WorldWideScience

Sample records for beam current drive

  1. CLIC Drive Beam Phase Stabilisation

    CERN Document Server

    Gerbershagen, Alexander; Schulte, Daniel

    The thesis presents phase stability studies for the Compact Linear Collider (CLIC) and focuses in particular on CLIC Drive Beam longitudinal phase stabilisation. This topic constitutes one of the main feasibility challenges for CLIC construction and is an essential component of the current CLIC stabilisation campaign. The studies are divided into two large interrelated sections: the simulation studies for the CLIC Drive Beam stability, and measurements, data analysis and simulations of the CLIC Test Facility (CTF3) Drive Beam phase errors. A dedicated software tool has been developed for a step-by-step analysis of the error propagation through the CLIC Drive Beam. It uses realistic RF potential and beam loading amplitude functions for the Drive and Main Beam accelerating structures, complete models of the recombination scheme and compressor chicane as well as of further CLIC Drive Beam modules. The tool has been tested extensively and its functionality has been verified. The phase error propagation at CLIC h...

  2. CLIC Drive Beam Accelerating Structures

    CERN Document Server

    Wegner, Rolf

    2012-01-01

    Travelling structures for accelerating the high-current (4.2 A) CLIC Drive Beam to an energy of 2.37 GeV are presented. The structures are optimised for efficiency (full beam loading operation) and a desired filling time. Higher order modes are studied and are reduced by detuning along the structure and by damping with silicon carbide loads.

  3. The Influence of Neutral Beam Injection on the Heating and Current Drive with Electron Cyclotron Wave on EAST

    Science.gov (United States)

    Chang, Pengxiang; Wu, Bin; Wang, Jinfang; Li, Yingying; Wang, Xiaoguang; Xu, Handong; Wang, Xiaojie; Liu, Yong; Zhao, Hailin; Hao, Baolong; Yang, Zhen; Zheng, Ting; Hu, Chundong

    2016-11-01

    Both neutral beam injection (NBI) and electron cyclotron resonance heating (ECRH) have been applied on the Experimental Advanced Superconducting Tokamak (EAST) in the 2015 campaign. In order to achieve more effective heating and current drive, the effects of NBI on the heating and current drive with electron cyclotron wave (ECW) are analyzed utilizing the code TORAY and experimental data in the shot #54411 and #54417. According to the experimental and simulated results, for the heating with ECW, NBI can improve the heating efficiency and move the power deposition place towards the inside of the plasma. On the other hand, for the electron cyclotron current drive (ECCD), NBI can also improve the efficiency of ECCD and move the place of ECCD inward. These results will be valuable for the center heating, the achievement of fully non-inductive current drive operation and the suppression of magnetohydrodynamic (MHD) instabilities with ECW on EAST or ITER with many auxiliary heating methods. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB101001 and 2014DFG61950) and National Natural Science Foundation of China (Nos. 11405212 and 11175211)

  4. Fast-ion transport and neutral beam current drive in ASDEX upgrade

    DEFF Research Database (Denmark)

    Geiger, B.; Weiland, M.; Jacobsen, Asger Schou;

    2015-01-01

    during on-axis injection and outwards shifted profiles during off-axis injection. Due to this change of the fast-ion population, a clear modification of the plasma current profile is predicted but not observed by a motional Stark effect diagnostic. The fast-ion transport caused by MHD activity has been...... studied in low collisionality discharges that exhibit strong (1, 1) modes. In particular due to sawtooth crashes, significant radial redistribution of co-rotating fast-ions is observed which can very well be described by the Kadomtsev model. In addition, first tomographic reconstructions of the central 2D...

  5. Non-inductive current built-up by local electron cyclotron heating and current drive with a 28 GHz focused beam on QUEST

    Science.gov (United States)

    Onchi, Takumi; Idei, Hiroshi; Hasegawa, Makoto; Ohwada, Hiroaki; Zushi, Hideki; Hanada, Kazuaki; Kariya, Tsuyoshi; Mishra, Kishore; Shikama, Taichi; Quest Team

    2016-10-01

    The plasma current can be driven solely by injecting electron cyclotron waves (ECWs) in spherical tokamak (ST) configuration. A system of 28 GHz gyrotron (maximum power: 270 kW) is renewed and reinstalled on QUEST. A focused ECW beam, whose diameter is about 5 cm at the second harmonic resonance, is injected for local ECW heating and current drive. The local power density at resonance exceeds 75 MW/m2 at an injection power of 150 kW. The incident ECW polarization can be adjusted employing the phase shifter consisting of two corrugated plates. During 1.25 second pulse of ECH, plasma current is built up to Ip = 70 kA fully non-inductively with a core electron density of ne > 1018 m-3. The closed flux in such ST plasma is determined at the inboard limiter on the center stack. Energetic electrons are also responsible for the pressure and equilibrium. This work is supported by JSPS KAKENHI (15H04231, 15K17800), NIFS Collaboration Research program (NIFS13KUTR085, NIFS11KUTR069, NIFS16KUTR114).

  6. CTF3 Drive Beam Injector Optimisation

    CERN Document Server

    AUTHOR|(CDS)2082899; Doebert, S

    2015-01-01

    In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel to the main linac. The main feasibility issues of the two-beam acceleration scheme are being demonstrated at CLIC Test Facility 3 (CTF3). The CTF3 Drive Beam injector consists of a thermionic gun followed by the bunching system and two accelerating structures all embedded in solenoidal magnetic field and a magnetic chicane. Three sub-harmonic bunchers (SHB), a prebuncher and a travelling wave buncher constitute the bunching system. The phase coding process done by the sub-harmonic bunching system produces unwanted satellite bunches between the successive main bunches. The beam dynamics of the CTF3 Drive Beam injector is reoptimised with the goal of improving the injector performance and in particular decreasing the satellite population, the beam loss in the magnetic chicane and the beam emittance in transverse plane compare to the original model based on P. Ur...

  7. Low current beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saint, A.; Laird, J.S.; Bardos, R.A.; Legge, G.J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T.; Sekiguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan).

    1993-12-31

    Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

  8. CTF3 Drive Beam Accelerating Structures

    CERN Document Server

    Jensen, E

    2002-01-01

    The 3 GHz drive beam accelerator of the CLIC Test Facility CTF3, currently under construction at CERN, will be equipped with 16 novel SICA (Slotted Iris – Constant Aperture) accelerating structures. The slotted irises couple out the potentially disruptive induced transverse HOM energy to integrated silicon carbide loads (dipole mode Q's below 20). The use of nose cones for detuning allows a constant inner aperture (34 mm). The structures will be 1.2 m long and consist of 34 cells. A first 6 cell prototype structure has been tested successfully up to power levels of 100 MW (nominal: 30 MW), corresponding to surface electric field levels of 180 MV/m.

  9. Electron cyclotron heating and current drive

    NARCIS (Netherlands)

    Westerhof, E.

    1996-01-01

    Plasma heating and non-inductive current drive by waves in the electron cyclotron range of frequencies are reviewed. Both theoretical aspects concerning wave properties, heating and current drive mechanisms, as well as the major experimental results are summarized.

  10. CLIC Main Linac Beam-Loading Compensation by Drive Beam Phase Modulation

    CERN Document Server

    Corsini, R; Syratchev, I V

    1999-01-01

    The CLIC final focus momentum acceptance of ± 0.5 % limits the bunch-to-bunch energy variation in the main beam to less than ± 0.1 %, since the estimated single-bunch contribution is ± 0.4 %. On the other hand, a relatively high beam-loading of the main accelerating structures (about 16 %) is unavoidable in order to optimize the RF-to-beam efficiency. Therefore, a compensation method is needed to reduce the resulting bunch-to-bunch energy spread of the main beam. Up to now, it has been planned to obtain the RF pulse shape needed for compensation by means of a charge ramp in the drive beam pulse. On the other hand, the use of constant-current drive beam pulses would make the design and operation of the drive beam injector considerably simpler. In this paper we present a possible solution adapted to the CLIC two-beam scheme with constant-current pulses, based on phase modulation of the drive beam bunches.

  11. Current drive induced by intermittent trapping

    Energy Technology Data Exchange (ETDEWEB)

    Nakach, R. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France); Gell, Y. [CET, Israel (Israel)

    1999-02-01

    We propose a mechanism for driving a current in a dispersive plasma based on intermittent trapping of electrons in a ponderomotive well generated by two- counterpropagating electron cyclotron waves. By choosing properly the parameters of the system, this mechanism is expected to induce a high efficiency current drive. (authors)

  12. Squid based beam current meter

    Energy Technology Data Exchange (ETDEWEB)

    Kuchnir, M.

    1983-11-25

    A SQUID based beam current meter has the capability of measuring the current of a beam with as little as 30 x 155 antiprotons (with a signal to noise ratio of 2). If low noise dc current is used to cancel most of the beam or an up-down counter is used to count auto-resets this sensitivity will be available at any time in the acumulation process. This current meter will therefore be a unique diagnostic tool for optimizing the performance of several Tev I components. Besides requiring liquid helium it seems that its only drawback is not to follow with the above sensitivity a sudden beam change larger than 16 ..mu..A, something that could be done using a second one in a less sensitive configuration.

  13. High-current cyclotron to drive an electronuclear assembly

    CERN Document Server

    Alenitsky, Yu G

    2002-01-01

    The proposal on creation of a high-current cyclotron complex for driving an electronuclear assembly reported at the 17th Meeting on Accelerators of Charged Particles is discussed. Some changes in the basic design parameters of the accelerator are considered in view of new results obtained in the recent works. It is shown that the cyclotron complex is now the most real and cheapest accelerator for production of proton beams with a power of up to 10 MW. Projects on design of a high-current cyclotron complex for driving an electronuclear subcritical assembly are presented.

  14. Digitally compensated beam current transformer

    CERN Document Server

    Kesselman, Martin

    2005-01-01

    The Spallation Neutron Source (SNS) is being built by a collaboration of six laboratories. Beam current monitors (BCMs) will be used to record the current of H-minus and H-plus beams ranging from 15 mA (tune-up in the Front End and Linac) to over 60A fully accumulated in the Ring and dumped to the load as a single pulse in the Ring to Beam Target (RTBT). The time structure of these beams ranges from 645ns "mini" bunches at the 1.05 MHz ring revolution rate, to an overall 1 ms long macro-pulse. The requirements for the BCMs will depend upon their location within the system. The need to measure individual mini-pulses, examine the characteristics of the chopper edge, as well as the longer average current pulse of the macropulse, or long duration pulses during Linac tuning place wide requirements upon the response of current transformers. To obtain the desired accuracy and resolution, current transformers must have less than 1 ns rise time and droops of 0.1 %/ms. This places a significant design burden on the cur...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-04-01

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

  16. Lower Hybrid Current Drive in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Ekedahl, A.; Goniche, M.; Guilhem, D.; Kazarian, F.; Peysson, Y. and Tore Supra Team [CEA, IRFM, F-13108 St Paul Les Durance, (France)

    2009-07-01

    Since the mission of Tore Supra is to produce quasi-steady-state discharges, the lower hybrid current drive (LHCD) system constitutes the most important method of additional hewing and noninductive current drive. A description of the LHCD is given, including the different launcher designs developed for the Tore Supra long-pulse program. Following the completion of the Composants Internes et Limiteur project, together with the installation of a high-performance LHCD launcher, world record discharges, injected and extracted energy exceeding 1 GJ, were obtained in 2003. With the flexibility of lower hybrid (LH) waves to tailor the current profile, an enhanced performance regime, the so-called LHEP has been maintained in quasi-steady-state discharges. Detailed measurements of the fast electron distribution have allowed us to constrain LHCD ray-tracing models and to quantify parametric dependencies describing the fast electron tail. Localized heat loads oil the LHCD launchers due to interaction with fast particles have been measured and quantified, using infrared imaging and calorimetric measurements oil water-cooled plasma facing components. Furthermore, experimental results in the area of LH wave coupling are presented. (authors)

  17. Assessment of Electron-Cyclotron-Current-Drive-Assisted Operation in DEMO

    Directory of Open Access Journals (Sweden)

    Marushchenko N.B.

    2012-09-01

    Full Text Available The achievable efficiency for external current drive through electron-cyclotron (EC waves in a demonstration tokamak reactor is discussed. Two possible reactor designs, one for steady state and one for pulsed operation, are considered. It is found that for midplane injection the achievable current drive efficiency is limited by secondharmonic absorption at levels consistent with previous studies. Propagation through the second-harmonic region can be reduced by moving the launch position to the high-field side (this can be obtained by injecting the beam from an upper port in the vacuum vessel. In this case, beam tracing calculations deliver values for the EC current drive efficiency approaching those usually reported for neutral beam current drive.

  18. Sensitive beam current measurement for FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Schwickert, Marcus; Kurian, Febin; Reeg, Hansjoerg [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Seidel, Paul; Neubert, Ralf [Friedrich-Schiller-Universitaet Jena (Germany); Geithner, Rene; Vodel, Wolfgang [Helmholtz-Institut Jena (Germany)

    2012-07-01

    Presently FAIR, the Facility for Antiproton and Ion Research, entered the final planning phase at GSI. The new accelerator facility requires precise devices for beam current measurements due to the large dynamics in beam intensities for the various synchrotrons, transport lines and storage rings. We report on the actual developments of beam diagnostic devices for the measurement of beam intensities ranging from 5 x 10{sup 11} uranium ions down to the detection of less than 10{sup 4} antiprotons. This contribution gives an overview of the planned instruments with a focus on non-intercepting beam current transformers, and summarizes the on-going development of a cryogenic current comparator.

  19. TOKAMAK EQUILIBRIA WITH CENTRAL CURRENT HOLES AND NEGATIVE CURRENT DRIVE

    Energy Technology Data Exchange (ETDEWEB)

    CHU, M.S.; PARKS, P.B.

    2002-06-01

    OAK B202 TOKAMAK EQUILIBRIA WITH CENTRAL CURRENT HOLES AND NEGATIVE CURRENT DRIVE. Several tokamak experiments have reported the development of a central region with vanishing currents (the current hole). Straightforward application of results from the work of Greene, Johnson and Weimer [Phys. Fluids, 3, 67 (1971)] on tokamak equilibrium to these plasmas leads to apparent singularities in several physical quantities including the Shafranov shift and casts doubts on the existence of this type of equilibria. In this paper, the above quoted equilibrium theory is re-examined and extended to include equilibria with a current hole. It is shown that singularities can be circumvented and that equilibria with a central current hole do satisfy the magnetohydrodynamic equilibrium condition with regular behavior for all the physical quantities and do not lead to infinitely large Shafranov shifts. Isolated equilibria with negative current in the central region could exist. But equilibria with negative currents in general do not have neighboring equilibria and thus cannot have experimental realization, i.e. no negative currents can be driven in the central region.

  20. Control Schemes for Driving Electro-optic Array Beam Deflectors

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The beam deflectors based on electro-optic phased array(EOPA) is mainly described, and then an analysis on existing control schemes for driving the EOPA beam deflectors, based on custom hard-wired electronics or based on software in a microcontroller, is made. Compared with these, a driving and control system for a multi-channel EOPA beam deflector is presented, in which the control assignment is implemented with a field programmable gate array(FPGA) chip. For different performance requirements, two control schemes, one with the serial scheme and another with the parallel scheme, have been explored and rapidly prototyped in Xilinx FPGA chips. With the control structures for the EOPA beam deflector, scanning rates of 588kHz and 5MHz can be respectively reached.

  1. Current Drive in a Ponderomotive Potential with Sign Reversal

    CERN Document Server

    Fisch, N J; Rax, J M

    2003-01-01

    Noninductive current drive can be accomplished through ponderomotive forces with high efficiency when the potential changes sign over the interaction region. The effect can practiced upon both ions and electrons. The current drive efficiencies, in principle, might be higher than those possible with conventional radio-frequency current-drive techniques, since different considerations come into play.

  2. Current Drive in a Ponderomotive Potential with Sign Reversal

    Energy Technology Data Exchange (ETDEWEB)

    N.J. Fisch; J.M. Rax; I.Y. Dodin

    2003-07-30

    Noninductive current drive can be accomplished through ponderomotive forces with high efficiency when the potential changes sign over the interaction region. The effect can practiced upon both ions and electrons. The current drive efficiencies, in principle, might be higher than those possible with conventional radio-frequency current-drive techniques, since different considerations come into play.

  3. Development of high current electron beam generator

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-05-01

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

  4. Off-Axis Undulator Radiation for CLIC Drive Beam Diagnostics

    CERN Document Server

    Jeff, A; Welsch, CP

    2013-01-01

    The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 1015 electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. In this paper we propose the use of relatively inexpensive permanent-magnet undulators to generate off-axis visible Synchrotron Radiation from the CLIC Drive Beam. The field strength and period length of the undulator should be designed such that the on-axis undulator wavelength is in the ultra-violet. A smaller but still useable amount of visible light is then generated in a hollow cone. This light can be reflected out of the beam pipe by a ring-shaped mirror placed downstream and imaged on a camera. In this contribution, results of SRW and ZEMA...

  5. Crossed-beam energy transfer in direct-drive implosions

    Energy Technology Data Exchange (ETDEWEB)

    Seka, W; Edgell, D H; Michel, D T; Froula, D H; Goncharov, V N; Craxton, R S; Divol, L; Epstein, R; Follett, R; Kelly, J H; Kosc, T Z; Maximov, A V; McCrory, R L; Meyerhofer, D D; Michel, P; Myatt, J F; Sangster, T C; Shvydky, A; Skupsky, S

    2012-05-22

    Direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have showed discrepancies between simulations of the scattered (non-absorbed) light levels and measured ones that indicate the presence of a mechanism that reduces laser coupling efficiency by 10%-20%. This appears to be due to crossed-beam energy transfer (CBET) that involves electromagnetic-seeded, low-gain stimulated Brillouin scattering. CBET scatters energy from the central portion of the incoming light beam to outgoing light, reducing the laser absorption and hydrodynamic efficiency of implosions. One-dimensional hydrodynamic simulations including CBET show good agreement with all observables in implosion experiments on OMEGA. Three strategies to mitigate CBET and improve laser coupling are considered: the use of narrow beams, multicolor lasers, and higher-Z ablators. Experiments on OMEGA using narrow beams have demonstrated improvements in implosion performance.

  6. Beam Tests of a Prototype Stripline Beam Position Monitoring System for the Drive Beam of the CLIC Two-beam Module at CTF3

    CERN Document Server

    Benot-Morell, Alfonso; Nappa, Jean-Marc; Vilalte, Sebastien; Wendt, Manfred

    2016-01-01

    In collaboration with LAPP and IFIC, two units of a prototype stripline Beam Position Monitor (BPM) for the CLIC Drive Beam (DB), and its associated readout electronics have been successfully installed and tested in the Two-Beam-Module (TBM) at the CLIC Test Facility 3 (CTF3) at CERN. This paper gives a short overview of the BPM system and presents the performance measured under different Drive Beam configurations.

  7. Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam

    CERN Document Server

    Carron, G; Luong, M; Millich, Antonio; Rugo, E; Syratchev, I V; Thorndahl, L

    2000-01-01

    For the CLIC two-beam scheme, a high-current, long-pulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 ms pulse length. The high current requires highly effective suppression of dipolar wakes. Two concepts are investigated for the accelerating structure design: the "Tapered Damped Structure" developed for the CLIC main beam, and the "Slotted Iris - Constant Aperture" structure. Both use 4 SiC loads per cell for effective higher-order mode damping. A full-size prototype of the TDS structure has been built and tested successfully at full power. A first prototype of the SICA structure is being built

  8. Variable Current Transient Beam Loading Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Zoltan D

    2000-10-25

    The energy spread caused by transients during beam turn-on can be reduced by suitable timing of the beam turn-on[1]. If the beam is injected when the no-load voltage reaches the desired loaded voltage, then the energy spread is about 10%. To eliminate this energy spread, one can amplitude or phase modulate the section input power for one fill time, so that when the beam is turned on, the no-load voltage equals the desired loaded voltage and from then on, the change in no-load voltage tracks the beam induced voltage. It is known that for a constant gradient (CG) structure, and amplitude variation of the form E(t) = a{sub 0} + (1 - a{sub 0}) t{sub p} will reduce the energy spread to zero for a current that is determined by a{sub 0}. When one uses rf modulation for transient beam loading compensation, the beam is injected a fill time after the rf has been turned on, and one is forced to throw away a section's worth of rf energy. In addition, it requires extra components which use up additional rf energy. This note describes transient beam loading compensation with variable current. It will show that it increases the rf energy to beam energy transfer efficiency.

  9. Current European developments in solar paddle drives

    Science.gov (United States)

    Bentall, R. H.

    1973-01-01

    The European Space Research and Technology Centre (ESTEC) is sponsoring the development of a number of critical spacecraft hardware items. The hardware under development includes two competing solar paddle drives which are being produced to similar specifications. Three mechanisms of each type are being produced and will undergo thermal vacuum testing. All mechanisms have lead lubricated bearings.

  10. Characterization of Input Current Interharmonics in Adjustable Speed Drives

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Zare, Firuz

    2017-01-01

    -edge symmetrical regularly sampled Space Vector Modulation (SVM) technique, on the input current interharmonic components are presented and discussed. Particular attention is also given to the influence of the asymmetrical regularly sampled modulation technique on the drive input current interharmonics...

  11. Plasma Heating and Current Drive for Fusion Reactors

    Science.gov (United States)

    Holtkamp, Norbert

    2010-02-01

    ITER (in Latin ``the way'') is designed to demonstrate the scientific and technological feasibility of fusion energy. Fusion is the process by which two light atomic nuclei combine to form a heavier one and thus release energy. In the fusion process two isotopes of hydrogen - deuterium and tritium - fuse together to form a helium atom and a neutron. Thus fusion could provide large scale energy production without greenhouse effects; essentially limitless fuel would be available all over the world. The principal goals of ITER are to generate 500 megawatts of fusion power for periods of 300 to 500 seconds with a fusion power multiplication factor, Q, of at least 10. Q >= 10 (input power 50 MW / output power 500 MW). In a Tokamak the definition of the functionalities and requirements for the Plasma Heating and Current Drive are relevant in the determination of the overall plant efficiency, the operation cost of the plant and the plant availability. This paper summarise these functionalities and requirements in perspective of the systems under construction in ITER. It discusses the further steps necessary to meet those requirements. Approximately one half of the total heating will be provided by two Neutral Beam injection systems at with energy of 1 MeV and a beam power of 16 MW into the plasma. For ITER specific test facility is being build in order to develop and test the Neutral Beam injectors. Remote handling maintenance scheme for the NB systems, critical during the nuclear phase of the project, will be developed. In addition the paper will give an overview over the general status of ITER. )

  12. Design and characterization of a prototype stripline beam position monitor for the Clic Drive Beam*

    CERN Document Server

    Benot-Morell, A; Wendt, M; Nappa, J M; Tassan-Viol, J; Vilalte, S; Smith, S

    2012-01-01

    The prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics is under development at CERN, in collaboration with SLAC, LAPP and IFIC. The anticipated position resolution and accuracy are expected to be below 2μm and 20μm respectively for operation of the BPM in the CLIC drive beam (DB) linac. This paper describes the particular CLIC DB conditions with respect to the beam position monitoring, presents the measurement concept, and summarizes electromagnetic simulations and RF measurements performed on the prototype.

  13. Achromatic beam transport of High Current Injector

    Science.gov (United States)

    Kumar, Sarvesh; Mandal, A.

    2016-02-01

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

  14. Sensorless optimal sinusoidal brushless direct current for hard disk drives

    Science.gov (United States)

    Soh, C. S.; Bi, C.

    2009-04-01

    Initiated by the availability of digital signal processors and emergence of new applications, market demands for permanent magnet synchronous motors have been surging. As its back-emf is sinusoidal, the drive current should also be sinusoidal for reducing the torque ripple. However, in applications like hard disk drives, brushless direct current (BLDC) drive is adopted instead of sinusoidal drive for simplification. The adoption, however, comes at the expense of increased harmonics, losses, torque pulsations, and acoustics. In this paper, we propose a sensorless optimal sinusoidal BLDC drive. First and foremost, the derivation for an optimal sinusoidal drive is presented, and a power angle control scheme is proposed to achieve an optimal sinusoidal BLDC. The scheme maintains linear relationship between the motor speed and drive voltage. In an attempt to execute the sensorless drive, an innovative power angle measurement scheme is devised, which takes advantage of the freewheeling diodes and measures the power angle through the detection of diode voltage drops. The objectives as laid out will be presented and discussed in this paper, supported by derivations, simulations, and experimental results. The proposed scheme is straightforward, brings about the benefits of sensorless sinusoidal drive, negates the need for current sensors by utilizing the freewheeling diodes, and does not incur additional cost.

  15. The LHC Fast Beam Current change Monitor

    CERN Document Server

    Belohrad, D; Jensen, L; Krupa, M; Topaloudis, A

    2013-01-01

    The modularity of the Large Hadron Collider’s (LHC) machine protection system (MPS) allows for the integration of several beam diagnostic instruments. These instruments have not necessarily been designed to have protection functionality, but MPS can still use them to increase the redundancy and reliability of the machine. The LHC fast beam current change monitor (FBCCM) is an example. It is based on analogue signals from fast beam current transformers (FBCT) used nominally to measure the LHC bunch intensities. The FBCCM calculates the magnitude of the beam signal provided by the FBCT, looks for a change over specific time intervals, and triggers a beam dump interlock if losses exceed an energy-dependent threshold. The first prototype of the FBCCM was installed in the LHC during the 2012-2013 run. The aim of this article is to present the FBCCM system and the results obtained, analyse its current performance and provide an outlook for the final system which is expected to be operational after the long LHC sh...

  16. Review of the Drive Beam Stabilization in the CLIC Test Facility CTF3

    CERN Document Server

    Dubrovskiy, A; Skowronski, P; Tecker, F; Persson, T

    2013-01-01

    CTF3 is a Test Facility focusing on beam-based studies of the key concepts of the Compact Linear Collider CLIC. Over the past several years many aspects of the CLIC two-beam acceleration scheme were studied in CTF3, including the crucial issue of drive beam stability. The main sources of drifts and instabilities have been identified and mitigated, helping to improve the machine performance and showing significant progress towards the experimental demonstration of the very stringent requirements on current, energy and phase stability needed in CLIC. In this paper, the more effective techniques and feed-backs are summarized. The latest measurements on beam stability are reported and their relevance to CLIC is discussed.

  17. RF Design of the TW Buncher for the CLIC Drive Beam Injector (2nd report)

    CERN Document Server

    Shaker, Hamed

    2016-01-01

    CLIC is based on the two beams concept that one beam (drive beam) produces the required RF power to accelerate another beam (main beam). The drive beam is produced and accelerated up to 50MeV inside the CLIC drive beam injector. The drive beam injector main components are a thermionic electron gun, three sub-harmonic bunchers, a pre-buncher, a TW buncher, 13 accelerating structures and one magnetic chicane. This document is the second report of the RF structure design of the TW buncher. This design is based on the beam dynamic design done by Shahin Sanaye Hajari due to requirements mentioned in CLIC CDR. A disk-loaded tapered structure is chosen for the TW buncher. The axial electric field increases strongly based on the beam dynamic requirements. This second report includes the study of HOM effects, retuning the cells, study of dimensional tolerances and the heat dissipation on the surface.

  18. Plasma heating and current drive using intense, pulsed microwaves

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B.I.; Cohen, R.H.; Nevins, W.M.; Rognlien, T.D.; Bonoli, P.T.; Porkolab, M.

    1988-01-01

    The use of powerful new microwave sources, e.g., free-electron lasers and relativistic gyrotrons, provide unique opportunities for novel heating and current-drive schemes in the electron-cyclotron and lower-hybrid ranges of frequencies. These high-power, pulsed sources have a number of technical advantages over conventional, low-intensity sources; and their use can lead to improved current-drive efficiencies and better penetration into a reactor-grade plasma in specific cases. The Microwave Tokamak Experiment at Lawrence Livermore National Laboratory will provide a test for some of these new heating and current-drive schemes. This paper reports theoretical progress both in modeling absorption and current drive for intense pulses and in analyzing some of the possible complications that may arise, e.g., parametric instabilities and nonlinear self-focusing. 22 refs., 9 figs., 1 tab.

  19. Microstructure cantilever beam for current measurement

    Directory of Open Access Journals (Sweden)

    M.T.E. Khan

    2010-01-01

    Full Text Available Most microelectromechanical systems (MEMS sensors are based on the microcantilever technology, which uses a broad range of design materials and structures. The benefit ofMEMStechnology is in developing devices with a lower cost, lower power consumption, higher performance and greater integration. A free-end cantilever beam with a magnetic material mass has been designed using MEMS software tools. The magnetic material was used to improve the sensitivity of the cantilever beam to an externally-applied magnetic field. The cantilever was designed to form a capacitance transducer, which consisted of variable capacitance where electrical and mechanical energies were exchanged. The aim of this paper was to analyse the system design of the microcantilever when subjected to a magnetic field produced by a current-carrying conductor. When the signal, a sinusoidal current with a constant frequency, was applied, the cantilever beam exhibited a vibration motion along the vertical axis when placed closer to the line current. This motion created corresponding capacitance changes and generated a voltage output proportional to the capacitive change in the signal-processing circuitry attached to the microcantilever. The equivalent massspring system theory was used to describe and analyse the effect of the natural frequency of the system vibrations and motion due to the applied magnetic field, in a single-degree of freedom. The main application of this microcantilever is in current measurements to develop a non-contact current sensor mote.

  20. SNS Ring and RTBT Beam Current Monitor

    Science.gov (United States)

    Blokland, W.; Armstrong, G.; Deibele, C.; Pogge, J.; Gaidash, V.

    2006-11-01

    The SNS Diagnostics Group has implemented Beam Current Monitors (BCM) for the Ring and RTBT (Ring to Target Beam Transferline). In the Ring, the BCM must handle a thousand-fold increase of intensity during the accumulation, and in the RTBT, the BCM must communicate the integrated charge of the beam pulse in real-time for every shot to the target division for correlation with the produced neutrons. This paper describes the development of a four channel solution for the Ring BCM and the use of FPGA for the RTBT BCM to deliver the total charge to the target over a fiber optic network. Both system versions are based on the same commercial digitizer board.

  1. Wavelength Detuning Cross-Beam Energy Transfer Mitigation for Polar Direct Drive and Symmetric Direct Drive

    Science.gov (United States)

    Marozas, J. A.; Collins, T. J. B.; McKenty, P. W.; Radha, P. B.; Hohenberger, M.; Rosenberg, M. J.

    2016-10-01

    Cross-beam energy transfer (CBET) results from two-beam energy exchange via stimulated Brillouin scattering, which reduces absorbed light and implosion velocity, alters time-resolved scattered-light spectra, and redistributes absorbed and scattered light. These effects reduce target performance in polar direct drive (PDD) and symmetric direct drive (SDD) at the National Ignition Facility (NIF) and on the OMEGA Laser System. The CBET package (Adaawam) incorporated into the 2-D hydrodynamics code DRACO is an integral part of the 3-D ray-trace package (Mazinisin). Detuning the initial laser wavelength (dλ0) reduces the CBET interaction volume, which can be combined with other mitigation domains (e.g., spatial and temporal). Recent PDD experiments on the NIF explored this option using a cone-swapping technique with dλ0 = +/- 2.34 Å UV, which are compared with DRACO simulations. DRACO simulations of wavelength detuning in SDD on OMEGA predict the expected mitigation using OMEGA's three main amplifier chains in both near-term dλ0 = { - 3 , 0 , + 3 } -Å and long-term dλ0 = { - 6 , 0 , + 6 } -Å UV configurations. The detuning simulations predict improved performance and changes in 2-D and 3-D morphology in both PDD and SDD. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  2. Advanced induction motor drive control with single current sensor

    Directory of Open Access Journals (Sweden)

    Adžić Evgenije M.

    2016-01-01

    Full Text Available This paper proposes induction motor drive control method which uses minimal number of sensors, providing only DC-link current as a feedback signal. Improved DC-link current sampling scheme and modified asymmetrical switching pattern cancels characteristic waveform errors which exist in all three reconstructed motor line-currents. Motor linecurrent harmonic content is reduced to an acceptable level, eliminating torque and speed oscillations which were inherent for conventional single sensor drives. Consequently, use of single current sensor and line-current reconstruction technique is no longer acceptable only for low and medium performance drives, but also for drives where priority is obtaining a highly accurate, stable and fast response. Proposed control algorithm is validated using induction motor drive hardware prototype based on TMS320F2812 digital signal processor. [Projekat Ministarstva nauke Republike Srbije, br. III 042004 and by the Provincial Secretariat for Science and Technological Development of AP Vojvodina under contract No. 114-451-3508/2013-04

  3. Current status of the LBNE neutrino beam

    CERN Document Server

    Moore, Craig Damon; Crowley, Cory Francis; Hurh, Patrick; Hylen, James; Lundberg, Byron; Marchionni, Alberto; McGee, Mike; Mokhov, Nikolai V; Papadimitriou, Vaia; Plunkett, Rob; Reitzner, Sarah Diane; Stefanik, Andrew M; Velev, Gueorgui; Williams, Karlton; Zwaska, Robert Miles

    2015-01-01

    The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab. The facility is designed to aim a beam of neutrinos toward a detector placed in South Dakota. The neutrinos are produced in a three-step process. First, protons from the Main Injector hit a solid target and produce mesons. Then, the charged mesons are focused by a set of focusing horns into the decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined by an amalgam of the physics goals, the Monte Carlo modeling of the facility, and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ~700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW. The LBNE Neutrino Beam has made significant changes to the initial design through consideration of numerous Value Engineering proposals and the current design is described.

  4. Current drive experiments in the Helicity Injected Torus - II

    Science.gov (United States)

    Hamp, W. T.; Redd, A. J.; Jarboe, T. R.; Nelson, B. A.; O'Neill, R. G.; Raman, R.; Sieck, P. E.; Smith, R. J.; Mueller, D.

    2006-10-01

    The HIT-II spherical torus (ST) device has demonstrated four toroidal plasma current drive configurations to form and sustain a tokamak: 1) inductive (ohmic) current drive, 2) coaxial helicity injection (CHI) current drive, 3) CHI initiated plasmas with ohmic sustainment (CHI+OH), and 4) ohmically initiated plasmas with CHI edge current drive (OH+ECD). CHI discharges with a sufficiently high ratio of injector current to toroidal field current form a closed flux core, and amplify the injector poloidal flux through magnetic reconnection. CHI+OH plasmas are more robust than unassisted ohmic discharges, with a wider operating space and more efficient use of the transformer Volt-seconds. Finally, edge CHI can enhance the plasma current of an ohmic discharge without significantly degrading the quality of the discharge. Results will be presented for each HIT-II operating regime, including empirical performance scalings, applicable parametric operating spaces, and requirements to produce these discharges. Thomson scattering measurements and EFIT simulations are used to evaluate confinement in several representative plasmas. Finally, we outline extensions to the HIT-II CHI studies that could be performed with NSTX, SUNIST, or other ST devices.

  5. Current Control in ITER Steady State Plasmas With Neutral Beam Steering

    Energy Technology Data Exchange (ETDEWEB)

    R.V. Budny

    2009-09-10

    Predictions of quasi steady state DT plasmas in ITER are generated using the PTRANSP code. The plasma temperatures, densities, boundary shape, and total current (9 - 10 MA) anticipated for ITER steady state plasmas are specified. Current drive by negative ion neutral beam injection, lower-hybrid, and electron cyclotron resonance are calculated. Four modes of operation with different combinations of current drive are studied. For each mode, scans with the NNBI aimed at differing heights in the plasma are performed to study effects of current control on the q profile. The timeevolution of the currents and q are calculated to evaluate long duration transients. Quasi steady state, strongly reversed q profiles are predicted for some beam injection angles if the current drive and bootstrap currents are sufficiently large.

  6. Numerical modeling of lower hybrid heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Valeo, E.J.; Eder, D.C.

    1986-03-01

    The generation of currents in toroidal plasma by application of waves in the lower hybrid frequency range involves the interplay of several physical phenomena which include: wave propagation in toroidal geometry, absorption via wave-particle resonances, the quasilinear generation of strongly nonequilibrium electron and ion distribution functions, and the self-consistent evolution of the current density in such a nonequilibrium plasma. We describe a code, LHMOD, which we have developed to treat these aspects of current drive and heating in tokamaks. We present results obtained by applying the code to a computation of current ramp-up and to an investigation of the possible importance of minority hydrogen absorption in a deuterium plasma as the ''density limit'' to current drive is approached.

  7. Research on Predicting Drive Current of Shipborne Satcom Antenna

    Directory of Open Access Journals (Sweden)

    Kong Jinping

    2015-01-01

    Full Text Available Predicting the effect of antenna wind load on servo system precisely is meaningful to ensure the safety of satcom antenna on operation, which can avoid overload operation. In this paper, the computational fluid dynamics is used to proceed numerical computation on the pressure distribution of the reflector and torque of drive shaft under different wind speed, windward angle and angle of pitch of the antenna. The simulation model is built under MATLAB/Simulink simulation environment, and the drive current of the antenna servo system is analyzed under wind load effect and ship swing. Then, a method of predicting drive current of antenna servo system according to the wind speed, wind direction and attitude of the antenna is concluded. And this method is verified by simulation at last.

  8. The PHIN photoinjector for the CTF3 Drive beam

    CERN Document Server

    Losito, R; Braun, H; Champault, N; Chevallay, E; Divall, M; Fedosseev, V; Hirst, G; Kumar, A; Kurdi, G; Martin, W; Masi, A; Mercier, B; Musgrave, I; Prevost, C; Ross, I; Roux, R; Springate, E; Suberlucq, Guy

    2006-01-01

    A new photoinjector for the CTF3 drive beam has been designed and is now being constructed by a collaboration among LAL, CCLRC and CERN within PHIN, the second Joint Research Activity of CARE. The photoinjector will provide a train of 2332 pulses at 1.5 GHz with a complex timing structure (sub-trains of 212 pulses spaced from one another by 333 ps or 999 ps) to allow the frequency multiplication scheme, which is one of the features of CLIC, to be tested in CTF3. Each pulse of 2.33 nC will be emitted by a Cs2Te photocathode deposited by a co-evaporation process to allow high quantum efficiency in operation (>3% for a minimum of 40 h). The 3 GHz, 2 1/2 cell RF gun has a 2 port coupler to minimize emittance growth due to asymmetric fields, racetrack profile of the irises and two solenoids to keep the emittance at the output below 20 p.mm.mrad. The laser has to survive very high average powers both within the pulse train (15 kW) and overall (200 W before pulse slicing). Challenging targets are also for amplitude ...

  9. Disturbance observer based current controller for vector controlled IM drives

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Dal, Mehmet

    2008-01-01

    In order to increase the accuracy of the current control loop, usually, well known parameter compensation and/or cross decoupling techniques are employed for advanced ac drives. In this paper, instead of using these techniques an observer-based current controller is proposed for vector controlled...... coupling effects and increase robustness against parameters change without requiring any other compensation strategies. The experimental implementation results are provided to demonstrate validity and performance of the proposed control scheme.......In order to increase the accuracy of the current control loop, usually, well known parameter compensation and/or cross decoupling techniques are employed for advanced ac drives. In this paper, instead of using these techniques an observer-based current controller is proposed for vector controlled...

  10. Enhanced Lower Hybrid Current Drive Experiments on HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Effective Lower Hybrid Current Driving (LHCD) and improved confinement exper-iments in higher plasma parameters (Ip > 200 kA, ne> 2×1013 cm-3, Te ≥ 1 keⅤ) havebeen curried out in optimized LH wave spectrum and plasma parameters in HT-7 supercon-ducting tokamak. The dependence of current driving efficiency on LH power spectrum, plasmadensity ne and toroidal magnetic field BT has been obtained under optimal conditions. A goodCD efficiency was obtained at higher plasma current and higher electron density. The improve-ment of the energy confinement time is accompanied with the increase in line averaged electrondensity, and in ion and electron temperatures. The highest current driving efficiency reachedηCD = IpneR/PRF ≈ 1.05 × 1019 Am-2/W. Wave-plasma coupling was sustained in a good stateand the reflective coefficient was less than 5%. The experiments have also demonstrated the abilityof LH wave in the start-up and ramp-up of the plasma current. The measurement of the temporaldistribution of plasma parameter shows that lower hybrid leads to a broader profile in plasmaparameter. The LH power deposition profile and the plasma current density profile were modeledwith a 2D Fokker-Planck code corresponding to the evolution process of the hard x-ray detectorarray.

  11. Study of lower hybrid current drive for the demonstration reactor

    Energy Technology Data Exchange (ETDEWEB)

    Molavi-Choobini, Ali Asghar [Dept. of Physics, Faculty of Engineering, Islamic Azad University, Shahr-e-kord Branch, Shahr-e-kord (Iran, Islamic Republic of); Naghidokht, Ahmed [Dept. of Physics, Urmia University, Urmia (Iran, Islamic Republic of); Karami, Zahra [Dept. of Engineering, Islamic Azad University, Zanjan Branch, Zanjan (Iran, Islamic Republic of)

    2016-06-15

    Steady-state operation of a fusion power plant requires external current drive to minimize the power requirements, and a high fraction of bootstrap current is required. One of the external sources for current drive is lower hybrid current drive, which has been widely applied in many tokamaks. Here, using lower hybrid simulation code, we calculate electron distribution function, electron currents and phase velocity changes for two options of demonstration reactor at the launched lower hybrid wave frequency 5 GHz. Two plasma scenarios pertaining to two different demonstration reactor options, known as pulsed (Option 1) and steady-state (Option 2) models, have been analyzed. We perceive that electron currents have major peaks near the edge of plasma for both options but with higher efficiency for Option 1, although we have access to wider, more peripheral regions for Option 2. Regarding the electron distribution function, major perturbations are at positive velocities for both options for flux surface 16 and at negative velocities for both options for flux surface 64.

  12. Electric machine and current source inverter drive system

    Science.gov (United States)

    Hsu, John S

    2014-06-24

    A drive system includes an electric machine and a current source inverter (CSI). This integration of an electric machine and an inverter uses the machine's field excitation coil for not only flux generation in the machine but also for the CSI inductor. This integration of the two technologies, namely the U machine motor and the CSI, opens a new chapter for the component function integration instead of the traditional integration by simply placing separate machine and inverter components in the same housing. Elimination of the CSI inductor adds to the CSI volumetric reduction of the capacitors and the elimination of PMs for the motor further improve the drive system cost, weight, and volume.

  13. Physics of electron cyclotron current drive on DIII-D

    CERN Document Server

    Petty, C C; Harvey, R W; Kinsey, J E; Lao, L L; Lohr, J; Luce, T C; Makowski, M A; Prater, R

    2002-01-01

    OAK A271 PHYSICS OF ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. Recent experiments on the DIII-D tokamak have focused on determining the effect of trapped particles on the electron cyclotron current drive (ECCD) efficiency. The measured ECCD efficiency increases as the deposition location is moved towards the inboard midplane or towards smaller minor radius for both co and counter injection. The measured ECCD efficiency also increases with increasing electron density and/or temperature. The experimental ECCD is compared to both the linear theory (Toray-GA) as well as a quasilinear Fokker-Planck model (CQL3D). The experimental ECCD is found to be in better agreement with the more complete Fokker-Planck calculation, especially for cases of high rf power density and/or loop voltage. The narrow width of the measured ECCD profile is consistent with only low levels of radial transport for the current carrying electrons.

  14. Fast wave current drive antenna performance on D3-D

    Science.gov (United States)

    Mayberry, M. J.; Pinsker, R. I.; Petty, C. C.; Chiu, S. C.; Jackson, G. L.; Lippmann, S. I.; Prater, R.; Porkolab, M.

    1991-10-01

    Fast wave current drive (FWCD) experiments at 60 MHz are being performed on the D3-D tokamak for the first time in high electron temperature, high (beta) target plasmas. A four-element phased-array antenna is used to launch a directional wave spectrum with the peak n(sub parallel) value (approximately = 7) optimized for strong single-pass electron absorption due to electron Landau damping. For this experiment, high power FW injection (2 MW) must be accomplished without voltage breakdown in the transmission lines or antenna, and without significant impurity influx. In addition, there is the technological challenge of impedance matching a four-element antenna while maintaining equal currents and the correct phasing (90 degrees) in each of the straps for a directional spectrum. We describe the performance of the D3-D FWCD antenna during initial FW electron heating and current drive experiments in terms of these requirements.

  15. Fast Wave Current Drive Antenna Performance on DIII-D

    Science.gov (United States)

    Mayberry, M. J.; Pinsker, R. I.; Petty, C. C.; Chiu, S. C.; Jackson, G. L.; Lippmann, S. I.; Porkolab, M.; Prater, R.; Baity, F. W.; Goulding, R. H.; Hoffman, D. J.

    1992-01-01

    Fast wave current drive (FWCD) experiments at 60 MHz are being performed on the DIII-D tokamak for the first time in high electron temperature, high β target plasmas. A four-element phased-array antenna is used to launch a directional wave spectrum with the peak n∥ value (≂7) optimized for strong single-pass electron absorption due to electron Landau damping. For this experiment, high power FW injection (2 MW) must be accomplished without voltage breakdown in the transmission lines or antenna, and without significant impurity influx. In addition, there is the technological challenge of impedance matching a four-element antenna while maintaining equal currents and the correct phasing (90°) in each of the straps for a directional spectrum. In this paper we describe the performance of the DIII-D FWCD antenna during initial FW electron heating and current drive experiments in terms of these requirements.

  16. Current drive at plasma densities required for thermonuclear reactors.

    Science.gov (United States)

    Cesario, R; Amicucci, L; Cardinali, A; Castaldo, C; Marinucci, M; Panaccione, L; Santini, F; Tudisco, O; Apicella, M L; Calabrò, G; Cianfarani, C; Frigione, D; Galli, A; Mazzitelli, G; Mazzotta, C; Pericoli, V; Schettini, G; Tuccillo, A A

    2010-08-10

    Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors.

  17. An Imposed Dynamo Current Drive Experiment: Demonstration of Confinement

    Science.gov (United States)

    Jarboe, Thomas; Hansen, Chris; Hossack, Aaron; Marklin, George; Morgan, Kyle; Nelson, Brian; Sutherland, Derek; Victor, Brian

    2014-10-01

    An experiment for studying and developing the efficient sustainment of a spheromak with sufficient confinement (current-drive power heats the plasma to its stability β-limit) and in the keV temperature range is discussed. A high- β spheromak sustained by imposed dynamo current drive (IDCD) is justified because: previous transient experiments showed sufficient confinement in the keV range with no external toroidal field coil; recent results on HIT-SI show sustainment with sufficient confinement at low temperature; the potential of IDCD of solving other fusion issues; a very attractive reactor concept; and the general need for efficient current drive in magnetic fusion. The design of a 0.55 m minor radius machine with the required density control, wall loading, and neutral shielding for a 2 s pulse is presented. Peak temperatures of 1 keV and toroidal currents of 1.35 MA and 16% wall-normalized plasma beta are envisioned. The experiment is large enough to address the key issues yet small enough for rapid modification and for extended MHD modeling of startup and code validation.

  18. Brushless DC motor Drive during Speed regulation with Current Controller

    Directory of Open Access Journals (Sweden)

    Bhikshalu Manchala

    2015-04-01

    Full Text Available Brushless DC Motor (BLDC is one of the best electrical drives that have increasing popularity, due to their high efficiency, reliability, good dynamic response and very low maintenance. Due to the increasing demand for compact & reliable motors and the evolution of low cost power semiconductor switches and permanent magnet (PM materials, brushless DC motors become popular in every application from home appliances to aerospace industry. The conventional techniques for controlling the stator phase current in a brushless DC drive are practically effective in low speed and cannot reduce the commutation torque ripple in high speed range. This paper presents the PI controller for speed control of BLDC motor. The output of the PI controllers is summed and is given as the input to the current controller. The BLDC motor is fed from the inverter where the rotor position and current controller is the input. The complete model of the proposed drive system is developed and simulated using MATLAB/Simulink software. The operation principle of using component is analysed and the simulation results are presented in this to verify the theoretical analysis.

  19. Towards fully non-inductive current drive operation in JET

    Energy Technology Data Exchange (ETDEWEB)

    Litaudon, X. [Association Euratom-CEA Cadarache, Dept. de Recherches sur la Fusion Controlee, 13 - Saint-Paul-lez-Durance (France); Crisanti, F. [Association Euratom-ENEA sulla Fusione, Centro Ricerche Frascati (Italy); Alper, B. [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom)] [and others

    2002-01-01

    Quasi steady operation has been achieved at JET in the high confinement regime with Internal Transport Barriers, ITBs. The ITBs' performances are maintained up to 11 s. This duration, much larger than the energy confinement time, is already approaching a current resistive time. The high performance phase is limited only by plant constraints. The radial profiles of the thermal electron and ion pressures have steep gradients typically at mid-plasma radius. A large fraction of non-inductive current (above 80%) is sustained throughout the high performance phase with a poloidal beta exceeding unity. The safety factor profile plays an important role in sustaining the ITB characteristics. In this regime where the self-generated bootstrap current (up to LOMA) represents 50% of the total current, the resistive evolution of the non-monotonic q-profile is slowed down by using off-axis lower hybrid current drive. (authors)

  20. Current drive for stability of thermonuclear plasma reactor

    Science.gov (United States)

    Amicucci, L.; Cardinali, A.; Castaldo, C.; Cesario, R.; Galli, A.; Panaccione, L.; Paoletti, F.; Schettini, G.; Spigler, R.; Tuccillo, A.

    2016-01-01

    To produce in a thermonuclear fusion reactor based on the tokamak concept a sufficiently high fusion gain together stability necessary for operations represent a major challenge, which depends on the capability of driving non-inductive current in the hydrogen plasma. This request should be satisfied by radio-frequency (RF) power suitable for producing the lower hybrid current drive (LHCD) effect, recently demonstrated successfully occurring also at reactor-graded high plasma densities. An LHCD-based tool should be in principle capable of tailoring the plasma current density in the outer radial half of plasma column, where other methods are much less effective, in order to ensure operations in the presence of unpredictably changes of the plasma pressure profiles. In the presence of too high electron temperatures even at the periphery of the plasma column, as envisaged in DEMO reactor, the penetration of the coupled RF power into the plasma core was believed for long time problematic and, only recently, numerical modelling results based on standard plasma wave theory, have shown that this problem should be solved by using suitable parameter of the antenna power spectrum. We show here further information on the new understanding of the RF power deposition profile dependence on antenna parameters, which supports the conclusion that current can be actively driven over a broad layer of the outer radial half of plasma column, thus enabling current profile control necessary for the stability of a reactor.

  1. Path to Efficient Lower Hybrid Current Drive at High Density

    Science.gov (United States)

    Baek, S. G.; Bonoli, P. T.; Brunner, D.; Faust, I.; Labombard, B. L.; Parker, R. R.; Shiraiwa, S.; Wallace, G. M.; Wukitch, S.

    2015-11-01

    Recovery of lower hybrid current drive (LHCD) efficiency at high density was demonstrated on Alcator C-Mod by modifying the scrape-off layer (SOL) plasma. RF probe measurements around the C-Mod tokamak indicate that the LH wave amplitude at the high field side wall significantly attenuates with plasma density. This is interpreted as enhanced collisional loss due to the increase in the SOL density and width. By taking advantage of the narrower SOL width by doubling plasma current to 1.1 MA, it is found that the LH wave amplitude maintains its strength, and an effective current drive is extended to above 1x10e20 m-3. An order of magnitude increase in non-thermal Bremsstrahlung emission is consistent with ray-tracing results which take into account the change of SOL profiles with current. In the coming campaign, a further investigation on the role of the SOL plasma is planned by raising plasma current above 1.1 MA. This will be aided with newly developed RF magnetic loop antennas mounted on a radially movable probe head. This system is expected to intercept the LH resonance cone on the first pass, allowing us to measure radial profiles of both the wave amplitude and dominant parallel wavenumber in the SOL for the first time. These data will be compared with the GENRAY ray-tracing code. Work supported by USDoE awards DE-FC02-99ER54512.

  2. Electric machine and current source inverter drive system

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, John S

    2014-06-24

    A drive system includes an electric machine and a current source inverter (CSI). This integration of an electric machine and an inverter uses the machine's field excitation coil for not only flux generation in the machine but also for the CSI inductor. This integration of the two technologies, namely the U machine motor and the CSI, opens a new chapter for the component function integration instead of the traditional integration by simply placing separate machine and inverter components in the same housing. Elimination of the CSI inductor adds to the CSI volumetric reduction of the capacitors and the elimination of PMs for the motor further improve the drive system cost, weight, and volume.

  3. Direct drive heavy-ion-beam inertial fusion at high coupling efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Logan, B.G.; Perkins, L.J.; Barnard, J.J.

    2008-05-16

    Issues with coupling efficiency, beam illumination symmetry, and Rayleigh-Taylor instability are discussed for spherical heavy-ion-beam-driven targets with and without hohlraums. Efficient coupling of heavy-ion beams to compress direct-drive inertial fusion targets without hohlraums is found to require ion range increasing several-fold during the drive pulse. One-dimensional implosion calculations using the LASNEX inertial confinement fusion target physics code shows the ion range increasing fourfold during the drive pulse to keep ion energy deposition following closely behind the imploding ablation front, resulting in high coupling efficiencies (shell kinetic energy/incident beam energy of 16% to 18%). Ways to increase beam ion range while mitigating Rayleigh-Taylor instabilities are discussed for future work.

  4. Electron cyclotron heating and current drive in toroidal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Kritz, A.H.

    1991-11-01

    The Principal Investigator has continued to work on problems associated both with the deposition and with the emission of electron cyclotron power in toroidal plasmas. We have investigated the use of electron cyclotron resonance heating for bringing compact tokamaks (BPX) to ignition-like parameters. This requires that we continue to refine the modeling capability of the TORCH code linked with the BALDUR 1 {1/2} D transport code. Using this computational tool, we have examined the dependence of ignition on heating and transport employing both theoretical (multi-mode) and empirically based transport models. The work on current drive focused on the suppression of tearing modes near the q = 2 surface and sawteeth near the q = 1 surface. Electron cyclotron current drive in CIT near the q =2 surface was evaluated for a launch scenario where electron cyclotron power was launched near the equatorial plane. The work on suppression of sawteeth has been oriented toward understanding the suppression that has been observed in a number of tokamaks, in particular, in the WT-3 tokamak in Kyoto. To evaluate the changes in current profile (shear) near the q =1 surface, simulations have been carried out using the linked BALDUR-TORCH code. We consider effects on shear resulting both from wave-induced current as well as from changes in conductivity associated with changes in local temperature. Abstracts and a paper relating to this work is included in Appendix A.

  5. Potential of ion cyclotron resonance frequency current drive via fast waves in DEMO

    Science.gov (United States)

    Kazakov, Ye O.; Van Eester, D.; Wauters, T.; Lerche, E.; Ongena, J.

    2015-02-01

    For the continuous operation of future tokamak-reactors like DEMO, non-inductively driven toroidal plasma current is needed. Bootstrap current, due to the pressure gradient, and current driven by auxiliary heating systems are currently considered as the two main options. This paper addresses the current drive (CD) potential of the ion cyclotron resonance frequency (ICRF) heating system in DEMO-like plasmas. Fast wave CD scenarios are evaluated for both the standard midplane launch and an alternative case of exciting the waves from the top of the machine. Optimal ICRF frequencies and parallel wave numbers are identified to maximize the CD efficiency. Limitations of the high frequency ICRF CD operation are discussed. A simplified analytical method to estimate the fast wave CD efficiency is presented, complemented with the discussion of its dependencies on plasma parameters. The calculated CD efficiency for the ICRF system is shown to be similar to those for the negative neutral beam injection and electron cyclotron resonance heating.

  6. Halo and tail simulations with applications to the CLIC drive beam

    CERN Document Server

    Fitterer, M; Adli, E; Burkhardt, H; Dalena, B; Rumolo, G; Schulte, D; Latina, A; Ahmed, I

    2010-01-01

    We report about generic halo and tail simulations and estimates. Previous studies weremainly focused on very high energies as relevant for the beam delivery systems of linear colliders. We have now studied, applied and extended these simulations to lower energies as relevant for the CLIC drive beam.

  7. Current drive generation based on autoresonance and intermittent trapping mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Nakach, R. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France); Gell, Y. [CET, Tel-Aviv (Israel)

    1999-10-15

    Two mechanisms for generating streams of high parallel velocity of electrons are presented. One has its origin in Autoresonance (AR) interaction taking place after a trapping conditioning stage, the second being dominated by the trapping itself. These mechanisms are revealed from the study of the relativistic motion of an electron in a configuration consisting of two counterpropagating electromagnetic waves along a uniform magnetic field in a dispersive medium. The operation of these mechanisms was found to circumvent the deterioration of the electron acceleration process which is characteristic for a dispersive medium, allowing for an effective generation of current drive. (author)

  8. Fluid equations in the presence of electron cyclotron current drive

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Thomas G.; Kruger, Scott E. [Tech-X Corporation, 5621 Arapahoe Avenue, Boulder, Colorado 80303 (United States)

    2012-12-15

    Two-fluid equations, which include the physics imparted by an externally applied radiofrequency source near electron cyclotron resonance, are derived in their extended magnetohydrodynamic forms using the formalism of Hegna and Callen [Phys. Plasmas 16, 112501 (2009)]. The equations are compatible with the closed fluid/drift-kinetic model developed by Ramos [Phys. Plasmas 17, 082502 (2010); 18, 102506 (2011)] for fusion-relevant regimes with low collisionality and slow dynamics, and they facilitate the development of advanced computational models for electron cyclotron current drive-induced suppression of neoclassical tearing modes.

  9. High current precision long pulse electron beam position monitor

    CERN Document Server

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

    2000-01-01

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

  10. Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility

    Energy Technology Data Exchange (ETDEWEB)

    Adonin, A. A., E-mail: a.adonin@gsi.de; Hollinger, R. [Linac and Operations/Ion Sources, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany)

    2014-02-15

    In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

  11. Lower hybrid current drive for edge current density modification in DIII-D: Final status report

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermacher, M.E. [Lawrence Livermore National Lab., CA (United States); Porkolab, M. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center

    1993-08-04

    Application of Lower Hybrid (LH) Current Drive (CD) in the DIII-D tokamak has been studied at LLNL, off and on, for several years. The latest effort began in February 1992 in response to a letter from ASDEX indicating that the 2.45 GHz, 3 MW system there was available to be used on another device. An initial assessment of the possible uses for such a system on DIII-D was made and documented in September 1992. Multiple meetings with GA personnel and members of the LH community nationwide have occurred since that time. The work continued through the submission of the 1995 Field Work Proposals in March 1993 and was then put on hold due to budget limitations. The purpose of this document is to record the status of the work in such a way that it could fairly easily be restarted at a future date. This document will take the form of a collection of Appendices giving both background and the latest results from the FY 1993 work, connected by brief descriptive text. Section 2 will describe the final workshop on LHCD in DIII-D held at GA in February 1993. This was an open meeting with attendees from GA, LLNL, MIT and PPPL. Summary documents from the meeting and subsequent papers describing the results will be included in Appendices. Section 3 will describe the status of work on the use of low frequency (2.45 GHZ) LH power and Parametric Decay Instabilities (PDI) for the special case of high dielectric in the edge regions of the DIII-D plasma. This was one of the critical issues identified at the workshop. Other potential issues for LHCD in the DIII-D scenarios are: (1) damping of the waves on fast ions from neutral beam injection, (2) runaway electrons in the low density edge plasma, (3) the validity of the WKB approximation used in the ray-tracing models in the steep edge density gradients.

  12. Recent experimental results of KSTAR RF heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. J., E-mail: sjwang@nfri.re.kr; Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G. [National Fusion Research Institute, Daejoen, 305-806 (Korea, Republic of)

    2015-12-10

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  13. Fast Beam Current Change Monitor for the LHC

    CERN Document Server

    Kral, Jan

    Stringent demands on the LHC safety and protection systems require improved methods of detecting fast beam losses. The Fast Beam Current Transformer (FBCT) is a measurement instrument, providing information about bunch-to-bunch intensity of the accelerated beam. This thesis describes the development of a new protection system based on the FBCT signal measurements. This system, the Fast Beam Current Change Monitor (FBCCM), measures the FBCT signal in a narrow frequency band and computes time derivation of the beam signal magnitude. This derivation is proportional to the beam losses. When the losses exceed a certain level, the FBCCM requests a beam dump in order to protect the LHC. The LHC protection will be ensured by four FBCCMs which will be installed into the LHC in July 2014. Six FBCCMs have been already constructed and their characteristics were measured with satisfactory results. The FBCCMs were tested by a laboratory simulation of the real LHC environment.

  14. Current status of HESYRL lithography beam line

    Science.gov (United States)

    Qian, Shinan; Li, Guihe; Liu, Zewen; Chen, Qianhong; Jiang, Dikui; kan, Ya; Liu, Wanpo

    1990-06-01

    A lithography beam line, as the first of possibly six or more, has been installed in the Hefei Synchrotron Radiation Laboratory (HESYRL). A scanning mirror is used to cut off shorter wavelengths and to expand exposure dimensions vertically. The scanning mirror is oscillated by a stepping motor while an in-situ Moirè fringe grating system measures motor speed uniformity. Some testing results are given. In the first part of the beam line, there is a beryllium window to block longer wavelength light, a laser alignment unit to align the beam line and a special exposure shutter, which is controlled by another stepping motor. An exposure chamber with vacuum of 5 × 10-7 torr is located 7 meters downstream from the source point. Because there is no window at the entrance of the chamber, a differential pumping system is needed. The chamber is equipped with a mask-wafer system, driven by a third stepping motor.

