm, with extraction efficiencies greater than 20% at 95 GHz with a 120-kV, 20-A electron beam. We have identified stable sheet-beam formation and transport as the key enabling technology for this type of device. In this paper, we describe sheet-beam transport, for both wiggler and periodic permanent magnet (PPM) magnetic field configurations, with natural (or single-plane) focusing. For emittance-dominated transport, the transverse equation of motion reduces to a Mathieu equation, and to a modified Mathieu equation for a space-charge dominated beam. The space-charge dominated beam has less beam envelope ripple than an emittance-dominated beam, but they have similar stability thresholds (defined by where the beam ripple continues to grow without bound along the transport line), consistent with the threshold predicted by the Mathieu equation. Design limits are derived for an emittance-dominated beam based on the Mathieu stability threshold. The increased beam envelope ripple for emittance-dominated transport may impact these design limits, for some transport requirements. The stability of transport in a wiggler field is additionally compromised by the beam’s increased transverse motion. Stable sheet-beam transport with natural focusing is shown to be achievable for a 120-kV, 20-A, elliptical beam with a cross section of

  17. Experimental Progress of DC-SC Photoinjector at Peking University

    CERN Document Server

    Wang, G M; Ding, Y T; Hao, J; Huang, S L; Lin, L; Lu, X Y; Quan, S W; Wang, L F; Xiang, R; Zhang, B C; Zhao, K; Jiao, F; Xie, D; Yang, L; Zhu, F; Liu, C; Wang, F; Xu, W; Liu, Z

    2005-01-01

    Beam loading experiments on DC-SC photoinjector test facility have been finished at 4.4 K. Upon the present experiments, the gradient of 6 MV/m is achieved. The maximum energy gain is 1.1 MeV at 4.4 K. With average beam current of 270 mA, the measured rms emittance is about 5 mm-mrad at the beam energy of 500 keV. Experiments on the test facility has validated that the DC-SC photoinjector is a good choice to provide moderate average current electron beams with low bunch charge and very high repetition rate.

  18. Design and power management of an offshore medium voltage DC microgrid realized through high voltage power electronics technologies and control

    Science.gov (United States)

    Grainger, Brandon Michael

    The growth in the electric power industry's portfolio of Direct Current (DC) based generation and loads have captured the attention of many leading research institutions. Opportunities for using DC based systems have been explored in electric ship design and have been a proven, reliable solution for transmitting bulk power onshore and offshore. To integrate many of the renewable resources into our existing AC grid, a number of power conversions through power electronics are required to condition the equipment for direct connection. Within the power conversion stages, there is always a requirement to convert to or from DC. The AC microgrid is a conceptual solution proposed for integrating various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 without extensive custom engineering and (2) control architecture and communication. The Medium Voltage DC (MVDC) architecture, explored by the University of Pittsburgh, can be visualized as a special type of DC microgrid. This dissertation is multi-faceted, focused on many design aspects of an offshore DC microgrid. The focal points of the discussion are focused on optimized high power, high frequency magnetic material performance in electric machines, transformers, and DC/DC power converters---all components found within offshore, power system architectures. A new controller design based upon model reference control is proposed and shown to stabilize the electric motor drives (modeled as constant power loads), which serve as the largest power consuming entities in the microgrid. The design and simulation of a state-of-the-art multilevel converter for High Voltage DC (HVDC) is discussed and a component sensitivity analysis on fault current peaks is explored. A power management routine is

  19. Local digital control of power electronic converters in a dc microgrid based on a-priori derivation of switching surfaces

    Science.gov (United States)

    Banerjee, Bibaswan

    In power electronic basedmicrogrids, the computational requirements needed to implement an optimized online control strategy can be prohibitive. The work presented in this dissertation proposes a generalized method of derivation of geometric manifolds in a dc microgrid that is based on the a-priori computation of the optimal reactions and trajectories for classes of events in a dc microgrid. The proposed states are the stored energies in all the energy storage elements of the dc microgrid and power flowing into them. It is anticipated that calculating a large enough set of dissimilar transient scenarios will also span many scenarios not specifically used to develop the surface. These geometric manifolds will then be used as reference surfaces in any type of controller, such as a sliding mode hysteretic controller. The presence of switched power converters in microgrids involve different control actions for different system events. The control of the switch states of the converters is essential for steady state and transient operations. A digital memory look-up based controller that uses a hysteretic sliding mode control strategy is an effective technique to generate the proper switch states for the converters. An example dcmicrogrid with three dc-dc boost converters and resistive loads is considered for this work. The geometric manifolds are successfully generated for transient events, such as step changes in the loads and the sources. The surfaces corresponding to a specific case of step change in the loads are then used as reference surfaces in an EEPROM for experimentally validating the control strategy. The required switch states corresponding to this specific transient scenario are programmed in the EEPROM as a memory table. This controls the switching of the dc-dc boost converters and drives the system states to the reference manifold. In this work, it is shown that this strategy effectively controls the system for a transient condition such as step changes

  20. Lifetime evaluation of DC-supplied electronic ballasts with fluorescent lamps for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Rosillo, F.G. [CIEMAT, Madrid (Spain)

    2004-05-01

    The evaluation of the lifetime of fluorescent lamps and electronic ballast is a current issue in illuminating engineering. The difficulty of carrying out this extensive evaluation by means of time-consuming tests of durability led to the search for a single-factor or shortened durability test that would give a reliable evaluation. This paper presents the results of submitting three samples of 14 different models of DC ballast with fluorescent lamps for photovoltaic (PV) applications, to a durability test of 2 h 45 min on/15 min off, for 10,500 h. An additional sample of each model was used for the measurement of various parameters such as the current crest factor (CCF) and a description is given of the main factors affecting lifetime. As a result of these tests, the CCF is assessed as a lifetime evaluator, together with a regression model that relates this CCF to the relative frequency at which premature breakdown occurs. A possible relationship is suggested between lamp voltage and lifetime, together with some considerations of the effect on lifetime of the state of charge of the battery. (author)

  1. Power electronic solutions for interfacing offshore wind turbine generators to medium voltage DC collection grids

    Science.gov (United States)

    Daniel, Michael T.

    Here in the early 21st century humanity is continuing to seek improved quality of life for citizens throughout the world. This global advancement is providing more people than ever with access to state-of-the-art services in areas such as transportation, entertainment, computing, communication, and so on. Providing these services to an ever-growing population while considering the constraints levied by continuing climate change will require new frontiers of clean energy to be developed. At the time of this writing, offshore wind has been proven as both a politically and economically agreeable source of clean, sustainable energy by northern European nations with many wind farms deployed in the North, Baltic, and Irish Seas. Modern offshore wind farms are equipped with an electrical system within the farm itself to aggregate the energy from all turbines in the farm before it is transmitted to shore. This collection grid is traditionally a 3-phase medium voltage alternating current (MVAC) system. Due to reactive power and other practical constraints, it is preferable to use a medium voltage direct current (MVDC) collection grid when siting farms >150 km from shore. To date, no offshore wind farm features an MVDC collection grid. However, MVDC collection grids are expected to be deployed with future offshore wind farms as they are sited further out to sea. In this work it is assumed that many future offshore wind farms may utilize an MVDC collection grid to aggregate electrical energy generated by individual wind turbines. As such, this work presents both per-phase and per-pole power electronic converter systems suitable for interfacing individual wind turbines to such an MVDC collection grid. Both interfaces are shown to provide high input power factor at the wind turbine while providing DC output current to the MVDC grid. Common mode voltage stress and circulating currents are investigated, and mitigation strategies are provided for both interfaces. A power sharing

  2. Ion sources with arc-discharge plasma box driven by directly heated LaB(6) electron emitter or cold cathode.

    Science.gov (United States)

    Ivanov, Alexander A; Davydenko, Vladimir I; Deichuli, Petr P; Shulzhenko, Grigori I; Stupishin, Nikolay V

    2008-02-01

    In the Budker Institute, Novosibirsk, an ion source with arc-discharge plasma box has been developed in the recent years for application in thermonuclear devices for plasma diagnostics. Several modifications of the ion source were provided with extracted current ranging from 1 to 7 A and pulse duration of up to 4 s. Initially, the arc-discharge plasma box with cold cathode was used, with which pulse duration is limited to 2 s by the cathode overheating and sputtering in local arc spots. Recently, a directly heated LaB(6) electron emitter was employed instead, which has extended lifetime compared to the cold cathode. In the paper, characteristics of the beam produced with both arrangements of the plasma box are presented.

  3. Inspection of anode and field wires for the COMPASS drift chamber, DC5, with Environmental Scanning Electron Microscope

    Science.gov (United States)

    Cyuzuzo, Sonia

    2014-09-01

    The COMPASS experiment at CERN uses a secondary pion beam from the Super Proton Synchrotron (SPS) at CERN to explore the spin structure of nucleons. A new drift chamber, DC5, will be integrated into the COMPASS spectrometer to replace an aging straw tube detector. DC5 will detect muon pairs from Drell-Yan scattering of a pion-beam off a transversely polarized proton target. This data will be used to determine the correlation between transverse proton spin and the intrinsic transverse momentum of up-quarks inside the proton, the Sivers effect. DC5 is a large area planar drift chamber with 8 layers of anode-frames made of G10 fiberglass-epoxy. The G10 frames support printed circuit boards for soldering 20 μm diameter anode and 100 μm diameter field wires. The anode planes are sandwiched by 13 graphite coated Mylar cathode planes. To ensure a well-functioning of DC5, the wires were carefully tested. An optical inspection and a spectral analysis was performed with an Environmental Scanning Electron Microscope (ESEM) to verify the composition and dimensions and the integrity of the gold plating on the surface of these wires. The spectra of the wires were studied at 10 and 30 keV. The COMPASS experiment at CERN uses a secondary pion beam from the Super Proton Synchrotron (SPS) at CERN to explore the spin structure of nucleons. A new drift chamber, DC5, will be integrated into the COMPASS spectrometer to replace an aging straw tube detector. DC5 will detect muon pairs from Drell-Yan scattering of a pion-beam off a transversely polarized proton target. This data will be used to determine the correlation between transverse proton spin and the intrinsic transverse momentum of up-quarks inside the proton, the Sivers effect. DC5 is a large area planar drift chamber with 8 layers of anode-frames made of G10 fiberglass-epoxy. The G10 frames support printed circuit boards for soldering 20 μm diameter anode and 100 μm diameter field wires. The anode planes are sandwiched by 13

  4. Proton beam emittance growth in the Relativistic Heavy Ion Collider

    Directory of Open Access Journals (Sweden)

    S. Y. Zhang

    2008-05-01

    Full Text Available With the significant beam intensity improvement in RHIC polarized proton run 2005 and run 2006, the emittance growth becomes a luminosity limiting factor. The beam emittance growth has a dependence on the dynamic pressure rise, which in RHIC proton runs is mainly caused by the electron cloud. The dependence of the emittance growth on other electron cloud related parameters is also identified. The beam instability is usually absent, and the emittance growth rate is much slower than the ones typically caused by the head-tail instability. It is suspected that the emittance growth is caused by the electron cloud below the instability threshold. A discussion follows.

  5. Direct first-principles simulation of a high-performance electron emitter: Lithium-oxide-coated diamond surface

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Yoshiyuki, E-mail: yoshi-miyamoto@aist.go.jp; Miyazaki, Takehide [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Takeuchi, Daisuke; Yamasaki, Satoshi [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); JST, ALCA, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2014-09-28

    We examined the field emission properties of lithium(Li)/oxygen(O)-co-terminated diamond (001) surface [C(001)-LiO] through real-time electron dynamics simulation under an applied field. The current emitted from this surface was found to be more than four-fold that emitted by an H-terminated (001) surface, the latter being a typical negative electron affinity system. This high performance is attributed to the Li layer, which bends the potential wall of O-induced electron pockets down in the direction of vacuum, thus facilitating electron emission. Detailed analysis of the emitted electrons and the profile of the self-consistent potential elucidated that the role of O atoms changes from an electron barrier on OH-terminated diamond surfaces to an outlet for electron emission on C(001)-LiO.

  6. Direct first-principles simulation of a high-performance electron emitter: Lithium-oxide-coated diamond surface

    Science.gov (United States)

    Miyamoto, Yoshiyuki; Miyazaki, Takehide; Takeuchi, Daisuke; Yamasaki, Satoshi

    2014-09-01

    We examined the field emission properties of lithium(Li)/oxygen(O)-co-terminated diamond (001) surface [C(001)-LiO] through real-time electron dynamics simulation under an applied field. The current emitted from this surface was found to be more than four-fold that emitted by an H-terminated (001) surface, the latter being a typical negative electron affinity system. This high performance is attributed to the Li layer, which bends the potential wall of O-induced electron pockets down in the direction of vacuum, thus facilitating electron emission. Detailed analysis of the emitted electrons and the profile of the self-consistent potential elucidated that the role of O atoms changes from an electron barrier on OH-terminated diamond surfaces to an outlet for electron emission on C(001)-LiO.

  7. DC Home Appliances for DC Distribution System

    Directory of Open Access Journals (Sweden)

    MUHAMMAD KAMRAN

    2017-10-01

    Full Text Available This paper strengthens the idea of DC distribution system for DC microgrid consisting of a building of 50 apartments. Since the war of currents AC system has been dominant because of the paucity of research in the protection of the DC system. Now with the advance research in power electronics material and components, generation of electricity is inherently DC as by solar PV, fuel cell and thermoelectric generator that eliminates the rectification process. Transformers are replaced by the power electronics buck-boost converters. DC circuit breakers have solved the protection problems for both DC transmission and distribution system. In this paper 308V DC microgrid is proposed and home appliances (DC internal are modified to operate on 48V DC from DC distribution line. Instead of using universal and induction motors in rotary appliances, BLDC (Brushless DC motors are proposed that are highly efficient with minimum electro-mechanical and no commutation losses. Proposed DC system reduces the power conversion stages, hence diminishes the associated power losses and standby losses that boost the overall system efficiency. So in view of all this a conventional AC system can be replaced by a DC system that has many advantages by cost as well as by performance

  8. On the Asymmetric Focusing of Low-Emittance Electron Bunches via Active Lensing by Using Capillary Discharges

    Science.gov (United States)

    Bulanov, Stepan; Bagdasarov, Gennadiy; Bobrova, Nadezhda; Boldarev, Alexey; Olkhovskaya, Olga; Sasorov, Pavel; Gasilov, Vladimir; Barber, Samuel; Gonsalves, Anthony; Schroeder, Carl; van Tilborg, Jeroen; Esarey, Eric; Leemans, Wim; Levato, Tadzio; Margarone, Daniele; Korn, Georg; Kando, Masaki; Bulanov, Sergei

    2017-10-01

    A novel method for asymmetric focusing of electron beams is proposed. The scheme is based on the active lensing technique, which takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus the ultrarelativistic electrons. The plasma and magnetic field parameters inside a capillary discharge are described theoretically and modeled with dissipative MHD simulations to enable analysis of capillaries of oblong rectangle cross-sections implying that large aspect ratio rectangular capillaries can be used to form flat electron bunches. The effect of the capillary cross-section on the electron beam focusing properties were studied using the analytical methods and simulation- derived magnetic field map showing the range of the capillary discharge parameters required for producing the high quality flat electron beams.

  9. A Theory of Control for a Class of Electronic Power Processing Systems: Energy-Storage DC-To-DC Converters. Ph.D. Thesis

    Science.gov (United States)

    Burns, W. W., III

    1977-01-01

    An analytically derived approach to the control of energy-storage dc-to-dc converters, which enables improved system performance and an extensive understanding of the manner in which this improved performance is accomplished, is presented. The control approach is derived from a state-plane analysis of dc-to-dc converter power stages which enables a graphical visualization of the movement of the system state during both steady state and transient operation. This graphical representation of the behavior of dc-to-dc converter systems yields considerable qualitative insight into the cause and effect relationships which exist between various commonly used converter control functions and the system performance which results from them.

  10. A Monte Carlo study of energy deposition at the sub-cellular level for application to targeted radionuclide therapy with low-energy electron emitters

    Science.gov (United States)

    Emfietzoglou, D.; Bousis, C.; Hindorf, C.; Fotopoulos, A.; Pathak, A.; Kostarelos, K.

    2007-03-01

    Optimizing targeted radionuclide therapy for patients with circulating malignant cells (e.g. blood-related cancers) or a micrometastatic spread requires quantification of various dosimetric parameters at the single-cell level. We present results on the energy deposition of monoenergetic electrons of initial energy from 100 eV to 20 keV - relevant to Auger emitting radionuclides - distributed either uniformly or at the surface of spherical volumes of radii from 10 nm to 1 μm which correspond to critical sub-cellular targets. Calculations have been carried out by our detailed-history Monte Carlo (MC) code which simulates event-by-event the complete slowing down (to 1 Ry) of both the primary and all subsequent generations of electrons, as well as, by the continuous-slowing-down-approximation (CSDA) using analytic range-energy relationships. The latter method has been adopted by the MIRD committee of the Society of Nuclear Medicine for dosimetry at the cellular level (>1 μm). Differences between the MC and CSDA results are up to ∼50% and are expected to be even larger at higher energies and/or smaller volumes. They are attributed to the deficiencies of the CSDA method associated with the neglect of straggling and δ-ray transport. The results are particularly relevant to targeted radiotherapy at the genome level by Auger emitters.

  11. Floating emitter solar cell

    Science.gov (United States)

    Chih, Sah (Inventor); Cheng, Li-Jen (Inventor)

    1987-01-01

    A front surface contact floating emitter solar cell transistor is provided in a semiconductor body (n-type), in which floating emitter sections (p-type) are diffused or implanted in the front surface. Between the emitter sections, a further section is diffused or implanted in the front surface, but isolated from the floating emitter sections, for use either as a base contact to the n-type semiconductor body, in which case the section is doped n+, or as a collector for the adjacent emitter sections.

  12. Spatial coherence of electron beams from field emitters and its effect on the resolution of imaged objects

    Energy Technology Data Exchange (ETDEWEB)

    Latychevskaia, Tatiana, E-mail: tatiana@physik.uzh.ch

    2017-04-15

    Sub-nanometer and nanometer-sized tips provide high coherence electron sources. Conventionally, the effective source size is estimated from the extent of the experimental biprism interference pattern created on the detector by applying the van Cittert Zernike theorem. Previously reported experimental intensity distributions on the detector exhibit Gaussian distribution and our simulations show that this is an indication that such electron sources must be at least partially coherent. This, in turn means that strictly speaking the Van Cittert Zernike theorem cannot be applied, since it assumes an incoherent source. The approach of applying the van Cittert Zernike theorem is examined in more detail by performing simulations of interference patterns for the electron sources of different size and different coherence length, evaluating the effective source size from the extent of the simulated interference pattern and comparing the obtained result with the pre-defined value. The intensity distribution of the source is assumed to be Gaussian distributed, as it is observed in experiments. The visibility or the contrast in the simulated holograms is found to be always less than 1 which agrees well with previously reported experimental results and thus can be explained solely by the Gaussian intensity distribution of the source. The effective source size estimated from the extent of the interference pattern turns out to be of about 2–3 times larger than the pre-defined size, but it is approximately equal to the intrinsic resolution of the imaging system. A simple formula for estimating the intrinsic resolution, which could be useful when employing nano-tips in in-line Gabor holography or point-projection microscopy, is provided. - Highlights: • van Cittert Zernike theorem for nano- and sub-nano electron emitting tips is revised. • Simulations show that nano- and sub-nano electron emitting tips are at least partially coherent. • A simple formula for evaluating

  13. Electronics pocket book

    CERN Document Server

    Parr, E A

    1981-01-01

    Electronics Pocket Book, Fourth Edition is a nonmathematical presentation of the many varied topics covered by electronics. The book tackles electron physics, electronic components (i.e. resistors, capacitors, and conductors), integrated circuits, and the principles of a.c. and d.c. amplifiers. The text also discusses oscillators, digital circuits, digital computers, and optoelectronics (i.e., sensors, emitters, and devices that utilize light). Communications (such as line and radio communications, transmitters, receivers, and digital techniques); the principles and examples of servosystems; a

  14. Gate Driver Circuit of Power Electronic Switches with Reduced Number of Isolated DC/DC Converter for a Switched Reluctance Motor

    Directory of Open Access Journals (Sweden)

    Ali Asghar Memon

    2013-04-01

    Full Text Available This paper presents a gate driver circuit for the switching devices used in the asymmetrical converter for a switched reluctance machine with reduced number of isolated dc/dc converters. Isolation required in the gate driver circuit of switching devices is indispensable. For the purpose of isolation different arrangements may be used such as pulse transformers. The dc/dc converter for isolation and powering the gate drive circuits is suitable, cheaper in cost and simple to implement. It is also significant that required number of isolation converters is much less than the switches used in converter. In addition, a simple logic circuit has been presented for producing the gate signals at correct phase sequence which is compared with the gated signals directly obtained from the encoder of an existing machine.

  15. The low-energy {beta}{sup -} and electron emitter {sup 161}Tb as an alternative to {sup 177}Lu for targeted radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lehenberger, Silvia; Barkhausen, Christoph [Institute for Radiochemistry, Technical University of Munich, Walther-Meissner-Strasse 3, 85748 Garching (Germany); Cohrs, Susan; Fischer, Eliane; Gruenberg, Juergen; Hohn, Alexander [Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen, PSI (Switzerland); Koester, Ulli [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Schibli, Roger [Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen, PSI (Switzerland); Tuerler, Andreas [Institute for Radiochemistry, Technical University of Munich, Walther-Meissner-Strasse 3, 85748 Garching (Germany); Laboratory of Radiochemistry and Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, PSI (Switzerland); Laboratory of Radiochemistry and Environmental Chemistry, Department of Chemistry and Biochemistry, University of Bern, Freiestr. 3, 3012 Bern (Switzerland); Zhernosekov, Konstantin, E-mail: konstantin.zhernosekov@psi.ch [Institute for Radiochemistry, Technical University of Munich, Walther-Meissner-Strasse 3, 85748 Garching (Germany); Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen, PSI (Switzerland); Laboratory of Radiochemistry and Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, PSI (Switzerland)

    2011-08-15

    Introduction: The low-energy {beta}{sup -} emitter {sup 161}Tb is very similar to {sup 177}Lu with respect to half-life, beta energy and chemical properties. However, {sup 161}Tb also emits a significant amount of conversion and Auger electrons. Greater therapeutic effect can therefore be expected in comparison to {sup 177}Lu. It also emits low-energy photons that are useful for gamma camera imaging. Methods: The {sup 160}Gd(n,{gamma}){sup 161}Gd{yields}{sup 161}Tb production route was used to produce {sup 161}Tb by neutron irradiation of massive {sup 160}Gd targets (up to 40 mg) in nuclear reactors. A semiautomated procedure based on cation exchange chromatography was developed and applied to isolate no carrier added (n.c.a.) {sup 161}Tb from the bulk of the {sup 160}Gd target and from its stable decay product {sup 161}Dy. {sup 161}Tb was used for radiolabeling DOTA-Tyr3-octreotate; the radiolabeling profile was compared to the commercially available n.c.a. {sup 177}Lu. A {sup 161}Tb Derenzo phantom was imaged using a small-animal single-photon emission computed tomography camera. Results: Up to 15 GBq of {sup 161}Tb was produced by long-term irradiation of Gd targets. Using a cation exchange resin, we obtained 80%-90% of the available {sup 161}Tb with high specific activity, radionuclide and chemical purity and in quantities sufficient for therapeutic applications. The {sup 161}Tb obtained was of the quality required to prepare {sup 161}Tb-DOTA-Tyr3-octreotate. Conclusions: We were able to produce {sup 161}Tb in n.c.a. form by irradiating highly enriched {sup 160}Gd targets; it can be obtained in the quantity and quality required for the preparation of {sup 161}Tb-labeled therapeutic agents.

  16. Excitation of a global plasma mode by an intense electron beam in a dc discharge

    Science.gov (United States)

    Sydorenko, D.; Kaganovich, I. D.; Ventzek, P. L. G.; Chen, L.

    2018-01-01

    The interaction of an intense electron beam with a finite-length, inhomogeneous plasma is investigated numerically. The plasma density profile is maximal in the middle and decays towards the plasma edges. Two regimes of the two-stream instability are observed. In one regime, the frequency of the instability is the plasma frequency at the density maximum and plasma waves are excited in the middle of the plasma. In the other regime, the frequency of the instability matches the local plasma frequency near the edges of the plasma and the intense plasma oscillations occur near plasma boundaries. The latter regime appears sporadically and only for strong electron beam currents. This instability generates a copious amount of suprathermal electrons. The energy transfer to suprathermal electrons is the saturation mechanism of the instability.

  17. Simulation to Implementation as Good Practices for Teaching Power Electronics to Undergraduate Students: Fuzzy Sliding Mode Control for DC Motors

    Directory of Open Access Journals (Sweden)

    Paul Cepeda

    2014-01-01

    Full Text Available How can students be given experience in the confused realities of engineering processes? How can undergraduate students be convinced that processes can be analyzed and improved? Computer simulations properly designed and applied could answer these challenges revolutionizing education in Power Electronics. In recent years, computer simulation has been commonly used in education to motivate students in their learning and help teachers to improve their teaching level. The present paper focuses on developing a speed controller for DC motors starting from theoretical aspects, passing through simulations, and finally reaching a control prototype. The control theory is based on a nonlinear technique known as Sliding Mode Control (SMC involving artificial intelligence for optimization such as Fuzzy Logic (FL, Adaptive Neurofuzzy Inference Systems (ANFIS, and Genetic Algorithms (GAs.

  18. Effect of thin emitter set-back layer on GaAs delta-doped emitter bipolar junction transistor

    Science.gov (United States)

    Lew, K. L.; Yoon, S. F.

    2005-05-01

    GaAs delta-doped emitter bipolar junction transistors (δ-BJT) with different emitter set-back layer thicknesses of 10to50nm were fabricated to study the emitter set-back layer thickness effect on device dc performance. We found that the current gain decreases following decrease in the emitter set-back layer thickness. A detailed analysis was performed to explain this phenomenon, which is believed to be caused by reduction of the effective barrier height in the δ-BJT. This is due to change in the electric-field distribution in the delta-doped structure caused by the built-in potential of the base-emitter (B-E ) junction. Considering the recombination and barrier height reduction effects, the thickness of the emitter set-back layer should be designed according to the B-E junction depletion width with a tolerance of ±5nm. The dc performance of a δ-BJT designed based on this criteria is compared to that of a Al0.25Ga0.75As /GaAs heterojunction bipolar transistor (HBT). Both devices employed base doping of 2×1019cm-3 and base-to-emitter doping ratio of 40. Large emitter area (AE≈1.6×10-5cm-2) and small emitter area (AE≈1.35×10-6cm-2) device current gains of 40 and 20, respectively, were obtained in both types of transistors passivated by (NH4)2S treatment. The measured current gain of the GaAs δ-BJT is the highest reported for a homojunction device with such high base-to-emitter doping ratio normally used in HBT devices.

  19. ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. D-C MAGNETIC MOTOR CONTROL, UNIT 7, INSTRUCTOR'S GUIDE.

    Science.gov (United States)

    SUTTON, MACK C.

    THIS GUIDE IS FOR TEACHER USE IN DIRECTING INDIVIDUAL STUDY OF DIRECT CURRENT MAGNETIC MOTOR CONTROL IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. EACH OF THE 15 INSTRUCTOR'S SHEETS GIVES THE LESSON SUBJECT, PURPOSE, INTRODUCTORY INFORMATION, REFERENCES, AND STEP-BY-STEP SOLUTIONS OF THE…

  20. Optimization of the design of DC-DC converters for improving the electromagnetic compatibility with the Front-End electronic for the super Large Hadron Collider Trackers

    CERN Document Server

    Fuentes Rojas, Cristian Alejandro; Blanchot, G

    2011-01-01

    The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DC buck converters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buck converter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility.

  1. The DIORAMA Neutron Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Terry, James Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  2. Beta emitters and radiation protection

    DEFF Research Database (Denmark)

    Jødal, Lars

    2009-01-01

    BACKGROUND. Beta emitters, such as 90Y, are increasingly being used for cancer treatment. However, beta emitters demand other precautions than gamma emitters during preparation and administration, especially concerning shielding. AIM. To discuss practical precautions for handling beta emitters...... on the outside of the primary shielding material. If suitable shielding is used and larger numbers of handlings are divided among several persons, then handling of beta emitters can be a safe procedure....

  3. Camphor soot: a tunable light emitter

    Science.gov (United States)

    Swapna, M. S.; Saritha Devi, H. V.; Sankararaman, S.

    2018-01-01

    The work in this paper is the first report on the green synthesis of the blue light emitter from waxy, flammable solid collected from Cinnamomum camphora by controlled combustion for photonic applications. Analysis with field emission scanning electron microscope and high-resolution transmission electron microscope provides the morphology, whereas the thermogravimetric analysis gives the thermal stability of the soot. The optical and structural characterizations are done by recording UV-Visible, Photoluminescent, and Raman Spectrum. The CIE plot and the power spectrum of the sample show a blue emission at an excitation of 350 nm at room temperature with a quantum yield of 46.15%. The dependence of luminescent behavior on temperature and excitation wavelength reveals that the material is a tunable blue emitter. This green synthesis of the blue light emitter is highly significant, when the world is in search of a simple, phosphor-free, non-toxic, cost-effective material with good quantum efficiency.

  4. Emittance measurement by multi-changing focusing strength

    CERN Document Server

    Wang Shu Hong; Cao Jian She; Ma Li; Liu Yu Cheng; Le Qi; Pei Guo Xi; Zhang Jia Fei

    2002-01-01

    Some advanced techniques to optimize the emittance measurement devices have been studied, such as thin lens approximation, multi-changing focusing strength, optimizing the position of the profile monitor and software improvement for accurate data acquisition and effective processing. By applying these techniques to the emittance measurement for electron beam of BEPC Linac, the satisfactory measurement results have been obtained

  5. Electron Beam Source for Technological Applications

    Science.gov (United States)

    Polyakov, V. A.; Shchedrin, I. S.

    1997-05-01

    Electron beam source with thermionic cathode and its application for technological purposes are described.Three electrode electron gun has a lanthanum hexaboride disc emitter with indirect heating. Accelerating voltage can be varied from 20 to 100 kV.Maximum d.c. current is 1-2 A for emitter diameter 4-5 mm.Magnetic focusing lens of solenoidal type ensures high beam power density on the object processed - up to 10 MW per sq.sm.This electron source was used for welding and thermoprocessing - surface hardening of ball-bearings. To ensure required complex power distribution on their surface special electronic unit for electron beam position control was designed.At the surface of ball-bearings the layer with hardness of 62-64 HRC and thickness about 1-1.5 mm was formed after electron processing that considerably increased their working period.

  6. Expanding veterinary biosurveillance in Washington, DC: The creation and utilization of an electronic-based online veterinary surveillance system.

    Science.gov (United States)

    Hennenfent, Andrew; DelVento, Vito; Davies-Cole, John; Johnson-Clarke, Fern

    2017-03-01

    To enhance the early detection of emerging infectious diseases and bioterrorism events using companion animal-based surveillance. Washington, DC, small animal veterinary facilities (n=17) were surveyed to determine interest in conducting infectious disease surveillance. Using these results, an electronic-based online reporting system was developed and launched in August 2015 to monitor rates of canine influenza, canine leptospirosis, antibiotic resistant infections, canine parvovirus, and syndromic disease trends. Nine of the 10 facilities that responded expressed interest conducting surveillance. In September 2015, 17 canine parvovirus cases were reported. In response, a campaign encouraging regular veterinary preventative care was launched and featured on local media platforms. Additionally, during the system's first year of operation it detected 5 canine leptospirosis cases and 2 antibiotic resistant infections. No canine influenza cases were reported and syndromic surveillance compliance varied, peaking during National Special Security Events. Small animal veterinarians and the general public are interested in companion animal disease surveillance. The system described can serve as a model for establishing similar systems to monitor disease trends of public health importance in pet populations and enhance biosurveillance capabilities. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Novel deep-blue emitting phosphorescent emitter

    Science.gov (United States)

    Schildknecht, C.; Ginev, G.; Kammoun, A.; Riedl, T.; Kowalsky, W.; Johannes, H.-H.; Lennartz, C.; Kahle, K.; Egen, M.; Geßner, T.; Bold, M.; Nord, S.; Erk, P.

    2005-10-01

    Currently, one of the most challenging applications for OLEDs is the full color display. The most energy-efficient way to realize light generation in OLEDs is by using phosphorescent emitters. Green and red emitters have already been demonstrated, but the search for blue emitting organic phosphorescent emitters with good color purity is still ongoing with arduous effort. Here we present our work with a new material developed at BASF which allows phosphorescent emission in the deep-blue spectral range. The emitter has an emission maximum at 400 nm, which gives CIE color coordinates of x = 0.16 and y = 0.06. An OLED device made with this new material shows a maximum external quantum efficiency of 1.5 %. The OLED was built in a three layer structure, with the emitting zone being a hybrid guest-host system. As host material we used the optically and electronically inert polymer poly-methyl-methacrylate (PMMA). Because of its lack of charge transport abilities we doped the host material with a high concentration of the triplet emitting material, i.e. the emitter itself is also used as charge transport material.

  8. Development of arrayed microcolumns and field emitters

    Science.gov (United States)

    Kim, Ho Seob; Bok Lee, Young; Choi, Sung Woong; Kim, Hyung Woo; Kim, Dae-Wook; Ahn, Seung Joon; Oh, Tae Sik; Song, Yoon-Ho; Chon Park, Byong; Jong Lim, Sun

    2017-06-01

    Electron beam devices have been widely used for inspection or lithography processes. The multibeam technology based on arrayed microcolumns has been developed to overcome the low throughput issue. However, the multicolumn system has some drawbacks such as complexity, electron optics, and electron source. The first drawback is the difficulty in multicolumn assembly. In particular, the alignment process of a source lens and a tip requires sophisticated techniques. The second drawback is that the e-beam characteristics of microcolumns constituting the multicolumn differ from column to column. To solve the first drawback, a sub-5-nm-resolution probe beam optic design with a simple structure and a two-dimensional carbon nanotube (2D-CNT) electron emitter instead of the widely used tungsten field emitter tip have been studied.

  9. Beam Loading Tests on DC-SC Photoinjector at Peking University

    CERN Document Server

    Huang, Senlin; Chu, Xiangqiang; Ding, Yuantao; Hao, Jiankui; Jiao, Fei; Lin, Lin; Lu Xiang Yang; Quan, Shengwen; Wang, Guimei; Wang, Lifang; Xiang Rong; Xiao, Binping; Xie, Datao; Yang Li Min; Zhang, Baocheng; Zhao, Kui; Zhu, Feng

    2004-01-01

    Since the beginning of commissioning in February 2003, lots of tests on the DC-SC photoinjector test facility have been performed. At present, Q0 of the 1+1/2-cell cavity has reached ~1E8 (at 4.2K) and the average gradient was about 4MeV/m. The DC photogun can provide stable electron beams. When the power of output laser went up to 100mW (266nm), the average beam current reached 400μA. Beam loading tests have been carried out, and SC acceleration was achieved. Average current of electron beams is about 100μA after acceleration.Further investigations are in progress to improve diagnostics system and to measure the emittance, energy spread and pulse length of electron beams.

  10. Cancellation of RF Coupler-Induced Emittance Due to Astigmatism

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC

    2016-12-11

    It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.

  11. GTF Transverse and Longitudinal Emittance Data Analysis Technique

    Energy Technology Data Exchange (ETDEWEB)

    2010-12-07

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. Measurements at the GTF include quadrupole scan transverse emittance measurements and linac phase scan longitudinal emittance measurements. Typically the beam size is measured on a screen as a function of a quadrupole current or linac phase and the beam matrix is then fit to the measured data. Often the emittance which is the final result of the measurement is the only number reported. However, the method used to reduce the data to the final emittance value can have a significant effect on the result. This paper describes in painful detail the methods used to analyze the transverse and longitudinal emittance data collected at the GTF.

  12. Low-emittance Storage Rings

    CERN Document Server

    Wolski, Andrzej

    2014-01-01

    The effects of synchrotron radiation on particle motion in storage rings are discussed. In the absence of radiation, particle motion is symplectic, and the beam emittances are conserved. The inclusion of radiation effects in a classical approximation leads to emittance damping: expressions for the damping times are derived. Then, it is shown that quantum radiation effects lead to excitation of the beam emittances. General expressions for the equilibrium longitudinal and horizontal (natural) emittances are derived. The impact of lattice design on the natural emittance is discussed, with particular attention to the special cases of FODO-, achromat- and theoretical-minimum-emittance-style lattices. Finally, the effects of betatron coupling and vertical dispersion (generated by magnet alignment and lattice tuning errors) on the vertical emittance are considered.

  13. Transverse emittance measurement at REGAE via a solenoid scan

    Energy Technology Data Exchange (ETDEWEB)

    Hachmann, Max

    2012-12-15

    The linear accelerator REGAE at DESY produces short and low charged electron bunches, on the one hand to resolve the excitation transitions of atoms temporally by pump probe electron diffraction experiments and on the other hand to investigate principal mechanisms of laser plasma acceleration. For both cases a high quality electron beam is required. A quantity to rate the beam quality is the beam emittance. In the course of this thesis transverse emittance measurements by a solenoid scan could be realized and beyond that an improved theoretical description of a solenoid was successful. The foundation of emittance measurements are constituted by theoretical models which describe the envelope of a beam. Two different models were derived. The first is an often used model to determine the transverse beam emittance without considering space charge effects. More interesting and challenging was the development of an envelope model taking space charge effects into account. It is introduced and cross checked with measurements and simulations.

  14. Early Oscillation Detection for DC/DC Converter Fault Diagnosis

    Science.gov (United States)

    Wang, Bright L.

