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Sample records for current drive power

  1. Critical power for lower hybrid current drive

    International Nuclear Information System (INIS)

    Assis, A.S. de; Sakanaka, P.H.; Azevedo, C.A. de; Busnardo-Neto, J.

    1995-11-01

    We have solved numerically the quasilinear Fokker-Planck equation which models the critical power for lower hybrid wave current drive. An exact value for the critical power necessary for current saturation, for tokamak current drive experiments, has been obtained. The nonlinear treatment presented here leads to a final profile for the parallel distribution function which is a plateau only in a part of the resonance region. This form of the distribution function is intermediate between two well known results: a plateau throughout the resonance region for the linear strong-source regime, D wave >> D coll and no plateau at all in the resonance region the linear weak-source regimen, D wave coll . The strength of the external power source and the value of the dc electric field are treated as given parameters in the integration scheme. (author). 24 refs, 6 figs

  2. Power and momentum relations in rotating magnetic field current drive

    Energy Technology Data Exchange (ETDEWEB)

    Hugrass, W N [Flinders Univ. of South Australia, Bedford Park. School of Physical Sciences

    1984-01-01

    The use of rotating magnetic fields (RMF) to drive steady currents in plasmas involves a transfer of energy and angular momentum from the radio frequency source feeding the rotating field coils to the plasma. The power-torque relationships in RMF systems are discussed and the analogy between RMF current drive and the polyphase induction motor is explained. The general relationship between the energy and angular momentum transfer is utilized to calculate the efficiency of the RMF plasma current drive. It is found that relatively high efficiencies can be achieved in RMF current drive because of the low phase velocity and small slip between the rotating field and the electron fluid.

  3. Direct Drive Generator for Renewable Power Conversion from Water Currents

    International Nuclear Information System (INIS)

    Segergren, Erik

    2005-01-01

    In this thesis permanent magnet direct drive generator for power conversion from water currents is studied. Water currents as a power source involves a number of constrains as well as possibilities, especially when direct drive and permanent magnets are considered. The high power fluxes and low current velocities of a water current, in combination with its natural variations, will affect the way the generator is operated and, flowingly, the appearance of the generator. The work in this thesis can, thus, be categorized into two general topics, generator technology and optimization. Under the first topic, fundamental generator technology is used to increase the efficiency of a water current generator. Under the latter topic, water current generators are optimized to a specific environment. The conclusion drawn from this work is that it is possible to design very low speed direct drive generators with good electromagnetic properties and wide efficiency peak

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

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

    International Nuclear Information System (INIS)

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

    1994-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-01-01

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

  7. Fast wave current drive

    International Nuclear Information System (INIS)

    Goree, J.; Ono, M.; Colestock, P.; Horton, R.; McNeill, D.; Park, H.

    1985-07-01

    Fast wave current drive is demonstrated in the Princeton ACT-I toroidal device. The fast Alfven wave, in the range of high ion-cyclotron harmonics, produced 40 A of current from 1 kW of rf power coupled into the plasma by fast wave loop antenna. This wave excites a steady current by damping on the energetic tail of the electron distribution function in the same way as lower-hybrid current drive, except that fast wave current drive is appropriate for higher plasma densities

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

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  9. Power deposition profile during lower hybrid current drive in Tore Supra

    International Nuclear Information System (INIS)

    Pecquet, A.L.; Moreau, D.; Fall, T.; Lasalle, J.; Lecoustey, P.; Mattioli, M.; Peysson, Y.; Auge, N.; Rodriguez, L.; Talvard, M.; Hubbard, A.; Moret, J.M.

    1991-01-01

    Lower hybrid current drive (LHCD) experiments have been performed in Tore Supra in various density regimes. The total power coupled to the plasma reached 4MW and a strong electron heating has been observed. To investigate the power deposition mechanism on the electrons, r.f power modulation experiments have been performed. These experiments allow us to estimate the power deposition profiles on both thermal and non-thermal electrons and also to study their respective time responses. From these studies it is possible to deduce a thermal heating scenario which agrees with the experimental results

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

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2010-01-01

    In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring...... the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress...