  15. Beam dynamics simulations for linacs driving short-wavelength FELs

    Energy Technology Data Exchange (ETDEWEB)

    Ferrario, M.; Tazzioli, F. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori nazionali di Frascati; Serafini, L. [Milan Univ., Milan (Italy); Istituto Nazionale di Fisica Nucleare, Milan (Italy)

    1999-07-01

    The fast code HOMDYN has been recently developed, in the framework of the TTF (Tesla test facility) collaboration, in order to study the beam dynamics of linacs delivering high brightness beams as those needed for short wavelength Fel experiments. These linacs are typically driven by radio-frequency photo-injectors, where correlated time dependent space charge effects are of great relevance: these effects cannot be studied by standard beam optics codes (TRACE3D, etc.) and they have been modeled so far by means of multi-particle (Pic or quasistatic) codes requiring heavy cpu time and memory allocations. HOMDYN is able to describe the beam generation at the photo-cathode and the emittance compensation process in the injector even running on a laptop with very modest running rimes (less than a minute). In this paper it is showed how this capability of the code is exploited so to model a whole linac up to the point where the space charge dominated regime is of relevance (200 MeV).

  16. Current drive generation based on autoresonance and intermittent trapping mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Nakach, R. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France); Gell, Y. [CET, Israel(Israel)

    1999-04-01

    Two mechanisms for generating stream of high velocity of electrons are presented. One has its origin in Auto Resonance interaction (AR) which takes place in the system after a trapping conditioning stage, the second being dominated by the trapping process itself. These mechanisms are revealed from the study of the relativistic motion of an electron in a configuration consisting of two counterpropagating electromagnetic waves along a constant magnetic field in a dispersive medium. Using a Hamiltonian formalism, we have numerically solved the equations of motion and presented the results in a set of figures showing the generation of stream of electrons having high parallel velocities. Insight into these numerical results is gained from a theoretical analysis which consists of a reformulation of the equations of motion. The operation of these mechanisms was found to circumvent the deterioration of the electron acceleration process which is characteristic for a dispersive medium, allowing for an effective generation of current drive. Discussion of the results follows. (author)

  17. Enhancing the accelerated beam current in the booster synchrotron by optimizing the transport line beam propagation

    Indian Academy of Sciences (India)

    Saini R S; Tyagi Y; Ghodke A D; Puntambekar T A

    2016-04-01

    In this paper, we present the results of transverse beam emittance and twiss parameter measurement of an electron beam, delivered by a 20 MeV microtron which is used as a pre-injector system for a booster synchrotron in the Indus Accelerator Facility at RRCAT Indore. Based on these measured beam parameters, beam optics of a transport line was optimized and its results are alsodiscussed in this paper. This beam transport line is used to transport the electron beam from the 20MeV microtron to the booster synchrotron. The booster synchrotron works as a main injector for Indus-1 and Indus-2 synchrotron radiation facilities. To optimize the beam optics of a transport linefor proper beam transmission through the line as well as to match the beam twiss parameters at the beam injection point of another accelerator, it is necessary to know the transverse beam emittance and twiss parameters of the beam coming from the first one. A MATLAB-based GUI program has been developed to calculate the beam emittance and twiss parameters, using quadrupole scanmethod. The measured parameters have been used for beam transport line optimization and twiss parameters matching at booster injection point. After this optimization, an enhancement of ∼50% beam current has been observed in the booster synchrotron.

  18. Integrated Plasma Simulation of Lower Hybrid Current Drive in Tokamaks

    Science.gov (United States)

    Bonoli, P. T.; Wright, J. C.; Harvey, R. W.; Batchelor, D. B.; Berry, L. A.; Kessel, C. E.; Jardin, S. C.

    2012-03-01

    It has been shown in Alcator C-Mod that the onset time for sawteeth can be delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through the injection of off-axis LH current drive power [1]. We are simulating these experiments using the Integrated Plasma Simulator (IPS) [2], where the driven LH current density profiles are computed using a ray tracing component (GENRAY) and Fokker Planck code (CQL3D) [3] that are run in a tightly coupled time advance. The background plasma is evolved using the TSC transport code with the Porcelli sawtooth model [4]. Predictions of the driven LH current profiles will be compared with simpler ``reduced'' models for LHCD such as the LSC code which is implemented in TSC and which is also invoked within the IPS. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, J. Comp. Phys. 66, 481 (1986).

  19. Heating and Current Drive by Electron Cyclotron Waves

    Science.gov (United States)

    Prater, R.

    2003-10-01

    The physics model of electron cyclotron heating (ECH) and current drive (ECCD) is becoming well validated through systematic comparisons of theory and experiment. Work has shown that ECCD can be highly localized and robustly controlled, leading to applications including stabilization of MHD instabilities like neoclassical tearing modes, control and sustainment of desired profiles of current density and plasma pressure, and studies of localized transport. These physics applications and the study of the basic physics of ECH and ECCD were enabled by the advent of the gyrotron in the 1980s and of the diamond window for megawatt gyrotrons in the 1990s. The experimental work stimulated a broad base of theory based on first principles which is encapsulated in linear ray tracing codes and fully relativistic quasilinear Fokker-Planck codes. Recent experiments use measurements of the local poloidal magnetic field through the motional Stark effect to determine the magnitude and profile of the locally driven current. The subtle balance between wave-induced diffusion and Coulomb relaxation in velocity space provides an understanding of the effects of trapping of current-carrying electrons in the magnetic well, an effect which can be used to advantage. Strong quasilinear effects and radial transport of electrons which may broaden the driven current profile have also been observed under some conditions and appear to be consistent with theory, but in large devices these are usually insignificant. Additional advantages of ECH compared with other rf heating methods are that the antenna can be far removed from the plasma and the power density can be very high. The agreement of theory and experiment, the broad base of established applications, and the technical advantages of ECH support the application of ECH in next-step tokamaks and stellarators.

  20. Studies of Cs3Sb cathodes for the CLIC drive beam photo injector option

    CERN Document Server

    Martini, Irene; Doebert, Steffen; Fedosseev, Valentine; Hessler, Christoph; Martyanov, Mikhail

    2013-01-01

    Within the CLIC (Compact Linear Collider) project, feasibility studies of a photo injector option for the drive beam as an alternative to its baseline design using a thermionic electron gun are on-going. This R&D program covers both the laser and the photocathode side. Whereas the available laser pulse energy in ultra-violet (UV) is currently limited by the optical defects in the 4thharmonics frequency conversion crystal induced by the0.14 ms long pulse trains, recent measurements of Cs3Sbphotocathodes sensitive to green light showed their potential to overcome this limitation. Moreover, using visible laser beams leads to better stability of produced electron bunches and one can take advantages of the availability of higher quality optics. The studied Cs3Sbphotocathodes have been produced in the CERN photo emission laboratory using the co-deposition technique and tested in a DC gun set-up. The analysis of data acquired during the cathode production process will be presented in this paper, as well as the r...

  1. Conditions for Lower Hybrid Current Drive in ITER

    Science.gov (United States)

    Cesario, R.; Amicucci, L.; Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Napoli, F.; Tuccillo, A. A.; Galli, A.; Schettini, G.

    2012-12-01

    To control the plasma current profile represents one of the most important problems of the research of nuclear fusion energy based on the tokamak concept, as in the plasma column the necessary conditions of stability and confinement should be satisfied. This problem can be solved by using the lower hybrid current drive (LHCD) effect, which was demonstrated to occur also at reactor grade high plasma densities provided that a proper method should be utilised, as assessed on FTU (Frascati Tokamak Upgrade). This method, based on theoretical predictions confirmed by experiment, produces relatively high electron temperature at the plasma periphery and scrape-off layer (SOL), consequently reducing the broadening of the spectrum launched by the antenna produced by parasitic wave physics of the edge, namely parametric instability (PI). The new results presented here show that, for kinetic profiles now foreseen for the SOL of ITER, PI is expected to hugely broaden the antenna spectrum and prevent any penetration in the core of the coupled LH power. However, considering the FTU method and assuming higher electron temperature at the edge (which would be however reasonable for ITER) the PI-produced spectral broadening would be mitigated, and enable the penetration of the coupled LH power in the main plasma. By successful LHCD effect, the control of the plasma current profile at normalised minor radius of about 0.8 would be possible, with much higher efficiency than that obtainable by other tools. A very useful reinforce of bootstrap current effects would be thus possible by LHCD in ITER.

  2. Limiting current of intense electron beams in a decelerating gap

    Science.gov (United States)

    Nusinovich, G. S.; Beaudoin, B. L.; Thompson, C.; Karakkad, J. A.; Antonsen, T. M.

    2016-02-01

    For numerous applications, it is desirable to develop electron beam driven efficient sources of electromagnetic radiation that are capable of producing the required power at beam voltages as low as possible. This trend is limited by space charge effects that cause the reduction of electron kinetic energy and can lead to electron reflection. So far, this effect was analyzed for intense beams propagating in uniform metallic pipes. In the present study, the limiting currents of intense electron beams are analyzed for the case of beam propagation in the tubes with gaps. A general treatment is illustrated by an example evaluating the limiting current in a high-power, tunable 1-10 MHz inductive output tube (IOT), which is currently under development for ionospheric modification. Results of the analytical theory are compared to results of numerical simulations. The results obtained allow one to estimate the interaction efficiency of IOTs.

  3. Lower Hybrid Current Drive Experiments in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    J.R. Wilson, S. Bernabei, P. Bonoli, A. Hubbard, R. Parker, A. Schmidt, G. Wallace, J. Wright, and the Alcator C-Mod Team

    2007-10-09

    A Lower Hybrid Current Drive (LHCD) system has been installed on the Alcator C-MOD tokamak at MIT. Twelve klystrons at 4.6 GHz feed a 4x22 waveguide array. This system was designed for maximum flexibility in the launched parallel wave-number spectrum. This flexibility allows tailoring of the lower hybrid deposition under a variety of plasma conditions. Power levels up to 900 kW have been injected into the tokomak. The parallel wave number has been varied over a wide range, n|| ~ 1.6–4. Driven currents have been inferred from magnetic measurements by extrapolating to zero loop voltage and by direct comparison to Fisch-Karney theory, yielding an efficiency of n20IR/P ~ 0.3. Modeling using the CQL3D code supports these efficiencies. Sawtooth oscillations vanish, accompanied with peaking of the electron temperature (Te0 rises from 2.8 to 3.8 keV). Central q is inferred to rise above unity from the collapse of the sawtooth inversion radius, indicating off-axis cd as expected. Measurements of non-thermal x-ray and electron cyclotron emission confirm the presence of a significant fast electron population that varies with phase and plasma density. The x-ray emission is observed to be radialy broader than that predicted by simple ray tracing codes. Possible explanations for this broader emission include fast electron diffusion or broader deposition than simple ray tracing predictions (perhaps due to diffractive effects).

  4. Lower hybrid counter current drive for edge current density modification in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermacher, M.E.; Nevins, W.M. [Lawrence Livermore National Lab., CA (US); Porkolab, M.; Bonoli, P.T. [Massachusetts Inst. of Technology, Cambridge, MA (US). Plasma Fusion Center; Harvey, R.W. [General Atomics, San Diego, CA (US)

    1993-07-01

    Each of the Advanced Tokamak operating modes in DIII-D is thought to have a distinctive current density profile. So far these modes have only been achieved transiently through experiments which ramp the plasma current and shape. Extension of these modes to steady state requires non-inductive current profile control, e.g. with lower hybrid current drive (LHCD). Calculations of LHCD have been done for DIII-D using the ACCOME and CQL3D codes, showing that counter driven current at the plasma edge can cancel some of the undesirable edge bootstrap current and potentially extend the VH-mode. Results are presented for scenarios using 2.45 GHz LH waves launched from both the midplane and off-axis ports. The sensitivity of the results to injected power, n{sub e} and T{sub e}, and launched wave spectrum is also shown.

  5. Polymorphic beams and Nature inspired circuits for optical current

    Science.gov (United States)

    Rodrigo, José A.; Alieva, Tatiana

    2016-10-01

    Laser radiation pressure is a basis of numerous applications in science and technology such as atom cooling, particle manipulation, material processing, etc. This light force for the case of scalar beams is proportional to the intensity-weighted wavevector known as optical current. The ability to design the optical current according to the considered application brings new promising perspectives to exploit the radiation pressure. However, this is a challenging problem because it often requires confinement of the optical current within tight light curves (circuits) and adapting its local value for a particular task. Here, we present a formalism to handle this problem including its experimental demonstration. It consists of a Nature-inspired circuit shaping with independent control of the optical current provided by a new kind of beam referred to as polymorphic beam. This finding is highly relevant to diverse optical technologies and can be easily extended to electron and x-ray coherent beams.

  6. ADAPTIVE CONTROL OF FLEXIBLE BEAM WITH UNKNOWN DEAD-ZONE IN THE DRIVING MOTOR

    Institute of Scientific and Technical Information of China (English)

    Wang Xingsong; Hong Henry; Su Chunyi

    2004-01-01

    Adaptive control of a flexible beam system preceded by an unknown dead-zone in the driving motor is investigated in state space form. By introducing an important lemma for simplifying error equation between the flexible beam model and the matching reference model, a robust adaptive control scheme is developed by involving the dead-zone inverse terms. The new adaptive control law ensures global stability of the entire system and achieves desired tracking precision even when the slopes of the dead-zone are not equal. Simulations performed on a typical flexible beam system illustrate and clarify the validity of this approach.

  7. Effective shielding to measure beam current from an ion source

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, H., E-mail: bayle@bergoz.com [Bergoz Instrumentation, Saint-Genis-Pouilly (France); Delferrière, O.; Gobin, R.; Harrault, F.; Marroncle, J.; Senée, F.; Simon, C.; Tuske, O. [CEA, Saclay (France)

    2014-02-15

    To avoid saturation, beam current transformers must be shielded from solenoid, quad, and RFQ high stray fields. Good understanding of field distribution, shielding materials, and techniques is required. Space availability imposes compact shields along the beam pipe. This paper describes compact effective concatenated magnetic shields for IFMIF-EVEDA LIPAc LEBT and MEBT and for FAIR Proton Linac injector. They protect the ACCT Current Transformers beyond 37 mT radial external fields. Measurements made at Saclay on the SILHI source are presented.

  8. Current ramp-up with lower hybrid current drive in EAST

    Science.gov (United States)

    Ding, B. J.; Li, M. H.; Fisch, N. J.; Qin, H.; Li, J. G.; Wilson, J. R.; Kong, E. H.; Zhang, L.; Wei, W.; Li, Y. C.; Wang, M.; Xu, H. D.; Gong, X. Z.; Shen, B.; Liu, F. K.; Shan, J. F.

    2012-12-01

    More economical fusion reactors might be enabled through the cyclic operation of lower hybrid current drive. The first stage of cyclic operation would be to ramp up the plasma current with lower hybrid waves alone in low-density plasma. Such a current ramp-up was carried out successfully on the EAST tokamak. The plasma current was ramped up with a time-averaged rate of 18 kA/s with lower hybrid (LH) power. The average conversion efficiency Pel/PLH was about 3%. Over a transient phase, faster ramp-up was obtained. These experiments feature a separate measurement of the L/R time at the time of current ramp up.

  9. Current drive generation based on autoresonance and intermittent trapping mechanisms.

    Science.gov (United States)

    Gell, Y; Nakach, R

    1999-09-01

    Two mechanisms for generating streams of high-velocity electrons are presented. One has its origin in auto resonance (AR) interaction, which takes place in the system after a trapping conditioning stage, the second being dominated by the trapping process itself. These mechanisms are revealed from the study of the relativistic motion of an electron in a configuration consisting of two counterpropagating electromagnetic waves along a constant magnetic field in a dispersive medium. Using a Hamiltonian formalism, we have numerically solved the equations of motion and presented the results in a set of figures showing the generation of streams of electrons having high parallel velocities. Insight into these numerical results is gained from a theoretical analysis, which consists of a reformulation of the equations of motion. The operation of these mechanisms was found to circumvent the deterioration of the electron acceleration process that is characteristic for a dispersive medium, thus allowing for an effective generation of a current drive. Discussion of the results follows.

  10. Online optimisation of the CLIC Drive Beam bunch train recombination at CTF3

    CERN Document Server

    AUTHOR|(CDS)2082483; Tecker, Frank

    The Compact Linear Collider (CLIC) design is the leading alternative for a future multi-TeV "e^+e^−" linear collider. One of the key aspects of the design is the use of a Drive Beam as power source for the acceleration of the colliding beams. This work is focused on the optimisation of the set-up and the operations of the CLIC Drive Beam recombination at the CLIC Test Facility (CTF3) at CERN. The main effects that may affect the beam quality during the recombination are studied, with emphasis on orbit, transverse dynamics and beam energy effects. A custom methodology is used to analyse the problem, both from a theoretical and a numerical point of view. The aim is to provide first-order orbit and transverse optics constraints, which can be used as guidelines during the set-up of the beam recombination process. The developed techniques are applied at the CTF3, and the results are reported. The non-linear beam energy effects have been investigated by means of MAD-X simulations. The results show that these effe...

  11. High-current ion beam from a moving plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, M.; John, P.K.; Ponomarenko, A.G.

    1979-05-01

    High-current ion beams in the 10--20-keV range are extracted from a moving plasma. Current densities up to 2.5 A/cm/sup 2/ are obtained at the plasma boundary, which is almost an order of magnitude larger than the Bohm current. Total currents of over 100 A are obtained from the plasma. Simple geometric focusing gives current densities approx.200 A/cm/sup 2/ at the focus.

  12. Current Behaviours and Attitudes Towards Texting While Driving in Australia

    DEFF Research Database (Denmark)

    Adamsen, Jannie Mia; Beasley, Keiran

    2011-01-01

    This paper aims to understand the behaviour of texting and driving among the broader driving public in Australia and uncover whether attitudes are congruent with behaviours. Recent studies have generally been focussing on the behaviours of 18-24 year olds suggesting that the practice is mainly...... confined to people in this age bracket. Findings from an anonymous online survey show that the practice of texting and driving is widespread in Australia and not just confined to the younger demographic. Additionally, evidence suggests smart phone users are more likely to engage in texting while driving....... The paper also reveals that a majority of people continue to text and drive despite having strong views on the dangers associated with the practice....

  13. Lower hybrid current drive favoured by electron cyclotron radiofrequency heating

    Energy Technology Data Exchange (ETDEWEB)

    Cesario, R.; Cardinali, A.; Castaldo, C.; Marinucci, M.; Tuccillo, A. A. [Associazione EURATOM/ENEA sulla Fusione, Centro Ricerche Frascati, 00044, Frascati (Italy); Amicucci, L.; Galli, A. [Università di Roma Sapienza, Dipartimento Ingegneria Elettronica, Rome (Italy); Giruzzi, G. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Napoli, F.; Schettini, G. [Università di Roma Tre, Dipartimento Ingegneria Elettronica, Rome (Italy)

    2014-02-12

    The important goal of adding to the bootstrap a fraction of non-inductive plasma current, which would be controlled for obtaining and optimizing steady-state profiles, can be reached by using the Current Drive produced by Lower Hybrid waves (LHCD). FTU (Frascati Tokamak Upgrade) experiments demonstrated, indeed, that LHCD is effective at reactor-graded high plasma density, and the LH spectral broadening is reduced, operating with higher electron temperature in the outer region of plasma column (T{sub e-periphery}). This method was obtained following the guidelines of theoretical predictions indicating that the broadening of launched spectrum produced by parametric instability (PI) should be reduced, and the LHCD effect at high density consequently enabled, under higher (T{sub e-periphery}). In FTU, the temperature increase in the outer plasma region was obtained by operating with reduced particle recycling, lithized walls and deep gas fuelling by means of fast pellet. Heating plasma periphery with electron cyclotron resonant waves (ECRH) will provide a further tool for achieving steady-state operations. New FTU experimental results are presented here, demonstrating that temperature effect at the plasma periphery, affecting LH penetration, occurs in a range of plasma parameters broader than in previous work. New information is also shown on the modelling assessing frequencies and growth rates of the PI coupled modes responsible of spectral broadening. Finally, we present the design of an experiment scheduled on FTU next campaign, where ECRH power is used to slightly increase the electron temperature in the outer plasma region of a high-density discharge aiming at restoring LHCD. Consequent to model results, by operating with a toroidal magnetic field of 6.3 T, useful for locating the electron cyclotron resonant layer at the periphery of the plasma column (r/a∼0.8, f{sub 0}=144 GHz), an increase of T{sub e} in the outer plasma (from 40 eV to 80 eV at r/a∼0.8) is

  14. Advances in modeling of lower hybrid current drive

    Science.gov (United States)

    Peysson, Y.; Decker, J.; Nilsson, E.; Artaud, J.-F.; Ekedahl, A.; Goniche, M.; Hillairet, J.; Ding, B.; Li, M.; Bonoli, P. T.; Shiraiwa, S.; Madi, M.

    2016-04-01

    First principle modeling of the lower hybrid (LH) current drive in tokamak plasmas is a longstanding activity, which is gradually gaining in accuracy thanks to quantitative comparisons with experimental observations. The ability to reproduce simulatenously the plasma current and the non-thermal bremsstrahlung radial profiles in the hard x-ray (HXR) photon energy range represents in this context a significant achievement. Though subject to limitations, ray tracing calculations are commonly used for describing wave propagation in conjunction with Fokker-Planck codes, as it can capture prominent features of the LH wave dynamics in a tokamak plasma-like toroidal refraction. This tool has been validated on several machines when the full absorption of the LH wave requires the transfer of a small fraction of power from the main lobes of the launched power spectrum to a tail at a higher parallel refractive index. Conversely, standard modeling based on toroidal refraction only becomes more challenging when the spectral gap is large, except if other physical mechanisms may dominate to bridge it, like parametric instabilities, as suggested for JET LH discharges (Cesario et al 2004 Phys. Rev. Lett. 92 175002), or fast fluctuations of the launched power spectrum or ‘tail’ LH model, as shown for Tore Supra (Decker et al 2014 Phys. Plasma 21 092504). The applicability of the heuristic ‘tail’ LH model is investigated for a broader range of plasma parameters as compared to the Tore Supra study and with different LH wave characteristics. Discrepancies and agreements between simulations and experiments depending upon the different models used are discussed. The existence of a ‘tail’ in the launched power spectrum significantly improves the agreement between modeling and experiments in plasma conditions for which the spectral gap is large in EAST and Alcator C-Mod tokamaks. For the Alcator C-Mod tokamak, the experimental evolution of the HXR profiles with density suggests

  15. Current profile redistribution driven by neutral beam injection in a reversed-field pinch

    Science.gov (United States)

    Parke, E.; Anderson, J. K.; Brower, D. L.; Den Hartog, D. J.; Ding, W. X.; Johnson, C. A.; Lin, L.

    2016-05-01

    Neutral beam injection in reversed-field pinch (RFP) plasmas on the Madison Symmetric Torus [Dexter et al., Fusion Sci. Technol. 19, 131 (1991)] drives current redistribution with increased on-axis current density but negligible net current drive. Internal fluctuations correlated with tearing modes are observed on multiple diagnostics; the behavior of tearing mode correlated structures is consistent with flattening of the safety factor profile. The first application of a parametrized model for island flattening to temperature fluctuations in an RFP allows inferrence of rational surface locations for multiple tearing modes. The m = 1, n = 6 mode is observed to shift inward by 1.1 ± 0.6 cm with neutral beam injection. Tearing mode rational surface measurements provide a strong constraint for equilibrium reconstruction, with an estimated reduction of q0 by 5% and an increase in on-axis current density of 8% ± 5%. The inferred on-axis current drive is consistent with estimates of fast ion density using TRANSP [Goldston et al., J. Comput. Phys. 43, 61 (1981)].

  16. Range of Possible Beam Current in Linac4

    CERN Document Server

    Lallement, J-B; CERN. Geneva. BE Department

    2009-01-01

    Linac4 is a new accelerator under construction at CERN. It is designed to accelerate H- ions to 160MeV, for injection into the existing Proton Synchrotron Booster (PSB). It is also the front-end of the SPL Linac, a high energy proton driver that will reach the energy of 5GeV. The Linac baseline design has been done for a nominal beam peak current of 70mA but it will certainly have to deal with different currents. 132 out of 155 quadrupoles in the Linac are permanent magnets, this choice of using PMQ having fixed gradient, mainly in the DTL and in the CCDTL may then entail issues concerning the beam transverse matching and quality from current different from the nominal one. In this paper, we present the beam dynamics performances in Linac4 obtained for different currents.

  17. Excitation of a cylindrical cavity by a helical current and an axial electron beam current

    Science.gov (United States)

    Davidovich, M. V.; Bushuev, N. A.

    2013-07-01

    The explicit expressions (in the Vainshtein and Markov forms) are derived for the excitation of a cylindrical cavity with perfectly conducting walls and with impedance end faces. Excitation of a cylindrical cavity and a cylindrical waveguide with a preset nonuniform axial electron-beam current and a helical current with a variable pitch, which is excited by a concentrated voltage source and is loaded by a preset pointlike matched load, is considered. For the helical current, the integro-differential equation is formulated. The traveling-wave tube (TWT) is simulated in the preset beam current approximation taking into account the nonuniform winding of the spiral coil, nonuniform electron beam, and losses.

  18. Image Currents in Azimuthally Inhomogeneous Metallic Beam Pipes

    CERN Document Server

    Caspers, Friedhelm; Palumbo, L; Ruggiero, F

    2001-01-01

    We consider an ultra-relativistic particle travelling on-axis in an infinitely long cylindrical metallic beam pipe with azimuthally varying conductivity. A semi-analytical solution, obtained by applying approximate boundary conditions, predicts an image current distribution on the pipe walls practically independent of the azimuth, at least in the frequency range relevant for future machines such as the LHC. We discuss numerical simulations and bench measurements which confirm the theoretical predictions. Implications for the beam-induced ohmic losses in the copper coated, welded LHC beam screen are also addressed.

  19. Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

    Directory of Open Access Journals (Sweden)

    Valeriy Shchavlev

    2012-12-01

    Full Text Available Electron beam welding (EBW shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process.

  20. Plasma charge current for controlling and monitoring electron beam welding with beam oscillation.

    Science.gov (United States)

    Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

    2012-12-14

    Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process.

  1. The Use of Current Generators in Electrical Converter Drives for Stepper Motors

    Directory of Open Access Journals (Sweden)

    Emanoil Toma

    2014-09-01

    Full Text Available This paper presents some ways to realize electrical converters for stepper motor drives. The first part analyzes aspects for unipolar stepper motor and use of constant current generators. The second part present current sources based on peak limiting current trough the inductance of motor coil. A complete drive module for bipolar stepper motor was conceived and simulation results confirm their functionability.

  2. Modeling of the influences of multiple modulated electron cyclotron current drive on NTMs in rotating plasma

    Science.gov (United States)

    Long, Chen; Jinyuan, Liu; Ping, Duan; Guangrui, Liu; Xingyu, Bian

    2017-02-01

    In this work, physical models of neoclassical tearing modes (NTMs) including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems during the suppression of NTMs by driven current, this work compares the efficiency of continuous and modulated driven currents, and simulates the physical processes of multiple modulated driven currents on suppressing rotating magnetic island. It is found that when island rotates along the poloidal direction, the suppression ability of continuous driven current can be massively reduced due to current deposition outside the island separatrix and reverse deposition direction at the X point, which can be avoided by current drive modulation. Multiple current drive has a better suppressing effect than single current drive. This work gives realistic numerical simulations by optimizing the model and parameters based on the experiments, which could provide references for successful suppression of NTMs in future advanced tokamak such as international thermonuclear experimental reactor.

  3. DPSS Laser Beam Quality Optimization Through Pump Current Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Omohundro, Rob; /Newport Spectra-Physics, Santa Clara; Callen, Alice; /SLAC; Sukuta, Sydney; /San Jose City Coll.

    2012-03-30

    The goal of this study is to demonstrate how a DPSS laser beam's quality parameters can be simultaneously optimized through pump current tuning. Two DPSS lasers of the same make and model were used where the laser diode pump current was first varied to ascertain the lowest RMS noise region. The lowest noise was found to be 0.13% in this region and the best M{sup 2} value of 1.0 and highest laser output power were simultaneously attained at the same current point. The laser manufacturer reported a M{sup 2} value of 1.3 and RMS noise value of .14% for these lasers. This study therefore demonstrates that pump current tuning a DPSS laser can simultaneously optimize RMS Noise, Power and M{sup 2} values. Future studies will strive to broaden the scope of the beam quality parameters impacted by current tuning.

  4. Research on Predicting Drive Current of Shipborne Satcom Antenna

    OpenAIRE

    Kong Jinping; Xu Zhengfeng; Wu Botao

    2015-01-01

    Predicting the effect of antenna wind load on servo system precisely is meaningful to ensure the safety of satcom antenna on operation, which can avoid overload operation. In this paper, the computational fluid dynamics is used to proceed numerical computation on the pressure distribution of the reflector and torque of drive shaft under different wind speed, windward angle and angle of pitch of the antenna. The simulation model is built under MATLAB/Simulink simulation environment, and the dr...

  5. Brushless DC motor Drive during Speed regulation with Current Controller

    OpenAIRE

    Bhikshalu Manchala; T.Amar Kiran

    2015-01-01

    Brushless DC Motor (BLDC) is one of the best electrical drives that have increasing popularity, due to their high efficiency, reliability, good dynamic response and very low maintenance. Due to the increasing demand for compact & reliable motors and the evolution of low cost power semiconductor switches and permanent magnet (PM) materials, brushless DC motors become popular in every application from home appliances to aerospace industry. The conventional techniques for controlling...

  6. An Improved Variable-Frequency Drive Based on Current Tracking

    Directory of Open Access Journals (Sweden)

    Zhiwei He

    2013-11-01

    Full Text Available Variable frequency devices are widely used in many power systems. A current tracking based VFD is proposed in this paper. The output current is firstly fed back and compared with a standard sine wave, the difference of them is then used for a PI regulator to control the PWM signal, so as to change the output current accordingly to make it approach the standard sine wave. Simulation and experiments results show that the current tracking VFD not only has a fast dynamic response, high current tracking precision, current limiting ability, but also has small distortion of the output sine wave current and low loss of the motor.    

  7. The role of the plasma current in turbulence decrease during lower hybrid current drive

    Science.gov (United States)

    Antar, G.; Ekedahl, A.; Goniche, M.; Asghar, A.; Žàček, F.

    2017-03-01

    The interaction of radio frequency (RF) waves with edge turbulence has resurfaced after the results obtained on many tokamaks showing that edge turbulence decreases when the ion cyclotron frequency heating (ICRH) is switched on. Using the lower hybrid (LH) waves to drive current into tokamak plasmas, this issue presented contradicting results with some tokamaks (FTU & HT-7) showing a net decrease, similar to the ICRH results, and others (Tore Supra) did not. In this article, these apparent discrepancies among tokamaks and RF wave frequencies are removed. It is found that turbulence large-scale structures in the scrape-off layer decrease at high enough plasma currents (Ip) on the Tore Supra tokamak. We distinguish three regimes: At low Ip's, no modification is detected with statistical properties of turbulence similar to ohmic plasmas even with PLH reaching 4.8 MW. At moderate plasma currents, turbulence properties are modified only at a high LH power. At high plasma currents, turbulent large scales are reduced to values smaller than 1 cm, and this is accompanied by a net decrease in the level of turbulence of about 30% even with a moderate LH power.

  8. First test of BNL electron beam ion source with high current density electron beam

    Science.gov (United States)

    Pikin, Alexander; Alessi, James G.; Beebe, Edward N.; Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard

    2015-01-01

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm2 and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  9. Optimization of solenoid based low energy beam transport line for high current H+ beams

    Science.gov (United States)

    Pande, R.; Singh, P.; Rao, S. V. L. S.; Roy, S.; Krishnagopal, S.

    2015-02-01

    A 20 MeV, 30 mA CW proton linac is being developed at BARC, Mumbai. This linac will consist of an ECR ion source followed by a Radio Frequency Quadrupole (RFQ) and Drift tube Linac (DTL). The low energy beam transport (LEBT) line is used to match the beam from the ion source to the RFQ with minimum beam loss and increase in emittance. The LEBT is also used to eliminate the unwanted ions like H2+ and H3+ from entering the RFQ. In addition, space charge compensation is required for transportation of such high beam currents. All this requires careful design and optimization. Detailed beam dynamics simulations have been done to optimize the design of the LEBT using the Particle-in-cell code TRACEWIN. We find that with careful optimization it is possible to transport a 30 mA CW proton beam through the LEBT with 100% transmission and minimal emittance blow up, while at the same time suppressing unwanted species H2+ and H3+ to less than 3.3% of the total beam current.

  10. Collective effects and experimental verification of the CLIC drive beam and decelerator

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00418229; Stapnes, Steinar; Adli, Erik

    The Compact Linear Collider (CLIC) is a potential next-generation particle collider, in which electrons and positrons collide at a center-of-mass energy of up to 3 TeV. In order to reach a high accelerating gradient and reduce the length of the machine, CLIC uses a novel two-beam scheme. Here, the acceleration energy for the main beam is provided by energy extraction from a secondary electron drive beam, by the use of Power Extraction and Transfer Structures (PETS). This Ph.D. thesis describes deceleration measurements from the CLIC Test Facility 3 at CERN, from a beam that had up to 37 % of its kinetic energy converted into 12 GHz rf power. The results are part of the feasibility demonstration of the CLIC scheme. The measured difference in beam energy of the decelerated beam is correlated with particle tracking simulations and with predictions based on analytical formulae, and a very good agreement is demonstrated. The evolution of the transverse emittance was also studied, since it is critical to contain th...

  11. Beam Current Measurement and Adjustment System on AMS

    Institute of Scientific and Technical Information of China (English)

    WUShao-yong; HEMING; SUSheng-yong; WANGZhen-jun; JIANGShan

    2003-01-01

    The beam current measurement and adjustment system of HI-13 tandem accelerator mass spectrometry detector system is consisted of the faraday cup, fluorescent target and a series of adjustable vertical slits(Fig. 1). The system's operation is very complicated and the transmission is low for the old system. A new system is instalated for improvement. We put the adjustable vertical slit, Faraday cup.

  12. Improvements on Pulsed Current Sharing in Driving Parallel MOSFETs

    Science.gov (United States)

    Takagi, Hajime; Orihara, Masato; Yamada, Tsutomu; Yanagidaira, Takeshi

    To switch high-voltage and high-current pulses by using MOS (Metal Oxide Semiconductor) transistors, it is necessary to distribute evenly the voltage and current to each element connected in series and parallel. In parallel connection, the current flowing in each element is different depending on the series resistance and wiring inductance. We verified improvements on pulsed current sharing in parallel transistors which were arranged in line on a printed circuit board. Although Gate and Drain wirings are different in length, pulsed current was evenly distributed by using transmission line transformers. Dissipation in transistors were equalized and four transistors were driven simultaneously near the rated current.

  13. Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

    CERN Document Server

    Lemery, Francois

    2015-01-01

    Collinear high-gradient ${\\cal O} (GV/m)$ beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios $>2$, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting "drive" bunch to an accelerated "witness" bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative current profiles which are smooth which also lead to enhanced transformer ratios. We especially explore a laser-shaping method capable of generating one the suggested distributions directly out of a photoinjector and discuss a linac concept that could possible drive a dielectric ...

  14. High current density sheet-like electron beam generator

    Science.gov (United States)

    Chow-Miller, Cora; Korevaar, Eric; Schuster, John

    Sheet electron beams are very desirable for coupling to the evanescent waves in small millimeter wave slow-wave circuits to achieve higher powers. In particular, they are critical for operation of the free-electron-laser-like Orotron. The program was a systematic effort to establish a solid technology base for such a sheet-like electron emitter system that will facilitate the detailed studies of beam propagation stability. Specifically, the effort involved the design and test of a novel electron gun using Lanthanum hexaboride (LaB6) as the thermionic cathode material. Three sets of experiments were performed to measure beam propagation as a function of collector current, beam voltage, and heating power. The design demonstrated its reliability by delivering 386.5 hours of operation throughout the weeks of experimentation. In addition, the cathode survived two venting and pump down cycles without being poisoned or losing its emission characteristics. A current density of 10.7 A/sq cm. was measured while operating at 50 W of ohmic heating power. Preliminary results indicate that the nearby presence of a metal plate can stabilize the beam.

  15. Clipper for High-Impedance Current-Drive Line

    Science.gov (United States)

    Woodhouse, Christopher E.

    1987-01-01

    New circuit leakage reduced by shunting current through saturated input at operational-amplifier follower already part of Howland, or equivalent, current source. Typical application is in circuit of germanium resistance thermometer in cryogenic system.

  16. Progress on the heating and current drive systems for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Jacquinot, J. [CEA, Cadarache, France; Beaumont, Bertrand [ITER Joint Work Site, Cadarache; Bora, D. [ITER Joint Work Site, Cadarache; Campbell, D. [ITER Joint Work Site, Cadarache; Darbos, Caroline [ITER Joint Work Site, Cadarache; Decamps, H. [ITER Organization, Saint Paul Lez Durance, France; Graceffa, J. [ITER Joint Work Site, Cadarache; Gassmann, T. [ITER Joint Work Site, Cadarache; Hemsworth, R. [ITER Joint Work Site, Cadarache; Henderson, Mark [ITER Joint Work Site, Cadarache; Kobayashi, N. [ITER Joint Work Site, Cadarache; Lamalle, Philippe [ITER Joint Work Site, Cadarache; Schunke, B. [ITER Joint Work Site, Cadarache; Tanaka, M. [ITER Joint Work Site, Cadarache; Tanga, A. [ITER Joint Work Site, Cadarache; Albajar, F. [Fusion for Energy (F4E), Barcelona, Spain; Bonicelli, T. [Fusion for Energy (F4E), Barcelona, Spain; Saibene, G. [Fusion for Energy (F4E), Barcelona, Spain; Sartori, R. [Fusion for Energy (F4E), Barcelona, Spain; Becoulet, A. [CEA, Cadarache, France; Hoang, G. T. [CEA, Cadarache, France; Inoue, T. [Japan Atomic Energy Agency (JAEA), Naka; Sakamoto, K. [Japan Atomic Energy Agency (JAEA), Naka; Takahashi, K. [Japan Atomic Energy Agency (JAEA), Naka; Watanabe, K. [Japan Atomic Energy Agency (JAEA), Naka; Goulding, Richard Howell [ORNL; Rasmussen, David A [ORNL; Swain, David W [ORNL; Chakraborty, A. [ITER India - Bhat, Gandhinagar, Gujarat; Mukherjee, A. [ITER India - Bhat, Gandhinagar, Gujarat; Rao, S. L. [ITER India - Bhat, Gandhinagar, Gujarat; Denisov, G. [Russian Academy of Science, Novgorod, Russia; Nightingale, M. [EURATOM / UKAEA, Abingdon, UK; Sonato, P. [EURATOM / ENEA, Italy

    2009-06-01

    The electron cyclotron (EC), ion cyclotron (IC), heating-neutral beam (H-NB) and, although not in the day 1 baseline, lower hybrid (LH) systems intended for ITER have been reviewed in 2007/2008 in light of progress of physics and technology in the field. Although the overall specifications are unchanged, notable changes have been approved. Firstly, it has been emphasized that the H&CD systems are vital for the ITER programme. Consequently, the full 73 MW should be commissioned and available on a routine basis before the D/T phase. Secondly, significant changes have been approved at system level, most notably: the possibility to operate the heating beams at full power during the hydrogen phase requiring new shine through protection; the possibility to operate IC with 2 antennas with increased robustness (no moving parts); the possible increase to 2 MW of key components of the EC transmission systems in order to provide an easier upgrading of the EC power as may be required by the project; the addition of a building dedicated to the RF power sources and to a testing facility for acceptance of diagnostics and heating port plugs. Thirdly, the need of a plan for developing, in time for the active phase, a CD system such as LH suitable for very long pulse operation of ITER was recognised. The review describes these changes and their rationale.

  17. Grad-B drift transport of high current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.R.; Backstrom, R.C.; Halbleib, J.A.; Wright, T.P.

    1983-01-01

    Grad-B transport, bunching and focusing of relativistic electron beams has been proposed as a method of increasing the power delivered to an ICF target by an order of magnitude. Recent experiments have demonstrated the efficient transport of high current electron beams over 1.0 m distances in the 1/r azimuthal magnetic field of a current-carrying wire. The electron drift velocity was measured as a function of wire current and found to be in good agreement with theory. Measurements of x-ray production in a tantalum target were used as a diagnostic tool to study transport efficiency. A theoretical model of the experiment was developed to calculate bremsstrahlung production in the target, assuming 100 percent transport efficiency. This model predicted radial x-ray dose profiles in the experimental converter assembly which were in good agreement with the measurements.

  18. High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system.

    Science.gov (United States)

    Takahashi, K; Kajiwara, K; Oda, Y; Kasugai, A; Kobayashi, N; Sakamoto, K; Doane, J; Olstad, R; Henderson, M

    2011-06-01

    High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20°-40° from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system.

  19. HHFW Heating and Current Drive Studies of NSTX H-Mode Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    G. Taylor, P.T. Bonoli, D.L. Green, R.W. Harvey, J.C. Hosea, E.F. Jaeger, B.P. LeBlanc, R. Maingi, C.K. Phillips, P.M. Ryan, E.J. Valeo, J.R. Wilson, J.C. Wright, and the NSTX Team

    2011-06-08

    30 MHz high-harmonic fast wave (HHFW) heating and current drive are being developed to assist fully non-inductive plasma current (I{sub p}) ramp-up in NSTX. The initial approach to achieving this goal has been to heat I{sub p} = 300 kA inductive plasmas with current drive antenna phasing in order to generate an HHFW H-mode with significant bootstrap and RF-driven current. Recent experiments, using only 1.4 MW of RF power (P{sub RF}), achieved a noninductive current fraction, f{sub NI} {approx} 0.65. Improved antenna conditioning resulted in the generation of I{sub p} = 650 kA HHFW H-mode plasmas, with f{sub NI} {approx} 0.35, when P{sub RF} {ge} 2.5 MW. These plasmas have little or no edge localized mode (ELM) activity during HHFW heating, a substantial increase in stored energy and a sustained central electron temperature of 5-6 keV. Another focus of NSTX HHFW research is to heat an H-mode generated by 90 keV neutral beam injection (NBI). Improved HHFW coupling to NBI-generated H-modes has resulted in a broad increase in electron temperature profile when HHFW heating is applied. Analysis of a closely matched pair of NBI and HHFW+NBI H-mode plasmas revealed that about half of the antenna power is deposited inside the last closed flux surface (LCFS). Of the power damped inside the LCFS about two-thirds is absorbed directly by electrons and one-third accelerates fast-ions that are mostly promptly lost from the plasma. At longer toroidal launch wavelengths, HHFW+NBI H-mode plasmas can have an RF power flow to the divertor outside the LCFS that significantly reduces RF power deposition to the core. ELMs can also reduce RF power deposition to the core and increase power deposition to the edge. Recent full wave modeling of NSTX HHFW+NBI H-mode plasmas, with the model extended to the vessel wall, predicts a coaxial standing mode between the LCFS and the wall that can have large amplitudes at longer launch wavelengths. These simulation results qualitatively agree with HHFW

  20. Gradient B drift transport of high current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.R.; Backstrom, R.C.; Halbleib, J.A.; Quintenz, J.P.; Wright, T.P.

    1984-12-01

    A 1-MeV, 200-kA electron beam was transported 89 cm in a low pressure background gas via gradient B drift in the 1/r azimuthal magnetic field of a current carrying wire. The electron drift velocity was measured and found to be in good agreement with theory. Measurements of x-ray production in the target indicated high transport efficiency.

  1. A microbeam slit system for high beam currents

    Science.gov (United States)

    Vallentin, T.; Moser, M.; Eschbaumer, S.; Greubel, C.; Haase, T.; Reichart, P.; Rösch, T.; Dollinger, G.

    2015-04-01

    A new microbeam slit system for high beam currents of 10 μA was built up to improve the brightness transport of a proton beam with a kinetic energy of up to 25 MeV into the microprobe SNAKE. The new slit system features a position accuracy of less than 1 μm under normal operating conditions and less than 2 μm if the beam is switched on and off. The thermal management with a powerful watercooling and potential-free thermocouple feedback controlled heating cables is optimized for constant slit aperture at thermal power input of up to 250 W. The transparent zone is optimized to 0.7 μm due to the use of tungsten formed to a cylindrical surface with a radius r = 100 mm and mechanically lapped surface to minimize small angle scattering effects and to minimize the number of ions passing the slits with low energy loss. Electrical isolation of the slit tip enables slit current monitoring, e.g. for tandem accelerator feedback control. With the ability to transport up to 10 μA of protons with the new microslit system, the brightness Bexp transported into the microprobe was increased by a factor of 2 compared to low current injection using the old slit system.

  2. Adiabatic Compression of Compact Tori for Current Drive and Heating

    Science.gov (United States)

    Woodruff, Simon; McNab, Angus; Miller, Kenneth; Ziemba, Tim

    2008-11-01

    Several critical issues stand in the development path for compact tori. An important one is the production of strong magnetic fields, (or large flux amplifications) by use of a low current source. The Pulsed Build-up Experiment is a Phase II SBIR project in which we aim to show a new means for generating strong magnetic fields from a low current source, namely, the repetitive injection of helicity-bearing plasma that also undergoes an acceleration and compression. In the Phase I SBIR, advanced computations were benchmarked against analytic theory and run to determine the best means for the acceleration and compression of a compact torus plasma. The study included detailed simulations of magnetic reconnection. In Phase II, an experiment has been designed and is being built to produce strong magnetic fields in a spheromak by the repetitive injection of magnetic helicity from a low current coaxial plasma source. The plasma will be accelerated and compressed in a similar manner to a traveling wave adiabatic compression scheme that was previously applied to a mirror plasma [1]. [1] P. M. Bellan Scalings for a Traveling Mirror Adiabatic Magnetic Compressor Rev. Sci. Instrum. 53(8) 1214 (1982) Work supported by DOE Grant No. DE-FG02-06ER84449.

  3. Fast wave current drive modeling using the combined RANT3D and PICES codes

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, E.F.; Murakami, M.; Stallings, D.C. [and others

    1995-07-01

    Two numerical codes are combined to give a theoretical estimate of the current drive and direct electron heating by fast waves launched from phased antenna arrays on the DIII-D tokamak. Results are compared with experiment.

  4. Fast wave current drive modeling using the combined RANT3D and PICES Codes

    Science.gov (United States)

    Jaeger, E. F.; Murakami, M.; Stallings, D. C.; Carter, M. D.; Wang, C. Y.; Galambos, J. D.; Batchelor, D. B.; Baity, F. W.; Bell, G. L.; Wilgen, J. B.; Chiu, S. C.; DeGrassie, J. S.; Forest, C. B.; Kupfer, K.; Petty, C. C.; Pinsker, R. T.; Prater, R.; Lohr, J.; Lee, K. M.

    1996-02-01

    Two numerical codes are combined to give a theoretical estimate of the current drive and direct electron heating by fast waves launched from phased antenna arrays on the DIII-D tokamak. Results are compared with experiment.

  5. Experimental Research of Harmonic Spectrum of Currents at Traction Drive with PMSM

    Directory of Open Access Journals (Sweden)

    J. Novak

    2011-06-01

    Full Text Available The paper deals with the significant results of the experimental research of current harmonic spectrum of traction drive with permanent magnet synchronous motor. The experiments were done on a special workplace with a real traction drive for wheel vehicles. Current harmonic spectrum was analyzed by a specialized device on the base of central measuring station. The knowledge of current marked subharmonic components of stator winding is the most significant finding of experiments. The frequencies of these components are given by multiples of frequency of mechanical speeds. The subharmonic components also pass to input DC current of drive. This fact is important in particular from the point of view of legislative requirements to electromagnetic compatibility of drive with railway interlocking devices.

  6. Langmuir probe study in the nonresonant current drive regime of helicon discharge

    Indian Academy of Sciences (India)

    Manash Kumar Paul; Dhiraj Bora

    2008-07-01

    Characterization of the current drive regime is done for helicon wave-generated plasma in a torus, at a very high operating frequency. A radiofrequency-compensated Langmuir probe is designed and used for the measurement of plasma parameters along with the electron energy distributions in radial scans of the plasma. The electron energy distribution patterns obtained in the operational regime suggest that Landau damping cannot be responsible for the efficient helicon discharge in the present study. A typical peaked radial density profile, high plasma temperature and absence of an appreciable amount of energetic electrons for resonant wave–particle interactions, suggest that the chosen operational regime is suitable for the study of nonresonant current drive by helicon wave. Successful and significant current drive achieved in our device clearly demonstrates the capability of nonresonant current drive by helicon waves in the present operational regime.

  7. Coupling of α-channeling to |k∥| upshift in lower hybrid current drive

    Energy Technology Data Exchange (ETDEWEB)

    Ochs, I. E. [Harvard University, Cambridge, MA (United States). Department of Physics.; Bertelli, N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Fisch, N. J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2014-08-26

    Although lower hybrid waves have been shown to be effective in driving plasma current in present-day tokamaks, they are predicted to strongly interact with the energetic α particles born from fusion reactions in eventual tokamak reactors.

  8. A relativistic model of electron cyclotron current drive efficiency in tokamak plasmas

    OpenAIRE

    Lin-Liu Y.R.; Hu Y.J.; Hu Y.M.

    2012-01-01

    A fully relativistic model of electron cyclotron current drive (ECCD) efficiency based on the adjoint function techniques is considered. Numerical calculations of the current drive efficiency in a tokamak by using the variational approach are performed. A fully relativistic extension of the variational principle with the modified basis functions for the Spitzer function with momentum conservation in the electron-electron collision is described in general tokamak geometry. The model developed ...

  9. RF current drive by electron cyclotron waves in the presence of magnetic islands

    Energy Technology Data Exchange (ETDEWEB)

    Da Silva Rosa, P.; Giruzzi, G

    1999-11-01

    The influence of the presence of magnetic islands, and the consequent modification of the tokamak magnetic surface topology, on electron current drive is analyzed. To this end, a new 3D Fokker-Planck code has been developed, taking into account the modifications of the magnetic equilibrium topology owing to the presence of the islands. Significant differences between electron cyclotron current drive efficiency with and without island inside the plasma are found, particularly in the case of interaction with locked modes. (authors)

  10. Mass of a skyrmion under a driving current

    Science.gov (United States)

    Martinez, J. C.; Jalil, M. B. A.

    2017-02-01

    We present arguments for a mass term in the Landau-Lifshitz-Gilbert equation based on the notion of mass as an inertial quantity. From trajectories of skyrmions in a confining potential and a 1-D potential we see evidence for a mass-inertia connection. We derive an expression for the effective mass for skyrmions, 1.6 ε ×10-23 kg , where ε accounts for the mismatch between the local magnetic moment induced on the conduction electrons and its corresponding effect on the current-driven skyrmion and varies from 10-2 to 1.

  11. Current Research Activities in Drive System Technology in Support of the NASA Rotorcraft Program

    Science.gov (United States)

    Handschuh, Robert F.; Zakrajsek, James J.

    2006-01-01

    Drive system technology is a key area for improving rotorcraft performance, noise/vibration reduction, and reducing operational and manufacturing costs. An overview of current research areas that support the NASA Rotorcraft Program will be provided. Work in drive system technology is mainly focused within three research areas: advanced components, thermal behavior/emergency lubrication system operation, and diagnostics/prognostics (also known as Health and Usage Monitoring Systems (HUMS)). Current research activities in each of these activities will be presented. Also, an overview of the conceptual drive system requirements and possible arrangements for the Heavy Lift Rotorcraft program will be reviewed.

  12. Current Measurements of Low-Intensity Beams at CRYRING

    CERN Document Server

    Paál, A; Källberg, A

    2003-01-01

    The demand for new ion species leads to an increasing number of cases in which the ions can only be produced in small quantities. Thus, weak ion currents quite often have to be handled in low energy ion storage ring, like CRYRING. Various detector systems have been developed to measure such low intensity coasting and bunched beams by using the overlapping ranges of those systems. We have extended the RMS resolution to 1 nA of the Bergoz Beam Charge Monitor (BCM) by using a low noise 60 dB preamplifier for the Integrating Current Transformer. The sum signal of a capacitive pick-up is integrated by a second gated integrator and the BCM output signal is used for calibration. The RMS resolution is about 100 pA.. To measure the coasting beam intensity, neutral particle detectors have been built. The fast Microchannel plate detector can handle 1 Mc/s, and a 50 Mc/s Secondary Electron Multiplier based detector is under construction. On the magnetic flat top, a time of 100 ms is available to calibrate the count r...

  13. Effects of passive components on the input current interharmonics of adjustable-speed drives

    DEFF Research Database (Denmark)

    Soltani, Hamid; Blaabjerg, Frede; Zare, Firuz;

    2016-01-01

    speed drives with and/or without motor current imbalance. The investigation is done at different motor operating frequencies and load torque values. It shows that selecting the small filter components (ac choke, dc choke and dc-link capacitor) results in different performances in respect to those......Current and voltage source Adjustable Speed Drives (ASDs) exert distortion current into the grid, which may produce some interharmonic components other than the characteristic harmonic components. This paper studies the effects of passive components on the input current interharmonics of adjustable...... interharmincs issued by motor current imbalance and other non-characteristic interharmonics. The results are helpful for engineers investigating the effects of drive filters on the input current interharmonic components....

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

    CERN Multimedia

    1978-01-01

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

  15. First test of BNL electron beam ion source with high current density electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, Alexander, E-mail: pikin@bnl.gov; Alessi, James G., E-mail: pikin@bnl.gov; Beebe, Edward N., E-mail: pikin@bnl.gov [Brookhaven National Laboratory, Upton, NY 11973 (United States); Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard [CERN, CH-1211 Geneva 23 (Switzerland)

    2015-01-09

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm{sup 2} and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio < 4.5 are requested by many heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  16. The drive to strive: goal generation based on current needs

    Directory of Open Access Journals (Sweden)

    Elisabeth A Murray

    2013-06-01

    Full Text Available Hungry animals are influenced by a multitude of different factors when foraging for sustenance. Much of the work on animal foraging has focused on factors relating to the amount of time and energy animals expend searching for and harvesting foods. Models that emphasize such factors have been invaluable in determining when it is beneficial for an animal to search for pastures new. When foraging, however, animals also have to determine how to direct their search. For what food should they forage? There is no point searching for more of a particular food when you are sated from eating it. Here we review work in macaques and humans that has sought to reveal the neural circuits critical for determining the subjective value of different foods and associated objects in our environment and tracking this value over time. There is mounting evidence that a network composed of the orbitofrontal cortex (OFC, amygdala and medial thalamus is critical for linking objects in the environment with food value and adjusting those valuations in real time based on current biological needs. Temporal inactivation studies have revealed that the amygdala and OFC play distinct, but complementary roles in this valuation process. Such a network for determining the subjective value of different foods and, by extension, associated objects, must interact with systems that determine where and for how long to forage. Only by efficiently incorporating these two factors into their decisions will animals be able to achieve maximal fitness.

  17. Fokker-Planck Simulation of Fast Wave Current Drive and Heating in the Reversed Field Pinch

    Science.gov (United States)

    Uchimoto, E.; Shiina, S.; Harvey, R. W.; Smirnov, A. P.; Forest, C. B.; Prager, S. C.; Wright, J. C.

    1999-11-01

    Fast wave current drive (FWCD) has been shown theoretically to be a good candidate for improving plasma confinement characteristics of a high-beta, reactor-grade RFP via current profile control.footnote S. Shiina, Y. Kondoh, H. Ishii, Nuclear Fusion 34, 1473 (1994); T. Nagai et al., Proc. ICPP (Nagoya, 1996), p. 1042; K. Kusano et al., 17th IAEA Fusion Energy Conf. (Yokohama, 1998), paper THP1/12. To assess the effects of toroidicity and quasilinear modifications to the electron distribution function on FWCD, we are using the RFP version of ray-tracing and Fokker-Planck codes (GENRAY and CQL3D). Although lower hybrid slow waves are ideally suited for poloidal current drive in large RFPs presently in operation, possible use of fast waves is being considered for core current drive and heating in these devices. For MST parameters, our calculations focus on intermediate to high harmonic fast waves for which geometric optics is valid.

  18. Closure of the single fluid magnetohydrodynamic equations in presence of electron cyclotron current drive

    NARCIS (Netherlands)

    Westerhof, E.; Pratt, J.

    2014-01-01

    In the presence of electron cyclotron current drive (ECCD), the Ohm's law of single fluid magnetohydrodynamics is modified as E + v × B = η(J – J EC). This paper presents a new closure relation for the EC driven current density appearing in this modified Ohm's law. The new relation faithfu

  19. The effect of toroidal field on the rotating magnetic field current drive in rotamak plasmas

    Institute of Scientific and Technical Information of China (English)

    Zhong Fang-Chuan; Huang Tian-Sen; Petrov Yuri

    2007-01-01

    A rotamak is one kind of compact spherically shaped magnetic-confinement device. In a rotamak the plasma current is driven by means of rotating magnetic field (RMF). The driven current can reverse the original equilibrium field and generate a field-reversed-configuration. In a conventional rotamak, a toroidal field (TF) is not necessary for the RMF to drive plasma current, but it was found that the present of an additional TF can influence the RMF current drive. In this paper the effect of TF on the RMF current drive in a rotamak are investigated in some detail.The experimental results show that addition of TF increases the RMF driven current greatly and enhances the RMF penetration dramatically. Without TF, the RMF can only penetrate into plasma in the edge region. When a TF is added, the RMF can reach almost the whole plasma region. This is an optimal strength of toroidal magnetic field for getting maximum plasma current when Bv and radio frequency generator power are fixed. Besides driving current,the RMF generates high harmonic fields in rotamak plasma. The effect of TF on the harmonic field spectra are also reported.

  20. Concept development and numerical analysis of tokamak heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Myung Hee; Hong, Bong Guen [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-10-01

    We have done the analytical study on the coupling between the KSTAR plasma and RF antenna necessary for the engineering design of the KSTAR auxiliary heating and current drive system as well as the KSTAR RF antenna. With the code TORIC, the possible parameter ranges of tokamak heating and current drive operation modes using fast wave on the KSTAR are defined and analyzed. The optimized operation scenarios corresponding to the variety of KSTAR fast wave-driven heating and current drive parameters are also developed. With the code RANT3D, the characteristics of the coupling between the KSTAR plasma and RF antenna are analyzed, and the data for the conceptual design of 6 MW KSTAR RF antenna are achieved. Finally the optimum heating and current drive scenarios for the 3 KSTAR operation modes (the baseline reference mode, the upgrade reference mode, the reverse shear mode) using ACCOME and WHIST are developed, and it was shown that they can be realized in KSTAR tokamak with the planned heating and current drive systems. (author). 20 refs., 39 figs., 3 tabs.

  1. Low-level feedback control for the phase regulation of CLIC Drive Beam Klystrons

    CERN Document Server

    AUTHOR|(SzGeCERN)752526

    2015-01-01

    The requirement of luminosity loss below 1% raises tight tolerances for the phase and power stability of the CLIC drive beam (DB) klystrons and consequently for the high voltage pulse ripple of the modulators. A low-level RF (LLRF) feedback system needs to be developed and combined with the modulator in order to guarantee the phase and amplitude tolerances. To this aim, three feedback control strategies were investigated, i) Proportional Integral (PI) controller, ii) Linear Quadratic Integral Regulator (LQI) and iii) Model Predictive Controller (MPC). The klystron, as well as the incident phase noise were modelled and used for the design and evaluation of the controllers. First simulation results are presented along with future steps and directions.

  2. Investigation of lower hybrid current drive during H-mode in EAST tokamak

    Institute of Scientific and Technical Information of China (English)

    Li Miao-Hui; Liu Fu-Kun; Wang Mao; Xu Han-Dong; Wan Bao-Nian; Ding Bo-Jiang; Kong Er-Hua; Zhang Lei; Zhang Xin-Jun; Qian Jin-Ping; Yan Ning; Han Xiao-Feng; Shan Jia-Fang

    2011-01-01

    H-mode discharges with lower hybrid current drive (LHCD) alone are achieved in EAST divertor plasma over a wide parameter range.These H-mode discharges are characterized by a sudden drop in Dα emission and a spontaneous rise in main plasma density.Good lower hybrid (LH) coupling during H-mode is obtained by putting the plasma close to the antenna and by injecting D2 gas from a pipe near the grill mouse.The analysis of lower hybrid current drive properties shows that the LH deposition profile shifts off axis during H-mode,and current drive (CD) efficiency decreases due to the increase in density.Modeling results of H-mode discharges with a general ray tracing code GENRAY are reported.

  3. Effect of finite beam width on current separation in beam plasma system: Particle-in-Cell simulations

    CERN Document Server

    Shukla, Chandrasekhar; Patel, Kartik

    2015-01-01

    The electron beam propagation in a plasma medium is susceptible to several instabilities. In the relativistic regime typically the weibel instability leading to the current separation dominates. The linear instability analysis is carried out for a system wherein the transverse extent of the beam is infinite. Even in simulations, infinite transverse extent of the beam has been chosen. In real situations, however, beam width will always be finite. keeping this in view the role of finite beam width on the evolution of the beam plasma system has been studied here using Particle - in - Cell simulations. It is observed that the current separation between the forward and return shielding current for a beam with finite beam occurs at the scale length of the beam width itself. Consequently the magnetic field structures that form have maximum power at the scale length of the beam width. This behaviour is distinct from what happens with a beam with having an infinite extent represented by simulations in a periodic box, ...