    2011-01-01

    The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

  15. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 ± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  16. Bidirectional DC/DC Converter

    Science.gov (United States)

    Pedersen, F.

    2008-09-01

    The presented bidirectional DC/DC converter design concept is a further development of an already existing converter used for low battery voltage operation.For low battery voltage operation a high efficient low parts count DC/DC converter was developed, and used in a satellite for the battery charge and battery discharge function.The converter consists in a bidirectional, non regulating DC/DC converter connected to a discharge regulating Buck converter and a charge regulating Buck converter.The Bidirectional non regulating DC/DC converter performs with relatively high efficiency even at relatively high currents, which here means up to 35Amps.This performance was obtained through the use of power MOSFET's with on- resistances of only a few mille Ohms connected to a special transformer allowing paralleling several transistor stages on the low voltage side of the transformer. The design is patent protected. Synchronous rectification leads to high efficiency at the low battery voltages considered, which was in the range 2,7- 4,3 Volt DC.The converter performs with low switching losses as zero voltage zero current switching is implemented in all switching positions of the converter.Now, the drive power needed, to switch a relatively large number of low Ohm , hence high drive capacitance, power MOSFET's using conventional drive techniques would limit the overall conversion efficiency.Therefore a resonant drive consuming considerable less power than a conventional drive circuit was implemented in the converter.To the originally built and patent protected bidirectional non regulating DC/DC converter, is added the functionality of regulation.Hereby the need for additional converter stages in form of a Charge Buck regulator and a Discharge Buck regulator is eliminated.The bidirectional DC/DC converter can be used in connection with batteries, motors, etc, where the bidirectional feature, simple design and high performance may be useful.

  17. DC + RSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne

    1996-01-01

    This document gives some initial ideas of how the Duration Calculus (DC) can be integrated with the RAISE Specification Language (RSL).......This document gives some initial ideas of how the Duration Calculus (DC) can be integrated with the RAISE Specification Language (RSL)....

  18. Measured emittance dependence on injection method in laser plasma accelerators

    Science.gov (United States)

    Barber, Samuel; van Tilborg, Jeroen; Schroeder, Carl; Lehe, Remi; Tsai, Hai-En; Swanson, Kelly; Steinke, Sven; Nakamura, Kei; Geddes, Cameron; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    The success of many laser plasma accelerator (LPA) based applications relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot transverse emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock induced density down-ramp injection. Notably, the measurements reveal that ionization injection results in significantly higher emittance. With the down-ramp injection configuration, emittances less than 1 micron at spectral charge densities up to 2 pC/MeV were measured. This work was supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the NSF under Grant No. PHY-1415596, by the U.S. DOE NNSA, DNN R&D (NA22), and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  19. Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters

    Science.gov (United States)

    Martinez-Rodrigo, Fernando; Herrero-De Lucas, Luis Carlos; de Pablo, Santiago; Rey-Boue, Alexis B.

    2017-01-01

    This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results…

  20. An Online Multisensor Data Fusion Framework for Radar Emitter Classification

    Directory of Open Access Journals (Sweden)

    Dongqing Zhou

    2016-01-01

    Full Text Available Radar emitter classification is a special application of data clustering for classifying unknown radar emitters in airborne electronic support system. In this paper, a novel online multisensor data fusion framework is proposed for radar emitter classification under the background of network centric warfare. The framework is composed of local processing and multisensor fusion processing, from which the rough and precise classification results are obtained, respectively. What is more, the proposed algorithm does not need prior knowledge and training process; it can dynamically update the number of the clusters and the cluster centers when new pulses arrive. At last, the experimental results show that the proposed framework is an efficacious way to solve radar emitter classification problem in networked warfare.

  1. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  2. Field emitters made of the contacted ytterbium and carbon nanolayers

    Directory of Open Access Journals (Sweden)

    G.G. Sominski

    2015-10-01

    Full Text Available The operation of field emitters of a new type prepared from contacted nanolayers of ytterbium and carbon has been investigated. The performed calculations and experiments allowed to optimize the emission characteristics of the emitters. The calculations took into account the existence of a transition zone between the layers of Yb and C. Emission characteristics of the cathodes including up to 40 pairs of layers of carbon and ytterbium with optimum thicknesses of 5 and 2 nm respectively were measured. The created multilayered emitters provide the average emission current density over the surface of the emitter up to 10–20 A/cm2 and show promise for use in miniature electronic devices.

  3. Boundary conditions on the plasma emitter surface in the presence of a particle counter flow: I. Ion emitter

    Energy Technology Data Exchange (ETDEWEB)

    Astrelin, V. T., E-mail: V.T.Astrelin@inp.nsk.su; Kotelnikov, I. A. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2017-02-15

    Emission of positively charged ions from a plasma emitter irradiated by a counterpropagating electron beam is studied theoretically. A bipolar diode with a plasma emitter in which the ion temperature is lower than the electron temperature and the counter electron flow is extracted from the ion collector is calculated in the one-dimensional model. An analog of Bohm’s criterion for ion emission in the presence of a counterpropagating electron beam is derived. The limiting density of the counterpropagating beam in a bipolar diode operating in the space-charge-limited-emission regime is calculated. The full set of boundary conditions on the plasma emitter surface that are required for operation of the high-current optics module in numerical codes used to simulate charged particle sources is formulated.

  4. WE-AB-204-12: Dosimetry at the Sub-Cellular Scale of Auger-Electron Emitter 99m-Tc in a Mouse Single Thyroid Follicle Model

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A; Benabdallah, N; Desbree, A [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-roses (France)

    2015-06-15

    Purpose: To perform a dosimetry study at the sub-cellular scale of Auger-electron emitter 99m-Tc using a mouse single thyroid cellular model to investigate the contribution of the 99m-Tc Auger-electrons to the absorbed dose and possible link to the thyroid stunning in in vivo experiments in mice, recently reported in literature. Methods: The simulation of S-values for Auger-electron emitting radionuclides was performed using both the recent MCNP6 software and the Geant4-DNA extension of the Geant4 toolkit. The dosimetric calculations were validated through comparison with results from literature, using a simple model of a single cell consisting of two concentric spheres of unit density water and for six Auger-electron emitting radionuclides. Furthermore, the S-values were calculated using a single thyroid follicle model for uniformly distributed 123-I and 125-I radionuclides and compared with published S-values. After validation, the simulation of the S-values was performed for the 99m-Tc radionuclide within the several mouse thyroid follicle cellular compartments, considering the radiative and non-radiative transitions of the 99m-Tc radiation spectrum. Results: The calculated S-values using MCNP6 are in good agreement with the results from literature, validating its use for the 99m-Tc S-values calculations. The most significant absorbed dose corresponds to the case where the radionuclide is uniformly distributed in the follicular cell’s nucleus, with a S-value of 7.8 mGy/disintegration, due mainly to the absorbed Auger-electrons. The results show that, at a sub-cellular scale, the emitted X-rays and gamma particles do not contribute significantly to the absorbed dose. Conclusion: In this work, MCNP6 was validated for dosimetric studies at the sub-cellular scale. It was shown that the contribution of the Auger-electrons to the absorbed dose is important at this scale compared to the emitted photons’ contribution and can’t be neglected. The obtained S

  5. Velocity bunching of high-brightness electron beams

    Directory of Open Access Journals (Sweden)

    S. G. Anderson

    2005-01-01

    Full Text Available Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly

  6. VELOCITY BUNCHING OF HIGH-BRIGHTNESS ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S G; Musumeci, P; Rosenzweig, J B; Brown, W J; England, R J; Ferrario, M; Jacob, J S; Thompson, M C; Travish, G; Tremaine, A M; Yoder, R

    2004-10-15

    Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments

  7. DC Distribution Systems and Microgrids

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Anvari-Moghaddam, Amjad; Quintero, Juan Carlos Vasquez

    2017-01-01

    A qualitative overview of different hardware topologies and control systems for DC MGs has been presented in this chapter. Some challenges and design considerations of DC protections systems have also been discussed. Finally, applications of DC MGs in emerging smart grid applications have been su...... in different industries and gradually lead to new ways of rethinking of the future power distribution philosophies, especially with the emergence of SSTs. Research in DC systems, especially in the power electronics-based technologies will be highly attractive in the future....

  8. First-Principle Electronic Properties of Dilute-P GaN1-xPx Alloy for Visible Light Emitters

    Science.gov (United States)

    Tan, Chee-Keong; Borovac, Damir; Sun, Wei; Tansu, Nelson

    2016-04-01

    A study on the electronic properties of the dilute-P GaN1-xPx alloy using First-Principle Density Functional Theory (DFT) calculations is presented. Our results indicate a band gap energy coverage from 3.645 eV to 2.697 eV, with P-content varying from 0% to 12.5% respectively. In addition, through line fitting of calculated and experimental data, a bowing parameter of 9.5 ± 0.5 eV was obtained. The effective masses for electrons and holes are analyzed, as well as the split-off energy parameters where findings indicate minimal interband Auger recombination. The alloy also possesses the direct energy band gap property, indicating its strong potential as a candidate for future photonic device applications.

  9. A Polarized Electron RF Photoinjector Using the Plane-Wave-Transformer (PWT) Design

    Energy Technology Data Exchange (ETDEWEB)

    Clendenin, James E

    2001-08-29

    Polarized electron beams are now in routine use in particle accelerators for nuclear and high energy physics experiments. These beams are presently produced by dc-biased photoelectron sources combined with rf chopping and bunching systems with inherently high transverse emittances. Low emittances can be produced with an rf gun, but the vacuum environment has until now been considered too harsh to support a negative electron affinity GaAs photocathode. We propose to significantly improve the vacuum conditions by adapting a PWT rf photoinjector to achieve reasonable cathode emission rates and lifetimes. This adaptation can also be combined with special optics that will result in a flat beam with a normalized rms emittance in the narrow dimension that may be as low as 10{sup -8} m.

  10. Benchmarking of 3D space charge codes using direct phase space measurements from photoemission high voltage dc gun

    Directory of Open Access Journals (Sweden)

    Ivan V. Bazarov

    2008-10-01

    Full Text Available We present a comparison between space charge calculations and direct measurements of the transverse phase space of space charge dominated electron bunches from a high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit emittance measurement system over a range of bunch charge and solenoid current values. The data are compared with detailed simulations using the 3D space charge codes GPT and Parmela3D. The initial particle distributions were generated from measured transverse and temporal laser beam profiles at the photocathode. The beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach within a factor of 2 the theoretical maximum set by the thermal energy and the accelerating field at the photocathode.

  11. Beam emittance reduction during operation of Indus-2

    Energy Technology Data Exchange (ETDEWEB)

    Fakhri, Ali Akbar, E-mail: fakhri@rrcat.gov.in; Kant, Pradeep; Ghodke, A. D.; Singh, Gurnam [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2015-11-15

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed.

  12. Graphene field emitters: A review of fabrication, characterization and properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Leifeng, E-mail: chlf@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yu, Hu; Zhong, Jiasong; Song, Lihui [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Jun, E-mail: wujun@hdu.edu.cn [Institute of Electron Device & Application, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018 (China); Su, Weitao [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2017-06-15

    Highlights: • The preparation, characterization and field emission properties for Gs are reviewed. • The review provides an updated progress on design and construction of Gs field emitters. • The review offers fundamental insights into understanding and design of Gs emitters. • The review can broach the subject and inspire readers in field of Gs based emitters. - Abstract: Graphenes are beneficial to electrons field emission due to its high aspect ratio, high carrier density, the larger carrier mobility, excellent electrical and thermal conductivity, excellent mechanical strength and chemical stability. In recent years, graphene or reduced oxide graphene field emitters have been successfully constructed by various methods such as chemical vapor deposition, chemical exfoliation, electrophoretic deposition, screen-printing and chemical synthesis methods. Graphene emitters are tried to construct in distribution with some angles or vertical orientation with respect to the substrate surface. The vertical alignment of graphene sheets or edges arrays can facilitate efficient electron emission from the atomically thick sheets. Therefore they have even more a low turn-on and threshold-field electronic field, high field enhancement factor, high current stability and high luminance. In this review, we shortly survey and discuss recent research progress in graphene field emission properties with particular an emphasis on their preparing method, characterization and applications in devices especially for vertical graphene and single layer graphene, also including their challenges and future prospects.

  13. Modular Power System Configured with Standard Product Hybrid DC-DC Converters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — VPT proposes an innovative concept whereby complex NASA space power electronic systems can be configured using a small number of qualified hybrid DC-DC converter and...

  14. DIAGNOSTIC/PROGNOSTIC EXPERIMENTS FOR CAPACITOR DEGRADATION AND HEALTH MONITORING IN DC-DC CONVERTERS

    Data.gov (United States)

    National Aeronautics and Space Administration — Studying and analyzing the ageing mechanisms of electronic components avionics in systems such as the GPS and INAV are of critical importance. In DC-DC power...

  15. DC electric springs with DC/DC converters

    DEFF Research Database (Denmark)

    Wang, Qingsong; Cheng, Ming; Jiang, Yunlei

    2016-01-01

    The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi-directio......The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi...

  16. Hierarchical Power Sharing Control in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami, Saeed; Mokhtari, Hossein; Blaabjerg, Frede

    2016-01-01

    Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [18], space applications [10], aircraft [12], offshore wind farms, electric vehicles [56], DC home systems [5, 20], and high-voltage DC transmission systems...

  17. Transverse emittance growth in staged laser-wakefield acceleration

    Directory of Open Access Journals (Sweden)

    T. Mehrling

    2012-11-01

    Full Text Available We present a study on the emittance evolution of electron bunches, externally injected into laser-driven plasma waves using the three-dimensional particle-in-cell (PIC code OSIRIS. Results show order-of-magnitude transverse emittance growth during the injection process, if the electron bunch is not matched to its intrinsic betatron motion inside the wakefield. This behavior is supported by analytic theory reproducing the simulation data to a percent level. The length over which the full emittance growth develops is found to be less than or comparable to the typical dimension of a single plasma module in current multistage designs. In addition, the analytic theory enables the quantitative prediction of emittance degradation in two consecutive accelerators coupled by free-drift sections, excluding this as a scheme for effective emittance-growth suppression, and thus suggests the necessity of beam-matching sections between acceleration stages with fundamental implications on the overall design of staged laser-wakefield accelerators.

  18. Electrical control of optical emitter relaxation pathways enabled by graphene

    Science.gov (United States)

    Tielrooij, K. J.; Orona, L.; Ferrier, A.; Badioli, M.; Navickaite, G.; Coop, S.; Nanot, S.; Kalinic, B.; Cesca, T.; Gaudreau, L.; Ma, Q.; Centeno, A.; Pesquera, A.; Zurutuza, A.; de Riedmatten, H.; Goldner, P.; García de Abajo, F. J.; Jarillo-Herrero, P.; Koppens, F. H. L.

    2015-03-01

    Controlling the energy flow processes and the associated energy relaxation rates of a light emitter is of fundamental interest and has many applications in the fields of quantum optics, photovoltaics, photodetection, biosensing and light emission. Advanced dielectric, semiconductor and metallic systems have been developed to tailor the interaction between an emitter and its environment. However, active control of the energy flow from an emitter into optical, electronic or plasmonic excitations has remained challenging. Here, we demonstrate in situ electrical control of the relaxation pathways of excited erbium ions, which emit light at the technologically relevant telecommunication wavelength of 1.5 μm. By placing the erbium at a few nanometres distance from graphene, we modify the relaxation rate by more than a factor of three, and control whether the emitter decays into electron-hole pairs, emitted photons or graphene near-infrared plasmons, confined to new paradigm for active (quantum) photonics and can be applied using any combination of light emitters and two-dimensional materials.

  19. JAERI 200 kV Electron Gun with an NEA-GaAs Photocathode

    CERN Document Server

    Nishitani, Tomohiro; Kikuzawa, Nobuhiro; John Minehara, Eisuke; Nagai, Ryoji; Nishimori, Nobuyuki; Sawamura, Masaru; Yamauchi, T

    2004-01-01

    The GaAs photocathode with negative electron affinity surface (NEA-GaAs) has been expected to be low emittance (<0.5 πmm・mrad) electron beam source. In order to generate low emittance electron beam required from ERL-FEL, we have started the developmental program of a 200keV electron gun with the NEA-GaAs photocathode for the first time in JAERI. An NEA surface has the problem that lifetime is limited by gun vacuum condition and by ion back bombardment between anode- and cathode-electrode. In order to long an NEA surface lifetime, the JAERI 200keV electron gun system consists of a 200kV DC-gun chamber on extreme high vacuum condition and an NEA activation chamber with load-lock system.

  20. ACCELERATING STRUCTURE: Ultra-low emittance X-band photocathode RF gun

    Science.gov (United States)

    Tang, Chuan-Xiang; Liu, Xiao-Han

    2009-06-01

    In this paper, we present the simulation results of a 1.6 cell X-band photocathode RF gun for ultra-low emittance electron beams. It will work at 9.3 GHz. The emittance, bunch length, electron energy and energy spread at the gun exit are optimized at bunch charge of 1pC using PARMELA. Electron bunches with emittance about 0.1 mm · mrad and bunch length less than 100 fs can be obtained from this gun. A PITZ type coupler is adopted in this gun and an initial simulation by MAFIA is also given in this paper.

  1. Proceedings of the Molecular Electronic Devices Workshop Held at Washington, DC on 23-24 March 1981.

    Science.gov (United States)

    1981-10-22

    be a nonenzyme 134 IN W ,- I A al3 tM .. N N: ’ N:c C - 1/ :N0_C-F-C=N: 4--> : NMC -Fe=C=N N <---- :N=C=Fe-C=N: C / I Z -• . 41 e N OcC 4jC ~III : L IN N...delocalization of electrons and is always negative. AS(s) is the change in entropy resulting from the change in the geometry of the switch and is usually...negative. AS(c) is the change in entropy resulting from the delocalization of electrons and is always positive. The Gibbs free energy of switching may be

  2. A relaxation-accelerated propagator method for calculations of electron energy distribution function and electron transport parameters in gas under dc electric fields

    Science.gov (United States)

    Sugawara, Hirotake

    2017-04-01

    A propagator method (PM), a numerical technique to solve the Boltzmann equation (BE) for the electron velocity or energy distribution function (EVDF/EEDF) of electron swarms in gases, was customized to obtain the equilibrium solution quickly. The PM calculates the number of electrons in cells defined in velocity space using an operator called the propagator or Green’s function. The propagator represents the intercellular transfer of electrons corresponding to the electron velocity change due to the acceleration by the electric field and the collisional events with gas molecules. The relaxation of the EVDF to its drift equilibrium solution proceeds with iterative propagator operations for the EVDF. Merits of the PM are that the series expansion of the EVDF as done in the BE analyses is not required and that time evolution of the electron swarm can be observed if necessary. On the other hand, in case only the equilibrium solution of the EVDF is wanted, the relaxation can be accelerated numerically. A demonstration achieved a shortening of the computational time by about three orders of magnitude. Furthermore, this scheme was applied to calculations of a set of electron transport parameters required in fluid-model simulations, i.e. the effective ionization frequency, the centroid drift velocity and the longitudinal diffusion coefficient, using the zeroth-, first- and second-order moment equations derived from the BE. A detailed description on the PM calculation was presented.

  3. Electronic media time and sedentary behaviors in children: Findings from the Built Environment and Active Play Study in the Washington DC area

    Directory of Open Access Journals (Sweden)

    Jennifer D. Roberts

    2017-06-01

    Full Text Available An objective of the Built Environment and Active Play (BEAP Study was to examine whether home built environment, bedroom electronic presence, parental rules and demographics predicted children's sedentary behavior (SB. In 2014, BEAP Study questionnaires were mailed to 2000 parents of children (7–12 years within the Washington DC area. SB-Duration (hours/day and SB-Frequency (days/week were assessed by two questions with multiple subparts relating to SB activity type (e.g. car riding and SB companionship (e.g. friends. Built environment, bedroom electronic presence, parental rules and demographic data were obtained through questionnaire items and ordered logistic regression models were used to examine whether these variables were associated with SB. Study sample included 144 children (female (50%; average age (9.7 years; White (56.3%; Black/African-American (23.7%; Asian-Americans (10.4%. Nearly 40% of the sample reported daily solitary SB with car riding being the most frequently reported type of SB. Children living on streets without a dead-end/cul-de-sac exhibited a higher odds in SB-Duration using electric media [2.61 (CI: 1.31, 5.18] and having no television in a child's bedroom was associated with a lower odds in SB-Frequency [0.048 (CI: 0.006, 0.393] and SB-Duration [0.085 (CI: 0.018, 0.395]. Non-Hispanic/Latino children were also found to have higher odds in solitary SB-Frequency when parental rules of electronic use were modeled [8.56 (CI: 1.11, 66.01]. Based on results from this cross-sectional study, home neighborhood built environment, bedroom electronic presence and absence of parental rules can significantly predict children's SB.

  4. Brightness limitations of cold field emitters caused by Coulomb interactions

    NARCIS (Netherlands)

    Cook, B.J.; Verduin, T.; Hagen, C.W.; Kruit, P.

    2010-01-01

    Emission theory predicts that high brightness cold field emitters can enhance imaging in the electron microscope. This (neglecting chromatic aberration) is because of the large (coherent) probe current available from a high brightness source and is based on theoretically determined values of reduced

  5. Auger Emitter Based Radiotherapy- A Possible New Treatment for Cancer

    DEFF Research Database (Denmark)

    Fredericia, Pil; Groesser, Torsten; Severin, Gregory

    2014-01-01

    be able to kill only the target cell while sparing the surrounding healthy tissue. In addition due to the multiple electrons released during the decay these emitters are more likely to produce at cluster of complex DNA damage which are considered to be much more harmful to the cell than dispersed DNA...

  6. Transverse Emittance Measurement at REX ISOLDE

    CERN Document Server

    Lanaia, D; Voulot, D

    2014-01-01

    The transverse emittance of REX-ISOLDE beams has been measured at 0.3 MeV/u (RFQ energy) and 2.85 MeV/u (maximum energy). This document compares RMS emittances measured with a slit-grid emittance meter (NTG emittance-meter) and RMS emittances measured with the quadrupole-scan method or three-gradient method. The results are compared with other measurements made with the slitgrid emittance meter in 2006 and 2008. The data treatment process is also described.

  7. Emittance Studies of the BNL/SLAC/UCLA 1.6 Cell Photocathode RF Gun

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, D.T.; /SLAC; Wang, X.J.; /Brookhaven; Miller, R.H.; /SLAC; Babzien, M.; Ben-Zvi, I.; /Brookhaven; Pellegrini, C.; /UCLA; Sheehan, J.; Skaritka, J.; /Brookhaven; Winick, H.; /SLAC; Woodle, M.; Yakimenko, V.; /Brookhaven

    2011-09-09

    The symmetrized 1.6 cell S-band photocathode gun developed by the BNL/SLAC/UCLA collaboration is in operation at the Brookhaven Accelerator Test Facility (ATF). A novel emittance compensation solenoid magnet has also been designed, built and is in operation at the ATF. These two subsystems form an emittance compensated photoinjector used for beam dynamics, advanced acceleration and free electron laser experiments at the ATF. The highest acceleration field achieved on the copper cathode is 150 MV/m, and the guns normal operating field is 130 MV/m. The maximum rf pulse length is 3 {mu}s. The transverse emittance of the photoelectron beam were measured for various injection parameters. The 1 nC emittance results are presented along with electron bunch length measurements that indicated that at above the 400 pC, space charge bunch lengthening is occurring. The thermal emittance, {epsilon}{sub o}, of the copper cathode has been measured.

  8. Early Oscillation Detection Technique for Hybrid DC/DC Converters

    Science.gov (United States)

    Wang, Bright L.

    2011-01-01

    Oscillation or instability is a situation that must be avoided for reliable hybrid DC/DC converters. A real-time electronics measurement technique was developed to detect catastrophic oscillations at early stages for hybrid DC/DC converters. It is capable of identifying low-level oscillation and determining the degree of the oscillation at a unique frequency for every individual model of the converters without disturbing their normal operations. This technique is specially developed for space-used hybrid DC/DC converters, but it is also suitable for most of commercial and military switching-mode power supplies. This is a weak-electronic-signal detection technique to detect hybrid DC/DC converter oscillation presented as a specific noise signal at power input pins. It is based on principles of feedback control loop oscillation and RF signal modulations, and is realized by using signal power spectral analysis. On the power spectrum, a channel power amplitude at characteristic frequency (CPcf) and a channel power amplitude at switching frequency (CPsw) are chosen as oscillation level indicators. If the converter is stable, the CPcf is a very small pulse and the CPsw is a larger, clear, single pulse. At early stage of oscillation, the CPcf increases to a certain level and the CPsw shows a small pair of sideband pulses around it. If the converter oscillates, the CPcf reaches to a higher level and the CPsw shows more high-level sideband pulses. A comprehensive stability index (CSI) is adopted as a quantitative measure to accurately assign a degree of stability to a specific DC/DC converter. The CSI is a ratio of normal and abnormal power spectral density, and can be calculated using specified and measured CPcf and CPsw data. The novel and unique feature of this technique is the use of power channel amplitudes at characteristic frequency and switching frequency to evaluate stability and identify oscillations at an early stage without interfering with a DC/DC converter s

  9. Breakdown voltage reliability improvement in gas-discharge tube surge protectors employing graphite field emitters

    Science.gov (United States)

    Žumer, Marko; Zajec, Bojan; Rozman, Robert; Nemanič, Vincenc

    2012-04-01

    Gas-discharge tube (GDT) surge protectors are known for many decades as passive units used in low-voltage telecom networks for protection of electrical components from transient over-voltages (discharging) such as lightning. Unreliability of the mean turn-on DC breakdown voltage and the run-to-run variability has been overcome successfully in the past by adding, for example, a radioactive source inside the tube. Radioisotopes provide a constant low level of free electrons, which trigger the breakdown. In the last decades, any concept using environmentally harmful compounds is not acceptable anymore and new solutions were searched. In our application, a cold field electron emitter source is used as the trigger for the gas discharge but with no activating compound on the two main electrodes. The patent literature describes in details the implementation of the so-called trigger wires (auxiliary electrodes) made of graphite, placed in between the two main electrodes, but no physical explanation has been given yet. We present experimental results, which show that stable cold field electron emission current in the high vacuum range originating from the nano-structured edge of the graphite layer is well correlated to the stable breakdown voltage of the GDT surge protector filled with a mixture of clean gases.

  10. Auger electron emitter against multiple myeloma - targeted endo-radio-therapy with {sup 125}I-labeled thymidine analogue 5-iodo-4'-thio-2'-deoxyuridine

    Energy Technology Data Exchange (ETDEWEB)

    Morgenroth, Agnieszka, E-mail: amorgenroth@ukaachen.de [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany); Nuclear Medicine Clinic, University Aachen, RWTH, Pauwelsstrasse 30, D-52074 Aachen (Germany); Dinger, Cornelia; Zlatopolskiy, Boris D.; Al-Momani, Ehab; Glatting, Gerhard [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany); Mottaghy, Felix M. [Nuclear Medicine Clinic, University Aachen, RWTH, Pauwelsstrasse 30, D-52074 Aachen (Germany); Reske, Sven N. [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany)

    2011-10-15

    Introduction: Multiple myeloma (MM) is a plasma cell malignancy characterized by accumulation of malignant, terminally differentiated B cells in the bone marrow. Despite advances in therapy, MM remains an incurable disease. Novel therapeutic approaches are, therefore, urgently needed. Auger electron-emitting radiopharmaceuticals are attractive for targeted nano-irradiation therapy, given that DNA of malignant cells is selectively addressed. Here we evaluated the antimyeloma potential of the Auger electron-emitting thymidine analogue {sup 125}I-labeled 5-iodo-4'-thio-2'-deoxyuridine ([{sup 125}I]ITdU). Methods: Cellular uptake and DNA incorporation of [{sup 125}I]ITdU were determined in fluorodeoxyuridine-pretreated KMS12BM, U266, dexamethasone-sensitive MM1.S and -resistant MM1.R cell lines. The effect of stimulation with interleukin 6 (IL6) or insulin-like growth factor 1 (IGF1) on the intracellular incorporation of [{sup 125}I]ITdU was investigated in cytokine-sensitive MM1.S and MM1.R cell lines. Apoptotic cells were identified using Annexin V. Cleavage of caspase 3 and PARP was visualized by Western blot. DNA fragmentation was investigated using laddering assay. Therapeutic efficiency of [{sup 125}I]ITdU was proven by clonogenic assay. Results: [{sup 125}I]ITdU was shown to be efficiently incorporated into DNA of malignant cells, providing a promising mechanism for delivering highly toxic Auger radiation emitters into tumor DNA. [{sup 125}I]ITdU had a potent antimyeloma effect in cell lines representing distinct disease stages and, importantly, in cell lines sensitive or resistant to the conventional therapeutic agent, but was not toxic for normal plasma and bone marrow stromal cells. Furthermore, [{sup 125}I]ITdU abrogated the protective actions of IL6 and IGF1 on MM cells. [{sup 125}I]ITdU induced massive damage in the DNA of malignant plasma cells, which resulted in efficient inhibition of clonogenic growth. Conclusion: These studies may provide a

  11. Combustion powered thermophotovoltaic emitter system

    Energy Technology Data Exchange (ETDEWEB)

    McHenry, R.S. [Naval Academy, Annapolis, MD (United States). Naval Architecture, Ocean and Marine Engineering

    1995-07-01

    The US Naval Academy (USNA) has recently completed an engineering design project for a high temperature thermophotovoltaic (TPV) photon emitter. The final apparatus was to be portable, completely self contained, and was to incorporate cycle efficiency optimization such as exhaust stream recuperation. Through computer modeling and prototype experimentation, a methane fueled emitter system was designed from structural ceramic materials to fulfill the high temperature requirements necessary for high system efficiency. This paper outlines the engineering design process, discusses obstacles and solutions encountered, and presents the final design.

  12. Studi Spektroskopi Electron Spin Resonance (Esr Lapisan Tipis Amorf Silikon Karbon (A-Sic:H Hasil Deposisi Metode Dc Sputtering

    Directory of Open Access Journals (Sweden)

    Rosari Saleh

    2002-04-01

    Full Text Available The dangling bond defect density in sputtered amorphous silicon carbon alloys have been studied by electron spin resonance (ESR. The results show that the spin density decreased slightly with increasing methane fl ow rate (CH4. The infl uence of carbon and hydrogen incorporation on g-value revealed that for CH4 fl ow rate up to 8 sccm, the ESR signal is dominated by defects characteristic of a-Si:H fi lms and for CH4 fl ow rate higher than 8 sccm the g-value decreased towards those usually found in a-C:H fi lms. Infrared (IR results suggest that as CH4 fl ow rate increases more carbon and hydrogen is incorporated into the fi lms to form Si-H, Si-C and C-H bonds. A direct relation between the IR results and the defect density and g-value is observed.

  13. Experimentally minimized beam emittance from an L-band photoinjector

    Directory of Open Access Journals (Sweden)

    M. Krasilnikov

    2012-10-01

    Full Text Available High brightness electron sources for linac based free-electron lasers (FELs are being developed at the Photo Injector Test facility at DESY, Zeuthen site (PITZ. Production of electron bunches with extremely small transverse emittance is the focus of the PITZ scientific program. The photoinjector optimization in 2008–2009 for a bunch charge of 1, 0.5, 0.25, and 0.1 nC resulted in measured emittance values which are beyond the requirements of the European XFEL [S. Rimjaem et al., Nucl. Instrum. Methods Phys. Res., Sect. A 671, 62 (2012NIMAER0168-900210.1016/j.nima.2011.12.101]. Several essential modifications were commissioned in 2010–2011 at PITZ, resulting in further improvement of the photoinjector performance. Significant improvement of the rf gun phase stability is a major contribution in the reduction of the measured transverse emittance. The old TESLA prototype booster was replaced by a new cut disk structure cavity. This allows acceleration of the electron beam to higher energies and supports much higher flexibility for stable booster operation as well as for longer rf pulses which is of vital importance especially for the emittance optimization of low charge bunches. The transverse phase space of the electron beam was optimized at PITZ for bunch charges in the range between 0.02 and 2 nC, where the quality of the beam measurements was preserved by utilizing long pulse train operation. The experimental optimization yielded worldwide unprecedented low normalized emittance beams in the whole charge range studied.

  14. Emittance growth in the DARHT Axis-II Downstream Transport

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Jr., Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schulze, Martin E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-14

    Using a particle-in-cell (PIC) code, we investigated the possibilities for emittance growth through the quadrupole magnets of the system used to transport the high-current electron beam from an induction accelerator to the bremsstrahlung converter target used for flash radiography. We found that even highly mismatched beams exhibited little emittance growth (< 6%), which we attribute to softening of their initial hard edge current distributions. We also used this PIC code to evaluate the accuracy of emittance measurements using a solenoid focal scan following the quadrupole magnets. If the beam is round after the solenoids, the simulations indicate that the measurement is highly accurate, but it is substantially inaccurate for elliptical beams

  15. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line

    Energy Technology Data Exchange (ETDEWEB)

    Alabau, M.; Faus-Golfe, A.; /Valencia U., IFIC; Alabau, M.; Bambade, P.; Brossard, J.; Le Meur, G.; Rimbault, C.; Touze, F.; /Orsay, LAL; Angal-Kalinin, D.; Jones, J.K.; /Daresbury; Appleby, R.; Scarfe, A.; /Manchester U.; Kuroda, S.; /KEK, Tsukuba; White, G.R.; Woodley, M.; /SLAC; Zimmermann, F.; /CERN

    2011-11-04

    Since several years, the vertical beam emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This longstanding problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experimented by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.

  16. Emittance of a Field Emission Electron Source

    Science.gov (United States)

    2010-01-05

    of frequency related to the inverse rise time, taken to be 50, 10, and 1 ps, respectively. Ldz Rdz Cdz FIG. 8. Color online RLC circuit used to...dimensions, and rise/fall time requirements for turning a beam on and off, as determined by the array’s RLC characterization. © 2010 American...the array is infinite. A systematic study by Rhee et al.31 for finite sized arrays obtains a similar expression to ours in their case 1 parallel beam

  17. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage...

  18. Experimental characterization of emittance growth induced by the nonuniform transverse laser distribution in a photoinjector

    Directory of Open Access Journals (Sweden)

    F. Zhou

    2002-09-01

    Full Text Available The emittance of a high-brightness electron beam from a photoinjector is affected by the transverse and longitudinal distributions of the laser beam illuminating the cathode. A nonuniform laser beam generates a nonuniform electron-beam distribution that experiences emittance growth on a time scale of the plasma period. Experiments were performed at the Brookhaven Accelerator Test Facility to investigate the emittance growth due to transversely nonuniform laser beams. Laser masks were fabricated to generate various laser distributions. Significant emittance growth was observed as the laser distribution deviated strongly from a uniform distribution. For cylindrically symmetric, nonuniform distributions, experimental results agree with PARMELA simulations. The emittance dependence on the bunch charge is linear as a function of the bunch charge for both uniform and nonuniform beams. For a uniform beam, the emittance measurements agree well with the predictions from PARMELA simulations, but the analytical approach overestimates the results. For nonuniform beams, analytical estimates are about 70% of the measurements. For noncylindrically symmetric, nonuniform beams, we observed that the emittance is linearly proportional to the rms laser nonuniformity and the best emittance for a perfectly uniform beam is extrapolated to be 1.07±0.13   mm mrad at 0.5 nC.

  19. Measured Emittance Dependence on the Injection Method in Laser Plasma Accelerators

    Science.gov (United States)

    Barber, S. K.; van Tilborg, J.; Schroeder, C. B.; Lehe, R.; Tsai, H.-E.; Swanson, K. K.; Steinke, S.; Nakamura, K.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2017-09-01

    Single-shot, charge-dependent emittance measurements of electron beams generated by a laser plasma accelerator (LPA) reveal that shock-induced density down-ramp injection produces beams with normalized emittances a factor of 2 smaller than beams produced via ionization injection. Such a comparison is made possible by the tunable LPA setup, which allows electron beams with nearly identical central energy and peak spectral charge density to be produced using the two distinct injection mechanisms. Parametric measurements of this type are essential for the development of LPA-based applications which ultimately require high charge density and low emittance.