  11. ENHANCING THE OPERATIONAL EFFICIENCY OF DIRECT CURRENT DRIVE BASED ON USE OF SUPERCONDENSER POWER STORAGE UNITS

    Directory of Open Access Journals (Sweden)

    А. M. Mukha

    2017-10-01

    Full Text Available Purpose.The scientific work is intended to analyse the expansion of the load range and the implementation of regeneration braking (RB of the direct current drive by using the supercondenser power storage units. Methodology.To solve the problem, we use the methods of the electric drive theory, impulse electronics and the method of calculation of transient electromagnetic processes in linear electric circuits in the presence of super-condensers therein. Findings.The stiffness of the mechanical and electromechanical characteristics of a series motor is significantly increased, which makes it possible to use a DC drive under load, much smaller than 15…20% of the nominal one. Numerical calculations of the operation process of the supercondenser power storage unit were fulfilled with a sharp decrease in the load of a traction electric motor of a direct current electric locomotive. The possibility of RB of the direct current drive with the series motor is substantiated. The equations of the process of charging and discharging of super-condenser storage unit in RB mode are solved. The authors examined the effect of capacitance on the nature of maintaining the excitation current of an electric motor in the mode of small loads.Originality.The paper developed theoretical approaches for the transformation of soft (mechanical and electromechanical characteristics into hard ones of DC series motors. For the first time a new, combined method of the series motor RB is proposed and substantiated. Further development obtained the methods for evaluating the storage unit parameters, taking into account the criteria for reliable parallel operation of super-condensers with an electric motor field. Practical value.The proposed and substantiated transformation of soft characteristics into stiff ones allows us to use general-purpose electric drives with series motors and at low loads, and in traction electric drives - to reduce the intensity of electric stockwheel

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

    International Nuclear Information System (INIS)

    Gassmann, T.; Arambhadiya, B.; Beaumont, B.; Baruah, U.K.; Bonicelli, T.; Darbos, C.; Purohit, D.; Decamps, H.; Albajar, F.; Gandini, F.; Henderson, M.; Kazarian, F.; Lamalle, P.U.; Omori, T.; Parmar, D.; Patel, A.; Rathi, D.; Singh, N.P.

    2011-01-01

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

  13. On the dynamics of the power spectrum during lower hybrid current drive in Tokamaks

    International Nuclear Information System (INIS)

    Bizarro, J.P.

    1993-01-01

    An investigation is provided on the propagation and absorption of the power spectrum during lower hybrid current drive in Tokamaks. A combined ray tracing and Fokker-Planck code is utilized and stochastic effects induced by toroidicity are correctly taken into account by using a large number of rays. It is shown that when strong wave damping prevails the absorbed spectrum is very similar in shape to the launched one, although some broadening and shifting in parallel wave index generally occur, and power deposition is localized. If the wave damping is weak and stochastic effects are important, rays end up sweeping the entire plasma cross-section, power deposition turns out to be extended, and the absorbed spectrum is much broader than the launched one

  14. Optimum launching of electron-cyclotron power for localized current drive in a hot tokamak

    International Nuclear Information System (INIS)

    Smith, G.R.

    1989-05-01

    Optimum launch parameters are determined for localized electron-cyclotron current drive near the magnetic axis and the q=2 surface by solving several minimization problems. For central current drive, equatorial and bottom launch are compared. Localized current drive near q=2 is studied for equatorial launch and for an alternative outside launch geometry that may be better for suppressing tearing modes and controlling disruptions. 6 refs., 2 figs

  15. High power tests of beryllium oxide windows to the lower hybrid current drive launcher in JET

    International Nuclear Information System (INIS)

    Ekedahl, A.; Brandon, M.; Finburg, P.

    1999-01-01

    The vacuum windows to the 3.70 GHz Lower Hybrid Current Drive (LHCD) system in JET were originally designed to withstand 350 kW for 20 s with VSWR ≤ 1.8. High power RF tests of the windows have been carried out in the LHCD test facility at JET. All windows that were tested could operate at 500 kW for 10 s in a matched load. Two windows passed an endurance test at 250 kW for 20 s with the windows terminated in a short circuit. One window also passed this endurance test without active cooling. The results show that this type of window can be used in a new advanced launcher, as proposed for ITER, in which the output power from each klystron (P ≤ 500 kW) will be transmitted through one waveguide and one vacuum window. (author)

  16. Development of high-power inverter supply for current drive of FRC plasma

    International Nuclear Information System (INIS)