  4. Lower hybrid current drive experiments on Alcator C-Mod: Comparison with theory and simulationa)

    Science.gov (United States)

    Bonoli, P. T.; Ko, J.; Parker, R.; Schmidt, A. E.; Wallace, G.; Wright, J. C.; Fiore, C. L.; Hubbard, A. E.; Irby, J.; Marmar, E.; Porkolab, M.; Terry, D.; Wolfe, S. M.; Wukitch, S. J.; Alcator C-Mod Team; Wilson, J. R.; Scott, S.; Valeo, E.; Phillips, C. K.; Harvey, R. W.

    2008-05-01

    Lower hybrid (LH) current drive experiments have been carried out on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] using a radio-frequency system at 4.6GHz. Up to 900kW of LH power has been coupled and driven LH currents have been inferred from magnetic measurements by extrapolating to zero loop voltage, yielding an efficiency of neILHR0/PLH≈2.5±0.2×1019(A/W/m2). We have simulated the LH current drive in these discharges using the combined ray tracing/three-dimensional (r,v⊥,v∥) Fokker-Planck code GENRAY-CQL3D (R. W. Harvey and M. McCoy, in Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992) and found similar current drive efficiencies. The simulated profiles of current density from CQL3D, including both ohmic plus LH drive have been found to be in good agreement with the measured current density from a motional Stark effect diagnostic. Measurements of nonthermal x-ray emission confirm the presence of a significant fast electron population and the three-dimensional (r,v⊥,v∥) electron distribution function from CQL3D has been used in a synthetic diagnostic code to simulate the measured hard x-ray data.

  5. Study and Experimental Characterization of a Novel Photo Injector for the CLIC Drive Beam

    CERN Document Server

    Mete, Oznur; Rivkin, Leonid

    2011-01-01

    In this thesis, the transverse and longitudinal beam properties of the PHIN photoinjector are characterized. The ob jective of the research is to demonstrate the reliable and stable production of a 1.3 µs long bunch train, with 2.33 nC charge per bunch and 4.5 µC of total charge, by the PHIN photoinjector. The results of this thesis are the important steps towards the feasibility demonstration of a photoinjector as the Compact Linear Collider’s drive beam source. The PHIN photoinjector has been conceptualized by a collaboration between “Laboratoire de l’Accélérateur Linéaire (LAL)”, “Rutherford Appleton Laboratory (RAL)” and “Organisation Européenne pour la Recherche Nucléaire (CERN)”. Within this collaboration, LAL and RAL have committed to the design and the construction of the RF gun and laser, respectively. The photocathode production as well as the overall coordination and commissioning were under the responsibility of CERN. The pro ject is in the framework of the second Joint Res...

  6. Design of long-pulse fast wave current drive antennas for DIII-D

    Science.gov (United States)

    Baity, F. W.; Batchelor, D. B.; Bills, K. C.; Fogelman, C. H.; Jaeger, E. F.; Ping, J. L.; Riemer, B. W.; Ryan, P. M.; Stallings, D. C.; Taylor, D. J.; Yugo, J. J.

    1994-10-01

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90° phasing into a low-density plasma (˜4×1019m-3) with hot electrons (˜10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  7. Analysis of JET LCHD/ICRH synergy experiments in terms of relativistic current drive theory

    Energy Technology Data Exchange (ETDEWEB)

    Start, D.F.H.; Baranov, Y.; Brusati, M.; Ekedahl, A.; Froissard, P.; Gormezano, C.; Jacquinot, J.; Paquin, L.; Rimini, F.G. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Cox, M.; Gardner, C.; O`Brien, M.R. [UKAEA Culham Lab., Abingdon (United Kingdom); Di Vita, A. [Ansaldo SpA, Genoa (Italy)

    1994-07-01

    The present analysis shows that the observed efficiency of current drive with synergy between LHCD and ICRH is in good agreement with the relativistic theory of Karney and Fisch for Landau damped waves. The predicted power absorption from the fast wave by the electron tail is within 30% of the measured value. In the presence of significant fast electron diffusion within a slowing down time it would be possible to produce central current drive using multiple ICRF resonances even when the LHCD deposition is at half radius, as in an ITER type device. (authors). 4 refs., 6 figs.

  8. Extracting DC bus current information for optimal phase correction and current ripple in sensorless brushless DC motor drive

    Institute of Scientific and Technical Information of China (English)

    Zu-sheng HO; Chii-maw UANG; Ping-chieh WANG

    2014-01-01

    Brushless DC motor (BLDCM) sensorless driving technology is becoming increasingly established. However, op-timal phase correction still relies on complex calculations or algorithms. In finding the correct commutation point, the problem of phase lag is introduced. In this paper, we extract DC bus current information for auto-calibrating the phase shift to obtain the correct commutation point and optimize the control of BLDC sensorless driving. As we capture only DC bus current information, the original shunt resistor is used in the BLDCM driver and there is no need to add further current sensor components. Software processing using only simple arithmetic operations successfully accomplishes the phase correction. Experimental results show that the proposed method can operate accurately and stably at low or high speed, with light or heavy load, and is suitable for practical applications. This approach will not increase cost but will achieve the best performance/cost ratio and meet market expectations.

  9. Lower hybrid heating and current drive design for ITER and application for present tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Froissard, P.; Rey, G.; Bibet, P.; Goniche, M.; Kazarian, F.; Portafaix, C.; Tonon, G. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Bosia, G.; Bruno, L. [ITER Joint Work Site, Garching (Germany); Kuzikov, S. [Inst. of Applied Physics, Nizhny Novgorod (Russian Federation); Wasastjerna, F. [VTT Energy (Finland)

    1998-07-01

    The lower Hybrid Heating and Current Drive (LHH and CD) System shall provide on ITER off-axis current profile control during burn, main contribution to the non-inductive current generation in the advanced Tokamak scenario, current profile tailoring during ramp up phase, heating and current drive during plasma shut-down, extension of the pulse duration during commissioning phase. The LHH and CD system operates at 5 GHz, this frequency being a trade-off between power absorption by alpha particles and klystron technology and couples a minimum of 50 MW using two ITER ports. This article describes the launcher plug and the transmission lines. Specific converters, such as the mode converters, RF windows and the hyper-guide have now been successfully tested at high power and long pulse duration.

  10. Lower hybrid heating and current drive in ignitor shear reversal scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Barbato, E.; Pinaccione, L. [Italian Agengy for New Technologies, Energy and the Environment, Centro Ricerche Frascati, Rome (Italy). Dip. Energia

    1996-05-01

    Injection of Lower Hybrid (LH) Wave power at 8 GHz is considered into IGNITOR shear reversal scenarios, characterized by a reduced plasma current and density. Power deposition calculation are performed to establish whether LH waves can be used both as central heating and off axis current drive tool. It turns out that LH waves can be used (a) for central plasma heating purpose during the current vamp phase, to freeze the shear reversed configuration, at the power level of {approx}10 MW. (b) to drive a current in the outer part of the plasma at the power level of 20 MW. In this way around 1/3-1/6 of the total current in the proper plasma position (i.e. where q is minimum) is driven.

  11. Theory and experiments on RF plasma heating, current drive and profile control in TORE SUPRA

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, D.

    1994-01-01

    This paper reviews the main experimental and theoretical achievements related to the study of RF heating and non-inductive current drive and particularly phenomena related to the current density profile control and the potentiality of producing stationary enhanced performance regimes: description of the Lower Hybrid (LH) and Ion Cyclotron Resonant Frequency (ICRF) systems; long pulse coupling performance of the RF systems; observation of the transition to the so-called ``stationary LHEP regime`` in which the (flat) central current density and (peaked) electron temperature profiles are fully decoupled; experiments on ICRF sawtooth stabilization with the combined effect of LHCD modifying the current density profile; diffusion of fast electrons generated by LH waves; ramp-up experiments in which the LH power provided a significant part of the resistive poloidal flux and flux consumption scaling; theory of spectral wave diffusion and multipass absorption; fast wave current drive modelling with the Alcyon full wave code; a reflector LH antenna concept. 18 figs., 48 refs.

  12. Application of drive circuit based on L298N in direct current motor speed control system

    Science.gov (United States)

    Yin, Liuliu; Wang, Fang; Han, Sen; Li, Yuchen; Sun, Hao; Lu, Qingjie; Yang, Cheng; Wang, Quanzhao

    2016-10-01

    In the experiment of researching the nanometer laser interferometer, our design of laser interferometer circuit system is up to the wireless communication technique of the 802.15.4 IEEE standard, and we use the RF TI provided by Basic to receive the data on speed control system software. The system's hardware is connected with control module and the DC motor. However, in the experiment, we found that single chip microcomputer control module is very difficult to drive the DC motor directly. The reason is that the DC motor's starting and braking current is larger than the causing current of the single chip microcomputer control module. In order to solve this problem, we add a driving module that control board can transmit PWM wave signal through I/O port to drive the DC motor, the driving circuit board can come true the function of the DC motor's positive and reversal rotation and speed adjustment. In many various driving module, the L298N module's integrated level is higher compared with other driver module. The L298N model is easy to control, it not only can control the DC motor, but also achieve motor speed control by modulating PWM wave that the control panel output. It also has the over-current protection function, when the motor lock, the L298N model can protect circuit and motor. So we use the driver module based on L298N to drive the DC motor. It is concluded that the L298N driver circuit module plays a very important role in the process of driving the DC motor in the DC motor speed control system.

  13. Influence of various physics phenomena on fast-wave current drive in advanced tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, D.B.; Jaeger, E.F.; Carter, M.D.; Goldfinger, R.C.; Stallings, D.C. [Oak Ridge National Lab., TN (United States)

    1992-12-31

    The need for some type of noninductive current drive in advanced tokamaks has been recognized for some time. In reactor-grade plasmas, as envisioned in the International Thermonuclear Experimental Reactor (ITER), high density and temperature may limit the penetration of lower hybrid (LH) waves to only the outer layers of the plasma. Fast waves in the ion cyclotron range of frequencies (ICRF), however, can easily penetrate to the center of such high-density plasmas. With sufficient directivity in the launched wave spectrum, currents can be driven by combined damping of the fast waves on resonant electrons through electron Landau damping (ELD) and transit-time magnetic pumping (TTMP). Experiments to study the feasibility of fast-wave current drive (FWCD) have only recently begun, but theoretical predictions look promising. In this paper we analyze the influence of the relevant physics phenomena, which are not necessarily independent, on current drive performance. Such phenomena include diffraction and other nongeometrical optics processes, k{sub ||} modification, single-pass absorption, and antenna characteristics, such as poloidal extent and poloidal location. To do this, we apply a two-and-one-half dimensional (2 1/2-D), full-wave code (PICES) for modeling ion cyclotron resonance heating (ICRH) and current drive based on the poloidal mode expansion method and the reduced-order expansion. By 2 1/2-D, we mean that 3-D wave fields are calculated in axisymmetric geometry (2-D solution domain - r, {theta}), while the correct toroidal dependence of the antenna source currents is obtained from a 2-D (r, {phi}) recessed antenna code. The model includes the poloidal and toroidal structure of the antennas, the modification of the k{sub ||} spectrum due to the poloidal magnetic field, and a nonperturbative solution for E{sub ||}. A semianalytical model for current drive, including trapped electron effects, is employed. (author) 10 refs., 4 figs.

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

    CERN Document Server

    Lallement, JB; CERN. Geneva. BE Department

    2009-01-01

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

  15. Lower Hybrid Heating and Current Drive on the Alcator C-Mod Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    R. Wilson, R. Parker, M. Bitter, P.T. Bonoli, C. Fiore, R.W. Harvey, K. Hill, A.E. Hubbard, J.W. Hughes, A. Ince-Cushman, C. Kessel, J.S. Ko, O. Meneghini, C.K. Phillips, M. Porkolab, J. Rice, A.E. Schmidt, S. Scott,S. Shiraiwa, E. Valeo, G.Wallace, J.C. Wright and the Alcator C-Mod Team

    2009-11-20

    On the Alcator C-Mod tokamak, lower hybrid current drive (LHCD) is being used to modify the current profile with the aim of obtaining advanced tokamak (AT) performance in plasmas with parameters similar to those that would be required on ITER. To date, power levels in excess of 1 MW at a frequency of 4.6 GHz have been coupled into a variety of plasmas. Experiments have established that LHCD on C-Mod behaves globally as predicted by theory. Bulk current drive efficiencies, n20IlhR/Plh ~ 0.25, inferred from magnetics and MSE are in line with theory. Quantitative comparisons between local measurements, MSE, ECE and hard x-ray bremsstrahlung, and theory/simulation using the GENRAY, TORIC-LH CQL3D and TSC-LSC codes have been performed. These comparisons have demonstrated the off-axis localization of the current drive, its magnitude and location dependence on the launched n|| spectrum, and the use of LHCD during the current ramp to save volt-seconds and delay the peaking of the current profile. Broadening of the x-ray emission profile during ICRF heating indicates that the current drive location can be controlled by the electron temperature, as expected. In addition, an alteration in the plasma toroidal rotation profile during LHCD has been observed with a significant rotation in the counter current direction. Notably, the rotation is accompanied by peaking of the density and temperature profiles on a current diffusion time scale inside of the half radius where the LH absorption is taking place.

  16. A mechanism for the dynamo terms to sustain closed-flux current, including helicity balance, by driving current which crosses the magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Jarboe, T. R.; Nelson, B. A.; Sutherland, D. A. [University of Washington, Seattle, Washington 98195 (United States)

    2015-07-15

    An analysis of imposed dynamo current drive (IDCD) [T.R. Jarboe et al., Nucl. Fusion 52 083017 (2012)] reveals: (a) current drive on closed flux surfaces seems possible without relaxation, reconnection, or other flux-surface-breaking large events; (b) the scale size of the key physics may be smaller than is often computationally resolved; (c) helicity can be sustained across closed flux; and (d) IDCD current drive is parallel to the current which crosses the magnetic field to produce the current driving force. In addition to agreeing with spheromak data, IDCD agrees with selected tokamak data.

  17. Advanced launcher design options for electron cyclotron current drive on ITER based on remote steering

    NARCIS (Netherlands)

    Graswinckel, M. R.; Bongers, W. A.; M.R. de Baar,; van den Berg, M. A.; Denisov, G.; Donne, A. J. H.; Elzendoorn, B. S. Q.; Goede, A. P. H.; Heidinger, R.; Kuzikov, S.; Kruijt, O. G.; Kruizinga, B.; Moro, A.; Poli, E.; Ronden, D. M. S.; Saibene, G.; Thoen, D. J.; Verhoeven, A. G. A.

    2008-01-01

    Electron cyclotron current drive will become the main scheme on ITER for the stabilization of neoclassical tearing modes (NTMs) and the control of sawtooth oscillations. The effectiveness of this scheme forms the basis for the requirements of the ITER Upper Port Launcher. These requirements include

  18. Study of multipass regimes in lower hybrid current drive experiments on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Arslanbekov, R.; Litaudon, X.; Peysson, Y.; Hoang, G.T.; Kazarian, F.; Moreau, D. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Shoucri, M.; Shkarofsky, I.P. [Centre Canadien de Fusion Magnetique, Varennes, PQ (Canada); Baranov, Y. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Kupfer, K. [General Atomics, San Diego, CA (United States)

    1995-12-31

    This document presents a study of multipass regimes in Lower Hybrid Current Drive on Tore Supra. A statistical model of the plasma wave propagation based on the Fokker-Planck theory is proposed, together with experimental results performed on Tore Supra. (TEC). 9 refs., 4 figs.

  19. Lower Hybrid Wave Current Drive Efficiency on the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhong-Yong; WAN Bao-Nian; SHI Yue-Jiang; HU Li-Qun; XU Han-Dong; LI Guo-Chao

    2005-01-01

    @@ Lower hybrid (LH) wave current drive efficiency on our HT-7 tokamak has been investigated based on the hot electrical conductivity theory.The interaction of the residual toroidal electric field with fast electrons has been included in the determination of current drive efficiency.The LH wave power scan was performed in the plasma parameter ranges of Ip = 50-156kA, (n)e = 0.5 × 1019-1.6 × 1019 m-3, PLH = 50-350kW.The current drive efficiency is derived to be about 0.1 × 1019-0.4 × 1019 Am-2W-1 on the HT-7 tokamak, which depends on the electron density and the LH wave phase velocity.At the electron density of about 1.5 × 1019 m-3, with the LH wave parallel refraction index peaked at 1.8, the highest current drive efficiency was obtained.A more generally normalized method is introduced to analyse the experimental data, which combines all the data in one curve.The normalized parameters are independent of the plasma parameters.

  20. Fast wave current drive modeling using the combined RANT3D and PICES Codes

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, E.F.; Murakami, M.; Stallings, D.C.; Carter, M.D.; Wang, C.Y.; Galambos, J.D.; Batchelor, D.B.; Baity, F.W.; Bell, G.L.; Wilgen, J.B. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States); Chiu, S.C.; DeGrassie, J.S.; Forest, C.B. [General Atomics, San Diego, California 92186-9784 (United States); Kupfer, K. [ORISE Postdoctoral Fellow at General Atomics, San Diego, California 92186-9784 (United States); Petty, C.C.; Pinsker, R.T.; Prater, R.; Lohr, J. [General Atomics, San Diego, California 92186-9784 (United States); Lee, K.M. [University of California, Los Angeles, California 90024-1597 (United States)

    1996-02-01

    Two numerical codes are combined to give a theoretical estimate of the current drive and direct electron heating by fast waves launched from phased antenna arrays on the DIII-D tokamak. Results are compared with experiment. {copyright} {ital 1996 American Institute of Physics.}

  1. Compensation methods applied in current control schemes for large AC drive systems

    DEFF Research Database (Denmark)

    Rus, D. C.; Preda, N. S.; Teodorescu, Remus;

    2012-01-01

    The paper deals with modified PI current control structures for large AC drive systems which use surface mounted permanent magnet synchronous machines or squirrel-cage induction motors supplied with voltage source inverters. In order to reduce the power losses caused by high frequency switching...

  2. Impact of heating and current drive mix on the ITER hybrid scenario

    NARCIS (Netherlands)

    Citrin, J.; Artaud, J. F.; Garcia, J.; Hogeweij, G. M. D.; Imbeaux, F.

    2010-01-01

    Hybrid scenario performance in ITER is studied with the CRONOS integrated modelling suite, using the GLF23 anomalous transport model for heat transport prediction. GLF23 predicted core confinement is optimized through tailoring the q-profile shape by a careful choice of current drive actuators, affe

  3. Globalisation and the foreignisation of space: The seven processes driving the current global land grab.

    NARCIS (Netherlands)

    Zoomers, E.B.

    2010-01-01

    The current global land grab is causing radical changes in the use and ownership of land. The main process driving the land grab, or ‘foreignisation of space’, as highlighted in the media and the emerging literature is the production of food and biofuel for export in the aftermath of recent food and

  4. Derivation of dynamo current drive in a closed-current volume and stable current sustainment in the HIT-SI experiment

    Science.gov (United States)

    Hossack, A. C.; Sutherland, D. A.; Jarboe, T. R.

    2017-02-01

    A derivation is given showing that the current inside a closed-current volume can be sustained against resistive dissipation by appropriately phased magnetic perturbations. Imposed-dynamo current drive theory is used to predict the toroidal current evolution in the helicity injected torus with steady inductive helicity injection (HIT-SI) experiment as a function of magnetic fluctuations at the edge. Analysis of magnetic fields from a HIT-SI discharge shows that the injector-imposed fluctuations are sufficient to sustain the measured toroidal current without instabilities whereas the small, plasma-generated magnetic fluctuations are not sufficiently large to sustain the current.

  5. "When can I return to driving?": a review of the current literature on returning to driving after lower limb injury or arthroplasty.

    Science.gov (United States)

    MacLeod, K; Lingham, A; Chatha, H; Lewis, J; Parkes, A; Grange, S; Smitham, P J

    2013-03-01

    Clinicians are often asked by patients, "When can I drive again?" after lower limb injury or surgery. This question is difficult to answer in the absence of any guidelines. This review aims to collate the currently available evidence and discuss the factors that influence the decision to allow a patient to return to driving. Medline, Web of Science, Scopus, and EMBASE were searched using the following terms: 'brake reaction time', 'brake response time', 'braking force', 'brake pedal force', 'resume driving', 'rate of application of force', 'driving after injury', 'joint replacement and driving', and 'fracture and driving'. Of the relevant literature identified, most studies used the brake reaction time and total brake time as the outcome measures. Varying recovery periods were proposed based on the type and severity of injury or surgery. Surveys of the Driver and Vehicle Licensing Agency, the Police, insurance companies in the United Kingdom and Orthopaedic Surgeons offered a variety of opinions. There is currently insufficient evidence for any authoritative body to determine fitness to drive. The lack of guidance could result in patients being withheld from driving for longer than is necessary, or returning to driving while still unsafe.

  6. Experimental Verification of Current Shear Design Equations for HSRC Beams

    Directory of Open Access Journals (Sweden)

    Attaullah Shah

    2012-07-01

    Full Text Available Experimental research on the shear capacity of HSRC (High Strength Reinforced Concrete beams is relatively very limited as compared to the NSRC (Normal Strength Reinforced Concrete beams. Most of the Building Codes determine the shear strength of HSRC with the help of empirical equations based on experimental work of NSRC beams and hence these equations are generally regarded as un-conservative for HSRC beams particularly at low level of longitudinal reinforcement. In this paper, 42 beams have been tested in two sets, such that in 21 beams no transverse reinforcement has been used, whereas in the remaining 21 beams, minimum transverse reinforcement has been used as per ACI-318 (American Concrete Institute provisions. Two values of compressive strength 52 and 61 MPa, three values of longitudinal steel ratio and seven values of shear span to depth ratio have been have been used. The beams were tested under concentrated load at the mid span. The results are compared with the equations proposed by different international building codes like ACI, AASHTO LRFD, EC (Euro Code, Canadian Code and Japanese Code for shear strength of HSRC beams.From comparison, it has been observed that some codes are less conservative for shear design of HSRC beams and further research is required to rationalize these equations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Greene, J. P.; Gabor, R.; Neubauer, J.

    2000-11-29

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

  8. A Smart Current Modulation Scheme for Harmonic Reduction in Three- Phase Motor Drive Applications

    DEFF Research Database (Denmark)

    Davari, Pooya; Zare, Firuz; Blaabjerg, Frede

    2015-01-01

    harmonic mitigation methods have been developed over the years, the total cost and complexity has become the main obstacle in employing prior-art methods for motor drive systems. This paper presents a novel current modulation method based on the electronic inductor concept for three-phase ac-dc systems......Electric motor-driven systems consume considerable amount of the global electricity. Majority of three-phase motor drives are equipped with conventional diode rectifier and passive harmonic mitigation, being witnessed as the main source in generating input current harmonics. While many active...... to reduce input current harmonics. The obtained results at simulation and experimental levels confirm the effectiveness of the proposed approach....

  9. An analysis of JET fast-wave heating and current drive experiments directly related to ITER

    Energy Technology Data Exchange (ETDEWEB)

    Bhatnagar, V.P.; Eriksson, L.; Gormezano, C.; Jacquinot, J.; Kaye, A.; Start, D.F.H. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    The ITER fast-wave system is required to serve a variety of purposes, in particular, plasma heating to ignition, current profile and burn control and eventually, in conjunction with other schemes, a central non-inductive current drive (CD) for the steady-state operation of ITER. The ICRF heating and current drive data that has been obtained in JET are analyzed in terms of dimensionless parameters, with a view to ascertaining its direct relevance to key ITER requirements. The analysis is then used to identify areas both in physics and technological aspects of ion-cyclotron resonance heating (ICRH) and CD that require further experimentation in ITER-relevant devices such as JET to establish the required data base. (authors). 12 refs., 8 figs.

  10. Resistive wall heating due to image current on the beam chamber for a superconducting undulator.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. H. (Accelerator Systems Division (APS))

    2012-03-27

    The image-current heating on the resistive beam chamber of a superconducting undulator (SCU) was calculated based on the normal and anomalous skin effects. Using the bulk resistivity of copper for the beam chamber, the heat loads were calculated for the residual resistivity ratios (RRRs) of unity at room temperature to 100 K at a cryogenic temperature as the reference. Then, using the resistivity of the specific aluminum alloy 6053-T5, which will be used for the SCU beam chamber, the heat loads were calculated. An electron beam stored in a storage ring induces an image current on the inner conducting wall, mainly within a skin depth, of the beam chamber. The image current, with opposite charge to the electron beam, travels along the chamber wall in the same direction as the electron beam. The average current in the storage ring consists of a number of bunches. When the pattern of the bunched beam is repeated according to the rf frequency, the beam current may be expressed in terms of a Fourier series. The time structure of the image current is assumed to be the same as that of the beam current. For a given resistivity of the chamber inner wall, the application ofthe normal or anomalous skin effect will depend on the harmonic numbers of the Fourier series of the beam current and the temperature of the chamber. For a round beam chamber with a ratius r, much larger than the beam size, one can assume that the image current density as well as the density square, may be uniform around the perimeter 2{pi}r. For the SCU beam chamber, which has a relatively narrow vertical gap compared to the width, the effective perimeter was estimated since the heat load should be proportional to the inverse of the perimeter.

  11. A Phase Current Reconstruction Approach for Three-Phase Permanent-Magnet Synchronous Motor Drive

    Directory of Open Access Journals (Sweden)

    Hao Yan

    2016-10-01

    Full Text Available Three-phase permanent-magnet synchronous motors (PMSMs are widely used in renewable energy applications such as wind power generation, tidal energy and electric vehicles owing to their merits such as high efficiency, high precision and high reliability. To reduce the cost and volume of the drive system, techniques of reconstructing three-phase current using a single current sensor have been reported for three-phase alternating current (AC control system using the power converts. In existing studies, the reconstruction precision is largely influenced by reconstructing dead zones on the Space Vector Pulse Width Modulation (SVPWM plane, which requires other algorithms to compensate either by modifying PWM modulation or by phase-shifting of the PWM signal. In this paper, a novel extended phase current reconstruction approach for PMSM drive is proposed. Six novel installation positions are obtained by analyzing the sampling results of the current paths between each two power switches. By arranging the single current sensor at these positions, the single current sensor is sampled during zero voltage vectors (ZVV without modifying the PWM signals. This proposed method can reconstruct the three-phase currents without any complex algorithms and is available in the sector boundary region and low modulation region. Finally, this method is validated by experiments.

  12. Cryogenic Current Comparator as Low Intensity Beam Current Monitor in the CERN Antiproton Decelerators

    CERN Document Server

    Fernandes, M; Soby, L; Welsch, CP

    2013-01-01

    In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor any losses during the deceleration and cooling phases. However, existing DC current transformers can hardly reach the μA level, while at the AD and ELENA currents can be as low as 100 nA. A Cryogenic Current Comparator (CCC) based on a superconducting quantum interference device (SQUID) is currently being designed and shall be installed in the AD and ELENA machines. It should meet the following specifications: A current resolution smaller than 10 nA, a dynamic range covering currents between 100 nA and 1 mA, as well as a bandwidth from DC to 1 kHz. Different design options are being considered, including the use of low or high temperature superconductor materials, different CCC shapes and dimensions, different SQUID characteristics, as well as electromagnetic shielding requirements. In this contribution we present first results f...

  13. Current Reversal Due to Coupling Between Asymmetrical Driving Force and Ratchet Potential

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.

  14. Proton beam therapy in Japan: current and future status.

    Science.gov (United States)

    Sakurai, Hideyuki; Ishikawa, Hitoshi; Okumura, Toshiyuki

    2016-10-01

    The number of patients treated by proton beam therapy in Japan since 2000 has increased; in 2016, 11 proton facilities were available to treat patients. Notably, proton beam therapy is very useful for pediatric cancer; since the pediatric radiation dose to normal tissues should be reduced as much as possible because of the effect of radiation on growth, intellectual development, endocrine organ function and secondary cancer development. Hepatocellular carcinoma is common in Asia, and most of the studies of proton beam therapy for liver cancer have been reported by Japanese investigators. Proton beam therapy is also a standard treatment for nasal and paranasal lesions and lesions at the base of the skull, because the radiation dose to critical organs such as the eyes, optic nerves and central nervous system can be reduced with proton beam therapy. For prostate cancer, comparative studies that address adverse effects, safety, patient quality of life and socioeconomic issues should be performed to determine the appropriate use of proton beam therapy for prostate cancer. Regarding new proton beam therapy applications, experience with proton beam therapy combined with chemotherapy is limited, although favorable outcomes have been recently reported for locally advanced lung cancer, esophageal cancer and pancreatic cancer. Therefore, 'chemoproton' therapy appears to be a very attractive field for further clinical investigations. In conclusion, there are cost issues and considerations regarding national insurance for the use of proton beam therapy in Japan. Further studies and discussions are needed to address the use of proton beam therapy for several types of cancers, and for maintaining the quality of life of patients while retaining a high cure rate.

  15. Design of long-pulse fast wave current drive antennas for DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Baity, F.W.; Batchelor, D.B.; Bills, K.C.; Fogelman, C.H.; Jaeger, E.F.; Ping, J.L.; Riemer, B.W.; Ryan, P.M.; Stallings, D.C.; Taylor, D.J.; Yugo, J.J. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States))

    1994-10-15

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90[degree] phasing into a low-density plasma ([similar to]4[times]10[sup 19]m[sup [minus]3]) with hot electrons ([similar to]10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  16. Design of Current Controller for Two Quadrant DC Motor Drive by Using Model Order Reduction Technique

    CERN Document Server

    Ramesh, K; Nirmalkumar, A; Gurusamy, G

    2010-01-01

    In this paper, design of current controller for a two quadrant DC motor drive was proposed with the help of model order reduction technique. The calculation of current controller gain with some approximations in the conventional design process is replaced by proposed model order reduction method. The model order reduction technique proposed in this paper gives the better controller gain value for the DC motor drive. The proposed model order reduction method is a mixed method, where the numerator polynomial of reduced order model is obtained by using stability equation method and the denominator polynomial is obtained by using some approximation technique preceded in this paper. The designed controllers responses were simulated with the help of MATLAB to show the validity of the proposed method.

  17. Fast electron dynamics in lower hybrid current drive experiment on HT-7 tokamak

    Institute of Scientific and Technical Information of China (English)

    Shi Yue-Jiang; Kuang Gang-Li; Li Jian-Gang; HT-7 Team; Wan Bao-Nian; Chen Zhong-Yong; Hu Li-Qun; Lin Shi-Yao; Ruan Huai-Lin; Qian Jin-Ping; Zhen Xiang-Jun; Ding Bo-Jiang

    2005-01-01

    The dynamic behaviour of fast electron in lower hybrid current drive (LHCD) experiments is a crucial issue in the sense of enhancing plasma performance. A new hard x-ray diagnostic system on HT-7 allows the investigation of the lower hybrid wave dynamics. The behaviour of fast electron is studied in several kinds of LHCD experiments, including long pulse discharges, high performance discharges and counter-LHCD experiments.

  18. First principles fluid modelling of magnetic island stabilization by electron cyclotron current drive (ECCD)

    Science.gov (United States)

    Février, O.; Maget, P.; Lütjens, H.; Luciani, J. F.; Decker, J.; Giruzzi, G.; Reich, M.; Beyer, P.; Lazzaro, E.; Nowak, S.; the ASDEX Upgrade Team

    2016-04-01

    Tearing modes are MagnetoHydroDynamics (MHD) instabilities that reduce the performance of fusion devices. They can however be controlled and suppressed using electron cyclotron current drive (ECCD) as demonstrated in various tokamaks. In this work, simulations of island stabilization by ECCD-driven current have been carried out using the toroidal nonlinear 3D full MHD code xtor-2f, in which a current source term modeling the ECCD has been implemented. The efficiency parameter, {η\\text{RF}} , has been computed and its variations with respect to source width and location were also computed. The influence of parameters such as current intensity, source width and position with respect to the island was evaluated and compared to the modified Rutherford equation. We retrieved a good agreement between the simulations and the analytical predictions concerning the variations of control efficiency with source width and position. We also show that the 3D nature of the current source term can lead to the onset of an island if the source term is precisely applied on a rational surface. We report the observation of a flip phenomenon in which the O- and X-points of the island rapidly switch their position in order for the island to take advantage of the current drive to grow.

  19. On the Current Drive Capability of Low Dimensional Semiconductors: 1D versus 2D

    Science.gov (United States)

    Zhu, Y.; Appenzeller, J.

    2015-10-01

    Low-dimensional electronic systems are at the heart of many scaling approaches currently pursuit for electronic applications. Here, we present a comparative study between an array of one-dimensional (1D) channels and its two-dimensional (2D) counterpart in terms of current drive capability. Our findings from analytical expressions derived in this article reveal that under certain conditions an array of 1D channels can outperform a 2D field-effect transistor because of the added degree of freedom to adjust the threshold voltage in an array of 1D devices.

  20. On the Current Drive Capability of Low Dimensional Semiconductors: 1D versus 2D.

    Science.gov (United States)

    Zhu, Y; Appenzeller, J

    2015-12-01

    Low-dimensional electronic systems are at the heart of many scaling approaches currently pursuit for electronic applications. Here, we present a comparative study between an array of one-dimensional (1D) channels and its two-dimensional (2D) counterpart in terms of current drive capability. Our findings from analytical expressions derived in this article reveal that under certain conditions an array of 1D channels can outperform a 2D field-effect transistor because of the added degree of freedom to adjust the threshold voltage in an array of 1D devices.

  1. Recent progress on lower hybrid current drive and implications for ITER

    CERN Document Server

    Hillairet, Julien; Goniche, M; Achard, J; Armitano, A; Beckett, B; Belo, J; Berger-By, G; Corbel, E; Delpech, L; Decker, J; Dumont, R; Guilhem, D; Kazarian, F; Litaudon, X; Magne, R; Marfisi, L; Mollard, P; Namkung, W; Nilsson, E; Park, S; Peysson, Y; Preynas, M; Sharma, P K; Prou, M

    2015-01-01

    The sustainment of steady-state plasmas in tokamaks requires efficient current drive systems. Lower Hybrid Current Drive (LHCD) is currently the most efficient method to generate a continuous additional off-axis toroidal plasma current as well as reduce the poloidal flux consumption during the plasma current ramp-up phase. The operation of the Tore Supra ITER-like LH launcher has demonstrated the capability to couple LH power at ITER-like power densities with very low reflected power during long pulses. In addition, the installation of eight 700kW/CW klystrons at the LH transmitter has allowed increasing the total LH power in long pulse scenarios. However, in order to achieve pure stationary LH sustained plasmas, some R\\&D are needed to increase the reliability of all the systems and codes, from the RF sources to the plasma scenario prediction. The CEA/IRFM is addressing some of these issues by leading a R\\&D program towards an ITER LH system and by the validation of an integrated LH modeling suite of...

  2. A New High Speed Induction Motor Drive based on Field Orientation and Hysteresis Current Comparison

    Science.gov (United States)

    Ogbuka, Cosmas; Nwosu, Cajethan; Agu, Marcel

    2016-09-01

    This paper presents a new high speed induction motor drive based on the core advantage of field orientation control (FOC) and hysteresis current comparison (HCC). A complete closed loop speed-controlled induction motor drive system is developed consisting of an outer speed and an inner HCC algorithm which are optimised to obtain fast and stable speed response with effective current and torque tracking, both during transient and steady states. The developed model, being speed-controlled, was examined with step and ramp speed references and excellent performances obtained under full load stress. A speed response comparison of the model with the standard AC3 (Field-Oriented Control Induction Motor Drive) of MATLAB Simpower systems shows that the model achieved a rise time of 0.0762 seconds compared to 0.2930 seconds achieved by the AC3. Also, a settle time of 0.0775 seconds was obtained with the developed model while that of the AC3 model is 0.2986 seconds confirming, therefore, the superiority of the developed model over the AC3 model which, hitherto, served as a reference standard.

  3. A Modified Bridgeless Converter for SRM Drive with Reduced Ripple Current

    Directory of Open Access Journals (Sweden)

    Maheswari C krishnakumar

    2015-06-01

    Full Text Available Single Phase Switched Reluctance Motor is more popular in many industrial purposes for high speed applications because of its robust and rugged construction. For low cost and variable speed drive applications SRM are widely used.Due to doubly salient structure of motor, the torque pulsations are high when compared to other sinusoidal machines. The major drawback in using SRM drive is torque pulsations and increased number of switching components. In order to overcome these drawbacks, a bridgeless Single Ended Primary Inductor Converter (SEPIC is proposed. The major advantages of this converter are continuous output current,smaller voltage ripple and reduced semiconductor current stress when compared to the conventional SEPIC converter. The ripple free input current is obtained by using additional winding of input inductor and auxiliary capacitors. To achieve high efficiency, active power factor correction circuits (PFC are employed to precise the power factor. Further, the unity power factor can be obtained by making the input current during switching period proportional to the input voltage is proposed. The proposed system consists of reduced components and it is also capable of reducing the conduction losses. The working principles and the waveforms of proposed converter are analyzed. To analyze the circuit operation, theoretical analysis and simulation results are provided. Finally, the  comparison between the waveforms of conventional SEPIC and proposed system is presented by using MATLAB/Simulink tools.

  4. Electron cyclotron heating and current drive in toroidal geometry. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kritz, A.H.

    1991-11-01

    The Principal Investigator has continued to work on problems associated both with the deposition and with the emission of electron cyclotron power in toroidal plasmas. We have investigated the use of electron cyclotron resonance heating for bringing compact tokamaks (BPX) to ignition-like parameters. This requires that we continue to refine the modeling capability of the TORCH code linked with the BALDUR 1 {1/2} D transport code. Using this computational tool, we have examined the dependence of ignition on heating and transport employing both theoretical (multi-mode) and empirically based transport models. The work on current drive focused on the suppression of tearing modes near the q = 2 surface and sawteeth near the q = 1 surface. Electron cyclotron current drive in CIT near the q =2 surface was evaluated for a launch scenario where electron cyclotron power was launched near the equatorial plane. The work on suppression of sawteeth has been oriented toward understanding the suppression that has been observed in a number of tokamaks, in particular, in the WT-3 tokamak in Kyoto. To evaluate the changes in current profile (shear) near the q =1 surface, simulations have been carried out using the linked BALDUR-TORCH code. We consider effects on shear resulting both from wave-induced current as well as from changes in conductivity associated with changes in local temperature. Abstracts and a paper relating to this work is included in Appendix A.

  5. Lower Hybrid Current Drive Experiments on Alcator C-Mod: Comparison with Theory and Simulation

    Science.gov (United States)

    Bonoli, Paul

    2007-11-01

    Recently, lower hybrid current drive (LHCD) experiments have been carried out on Alcator C-Mod using an RF system consisting of 12 klystrons at 4.6 GHz, feeding a 4 x 22 waveguide array. Up to 900 kW of LH power has been coupled in the range1.6 PLH 0.3 [1]. We have simulated the LH current drive in these discharges using the combined ray tracing / 3D (r, v, v//) Fokker Planck code GENRAY -- CQL3D [2] and found similar current drive efficiencies. Measurements of nonthermal x-ray emission and electron cyclotron emission (ECE) confirm the presence of a significant fast electron population that varies with waveguide phasing and plasma density. Studies are currently underway to investigate the role of fast electron diffusion and full-wave effects such as diffractional broadening in determining the spatial and velocity space structure of the nonthermal electrons. The 3D (r, v, v//) electron distribution function from CQL3D has been used in synthetic diagnostic codes to simulate the measured hard x-ray and ECE emissions. Fast electron diffusion times have been inferred from x-ray data by employing a radial diffusion operator in CQL3D and determining the fast electron diffusivities that are required to reproduce the experimentally observed profiles of hard x-ray emission. Finally, we have been performing full-wave LH field simulations using the massively parallel TORIC --LH solver [3] in order to assess spatial and spectral broadening of the incident wave front that can result from diffraction and wave focusing effects. [1] R. Parker, Bull. Am. Phys. Soc. 51, 20 (2006). [2] R.W. Harvey and M. McCoy, ``The CQL3D Fokker Planck Code,'' Proc. IAEA Tech. Comm. Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992. [3] J. C. Wright et al., Nucl. Fusion 45, 1411 (2005).

  6. Generation of Ramped Current Profiles in Relativistic Electron Beams Using Wakefields in Dielectric Structures

    Science.gov (United States)

    Andonian, G.; Barber, S.; O'Shea, F. H.; Fedurin, M.; Kusche, K.; Swinson, C.; Rosenzweig, J. B.

    2017-02-01

    Temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefield diagnostics and pulse profile reconstruction techniques.

  7. Generation of Ramped Current Profiles in Relativistic Electron Beams Using Wakefields in Dielectric Structures.

    Science.gov (United States)

    Andonian, G; Barber, S; O'Shea, F H; Fedurin, M; Kusche, K; Swinson, C; Rosenzweig, J B

    2017-02-03

    Temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefield diagnostics and pulse profile reconstruction techniques.

  8. Direct Drive and Eddy Current Septa Magnet Designs for CERN’s PSB Extraction at 2 GeV

    CERN Multimedia

    Szoke, Zsolt; Balhan, Bruno; Baud, Cedric; Borburgh, Jan; Hourican, Michael; Masson, Thierry; Prost, Antoine

    2015-01-01

    In the framework of the LIU project, new septa magnets have been designed between CERN’s PS Booster (PSB) extraction and PS injection. The upgraded devices are to deal with the increased beam energy from 1.4 GeV to 2 GeV at extraction of the PSB. The direct drive recombination septa in the PSB transfer line to the PS, the eddy current PS injection septum together with a bumper at injection have been investigated using finite element software. For the recombination magnets an increase in magnet length is sufficient to obtain the required deflection; however, for the PS injection elements a more novel solution is necessary to also achieve increased robustness to extend the expected lifetime of the pulsed device. The injection septum will share the same vacuum vessel with an injection bumper and both magnets will be located adjacent to each other. The new PS injection magnet will be the first septum operated at CERN based on eddy current technology. The magnetic modelling of the devices, the comparison of the ...

  9. Current drive with combined electron cyclotron wave and high harmonic fast wave in tokamak plasmas

    Science.gov (United States)

    Li, J. C.; Gong, X. Y.; Dong, J. Q.; Wang, J.; Zhang, N.; Zheng, P. W.; Yin, C. Y.

    2016-12-01

    The current driven by combined electron cyclotron wave (ECW) and high harmonic fast wave is investigated using the GENRAY/CQL3D package. It is shown that no significant synergetic current is found in a range of cases with a combined ECW and fast wave (FW). This result is consistent with a previous study [Harvey et al., in Proceedings of IAEA TCM on Fast Wave Current Drive in Reactor Scale Tokamaks (Synergy and Complimentarily with LHCD and ECRH), Arles, France, IAEA, Vienna, 1991]. However, a positive synergy effect does appear with the FW in the lower hybrid range of frequencies. This positive synergy effect can be explained using a picture of the electron distribution function induced by the ECW and a very high harmonic fast wave (helicon). The dependence of the synergy effect on the radial position of the power deposition, the wave power, the wave frequency, and the parallel refractive index is also analyzed, both numerically and physically.

  10. High voltage power supplies for ITER RF heating and current drive systems

    Energy Technology Data Exchange (ETDEWEB)

    Gassmann, T., E-mail: thibault.gassmann@iter.org [ITER Organization, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Arambhadiya, B.; Beaumont, B. [ITER Organization, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Baruah, U.K. [Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar 382428 (India); Bonicelli, T. [Fusion For Energy, C/3 Josep Pla 2, Torres Diagonal Litoral-B3, E-08019 Barcelona (Spain); Darbos, C.; Purohit, D.; Decamps, H. [ITER Organization, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Albajar, F. [Fusion For Energy, C/3 Josep Pla 2, Torres Diagonal Litoral-B3, E-08019 Barcelona (Spain); Gandini, F.; Henderson, M.; Kazarian, F.; Lamalle, P.U.; Omori, T. [ITER Organization, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Parmar, D.; Patel, A. [Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar 382428 (India); Rathi, D. [ITER Organization, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Singh, N.P. [Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar 382428 (India)

    2011-10-15

    The RF heating and current drive (H and CD) systems to be installed for the ITER fusion machine are the electron cyclotron (EC), ion cyclotron (IC) and, although not in the first phase of the project, lower hybrid (LH). These systems require high voltage, high current power supplies (HVPS) in CW operation. These HVPS should deliver around 50 MW electrical power to each of the RF H and CD systems with stringent requirements in terms of accuracy, voltage ripple, response time, turn off time and fault energy. The PSM (Pulse Step Modulation) technology has demonstrated over the past 20 years its ability to fulfill these requirements in many industrial facilities and other fusion reactors and has therefore been chosen as reference design for the IC and EC HVPS systems. This paper describes the technical specifications, including interfaces, the resulting constraints on the design, the conceptual design proposed for ITER EC and IC HVPS systems and the current status.

  11. Evolution of Wave Energy Deposition Profile in HT-7 Lower Hybrid Current Drive Experiment

    Institute of Scientific and Technical Information of China (English)

    方瑜德; 石跃江; 匡光力; 刘岳修; 沈慰慈; 丁伯江

    2001-01-01

    Lower hybrid waves (LHWs) with a selected n‖ spectrum have been used to control the energy deposition profiles, and then the wave driven current profiles effectively in tokamak discharges. In our lower hybrid current drive experiment in the HT-7 tokamak, it was found that the set-up of the wave energy deposition profile is a graduation process. In the beginning phase of the wave injection duration, the waves (with different n‖ spectra)deposit almost all their energy in the central region of the plasma column, even if their n‖ are very different. Up to around one hundred milliseconds, the wave energy deposition profiles can only take their corresponding shapes according to the n‖ spectra of LHWs. It also shown that this evolution process is affected obviously by the LHW driven current profile, which has been formed early.

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

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2010-01-01

    In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring......, oscillations in the power etc. For this reason the integrating action of the speed controller must be limited leading to offsets in the speed control and a poor response to load torque variations. For this reason a load torque estimator is proposed in this paper in order to further improve MPDCC dynamic...... the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress...

  13. Broadband sidebands generated by parametric instability in lower hybrid current drive experiments on EAST

    Energy Technology Data Exchange (ETDEWEB)

    Amicucci, L., E-mail: luca.amicucci@enea.it; Castaldo, C.; Cesario, R.; Giovannozzi, E.; Tuccillo, A. A. [EUROfusion-ENEA, Centro Ricerche Frascati, Unità Fusione, Frascati (Italy); Ding, B. J.; Li, M. H. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2015-12-10

    Modern research on nuclear fusion energy, based on the tokamak concept, has strong need of tools for actively driving non-inductive current especially at the periphery of plasma column, where tools available so far have poor efficiency. This is essential for solving one of the most critical problems for thermonuclear reactor, consisting in how to achieve the figure of fusion gain in the context of sufficient stability. The lower hybrid current drive (LHCD) effect has the potential capability of driving current at large radii of reactor plasma with high efficiency [1]. Experiments recently carried out on EAST showed that a strong activity of LH sideband waves (from the RF probe spectra), accompanied by weak core penetration of the coupled LH power, is present when operating at relatively high plasma densities. Previous theoretical results, confirmed by experiments on FTU, showed that the LH sideband phenomenon is produced by parametric instability (PI), which are mitigated by higher plasma edge temperatures. This condition is thus useful for enabling the LH power propagation when operating with profiles having high plasma densities even at the edge. In the present work, we show new PI modeling of EAST plasmas data, obtained in condition of higher plasma edge temperature due to chamber lithisation. The obtained trend of the PI frequencies and growth rates is consistent with data of RF probe spectra, available in different regimes of lithisated and not lithisated vessel. Moreover, these spectra are interpreted as PI effect occurring at the periphery of plasma column, however in the low field side where the LH power is coupled.

  14. Broadband sidebands generated by parametric instability in lower hybrid current drive experiments on EAST

    Science.gov (United States)

    Amicucci, L.; Ding, B. J.; Castaldo, C.; Cesario, R.; Giovannozzi, E.; Li, M. H.; Tuccillo, A. A.

    2015-12-01

    Modern research on nuclear fusion energy, based on the tokamak concept, has strong need of tools for actively driving non-inductive current especially at the periphery of plasma column, where tools available so far have poor efficiency. This is essential for solving one of the most critical problems for thermonuclear reactor, consisting in how to achieve the figure of fusion gain in the context of sufficient stability. The lower hybrid current drive (LHCD) effect has the potential capability of driving current at large radii of reactor plasma with high efficiency [1]. Experiments recently carried out on EAST showed that a strong activity of LH sideband waves (from the RF probe spectra), accompanied by weak core penetration of the coupled LH power, is present when operating at relatively high plasma densities. Previous theoretical results, confirmed by experiments on FTU, showed that the LH sideband phenomenon is produced by parametric instability (PI), which are mitigated by higher plasma edge temperatures. This condition is thus useful for enabling the LH power propagation when operating with profiles having high plasma densities even at the edge. In the present work, we show new PI modeling of EAST plasmas data, obtained in condition of higher plasma edge temperature due to chamber lithisation. The obtained trend of the PI frequencies and growth rates is consistent with data of RF probe spectra, available in different regimes of lithisated and not lithisated vessel. Moreover, these spectra are interpreted as PI effect occurring at the periphery of plasma column, however in the low field side where the LH power is coupled.

  15. The targeted heating and current drive applications for the ITER electron cyclotron system

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, M.; Darbos, C.; Gandini, F.; Gassmann, T.; Loarte, A.; Omori, T.; Purohit, D. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Saibene, G.; Gagliardi, M. [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Farina, D.; Figini, L. [Istituto di Fisica del Plasma CNR, 20125 Milano (Italy); Hanson, G. [US ITER Project Office, ORNL, 1055 Commerce Park, PO Box 2008, Oak Ridge, Tennessee 37831 (United States); Poli, E. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany); Takahashi, K. [Japan Atomic Energy Agency (JAEA), Naka, Ibaraki 311-0193 (Japan)

    2015-02-15

    A 24 MW Electron Cyclotron (EC) system operating at 170 GHz and 3600 s pulse length is to be installed on ITER. The EC plant shall deliver 20 MW of this power to the plasma for Heating and Current Drive (H and CD) applications. The EC system is designed for plasma initiation, central heating, current drive, current profile tailoring, and Magneto-hydrodynamic control (in particular, sawteeth and Neo-classical Tearing Mode) in the flat-top phase of the plasma. A preliminary design review was performed in 2012, which identified a need for extended application of the EC system to the plasma ramp-up, flattop, and ramp down phases of ITER plasma pulse. The various functionalities are prioritized based on those applications, which can be uniquely addressed with the EC system in contrast to other H and CD systems. An initial attempt has been developed at prioritizing the allocated H and CD applications for the three scenarios envisioned: ELMy H-mode (15 MA), Hybrid (∼12 MA), and Advanced (∼9 MA) scenarios. This leads to the finalization of the design requirements for the EC sub-systems.

  16. Reduction of current chopping noise with DSP controller in switched reluctance motor drive system

    Institute of Scientific and Technical Information of China (English)

    郭伟; 詹琼华; 马志源

    2002-01-01

    A novel current chopping mode was used in a switched reluctance motor drive system to make full use of the characteristics of digital signal processor (DSP) TMS320F240. The necessity of this 180° phase-shift current control (PSCC) mode is introduced first and then the principle of PSCC covering both hardware requirement and software programming is described in detail. The analysis made indicated that with this mode, the chopping frequency in winding can reach 20 kHz with 10 kHz power switches and the control frequency can reach 40 kHz at the same time. Subsequently, based on the linear and nonlinear mathematical models of the switched reluctance motor ( SRM), some simulation work has been done. The simulation results show that when this mode is applied to SRM drive (SRD) system, the current waveform becomes better. So the ripple of the torque is reduced simultaneously and the vibration and acoustic noise are reduced involuntarily. Stationary tests show that the acoustic noise is greatly diminished. Finally, some experiments were made using a 50 kW SRD system for electric vehicle (EV). Experimental results indicate that this mode can be implemented feasibly and it has a good action on the SRD system.

  17. Effort of lower hybrid current drive experiments toward to H-mode in EAST

    Science.gov (United States)

    Ding, B. J.; Li, M. H.; Liu, F. K.; Shan, J. F.; Li, Y. C.; Wang, M.; Liu, L.; Zhao, L. M.; Yang, Y.; Wu, Z. G.; Feng, J. Q.; Hu, H. C.; Jia, H.; Cheng, M.; Zang, Q.; Lyu, B.; Duan, Y. M.; Lin, S. Y.; Wu, J. H.; Hillairet, J.; Ekedahl, A.; Peysson, Y.; Goniche, M.; Tuccillo, A. A.; Cesario, R.; Amicucci, L.; Shen, B.; Gong, X. Z.; Xu, G. S.; Zhao, H. L.; Hu, L. Q.; Li, J. G.; Wan, B. N.; EAST Team

    2017-02-01

    Lower hybrid current drive (LHCD) is an effective tool to achieve high confinement (H-mode) plasma in EAST. To utilize LHCD for accessing H-mode plasma, efforts have been made to improve LHW (lower hybrid wave)-plasma coupling and current drive capability at high density. Improved LHW-plasma coupling by means of local gas puffing and gas puffing from the electron side is routinely used during EAST operation with LHCD. High density experiments suggest that low recycling and high LH frequency are preferred for LHCD experiments at high density, consistent with previous results in other machines. The effect of LHCD on the current profile in EAST demonstrates that it is possible to control the plasma profile by optimizing the LHW spectrum. Repeatable H-mode plasma was obtained by LHCD and the maximum density during H-mode with the combination of 2.45 GHz and 4.6 GHz LH waves was up to 4.5  ×  1019 m-3.

  18. Reduced Order Models of a Current Source Inverter Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    Ibrahim K. Al-Abbas

    2009-01-01

    Full Text Available Problem Statement: The current source inverter induction motor (CSI-IM drive was widely used in various industries. The main disadvantage of this drive was nonlinearity and complexity. This work was done to develop a simple drive systems models. Approach: The MATLAB/SIMULINK software was used for system modeling. Three reduced models were developed by choosing specific frame, neglecting stator transients and ignoring stator equations. Results: The dynamic performance of the models was examined in open loop form for a step change in control variable (the input voltage as well as for step change in disturbance (mechanical load.Conclusion: The three models were equivalent in steady state. The error of these models in the transient response was less than 5 %, with the exception of the time performances of the transient model to step change of supply voltage. Recommendations: All three models were suggested to be used for designing torque control systems. The detailed and stator equation models were recommended to be used in speed control design.

  19. Destabilization of fast particle stabilized sawteeth in ASDEX Upgrade with electron cyclotron current drive

    DEFF Research Database (Denmark)

    Igochine, V.; Chapman, I.T.; Bobkov, V.;

    2011-01-01

    It is often observed that large sawteeth trigger the neoclassical tearing mode well below the usual threshold for this instability. At the same time, fast particles in the plasma core stabilize sawteeth and provide these large crashes. The paper presents results of first experiments in ASDEX...... Upgrade for destabilization of fast particle stabilized sawteeth with electron cyclotron current drive (ECCD). It is shown that moderate ECCD from a single gyrotron is able to destabilize the fast particle stabilized sawteeth. A reduction in sawtooth period by about 40% was achieved in first experiments...

  20. Effect of Alfvén resonance on low-frequency fast wave current drive

    Science.gov (United States)

    Wang, C. Y.; Batchelor, D. B.; Carter, M. D.; Jaeger, E. F.; Stallings, D. C.

    1995-08-01

    The Alfvén resonances may occur on the low- and high-field sides for a low-frequency fast wave current drive scenario proposed for the International Thermonuclear Experimental Reactor (ITER) [Nucl. Fusion 31, 1135 (1991)]. At the resonance on the low-field side, the fast wave may be mode converted into a short-wavelength slow wave, which can be absorbed by electrons at the plasma edge, before the fast wave propagates into the core area of the plasma. Such absorption may cause a significant parasitic power loss.

  1. Effect of Alfven resonance on low-frequency fast wave current drive

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.Y.; Batchelor, D.B.; Carter, M.D.; Jaeger, E.F.; Stallings, D.C. [Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    1995-07-01

    The Alfven resonances may occur on the low- and high-field sides for a low-frequency fast wave current drive scenario proposed for the International Thermonuclear Experimental Reactor (ITER) [Nucl. Fusion {bold 31}, 1135 (1991)]. At the resonance on the low-field side, the fast wave may be mode converted into a short-wavelength slow wave, which can be absorbed by electrons at the plasma edge, before the fast wave propagates into the core area of the plasma. Such absorption may cause a significant parasitic power loss. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  2. Effects of electron cyclotron current drive on the evolution of double tearing mode

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Guanglan, E-mail: sunguanglan@nciae.edu.cn; Dong, Chunying [Basic Science Section, North China Institute of Aerospace Engineering, Langfang 065000 (China); Duan, Longfang [School of Computer and Remote Sensing Information Technology, North China Institute of Aerospace Engineering, Langfang 065000 (China)

    2015-09-15

    The effects of electron cyclotron current drive (ECCD) on the double tearing mode (DTM) in slab geometry are investigated by using two-dimensional compressible magnetohydrodynamics equations. It is found that, mainly, the double tearing mode is suppressed by the emergence of the secondary island, due to the deposition of driven current on the X-point of magnetic island at one rational surface, which forms a new non-complete symmetric magnetic topology structure (defined as a non-complete symmetric structure, NSS). The effects of driven current with different parameters (magnitude, initial time of deposition, duration time, and location of deposition) on the evolution of DTM are analyzed elaborately. The optimal magnitude or optimal deposition duration of driven current is the one which makes the duration of NSS the longest, which depends on the mutual effect between ECCD and the background plasma. Moreover, driven current introduced at the early Sweet-Parker phase has the best suppression effect; and the optimal moment also exists, depending on the duration of the NSS. Finally, the effects varied by the driven current disposition location are studied. It is verified that the favorable location of driven current is the X-point which is completely different from the result of single tearing mode.

  3. The effect of the driving frequency on the confinement of beam electrons and plasma density in low pressure capacitive discharges

    CERN Document Server

    Wilczek, S; Schulze, J; Schuengel, E; Brinkmann, R P; Derzsi, A; Korolov, I; Donkó, Z; Mussenbrock, T

    2014-01-01

    The effect of changing the driving frequency on the plasma density and the electron dynamics in a capacitive radio-frequency argon plasma operated at low pressures of a few Pa is investigated by Particle in Cell/Monte Carlo Collisions simulations and analytical modeling. In contrast to previous assumptions the plasma density does not follow a quadratic dependence on the driving frequency in this non-local collisionless regime. Instead, a step-like increase at a distinct driving frequency is observed. Based on the analytical power balance model, in combination with a detailed analysis of the electron kinetics, the density jump is found to be caused by an electron heating mode transition from the classical $\\alpha$-mode into a low density resonant heating mode characterized by the generation of two energetic electron beams at each electrode per sheath expansion phase. These electron beams propagate through the bulk without collisions and interact with the opposing sheath. In the low density mode, the second bea...

  4. Cone beam CT in orthodontics: the current picture.

    Science.gov (United States)

    Makdissi, Jimmy

    2013-03-01

    The introduction of cone beam computed tomography (CBCT) technology to dentistry and orthodontics revolutionized the diagnosis, treatment and monitoring of orthodontic patients. This review article discusses the use of CBCT in diagnosis and treatment planning in orthodontics. The steps required to install and operate a CBCT facility within the orthodontic practice as well as the challenges are highlighted. The available guidelines in relation to the clinical applications of CBCT in orthodontics are explored.

  5. SOL plasma measurements during high density and long duration current drive on TRIAM-1M

    Energy Technology Data Exchange (ETDEWEB)

    Takemura, Takeharu; Kawasaki, Shoji; Jotaki, Eriko; Makino, Ken-ichi; Sakamoto, Mizuki; Nakamura, Kazuo; Nakamura, Yukio; Itoh, Sanae; Itoh, Satoshi [Kyushu Univ., Kasuga, Fukuoka (Japan). Research Inst. for Applied Mechanics

    1997-02-01

    In the superconducting, strong magnetic field tokamak, TRIAM-1M, for the purpose of maintaining high density plasma for long time, the current drive experiment using 8.2 GHz lower hybrid wave has been carried out. For maintaining high density plasma for long time, it is indispensable to control gas puff and recycling from wall, as these are closely related to the structure and characteristics of boundary plasma including scrape-off layer (SOL). In this study, in the high density, long time current drive using 8.2 GHz lower hybrid wave, the electron density and electron temperature of SOL plasma were measured by using double probe, and the z-direction distribution and the toroidal magnetic field dependence of the electron density and electron temperature of SOL plasma were examined and compared with OH discharge. Also the dependence of the electron density of SOL plasma on the phase difference in a adjoining waveguide tubes was examined. The experimental setup and the double probe theory are explained. The experimental results of the change with time lapse, the z-direction distribution and the magnetic field dependence of the electron density and electron temperature of SOL plasma are reported. (K.I.)

  6. Ion cyclotron and lower hybrid arrays applicable to current drive in fusion reactors

    Science.gov (United States)

    Bosia, G.; Helou, W.; Goniche, M.; Hillaret, J.; Ragona, R.

    2014-02-01

    This paper presents concepts for Ion Cyclotron and Lower Hybrid Current Drive arrays applicable to fusion reactors and based on periodically loaded line power division. It is shown that, in large arrays, such as the ones proposed for fusion reactor applications, these schemes can offer, in principle, a number of practical advantages, compared with currently adopted ones, such as in-blanket operation at significantly reduced power density, lay out suitable for water cooling, single ended or balanced power feed, simple and load independent impedance matching In addition, a remote and accurate real time measurement of the complex impedance of all array elements as well as detection, location, and measurement of the complex admittance of a single arc occurring anywhere in the structure is possible.