  20. The cataphoretic emitter effect exhibited in high intensity discharge lamp electrodes

    Science.gov (United States)

    Mentel, Juergen

    2018-01-01

    A mono-layer of atoms, electropositive with respect to the substrate atoms, forms a dipole layer, reducing its work function. Such a layer is generated by diffusion of emitter material from the interior of the substrate, by vapour deposition or by deposition of emitter material onto arc electrodes by cataphoresis. This cataphoretic emitter effect is investigated within metal halide lamps with transparent YAG ceramic burners, and within model lamps. Within the YAG lamps, arcs are operated with switched-dc current between rod shaped tungsten electrodes in high pressure Hg vapour seeded with metal iodides. Within the model lamps, dc arcs are operated between rod-shaped tungsten electrodes—one doped—in atmospheric pressure Ar. Electrode temperatures are determined by 1λ -pyrometry, combined with simulation of the electrode heat balance. Plasma temperatures, atom and ion densities of emitter material are determined by emission and absorption spectroscopy. Phase resolved measurements in YAG lamps seeded with CeI3, CsI, DyI3, TmI3 and LaI3 show, within the cathodic half period, a reduction of the electrode temperature and an enhanced metal ion density in front of the electrode, and an opposite behavior after phase reversal. With increasing operating frequency, the state of the cathode overlaps onto the anodic phase—except for Cs, being low in adsorption energy. Generally, the phase averaged electrode tip temperature is reduced by seeding a lamp with emitter material; its height depends on admixtures. Measurements at tungsten electrodes doped with ThO2, La2O3 and Ce2O3 within the model lamp show that evaporated emitter material is redeposited by an emitter ion current onto the electrode surface. It reduces the work function of tungsten cathodes above the evaporation temperature of the emitter material, too; and also of cold anodes, indicating a field reversal in front of them. The formation of an emitter spot at low cathode temperature and high emitter material

  1. Demonstration of low emittance in the Cornell energy recovery linac injector prototype

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2013-07-01

    Full Text Available We present a detailed study of the six-dimensional phase space of the electron beam produced by the Cornell Energy Recovery Linac Photoinjector, a high-brightness, high repetition rate (1.3 GHz DC photoemission source designed to drive a hard x-ray energy recovery linac (ERL. A complete simulation model of the injector has been constructed, verified by measurement, and optimized. Both the horizontal and vertical 2D transverse phase spaces, as well as the time-resolved (sliced horizontal phase space, were simulated and directly measured at the end of the injector for 19 and 77 pC bunches at roughly 8 MeV. These bunch charges were chosen because they correspond to 25 and 100 mA average current if operating at the full 1.3 GHz repetition rate. The resulting 90% normalized transverse emittances for 19   (77  pC/bunch were 0.23±0.02 (0.51±0.04  μm in the horizontal plane, and 0.14±0.01 (0.29±0.02  μm in the vertical plane, respectively. These emittances were measured with a corresponding bunch length of 2.1±0.1 (3.0±0.2  ps, respectively. In each case the rms momentum spread was determined to be on the order of 10^{-3}. Excellent overall agreement between measurement and simulation has been demonstrated. Using the emittances and bunch length measured at 19  pC/bunch, we estimate the electron beam quality in a 1.3 GHz, 5 GeV hard x-ray ERL to be at least a factor of 20 times better than that of existing storage rings when the rms energy spread of each device is considered. These results represent a milestone for the field of high-brightness, high-current photoinjectors.

  2. Transformation of polycrystalline tungsten to monocrystalline tungsten W(100) and its potential application in Schottky emitters

    NARCIS (Netherlands)

    Dokania, A.K.; Hendrikx, R.; Kruit, P.

    2009-01-01

    The electron sources in electron microscopes and electron lithography machines often consist of small diameter W(100) wires, etched to form a sharp tip. The electron emission is facilitated by the Schottky effect, thus the name Schottky emitter. The authors are investigating the feasibility of

  3. Electronic transport in the multi-terminal graphene nanodevices

    Energy Technology Data Exchange (ETDEWEB)

    Ye, En-Jia [Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou, 310027 (China); Lan, Jin; Sui, Wen-Quan [Zhejiang–California International Nanosystem Institute, Electronic Department, Zhejiang University, Hangzhou, 310029 (China); Sun, Chang Q. [School of Electric and Electronic Engineering, Nanyang Technological University, Singapore, 639798 (Singapore); Zhao, Xuean, E-mail: zhaoxa@zju.edu.cn [Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou, 310027 (China)

    2012-07-30

    We examined the ac transport attribute of the multi-terminal structures in the absence and presence of magnetic field. We found that the ac response depends on the structural configurations and that the admittance varies with the features of the attached nanoribbons. In the vicinity of Dirac point the dc conductance manifests a dip or peak and the imaginary part (emittance) vanishes or not, depending on whether the attached ribbon is semiconductive or metallic. In the presence of magnetic field, the emittance becomes asymmetric reflecting the dynamic behaviors of electron and hole. -- Highlights: ► Ac transport of multi-terminal graphene nanoribbon structures is studied in the absence and presence of magnetic field. ► The admittances of the devices are related to the configurations of attached ribbons. ► The negative and positive signs of the imaginary part of admittance (emittance) relate to the capacitive and inductive responses of the system. ► In the presence of magnetic field, emittance becomes asymmetric reflecting the dynamic behaviors of electron and hole.

  4. An L-Band Polarized Electron PWT Photoinjector for the International Linear Collider (ILC)

    CERN Document Server

    Yu, David; Chen Ping; Lundquist, Martin; Luo, Yan; Smirnov, Alexei Yu

    2005-01-01

    A multi-cell, standing-wave, L-band, p-mode, plane-wave-transformer (PWT) photoinjector with an integrated photocathode in a novel linac structure is proposed by DULY Research Inc. as a polarized electron source. The PWT photoinjector is capable of operation in ultra high vacuum and moderate field gradient. Expected performance of an L-band polarized electron PWT injector operating under the parameters for the International Linear Collider is presented. The projected normalized transverse rms emittance is an order of magnitude lower than that produced with a polarized electron dc gun followed by subharmonic bunchers.

  5. Sources of Emittance in RF Photocathode Injectors

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-12-11

    Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and applied science. One important beam technology for both is the electron source which, for many of these instruments, is the photocathode RF gun. The invention of the photocathode gun and the concepts of emittance compensation and beam matching in the presence of space charge and RF forces have made these high-quality beams possible. Achieving even brighter beams requires a taking a finer resolution view of the electron dynamics near the cathode during photoemission and the initial acceleration of the beam. In addition, the high brightness beam is more sensitive to degradation by the optical aberrations of the gun’s RF and magnetic lenses. This paper discusses these topics including the beam properties due to fundamental photoemission physics, space charge effects close to the cathode, and optical distortions introduced by the RF and solenoid fields. Analytic relations for these phenomena are derived and compared with numerical simulations.

  6. A high-brightness thermionic microwave electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Borland, Michael [Stanford Univ., CA (United States)

    1991-02-01

    In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun`s performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ``State-of-the-art`` microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of < 10 π • mec • μm for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread ±10%. These emittances are for up to 5 x 109e- per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically < 30 π • me • μm.

  7. A resonant dc-dc power converter assembly

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the s......The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor...

  8. Emitter frequency refinement based on maximum likelihood

    Science.gov (United States)

    Xu, Xin; Wang, Huijuan

    2015-07-01

    Frequency estimation via signal sorting is widely recognized as one of the most practical technologies in signal processing. However, the estimated frequencies via signal sorting may be inaccurate and biased due to signal fluctuation under different emitter working modes, problems of transmitter circuit, environmental noises or certain unknown interference sources. Therefore, it has become an important issue to further analyze and refine signal frequencies after signal sorting. To address the above problem, we have brought forward an iterative frequency refinement method based on maximum likelihood. Iteratively, the initial estimated signal frequency values are refined. Experimental results indicate that the refined signal frequencies are more informative than the initial ones. As another advantage of our method, noises and interference sources could be filtered out simultaneously. The efficiency and flexibility enables our method to apply in a wide application area, i.e., communication, electronic reconnaissance and radar intelligence analysis.

  9. Alpha particle emitters in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, D.R.

    1989-09-01

    Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs.

  10. Metal halide perovskite light emitters

    Science.gov (United States)

    Kim, Young-Hoon; Cho, Himchan; Lee, Tae-Woo

    2016-01-01

    Twenty years after layer-type metal halide perovskites were successfully developed, 3D metal halide perovskites (shortly, perovskites) were recently rediscovered and are attracting multidisciplinary interest from physicists, chemists, and material engineers. Perovskites have a crystal structure composed of five atoms per unit cell (ABX3) with cation A positioned at a corner, metal cation B at the center, and halide anion X at the center of six planes and unique optoelectronic properties determined by the crystal structure. Because of very narrow spectra (full width at half-maximum ≤20 nm), which are insensitive to the crystallite/grain/particle dimension and wide wavelength range (400 nm ≤ λ ≤ 780 nm), perovskites are expected to be promising high-color purity light emitters that overcome inherent problems of conventional organic and inorganic quantum dot emitters. Within the last 2 y, perovskites have already demonstrated their great potential in light-emitting diodes by showing high electroluminescence efficiency comparable to those of organic and quantum dot light-emitting diodes. This article reviews the progress of perovskite emitters in two directions of bulk perovskite polycrystalline films and perovskite nanoparticles, describes current challenges, and suggests future research directions for researchers to encourage them to collaborate and to make a synergetic effect in this rapidly emerging multidisciplinary field. PMID:27679844

  11. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  12. Achievement of ultra-low emittance beam in the ATF damping ring

    CERN Document Server

    Honda, Y; Araki, S; Bane, Karl Leopold Freitag; Brachmann, A; Frisch, J; Fukuda, M; Hasegawa, K; Hayano, H; Hendrickson, L; Higashi, Y; Higo, T; Hirano, K; Hirose, T; Iida, K; Imai, T; Inoue, Y; Karataev, P; Kubo, K; Kurihara, Y; Kuriki, M; Kuroda, R; Kuroda, S; Luo, X; Matsuda, M; McCormick, D; Muto, T; Nakajima, K; Nelson, J; Nomura, M; Ohashi, A; Okugi, T; Omori, T; Ross, M; Sakai, H; Sakai, I; Sasao, N; Smith, S; Suzuki, T; Takano, M; Takashi, N; Taniguchi, T; Terunuma, N; Toge, N; Turner, J; Urakawa, J; Vogel, V; Wolski, A; Woodley, M; Yamazaki, I; Yamazaki, Y; Yocky, J; Young, A; Zimmermann, Frank

    2003-01-01

    We report on the smallest vertical emittance achieved in single-bunch-mode operation of the ATF. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured is 4 pm in the limit of zero current. It increases by a factor of 1.5 for a bunch intensity of 10^10 electrons. There are no discrepancies between the measured data and the calculations of intra-beam scattering.

  13. Controlling Singlet-Triplet Energy Splitting for Deep-Blue Thermally Activated Delayed Fluorescence Emitters.

    Science.gov (United States)

    Cui, Lin-Song; Nomura, Hiroko; Geng, Yan; Kim, Jong Uk; Nakanotani, Hajime; Adachi, Chihaya

    2017-02-01

    The development of efficient metal-free organic emitters with thermally activated delayed fluorescence (TADF) properties for deep-blue emission is still challenging. A new family of deep-blue TADF emitters based on a donor-acceptor architecture has been developed. The electronic interaction between donor and acceptor plays a key role in the TADF mechanism. Deep-blue OLEDs fabricated with these TADF emitters achieved high external quantum efficiencies over 19.2 % with CIE coordinates of (0.148, 0.098). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Photosensitivity of p-type black Si field emitter arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mingels, S., E-mail: smingels@uni-wuppertal.de; Porshyn, V.; Lützenkirchen-Hecht, D.; Müller, G. [School of Mathematics and Natural Sciences, Physics Department, University of Wuppertal, Wuppertal 42119 (Germany); Prommesberger, C.; Langer, C.; Schreiner, R. [Faculty of General Sciences and Microsystems Technology, OTH Regensburg, Regensburg 93053 (Germany)

    2016-04-28

    We have investigated the properties of black Si field emitter arrays under strong electric fields and laser illumination. A low onset field of 1.8 MV/m for an emission current of 1 nA was obtained. A pronounced saturation region of the dark and photo-enhanced current was observed, which provided a short-term stability of 0.1% at 0.4 μA and 0.7% at 1.0 μA, respectively. As maximum value for the photosensitivity, an on-off current switching ratio of 43 reaching about 13 μA was achieved at a laser power of 15 mW. Electron spectra in the dark and under laser illumination are presented, showing a current and light-sensitive voltage drop across the emitters as well as hints for hot electron emission.

  15. Source brightness and useful beam current of carbon nanotubes and other very small emitters

    NARCIS (Netherlands)

    Kruit, P.; Bezuijen, M.; Barth, J.E.

    2006-01-01

    The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky

  16. Normal spectral emittance of Inconel 718 aeronautical alloy coated with yttria stabilized zirconia films

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Campo, L. del [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.es [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Emittance of Inconel 718 coated with plasma sprayed yttria stabilized zirconia. Black-Right-Pointing-Pointer The coating is opaque for {lambda} > 9 {mu}m and semi-transparent for {lambda} < 9 {mu}m. Black-Right-Pointing-Pointer In the semi-transparent region the emittance decreases with coating thickness. Black-Right-Pointing-Pointer 300 {mu}m thick coatings are still semi-transparent. Black-Right-Pointing-Pointer In the opaque region the surface roughness determines the emittance level. - Abstract: Knowledge of the radiative behaviour of the yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) is needed to perform radiative heat transfer calculations in industrial applications. In this paper, normal spectral emittance experimental data of atmospheric plasma sprayed (PS) YSZ films layered on Inconel 718 substrates are shown. The spectral emittance was measured between 2.5 and 22 {mu}m on samples with film thicknesses ranging from 20 to 280 {mu}m. The samples were heated in a controlled environment, and the emittance was measured for several temperatures between 330 and 730 Degree-Sign C. The dependence of the spectral emittance with film thickness, surface roughness and temperature has been studied and compared with the available results for YSZ TBCs obtained by electron-beam physical vapour deposition. The PS-TBC samples show a Christiansen point at {lambda} = 12.8 {mu}m. The films are semi-transparent for {lambda} < 9 {mu}m, and opaque for {lambda} > 9 {mu}m. In the semi-transparent region, the contribution of the radiation emitted by the Inconel 718 substrate to the global emittance of the samples is analysed. In addition, the influence of the roughness in the emittance values in the opaque spectral region is discussed. Finally, the total normal emittance is obtained as a function of the TBC thickness.

  17. Low Emittance Gun Project based on Field Emission

    CERN Document Server

    Ganter, Romain; Dehler, M; Gobrecht, Jens; Gough, Chris; Ingold, Gerhard; Leemann, Simon C; Shing-Bruce-Li, Kevin; Paraliev, Martin; Pedrozzi, Marco; Raguin, Jean Yves; Rivkin, Leonid; Schlott, Volker; Sehr, Harald; Streun, Andreas; Wrulich, Albin F; Zelenika, Sasa

    2004-01-01

    The design of an electron gun capable of producing beam emittance one order of magnitude lower than current technology would reduce considerably the cost and size of a free electron laser emitting at 0.1nm. Field emitter arrays (FEAs) including a gate and a focusing layer are an attractive technology for such high brightness sources. Electrons are extracted from micrometric tips thanks to voltage pulses between gate and tips. The focusing layer should then reduce the initial divergence of each emitted beamlets. This FEA will be inserted in a high gradient diode configuration coupled with a radiofrequency structure. In the diode part very high electric field pulses (several hundreds of MV/m) will limit the degradation of emittance due to space charge effect. This first acceleration will be obtained with high voltage pulses (typically a megavolt in a few hundred of nanoseconds) synchronized with the low voltage pulses applied to the FEA (typically one hundred of volts in one nanosecond at frequency below kilohe...

  18. DC grid for home applications

    Science.gov (United States)

    Elangovan, D.; Archana, R.; Jayadeep, V. J.; Nithin, M.; Arunkumar, G.

    2017-11-01

    More than fifty percent Indian population do not have access to electricity in daily lives. The distance between the power generating stations and the distribution centers forms one of the main reasons for lack of electrification in rural and remote areas. Here lies the importance of decentralization of power generation through renewable energy resources. In the present world, electricity is predominantly powered by alternating current, but most day to day devices like LED lamps, computers and electrical vehicles, all run on DC power. By directly supplying DC to these loads, the number of power conversion stages was reduced, and overall system efficiency increases. Replacing existing AC network with DC is a humongous task, but with power electronic techniques, this project intends to implement DC grid at a household level in remote and rural areas. Proposed work was designed and simulated successfully for various loads amounting to 250 W through appropriate power electronic convertors. Maximum utilization of the renewable sources for domestic and commercial application was achieved with the proposed DC topology.

  19. Performance of pressure-compensating emitters using treated sewage effluent for irrigation

    Directory of Open Access Journals (Sweden)

    João A. Fischer Filho

    Full Text Available ABSTRACT This study aimed to evaluate the flow variation of pressure-compensating emitters using treated sewage effluent (TSE. A drip irrigation system with four types of pressure-compensating emitters (G1 - Naan Dan Jain Model Top Drip, G2 - Naan Dan Jain Model Naan PC, G3 - Drip-Plan, G4 - Naan Dan Jain Model Naan Amnon was installed with TSE from the sewage treatment station, filtered through a disc filter (120 mesh. Seven evaluations of flow rate of the drippers were performed (0, 100, 200, 300, 400, 500 and 600 h of operation operating at 100 kPa. The experimental design was completely randomized in a 4 x 7 factorial arrangement (4 models and 7 times with four replicates and Tukey test to compare the means. The relative flow rate (Qr, flow rate coefficient of variation (CVQ and degree of clogging (DC were determined. It was found that the models of emitters were not much susceptible to clogging during the operation of the system. The G4 model showed better performance compared with the others, presenting mean Qr of 99.92%, CVQ of 2.69% and DC of 1.19% at the end of the experiment. The results revealed that emitters are affected by the time of use of TSE.

  20. Pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2008-01-01

    This book studies switch-mode power supplies (SMPS) in great detail. This type of converter changes an unregulated DC voltage into a high-frequency pulse-width modulated (PWM) voltage controlled by varying the duty cycle, then changes the PWM AC voltage to a regulated DC voltage at a high efficiency by rectification and filtering. Used to supply electronic circuits, this converter saves energy and space in the overall system. With concept-orientated explanations, this book offers state-of-the-art SMPS technology and promotes an understanding of the principle operations of PWM converters,

  1. Laboratory manual for pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2015-01-01

    Designed to complement a range of power electronics study resources, this unique lab manual helps students to gain a deep understanding of the operation, modeling, analysis, design, and performance of pulse-width modulated (PWM) DC-DC power converters.  Exercises focus on three essential areas of power electronics: open-loop power stages; small-signal modeling, design of feedback loops and PWM DC-DC converter control schemes; and semiconductor devices such as silicon, silicon carbide and gallium nitride. Meeting the standards required by industrial employers, the lab manual combines program

  2. Quantum efficiency temporal response and lifetime of a GaAs cathode in SRF electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Wang, E.; Ben-Zvi, I.; Kewisch, J.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

    2010-05-23

    RF electron guns with a strained super lattice GaAs cathode can generate polarized electron beam of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface. In a normal conducting RF gun, the extremely high vaccum required by these cathodes can not be met. We report on an experiment with a superconducting SRF gun, which can maintain a vacuum of nearly 10-12 torr because of cryo-pumping at the temperature of 4.2K. With conventional activation, we obtained a QE of 3% at 532 nm, with lifetime of nearly 3 days in the preparation chamber. We plan to use this cathode in a 1.3 GHz 1/2 cell SRF gun to study its performance. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper. Future particle accelerators such as eRHIC and ILC require high brightness, high current polarized electrons Recently, using a superlattice crystal, the maximum polarization of 95% was reached. Activation with Cs,O lowers the electron affinity and makes it energetically possible for all the electrons excited in to the conduction band and reach the surface to escape into the vacuum. Presently the polarized electron sources are based on DC gun, such as that at the CEBAF at Jlab. In these devices, the life time of the cathode is extended due to the reduced back bombardment in their UHV conditions. However, the low accelerating gradient of the DC guns lead to poor longitudinal emittance. The higher accelerating gradient of the RF gun generates low emittance beams. Superconducting RF guns combine the excellent vacuum conditions of the DC guns with the higher accelerating gradients of the RF guns and provide potentially a long lived cathode with very low transverse and longitudinal emittance. In our work at BNL, we successfully activated the GaAs. The quantum efficient is 3% at 532 nm and is

  3. Development of the electron cooling simulation program for JLEIC

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, He [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Chen, Jie [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Li, Rui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Huang, He [Old Dominion Univ., Norfolk, VA (United States); Luo, Li-Shi [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during collision at the collider ring. A new electron cooling process simulation program has been developed to fulfill the requirements of the JLEIC electron cooler design. The new program allows the users to calculate the electron cooling rate and simulate the cooling process with either DC or bunched electron beam to cool either coasting or bunched ion beam. It has been benchmarked with BETACOOL in aspect of accuracy and efficiency. In typical electron cooling process of JLEIC, the two programs agree very well and we have seen a significant improvement of computational speed using the new one. Being adaptive to the modern multicore hardware makes it possible to further enhance the efficiency for computationally intensive problems. The new program is being actively used in the electron cooling study and cooler design for JLEIC. We will present our models and some simulation results in this paper.

  4. Soft switched DC-DC converter

    Science.gov (United States)

    Subramanian, K.; Kavitha, K. V. N.; Saravanan, K.

    2017-11-01

    A soft switched single switch isolated dc-dc conveys proposed in this paper. This converter works on the principle of zero current switching (zcs) and zero voltage switching (zvs). The circuit comprises lossless snubber with low rating. The switch works on zcs during turn on and zvs during turnoff. The diodes are based on zcs turn on and turnoff conditions. This paper presents the concept of soft switching and its applications to dc-dc converter. The losses due to soft switching and hard switching are compared.

  5. IGBT Based DC/DC Converter

    Directory of Open Access Journals (Sweden)

    M. Akherraz

    1997-12-01

    Full Text Available This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high  frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.

  6. Coupling single emitters to quantum plasmonic circuits

    DEFF Research Database (Denmark)

    Huck, Alexander; Andersen, Ulrik Lund

    2016-01-01

    In recent years, the controlled coupling of single-photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic nonlinearity on a nanoscaled platform. In this article, we will review the recent progress on coupling single emitters...

  7. Robust multiplatform RF emitter localization

    Science.gov (United States)

    Al Issa, Huthaifa; Ordóñez, Raúl

    2012-06-01

    In recent years, position based services has increase. Thus, recent developments in communications and RF technology have enabled system concept formulations and designs for low-cost radar systems using state-of-the-art software radio modules. This research is done to investigate a novel multi-platform RF emitter localization technique denoted as Position-Adaptive RF Direction Finding (PADF). The formulation is based on the investigation of iterative path-loss (i.e., Path Loss Exponent, or PLE) metrics estimates that are measured across multiple platforms in order to autonomously adapt (i.e. self-adjust) of the location of each distributed/cooperative platform. Experiments conducted at the Air-Force Research laboratory (AFRL) indicate that this position-adaptive approach exhibits potential for accurate emitter localization in challenging embedded multipath environments such as in urban environments. The focus of this paper is on the robustness of the distributed approach to RF-based location tracking. In order to localize the transmitter, we use the Received Signal Strength Indicator (RSSI) data to approximate distance from the transmitter to the revolving receivers. We provide an algorithm for on-line estimation of the Path Loss Exponent (PLE) that is used in modeling the distance based on Received Signal Strength (RSS) measurements. The emitter position estimation is calculated based on surrounding sensors RSS values using Least-Square Estimation (LSE). The PADF has been tested on a number of different configurations in the laboratory via the design and implementation of four IRIS wireless sensor nodes as receivers and one hidden sensor as a transmitter during the localization phase. The robustness of detecting the transmitters position is initiated by getting the RSSI data through experiments and then data manipulation in MATLAB will determine the robustness of each node and ultimately that of each configuration. The parameters that are used in the functions are

  8. Oxidation and emittance of superalloys in heat shield applications

    Science.gov (United States)

    Wiedemann, K. E.; Clark, R. K.; Unnam, J.

    1986-01-01

    Recently developed superalloys that form alumina coatings have a high potential for heat shield applications for advanced aerospace vehicles at temperatures above 1095C. Both INCOLOY alloy MA 956 (of the Inco Alloys International, Inc.), an iron-base oxide-dispersion-strengthened alloy, and CABOT alloy No. 214 (of the Cabot Corporation), an alumina-forming nickel-chromium alloy, have good oxidation resistance and good elevated temperature strength. The oxidation resistance of both alloys has been attributed to the formation of a thin alumina layer (alpha-Al2O3) at the surface. Emittance and oxidation data were obtained for simulated Space Shuttle reentry conditions using a hypersonic arc-heated wind tunnel. The surface oxides and substrate alloys were characterized using X-ray diffraction and scanning and transmission electron microscopy with an energy-dispersive X-ray analysis unit. The mass loss and emittance characteristics of the two alloys are discussed.

  9. A New Design Strategy for Efficient Thermally Activated Delayed Fluorescence Organic Emitters: From Twisted to Planar Structures

    KAUST Repository

    Chen, Xiankai

    2017-10-17

    In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔEST ) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔEST with a large fluorescence oscillator strength. Since this strategy goes beyond the traditional framework of structurally twisted, charge-transfer type emitters, importantly, it opens the way for coplanar molecules to be efficient TADF emitters. Here, a new emitter, composed of azatriangulene and diphenyltriazine moieties, is theoretically designed, which is coplanar due to intramolecular H-bonding interactions. The synthesis of this hexamethylazatriangulene-triazine (HMAT-TRZ) emitter and its preliminary photophysical characterizations point to HMAT-TRZ as a potential efficient TADF emitter.

  10. Engineering and localization of quantum emitters in large hexagonal boron nitride layers

    CERN Document Server

    Choi, Sumin; ElBadawi, Christopher; Lobo, Charlene; Wang, Xuewen; Juodkazis, Saulius; Seniutinas, Gediminas; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Hexagonal boron nitride (hBN) is a wide bandgap van der Waals material that has recently emerged as promising platform for quantum photonics experiments. In this work we study the formation and localization of narrowband quantum emitters in large flakes (up to tens of microns wide) of hBN. The emitters can be activated in as-grown hBN by electron irradiation or high temperature annealing, and the emitter formation probability can be increased by ion implantation or focused laser irradiation of the as-grown material. Interestingly, we show that the emitters are always localized at edges of the flakes, unlike most luminescent point defects in 3D materials. Our results constitute an important step on the road map of deploying hBN in nanophotonics applications.

  11. Time-Resolved Emittance Characterization of an Induction Linac Beam using Optical Transition Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Le Sage, G P

    2002-11-05

    An induction linac is used by Lawrence Livermore National Laboratory to perform radiographic testing at the Flash X-ray Radiography facility. Emittance characterization is important since x-ray spot size impacts the resolution of shadow-graphs. Due to the long pulse length, high current, and beam energy, emittance measurement using Optical Transition Radiation is an attractive alternative for reasons that will be described in the text. The utility of OTR-based emittance measurement has been well demonstrated for both RF and induction linacs. We describe the time-resolved emittance characterization of an induction linac electron beam. We have refined the optical collection system for the induction linac application, and have demonstrated a new technique for probing the divergence of a subset of the beam profile. The experimental apparatus, data reduction, and conclusions will be presented. Additionally, a new scheme for characterizing the correlation between beam divergence and spatial coordinates within the beam profile will be described.

  12. Measurement of a small vertical emittance with a laser wire beam profile monitor

    Directory of Open Access Journals (Sweden)

    Hiroshi Sakai

    2002-12-01

    Full Text Available We describe in this paper a measurement of vertical emittance in the Accelerator Test Facility (ATF damping ring at KEK with a laser wire beam profile monitor. This monitor is based on the Compton scattering process of electrons with a laser light target which is produced by injecting a cw laser beam into a Fabry-Perot optical cavity. We installed the monitor at a straight section of the damping ring and measured the vertical emittance with three different ring conditions. In all cases, the ATF ring was operated at 1.28 GeV in a single bunch mode. When the ring was tuned for ultralow emittance, the vertical emittance of ε_{y}=(1.18±0.08×10^{-11}   mrad was achieved. This shows that the ATF damping ring has realized its target value also vertically.

  13. Time-Resolved Emittance Characterization of an Induction Linac Beam using Optical Transition Radiation

    CERN Document Server

    Le Sage, G P

    2002-01-01

    An induction linac is used by Lawrence Livermore National Laboratory to perform radiographic testing at the Flash X-ray Radiography facility. Emittance characterization is important since x-ray spot size impacts the resolution of shadow-graphs. Due to the long pulse length, high current, and beam energy, emittance measurement using Optical Transition Radiation is an attractive alternative for reasons that will be described in the text. The utility of OTR-based emittance measurement has been well demonstrated for both RF and induction linacs. We describe the time-resolved emittance characterization of an induction linac electron beam. We have refined the optical collection system for the induction linac application, and have demonstrated a new technique for probing the divergence of a subset of the beam profile. The experimental apparatus, data reduction, and conclusions will be presented. Additionally, a new scheme for characterizing the correlation between beam divergence and spatial coordinates within the b...

  14. Positron emitter labeled enzyme inhibitors

    Science.gov (United States)

    Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

    1987-05-22

    This invention involved a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide in activators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.

  15. Unconventional Molecular Design Approach of High-Efficiency Deep Blue Thermally Activated Delayed Fluorescent Emitters Using Indolocarbazole as an Acceptor.

    Science.gov (United States)

    Seo, Jeong-A; Im, Yirang; Han, Si Hyun; Lee, Chil Won; Lee, Jun Yeob

    2017-11-01

    Unconventional blue thermally activated delayed fluorescent emitters having electron-donating type indolocarbazole as an acceptor were developed by attaching carbazolylcarbazole or acridine donors to the indolocarbazole acceptor. Three compounds were derived from the indolocarbazole acceptor. The indolocarbazole-acridine combined products showed efficient delayed fluorescent behavior and a high quantum efficiency of 19.5% with a color coordinate of (0.15, 0.16) when they were evaluated as thermally activated delayed fluorescent emitters in deep blue fluorescent devices. This is the first demonstration of the use of electron-donating carbazole-derived moieties as efficient acceptor units of blue thermally activated delayed fluorescent emitters.

  16. Modeling of Diamond Field-Emitter-Arrays for high brightness photocathode applications

    Science.gov (United States)

    Kwan, Thomas; Huang, Chengkun; Piryatinski, Andrei; Lewellen, John; Nichols, Kimberly; Choi, Bo; Pavlenko, Vitaly; Shchegolkov, Dmitry; Nguyen, Dinh; Andrews, Heather; Simakov, Evgenya

    2017-10-01

    We propose to employ Diamond Field-Emitter-Arrays (DFEAs) as high-current-density ultra-low-emittance photocathodes for compact laser-driven dielectric accelerators capable of generating ultra-high brightness electron beams for advanced applications. We develop a semi-classical Monte-Carlo photoemission model for DFEAs that includes carriers' transport to the emitter surface and tunneling through the surface under external fields. The model accounts for the electronic structure size quantization affecting the transport and tunneling process within the sharp diamond tips. We compare this first principle model with other field emission models, such as the Child-Langmuir and Murphy-Good models. By further including effects of carrier photoexcitation, we perform simulations of the DFEAs' photoemission quantum yield and the emitted electron beam. Details of the theoretical model and validation against preliminary experimental data will be presented. Work ssupported by LDRD program at LANL.

  17. Foundations of DC plasma sources

    Science.gov (United States)

    Tomas Gudmundsson, Jon; Hecimovic, Ante

    2017-12-01

    A typical dc discharge is configured with the negative cathode at one end and a positive anode at the other end, separated by a gas filled gap, placed inside a long glass cylinder. A few hundred volts between the cathode and anode is required to maintain the discharge. The type of discharge that is formed between the two electrodes depends upon the pressure of the working gas, the nature of the working gas, the applied voltage and the geometry of the discharge. We discuss the current–voltage characteristics of the discharge as well as the distinct structure that develops in the glow discharge region. The dc glow discharge appears in the discharge current range from μA to mA at 0.5–300 Pa pressure. We discuss the various phenomena observed in the dc glow discharge, including the cathode region, the positive column, and striations. The dc glow discharge is maintained by the emission of secondary electrons from the cathode target due to the bombardment of ions. For decades, the dc glow discharge has been used as a sputter source. Then it is often operated as an obstructed abnormal glow discharge and the required applied voltage is in the range 2–5 kV. Typically, the cathode target (the material to be deposited) is connected to a negative voltage supply (dc or rf) and the substrate holder faces the target. The relatively high operating pressure, in the range from 2 to 4 Pa, high applied voltages, and the necessity to have a conductive target limit the application of dc glow discharge as a sputter source. In order to lower the discharge voltage and expand the operation pressure range, the lifetime of the electrons in target vicinity is increased through applying magnetic field, by adding permanent magnets behind the cathode target. This arrangement is coined the magnetron sputtering discharge. The various configurations of the magnetron sputtering discharge and its applications are described. Furthermore, the use of dc discharges for chemical analysis, the

  18. Microscale Digital Vacuum Electronic Gates

    Science.gov (United States)

    Manohara, Harish (Inventor); Mojarradi, Mohammed M. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement microscale digital vacuum electronic gates. In one embodiment, a microscale digital vacuum electronic gate includes: a microscale field emitter that can emit electrons and that is a microscale cathode; and a microscale anode; where the microscale field emitter and the microscale anode are disposed within at least a partial vacuum; where the microscale field emitter and the microscale anode are separated by a gap; and where the potential difference between the microscale field emitter and the microscale anode is controllable such that the flow of electrons between the microscale field emitter and the microscale anode is thereby controllable; where when the microscale anode receives a flow of electrons, a first logic state is defined; and where when the microscale anode does not receive a flow of electrons, a second logic state is defined.

  19. Modeling methodology of the conducted emission of a DC-DC converter board

    OpenAIRE

    Boyer, Alexandre; Gonzalez Sentis, Manuel; Ghfiri, Chaimae; Durier, André

    2017-01-01

    International audience; This paper proposes a methodology to model an electronic board according to a bottom-up approach. This method is applied to build the model of a synchronous buck DC-DC converter board for conducted emission prediction purpose. The different steps to select the model terminals and the construction of the component and PCB interconnect models are described.

  20. 76 FR 31462 - Airworthiness Directives; The Boeing Company Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10...

    Science.gov (United States)

    2011-06-01

    ... Model DC-10-10, DC- 10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F.... Applicability (c) This AD applies to all The Boeing Company Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10- 40, DC-10-40F, MD-10-10F, MD-10-30F, MD-11, and MD-11F airplanes...

  1. Laser wire emittance measurement line AT CLIC

    CERN Document Server

    Garcia, H; Blair, G A; Aumeyr, T; Schulte, D; Stulle, F

    2011-01-01

    A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical errors and of their impact on the accuracy of the emittance reconstruction are given. Laser wire systems suitable for CLIC and their main characteristics are discussed.

  2. Emittance growth due to Tevatron flying wires

    Energy Technology Data Exchange (ETDEWEB)

    Syphers, M; Eddy, Nathan

    2004-06-01

    During Tevatron injection, Flying Wires have been used to measure the transverse beam size after each transfer from the Main Injector in order to deduce the transverse emittances of the proton and antiproton beams. This amounts to 36 + 9 = 45 flies of each of 3 wire systems, with an individual wire passing through each beam bunch twice during a single ''fly''. below they estimate the emittance growth induced by the interaction of the wires with the particles during these measurements. Changes of emittance from Flying Wire measurements conducted during three recent stores are compared with the estimations.

  3. Vacuum electronics

    CERN Document Server

    Eichmeier, Joseph A

    2008-01-01

    Nineteen experts from the electronics industry, research institutes and universities have joined forces to prepare this book. ""Vacuum Electronics"" covers the electrophysical fundamentals, the present state of the art and applications, as well as the future prospects of microwave tubes and systems, optoelectronics vacuum devices, electron and ion beam devices, light and X-ray emitters, particle accelerators and vacuum interrupters. These topics are supplemented by useful information about the materials and technologies of vacuum electronics and vacuum technology.

  4. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  5. Emittance scans for CMS luminosity calibration in 2017

    CERN Document Server

    CMS Collaboration

    2018-01-01

    Emittance scans are short van der Meer type scans performed at the beginning and at the end of LHC fills. The beams are scanned against each other in X and Y planes in 7 displacement steps. These scans are used for LHC diagnostics and since 2017 for a cross check of the CMS luminosity calibration. An XY pair of scans takes around 3 minutes. The BRIL project provides to LHC three independent online luminosity measurement from the Pixel Luminosity Telescope (PLT), the Fast Beam Condition Monitor (BCM1F) and the Forward calorimeter (HF). The excellent performance of the BRIL detector front-ends, fast back-end electronics and CMS XDAQ based data processing and publication allow the use of emittance scans for linearity and stability studies of the luminometers. Emittance scans became a powerful tool and dramatically improved the understanding of the luminosity measurement during the year. Since each luminometer is independently calibrated in every scan the measurements are independent and ratios of luminometers ca...

  6. Fowler Nordheim theory of carbon nanotube based field emitters

    Energy Technology Data Exchange (ETDEWEB)

    Parveen, Shama; Kumar, Avshish [Department of Physics, Jamia Millia Islamia (Central University), New Delhi (India); Husain, Samina [Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (Central University), New Delhi (India); Husain, Mushahid, E-mail: mush_reslab@rediffmail.com [Department of Physics, Jamia Millia Islamia (Central University), New Delhi (India)

    2017-01-15

    Field emission (FE) phenomena are generally explained in the frame-work of Fowler Nordheim (FN) theory which was given for flat metal surfaces. In this work, an effort has been made to present the field emission mechanism in carbon nanotubes (CNTs) which have tip type geometry at nanoscale. High aspect ratio of CNTs leads to large field enhancement factor and lower operating voltages because the electric field strength in the vicinity of the nanotubes tip can be enhanced by thousand times. The work function of nanostructure by using FN plot has been calculated with reverse engineering. With the help of modified FN equation, an important formula for effective emitting area (active area for emission of electrons) has been derived and employed to calculate the active emitting area for CNT field emitters. Therefore, it is of great interest to present a state of art study on the complete solution of FN equation for CNTs based field emitter displays. This manuscript will also provide a better understanding of calculation of different FE parameters of CNTs field emitters using FN equation.

  7. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    Science.gov (United States)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  8. Current-Fluctuation Mechanism of Field Emitters Using Metallic Single-Walled Carbon Nanotubes with High Crystallinity

    Directory of Open Access Journals (Sweden)

    Norihiro Shimoi

    2017-12-01

    Full Text Available Field emitters can be used as a cathode electrode in a cathodoluminescence device, and single-walled carbon nanotubes (SWCNTs that are synthesized by arc discharge are expected to exhibit good field emission (FE properties. However, a cathodoluminescence device that uses field emitters radiates rays whose intensity considerably fluctuates at a low frequency, and the radiant fluctuation is caused by FE current fluctuation. To solve this problem, is very important to obtain a stable output for field emitters in a cathodoluminescence device. The authors consider that the electron-emission fluctuation is caused by Fowler–Nordheim electron tunneling and that the electrons in the Fowler–Nordheim regime pass through an inelastic potential barrier. We attempted to develop a theoretical model to analyze the power spectrum of the FE current fluctuation using metallic SWCNTs as field emitters, owing to their electrical conductivity by determining their FE properties. Field emitters that use metallic SWCNTs with high crystallinity were successfully developed to achieve a fluctuating FE current from field emitters at a low frequency by employing inelastic electron tunneling. This paper is the first report of the successful development of an inelastic-electron-tunneling model with a Wentzel–Kramers–Brillouin approximation for metallic SWCNTs based on the evaluation of FE properties.