    Kitano, Katsuhisa; Higashikozono, Takamitsu; Okada, Shigefumi; Goto, Seiichi

    2003-01-01

    High-Power RF supply is developed for the current drive of FRC (Field Reversed Configuration) plasma. The rotating magnetic field is produced by the four antennas set in the parallel direction to the geometrical axis of the FRC and faced each other. The sinusoidal currents with shifted phases by 90 degree each other should be supplied to the antennas. The two power supplies are necessary if a pair of the antennas faced oppositely are connected. Considering the plasma parameters, the rotating field of 50-100kHz and 50G at the center axis is expected to be required. We develop the adequate RF power supply for the purpose. The power supply consists of the inverter circuit, the step-up transformer and the LC tank ciruit. For the switching device of the inverter circuit, the IGBT (Insulated Gate Bipolar Transistor) is adopted. The inverter circuit is full bridge type. To operate it at high voltages, its arm consists of the 3 IGBTs arranged series. The output of the inverter is connected to the tank circuit by way of the step-up transformer with air core. The tank circuit is the parallel circuit of the antenna and the capacitor. By the adjustment of the frequency of the inverter output to the resonance frequency of the tank circuit, the large sinusoidal waveform current is obtained. The developed power supply can produce the current of 5kA at 10kV to the dummy antenna with almost the same inductance of the antenna. (author)

  17. Modulated Current Drive Measurements

    International Nuclear Information System (INIS)

    Petty, C.C.; Lohr, J.; Luce, T.C.; Prater, R.; Cox, W.A.; Forest, C.B.; Jayakumar, R.J.; Makowski, M.A.

    2005-01-01

    A new measurement approach is presented which directly determines the noninductive current profile from the periodic response of the motional Stark effect (MSE) signals to the slow modulation of the external current drive source. A Fourier transform of the poloidal magnetic flux diffusion equation is used to analyze the MSE data. An example of this measurement technique is shown using modulated electron cyclotron current drive (ECCD) discharges from the DIII-D tokamak

  18. Turbulent current drive mechanisms

    Science.gov (United States)

    McDevitt, Christopher J.; Tang, Xian-Zhu; Guo, Zehua

    2017-08-01

    Mechanisms through which plasma microturbulence can drive a mean electron plasma current are derived. The efficiency through which these turbulent contributions can drive deviations from neoclassical predictions of the electron current profile is computed by employing a linearized Coulomb collision operator. It is found that a non-diffusive contribution to the electron momentum flux as well as an anomalous electron-ion momentum exchange term provide the most efficient means through which turbulence can modify the mean electron current for the cases considered. Such turbulent contributions appear as an effective EMF within Ohm's law and hence provide an ideal means for driving deviations from neoclassical predictions.

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

    International Nuclear Information System (INIS)

    Maebara, S.; Seki, M.; Ikeda, Y.; Kiyono, K.; Suganuma, K.; Imai, T.; Goniche, M.; Bibet, Ph.; Brossaud, J.; Cano, V.; Kazarian-Vibert, F.; Froissard, P.; Rey, G.

    1998-01-01

    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 2 were performed with no breakdowns on the CFC module. It was also checked that the highest power density, up to 150 MW/m 2 , could be transmitted when the waveguides are filled with H2 at a pressure of 5 x 10 -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)

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

    International Nuclear Information System (INIS)

    Sharma, P.K.; Kazarian, F.; Garibaldi, P.; Gassman, T.; Artaud, J.F.; Bae, Y.S.; Belo, J.; Berger-By, G.; Bernard, J.M.; Cara, Ph.; Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Cesario, R.; Decker, J.; Delpech, L.; Ekedahl, A.; Garcia, J.; Goniche, M.; Guilhem, D.

    2011-01-01

    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.

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

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2011-01-01

    The widely used cascade speed and torque controllers have a limited control performance in most high power applications due to the low switching frequency of power electronic converters and the convenience to avoid speed overshoots and oscillations for lifetime considerations. Model Predictive...... Direct Current Control (MPDCC) leads to an increase of torque control performance taking into account the discrete nature of inverters but temporary offsets and poor responses to load torque variations are still issues in speed control. A load torque estimator is proposed in this paper in order...

  3. Electron cyclotron heating/current-drive system using high power tubes for QUEST spherical tokamak

    Science.gov (United States)

    Onchi, Takumi; Idei, H.; Hasegawa, M.; Nagata, T.; Kuroda, K.; Hanada, K.; Kariya, T.; Kubo, S.; Tsujimura, T. I.; Kobayashi, S.; Quest Team

    2017-10-01

    Electron cyclotron heating (ECH) is the primary method to ramp up plasma current non-inductively in QUEST spherical tokamak. A 28 GHz gyrotron is employed for short pulses, where the radio frequency (RF) power is about 300 kW. Current ramp-up efficiency of 0.5 A/W has been obtained with focused beam of the second harmonic X-mode. A quasi-optical polarizer unit has been newly installed to avoid arcing events. For steady-state tokamak operation, 8.56 GHz klystron with power of 200 kW is used as the CW-RF source. The high voltage power supply (54 kV/13 A) for the klystron has been built recently, and initial bench test of the CW-ECH system is starting. The array of insulated-gate bipolar transistor works to quickly cut off the input power for protecting the klystron. This work is supported by JSPS KAKENHI (15H04231), NIFS Collaboration Research program (NIFS13KUTR085, NIFS17KUTR128), and through MEXT funding for young scientists associated with active promotion of national university reforms.