  7. Ohmic Radio-Frequency Synergy Current Drive and Transformer Recharging Experiments in the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhong-Yong; WAN Bao-Nian; SHI Yue-Jiang; HU Li-Qun; XU Han-Dong

    2005-01-01

    @@ Lower hybrid current drive (LHCD) experiments for investigating the interaction between lower hybrid (LH) wave and residual dc electric field were performed in extensive plasma parameter ranges in the HT-7 superconducting tokamak. The experimental results are well fitted to the Karney-Fisch theory on the efficiency of LH waves energy converted to poloidal magnetic field energy. The fraction of absorbed LH power is about 0.75 for the HT-7 machine, and the upshift of the LH-wave parallel refraction index during LHCD experiments have been derived by the optimizing fitting parameters. The LH wave is also used for the transformer recharging when the plasma current is maintained unchanged. The highest efficiency about 7% has been achieved in HT-7 machine.

  8. Capabilities of the ITER Electron Cyclotron Equatorial Launcher for Heating and Current Drive

    Directory of Open Access Journals (Sweden)

    Ramponi G.

    2012-09-01

    Full Text Available The ITER Electron Cyclotron Equatorial Launcher is designed to be one of the heating systems to assist and sustain the development of various ITER plasma scenarios starting with the very first plasma operation. Here the capabilities for Heating and Current Drive of this system are reviewed. In particular, the optimum launching conditions are investigated for two scenarios at burn, comparing toroidal and poloidal steering options. Then, the EC capabilities are investigated for different plasma parameters corresponding to various phases of the ITER plasma discharge, from current ramp-up up to burn, and for a wide range of magnetic field, focusing in particular on the EC potential for heating and for L to H-mode assist. It is found that the EC system can contribute to a wide range of heating scenarios during the ramp-up of the magnetic field, significantly increasing the applicable range as a function of magnetic field.

  9. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    CERN Document Server

    Yu, Deyang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei; Li, Xin

    2015-01-01

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking the advantages of high electric potential and narrow bandwidth in DC energetic charged beam measurements, current resolution better than 5 fA can be achieved. Two 128-channel Faraday cup arrays are built, and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O3+ ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

  10. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Deyang, E-mail: d.yu@impcas.ac.cn; Liu, Junliang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Xin [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2015-11-15

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O{sup 3+} ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

  11. Controlling fluctuations and transport in the reversed field pinch with edge current drive and plasma biasing

    Energy Technology Data Exchange (ETDEWEB)

    Craig, D.J.G.

    1998-09-01

    Two techniques are employed in the Madison Symmetric Torus (MST) to test and control different aspects of fluctuation induced transport in the Reversed Field Pinch (RFP). Auxiliary edge currents are driven along the magnetic field to modify magnetic fluctuations, and the particle and energy transport associated with them. In addition, strong edge flows are produced by plasma biasing. Their effect on electrostatic fluctuations and the associated particle losses is studied. Both techniques are accomplished using miniature insertable plasma sources that are biased negatively to inject electrons. This type of emissive electrode is shown to reliably produce intense, directional current without significant contamination by impurities. The two most important conclusions derived from these studies are that the collective modes resonant at the reversal surface play a role in global plasma confinement, and that these modes can be controlled by modifying the parallel current profile outside of the reversal surface. This confirms predictions based on magnetohydrodynamic (MHD) simulations that auxiliary current drive in the sense to flatten the parallel current profile can be successful in controlling magnetic fluctuations in the RFP. However, these studies expand the group of magnetic modes believed to cause transport in MST and suggest that current profile control efforts need to address both the core resonant magnetic modes and those resonant at the reversal surface. The core resonant modes are not significantly altered in these experiments; however, the distribution and/or amplitude of the injected current is probably not optimal for affecting these modes. Plasma biasing generates strong edge flows with shear and particle confinement likely improves in these discharges. These experiments resemble biased H modes in other magnetic configurations in many ways. The similarities are likely due to the common role of electrostatic fluctuations in edge transport.

  12. A DSP-Based Beam Current Monitoring System for Machine Protection Using Adaptive Filtering

    Energy Technology Data Exchange (ETDEWEB)

    J. Musson; H. Dong; R. Flood; C. Hovater; J. Hereford

    2001-06-01

    The CEBAF accelerator at Jefferson Lab is currently using an analog beam current monitoring (BCM) system for its machine protection system (MPS), which has a loss accuracy of 2 micro-amps. Recent burn-through simulations predict catastrophic beam line component failures below 1 micro-amp of loss, resulting in a blind spot for the MPS. Revised MPS requirements target an ultimate beam loss accuracy of 250 nA. A new beam current monitoring system has been developed which utilizes modern digital receiver technology and digital signal processing concepts. The receiver employs a direct-digital down converter integrated circuit, mated with a Jefferson Lab digital signal processor VME card. Adaptive filtering is used to take advantage of current-dependent burn-through rates. Benefits of such a system include elimination of DC offsets, generic algorithm development, extensive filter options, and interfaces to UNIX-based control systems.

  13. Electromagnetic and beam dynamics studies of a high current drift tube linac for LEHIPA

    Science.gov (United States)

    Roy, S.; Rao, S. V. L. S.; Pande, R.; Krishnagopal, S.; Singh, P.

    2014-06-01

    We have performed detailed electromagnetic and beam dynamics studies of a 352.21 MHz drift-tube linac (DTL) that will accelerate a 30 mA CW proton beam from 3 to 20 MeV. At such high currents space charge effects are important, and therefore the effect of linear as well as non-linear space charge has been studied (corresponding to uniform and Gaussian initial beam distributions), in order to avoid space charge instabilities. To validate the electromagnetic simulations, a 1.2 m long prototype of the DTL was fabricated. RF measurements performed on the prototype were in good agreement with the simulations. A detailed simulation study of beam halos was also performed, which showed that beyond a current of 10 mA, significant longitudinal beam halos are excited even for a perfectly matched beam, whereas for a mis-matched beam transverse beam halos are also excited. However, these do not lead to any beam loss within the DTL.

  14. DEVELOPMENT OF ACCELERATOR DATA REPORTING SYSTEM AND ITS APPLICATION TO TREND ANALYSIS OF BEAM CURRENT DATA

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, M.J.; Blokland, W.

    2009-01-01

    Detailed ongoing information about the ion beam quality is crucial to the successful operation of the Spallation Neutron Source at Oak Ridge National Laboratory. In order to provide the highest possible neutron production time, ion beam quality is monitored to isolate possible problems or performance-related issues throughout the accelerator and accumulator ring. For example, beam current monitor (BCM) data is used to determine the quality of the beam transport through the accelerator. In this study, a reporting system infrastructure was implemented and used to generate a trend analysis report of the BCM data. The BCM data was analyzed to facilitate the identifi cation of monitor calibration issues, beam trends, beam abnormalities, beam deviations and overall beam quality. A comparison between transformed BCM report data and accelerator log entries shows promising results which represent correlations between the data and changes made within the accelerator. The BCM analysis report is one of many reports within a system that assist in providing overall beam quality information to facilitate successful beam operation. In future reports, additional data manipulation functions and analysis can be implemented and applied. Built-in and user-defi ned analytic functions are available throughout the reporting system and can be reused with new data.

  15. Simulation of Electron Beam Dynamics in a Nonmagnetized High-Current Vacuum Diode

    CERN Document Server

    Anishchenko, Sergey

    2016-01-01

    The electron beam dynamics in a nonmagnetized high-current vacuum diode is analyzed for different cathode-anode gap geometries. The conditions enabling to achieve the minimal {initial} momentum spread in the electron beam are found out. A drastic rise of current density in a vacuum diode with a ring-type cathode is described. The effect is shown to be caused by electrostatic repulsion.

  16. Fast range switching of passively scattered proton beams using a modulation wheel and dynamic beam current modulation.

    Science.gov (United States)

    Sánchez-Parcerisa, D; Pourbaix, J C; Ainsley, C G; Dolney, D; Carabe, A

    2014-04-01

    In proton radiotherapy, the range of particles in the patient body is determined by the energy of the protons. For most systems, the energy selection time is on the order of a few seconds, which becomes a serious obstacle for continuous dose delivery techniques requiring adaptive range modulation. This work analyses the feasibility of using the range modulation wheel, an element in the beamline used to form the spread-out Bragg peak (SOBP), to produce near-instantaneous changes not only in the modulation, but also in the range of the beam. While delivering proton beams in double scattering mode, the beam current can be synchronized with the range modulation wheel rotation by defining a current modulation pattern. Different current modulation patterns were computed from Monte Carlo simulations of our double scattering nozzle to range shift an SOBP of initial range 15 cm by varying degrees of up to ∼9 cm. These patterns were passed to the treatment control system at our institution and the resulting measured depth-dose distributions were analysed in terms of flatness, distal penumbra and relative irradiation time per unit mid-SOBP dose. Suitable SOBPs were obtained in all cases, with the maximum range shift being limited only by the maximum thickness of the wheel. The distal dose fall-off (80% to 20%) of the shifted peaks was broadened to about 1 cm, from the original 0.5 cm, and the predicted overhead in delivery time showed a linear increase with the amount of the shift. By modulating the beam current in clinical scattered proton beams equipped with a modulation wheel, it is possible to dynamically modify the in-patient range of the SOBP without adding any specific hardware or compensators to the beamline. A compromise between sharper distal dose fall-off and lower delivery time can be achieved and is subject to optimization.

  17. Nano-electron beam induced current and hole charge dynamics through uncapped Ge nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Marchand, A.; El Hdiy, A.; Troyon, M. [Laboratoire de Recherche en Nanosciences, Bat. 6, case no 15, UFR Sciences, Universite de Reims Champagne Ardenne, 51687 Reims Cedex 2 (France); Amiard, G.; Ronda, A.; Berbezier, I. [IM2NP, Faculte des Sciences et Techniques, Campus de Saint Jerome - Case 142, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20 (France)

    2012-04-16

    Dynamics of hole storage in spherical Ge nanocrystals (NCs) formed by a two step dewetting/nucleation process on an oxide layer grown on an n-doped <001> silicon substrate is studied using a nano-electron beam induced current technique. Carrier generation is produced by an electron beam irradiation. The generated current is collected by an atomic force microscope--tip in contact mode at a fixed position away from the beam spot of about 0.5 {mu}m. This distance represents the effective diffusion length of holes. The time constants of holes charging are determined and the effect of the NC size is underlined.

  18. Electron Cyclotron Current Drive at High Electron Temperature on DIII-D

    Science.gov (United States)

    Petty, C. C.; Austin, M. E.; Harvey, R. W.; Lohr, J.; Luce, T. C.; Makowski, M. A.; Prater, R.

    2007-09-01

    Experiments on DIII-D have measured the electron cyclotron current drive (ECCD) efficiency for co- and counter-injection in low density plasmas with radiation temperatures from electron cyclotron emission (ECE) above 20 keV. The radiation temperature is generally higher than the Thomson scattering temperature, indicating that there is a significant population of non-thermal electrons. The experimental ECCD profile measured with motional Stark effect (MSE) polarimetry is found to agree with quasi-linear theory except for the highest power density cases (QEC/ne2≫1). Radial transport of the energetic electrons with diffusion coefficients of ˜0.4 m2/s is needed to model the broadened ECCD profile at high power density.

  19. A Study on New Current Controller for 7-Phase BLDC Motor Drive System

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Surk; Jeon, Ywun Seok; Mok, Hyung Soo [Konkuk University (Korea); Kim, Duk Keun [Komotek Co., Ltd. (Korea)

    2001-04-01

    Recently, the demand of motor for industrial, household machinery is increasing. As Switching devices and control technology are progressing, so the use of BLDC Motor is increasing. But 3-phase BLCD Motor generally used has pulsating torque and speed variation in commutation, so the range of its application is limited to high speed operation. Especially, to solve these problems, it is necessary to increase phase of Motor, so study of Poly-Phase BLDC Motor is progressing. However, when hysteresis current controller is used, switching frequency is highly increasing. In this paper, 7-Phase BLDC Motor drive system is designed. Also MSTC (Minimum Switching Time Controller) is proposed and with simulation and experiment, their validities are verified. (author). 10 refs., 26 figs., 1 tab.

  20. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    Science.gov (United States)

    Milanesio, D.; Maggiora, R.

    2015-12-01

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  1. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    Energy Technology Data Exchange (ETDEWEB)

    Milanesio, D., E-mail: daniele.milanesio@polito.it; Maggiora, R. [Politecnico di Torino, Dipartimento di Elettronica e Telecomunicazioni (DET), Torino (Italy)

    2015-12-10

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  2. Return-current formation in the electron beam – plasma system

    Directory of Open Access Journals (Sweden)

    M. Bárta

    2009-07-01

    Full Text Available Using a 3-D electromagnetic particle-in-cell model an evolution of the electron distribution function in the beam-plasma system with the return current is computed. It was found that the resulting electron distribution function depends on the magnetic field assumed along the beam-propagation direction. While for small magnetic fields the electron distribution function becomes broad in the direction perpendicular to the beam propagation due to the Weibel (filamentation instability and the return current is formed by a shifted bulk distribution, for stronger magnetic fields the distribution, especially on the return current side, is extended in the beam-propagation direction. To understand better the instabilities influencing the mentioned processes, the dispersion diagrams are computed and discussed.

  3. Principal physics of rotating magnetic-field current drive of field reversed configurations

    Science.gov (United States)

    Hoffman, A. L.; Guo, H. Y.; Miller, K. E.; Milroy, R. D.

    2006-01-01

    After extensive experimentation on the Translation, Confinement, and Sustainment rotating magnetic-field (RMF)-driven field reversed configuration (FRC) device [A. L. Hoffman et al., Fusion Sci. Technol. 41, 92 (2002)], the principal physics of RMF formation and sustainment of standard prolate FRCs inside a flux conserver is reasonably well understood. If the RMF magnitude Bω at a given frequency ω is high enough compared to other experimental parameters, it will drive the outer electrons of a plasma column into near synchronous rotation, allowing the RMF to penetrate into the plasma. If the resultant azimuthal current is strong enough to reverse an initial axial bias field Bo a FRC will be formed. A balance between the RMF applied torque and electron-ion friction will determine the peak plasma density nm∝Bω/η1/2ω1/2rs, where rs is the FRC separatrix radius and η is an effective weighted plasma resistivity. The plasma total temperature Tt is free to be any value allowed by power balance as long as the ratio of FRC diamagnetic current, I'dia≈2Be/μo, is less than the maximum possible synchronous current, I'sync=⟨ne⟩eωrs2/2. The RMF will self-consistently penetrate a distance δ* governed by the ratio ζ =I'dia/I'sync. Since the FRC is a diamagnetic entity, its peak pressure pm=nmkTt determines its external magnetic field Be≈(2μopm)1/2. Higher FRC currents, magnetic fields, and poloidal fluxes can thus be obtained, with the same RMF parameters, simply by raising the plasma temperature. Higher temperatures have also been noted to reduce the effective plasma resistivity, so that these higher currents can be supported with surprisingly little increase in absorbed RMF power.

  4. Fault diagnosis of motor drives using stator current signal analysis based on dynamic time warping

    Science.gov (United States)

    Zhen, D.; Wang, T.; Gu, F.; Ball, A. D.

    2013-01-01

    Electrical motor stator current signals have been widely used to monitor the condition of induction machines and their downstream mechanical equipment. The key technique used for current signal analysis is based on Fourier transform (FT) to extract weak fault sideband components from signals predominated with supply frequency component and its higher order harmonics. However, the FT based method has limitations such as spectral leakage and aliasing, leading to significant errors in estimating the sideband components. Therefore, this paper presents the use of dynamic time warping (DTW) to process the motor current signals for detecting and quantifying common faults in a downstream two-stage reciprocating compressor. DTW is a time domain based method and its algorithm is simple and easy to be embedded into real-time devices. In this study DTW is used to suppress the supply frequency component and highlight the sideband components based on the introduction of a reference signal which has the same frequency component as that of the supply power. Moreover, a sliding window is designed to process the raw signal using DTW frame by frame for effective calculation. Based on the proposed method, the stator current signals measured from the compressor induced with different common faults and under different loads are analysed for fault diagnosis. Results show that DTW based on residual signal analysis through the introduction of a reference signal allows the supply components to be suppressed well so that the fault related sideband components are highlighted for obtaining accurate fault detection and diagnosis results. In particular, the root mean square (RMS) values of the residual signal can indicate the differences between the healthy case and different faults under varying discharge pressures. It provides an effective and easy approach to the analysis of motor current signals for better fault diagnosis of the downstream mechanical equipment of motor drives in the time

  5. Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas.

    Science.gov (United States)

    Bright, A N; Yoshida, K; Tanaka, N

    2013-01-01

    Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar.

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

    CERN Document Server

    Gräwer, G

    2004-01-01

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

  7. MSE measurements for sawtooth and non-inductive current drive studies in KSTAR

    Science.gov (United States)

    Ko, J.; Park, H.; Bea, Y. S.; Chung, J.; Jeon, Y. M.

    2016-10-01

    Two major topics where the measurement of the magnetic-field-line rotational transform profiles in toroidal plasma systems include the long-standing issue of complete versus incomplete reconnection model of the sawtooth instability and the issue with future reactor-relevant tokamak devices in which non-inductive steady state current sustainment is essential. The motional Stark effect (MSE) diagnostic based on the photoelastic-modulator (PEM) approach is one of the most reliable means to measure the internal magnetic pitch, and thus the rotational transform, or its reciprocal (q), profiles. The MSE system has been commissioned for the Korea Superconducting Tokamak Advanced Research (KSTAR) along with the development of various techniques to minimize systematic offset errors such as Faraday rotation and mis-alignment of the bandpass filters. The diagnostic has revealed the central q is well correlated with the sawtooth oscillation, maintaining its value above unity during the MHD quiescent period and that the response of the q profile to external current drive such as electron cyclotron wave injection not only involves the local change of the pitch angle gradient but also a significant shift of the magnetic topology due to the wave energy transport. Work supported by the Ministry of Science, ICT and Future Planning, Korea.

  8. Integrated Plasma Simulation of Lower Hybrid Current Drive Modification of Sawtooth in Alcator C-Mod

    Science.gov (United States)

    Bonoli, P. T.; Hubbard, A. E.; Schmidt, A. E.; Wright, J. C.; Kessel, C. E.; Batchelor, D. B.; Berry, L. A.; Harvey, R. W.

    2010-11-01

    Experiments were performed in Alcator C-Mod, where the onset time for sawteeth was delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through injection of off-axis LH current drive power [1]. In this poster we discuss simulations of these experiments using the Integrated Plasma Simulator (IPS) [2], through which driven current density profiles and hard x-ray spectra are computed using a ray tracing code (GENRAY) and Fokker Planck code (CQL3D) [3], that are executed repeatedly in time. The background plasma is evolved in these simulations using the TSC transport code with the Porcelli sawtooth model [4]. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Mtg. on Sim. and Mod. of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, Journal Comp. Phys. 66, 481 (1986).

  9. Segmented Beam Dump for Time Resolved Spectrometry on a High Current Electron Beam

    CERN Document Server

    Lefèvre, T; Bravin, E; Braun, H H

    2008-01-01

    In the CLIC Test Facility 3 (CTF3), the strong coupling between the beam and the accelerating cavities induces transient effects such that the head of the pulse is accelerated twice as much as the rest of the pulse. Three spectrometer lines are installed along the linac with the aim of measuring energy spread versus time with a 20ns resolution. A major difficulty is due to the high power carried by the beam which imposes extreme constraints of thermal and radiation resistances on the detector. This paper presents the design and the performances of a simple and easy-to-maintain device, called ‘segmented dump'. In this device, the particles are stopped inside metallic plates and the deposited charge is measured in the same way as in Faraday cups. Simulations were carried out with the Monte Carlo code ‘FLUKA' to evaluate the problems arising from the energy deposition and to find ways to prevent or reduce them. The detector resolution was optimized by an adequate choice of material and thickness of the...

  10. A Wave-Based Model for Cross-Beam Energy Transfer in Direct-Drive Inertial Confinement Fusion Implosions

    Science.gov (United States)

    Myatt, J. F.

    2016-10-01

    Cross-beam energy transfer (CBET) is thought to be responsible for an 30 % reduction in hydrodynamic coupling efficiency on OMEGA and up to 50% at the ignition scale for direct-drive (DD) implosions. These numbers are determined by ray-based models that have been developed and integrated within the radiation-hydrodynamics codes LILAC (1-D) and DRACO (2-D). However, ray-based modeling of CBET in an inhomogeneous plasma assumes a steady-state plasma response, does not include the effects of beam speckle, and ray caustics are treated in an ad hoc manner. Nevertheless, simulation results are in good qualitative agreement with implosion experiments on OMEGA (when combined with a model for nonlocal heat transport). The validity of the modeling for ignition-scale implosions has not yet been determined. To address the physics shortcomings, which have important implications for DD inertial confinement fusion, a new wave-based model has been constructed. It solves the time-enveloped Maxwell equations in three-dimensions, including polarization effects, plasma inhomogeneity, and open-boundary conditions with the ability to prescribe beams incident at arbitrary angles. Beams can be made realistic with respect to laser speckle, polarization smoothing, and laser bandwidth. This, coupled to a linearized low-frequency plasma response that does not assume a steady state, represents the most-complete model of CBET to date. New results will be presented and the implications for CBET modeling and mitigation will be described. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DENA0001944, in collaboration with J. G. Shaw, R. K. Follett, and D. H. Edgell (LLE).

  11. Design and simulation of a beam position monitor for the high current proton linac

    Institute of Scientific and Technical Information of China (English)

    RUAN Yu-Fang; XU Tao-Guang; FU Shi-Nian

    2009-01-01

    In this paper, the 2-D electrostatic field software, POISSON, is used to calculate the characteristic impedance of a BPM (beam position monitor) for a high current proton linac. Furthermore, the time-domain 3-D module of MAFIA with a beam microbunch at a varying offset from the axis is used to compute the induced voltage on the electrodes as a function of time. Finally, the effect of low 13 beams on the induced voltage, the sensitivity and the signal dynamic range of the BPM are discussed.

  12. Leakage Current Simulation of Insulating Thin Film Irradiated by a Nonpenetrating Electron Beam

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-Bo; LI Wei-Qin; CAO Meng

    2012-01-01

    We perform numerical simulations of the leakage current characteristics of an insulating thin film of SiO2 negatively charged by a low-energy nonpenetrating focused electron beam. For the formation of leakage current, electrons are demonstrated to turn from diffusion to drift after clearing the minimum potential barrier due to electron-hole separation. In the equilibrium state, the leakage current increases approximately linearly with the increasing primary beam current and energy. It also increases with the increasing film thickness and trap density, and with the decreasing electron mobility, in which the film thickness has a greater influence. Validated by some existing experiments, the simulation results provide a new perspective for the negative charging effects of insulating samples due to the low-energy focused electron beam.%We perform numerical simulations of the leakage current characteristics of an insulating thin film of SiO2 negatively charged by a low-energy nonpenetrating focused electron beam.For the formation of leakage current,electrons are demonstrated to turn from diffusion to drift after clearing the minimum potential barrier due to electron-hole separation.In the equilibrium state,the leakage current increases approximately linearly with the increasing primary beam current and energy.It also increases with the increasing film thickness and trap density,and with the decreasing electron mobility,in which the film thickness has a greater influence.Validated by some existing experiments,the simulation results provide a new perspective for the negative charging effects of insulating samples due to the low-energy focused electron beam.

  13. Impurity heterogeneity in natural pyrite and its relation to internal electric fields mapped using remote laser beam induced current

    Energy Technology Data Exchange (ETDEWEB)

    Laird, Jamie S., E-mail: csirojamie@gmail.com [CSIRO, Earth Science and Resource Engineering, Clayton, Victoria (Australia); Centre of Excellence in Ore Deposits (CODES), University of Tasmania, Hobart, Tasmania (Australia); School of Physics, University of Melbourne, Parkville 3010, Victoria (Australia); Large, Ross [Centre of Excellence in Ore Deposits (CODES), University of Tasmania, Hobart, Tasmania (Australia); Ryan, Chris G. [CSIRO, Earth Science and Resource Engineering, Clayton, Victoria (Australia); Centre of Excellence in Ore Deposits (CODES), University of Tasmania, Hobart, Tasmania (Australia); School of Physics, University of Melbourne, Parkville 3010, Victoria (Australia)

    2013-07-01

    Regions of band-bending in naturally occurring semiconducting sulfides are thought to drive electrochemical reactions with passing fluids. Metal bearing fluids within the right pH range interact with the electric fields at the surface resulting in precious metal ore genesis, even in under-saturated solutions. Metal reduction at the surface occurs via field assisted electron transfer from the semiconductor bulk to the ion in solution via surface states. Better understanding the role these regions and their texturing play on nucleating ore growth requires imaging of electric field distributions near the sulfide surface and correlation with underlying elemental heterogeneity. In this paper we discuss PIXE measurements made on the CSIRO Nuclear Microprobe and correlate elemental maps with laser beam induced current maps of the electric field distribution.

  14. Positron source investigation by using CLIC drive beam for Linac-LHC based e{sup +}p collider

    Energy Technology Data Exchange (ETDEWEB)

    Arikan, Ertan [Department of Physics, Faculty of Art and Sciences, Nigde University, Nigde (Turkey); Aksakal, Huesnue, E-mail: aksakal@cern.ch [Department of Physics, Faculty of Art and Sciences, Nigde University, Nigde (Turkey)

    2012-08-11

    Three different methods which are alternately conventional, Compton backscattering and Undulator based methods employed for the production of positrons. The positrons to be used for e{sup +}p collisions in a Linac-LHC (Large Hadron Collider) based collider have been studied. The number of produced positrons as a function of drive beam energy and optimum target thickness has been determined. Three different targets have been used as a source investigation which are W{sub 75}-Ir{sub 25}, W{sub 75}-Ta{sub 25}, and W{sub 75}-Re{sub 25} for three methods. Estimated number of the positrons has been performed with FLUKA simulation code. Then, these produced positrons are used for following Adiabatic matching device (AMD) and capture efficiency is determined. Then e{sup +}p collider luminosity corresponding to the methods mentioned above have been calculated by CAIN code.

  15. A camera for imaging hard x-rays from suprathermal electrons during lower hybrid current drive on PBX-M

    Energy Technology Data Exchange (ETDEWEB)

    von Goeler, S.; Kaita, R.; Bernabei, S.; Davis, W.; Fishman, H.; Gettelfinger, G.; Ignat, D.; Roney, P.; Stevens, J.; Stodiek, W. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Jones, S.; Paoletti, F. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center); Petravich, G. (Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Physics); Rimini,

    1993-05-01

    During lower hybrid current drive (LHCD), suprathermal electrons are generated that emit hard X-ray bremsstrahlung. A pinhole camera has been installed on the PBX-M tokamak that records 128 [times] 128 pixel images of the bremsstrahlung with a 3 ms time resolution. This camera has identified hollow radiation profiles on PBX-M, indicating off-axis current drive. The detector is a 9in. dia. intensifier. A detailed account of the construction of the Hard X-ray Camera, its operation, and its performance is given.

  16. Extended magnetohydrodynamic simulations of field reversed configuration formation and sustainment with rotating magnetic field current drive

    Science.gov (United States)

    Milroy, R. D.; Kim, C. C.; Sovinec, C. R.

    2010-06-01

    Three-dimensional simulations of field reversed configuration (FRC) formation and sustainment with rotating magnetic field (RMF) current drive have been performed with the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. The Hall term is a zeroth order effect with strong coupling between Fourier components, and recent enhancements to the NIMROD preconditioner allow much larger time steps than was previously possible. Boundary conditions to capture the effects of a finite length RMF antenna have been added, and simulations of FRC formation from a uniform background plasma have been performed with parameters relevant to the translation, confinement, and sustainment-upgrade experiment at the University of Washington [H. Y. Guo, A. L. Hoffman, and R. D. Milroy, Phys. Plasmas 14, 112502 (2007)]. The effects of both even-parity and odd-parity antennas have been investigated, and there is no evidence of a disruptive instability for either antenna type. It has been found that RMF effects extend considerably beyond the ends of the antenna, and that a large n =0 Bθ can develop in the open-field line region, producing a back torque opposing the RMF.

  17. Proposed high voltage power supply for the ITER relevant lower hybrid current drive system

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, P.K., E-mail: pramod@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat (India); Kazarian, F.; Garibaldi, P.; Gassman, T. [ITER Organization, CS 90 046, 13067 Saint-Paul-Les-Durance (France); Artaud, J.F. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Bae, Y.S. [National Fusion Research Institute, Daejeon (Korea, Republic of); Belo, J. [Associacao Euratom-IST, Centro de Fusao Nuclear, Lisboa (Portugal); Berger-By, G.; Bernard, J.M.; Cara, Ph. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Cesario, R. [Associazione Euratom-ENEA sulla Fusione, CR Frascati, Rome (Italy); Decker, J.; Delpech, L.; Ekedahl, A.; Garcia, J.; Goniche, M.; Guilhem, D. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

    2011-10-15

    In the framework of the EFDA task HCD-08-03-01, the ITER lower hybrid current drive (LHCD) system design has been reviewed. The system aims to generate 24 MW of RF power at 5 GHz, of which 20 MW would be coupled to the plasmas. The present state of the art does not allow envisaging a unitary output of the klystrons exceeding 500 kW, so the project is based on 48 klystron units, leaving some margin when the transmission lines losses are taken into account. A high voltage power supply (HVPS), required to operate the klystrons, is proposed. A single HVPS would be used to feed and operate four klystrons in parallel configuration. Based on the above considerations, it is proposed to design and develop twelve HVPS, based on pulse step modulator (PSM) technology, each rated for 90 kV/90 A. This paper describes in details, the typical electrical requirements and the conceptual design of the proposed HVPS for the ITER LHCD system.

  18. High Power Antenna Design for Lower Hybrid Current Drive in MST

    Science.gov (United States)

    Thomas, M. A.; Goetz, J. A.; Kaufman, M. C.; Oliva, S. P.; Caughman, J. B. O.; Ryan, P. M.

    2003-10-01

    RF current drive has been proposed as a method for reducing the tearing fluctuations that are responsible for anomalous energy transport in the RFP. A system for launching lower hybrid slow waves at 800 MHz and n_||= 7.5 is now in operation at up to 50 kW on MST. The antenna is an enclosed interdigital line using λ/4 resonators with an opening in the cavity through which the wave is coupled to the plasma. It has an untuned VSWR of ˜2, and is instrumented on 5 of its 23 elements to allow measurement of damping length. The antenna design is being optimized for higher power handling. Improvements include larger vacuum feedthroughs, better impedance matching, and RF instrumentation on all resonators. The new antenna will be modeled in Microwave Studio^TM. The goal is a design which can handle ˜250 kW and presents a VSWR of 1.4 or better without external tuning. Full instrumentation will allow more detailed power deposition measurements.

  19. Detection and sizing of defects in control rod drive mechanism penetrations using eddy current and ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Light, G.M.; Fisher, J.L.; Tennis, R.F.; Stolte, J.S.; Hendrix, G.J. [Southwest Research Inst., San Antonio, TX (United States)

    1996-08-01

    Over the last two years, concern has been generated about the capabilities of performing nondestructive evaluation (NDE) of the closure-head penetrations in nuclear-reactor pressure vessels. These penetrations are primarily for instrumentation and control rod drive mechanisms (CRDMs) and are usually thick-walled Inconel tubes, which are shrink-fitted into the steel closure head. The penetrations are then welded between the outside surface of the penetration and the inside surface of the closure head. Stress corrosion cracks initiating at the inner surface of the penetration have been reported at several plants. Through-wall cracks in the CRDM penetration or CRDM weld could lead to loss of coolant in the reactor vessel. The CRDM penetration presents a complex inspection geometry for conventional NDE techniques. A thermal sleeve, through which pass the mechanical linkages for operating the control rods, is inserted into the penetration in such a way that only a small annulus (nominally 3 mm) exists between the thermal sleeve and inside surface of the penetration. Ultrasonic (UT) and eddy current testing (ET) techniques that could be used to provide defect detection and sizing capability were investigated. This paper describes the ET and UT techniques, the probes developed, and the results obtained using these probes and techniques on CRDM penetration mock-ups.

  20. NTM stabilization by alternating O-point EC current drive using a high-power diplexer

    Science.gov (United States)

    Kasparek, W.; Doelman, N.; Stober, J.; Maraschek, M.; Zohm, H.; Monaco, F.; Eixenberger, H.; Klop, W.; Wagner, D.; Schubert, M.; Schütz, H.; Grünwald, G.; Plaum, B.; Munk, R.; Schlüter, K. H.; ASDEX Upgrade Team

    2016-12-01

    At the tokamak ASDEX Upgrade, experiments to stabilize neoclassical tearing modes (NTMs) by electron cyclotron (EC) heating and current drive in the O-points of the magnetic islands were performed. For the first time, injection into the O-points of the revolving islands was performed via a fast directional switch, which toggled the EC power between two launchers synchronously to the island rotation. The switching was performed by a resonant diplexer employing a sharp resonance in the transfer function, and a small frequency modulation of the feeding gyrotron around the slope of the resonance. Thus, toggling of the power between the two outputs of the diplexer connected to two articulating launchers was possible. Phasing and control of the modulation were performed via a set of Mirnov coils and appropriate signal processing. In the paper, technological issues, the design of the diplexer, the tracking of the diplexer resonance to the gyrotron frequency, the generation and processing of control signals for the gyrotron, and the typical performance concerning switching contrast and efficiency are discussed. The plasma scenario is described, and plasma experiments are presented, where the launchers scanned the region of the resonant surface continuously and also where the launchers were at a fixed position near to the q  =  1.5-surface. In the second case, complete stabilization of a 3/2 NTM could be reached. These experiments are also seen as a technical demonstration for the applicability of diplexers in large-scale ECRH systems.

  1. Quasi-linear modeling of lower hybrid current drive in ITER and DEMO

    Energy Technology Data Exchange (ETDEWEB)

    Cardinali, A., E-mail: alessandro.cardinali@enea.it; Cesario, R.; Panaccione, L.; Santini, F.; Amicucci, L.; Castaldo, C.; Ceccuzzi, S.; Mirizzi, F.; Tuccillo, A. A. [ENEA, Unità Tecnica Fusione, Via E Fermi 45 Rome (Italy)

    2015-12-10

    First pass absorption of the Lower Hybrid waves in thermonuclear devices like ITER and DEMO is modeled by coupling the ray tracing equations with the quasi-linear evolution of the electron distribution function in 2D velocity space. As usually assumed, the Lower Hybrid Current Drive is not effective in a plasma of a tokamak fusion reactor, owing to the accessibility condition which, depending on the density, restricts the parallel wavenumber to values greater than n{sub ∥crit} and, at the same time, to the high electron temperature that would enhance the wave absorption and then restricts the RF power deposition to the very periphery of the plasma column (near the separatrix). In this work, by extensively using the “ray{sup star}” code, a parametric study of the propagation and absorption of the LH wave as function of the coupled wave spectrum (as its width, and peak value), has been performed very accurately. Such a careful investigation aims at controlling the power deposition layer possibly in the external half radius of the plasma, thus providing a valuable aid to the solution of how to control the plasma current profile in a toroidal magnetic configuration, and how to help the suppression of MHD mode that can develop in the outer part of the plasma. This analysis is useful not only for exploring the possibility of profile control of a pulsed operation reactor as well as the tearing mode stabilization, but also in order to reconsider the feasibility of steady state regime for DEMO.

  2. High Dynamic Magnetic Beam Current Measurements by Means of Optimised Magneto-Resistance (MR) Sensor Engineering

    CERN Document Server

    Hape, M; Ricken, W

    2005-01-01

    The GSI-FAIR project (facility for antiprotons and ion research) will comprehend DC currents up to around 5 A in the SIS 100 synchrotron and after bunch compression down to 50 ns pulse length the peak currents will reach up to 100 A. To meet these higher demands of beam current measurements new sensor techniques are foreseen. The measurement device itself will be designed in form of a clip-on ampere-meter. The air gap of the flux concentrator is assumed to be around 5 mm and thus, the estimated maximum field therein is around 30 mT for a beam current of 100 A peak. The resolution of this device is aimed to be 1 mA in beam current, corresponding to a system dynamic of around 105. This high demands of beam current measurement require more sophisticated sensor types than just using a Hall probe. The characteristics of AMR (anisotropic magneto-resistance), GMR (giant magneto-resistance) and GMI (giant magneto-impedance) sensors like hysteresis, linearity and sensitivity have been measured within the magnetic fiel...

  3. Enhanced Phase-Shifted Current Control for Harmonic Cancellation in Three-Phase Multiple Adjustable Speed Drive Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Davari, Pooya; Zare, Firuz

    2017-01-01

    A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies on......-shifted current control is a cost-effective solution to multiple ASD systems in terms of harmonic cancellation.......A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies...... on the loading condition of each drive unit as well as the number of drives in parallel. In order to enhance the harmonic cancellation by means of the phase-shifted current control, the currents drawn by the rectifiers should be maintained almost at the same level. Thus, this paper firstly analyzes the impact...

  4. Aberrations due to solenoid focusing of a multiply charged high-current ion beam

    CERN Document Server

    Grégoire, G; Lisi, N; Schnuriger, J C; Scrivens, R; Tambini, J

    2000-01-01

    At the output of a laser ion source, a high current of highly charged ions with a large range of charge states is available. The focusing of such a beam by magnetic elements causes a nonlinear space-charge field to develop which can induce large aberrations and emittance growth in the beam. Simulation of the beam from the CERN laser ion source will be presented for an ideal magnetic and electrostatic system using a radially symmetric model. In addition, the three dimensional software KOBRA3 is used for the simulation of the solenoid line. The results of these simulations will be compared with experiments performed on the CERN laser ion source with solenoids (resulting in a hollow beam) and a series of gridded electrostatic lenses. (5 refs).

  5. Modulation of auroral electrojet currents using dual HF beams with ELF phase offset

    Science.gov (United States)

    Golkowski, M.; Cohen, M.; Moore, R. C.

    2012-12-01

    The modulation of naturally occuring ionospheric currents with high power radio waves in the high frequency (HF, 3-10 MHz) band is a well known technique for generation of extremely low frequency (ELF, 3-3000 Hz) and very low frequency (VLF, 3-30 kHz) waves. We use the heating facility of the High Frequency Active Auroral Research Program (HAARP) to investigate the effect of using dual HF beams with an ELF/VLF phase offset between the modulation waveforms. Experiments with offset HF beams confirm the model of independent ELF/VLF sources. Experiments with co-located HF beams exhibit interaction between the first and second harmonics of the modulated tones when square and sine wave modulation waveforms are employed. Using ELF/VLF phase offsets for co-loacted beams is also shown to be a potential diagnostic for the D-region ionospheric profile.

  6. A Particle In Cell code development for high current ion beam transport and plasma simulations

    CERN Document Server

    Joshi, N

    2016-01-01

    A simulation package employing a Particle in Cell (PIC) method is developed to study the high current beam transport and the dynamics of plasmas. This package includes subroutines those are suited for various planned projects at University of Frankfurt. In the framework of the storage ring project (F8SR) the code was written to describe the beam optics in toroidal magnetic fields. It is used to design an injection system for a ring with closed magnetic field lines. The generalized numerical model, in Cartesian coordinates is used to describe the intense ion beam transport through the chopper system in the low energy beam section of the FRANZ project. Especially for the chopper system, the Poisson equation is implemented with irregular geometries. The Particle In Cell model is further upgraded with a Monte Carlo Collision subroutine for simulation of plasma in the volume type ion source.

  7. A Four Channel Beam Current Monitor Data Acquisition System Using Embedded Processors

    Energy Technology Data Exchange (ETDEWEB)

    Wheat, Jr., Robert Mitchell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalmas, Dale A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-11

    Data acquisition from multiple beam current monitors is required for electron accelerator production of Mo-99. A two channel system capable of recording data from two beam current monitors has been developed, is currently in use, and is discussed below. The development of a cost-effective method of extending this system to more than two channels and integrating of these measurements into an accelerator control system is the main focus of this report. Data from these current monitors is digitized, processed, and stored by a digital data acquisition system. Limitations and drawbacks with the currently deployed digital data acquisition system have been identified as have been potential solutions, or at least improvements, to these problems. This report will discuss and document the efforts we've made in improving the flexibility and lowering the cost of the data acquisition system while maintaining the minimum requirements.

  8. High RF power test of a CFC antenna module for lower hybrid current drive

    Energy Technology Data Exchange (ETDEWEB)

    Maebara, S.; Seki, M.; Ikeda, Y.; Kiyono, K.; Suganuma, K.; Imai, T. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Goniche, M.; Bibet, Ph.; Brossaud, J.; Cano, V.; Kazarian-Vibert, F.; Froissard, P.; Rey, G. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1998-07-01

    A mock-up of a 3.7 GHz Lower Hybrid Current Drive (LHCD) antenna module was fabricated from Carbon Fibre Composite (CFC) for the development of heat resistive low Z front facing the plasma. This 2 divided waveguide module is made from CFC plates and rods which are Cu-plated to reduce the RF losses. The withstand-voltage, the RF properties and the outgassing rates for long pulses and high RF power were tested at the Lower Hybrid test bed facility of Cadarache. A reference module made from Dispersion Strengthened Copper (DSC) was also fabricated. After the short pulse conditioning, long pulses with a power density ranging between 50 and 150 MW/m{sup 2} were performed with no breakdowns on the CFC module. It was also checked that the highest power density, up to 150 MW/m{sup 2}, could be transmitted when the waveguides are filled with H2 at a pressure of 5 x 10{sup -2} Pa. During a long pulse, the power reflection coefficient remains low in the 0.8-1.3 % range and no significant change in the reflection coefficient is measured after the thermal cycling provided by the long pulse operation. From thermocouple measurements, RF losses of the copper coated CFC and the DSC modules were compared. No significant differences were measured. From pressure measurements, it was found that the outgassing rate of Cu-plated CFC is about 6-7 times larger than of DSC at 300 deg.C. It is concluded that a CFC module is an attractive candidate for the hardening of the tip of the LHCD antenna. (author)

  9. Evolution of the Tore Supra Lower Hybrid Current Drive System for WEST

    Energy Technology Data Exchange (ETDEWEB)

    Delpech, Léna, E-mail: lena.delpech@cea.fr [CEA, IRFM, F-13108 St Paul-Lez-Durance (France); Achard, Joelle; Armitano, Arthur; Berger-By, Gilles; Ekedahl, Annika; Gargiulo, Laurent; Goniche, Marc; Guilhem, Dominique; Hertout, Patrick; Hillairet, Julien; Magne, Roland; Mollard, Patrick [CEA, IRFM, F-13108 St Paul-Lez-Durance (France); Piluso, P. [CNIM Industrial Systems, 83507 La Seyne-sur-Mer (France); Poli, Serge; Prou, Marc; Saille, Alain; Samaille, Franck [CEA, IRFM, F-13108 St Paul-Lez-Durance (France)

    2015-10-15

    Highlights: • Describe the state of the Lower Hybrid heating system for the WEST project. • Detailed the experiments to assess the coupling in WEST configuration. • Give the modifications required on the launchers to be adapted to WEST configuration. • Detailed the technical modifications with the CNIM company on the launchers. - Abstract: The WEST-project (W-tungsten Environment in Steady-state Tokamak) involves equipping Tore Supra with a full tungsten divertor, capable of withstanding heat load of 10 MW/m{sup 2} in steady-state conditions, in discharges sustained by Lower Hybrid Current Drive (LHCD). The LHCD generator, recently upgraded to deliver 9.2 MW/1000 s, is equipped with sixteen TH2103C klystrons powering two launchers. The WEST transformation involves reducing the plasma volume, thus moving the launchers ∼10 cm closer to the tokamak centre. The toroidal curvature of the launchers no longer fits the plasma curvature due to the strong magnetic field ripple effect, leading to a degradation of the LH wave coupling, especially with the Full Active Multijunction Launcher (FAM). The toroidal curvature radius of the FAM launcher mouth will therefore be reshaped from 1700 mm to 2300 mm. The machining process is described in this article. In order to improve the coupling of the LH wave, the local gas injection has been modified to help to meet the requirement of 7 MW/1000 s of LH power coupled to the plasma in the WEST scenarios. Finally, the curvature radius of the waveguide septa are rounded to minimize the excitation of suprathermal electrons near the plasma edge, which can induce high power loads on the plasma facing components.

  10. Magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

    Institute of Scientific and Technical Information of China (English)

    Yang Liu; Min Yun; Jianping Yin

    2006-01-01

    @@ A new scheme to realize a two-dimensional (2D) array of magnetic micro-lenses for a cold atomic beam,formed by an array of square current-carrying wires,is proposed.We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms,and study the dynamic focusing processes of cold atoms passing through the magnetic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method.The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam,even to load ultracold atoms or a BEC sample into a 2D optical lattice formed by blue detuned hollow beams.

  11. Vacuum tube operation analysis under multi-harmonic driving and heavy beam loading effect in J-PARC RCS

    Science.gov (United States)

    Yamamoto, M.; Nomura, M.; Shimada, T.; Tamura, F.; Hara, K.; Hasegawa, K.; Ohmori, C.; Toda, M.; Yoshii, M.; Schnase, A.

    2016-11-01

    An rf cavity in the J-PARC RCS not only covers the frequency range of a fundamental acceleration pattern but also generates multi-harmonic rf voltage because it has a broadband impedance. However, analyzing the vacuum tube operation in the case of multi-harmonics is very complicated because many variables must be solved in a self-consistent manner. We developed a method to analyze the vacuum tube operation using a well-known formula and which includes the dependence on anode current for some variables. The calculation method is verified with beam tests, and the results indicate that it is efficient under condition of multi-harmonics with a heavy beam loading effect.

  12. Technological and physics assessments on heating and current drive systems for DEMO

    Energy Technology Data Exchange (ETDEWEB)

    Franke, Thomas, E-mail: thomas.franke@efda.org [EFDA Close Support Unit, Boltzmannstr. 2, D-85748 Garching (Germany); Max Planck Institute for Plasma Physics, Boltzmannstr. 2, D-85748 Garching (Germany); Barbato, E. [Unità Tecnica Fusione ENEA, C. R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Bosia, G. [Department of Physics, University of Turin, Via P. Giuria 1, 10125 Turin (Italy); Cardinali, A.; Ceccuzzi, S.; Cesario, R. [Unità Tecnica Fusione ENEA, C. R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Van Eester, D. [Laboratory for Plasma Physics, LPP-ERM/KMS, TEC & Belgian EUROfusion Consortium Partner, Brussels (Belgium); Federici, G. [EFDA Close Support Unit, Boltzmannstr. 2, D-85748 Garching (Germany); Gantenbein, G. [Karlsruhe Institute of Technology (KIT), Association EURATOM-KIT, Kaiserstrasse 12, 76131 Karlsruhe (Germany); Helou, W.; Hillairet, J. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Jenkins, I. [CCFE, Culham Science Centre, Abingdon OX143DB (United Kingdom); Kazakov, Ye.O. [Laboratory for Plasma Physics, LPP-ERM/KMS, TEC & Belgian EUROfusion Consortium Partner, Brussels (Belgium); Kemp, R. [CCFE, Culham Science Centre, Abingdon OX143DB (United Kingdom); Lerche, E. [Laboratory for Plasma Physics, LPP-ERM/KMS, TEC & Belgian EUROfusion Consortium Partner, Brussels (Belgium); Mirizzi, F. [Unità Tecnica Fusione ENEA, C. R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Noterdaeme, J.-M.; Poli, E. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, D-85748 Garching (Germany); Porte, L. [Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 13, CH-1015 Lausanne (Switzerland); Ravera, G.L. [Unità Tecnica Fusione ENEA, C. R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); and others

    2015-10-15

    Highlights: • Basic physics requirements of H&CD systems in DEMO have been captured. • The four H&CD systems NBI, EC, IC and LH were analysed to optimize performance. • Novel solutions were studied to overcome the limitations of the present H&CD systems. • RAMI as well as efficiency and optimized design of H&CD systems have been assessed. • Further constraints by remote maintenance or breeding blanket interactions were considered. - Abstract: The physics requirements of the heating and current (H&CD) systems in a Demonstration Fusion Power Plant (DEMO) are often beyond the actual level of design maturity and technology readiness required. The recent EU fusion roadmap advocates a pragmatic approach and favours, for the initial design integration studies, systems to be as much as possible, extrapolated from the ITER experience. To reach the goal of demonstrating the production of electricity in DEMO with a closed fuel cycle by 2050, one must ensure reliability, availability, maintainability, inspectability (RAMI) as well as performance, efficiency and optimized design for the H&CD systems. In the recent Power Plant Physics & Technology (PPP&T) Work Programme, a number of H&CD studies were performed. The four H&CD systems Neutral Beam (NB) Injection, Electron Cyclotron (EC), Ion Cyclotron (IC) and Lower Hybrid (LH) were considered. First, a physics optimization study was made assuming all technologies are available and identifying which parameters are needed to optimize the performance for given plasma parameters. Separately, the (i) technological maturity was considered (e.g. 240 GHz gyrotrons for EC) and (ii) technologies were adapted (e.g. multi-stage depressed collector for EC) or (iii) novel solutions (e.g. photo-neutralization for NB or new antennae concepts for IC) were studied to overcome the limitations of the present H&CD systems with respect to DEMO requirements. Further constraints imposed by remote maintenance or breeding blanket interactions

  13. Upward electron beams measured by DE-1 - A primary source of dayside region-1 Birkeland currents

    Science.gov (United States)

    Burch, J. L.; Reiff, P. H.; Sugiura, M.

    1983-01-01

    Measurements made by the High Altitude Plasma Instrument on DE-1 have shown that intense upward electron beams with energies from about 20 eV to about 200 eV are a common feature of the region just equatorward of the morning-side polar cusp. Computations of the currents carried by these beams and by the precipitating cusp electrons show excellent agreement with the simultaneous DE-1 magnetometer measurements for both upward and downward Birkeland currents. The data indicate that cold ionospheric electrons, which carry the downward region-1 Birkeland currents on the morning side, are accelerated upward by potential drops of a few tens of eV at altitudes of several thousand kilometers. This acceleration process allows spacecraft above those altitudes to measure routinely the charge carriers of both downward and upward current systems.

  14. Low energy high current pulsed electron beam treatment for improving surface microstructure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J; Allain-Bonasso, N; Zhang, X D; Hao, S Z; Grosdider, T; Dong, C [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Zou, J X, E-mail: jiang.wu@univ-metz.fr, E-mail: thierry.grosdidier@univ-metz.fr [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-06-15

    Low energy high current pulsed electron beam (LEHCPEB) is a fairly new technique for surface modifications authorizing improvement in wear and corrosion properties as well as texture changes and hardening. This contribution highlights some microstructure modifications encountered at the surface of HCPEB treated steels and bulk metallic glasses taking into account the effects of surface melting and the effects of the induced stress.

  15. Thermal evaluation of different DC multi-conductor cable cross-sections and installation patterns for the CLIC drive-beam quadrupoles

    CERN Document Server

    Maglio, D

    2007-01-01

    The main goal of this study is to determine the thermal behaviour of different dc multi-conductor cable cross-sections and installations patterns for the CLIC drive beam quadrupoles loaded with increasing values of current intensity. A simplified two dimensional model of the heat transfer problem was prepared with a commercial CFD software, STAR-CD 4.2. The heat flux generated by Joule effect in conductors was estimated taking into account the current value per conductor and the temperature dependence of the copper electrical resistance. In parallel, a geometrical simplification of the problem has been done in order to be able to apply theoretical formulas which have been implemented by Microsoft Excel. Obtained results have been compared with those got by the dedicated software, showing between them a good correspondence for two-conductor cables and confirming, for this case, the rules given in the in the French norm NF C15-100. In case of multiconductor cables, attention is to be paid to the temperature lev...

  16. The current status of cone beam computed tomography imaging in orthodontics

    OpenAIRE

    S. Kapila; Conley, R S; Harrell, W E

    2011-01-01

    Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. Currently available information from studies using CBCT can be organized into five broad categories: 1, the assess...

  17. Study of lower hybrid current drive efficiency and its correlation with photon temperatures in the HT-7 tokamak

    Science.gov (United States)

    Younis, J.; Wan, B. N.; Lin, S. Y.; Shi, Y. J.; Ding, B. J.; Gong, X.; HT-7 Team

    2009-07-01

    Lower hybrid current drive (LHCD) efficiency is a very important parameter. The experimental current drive efficiency is defined as η = IrfneR/PLH, where Irf is the current driven by the lower hybrid waves (LHWs), ne is the central line-average density, R is the major radius of the plasma and PLH is the injected LH wave power absorbed by the plasma through Landau damping. A study of current drive efficiency of LHWs in the HT-7 tokamak has been carried out in the parameter ranges: ne = (1.2-2.5) × 1019 m-3, Ip = (80-200) kA, Bt = 1.8 T, PLH = (188-532) kW in the limiter configuration. Current drive efficiency is investigated through a simple correlation with photon temperature and normalized intensity of fast electron bremstrahlung emission, which is, in the first approximation, proportional to the averaged velocity and population of the fast electrons. The plasma current scanning experiment shows that CD efficiency increase is due to the increase in both the photon temperature and the population of the fast electrons generated by LHWs. The density scanning experiment shows that as the plasma density is increased, an increment in CD efficiency along with the increase in the population of fast electrons is observed. The slowing down through the collisions with bulk electrons is mainly responsible for the decreased photon temperature during the plasma density scan. These experiments strongly suggest the dominant role of the population of fast electrons generated by LHCD and the generation of the current carried by fast electrons.

  18. When do we think it is Safe to Drive after Hand Surgery? – Current Practice and Legal Perspective

    LENUS (Irish Health Repository)

    Murphy, SF

    2016-11-01

    Patients recovering from hand surgery frequently ask when it is safe to drive and it is unclear where the responsibility lies; the surgeon, the patient or the insurance company. An eight-question survey looking at various aspects of clinical practice was circulated to consultant and trainee plastic and orthopaedic surgeons in Ireland and the UK. Of the 89 surgeons who replied, (53%) felt the decision when to drive was the patient’s compared with the insurance company (40%) and the surgeon (7%). 80% advised patients to contact their insurance company. 87% were unaware of current regulations or guidelines. National guidelines were vague and left the decision with the treating doctor. Similarly, major insurers advise patients to contact their doctor for advice. From a legal standpoint, the patient has a duty of care to other road users to be in full control of his vehicle prior to driving, regardless of any advice received.

  19. Search for lepton number violating charged current processes with neutrino beams

    Energy Technology Data Exchange (ETDEWEB)

    Kanemura, Shinya, E-mail: kanemu@sci.u-toyama.ac.jp [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Kuno, Yoshitaka, E-mail: kuno@phys.sci.osaka-u.ac.jp [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Ota, Toshihiko, E-mail: toshi@mppmu.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany)

    2013-02-26

    We propose a novel idea on measurements to understand which physics mechanism is responsible for the origin of a small neutrino mass, by searching for the processes of lepton number violating charged current interaction with incident of a neutrino beam. It turns out that only the proposed measurements could provide a potential to discriminate the mechanisms, in particular the ones called loop-induced mechanisms of neutrino mass generation, from the others. The expected rates of these processes based on some theoretical assumptions are estimated. They are found to be sizable so that detection of such processes could be achievable at near detectors in future highly intense neutrino-beam facilities.

  20. Study of lower hybrid current drive system in tokamak fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Maebara, Sunao [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-01-01

    This report describes R and D of a high-power klystron, RF vacuum window, low-outgassing antenna and a front module for a plasma-facing antenna aiming the 5 GHz Lower Hybrid Current Drive (LHCD) system for the next Tokamak Fusion Device. 5 GHz klystron with a low-perveances of 0.7 {mu}P is designed for a high-power and a high-efficiency, the output-power of 715 kW and the efficiency of 63%, which are beyond the conventional design scaling of 450 kW-45%, are performed using the prototype klystron which operates at the pulse duration of 15 {mu}sec. A new pillbox window, which has an oversized length in both the axial and the radial direction, are designed to reduce the RF power density and the electric field strength at the ceramics. It is evaluated that the power capability by cooling edge of ceramics is 1 MW with continuous-wave operation. The antenna module using Dispersion Strengthened Copper which combines high mechanical property up to 500degC with high thermal conductivity, are developed for a low-outgassing antenna in a steady state operation. It is found that the outgassing rate is in the lower range of 4x10{sup -6} Pam{sup 3}/sm{sup 2} at the module temperature of 300degC, which requires no active vacuum pumping of the LHCD antenna. A front module using Carbon Fiber Composite (CFC) are fabricated and tested for a plasma facing antenna which has a high heat-resistive. Stationary operation of the CFC module with water cooling is performed at the RF power of 46 MWm{sup -2} (about 2 times higher than the design value) during 1000 sec, it is found that the outgassing rate is less than 10{sup -5} Pam{sup 3}/sm{sup 2} which is low enough for an antenna material. (author)

  1. A compact x-ray beam intensity monitor using gas amplified sample current measurement

    Science.gov (United States)

    Hayakawa, Shinjiro; Kobayashi, Kazuo; Gohshi, Yohichi

    2000-01-01

    Development of a compact beam intensity monitor using gas amplified sample current measurement is described. The monitor can be a powerful tool for x-ray spectroscopy and microscopy when the beam is defined by a small pinhole or slits and when the workspace around the sample is limited. The thickness of the monitor is as small as approximately 3 mm, and the dimension is 10 mm square. The photon flux is monitored by measuring x-ray excited current from an Al foil under atmospheric conditions. Emitted electrons from the Al foil can ionize surrounding air molecules, and the gas amplified current can be measured with the use of a biased grid that prevents created ion pairs from recombination.

  2. Application of ESPRIT in Broad Beam HF Ground Wave Radar Sea Surface Current Mapping

    Institute of Scientific and Technical Information of China (English)

    Liu Dan-hong; Wu Xiong-bin; Wen Bi-yang; Cheng Feng

    2004-01-01

    HF surface wave radar system OSMAR2000 is a broad-beam sea-state detecting radar. ESPRIT (Estimation of Signal Parameters via Rotational Invariance Technique) algorithm is proposed to apply in DOA (direction of arrival) determination of sea echoes. The algorithm of ESPRIT is briefly introduced first. Then discussions are made on the technique for application in the OSMAR2000 framework. Numerical simulation results are presented to demonstrate the feasibility of radial current mapping based on this method. The algorithm manifests significant performance and computational advantages compared with that of MUSIC. Data acquired by OSMAR2000 are processed to give radial current map and the synthesized vector currents are compared with the in-situ measurement with traditional means. The results show the validity of ESPRIT application in DOA determination for broad-beam radar.

  3. Discharge current and current of supershort avalanche E-beam at volume nanosecond discharge in non-uniform electric field

    Science.gov (United States)

    Tarasenko, Victor F.; Rybka, Dmitrii V.; Baksht, Evgenii H.; Kostyrya, Igor'D.; Lomaev, Mikhail I.

    2008-01-01

    The gas diode current-voltage characteristics at the voltage pulses applied from the RADAN and SM-3NS pulsers, and generation of an supershort avalanche electron beam (SAEB) have been studied experimentally in an inhomogeneous electric field upon a nanosecond breakdown in an air gap at atmospheric pressure. Displacement currents with amplitude over 1 kA have been observed and monitored. It is shown that the displacement current amplitude gets increased due to movement of the dense plasma front and charging of a "capacitor" formed between plasma and anode. The SAEB generation time relatively to the discharge current pulses and the gap voltage were determined in the experiments. It is shown that the SAEB current maximum at the pulser voltages of hundreds kV is registered on the discharge current pulse front, before the discharge current peak of the gas diode capacitance, and the delay time of these peaks is determined by the value of an interelectrode spacing. The delay time in case of a gap of 16 mm and air breakdown at atmospheric pressure was ~100 ps, and in case of 10 mm it was less than 50 ps.

  4. Input current interharmonics in adjustable speed drives caused by fixed-frequency modulation techniques

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Loh, Poh Chiang;

    2016-01-01

    Adjustable Speed Drives (ASDs) based on double-stage conversion systems may inject interharmonics distortion into the grid, other than the well-known characteristic harmonic components. The problems created by interharmonics make it necessary to find their precise sources, and, to adopt an approp...

  5. Performance Evaluation of Electronic Inductor-Based Adjustable Speed Drives with Respect to Line Current Interharmonics

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Zare, Firuz;

    2017-01-01

    Electronic Inductor (EI)-based front-end rectifiers have a large potential to become the prominent next generation of Active Front End (AFE) topology used in many applications including Adjustable Speed Drives (ASDs) for systems having unidirectional power flow. The EI-based ASD is mostly attract...

  6. Proceedings of the 1979 workshop on beam current limitations in storage rings, July 16-27, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrini, C. (ed.)

    1979-01-01

    The Workshop on Beam Current Limitations in Storage Rings was held at Brookhaven National Laboratory from July 16 to 27, 1979. The purpose of this Workshop was to discuss the physical mechanisms limiting the beam current or current density in accelerators or storage rings. Many of these machines are now being built or planned for a variety of applications, such as colliding beam experiments, synchrotron light production, heavy ion beams. This diversity was reflected in the Workshop and in the papers which have been contributed to these Proceedings. The twenty-one papers from the workshop were incorporated individually in the data base. (GHT)

  7. Comparison of Parmela and MAFIA Simulations of Beam Dynamics in High Current Photoinjector

    CERN Document Server

    Kurennoy, Sergey S

    2004-01-01

    A high-current RF photoinjector producing low-emittance electron beam is an important technology for high-power CW FEL. LANL-AES team designed a 2.5-cell, pi-mode, 700-MHz normal-conducting RF photoinjector with magnetic emittance compensation. With the electric field gradients of 7, 7, and 5 MV/m in the three subsequent cells, the photoinjector will produce a 2.5-MeV electron beam with 3-nC charge per bunch and the transverse rms emittance 7 mm-mrad. Beam dynamics in the photoinjector has been modeled in details. In addition to the usual approach, with fields calculated by Superfish-Poisson and beam simulations performed by Parmela, we also used MAFIA group of codes, both to calculate cavity fields and to model beam dynamics with its particle-in-cell module TS. The second way naturally includes wake-field effects into consideration. The simulation results and comparison between two approaches will be presented.