  9. Multinozzle emitter arrays for ultrahigh-throughput nanoelectrospray mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Daojing; Mao, Pan; Wang, Hung-Ta; Yang, Peidong

    2017-10-17

    The present invention provides for a structure comprising a plurality of emitters, wherein a first nozzle of a first emitter and a second nozzle of a second emitter emit in two directions that are not or essentially not in the same direction; wherein the walls of the nozzles and the emitters form a monolithic whole. The present invention also provides for a structure comprising an emitter with a sharpened end from which the emitter emits; wherein the emitters forms a monolithic whole. The present invention also provides for a fully integrated separation of proteins and small molecules on a silicon chip before the electrospray mass spectrometry analysis.

  10. Alpha-emitters for medical therapy workshop

    Energy Technology Data Exchange (ETDEWEB)

    Feinendegen, L.E.; McClure, J.J.

    1996-12-31

    A workshop on ``Alpha-Emitters for Medical Therapy`` was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference.

  11. Sheppard-Taylor Isolated High Boost DC-DC Converter

    DEFF Research Database (Denmark)

    Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

    2017-01-01

    be implemented with fewer passive components. Soft-switching in semiconductors allows achieving high efficiency. In addition, the input side current is continuous. The operating principle and the design guidelines derived for the converter are presented. Theoretical results are supported with experimental......This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can...... results obtained using a 100 W prototype. The converter proposed can be used in photovoltaic module level power electronics applications, where a wide input voltage and load regulation range are highly demanded....

  12. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  13. DC-to-DC switching converter

    Science.gov (United States)

    Cuk, Slobodan M. (Inventor); Middlebrook, Robert D. (Inventor)

    1980-01-01

    A dc-to-dc converter having nonpulsating input and output current uses two inductances, one in series with the input source, the other in series with the output load. An electrical energy transferring device with storage, namely storage capacitance, is used with suitable switching means between the inductances to DC level conversion. For isolation between the source and load, the capacitance may be divided into two capacitors coupled by a transformer, and for reducing ripple, the inductances may be coupled. With proper design of the coupling between the inductances, the current ripple can be reduced to zero at either the input or the output, or the reduction achievable in that way may be divided between the input and output.

  14. Electronic media time and sedentary behaviors in children: Findings from the Built Environment and Active Play Study in the Washington DC area

    National Research Council Canada - National Science Library

    Roberts, Jennifer D; Rodkey, Lindsey; Ray, Rashawn; Knight, Brandon; Saelens, Brian E

    2017-01-01

    An objective of the Built Environment and Active Play (BEAP) Study was to examine whether home built environment, bedroom electronic presence, parental rules and demographics predicted children's sedentary behavior (SB...

  15. High-temperature plasmonic thermal emitter for thermophotovotaics

    DEFF Research Database (Denmark)

    Liu, Jingjing; Guler, Urcan; Li, Wei

    2014-01-01

    We use titanium nitride (TiN) to demonstrate an ultra-thin plasmonic thermal emitter operating at high temperatures (830 K). The spectrally selective emitter exhibits a large emittance at around 2.5 μm and below, and suppresses emission at longer wavelengths.......We use titanium nitride (TiN) to demonstrate an ultra-thin plasmonic thermal emitter operating at high temperatures (830 K). The spectrally selective emitter exhibits a large emittance at around 2.5 μm and below, and suppresses emission at longer wavelengths....

  16. Observation of emittance growth at KEK PS

    CERN Document Server

    Igarashi, S; Nakamura, E; Shimosaki, Y; Shirakata, M; Takayama, K; Toyama, T

    2003-01-01

    Emittance growth has been observed in the transverse direction at the injection period of the 12 GeV main ring of the KEK proton synchrotron. Measurement of the beam profiles using flying wires has revealed a characteristic temporal change of the beam profile within a few milliseconds after injection. Horizontal emittance growth was observed when the horizontal tune was close to the integer. The effect was more enhanced for higher beam intensity and could not be explained with the injection mismatch. Resonance created by the space charge field was the cause of the emittance growth. A multiparticle tracking simulation program, ACCSIM, taking account of space charge effects has qualitatively reproduced the beam profiles.

  17. A theoretical model for effect of electron radial diffusion on breakdown characteristics of DC Townsend discharge in uniform axial magnetic field

    Science.gov (United States)

    Noori, H.; Rahmanipour, R.; Ranjbar, A. H.

    2017-12-01

    The breakdown characteristics of gas discharge between two parallel disks including the electron losses in the discharge process due to radial diffusion have been discussed. A theoretical approach was established to determine the fraction of electrons lost from the discharge cell due to radial diffusion. Then, the dependency of the effective secondary electron emission coefficient on the inter-electrode spacing d, the electrode radius R, and the axial magnetic field B was studied. A particle-in-cell, Monte Carlo collision technique was employed to obtain the values of electron loss coefficient, δ, for d from 1 cm to 10 cm, R between 1 and 10 cm, B up to 300 G, and the gas pressures from 50 mTorr to 250 mTorr. The results show that the loss of the electrons increases exponentially with the distance d, while it decreases by increasing R. Based on the model, the applied magnetic field lowers the Paschen curve that is in agreement with the experimental data.

  18. Current Injection Pumping of Organic Light Emitters

    Science.gov (United States)

    1989-09-28

    MOT-OOO1AF I Current Injection Pumping of Organic Light Emitters Prepared by DI Jeffrey C. Buchholz E L ri: 8 James P. Stec OCT C "t989 Mary C...Schutte Micro -Optics Technologies, Inc. 8608 University Green #5 Middleton, WI 53562 28 September 1989 D,:?UqflON SA2". N’.’ _ Disuibunon Uanu-ted Contract...Title Report Date Current Injection Pumping of Organic Light Emitters 28 September 1989 Authors Jeffrey C. Buchholz, James P. Stec, Mary C. Schutte

  19. Quadrupole Transfer Function for Emittance Measurement

    CERN Document Server

    Cameron, Peter; Jansson, Andreas; Tan, Cheng-Yang

    2008-01-01

    Historically the use of the quadrupole moment measurement has been impeded by the requirement for large dynamic range, as well as measurement sensitivity to beam position. We investigate the use of the transfer function technique [1-3] in combination with the sensitivity and 160dB revolution line rejection of the direct diode detection analog front end [4] to open the possibility of an emittance diagnostic that may be implemented without operational complication, quasi- parasitic to the operation of existing tune measurement systems. Such a diagnostic would be particularly useful as an emittance monitor during acceleration ramp development in machines like RHIC and the LHC.

  20. Coupling single emitters to quantum plasmonic circuits

    Directory of Open Access Journals (Sweden)

    Huck Alexander

    2016-09-01

    Full Text Available In recent years, the controlled coupling of single-photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic nonlinearity on a nanoscaled platform. In this article, we will review the recent progress on coupling single emitters to nanowires towards the construction of a new platform for strong light-matter interaction. The control over such a platform might open new doors for quantum information processing and quantum sensing at the nanoscale and for the study of fundamental physics in the ultrastrong coupling regime.

  1. 75 FR 38943 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

    Science.gov (United States)

    2010-07-07

    ... Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10-40, and DC-10-40F Airplanes AGENCY... propose to adopt a new airworthiness directive (AD) for certain Model DC-10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10- 40, and DC-10-40F airplanes. This proposed AD would require installing a support...

  2. 75 FR 63040 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

    Science.gov (United States)

    2010-10-14

    ... Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10-40, and DC-10-40F Airplanes AGENCY... (b) None. Applicability (c) This AD applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10-40, and DC-10- 40F airplanes, certificated in any category...

  3. Optimizations of transverse projected emittance at the photo-injector test facility at DESY, location Zeuthen

    Energy Technology Data Exchange (ETDEWEB)

    Rimjaem, S., E-mail: r.sakhorn@gmail.com [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738 Zeuthen (Germany); Stephan, F.; Krasilnikov, M. [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738 Zeuthen (Germany); Ackermann, W. [Technische Universtaet Darmstadt, Schossgartenstrasse 8, 64289 Darmstadt (Germany); Asova, G.; Baehr, J. [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738 Zeuthen (Germany); Gjonaj, E. [Technische Universtaet Darmstadt, Schossgartenstrasse 8, 64289 Darmstadt (Germany); Grabosch, H.J.; Hakobyan, L.; Haenel, M.; Ivanisenko, Y.; Khojoyan, M.; Klemz, G. [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738 Zeuthen (Germany); Lederer, S. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany); Mahgoub, M. [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738 Zeuthen (Germany); Michelato, P.; Monaco, L. [Istituto Nazionale di Fisica Nucleare, Sezione di Milano - LASA, Via F.lli Cervi 201, 20090 Segrate Milano (Italy); Nozdrin, M.; O' Shea, B.; Otevrel, M. [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738 Zeuthen (Germany); and others

    2012-04-11

    High brightness electron sources for linac based short-wavelength free-electron lasers are developed and optimized for small transverse projected emittance at the photo-injector test facility at DESY, location Zeuthen (PITZ). A major part of the measurement program at PITZ is dedicated to transverse phase space optimization in order to fulfill the requirements of the European X-ray free-electron laser (European XFEL). A laser-driven RF-gun, treated with a dry-ice sublimation-impulse cleaning technique, a new photocathode laser system allowing short rise and fall times of the flat-top temporal distribution as well as several new diagnostic components have been installed at PITZ in 2008. The electrons generated via the photo-effect at a cesium telluride (Cs{sub 2}Te) cathode are accelerated by a 1.6 cell L-band RF-gun cavity with a maximum accelerating gradient at the cathode of about 60 MV/m. The transverse projected emittance is measured using a single slit scan technique. In the 2008-2009 run period, a detailed characterization of the projected transverse emittance was performed at different operating conditions. Optimizations and measurement results as well as simulation predictions of the transverse projected emittance for bunch charges of 1, 0.5, 0.25 and 0.1 nC are presented and discussed in this paper. The geometric mean of the normalized projected rms emittance in both transverse directions for an electron bunch charge of 1 nC was measured to be 0.89{+-}0.01 mm mrad for a 100% rms phase-space distribution.

  4. Optimizations of transverse projected emittance at the photo-injector test facility at DESY, location Zeuthen

    Science.gov (United States)

    Rimjaem, S.; Stephan, F.; Krasilnikov, M.; Ackermann, W.; Asova, G.; Bähr, J.; Gjonaj, E.; Grabosch, H. J.; Hakobyan, L.; Hänel, M.; Ivanisenko, Y.; Khojoyan, M.; Klemz, G.; Lederer, S.; Mahgoub, M.; Michelato, P.; Monaco, L.; Nozdrin, M.; O'Shea, B.; Otevrel, M.; Petrosyan, B.; Richter, D.; Rönsch-Schulenburg, J.; Sertore, D.; Schreiber, S.; Schnepp, S.; Shapovalov, A.; Spesyvtsev, R.; Staykov, L.; Vashchenko, G.; Weiland, T.; Will, I.

    2012-04-01

    High brightness electron sources for linac based short-wavelength free-electron lasers are developed and optimized for small transverse projected emittance at the photo-injector test facility at DESY, location Zeuthen (PITZ). A major part of the measurement program at PITZ is dedicated to transverse phase space optimization in order to fulfill the requirements of the European X-ray free-electron laser (European XFEL). A laser-driven RF-gun, treated with a dry-ice sublimation-impulse cleaning technique, a new photocathode laser system allowing short rise and fall times of the flat-top temporal distribution as well as several new diagnostic components have been installed at PITZ in 2008. The electrons generated via the photo-effect at a cesium telluride (Cs2Te) cathode are accelerated by a 1.6 cell L-band RF-gun cavity with a maximum accelerating gradient at the cathode of about 60 MV/m. The transverse projected emittance is measured using a single slit scan technique. In the 2008-2009 run period, a detailed characterization of the projected transverse emittance was performed at different operating conditions. Optimizations and measurement results as well as simulation predictions of the transverse projected emittance for bunch charges of 1, 0.5, 0.25 and 0.1 nC are presented and discussed in this paper. The geometric mean of the normalized projected rms emittance in both transverse directions for an electron bunch charge of 1 nC was measured to be 0.89±0.01 mm mrad for a 100% rms phase-space distribution.

  5. Low Emittance Growth in a LEBT with Un-Neutralized Section

    Energy Technology Data Exchange (ETDEWEB)

    Prost, Lionel [Fermilab; Carneiro, Jean-Paul [Fermilab; Shemyakin, Alexander [Fermilab

    2016-06-01

    In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam's own space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT that contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report discusses the experimental realization of such a scheme at Fermilab's PXIE, where low beam emittance dilution was demonstrated

  6. Optimization of multi-tip-shaped field emitters with bilayer protective coatings

    Science.gov (United States)

    Sominskii, G. G.; Taradaev, E. P.

    2017-06-01

    The calculations needed to optimize the ordered multi-tip-shaped silicon field emitters with the two-layer protective metal-fullerene coatings intended for use in high voltage electronic devices operating in technical vacuum have been performed. The calculations are fulfilled using the COMSOL program. The influence of the morphology of the surface on the emission characteristics of the emitters is determined, including the needles height and radius of their vertices, and also the distance between needles. It has been shown that the emitters with an area of 0.2 cm2, operating under the conditions of partial mutual screening, can provide currents of several hundred milliamps for fairly high voltages.

  7. Low-emittance tuning of storage rings using normal mode beam position monitor calibration

    Directory of Open Access Journals (Sweden)

    A. Wolski

    2011-07-01

    Full Text Available We describe a new technique for low-emittance tuning of electron and positron storage rings. This technique is based on calibration of the beam position monitors (BPMs using excitation of the normal modes of the beam motion, and has benefits over conventional methods. It is relatively fast and straightforward to apply, it can be as easily applied to a large ring as to a small ring, and the tuning for low emittance becomes completely insensitive to BPM gain and alignment errors that can be difficult to determine accurately. We discuss the theory behind the technique, present some simulation results illustrating that it is highly effective and robust for low-emittance tuning, and describe the results of some initial experimental tests on the CesrTA storage ring.

  8. Current-horn suppression for reduced coherent-synchrotron-radiation-induced emittance growth in strong bunch compression

    Science.gov (United States)

    Charles, T. K.; Paganin, D. M.; Latina, A.; Boland, M. J.; Dowd, R. T.

    2017-03-01

    Control of coherent synchrotron radiation (CSR)-induced emittance growth is essential in linear accelerators designed to deliver very high brightness electron beams. Extreme current values at the head and tail of the electron bunch, resulting from strong bunch compression, are responsible for large CSR production leading to significant transverse projected emittance growth. The Linac Coherent Light Source (LCLS) truncates the head and tail current spikes which greatly improves free electron laser (FEL) performance. Here we consider the underlying dynamics that lead to formation of current spikes (also referred to as current horns), which has been identified as caustics forming in electron trajectories. We present a method to analytically determine conditions required to avoid the caustic formation and therefore prevent the current spikes from forming. These required conditions can be easily met, without increasing the transverse slice emittance, through inclusion of an octupole magnet in the middle of a bunch compressor.

  9. The generation and acceleration of low emittance flat beams for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Raubenheimer, T.O.

    1991-11-01

    Many future linear collider designs call for electron and positron beams with normalized rms horizontal and vertical emittances of {gamma}{epsilon}{sub x} = 3{times}10{sup {minus}6} m-rad and {gamma}{epsilon}{sub y} = 3{times}10{sup {minus}8} m-rad; these are a factor of 10 to 100 below those observed in the Stanford Linear Collider. In this dissertation, we examine the feasibility of achieving beams with these very small vertical emittances. We examine the limitations encountered during both the generation and the subsequent acceleration of such low emittance beams. We consider collective limitations, such as wakefields, space charge effects, scattering processes, and ion trapping; and also how intensity limitations, such as anomalous dispersion, betatron coupling, and pulse-to-pulse beam jitter. In general, the minimum emittance in both the generation and the acceleration stages is limited by the transverse misalignments of the accelerator components. We describe a few techniques of correcting the effect of these errors, thereby easing the alignment tolerances by over an order of magnitude. Finally, we also calculate fundamental'' limitations on the minimum vertical emittance; these do not constrain the current designs but may prove important in the future.

  10. The generation and acceleration of low emittance flat beams for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Raubenheimer, Tor O. [Stanford Univ., CA (United States)

    1991-11-01

    Many future linear collider designs call for electron and positron beams with normalized rms horizontal and vertical emittances of γϵx = 3x10-6 m-rad and γϵy = 3x10-8 m-rad; these are a factor of 10 to 100 below those observed in the Stanford Linear Collider. In this dissertation, we examine the feasibility of achieving beams with these very small vertical emittances. We examine the limitations encountered during both the generation and the subsequent acceleration of such low emittance beams. We consider collective limitations, such as wakefields, space charge effects, scattering processes, and ion trapping; and also how intensity limitations, such as anomalous dispersion, betatron coupling, and pulse-to-pulse beam jitter. In general, the minimum emittance in both the generation and the acceleration stages is limited by the transverse misalignments of the accelerator components. We describe a few techniques of correcting the effect of these errors, thereby easing the alignment tolerances by over an order of magnitude. Finally, we also calculate ``fundamental`` limitations on the minimum vertical emittance; these do not constrain the current designs but may prove important in the future.

  11. Shortwave-infrared (SWIR emitters for biological imaging: a review of challenges and opportunities

    Directory of Open Access Journals (Sweden)

    Thimsen Elijah

    2017-06-01

    Full Text Available Shortwave infrared radiation (SWIR is the portion of the electromagnetic spectrum from approximately 900 nm to 2500 nm. Recent advances in imaging systems have expanded the application of SWIR emitters from traditional fields in materials science to biomedical imaging, and the new detectors in SWIR opened an opportunity of deep tissue imaging. Achieving deep photon penetration while maintaining high resolution is one of the main objectives and challenges in bioimaging used for the investigation of diverse processes in living organisms. The application of SWIR emitters in biological settings is, however, hampered by low quantum efficiency. So far, photoluminescent properties in the SWIR region have not been improved by extending concepts that have been developed for the visible (400–650 nm and near-infrared (NIR, 700–900 nm wavelengths, which indicates that the governing behavior is fundamentally different in the SWIR. The focus of this minireview is to examine the mechanisms behind the low efficiency of SWIR emitters as well as to highlight the progress in their design for biological applications. Several common mechanisms will be considered in this review: (a the effect of the energy gap between the excited and ground state on the quantum efficiency, (b the coupling of the excited electronic states in SWIR emitters to vibrational states in the surrounding matrix, and (c the role of environment in quenching the excited states. General strategies to improve the quantum yields for a diverse type of SWIR emitters will be also presented.

  12. Shortwave-infrared (SWIR) emitters for biological imaging: a review of challenges and opportunities

    Science.gov (United States)

    Thimsen, Elijah; Sadtler, Bryce; Berezin, Mikhail Y.

    2017-06-01

    Shortwave infrared radiation (SWIR) is the portion of the electromagnetic spectrum from approximately 900 nm to 2500 nm. Recent advances in imaging systems have expanded the application of SWIR emitters from traditional fields in materials science to biomedical imaging, and the new detectors in SWIR opened an opportunity of deep tissue imaging. Achieving deep photon penetration while maintaining high resolution is one of the main objectives and challenges in bioimaging used for the investigation of diverse processes in living organisms. The application of SWIR emitters in biological settings is, however, hampered by low quantum efficiency. So far, photoluminescent properties in the SWIR region have not been improved by extending concepts that have been developed for the visible (400-650 nm) and near-infrared (NIR, 700-900 nm) wavelengths, which indicates that the governing behavior is fundamentally different in the SWIR. The focus of this minireview is to examine the mechanisms behind the low efficiency of SWIR emitters as well as to highlight the progress in their design for biological applications. Several common mechanisms will be considered in this review: (a) the effect of the energy gap between the excited and ground state on the quantum efficiency, (b) the coupling of the excited electronic states in SWIR emitters to vibrational states in the surrounding matrix, and (c) the role of environment in quenching the excited states. General strategies to improve the quantum yields for a diverse type of SWIR emitters will be also presented.

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

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI, I.

    2005-09-18

    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&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.

  14. Analysis of DC/DC Converter Efficiency for Energy Storage System Based on Bidirectional Fuel Cells

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    Renewable energy sources are fluctuating depending on the availability of the energy source. For this reason, energy storage is becoming more important and bidirectional fuel cells represent an attractive technology. Fuel cells require highcurrent low-voltage dc-dc or dc-ac converters as power...... interface to the grid. In power electronics, the converter efficiency is characterized at fixed operating voltage for various output power. This type of characterization is not suitable for fuel cells, since as the power from the fuel cell increases, the cell voltage decreases. This paper analyses how...

  15. Longitudinal emittance measurements at REX-ISOLDE

    CERN Document Server

    Fraser, M A; Jones, R.M.; Jones, R M; Pasini, M; Posocco, P A; Voulot, D; Wenander, F

    2012-01-01

    We report on measurements of the longitudinal emittance at the Radioactive ion beam EXperiment (REX) at ISOLDE, CERN. The rms longitudinal emittance was measured as 0.34 ± 0.08 π ns keV/u at the output of the RFQ and as 0.36 ± 0.04π ns keV/u in front of the third 7-gap split-ring resonator (7G3) using the three-gradient technique; systematic errors are not included but are estimated at approximately 10%. The 86% emittance was measured a factor of approximately 4.4 times larger than the rms emittance at 1.48 ± 0.2 and 1.55 ± 0.12π ns keV/u at the RFQ and 7G3, respectively. The REX switchyard magnet was used as a spectrometer to analyse the energy spread of the beam as it was manipulated by varying the voltage of the rebuncher (ReB) and 7G3 cavities operating at non-accelerating phases. The transfer matrix for a multi-gap bunching cavity is derived and suitably truncated to allow for the accurate reconstruction of the beam parameters from measurement. The technique for measuring the energy spread was rig...

  16. Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

    CSIR Research Space (South Africa)

    Grobler, Inus

    2013-09-01

    Full Text Available Extended Conducted Electromagnetic Interference in Densely Packed DC- DC Converter I Grobler1 and MN Gitau2 Department of Electrical, Electronic and Computer Engineering, University of Pretoria, South Africa. igrobler@csir.co.za1, mgitau.... This will improve the overall design efficiency and shorten the crucial time to market period [1]. It is of utmost importance to try and model the electromagnetic compatibility concurrent with the power processor design stage. The marketplace is in need...

  17. Facet engineering of high power single emitters

    Science.gov (United States)

    Yanson, Dan; Levi, Moshe; Shamay, Moshe; Tesler, Renana; Rappaport, Noam; Don, Yaroslav; Karni, Yoram; Schnitzer, Itzhak; Sicron, Noam; Shusterman, Sergey

    2011-03-01

    The ever increasing demand for high-power, high-reliability operation of single emitters at 9xx nm wavelengths requires the development of laser diodes with improved facet regions immune to both catastrophic and wear-out failure modes. In our study, we have evaluated several laser facet definition technologies in application to 90 micron aperture single emitters in asymmetric design (In)GaAs/AlGaAs based material emitting at 915, 925 and 980nm. A common epitaxy and emitter design makes for a straightforward comparison of the facet technologies investigated. Our study corroborates a clear trend of increasing difficulty in obtaining reliable laser operation from 980nm down to 915nm. At 980nm, one can employ dielectric facet passivation with a pre-clean cycle delivering a device lifetime in excess of 3,000 hours at increasing current steps. At 925nm, quantum-well intermixing can be used to define non-absorbing mirrors giving good device reliability, albeit with a large efficiency penalty. Vacuum cleaved emitters have delivered excellent reliability at 915nm, and can be expected to perform just as well at 925 and 980nm. Epitaxial regrowth of laser facets is under development and has yet to demonstrate an appreciable reliability improvement. Only a weak correlation between start-of-life catastrophic optical mirror damage (COMD) levels and reliability was established. The optimized facet design has delivered maximum powers in excess of 19 MW/sq.cm (rollover limited) and product-grade 980nm single emitters with a slope efficiency of >1 W/A and a peak efficiency of >60%. The devices have accumulated over 1,500 hours of CW operation at 11W. A fiber-coupled device emits 10W ex-fiber with 47% efficiency.

  18. Longitudinal emittance reduction in LEIR of ion beams for LHC

    CERN Document Server

    Angoletta, M E; Findlay, A; Hancock, S; Manglunki, D

    2014-01-01

    For the 2013 LHC ion run the anticipated request for batches from the PS Complex comprising four ion bunches spaced by 100 ns was changed to batches of two bunches spaced by 200 ns. This modified demand was met by suppressing a splitting step in the PS machine, but with the consequence of halving the longitudinal emittance required from LEIR. Thus NOMINAL Pb54+ beams from LEIR had to be delivered inside ~9 eVs to provide sufficient blow-up margin in the PS. Machine Development (MD) sessions were carried out in LEIR to investigate methods to satisfy these stricter requirements. Two main ingredients were found to reduce longitudinal emittance. The first and most important was to adjust carefully the frequency offset at capture in order to align the RF with the position where the beam is deposited by the electron cooling system prior to acceleration. The second ingredient was to reduce the final bucket area in order to reduce any residual filamentation during capture. This note documents the results obtaine...

  19. Discrete space charge affected field emission: Flat and hemisphere emitters

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Kevin L., E-mail: kevin.jensen@nrl.navy.mil [Code 6854, Naval Research Laboratory, Washington, DC 20375 (United States); Shiffler, Donald A.; Tang, Wilkin [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States); Rittersdorf, Ian M. [Code 6770, Naval Research Laboratory, Washington, DC 20375 (United States); Lebowitz, Joel L. [Department of Mathematics and Department of Physics, Rutgers University, Piscataway, New Jersey 08854-8019 (United States); Harris, John R. [U.S. Navy Reserve, New Orleans, Louisiana 70143 (United States); Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Petillo, John J. [Leidos, Billerica, Massachusetts 01821 (United States); Luginsland, John W. [Physics and Electronics Directorate, AFOSR, Arlington, Virginia 22203 (United States)

    2015-05-21

    Models of space-charge affected thermal-field emission from protrusions, able to incorporate the effects of both surface roughness and elongated field emitter structures in beam optics codes, are desirable but difficult. The models proposed here treat the meso-scale diode region separate from the micro-scale regions characteristic of the emission sites. The consequences of discrete emission events are given for both one-dimensional (sheets of charge) and three dimensional (rings of charge) models: in the former, results converge to steady state conditions found by theory (e.g., Rokhlenko et al. [J. Appl. Phys. 107, 014904 (2010)]) but show oscillatory structure as they do. Surface roughness or geometric features are handled using a ring of charge model, from which the image charges are found and used to modify the apex field and emitted current. The roughness model is shown to have additional constraints related to the discrete nature of electron charge. The ability of a unit cell model to treat field emitter structures and incorporate surface roughness effects inside a beam optics code is assessed.

  20. Guest Editorial Special Issue on Structured DC Microgrids

    DEFF Research Database (Denmark)

    Guerrero, Josep M.; Tan, Don F. D.

    2017-01-01

    With the development of dc coupled devices, such as photovoltaic generations, batteries, supercapacitors, LEDs, computers, and electronics equipment, low-voltage dc distribution networks, structured dc microgrids are emerging as a natural platform to integrate renewable energy sources. However......, there are a number of technical challenges: lack of standardized equipment, inadequate stability, and versatile control design. In the past, the interest of power electronics community was moving from a single power electronics converter to multiple distributed systems that encompass a number of converters connected...... in either series/parallel, forming a number of dc busses with different voltage levels. Recently, with the advance of new dc power technologies, several ongoing standards, alliances, and initiatives are bringing the possibility of developing future homes, offices, buildings, campuses, datacenters, ships...

  1. Three new DC-to-DC Single-Switch Converters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2017-06-01

    Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.

  2. Study of Thermal-Field Emission Properties and Investigation of Temperature dependent Noise in the Emission Current form vertical Carbon nanotube emitters

    KAUST Repository

    Kolekar, Sadhu

    2017-05-05

    We have investigated temperature dependent field electron emission characteristics of vertical carbon nanotubes (CNTs). The generalized expression for electron emission from well defined cathode surface is given by Millikan and Lauritsen [1] for the combination of temperature and electric field effect. The same expression has been used to explain the electron emission characteristics from vertical CNT emitters. Furthermore, this has been applied to explain the electron emission for different temperatures ranging from room temperature to 1500 K. The real-time field electron emission images at room temperature and 1500 K are recorded by using Charge Coupled Device (CCD), in order to understand the effect of temperature on electron emission spots in image morphology (as indicated by ring like structures) and electron emission spot intensity of the emitters. Moreover, the field electron emission images can be used to calculate the total number of emitters per cm2 for electron emission. The calculated number of emitters per cm2 is 4.5x107 and, the actual number emitters per cm2 present for electron emission calculated from Atomic Force Microscopy (AFM) data is 1.2x1012. The measured Current-Voltage (I-V) characteristics obey the Folwer-Nordheim (F-N) type behavior. The fluctuations in the emission current are recorded at different temperatures and, temperature dependence of power spectral density obeys power law relation s(f)=I2/f2 with that of emission current and frequency.

  3. Design and Development of Emittance Measurement Device by Using the Pepper-pot Technique

    Science.gov (United States)

    Pakluea, S.; Rimjaem, S.

    2017-09-01

    Transverse emittance of a charged particle beam is one of the most important properties that reveals the quality of the beam. It is related to charge density, transvers size and angular displacement of the beam in transverse phase space. There are several techniques to measure the transverse emittance value. One of practical methods is the pepper-pot technique, which can measure both horizontal and vertical emittance value in a single measurement. This research concentrates on development of a pepper-pot device to measure the transverse emittance of electron beam produced from an accelerator injector system, which consists of a thermionic cathode RF electron gun and an alpha magnet, at the Plasma and Beam Physics Research Facility, Chiang Mai University. Simulation of beam dynamics was conducted with programs PARMELA, ELEGANT and self-developed codes using C and MATLAB. The geometry, dimensions and location of the pepper-pot as well as its corresponding screen station position were included in the simulation. The result from this study will be used to design and develop a practical pepper-pot experimental station.

  4. Three new DC-to-DC Single-Switch Converters

    OpenAIRE

    Barry W. Williams; Mona Fouad Moussa

    2017-01-01

    This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations ...

  5. Reappraisal of solid selective emitters. [for thermovoltaic energy conversion

    Science.gov (United States)

    Chubb, Donald L.

    1990-01-01

    New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus, low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied, Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

  6. DEVELOPMENT OF EMITTANCE ANALYSIS SOFTWARE FOR ION BEAM CHARACTERIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, M. J.; Liu, Y.

    2007-01-01

    Transverse beam emittance is a crucial property of charged particle beams that describes their angular and spatial spread. It is a fi gure of merit frequently used to determine the quality of ion beams, the compatibility of an ion beam with a given beam transport system, and the ability to suppress neighboring isotopes at on-line mass separator facilities. Generally a high quality beam is characterized by a small emittance. In order to determine and improve the quality of ion beams used at the Holifi eld Radioactive Ion beam Facility (HRIBF) for nuclear physics and nuclear astrophysics research, the emittances of the ion beams are measured at the off-line Ion Source Test Facilities. In this project, emittance analysis software was developed to perform various data processing tasks for noise reduction, to evaluate root-mean-square emittance, Twiss parameters, and area emittance of different beam fractions. The software also provides 2D and 3D graphical views of the emittance data, beam profi les, emittance contours, and RMS. Noise exclusion is essential for accurate determination of beam emittance values. A Self-Consistent, Unbiased Elliptical Exclusion (SCUBEEx) method is employed. Numerical data analysis techniques such as interpolation and nonlinear fi tting are also incorporated into the software. The software will provide a simplifi ed, fast tool for comprehensive emittance analysis. The main functions of the software package have been completed. In preliminary tests with experimental emittance data, the analysis results using the software were shown to be accurate.

  7. Efficiency Analyses of a DC Residential Power Distribution System for the Modern Home

    Directory of Open Access Journals (Sweden)

    GELANI, H. E.

    2015-02-01

    Full Text Available The electric power system started as DC back in the nineteenth century. However, the DC paradigm was soon ousted by AC due to inability of DC to change its voltage level. Now, after many years, with the development of power electronic converters capable of stepping-up and down DC voltage and converting it to-and-from AC, DC appears to be challenging AC and attempting a comeback. We now have DC power generation by solar cells, fuel cells and wind farms, DC power transmission in the form of HVDC (High Voltage DC transmission, DC power utilization by various modern electronic loads and DC power distribution that maybe regarded as still in research phase. This paper is an attempt to investigate feasibility of DC in the distribution portion of electrical power system. Specifically, the efficiency of a DC distribution system for residential localities is determined while keeping in view the concept of daily load variation. The aim is to bring out a more practical value of system efficiency as the efficiencies of DC/DC converters making up the system vary with load variation. This paper presents the modeling and simulation of a DC distribution system and efficiency results for various scenarios are presented.

  8. Low emittance coatings and the thermal performance of vacuum glazing

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yueping; Hyde, Trevor J.; Zhao, Junfu; Wang, Jinlei; Huang, Ye [Centre for Sustainable Technologies, School of the Built Environment, University of Ulster, Newtownabbey, BT37 0QB, N. Ireland (United Kingdom); Eames, Philip C. [School of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Norton, Brian [Dublin Institute of Technology, Aungier Street, Dublin 2 (Ireland)

    2007-01-15

    The thermal performances of vacuum glazings employing coatings with emittance between 0.02 and 0.16 were simulated using a three-dimensional finite volume model. Physical samples of vacuum glazings with hard and soft coatings with emittance of 0.04, 0.12 and 0.16 were fabricated and their thermal performance characterised experimentally using a guarded hot box calorimeter. Good agreement was found between experimental and theoretical thermal performances for both a vacuum glazing with a soft coating (emittance 0.04) and those with hard coatings (emittance 0.12 and 0.16). Simulations showed that for a low value of emittance (e.g. 0.02), the use of two low-emittance coatings gives limited improvement in thermal performance of the glazing system. The use of a single high performance low-emittance coating in a vacuum glazing has been shown to provide excellent performance. (author)

  9. Modeling quantum yield, emittance, and surface roughness effects from metallic photocathodes

    Science.gov (United States)

    Dimitrov, D. A.; Bell, G. I.; Smedley, J.; Ben-Zvi, I.; Feng, J.; Karkare, S.; Padmore, H. A.

    2017-10-01

    Detailed measurements of momentum distributions of emitted electrons have allowed the investigation of the thermal limit of the transverse emittance from metal photocathodes. Furthermore, recent developments in material design and growth have resulted in photocathodes that can deliver high quantum efficiency and are sufficiently robust to use in high electric field gradient photoinjectors and free electron lasers. The growth process usually produces photoemissive material layers with rough surface profiles that lead to transverse accelerating fields and possible work function variations, resulting in emittance growth. To better understand the effects of temperature, density of states, and surface roughness on the properties of emitted electrons, we have developed realistic three-dimensional models for photocathode materials with grated surface structures. They include general modeling of electron excitation due to photon absorption, charge transport, and emission from flat and rough metallic surfaces. The models also include image charge and field enhancement effects. We report results from simulations with flat and rough surfaces to investigate how electron scattering, controlled roughness, work function variation, and field enhancement affect emission properties. Comparison of simulation results with measurements of the quantum yield and transverse emittance from flat Sb emission surfaces shows the importance of including efficient modeling of photon absorption, temperature effects, and the material density of states to achieve agreement with the experimental data.

  10. The gas phase emitter effect of lanthanum within ceramic metal halide lamps and its dependence on the La vapor pressure and operating frequency

    Science.gov (United States)

    Ruhrmann, C.; Hoebing, T.; Bergner, A.; Groeger, S.; Denissen, C.; Suijker, J.; Awakowicz, P.; Mentel, J.

    2015-08-01

    The gas phase emitter effect increases the lamp lifetime by lowering the work function and, with it, the temperature of the tungsten electrodes of metal halide lamps especially for lamps in ceramic vessels due to their high rare earth pressures. It is generated by a monolayer on the electrode surface of electropositive atoms of certain emitter elements, which are inserted into the lamp bulb by metal iodide salts. They are vaporized, dissociated, ionized, and deposited by an emitter ion current onto the electrode surface within the cathodic phase of lamp operation with a switched-dc or ac-current. The gas phase emitter effect of La and the influence of Na on the emitter effect of La are studied by spatially and phase-resolved pyrometric measurements of the electrode tip temperature, La atom, and ion densities by optical emission spectroscopy as well as optical broadband absorption spectroscopy and arc attachment images by short time photography. An addition of Na to the lamp filling increases the La vapor pressure within the lamp considerably, resulting in an improved gas phase emitter effect of La. Furthermore, the La vapor pressure is raised by a heating of the cold spot. In this way, conditions depending on the La vapor pressure and operating frequency are identified, at which the temperature of the electrodes becomes a minimum.