  4. Design and RF test result of High Power Hybrid Combiner for Helicon Wave Current Drive in KSTAR Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. Y.; Kim, H. J.; Wi, H. H.; Wang, S. J.; Kwak, J. G. [NFRI, Daejeon (Korea, Republic of)

    2016-05-15

    200 kW RF power will be injected to plasmas through the traveling wave antenna after combining four klystrons output powers using three hybrid combiners. Each klystron produces 60 kW output at the frequency of 500 MHz. RF power combiners commonly used to divide or combine output powers for various rf and microwave applications. It is divided into several types according to the design type such as Wilkinson combiner, radial and quadrature hybrid combiner. We designed high power hybrid combiners using 6-1/8 inch coaxial line. The power combiner has many advantages such as high isolation, low insertion loss and high power handling capability. In this paper design and rf test results of high power combiners will be described. High power combiners using three coaxial hybrid couplers will be utilized for effectively combining of 500 MHz, 200 kW output powers generated by four klystrons. We have designed, fabricated, and tested a 6-1/8 inch coaxial hybrid combiners at 500 MHz for efficiently off-axis Helicon wave current drive in KSTAR. Simulation and test results of high power coaxial hybrid combiners are good agreement.

  5. Lower hybrid current drive and heating experiments at the 1 MW rf power level on Alcator C

    International Nuclear Information System (INIS)

    Porkolab, M.; Lloyd, B.; Schuss, J.J.

    1983-07-01

    Lower hybrid current drive experiments were carried out in the density range 1.0 x 10 13 less than or equal to anti n(cm -3 ) less than or equal to 1.0 x 10 14 , at magnetic fields 6.0 less than or equal to B(T) less than or equal to 10. Using one 16 waveguide array, plasma currents of 150 to 200 kA have been driven by rf powers up to 600 kW for times greater than 100 msec at anti n/sub e/ up to 5 x 10 13 cm -3 . With two arrays at anti n/sub e/ approx. = 4.3 x 10 13 cm -3 at B/sub T/ = 10 T, plasma currents of 160 kA have been maintained by the rf power for 300 msec with zero loop voltage and constant internal inductance

  6. Assessment of quasi-linear effect of RF power spectrum for enabling lower hybrid current drive in reactor plasmas

    Science.gov (United States)

    Cesario, Roberto; Cardinali, Alessandro; Castaldo, Carmine; Amicucci, Luca; Ceccuzzi, Silvio; Galli, Alessandro; Napoli, Francesco; Panaccione, Luigi; Santini, Franco; Schettini, Giuseppe; Tuccillo, Angelo Antonio

    2017-10-01

    The main research on the energy from thermonuclear fusion uses deuterium plasmas magnetically trapped in toroidal devices. To suppress the turbulent eddies that impair thermal insulation and pressure tight of the plasma, current drive (CD) is necessary, but tools envisaged so far are unable accomplishing this task while efficiently and flexibly matching the natural current profiles self-generated at large radii of the plasma column [1-5]. The lower hybrid current drive (LHCD) [6] can satisfy this important need of a reactor [1], but the LHCD system has been unexpectedly mothballed on JET. The problematic extrapolation of the LHCD tool at reactor graded high values of, respectively, density and temperatures of plasma has been now solved. The high density problem is solved by the FTU (Frascati Tokamak Upgrade) method [7], and solution of the high temperature one is presented here. Model results based on quasi-linear (QL) theory evidence the capability, w.r.t linear theory, of suitable operating parameters of reducing the wave damping in hot reactor plasmas. Namely, using higher RF power densities [8], or a narrower antenna power spectrum in refractive index [9,10], the obstacle for LHCD represented by too high temperature of reactor plasmas should be overcome. The former method cannot be used for routinely, safe antenna operations, Thus, only the latter key is really exploitable in a reactor. The proposed solutions are ultimately necessary for viability of an economic reactor.

  7. RF power diagnostics and control on the DIII-D, 4 MW 30--120 MHz fast wave current drive system (FWCD)

    International Nuclear Information System (INIS)

    Ferguson, S.W.; Allen, J.C.; Callis, R.W.; Cary, W.P.; Harris, T.E.