  8. A Framework for Applying Point Clouds Grabbed by Multi-Beam LIDAR in Perceiving the Driving Environment.

    Science.gov (United States)

    Liu, Jian; Liang, Huawei; Wang, Zhiling; Chen, Xiangcheng

    2015-08-31

    The quick and accurate understanding of the ambient environment, which is composed of road curbs, vehicles, pedestrians, etc., is critical for developing intelligent vehicles. The road elements included in this work are road curbs and dynamic road obstacles that directly affect the drivable area. A framework for the online modeling of the driving environment using a multi-beam LIDAR, i.e., a Velodyne HDL-64E LIDAR, which describes the 3D environment in the form of a point cloud, is reported in this article. First, ground segmentation is performed via multi-feature extraction of the raw data grabbed by the Velodyne LIDAR to satisfy the requirement of online environment modeling. Curbs and dynamic road obstacles are detected and tracked in different manners. Curves are fitted for curb points, and points are clustered into bundles whose form and kinematics parameters are calculated. The Kalman filter is used to track dynamic obstacles, whereas the snake model is employed for curbs. Results indicate that the proposed framework is robust under various environments and satisfies the requirements for online processing.

  9. The Effect of Cross-Beam Energy Transfer on Two-Plasmon Decay in Direct-Drive Implosions

    Science.gov (United States)

    Froula, D. H.; Follett, R. K.; Henchen, R. J.; Davis, A. K.; Goncharov, V. N.; Edgell, D. H.; Solodov, A. A.; Michel, D. T.; Myatt, J. F.; Shaw, J. G.; Stoeckl, C.

    2016-10-01

    Mitigation of cross-beam energy transfer (CBET) in direct-drive implosions was shown to increase the hot electrons generated by two-plasmon decay. Reducing the diameter of the laser spots by 30% significantly reduces CBET and the laser absorption was measured to increase from 75% to nearly 90%. The reduced CBET leads to higher intensity at the quarter-critical density surface, increasing the hot-electron production by a factor of 7 . Adding a thin layer (0.6 to 1.1 μm) of Si to the target ablator reduced the hot-electron fraction by a factor of 2 . Spatially resolved Thomson-scattering measurements show an 15 % increase in the electron temperature and an increase in the Si fraction at the quarter-critical surface when the Si layer is added. Three-dimensional laser-plasma interaction simulations of hot-electron production using the code LPSE show that in addition to the reduced gain (smaller ILn Te), the observed reduction in hot electrons results from increased electron-ion collision frequencies and reduced Landau damping of ion-acoustic waves. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  10. A Framework for Applying Point Clouds Grabbed by Multi-Beam LIDAR in Perceiving the Driving Environment

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2015-08-01

    Full Text Available The quick and accurate understanding of the ambient environment, which is composed of road curbs, vehicles, pedestrians, etc., is critical for developing intelligent vehicles. The road elements included in this work are road curbs and dynamic road obstacles that directly affect the drivable area. A framework for the online modeling of the driving environment using a multi-beam LIDAR, i.e., a Velodyne HDL-64E LIDAR, which describes the 3D environment in the form of a point cloud, is reported in this article. First, ground segmentation is performed via multi-feature extraction of the raw data grabbed by the Velodyne LIDAR to satisfy the requirement of online environment modeling. Curbs and dynamic road obstacles are detected and tracked in different manners. Curves are fitted for curb points, and points are clustered into bundles whose form and kinematics parameters are calculated. The Kalman filter is used to track dynamic obstacles, whereas the snake model is employed for curbs. Results indicate that the proposed framework is robust under various environments and satisfies the requirements for online processing.

  11. A Framework for Applying Point Clouds Grabbed by Multi-Beam LIDAR in Perceiving the Driving Environment

    Science.gov (United States)

    Liu, Jian; Liang, Huawei; Wang, Zhiling; Chen, Xiangcheng

    2015-01-01

    The quick and accurate understanding of the ambient environment, which is composed of road curbs, vehicles, pedestrians, etc., is critical for developing intelligent vehicles. The road elements included in this work are road curbs and dynamic road obstacles that directly affect the drivable area. A framework for the online modeling of the driving environment using a multi-beam LIDAR, i.e., a Velodyne HDL-64E LIDAR, which describes the 3D environment in the form of a point cloud, is reported in this article. First, ground segmentation is performed via multi-feature extraction of the raw data grabbed by the Velodyne LIDAR to satisfy the requirement of online environment modeling. Curbs and dynamic road obstacles are detected and tracked in different manners. Curves are fitted for curb points, and points are clustered into bundles whose form and kinematics parameters are calculated. The Kalman filter is used to track dynamic obstacles, whereas the snake model is employed for curbs. Results indicate that the proposed framework is robust under various environments and satisfies the requirements for online processing. PMID:26404290

  12. Review of Recent Advances in Heating and Current Drive on Textor

    NARCIS (Netherlands)

    Messiaen, A. M.; Van Eester, D.; Koch, R.; Ongena, J.; van Wassenhove, G.; Weynants, R. R.; Borgermans, P.; Conrads, H.; Dumortier, P.; Durodie, F.; Fuchs, G.; Euringer, H.; Giesen, B.; Hillis, D.; Hoenen, F.; Koslowski, H. R.; KramerFlecken, A.; Lochter, M.; Oyevaar, T.; Soltwisch, H.; Tammen, H. F.; Telesca, G.; Uhlemann, R.; van den Durpel, L.; Vandenplas, P. E.; Soltwisch, H.; Tammen, H. F.; Telesca, G.; Uhlemann, R.; van den Durpel, L.; Vandenplas, P. E.; Vannieuwenhove, R.; Van Oost, G.; Vervier, M.; Waidmann, G.

    1993-01-01

    Co-injection (DO --> D+) applied to TEXTOR leads to a hot ion node regime with enhanced confinement. A synergistic increase of the beam effects is observed with the addition of ICRH at omega = 2omega(cD) = omega(cH) (H minority heating scenario) resulting, beside other reviewed effects, in a sign

  13. Saturation current and collection efficiency for ionization chambers in pulsed beams.

    Science.gov (United States)

    DeBlois, F; Zankowski, C; Podgorsak, E B

    2000-05-01

    Saturation currents and collection efficiencies in ionization chambers exposed to pulsed megavoltage photon and electron beams are determined assuming a linear relationship between 1/I and 1/V in the extreme near-saturation region, with I and V the chamber current and polarizing voltage, respectively. Careful measurements of chamber current against polarizing voltage in the extreme near-saturation region reveal a current rising faster than that predicted by the linear relationship. This excess current combined with conventional "two-voltage" technique for determination of collection efficiency may result in an up to 0.7% overestimate of the saturation current for standard radiation field sizes of 10X10 cm2. The measured excess current is attributed to charge multiplication in the chamber air volume and to radiation-induced conductivity in the stem of the chamber (stem effect). These effects may be accounted for by an exponential term used in conjunction with Boag's equation for collection efficiency in pulsed beams. The semiempirical model follows the experimental data well and accounts for both the charge recombination as well as for the charge multiplication effects and the chamber stem effect.

  14. Design and Preparation of RF System for the Lower Hybrid Fast Wave Heating and Current Drive Research on VEST

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Ho; Jeong, Seung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Hyun Woo; Lee, Byung Je [Kwang Woon University, Chuncheon (Korea, Republic of); Jo, Jong Gab; Lee, Hyun Young; Hwang, Yong Seok [Seoul National University, Seoul (Korea, Republic of)

    2015-10-15

    Continuous current drive is one of the key issues for tokamak to be a commercial fusion reactor. As a part of new and efficient current drive concept research by using a Lower Hybrid Fast Wave (LHFW), the experimental study is planned on Versatile Experiment Spherical Torus (VEST) and a RF system is being developed in collaboration with Kwang Woon University (KWU), Korea Accelerator Plasma Research Association (KAPRA) and Seoul National University (SNU). The LHFW RF system includes UHF band klystron, inter-digital antenna, RF diagnostics and power transmission sub components such as circulator, DC breaker, vacuum feed-thru. The design and preparation status of the RF system will be presented in the meeting in detail. A RF system has been designed and prepared for the experimental study of efficient current drive by using Lower Hybrid Fast Wave. Overall LHFW RF system including diagnostics is designed to deliver about 10 kW in UHF band. And the key hardware components including klystron and antenna are being prepared and designed through the collaboration with KWU, KAPRA and SNU.

  15. Studies of challenge in lower hybrid current drive capability at high density regime in experimental advanced superconducting tokamak

    Science.gov (United States)

    Ding, B. J.; Li, M. H.; Li, Y. C.; Wang, M.; Liu, F. K.; Shan, J. F.; Li, J. G.; Wan, B. N.; Wan

    2017-02-01

    Aiming at a fusion reactor, two issues must be solved for the lower hybrid current drive (LHCD), namely good lower hybrid wave (LHW)-plasma coupling and effective current drive at high density. For this goal, efforts have been made to improve LHW-plasma coupling and current drive capability at high density in experimental advanced superconducting tokamak (EAST). LHW-plasma coupling is improved by means of local gas puffing and gas puffing from the electron side is taken as a routine way for EAST to operate with LHCD. Studies of high density experiments suggest that low recycling and high lower hybrid (LH) frequency are preferred for LHCD experiments at high density, consistent with previous results in other machines. With the combination of 2.45 GHz and 4.6 GHz LH waves, a repeatable high confinement mode plasma with maximum density up to 19~\\text{m}-3$ was obtained by LHCD in EAST. In addition, in the first stage of LHCD cyclic operation, an alternative candidate for more economical fusion reactors has been demonstrated in EAST and further work will be continued.

  16. Development of long pulse RF heating and current drive for H-mode scenarios with metallic walls in WEST

    Energy Technology Data Exchange (ETDEWEB)

    Ekedahl, Annika, E-mail: annika.ekedahl@cea.fr; Bourdelle, Clarisse; Artaud, Jean-François; Bernard, Jean-Michel; Bufferand, Hugo; Colas, Laurent; Decker, Joan; Delpech, Léna; Dumont, Rémi; Goniche, Marc; Helou, Walid; Hillairet, Julien; Lombard, Gilles; Magne, Roland; Mollard, Patrick; Nardon, Eric; Peysson, Yves; Tsitrone, Emmanuelle [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France)

    2015-12-10

    The longstanding expertise of the Tore Supra team in long pulse heating and current drive with radiofrequency (RF) systems will now be exploited in the WEST device (tungsten-W Environment in Steady-state Tokamak) [1]. WEST will allow an integrated long pulse tokamak programme for testing W-divertor components at ITER-relevant heat flux (10-20 MW/m{sup 2}), while treating crucial aspects for ITER-operation, such as avoidance of W-accumulation in long discharges, monitoring and control of heat fluxes on the metallic plasma facing components (PFCs) and coupling of RF waves in H-mode plasmas. Scenario modelling using the METIS-code shows that ITER-relevant heat fluxes are compatible with the sustainment of long pulse H-mode discharges, at high power (up to 15 MW / 30 s at I{sub P} = 0.8 MA) or high fluence (up to 10 MW / 1000 s at I{sub P} = 0.6 MA) [2], all based on RF heating and current drive using Ion Cyclotron Resonance Heating (ICRH) and Lower Hybrid Current Drive (LHCD). This paper gives a description of the ICRH and LHCD systems in WEST, together with the modelling of the power deposition of the RF waves in the WEST-scenarios.

  17. Dosimetric response for crystalline and nanostructured aluminium oxide to a high-current pulse electron beam.

    Science.gov (United States)

    Nikiforov, S V; Kortov, V S

    2014-11-01

    The main thermoluminescent (TL) and dosimetric properties of the detectors based on anion-defective crystalline and nanostructured aluminium oxide after exposure to a high-current pulse electron beam are studied. TL peaks associated with deep-trapping centres are registered. It is shown that the use of deep-trap TL at 200-600°С allows registering absorbed doses up to 750 kGy for single-crystalline detectors and those up to 6 kGy for nanostructured ones. A wide range of the doses registered, high reproducibility of the TL signal and low fading contribute to a possibility of using single-crystalline and nanostructured aluminium oxide for the dosimetry of high-current pulse electron beams.

  18. Electronic regulation of the SPS extraction quadrupole current pulse shape for improved stability of the extracted beam

    CERN Document Server

    Carlier, E; Vossenberg, Eugène B; CERN. Geneva. SPS and LEP Division

    1996-01-01

    In order to minimise the event pile-up and therefore optimise the detection efficiency, Chorus and Nomad experiments ask for a long and rectangular spill profile. At present the fast-slow extractio n is generated by driving the beam into a quadrupolar-octopolar resonance by exciting a quadrupole magnet with a semi-trapezoidal current [1]. The trapezoidal pulse shape is obtained by dischargin g a capacitor into the magnet coils. After a few milliseconds of undamped discharge a fixed resistor is switched into the circuit. The attenuation is then higher and the sine wave continues with a lower gradient. The two gradients can be adjusted by varying the initial capacitor voltage and the time at which the resistor is switched into the circuit. A further degree of freedom in determini ng the spill shape has been added by allowing the possibility of changing the second slope value independently of the initial conditions. This task is achieved by means of a variable current sour ce added in parallel to the fixed resis...

  19. Charged current disappearance measurements in the NuMI off-axis beam

    Energy Technology Data Exchange (ETDEWEB)

    R. H. Bernstein

    2003-09-25

    This article studies the potential of combining charged-current disappearance measurements of {nu}{sub {mu}} {yields} {nu}{sub {tau}} from MINOS and an off-axis beam. The author finds that the error on {Delta}m{sup 2} from a 100 kt-yr off-axis measurement is a few percent of itself. Further, the author found little improvement to an off-axis measurement by combining it with MINOS.

  20. Experiments on current-driven three-dimensional ion sound turbulence. I - Return-current limited electron beam injection. II - Wave dynamics

    Science.gov (United States)

    Stenzel, R. L.

    1978-01-01

    Pulsed electron beam injection into a weakly collisional magnetized background plasma is investigated experimentally; properties of the electron beam and background plasma, as well as the low-frequency instabilities and wave dynamics, are discussed. The current of the injected beam closes via a field-aligned return current of background electrons. Through study of the frequency and wavenumber distribution, together with the electron distribution function, the low-frequency instabilities associated with the pulsed injection are identified as ion acoustic waves driven unstable by the return current. The frequency cut-off of the instabilities predicted from renormalized plasma turbulence theory, has been verified experimentally.

  1. Open-loop correction for an eddy current dominated beam-switching magnet

    Science.gov (United States)

    Koseki, K.; Nakayama, H.; Tawada, M.

    2014-04-01

    A beam-switching magnet and the pulsed power supply it requires have been developed for the Japan Proton Accelerator Research Complex. To switch bunched proton beams, the dipole magnetic field must reach its maximum value within 40 ms. In addition, the field flatness should be less than 5 × 10-4 to guide each bunched beam to the designed orbit. From a magnetic field measurement by using a long search coil, it was found that an eddy current in the thick endplates and laminated core disturbs the rise of the magnetic field. The eddy current also deteriorates the field flatness over the required flat-top period. The measured field flatness was 5 × 10-3. By using a double-exponential equation to approximate the measured magnetic field, a compensation pattern for the eddy current was calculated. The integrated magnetic field was measured while using the newly developed open-loop compensation system. A field flatness of less than 5 × 10-4, which is an acceptable value, was achieved.

  2. Open-loop correction for an eddy current dominated beam-switching magnet

    Energy Technology Data Exchange (ETDEWEB)

    Koseki, K., E-mail: kunio.koseki@kek.jp; Nakayama, H.; Tawada, M. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2014-04-15

    A beam-switching magnet and the pulsed power supply it requires have been developed for the Japan Proton Accelerator Research Complex. To switch bunched proton beams, the dipole magnetic field must reach its maximum value within 40 ms. In addition, the field flatness should be less than 5 × 10{sup −4} to guide each bunched beam to the designed orbit. From a magnetic field measurement by using a long search coil, it was found that an eddy current in the thick endplates and laminated core disturbs the rise of the magnetic field. The eddy current also deteriorates the field flatness over the required flat-top period. The measured field flatness was 5 × 10{sup −3}. By using a double-exponential equation to approximate the measured magnetic field, a compensation pattern for the eddy current was calculated. The integrated magnetic field was measured while using the newly developed open-loop compensation system. A field flatness of less than 5 × 10{sup −4}, which is an acceptable value, was achieved.

  3. High-power Čerenkov microwave oscillators utilizing High-Current nanosecond Electron beams

    Science.gov (United States)

    Korovin, S. D.; Polevin, S. D.; Rostov, V. V.

    1996-12-01

    A short review is given of results obtained at the Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences on generating high-power microwave radiation. Most of the research was devoted to a study of stimulated Čerenkov radiation from relativistic electron beams. It is shown that the efficiency of a relativistic 3-cm backward wave tube with a nonuniform coupling resistance can reach 35%. High-frequency radiation was discovered in the emission spectrum of the Čerenkov oscillators and it was shown that the nature of the radiation was associated with the stimulated scattering of low-frequency radiation by the relativistic electrons. Radiation with a power of 500 MW was obtained in the 8-mm wavelength range using a two-beam Čerenkov oscillator. High-current pulse-periodic nanosecond accelerators with a charging device utilizing a Tesla transformer were used in the experiments. The possibility was demonstrated of generating high-power microwave radiation with a pulse-repetition frequency of up to 100 Hz. An average power of ˜500 W was achieved from the relativistic oscillators. A relativistic backward wave tube with a high-current electron beam was used to make a prototype nanosecond radar device. Some of the results presented were obtained jointly with the Russian Academy of Sciences Institute of Applied Physics. Questions concerning multiwave Čerenkov interaction are not considered in this paper.

  4. Coherent Effects of High Current Beam in Project-X Linac

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, Alexander; Yakovlev, Vyacheslav; Gonin, Ivan; Khabiboulline, Timergali; Lunin, Andrei; Saini, Arun; Solyak, Nikolay; Vostrikov, Alexander

    2013-04-01

    Resonance excitation of longitudinal high order modes in superconducting RF structures of Project-X continuous wave linac is studied. We analyze regimes of operation of the linac with high beam current, which can be used to provide an intense muon source for the future Neutrino Factory or Muon Collider, and also important for the Accelerator-Driven Subcritical systems. We calculate power loss and associated heat load to the cryogenic system. Longitudinal emittance growth is estimated. We consider an alternative design of the elliptical cavity for the high energy part of the linac, which is more suitable for high current operation.

  5. Numerical simulation of the processes of small-diameter high-current electron beam shaping and injection

    CERN Document Server

    Gordeev, V S; Myskov, G A

    2001-01-01

    With the aid of BEAM 25 program there was carried out the numerical simulation of the non-stationary process of shaping a small-diameter (<= 20mm) high-current hollow electron beam in a diode with magnetic insulation,as well as of the process of beam injection into the accelerating LIA track. The diode configuration for the purpose of eliminating the leakage of electron flux to the anode surface was update. Presented are the results of calculation of the injected beam characteristics (amplitude-time parameters of a current pulse, space-angle distributions of electrons etc.) depending on diode geometric parameters.

  6. REACTIVE CURRENT OF AN INDUCTION ELECTRIC DRIVES WITH THYRISTOR VOLTAGE REGULATOR

    Directory of Open Access Journals (Sweden)

    J.V. Kovalova

    2014-12-01

    Full Text Available A model for a separation of reactive constituent from current of idling of an induction motor at its feed from a thyristor voltage regulator in the dependences on the control angle of thyristors is developed. As a result of modeling, dependence of relative reactive current which is approximated by formula for calculation of effective current of reactive constituent of nonsinusoidal current is obtained.

  7. Determination of the ReA Electron Beam Ion Trap electron beam radius and current density with an X-ray pinhole camera

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Thomas M., E-mail: baumannt@nscl.msu.edu; Lapierre, Alain, E-mail: lapierre@nscl.msu.edu; Kittimanapun, Kritsada; Schwarz, Stefan; Leitner, Daniela; Bollen, Georg [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), 640 S. Shaw Lane, East Lansing, Michigan, 48824 (United States)

    2014-07-15

    The Electron Beam Ion Trap (EBIT) of the National Superconducting Cyclotron Laboratory at Michigan State University is used as a charge booster and injector for the currently commissioned rare isotope re-accelerator facility ReA. This EBIT charge breeder is equipped with a unique superconducting magnet configuration, a combination of a solenoid and a pair of Helmholtz coils, allowing for a direct observation of the ion cloud while maintaining the advantages of a long ion trapping region. The current density of its electron beam is a key factor for efficient capture and fast charge breeding of continuously injected, short-lived isotope beams. It depends on the radius of the magnetically compressed electron beam. This radius is measured by imaging the highly charged ion cloud trapped within the electron beam with a pinhole camera, which is sensitive to X-rays emitted by the ions with photon energies between 2 keV and 10 keV. The 80%-radius of a cylindrical 800 mA electron beam with an energy of 15 keV is determined to be r{sub 80%}=(212±19)μm in a 4 T magnetic field. From this, a current density of j = (454 ± 83)A/cm{sup 2} is derived. These results are in good agreement with electron beam trajectory simulations performed with TriComp and serve as a test for future electron gun design developments.

  8. Radiation induced currents in parallel plate ionization chambers: measurement and Monte Carlo simulation for megavoltage photon and electron beams.

    Science.gov (United States)

    Abdel-Rahman, Wamied; Seuntjens, Jan P; Verhaegen, Frank; Podgorsak, Ervin B

    2006-09-01

    Polarity effects in ionization chambers are caused by a radiation induced current, also known as Compton current, which arises as a charge imbalance due to charge deposition in electrodes of ionization chambers. We used a phantom-embedded extrapolation chamber (PEEC) for measurements of Compton current in megavoltage photon and electron beams. Electron contamination of photon beams and photon contamination of electron beams have a negligible effect on the measured Compton current. To allow for a theoretical understanding of the Compton current produced in the PEEC effect we carried out Monte Carlo calculations with a modified user code, the COMPTON/ EGSnrc. The Monte Carlo calculated COMPTON currents agree well with measured data for both photon and electron beams; the calculated polarity correction factors, on the other hand, do not agree with measurement results. The conclusions reached for the PEEC can be extended to parallel-plate ionization chambers in general.

  9. Switching processes in TGS crystals irradiated by high-current electron beam

    CERN Document Server

    Efimov, V V; Klevtsova, E A; Tyutyunnikov, S I

    2002-01-01

    The relaxation processes study of the dielectric permittivity epsilon during commutation of the external electric field in triglycine sulphate (NH sub 2 CH sub 2 COOH) sub 3 centre dot H sub 2 SO sub 4 (TGS) single crystal plates before and after irradiation by a high-current pulsed electron beam with different doses at various temperatures is presented. The parameters of the electron beam produced by the accelerator facility as a source were: energy E = 250 keV, current density I = 1000 A/cm sup 2 , fluence F = 15 J/cm sup 2 , pulse duration tau = 300 ns, beam density 5 centre dot sup 1 5 electrons/cm sup 2 per pulse. It was shown that the dependences of epsilon (t) are described by the Kohlrausch law: epsilon (t) approx exp (-t/tau) supalpha, where alpha is the average relaxation time of the all volume samples, 0 < alpha <1. Besides, it was found that switching processes in the irradiated crystals were much more intensive than those in the non-irradiated ones. The relaxation times decrease with rising...

  10. Development of a universal serial bus interface circuit for ion beam current integrators.

    Science.gov (United States)

    Suresh, K; Panigrahi, B K; Nair, K G M

    2007-08-01

    A universal serial bus (USB) interface circuit has been developed to enable easy interfacing of commercial as well as custom-built ion beam current integrators to personal computer (PC) based automated experimental setups. Built using the popular PIC16F877A reduced instruction set computer and a USB-universal asynchronous receiver-transmitter/first in, first out controller, DLP2232, this USB interface circuit virtually emulates the ion beam current integrators on a host PC and uses USB 2.0 protocol to implement high speed bidirectional data transfer. Using this interface, many tedious and labor intensive ion beam irradiation and characterization experiments can be redesigned into PC based automated ones with advantages of improved accuracy, rapidity, and ease of use and control. This interface circuit was successfully used in carrying out online in situ resistivity measurement of 70 keV O(+) ion irradiated tin thin films using four probe method. In situ electrical resistance measurement showed the formation of SnO(2) phase during ion implantation.

  11. Persistent sodium current drives conditional pacemaking in CA1 pyramidal neurons under muscarinic stimulation.

    Science.gov (United States)

    Yamada-Hanff, Jason; Bean, Bruce P

    2013-09-18

    Hippocampal CA1 pyramidal neurons are normally quiescent but can fire spontaneously when stimulated by muscarinic agonists. In brain slice recordings from mouse CA1 pyramidal neurons, we examined the ionic basis of this activity using interleaved current-clamp and voltage-clamp experiments. Both in control and after muscarinic stimulation, the steady-state current-voltage curve was dominated by inward TTX-sensitive persistent sodium current (I(NaP)) that activated near -75 mV and increased steeply with depolarization. In control, total membrane current was net outward (hyperpolarizing) near -70 mV so that cells had a stable resting potential. Muscarinic stimulation activated a small nonselective cation current so that total membrane current near -70 mV shifted to become barely net inward (depolarizing). The small depolarization triggers regenerative activation of I(NaP), which then depolarizes the cell from -70 mV to spike threshold. We quantified the relative contributions of I(NaP), hyperpolarization-activated cation current (I(h)), and calcium current to pacemaking by using the cell's own firing as a voltage command along with specific blockers. TTX-sensitive sodium current was substantial throughout the entire interspike interval, increasing as the membrane potential approached threshold, while both Ih and calcium current were minimal. Thus, spontaneous activity is driven primarily by activation of I(NaP) in a positive feedback loop starting near -70 mV and providing increasing inward current to threshold. These results show that the pacemaking "engine" from I(NaP) is an inherent property of CA1 pyramidal neurons that can be engaged or disengaged by small shifts in net membrane current near -70 mV, as by muscarinic stimulation.

  12. Polar-Direct-Drive Experiments on OMEGA

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, F.J.; Craxton, R.S.; Bonino, M.J.; Epstein, R.; Glebov, V.Yu.; Jacobs-Perkins, D.; Knauer, J.P.; Marozas, J.A.; McKenty, P.W.; Noyes, S.G.; Radha, P.B.; Seka, W.; Skupsky, S.; Smalyuk

    2006-06-28

    Polar direct drive (PDD), a promising ignition path for the NIF while the beams are in the indirect-drive configuration, is currently being investigated on the OMEGA laser system by using 40 beams in six rings repointed to more uniformly illuminate the target. The OMEGA experiments are being performed with standard, “warm” targets with and without the use of an equatorial “Saturn-like” toroidally shaped CH ring. Target implosion symmetry is diagnosed with framed x-ray backlighting using additional OMEGA beams and by time-integrated x-ray imaging of the stagnating core.

  13. On radio frequency current drive in the ion cyclotron range of frequencies in DEMO and large ignited plasmas

    Science.gov (United States)

    Brambilla, Marco; Bilato, Roberto

    2015-02-01

    To explore the possibility of efficient fast wave current drive in an ignited plasma in the ion cyclotron (IC) range of frequency in spite of competition from absorption by ions, we have added to the full-wave toroidal code TORIC a set of subroutines which evaluate absorption by these particles at IC harmonic resonances, using a realistic ‘slowing-down’ distribution function, and taking into account that their Larmor radius is comparable or even larger than the fast wave wavelength. The thermalized population of α-particles is not a serious competitor for power absorption as long as their number density is compatible with maintenance of ignition. By contrast, the energetic slowing down fraction, in spite of its even greater dilution, can absorb from the waves a substantial amount of power at the cyclotron resonance and its harmonics. An extensive exploration both in frequency and in toroidal wavenumbers using the parameters of one of the European versions of DEMO shows that three frequency windows exist in which damping is nevertheless predominantly on the electrons. Designing an antenna capable of shaping the launched spectrum to optimize current drive, however, will not be straightforward. Only in a narrow range when the first IC harmonic of tritium is deep inside the plasma on the high-field side of the magnetic axis, and that of deuterium and helium is still outside on the low-field side, it appears possible to achieve a satisfactory current drive efficiency with a conventional multi-strap antenna, preferentially located in the upper part of the vessel. Exploiting the other two windows at quite low and quite high frequencies is either impossible on first principles, or will demand novel ideas in antenna design.

  14. Optimal state feedback control of brushless direct-current motor drive systems based on Lyapunov stability criterion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper develops a unified methodology for a real-time speed control of brushless direct-current motor drive systems in the presence of measurement noise and load torque disturbance. First, the mathematical model and hardware structure of system is established. Next, an optimal state feed back controller using the Kalman filter state estimation technique is derived.This is followed by an adaptive control algorithm to compensate for the effects of noise and disturbance. Those two algorithms working together can provide a very-high-speed regulation and dynamic response over a wide range of operating conditions.Simulated responses are presented to highlight the effectiveness of the proposed control strategy.

  15. Berry{close_quote}s phase and a possible new topological current drive in certain weak link superconducting systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaitan, F.; Shenoy, S.R. [International Center for Theoretical Physics, P. O. Box 586, Miramare, 34100 Trieste (Italy)

    1996-06-01

    We examine the consequences of Berry{close_quote}s phase for the dynamics of Josephson junctions and junction arrays in which moving vortices are present. For both a large annular Josephson junction and a 2D junction array, Berry{close_quote}s phase produces a new current drive in the superconducting phase dynamics of these weak link systems. This Berry phase effect is shown to be physically inequivalent to a known effect in junction arrays associated with the Aharonov-Casher phase. {copyright} {ital 1996 The American Physical Society.}

  16. Gandhi and the Environmental Consequences of the Current Drive to Industrialization and Modernization.

    Science.gov (United States)

    Sinha, Rajiv K.

    1993-01-01

    Discusses Gandhi's developmental philosophy that small is beautiful in relation to current issues in ecological conservation. Issues include environmental education, economic development, rural development, natural farming, and Gandhi's philosophy among Western nations. (MDH)

  17. Complex state variable- and disturbance observer-based current controllers for AC drives

    DEFF Research Database (Denmark)

    Dal, Mehmet; Teodorescu, Remus; Blaabjerg, Frede

    2013-01-01

    , extracted by a disturbance observer and then injected into the current controller. In this study, a revised version of a disturbance observer-based controller and a well known complex variable model-based design with a single set of complex pole are compared in terms of design aspects and performance...... of the parameter and the cross-coupling effect. Moreover, it provides a better performance, smooth and low noisy operation with respect to the complex variable controller....... of the stator current. In order to improve the current control performance an alternative current control strategy was proposed previously aiming to avoid the undesired cross-coupling and non-linearities between the state variables. These effects are assumed as disturbances arisen in the closed-loop path...

  18. Current understanding of the driving mechanisms for spatiotemporal variations of atmospheric speciated mercury: a review

    Science.gov (United States)

    Mao, Huiting; Cheng, Irene; Zhang, Leiming

    2016-10-01

    Atmospheric mercury (Hg) is a global pollutant and thought to be the main source of mercury in oceanic and remote terrestrial systems, where it becomes methylated and bioavailable; hence, atmospheric mercury pollution has global consequences for both human and ecosystem health. Understanding of spatial and temporal variations of atmospheric speciated mercury can advance our knowledge of mercury cycling in various environments. This review summarized spatiotemporal variations of total gaseous mercury or gaseous elemental mercury (TGM/GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM) in various environments including oceans, continents, high elevation, the free troposphere, and low to high latitudes. In the marine boundary layer (MBL), the oxidation of GEM was generally thought to drive the diurnal and seasonal variations of TGM/GEM and GOM in most oceanic regions, leading to lower GEM and higher GOM from noon to afternoon and higher GEM during winter and higher GOM during spring-summer. At continental sites, the driving mechanisms of TGM/GEM diurnal patterns included surface and local emissions, boundary layer dynamics, GEM oxidation, and for high-elevation sites mountain-valley winds, while oxidation of GEM and entrainment of free tropospheric air appeared to control the diurnal patterns of GOM. No pronounced diurnal variation was found for Tekran measured PBM at MBL and continental sites. Seasonal variations in TGM/GEM at continental sites were attributed to increased winter combustion and summertime surface emissions, and monsoons in Asia, while those in GOM were controlled by GEM oxidation, free tropospheric transport, anthropogenic emissions, and wet deposition. Increased PBM at continental sites during winter was primarily due to local/regional coal and wood combustion emissions. Long-term TGM measurements from the MBL and continental sites indicated an overall declining trend. Limited measurements suggested TGM/GEM increasing from the

  19. A Fast Non Intercepting Linac Electron Beam Position and Current Monitor

    DEFF Research Database (Denmark)

    Hansen, Jørgen-Walther; Wille, Mads

    1982-01-01

    A non-intercepting beam monitor consisting of four detecting loops is used to determine the spatial postion and current of a pulsed beam from an electron linear accelerator. The monitor detects the magnetic field radiated by the substructure of the electron bunches created by the accelerating...... microwave. The detecting loops are interconnected two by two, by means of two coaxial hybrid junctions, the two sets positioned perpendicular to each other. By means of the two signals from the diametrically positioned detecting loops, a good spatial displacement and current monitoring sensitivity...... are achieved by subtracting one signal from the other and adding the two signals, respectively. For displacements below 2 mm from the center axis an average sensitivity of 0.5 mV/mm·mA is measured, whereas displacements more than 2 mm yields 1.3 mV / mm·mA. A sensitivity of 0.2 mV / mA in current monitoring...

  20. Current-Sensing and Voltage-Feedback Driving Method for Large-Area High-Resolution Active Matrix Organic Light Emitting Diodes

    Science.gov (United States)

    In, Hai‑Jung; Choi, Byong‑Deok; Chung, Ho‑Kyoon; Kwon, Oh‑Kyong

    2006-05-01

    There is the problem of picture quality nonuniformity due to thin film transistor (TFT) characteristic variations throughout a panel of large-area high-resolution active matrix organic light emitting diodes. The current programming method could solve this issue, but it also requires very long charging time of a data line at low gray shades. Therefore, we propose a new driving method and a pixel circuit with emission-current sensing and feedback operation in order to resolve these problems. The proposed driving method and pixel circuit successfully compensate threshold voltage and mobility variations of TFTs and overcome the data line charging problem. Simulation results show that emission current deviations of the proposed driving method are less than 1.7% with ± 10.0% mobility and ± 0.3 V threshold voltage variations of pixel-driving TFTs, which means the proposed driving method is applicable to large-area high-resolution applications.

  1. Positron annihilation and thermally stimulated current of electron beam irradiated polyetheretherketone

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Shigetaka; Shinyama, Katsuyoshi; Baba, Makoto [Hachinohe Inst. of Tech., Hachinohe, Aomori (Japan); Suzuki, Takenori

    1997-03-01

    Positron lifetime measurements were applied to electron beam irradiated poly(ether-ether-ketone). The lifetime, {tau}{sub 3}, of the ortho-positronium of unirradiated and 5 MGy irradiated specimen became rapidly longer above about 150degC. {tau}{sub 3} of 50 MGy and 100 MGy irradiated specimen was shorter than that of unirradiated one. Thermally stimulated current (TSC) decreased with increasing the dose before voltage application. In the case of voltage application, a TSC peak appeared and the peak value decreased with increased the dose. The correlation between the results of positron annihilation and TSC was investigated. (author)

  2. High-Speed Current dq PI Controller for Vector Controlled PMSM Drive

    Directory of Open Access Journals (Sweden)

    Mohammad Marufuzzaman

    2014-01-01

    Full Text Available High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA. FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era.

  3. Effect of External Magnetic Field on Critical Current for the Onset of Virtual Cathode Oscillations in Relativistic Electron Beams

    CERN Document Server

    Hramov, Alexander E; Morozov, Mikhail; Mushtakov, Alexander

    2008-01-01

    In this Letter we research the space charge limiting current value at which the oscillating virtual cathode is formed in the relativistic electron beam as a function of the external magnetic field guiding the beam electrons. It is shown that the space charge limiting (critical) current decreases with growth of the external magnetic field, and that there is an optimal induction value of the magnetic field at which the critical current for the onset of virtual cathode oscillations in the electron beam is minimum. For the strong external magnetic field the space charge limiting current corresponds to the analytical relation derived under the assumption that the motion of the electron beam is one-dimensional [High Power Microwave Sources. Artech House Microwave Library, 1987. Chapter~13]. Such behavior is explained by the characteristic features of the dynamics of electron space charge in the longitudinal and radial directions in the drift space at the different external magnetic fields.

  4. A Review of Voltage and Current Signature Diagnosis in Industrial Drives

    Directory of Open Access Journals (Sweden)

    K. Vinoth Kumar

    2011-09-01

    Full Text Available This paper presents the review of identify the different types of faults in the induction motor during online condition by using current and voltage signature analysis. Special attention is focused on the effect of both space distribution of rotor breakage and rotor dis-symmetry on the mechanism of generation of diagnosis signatures with the consideration of voltage supply unbalance and speed ripples. A comparison is made between the voltage signature analysis and current signature analysis. Keywords: Fault diagnosis, Induction motor, rotor breakage, MCSA, Motor voltage signature analysis (MVSA.

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

    Science.gov (United States)

    Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H

    2015-11-01

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

  6. Performance Evaluation of Electronic Inductor-Based Adjustable Speed Drives with Respect to Line Current Interharmonics

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Zare, Firuz;

    2017-01-01

    attractive due to its improved harmonic performance compared to a conventional ASD. In this digest, the input currents of the EI-based ASD are investigated and compared with the conventional ASDs with respect to interharmonics, which is an emerging power quality topic. First, the main causes...

  7. Nonlinear MHD simulation of current drive by multi-pulsed coaxial helicity injection in spherical torus

    Science.gov (United States)

    Kanki, Takashi; Nagata, Masayoshi; Kagei, Yasuhiro

    2011-10-01

    The dynamics of structures of magnetic field, current density, and plasma flow generated during multi-pulsed coaxial helicity injection in spherical torus is investigated by 3-D nonlinear MHD simulations. During the driven phase, the flux and current amplifications occur due to the merging and magnetic reconnection between the preexisting plasma in the confinement region and the ejected plasma from the gun region involving the n = 1 helical kink distortion of the central open flux column (COFC). Interestingly, the diamagnetic poloidal flow which tends toward the gun region is then observed due to the steep pressure gradients of the COFC generated by ohmic heating through an injection current winding around the inboard field lines, resulting in the formation of the strong poloidal flow shear at the interface between the COFC and the core region. This result is consistent with the flow shear observed in the HIST. During the decay phase, the configuration approaches the axisymmetric MHD equilibrium state without flow because of the dissipation of magnetic fluctuation energy to increase the closed flux surfaces, suggesting the generation of ordered magnetic field structure. The parallel current density λ concentrated in the COFC then diffuses to the core region so as to reduce the gradient in λ, relaxing in the direction of the Taylor state.

  8. On the merits of heating and current drive for tearing mode stabilization

    NARCIS (Netherlands)

    De Lazzari, D.; Westerhof, E.

    2009-01-01

    Neoclassical tearing modes (NTMs) are magnetohydrodynamic modes that can limit the performance of high beta discharges in a tokamak, leading eventually to a plasma disruption. A NTM is sustained by the perturbation of the 'bootstrap' current, which is a consequence of the pressure flatteni

  9. Current Transformers for GSI's KeV/u to GeV/u Ion Beams an Overview

    CERN Document Server

    Reeg, H

    2001-01-01

    At GSI's accelerator facilities ion beam intensities usually are observed and measured with various types of current transformers (CT), matched to the special requirements at their location in the machines. In the universal linear accelerator (UNILAC), and the high charge state injector (HLI) as well, active transformers with 2nd-order feedback are used, while passive pulse CTs and two DC-CTs based on the magnetic modulator principle are implemented in the heavy ion synchrotron (SIS) and the experimental storage ring (ESR). In the high energy beam transfer lines (HEBT) the particle bunch extraction/reinjection is monitored with resonant charge-integrating types. Since more than 10 years number and significance of beam current transformers for operating GSI's accelerators have grown constantly. Due to increased beam intensities following the last UNILAC upgrade, transmission monitoring and beam loss supervision with CTs have become the main tools for machine protection and radiation security purposes. All CTs ...

  10. Comparison of Output Current Ripple in Single and Dual Three-Phase Inverters for Electric Vehicle Motor Drives

    Directory of Open Access Journals (Sweden)

    Jelena Loncarski

    2015-04-01

    Full Text Available The standard solution for the traction system in battery powered electric vehicles (EVs is a two-level (2L inverter feeding a three-phase motor. A simple and effective way to achieve a three-level (3L inverter in battery-supplied electric vehicles consists of using two standard three-phase 2L inverters with the open-end winding connection of standard three-phase ac motors. The 3L inverter solution can be usefully adopted in EVs since it combines several benefits such as current ripple reduction, increment of phase motor voltage with limited voltage ratings of the two battery banks, improvement in system reliability, etc. The reduction in current ripple amplitude is particularly relevant since it is a source of electromagnetic interference and audio noise from the inverter-motor power connection cables and from the motor itself. By increasing the inverter switching frequency the ripple amplitude is reduced, but the drive efficiency decreases due to the proportionally increased switching losses. In this paper the peak-to-peak ripple amplitude of the dual-2L inverter is evaluated and compared with the corresponding ripple of the single-2L inverter, considering the same voltage and power motor ratings. The ripple analysis is carried out as a function of the modulation index to cover the whole modulation range of the inverter, and the theoretical results are verified with experimental tests carried out by an inverter-motor drive prototype.

  11. The simulation of hard x-ray images obtained during lower hybrid current drive on PBX-M

    Energy Technology Data Exchange (ETDEWEB)

    Goeler, S. von; Fishman, H.; Ignat, D. [and others

    1994-10-01

    During lower hybrid current drive on PBX-M suprathermal electrons in the 30 to 150 keV range are generated. These electrons emit hard X-ray bremsstrahlung in collisions with plasma ions; the radiation creates images in a hard X-ray pinhole camera. In order to interpret the hard X-ray images, a computer simulation code has been written, the PBXRAY code. It represents an extension of the STEVENS code that calculates the free-free and free-bound radiation for non-Maxwellian relativistic electron tail distributions. The PBXRAY code provides the chord integration in the bean-shaped plasma geometry on PBX-M and integrates over photon energy. The simulations show that the location of the suprathermal electrons can be determined with an accuracy of approximately two centimeters in the plasma. In particular, the authors analyzed discharges whose characteristic ``hollow`` images indicate off-axis LH current drive. A comparison of images taken with different absorber foils reveals that the suprathermal electrons have less than 150 keV parallel energy for the hollow discharges.

  12. Benchmarking of electron cyclotron heating and current drive codes on ITER scenarios within the European Integrated Tokamak Modelling framework

    Directory of Open Access Journals (Sweden)

    Peysson Y.

    2012-09-01

    Full Text Available Electron cyclotron resonance heating (ECRH and electron cyclotron current drive (ECCD are used to heat the plasma, to tailor the current profiles and to achieve different operating regimes of tokamak plasmas. Plasmas with ECRH/ECCD are characterized by non-thermal electrons, which cannot be described by a Maxwellian distribution. Non-thermal electrons are also generated during MHD activity, like sawteeth crashes. Quantifying the non-thermal electron distribution is therefore a key for understanding EC heated fusion plasmas. For this purpose a vertical electron cyclotron emission (V-ECE diagnostic is being installed at TCV. The diagnostic layout, the calibration, the analysis technique for data interpretation, the physics potentials and limitations are discussed.

  13. Minimization and identification of conducted emission bearing current in variable speed induction motor drives using PWM inverter

    Indian Academy of Sciences (India)

    A Ramachandran; M Channa Reddy; Ranjan Moodithaya

    2008-10-01

    The recent increase in the use of speed control of ac induction motor for variable speed drive using pulse width modulation (PWM) inverter is due to the advent of modern power electronic devices and introduction of microprocessors. There are many advantages of using ac induction motor for speed control applicatons in process and aerospace industries, but due to fast switching of the modern power electronic devices, the parasitic coupling produces undesirable effects. The undesirable effects include radiated and conducted electromagnetic interference (EMI) which adversely affect nearby computers, electronic/electrical instruments and give rise to the flow of bearing current in the induction motor. Due to the flow of bearing current in the induction motor, electrical discharge machining takes place in the inner race of the bearing which reduces the life of the bearing. In high power converters and inverters, the conducted and radiated emissions become a major concern. In this paper, identification of bearing current due to conducted emission, the measurement of bearing current in a modified induction motor and to minimize the bearing current are discussed. The standard current probe, the standard line impedance stabilization network (LISN)), the electronics interface circuits are used to measure high frequency common mode current, bearing current and to minimize the conducted noise from the system. The LISN will prevent the EMI noise entering the system from the supply source by conductive methods, at the same time prevents the EMI generated if any due to PWM, fast switching in the system, will not be allowed to enter the supply line. For comparing the results with Federal Communications Commission (FCC) and Special Committee on Radio Interference (CISPR) standards, the graphs are plotted with frequency Vs, line voltage in $dB{_\\mu} V$, common mode voltage in $dB{_\\mu} V$ and the bearing current in $dB_{\\mu} A$ with out and with minimizing circuits.

  14. 10 Orders of Magnitude Current Measurement Digitisers for the CERN Beam Loss Systems

    CERN Document Server

    Vigano, W; Dehning, B; Kwiatkowski, M; Venturini, G G; Zamantzas, C

    2014-01-01

    A wide range current digitizer card is needed for the acquisition module of the beam loss monitoring systems in the CERN Injector Complex. The fully differential frequency converter allows measuring positive and negative input currents with a resolution of 31nA in an integration window of 2μs. Increasing the integration window, the dynamic range covers 2•1010 were the upper part of the range is converted by measuring directly the voltage drop on a resistor. The key elements of this design are the fully differential integrator and the switches operated by an FPGA. The circuit is designed to avoid any dead time in the acquisition and reliability and failsafe operational considerations are main design goals. The circuit will be discussed in detail and lab and field measurements will be shown.

  15. Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Y.; jima, Y.Naka; Alcaraz-Aunion, J.L.; Brice, S.J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J.M.; Djurcic, Z.; Dore, U.; Finley, D.A.; /Kyoto U. /Barcelona, IFAE /Fermilab /MIT /Valencia U. /Columbia U. /MIT /Columbia U. /INFN, Rome /Rome U. /Fermilab /Columbia U. /INFN, Rome /Rome U.

    2010-11-01

    The SciBooNE Collaboration reports a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6-15% for the energy dependent and 3% for the energy integrated analyses. We also extract CC inclusive interaction cross sections from the observed rates, with a precision of 10-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross section ratio measurements to absolute cross section values.

  16. Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

    CERN Document Server

    jima, Y Naka; Brice, S J; Bugel, L; Catala-Perez, J; Cheng, G; Conrad, J M; Djurcic, Z; Dore, U; Finley, D A; Franke, A J; Giganti, C; Gomez-Cadenas, J J; Guzowski, P; Hanson, A; Hayato, Y; Hiraide, K; Jover-Manas, G; Karagiorgi, G; Katori, T; Kobayashi, Y K; Kobilarcik, T; Kubo, H; Kurimoto, Y; Louis, W C; Loverre, P F; Ludovici, L; Mahn, K B M; Mariani, C; Masuike, S; Matsuoka, K; McGary, V T; Metcalf, W; Mills, G B; Mitsuka, G; Miyachi, Y; Mizugashira, S; Moore, C D; Nakaya, T; Napora, R; Nienaber, P; Orme, D; Otani, M; Russell, A D; Sanchez, F; Shaevitz, M H; Shibata, T -A; Sorel, M; Stefanski, R J; Takei, H; Tanaka, H -K; Tanaka, M; Tayloe, R; Taylor, I J; Tesarek, R J; Uchida, Y; Van de Water, R; Walding, J J; Wascko, M O; White, H B; Yokoyama, M; Zeller, G P; Zimmerman, E D

    2010-01-01

    The SciBooNE Collaboration reports a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8~GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6-15% for the energy dependent and 3% for the energy integrated analyses. We also extract CC inclusive interaction cross sections from the observed rates, with a precision of 10-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross section ratio measurements to absolute cross section values.

  17. Solar cell evaluation using electron beam induced current with the large chamber scanning electron microscope

    Science.gov (United States)

    Wink, Tara; Kintzel, Edward; Marienhoff, Peter; Klein, Martin

    2012-02-01

    An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanning electron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanning electron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

  18. 10 orders of magnitude current measurement digitisers for the CERN beam loss systems

    Science.gov (United States)

    Viganò, W.; Alsdorf, M.; Dehning, B.; Kwiatkowski, M.; Venturini, G. G.; Zamantzas, C.

    2014-02-01

    A wide range current digitizer card is needed for the acquisition module of the beam loss monitoring systems in the CERN Injector Complex. The fully differential frequency converter allows measuring positive and negative input currents with a resolution of 31 nA in an integration window of 2 μs. Increasing the integration window, the dynamic range covers 21010 were the upper part of the range is converted by measuring directly the voltage drop on a resistor. The key elements of this design are the fully differential integrator and the switches operated by an FPGA. The circuit is designed to avoid any dead time in the acquisition and reliability and failsafe operational considerations are main design goals. The circuit will be discussed in detail and lab and field measurements will be shown.

  19. Calibration of eddy current carburization measurements in ethylene production tubes using ion beam analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, K J [Materials Performance Technologies, Industrial Research Ltd, PO Box 31-310, Lower Hutt (New Zealand); Trompetter, W J [Rafter Laboratory, Institute of Geological and Nuclear Sciences, PO Box 31-312, Lower Hutt (New Zealand)

    2004-02-07

    Nuclear reaction analysis using a {sup 12}C(d, p{sub 0}){sup 13}C reaction and a {sup 16}O(d, p{sub 1}){sup 17}O reaction, with 1.02 MeV deuterons in an accelerator microprobe, has been used to produce quantitative linescans of the carbon and oxygen levels in ex-service ethylene pyrolysis tubes of HPM, HK40 and Manaurite XM alloy. Particle induced x-ray emission in the ion beam microprobe and energy dispersive analysis of x-rays in a scanning electron microscope were used for linescans of the heavier elements (Cr, Ni, Fe, Si and Ti). The composition linescans were used to calibrate the response and accuracy of an eddy current probe system for measuring carburization near the inner surface of the tubes. The influence of the ferromagnetic outer oxide surface layers has been clarified. A two-dimensional ANSYS finite element model (FEM) was used for interpretation of the eddy current scans. Good correlation was obtained between the ion beam analysis results, the impedance scans and the FEM.

  20. Calibration of eddy current carburization measurements in ethylene production tubes using ion beam analysis

    Science.gov (United States)

    Stevens, K. J.; Trompetter, W. J.

    2004-02-01

    Nuclear reaction analysis using a 12C(d, p0)13C reaction and a 16O(d, p1)17O reaction, with 1.02 MeV deuterons in an accelerator microprobe, has been used to produce quantitative linescans of the carbon and oxygen levels in ex-service ethylene pyrolysis tubes of HPM, HK40 and Manaurite XM alloy. Particle induced x-ray emission in the ion beam microprobe and energy dispersive analysis of x-rays in a scanning electron microscope were used for linescans of the heavier elements (Cr, Ni, Fe, Si and Ti). The composition linescans were used to calibrate the response and accuracy of an eddy current probe system for measuring carburization near the inner surface of the tubes. The influence of the ferromagnetic outer oxide surface layers has been clarified. A two-dimensional ANSYS finite element model (FEM) was used for interpretation of the eddy current scans. Good correlation was obtained between the ion beam analysis results, the impedance scans and the FEM.

  1. Surface modification of Al-Pb alloy by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    LU You; LI Shi-long; AN Jian; LIU Yong-bing

    2006-01-01

    Al-Pb alloy was modified by high current pulsed electron beam and the microstructure, hardness and tribological characteristics were characterized by scanning electron microscopy, electronic microanalysis probe microanalysis, Knoop hardness indentation and pin-on-disc type wear testing machine. The results show that the microstructure and hardness can be greatly improved, and the modification layer consists of a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone and a transition zone followed by the substrate. The tribological properties of high current pulsed electron beam irradiated Al-Pb alloy are correspondingly improved largely. Optical observation and scanning electron microscopy analysis reveal that the low wear rate and lowest level in coefficient of friction at high load level for irradiated Al-Pb alloy are due to the formation of a lubricious tribolayer covering the worn surface, which is a mixture of Al2O3, Pb3O4 and silicate. The wear mode varies from oxidative wear at low load to film spalling at high load and, finally, adhesive wear.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-01

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

  3. Compact ASD Topologies for Single-Phase Integrated Motor Drives with Sinusoidal Input Current

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede; Thoegersen, Paul

    2005-01-01

    -density integration of the converter caused by the large size of the passive components (electrolytic capacitors and iron chokes) and vibration of the converter enclosure. This paper analyzes the implementation aspects for obtaining a compact and cost effective single-phase ASD with sinusoidal input current......, no needfor shielded cables to reduce EM1 (Electro Magnetic Inteiference), no needfor cables for the speed transducers or for other sensorsfor industrial process control (e.g. pressure). This solution is currently available up to 7.5 kW being not used in the medium and high power range due to a low....... Topologies of single-phase converters that take advantage of the motor leakage inductance are analyzed. The installed power in silicon active devices of these topologies is compared with a standard situation, showing that this will involve higher cost. As the iron core of the inductors is not suitable...

  4. Structural transitions in electron beam deposited Co–carbonyl suspended nanowires at high electrical current densities

    Directory of Open Access Journals (Sweden)

    Gian Carlo Gazzadi

    2015-06-01

    Full Text Available Suspended nanowires (SNWs have been deposited from Co–carbonyl precursor (Co2(CO8 by focused electron beam induced deposition (FEBID. The SNWs dimensions are about 30–50 nm in diameter and 600–850 nm in length. The as-deposited material has a nanogranular structure of mixed face-centered cubic (FCC and hexagonal close-packed (HCP Co phases, and a composition of 80 atom % Co, 15 atom % O and 5 atom % C, as revealed by transmission electron microscopy (TEM analysis and by energy-dispersive X-ray (EDX spectroscopy, respectively. Current (I–voltage (V measurements with current densities up to 107 A/cm2 determine different structural transitions in the SNWs, depending on the I–V history. A single measurement with a sudden current burst leads to a polycrystalline FCC Co structure extended over the whole wire. Repeated measurements at increasing currents produce wires with a split structure: one half is polycrystalline FCC Co and the other half is graphitized C. The breakdown current density is found at 2.1 × 107 A/cm2. The role played by resistive heating and electromigration in these transitions is discussed.

  5. Structural transitions in electron beam deposited Co-carbonyl suspended nanowires at high electrical current densities.

    Science.gov (United States)

    Gazzadi, Gian Carlo; Frabboni, Stefano

    2015-01-01

    Suspended nanowires (SNWs) have been deposited from Co-carbonyl precursor (Co2(CO)8) by focused electron beam induced deposition (FEBID). The SNWs dimensions are about 30-50 nm in diameter and 600-850 nm in length. The as-deposited material has a nanogranular structure of mixed face-centered cubic (FCC) and hexagonal close-packed (HCP) Co phases, and a composition of 80 atom % Co, 15 atom % O and 5 atom % C, as revealed by transmission electron microscopy (TEM) analysis and by energy-dispersive X-ray (EDX) spectroscopy, respectively. Current (I)-voltage (V) measurements with current densities up to 10(7) A/cm(2) determine different structural transitions in the SNWs, depending on the I-V history. A single measurement with a sudden current burst leads to a polycrystalline FCC Co structure extended over the whole wire. Repeated measurements at increasing currents produce wires with a split structure: one half is polycrystalline FCC Co and the other half is graphitized C. The breakdown current density is found at 2.1 × 10(7) A/cm(2). The role played by resistive heating and electromigration in these transitions is discussed.

  6. Magnetic ripple and the modeling of lower-hybrid current drive in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Arslanbekov, R.; Basiuk, V.; Carrasco, J.; Litaudon, X.; Moreau, D. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Bizarro, J.P. [Instituto Superior Tecnico, Lisbon (Portugal). Lab. de Quimica Organica

    1996-01-01

    Using ray-tracing, a detailed investigation of the lower hybrid (LH) wave propagation in presence of toroidal magnetic field ripple is presented. By coupling ray tracing with a one-dimensional relativistic Fokker-Planck code, simulations of LH experiments have been performed for the Tore Supra tokamak. Taking into account magnetic ripple in LH simulations, a better agreement is found between numerical predictions and experimental observations, such as non-thermal Bremsstrahlung emission, current profile, ripple-induced power losses in local magnetic mirrors, when plasma conditions correspond to the ` `few passes` regime. (author). 47 refs.

  7. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Hughes, Thomas [Los Alamos National Laboratory; Anaya, Richard [LLNL; Caporaso, George [LLNL; Chambers, Frank [LLNL; Chen, Yu - Jiuan [LLNL; Falabella, Steve [LLNL; Guethlein, Gary [LLNL; Raymond, Brett [LLNL; Richardson, Roger [LLNL; Trainham, C [NSTEC/STL; Watson, Jim [LLNL; Weir, John [LLNL; Genoni, Thomas [VOSS; Toma, Carsten [VOSS

    2009-01-01

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 {micro}s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  8. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, O. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Degen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Lambiase, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meng, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rao, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Sheehy, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pietz, J. [Transfer Engineering and Manufacturing, Inc., Fremont, CA (United States); Ackeret, M. [Transfer Engineering and Manufacturing, Inc., Fremont, CA (United States); Yeckel, C. [Stangenes Industries, Palo Alto, CA (United States); Miller, R. [Stangenes Industries, Palo Alto, CA (United States); Dobrin, E. [Stangenes Industries, Palo Alto, CA (United States); Thompson, K. [Stangenes Industries, Palo Alto, CA (United States)

    2015-05-03

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  9. A fresh look at electron cyclotron current drive power requirements for stabilization of tearing modes in ITER

    Science.gov (United States)

    La Haye, R. J.

    2015-12-01

    ITER is an international project to design and build an experimental fusion reactor based on the "tokamak" concept. ITER relies upon localized electron cyclotron current drive (ECCD) at the rational safety factor q=2 to suppress or stabilize the expected poloidal mode m=2, toroidal mode n=1 neoclassical tearing mode (NTM) islands. Such islands if unmitigated degrade energy confinement, lock to the resistive wall (stop rotating), cause loss of "H-mode" and induce disruption. The International Tokamak Physics Activity (ITPA) on MHD, Disruptions and Magnetic Control joint experiment group MDC-8 on Current Drive Prevention/Stabilization of Neoclassical Tearing Modes started in 2005, after which assessments were made for the requirements for ECCD needed in ITER, particularly that of rf power and alignment on q=2 [1]. Narrow well-aligned rf current parallel to and of order of one percent of the total plasma current is needed to replace the "missing" current in the island O-points and heal or preempt (avoid destabilization by applying ECCD on q=2 in absence of the mode) the island [2-4]. This paper updates the advances in ECCD stabilization on NTMs learned in DIII-D experiments and modeling during the last 5 to 10 years as applies to stabilization by localized ECCD of tearing modes in ITER. This includes the ECCD (inside the q=1 radius) stabilization of the NTM "seeding" instability known as sawteeth (m/n=1/1) [5]. Recent measurements in DIII-D show that the ITER-similar current profile is classically unstable, curvature stabilization must not be neglected, and the small island width stabilization effect from helical ion polarization currents is stronger than was previously thought [6]. The consequences of updated assumptions in ITER modeling of the minimum well-aligned ECCD power needed are all-in-all favorable (and well-within the ITER 24 gyrotron capability) when all effects are included. However, a "wild card" may be broadening of the localized ECCD by the presence of

  10. Heating and current drive requirements for ideal MHD stability and ITB sustainment in ITER steady state scenarios

    Science.gov (United States)

    Poli, Francesca

    2012-10-01

    Steady state scenarios envisaged for ITER aim at optimizing the bootstrap current, while maintaining sufficient confinement and stability to provide the necessary fusion yield. Non-inductive scenarios will need to operate with Internal Transport Barriers (ITBs) in order to reach adequate fusion gain at typical currents of 9 MA. However, the large pressure gradients associated with ITBs in regions of weak or negative magnetic shear can be conducive to ideal MHD instabilities in a wide range of βN, reducing the no-wall limit. Scenarios are established as relaxed flattop states with time-dependent transport simulations with TSC [1]. Fully non-inductive configurations with current in the range of 7-10 MA and various heating mixes (NB, EC, IC and LH) have been studied against variations of the pressure profile peaking and of the Greenwald fraction. It is found that stable equilibria have qmin> 2 and moderate ITBs at 2/3 of the minor radius [2]. The ExB flow shear from toroidal plasma rotation is expected to be low in ITER, with a major role in the ITB dynamics being played by magnetic geometry. Combinations of H&CD sources that maintain reverse or weak magnetic shear profiles throughout the discharge and ρ(qmin)>=0.5 are the focus of this work. The ITER EC upper launcher, designed for NTM control, can provide enough current drive off-axis to sustain moderate ITBs at mid-radius and maintain a non-inductive current of 8-9MA and H98>=1.5 with the day one heating mix. LH heating and current drive is effective in modifying the current profile off-axis, facilitating the formation of stronger ITBs in the rampup phase, their sustainment at larger radii and larger bootstrap fraction. The implications for steady state operation and fusion performance are discussed.[4pt] [1] Jardin S.C. et al, J. Comput. Phys. 66 (1986) 481[0pt] [2] Poli F.M. et al, Nucl. Fusion 52 (2012) 063027.