  11. The gas phase emitter effect of lanthanum within ceramic metal halide lamps and its dependence on the La vapor pressure and operating frequency

    Energy Technology Data Exchange (ETDEWEB)

    Ruhrmann, C.; Hoebing, T.; Bergner, A.; Groeger, S.; Awakowicz, P.; Mentel, J. [Electrical Engineering and Plasma Technology, Ruhr University Bochum, D-44780 Bochum (Germany); Denissen, C.; Suijker, J. [Philips Lighting, Category Professional Lamps, P.O. Box 80020, NL-5600JM Eindhoven (Netherlands)

    2015-08-07

    The gas phase emitter effect increases the lamp lifetime by lowering the work function and, with it, the temperature of the tungsten electrodes of metal halide lamps especially for lamps in ceramic vessels due to their high rare earth pressures. It is generated by a monolayer on the electrode surface of electropositive atoms of certain emitter elements, which are inserted into the lamp bulb by metal iodide salts. They are vaporized, dissociated, ionized, and deposited by an emitter ion current onto the electrode surface within the cathodic phase of lamp operation with a switched-dc or ac-current. The gas phase emitter effect of La and the influence of Na on the emitter effect of La are studied by spatially and phase-resolved pyrometric measurements of the electrode tip temperature, La atom, and ion densities by optical emission spectroscopy as well as optical broadband absorption spectroscopy and arc attachment images by short time photography. An addition of Na to the lamp filling increases the La vapor pressure within the lamp considerably, resulting in an improved gas phase emitter effect of La. Furthermore, the La vapor pressure is raised by a heating of the cold spot. In this way, conditions depending on the La vapor pressure and operating frequency are identified, at which the temperature of the electrodes becomes a minimum.

  12. Improvement of Control System Based on Labview for Beam Emittance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Il; Kim, Jae-Ha; Kwon, Hyeok-Jung; Kim, Han-Sung; Lee, Seok-Geun; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

    2016-10-15

    Some ion sources have been developing at KOMAC. It is important to measure the beam properties to characterize the ion sources such as beam emittance. An electric sweep scanner (ESS) was used to measure the beam distribution in phase space. For performance of ESS, it consists of control system based on NI PXI devices and GUI (graphic user interface) based on Labview. In this paper, a control system with algorism applied reliable sequence for data acquisition is presented. In a sequence with 1 Hz of repetition rate, in case of time 6 s and interval 0.2 V on panel, DC output voltage increases with interval of 0.2 V from -3.6 V to + 3.6 V every 6 seconds. Total period is 216 second. In this case, 6 files are saved in every step. But first one of 6 could not be used because of unreliable signal with variation of DC output voltage. The control system based on Labview was developed for beam emittance measurement. And it was improved by the modification of algorism and the use of external tools applied global variable. In Future, the control system will be used in other ion sources of KOMAC.

  13. 75 FR 68246 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-11-05

    ... Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F... to supersede an existing airworthiness directive (AD) that applies to all Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F, MD-10- 10F, MD-10-30F, MD-11...

  14. 75 FR 20790 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-04-21

    ... Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F... (AD) for certain Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC- 10A and KDC-10), DC-10-40, DC-10-40F, MD-10-10F, MD-10-30F, MD-11, and MD-11F airplanes. This proposed AD would require...

  15. 75 FR 23571 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-05-04

    ... Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F.... ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F, MD-10-10F, MD...

  16. 75 FR 60602 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-10-01

    ... Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F.... ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F, MD-10-10F, MD...

  17. Electron-Deficient Near-Infrared Pt(II) and Pd(II) Benzoporphyrins with Dual Phosphorescence and Unusually Efficient Thermally Activated Delayed Fluorescence: First Demonstration of Simultaneous Oxygen and Temperature Sensing with a Single Emitter.

    Science.gov (United States)

    Zach, Peter W; Freunberger, Stefan A; Klimant, Ingo; Borisov, Sergey M

    2017-11-01

    We report a family of Pt and Pd benzoporphyrin dyes with versatile photophysical properties and easy access from cheap and abundant chemicals. Attaching 4 or 8 alkylsulfone groups onto a meso-tetraphenyltetrabenzoporphyrin (TPTBP) macrocylcle renders the dyes highly soluble in organic solvents, photostable, and electron-deficient with the redox potential raised up to 0.65 V versus the parent porphyrin. The new dyes intensively absorb in the blue (Soret band, 440-480 nm) and in the red (Q-band, 620-650 nm) parts of the electromagnetic spectrum and show bright phosphorescence at room-temperature in the NIR with quantum yields up to 30% in solution. The small singlet-triplet energy gap yields unusually efficient thermally activated delayed fluorescence (TADF) at elevated temperatures in solution and in polymeric matrices with quantum yields as high as 27% at 120 °C, which is remarkable for benzoporphyrins. Apart from oxygen sensing, these properties enable unprecedented simultaneous, self-referenced oxygen and temperature sensing with a single indicator dye: whereas oxygen can be determined either via the decay time of phosphorescence or TADF, the temperature is accessed via the ratio of the two emissions. Moreover, the dyes are efficient sensitizers for triplet-triplet annihilation (TTA)-based upconversion making possible longer sensitization wavelength than the conventional benzoporphyrin complexes. The Pt-octa-sulfone dye also features interesting semireversible transformation in basic media, which generates new NIR absorbing species.

  18. Front contact solar cell with formed emitter

    Science.gov (United States)

    Cousins, Peter John [Menlo Park, CA

    2012-07-17

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  19. FIrpic: archetypal blue phosphorescent emitter for electroluminescence.

    Science.gov (United States)

    Baranoff, Etienne; Curchod, Basile F E

    2015-05-14

    FIrpic is the most investigated bis-cyclometallated iridium complex in particular in the context of organic light emitting diodes (OLEDs) because of its attractive sky-blue emission, high emission efficiency, and suitable energy levels. In this Perspective we review the synthesis, structural characterisations, and key properties of this emitter. We also survey the theoretical studies and summarise a series of selected monochromatic electroluminescent devices using FIrpic as the emitting dopant. Finally we highlight important shortcomings of FIrpic as an emitter for OLEDs. Despite the large body of work dedicated to this material, it is manifest that the understanding of photophysical and electrochemical processes are only broadly understood mainly because of the different environment in which these properties are measured, i.e., isolated molecules in solvent vs. device.

  20. Emittance growth in coast in the SPS

    CERN Document Server

    Alekou, A; Bartosik, H; Calaga, R

    2017-01-01

    The CERN SPS will be used as a test-bed for the LHCprototype crab-cavities, which will be installed and testedin the SPS in 2018. As the time available for experimen-tal beam dynamics studies with the crab cavities installedin the machine will be limited, a very good preparation isrequired in advance. One of the main concerns is the in-duced emittance growth, driven by phase jitter in the crabcavities. In this respect, several machine development (MD)studies were performed during the past years to quantifyand characterize the emittance evolution of proton beamsin coast in the SPS. In these proceedings, the experimentalobservations from past years are summarized and the MDstudies from 2016 are presented. Finally, a proposal for anexperimental program for 2017 is discussed.

  1. Computing Eigen-Emittances from Tracking Data

    Energy Technology Data Exchange (ETDEWEB)

    Alexahin, Y. [Fermilab

    2014-09-18

    In a strongly nonlinear system the particle distribution in the phase space may develop long tails which contribution to the covariance (sigma) matrix should be suppressed for a correct estimate of the beam emittance. A method is offered based on Gaussian approximation of the original particle distribution in the phase space (Klimontovich distribution) which leads to an equation for the sigma matrix which provides efficient suppression of the tails and cannot be obtained by introducing weights. This equation is easily solved by iterations in the multi-dimensional case. It is also shown how the eigen-emittances and coupled optics functions can be retrieved from the sigma matrix in a strongly coupled system. Finally, the developed algorithm is applied to 6D ionization cooling of muons in HFOFO channel.

  2. Emittance growths in resonance crossing at FFAGs

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab; Pang, X.; Wang, F.; Wang, X.; Lee, S.Y.; /Indiana U.

    2007-10-01

    Scaling laws of the emittance growth for a beam crossing the 6th-order systematic space-charge resonances and the random-octupole driven 4th-order resonance are obtained by numerical multi-particle simulations. These laws can be important in setting the minimum acceleration rate and maximum tolerable resonance strength for the design of non-scaling fixed-field alternating gradient accelerators.

  3. Measurement system for alpha emitters in solution

    Energy Technology Data Exchange (ETDEWEB)

    Robert, A. (CEA Centre d' Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Dept. de Genie Radioactif); Sella, C.; Heindl, R. (Centre National de la Recherche Scientifique, 92 - Meudon-Bellevue (France))

    1984-08-01

    The measurement of alpha emitter concentrations in solution corresponds to a need felt in particular by laboratories working on actinides and in the spent fuel reprocessing industry. The instrument present here allows this measurement continuously by the use of a new scintillator that is insensitive to corrosive liquids. The extreme thinness of the scintillator guarantees good detection selectivity of alpha particles in the presence of beta and gamma emissions. Examples of uranium-233, plutonium-239 and americium-241 concentration measurements are presented.

  4. Three-port DC-DC converter with new integrated transformer for DC Distribution Systems

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Andersen, Michael A. E.

    2014-01-01

    A new integrated transformer for three-port dc-dc converter is proposed to overcome the power coupling effect existed in some known multiple inputs dc-dc converters. Orthogonal primary windings arrangement and in series connection of diagonal secondary Windings enables a fully power decoupling...

  5. On the feasibility of sub-100 nm rad emittance measurement in plasma accelerators using permanent magnetic quadrupoles

    Science.gov (United States)

    Li, F.; Wu, Y. P.; Nie, Z.; Guo, B.; Zhang, X. H.; Huang, S.; Zhang, J.; Cheng, Z.; Ma, Y.; Fang, Y.; Zhang, C. J.; Wan, Y.; Xu, X. L.; Hua, J. F.; Pai, C. H.; Lu, W.; Gu, Y. Q.

    2018-01-01

    Low emittance (sub-100 nm rad) measurement of electron beams in plasma accelerators has been a challenging issue for a while. Among various measurement schemes, measurements based on single-shot quad-scan using permanent magnetic quadrupoles (PMQs) has been recently reported with emittance as low as ∼200 nm Weingartner (2012 Phys. Rev. Spec. Top. Accel. Beams 15 111302). However, the accuracy and reliability of this method have not been systematically analyzed. Such analysis is critical for evaluating the potential of sub-100 nm rad emittance measurement using any scheme. In this paper, we analyze the effects of various nonideal physical factors on the accuracy and reliability using the PMQ method. These factors include aberration induced by a high order field, PMQ misalignment and angular fluctuation of incoming beams. Our conclusions are as follows: (i) the aberrations caused by high order fields of PMQs are relatively weak for low emittance measurement as long as the PMQs are properly constructed. A series of PMQs were manufactured and measured at Tsinghua University, and using numerical simulations their high order field effects were found to be negligible . (ii) The largest measurement error of emittance is caused by the angular misalignment between PMQs. For low emittance measurement of ∼100 MeV beams, an angular alignment accuracy of 0.1° is necessary. This requirement can be eased for beams with higher energies. (iii) The transverse position misalignment of PMQs and angular fluctuation of incoming beams only cause a translational and rotational shift of measured signals, respectively, therefore, there is no effect on the measured value of emittance. (iv) The spatial resolution and efficiency of the detection system need to be properly designed to guarantee the accuracy of sub-100 nm rad emittance measurement.

  6. Longitudinal Emittance Measurements at REX-ISOLDE

    CERN Document Server

    Fraser, MA; Piselli, E; Posocco, PA; Voulot, D; Wenander, F; Zocca, F

    2011-01-01

    The rms longitudinal emittance at output from the REX-ISOLDE RFQ was measured as 0.34 ± 0.08 π ns keV/u and at entry to the 7G3 as 0.36 ± 0.04 π ns keV/u using the three gradient technique; systematic errors are not included but are thought to be approximately 10%. The 86% emittance was measured a factor of approximately 4.4 times larger than the rms emittance at 1.48 ± 0.2 and 1.55 ± 0.12 π ns keV/u at the RFQ and 7G3, respectively. The REX-ISOLDE switchyard magnet was used as a spectrometer to analyse the energy spread as the beam was manipulated by changing the voltage of the ReB and 7G3 cavities operating at non-accelerating phases. The technique for measuring the energy spread was rigorously simulated and validated. A formalism was developed to accurately reconstruct the longitudinal beam parameters using a multi-gap constant-velocity bunching cavity when the voltage cannot be kept small. A silicon detector in its development phase was also exploited to measure the longitudinal beam properties. Th...

  7. Overview of Multi-DC-Bus Solutions for DC Microgrids

    DEFF Research Database (Denmark)

    Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco

    2013-01-01

    DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....

  8. COMPENSATION FOR BUNCH EMITTANCE IN A MAGNETIZATION AND SPACE CHARGE DOMINATED BEAM.

    Energy Technology Data Exchange (ETDEWEB)

    CHANG,X.; BEN-ZVI,I.; KEWISCH,J.

    2004-06-21

    In order to obtain sufficient cooling rates for the Relativistic Heavy Ion Collider (RHIC) electron cooling, a bunched beam with high bunch charge, high repetition frequency and high energy is required and it is necessary to use a ''magnetized'' beam, i.e., an electron beam with non-negligible angular momentum. Applying a longitudinal solenoid field on the cathode can generate such a beam, which rotates around its longitudinal axis in a field-free region. This paper suggests how a magnetized beam can be accelerated and transported from a RF photocathode electron gun to the cooling section without significantly increasing its emittance. The evolution of longitudinal slices of the beam under a combination of space charge and magnetization is investigated, using paraxial envelope equations and numerical simulations. We find that we must modify the traditional method of compensating for emittance as used for normal non-magnetized beam with space charge to account for magnetization. The results of computer simulations of successful compensation are presented. Alternately, we show an electron bunch density distribution for which all slices propagate uniformly and which does not require emittance compensation.

  9. An Observation of a Transverse to Longitudinal Emittance Exchange at the Fermilab A0 Photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Koeth, Timothy W [State Univ. of New Jersey, New Brunswick, NJ (United States)

    2009-05-01

    An experimental program to perform a proof of principle of transverse to longitudinal emittance exchange (ϵxin ↔ ϵzout and ϵxin ↔ ϵzout) has been developed at the Fermilab A0 Photoinjector. A new beamline, including two magnetic dogleg channels and a TM110 deflecting mode radio frequency cavity, were constructed for the emittance exchange experiment. The first priority was a measurement of the Emittance Exchange beamline transport matrix. The method of difference orbits was used to measure the transport matrix. Through varying individual beam input vector elements, such as xin, x'in, yin, y'in, zin, or δin, and measuring the changes in all of the beam output vector's elements, xout, x'out, yout, y'out, zout, δout, the full 6 x 6 transport matrix was measured. The measured emittance exchange transport matrix was in overall good agreement with our calculated transport matrix. A direct observation of an emittance exchange was performed by measuring the electron beam's characteristics before and after the emittance exchange beamline. Operating with a 14.3 MeV, 250pC electron bunch, ϵzin of 21.1 ± 1.5 mm • mrad was observed to be exchanged with ϵxout of 20.8 ± 2.00 mm • mrad. Diagnostic limitations in the ϵzout measurement did not account for an energy-time correlation, thus potentially returning values larger than the actual longitudinal emittance. The ϵxin of 4.67 ± 0.22 mm • mrad was observed to be exchanged with ϵzout of 7.06 ± 0.43 mm • mrad. The apparent ϵzoutgrowth is consistent with calculated values in which the correlation term is neglected.

  10. Single photon emitters in boron nitride: More than a supplementary material

    Science.gov (United States)

    Koperski, M.; Nogajewski, K.; Potemski, M.

    2018-03-01

    We present comprehensive optical studies of recently discovered single photon sources in boron nitride, which appear in form of narrow lines emitting centres. Here, we aim to compactly characterise their basic optical properties, including the demonstration of several novel findings, in order to inspire discussion about their origin and utility. Initial inspection reveals the presence of narrow emission lines in boron nitride powder and exfoliated flakes of hexagonal boron nitride deposited on Si/SiO2 substrates. Generally rather stable, the boron nitride emitters constitute a good quality visible light source. However, as briefly discussed, certain specimens reveal a peculiar type of blinking effects, which are likely related to existence of meta-stable electronic states. More advanced characterisation of representative stable emitting centres uncovers a strong dependence of the emission intensity on the energy and polarisation of excitation. On this basis, we speculate that rather strict excitation selectivity is an important factor determining the character of the emission spectra, which allows the observation of single and well-isolated emitters. Finally, we investigate the properties of the emitting centres in varying external conditions. Quite surprisingly, it is found that the application of a magnetic field introduces no change in the emission spectra of boron nitride emitters. Further analysis of the impact of temperature on the emission spectra and the features seen in second-order correlation functions is used to provide an assessment of the potential functionality of boron nitride emitters as single photon sources capable of room temperature operation.

  11. Silicon heterojunction solar cells: Optimization of emitter and contact properties from analytical calculation and numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Varache, R. [Laboratoire de Génie Electrique de Paris, Centre National de la Recherche Scientifique - Unité Mixte de Recherche 8507, Ecole Supelec, Université Paris-Sud 11, Université Pierre et Marie Curie - Paris 6, 11 rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette Cedex (France); Helmholtz-Zentrum Berlin für Materialien und Energie, Institut Silizium Photovoltaik, Kekuléstrasse 5, D-12489 Berlin (Germany); Kleider, J.P.; Gueunier-Farret, M.E. [Laboratoire de Génie Electrique de Paris, Centre National de la Recherche Scientifique - Unité Mixte de Recherche 8507, Ecole Supelec, Université Paris-Sud 11, Université Pierre et Marie Curie - Paris 6, 11 rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette Cedex (France); Korte, L. [Helmholtz-Zentrum Berlin für Materialien und Energie, Institut Silizium Photovoltaik, Kekuléstrasse 5, D-12489 Berlin (Germany)

    2013-05-15

    Highlights: ► We relate the open circuit voltage and the band-bending in crystalline silicon. ► We calculate the band-bending in the crystalline part of a silicon heterojunction. ► The band-bending is strongly influenced by the work function and density of states. ► A high defect density in the amorphous silicon emitter increases the band bending. ► A high defect density reduces the impact of the contact on the open circuit voltage. -- Abstract: The key constituent of silicon heterojunction solar cells, the amorphous silicon/crystalline silicon heterojunction (a-Si:H/c-Si), offers a high open-circuit voltage (V{sub oc}) potential providing that both the interface defect passivation and the band bending in the c-Si absorber are sufficient. We detail here analytical calculations of the equilibrium band bending in c-Si (ψ{sub c-Si}) in Transparent Conductive Oxide (TCO)/a-Si:H emitter/c-Si absorber structures. We studied the variation of some electronic parameters (density of states, work function) according to relevant experimental values. This study introduces a discussion on the optimization of the doped emitter layer in relation with the work function of the TCO. In particular, we argue on the advantage of having a highly defective (p)a-Si:H emitter layer that maximizes ψ{sub c-Si} and reduces the influence of the TCO on V{sub oc}.

  12. Single-shot measurements of low emittance beams from laser-plasma accelerators comparing two triggered injection methods

    Science.gov (United States)

    van Tilborg, Jeroen

    2017-10-01

    The success of laser plasma accelerator (LPA) based applications, such as a compact x-ray free electron laser (FEL), relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot energy-dispersed emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock-induced density down-ramp injection. Both injection mechanisms have gained in popularity in recent years due to their demonstrated stable LPA performance. For the down-ramp injection configuration, normalized emittances a factor of two lower were recorded: less than 1 micron at spectral charge densities up to 2 pC/MeV. For both injection mechanisms, a contributing correlation of space charge to the emittance was identified. This measurement technique in general, and these results specifically, are critical to the evaluation of LPA injection methods and development of high-quality LPA beam lines worldwide. This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the U.S. DOE NNSA, DNN R&D (NA22), by the National Science Foundation under Grant No. PHY-1415596, and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  13. DC arc weld starter

    Science.gov (United States)

    Campiotti, Richard H.; Hopwood, James E.

    1990-01-01

    A system for starting an arc for welding uses three DC power supplies, a high voltage supply for initiating the arc, an intermediate voltage supply for sustaining the arc, and a low voltage welding supply directly connected across the gap after the high voltage supply is disconnected.

  14. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. \\tRecent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. \\tIn this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis

  15. A Robust Fuzzy Sliding Mode Controller Synthesis Applied on Boost DC-DC Converter Power Supply for Electric Vehicle Propulsion System

    Directory of Open Access Journals (Sweden)

    Boumediène Allaoua

    2013-01-01

    Full Text Available The development of electric vehicles power electronics system control comprising of DC-AC inverters and DC-DC converters takes a great interest of researchers in the modern industry. A DC-AC inverter supplies the high power electric vehicle motors torques of the propulsion system and utility loads, whereas a DC-DC converter supplies conventional low-power, low-voltage loads. However, the need for high power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. Nonlinear control of power converters is an active area of research in the fields of power electronics. This paper focuses on a fuzzy sliding mode strategy (FSMS as a control strategy for boost DC-DC converter power supply for electric vehicle. The proposed fuzzy controller specifies changes in the control signal based on the surface and the surface change knowledge to satisfy the sliding mode stability and attraction conditions. The performances of the proposed fuzzy sliding controller are compared to those obtained by a classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variation of the load resistance and the input voltage of the studied converter.

  16. Study of direct-current, pulsed, and temperature--field emission from LaB/sub 6//tungsten field emitter

    Energy Technology Data Exchange (ETDEWEB)

    Khairnar, R. S.; Dharmadhikari, C. V.; Joag, D. S.; Kanitkar, P. L.; Nigavekar, A. S.

    1989-07-01

    This paper reports dc, temperature--field (/ital T/--/ital F/), and pulsed emission from a lanthanum hexaboride (LaB/sub 6/)--tungsten (W) field emitter. Various parameters are drived from the Fowler--Nordheim plots for the three configurations of the emitter, viz., clean tungsten, LaB/sub 6/ overgrowth on W(111) plane (''two spot''), and LaB/sub 6/ equilibrated W surface (''well spread''). The current stability is observed at 300, 730, and 850 K, (and 1065 K for well spread) under /ital T/--/ital F/ operation. A comparison is made with various types of field emitting cathodes and the results are discussed from the point of view of LaB/sub 6//W field emitting cathodes.

  17. 75 FR 6160 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-02-08

    ... Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F, MD-10-10F, MD-10-30F, MD-11, and MD-11F Airplanes AGENCY: Federal Aviation... airworthiness directive (AD) for certain Model DC-10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC- 10A and...

  18. Beam-target interaction and intrabeam scattering in the HESR ring. Emittance, momentum resolution and luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Hinterberger, F. [Bonn Univ. (Germany). Inst. fuer Strahlen- und Kernphysik

    2006-02-15

    The beam-target interaction is studied with respect to the transverse and longitudinal emittance growth of the HESR antiproton beam. The transverse emittance growth caused by the small angle Coulomb scattering can be described analytically using the differential cross section of the Coulomb interaction. Similarly, the longitudinal emittance growth caused by the energy loss of the beam can be calculated using the differential cross section of the energy-loss distribution. It is shown that particles with energy losses near the maximum energy loss in a head-on collision with a target electron are lost due to momentum acceptance of the HESR ring. Taking a relative momentum acceptance of about 1 x 10{sup -3} into account yields an order of magnitude smaller growth rate of the mean square momentum deviation. The necessary cooling rates for the High Resolution mode and the High Luminosity mode are deduced assuming that the beam-target interaction is the dominant beam heating process. For comparison the effects of intrabeam scattering are estimated. For electron and stochastic cooling, analytic expressions are quoted in order to evaluate the momentum resolution and cooling rate. The potentialities of electron and stochastic cooling are discussed with respect to the achievable momentum resolution and beam-target overlap. Beam loss rates and average luminosities are evaluated taking the total hadronic cross section, the restricted momentum acceptance of the HESR ring, the large angle Coulomb scattering and the Touschek effect into account. (orig.)

  19. Intelligent Variable Emittance Panels Using New, ""True"" Solid Electrolyte Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This work further developed a highly promising Variable Emittance technology for spacecraft thermal control based on Conducting Polymer (CP) electrochromics...

  20. Measurement of the microwave emitter's inhomogeneity using optical fiber DTS

    Science.gov (United States)

    Jaros, Jakub; Papes, Martin; Liner, Andrej; Vašinek, Vladimir; Smira, Pavel; Nasswettrova, Andrea; Cubik, Jakub; Kepak, Stanislav

    2014-06-01

    Researcher's teams were dealing with the microwave emitter's inhomogeneity problem since the microwaves were used. One possible way, how to measure electromagnetic field is the measurement on inhomogeneous temperature distribution on the irradiated sample, which can cause problems as in other material processing, so in the undesirable change of properties and even security. Inhomogeneity of electromagnetic field is specific by creating spots with higher or lower temperature called "hot spots". This inhomogeneity strongly affects the temperature distribution in the cross section of the material and its resultant heating. Given the impossibility of using classical electronic devices with metal temperature sensors were various indirect methods used in the past. This paper deals with experimental measurement of the microwave emitter's inhomogeneity (2.45 GHz) using the optical fiber DTS. The greatest advantage of this sensor system is just in using of the optical fiber (electromagnetic resistance, small size, safety using in inflammable and explosive area, easy installation). Due to these properties of the optical fiber sensor it's possible to measure the temperature of the sample in real time. These sensor are able to measure the temperature along the fiber, in some cases they use nonlinear effect in optical fiber (Raman nonlinear effect). The verification of non-homogeneity consists in experimental measuring of the temperature distribution within the wooden sample. The method is based on heat exchange in an isolated system where wooden sample serves as an absorber of the irradiated energy. To identify locations with different power density was used DTS system, based on nonlinear phenomena in optical fibers.

  1. Multi-channel polarized thermal emitter

    Science.gov (United States)

    Lee, Jae-Hwang; Ho, Kai-Ming; Constant, Kristen P

    2013-07-16

    A multi-channel polarized thermal emitter (PTE) is presented. The multi-channel PTE can emit polarized thermal radiation without using a polarizer at normal emergence. The multi-channel PTE consists of two layers of metallic gratings on a monolithic and homogeneous metallic plate. It can be fabricated by a low-cost soft lithography technique called two-polymer microtransfer molding. The spectral positions of the mid-infrared (MIR) radiation peaks can be tuned by changing the periodicity of the gratings and the spectral separation between peaks are tuned by changing the mutual angle between the orientations of the two gratings.

  2. Summary report on transverse emittance preservation

    Energy Technology Data Exchange (ETDEWEB)

    Chou, W.; Vos, L. [European Organization for Nuclear Research, Geneva (Switzerland)

    1997-12-01

    During the past years, significant progress has been made in understanding the beam transverse emittance blow-up and its preservation. However, one often finds him-/herself ignorant when he/she tries to explain what was observed in an existing machine or to predict what will happen in a machine under design. There are a number of such examples given in this report. Some of them are even fundamental. These are the challenges. But they are also the directions leading to new achievements. The workshop gladly acknowledged them and promised to work on them.

  3. A Smart Microwave Vacuum Electron Device (MVED) Using Field Emitters

    Science.gov (United States)

    2012-01-31

    The entrance slit is 0.9 mm and the exit is 0.3 mm. Then metal 1 is printed, and the structure is fired in an oven to burn out the binder. At this...connector is rated at 500V for safety . The ground and power planes on the PC Board were pulled back from theses pins in order to avoid potential

  4. A Survey of Electronics Obsolescence and Reliability

    Science.gov (United States)

    2010-07-01

    bipolar junction ( BJT ) transistor , named as its operation involves flow of both electrons and holes, consists of a layer of semiconductor material, named...they are connected to. Usage requires connecting the emitter of a NPN-type transistor to negative, and the emitter of a PNP-type to positive. BJTs are...Diodes ...........................................................................................................17 3.2.2 Transistors

  5. Design of a kilowatt DC-DC converter

    Directory of Open Access Journals (Sweden)

    Liu Hongxing

    2017-01-01

    Full Text Available In view of the low power of traditional DC-DC converters, a DC-DC converter with a kilowatt power is designed. The input signal's frequency is 1 kHz and the duty cycle is 5%. The PWM signal controls the high-speed conduction or cut-off of the switch tube. The input DC voltage is 36V, and the output voltage is twice as high as the input voltage. The output power is greater than 1 KW; the circuit conversion efficiency is 87.21%.

  6. DC micro-grids

    OpenAIRE

    Mia, Gredelj

    2014-01-01

    The conventional electrical system in place today sees our electrical devices powered by AC mains. But as renewable technologies such as solar photovoltaic and wind power become more prevalent at a household level, DC micro-grids could be a cheaper and more efficient alternative. New lighting devices (LED) can reduce the electricity consumption substantially. Two alternatives are envisioned in this paper: A stand-alone alternative in which there is no grid connection, that would require local...

  7. Minimizing Emittance for the CLIC Damping Ring

    CERN Document Server

    Braun, H; Levitchev, E; Piminov, P; Schulte, Daniel; Siniatkin, S; Vobly, P P; Zimmermann, Frank; Zolotarev, Konstantin V; CERN. Geneva

    2006-01-01

    The CLIC damping rings aim at unprecedented small normalized equilibrium emittances of 3.3 nm vertical and 550 nm horizontal, for a bunch charge of 2.6·109 particles and an energy of 2.4 GeV. In this parameter regime the dominant emittance growth mechanism is intra-beam scattering. Intense synchrotron radiation damping from wigglers is required to counteract its effect. Here the overall optimization of the wiggler parameters is described, taking into account state-of-the-art wiggler technologies, wiggler effects on dynamic aperture, and problems of wiggler radiation absorption. Two technical solutions, one based on superconducting magnet technology the other on permanent magnets are presented. Although dynamic aperture and tolerances of this ring design remain challenging, benefits are obtained from the strong damping. For optimized wigglers, only bunches for a single machine pulse may need to be stored, making injection/extraction particularly simple and limiting the synchrotron-radiation power. With a 36...

  8. Therapeutic use of alpha-emitters

    Energy Technology Data Exchange (ETDEWEB)

    Lassmann, M. [Klinik und Poliklinik fuer Nuklearmedizin der Univ. Wuerzburg (Germany)

    2005-07-01

    In recent years there is a growing interest in the therapeutic use of {alpha}-emitters for patient treatment, {alpha}-particles have much higher energy and their range is only a few cell diameters. Their high LET and the limited ability of cells to repair DNA damage from {alpha}-radiation explain their high relative biological effectiveness and cytotoxicity. Potential {alpha}-emitting isotopes for therapeutic applications are {sup 224}Ra, {sup 223}Ra, {sup 213}Bi and {sup 211}At. The treatment with {alpha}-particles is focused upon targeted cancer therapy using radiolabeled monoclonal antibodies, on palliation of bone metastases or upon pain relief in patients with ankylosing spondylitis (AS). Examples for targeted cancer therapy are the treatment of melanoma with {sup 213}Bi and non-Hodgkin lymphoma with {sup 211}At. For metastatic bone pain palliation {sup 223}Ra was applied in a phase I clinical trial. For amelioration of pain in AS-patients {sup 224}Ra-chloride is used. This radiopharmaceutical is licensed for this particular application in Germany. Today there are some potential clinical applications for {alpha}-emitters although most of them are in the state of scientific, non-routine investigations. In-vivo dosimetry for risk assessment associated with this treatment is even more difficult to perform than for therapies using beta-emitting radiopharmaceuticals. (orig.)

  9. Muon Emittance Exchange with a Potato Slicer

    Energy Technology Data Exchange (ETDEWEB)

    Summers, D. J. [Univ. of Mississippi, Oxford, MS (United States); Hart, T. L. [Univ. of Mississippi, Oxford, MS (United States); Acosta, J. G. [Univ. of Mississippi, Oxford, MS (United States); Cremaldi, L. M. [Univ. of Mississippi, Oxford, MS (United States); Oliveros, S. J. [Univ. of Mississippi, Oxford, MS (United States); Perera, L. P. [Univ. of Mississippi, Oxford, MS (United States); Neuffer, D. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-04-15

    We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunch with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 µs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift in the ring until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87 %.

  10. Design of Electronic Experiments Using Computer Generated Virtual Instruments

    Science.gov (United States)

    1994-03-01

    is displayed on the front panel DC Voltage meter. C LABORATORY 4 DESIGN The original Laboratory 4, Transistor ( BJT ) Characteristics, experiment...voltage relations of an NPN transistor in a common-emitter circuit configuration used in both the static and dynamic operation. 5. Transistor curve...of a BJT common emitter amplifier to stated specifications, test it for prop biasing signal amplification characteristics and operational stability. 7

  11. Emitter-site-selective photoelectron circular dichroism of trifluoromethyloxirane

    Science.gov (United States)

    Ilchen, M.; Hartmann, G.; Rupprecht, P.; Artemyev, A. N.; Coffee, R. N.; Li, Z.; Ohldag, H.; Ogasawara, H.; Osipov, T.; Ray, D.; Schmidt, Ph.; Wolf, T. J. A.; Ehresmann, A.; Moeller, S.; Knie, A.; Demekhin, Ph. V.

    2017-05-01

    The angle-resolved inner-shell photoionization of R-trifluoromethyloxirane, C3H3F3O , is studied experimentally and theoretically. Thereby, we investigate the photoelectron circular dichroism (PECD) for nearly symmetric O 1 s and F 1 s electronic orbitals, which are localized on different molecular sites. The respective dichroic β1 and angular distribution β2 parameters are measured at the photoelectron kinetic energies from 1 to 16 eV by using variably polarized synchrotron radiation and velocity map imaging spectroscopy. The present experimental results are in good agreement with the outcome of ab initio electronic structure calculations. We report a sizable chiral asymmetry β1 of up to about 9% for the K -shell photoionization of oxygen atom. For the individual fluorine atoms, the present calculations predict asymmetries of similar size. However, being averaged over all fluorine atoms, it drops down to about 2%, as also observed in the present experiment. Our study demonstrates a strong emitter and site sensitivity of PECD in the one-photon inner-shell ionization of this chiral molecule.

  12. A CW normal-conductive RF gun for free electron laser and energy recovery linac applications

    Energy Technology Data Exchange (ETDEWEB)

    Baptiste, Kenneth; Corlett, John; Kwiatkowski, Slawomir; Lidia, Steven; Qiang, Ji; Sannibale, Fernando; Sonnad, Kiran; Staples, John; Virostek, Steven; Wells, Russell

    2008-10-08

    Currently proposed energy recovery linac and high average power free electron laser projects require electron beam sources that can generate up to {approx} 1 nC bunch charges with less than 1 mmmrad normalized emittance at high repetition rates (greater than {approx} 1 MHz). Proposed sources are based around either high voltage DC or microwave RF guns, each with its particular set of technological limits and system complications. We propose an approach for a gun fully based on mature RF and mechanical technology that greatly diminishes many of such complications. The concepts for such a source as well as the present RF and mechanical design are described. Simulations that demonstrate the beam quality preservation and transport capability of an injector scheme based on such a gun are also presented.

  13. A Design Report of the Baseline for PEP-X: an Ultra-Low Emittance Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl; Bertsche, Kirk; Cai, Yunhai; Chao, Alex; Corbett, Willian; Fox, John; Hettel, Robert; Huang, Xiaobiao; Huang, Zhirong; Ng, Cho-Kuen; Nosochkov, Yuri; Novokhatski, Sasha; Radedeau, Thomas; Raubenheimer, Tor; Rivetta, Claudio; Safranek, James; Seeman, John; Stohr, Joachim; Stupakov, Gennady; Wang, Lanfa; Wang, Min-Huey; /SLAC

    2010-06-02

    Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance storage ring that could reside in the existing 2.2-km PEPII tunnel. The design features a hybrid lattice with double bend achromat (DBA) cells in two arcs and theoretical minimum emittance (TME) cells in the remaining four arcs. Damping wigglers are used to reduce the horizontal emittance to 86 pm-rad at zero current for a 4.5 GeV electron beam. At a design current of 1.5 A, the horizontal emittance increases, due to intrabeam scattering, to 164 pm-rad when the vertical emittance is maintained at a diffraction limited 8 pm-rad. The baseline design will produce photon beams achieving a brightness of 10{sup 22} (ph/s/mm{sup 2}/mrad{sup 2}/0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional off-axis injection system. In this report, we present the results of study, including the lattice properties, nonlinear dynamics, intra-beam scattering and Touschek lifetime, RF system, and collective instabilities. Finally, we discuss the possibility of partial lasing at soft X-ray wavelengths using a long undulator in a straight section.

  14. Coated nano-particle jamming of quantum emitters

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2012-01-01

    Spherical active coated nano-particles are examined analytically and numerically in the presence of one, two or four quantum emitters (electric Hertzian dipoles). The ability of the coated nano-particle to effectively cloak the emitters to a far-field observer is reported. This offers...

  15. Properties of nanolasers based on few discrete emitters

    DEFF Research Database (Denmark)

    Lund, Anders Mølbjerg; Nielsen, Per Kær; Lorke, Michael

    2012-01-01

    emitters and 100 photon states the density matrix has more than 2.5 × 106 elements. We have been able to simplify the problem significantly by adiabatically eliminating the photon-assisted polarizations and the correlations between emitters and cavity [3]. This results in a set of rate equations...

  16. Low Cost Constant – Head Drip Irrigation Emitter for Climate ...

    African Journals Online (AJOL)

    The drip system comprises of abarrel, sub-main line, lateral lines, tubes and emitters, it can irrigate140 crop stands and can be extended to 560 stands. The emitters produced a mean discharge and emission uniformity (Eu) of 1.60l/hr. and 74 % respectively; while the calibrated manufacturer's coefficient of variation and ...