  11. A fresh look at electron cyclotron current drive power requirements for stabilization of tearing modes in ITER

    Energy Technology Data Exchange (ETDEWEB)

    La Haye, R. J., E-mail: lahaye@fusion.gat.com [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

    2015-12-10

    ITER is an international project to design and build an experimental fusion reactor based on the “tokamak” concept. ITER relies upon localized electron cyclotron current drive (ECCD) at the rational safety factor q=2 to suppress or stabilize the expected poloidal mode m=2, toroidal mode n=1 neoclassical tearing mode (NTM) islands. Such islands if unmitigated degrade energy confinement, lock to the resistive wall (stop rotating), cause loss of “H-mode” and induce disruption. The International Tokamak Physics Activity (ITPA) on MHD, Disruptions and Magnetic Control joint experiment group MDC-8 on Current Drive Prevention/Stabilization of Neoclassical Tearing Modes started in 2005, after which assessments were made for the requirements for ECCD needed in ITER, particularly that of rf power and alignment on q=2 [1]. Narrow well-aligned rf current parallel to and of order of one percent of the total plasma current is needed to replace the “missing” current in the island O-points and heal or preempt (avoid destabilization by applying ECCD on q=2 in absence of the mode) the island [2-4]. This paper updates the advances in ECCD stabilization on NTMs learned in DIII-D experiments and modeling during the last 5 to 10 years as applies to stabilization by localized ECCD of tearing modes in ITER. This includes the ECCD (inside the q=1 radius) stabilization of the NTM “seeding” instability known as sawteeth (m/n=1/1) [5]. Recent measurements in DIII-D show that the ITER-similar current profile is classically unstable, curvature stabilization must not be neglected, and the small island width stabilization effect from helical ion polarization currents is stronger than was previously thought [6]. The consequences of updated assumptions in ITER modeling of the minimum well-aligned ECCD power needed are all-in-all favorable (and well-within the ITER 24 gyrotron capability) when all effects are included. However, a “wild card” may be broadening of the localized

  12. Effective variable switching point predictive current control for ac low-voltage drives

    Science.gov (United States)

    Stolze, Peter; Karamanakos, Petros; Kennel, Ralph; Manias, Stefanos; Endisch, Christian

    2015-07-01

    This paper presents an effective model predictive current control scheme for induction machines driven by a three-level neutral point clamped inverter, called variable switching point predictive current control. Despite the fact that direct, enumeration-based model predictive control (MPC) strategies are very popular in the field of power electronics due to their numerous advantages such as design simplicity and straightforward implementation procedure, they carry two major drawbacks. These are the increased computational effort and the high ripples on the controlled variables, resulting in a limited applicability of such methods. The high ripples occur because in direct MPC algorithms the actuating variable can only be changed at the beginning of a sampling interval. A possible remedy for this would be to change the applied control input within the sampling interval, and thus to apply it for a shorter time than one sample. However, since such a solution would lead to an additional overhead which is crucial especially for multilevel inverters, a heuristic preselection of the optimal control action is adopted to keep the computational complexity at bay. Experimental results are provided to verify the potential advantages of the proposed strategy.

  13. Laser-driven Beat-Wave Current Drive in Dense Plasmas with Demo on CTIX

    Science.gov (United States)

    Liu, Fei; Horton, Robert; Hwang, David; Zhu, Ben; Evans, Russell; Hong, Sean; Hsu, Scott

    2010-11-01

    The ability to remotely generate plasma current in dense plasmas hanging freely in vacuum in voluminous amount without obstruction to diagnostics will greatly enhance our ability to study the physics of high energy density plasmas in strong magnetic fields. Plasma current can be generated through nonlinear beat-wave process by launching two intense electromagnetic waves into unmagnetized plasma. Beat-wave acceleration of electrons has been demonstrated in a low-density plasma using microwaves [1]. The proposed PLX experimental facility presently under construction at Los Alamos offers the opportunity to test the method at a density level scalable to the study of HED plasmas. For PLX beat-wave experiments, CO2 lasers will be used as pump waves due to their high power and tunability. For a typical PLX density ne=10^17cm-3, two CO2 lasers can be separately tuned to 9P(28) and 10P(20) to match the 2.84THz plasma frequency. The beat-wave demo experiment will be conducted on CTIX. The laser arrangement is being converted to two independent single lasers. Frequency-tuning methods, optics focusing system and diagnostics system will be discussed. The laser measurements and results of synchronization of two lasers will be presented, and scaling to PLX experiments will be given. [1] Rogers, J. H. and Hwang, D. Q., PRL. v68 p3877 (1992).

  14. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    Science.gov (United States)

    Pace, D. C.; Collins, C. S.; Crowley, B.; Grierson, B. A.; Heidbrink, W. W.; Pawley, C.; Rauch, J.; Scoville, J. T.; Van Zeeland, M. A.; Zhu, Y. B.; The DIII-D Team

    2017-01-01

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak (Luxon 2002 Nucl. Fusion 42 614). Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. Developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.

  15. Heating, current drive and confinement regimes with the JET ICRH and LHCD systems

    DEFF Research Database (Denmark)

    Jacquinot, J.; Adams, J.M.; Altmann, H.;

    1991-01-01

    During its 1990 operation, 2 large RF systems were available on JET. The Ion Cyclotron Resonance Heating (ICRH) system was equipped with new beryllium screens and with feedback matching systems. Specific impurities generated by ICRH were reduced to negligible levels even in the most stringent H......-mode conditions. A maximum power of 22 MW was coupled to L-mode plasmas. High quality H-modes (tau-E greater-than-or-equal-to 2.5 tau-EG) were achieved using dipole phasing. A new high confinement mode was discovered. It combines the properties of the H-mode regime to the low central diffusivities obtained....... Paradoxically, LHCD induces central heating particularly in combination with ICRH. Finally we present the first observations of the synergistic acceleration of fast electrons by Transit Time Magnetic Pumping (TTMP) (from ICRH) and Electron Landau Damping (ELD) (from LHCD). The synergism generates TTMP current...

  16. Electron Drift Speed And Current-Induced Drive Torques On A Domain Wall

    Science.gov (United States)

    Berger, Luc

    2009-03-01

    It has become fashionable to describe [1] current-induced torques on a DW in terms of an electron drift speed u = - P*j*muB/e*M where muB is the Bohr magneton and M the saturation magnetization. While appropriate for adiabatic torques, this quantity u is misleading and not the best choice in the case of non-adiabatic torques. For example, it leads [2] to beta not equal to alpha, where beta represents the intensity of the non-adiabatic torque, and alpha is the damping parameter. By writing equations of motion for conduction- electron spins in a moving frame where the electron gas is at rest, we find [3] a direct relation between damping and non- adiabatic torques. The correct electron drift speed turns out to be the speed of the frame, and is v = P*j/(n*q) where n and q are the carrier density and charge. It is related to the ordinary Hall constant R0 by v P*R0*j. After substituting v for u in the expression of the non-adiabatic torque, we find that beta = alpha holds now. Because v is larger than u in Permalloy, it can explain better the large current-induced DW speeds found [4] experimentally. In materials where R0> 0 and the carriers are dominantly hole-like, v and u have opposite signs, leading to different predictions for the sense of DW motion. We discuss examples of such materials. 1. G. Tatara and H. Kohno, Phys. Rev. Lett. 92, 086601 (2004). 2. H. Kohno et al., J. Phys. Soc. Japan, 75, 113706 (2006). 3. L. Berger, Phys. Rev. B 75, 174401 (2007). 4. M. Hayashi et al., Phys. Rev. Lett. 98, 037204 (2007).

  17. FPGA-based voltage and current dual drive system for high frame rate electrical impedance tomography.

    Science.gov (United States)

    Khan, Shadab; Manwaring, Preston; Borsic, Andrea; Halter, Ryan

    2015-04-01

    Electrical impedance tomography (EIT) is used to image the electrical property distribution of a tissue under test. An EIT system comprises complex hardware and software modules, which are typically designed for a specific application. Upgrading these modules is a time-consuming process, and requires rigorous testing to ensure proper functioning of new modules with the existing ones. To this end, we developed a modular and reconfigurable data acquisition (DAQ) system using National Instruments' (NI) hardware and software modules, which offer inherent compatibility over generations of hardware and software revisions. The system can be configured to use up to 32-channels. This EIT system can be used to interchangeably apply current or voltage signal, and measure the tissue response in a semi-parallel fashion. A novel signal averaging algorithm, and 512-point fast Fourier transform (FFT) computation block was implemented on the FPGA. FFT output bins were classified as signal or noise. Signal bins constitute a tissue's response to a pure or mixed tone signal. Signal bins' data can be used for traditional applications, as well as synchronous frequency-difference imaging. Noise bins were used to compute noise power on the FPGA. Noise power represents a metric of signal quality, and can be used to ensure proper tissue-electrode contact. Allocation of these computationally expensive tasks to the FPGA reduced the required bandwidth between PC, and the FPGA for high frame rate EIT. In 16-channel configuration, with a signal-averaging factor of 8, the DAQ frame rate at 100 kHz exceeded 110 frames s (-1), and signal-to-noise ratio exceeded 90 dB across the spectrum. Reciprocity error was found to be for frequencies up to 1 MHz. Static imaging experiments were performed on a high-conductivity inclusion placed in a saline filled tank; the inclusion was clearly localized in the reconstructions obtained for both absolute current and voltage mode data.

  18. Pile Driving

    Science.gov (United States)

    1987-01-01

    Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

  19. First simultaneous measurement of sextupolar and octupolar resonance driving terms in a circular accelerator from turn-by-turn beam position monitors data

    CERN Document Server

    Franchi, A; Ewald, F; Bec, G Le; Scheidt, K B

    2014-01-01

    Beam lifetime in storage rings and colliders is affected by, among other effects, lattice nonlinearities. Their control are of great benefit to the dynamic aperture of an accelerator, whose enlargement leads in general to more efficient injection and longer lifetime. This article describes a procedure to evaluate and correct unwanted nonlinearities by using turn-by-turn beam position monitor data, which is an evolution of previous works on the resonance driving terms (RDTs). Effective sextupole magnetic errors and tilts at the ESRF electron storage ring are evaluated and corrected (when possible) by using this technique. For the first time, also octupolar RDTs could be measured and used to define an octupolar model for the main quadrupoles. Most of the deviations from the model observed in the sextupolar RDTs of the ESRF storage ring turned out to be generated by focusing errors rather than by sextupole errors. These results could be achieved thanks to new analytical formulas describing the harmonic content o...

  20. Lower Hybrid Current Drive and Heating for the National Transport Code Collaboration

    Science.gov (United States)

    Ignat, D. W.; Jardin, S. C.; McCune, D. C.; Valeo, E. J.

    2000-10-01

    The Lower hybrid Simulation Code LSC was originally written as a subroutine to the Toroidal Simulation Code TSC (Jardin, Pomphrey, Kessel, et al) and subsequently ported to a subroutine of TRANSP. Modifications to simplify the use of the LSC both as a callable module, and also independently of larger transport codes, and improve the documentation have been undertaken with the goal of installing LSC in the NTCC library. The physical model, which includes ray tracing from a Brambilla spectrum, 1D Fokker-Planck development of the electron distribution, the Karney-Fisch treatment of the electric field, heuristic diffusion of current and power and wall scattering, has not been changed. The computational approach is to suppress or remove from the control of the user numerical parameters such as step size and number of iterations while changing some code to be extremely stable in varied conditions. Essential graphics are now output as gnuplot commands and data for off-line post processing, but the original outputs to sglib are retained as an option. Examples of output are shown.

  1. Surface treatment of 0.20% C carbon steel by high-current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    XU Guo-cheng; FU Shi-you; GUAN Qing-feng

    2006-01-01

    A high-current pulsed electron beam(HCPEB) generated on the system of Nadezhda-2 was applied to improve the microstructure and performance of 0.20% C low carbon steel. Surface layers of the samples bombarded by explosive electron beam at different pulses was observed by using electron microscopy. The physical model of the thermal-stress process and related modification mechanism as a result of HCPEB irradiation was also investigated. After HCPEB post treatments, obvious changes in microstructure and significant hardening occur in the depth of 200-250 μm from the surface after HCPEB irradiation. Rapid heating and subsequent rapid solidification induce heavy plastic deformation, which results in that the laminated structure of pearlite is substituted by dispersive rounded-like cementites in the near-surface. The effect of HCPEB treatment can reach more than 500 m depth from the surface. The original crystalline structure is changed to a different degree that grows with the numbers of bombardment, and in the surface layer amorphous states and nanocrystaline structures consisting of grains of γ-phase and cementite are found. The violent stress induced by HCPEB irradiation is the origin of the nanostructured and amorphous structure formation.

  2. Model of convection mass transfer in titanium alloy at low energy high current electron beam action

    Science.gov (United States)

    Sarychev, V. D.; Granovskii, A. Yu; Nevskii, S. A.; Konovalov, S. V.; Gromov, V. E.

    2017-01-01

    The convection mixing model is proposed for low-energy high-current electron beam treatment of titanium alloys, pre-processed by heterogeneous plasma flows generated via explosion of carbon tape and powder TiB2. The model is based on the assumption vortices in the molten layer are formed due to the treatment by concentrated energy flows. These vortices evolve as the result of thermocapillary convection, arising because of the temperature gradient. The calculation of temperature gradient and penetration depth required solution of the heat problem with taking into account the surface evaporation. However, instead of the direct heat source the boundary conditions in phase transitions were changed in the thermal conductivity equation, assuming the evaporated material takes part in the heat exchange. The data on the penetration depth and temperature distribution are used for the thermocapillary model. The thermocapillary model embraces Navier-Stocks and convection heat transfer equations, as well as the boundary conditions with the outflow of evaporated material included. The solution of these equations by finite elements methods pointed at formation of a multi-vortices structure when electron-beam treatment and its expansion over new zones of material. As the result, strengthening particles are found at the depth exceeding manifold their penetration depth in terms of the diffusion mechanism.

  3. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A' aisah [Malaysian Nuclear Agency (Nuclear Malaysia), Bangi 43000 Kajang Selangor (Malaysia); Ahmad, Pauzi [Universiti Kebangsaan Malaysia, 43600 UKM, Bangi Selangor (Malaysia)

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  4. A particle-core-MD model for intrabeam scattering and halo formation in high current beams in a FODO channel

    CERN Document Server

    Uhlmann, N; Comunian, M; Pisent, A

    2002-01-01

    An essential problem for the successful operation of high current linear ion accelerators is the control of beam losses due to halo particles. As a possible mechanism for the formation of such a halo we concentrate on the interplay between intrabeam scattering (IBS) and the incidence of particles which are driven to high amplitudes by resonances with the nonlinear space charge fields of a mismatched beam. Since a fully microscopic numerical treatment including all the mutual Coulomb interactions between the beam ions requires much too high computational effort, we developed an approximative method. These particle-core-molecular-dynamics (PCMD) simulations suitably join the mean-field description of the time evolution of the beam in framework of the envelope equations and a microscopic calculation of the Coulomb interactions between pseudo-particles with a renormalized charge. With this method we studied matched and mismatched continuous KV-beams in a FODO channel. In first simulation runs we observed a signif...

  5. A modified beam-to-earth transformation to measure short-wavelength internal waves with an acoustic Doppler current profiler

    Science.gov (United States)

    Scotti, A.; Butman, B.; Beardsley, R.C.; Alexander, P.S.; Anderson, S.

    2005-01-01

    The algorithm used to transform velocity signals from beam coordinates to earth coordinates in an acoustic Doppler current profiler (ADCP) relies on the assumption that the currents are uniform over the horizontal distance separating the beams. This condition may be violated by (nonlinear) internal waves, which can have wavelengths as small as 100-200 m. In this case, the standard algorithm combines velocities measured at different phases of a wave and produces horizontal velocities that increasingly differ from true velocities with distance from the ADCP. Observations made in Massachusetts Bay show that currents measured with a bottom-mounted upward-looking ADCP during periods when short-wavelength internal waves are present differ significantly from currents measured by point current meters, except very close to the instrument. These periods are flagged with high error velocities by the standard ADCP algorithm. In this paper measurements from the four spatially diverging beams and the backscatter intensity signal are used to calculate the propagation direction and celerity of the internal waves. Once this information is known, a modified beam-to-earth transformation that combines appropriately lagged beam measurements can be used to obtain current estimates in earth coordinates that compare well with pointwise measurements. ?? 2005 American Meteorological Society.

  6. THEORY OF ELECTROMAGNETIC DRIVE WITH ELEMENTARY PARTICLES CURRENT AND VACUUM POLARIZATION

    Directory of Open Access Journals (Sweden)

    Trunev A. P.

    2016-01-01

    Full Text Available The article discusses a model of rocket motor of electromagnetic type, consisting of a source of electromagnetic radio frequency oscillations and the conical cavity, in which electromagnetic waves are excited. We have created a multi-dimensional transient numerical model describing the process of establishing electromagnetic oscillations in the resonator, taking into account the finite conductivity of the walls. Separately, the standing waves in the cavity with conducting walls have been simulated. It is shown that the oscillations mode in the conducting resonator different from that in an ideal resonator, both in a case of steady and unsteady waves. We have built a dynamic model taking into account the thermal conductivity and electrical conductivity of the walls, waves and particles emission and vacuum polarization. We have also developed a dynamic model enables to optimize a thrust force on a considerable number of parameters without the involvement of the hypotheses about the physics of the phenomenon. We run the optimization of the operating parameters of the device, namely by the excitation frequency, the frequency of the modulating signal, the magnitude of heat losses of electromagnetic energy by thermal radiation in the IR spectrum, the parameters of forced heat transfer and the temperature dependence of the resistance of the material of the cavity walls. It is found that the pulse modulation greatly improves the efficiency of conversion of electromagnetic energy into thrust. The mechanism of formation of traction, adjusting the metrics of space-time, the current contribution of elementary particles, the Yang-Mills and electromagnetic fields is proposed. It is shown that the contribution of the elementary particles in the thrust force is proportional to the electrical conductivity of the system multiplied by Abraham force

  7. Sawtooth control using electron cyclotron current drive in the presence of energetic particles in high performance ASDEX Upgrade plasmas

    CERN Document Server

    Chapman, I T; Maraschek, M; McCarthy, P J; Tardini, G

    2013-01-01

    Sawtooth control using steerable electron cyclotron current drive (ECCD) has been demonstrated in ASDEX Upgrade plasmas with a significant population of energetic ions in the plasma core and long uncontrolled sawtooth periods. The sawtooth period is found to be minimised when the ECCD resonance is swept to just inside the q = 1 surface. By utilising ECCD inside q = 1 for sawtooth control, it is possible to avoid the triggering of neoclassical tearing modes, even at significnatly higher pressure than anticipated in the ITER baseline scenario. Operation at 25% higher normalised pressure has been achieved when only modest ECCD power is used for sawtooth control compared to identical discharges without sawtooth control when neo-classical tearing modes are triggered by the sawteeth. Modelling suggests that the destabilisation arising from the change in the local magnetic shear caused by the ECCD is able to compete with the stabilising influence of the energetic particles inside the q = 1 surface.

  8. Effect of longitudinal applied magnetic field on the self-pinched critical current in intense electron beam diode

    Institute of Scientific and Technical Information of China (English)

    Liu Guo-Zhi; Huang Wen-Hua; Shao Hao; Xiao Ren-Zhen

    2006-01-01

    The effect of applied longitudinal magnetic field on the self-pinched critical current in the intense electron beam diode is discussed. The self-pinched critical current is derived and its validity is tested by numerical simulations. The results shows that an applied longitudinal magnetic field tends to increase the self-pinched critical current. Without the effect of anode plasma, the maximal diode current approximately equals the self-pinched critical current with the longitudinal magnetic field applied; when self-pinched occurs, the diode current approaches the self-pinched critical current.

  9. Current status of dental caries diagnosis using cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young Seok; Ahn, Jin Soo; Kwon, Ho Beom; Lee, Seung Pyo [School of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    2011-06-15

    The purpose of this article is to review the current status of dental caries diagnosis using cone beam computed tomography (CBCT). An online PubMed search was performed to identify studies on caries research using CBCT. Despite its usefulness, there were inherent limitations in the detection of caries lesions through conventional radiograph mainly due to the two-dimensional (2D) representation of caries lesions. Several efforts were made to investigate the three-dimensional (3D) image of lesion, only to gain little popularity. Recently, CBCT was introduced and has been used for diagnosis of caries in several reports. Some of them maintained the superiority of CBCT systems, however it is still under controversies. The CBCT systems are promising, however they should not be considered as a primary choice of caries diagnosis in everyday practice yet. Further studies under more standardized condition should be performed in the near future.

  10. Microstructure Analysis of HPb59-1 Brass Induced by High Current Pulsed Electron Beam

    Science.gov (United States)

    Lyu, Jike; Gao, Bo; Hu, Liang; Lu, Shuaidan; Tu, Ganfeng

    2016-08-01

    In this paper, the effects of high current pulsed electron beam (HCPEB) on the microstructure evolution of casting HPb59-1 (Cu 57.1 mass%, Pb 1.7 mass% and Zn balance) alloy were investigated. The results showed a "wavy" surface which was formed with Pb element existing in the forms of stacking block and microparticles on the top surface layer after treatment. Nanocrystalline structures including Pb grains and two phases (α and β) were formed on the top remelted layer and their sizes were all less than 100 nm. The disordered β phase was generated in the surface layer after HCPEB treatment, which is beneficial for the improvement of surface properties. Meanwhile, there was a large residual stress on the alloy surface, along with the appearance of microcracks, and the preferred orientations of grains also changed.

  11. Characteristics of electron cyclotron resonance plasma formed by lower hybrid current drive grill antenna

    Indian Academy of Sciences (India)

    P K Sharma; S L Rao; K Mishra; R G Trivedi; D Bora

    2008-03-01

    A 3.7 GHz system, which is meant for LHCD experiments on ADITYA tokamak, is used for producing ECR discharge. The ECR discharge is produced by setting the appropriate resonance magnetic field of 0.13 T, with hydrogen at a fill pressure of about 5 × 10-5 Torr. The RF powe r, up to 10 kW (of which ∼ 50% is reflected back), with a typical pulse length of 50 ms, is injected into the vacuum chamber of the ADITYA tokamak by a LHCD grill antenna and is used for plasma formation. The average coupled RF power density (the RF power/a typical volume of the plasma) is estimated to be ∼ 5 kW/m3. When the ECR appears inside the tokamak chamber for the given pumping frequency ( = 3.7 GHz) a plasma with a density () ∼ 4 × 1016 m-3 and electron temperature ∼ 8 eV is produced. The density and temperature during the RF pulse are measured by sets of Langmuir probes, located toroidally, on either side of the antenna. signals are also monitored to detect ionization. An estimate of density and temperature based on simple theoretical calculation agrees well with our experimental measurements. The plasma produced by the above mechanism is further used to characterize the ECR-assisted low voltage Ohmic start-up discharges. During this part of the experiments, Ohmic plasma is formed using capacitor banks. The plasma loop voltage is gradually decreased, till the discharge ceases to form. The same is repeated in the presence of ECR-formed plasma (RF pre-ionization), formed 10 ms prior to the loop voltage. We have observed that (with LHCD-induced) ECR-assisted Ohmic start-up discharges is reliably and repeatedly obtained with reduced loop voltage requirement and breakdown time decreases substantially. The current ramp-up rates also decrease with reduced loop voltage operation. These studies established that ECR plasma formed with LHCD system exhibits similar characteristics as reported earlier by dedicated ECR systems. This experiment also addresses the issue of whether ECR plasma

  12. Historical processes and contemporary ocean currents drive genetic structure in the seagrass Thalassia hemprichii in the Indo-Australian Archipelago.

    Science.gov (United States)

    Hernawan, Udhi E; van Dijk, Kor-Jent; Kendrick, Gary A; Feng, Ming; Biffin, Edward; Lavery, Paul S; McMahon, Kathryn

    2017-02-01

    Understanding spatial patterns of gene flow and genetic structure is essential for the conservation of marine ecosystems. Contemporary ocean currents and historical isolation due to Pleistocene sea level fluctuations have been predicted to influence the genetic structure in marine populations. In the Indo-Australian Archipelago (IAA), the world's hotspot of marine biodiversity, seagrasses are a vital component but population genetic information is very limited. Here, we reconstructed the phylogeography of the seagrass Thalassia hemprichii in the IAA based on single nucleotide polymorphisms (SNPs) and then characterized the genetic structure based on a panel of 16 microsatellite markers. We further examined the relative importance of historical isolation and contemporary ocean currents in driving the patterns of genetic structure. Results from SNPs revealed three population groups: eastern Indonesia, western Indonesia (Sunda Shelf) and Indian Ocean; while the microsatellites supported five population groups (eastern Indonesia, Sunda Shelf, Lesser Sunda, Western Australia and Indian Ocean). Both SNPs and microsatellites showed asymmetrical gene flow among population groups with a trend of southwestward migration from eastern Indonesia. Genetic diversity was generally higher in eastern Indonesia and decreased southwestward. The pattern of genetic structure and connectivity is attributed partly to the Pleistocene sea level fluctuations modified to a smaller level by contemporary ocean currents.

  13. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shen [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Cai, Jie [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Engineering Institute of Advanced Manufacturing and Modern Equipment Technology, Jiangsu University, Zhenjiang 212013 (China); Lv, Peng; Zhang, Conglin; Huang, Wei [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng, E-mail: guanqf@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-09-01

    Highlights: • Zirconium-702 irradiated by high current pulsed electron beam was investigated. • Irradiated surface was melted and martensitic phase transformation occurred. • High density dislocations and deformation twins were formed in melted layer. • Micropores and ultrafine structures were also obtained on the irradiated surface. • Microhardness and corrosion resistance were improved after HCPEB irradiation. - Abstract: The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO{sub 3} solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  14. High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation.

    Science.gov (United States)

    Navas, F J; Alcántara, R; Fernández-Lorenzo, C; Martín-Calleja, J

    2010-03-01

    A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

  15. The current status of cone beam computed tomography imaging in orthodontics.

    Science.gov (United States)

    Kapila, S; Conley, R S; Harrell, W E

    2011-01-01

    Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. Currently available information from studies using CBCT can be organized into five broad categories: 1, the assessment of CBCT technology; 2, its use in craniofacial morphometric analyses; 3, incidental and missed findings; 4, analysis of treatment outcomes; and 5, efficacy of CBCT in diagnosis and treatment planning. The findings in these topical areas are summarized, followed by current indications and protocols for the use of CBCT in specific cases. Despite the increasing popularity of CBCT in orthodontics, and its advantages over routine radiography in specific cases, the effects of information derived from these images in altering diagnosis and treatment decisions has not been demonstrated in several types of cases. It has therefore been recommended that CBCT be used in select cases in which conventional radiography cannot supply satisfactory diagnostic information; these include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and for planning orthognathic surgery. The need to image other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations.

  16. The current status of cone beam computed tomography imaging in orthodontics

    Science.gov (United States)

    Kapila, S; Conley, R S; Harrell, W E

    2011-01-01

    Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. Currently available information from studies using CBCT can be organized into five broad categories: 1, the assessment of CBCT technology; 2, its use in craniofacial morphometric analyses; 3, incidental and missed findings; 4, analysis of treatment outcomes; and 5, efficacy of CBCT in diagnosis and treatment planning. The findings in these topical areas are summarized, followed by current indications and protocols for the use of CBCT in specific cases. Despite the increasing popularity of CBCT in orthodontics, and its advantages over routine radiography in specific cases, the effects of information derived from these images in altering diagnosis and treatment decisions has not been demonstrated in several types of cases. It has therefore been recommended that CBCT be used in select cases in which conventional radiography cannot supply satisfactory diagnostic information; these include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and for planning orthognathic surgery. The need to image other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations. PMID:21159912

  17. Design and characterization of the annular cathode high current pulsed electron beam source for circular components

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei; Wang, Langping, E-mail: aplpwang@hit.edu.cn; Wang, Xiaofeng

    2016-08-01

    Highlights: • An annular cathode for HCPEB irradiation of circular components was designed. • The processing window for the annular cathode is obtained. • Irradiation thickness uniformity along the circumferential direction exceeds 90%. - Abstract: In order to irradiate circular components with high current pulsed electron beam (HCPEB), an annular cathode based on carbon fiber bunches was designed and fabricated. Using an acceleration voltage of 25 kV, the maximum pulsed irradiation current and energy of this annular cathode can reach 7.9 kA and 300 J, respectively. The irradiation current density distribution of the annular cathode HCPEB source measured along the circumferential direction shows that the annular cathode has good emission uniformity. In addition, four 9310 steel substrates fixed uniformly along the circumferential direction of a metal ring substrate were irradiated by this annular cathode HCPEB source. The surface and cross-section morphologies of the irradiated samples were characterized by scanning electron microscopy (SEM). SEM images of the surface reveal that crater and surface undulation have been formed, which hints that the irradiation energy of the HCPEB process is large enough for surface modification of 9310 steel. Meanwhile, SEM cross-section images exhibit that remelted layers with a thickness of about 5.4 μm have been obtained in all samples, which proves that a good practical irradiation uniformity can be achieved by this annular cathode HCPEB source.

  18. On the suitability of longitudinal profile measurements using Coherent Smith-Purcell radiation for high current proton beams

    CERN Document Server

    Barros, Joanna; Vieille-Grosjean, Mélissa; Kittelmann, Irena Dolenc; Thomas, Cyrille

    2014-01-01

    The use of Smith-Purcell radiation to measure electrons longitudinal profiles has been demonstrated at several facilities in the picosecond and sub-picosecond range. There is a strong interest for the development of non intercepting longitudinal profile diagnostics for high current proton beams. We present here results of simulations on the expected yield of longitudinal profile monitors using Smith-Purcell radiation for such proton beams.

  19. Gated current integrator for the beam in the RR barrier buckets

    Energy Technology Data Exchange (ETDEWEB)

    A. Cadorn; C. Bhat; J. Crisp

    2003-06-10

    At the Fermilab Recycler Ring (RR), the antiproton (pbar) beam will be stored azimuthally in different segments created by barrier buckets. The beam in each segment may have widely varying intensities. They have developed a gated integrator system to measure the beam intensity in each of the barrier bucket. Here they discuss the design of the system and the results of beam measurements using the integrator.

  20. Investigation of Line Current Harmonics in Cascaded Multi-level Inverter Based Induction Motor Drive and an Adaptive On-line Selective Current Harmonic Elimination Algorithm

    Directory of Open Access Journals (Sweden)

    P. Avirajamanjula

    2015-03-01

    Full Text Available Multilevel Inverters (MLIs have drawn increasing attention in numerous applications, especially in drives, distributed energy resources area, utility etc. MLIs have the ability to synthesize a near sinusoidal output voltage wave with minimal Total Harmonic Distortion (THD in low frequency switching. Even though they offer lower THD, the presence of lower order harmonics is objectionable and harmonics elimination in Multilevel Inverters (MLIs has been receiving immense attention for the past few decades. Existing Selective Harmonic Elimination (SHE techniques can eliminate the objectionable lower order voltage harmonics with low switching frequency by solving the Fourier non-linear transcendental equations of the output voltage. The line current harmonics has a direct role to play on the magneto-motive force and results in increase of mismatching of air-gap permeance, vibrations, acoustic noise etc. This study proposes Normalized Least Mean Squares (NLMS algorithm based scheme to eliminate the selected dominant harmonics in load current using only the knowledge of the frequencies to be eliminated. The algorithm is simulated using MATLAB/SIMULINK tool for a three-phase VSI to eliminate the fifth and seventh harmonics. The informative simulation results verify the validity and effectiveness of the proposed algorithm. The system performance is analyzed based on the simulation results considering Total Harmonic Distortion (THD, magnitude of eliminated harmonics and frequency spectrum.

  1. Development of a 300-kV Marx generator and its application to drive a relativistic electron beam

    Indian Academy of Sciences (India)

    Y Choyal; Lalit Gupta; Preeti Vyas; Prasad Deshpande; Anamika Chaturvedi; K C Mittal; K P Maheshwari

    2005-12-01

    We have indigenously developed a twenty-stage vertical structure type Marx generator. At a matched load of $90-100 \\Omega$, for 25 kV DC charging, an output voltage pulse of 230 kV, and duration 150 ns is obtained. This voltage pulse is applied to a relativistic electron beam (REB) planar diode. For a cathode-anode gap of 7·5 mm, an REB having beam voltage 160 kV and duration 150 ns is obtained. Brass as well as aluminum explosive electron emission-type cathodes have been used.

  2. Design of Current Controller in Servo Drive%伺服驱动电流调节器的设计

    Institute of Scientific and Technical Information of China (English)

    游帅; 马钧华

    2012-01-01

    This paper presented a design method of current controller in servo drive. On hardware design, three current sensors, LTS25-NP, ACS7xx, HCPL-7840 and their interface circuit with DSP's AD input were introduced, and these three current sensors can perform well to meet the demands of accuracy and speed in current sampling circuit. On software design, according to simulation, the principles of adjusting PI controller parameters were discussed. The results of the simulations show that good initial PI parameters can he calculated through the motor parameters, thus lay the foundation for experiment tuning. [Ch,8 fig. 1 tab. 10 ref. ]%介绍了伺服驱动中电流调节器的设计方法.在硬件上给出LTS25-NP,ACS7xx,HCPL-7840 3种电流采样器件的工作原理、性能指标和DSP的接口设计,可知3种器件可以满足不同的电流采样精度与速度的要求.在软件上,利用仿真得到电流调节器PI参数计算方法,并介绍实验整定方法.仿真结果表明,通过电机的参数可以计算得到PI电流调节器良好的初始参数,为实验整定做基础.

  3. Production of high current proton beams using complex H-rich molecules at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Adonin, A., E-mail: a.adonin@gsi.de; Barth, W.; Heymach, F.; Hollinger, R.; Vormann, H.; Yakushev, A. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 64291 (Germany)

    2016-02-15

    In this contribution, the concept of production of intense proton beams using molecular heavy ion beams from an ion source is described, as well as the indisputable advantages of this technique for operation of the GSI linear accelerator. The results of experimental investigations, including mass-spectra analysis and beam emittance measurements, with different ion beams (CH{sub 3}{sup +},C{sub 2}H{sub 4}{sup +},C{sub 3}H{sub 7}{sup +}) using various gaseous and liquid substances (methane, ethane, propane, isobutane, and iodoethane) at the ion source are summarized. Further steps to improve the ion source and injector performance with molecular beams are depicted.

  4. Two-way shape memory effect and alternating current driving characteristics of a TiNi alloy spring

    Institute of Scientific and Technical Information of China (English)

    WANG Zhiguo; ZU Xiaotao

    2004-01-01

    Two-way shape memory effect (TWSME) was induced into the TiNi shape memory alloys (SMAs) spring by thermomechanical training after annealing treatment, which has promising application in micro-actuating fields. The TWSME spring can contract upon heating and extend upon cooling. The results show that there is an increase of the recovery ratio up to a maximum TWSME of 45%. During the training procedure, transformation temperatures and hysteresis were measured by different scanning calorimetry (DSC). The results show that As (reverse transformation start temperature) and Af (revere transformation finish temperature) shift to lower temperature after training. The intervals of Af-As and Ms-Mr (Ms and Mf are the martensite start and finish temperatures, respectively) increase and the heat of transformation decreases after training. The electrothermal driving characteristics of the TWSME springs were also investigated with alternating current density of 3.2-14.7 A/mm2. It is found that the time response and the maximum contraction ratio greatly depend on the magnitude of the electrical current density.

  5. Experimental research of different plasma cathodes for generation of high-current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Shafir, G.; Kreif, M.; Gleizer, J. Z.; Gleizer, S.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel); Gunin, A. V.; Kutenkov, O. P.; Rostov, V. V. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Pegel, I. V. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Tomsk Polytechnic University, Tomsk 634034 (Russian Federation)

    2015-11-21

    The results of experimental studies of different types of cathodes—carbon-epoxy rods, carbon-epoxy capillary, edged graphite, and metal-dielectric—under the application of high-voltage pulses with an amplitude of several hundreds of kV and pulse duration of several nanoseconds are presented. The best diode performance was achieved with the edged graphite and carbon-epoxy-based cathodes characterized by uniform and fast (<1 ns) formation of explosive emission plasma spots and quasi-constant diode impedance. This result was achieved for both annular cathodes in a strong magnetic field and planar cathodes of a similar diameter (∼2 cm) with no external magnetic field. The cathodes based on carbon-epoxy rods and carbon-epoxy capillaries operating with an average current density up to 1 kA/cm{sup 2} showed insignificant erosion along 10{sup 6} pulses of the generator and the generated electron beam current showed excellent reproducibility in terms of the amplitude and waveform.

  6. Observation of asymmetric implosions in indirect-drive ICF associated with changes in laser beam-hohlraum coupling and relevance to mix experiments.

    Science.gov (United States)

    Turner, R. E.; Amendt, P. A.; Landen, O. L.; Wallace, R. J.; Thorp, K.; Pien, G.

    2004-11-01

    Indirect drive ICF experiments were performed on the Omega laser at LLE, both with and without distributed polarization rotators (DPR) in the laser beams. The hohlraums were irradiated with a three-cone beam geometry, experimentally adjusted to produce high-yield implosions with no DPRs installed. X-ray images of the cores of these implosions showed a small but tolerable P2 asymmetry. Similar experiments with DPRs installed produced lower yields, and x-ray images of the imploded cores showed substantially increased P2 asymmetries, suggesting that the shallow-angle cone of beams, which transits through the longest length of plasma and along the shallowest density gradients, had substantially increased absorption compared to the no-DPR case. We will show high magnification (nearly 100x) x-ray images of the cores, along with fusion neutron data. For capsules driven with good symmetry, we show the neutron yield results from capsules whose surfaces have been deliberately roughened by a measured amount, in order to compare to mix models in simulations.

  7. Optical Mixing in the Strong Coupling Regime: A New Method of Beam Conditioning at Hohlraum LEH and Direct Drive ICF Coronal Plasmas

    Science.gov (United States)

    Mardirian, Marine; Afeyan, Bedros; Huller, Stefan; Montgomery, David; Froula, Dustin; Kirkwood, Robert

    2012-10-01

    We will present theoretical and computational results on Brillouin interactions between two beams in co-, counter-, and orthogonal propagation geometries. The beams will be structured (with speckle patterns), the plasma will have inhomogeneous flow including the Mach -1 surface. As the growth rate of the instability surpasses the natural frequency of the ion wave, the strong coupling regime (SCR) is reached, where reactive quasi-modes with intensity dependent frequency shifts result. This is especially true in laser hot spots. We trace the consequences of operations in this regime with different damping rates on the ion acoustic waves. We consider convective and absolute instabilities as well as the design of experiments which could examine these new regimes of instability behavior with new 10 psec time resolved diagnostics. Whether well enough conditioned beams can result after 10's or 100's of pairwise crossings in direct and indirect drive ICF configurations, and whether SRS can thus be strongly suppressed downstream, remains to be demonstrated. But the prospects exist for such new paths to instability control in a staged manner before STUD pulses are implemented.-

  8. Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research.

    Science.gov (United States)

    Bornstein, Michael M; Horner, Keith; Jacobs, Reinhilde

    2017-02-01

    Diagnostic radiology is an essential component of treatment planning in the field of implant dentistry. This narrative review will present current concepts for the use of cone beam computed tomography imaging, before and after implant placement, in daily clinical practice and research. Guidelines for the selection of three-dimensional imaging will be discussed, and limitations will be highlighted. Current concepts of radiation dose optimization, including novel imaging modalities using low-dose protocols, will be presented. For preoperative cross-sectional imaging, data are still not available which demonstrate that cone beam computed tomography results in fewer intraoperative complications such as nerve damage or bleeding incidents, or that implants inserted using preoperative cone beam computed tomography data sets for planning purposes will exhibit higher survival or success rates. The use of cone beam computed tomography following the insertion of dental implants should be restricted to specific postoperative complications, such as damage of neurovascular structures or postoperative infections in relation to the maxillary sinus. Regarding peri-implantitis, the diagnosis and severity of the disease should be evaluated primarily based on clinical parameters and on radiological findings based on periapical radiographs (two dimensional). The use of cone beam computed tomography scans in clinical research might not yield any evident beneficial effect for the patient included. As many of the cone beam computed tomography scans performed for research have no direct therapeutic consequence, dose optimization measures should be implemented by using appropriate exposure parameters and by reducing the field of view to the actual region of interest.

  9. Control algorithm for the inverter fed induction motor drive with DC current feedback loop based on principles of the vector control

    Energy Technology Data Exchange (ETDEWEB)

    Vuckovic, V.; Vukosavic, S. (Electrical Engineering Inst. Nikola Tesla, Viktora Igoa 3, Belgrade, 11000 (Yugoslavia))

    1992-01-01

    This paper brings out a control algorithm for VSI fed induction motor drives based on the converter DC link current feedback. It is shown that the speed and flux can be controlled over the wide speed and load range quite satisfactorily for simpler drives. The base commands of both the inverter voltage and frequency are proportional to the reference speed, but each of them is further modified by the signals derived from the DC current sensor. The algorithm is based on the equations well known from the vector control theory, and is aimed to obtain the constant rotor flux and proportionality between the electrical torque, the slip frequency and the active component of the stator current. In this way, the problems of slip compensation, Ri compensation and correction of U/f characteristics are solved in the same time. Analytical considerations and computer simulations of the proposed control structure are in close agreement with the experimental results measured on a prototype drive.

  10. Development of a high power wideband polarizer for electron cyclotron current drive system in JT-60SA

    Energy Technology Data Exchange (ETDEWEB)

    Saigusa, Mikio, E-mail: saigusa@mx.ibaraki.ac.jp [Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Oyama, Gaku; Matsubara, Fumiaki; Takii, Keita; Sai, Takuma [Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Kobayashi, Takayuki; Moriyama, Shinichi [Japan Atomic Energy Agency, Naka, Ibaraki 311-0193 (Japan)

    2015-10-15

    Highlights: • We developed a new wideband polarizer for JT-60SA ECCD system. • The wideband polarizer is optimized for dual frequency gyrotrons (110 and 138 GHz) in JT-60SA. • The wideband polarization properties were verified at cold tests. • The preliminary high power tests have been carried out at 0.25 MW, 3 s at 110 GHz. - Abstract: A wideband polarizer consisting of a polarization twister and a circular polarizer has been developed for an electron cyclotron current driving system in JT-60SA, where the output frequencies of a dual frequency gyrotron for JT-60SA are 110 and 138 GHz. The groove depths are optimized for the dual frequencies by numerical simulations using a FDTD method and cold test results. The polarization properties of a mock-up polarizer are measured at the dual frequencies in cold tests. The cold test results suggest that all practical polarizations for ECCD experiments can be achieved at the dual frequencies. The prototype polarization twister has been tested up to 0.25 MW during 3 s at the frequency of 110 GHz.

  11. Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER

    CERN Document Server

    Chapman, I T; Sauter, O; Zucca, C; Asunta, O; Buttery, R J; Coda, S; Goodman, T; Igochine, V; Johnson, T; Jucker, M; La Haye, R J; Lennholm, M; Contributors, JET-EFDA

    2013-01-01

    13MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neo-classical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prudent to plan to use a complementary scheme which directly decreases the potential energy of the kink mode in order to reduce the sawtooth period. In the event that the natural sawtooth period is longer than expected, due to enhanced alpha particle stabilisation for instance, this ancillary sawtooth control can be provided from > 10MW of ion cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1 surface. Both ECCD and ICRH control schemes would benefit greatly from active feedback of the deposition with respect to the rational surface. If the q = 1 surface can be maintained closer to the magnetic axis, the efficacy of ECCD and ICRH schemes sig...

  12. Simulation of injector dynamics during steady inductive helicity injection current drive in the HIT-SI experiment

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, C., E-mail: hansec@uw.edu [PSI-Center, University of Washington, Seattle, Washington 98195 (United States); Columbia University, New York, New York 10027 (United States); Marklin, G. [PSI-Center, University of Washington, Seattle, Washington 98195 (United States); Victor, B. [HIT-SI Group, University of Washington, Seattle, Washington 98195 (United States); Akcay, C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Jarboe, T. [HIT-SI Group, University of Washington, Seattle, Washington 98195 (United States); PSI-Center, University of Washington, Seattle, Washington 98195 (United States)

    2015-04-15

    We present simulations of inductive helicity injection in the Helicity Injected Torus with Steady Inductive helicity injection (HIT-SI) device that treats the entire plasma volume in a single dynamic MHD model. A new fully 3D numerical tool, the PSI-center TETrahedral mesh code, was developed that provides the geometric flexibility required for this investigation. Implementation of a zero-β Hall MHD model using PSI-TET will be presented including formulation of a new self-consistent magnetic boundary condition for the wall of the HIT-SI device. Results from simulations of HIT-SI are presented focusing on injector dynamics that are investigated numerically for the first time. Asymmetries in the plasma loading between the two helicity injectors and progression of field reversal in each injector are observed. Analysis indicates cross-coupling between injectors through confinement volume structures. Injector impedance is found to scale with toroidal current at fixed density, consistent with experimental observation. Comparison to experimental data with an injector drive frequency of 14.5 kHz shows good agreement with magnetic diagnostics. Global mode structures from Bi-Orthogonal decomposition agree well with experimental data for the first four modes.

  13. High-current electron beam generation in a diode with a multicapillary dielectric cathode

    Science.gov (United States)

    Gleizer, J. Z.; Hadas, Y.; Gurovich, V. Tz.; Felsteiner, J.; Krasik, Ya. E.

    2008-02-01

    Results of high-current electron beam generation in an ˜200kV, ˜250ns diode with a multicapillary dielectric cathode (MCDC) assisted by either velvet-type or ferroelectric plasma sources (FPSs) are presented. Multicapillary cathodes made of cordierite, glass, and quartz glass samples were studied. It was found that the source of electrons is the plasma ejected from capillaries. The plasma parameters inside capillary channels and in the vicinity of the cathode surface were determined during the accelerating pulse using visible range spectroscopy. It was shown that glass multicapillary cathodes are characterized by less surface erosion than the cordierite cathodes. Also, it was found that multicapillary cathodes assisted by a FPS showed longer lifetime and better vacuum compatibility than multicapillary cathodes assisted by a velvet-type igniter. Finally, it was found that quartz glass MCDC assisted by FPS is characterized by almost simultaneous formation of the plasma in a cross-sectional area of the dielectric sample with respect to the beginning of the accelerating pulse. The latter is explained by intense UV radiation which synchronized formation of parallel discharges due to induced secondary electron emission.

  14. Experimental Estimating Deflection of a Simple Beam Bridge Model Using Grating Eddy Current Sensors

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2012-07-01

    Full Text Available A novel three-point method using a grating eddy current absolute position sensor (GECS for bridge deflection estimation is proposed in this paper. Real spatial positions of the measuring points along the span axis are directly used as relative reference points of each other rather than using any other auxiliary static reference points for measuring devices in a conventional method. Every three adjacent measuring points are defined as a measuring unit and a straight connecting bar with a GECS fixed on the center section of it links the two endpoints. In each measuring unit, the displacement of the mid-measuring point relative to the connecting bar measured by the GECS is defined as the relative deflection. Absolute deflections of each measuring point can be calculated from the relative deflections of all the measuring units directly without any correcting approaches. Principles of the three-point method and displacement measurement of the GECS are introduced in detail. Both static and dynamic experiments have been carried out on a simple beam bridge model, which demonstrate that the three-point deflection estimation method using the GECS is effective and offers a reliable way for bridge deflection estimation, especially for long-term monitoring.

  15. Surface Modification of Light Alloys by Low-Energy High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    X. D. Zhang

    2012-01-01

    Full Text Available This paper reviews results obtained by the research groups developing the low-energy high-current pulsed electron beam (LEHCPEB in Dalian (China and Metz (France on the surface treatment of light alloys. The pulsed electron irradiation induces an ultra-fast thermal cycle at the surface combined with the formation of thermal stress and shock waves. As illustrated for Mg alloys and Ti, this results in deep subsurface hardening (over several 100 μm which improves the wear resistance. The analysis of the top surface melted surface of light alloys also often witnesses evaporation and condensation of chemical species. This phenomenon can significantly modify the melt chemistry and was also suggested to lead to the development of specific solidification textures in the rapidly solidified layer. The potential use of the LEHCPEB technique for producing thermomechanical treatments under the so-called heating mode and, thus, modify the surface crystallographic texture, and enhance solid-state diffusion is also demonstrated in the case of the FeAl intermetallic compound.

  16. Study on Nanostructures Induced by High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2012-01-01

    Full Text Available Four techniques using high-current pulsed electron beam (HCPEB were proposed to obtain surface nanostructure of metal and alloys. The first method involves the distribution of several fine Mg nanoparticles on the top surface of treated samples by evaporation of pure Mg with low boiling point. The second technique uses superfast heating, melting, and cooling induced by HCPEB irradiation to refine the primary phase or the second phase in alloys to nanosized uniform distributed phases in the matrix, such as the quasicrystal phase Mg30Zn60Y10 in the quasicrystal alloy Mg67Zn30Y3. The third technique involves the refinement of eutectic silicon phase in hypereutectic Al-15Si alloys to fine particles with the size of several nanometers through solid solution and precipitation refinement. Finally, in the deformation zone induced by HCPEB irradiation, the grain size can be refined to several hundred nanometers, such as the grain size of the hypereutectic Al-15Si alloys in the deformation zone, which can reach ~400 nm after HCPEB treatment for 25 pulses. Therefore, HCPEB technology is an efficient way to obtain surface nanostructure.

  17. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    Science.gov (United States)

    Yang, Shen; Cai, Jie; Lv, Peng; Zhang, Conglin; Huang, Wei; Guan, Qingfeng

    2015-09-01

    The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO3 solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  18. Study on the effect of welding current during laser beam-resistance seam welding of aluminum alloy 5052

    Institute of Scientific and Technical Information of China (English)

    Li Yongqiang; Zhao Xihua; Zhao He; Cao Haipeng; Zhao Huanling

    2008-01-01

    The effect of welding current on the weld shape and tensile shear load during laser beam-resistance seam welding (LB-RSW) of aluminum alloy 5052 is studied. Experimental results show that the penetration depth, weld width,tensile shear load and the ratio of penetration depth to weld width of LB-RSW are bigger than those of laser beam welding(LBW) under the same conditions and the former three parameters increase as welding current rises. The weld shape of LB-RSW below 5 kA welding current is nearly the same as that of LBW. The weld morphology is protuberant under the condition of 5 kA welding current and 0.8 m/min welding speed. Furthermore, the microstructure of the weld seam of LB-RSW is coarser than that of LBW.

  19. Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA

    NARCIS (Netherlands)

    Chekanov, S.; Derrick, M.; Magill, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cindolo, F.; Corradi, M.; Iacobucci, G.; Margotti, A.; Nania, R.; Polini, A.; Antonelli, S.; Basile, M.; Bindi, M.; Cifarelli, L.; Contin, A.; Pasquale, S. De; Sartorelli, G.; Zichichi, A.; Bartsch, D.; Brock, I.; Hartmann, H.; Hilger, E.; Jakob, H.-P.; Jungst, M.; Nuncio-Quiroz, A. E.; Samson, U.; Schonberg, V.; Shehzadi, R.; Wlasenko, M.; Brook, N. H.; Heath, G. P.; Kaur, M.; Kaur, P.; Singh, I.; Capua, M.; Fazio, S.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Tassi, E.; Kim, J. Y.; Ibrahim, Z. A.; Mohamad Idris, F.; Kamaluddin, B.; Wan Abdullah, W. A. T.; Ning, Y.; Ren, Z.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Galas, A.; Olkiewicz, K.; Pawlik, B.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bold, T.; Grabowska-Bold, I.; Kisielewska, D.; Lukasik, J.; Przybycien, M.; Suszycki, L.; Kotanski, A.; Slominski, W.; Behnke, O.; Behrens, U.; Blohm, C.; Bonato, A.; Borras, K.; Ciesielski, R.; Coppola, N.; Fourletova, J.; Geiser, A.; Gottlicher, P.; Grebenyuk, J.; Gregor, I.; Haas, T.; Hain, W.; Huttmann, A.; Januschek, F.; Kahle, B.; Katkov, I. I.; Klein, U.; Kotz, U.; Kowalski, H.; Lisovyi, M.; Lobodzinska, E.; Lohr, B.; Mankel, R.; Melzer-Pellmann, I.-A.; Miglioranzi, S.; Montanari, A.; Namsoo, T.; Notz, D.; Parenti, A.; Rinaldi, L.; Roloff, P.; Rubinsky, I.; Schneekloth, U.; Spiridonov, A.; Szuba, D.; Szuba, J.; Theedt, T.; Ukleja, J.; Wolf, G.; Wrona, K.; Yagues Molina, A. G.; Youngman, C.; Zeuner, W.; Drugakov, V.; Lohmann, W.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P. G.; Bamberger, A.; Dobur, D.; Karstens, F.; Vlasov, N. N.; Bussey, P. J.; Doyle, A. T.; Dunne, W.; Forrest, M.; Rosin, M.; Saxon, D. H.; Skillicorn, I. O.; Gialas, I.; Papageorgiu, K.; Holm, U.; Klanner, R.; Lohrmann, E.; Perrey, H.; Schleper, P.; Schorner-Sadenius, T.; Sztuk, J.; Stadie, H.; Turcato, M.; Foudas, C.; Fry, C.; Long, K. R.; Tapper, A. D.; Matsumoto, T.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Aushev, V.; Bachynska, O.; Borodin, M.; Kadenko, I.; Kozulia, A.; Libov, V.; Lontkovskyi, D.; Makarenko, I.; Sorokin, Iu.; Verbytskyi, A.; Volynets, O.; Son, D.; de Favereau, J.; Piotrzkowski, K.; Barreiro, F.; Glasman, C.; Jimenez, M.; Labarga, L.; del Peso, J.; Ron, E.; Soares, M.; Terron, J.; Uribe-Estrada, C.; Zambrana, M.; Corriveau, F.; Schwartz, J.; Walsh, R.; Tsurugai, T.; Antonov, A.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Stifutkin, A.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Khein, L. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Zotkin, D. S.; Abt, I.; Caldwell, A.; Kollar, D.; Reisert, B.; Schmidke, W. B.; Grigorescu, G.; Keramidas, A.; Kooijman, P.; Pellegrino, A.; Tiecke, H.; Vazquez, M.; Brummer, N.; Bylsma, B.; Durkin, L. S.; Lee, A.; Ling, T. Y.; Allfrey, P. D.; Bell, M. A.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Foster, B.; Gwenlan, C.; Horton, K.; Oliver, K.; Robertson, A.; Walczak, R.; Bertolin, A.; Dal Corso, F.; Dusini, S.; Longhin, A.; Stanco, L.; Bellan, P.; Brugnera, R.; Carlin, R.; Garfagnini, A.; Limentani, S.; Oh, B. Y.; Raval, A.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cole, J. E.; Hart, J. C.; Abramowicz, H.; Ingbir, R.; Kananov, S.; Stern, A.; Kuze, M.; Maeda, J.; Hori, R.; Kagawa, S.; Okazaki, N.; Tawara, T.; Hamatsu, R.; Kaji, H.; Kitamura, S.; Ota, O.; Ri, Y. D.; Costa, M.; Ferrero, M. I.; Monaco, V.; Sacchi, R.; Sola, V.; Solano, A.; Arneodo, M.; Ruspa, M.; Fourletov, S.; Stewart, T. P.; Boutle, S. K.; Butterworth, J. M.; Jones, T. W.; Loizides, J. H.; Wing, M.; Brzozowska, B.; Ciborowski, J.; Grzelak, G.; Kulinski, P.; Luzniak, P.; Malka, J.; Nowak, R. J.; Pawlak, J. M.; Perlanski, W.; Tymieniecka, T.; Zarnecki, A. F.; Adamus, M.; Plucinski, P.; Ukleja, A.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Brownson, E.; Reeder, D. D.; Savin, A. A.; Smith, W. H.; Wolfe, H.; Bhadra, S.; Catterall, C. D.; Hartner, G.; Menary, S.; Noor, U.; Standage, J.; Whyte, J.

    2009-01-01

    Measurements of the cross sections for charged current deep inelastic scattering in e(-)p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb(-1) collected with the ZEUS detector at HERA at a centr

  20. Wideband current transformers for the surveillance of the beam extraction kicker system of the Large Hadron Collider

    CERN Document Server

    Defrance, C; Ducimetière, L; Vossenberg, E

    2007-01-01

    The LHC beam dumping system must protect the LHC machine from damage by reliably and safely extracting and absorbing the circulating beams when requested. Two sets of 15 extraction kicker magnets form the main active part of this system. A separate high voltage pulse generator powers each magnet. Because of the high beam energy and the consequences which could result from significant beam loss due to a malfunctioning of the dump system the magnets and generators are continuously surveyed in order to generate a beam abort as soon as an internal fault is detected. Amongst these surveillance systems, wideband current transformers have been designed to detect any erratic start in one of the generators. Output power should be enough to directly re-trigger all the power trigger units of the remaining 14 generators. The current transformers were developed in collaboration with industry. To minimize losses, high-resistivity cobalt alloy was chosen for the cores. The annealing techniques originally developed for LEP b...

  1. The SPARC project: a high-brightness electron beam source at LNF to drive a SASE-FEL experiment

    Energy Technology Data Exchange (ETDEWEB)

    Alesini, D.; Bertolucci, S.; Biagini, M.E.; Biscari, C.; Boni, R.; Boscolo, M.; Castellano, M.; Clozza, A.; Di Pirro, G.; Drago, A.; Esposito, A.; Ferrario, M. E-mail: massimo.ferrario@lnf.infn.it; Fusco, V.; Gallo, A.; Ghigo, A.; Guiducci, S.; Incurvati, M.; Laurelli, P.; Ligi, C.; Marcellini, F.; Migliorati, M.; Milardi, C.; Palumbo, L.; Pellegrino, L.; Preger, M.; Raimondi, P.; Ricci, R.; Sanelli, C.; Sgamma, F.; Spataro, B.; Serio, M.; Stecchi, A.; Stella, A.; Tazzioli, F.; Vaccarezza, C.; Vescovi, M.; Vicario, C.; Zobov, M.; Acerbi, E.; Alessandria, F.; Barni, D.; Bellomo, G.; Boscolo, I.; Broggi, F.; Cialdi, S.; DeMartinis, C.; Giove, D.; Maroli, C.; Petrillo, V.; Rome' , M.; Serafini, L.; Chiadroni, E.; Felici, G.; Levi, D.; Mastrucci, M.; Mattioli, M.; Medici, G.; Petrarca, G.S.; Catani, L.; Cianchi, A.; D' Angelo, A.; Di Salvo, R.; Fantini, A.; Moricciani, D.; Schaerf, C.; Bartolini, R.; Ciocci, F.; Dattoli, G.; Doria, A.; Flora, F.; Gallerano, G.P.; Giannessi, L.; Giovenale, E.; Messina, G.; Mezi, L.; Ottaviani, P.L.; Picardi, L.; Quattromini, M.; Renieri, A.; Ronsivalle, C.; Avaldi, L.; Carbone, C.; Cricenti, A.; Pifferi, A.; Perfetti, P.; Prosperi, T.; Albertini, V. Rossi; Quaresima, C.; Zema, N

    2003-07-11

    The Project Sorgente Pulsata e Amplificata di Radiazione Coerente (SPARC), proposed by a collaboration among ENEA-INFN-CNR-Universita' di Tor Vergata-INFM-ST, was recently approved by the Italian Government and will be built at LNF. The aim of the project is to promote an R and D activity oriented to the development of a coherent ultra-brilliant X-ray source in Italy. This collaboration has identified a program founded on two main issues: the generation of ultra-high peak brightness electron beams and of resonant higher harmonics in the SASE-FEL process, as presented in this paper.

  2. Investigations of Beam Dynamics Issues at Current and Future Hadron Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James [Univ. of New Mexico, Albuquerque, NM (United States); Lau, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Heinemann, Klaus [Univ. of New Mexico, Albuquerque, NM (United States); Bizzozero, David [Univ. of New Mexico, Albuquerque, NM (United States)

    2015-03-12

    Final Report Abstract for DE-FG02-99ER4110, May 15, 2011- October 15, 2014 There is a synergy between the fields of Beam Dynamics (BD) in modern particle accelerators and Applied Mathematics (AMa). We have formulated significant problems in BD and have developed and applied tools within the contexts of dynamical systems, topological methods, numerical analysis and scientific computing, probability and stochastic processes, and mathematical statistics. We summarize the three main areas of our AMa work since 2011. First, we continued our study of Vlasov-Maxwell systems. Previously, we developed a state of the art algorithm and code (VM3@A) to calculate coherent synchrotron radiation in single pass systems. In this cycle we carefully analyzed the major expense, namely the integral-over-history (IOH), and developed two approaches to speed up integration. The first strategy uses a representation of the Bessel function J0 in terms of exponentials. The second relies on “local sequences” developed recently for radiation boundary conditions, which are used to reduce computational domains. Although motivated by practicality, both strategies involve interesting and rather deep analysis and approximation theory. As an alternative to VM3@A, we are integrating Maxwell’s equations by a time-stepping method, bypass- ing the IOH, using a Discontinuous Galerkin (DG) method. DG is a generalization of Finite Element and Finite Volume methods. It is spectrally convergent, unlike the commonly used Finite Difference methods, and can handle complicated vacuum chamber geometries. We have applied this in several contexts and have obtained very nice results including an explanation of an experiment at the Canadian Light Source, where the geometry is quite complex. Second, we continued our study of spin dynamics in storage rings. There is much current and proposed activity where spin polarized beams are being used in testing the Standard Model and its modifications. Our work has focused

  3. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    Science.gov (United States)

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik

    2014-02-01

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 1011 n/cm2/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  4. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik, E-mail: hskang@postech.ac.kr [Pohang Accelerator Laboratory, San31, Hyoja-dong, Pohang, Gyeongbuk 790-784 (Korea, Republic of)

    2014-02-14

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E < 12.47% for 99% particles). The whole linac comprises mainly E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 10{sup 11} n/cm{sup 2}/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  5. Investigation of chemical vapour deposition diamond detectors by X- ray micro-beam induced current and X-ray micro-beam induced luminescence techniques

    CERN Document Server

    Olivero, P; Vittone, E; Fizzotti, F; Paolini, C; Lo Giudice, A; Barrett, R; Tucoulou, R

    2004-01-01

    Tracking detectors have become an important ingredient in high-energy physics experiments. In order to survive the harsh detection environment of the Large Hadron Collider (LHC), trackers need to have special properties. They must be radiation hard, provide fast collection of charge, be as thin as possible and remove heat from readout electronics. The unique properties of diamond allow it to fulfill these requirements. In this work we present an investigation of the charge transport and luminescence properties of "detector grade" artificial chemical vapour deposition (CVD) diamond devices developed within the CERN RD42 collaboration, performed by means of X-ray micro-beam induced current collection (XBICC) and X-ray micro- beam induced luminescence (XBIL) techniques. XBICC technique allows quantitative estimates of the transport parameters of the material to be evaluated and mapped with micrometric spatial resolution. In particular, the high resolution and sensitivity of the technique has allowed a quantitati...

  6. High-current CW beam profile monitors using transition radiation at CEBAF

    Science.gov (United States)

    Piot, P.; Denard, J.-C.; Adderley, P.; Capek, K.; Feldl, E.

    1997-01-01

    One way of measuring the profile of CEBAF's low-emittance, high-power beam is to use the optical transition radiation (OTR) emitted from a thin foil surface when the electron beam passes through it. We present the design of a monitor using the forward OTR emitted from a 0.25-μm carbon foil. We believe that the monitor will resolve three main issues: i) whether the maximum temperature of the foil stays below the melting point, ii) whether the beam loss remains below 0.5%, in order not to trigger the machine protection system, and iii) whether the monitor resolution (unlike that of synchrotron radiation monitors) is better than the product λγ. It seems that the most serious limitation for CEBAF is the beam loss due to beam scattering. We present results from Keil's theory and simulations from the computer code GEANT as well as measurements with aluminum foils with a 45-MeV electron beam. We also present a measurement of a 3.2-GeV beam profile that is much smaller than λγ, supporting Rule and Fiorito's calculations of the OTR resolution limit due to diffraction.

  7. Clinical utility of dental cone-beam computed tomography: current perspectives

    Directory of Open Access Journals (Sweden)

    Jaju PP

    2014-04-01

    Full Text Available Prashant P Jaju,1 Sushma P Jaju21Oral Medicine and Radiology, 2Conservative Dentistry and Endodontics, Rishiraj College of Dental Sciences and Research Center, Bhopal, IndiaAbstract: Panoramic radiography and computed tomography were the pillars of maxillofacial diagnosis. With the advent of cone-beam computed tomography, dental practice has seen a paradigm shift. This review article highlights the potential applications of cone-beam computed tomography in the fields of dental implantology and forensic dentistry, and its limitations in maxillofacial diagnosis.Keywords: dental implants, cone-beam computed tomography, panoramic radiography, computed tomography

  8. Basis for low beam loss in the high-current APT linac

    Energy Technology Data Exchange (ETDEWEB)

    Wangler, T.P.; Gray, E.R.; Krawczyk, F.L.; Kurennoy, S.S.; Lawrence, G.P.; Ryne, R.D. [Los Alamos National Lab., NM (United States); Crandall, K.R. [TECHSOURCE, Santa Fe, NM (United States)

    1998-12-31

    The present evidence that the APT proton linac design will meet its goal of low beam loss operation. The conclusion has three main bases: (1) extrapolation from the understanding of the performance of the 800-MeV LANSCE proton linac at Los Alamos, (2) the theoretical understanding of the dominant halo-forming mechanism in the APT accelerator from physics models and multiparticle simulations, and (3) the conservative approach and key principles underlying the design of the APT linac, which are aimed at minimizing beam halo and providing large apertures to reduce beam loss to a very low value.

  9. Preliminary results concerning the simulation of beam profiles from extracted ion current distributions for mini-STRIKE

    Energy Technology Data Exchange (ETDEWEB)

    Agostinetti, P., E-mail: piero.agostinetti@igi.cnr.it; Serianni, G.; Veltri, P. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Giacomin, M. [Physics Department, Università di Padova, via F. Marzolo 8, 35131 Padova (Italy); Bonomo, F.; Schiesko, L. [Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2016-02-15

    The Radio Frequency (RF) negative hydrogen ion source prototype has been chosen for the ITER neutral beam injectors due to its optimal performances and easier maintenance demonstrated at Max-Planck-Institut für Plasmaphysik, Garching in hydrogen and deuterium. One of the key information to better understand the operating behavior of the RF ion sources is the extracted negative ion current density distribution. This distribution—influenced by several factors like source geometry, particle drifts inside the source, cesium distribution, and layout of cesium ovens—is not straightforward to be evaluated. The main outcome of the present contribution is the development of a minimization method to estimate the extracted current distribution using the footprint of the beam recorded with mini-STRIKE (Short-Time Retractable Instrumented Kalorimeter). To accomplish this, a series of four computational models have been set up, where the output of a model is the input of the following one. These models compute the optics of the ion beam, evaluate the distribution of the heat deposited on the mini-STRIKE diagnostic calorimeter, and finally give an estimate of the temperature distribution on the back of mini-STRIKE. Several iterations with different extracted current profiles are necessary to give an estimate of the profile most compatible with the experimental data. A first test of the application of the method to the BAvarian Test Machine for Negative ions beam is given.

  10. Comparison of three different concepts of high dynamic range and dependability optimised current measurement digitisers for beam loss systems

    CERN Document Server

    Viganò, W; Effinger, E; Venturini, G G; Zamantzas, C

    2012-01-01

    Three Different Concepts of High Dynamic Range and Dependability Optimised Current Measurement Digitisers for Beam Loss Systems will be compared on this paper. The first concept is based on Current to Frequency Conversion, enhanced with an ADC for extending the dynamic range and decreasing the response time. A summary of 3 years’ worth of operational experience with such a system for LHC beam loss monitoring will be given. The second principle is based on an Adaptive Current to Frequency Converter implemented in an ASIC. The basic parameters of the circuit are discussed and compared with measurements. Several measures are taken to harden both circuits against single event effects and to make them tolerant for operation in radioactive environments. The third circuit is based on a Fully Differential Integrator for enhanced dynamic range, where laboratory and test installation measurements will be presented. All circuits are designed to avoid any dead time in the acquisition and have reliability and fail safe...

  11. The edge transient-current technique (E-TCT) with high energy hadron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gorišek, Andrej; Cindro, Vladimir; Kramberger, Gregor; Mandić, Igor [J. Stefan Institute, Ljubljana (Slovenia); Mikuž, Marko [J. Stefan Institute, Ljubljana (Slovenia); University of Ljubljana (Slovenia); Muškinja, Miha; Zavrtanik, Marko [J. Stefan Institute, Ljubljana (Slovenia)

    2016-09-21

    We propose a novel way to investigate the properties of silicon and CVD diamond detectors for High Energy Physics experiments complementary to the already well-established E-TCT technique using laser beam. In the proposed setup the beam of high energy hadrons (MIPs) is used instead of laser beam. MIPs incident on the detector in the direction parallel to the readout electrode plane and perpendicular to the edge of the detector. Such experiment could prove very useful to study CVD diamond detectors that are almost inaccessible for the E-TCT measurements with laser due to large band-gap as well as to verify and complement the E-TCT measurements of silicon. The method proposed is being tested at CERN in a beam of 120 GeV hadrons using a reference telescope with track resolution at the DUT of few μm. The preliminary results of the measurements are presented.

  12. The edge transient-current technique (E-TCT) with high energy hadron beam

    Science.gov (United States)

    Gorišek, Andrej; Cindro, Vladimir; Kramberger, Gregor; Mandić, Igor; Mikuž, Marko; Muškinja, Miha; Zavrtanik, Marko

    2016-09-01

    We propose a novel way to investigate the properties of silicon and CVD diamond detectors for High Energy Physics experiments complementary to the already well-established E-TCT technique using laser beam. In the proposed setup the beam of high energy hadrons (MIPs) is used instead of laser beam. MIPs incident on the detector in the direction parallel to the readout electrode plane and perpendicular to the edge of the detector. Such experiment could prove very useful to study CVD diamond detectors that are almost inaccessible for the E-TCT measurements with laser due to large band-gap as well as to verify and complement the E-TCT measurements of silicon. The method proposed is being tested at CERN in a beam of 120 GeV hadrons using a reference telescope with track resolution at the DUT of few μm. The preliminary results of the measurements are presented.

  13. Schottky Noise and Beam Transfer Functions

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz M.; Blaskiewicz M.

    2016-12-01

    Beam transfer functions (BTF)s encapsulate the stability properties of charged particle beams. In general one excites the beam with a sinusoidal signal and measures the amplitude and phase of the beam response. Most systems are very nearly linear and one can use various Fourier techniques to reduce the number of measurements and/or simulations needed to fully characterize the response. Schottky noise is associated with the finite number of particles in the beam. This signal is always present. Since the Schottky current drives wakefields, the measured Schottky signal is influenced by parasitic impedances.

  14. Investigations of Beam Dynamics Issues at Current and Future Hadron Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James [Univ. of New Mexico, Albuquerque, NM (United States); Lau, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Heinemann, Klaus [Univ. of New Mexico, Albuquerque, NM (United States); Bizzozero, David [Univ. of New Mexico, Albuquerque, NM (United States)

    2015-03-12

    Final Report Abstract for DE-FG02-99ER4110, May 15, 2011- October 15, 2014 There is a synergy between the fields of Beam Dynamics (BD) in modern particle accelerators and Applied Mathematics (AMa). We have formulated significant problems in BD and have developed and applied tools within the contexts of dynamical systems, topological methods, numerical analysis and scientific computing, probability and stochastic processes, and mathematical statistics. We summarize the three main areas of our AMa work since 2011. First, we continued our study of Vlasov-Maxwell systems. Previously, we developed a state of the art algorithm and code (VM3@A) to calculate coherent synchrotron radiation in single pass systems. In this cycle we carefully analyzed the major expense, namely the integral-over-history (IOH), and developed two approaches to speed up integration. The first strategy uses a representation of the Bessel function J0 in terms of exponentials. The second relies on “local sequences” developed recently for radiation boundary conditions, which are used to reduce computational domains. Although motivated by practicality, both strategies involve interesting and rather deep analysis and approximation theory. As an alternative to VM3@A, we are integrating Maxwell’s equations by a time-stepping method, bypass- ing the IOH, using a Discontinuous Galerkin (DG) method. DG is a generalization of Finite Element and Finite Volume methods. It is spectrally convergent, unlike the commonly used Finite Difference methods, and can handle complicated vacuum chamber geometries. We have applied this in several contexts and have obtained very nice results including an explanation of an experiment at the Canadian Light Source, where the geometry is quite complex. Second, we continued our study of spin dynamics in storage rings. There is much current and proposed activity where spin polarized beams are being used in testing the Standard Model and its modifications. Our work has focused

  15. Measurement of neutral current neutral pion production on Carbon in a Few-GeV Neutrino Beam

    CERN Document Server

    Kurimoto, Y

    2009-01-01

    The SciBooNE Collaboration has measured neutral current neutral pion production by the muon neutrino beam at a polystyrene target (C8H8). We obtained (7.7+- 0.5(stat.)+0.4-0.5 (sys.)) x 10^-2 as cross section ratio of the neutral current neutral pion production to total charged current cross section at the mean neutrino energy of 1.16 GeV. This result is consistent with the Monte Carlo prediction based on the Rein-Sehgal model

  16. Measurement of neutral current coherent neutral pion production on carbon in a few-GeV neutrino beam

    CERN Document Server

    Kurimoto, Y; Brice, S J; Bugel, L; Catala-Perez, J; Cheng, G; Conrad, J M; Djurcic, Z; Dore, U; Finley, D A; Franke, A J; Giganti, C; Gomez-Cadenas, J J; Guzowski, P; Hanson, A; Hayato, Y; Hiraide, K; Jover-Manas, G; Karagiorgi, G; Katori, T; Kobayashi, Y K; Kobilarcik, T; Kubo, H; Louis, W C; Loverre, P F; Ludovici, L; Mahn, K B M; Mariani, C; Masuike, S; Matsuoka, K; McGary, V T; Metcalf, W; Mills, G B; Mitsuka, G; Miyachi, Y; Mizugashira, S; Moore, C D; Nakajima, Y; Nakaya, T; Napora, R; Nienaber, P; Orme, D; Otani, M; Russell, A D; Sanchez, F; Shaevitz, M H; Shibata, T -A; Sorel, M; Stefanski, R J; Takei, H; Tanaka, H -K; Tanaka, M; Tayloe, R; Taylor, I J; Tesarek, R J; Uchida, Y; Van de Water, R; Walding, J J; Wascko, M O; White, H B; Wilking, M J; Yokoyama, M; Zeller, G P; Zimmerman, E D

    2010-01-01

    The SciBooNE Collaboration reports a measurement of neutral current coherent neutral pion production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive neutral pion production has been improved by detecting recoil protons from resonant neutral pion production. We measure the ratio of the neutral current coherent neutral pion production to total charged current cross sections to be (1.16 +/- 0.24) x 10-2. The ratio of charged current coherent pion to neutral current coherent pion production is calculated to be 0.14+0.30 -0.28, using our published charged current coherent pion measurement.

  17. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Yuri, E-mail: yufi55@mail.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 2/3 Akademicheskiy Ave. Tomsk, 634055 (Russian Federation); National Research Tomsk State University, 36 Lenina Str., Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenina Str., Tomsk, 634050 (Russian Federation); Tolkachev, Oleg, E-mail: ole.ts@mail.ru; Petyukevich, Maria, E-mail: petukevich@tpu.ru; Polisadova, Valentina, E-mail: polis@tpu.ru [National Research Tomsk Polytechnic University, 30 Lenina Str., Tomsk, 634050 (Russian Federation); Teresov, Anton, E-mail: tad514@sibmail.com [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 2/3 Akademicheskiy Ave. Tomsk, 634055 (Russian Federation); National Research Tomsk State University, 36 Lenina Str., Tomsk, 634050 (Russian Federation); Ivanova, Olga, E-mail: ivaov@mail.ru; Ikonnikova, Irina, E-mail: irina-ikonnikova@yandex.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm{sup 2}, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

  18. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    Science.gov (United States)

    Ivanov, Yuri; Tolkachev, Oleg; Petyukevich, Maria; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina; Polisadova, Valentina

    2016-01-01

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

  19. Polar-direct-drive experiments on OMEGA

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, F.J.; Craxton, R.S.; Bonino, M.J.; Epstein, R.; Glebov, V.Y.; Jacobs-Perkins, D.; Knauer, J.P.; Marozas, J.A.; McKenty, P.W.; Noyes, S.G.; Radha, P.B.; Seka, W.; Skupsky, S.; Smalyuk, V.A. [Rochester Univ., Lab. for Laser Energetics, NY (United States)

    2006-06-15

    Polar direct drive (PDD), a promising ignition path for the National Ignition Facility while the beams are in the indirect-drive configuration is currently being investigated on the OMEGA laser system by using 40 beams in six rings re-pointed to more uniformly illuminate the target. The OMEGA experiments are being performed with standard, 'warm' targets (865 {mu}m long diameter, 20 {mu}m thick, polymer (CH) shells filled with 15-atm D{sub 2}) with and without the use of an equatorial 'Saturn-like' toroidally shaped CH ring (nominal dimensions: 2.2 mm long diameter measured to ring center, 0.3 mm thick). For the Saturn case, the plasma formed around the ring refracts light toward the target equator as the ring plasma expands. The nominal laser drive is a 1 ns flat pulse, {approx} 400 J per beam, employing 1 THz, 2 dimensional smoothing by spectral dispersion (SSD) with polarization smoothing. Target implosion symmetry is diagnosed with framed X-ray back-lighting using additional OMEGA beams and by time-irradiated X-ray imaging of the stagnating core. The best results have been obtained with Saturn targets by varying the beam pointing and ring diameter, achieving about 75% of the fusion yield from symmetrically illuminated targets with the same total energy (60 beams, 15.3 kJ). (authors)

  20. Surface Nanocrystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    OpenAIRE

    2013-01-01

    The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB) technique. The structures of the nanocrystallized surface were characterized by X-ray diffraction and electron microscopy. Two nanostructures consisting of fine austenite grains (50–150 nm) and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that th...

  1. Measurement of Inclusive Neutral Current Neutral Pion Production on Carbon in a Few-GeV Neutrino Beam

    CERN Document Server

    Kurimoto, Y

    2009-01-01

    The SciBooNE Collaboration reports inclusive neutral current neutral pion production by a muon neutrino beam on a polystyrene target (C8H8). We obtain (7.7 \\pm 0.5(stat.) \\pm 0.5 (sys.)) x 10^(-2) as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein-Sehgal model implemented in our neutrino interaction simulation program with nuclear effects. The spectrum shape of the neutral pion momentum and angle agree with the model. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be (0.9 \\pm 0.5) x 10^(-2).

  2. Eddy-current analysis of isolated permanent-magnet drives using two- and three-dimensional finite-element methods (abstract)

    Science.gov (United States)

    Ferreira, C. A.

    1990-05-01

    Present drive systems which rely on mechanical devices for torque transmission have some negative features: the driven component cannot be isolated from the drive motor, rotating seals have inherent leakage and friction problems, and mechanical failures often occur due to torque overloads. Magnetic couplings are especially well suited for use in isolated-drive systems. This is often the case in military and aerospace applications where pumps and compressors are vital parts of the thermal and fuel operating systems. The application of permanent-magnet couplings in isolated drives requires accurate calculation of the eddy-current losses induced on the hermetic vessel. This is because the losses along with the required output torque dictate the size and efficiency of the permanent-magnet coupling. The vessel isolates the drive member from the driven member of the turbocompressor. The paper will show the formulation of the computational method based on the Poynting-vector theorem and the concept of motional electric field intensity. The eddy-current losses are calculated using two- and three-dimensional magnetostatic finite-element (FE) analysis. A comparison of the results obtained by two- and three-dimensional FE analysis is made. The results of the analysis will be compared to test data for verification. The test-facility setup and procedure will also be described. This state-of-the-art technique for computation of eddy-current losses has several advantages over conventional analysis methods: the nonlinearities of the magnetic circuit are taken into account, magnetic field fringing and end-leakage effects are not neglected, and the method does not rely on the use of empirical factors. The significant benefits of this approach are that trial-and-error experimental design approaches are eliminated and test data provide validation of analytical results.

  3. HARMONIC DRIVE SELECTION

    Directory of Open Access Journals (Sweden)

    Piotr FOLĘGA

    2014-03-01

    Full Text Available The variety of types and sizes currently in production harmonic drive is a problem in their rational choice. Properly selected harmonic drive must meet certain requirements during operation, and achieve the anticipated service life. The paper discusses the problems associated with the selection of the harmonic drive. It also presents the algorithm correct choice of harmonic drive. The main objective of this study was to develop a computer program that allows the correct choice of harmonic drive by developed algorithm.

  4. A high current sinusoidal pulse generator for the diluter magnets of the LHC beam dump system

    CERN Document Server

    Vossenberg, Eugène B; Ducimetière, L; Schröder, G H

    2000-01-01

    CERN is constructing the Large Hadron Collider (LHC), a superconducting accelerator that will collide protons at a center of mass energy of 14 TeV. The two colliding beams will each store an energy of up to 540 MJ, which must be safely deposited within one beam revolution of 89 mu s on two external absorbers located about 700 m from the extraction points at the end of dedicated extraction tunnels. To avoid evaporation of the graphite absorber material by the very high energy density of the incident beams, the deposition area of the beams on the absorber front face will be increased. This is done by a pair of sinusoidally powered orthogonal magnet systems producing approximately an e-shape figure of about 35 mm diameter, with a minimum velocity of 10 mm/ mu s during the dumping process. The pulse generators of the horizontally and vertically deflecting diluter magnets are composed of capacitor banks, discharged by stacks of solid state closing switches. They are connected to the magnets by 28 m long low induct...

  5. Beam Envelope, Injection and Acceleration in a Compact, High Current, Strong Focused Recirculating Accelerator Scheme

    Science.gov (United States)

    1988-12-01

    fixed vertical (berding) magnetic field, the insensitivity to energy i tdh poses a problem for ban trqaing and injectin. It is shoam that a ber trapping...Institute for Acetor and Plasma Beam Technology University of New Mexico A~xxpierque, N 87131 1 Dr. C. L. Hanner De e of Physics Iowa State University

  6. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, B., E-mail: biswaranjan.nayak1@gmail.com; Acharya, S.; Rajawat, R. K. [Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); DasGupta, K. [Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Beam Technology Development Group, BARC, Mumbai 400085 (India)

    2016-01-15

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ∼10{sup 12}–10{sup 13} n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  7. Development of 2D particle-in-cell code to simulate high current, low energy beam in a beam transport system

    Indian Academy of Sciences (India)

    S C L Srivastava; S V L S Rao; P Singh

    2007-10-01

    A code for 2D space-charge dominated beam dynamics study in beam transport lines is developed. The code is used for particle-in-cell (PIC) simulation of -uniform beam in a channel containing solenoids and drift space. It can also simulate a transport line where quadrupoles are used for focusing the beam. Numerical techniques as well as the results of beam dynamics studies are presented in the paper.

  8. Current status of ATLAS and proposed expansion to an exotic beam facility

    Science.gov (United States)

    Zinkann, G. P.; Billquist, P.; Bogaty, J.; Clifft, B.; Munson, F.; Nakagawa, K.; Nolen, J.; Pardo, R.; Shepard, K. W.; Specht, J.; Sutherland, A.; Tieman, B.; Tilbrook, I.

    1996-02-01

    The Argonne Tandem Linear Accelerator System (ATLAS) has been operating on a 24 hour, seven days a week schedule since the beginning of Fiscal Year 1994. Twenty-six different ion species ran during this period in 71 separate experiments. During the past year, there have been many projects undertaken to improve operation efficiency and upgrade various accelerator systems. There is also a new ECR ion source construction project underway. This paper covers, linac operation and new tuning techniques, the second generation ECR source construction project, the refrigerator system upgrade, an upgrade to the control system. Also described is a future expansion of ATLAS as an Exotic Beam Facility. (ATLAS is a world class heavy ion accelerator with an estimated value of approximately $80 million.) A concept that would utilize ATLAS as the foundation for a facility to generate and accelerate radioactive beams is briefly discussed.

  9. High-resolution electron-beam-induced-current study of the defect structure in GaN epilayers

    CERN Document Server

    Shmidt, N M; Usikov, A S; Yakimov, E B; Zavarin, E E

    2002-01-01

    Electron-beam-induced-current (EBIC) investigations of GaN structures grown by metal-organic chemical vapour deposition on (0001) sapphire substrates have been carried out. It is shown that the widths of the EBIC profiles for individual extended defects can be as small as about 100 nm. This width is observed to decrease with decreasing diffusion length and/or with increasing electron beam energy. The high spatial resolution is explained by the small diffusion length in the samples under study. The diffusion length is small even in structures with dislocation densities of about 10 sup 8 cm sup - sup 3 and carrier mobilities of about 600 cm sup 2 V sup - sup 1 s sup - sup 1 at 300 K and 1800 cm sup 2 V sup - sup 1 s sup - sup 1 at 125 K.

  10. Design of a high-current low-energy beam transport line for an intense D-T/D-D neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xiaolong, E-mail: luxl@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Engineering Research Center for Neutron Application, Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Wang, Junrun [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Engineering Research Center for Neutron Application, Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Zhang, Yu; Li, Jianyi; Xia, Li; Zhang, Jie; Ding, Yanyan; Jiang, Bing; Huang, Zhiwu; Ma, Zhanwen; Wei, Zheng [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Qian, Xiangping; Xu, Dapeng; Lan, Changlin [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Engineering Research Center for Neutron Application, Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Yao, Zeen, E-mail: zeyao@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Engineering Research Center for Neutron Application, Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2016-03-01

    An intense D-T/D-D neutron generator is currently being developed at the Lanzhou University. The Cockcroft–Walton accelerator, as a part of the neutron generator, will be used to accelerate and transport the high-current low-energy beam from the duoplasmatron ion source to the rotating target. The design of a high-current low-energy beam transport (LEBT) line and the dynamics simulations of the mixed beam were carried out using the TRACK code. The results illustrate that the designed beam line facilitates smooth transportation of a deuteron beam of 40 mA, and the number of undesired ions can be reduced effectively using two apertures.

  11. Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe [Northern Illinois U.

    2015-12-01

    Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

  12. Fundamental analysis and development of the current and voltage control method by changing the driving frequency for the transcutaneous energy transmission system.

    Science.gov (United States)

    Miura, Hidekazu; Yamada, Akihiro; Shiraishi, Yasuyuki; Yambe, Tomoyuki

    2015-08-01

    We have been developing transcutaneous energy transmission system (TETS) for a ventricular assist device, shape memory alloy (SMA) fibered artificial organs and so on, the system has high efficiency and a compact size. In this paper, we summarize the development, design method and characteristics of the TETS. New control methods for stabilizing output voltage or current of the TETS are proposed. These methods are primary side, are outside of the body, not depending on a communication system from the inside the body. Basically, the TETS operates at the fixed frequency with a suitable compensation capacitor so that the internal impedance is minimalized and a flat load characteristic is obtained. However, when the coil shifted from the optimal position, the coupling factor changes and the output is fluctuated. TETS has a resonant property; its output can be controlled by changing the driving frequency. The continuous current to continuous voltage driving method was implemented by changing driving frequency and setting of limitation of low side frequency. This method is useful for battery charging system for electrically driven artificial hearts and also useful for SMA fibered artificial organs which need intermittent high peak power comsumption. In this system, the internal storage capacitor is charged slowly while the fibers are turned off and discharge the energy when the fibers are turned on. We examined the effect of the system. It was found that the size and maximum output of the TETS would able to be reduced.

  13. Formation Mechanism of Micropores on the Surface of Pure Aluminum Induced by High-Current Pulsed Electron Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    ZOU Yang; CAI Jie; WAN Ming-Zhen; LV Peng; GUAN Qing-Feng

    2011-01-01

    The mechanism of micropores formed on the surface of polycrystalline pure aluminum under high-current pulsed electron beam (HCPEB) irradiation is explained. It is discovered that dispersed micropores with sizes of 0.1-1μm on the irradiated surface of pure aluminum can be successfully fabricated after HCPEB irradiation. The dominant formation mechanism of the surface micropores should be attributed to the formation of supersaturation vacancies within the near surface during the HCPEB irradiation and the migration of vacancies along gra,in boundaries and/or dislocations towards the irradiated surface. It is expected that the HCPEB technique will become a new method for the rapid synthesis of surface porous materials.%The mechanism of micropores formed on the surface of polycrystalline pure aluminum under high-current pulsed electron beam (HCPEB) irradiation is explained.It is discovered that dispersed micropores with sizes of 0.1-1μm on the irradiated surface of pure aluminum can be successfully fabricated after HCPEB irradiation.The dominant formation mechanism of the surface micropores should be attributed to the formation of supersaturation vacancies within the near surface during the HCPEB irradiation and the migration of vacancies along grain boundaries and/or dislocations towards the irradiated surface.It is expected that the HCPEB technique will become a new method for the rapid synthesis of surface porous materials.High-current pulsed electron beams (HCPEBs)have attracted much attention in the field of material surface modification.[1-7] During the transient bombardment process a high energy (108-109 W·cm-2) is deposited only in a very thin layer (less than tens of micrometers) within a very short time (a few microseconds) and thereby causes ultrafast heating and cooling on the irradiated surface of materials.The dynamic stress fields induced in these processes can induce intense deformation on the material surface.

  14. High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules

    Science.gov (United States)

    Phillips, Adam B.; Song, Zhaoning; DeWitt, Jonathan L.; Stone, Jon M.; Krantz, Patrick W.; Royston, John M.; Zeller, Ryan M.; Mapes, Meghan R.; Roland, Paul J.; Dorogi, Mark D.; Zafar, Syed; Faykosh, Gary T.; Ellingson, Randy J.; Heben, Michael J.

    2016-09-01

    We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm2) can be produced in a ˜40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm2) to full modules (1 m2). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.

  15. High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules.

    Science.gov (United States)

    Phillips, Adam B; Song, Zhaoning; DeWitt, Jonathan L; Stone, Jon M; Krantz, Patrick W; Royston, John M; Zeller, Ryan M; Mapes, Meghan R; Roland, Paul J; Dorogi, Mark D; Zafar, Syed; Faykosh, Gary T; Ellingson, Randy J; Heben, Michael J

    2016-09-01

    We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm(2)) can be produced in a ∼40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm(2)) to full modules (1 m(2)). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.

  16. A veterinary and behavioral analysis of dolphin killing methods currently used in the "drive hunt" in Taiji, Japan.

    Science.gov (United States)

    Butterworth, Andrew; Brakes, Philippa; Vail, Courtney S; Reiss, Diana

    2013-01-01

    Annually in Japanese waters, small cetaceans are killed in "drive hunts" with quotas set by the government of Japan. The Taiji Fishing Cooperative in Japan has published the details of a new killing method that involves cutting (transecting) the spinal cord and purports to reduce time to death. The method involves the repeated insertion of a metal rod followed by the plugging of the wound to prevent blood loss into the water. To date, a paucity of data exists regarding these methods utilized in the drive hunts. Our veterinary and behavioral analysis of video documentation of this method indicates that it does not immediately lead to death and that the time to death data provided in the description of the method, based on termination of breathing and movement, is not supported by the available video data. The method employed causes damage to the vertebral blood vessels and the vascular rete from insertion of the rod that will lead to significant hemorrhage, but this alone would not produce a rapid death in a large mammal of this type. The method induces paraplegia (paralysis of the body) and death through trauma and gradual blood loss. This killing method does not conform to the recognized requirement for "immediate insensibility" and would not be tolerated or permitted in any regulated slaughterhouse process in the developed world.

  17. High-current long-duration uniform electron beam generation in a diode with multicapillary carbon-epoxy cathode

    Energy Technology Data Exchange (ETDEWEB)

    Queller, T.; Gleizer, J. Z.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

    2013-09-28

    The results of reproducibly generating an electron beam with a current density of up to 5 kA/cm{sup 2}, without the cathode-anode gap being shorted by the plasma formed inside the cathode carbon-epoxy capillaries, in a ∼350 kV, ∼600 ns diode, with and without an external guiding magnetic field, are presented. The cathode sustained hundreds of pulses without degradation of its emission properties. Time- and space-resolved emissions of the plasma and spectroscopy analyses were used to determine the cathode plasma's density, temperature, and expansion velocity.

  18. High-current long-duration uniform electron beam generation in a diode with multicapillary carbon-epoxy cathode

    Science.gov (United States)

    Queller, T.; Gleizer, J. Z.; Krasik, Ya. E.

    2013-09-01

    The results of reproducibly generating an electron beam with a current density of up to 5 kA/cm2, without the cathode-anode gap being shorted by the plasma formed inside the cathode carbon-epoxy capillaries, in a ˜350 kV, ˜600 ns diode, with and without an external guiding magnetic field, are presented. The cathode sustained hundreds of pulses without degradation of its emission properties. Time- and space-resolved emissions of the plasma and spectroscopy analyses were used to determine the cathode plasma's density, temperature, and expansion velocity.

  19. On-line measurements of proton beam current from a PET cyclotron using a thin aluminum foil

    Science.gov (United States)

    Ghithan, S.; do Carmo, S. J. C.; Ferreira Marques, R.; Fraga, F. A. F.; Simões, H.; Alves, F.; Crespo, P.

    2013-07-01

    The number of cyclotrons capable of accelerating protons to about 20 MeV is increasing throughout the world. Originally aiming at the production of positron emission tomography (PET) radionuclides, some of these facilities are equipped with several beam lines suitable for scientific research. Radiobiology, radiophysiology, and other dosimetric studies can be performed using these beam lines. In this work, we measured the Bragg peak of the protons from a PET cyclotron using a stacked target consisting of several aluminum foils interleaved with polyethylene sheets, readout by in-house made transimpedance electronics. The measured Bragg peak is consistent with simulations performed using the SRIM/TRIM simulation toolkit. Furthermore, we report on experimental results aiming at measuring proton beam currents down to 10 pA using a thin aluminum foil (20-μm-thick). The aluminum was chosen for this task because it is radiation hard, it has low density and low radiation activity, and finally because it is easily available at negligible cost. This method allows for calculating the dose delivered to a target during an irradiation with high efficiency, and with minimal proton energy loss and scattering.

  20. Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

    Science.gov (United States)

    Trushnikov, D. N.; Mladenov, G. M.; Belenkiy, V. Ya.; Koleva, E. G.; Varushkin, S. V.

    2014-04-01

    Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 1016 m-3, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A.m-2, i.e. 8 mA for a 3-10 cm2 collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole.

  1. Influence of impurity and recycling on high-β steady-state plasmas sustained by rotating magnetic fields current drive

    Science.gov (United States)

    Guo, H. Y.; Grossnickle, J. A.; Hoffman, A. L.; Vlases, G. C.

    2009-06-01

    A new upgrade of the Translation, Confinement, and Sustainment (TCS) device, TCSU, has been built to form and sustain high temperature compact toroids (CT), known as Field Reversed Configurations, using Rotating Magnetic Fields (RMF). In TCS the plasma temperature was limited to several 10s of eV due to high impurity content. These impurities are greatly reduced in TCSU by using advanced plasma chamber and helium glow discharge cleaning. Reducing impurity radiation, when coupled with reduced overall recycling, enabled the plasma to enter into a new, collisionless regime with temperatures well over 200 eV, substantially exceeding the radiation barrier. This is a first for CTs at low input power density. This was achieved using the simple even-parity RMF drive (despite transient opening of field lines by the RMF) because the associated energy loss is sheath-limited, coupled with the low edge density resulting from the RMF pinch effect.

  2. Self-focusing of a high current density ion beam extracted with concave electrodes in a low energy region around 150 eV

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Y., E-mail: y.hirano@aist.go.jp [Innovative Plasma Technologies Group, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki (Japan); Laboratory of Physics, College of Science and Technologies, Nihon University, Tokyo (Japan); Kiyama, S.; Koguchi, H. [Innovative Plasma Technologies Group, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki (Japan); Sakakita, H. [Innovative Plasma Technologies Group, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki (Japan); Department of Engineering Mechanics and Energy, University of Tsukuba, Ibaraki (Japan)

    2014-02-15

    Spontaneous self-focusing of ion beam with high current density (J{sub c} ∼ 2 mA/cm{sup 2}, I{sub b} ∼ 65 mA) in low energy region (∼150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over ∼135–150 eV, and the J{sub c} jumps up from 0.7 to 2 mA/cm{sup 2}. Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence.

  3. PROSPECTS OF HIGH-CURRENT ELECTRON BEAMS APPLICATION TO RADIATION POLYETHYLENE CROSS-LINKING

    Directory of Open Access Journals (Sweden)

    A.G. Gurin

    2013-09-01

    Full Text Available A possibility of applying a pulse-periodic high-current induction electron accelerators to radiation polyethylene cross-linking is considered in the article. A comparative analysis with other devices used for irradiation is made.

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

    Science.gov (United States)

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

    2012-08-01

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

  5. Design and fabrication of nano-ring MRAM demo devices based on spin-polarized current driving

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nano-ring-type magnetic tunnel junctions(NR-MTJ)were nano-fabricated.The tunneling magnetoresistance(TMR)versus current(Ⅰ)loops of the NR-MTJs for a spin-polarized current switching were measured and the TMR ratio of around 20%~50% with a Al-O barrier at room temperature were observed.The critical value of switching current for the free Co_(60)Fe_(20)B_(20) layer between parallel and anti-parallel magnetization states is smaller than 650μA.The NR-MTJs arrays were also integrated above the transistors in ...

  6. Beyond ITER: Neutral beams for DEMO

    CERN Document Server

    McAdams, R

    2013-01-01

    In the development of magnetically confined fusion as an economically sustainable power source, ITER is currently under construction. Beyond ITER is the DEMO programme in which the physics and engineering aspects of a future fusion power plant will be demonstrated. DEMO will produce net electrical power. The DEMO programme will be outlined and the role of neutral beams for heating and current drive will be described. In particular, the importance of the efficiency of neutral beam systems in terms of injected neutral beam power compared to wallplug power will be discussed. Options for improving this efficiency including advanced neutralisers and energy recovery are discussed.

  7. The impact of interface states on the mobility and drive current of In0.53Ga0.47 As semiconductor n-MOSFETs

    Science.gov (United States)

    Osgnach, Patrik; Caruso, Enrico; Lizzit, Daniel; Palestri, Pierpaolo; Esseni, David; Selmi, Luca

    2015-06-01

    Accurate Schrödinger-Poisson and Multi-Subband Monte Carlo simulations are used to investigate the effect of interface states at the channel-insulator interface of In0.53Ga0.47 As MOSFETs. Acceptor states with energy inside the conduction band of the semiconductor can explain the dramatic Fermi level pinning observed in the experiments. Our results show that these states significantly impact the electrical mobility measurements but they appear to have a limited influence on the static current drive of short channel devices.

  8. Observation of Lower Hybrid Current Drive Improved Confinement with a Graphite Probe at the Last Closed Flux Surface of the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    徐国盛; 万宝年; 宋梅; 凌必利; 匡光力; 丁伯江

    2002-01-01

    High time resolution measurements of the electrostatic fluctuations, radial electric field Er and turbulence-induced electron flux Гe have been performed across the transition of lower hybrid current drive improved confinement with a graphite Langmuir probe array at the last closed flux surface of the HT-7 tokamak. The decrease of Гe is dominated by the suppression of fluctuation levels, which follows the change of Er. A reversal of the poloidal propagation direction of turbulence demonstrates that the poloidal propagation is dominated by Eт× Bφ drift. The enhancement of poloidal coherence accompanies the fluctuation suppression, which suggests the subtle variation of turbulence features.

  9. A Study of Energy Conversion Efficiency Versus Plasma Density by Lower Hybrid Current Drive in HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    丁伯江; 匡光力; 刘岳修; 刘登成; 单家方; 刘甫坤; 沈慰慈; 石跃江; 吴振伟; 林建安; 俞家文; 徐汉东; 商连全; 张晓东; 刘小宁; 赵燕平; 李建刚

    2002-01-01

    Ramp-up experiments by means of lower hybrid wave on HT-7 superconducting tokamak have been performed and analyzed. A ramp-up rate of over 300 kA/s is obtained and a conversion efficiency of over 10% has been achieved during the ramp-up phase. The study of the dependence of conversion efficiency on plasma density shows that the conversion efficiency is affected by the driven current, which is mainly dominated by the competition of impurity concentration with wave accessibility condition. In addition, the effect of current profile may play an important role in determining the conversion efficiency.

  10. A Study of Energy Conversion Efficiency Versus Plasma Density by Lower Hybrid Current Drive in HT—7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    丁伯江; 匡光力; 等

    2002-01-01

    Ramp-up experiments by means of lower hydrid wave on HT-7 superconducting tokamak have been performed and analyzed.A ramp-up rate of over 300kA/s is obtained and a conversion efficiency of over 10% has been achieved during the ramp-up phases.The study of the dependence of conversion efficiency on plasma density shows that the conversion efficiency is affected by the driven current,which is mainly dominated by the competition of impurity concentration with wave accessibility condition.In addition,the effect of current profile may play an important role in determining the conversion efficiency.

  11. Simulation of ion beam induced current in radiation detectors and microelectronic devices.

    Energy Technology Data Exchange (ETDEWEB)

    Vizkelethy, Gyorgy

    2009-10-01

    Ionizing radiation is known to cause Single Event Effects (SEE) in a variety of electronic devices. The mechanism that leads to these SEEs is current induced by the radiation in these devices. While this phenomenon is detrimental in ICs, this is the basic mechanism behind the operation of semiconductor radiation detectors. To be able to predict SEEs in ICs and detector responses we need to be able to simulate the radiation induced current as the function of time. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. On the other end, TCAD programs can simulate this process in microelectronic devices, but these TCAD codes costs hundreds of thousands of dollars and they require huge computing resources. In addition, in certain cases they fail to predict the correct behavior. A simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework.

  12. Five-Phase Five-Level Open-Winding/Star-Winding Inverter Drive for Low-Voltage/High-Current Applications

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick;

    2016-01-01

    This paper work proposed a five-phase five-level open-/star-winding multilevel AC converter suitable for low-voltage/high-current applications. Modular converter consists of classical two-level five-phase voltage source inverter (VSI) with slight reconfiguration to serve as a multilevel converter...

  13. Hosing Instability of the Drive Electron Beam in the E157 Plasma-Wakefield Acceleration Experiment at the Stanford Linear Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Brent Edward; /SLAC /UCLA

    2005-10-10

    In the plasma-wakefield experiment at SLAC, known as E157, an ultra-relativistic electron beam is used to both excite and witness a plasma wave for advanced accelerator applications. If the beam is tilted, then it will undergo transverse oscillations inside of the plasma. These oscillations can grow exponentially via an instability know as the electron hose instability. The linear theory of electron-hose instability in a uniform ion column predicts that for the parameters of the E157 experiment (beam charge, bunch length, and plasma density) a growth of the centroid offset should occur. Analysis of the E157 data has provided four critical results. The first was that the incoming beam did have a tilt. The tilt was much smaller than the radius and was measured to be 5.3 {micro}m/{delta}{sub z} at the entrance of the plasma (IP1.) The second was the beam centroid oscillates in the ion channel at half the frequency of the beam radius (betatron beam oscillations), and these oscillations can be predicted by the envelope equation. Third, up to the maximum operating plasma density of E157 ({approx}2 x 10{sup 14} cm{sup -3}), no growth of the centroid offset was measured. Finally, time-resolved data of the beam shows that up to this density, no significant growth of the tail of the beam (up to 8ps from the centroid) occurred even though the beam had an initial tilt.

  14. Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, IL (US)] (and others)

    2008-12-15

    Measurements of the cross sections for charged current deep inelastic scattering in e{sup -}p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb{sup -1} collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy are presented for Q{sup 2}>200 GeV{sup 2}. The double-differential cross-section d{sup 2}{sigma}/dxdQ{sup 2} is presented in the kinematic range 280

  15. Drive Stands

    Data.gov (United States)

    Federal Laboratory Consortium — The Electrical Systems Laboratory (ESL)houses numerous electrically driven drive stands. A drive stand consists of an electric motor driving a gearbox and a mounting...

  16. Chosen Aspects Of Investigations Of Solar Cells With The Laser Beam Induced Current Technique

    Directory of Open Access Journals (Sweden)

    Chrobak Łukasz Bartłomiej

    2015-06-01

    Full Text Available This paper presents maps of spatial distributions of the short circuit current Isc(x,y and the open circuit voltage Uoc(x,y of the investigated low cost solar cells. Visible differences in values of these parameters were explained by differences in the serial and shunt resistances determined for different points of solar cells from measurements of I–V characteristics. The spectral dependence of the photo voltage of solar cell is also shown, discussed and interpreted in the model of amorphous and crystal silicon.

  17. Comparative Studies on the Laser Damage Resistance of Ta2O5 and Nb2O5 Films Performed under Different Electron Beam Currents

    Institute of Scientific and Technical Information of China (English)

    XV Cheng; XU Lin-Min; ZHANG Han-Zhuo; QIANG Ying-Huai; ZHU Ya-Bo; LIU Jiong-Tian; SHAO Jian-Da

    2011-01-01

    @@ TaO and NbO films are deposited by conventional e-beam method under different electron beam currents.The optical transmittance, chemical composition, absorption, scattering, surface topography and laser-induced damage threshoM (LIDT) of the films are comparatively studied.It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry, whereas it increases the absorption, scattering and rms roughness for both TaO and NbO films.However, the LIDT increases first and then decreases with the increase of electron beam current.In addition, the annealing improves the optical transmittance, stoichiometry and LIDT for the two kinds of films.Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors: substoichiometric defects, structural defects and adhesive force.Furthermore, the comparative results indicate that the laser damage resistance of TaO is lower than that of NbO.%Ta2O5 and Nb2Os Rims are deposited by conventional e-beam method under different electron beam currents. The optical transmittance, chemical composition, absorption, scattering, surface topography and laser-induced damage threshold (LIDT) of the dims are comparatively studied. It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry, whereas it increases the absorption, scattering and rms roughness for both Ta2O5, and Ni2O5 Sims. However, the LIDT increases first and then decreases with the increase of electron beam current. In addition, the annealing improves the optical transmittance, stoichiometry and LIDT for the two kinds of Sims. Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors: substoichiometric defects, structural defects and adhesive force. Furthermore, the comparative results indicate that the laser damage resistance of Ta2O5 is lower than that ofNb2O5.

  18. Surface Nanocrystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    Directory of Open Access Journals (Sweden)

    Zhiyong Han

    2013-01-01

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

  19. Improvement of Wear Resistance of Magnesium Alloy AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; ZOU Jian-xin; JIANG Li-min; ZHOU Ji-yang; DONG Chuang

    2004-01-01

    Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase Mg17Al12 is nearly completely dissolved and as a result, a super-saturated solid solution forms on the re-melted surface.The microhardness is increased both in and far beyond the heat-affected zone (HAZ), reaching about 250μm.Measurements on sliding wear have shown that the wear resistance of the treated samples was improved by a factor of about 2.4 as compared to the as-received sample. It is also found that the sliding wear resistance can be further improved by surface alloying with TiN.

  20. Numerical simulation of thermal-mechanical process of Al-Si-Pb alloy treated by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    L(U) Xiao-xia; LI Rong-guang; AN Jian

    2006-01-01

    The modified microstructure of Al-Si-Pb alloys irradiated by high current electron beam (HCPEB) reveals three distinct regions: a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.

  1. Laser-beam-induced current mapping evaluation of porous silicon-based passivation in polycrystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rabha, M. Ben; Bessais, B. [Laboratoire de Nanomateriaux et des Systemes pour l' Energie, Centre de Recherches et des Technologies de l' Energie - Technopole de Borj-Cedria BP 95, 2050 Hammam-Lif (Tunisia); Dimassi, W.; Bouaicha, M.; Ezzaouia, H. [Laboratoire de photovoltaique, des semiconducteurs et des nanostructures, Centre de Recherches et des Technologies de l' Energie - Technopole de Borj-Cedria BP 95, 2050 Hammam-Lif (Tunisia)

    2009-05-15

    In the present work, we report on the effect of introducing a superficial porous silicon (PS) layer on the performance of polycrystalline silicon (pc-Si) solar cells. Laser-beam-induced current (LBIC) mapping shows that the PS treatment on the emitter of pc-Si solar cells improves their quantum response and reduce the grain boundaries (GBs) activity. After the porous silicon treatment, mapping investigation shows an enhancement of the LBIC and the internal quantum efficiency (IQE), due to an improvement of the minority carrier diffusion length and the passivation of recombination centers at the GBs as compared to the reference substrate. It was quantitatively shown that porous silicon treatment can passivate both the grains and GBs. (author)

  2. Relativistic high-current electron-beam stopping-power characterization in solids and plasmas: collisional versus resistive effects.

    Science.gov (United States)

    Vauzour, B; Santos, J J; Debayle, A; Hulin, S; Schlenvoigt, H-P; Vaisseau, X; Batani, D; Baton, S D; Honrubia, J J; Nicolaï, Ph; Beg, F N; Benocci, R; Chawla, S; Coury, M; Dorchies, F; Fourment, C; d'Humières, E; Jarrot, L C; McKenna, P; Rhee, Y J; Tikhonchuk, V T; Volpe, L; Yahia, V

    2012-12-21

    We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K(α) yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of ≈ 8 × 10(10) A/cm(2) they reach 1.5 keV/μm and 0.8 keV/μm, respectively. For higher current densities up to 10(12)A/cm(2), numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV/μm for electron current densities of 10(14)A/cm(2), representative of the full-scale conditions in the fast ignition of inertially confined fusion targets.

  3. Influence of electron-beam lithography exposure current level on the transport characteristics of graphene field effect transistors

    Science.gov (United States)

    Kang, Sangwoo; Movva, Hema C. P.; Sanne, Atresh; Rai, Amritesh; Banerjee, Sanjay K.

    2016-03-01

    Many factors have been identified to influence the electrical transport characteristics of graphene field-effect transistors. In this report, we examine the influence of the exposure current level used during electron beam lithography (EBL) for active region patterning. In the presence of a self-assembled hydrophobic residual layer generated by oxygen plasma etching covering the top surface of the graphene channel, we show that the use of low EBL current level results in higher mobility, lower residual carrier density, and charge neutrality point closer to 0 V, with reduced device-to-device variations. We show that this correlation originates from the resist heating dependent release of radicals from the resist material, near its interface with graphene, and its subsequent trapping by the hydrophobic polymer layer. Using a general model for resist heating, we calculate the difference in resist heating for different EBL current levels. We further corroborate our argument through control experiments, where radicals are either intentionally added or removed by other processes. We also utilize this finding to obtain mobilities in excess of 18 000 cm2/V s on silicon dioxide substrates. We believe these results are applicable to other 2D materials such as transition metal dichalcogenides and nanoscale devices in general.

  4. Polar Direct Drive

    Science.gov (United States)

    Skupsky, S.

    2003-10-01

    Direct drive offers the potential of higher target gain on the National Ignition Facility (NIF) than x-ray drive: The initial direct-drive target design had a 1-D gain of 45 and consisted primarily of a pure cryogenic DT shell. Using the expected levels of target and laser nonuniformities for the NIF, two-dimensional (2-D) hydrodynamic simulations predicted target gains around 30.(P.W. McKenty et al.), Phys. Plasmas 8, 2315 (2001). More-recent designs have shown that higher target gains could be obtained by replacing a portion of the DT shell with ``wetted'' CH foam and by using adiabat shaping: (1) Higher-Z material (C) in the foam increases laser absorption by about 40% (from 60% absorption to 85%).(S. Skupsky et al.), in Inertial Fusion Sciences and Applications 2001, edited by K. Tanaka et al. (Elsevier, Paris, 2002), p. 240. (2) Adiabat shaping allows the main portion of the fuel to be placed on a lower adiabat without compromising target stability.(V.N. Goncharov et al.), Phys. Plasmas 10, 1906 (2003). These direct-drive concepts can be tested on the NIF, long before that facility is converted to a direct-drive (spherically symmetric) irradiation configuration. Using the NIF x-ray-drive beam configuration, some of the near-polar beams could be pointed to better illuminate the target's equator. These more-oblique, equatorial beams will have lower absorption and reduced drive efficiency than the polar beams. One strategy to compensate for the difference in polar and equatorial drive is to reduce the irradiation at the poles and employ different pulse shapes to accommodate the time-dependent variations in drive and absorption. This concept of polar direct drive (PDD) has been studied using the 2-D hydrocode DRACO to determine the requirements for achieving ignition and moderate target gain for the NIF. Experiments on the OMEGA laser will examine the effects of oblique irradiation on target drive. Results of simulations for different direct-drive target designs

  5. Numerical Simulations of Electrokinetic Processes Comparing the Use of a Constant Voltage Difference or a Constant Current as Driving Force

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.

    materials and the prevention of the reinforced concrete corrosion. The electrical energy applied in an electrokinetic process produces electrochemical reactions at the electrodes. Different electrode processes can occur. When considering inert electrodes in aqueous solutions, the reduction of water...... are transported from the anode to the cathode through the closed electrical circuit of the cell. In the solution, the electrical current is carried by the ions, which move towards the electrode with different charge. Therefore, different authors have studied the system using the circuit theory. Assuming...

  6. Measurement of Neutral Current Neutral Pion Production on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Kurimoto, Yoshinori [Kyoto Univ. (Japan)

    2010-01-01

    Understanding of the π0 production via neutrino-nucleus neutral current interaction in the neutrino energy region of a few GeV is essential for the neutrino oscillation experiments. In this thesis, we present a study of neutral current π0 production from muon neutrinos scattering on a polystyrene (C8H8) target in the SciBooNE experiment. All neutrino beam data corresponding to 0.99 × 1020 protons on target have been analyzed. We have measured the cross section ratio of the neutral current π0 production to the total charge current interaction and the π0 kinematic distribution such as momentum and direction. We obtain [7.7 ± 0.5(stat.) ± 0.5(sys.)] × 10-2 as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein- Sehgal model, which is generally used for the Monte Carlo simulation by many neutrino oscillation experiments. We achieve less than 10 % uncertainty which is required for the next generation search for νµ → νe oscillation. The spectrum shape of the π0 momentum and the distribution of the π0 emitted angle agree with the prediction, which means that not only the Rein-Sehgal model but also the intra-nuclear interaction models describe our data well. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be (1.17 ± 0.23 ) × 10-2 based on the Rein and Sehgal model. The result gives the evidence for non-zero coherent pion production via neutral current interaction at the mean neutrino energy of 1.0 GeV.

  7. Polar-direct-drive simulations and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Marozas, J.A.; Marshall, F.J.; Craxton, R.S.; Igumenshchev, I.V.; Skupsky, S.; Bonino, M.J.; Collins, T.J.B.; Epstein, R.; Glebov, V.Yu.; Jacobs-Perkins, D.; Knauer, J.P.; McCrory, R.L.; McKenty, P.W.; Meyerhofer, D.D.; Noyes, S.G.; Radha, P.B.; Sangster, T.C.; Seka, W.; Smalyuk, V.A.

    2006-05-17

    Polar direct drive (PDD) will allow direct-drive ignition experiments on the National Ignition Facility (NIF) as it is configured for x-ray drive. Optimal drive uniformity is obtained via a combination of beam repointing, pulse shapes, spot shapes, and/or target design. This article describes progress in the development of standard and "Saturn" PDD target designs.

  8. A Measurement of Neutrino Charged Current Interactions and a Search for Muon Neutrino Disappearance with the Fermilab Booster Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Yasuhiro [Kyoto Univ. (Japan)

    2011-01-01

    In this thesis, we report on a measurement of muon neutrino inclusive charged current interactions on carbon in the few GeV region, using the Fermilab Booster Neutrino Beam. The all neutrino mode data collected in the SciBooNE experiment is used for this analysis. We collected high-statistics CC interaction sample at SciBooNE, and extracted energy dependent inclusive charged current interaction rates and cross sections for a wide energy range from 0.25 GeV to ~3 GeV. We measure the interaction rates with 6-15% precision, and the cross sections with 10-30% precision. We also made an energy integrated measurements, with the precisions of 3% for the rate, and 8% for the cross section measurements. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. This inclusive interaction measurement is nearly free from effects of hadron re-interactions in the nucleus. Hence, it is complementary to other exclusive cross section measurements, and essential to understand the neutrino interaction cross sections in the few GeV region, which is relevant to ongoing and future neutrino oscillation experiments. This analysis also provides the normalization for SciBooNE's previous cross section ratio measurements for charged current coherent pion production and neutral current neutral pion production. Then, a precise comparison between our previous measurements and the model predictions becomes possible. The result of the interaction rate measurement is used to constrain the product of the neutrino flux and the cross section at the other experiment on the Fermilab Booster Neutrino Beam: Mini-BooNE. We conducted a search for short-baseline muon neutrino disappearance using data both from SciBooNE and MiniBooNE, to test a possible neutrino oscillation with sterile neutrinos which is suggested by the LSND experiment. With this constraint by SciBooNE, we significantly reduced the flux and the cross section uncertainties at MiniBooNE, and achieved the

  9. Study of Bridging of the Spectral Gap in the Lower Hybrid Wave Current Drive in the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    WANG Mao; DING Bojiang; XU Handong; ZHAO Lianmin; LIU Liang; LIN Shiyao; XU Ping; SUN Youwen; HU Huaichuan; YANG Yong; JIA Hua; WANG Xiaojie; WANG Dongxia; QIN Yongliang; FENG Jianqiang; LIU Fukun; SHAN Jiafang; ZHAO Yanping; HT-7 team

    2009-01-01

    An additional lower hybrid wave (LHW) with a higher refractive index(N//)was investigated in the HT-7 tokamak to bridge the spectral gap.It was found that the spectral gap between the wave and the electrons in the outer region was bridged by the additional wave with a higher N// spectrum.The results showed that the sawteeth oscillation was suppressed by launching the additional wave,and that the power deposition profile was moved outwards and the current profile was broadened due to the application of the additional wave.Our study indicates that the spectral gap may be bridged by an additional wave with a higher N// spectrum in the outer region.

  10. Quasi-two-dimensional subthreshold current model of deep submicrometer SOI drive-in gate controlled hybrid transistors with lateral non-uniform doping profile

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We have analyzed the operating mechanism of the novel deep submicrometer SOI drive-in gate controlled hybrid transistor (DGCHT), which can effectively alleviate the contradiction between speed enhancement and power reduction in conventional MOS devices and can improve the output resistance. On the basis of this, the subthreshold current model of DGCHTs is proposed. The model takes into account the impact of lateral non-uniform doping profile on body effect, short-channel effect and carrier mobility. Considering the mobile charge, two-dimensional Poisson equation is solved with quasi-two-dimensional analysis and parabolic approximation of surface potential. With the surface potential obtained, the subthreshold current is figured out, including both the diffusion and drift component. The calculated results are in good agreement with the MEDICI numerical simulation results, indicating the correct description of the current characteristics of SOI DGCHT by the presented model. The model can also be considered as an important reference to the current simulation of deep submicrometer MOSFET with pocket implantation.

  11. An Insight into the Time Domain Phenomenon during the Transition Zone from Induction Motor to Synchronous Motor Mode for a Current Source Inverter Fed Synchronous Motor Drive System

    Directory of Open Access Journals (Sweden)

    A.B. Chattopadhyay

    2014-10-01

    Full Text Available Modeling of synchronous motor plays a dominant role in designing complicated drive system for different applications, especially large blower fans etc., for steel industries. As synchronous motor has no inherent starting torque generally it is started as an induction motor with the help of a damper winding and it pulls into synchronism under certain conditions. The present study exactly concentrates on this particular zone of transition from induction motor to synchronous motor mode for a current source inverter fed synchronous motor drive system. Due to complexity of synchronous motor in terms of number of windings and finite amount of air gap saliency, direct modeling of such transition zone in time domain becomes cumbersome at the first instance of modeling. That is why firstly the modeling is presented in complex frequency domain and then the time domain modeling is obtained by applying inverse Laplace transform technique. Apparently it seems to be a straight forward mathematical treatment but involvement of Convolution Integral for converting the formulation from s-domain to time domain becomes a matter of interest and it may draw the attention of various researchers working in this area. Furthermore the time domain response of the disturbance function may help a designer to fix up the time instant when the pull in phenomenon will be imposed by throwing the field winding to a DC supply.

  12. Current selection for lower migratory activity will drive the evolution of residency in a migratory bird population.

    Science.gov (United States)

    Pulido, Francisco; Berthold, Peter

    2010-04-20

    Global warming is impacting biodiversity by altering the distribution, abundance, and phenology of a wide range of animal and plant species. One of the best documented responses to recent climate change is alterations in the migratory behavior of birds, but the mechanisms underlying these phenotypic adjustments are largely unknown. This knowledge is still crucial to predict whether populations of migratory birds will adapt to a rapid increase in temperature. We monitored migratory behavior in a population of blackcaps (Sylvia atricapilla) to test for evolutionary responses to recent climate change. Using a common garden experiment in time and captive breeding we demonstrated a genetic reduction in migratory activity and evolutionary change in phenotypic plasticity of migration onset. An artificial selection experiment further revealed that residency will rapidly evolve in completely migratory bird populations if selection for shorter migration distance persists. Our findings suggest that current alterations of the environment are favoring birds wintering closer to the breeding grounds and that populations of migratory birds have strongly responded to these changes in selection. The reduction of migratory activity is probably an important evolutionary process in the adaptation of migratory birds to climate change, because it reduces migration costs and facilitates the rapid adjustment to the shifts in the timing of food availability during reproduction.

  13. Mesoscale SST-wind stress coupling in the Peru-Chile current system: Which mechanisms drive its seasonal variability?

    Science.gov (United States)

    Oerder, Vera; Colas, François; Echevin, Vincent; Masson, Sebastien; Hourdin, Christophe; Jullien, Swen; Madec, Gurvan; Lemarié, Florian

    2016-10-01

    Satellite observations and a high-resolution regional ocean-atmosphere coupled model are used to study the air/sea interactions at the oceanic mesoscale in the Peru-Chile upwelling current system. Coupling between mesoscale sea surface temperature (SST) and wind stress (WS) intensity is evidenced and characterized by correlations and regression coefficients. Both the model and the observations display similar spatial and seasonal variability of the coupling characteristics that are stronger off Peru than off Northern Chile, in relation with stronger wind mean speed and steadiness. The coupling is also more intense during winter than during summer in both regions. It is shown that WS intensity anomalies due to SST anomalies are mainly forced by mixing coefficient anomalies and partially compensated by wind shear anomalies. A momentum balance analysis shows that wind speed anomalies are created by stress shear anomalies. Near-surface pressure gradient anomalies have a negligible contribution because of the back-pressure effect related to the air temperature inversion. As mixing coefficients are mainly unchanged between summer and winter, the stronger coupling in winter is due to the enhanced large-scale wind shear that enables a more efficient action of the turbulent stress perturbations. This mechanism is robust as it does not depend on the choice of planetary boundary layer parameterization.