  17. Emittance measurements of low-energy beam line at KVI

    NARCIS (Netherlands)

    Toprek, D; Formanoy, [No Value

    2006-01-01

    In this paper is represented the results of beam profile measurements of He-3(+) beam delivered from ECR ion source at KVI. The beam emittance is estimated by varying quadrupole method. The estimated values for the beam emittance at the different profile grid locations along the transport beam line

  18. Dynamic Evolution Control for Fuel Cell DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Ahmad Saudi Samosir

    2011-04-01

    Full Text Available Fuel cells are new alternative energy resource that has a great promise for distributed generation and electric vehicle application. However, fuel cells have a slow response due to their slow internal electromechanical and thermodynamic response. To optimize the fuel cell system performance, a fuel cell DC-DC converter with an appropriate controller which can regulate the power flow and automatically adjust the converter output voltage is needed. This paper proposes a new control technique for fuel cell DC-DC power converter. Design of the proposed control method for fuel cell DC-DC power converter is provided. A new approach for converter controllers synthesis based on dynamic evolution control theory is presented. In this paper, synthesis example of boost DC-DC converter is discussed. Performance of the proposed dynamic evolution control under step load variation condition is simulated under Matlab-Simulink environment. Simulation results show that the proposed techniques are capable for controlling fuel cell DC-DC converter.

  19. A Two-Frequency RF Cavity for the PSI Low Emittance Gun

    CERN Document Server

    Raguin, J Y; Li, K S B; Pedrozzi, M

    2005-01-01

    In the Low Emittance Gun (LEG) under development at PSI an extremely bright electron beam is produced from a field emission array and then rapidly accelerated in a diode configuration up to 1 MeV with gradients of the order of 250 to 500 MV/m. The electronic emission from such a cold cathode allows normalized intrinsic emittance below 0.1 mm.mrad well suited for X-ray FELs or linear collider applications. The diode is followed by an L-band RF-gun like cavity to further accelerate the beam. A third harmonic field is superposed to the fundamental [1] 1.5 GHz pi-mode field to minimize the RF emittance. We report here on the design of such a two-frequency RF cavity with some details on the RF coupling and possible tuning mechanisms. Beam dynamics studies, performed with PARMELA and the fully self-consistent code MAFIA, are presented and compared with the results obtained for an RF cavity excited with the fundamental frequency only.

  20. Transverse emittance and phase space program developed for use at the Fermilab A0 Photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Thurman-Keup, R.; Johnson, A.S.; Lumpkin, A.H.; Ruan, J.; /Fermilab

    2011-03-01

    The Fermilab A0 Photoinjector is a 16 MeV high intensity, high brightness electron linac developed for advanced accelerator R&D. One of the key parameters for the electron beam is the transverse beam emittance. Here we report on a newly developed MATLAB based GUI program used for transverse emittance measurements using the multi-slit technique. This program combines the image acquisition and post-processing tools for determining the transverse phase space parameters with uncertainties. An integral part of accelerator research is a measurement of the beam phase space. Measurements of the transverse phase space can be accomplished by a variety of methods including multiple screens separated by drift spaces, or by sampling phase space via pepper pots or slits. In any case, the measurement of the phase space parameters, in particular the emittance, can be drastically simplified and sped up by automating the measurement in an intuitive fashion utilizing a graphical interface. At the A0 Photoinjector (A0PI), the control system is DOOCS, which originated at DESY. In addition, there is a library for interfacing to MATLAB, a graphically capable numerical analysis package sold by The Mathworks. It is this graphical package which was chosen as the basis for a graphical phase space measurement system due to its combination of analysis and display capabilities.

  1. Vacuum Rabi spectra of a single quantum emitter.

    Science.gov (United States)

    Ota, Yasutomo; Ohta, Ryuichi; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2015-04-10

    We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We use a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences from those measured by detecting the cavity photon leakage. Moreover, we observe an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

  2. Silicon heterojunction solar cells with p nanocrystalline thin emitter on monocrystalline substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zignani, F.; Desalvo, A.; Centurioni, E.; Iencinella, D.; Rizzoli, R.; Summonte, C.; Migliori, A

    2004-03-22

    In the framework of plasma deposition of silicon heterojunction solar cells, the issue of depositing by very high frequency, a microcrystalline emitter, without affecting the passivating properties of the underlying amorphous buffer layer, is addressed. The sequence, deposition-exposure to H{sub 2} plasma-deposition, was used to fabricate the microcrystalline emitter. Using high-resolution transmission electron microscopy, we give microscopic evidence of the long-range effects of hydrogen, already inferred by large area optical techniques. Upon exposure to H{sub 2} plasma, it is observed that silicon nanocrystallites are formed within the amorphous layer. Thinner amorphous layers undergo etching, and epitaxial growth takes place from the substrate. Photovoltaic devices with open circuit voltage up to 638 mV were fabricated.

  3. Probing the Electromagnetic Local Density of States with a Strongly Mixed Electric and Magnetic Dipole Emitter

    CERN Document Server

    Karaveli, Sinan; Zia, Rashid

    2013-01-01

    We identify a solid-state quantum emitter whose room-temperature radiative decay is mediated by a nearly equal mixture of isotropic electric dipole (ED) and magnetic dipole (MD) transitions. Using energy-momentum spectroscopy, we experimentally show that the near-infrared $^3$T$_2{\\rightarrow}^3$A$_2$ emission from divalent-nickel-doped magnesium oxide (Ni$^{2+}$:MgO) is composed of $\\sim$50% MD and $\\sim$50% ED transitions. We then demonstrate that the spontaneous emission rate of these ions near planar interfaces is determined by the combined electric and magnetic local density of optical states (LDOS). This electromagnetic LDOS probes the total mode density, and thus similar to thermal emission, these unique electronic emitters effectively excite all polarizations and orientations of the electromagnetic field.

  4. Emitter tailoring in ion implanted and e-beam annealed silicon solar cells

    Science.gov (United States)

    Gabilli, E.; Galloni, R.; Lulli, G.; Merli, P. G.; Nipoti, R.; Ostoja, P.; Rizzoli, R.; Servidori, M.; Susi, E.; Zignani, F.

    Ion implanted solar cells, with tailored emitters, have been analyzed both theoretically, by using a one dimensional computer model, and experimentally, in order to improve the collection efficiency by an increased electric field effect, and to decrease the negative influence of residual lattice damage. Annealing in the solid phase regime was performed by e-beam irradiations at power densities between 5 and 40 W/sq cm and times of exposure of 2s and 15s, and by furnace treatments. Electrical measurements and stripping were used, to detect the active dopant profile concentration and the majority carrier mobility profile in the implanted emitter region. X-ray double crystal diffractometry was used to obtain information on residual crystal strain after annealing. Experiments were performed in electronic grade silicon single crystals and preliminary results were also obtained on solar grade poly. Bulk life-time variations after thermal treatment were analyzed and correlated to the oxygen and carbon state in the crystal.

  5. Collective plasmon-modes in gain media quantum emitters and plasmonic nanostructures

    CERN Document Server

    Rivera, V A G; Ledemi, Y; Messaddeq, Y; Marega Jr , E

    2015-01-01

    This book represents the first detailed description, including both theoretical aspects and experimental methods, of the interaction of rare-earth ions with surface plasmon polariton from the point of view of collective plasmon-photon interactions via resonance modes (metal nanoparticles or nanostructure arrays) with quantum emitters (rare-earth ions). These interactions are of particular interest for applications to optical telecommunications, optical displays, and laser solid state technologies. Thus, our main goal is to give a more precise overview of the rapidly emerging field of nanophotonics by means of the study of the quantum properties of light interaction with matter at the nanoscale. In this way, collective plasmon-modes in a gain medium result from the interaction/coupling between a quantum emitter (created by rare-earth ions) with a metallic surface, inducing different effects such as the polarization of the metal electrons (so-called surface plasmon polariton - SPP), a field enhancement sustaine...

  6. Theory and measurements of emittance preservation in plasma wakefield acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Frederico, Joel

    2016-12-01

    In this dissertation, we examine the preservation and measurement of emittance in the plasma wakefield acceleration blowout regime. Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles that has been demonstrated to have the potential for gradients orders of magnitude greater than traditional approaches. The application of PWFA to the design of a linear collider will make new high energy physics research possible, but the design parameters must first be shown to be competitive with traditional methods. Emittance preservation is necessary in the design of a linear collider in order to maximize luminosity. We examine the conditions necessary for circular symmetry in the PWFA blowout regime, and demonstrate that current proposals meet these bounds. We also present an application of beam lamentation which describes the process of beam parameter and emittance matching. We show that the emittance growth saturates as a consequence of energy spread in the beam. The initial beam parameters determine the amount of emittance growth, while the contribution of energy spread is negligible. We also present a model for ion motion in the presence of a beam that is much more dense than the plasma. By combining the model of ion motion and emittance growth, we find the emittance growth due to ion motion is minimal in the case of marginal ion motion. In addition, we present a simulation that validates the ion motion model, which is under further development to examine emittance growth of both marginal and pronounced ion motion. Finally, we present a proof-of-concept of an emittance measurement which may enable the analysis of emittance preservation in future PWFA experiments.

  7. A new optimum topology switching dc-to-dc converter

    Science.gov (United States)

    Cuk, S.; Middlebrook, R. D.

    1977-01-01

    A novel switching dc-to-dc converter is presented, which has the same general conversion property (increase or decrease of the input dc voltage) as does the conventional buck-boost converter, and which offers through its new optimum topology higher efficiency, lower output voltage ripple, reduced EMI, smaller size and weight, and excellent dynamic response. One of its most significant advantages is that both input and output current are not pulsating but are continuous (essentially dc with small superimposed switching current ripple), thus resulting in a close approximation to the ideal physically nonrealizable dc-to-dc transformer. The converter retains the simplest possible structure with the minimum number of components which, when interconnected in its optimum topology, yield the maximum performance.

  8. The Drive Laser System for DC-SC Injector

    CERN Document Server

    Lu Xiang Yang; Quan, Shengwen; Wang, Fang; Zhao, Kui

    2004-01-01

    PKU-SCAF has developed a photoinjector which adopt a 1+1/2 cell super conducting cavity and DC electron gun. We also developed a low cost drive laser system for the photocathode DC gun to provide high average beam current. This laser system include a commercial high repetition rate, ps, all solid-state laser, the home made SHG and FHG, Fourier relay optics and the uniform illumination optics. The test results shows the output power at 266 nm of the laser system is more than 1.2W and got more than 500 A beam current from CsTe cathode from the DC gun.

  9. Modelling of dc characteristics for granular semiconductors

    Science.gov (United States)

    Varpula, Aapo; Sinkkonen, Juha; Novikov, Sergey

    2010-11-01

    The dc characteristics of granular n-type semiconductors are calculated analytically with the drift-diffusion theory. Electronic trapping at the grain boundaries (GBs) is taken into account. The use of quadratic and linear GB potential profiles in the calculation is compared. The analytical model is verified with numerical simulation performed by SILVACO ATLAS. The agreement between the analytical and numerical results is excellent in a large voltage range. The results show that electronic trapping at the GBs has a remarkable effect on the highly nonlinear I-V characteristics of the material.

  10. Mesoscopic quantum emitters coupled to plasmonic nanostructures

    DEFF Research Database (Denmark)

    Andersen, Mads Lykke

    This thesis reports research on quantum dots coupled to dielectric and plasmonic nano-structures by way of nano-structure fabrication, optical measurements, and theoretical modeling. To study light-matter interaction, plasmonic gap waveguides with nanometer dimensions as well as samples for studies...... of quantum dots in proximity to semiconductor/air and semiconductor/metal interfaces, were fabricated. We measured the decay dynamics of quantum dots near plasmonic gap waveguides and observed modied decay rates. The obtainable modications with the fabricated structures are calculated to be too small...... to allow for e- cient plasmon-based single-photon sources. Theoretical studies of coupling and propagation properties of plasmonic waveguides reveal that a high-refractive index of the medium surrounding the emitter, e.g. nGaAs = 3.5, limits the realizability of ecient plasmon-based single-photon sources...

  11. A simple X-ray emitter.

    Science.gov (United States)

    Murakami, Hiroaki; Ono, Ryoichi; Hirai, Atsuhiko; Hosokawa, Yoshinori; Kawai, Jun

    2005-07-01

    A compact X-ray emission instrument is made, and the X-ray spectra are measured by changing the applied electric potential. Strong soft X-rays are observed when evacuating roughly and applying a high voltage to an insulator settled in this device. The X-ray intensity is higher as the applied voltage is increased. A light-emitting phenomenon is observed when this device emits X-rays. The present X-ray emitter is made of a small cylinder with a radius of 20 mm and a height of 50 mm. This X-ray generator has a potential to be used as an X-ray source in an X-ray fluorescence spectrometer.

  12. PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC

    Directory of Open Access Journals (Sweden)

    Bambang Prio Hartono

    2012-09-01

    Full Text Available Abstract: Using system fuzzy logic as control  technology have been used on low load dc-dc converter with combined parallel compiled  dc-dc converter can  obtain big load.   With existence of differrence of component parameter and each parallel compiled converter can obtained different current  and voltage output.  Function of controller  for to do adjustment, so that current which is applied  to  load by each converter  can be obtained  difference error as small as possible or same. The object of research is developing design of large signal dc-dc converter which is  combined with using  FLC so that  obtain  better performance.  To get better performance have been made plant model and simulation with CDE method.  The more systematic  system and design is needed to overcome bigger load  on dc-dc converter, so that parallel  compiled current master slave control system on dc-dc converter with using fuzzy logic  controller is used. Result of  research showed that error or difference of  current  which is applied to load can handled by fuzzy logic  controller.  Technic of current and voltage controller co to do adjustment current and voltage distribution  equally to load.  Distribution of iL1,iL2 and  output voltage Vo on dc-dc  converter with load 2,25 until  7,875 and voltage  100  until 120 volt,  load current beetwen  12 until 48, % relatif  error  Vo  0,4% until  0,9%.

  13. Determination and error analysis of emittance and spectral emittance measurements by remote sensing. [of leaves, soil and plant canopies

    Science.gov (United States)

    Kumar, R.

    1977-01-01

    Theoretical and experimental determinations of the emittance of soils and leaves are reviewed, and an error analysis of emittance and spectral emittance measurements is developed as an aid to remote sensing applications. In particular, an equation for the upper bound of the absolute error in an emittance determination is derived. The absolute error is found to decrease with an increase in contact temperature and to increase with an increase in environmental integrated radiant flux density. The difference between temperature and band radiance temperature is plotted as a function of emittance for the wavelength intervals 4.5 to 5.5 microns, 8 to 13.5 microns and 10.2 to 12.5 microns.

  14. Direct Sensitivity Analysis of the DC-to-DC Converters

    Directory of Open Access Journals (Sweden)

    Elena Niculescu

    2009-05-01

    Full Text Available The mathematical principle of the directsensitivity analysis of the dynamic systems and itsapplication to the DC-to-DC PWM converters arepresented. The model of the dynamic system associatedto the PWM Sepic converter with parasitic includedand continuous conduction mode (CCM, and coupledinductors was used in this study. The modelling of theconverter and the state sensitivity analysis with respectto some parameters of the converter have beenperformed with MATLAB environment. The algorithmcarried out for computing the state sensitivity functionsof converter can be applied to other configurations ofDC-to-DC PWM converters, for the two operatingmodes (CCM and DCM, with parasitic included andwith coupled or separate inductors, regardless ofsystem order.

  15. Optics Design and Performance of an Ultra-Low Emittance Damping Ring for the Compact Linear Collider

    CERN Document Server

    Korostelev, M S

    2006-01-01

    A high-energy (0.5-3.0 TeV centre of mass) electron-positron Compact Linear Collider (CLIC) is being studied at CERN as a new physics facility. The design study has been optimized for 3 TeV centre-of-mass energy. Intense bunches injected into the main linac must have unprecedentedly small emittances to achieve the design luminosity 1035cm-2s-1 required for the physics experiments. The positron and electron bunch trains will be provided by the CLIC injection complex. This thesis describes an optics design and performance of a positron damping ring developed for producing such ultra-low emittance beam. The linear optics of the CLIC damping ring is optimized by taking into account the combined action of radiation damping, quantum excitation and intrabeam scattering. The required beam emittance is obtained by using a TME (Theoretical Minimum Emittance) lattice with compact arcs and short period wiggler magnets located in dispersionfree regions. The damping ring beam energy is chosen as 2.42 GeV. The lattice featu...

  16. Three-gradient Emittance Measurements at REX-ISOLDE

    CERN Document Server

    Olsson, T; Lanaia, D; Voulot, D

    2013-01-01

    The transverse emittance was measured using the three-gradient method (also known as the quadrupole scan method) and compared to the slit-grid method that is normally used at REX-ISOLDE. For a 2.85 MeV/u beam with A=q = 4 the rms normalised emittance was measured as 0:32 0:06 mm mrad with the three-gradient method, a factor of 5 larger than was measured by the NTG emittance meter. An investigation into the discrepancy and a hypothesis for its cause are detailed in this note.

  17. New Low Emittance Lattice for the Super-B Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Biagini, M.E.; Boscolo, M.; Raimondi, P.; Tomassini, S.; Zobov, M.; /Frascati; Seeman, J.; Sullivan, M.; Wienands, U.; Wittmer, W.; /SLAC; Bettoni, S.; /CERN; Paoloni, E.; /Pisa U. /INFN, Pisa; Bogomyagkov, A.; Koop, I.; Levichev, E.; Nikitin, S.; Piminov, P.; Shatilov, D.; /Novosibirsk, IYF

    2011-10-21

    New low emittance lattices have been designed for the asymmetric SuperB accelerator, aiming at a luminosity of 10{sup 36} cm{sup -2} s{sup -1}. Main optics features are two alternating arc cells with different horizontal phase advance, decreasing beam emittance and allowing at the same time for easy chromaticity correction in the arcs. Emittance can be further reduced by a factor of two for luminosity upgrade. Spin rotation schemes for the e{sup -} beam have been studied to provide longitudinal polarization at the IP, and implementation into the lattice is in progress.

  18. Optical Properties of Selective Emitter Materials for Thermophotovoltaic Applications

    Science.gov (United States)

    Hambourger, Paul D.

    1996-01-01

    We investigate the optical properties of new "selective emitter" materials for possible use in high-efficiency thermophotovoltaic power systems. These are systems which directly convert heat to radiation at a wavelength closely matched to the bandgap energy of the solar cell. Candidate materials which have strong absorption lines fairly close to the bandgap of good solar-cell materials were chosen for study. Their emittance was measured as a function of wavelength to evaluate their promise as selective TPV emitters. Useful and informative results were obtained. Some of these results were presented at a January 1996 solar energy conference of the American Institute of Aeronautics and Astronautics.

  19. The dust nature of micro field emitters in accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V.; Petrov, V.M.

    2016-11-21

    Field emission currents emitted by micro-emitters are a limiting factor for the operational gradients of accelerating radio frequency (rf) cavities. Within the rf field emission theory the existence of needle like micro field emitters with very high length relative to the radius and corresponding high enhancement factor (β) is assumed. In this article the hypothesis that micro field emitters consists of long chains of conductive micro-particles is considered. Five different forces acting onto the particles in a high rf field are considered and the respective equations are derived. Some experimental observations and their explanation within this hypothesis are discussed.

  20. SCM Handbooks for dc-to-dc Converters

    Science.gov (United States)

    Lee, F.; Mohmoud, M.; Yu, Y.

    1984-01-01

    Two documents aid in design of control modules for dc-to-dc converters. Features of SCM include: Adaptive stability, power component stress limiting, implementation of various control laws, unified design approach. Analysis and quidelines contained in handbooks enable engineer to design SCM circuit and confidently predict resulting overall performance.

  1. Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

    Science.gov (United States)

    Gruber, Robert P.; Gott, Robert W.

    1991-01-01

    In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.

  2. Study of thermal-field emission properties and investigation of temperature dependent noise in the field emission current from vertical carbon nanotube emitters

    Science.gov (United States)

    Kolekar, Sadhu; Patole, S. P.; Patil, Sumati; Yoo, J. B.; Dharmadhikari, C. V.

    2017-10-01

    We have investigated temperature dependent field electron emission characteristics of vertical carbon nanotubes (CNTs). The generalized expression for electron emission from well-defined cathode surface is given by Millikan and Lauritsen [1] for the combination of temperature and electric field effect. The same expression has been used to explain the electron emission characteristics from vertical CNT emitters. Furthermore, this has been applied to explain the electron emission for different temperatures ranging from room temperature to 1500 K. The real-time field electron emission images at room temperature and 1500 K are recorded by using Charge Coupled Device (CCD) in order to understand the effect of temperature on distribution of electron emission spots and ring like structures in Field Emission Microscope (FEM) image. The FEM images could be used to calculate the total number of emitters per cm2 for electron emission. The calculated number of emitters per cm2 from FEM image is typically, 4.5 × 107 and the actual number emitters per cm2 present as per Atomic Force Microscopy (AFM) data is 1.2 × 1012. The measured Current-Voltage (I-V) characteristics exhibit non linear Folwer-Nordheim (F-N) type behavior. The fluctuations in the emission current were recorded at different temperatures and Fast Fourier transformed into temperature dependent power spectral density. The latter was found to obey power law relation S(f) = A(Iδ/fξ), where δ and ξ are temperature dependent current and frequency exponents respectively.

  3. Computational design of high efficiency nonplanar tri-s-triazine-based ambipolar host materials for phosphorescent blue emitters.

    Science.gov (United States)

    Nie, Zhaomin; Mai, Zhirui; Peng, Yiming; Chen, Kaiping; Zhang, Yiyun; Zheng, Wenxu

    2016-12-07

    A series of nonplanar tri-s-triazine-based molecules were designed, and their optical, electronic, and charge transport properties as ambipolar host materials for blue electrophosphorescence emitters were explored by density functional theory. The influence of the linkage between tri-s-triazine and carbazole, diphenylamine and triphenylamine, as well as the influence of a series of electron-donating and electron-withdrawing substituents on triplet energy, energy level matching and charge transport of the designed molecules was discussed in detail. Our results reveal that the molecules under investigation can serve as host materials for blue electrophosphorescence emitters. We also predicted the mobility of designed molecules with better performance in the P1[combining macron] space group. Based on the investigated results, we proposed a rational way for the design of host materials for OLEDs, and also expanded the application field of tri-s-triazine.

  4. Low Emittance Growth in a LEBT with Un-Neutralized Section

    Energy Technology Data Exchange (ETDEWEB)

    Prost, L. [Fermilab; Carneiro, J.-P. [Fermilab; Shemyakin, A. [Fermilab

    2017-12-20

    In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam’s space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern usually changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT that contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report introduces the rationale for the proposed scheme and formulates the physical arguments for it as well as its limitations. An experimental realization of the scheme was carried out at Fermilab’s PIP2IT where low beam emittance dilution was demonstrated for a 5 mA, 30 keV H- beam.

  5. Influence of injection beam emittance on beam transmission efficiency in a cyclotron.

    Science.gov (United States)

    Kurashima, Satoshi; Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Yoshida, Ken-Ichi; Okumura, Susumu

    2014-02-01

    The JAEA AVF cyclotron accelerates various kinds of high-energy ion beams for research in biotechnology and materials science. Beam intensities of an ion species of the order of 10(-9)-10(-6) ampere are often required for various experiments performed sequentially over a day. To provide ion beams with sufficient intensity and stability, an operator has to retune an ion source in a short time. However, the beam intensity downstream of the cyclotron rarely increases in proportion to the intensity at the ion source. To understand the cause of this beam behavior, transmission efficiencies of a (12)C(5+) beam from an electron cyclotron resonance ion source to the cyclotron were measured for various conditions of the ion source. Moreover, a feasible region for acceleration in the emittance of the injection beam was clarified using a transverse-acceptance measuring system. We confirmed that the beam emittance and profile were changed depending on the condition of the ion source and that matching between the beam emittance and the acceptance of the cyclotron was degraded. However, after fine-tuning to improve the matching, beam intensity downstream of the cyclotron increased.

  6. Overview of laserwire beam profile and emittance measurements for high power proton accelerators

    CERN Document Server

    Gibson, S M; Bosco, A; Gabor, C; Pozimski, J; Savage, P; Hofmann, T

    2013-01-01

    Laserwires were originally developed to measure micron-sized electron beams via Compton scattering, where traditional wire scanners are at the limit of their resolution. Laserwires have since been applied to larger beamsize, high power H$^-$ ion beams, where the non-invasive method can probe beam densities that would damage traditional diagnostics. While photo-detachment of H$^-$ ions is now routine to measure beam profiles, extending the technique to transverse and longitudinal emittance measurements is a key aim of the laserwire emittance scanner under construction at the Front End Test Stand (FETS) at the RAL. A pulsed, 30 kHz, 8kW peak power laser is fibrecoupled to motorized collimating optics, which controls the position and thickness of the laserwire delivered to the H- interaction chamber. The laserwire slices out a beamlet of neutralized particles, which propagate to a downstream scintillator and camera. The emittance is reconstructed from 2D images as the laserwire position is scanned. Results from ...

  7. Surface Texturing Investigated for a High Solar Absorptance Low Infrared Emittance Solar Collector

    Science.gov (United States)

    Jaworske, Donald A.

    2001-01-01

    The objective of this work was to design, build, and vacuum test a high solar absorptance, low infrared emittance solar collector for heat engine and thermal switching applications. Mini-satellites proposed by the Applied Physics Laboratory for operation in environments that are subject to radiation threat may utilize a heat engine for power and a thermal bus for thermal control. To achieve this goal, a surface having high solar absorptance and low infrared emittance is needed. At the NASA Glenn Research Center, one concept being pursued to achieve this goal is texturing high thermal conductivity graphite epoxy composites using a directed atomic oxygen beam and then coating the textured surface with a reflective metallic coating. Coupons were successfully textured, coated, and evaluated. A variety of texturing conditions were explored, and textures were documented by scanning electron microscopy. Copper, gold, silver, iridium, and aluminum coatings were applied, and the highest solar absorptance to infrared emittance ratio was found to be 1.3. A full-sized solar collector was manufactured with this ratio, and the amount of heat collected was observed using an Inconel calorimeter installed in a bench-top vacuum chamber equipped with a solar simulator. Results to date indicate good heat flow through the system, with 9 W of heat flow measured by the calorimeter.

  8. Commissioning of the SPARC Movable Emittance Meter and Its First Operation at PITZ

    CERN Document Server

    Catani, L; Cianchi, A

    2005-01-01

    For the SPARC Project a novel diagnostic device, called "Emittance-meter", has been conceived and constructed to perform a detailed study of the emittance compensation process in the SPARC photo-injector and to optimize the RF-gun and the accelerator working point. It consists of a movable emittance measurement system, based on the 1D pepper-pot method, installed between two long bellows with the possibility to scan a region 1.5 m long downstream the RF-gun. The construction of the device was completed in the first part of this year and a series of laboratory tests, to evaluate its performances, were carried out in Spring 2005. At the beginning of the summer the complete system was moved to DESY at Zeuthen to be installed on the Photo Injector Test Facility PITZ. After the commissioning it will used for measurements of the PITZ electron beam in the framework of a collaboration between the SPARC and PITZ Projects aiming on studies and operations with photo injectors.

  9. A DC Transformer

    Science.gov (United States)

    Youngquist, Robert C.; Ihlefeld, Curtis M.; Starr, Stanley O.

    2013-01-01

    A component level dc transformer is described in which no alternating currents or voltages are present. It operates by combining features of a homopolar motor and a homopolar generator, both de devices, such that the output voltage of a de power supply can be stepped up (or down) with a corresponding step down (or up) in current. The basic theory for this device is developed, performance predictions are made, and the results from a small prototype are presented. Based on demonstrated technology in the literature, this de transformer should be scalable to low megawatt levels, but it is more suited to high current than high voltage applications. Significant development would be required before it could achieve the kilovolt levels needed for de power transmission.

  10. Engineered Emitters for Improved Silicon Photovoltaics

    Science.gov (United States)

    Kamat, Ronak A.

    In 2014, installation of 5.3GW of new Photovoltaic (PV) systems occurred in the United States, raising the total installed capacity to 16.36GW. Strong growth is predicted for the domestic PV market with analysts reporting goals of 696GW by 2020. Conventional single crystalline silicon cells are the technology of choice, accounting for 90% of the installations in the global commercial market. Cells made of GaAs offer higher efficiencies, but at a substantially higher cost. Thin film technologies such as CIGS and CdTe compete favorably with multi-crystalline Si (u-Si), but at 20% efficiency, still lag the c-Si cell in performance. The c-Si cell can be fabricated to operate at approximately 25% efficiency, but commercially the efficiencies are in the 18-21% range, which is a direct result of cost trade-offs between process complexity and rapid throughput. With the current cost of c-Si cell modules at nearly 0.60/W. The technology is well below the historic metric of 1/W for economic viability. The result is that more complex processes, once cost-prohibitive, may now be viable. An example is Panasonic's HIT cell which operates in the 22-24% efficiency range. To facilitate research and development of novel PV materials and techniques, RIT has developed a basic solar cell fabrication process. Student projects prior to this work had produced cells with 12.8% efficiency using p type substrates. This thesis reports on recent work to improve cell efficiencies while simultaneously expanding the capability of the rapid prototyping process. In addition to the p-Si substrates, cells have been produced using n-Si substrates. The cell emitter, which is often done with a single diffusion or implant has been re-engineered using a dual implant of the same dose. This dual-implanted emitter has been shown to lower contact resistance, increase Voc, and increase the efficiency. A p-Si substrate cell has been fabricated with an efficiency of 14.6% and n-Si substrate cell with a 13

  11. Determination of appropriate DC voltage for switched mode power supply (SMPS) loads

    Science.gov (United States)

    Setiawan, Eko Adhi; Setiawan, Aiman; Purnomo, Andri; Djamal, Muchlishah Hadi

    2017-03-01

    Nowadays, most of modern and efficient household electronic devices operated based on Switched Mode Power Supply (SMPS) technology which convert AC voltage from the grid to DC voltage. Based on theory and experiment, SMPS loads could be supplied by DC voltage. However, the DC voltage rating to energize electronic home appliances is not standardized yet. This paper proposed certain method to determine appropriate DC voltage, and investigated comparison of SMPS power consumption which is supplied from AC and DC voltage. To determine the appropriate DC voltage, lux value of several lamps which have same specification energized by using AC voltage and the results is using as reference. Then, the lamps were supplied by various DC voltage to obtain the trends of the lux value to the applied DC voltage. After that, by using the trends and the reference lux value, the appropriate DC voltage can be determined. Furthermore, the power consumption on home appliances such as mobile phone, laptop and personal computer by using AC voltage and the appropriate DC voltage were conducted. The results show that the total power consumption of AC system is higher than DC system. The total power (apparent power) consumed by the lamp, mobile phone and personal computer which operated in 220 VAC were 6.93 VA, 34.31 VA and 105.85 VA respectively. On the other hand, under 277 VDC the load consumption were 5.83 W, 19.11 W and 74.46 W respectively.

  12. Beam lifetime and emittance growth in RHIC under normal operating conditions with the hydrogen gas jet, the cluster-jet and pellet targets

    Energy Technology Data Exchange (ETDEWEB)

    Trbojevic, D.

    2010-09-01

    The inelastic scattering of the beam and the residual gas molecules in RHIC could represent one of the limitations on the beam life time and emittance growth. This report covers the dominant central nuclear collisions influence on the beam lifetime and transverse emittance growth. The cross sections for the beam-gas electron radiative captures are an order of magnitude smaller. The capture cross sections include the radiative and non-radiative capture, and the capture from the electron-positron pair creation from the 'vacuum capture'.

  13. Combining and Correlating DC, Modulated, and Transient Measurement Techniques to Disentangle and Quantify Key Physical Properties for Organic Semiconductor Devices

    Science.gov (United States)

    Gundlach, David

    2015-03-01

    Organic thin film electronics offer the potential to significantly impact how humans interface with their surroundings and society in general. Substantial contributions over the past two decades in this highly multidisciplinary area of research have led to significant improvements in discrete device performance and several impressive advanced technology demonstrations. However, fundamental understanding and quantification of the physical properties and processes that govern device operation remains limited compared to conventional semiconductors, such as silicon. In this presentation I will discuss our recent development and application of combined and correlated optical-electrical measurement methods to obtain a more nuanced understanding and quantification of the critical properties and fundamental processes relevant to device operation. In particular, I will discuss the use of steady state and pulsed light techniques combined with modulated and DC electrical measurements tailored to the specific operating regimes and device structures of organic diodes (solar cells and light emitters) and transistors to provide greater understanding of charge injection, transport, lifetime, density, and recombination kinetics.

  14. Study of the measurement of the transverse emittances of a beam by the three gradients method. Application to the case of a focusing by solenoid

    Science.gov (United States)

    M'Garrech, S.

    2005-09-01

    Within the framework of the ALTO project (Linear Accelerator near the Orsay Tandem), IPN Orsay will use NEPAL facility of LAL as the ALTO injector. In order to calculate the beam optics of the linear accelerator, it is necessary to find out the electrons beam emittance at the exit of the buncher station. According to previous studies there are several methods for measuring this emittance: direct methods like the Pepper Pot technique, and indirect ones namely the three distances method and the three gradients technique. Moreover, the latter requires a variable optic element (i.e. quadrupole, solenoid…). Generally, the solenoid is used to focus the beam when the later has a symmetry axe of revolution compared to the direction of propagation and it has the same emittance in the two horizontal and vertical planes. In the case of ALTO injector, we did not have the certainty if the beam presented such symmetry. The effects of coupling introduced by the action of the solenoid were thus to be planned to determine the emittance starting from the transverse profiles measurement. This is why we developed a general method of calculation which takes into account the coupling when the horizontal and vertical emittances are different. The first part of this study is dedicated to its presentation. The second part is dedicated to the presentation of emittance measurement results obtained by using this method.

  15. Estimation Method for Turn-off Collector Voltage of IGBTs Using Emitter-auxiliary Inductor

    DEFF Research Database (Denmark)

    Luo, Haoze; Iannuzzo, Francesco; Blaabjerg, Frede

    2016-01-01

    of high-voltage and high-power IGBT module, there exists an emitter-auxiliary inductor between the power emitter and Kelvin emitter. The same variable dic/dt during turn-off transition will also induce a measurable voltage veE across the emitter-auxiliary inductor LeE. As a result, the hazardous turn...

  16. Emittance preservation in plasma-based accelerators with ion motion

    Science.gov (United States)

    Benedetti, C.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2017-11-01

    In a plasma-accelerator-based linear collider, the density of matched, low-emittance, high-energy particle bunches required for collider applications can be orders of magnitude above the background ion density, leading to ion motion, perturbation of the focusing fields, and, hence, to beam emittance growth. By analyzing the response of the background ions to an ultrahigh density beam, analytical expressions, valid for nonrelativistic ion motion, are derived for the transverse wakefield and for the final (i.e., after saturation) bunch emittance. Analytical results are validated against numerical modeling. Initial beam distributions are derived that are equilibrium solutions, which require head-to-tail bunch shaping, enabling emittance preservation with ion motion.

  17. Measurement of Emittance of Beam in the Debuncher During Stacking

    Energy Technology Data Exchange (ETDEWEB)

    Halling, Mike

    1991-12-11

    The emittance of antiprotons in the debuncher was measured using two methods during normal stacking conditions. With 2.3 seconds of cooling the vertical emittance was found to be 3.6 {pi} mm-mr using scraper D:TJ308, and 2.9 {pi} mm-mr using the profile on SEM806. With 6.9 seconds of cooling time time the measured horizontal emittance was 2.1 {pi} mm-mr using D:RJ306 v.s. 1.9 {pi} mm-mr using SEM806; but with 2.3 seconds of cooling the measured emittance in the debuncher was larger than in the DTOA line, 4.5 {pi} mm-mr v.s. 2.8 {pi} mm-mr. This suggests that some beam is being scraped on a horizontal aperture restriction someplace in the extraction process.

  18. Optimization of Metamaterial Selective Emitters for Use in Thermophotovoltaic Applications

    Science.gov (United States)

    Pfiester, Nicole A.

    The increasing costs of fossil fuels, both financial and environmental, has motivated many to look into sustainable energy sources. Thermophotovoltaics (TPVs), specialized photovoltaic cells focused on the infrared range, offer an opportunity to achieve both primary energy capture, similar to traditional photovoltaics, as well as secondary energy capture in the form of waste heat. However, to become a feasible energy source, TPV systems must become more efficient. One way to do this is through the development of selective emitters tailored to the bandgap of the TPV diode in question. This thesis proposes the use of metamaterial emitters as an engineerable, highly selective emitter that can withstand the temperatures required to collect waste heat. Metamaterial devices made of platinum and a dielectric such as alumina or silicon nitride were initially designed and tested as perfect absorbers. High temperature robustness testing demonstrates the device's ability to withstand the rigors of operating as a selective emitter.

  19. Nanobubble induced formation of quantum emitters in monolayer semiconductors

    Science.gov (United States)

    Shepard, Gabriella D.; Ajayi, Obafunso A.; Li, Xiangzhi; Zhu, X.-Y.; Hone, James; Strauf, Stefan

    2017-06-01

    The recent discovery of exciton quantum emitters in transition metal dichalcogenides (TMDCs) has triggered renewed interest of localized excitons in low-dimensional systems. Open questions remain about the microscopic origin previously attributed to dopants and/or defects as well as strain potentials. Here we show that the quantum emitters can be deliberately induced by nanobubble formation in WSe2 and BN/WSe2 heterostructures. Correlations of atomic-force microscope and hyperspectral photoluminescence images reveal that the origin of quantum emitters and trion disorder is extrinsic and related to 10 nm tall nanobubbles and 70 nm tall wrinkles, respectively. We further demonstrate that ‘hot stamping’ results in the absence of 0D quantum emitters and trion disorder. The demonstrated technique is useful for advances in nanolasers and deterministic formation of cavity-QED systems in monolayer materials.