  14. Growth of doped silicon nanowires by pulsed laser deposition and their analysis by electron beam induced current imaging

    Energy Technology Data Exchange (ETDEWEB)

    Eisenhawer, B; Berger, A; Christiansen, S [Institute of Photonic Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Zhang, D; Clavel, R [Laboratory of Robotic Systems, Ecole Polytechnique Federale de Lausanne (EPFL), Station 9, CH-1015 Lausanne (Switzerland); Michler, J, E-mail: bjoern.eisenhawer@ipht-jena.de [Mechanics of Materials and Nanostructures Laboratory, EMPA-Materials Science and Technology, Feuerwerkstrasse 39, CH-3602 Thun (Switzerland)

    2011-02-18

    Doped silicon nanowires (NWs) were epitaxially grown on silicon substrates by pulsed laser deposition following a vapour-liquid-solid process, in which dopants together with silicon atoms were introduced into the gas phase by laser ablation of lightly and highly doped silicon target material. p-n or p{sup ++}-p junctions located at the NW-silicon substrate interfaces were thus realized. To detect these junctions and visualize them the electron beam induced current technique and two-point probe current-voltage measurements were used, based on nanoprobing individual silicon NWs in a scanning electron microscope. Successful silicon NW doping by pulsed laser deposition of doped target material could experimentally be demonstrated. This doping strategy compared to the commonly used doping from the gas phase during chemical vapour deposition is evaluated essentially with a view to potentially overcoming the limitations of chemical vapour deposition doping, which shows doping inhomogeneities between the top and bottom of the NW as well as between the core and shell of NWs and structural lattice defects, especially when high doping levels are envisaged. The pulsed laser deposition doping technique yields homogeneously doped NWs and the doping level can be controlled by the choice of the target material. As a further benefit, this doping procedure does not require the use of poisonous gases and may be applied to grow not only silicon NWs but also other kinds of doped semiconductor NWs, e.g. group III nitrides or arsenides.

  15. Multi-dimensional collective effects in high-current relativistic beams relevant to High Density Laboratory Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Shvets, Gennady

    2014-05-09

    In summary, an analytical model describing the self-pinching of a relativistic charge-neutralized electron beam undergoing the collisionless Weibel instability in an overdense plasma has been developed. The model accurately predicts the final temperature and size of the self-focused filament. It is found that the final temperature is primarily defined by the total beam’s current, while the filament’s radius is shown to be smaller than the collisionless skin depth in the plasma and primarily determined by the beam’s initial size. The model also accurately predicts the repartitioning ratio of the initial energy of the beam’s forward motion into the magnetic field energy and the kinetic energy of the surrounding plasma. The density profile of the final filament is shown to be a superposition of the standard Bennett pinch profile and a wide halo surrounding the pinch, which contains a significant fraction of the beam’s electrons. PIC simulations confirm the key assumption of the analytic theory: the collisionless merger of multiple current filaments in the course of the Weibel Instability provides the mechanism for Maxwellization of the beam’s distribution function. Deviations from the Maxwell-Boltzmann distribution are explained by incomplete thermalization of the deeply trapped and halo electrons. It is conjectured that the simple expression derived here can be used for understanding collsionless shock acceleration and magnetic field amplification in astrophysical plasmas.

  16. Complex reduction coefficient for a cylindrical electron beam with variable amplitude of the variable current component in the TWT

    Directory of Open Access Journals (Sweden)

    Chasnyk V. I.

    2013-12-01

    Full Text Available The conventional approach to calculating the space charge for the traveling-wave tube (TWT with phase velocity jumps is to use the same values of the depression coefficient as the ones for homogeneous helical TWTs. However, if the variable component of the exciting current in the expressions for determining the reduction coefficient is changed in amplitude, then the reduction factor is a complex value. Perhaps the neglect of this fact can significantly affect the volume discharge calculated value, and hence the non-synchronization parameter, for those of its values, which are characteristic of the TWT with a phase velocity jump. In this paper, formulas has been obtained for computation of real and imaginary parts of the complex reduction coefficient for a cylindrical electrons beam with exponential variable amplitude of variable current component in the TWT. Influence of complex reduction coefficient on the parameters of the TWT operating in the linear mode is estimated. It is shown that taking into account the imaginary part of the reduction coefficient for linear operation of the TWT makes it possible to change the estimated amount of space charge 1.5 to 2 times, which in its turn has quite a strong effect on the formation of the initial conditions of the nonlinear mode and, subsequently, on the output characteristics of the TWT.

  17. Dielectric Wakefield Accelerator to drive the future FEL Light Source.

    Energy Technology Data Exchange (ETDEWEB)

    Jing, C.; Power, J.; Zholents, A. (Accelerator Systems Division (APS)); ( HEP); (LLC)

    2011-04-20

    X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall layout, the transform ratio enhancement scheme used to increase the drive to main beam efficiency, main wakefield linac design, cooling of the structure, etc.

  18. Physical mechanism of beam halo-chaos formation for high-current proton beam in a periodic-focusing channels and a nonlinear control strategy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The physical mechanism of the halo-chaos formation for a high intensity proton beam in a periodic-fo cusing channel is analyzed using the transfer mahix theory and a qualiative analysis method.Particles-in-cell simula tims are further used to explore the mechanism of the beam halo-chaos fomation, which concerns not only with thc non linear effect of the beam space charge but also with the lransverse energy exchange belween the particles and the particle core. as well as the chaos generated by the nonlinear resonance ovcrlap. A nonlinear control method is proposed for con trolling tie haho-chaos. Simulation results show lhal the melhod is efhclivc. Somc potemlial applications of the halo chaos conlrol in experimenls are discussed.

  19. Electrostatic solitary waves in current layers: from Cluster observations during a super-substorm to beam experiments at the LAPD

    Directory of Open Access Journals (Sweden)

    J. S. Pickett

    2009-06-01

    Full Text Available Electrostatic Solitary Waves (ESWs have been observed by several spacecraft in the current layers of Earth's magnetosphere since 1982. ESWs are manifested as isolated pulses (one wave period in the high time resolution waveform data obtained on these spacecraft. They are thus nonlinear structures generated out of nonlinear instabilities and processes. We report the first observations of ESWs associated with the onset of a super-substorm that occurred on 24 August 2005 while the Cluster spacecraft were located in the magnetotail at around 18–19 RE and moving northward from the plasma sheet to the lobes. These ESWs were detected in the waveform data of the WBD plasma wave receiver on three of the Cluster spacecraft. The majority of the ESWs were detected about 5 min after the super-substorm onset during which time 1 the PEACE electron instrument detected significant field-aligned electron fluxes from a few 100 eV to 3.5 keV, 2 the EDI instrument detected bursts of field-aligned electron currents, 3 the FGM instrument detected substantial magnetic fluctuations and the presence of Alfvén waves, 4 the STAFF experiment detected broadband electric and magnetic waves, ion cyclotron waves and whistler mode waves, and 5 CIS detected nearly comparable densities of H+ and O+ ions and a large tailward H+ velocity. We compare the characteristics of the ESWs observed during this event to those created in the laboratory at the University of California-Los Angeles Plasma Device (LAPD with an electron beam. We find that the time durations of both space and LAPD ESWs are only slightly larger than the respective local electron plasma periods, indicating that electron, and not ion, dynamics are responsible for generation of the ESWs. We have discussed possible mechanisms for generating the ESWs in space, including the beam and kinetic Buneman type instabilities and the acoustic instabilities. Future studies will examine these mechanisms in

  20. Parametic Study of the current limit within a single driver-scaletransport beam line of an induction Linac for Heavy Ion Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Prost, Lionel Robert [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program that explores heavy-ion beam as the driver option for fusion energy production in an Inertial Fusion Energy (IFE) plant. The HCX is a beam transport experiment at a scale representative of the low-energy end of an induction linear accelerator driver. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ~0.2 μC/m) over long pulse durations (4 μs) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo and, electron and gas cloud effects. We present the results for a coasting 1 MeV K+ ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase-space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (~80%) is achieved with acceptable emittance growth and beam loss. We achieved good envelope control, and re-matching may only be needed every ten lattice periods (at 80% fill factor) in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  1. Grain refinement, hardening and metastable phase formation by high current pulsed electron beam (HCPEB) treatment under heating and melting modes

    Energy Technology Data Exchange (ETDEWEB)

    Grosdidier, T., E-mail: Thierry.grosdidier@univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Lab of Materials Modification by Laser, Ion and Electron Beams and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zou, J.X. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Bolle, B. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), ENIM, Ile du Saulcy, 57045 Metz (France); Hao, S.Z.; Dong, C. [Lab of Materials Modification by Laser, Ion and Electron Beams and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2010-08-15

    High current pulsed electron beam is a recently developed technique for surface modification. The pulsed electron irradiation introduces concentrated energy depositions in the thin surface layer of the treated materials, giving rise to an extremely fast heating and subsequent rapid cooling of the surface together with the formation of dynamic stress waves. Improved surface properties (hardness, corrosion resistance) can be obtained under the 'melting' mode when the top surface is melted and rapidly solidified (10{sup 7} K/s). In steels, this is essentially the result of nanostructures formed from the highly undercooled melt, melt surface purification, strain hardening induced by the thermal stress waves as well as metastable phase selections in the rapidly solidified melted layers. The use of the 'heating' mode is less conventional, combining effects of the heavy deformation and recrystallization/recovery mechanisms. A detailed analysis of a FeAl alloy demonstrates grain size refinement, hardening, solid-state enhanced diffusion and texture modification without modification of the surface geometry.

  2. Improvement of wear resistance of AZ31 and AZ91HP by high current pulsed electron beam treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; DONG Chuang; TU Gan-feng

    2005-01-01

    The surface modification of magnesium alloys (AZ31 and AZ91HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone(HAZ), but also beyond HAZ, reaching over 250 μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg17Al12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples.

  3. WC/Co composite surface structure and nano graphite precipitate induced by high current pulsed electron beam irradiation

    Science.gov (United States)

    Hao, S. Z.; Zhang, Y.; Xu, Y.; Gey, N.; Grosdidier, T.; Dong, C.

    2013-11-01

    High current pulsed electron beam (HCPEB) irradiation was conducted on a WC-6% Co hard alloy with accelerating voltage of 27 kV and pulse duration of 2.5 μs. The surface phase structure was examined by using glancing-angle X-ray diffraction (GAXRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) methods. The surface tribological properties were measured. It was found that after 20 pulses of HCPEB irradiation, the surface structure of WC/Co hard alloy was modified dramatically and composed of a mixture of nano-grained WC1-x, Co3W9C4, Co3W3C phases and graphite precipitate domains ˜50 nm. The friction coefficient of modified surface decreased to ˜0.38 from 0.6 of the initial state, and the wear rate reduced from 8.4 × 10-5 mm3/min to 6.3 × 10-6 mm3/min, showing a significant self-lubricating effect.

  4. Monte Carlo Simulations of Beam Losses in the Test Beam Line of CTF3

    CERN Document Server

    Nebot Del Busto, E; Branger, E; Holzer, E B; Doebert, S; Lillestol, R L; Welsch, C P

    2013-01-01

    The Test Beam Line (TBL) of the CLIC Test Facility 3 (CTF3) aims to validate the drive beam deceleration concept of CLIC, in which the RF power requested to boost particles to multi-TeV energies is obtained via deceleration of a high current and low energy drive beam (DB). Despite a TBL beam energy (150-80 MeV) significantly lower than the minimum nominal energy of the CLIC DB (250 MeV), the pulse time structure of the TBL provides the opportunity to measure beam losses with CLIC-like DB timing conditions. In this contribution, a simulation study on the detection of beam losses along the TBL for the commissioning of the recently installed beam loss monitoring system is presented. The most likely loss locations during stable beam conditions are studied by considering the beam envelope defined by the FODO lattice as well as the emittance growth due to the deceleration process. Moreover, the optimization of potential detector locations is discussed. Several factors are considered, namely: the distance to the bea...

  5. A Study of Charged Current Single Charged Pion Productions on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Hiraide, Katsuki [Kyoto Univ. (Japan)

    2009-01-01

    Understanding single charged pion production via neutrino-nucleus charged current interaction in the neutrino energy region of a few GeV is essential for future neutrino oscillation experiments since this process is a dominant background for vμ → vx oscillation measurements. There are two contributions to this process: single pion production via baryonic resonance (vμN → μ-+) and coherent pion production interacting with the entire nucleus (vμA → μ-+), where N is nucleon in the nucleus and A is the nucleus. The purpose of the study presented in this thesis is a precise measurement of charged current single charged pion productions, resonant and coherent pion productions, with a good final state separation in the neutrino energy region of a few GeV. In this thesis, we focus on the study of charged current coherent pion production from muon neutrinos scattering on carbon, vμ 12C → μ-12+, in the SciBooNE experiment. This is motivated by the fact that without measuring this component first, the precise determination of resonant pion production cross section can not be achieved since the contribution of coherent pion production in the region of small muon scattering angle is not small. Furthermore, the coherent process is particularly interesting because it is deeply rooted in fundamental physics via Adler's partially conserved axial-vector current theorem. We took data from June 2007 until August 2008, in both the neutrino and antineutrino beam. In total, 2.52 x 1020 protons on target were collected. We have performed a search for charged current coherent pion production by using SciBooNE's full neutrino data set, corresponding to 0.99 x 1020 protons on target. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio

  6. Drugged Driving

    Science.gov (United States)

    ... Parents & Educators Children & Teens Search Connect with NIDA : Google Plus Facebook LinkedIn Twitter YouTube Flickr RSS Menu ... misuse of prescription drugs can make driving a car unsafe—just like driving after drinking alcohol. Drugged ...

  7. Measurement of high-Q(2) neutral current deep inelastic e(+) p scattering cross sections with a longitudinally polarized positron beam at HERA

    NARCIS (Netherlands)

    Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartosik, N.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bold, T.; Bondarenko, K.; Boos, E. G.; Borras, K.; Boscherini, D.; Brock, I.; Brownson, E.; Brugnera, R.; Bruemmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A. M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, F.; Del Peso, J.; Dementiev, R. K.; De Pasquale, S.; Derrick, M.; Devenish, R. C. E.; Dobur, D.; Dolgoshein, B. A.; Dolinska, G.; Doyle, A. T.; Drugakov, V.; Durkin, L. S.; Dusini, S.; Eisenberg, Y.; Ermolov, P. F.; Eskreys, A.; Fazio, S.; Ferrando, J.; Ferrero, M. I.; Figiel, J.; Foster, B.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gizhko, A.; Gladilin, L. K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu. A.; Goettlicher, P.; Grabowska-Bold, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J. C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Huettmann, A.; Ibrahim, Z. A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jakob, H. -P.; Januschek, F.; Jones, T. W.; Juengst, M.; Kadenko, I.; Kahle, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I. I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L. A.; Kim, J. Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Kondrashova, N.; Kononenko, O.; Kooijman, P.; Korol, Ie.; Korzhavina, I. A.; Kotanski, A.; Koetz, U.; Kowalski, H.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B. B.; Libov, V.; Limentani, S.; Ling, T. Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Loehr, B.; Lohrmann, E.; Long, K. R.; Longhin, A.; Lontkovskyi, D.; Lukina, O. Yu.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Mastroberardino, A.; Mattingly, M. C. K.; Melzer-Pellmann, I. -A.; Mergelmeyer, S.; Miglioranzi, S.; Idris, F. Mohamad; Monaco, V.; Montanari, A.; Mujkic, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nigro, A.; Ning, Y.; Nobe, T.; Notz, D.; Nowak, R. J.; Nuncio-Quiroz, A. E.; Oh, B. Y.; Okazaki, N.; Olkiewicz, K.; Onishchuk, Yu.; Papageorgiu, K.; Parenti, A.; Pawlak, J. M.; Pawlik, B.; Pelfer, P. G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N. S.; Polini, A.; Proskuryakov, A. S.; Przybycien, M.; Raval, A.; Reeder, D. D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y. D.; Robertson, A.; Roloff, P.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Samson, U.; Sartorelli, G.; Savin, A. A.; Saxon, D. H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W. B.; Schneekloth, U.; Schoenberg, V.; Schoerner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L. M.; Shehzadi, R.; Singh, I.; Skillicorn, I. O.; Slominski, W.; Smith, W. H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stefaniuk, N.; Stern, A.; Stewart, T. P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A. D.; Tassi, E.; Terron, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomaszewska, J.; Trusov, V.; Tsurugai, T.; Turcato, M.; Turkot, O.; Tymieniecka, T.; Vazquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N. N.; Walczak, R.; Abdullah, W. A. T. Wan; Whitmore, J. J.; Wichmann, K.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yaguees-Molina, A. G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zabiegalov, O.; Zarnecki, A. F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B. O.; Zhmak, N.; Zichichi, A.; Zolkapli, Z.; Zotkin, D. S.

    2013-01-01

    Measurements of neutral current cross sections for deep inelastic scattering in e(+)p collisions at HERA with a longitudinally polarized positron beam are presented. The single-differential cross-sections d sigma=dQ(2), d sigma=dx and d sigma=dy and the reduced cross section (sigma) over tilde are m

  8. Measurement of high-Q (2) charged current deep inelastic scattering cross sections with a longitudinally polarised positron beam at HERA

    NARCIS (Netherlands)

    Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bold, T.; Boos, E. G.; Borras, K.; Boscherini, D.; Boutle, S. K.; Brock, I.; Brownson, E.; Brugnera, R.; Bruemmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Butterworth, J. M.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A. M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, F.; del Peso, J.; Dementiev, R. K.; De Pasquale, S.; Derrick, M.; Devenish, R. C. E.; Dobur, D.; Dolgoshein, B. A.; Dolinska, G.; Doyle, A. T.; Drugakov, V.; Durkin, L. S.; Dusini, S.; Eisenberg, Y.; Ermolov, P. F.; Eskreys, A.; Fazio, S.; Ferrando, J.; Ferrero, M. I.; Figiel, J.; Forrest, M.; Foster, B.; Fourletov, S.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gladilin, L. K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu. A.; Goettlicher, P.; Grabowska-Bold, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J. C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Horton, K.; Huettmann, A.; Iacobucci, G.; Ibrahim, Z. A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jakob, H. -P.; Januschek, F.; Jimenez, M.; Jones, T. W.; Juengst, M.; Kadenko, I.; Kahle, B.; Kamaluddin, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I. I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L. A.; Kim, J. Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Kooijman, P.; Korol, Ie.; Korzhavina, I. A.; Kotanski, A.; Koetz, U.; Kowalski, H.; Kulinski, P.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B. B.; Libov, V.; Limentani, S.; Ling, T. Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Loehr, B.; Lohrmann, E.; Loizides, J. H.; Long, K. R.; Longhin, A.; Lontkovskyi, D.; Lukina, O. Yu.; Luzniak, P.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Mastroberardino, A.; Matsumoto, T.; Mattingly, M. C. K.; Melzer-Pellmann, I. -A.; Miglioranzi, S.; Idris, F. Mohamad; Monaco, V.; Montanari, A.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nicholass, D.; Nigro, A.; Ning, Y.; Noor, U.; Notz, D.; Nowak, R. J.; Nuncio-Quiroz, A. E.; Oh, B. Y.; Okazaki, N.; Oliver, K.; Olkiewicz, K.; Onishchuk, Yu.; Ota, O.; Papageorgiu, K.; Parenti, A.; Pawlak, J. M.; Pawlik, B.; Pelfer, P. G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N. S.; Polini, A.; Proskuryakov, A. S.; Przybycien, M.; Raval, A.; Reeder, D. D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y. D.; Robertson, A.; Roloff, P.; Ron, E.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Salii, A.; Samson, U.; Sartorelli, G.; Savin, A. A.; Saxon, D. H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W. B.; Schneekloth, U.; Schoenberg, V.; Schoerner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L. M.; Shehzadi, R.; Singh, I.; Skillicorn, I. O.; Slominski, W.; Smith, W. H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stern, A.; Stewart, T. P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A. D.; Tassi, E.; Terron, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomalak, O.; Tomaszewska, J.; Tsurugai, T.; Turcato, M.; Tymieniecka, T.; Uribe-Estrada, C.; Vazquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N. N.; Volynets, O.; Walczak, R.; Abdullah, W. A. T. Wan; Whitmore, J. J.; Whyte, J.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yaguees-Molina, A. G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zarnecki, A. F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B. O.; Zhmak, N.; Zichichi, A.; Zolko, M.; Zotkin, D. S.; Zulkapli, Z.

    2010-01-01

    Measurements of the cross sections for charged current deep inelastic scattering in e (+) p collisions with a longitudinally polarised positron beam are presented. The measurements are based on a data sample with an integrated luminosity of 132 pb(-1) collected with the ZEUS detector at HERA at a ce

  9. Measurement of high-Q(2) neutral current deep inelastic e(-) p scattering cross sections with a longitudinally polarised electron beam at HERA

    NARCIS (Netherlands)

    Chekanov, S.; Derrick, M.; Magill, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cindolo, F.; Corradi, M.; Iacobucci, G.; Margotti, A.; Nania, R.; Polini, A.; Antonelli, S.; Basile, M.; Bindi, M.; Cifarelli, L.; Contin, A.; De Pasquale, S.; Sartorelli, G.; Zichichi, A.; Bartsch, D.; Brock, I.; Hartmann, H.; Hilger, E.; Jakob, H. P.; Juengst, M.; Nuncio-Quiroz, A. E.; Samson, U.; Schoenberg, V.; Shehzadi, R.; Wlasenko, M.; Brook, N. H.; Heath, G. P.; Kaur, M.; Kaur, P.; Singh, I.; Capua, M.; Fazio, S.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Tassi, E.; Kim, J. Y.; Ibrahim, Z. A.; Mohamad Idris, F.; Kamaluddin, B.; Wan Abdullah, W. A. T.; Ning, Y.; Ren, Z.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Galas, A.; Olkiewicz, K.; Pawlik, B.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bold, T.; Grabowska-Bold, I.; Kisielewska, D.; Lukasik, J.; Przybycien, M.; Suszycki, L.; Kotanski, A.; Slominski, W.; Behnke, O.; Behrens, U.; Blohm, C.; Bonato, A.; Borras, K.; Ciesielski, R.; Coppola, N.; Fourletova, J.; Geiser, A.; Goettlicher, P.; Grebenyuk, J.; Gregor, I.; Haas, T.; Hain, W.; Huettmann, A.; Januschek, F.; Kahle, B.; Katkov, I. I.; Klein, U.; Koetz, U.; Kowalski, H.; Lisovyi, M.; Lobodzinska, E.; Loehr, B.; Mankel, R.; Melzer-Pellmann, I. -A.; Miglioranzi, S.; Montanari, A.; Namsoo, T.; Notz, D.; Parenti, A.; Rinaldi, L.; Roloff, P.; Rubinsky, I.; Schneekloth, U.; Spiridonov, A.; Szuba, D.; Szuba, J.; Theedt, T.; Ukleja, J.; Wolf, G.; Wrona, K.; Molina, A. G. Yagues; Youngman, C.; Zeuner, W.; Drugakov, V.; Lohmann, W.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P. G.; Bamberger, A.; Dobur, D.; Karstens, F.; Vlasov, N. N.; Bussey, P. J.; Doyle, A. T.; Dunne, W.; Forrest, M.; Rosin, M.; Saxon, D. H.; Skillicorn, I. O.; Gialas, I.; Papageorgiu, K.; Holm, U.; Klanner, R.; Lohrmann, E.; Perrey, H.; Schleper, P.; Schoerner-Sadenius, T.; Sztuk, J.; Stadie, H.; Turcato, M.; Foudas, C.; Fry, C.; Long, K. R.; Tapper, A. D.; Matsumoto, T.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Aushev, V.; Bachynska, O.; Borodin, M.; Kadenko, I.; Kozulia, A.; Libov, V.; Lontkovskyi, D.; Makarenko, I.; Sorokin, Iu.; Verbytskyi, A.; Volynets, O.; Son, D.; de Favereau, J.; Piotrzkowski, K.; Barreiro, F.; Glasman, C.; Jimenez, M.; Labarga, L.; del Peso, J.; Ron, E.; Soares, M.; Terron, J.; Uribe-Estrada, C.; Zambrana, M.; Corriveau, F.; Schwartz, J.; Walsh, R.; Tsurugai, T.; Antonov, A.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Stifutkin, A.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Khein, L. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Zotkin, D. S.; Abt, I.; Caldwell, A.; Kollar, D.; Reisert, B.; Schmidke, W. B.; Grigorescu, G.; Keramidas, A.; Kooijman, P.; Pellegrino, A.; Tiecke, H.; Vazquez, M.; Bruemmer, N.; Bylsma, B.; Durkin, L. S.; Lee, A.; Ling, T. Y.; Allfrey, P. D.; Bell, M. A.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Foster, B.; Gwenlan, C.; Horton, K.; Oliver, K.; Robertson, A.; Walczak, R.; Bertolin, A.; Dal Corso, F.; Dusini, S.; Longhin, A.; Stanco, L.; Bellan, P.; Brugnera, R.; Carlin, R.; Garfagnini, A.; Limentani, S.; Oh, B. Y.; Raval, A.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cole, J. E.; Hart, J. C.; Abramowicz, H.; Ingbir, R.; Kananov, S.; Stern, A.; Kuze, M.; Maeda, J.; Hori, R.; Kagawa, S.; Okazaki, N.; Tawara, T.; Hamatsu, R.; Kaji, H.; Kitamura, S.; Ota, O.; Ri, Y. D.; Costa, M.; Ferrero, M. I.; Monaco, V.; Sacchi, R.; Sola, V.; Solano, A.; Arneodo, M.; Ruspa, M.; Fourletov, S.; Stewart, T. P.; Boutle, S. K.; Butterworth, J. M.; Jones, T. W.; Loizides, J. H.; Wing, M.; Brzozowska, B.; Ciborowski, J.; Grzelak, G.; Kulinski, P.; Luzniak, P.; Malka, J.; Nowak, R. J.; Pawlak, J. M.; Perlanski, W.; Tymieniecka, T.; Zarnecki, A. F.; Adamus, M.; Plucinski, P.; Ukleja, A.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Brownson, E.; Reeder, D. D.; Savin, A. A.; Smith, W. H.; Wolfe, H.; Bhadra, S.; Catterall, C. D.; Hartner, G.; Menary, S.; Noor, U.; Standage, J.; Whyte, J.

    2009-01-01

    Measurements of the neutral current cross sections for deep inelastic scattering in e(-) p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections d sigma/dQ(2), d sigma/dx and d sigma/dy and the double-differential cross sections in Q(2

  10. Resurgent Na+ current in pyramidal neurones of rat perirhinal cortex: axonal location of channels and contribution to depolarizing drive during repetitive firing

    Science.gov (United States)

    Castelli, Loretta; Biella, Gerardo; Toselli, Mauro; Magistretti, Jacopo

    2007-01-01

    The perirhinal cortex (PRC) is a supra-modal cortical area that collects and integrates information originating from uni- and multi-modal neocortical regions and directed to the hippocampus. The mechanisms that underlie the specific excitable properties of the different PRC neuronal types are still largely unknown, and their elucidation may be important in understanding the integrative functions of PRC. In this study we investigated the expression and properties of resurgent Na+ current (INaR) in pyramidal neurones of rat PRC area 35 (layer II). Patch-clamp experiments in acute PRC slices were first carried out. A measurable INaR was expressed by a large majority of neurones (31 out of 35 cells). INaR appeared as an inward, slowly decaying current elicited upon step repolarization after depolarizations sufficient to induce nearly complete inactivation of the transient Na+ current (INaT). INaR had a peak amplitude of ∼2.5% that of INaT, and showed the typical biophysical properties also observed in other neuronal types (i.e. cerebellar Purkinje and granule cells), including a bell-shaped current–voltage relationship with a peak at approximately −40 mV, and a characteristic acceleration of activation and decay speed at potentials negative to −45 mV. Current-clamp experiments were then carried out in which repetitive action-potential discharge at various frequencies was induced with depolarizing current injection. The voltage signals thus obtained were then used as command waveforms for voltage-clamp recordings. These experiments showed that a Na+ current identifiable as INaR activates in the early interspike phase even at relatively high firing frequencies (20 Hz), thereby contributing to the depolarizing drive and possibly enhancing repetitive discharge. In acutely dissociated area 35 layer II neurones, as well as in nucleated patches from the same neurones, INaR was never observed, despite the presence of typical INaTs. Since in both preparations neuronal

  11. Polar-direct-drive experiments on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Hohenberger, M.; Radha, P. B.; Myatt, J. F.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Fiksel, G.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); and others

    2015-05-15

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D{sub 2} gas were imploded with total drive energies ranging from ∼500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 × 10{sup 14} to 1.2 × 10{sup 15 }W/cm{sup 2}. Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.

  12. Polar-direct-drive experiments on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Hohenberger, M. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Radha, P. B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Myatt, J. F. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; LePape, S. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Marozas, J. A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Marshall, F. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Michel, D. T. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Regan, S. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Seka, W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Shvydky, A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Bates, J. W. [U. S. Naval Research Laboratory, Washington, DC 20375, USA; Betti, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Boehly, T. R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Bonino, M. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Casey, D. T. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Collins, T. J. B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Craxton, R. S. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Delettrez, J. A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Edgell, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Epstein, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Fiksel, G. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Fitzsimmons, P. [General Atomics, San Diego, California 92121, USA; Frenje, J. A. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Goncharov, V. N. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Harding, D. R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Kalantar, D. H. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Karasik, M. [U. S. Naval Research Laboratory, Washington, DC 20375, USA; Kessler, T. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Kilkenny, J. D. [General Atomics, San Diego, California 92121, USA; Knauer, J. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Kurz, C. [General Atomics, San Diego, California 92121, USA; Lafon, M. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; LaFortune, K. N. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; MacGowan, B. J. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Mackinnon, A. J. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; MacPhee, A. G. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; McCrory, R. L. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; McKenty, P. W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Meeker, J. F. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Nagel, S. R. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Nikroo, A. [General Atomics, San Diego, California 92121, USA; Obenschain, S. [U. S. Naval Research Laboratory, Washington, DC 20375, USA; Petrasso, R. D. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Ralph, J. E. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Rinderknecht, H. G. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Rosenberg, M. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Schmitt, A. J. [U. S. Naval Research Laboratory, Washington, DC 20375, USA; Wallace, R. J. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Weaver, J. [U. S. Naval Research Laboratory, Washington, DC 20375, USA; Widmayer, C. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Skupsky, S. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Solodov, A. A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Yaakobi, B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA; Zuegel, J. D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA

    2015-05-01

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D2 gas were imploded with total drive energies ranging from ~500-750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 x 1014 to 1.2 x 1015 W/cm2. Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.

  13. Electric drives

    CERN Document Server

    Boldea, Ion

    2005-01-01

    ENERGY CONVERSION IN ELECTRIC DRIVESElectric Drives: A DefinitionApplication Range of Electric DrivesEnergy Savings Pay Off RapidlyGlobal Energy Savings Through PEC DrivesMotor/Mechanical Load MatchMotion/Time Profile MatchLoad Dynamics and StabilityMultiquadrant OperationPerformance IndexesProblemsELECTRIC MOTORS FOR DRIVESElectric Drives: A Typical ConfigurationElectric Motors for DrivesDC Brush MotorsConventional AC MotorsPower Electronic Converter Dependent MotorsEnergy Conversion in Electric Motors/GeneratorsPOWER ELECTRONIC CONVERTERS (PECs) FOR DRIVESPower Electronic Switches (PESs)The

  14. Modulation method for a multiple drive system based on a two-stage direct power conversion topology with reduced input current ripple

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    A new two-stage multi-drive direct power conversion (DPC) topology suited for multi-drive application is proposed, having an input port for a three-phase power supply and several output ports to connect three-phase loads, which are independently controlled and allow for sine wave in-sine wave out...

  15. It does not always have to be three-phase current. Digitalisation makes dc drives still attractive. Es muss nicht immer Drehstrom sein. Digitalisierung macht Gleichstromantriebe weiter attraktiv

    Energy Technology Data Exchange (ETDEWEB)

    Heinrich, W. (ABB Antriebstechnik GmbH, Lampertheim (Germany))

    1992-01-31

    The stormy development of three-phase drives has replaced the dc systems in mechanical engineering and plant engineering partially, but the dc drive has managed to preserve its attractivity. Digitalisation sees to it. The progress made here is proved by the example a digital compact power converter of the second generation. (orig.).

  16. Beam Matching Study of High Current Proton Accelerator%强流质子加速器束流匹配研究

    Institute of Scientific and Technical Information of China (English)

    刘晓英; 李宏昭; 马晓燕; 傅世年

    2009-01-01

    A high current proton accelerator requires very low beam losses in order to minimize the induced radioactivity to an acceptable level. Beam matching between the different accelerator sections is one of the key points to reduce the beam losses and emittance growth. A matching design study has been performed for the beam lines between the different types of normalconducting accelerating structures. In this paper, we will present the beamline design by TRACE3D code and multiparticle simulations of the beam behavior in different matching conditions. The results show that the beam halo and emittance growth have been well controlled with the matched design of the beam lines in both transversal and longitudinal directions.%为了使感生放射性降低到可以接受的水平,强流质子加速器必须减少束流损失.不同加速段间的束流匹配是减少束流损失和发射度增长的关键之一.研究了一台常温加速结构不同段间的束流传输线的匹配设计问题.采用TRACE3-D软件以及其他多粒子模拟软件,研究了在不同匹配状态下的束流特性.结果表明,设计所采用的横向和纵向匹配手段,能够有效地控制束晕产生和束流发射度的增长.

  17. Particle-in-cell simulations of an alpha channeling scenario: electron current drive arising from lower hybrid drift instability of fusion-born ions

    Science.gov (United States)

    Cook, James; Chapman, Sandra; Dendy, Richard

    2010-11-01

    Particle-in-cell (PIC) simulations of fusion-born protons in deuterium plasmas demonstrate a key alpha channeling phenomenon for tokamak fusion plasmas. We focus on obliquely propagating modes at the plasma edge, excited by centrally born fusion products on banana orbits, known to be responsible for observations of ion cyclotron emission in JET and TFTR. A fully self-consistent electromagnetic 1D3V PIC code evolves a ring-beam distribution of 3MeV protons in a 10keV thermal deuterium-electron plasma with realistic mass ratio. A collective instability occurs, giving rise to electromagnetic field activity in the lower hybrid range of frequencies. Waves spontaneously excited by this lower hybrid drift instability undergo Landau damping on resonant electrons, drawing out an asymmetric tail in the distribution of electron parallel velocities, which constitutes a net current. These simulations demonstrate a key building block of some alpha channeling scenarios: the direct collisionless coupling of fusion product energy into a form which can help sustain the equilibrium of the tokamak.

  18. A theory of two-beam acceleration of charged particles in a plasma waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Ostrovsky, A.O. [Kharkov Inst. of Physics and Technology (Ukraine)

    1993-11-01

    The progress made in recent years in the field of high-current relativistic electron beam (REB) generation has aroused a considerable interest in studying REB potentialities for charged particle acceleration with a high acceleration rate T = 100MeV/m. It was proposed, in particular, to employ high-current REB in two-beam acceleration schemes (TBA). In these schemes high current REB (driving beam) excites intense electromagnetic waves in the electrodynamic structure which, in their turn, accelerate particles of the other beam (driven beam). The TBA schemes can be divided into two groups. The first group includes the schemes, where the two beams (driving and driven) propagate in different electrodynamic structures coupled with each other through the waveguides which ensure the microwave power transmission to accelerate driven beam particles. The second group includes the TBA schemes, where the driving and driven beams propagate in one electrodynamic structure. The main aim of this work is to demonstrate by theory the possibility of realizing effectively the TBA scheme in the plasma waveguide. The physical model of the TBA scheme under study is formulated. A set of equations describing the excitation of RF fields by a high-current REB and the acceleration of driven beam electrons is also derived. Results are presented on the the linear theory of plasma wave amplification by the driving beam. The range of system parameters, at which the plasma-beam instability develops, is defined. Results of numerical simulation of the TBA scheme under study are also presented. The same section gives the description of the dynamics of accelerated particle bunching in the high-current REB-excited field. Estimates are given for the accelerating field intensities in the plasma and electron acceleration rates.

  19. New method of a "point-like" neutron source creation based on sharp focusing of high-current deuteron beam onto deuterium-saturated target for neutron tomography

    Science.gov (United States)

    Golubev, S.; Skalyga, V.; Izotov, I.; Sidorov, A.

    2017-02-01

    A possibility of a compact powerful point-like neutron source creation is discussed. Neutron yield of the source based on deuterium-deuterium (D-D) reaction is estimated at the level of 1011 s‑1 (1013 s‑1 for deuterium-tritium reaction). The fusion takes place due to bombardment of deuterium- (or tritium) loaded target by high-current focused deuterium ion beam with energy of 100 keV. The ion beam is formed by means of high-current quasi-gasdynamic ion source of a new generation based on an electron cyclotron resonance (ECR) discharge in an open magnetic trap sustained by powerful microwave radiation. The prospects of proposed generator for neutron tomography are discussed. Suggested method is compared to the point-like neutron sources based on a spark produced by powerful femtosecond laser pulses.

  20. Recombination-current suppression in GaAs p-n junctions grown on AlGaAs buffer layers by molecular-beam epitaxy

    Science.gov (United States)

    Rancour, D. P.; Melloch, M. R.; Pierret, R. F.; Lundstrom, M. S.; Klausmeier-Brown, M. E.; Kyono, C. S.

    1987-08-01

    n+pp+GaAs and n+pP+ GaAs/GaAs/Al0.3Ga0.7As mesa diodes have been fabricated from films grown by molecular-beam epitaxy. The diodes made from films employing an AlGaAs buffer layer show marked improvements (a factor of 5 reduction) in recombination current densities. Deep level transient spectroscopy measurements moreover indicate that deep level concentrations are reduced by the AlGaAs buffer.

  1. Simulation of Sliding Efficiency for Belt Driving in Beam Pumping Units%游梁式抽油机井皮带滑动效率的仿真研究

    Institute of Scientific and Technical Information of China (English)

    邢明明; 董世民

    2013-01-01

    针对游梁式抽油机皮带传动装置负载扭矩波动大的特点,研究了游梁式抽油机皮带的纵向振动特性、皮带与带轮之间的相对滑动速度以及皮带传动的瞬时滑动效率.将皮带简化为纵向振动的弹性体,建立了皮带在交变摩擦力激励下的纵向振动力学模型与波动方程形式的数学模型;应用振型叠加法建立了皮带纵向振动的数值仿真模型;建立了皮带相对于带轮的瞬时滑动速度、瞬时滑动效率的仿真模型;仿真分析了抽油机曲柄扭矩波动幅值、皮带预紧力对皮带滑动效率的影响.仿真结果表明:抽油机曲柄扭矩波动会降低滑动效率;当抽油机曲柄扭矩存在负扭矩时,皮带滑动效率明显降低;在预紧力能保证皮带传动正常工作的情况下,再增加皮带预紧力会增大皮带的传动效率.%Considering great fluctuation of load torque of the belt driving device in a beam pumping unit,belt longitudinal vibration of beam pumping unit,the relative sliding speed between belt and pulley and instantaneous sliding efficiency were researched. The belt was simplified to elastic body of longitudinal vibration,the mechanical model of longitudinal vibration of the belt which was excited by alternating friction was established,and the mathematical model of the wave equation form was built. The numerical simulation model of wave equation was established with the superposition method of vibration mode. Simulation model of belt instantaneous sliding speed relative to pulley and simulation model of belt instantaneous sliding efficiency were established. The factors of affecting sliding efficiency were pointed out, such as oscillation amplitude of alternating torque and initial tension of belt in beam pumping unit. The following conclusions are obtained by the simulation results:load torque fluctuations of beam pumping unit will lead to lower sliding efficiency;sliding efficiency of belt driving

  2. The effect of cavity tuning on oxygen beam currents of an A-ECR type 14 GHz electron cyclotron resonance ion source.

    Science.gov (United States)

    Tarvainen, O; Orpana, J; Kronholm, R; Kalvas, T; Laulainen, J; Koivisto, H; Izotov, I; Skalyga, V; Toivanen, V

    2016-09-01

    The efficiency of the microwave-plasma coupling plays a significant role in the production of highly charged ion beams with electron cyclotron resonance ion sources (ECRISs). The coupling properties are affected by the mechanical design of the ion source plasma chamber and microwave launching system, as well as damping of the microwave electric field by the plasma. Several experiments attempting to optimize the microwave-plasma coupling characteristics by fine-tuning the frequency of the injected microwaves have been conducted with varying degrees of success. The inherent difficulty in interpretation of the frequency tuning results is that the effects of microwave coupling system and the cavity behavior of the plasma chamber cannot be separated. A preferable approach to study the effect of the cavity properties of the plasma chamber on extracted beam currents is to adjust the cavity dimensions. The results of such cavity tuning experiments conducted with the JYFL 14 GHz ECRIS are reported here. The cavity properties were adjusted by inserting a conducting tuner rod axially into the plasma chamber. The extracted beam currents of oxygen charge states O(3+)-O(7+) were recorded at various tuner positions and frequencies in the range of 14.00-14.15 GHz. It was observed that the tuner position affects the beam currents of high charge state ions up to several tens of percent. In particular, it was found that at some tuner position / frequency combinations the plasma exhibited "mode-hopping" between two operating regimes. The results improve the understanding of the role of plasma chamber cavity properties on ECRIS performances.

  3. The effect of cavity tuning on oxygen beam currents of an A-ECR type 14 GHz electron cyclotron resonance ion source

    Science.gov (United States)

    Tarvainen, O.; Orpana, J.; Kronholm, R.; Kalvas, T.; Laulainen, J.; Koivisto, H.; Izotov, I.; Skalyga, V.; Toivanen, V.

    2016-09-01

    The efficiency of the microwave-plasma coupling plays a significant role in the production of highly charged ion beams with electron cyclotron resonance ion sources (ECRISs). The coupling properties are affected by the mechanical design of the ion source plasma chamber and microwave launching system, as well as damping of the microwave electric field by the plasma. Several experiments attempting to optimize the microwave-plasma coupling characteristics by fine-tuning the frequency of the injected microwaves have been conducted with varying degrees of success. The inherent difficulty in interpretation of the frequency tuning results is that the effects of microwave coupling system and the cavity behavior of the plasma chamber cannot be separated. A preferable approach to study the effect of the cavity properties of the plasma chamber on extracted beam currents is to adjust the cavity dimensions. The results of such cavity tuning experiments conducted with the JYFL 14 GHz ECRIS are reported here. The cavity properties were adjusted by inserting a conducting tuner rod axially into the plasma chamber. The extracted beam currents of oxygen charge states O3+-O7+ were recorded at various tuner positions and frequencies in the range of 14.00-14.15 GHz. It was observed that the tuner position affects the beam currents of high charge state ions up to several tens of percent. In particular, it was found that at some tuner position / frequency combinations the plasma exhibited "mode-hopping" between two operating regimes. The results improve the understanding of the role of plasma chamber cavity properties on ECRIS performances.

  4. Beam Dynamics Studies in Recirculating Machines

    CERN Document Server

    Pellegrini, Dario; Latina, A

    The LHeC and the CLIC Drive Beam share not only the high-current beams that make them prone to show instabilities, but also unconventional lattice topologies and operational schemes in which the time sequence of the bunches varies along the machine. In order to asses the feasibility of these projects, realistic simulations taking into account the most worrisome effects and their interplays, are crucial. These include linear and non-linear optics with time dependent elements, incoherent and coherent synchrotron radiation, short and long-range wakefields, beam-beam effect and ion cloud. In order to investigate multi-bunch effects in recirculating machines, a new version of the tracking code PLACET has been developed from scratch. PLACET2, already integrates most of the effects mentioned before and can easily receive additional physics. Its innovative design allows to describe complex lattices and track one or more bunches accordingly to the machine operation, reproducing the bunch train splitting and recombinat...

  5. DRIVING GREEN

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    China is promoting environmentally friendly cars to save energy and protect the environment While people enjoy the pleasure and convenience of driving, they are also creating and breathing more and more toxic

  6. Distracted Driving

    Science.gov (United States)

    ... What's this? Submit What's this? Submit Button Distracted Driving Recommend on Facebook Tweet Share Compartir Each day in the United States, over 8 people are killed and 1,161 injured in crashes ...

  7. Generation of multi-charged high current ion beams using the SMIS 37 gas-dynamic electron cyclotron resonance (ECR) ion source

    Energy Technology Data Exchange (ETDEWEB)

    Dorf, M.A., E-mail: dorf1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Zorin, V.G.; Sidorov, A.V.; Bokhanov, A.F.; Izotov, I.V.; Razin, S.V.; Skalyga, V.A. [Institute of Applied Physics RAS, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation)

    2014-01-01

    A gas-dynamic ECR ion source (GaDIS) is distinguished by its ability to produce high current and high brightness beams of moderately charged ions. Contrary to a classical ECR ion source where the plasma confinement is determined by the slow electron scattering into an empty loss-cone, the higher density and lower electron temperature in a GaDIS plasma lead to an isotropic electron distribution with the confinement time determined by the prompt gas-dynamic flow losses. As a result, much higher ion fluxes are available; however a decrease in the confinement time of the GaDIS plasma lowers the ion charge state. The gas-dynamic ECR ion source concept has been successfully realized in the SMIS 37 experimental facility operated at the Institute of Applied Physics, Russia. The use of high-power (∼100 kW) microwave (37.5 GHz) radiation provides a dense plasma (∼10{sup 13} cm{sup −3}) with a relatively low electron temperature (∼50–100 eV) and allows for the generation of high current (∼1 A/cm{sup 2}) beams of multi-charged ions. In this work we report on the present status of the SMIS 37 ion source and discuss the advanced numerical modeling of ion beam extraction using the particle-in-cell code WARP.

  8. Generation of multi-charged high current ion beams using the SMIS 37 gas-dynamic electron cyclotron resonance (ECR) ion source

    Energy Technology Data Exchange (ETDEWEB)

    Dorf, M. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zorin, V. G. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Sidorov, A. V. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Bokhanov, A. F. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Izotov, I. V. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Razin, S. V. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Skalyga, V. A. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics

    2013-06-02

    A gas-dynamic ECR ion source (GaDIS) is distinguished by its ability to produce high current and high brightness beams of moderately charged ions. Contrary to a classical ECR ion source where the plasma confinement is determined by the slow electron scattering into an empty loss-cone, the higher density and lower electron temperature in a GaDIS plasma lead to an isotropic electron distribution with the confinement time determined by the prompt gas-dynamic flow losses. As a result, much higher ion fluxes are available, however a decrease in the confinement time of the GaDIS plasma lowers the ion charge state. The gas-dynamic ECR ion source concept has been successfully realized in the SMIS 37 experimental facility operated at the Institute of Applied Physics, Russia. The use of high-power (~100 kW) microwave (37.5 GHz) radiation provides a dense plasma (~1013 cm-3) with a relatively low electron temperature (~50- 100 eV) and allows for the generation of high current (~1 A/cm2) beams of multi-charged ions. In this work we report on the present status of the SMIS 37 ion source and discuss the advanced numerical modeling of ion beam extraction using the particle-in-cell code WARP

  9. Beam ion confinement on NSTX-U

    Science.gov (United States)

    Liu, D.; Heidbrink, W. W.; Hao, G. Z.; Podesta, M.; Darrow, D. S.; Fredrickson, E. D.

    2016-10-01

    A second and more tangential neutral beam line is a major upgrade component of the National Spherical Torus Experiment - Upgrade (NSTX-U) with the purpose of improving neutral beam current drive efficiency and providing more flexibility in current/pressure profile control. Good beam ion confinement is essential to achieve the anticipated improvements in performance. In the planned beam ion confinement experiment, various short and long (relative to fast ion slowing-down time) neutral beam (NB) pulses from six neutral beam sources will be injected into center-stack limited L-mode plasmas to characterize the beam ion confinement and distribution function produced by the new and the existing NBI lines. The neutron rate decay after the turn-off of short NB pulses will be used to estimate the beam ion confinement time and to investigate its dependence on NB source/geometry, injection energy, and plasma current. The tangential and vertical Fast-Ion D-Alpha (FIDA) diagnostics and multi-view Solid State Neutral Particle Analyzer (SSNPA) arrays will be used to measure beam ion slowing-down distribution function and spatial profile during the injection of relatively long NB pulses. Beam ion prompt losses will be monitored with a scintillator Fast Lost Ion Probe (sFLIP) diagnostic. The experimental data and comparisons with classical predictions from NUBEAM modeling will be presented. Work supported by U.S. DOE DE-AC0209CH11466, DE-FG02-06ER54867, and DE-FG03-02ER54681.

  10. Measurement of Minority Charge Carrier Diffusion Length in Gallium Nitride Nanowires Using Electron Beam Induced Current (EBIC)

    Science.gov (United States)

    2009-12-01

    column consists of a thermionic emission electron gun, several magnetic lenses that control the path and focus of the electron beam and an...barrier is affected by the magnitude of the bias as illustrated in Figure 6. The reduced barrier under forward bias is the mechanism for switching in...connected to the amplifier. Figure 66 shows the expected symmetry of the EBIC signals when the contact connected to the amplifier is switched . In

  11. Measurement of beam currents downstream from strong electric field%强电场中的脉冲束流强度测量方法

    Institute of Scientific and Technical Information of China (English)

    柯建林; 胡永宏; 周长庚; 邱瑞; 何铁; 刘玉国

    2016-01-01

    针对强电场中电场渗透的问题,采用特殊的法拉第筒法测量脉冲束流强度:在法拉第筒入口处用栅网屏蔽强电场,并用在收集板上加正压的方式抑制二次电子。采用解析计算和数值模拟方式对栅网的形状进行了选择,在同样的栅网丝宽和透过率的前提下,通过正六边形栅网的渗透电场最弱,因此选择正六边形栅网。将设计的法拉第筒用于一台真空弧离子源的束流强度测量,获得了该离子源的束流强度波形,其峰值流强约为550 mA;利用测量结果计算了混合离子束在 Cu 收集板上的二次电子发射系数,约为2.0。%A Faraday cup used for measuring the beam currents downstream from strong electric fields was designed.The strong electric field was screened by a grid.The electrons were prohibited by the positive voltage on the collector.The shape of the grid was equilateral hexagon distributed because of its lowest saturation electric field at the same grid widths and the same grid transmission rates.The beam current of a vacuum arc ion source was measured by the designed beam current measuring device and the peak value of the beam current was about 550 mA.The secondary electron yield of the Cu collector bombarded by the hy-brid ion beams was calculated to be 2.0.

  12. Stray Field Reduction in ALS Eddy Current Septum Magnets

    CERN Document Server

    Shuman, Derek; Prestemon, Soren; Schlüter, Ross D; Steier, Christoph; Stover, Gregory D

    2005-01-01

    Stray field from an eddy current septum magnet adversely affects the circulating beam and can be reduced using several techniques. The stray field time history typically has a fast rise section followed by a long exponential decay section when pulsed with a half sine drive current. Changing the drive current pulse to a full sine has the effect of both reducing peak stray field magnitude by ~3x, and producing a quick decay from this peak to a lower field level which then has a similar long decay time constant as that from the half sine only drive current pulse. A method for tuning the second half sine (reverse) drive current pulse to eliminate the long exponential decay section is given.

  13. Particle-in-cell simulation of electron trajectories and irradiation uniformity in an annular cathode high current pulsed electron beam source

    Science.gov (United States)

    Jiang, Wei; Wang, Langping; Zhou, Guangxue; Wang, Xiaofeng

    2017-02-01

    In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 mm and -15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source.

  14. Ions beams and ferroelectric plasma sources

    Science.gov (United States)

    Stepanov, Anton

    Near-perfect space-charge neutralization is required for the transverse compression of high perveance ion beams for ion-beam-driven warm dense matter experiments, such as the Neutralized Drift Compression eXperiment (NDCX). Neutralization can be accomplished by introducing a plasma in the beam path, which provides free electrons that compensate the positive space charge of the ion beam. In this thesis, charge neutralization of a 40 keV, perveance-dominated Ar+ beam by a Ferroelectric Plasma Source (FEPS) is investigated. First, the parameters of the ion beam, such as divergence due to the extraction optics, charge neutralization fraction, and emittance were measured. The ion beam was propagated through the FEPS plasma, and the effects of charge neutralization were inferred from time-resolved measurements of the transverse beam profile. In addition, the dependence of FEPS plasma parameters on the configuration of the driving pulser circuit was studied to optimize pulser design. An ion accelerator was constructed that produced a 30-50 keV Ar + beam with pulse duration ion source showed that the dependence of beam radius on Q was consistent with space charge expansion. It was concluded that the beam was perveance-dominated with a charge neutralization fraction of approximately zero in the absence of neutralizing plasma. Since beam expansion occurred primarily due to space charge, the decrease in effective perveance due to neutralization by FEPS plasma can be inferred from the reduction in beam radius. Results on propagation of the ion beam through FEPS plasma demonstrate that after the FEPS is triggered, the beam radius decreases to its neutralized value in about 5 mus. The duration of neutralization was about 10 mus at a charging voltage VFEPS = 5.5 kV and 35 mus at VFEPS = 6.5 kV. With VFEPS = 6.5 kV, the transverse current density profile 33 cm downstream of the source had a Gaussian shape with xrms =5 mm, which corresponds to a half-angle divergence of 0.87°. The

  15. SIMULATION MODEL OF TRANSMISSION EFFICIENCY OF THE BELT-DRIVING SYSTEMS OF BEAM PUMPING UNITS%游梁式抽油机皮带传动效率的仿真模型

    Institute of Scientific and Technical Information of China (English)

    邢明明; 董世民; 崔阳; 陈培毅

    2013-01-01

    A beam pumping system is of the following characteristics:1) the rotating speed of the motor changes instantaneously; 2) the load torque of a belt-driving unit fluctuates greatly; 3) the longitudinal elastic deformation of the belt changes instantaneously.With the belt simplified as two springs of no mass,and with the motor speed fluctuation,the sliding friction between the belt and the pulleys as well as the influences of the belt transmission's instantaneous load torque on the pulley sliding angle and equivalent spring stiffness taken into consideration,a dynamic simulation model of a belt driving unit of a beam pumping system is built.According to the simulation results of the driving-driven pulley's momentary speed and the instantaneous output torque of the motor,the simulation model of belt instantaneous transmission efficiency of beam pumping units is established.Simulation results show that:1) the motor rotating speed fluctuates periodically,and the higher frequency fluctuation of the motor rotating speed is made by the belt's alternating longitudinal elastic deformation; 2) there is a rotating variation loss between the driving-pulley and the driven-pulley,and the belt transmission efficiency is reduced by the driven-pulley speed loss; 3) after the system achieves a stable running state,the transmission efficiency of the belt unit changes periodically,and its varying amplitude depends on fluctuating characteristics of the load torque.Average transmission efficiency is decreasing with the load torque increasing,and it is also decreasing with the torque balance degree decreasing; 4) belt's average transmission efficiency of a beam pumping unit is usually less than 90%.When the load torque is bigger and the torque balance degree is smaller,it is possible that the average transmission efficiency of the belt driving unit is less than 85%.%针对游梁式抽油机电动机转速存在波动、皮带传动负载扭矩波动大、皮带纵向弹性变形交变

  16. Progress in direct-drive inertial confinement fusion research at the laboratory for laser energetics

    Energy Technology Data Exchange (ETDEWEB)

    McCrory, R.L.; Meyerhofer, D.D.; Loucks, J.; Skupsky, S.; Betti, R.; Boehly, T.R.; Collins, T.J.B.; Craxton, R.S.; Delettrez, J.A.; Edgell, D.H.; Epstein, R.; Glebov, V.Y.; Goncharov, V.N.; Harding, D.R.; Igumenshchev, I.V.; Keck, R.L.; Kilkenny, J.D.; Knauer, J.P.; Marciante, J.; Marozas, J.A.; Marshall, F.J.; Maximov, A.V.; McKenty, P.W.; Morse, S.F.B.; Myatt, J.; Radha, P.B.; Regan, S.P.; Sangster, T.C.; Seka, W.; Smalyuk, V.A.; Soures, J.M.; Stoeckl, C.; Yaakobi, B.; Zuegel, J.D. [Rochester Univ., Lab. for Laser Energetics, NY (United States); McCrory, R.L.; Meyerhofer, D.D.; Betti, S.R.; Goncharov, V.N. [Rochester Univ., Dept. of Mechanical Engineering and Physics and Astronomy, NY (United States); Fletcher, A.; Freeman, C.; Padalino, S. [SUNY Geneseo, Geneseo, NY (United States); Frenje, J.A.; Li, C.K.; Petrasso, R.D.; Seguin, F.H. [Plasma Science and Fusion Center, MIT, Cambridge, MA (United States); Kilkenny, J.D. [General Atomics, San Diego, CA (United States)

    2007-08-15

    Direct-drive inertial confinement fusion (ICF) is expected to demonstrate high gain on the National Ignition Facility (NIF) in the next decade and is a leading candidate for inertial fusion energy production. The demonstration of high areal densities in hydro-dynamically scaled cryogenic DT or D{sub 2} implosions with neutron yields that are a significant fraction of the 'clean' 1-D predictions will validate the ignition-equivalent direct-drive target performance on the OMEGA laser at the Laboratory for Laser Energetics (LLE). This paper highlights the recent experimental and theoretical progress leading toward achieving this validation in the next few years. The NIF will initially be configured for X-ray drive and with no beams placed at the target equator to provide a symmetric irradiation of a direct-drive capsule. LLE is developing the 'polar-direct-drive' (PDD) approach that directs beams toward the target equator. Initial 2-dimensional simulations have shown ignition. A unique 'Saturn-like' plastic ring around the equator refracts the laser light incident near the equator toward the target, improving the drive uniformity. LLE is currently constructing the multibeam, 2.6-kJ/beam, peta-watt laser system OMEGA-EP (Extended Performance). Integrated fast-ignition experiments, combining the OMEGA-EP and OMEGA Laser Systems, will begin in 2008. (authors)

  17. Detailed magnetic model simulations of the H- injection chicane magnets for the CERN PS Booster Upgrade, including eddy currents and influence on beam dynamics

    CERN Document Server

    Benedetto, E; Borburgh, J; Carli, C; Martini, M; Forte, V

    2014-01-01

    The CERN PS Booster will be upgraded with an H- injection system. The chicanemagnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The -beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and correction on beam dynamics.

  18. An Insight into the Time Domain Phenomenon during the Transition Zone from Induction Motor to Synchronous Motor Mode for a Current Source Inverter Fed Synchronous Motor Drive System

    OpenAIRE

    A.B. Chattopadhyay; Sunil Thomas

    2014-01-01

    Modeling of synchronous motor plays a dominant role in designing complicated drive system for different applications, especially large blower fans etc., for steel industries. As synchronous motor has no inherent starting torque generally it is started as an induction motor with the help of a damper winding and it pulls into synchronism under certain conditions. The present study exactly concentrates on this particular zone of transition from induction motor to synchronous motor mode for a cur...

  19. 一个新的适用于无刷直流电机驱动的单电流传感器技术%A Novel Current Sensor Technique for Brushless DC Motor Drives

    Institute of Scientific and Technical Information of China (English)

    谭徽; 江建中; 汪信尧; 王勇

    2000-01-01

    The torque output in a permanent magnet brushless DC motor (BLDCM) is usually controlled by regulating the motor phase currents. In this paper, three kinds of PWM strategies together with some critical review on traditional current measurements in a BLDCM drive system are discussed. A novel method for assessing the PWM information and measuring the motor phase currents by a dc link current sensor is proposed. An attractive feature of the proposed method is the simplicity with the current sample processing because there is no need to incorporate the conduction information of the power switches or diodes. Only the single sided PWM or the double sided complementary PWM is needed with the proposed technique.

  20. Observation of Muon Neutrino Charged Current Events in an Off-Axis Horn-Focused Neutrino Beam Using the NOvA Prototype Detector

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Enrique Arrieta [Michigan State Univ., East Lansing, MI (United States)

    2014-01-01

    The NOνA is a long base-line neutrino oscillation experiment. It will study the oscillations between muon and electron neutrinos through the Earth. NOνA consists of two detectors separated by 810 km. Each detector will measure the electron neutrino content of the neutrino (NuMI) beam. Differences between the measurements will reveal details about the oscillation channel. The NOνA collaboration built a prototype detector on the surface at Fermilab in order to develop calibration, simulation, and reconstruction tools, using real data. This 220 ton detector is 110 mrad off the NuMI beam axis. This off-axis location allows the observation of neutrino interactions with energies around 2 GeV, where neutrinos come predominantly from charged kaon decays. During the period between October 2011 and April 2012, the prototype detector collected neutrino data from 1.67 × 1020 protons on target delivered by the NuMI beam. This analysis selected a number of candidate charged current muon neutrino events from the prototype data, which is 30% lower than predicted by the NOνA Monte Carlo simulation. The analysis suggests that the discrepancy comes from an over estimation of the neutrino flux in the Monte Carlo simulation, and in particular, from neutrinos generated in charged kaon decays. The ratio of measured divided by the simulated flux of muon neutrinos coming from charged kaon decays is: 0.70+0.108 -0.094. The NOνA collaboration may use the findings of this analysis to introduce a more accurate prediction of the neutrino flux produced by the NuMI beam in future Monte Carlo simulations.