  20. Transverse Emittance Measurement and Preservation at the LHC

    CERN Document Server

    AUTHOR|(CDS)2082907

    The Large Hadron Collider (LHC) at CERN is a high energy storage ring that provides proton and heavy ion collisions to study fundamental particle physics. The luminosity production is closely linked to emittance preservation in the accelerator. The transverse emittance is the phase space density of the beam and should be conserved when the particle beam is transformed through the accelerator. Perturbing effects, however, can lead to emittance increase and hence luminosity degradation. Measuring the emittance growth is a complex task with high intensity beams and changing energies. The machine optics and the transverse beam size have to be measured as accurately as possible. Beta function measurements with k-modulation will be discussed. With this method the quadrupole focussing strength is varied and the resulting tune change is traced to determine the beta function at the quadrupole. A new k-modulation measurement tool was developed for the LHC. The fully automatic and online measurement system takes constra...

  1. Absolute beam emittance measurements at RHIC using ionization profile monitors

    Energy Technology Data Exchange (ETDEWEB)

    Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Connolly, R [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Summers, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tepikian, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-08-15

    In the past, comparisons between emittance measurements obtained using ionization profile monitors, Vernier scans (using as input the measured rates from the zero degree counters, or ZDCs), the polarimeters and the Schottky detectors evidenced significant variations of up to 100%. In this report we present studies of the RHIC ionization profile monitors (IPMs). After identifying and correcting for two systematic instrumental errors in the beam size measurements, we present experimental results showing that the remaining dominant error in beam emittance measurements at RHIC using the IPMs was imprecise knowledge of the local beta functions. After removal of the systematic errors and implementation of measured beta functions, precise emittance measurements result. Also, consistency between the emittances measured by the IPMs and those derived from the ZDCs was demonstrated.

  2. New technique to measure emittance for beams with space charge

    Directory of Open Access Journals (Sweden)

    K. Poorrezaei

    2013-08-01

    Full Text Available The characterization of the transverse phase space of beams is a fundamental requirement for particle accelerators. We present a novel approach for measurement of transverse emittance for beams with space charge, an important quality indicator of transverse phase space. The method utilizes a lens-drift-screen setup similar to that of a quadrupole scan emittance measurement. Measurements of radius and divergence that can be obtained from beam produced radiation, e.g. optical transition, are used to calculate the cross-correlation term and therefore the rms emittance. A linear space-charge model is used in the envelope equations; hence, the errors in the measurement relate to the nonuniformity of the beam distribution. The emittance obtained with our method shows small deviation from those obtained by WARP simulations for beams with high space charge, in contrast to other techniques.

  3. Two-photon interference from two blinking quantum emitters

    Science.gov (United States)

    Jöns, Klaus D.; Stensson, Katarina; Reindl, Marcus; Swillo, Marcin; Huo, Yongheng; Zwiller, Val; Rastelli, Armando; Trotta, Rinaldo; Björk, Gunnar

    2017-08-01

    We investigate the effect of blinking on the two-photon interference measurement from two independent quantum emitters. We find that blinking significantly alters the statistics in the Hong-Ou-Mandel second-order intensity correlation function g(2 )(τ ) and the outcome of two-photon interference measurements performed with independent quantum emitters. We theoretically demonstrate that the presence of blinking can be experimentally recognized by a deviation from the gD(2 )(0 ) =0.5 value when distinguishable photons from two emitters impinge on a beam splitter. Our findings explain the significant differences between linear losses and blinking for correlation measurements between independent sources and are experimentally verified using a parametric down-conversion photon-pair source. We show that blinking imposes a mandatory cross-check measurement to correctly estimate the degree of indistinguishability of photons emitted by independent quantum emitters.

  4. Intelligent Variable Emittance Panels Using New, ?True? Solid Electrolyte Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This firm has, in ongoing work in collaboration with the Air Force, NASA and JPL, developed a unique Variable Emittance technology based on the electrochromism of...

  5. Emittance display on the new Linac controls computer

    CERN Document Server

    CERN PhotoLab

    1975-01-01

    Top left : horizontal emittance plot. Top right : above-angular beam profile; below-horizontal beam profile. Bottom : "mountain range" display combining beam intensity distribution as the third dimension with the horizontal.

  6. Emittance preservation in plasma-based accelerators with ion motion

    Science.gov (United States)

    Benedetti, Carlo; Schroeder, Carl; Esarey, Eric E.; Leemans, Wim

    2017-10-01

    In a plasma-accelerator-based linear collider, the density of matched, low-emittance, high-energy particle bunches required for collider applications can be orders of magnitude above the background ion density, leading to ion motion, nonlinear focusing fields, and, hence, to beam emittance growth. By analyzing the response of the background ions to an ultra-high density beam, analytical expressions, valid for nonrelativistic ion motion, are derived for the transverse wakefield and for the final (i.e., after saturation) bunch emittance. Analytical results are validated against numerical modeling. A class of initial beam distributions are derived that are equilibrium solutions, which require head-to-tail bunch shaping, enabling emittance preservation with ion motion. This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. DOE under Contract No. DE-AC02-05CH11231.

  7. Scanning Anode Field Emission Characterisation of Carbon Nanotube emitter arrays

    NARCIS (Netherlands)

    Berhanu, S.; Gröning, O.; Chen, Z.; Merikhi, J.; Bachmann, P.K.

    2011-01-01

    Scanning anode field emission microscopy (SAFEM) was used to characterise carbon nanotube (CNT) emitter arrays produced within Philips CediX-Technotubes' activities. Four different samples were investigated and compared. The field enhancement distributions were determined and the local field

  8. Power Capability in Low Voltage DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    C.O. Gecan

    2009-12-01

    Full Text Available Recent developments in power electronics components enable the use of power electronics in Low Voltage (LV networks. This development makes the model of a Low Voltage Direct Current (LVDC distribution system possible. The technical and economical benefits of this technology make possible the alternative hypothesis of using DC instead of AC distribution systems. Some aspects, such as increasing the capability of the existing lines, interconnecting distributed generation units and even supplying in DC some loads are creating additional requirements of using a LVDC distribution system. The paper presents some general considerations regarding cables used in a LVAC distribution system and different line reconfigurations witch enable the use of cobles in a LVDC distribution system. The reconfigurations are presented in respect of the DC network topologies: unipolar and bipolar. The central aim of this paper is to investigate capability of power transmission and to calculate the transmission distance for cables used in Low Voltage AC and DC distribution systems. Capability computation is considered in respect of two constrains imposed in the cables cross section selection: cable thermal limit and the maximum allowable voltage drop. Cable thermal limit is represented in calculations by the maximum rated current. The equations used to calculate the power capability are presented for single-phase and threephase AC networks and unipolar and bipolar DC networks. Based on these equations, comparisons between power capability of cables with different cross sections used in Low Voltage DC and AC distribution systems are realized and presented.

  9. Internal emitter limits for iodine, radium and radon daughters

    Energy Technology Data Exchange (ETDEWEB)

    Schlenker, R.A.

    1984-08-15

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (/sup 131/I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables.

  10. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    OpenAIRE

    Guag Joshua W; Seidman Seth J; Pantchenko Oxana S; Witters Donald M; Sponberg Curt L

    2011-01-01

    Abstract Background The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, inco...

  11. Study of ultra-low emittance design for SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Wang, M. -H.; Huang, X.; Safranek, J.; /SLAC

    2015-09-17

    Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now, to further enhance the performance of SPEAR3, we are looking into the possibility of converting SPEAR3 to an ultra-low emittance storage ring within its site constraint.

  12. Modular Power System Configured with Standard Product Hybrid DC-DC Converters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — VPT proposes an innovative concept whereby complex, multiple-output, DC-DC converter systems can be configured through use of only 2 standard product hybrid DC-DC...

  13. Triple voltage dc-to-dc converter and method

    Science.gov (United States)

    Su, Gui-Jia

    2008-08-05

    A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

  14. Plasmon-assisted quantum control of distant emitters

    Energy Technology Data Exchange (ETDEWEB)

    Susa, Cristian E. [Departamento de Física, Universidad del Valle, A.A. 25360, Cali (Colombia); Reina, John H., E-mail: john.reina@correounivalle.edu.co [Departamento de Física, Universidad del Valle, A.A. 25360, Cali (Colombia); Departamento de Óptica, Facultad de Física, Universidad Complutense, 28040 Madrid (Spain); Hildner, Richard [Experimentalphysik IV, Universität Bayreuth, Universitätsstrasse 30, 95447 Bayreuth (Germany)

    2014-06-27

    We show how to generate and control the correlations in a set of two distant quantum emitters coupled to a one-dimensional dissipative plasmonic waveguide. An external laser field enhances the dimer's steady-state correlations and allows an active control (switching on/off) of nonclassical correlations. The plasmon-assisted dipolar-interacting qubits exhibit persistent correlations, which in turn can be decoupled and made to evolve independently from each other. The setup enables long-distance (∼1 μm) qubit control that works for both resonant and detuned emitters. For suitable emitter initialization, we also show that the quantum correlation is always greater than the classical one. - Highlights: • Experimentally realistic setup: single emitters coupled to plasmon waveguide. • Conditional dynamics and qubit control of quantum emitters at long (>μm) distance. • Quantum mechanism: plasmon-assisted qubit coupling and driving by laser field. • Quantum discord dominates induced conditional dynamics. • Long-range quantum mechanism effective for both resonant and detuned emitters.

  15. Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter

    Science.gov (United States)

    Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos

    2015-11-01

    This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.

  16. Electromagnetic compatibility of implantable neurostimulators to RFID emitters.

    Science.gov (United States)

    Pantchenko, Oxana S; Seidman, Seth J; Guag, Joshua W; Witters, Donald M; Sponberg, Curt L

    2011-06-09

    The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz. The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters.

  17. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    Science.gov (United States)

    2011-01-01

    Background The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters. PMID:21658266

  18. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    Directory of Open Access Journals (Sweden)

    Guag Joshua W

    2011-06-01

    Full Text Available Abstract Background The objective of this study is to investigate electromagnetic compatibility (EMC of implantable neurostimulators with the emissions from radio frequency identification (RFID emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters.

  19. Bi-Directional DC-DC Converter for PHEV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  20. Introduction to electrical power and power electronics

    CERN Document Server

    Patel, Mukund R

    2012-01-01

    Power Generation, Distribution, and Utilization AC Power Fundamentals Common Aspects of Power Equipments AC Generator AC and DC Motors Transformer Power Cable Power Distribution Fault Current Analysis System ProtectionEconomic Use of PowerElectrochemical BatteryPower Electronics and Motor Drives Power Electronics Devices DC-DC Converters AC-DC-AC Converters Variable-Frequency Drives Quality of Power Power Converter CoolingAppendixIndex

  1. Conceptual Design of an Insertion Device for Non-Destructive Beam Diagnostics of a Low-Emittance Synchrotron Light Source

    CERN Document Server

    Masaki, Mitsuhiro

    2005-01-01

    An insertion device is proposed to measure small vertical angular divergence and energy spread (dE/E) of electron beam in a low-emittance synchrotron light source. In accelerators such as the SPring-8 storage ring operated on the small emittance-coupling ratio, vertical divergence of spectral photon flux produced by electron beam in a conventional undulator of several meters long will be dominated by natural divergence of the undulator radiation. Therefore, the divergence of spectral flux is not useful for vertical emittance diagnostics. The proposed insertion device consists of N short undulator sections as x-ray radiators cascaded through vertical deflective sections to make a half-period cosine-like electron trajectory. Two radiation parts of the upper and lower sides are formed due to up-and-down electron orbit by the deflective sections. X-rays emitted from the two radiation parts interfere at observation point far from the insertion device. It was numerically studied that the vertical angular divergence...

  2. Improved DC Gun and Insulator Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, Michael [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-01-11

    Many user facilities such as synchrotron radiation light sources and free electron lasers rely on DC high voltage photoguns with internal field gradients as high as 10 to 15 MV/m. These high gradients often lead to field emission which poses serious problems for the photocathode used to generate the electron beam and the ceramic insulators used to bias the photocathode at high voltage. Ceramic insulators are difficult to manufacture, require long commissioning times, and have poor reliability, in part because energetic electrons bury themselves in the ceramic causing a buildup of charge and eventual puncture, and also because large diameter ceramics are difficult to braze reliably. The lifetimes of photo cathodes inside high current DC guns exhibiting field emission are limited to less than a hundred hours. Reducing the surface gradients on the metals reduces the field emission, which serves to maintain the required ultrahigh vacuum condition. A novel gun design with gradients around 5 MV/m and operating at 350 kV, a major improvement over existing designs, was proposed that allows for the in-situ replacement of photo cathodes in axially symmetric designs using inverted ceramics. In this project, the existing JLAB CEBAF asymmetric gun design with an inverted ceramic support was modeled and the beam dynamics characterized. An improved structure was designed that reduces the surface gradients and improves the beam optics. To minimize the surface gradients, a number of electrostatic gun designs were studied to determine the optimum configuration of the critical electrodes within the gun structure. Coating experiments were carried out to create a charge dissipative coating for cylindrical ceramics. The phase II proposal, which was not granted, included the design and fabrication of an axially symmetric DC Gun with an inverted ceramic that would operate with less than 5 MV/m at 350 kV and would be designed with an in-situ replaceable photo-cathode.

  3. Software Tools for Emittance Measurement and Matching for 12 GeV CEBAF

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Dennis L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    This paper discusses model-driven setup of the Continuous Electron Beam Accelerator Facility (CEBAF) for the 12GeV era, focusing on qsUtility. qsUtility is a set of software tools created to perform emittance measurements, analyze those measurements, and compute optics corrections based upon the measurements.qsUtility was developed as a toolset to facilitate reducing machine configuration time and reproducibility by way of an accurate accelerator model, and to provide Operations staff with tools to measure and correct machine optics with little or no assistance from optics experts.

  4. Performance of InP/InGaAs HBTs with a Thin Highly N-Type Doped Layer in the Emitter-Base Heterojunction Vicinity

    Science.gov (United States)

    Kurishima, Kenji; Ida, Minoru; Kashio, Norihide; K. Fukai, Yoshino

    This paper investigates the effects of n-type doping in the emitter-base heterojunction vicinity on the DC and high-frequency characteristics of InP/InGaAs heterojunction bipolar transistors (HBTs). The n-type doping is shown to be very effective for enhancing the tunneling-injection current from the emitter and thus for reducing the collector-current turn-on voltage. However, it is also revealed that an unnecessary increase in the doping level only degrades the current gain, especially in the low-current region. A higher doping level also increases the emitter junction capacitance. The optimized HBT structures with a 0.5-µm-wide emitter exhibit turn-on voltage as low as 0.78V and current gain of around 80 at JC =1mA/µm2. They also provide a current-gain cutoff frequency, ft, of 280GHz and a maximum oscillation frequency, fmax, of 385GHz at VCE =1V and JC =3mA/µm2. These results indicate that the proposed HBTs are very useful for high-speed and low-power IC applications.

  5. Classification of electrical discharges in DC Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Srutarshi, E-mail: sruban.stephens@gmail.com [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Deb, A.K. [Department of Electrical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Rajan, Rehim N. [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kishore, N.K. [Department of Electrical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2016-08-11

    Controlled electrical discharge aids in conditioning of the system while uncontrolled discharges damage its electronic components. DC Accelerator being a high voltage system is no exception. It is useful to classify electrical discharges according to the severity. Experimental prototypes of the accelerator discharges are developed. Photomultiplier Tubes (PMTs) are used to detect the signals from these discharges. Time and Frequency domain characteristics of the detected discharges are used to extract features. Machine Learning approaches like Fuzzy Logic, Neural Network and Least Squares Support Vector Machine (LSSVM) are employed to classify the discharges. This aids in detecting the severity of the discharges.

  6. Tunable graphene dc superconducting quantum interference device.

    Science.gov (United States)

    Girit, Caglar; Bouchiat, V; Naaman, O; Zhang, Y; Crommie, M F; Zettl, A; Siddiqi, I

    2009-01-01

    Graphene exhibits unique electrical properties on account of its reduced dimensionality and "relativistic" band structure. When contacted with two superconducting electrodes, graphene can support Cooper pair transport, resulting in the well-known Josephson effect. We report here the fabrication and operation of a two junction dc superconducting quantum interference device (SQUID) formed by a single graphene sheet contacted with aluminum/palladium electrodes in the geometry of a loop. The supercurrent in this device can be modulated not only via an electrostatic gate but also by an applied magnetic fielda potentially powerful probe of electronic transport in graphene and an ultrasensitive platform for nanomagnetometry.

  7. Classification of electrical discharges in DC Accelerators

    Science.gov (United States)

    Banerjee, Srutarshi; Deb, A. K.; Rajan, Rehim N.; Kishore, N. K.

    2016-08-01

    Controlled electrical discharge aids in conditioning of the system while uncontrolled discharges damage its electronic components. DC Accelerator being a high voltage system is no exception. It is useful to classify electrical discharges according to the severity. Experimental prototypes of the accelerator discharges are developed. Photomultiplier Tubes (PMTs) are used to detect the signals from these discharges. Time and Frequency domain characteristics of the detected discharges are used to extract features. Machine Learning approaches like Fuzzy Logic, Neural Network and Least Squares Support Vector Machine (LSSVM) are employed to classify the discharges. This aids in detecting the severity of the discharges.

  8. Step-Up DC-DC Power Converter

    DEFF Research Database (Denmark)

    2015-01-01

    capacitor coupled between the positive and negative input terminals and the secondary side circuit comprises an output capacitor chargeable to a converter output voltage between a first positive electrode and a second negative electrode. A switched energy storage network is configured for alternatingly...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic......The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...

  9. Active pre-filters for dc/dc Boost regulators

    Directory of Open Access Journals (Sweden)

    Carlos Andrés Ramos-Paja

    2014-05-01

    Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.

  10. Fuzzy Control of DC-DC Converters with Input Constraint

    Directory of Open Access Journals (Sweden)

    D. Saifia

    2012-01-01

    Full Text Available This paper proposes a method for designing fuzzy control of DC-DC converters under actuator saturation. Because linear control design methods do not take into account the nonlinearity of the system, a T-S fuzzy model and a controller design approach is used. The designed control not only handles the external disturbance but also the saturation of duty cycle. The input constraint is first transformed into a symmetric saturation which is represented by a polytopic model. Stabilization conditions for the state feedback system of DC-DC converters under actuator saturation are established using the Lyapunov approach. The proposed method has been compared and verified with a simulation example.

  11. Decentralized Interleaving of Paralleled Dc-Dc Buck Converters

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sinha, Mohit [University of Minnesota; Dhople, Sairaj [University of Minnesota; Poon, Jason [University of California at Berkeley

    2017-08-21

    We present a decentralized control strategy that yields switch interleaving among parallel-connected dc-dc buck converters. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform and no communication between different controllers is needed. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work presents the first fully decentralized strategy for switch interleaving in paralleled dc-dc buck converters.

  12. Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sinha, Mohit [University of Minnesota; Dhople, Sairaj [University of Minnesota; Poon, Jason [University of California at Berkeley

    2017-09-01

    We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy for switch interleaving of paralleled dc-dc buck converters.

  13. RESONANT STEP-DOWN DC-DC POWER CONVERTERS

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant step-down DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage...... charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short......-circuit connection across the galvanic isolation barrier connecting, in a first case, the second negative electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal...

  14. DC-Compensated Current Transformer.

    Science.gov (United States)

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-20

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

  15. Highly efficient non-doped deep blue fluorescent emitters with horizontal emitting dipoles using interconnecting units between chromophores.

    Science.gov (United States)

    Kim, Kwon-Hyeon; Baek, Jang Yeol; Cheon, Chan Woo; Moon, Chang-Ki; Sim, Bomi; Choi, Myeong Yong; Kim, Jang-Joo; Kim, Yun-Hi

    2016-09-21

    New deep blue fluorescent emitters composed of anthracene as an electron rich unit, a diphenyltriazine as a strong electron acceptor unit, and phenyl or xylene as interconnecting units were synthesised. The interconnecting unit between chromophores increased the singlet transition energy and the ratio of horizontal emitting dipoles. As a result, a non-doped blue fluorescent organic light-emitting diode (OLED) using a new emitter was demonstrated, with an external quantum efficiency (EQE) of 6.6% and Commision Internationale de l'Eclairage (CIE) colour coordinates of (0.145, 0.068). This device performance has been the highest EQE observed in deep blue non-doped OLEDs with CIE coordinates less than (0.145, 0.068) to date.

  16. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  17. DSm Evidence Modeling and Radar Emitter Fusion Recognition Method Based on Cloud Model DSm Evidence Modeling and Radar Emitter Fusion Recognition Method Based on Cloud Model

    OpenAIRE

    Guo, Qiang; He, You

    2015-01-01

    To improve the correct radar emitter recognition rate in cases that radar emitter characteristic parameters are overlapped with each other and existence of multiple modes, a DSm (Dezert-Smarandache) evidence modeling and radar emitter fusion recognition method based on cloud model is proposed.

  18. Digital Control Technologies for Modular DC-DC Converters

    Science.gov (United States)

    Button, Robert M.; Kascak, Peter E.; Lebron-Velilla, Ramon

    2002-01-01

    Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.

  19. Isolated step-down DC -DC converter for electric vehicles

    Science.gov (United States)

    Kukovinets, O. V.; Sidorov, K. M.; Yutt, V. E.

    2018-02-01

    Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.

  20. Emittance and Phase Space Tomography for the Fermilab Linac

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, F.G.G.; Johnstone, C.; Kobilarcik, T.; Koizumi, G.M.; Moore, C.D.; /Fermilab; Newhart, D.L.; /Fermilab

    2012-05-01

    The Fermilab Linac delivers a variable intensity, 400-MeV beam to the MuCool Test Area experimental hall via a beam line specifically designed to facilitate measurements of the Linac beam emittance and properties. A 10 m, dispersion-free and magnet-free straight utilizes an upstream quadrupole focusing triplet in combination with the necessary in-straight beam diagnostics to fully characterize the transverse beam properties. Since the Linac does not produce a strictly elliptical phase space, tomography must be performed on the profile data to retrieve the actual particle distribution in phase space. This is achieved by rotating the phase space distribution using different waist focusing conditions of the upstream triplet and performing a deconvolution of the profile data. Preliminary measurements using this diagnostic section are reported here. These data represent a first-pass measurement of the Linac emittance based on various techniques. It is clear that the most accurate representation of the emittance is given by the 3-profile approach. Future work will entail minimizing the beam spot size on MW5 to test and possibly improve the accuracy of the 2-profile approach. The 95% emittance is {approx} 18{pi} in the vertical and {approx} 13{pi} in the horizontal, which is especially larger than anticipated - 8-10{pi} was expected. One possible explanation is that the entire Linac pulse is extracted into the MTA beamline and during the first few microseconds, the feed forward and RF regulation are not stable. This may result in a larger net emittance observed versus beam injected into Booster, where the leading part of the Linac beam pulse is chopped. Future studies will clearly entail a measurement of the emittance vs. pulse length. One additional concern is that the Linac phase space is most likely aperture-defined and non-elliptical in nature. A non-elliptical phase-space determination would require a more elaborate analysis and provide another explanation of the

  1. DC Microgrids – Part I

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez

    2016-01-01

    This paper presents a review of control strategies, stability analysis and stabilization techniques for DC microgrids (MGs). Overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level. As opposed to local control...

  2. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Yong, X.

    2000-01-01

    Duration Calculus (DC) is an interval-based real-time logic, which can be used in capturing and eliciting users' real-time requirements. The Timed RAISE Specification Language (TRSL) is an extension of the RAISE Specification Language with real-time features. This paper links DC and TRSL together...... approach for linking state-based real-time logics together with event-based, timed process algebra languages....

  3. Transverse emittance measurement and preservation at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Maria

    2016-06-20

    The Large Hadron Collider (LHC) at CERN is a high energy storage ring that provides proton and heavy ion collisions to study fundamental particle physics. The luminosity production is closely linked to emittance preservation in the accelerator. The transverse emittance is the phase space density of the beam and should be conserved when the particle beam is transformed through the accelerator. Perturbing effects, however, can lead to emittance increase and hence luminosity degradation. Measuring the emittance growth is a complex task with high intensity beams and changing energies. The machine optics and the transverse beam size have to be measured as accurately as possible. Beta function measurements with k-modulation are discussed. With this method the quadrupole focussing strength is varied and the resulting tune change is traced to determine the beta function at the quadrupole. A new k-modulation measurement tool was developed for the LHC. The fully automatic and online measurement system takes constraints of various systems such as tune measurement precision and powering limitations of the LHC superconducting circuits into account. With sinusoidal k-modulation record low beta function measurement uncertainties in the LHC have been reached. 2015 LHC beta function and β*, which is the beta function at the collision point, measurements with k-modulation will be presented. Wire scanners and synchrotron light monitors are presently used in the LHC to measure the transverse beam size. Accuracy and limitations of the LHC transverse profile monitors are discussed. During the 2012 LHC proton run it was found that wire scanner photomultiplier saturation added significant uncertainty on all measurements. A large discrepancy between emittances from wire scanners and luminosity was discovered but not solved. During Long Shutdown 1 the wire scanner system was upgraded with new photomultipliers. A thorough study of LHC wire scanner measurement precision in 2015 is presented

  4. Analytical solution for irradiance due to inhomogeneous Lambertian polygonal emitters.

    Science.gov (United States)

    Chen, Min; Arvo, James

    2003-05-01

    We present an analytic solution for the irradiance at a point due to a polygonal Lambertian emitter with radiant exitance that varies with position according to a polynomial of arbitrary degree. This is a basic problem that arises naturally in radiative transfer and more specifically in global illumination, a subfield of computer graphics. Our solution is closed form except for a single nonalgebraic special function known as the Clausen integral. We begin by deriving several useful formulas for high-order tensor analogs of irradiance, which are natural generalizations of the radiation pressure tensor. We apply the resulting tensor formulas to linearly varying emitters, obtaining a solution that exhibits the general structure of higher-degree cases, including the dependence on the Clausen integral. We then generalize to higher-degree polynomials with a recurrence formula that combines solutions for lower-degree polynomials; the result is a generalization of Lambert's formula for homogeneous diffuse emitters, a well-known formula with many applications in radiative transfer and computer graphics. Similar techniques have been used previously to derive closed-form solutions for the irradiance due to homogeneous polygonal emitters with directionally varying radiance. The present work extends this previous result to include inhomogeneous emitters, which proves to be significantly more challenging to solve in closed form. We verify our theoretical results with numerical approximations and briefly discuss their potential applications.

  5. InterProScan Result: DC565078 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available DC565078 DC565078_4_ORF1 7A3C29E0C70FDCFD PRINTS PR00385 P450 2.1e-08 T IPR001128 Cytochrome P450 Molecular... Function: monooxygenase activity (GO:0004497)|Molecular Function: iron ion binding (GO:0005506)|Molecular... Function: electron carrier activity (GO:0009055)|Molecular Function: heme binding (GO:0020037) ...

  6. InterProScan Result: DC530232 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available DC530232 DC530232_3_ORF2 7F2C76CC75E1A858 PFAM PF00067 p450 1.3e-23 T IPR001128 Cytochrome P450 Molecular... Function: monooxygenase activity (GO:0004497)|Molecular Function: iron ion binding (GO:0005506)|Molecular... Function: electron carrier activity (GO:0009055)|Molecular Function: heme binding (GO:0020037) ...

  7. InterProScan Result: DC547271 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available DC547271 DC547271_3_ORF1 0A2629B380B6CC73 PRINTS PR00385 P450 5.1e-13 T IPR001128 Cytochrome P450 Molecular... Function: monooxygenase activity (GO:0004497)|Molecular Function: iron ion binding (GO:0005506)|Molecular... Function: electron carrier activity (GO:0009055)|Molecular Function: heme binding (GO:0020037) ...

  8. InterProScan Result: DC553750 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available DC553750 DC553750_3_ORF1 E7404E2C0B422C6A PFAM PF00067 p450 5.7e-11 T IPR001128 Cytochrome P450 Molecular... Function: monooxygenase activity (GO:0004497)|Molecular Function: iron ion binding (GO:0005506)|Molecular... Function: electron carrier activity (GO:0009055)|Molecular Function: heme binding (GO:0020037) ...

  9. InterProScan Result: DC565078 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available DC565078 DC565078_4_ORF1 7A3C29E0C70FDCFD PFAM PF00067 p450 4.5e-35 T IPR001128 Cytochrome P450 Molecular... Function: monooxygenase activity (GO:0004497)|Molecular Function: iron ion binding (GO:0005506)|Molecular... Function: electron carrier activity (GO:0009055)|Molecular Function: heme binding (GO:0020037) ...

  10. InterProScan Result: DC547271 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available DC547271 DC547271_3_ORF1 0A2629B380B6CC73 PFAM PF00067 p450 1.4e-64 T IPR001128 Cytochrome P450 Molecular... Function: monooxygenase activity (GO:0004497)|Molecular Function: iron ion binding (GO:0005506)|Molecular... Function: electron carrier activity (GO:0009055)|Molecular Function: heme binding (GO:0020037) ...

  11. Research on ripple rejection of DC power supply based on dual pulse width modulation

    Science.gov (United States)

    Liu, Xin; Liu, Peiyi

    2017-08-01

    With the development of power electronics technology, how to improve the output quality of DC power supply has become an important subject of recent scholars’ research. This paper put forward a new PWM control mode, the DC power supply output ripple is effectively suppressed. The theoretical basis is given by the principle analysis. Finally, the accuracy of the theoretical analysis is verified by simulation.

  12. Intelligent Control for a DC Micro-Grid System

    DEFF Research Database (Denmark)

    Martino, Michele; Quiñones, Yamshid Farhat; Raboni, Pietro

    2012-01-01

    This paper presents the dynamic response of a DC–micro-grid (DC-MG) controlled in master-slave mode. The benefits of the micro-grids (MGs) are the low cost in terms of power electronics converters and the high reliability and quality, even in case of loss connection to the transmission system. A ...

  13. Thickness effect on properties of titanium film deposited by dc ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 5. Thickness effect on properties of titanium film deposited by d.c. magnetron sputtering and electron beam evaporation techniques. Nishat Arshi Junqing Lu Chan Gyu Lee Jae Hong Yoon Bon Heun Koo Faheem Ahmed. Volume 36 Issue 5 October 2013 pp ...

  14. Optical properties of dc magneto sputtered tantalum and titanium ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 33; Issue 5. Optical properties of d.c. magneto sputtered ... Large changes in both transmission and absorption on loading these films with hydrogen are accompanied by significant phase changes and electronic transformation. Optical photograph shows the colour ...

  15. A brushless dc spin motor for momentum exchange altitude control

    Science.gov (United States)

    Stern, D.; Rosenlieb, J. W.

    1972-01-01

    Brushless dc spin motor is designed to use Hall effect probes as means of revolving rotor position and controlling motor winding currents. This results in 3 to 1 reduction in watt-hours required for wheel acceleration, a 2 to 1 reduction in power to run wheel, and a 10 to 1 reduction in the electronics size and weight.

  16. Conductivity of Graphene Nanoribbon Affected by DC Electric Field

    Science.gov (United States)

    Konobeev, N. N.; Belonenko, M. B.

    2018-01-01

    The paper focuses on the calculation of the density of states based on the electron hopping Hamiltonian of graphene using the direct Hamiltonian diagonalization. The density of states is then recalculated into the tunneling current arising between graphene nanoribbon and contact metal. It is shown that the dc electric field applied in parallel to the nanoribbon plane modifies the properties of the tunneling current.

  17. DC drive system for cine/pulse cameras

    Science.gov (United States)

    Gerlach, R. H.; Sharpsteen, J. T.; Solheim, C. D.; Stoap, L. J.

    1977-01-01

    Camera-drive functions are separated mechanically into two groups which are driven by two separate dc brushless motors. First motor, a 90 deg stepper, drives rotating shutter; second electronically commutated motor drives claw and film transport. Shutter is made of one piece but has two openings for slow and fast exposures.

  18. GaN-based High Efficiency Bidirectional DC-DC Converter with 10 MHz Switching Frequency

    DEFF Research Database (Denmark)

    Kruse, Kristian; Zhang, Zhe; Elbo, Mads

    2017-01-01

    -isolated bidirectional DC-DC converter equipped with Gallium Nitride (GaN) semiconductor transistors is presented. The converter’s operation principles, zero-voltage switching (ZVS) constraints and dead-time effects are studied. Moreover, the optimization and tradeoffs on the adopted high-frequency inductor......Wide bandgap (WBG) semiconductor devices allow power electronic converters to achieve higher efficiency, higher power density and potentially higher reliability. However, the design challenges accompanied by applying the new WBG devices have risen accordingly. In this paper, a non...... are investigated. Based on the theoretical analysis and calculation, a laboratory prototype with a switching frequency up to 10 MHz and the maximum output power of 100 W is constructed and tested. Switching at 10 MHz, a power density of approximately 6.25W/cm3 and an efficiency of 94.4% in the Buck mode...

  19. Planar Integrated Magnetics (PIM) Module in Hybrid Bidirectional DC-DC Converter for Fuel Cell Application

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Zhang, Zhe; Thomsen, Ole Cornelius

    2011-01-01

    , hereby increasing the power density of converters. In this paper, a new planar integrated magnetics (PIM) module for a phase-shift plus duty cycle controlled hybrid bi-directional dc-dc converter is proposed, which assembles one boost inductor and two transformers into an E-I-E core geometry, reducing......In most power electronics converters, the overall volume is mainly determined by the number of parts and the size of passive components. Integrated magnetics and planar magnetics techniques therefore have been an excellent option in order to reduce the counts and the size of magnetic components...... the number of parts, the total volume of converter, as well as the total core loss of the magnetic components. AC losses in the windings and leakage inductance of the transformers are kept low by interleaving the primary and secondary turns of the transformers. To verify the validity of the design approach...

  20. Conventional control and fuzzy control of a dc-dc converter for machine drive

    Energy Technology Data Exchange (ETDEWEB)

    Radoi, C.; Florescu, A. [Department of Power Electronics `Politecnica` University Bucharest (Romania)

    1997-12-31

    Fuzzy logic or fuzzy set theory is recently getting increasing emphasis in process control applications. The paper describes an application of fuzzy logic in speed control system that uses a dc-dc converter. The fuzzy control is used to linearize the family of external characteristics of the converter in discontinuous-conduction mode occurring at light load and/or high speed. In order to compare the conventional control with the fuzzy logic control, algorithms have been developed in detail and verified by Microsoft Excel simulation. The simulation study indicates that fuzzy control is a good alternative for conventional control methods, being used particularly in non-linear complex systems ill defined or totally unknown. Where the mathematical model exists, it is useful. The applications of fuzzy set theory in power electronics are almost entirely new; fuzzy logic seems to have a lot of premises in the large industrial control field. (orig.) 2 refs.

  1. Laser Process for Selective Emitter Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    G. Poulain

    2012-01-01

    Full Text Available Selective emitter solar cells can provide a significant increase in conversion efficiency. However current approaches need many technological steps and alignment procedures. This paper reports on a preliminary attempt to reduce the number of processing steps and therefore the cost of selective emitter cells. In the developed procedure, a phosphorous glass covered with silicon nitride acts as the doping source. A laser is used to open locally the antireflection coating and at the same time achieve local phosphorus diffusion. In this process the standard chemical etching of the phosphorous glass is avoided. Sheet resistance variation from 100 Ω/sq to 40 Ω/sq is demonstrated with a nanosecond UV laser. Numerical simulation of the laser-matter interaction is discussed to understand the dopant diffusion efficiency. Preliminary solar cells results show a 0.5% improvement compared with a homogeneous emitter structure.

  2. High efficiency and stable white OLED using a single emitter

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian [Arizona State Univ., Tempe, AZ (United States). School of Mechanical, Aerospace, Chemical and Materials Engineering

    2016-01-18

    The ultimate objective of this project was to demonstrate an efficient and stable white OLED using a single emitter on a planar glass substrate. The focus of the project is on the development of efficient and stable square planar phosphorescent emitters and evaluation of such class of materials in the device settings. Key challenges included improving the emission efficiency of molecular dopants and excimers, controlling emission color of emitters and their excimers, and improving optical and electrical stability of emissive dopants. At the end of this research program, the PI has made enough progress to demonstrate the potential of excimer-based white OLED as a cost-effective solution for WOLED panel in the solid state lighting applications.

  3. A polarization-insensitive plasmonic photoconductive terahertz emitter

    KAUST Repository

    Li, Xurong

    2017-11-16

    We present a polarization-insensitive plasmonic photoconductive terahertz emitter that uses a two-dimensional array of nanoscale cross-shaped apertures as the plasmonic contact electrodes. The geometry of the cross-shaped apertures is set to maximize optical pump absorption in close proximity to the contact electrodes. The two-dimensional symmetry of the cross-shaped apertures offers a polarization-insensitive interaction between the plasmonic contact electrodes and optical pump beam. We experimentally demonstrate a polarization-insensitive terahertz radiation from the presented emitter in response to a femtosecond optical pump beam and similar terahertz radiation powers compared to previously demonstrated polarization-sensitive photoconductive emitters with plasmonic contact electrode gratings at the optimum optical pump polarization.

  4. Control and Data Analysis for Emittance Measuring Devices

    CERN Document Server

    Hoffmann, T

    2001-01-01

    Due to the wide range of heavy ion beam intensities and energies in the GSI linac and the associated transfer channel to the synchrotron, several different types of emittance measurement systems have been established. Many common devices such as slit/grid or dipole-sweep systems are integrated into the GSI control system. Other systems like the single shot pepper pot method using CCD-cameras or stand-alone slit/grid set-ups are connected to personal computers. An overview is given about the various systems and their software integration. Main interest is directed on the software development for emittance front-end control and data analysis such as evaluation algorithms or graphical presentation of the results. In addition, special features for improved usability of the software such as data export, project databases and automatic report generation will be presented. An outlook on a unified evaluation procedure for all different types of emittance measurement is given.

  5. Optical characterization of OLED emitter properties by radiation pattern analyses

    Energy Technology Data Exchange (ETDEWEB)

    Flaemmich, Michael

    2011-09-08

    Researches in both, academia and industry are investigating optical loss channels in OLED layered systems by means of optical simulation tools in order to derive promising concepts for a further enhancement of the overall device performance. Besides other factors, the prospects of success of such optimization strategies rely severely on the credibility of the optical input data. The present thesis provides a guideline to measure the active optical properties of OLED emitter materials in situ by radiation pattern analyses. Reliable and widely applicable methods are introduced to determine the internal electroluminescence spectrum, the profile of the emission zone, the dipole emitter orientation, and the internal luminescence quantum efficiency of emissive materials from the optical far field emission of OLEDs in electrical operation. The proposed characterization procedures are applied to sets of OLEDs containing both, fluorescent polymeric materials as well as phosphorescent small-molecular emitters, respectively. On the one hand, quite expected results are obtained. On the other hand, several novel and truly surprising results are found. Most importantly, this thesis contains the first report of a non-isotropic, mainly parallel emitter orientation in a phosphorescent small-molecular guest-host system (Ir(MDQ)2(acac) in a-NPD). Due to the latter result, emitter orientation based optimization of phosphorescent OLEDs seems to be within reach. Since parallel dipoles emit preferably into air, the utilization of smart emissive materials with advantageous molecular orientation is capable to boost the efficiency of phosphorescent OLEDs by 50%. Materials design, the influence of the matrix material and the substrate, as well as film deposition conditions are just a few parameters that need to be studied further in order to exploit the huge potential of the dipole emitter orientation in phosphorescent OLEDs.

  6. High-efficiency photonic crystal narrowband thermal emitters

    Science.gov (United States)

    Farfan, G. B.; Su, M. F.; Reda Taha, M. M.; El-Kady, I.

    2010-02-01

    Photonic crystals (PhC) are artificial structures fabricated with a periodicity in the dielectric function. This periodic electromagnetic potential results in creation of energy bandgaps where photon propagation is prohibited. PhC structures have promising use in thermal applications if optimized to operate at specific thermal emission spectrum. Here, novel utilization of optimized PhC's in thermal applications is presented. We demonstrate through numerical simulation the modification of the thermal emission spectrum by a metallic photonic crystal (PhC) to create high-efficiency multispectral thermal emitters. These emitters funnel radiation from a broad emission spectrum associated with a Plancklike distribution into a prescribed narrow emission band. A detailed quantitative evaluation of the spectral and power efficiencies of a PhC thermal emitter and its portability across infrared (IR) spectral bands are provided. We show an optimized tungsten PhC with a predominant narrow-band emission profile with an emitter efficiency that is more than double that of an ideal blackbody and ~65-75% more power-efficiency across the IR spectrum. We also report on using optimal three-dimensional Lincoln log photonic crystal (LL-PhC) emitters for thermophotovoltaic (TPV) generation as opposed to using a passive filtering approach to truncate the broadband thermal source emission to match the bandgap of a photovoltaic (PV) cell. The emitter performance is optimized for the 1-2μm PV band using different PhC materials, specifically copper, silver and gold. The use of the proposed PhC in TPV devices can produce significant energy savings not reported before. The optimal design of the PhC geometry is obtained by implementing a variety of optimization methods integrated with artificial intelligence (AI) algorithms.

  7. Atmel Microcontroller Based Soft Switched PWM ZVS Full Bridge DC to DC Converter

    Directory of Open Access Journals (Sweden)

    DEEPAK KUMAR NAYAK

    2010-12-01

    Full Text Available This paper deals with the simulation and implementation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Later it is rectified using a full wave rectifier. Laboratory model of microcontroller based DC to DC converter is fabricated and tested. The experimental results are compared with the simulation results.

  8. Pyrometric method for measuring emittances at high temperatures

    Science.gov (United States)

    Ballestrín, J.; Rodríguez, J.; Carra, M. E.; Cañadas, I.; Roldan, M. I.; Barbero, J.; Marzo, A.

    2016-05-01

    In this work an alternative method for emittance determination based on pyrometric measurements is presented. The measurement procedure has been applied to AISI 310S steel samples in the Plataforma Solar de Almería vertical axis solar furnace SF5. The experimental results show that emittance increases with increasing temperature and decreases with increasing wavelength. This behaviour is in agreement with experimental results obtained by other authors. Analysis of tests has revealed a good repeatability (1%) and accuracy (< 2%) of this measurement procedure.

  9. Spectrum of classes of point emitters of electromagnetic wave fields.

    Science.gov (United States)

    Castañeda, Román

    2016-09-01

    The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

  10. Nanodiamonds with photostable, sub-gigahertz linewidth quantum emitters

    Science.gov (United States)

    Tran, Toan Trong; Kianinia, Mehran; Bray, Kerem; Kim, Sejeong; Xu, Zai-Quan; Gentle, Angus; Sontheimer, Bernd; Bradac, Carlo; Aharonovich, Igor

    2017-11-01

    Single-photon emitters with narrow linewidths are highly sought after for applications in quantum information processing and quantum communications. In this letter, we report on a bright, highly polarized near infrared single photon emitter embedded in diamond nanocrystals with a narrow, sub-GHz optical linewidth at 10 K. The observed zero-phonon line at ˜780 nm is optically stable under low power excitation and blue shifts as the excitation power increases. Our results highlight the prospect for using new near infrared color centers in nanodiamonds for quantum applications.

  11. Very High Frequency Half Bridge DC/DC Converter

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents the first, off chip, class DE (resonant half bridge) converter working in the Very High Frequency (VHF) range. The benefits of using half bridge circuits both in the inverter and rectifier part of a VHF resonant dc/dc converter are analyzed and design equations for all...... components in the power stage are given. The circuit has been simulated to verify the accuracy of the presented equations and an efficiency of 89% has been shown. A prototype has been implemented with self-oscillating resonant gate drives driving the switches. The prototype has been used to drive an LED...

  12. A SOFT SWITCHED INTERLEAVED HIGH GAIN DC-DC CONVERTER

    Directory of Open Access Journals (Sweden)

    SHESHIDHAR REDDY ADDULA

    2017-09-01

    Full Text Available In this paper, a novel soft-switched interleaved DC-DC converter which provides a high voltage gain of 12 is proposed. Voltage gain of the basic interleaved boost converter is extended by using diode-capacitor multiplier (DCM cells. The switches are operated at a nominal duty ratio of 0.5. The voltage stress on the power switches and diodes is only a fraction of the output voltage. To enhance the operating power conversion efficiency, the switches are turned ON at zero voltage condition. Experimental results of 18-216V, 100W prototype converter validate the operating principle and the advantageous features of the presented converter.

  13. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification...... is carried out by comparing the calculation results with detailed time domain simulation results. With the droop parameters as variables in the power flow analysis, their effects on power sharing and secondary voltage regulation can now be analytically studied, and specialized optimization in the upper level...... control can also be made accordingly. Case studies on power sharing and secondary voltage regulation are carried out using proposed power flow analysis....

  14. Light-weight DC to very high voltage DC converter

    Science.gov (United States)

    Druce, R.L.; Kirbie, H.C.; Newton, M.A.

    1998-06-30

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current. 1 fig.

  15. Feasibility Study of Schottky Emitter Arrays

    NARCIS (Netherlands)

    Dokania, A.K.

    2010-01-01

    In this thesis an attempt is made to make a step forward in the development of next a generation scanning electron lithography machine for sub 25nm chip making. One of the challenges for such a system is to have sufficient beam-lets with enough current for parallel writing which requires a

  16. A voltage control method for an active capacitive DC-link module with series-connected circuit

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai; Blaabjerg, Frede

    2017-01-01

    capacitive DC-link module is proposed. Current sensor at the DC-link will be cancel from the circuit. The controller of the series-connected circuit requires internal voltage signals of the DC-link module only, making it possible to be fully independent without any additional connection to the main circuit......Many efforts have been made to improve the performance of power electronic systems with active capacitive DC-link module in terms of power density as well as reliability. One of the attractive solution is an active capacitive DC-link with the series-connected circuit because of handling small...

  17. Half-life measurements for neutral and highly-charged {alpha}-emitters

    Energy Technology Data Exchange (ETDEWEB)

    Farinon, Fabio [GSI, Darmstadt (Germany); Justus-Liebig Universitaet, Giessen (Germany); Collaboration: E073-Collaboration

    2012-07-01

    The influence of the bound electron cloud on the {alpha}-decay constant {lambda} has been discussed theoretically since the late 50s. Tiny changes in Q-values and {alpha}-decay half-lives of fully stripped ions are expected and can provide information on the electron screening energy, thereby deducing reliable reaction rates in stellar environments. Recently, the measurements of {alpha}-decay half-lives are feasible also for highly-charged radioactive nuclides. Using a {sup 238}U beam at relativistic energies at the present FRS-ESR facility at GSI it is possible to produce, efficiently separate and store highly charged {alpha}-emitters. {sup 213}Fr{sup 86+} have been investigated by using the Schottky Mass Spectrometry technique. In order to establish a solid reference data set, lifetime measurements of the corresponding neutral atoms have been performed directly at the FRS by implanting the separated ions into an active silicon stopper. These results are reported.

  18. Scanning-tunneling-spectroscopy-directed design of tailored deep-blue emitters.

    Science.gov (United States)

    Sanning, Jan; Ewen, Pascal R; Stegemann, Linda; Schmidt, Judith; Daniliuc, Constantin G; Koch, Tobias; Doltsinis, Nikos L; Wegner, Daniel; Strassert, Cristian A

    2015-01-12

    Frontier molecular orbitals can be visualized and selectively set to achieve blue phosphorescent metal complexes. For this purpose, the HOMOs and LUMOs of tridentate Pt(II) complexes were measured using scanning tunneling microscopy and spectroscopy. The introduction of electron-accepting or -donating moieties enables independent tuning of the frontier orbital energies, and the measured HOMO-LUMO gaps are reproduced by DFT calculations. The energy gaps correlate with the measured and the calculated energies of the emissive triplet states and the experimental luminescence wavelengths. This synergetic interplay between synthesis, microscopy, and spectroscopy enabled the design and realization of a deep-blue triplet emitter. Finding and tuning the electronic "set screws" at molecular level constitutes a useful experimental method towards an in-depth understanding and rational design of optoelectronic materials with tailored excited state energies and defined frontier-orbital properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne; Yong, Xia

    1999-01-01

    for high-level specifications of real-time requirementsand TRSL for specifying real-time implementations in the form of timed communicating concurrent processes.In order to link DC and TRSL together in a well-founded way, we formally define what it means for a TRSL process to satisfy a DC requirement...... of constraints on the durations of states of the system, i.e. at a high level of abstraction.However, as a state-based logic, it lacks the ability to specifysequential programs and communicating concurrent processes at a concrete level. The Timed RAISE Specification Language (TRSL) [XG99] has this ability.......TRSL is a real-time extension of the RAISE Specification Language (RSL) [Rlg92] which together with its associated method [Rmg95]and tools has shown to be very useful in the industrial development of software systems. Therefore, a promising approach for the development of real-time systemscould be to use DC...

  20. The effects of emitter-tied field plates on lateral PNP ionizing radiation response

    Energy Technology Data Exchange (ETDEWEB)

    Barnaby, H.J.; Schrimpf, R.D.; Cirba, C.R. [Vanderbilt Univ., Nashville, TN (United States); Pease, R.L. [RLP Research, Inc., Albuquerque, NM (United States); Fleetwood, D.M. [Sandia National Labs., Albuquerque, NM (United States); Kosier, S.L. [VTC Inc., Bloomington, MN (United States)

    1998-03-01

    Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps.

  1. A combined emitter threat assessment method based on ICW-RCM

    Science.gov (United States)

    Zhang, Ying; Wang, Hongwei; Guo, Xiaotao; Wang, Yubing

    2017-08-01

    Considering that the tradition al emitter threat assessment methods are difficult to intuitively reflect the degree of target threaten and the deficiency of real-time and complexity, on the basis of radar chart method(RCM), an algorithm of emitter combined threat assessment based on ICW-RCM (improved combination weighting method, ICW) is proposed. The coarse sorting is integrated with fine sorting in emitter combined threat assessment, sequencing the emitter threat level roughly accordance to radar operation mode, and reducing task priority of the low-threat emitter; On the basis of ICW-RCM, sequencing the same radar operation mode emitter roughly, finally, obtain the results of emitter threat assessment through coarse and fine sorting. Simulation analyses show the correctness and effectiveness of this algorithm. Comparing with classical method of emitter threat assessment based on CW-RCM, the algorithm is visual in image and can work quickly with lower complexity.

  2. Exploring potentialities and limitations of stapled o-oligo(phenyleneethynylene)s (o-OPEs) as efficient circularly polarized luminescence emitters.

    Science.gov (United States)

    Reiné, Pablo; Justicia, José; Morcillo, Sara P; Mazzeo, Giuseppe; García-Fernández, Emilio; Rodríguez-Diéguez, Antonio; Álvarez de Cienfuegos, Luis; Abbate, Sergio; Cuerva, Juan M; Longhi, Giovanna; Miguel, Delia

    2018-01-01

    In this paper, we have studied the chiroptical properties of a family of o-oligo(phenyleneethynylene) (o-OPE) derivatives with different steric hindrance. Experimental results show high dissymmetry factors (g abs and g lum up to 1.1 × 10 -2 ) and very similar electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) for all the derivatives that make this basic o-OPE scaffold a robust pure organic emitter. Vibrational circular dichroism spectra are used to characterize conformational properties in solution. Density functional theory and time-dependent density functional theory calculations support experimental results also proving that ECD and CPL are almost exclusively linked to helical moiety and not to size or conformation of substituents. As chiroptical properties of these emitters are independent of substituents, this OPE scaffold can be used as basic skeleton for the design of sensing probes with high CPL efficiencies. © 2017 Wiley Periodicals, Inc.

  3. Design study of a low-emittance high-repetition rate thermionic rf gun

    Science.gov (United States)

    Opanasenko, A.; Mytrochenko, V.; Zhaunerchyk, V.; Goryashko, V. A.

    2017-05-01

    We propose a novel gridless continuous-wave radiofrequency (rf) thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

  4. Modeling and analysis of fractional order DC-DC converter.

    Science.gov (United States)

    Radwan, Ahmed G; Emira, Ahmed A; AbdelAty, Amr M; Azar, Ahmed Taher

    2017-07-11

    Due to the non-idealities of commercial inductors, the demand for a better model that accurately describe their dynamic response is elevated. So, the fractional order models of Buck, Boost and Buck-Boost DC-DC converters are presented in this paper. The detailed analysis is made for the two most common modes of converter operation: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Closed form time domain expressions are derived for inductor currents, voltage gain, average current, conduction time and power efficiency where the effect of the fractional order inductor is found to be strongly present. For example, the peak inductor current at steady state increases with decreasing the inductor order. Advanced Design Systems (ADS) circuit simulations are used to verify the derived formulas, where the fractional order inductor is simulated using Valsa Constant Phase Element (CPE) approximation and Generalized Impedance Converter (GIC). Different simulation results are introduced with good matching to the theoretical formulas for the three DC-DC converter topologies under different fractional orders. A comprehensive comparison with the recently published literature is presented to show the advantages and disadvantages of each approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  5. An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

    Directory of Open Access Journals (Sweden)

    Liwen Pan

    2016-06-01

    Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.

  6. Enhanced Light Emitters Based on Metamaterials

    Science.gov (United States)

    2015-03-30

    metal-dielectric structures with colloidal quantum dots. Schematic drawing of the structure is shown in Fig. 1. The colloidal QDs are deposited via...spin coating and capped with poly methyl methacrylate. The metal and dielectric layers are deposited via sputtering/electron beam evaporation. The...ouput. The samples weer pumped with a 440 nm laser and imaged using a scanning confocal imaging set up with an avalanche photo diode (APD) detector. Fig

  7. Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

    Science.gov (United States)

    Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

    2014-09-09

    A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

  8. Deterministic Cold Cathode Electron Emission from Carbon Nanofibre Arrays

    Science.gov (United States)

    Cole, Matthew T.; Teo, Kenneth B. K.; Groening, Oliver; Gangloff, Laurent; Legagneux, Pierre; Milne, William I.

    2014-05-01

    The ability to accurately design carbon nanofibre (CN) field emitters with predictable electron emission characteristics will enable their use as electron sources in various applications such as microwave amplifiers, electron microscopy, parallel beam electron lithography and advanced Xray sources. Here, highly uniform CN arrays of controlled diameter, pitch and length were fabricated using plasma enhanced chemical vapour deposition and their individual emission characteristics and field enhancement factors were probed using scanning anode field emission mapping. For a pitch of 10 µm and a CN length of 5 µm, the directly measured enhancement factors of individual CNs was 242, which was in excellent agreement with conventional geometry estimates (240). We show here direct empirical evidence that in regular arrays of vertically aligned CNs the overall enhancement factor is reduced when the pitch between emitters is less than half the emitter height, in accordance to our electrostatic simulations. Individual emitters showed narrow Gaussian-like field enhancement distributions, in excellent agreement with electric field simulations.

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

    DEFF Research Database (Denmark)

    2009-01-01

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

  10. Selective emitter using porous silicon for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Inyong; Kim, Kyunghae; Kim, Youngkuk; Han, Kyumin; Kyeong, Doheon; Kwon, Taeyoung; Vinh Ai, Dao; Lee, Jeongchul; Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-Gu, Suwon-City, Kyunggi-Do 440-746 (Korea); Thamilselvan, M. [School of Information and Communication Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-Gu, Suwon-City, Kyunggi-Do 440-746 (Korea); Government College of Technology, Coimbatore, Tamilnadu (India); Ju, Minkyu; Lee, Kyungsoo [KPE Ins. Chunchun-dong, Jangan-Gu, Suwon-City, Kyunggi-Do 440-746 (Korea)

    2009-06-15

    This study is devoted to the formation of high-low-level-doped selective emitter for crystalline silicon solar cells for photovoltaic application. We report here the formation of porous silicon under chemical reaction condition. The chemical mixture containing hydrofluoric and nitric acid, with de-ionized water, was used to make porous on the half of the silicon surface of size 125 x 125 cm. Porous and non-porous areas each share half of the whole silicon surface. H{sub 3}PO{sub 4}:methanol gives the best deposited layer with acceptable adherence and uniformity on the non-porous and porous areas of the silicon surface to get high- and low-level-doped regions. The volume concentration of H{sub 3}PO{sub 4} does not exceed 10% of the total volume emulsion. Phosphoric acid was used as an n-type doping source to make emitter for silicon solar cells. The measured emitter sheet resistances at the high- and low-level-doped regions were 30-35 and 97-474 {omega}/{open_square} respectively. A simple process for low- and high-level doping has been achieved by forming porous and porous-free silicon surface, in this study, which could be applied for solar cells selective emitter doping. (author)

  11. Selective solar absorber emittance measurement at elevated temperature

    Science.gov (United States)

    Giraud, Philémon; Braillon, Julien; Raccurt, Olivier

    2017-06-01

    Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The characterization of a material in such condition is complicated and requires advanced apparatuses, and different measurement methods exist for the determination of the two quantities of relevance regarding an absorber, which are its emittance and its solar absorbance. The objective is to develop new optical equipment for measure the emittance of this solar absorber at elevated temperature. In this paper, we present an optical bench developed for emittance measurement on absorbers is conditions of use. Results will be shown, with a discussion of some factors of influence over this measurement and how to control them.

  12. Analysis of Urine for Pure Beta Emitters: Methods and Application

    DEFF Research Database (Denmark)

    Hou, Xiaolin

    2011-01-01

    by combustion to separate tritiated water from organically-bound tritium. Inorganic C-14 from organically-bound C-14, the separated tritium and C-14 were measured using liquid scintillation counting. Iodine-129, a long-lived beta emitter, is normally released to the atmosphere during the operation of nuclear...

  13. The brightest Ly α emitter: Pop III or black hole?

    NARCIS (Netherlands)

    Pallottini, A.; Ferrara, A.; Pacucci, F.; Gallerani, S.; Salvadori, S.; Schneider, R.; Schaerer, D.; Sobral, D.; Matthee, J.

    2015-01-01

    CR7 is the brightest z = 6.6 Ly α emitter (LAE) known to date, and spectroscopic follow-up by Sobral et al. suggests that CR7 might host Population (Pop) III stars. We examine this interpretation using cosmological hydrodynamical simulations. Several simulated galaxies show the same `Pop III wave'

  14. Application of positron emitters to studies on plants

    Energy Technology Data Exchange (ETDEWEB)

    Ishioka, N.S.; Matsuoka, H. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Sekine, T. [and others

    1998-10-01

    A newly developed positron emitting tracer imaging system enables us to study dynamically the physiological function of plants, although this system covers, at present, a limited area in a plant. Production of the positron emitters {sup 11}C, {sup 13}N, {sup 18}F and {sup 48}V for this application, using an AVF cyclotron, is described. (author)

  15. Jamming of Quantum Emitters by Active Coated Nanoparticles

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2013-01-01

    A spherical active coated nanoparticle consisting of a silica nanocore covered concentrically with a silver nanoshell is examined analytically and numerically in the presence of one, two, or four quantum emitters modeled by electric Hertzian dipoles. The ability of the active coated nanoparticle...

  16. Scanning Emitter Lifetime Imaging Microscopy for Spontaneous Emission Control

    DEFF Research Database (Denmark)

    Frimmer, Martin; Chen, Yuntian; Koenderink, A. Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nanophotonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment while...

  17. Low-energy electron beams through ultra-thin foils, applications for electron microscopy

    NARCIS (Netherlands)

    Van Aken, R.H.

    2005-01-01

    This thesis has discussed two electron microscopy applications that make use of ultra-thin foils: the tunnel junction emitter and the low-energy foil corrector. Both applications have in common that the electron beam is sent through the thin foil at low energy. Part of the electrons will scatter in

  18. DC Microgrids—Part II

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez

    2016-01-01

    . Closely coupled with protection, conflicting grounding objectives, e.g. minimization of stray current and common mode voltage are explained and several practical solutions are presented. Also, standardization efforts for DC systems are addressed. Finally, concluding remarks and important future research...

  19. Electricity-AC versus DC

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Electricity - AC versus DC. D P Sen Gupta. General Article Volume 2 Issue 10 October 1997 pp 46-53. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/10/0046-0053. Author Affiliations.

  20. Voltage Weak DC Distribution Grids

    NARCIS (Netherlands)

    Hailu, T.G.; Mackay, L.J.; Ramirez Elizondo, L.M.; Ferreira, J.A.

    2017-01-01

    This paper describes the behavior of voltage weak DC distribution systems. These systems have relatively small system capacitance. The size of system capacitance, which stores energy, has a considerable effect on the value of fault currents, control complexity, and system reliability. A number of

  1. Nonmagnetic Quantum Emitters in Boron Nitride with Ultranarrow and Sideband-Free Emission Spectra.

    Science.gov (United States)

    Li, Xiangzhi; Shepard, Gabriella D; Cupo, Andrew; Camporeale, Nicolas; Shayan, Kamran; Luo, Yue; Meunier, Vincent; Strauf, Stefan

    2017-07-25

    Hexagonal boron nitride (hBN) is an emerging material in nanophotonics and an attractive host for color centers for quantum photonic devices. Here, we show that optical emission from individual quantum emitters in hBN is spatially correlated with structural defects and can display ultranarrow zero-phonon line width down to 45 μeV if spectral diffusion is effectively eliminated by proper surface passivation. We demonstrate that undesired emission into phonon sidebands is largely absent for this type of emitter. In addition, magneto-optical characterization reveals cycling optical transitions with an upper bound for the g-factor of 0.2 ± 0.2. Spin-polarized density functional theory calculations predict possible commensurate transitions between like-spin electron states, which are in excellent agreement with the experimental nonmagnetic defect center emission. Our results constitute a step toward the realization of narrowband quantum light sources and the development of spin-photon interfaces within 2D materials for future chip-scale quantum networks.

  2. Experimental results of the laserwire emittance scanner for LINAC4 at CERN

    CERN Document Server

    Hofmann, Thomas; Bosco, Alessio; Bravin, Enrico; Gibson, Stephen M.; Kruchinin, Konstantin O.; Raich, Uli; Roncarolo, Federico; Zocca, Francesca

    2016-01-01

    Within the framework of the LHC Injector Upgrade (LIU), the new LINAC4 is currently being commissioned to replace the existing LINAC2 proton source at CERN. After the expected completion at the end of 2016, the LINAC4 will accelerate H- ions to 160 MeV. To measure the transverse emittance of the H- beam, a method based on photo-detachment is proposed. This system will operate using a pulsed laser with light delivered via an optical fibre and subsequently focused through a thin slice of the H- beam. The laser photons have sufficient energy to detach the outer electron and create H0/e- pairs. In a downstream dipole, the created H0 particles are separated from the unstripped H- ions and their distribution is measured with a dedicated detector. By scanning the focused laser across the H- beam, the transverse emittance of the H- beam can be reconstructed. This paper will first discuss the concept, design and simulations of the laser

  3. Influence of Particle Velocity of Copper on Emitter Contact by Cold-Spray Method

    Science.gov (United States)

    Kang, Byungjun; Lee, Kyung Dong; Lee, Jong-gun; Choi, Jae-Wook; Yoon, Sam S.; Kang, Yoonmook; Lee, Hae-seok; Kim, Donghwan

    2016-02-01

    In this study, we investigated cold-sprayed copper as a front contact for crystalline silicon solar cells. Copper powder was deposited on a monocrystalline silicon wafer with variation of the particle velocity during deposition. The particle velocity was varied by varying the heating temperature from 250 to 400 °C using a gas pressure of 0.45 MPa. The particle velocities were calculated using empirical equations, and were found to increase with an increase in the carrier gas temperature. Grid patterns were formed on a phosphorus-doped n-type emitter of a p-type silicon substrate. The electrode thickness increased with increasing particle velocity. The electrical properties of the grids were evaluated using the transfer length method. The specific contact resistance of the n-type emitter was in the range of 2.6-26.4 mΩ-cm2. Damage to the p- n junction was investigated via minority carrier lifetime measurement of the substrate. The copper-silicon interface was evaluated using transmission electron microscopy. The contact properties were affected by the interface conditions.

  4. Stable two-plane focusing for emittance-dominated sheet-beam transport

    Science.gov (United States)

    Carlsten, B. E.; Earley, L. M.; Krawczyk, F. L.; Russell, S. J.; Potter, J. M.; Ferguson, P.; Humphries, S.

    2005-06-01

    Two-plane focusing of sheet electron beams will be an essential technology for an emerging class of high-power, 100 to 300 GHz rf sources [Carlsten et al., IEEE Trans. Plasma Sci. 33, 85 (2005), ITPSBD, 0093-3813, 10.1109/TPS.2004.841172]. In these devices, the beam has a unique asymmetry in which the transport is emittance dominated in the sheet’s thin dimension and space-charge dominated in the sheet’s wide dimension. Previous work has studied the stability of the transport of beams in the emittance-dominated regime for both wiggler and periodic permanent magnet (PPM) configurations with single-plane focusing, and has found that bigger envelope scalloping occurs for equilibrium transport, as compared to space-charge dominated beams [Carlsten et al., this issue, Phys. Rev. ST Accel. Beams 8, 062001 (2005), PRABFM, 1098-4402]. In this paper, we describe the differences in transport stability when two-plane focusing is included. Two-plane wiggler focusing degrades the transport stability slightly, whereas two-plane PPM focusing greatly compromises the transport. On the other hand, single-plane PPM focusing can be augmented with external quadrupole fields to provide weak focusing in the sheet’s wide dimension, which has stability comparable to two-plane wiggler transport.

  5. The present status of high-T c superconducting terahertz emitters

    Science.gov (United States)

    Kashiwagi, T.; Kubo, H.; Sakamoto, K.; Yuasa, T.; Tanabe, Y.; Watanabe, C.; Tanaka, T.; Komori, Y.; Ota, R.; Kuwano, G.; Nakamura, K.; Katsuragawa, T.; Tsujimoto, M.; Yamamoto, T.; Yoshizaki, R.; Minami, H.; Kadowaki, K.; Klemm, R. A.

    2017-07-01

    A terahertz (THz) wave emitter using the stack of intrinsic Josephson junctions present in the high-T c superconductor Bi2Sr2CaCu2O8+δ (Bi2212) has been developed. By applying a dc voltage V across the stack, the ac-Josephson effect converts this to an ac-current that emits photons at the Josephson frequency proportional to V. The Bi2212 device also behaves as and electromagnetic (EM) cavity, so depending upon the shape of the Bi2212 crystal, when the Josephson frequency matches that of a cavity resonance, the emission power is enhanced. However, the EM radiation characteristics also strongly depend upon the effects of Joule self heating of the device. In order to alleviate this Joule heating problem, we fabricated three distinct stand-alone Bi2212 sandwich device shapes, each crystal being first covered with Au on its top and bottom, and then sandwiched between sapphire plates. From our comparative studies of the three devices, we obtained important clues that could help to increase the emission power up to ∼mW and the frequency range up to several THz, as necessary for many applications such as security screening, high speed communications, medical and biological sensing, and astronomical detection, etc.

  6. Next-Generation Shipboard DC Power System

    DEFF Research Database (Denmark)

    Jin, Zheming; Sulligoi, Giorgio; Cuzner, Rob

    2016-01-01

    . At present, the research of dc microgrid has investigated and developed a series of advanced methods in control, management and objective-oriented optimization, which would found the technical interface enabling the future applications in multiple industrial areas, such as smart buildings, electric vehicles......In recent years, more and more evidence suggests that the global energy system is on the verge of a drastic revolution. The evolutionary development in power electronic technologies, the emerging high-performance energy storage devices, as well as the ever increasing penetration of renewable energy...... in research interests and industrial applications. In addition, the concept of flexible and smart distribution has also been proposed, which tends to exploit distributed generation and pack the distributed RESs and local electrical loads as an independent and self-sustainable entity, namely microgrid...

  7. Diamond coated silicon field emitter array

    Energy Technology Data Exchange (ETDEWEB)

    S. Albin; W. Fu; A. Varghese; A. C. Lavarias; G. R. Myneni

    1999-07-01

    Diamond coated silicon tip arrays, with and without a self-aligned gate, were fabricated, and current-voltage characteristics of 400 tips were measured. Diamond films were grown uniformly on Si tips using microwave plasma after nucleation with 10 nm diamond suspension and substrate bias. An emission current of 57 ?A was obtained at 5 V from the ungated array tips separated from an anode at 2 ?m. In the case of the gated arrays with 1.5 ?m aperture, an emission current of 3.4 ?A was measured at a gate voltage of 80 V for an anode separation of 200 ?m. The turn-on voltages for these two types of devices were 0.2 and 40 V, respectively. Diamond coated Si tip arrays have potential applications in field emission based low voltage vacuum electronic devices and microsensors.

  8. A Current-Fed Isolated Bidirectional DC-DC Converter

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

    2017-01-01

    This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...... of the low-voltage (LV) side switches in the proposed converter can be eliminated without additional clamp circuits. The converter adopts the pulse width modulation (PWM) plus hybrid phase-shift control scheme such that the bus voltage can match the output voltage by means of the transformer. Thus......, the current stresses and conduction losses of the converter become lower. In addition, the practical ZVS of the secondary-side switches can be realized by adjusting the phase-shift angle within the secondary side when in light load or no load condition. The operating principles and characteristics including...

  9. Dilation and Curettage (D&C)

    Science.gov (United States)

    ... For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and Curettage ( ... February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage (D& ...

  10. NAMMA DC-8 DROPSONDE V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA DC-8 Dropsonde dataset were collected by the DC-8 dropsonde system, which uses an integrated, highly accurate, GPS-located atmospheric profiling dropsonde...

  11. Field emission electronics

    CERN Document Server

    Egorov, Nikolay

    2017-01-01

    This book is dedicated to field emission electronics, a promising field at the interface between “classic” vacuum electronics and nanotechnology. In addition to theoretical models, it includes detailed descriptions of experimental and research techniques and production technologies for different types of field emitters based on various construction principles. It particularly focuses on research into and production of field cathodes and electron guns using recently developed nanomaterials and carbon nanotubes. Further, it discusses the applications of field emission cathodes in new technologies such as light sources, flat screens, microwave and X-ray devices.

  12. High-Temperature SOI/SiC-Based DC-DC Converter Suite

    Directory of Open Access Journals (Sweden)

    Brice McPherson

    2008-08-01

    Full Text Available A complete design strategy (mechanical and electrical for a 25 W 28 V/5 V dc-dc converter utilizing SiC and SOI electronics is presented. The converter includes a high-temperature SOI-based PWM controller featuring 150 kHz operation, a PID feedback loop, maximum duty cycle limit, complementary or symmetrical outputs, and a bootstrapped high-side gate driver. Several passive technologies were investigated for both control and power sections. Capacitor technologies were characterized over temperature and over time at 300C∘, power inductors designed and tested up to 350C∘, and power transformers designed and tested up to 500C∘. Northrop Grumman normally-off SiC JFETs were used as power switches and were characterized up to 250C∘. Efficiency and mass optimization routines were developed with the data gained from the first prototype. The effects of radiation on SiC and SOI electronics are then discussed. The results of the first prototype module are presented, with operation from 25C∘ up to an ambient temperature of 240C∘ .

  13. Implementation of hierarchical control in DC microgrids

    DEFF Research Database (Denmark)

    Jin, Chi; Wang, Peng; Xiao, Jianfang

    2014-01-01

    DC microgrids are becoming popular in low-voltage distribution systems due to the better compatibility with photovoltaic panels, electric vehicles, and dc loads. This paper presents a practical dc microgrid developed in the Water and Energy Research Laboratory (WERL) in the Nanyang University of ...

  14. Toward the Universal DC Distribution System

    NARCIS (Netherlands)

    Mackay, L.J.; van der Blij, N.H.; Ramirez Elizondo, L.M.; Bauer, P.

    2017-01-01

    AbstractDue to an increasing number of power generation units and load devices operating with direct current (DC) at distribution level, there is a potential benefit of leading efforts toward building a DC distribution system. However, the implementation of DC distribution systems faces important

  15. High efficiency high step-up DC/DC converters - a review

    National Research Council Canada - National Science Library

    Tomaszuk, A; Krupa, A

    2011-01-01

    .... This review is focused on high efficiency step-up DC/DC converters with high voltage gain. The differentiation is based on the presence or lack of galvanic isolation. A comparison and discussion of different DC/DC step-up topologies will be performed across number of parameters and presented in this paper.

  16. High Power Zero-Voltage and Zero-Current Switching DC-DC Converters

    Directory of Open Access Journals (Sweden)

    Jaroslav Dudrik

    2005-01-01

    Full Text Available The paper presents principles and properties of the soft switching PWM DC-DC converters. The attention is focused mainly on high power applications and thus the full-bridge inverters are used in DC-DC converters. Considerations are also given to the control methods and principles of the switching and conduction losses reduction.

  17. A Family of Four Quadrant DC/DC Converters with Reduced Number of Components

    DEFF Research Database (Denmark)

    Mostaan, Ali; Soltani, Mohsen

    2015-01-01

    A family of four quadrant DC/DC converters is presented in this paper. Compare with existing four quadrant DC/DC converters that have been introduced in literature, the proposed converters have lower number of components. There are two bidirectional switches, two coupled inductors and one capacitor...

  18. Impact of water temperature and structural parameters on the hydraulic labyrinth-channel emitter performance

    Directory of Open Access Journals (Sweden)

    Ahmed I. Al-Amoud

    2014-06-01

    Full Text Available The effects of water temperature and structural parameters of a labyrinth emitter on drip irrigation hydraulic performance were investigated. The inside structural parameters of the trapezoidal labyrinth emitter include path width (W and length (L, trapezoidal unit numbers (N, height (H, and spacing (S. Laboratory experiments were conducted using five different types of labyrinth-channel emitters (three non-pressure compensating and two pressure-compensating emitters commonly used for subsurface drip irrigation systems. The water temperature effect on the hydraulic characteristics at various operating pressures was recorded and a comparison was made to identify the most effective structural parameter on emitter performance. The pressure compensating emitter flow exponent (x average was 0.014, while non-pressure compensating emitter’s values average was 0.456, indicating that the sensitivity of non-pressure compensating emitters to pressure variation is an obvious characteristic (p<0.001 of this type of emitters. The effects of water temperature on emitter flow rate were insignificant (p>0.05 at various operating pressures, where the flow rate index values for emitters were around one. The effects of water temperature on manufacturer’s coefficient of variation (CV values for all emitters were insignificant (p>0.05. The CV values of the non-pressure compensating emitters were lower than those of pressure compensating emitters. This is typical for most compensating models because they are manufactured with more elements than non-compensating emitters are. The results of regression analysis indicate that N and H are the essential factors (p<0.001 to affect the hydraulic performance.

  19. Power Electronics for Microgrids

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Blaabjerg, Frede

    2016-01-01

    A microgrid (MG) is a stand-alone or grid-connected hybrid renewable system that uses distributed renewable and nonrenewable energy sources and energy storage systems (ESSs) to supply power to local loads. The system is ordinarily based on power electronics, with interface converters allowing...... a continuous supply of power in the presence of variable RES production. This chapter describes some specific features of DC MGs in terms of power architecture, control, and protection. It also reviews several uncommon power electronic interfaces. Regarding control, operation without critical communication...... are explained in this chapter. The chapter concludes with a review of power electronic intensive protection solutions for DC MGs....

  20. 75 FR 36579 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-30, DC-10-30F, DC-10-30F (KC...

    Science.gov (United States)

    2010-06-28

    ... Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10), DC-10-40, DC-10-40F, and MD-10-30F...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain Model DC-10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10), DC- 10-40, DC10-40F, and MD-10-30F airplanes. This proposed AD would...