    1995-10-01

    The Fast Wave Current Drive System uses three 2 MW transmitters to drive three antennas inside the DIII-D vacuum vessel. This paper describes the diagnostics for this system. The diagnostics associated with the General Atomics Fast Wave Current Drive System allow the system tuning to be analyzed and modified on a between shot basis. The transmitters can be exactly tuned to match the plasma with only one tuning shot into the plasma. This facilitates maximum rf power utilization

  8. Noninductive current drive in tokamaks

    International Nuclear Information System (INIS)

    Uckan, N.A.

    1985-01-01

    Various current drive mechanisms may be grouped into four classes: (1) injection of energetic particle beams; (2) launching of rf waves; (3) hybrid schemes, which are combinations of various rf schemes (rf plus beams, rf and/or beam plus ohmic heating, etc.); and (4) other schemes, some of which are specific to reactor plasma conditions requiring the presence of alpha particle or intense synchrotron radiation. Particle injection schemes include current drive by neutral beams and relativistic electron beams. The rf schemes include current drive by the lower hybrid (LH) waves, the electron waves, the waves in the ion cyclotron range of frequencies, etc. Only a few of these approaches, however, have been tested experimentally, with the broadest data base available for LH waves. Included in this report are (1) efficiency criteria for current drive, (2) current drive by neutral beam injection, (3) LH current drive, (4) electron cyclotron current drive, (5) current drive by ion cyclotron waves - minority species heating, and (6) current drive by other schemes (such as hybrids and low frequency waves)

  9. 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

  10. The dynomak: An advanced spheromak reactor concept with imposed-dynamo current drive and next-generation nuclear power technologies

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, D.A., E-mail: das1990@uw.edu; Jarboe, T.R.; Morgan, K.D.; Pfaff, M.; Lavine, E.S.; Kamikawa, Y.; Hughes, M.; Andrist, P.; Marklin, G.; Nelson, B.A.

    2014-04-15

    A high-β spheromak reactor concept has been formulated with an estimated overnight capital cost that is competitive with conventional power sources. This reactor concept utilizes recently discovered imposed-dynamo current drive (IDCD) and a molten salt (FLiBe) blanket system for first wall cooling, neutron moderation and tritium breeding. Currently available materials and ITER-developed cryogenic pumping systems were implemented in this concept from the basis of technological feasibility. A tritium breeding ratio (TBR) of greater than 1.1 has been calculated using a Monte Carlo N-Particle (MCNP5) neutron transport simulation. High temperature superconducting tapes (YBCO) were used for the equilibrium coil set, substantially reducing the recirculating power fraction when compared to previous spheromak reactor studies. Using zirconium hydride for neutron shielding, a limiting equilibrium coil lifetime of at least thirty full-power years has been achieved. The primary FLiBe loop was coupled to a supercritical carbon dioxide Brayton cycle due to attractive economics and high thermal efficiencies. With these advancements, an electrical output of 1000 MW from a thermal output of 2486 MW was achieved, yielding an overall plant efficiency of approximately 40%.

  11. Starlite figures of merit for tokamak current drive - economic analysis of pulsed and steady state power plants with various engineering and physics performance parameters

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1995-09-01

    The physics efficiency of current drive (γ B ∝ n e I o R o /P CD ), including the bootstrap effect, needs to exceed certain goals in order to provide economical steady state operation compared to pulsed power plants. The goal for γ B depends not only on engineering performance of the current drive system, but also on normalized beta and the effective safety factor of the achievable MHD equilibrium

  12. STARLITE figures of merit for tokamak current drive -- Economic analysis of pulsed and steady state power plants with various engineering and physics performance parameters

    International Nuclear Information System (INIS)

    Ehst, D.A.; Jardin, S.; Kessel, C.

    1995-10-01

    The physics efficiency of current drive (γ B ∝ n e I 0 R 0 /P CD ), including the bootstrap effect, needs to exceed certain goals in order to provide economical steady state operation compared to pulsed power plants. The goal for γ B depends not only on engineering performance of the current drive system, but also on normalized beta and the effective safety factor of the achievable MHD equilibrium

  13. Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER

    Science.gov (United States)

    Chapman, I. T.; Graves, J. P.; 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

    2013-06-01

    13 MW 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 neoclassical 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 α particle stabilization 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 significantly increases, the negative effect on the fusion gain is reduced, and off-axis negative-ion neutral beam injection (NNBI) can also be considered for sawtooth control. Consequently, schemes to reduce the q = 1 radius are highly desirable, such as early heating to delay the current penetration and, of course, active sawtooth destabilization to mediate small frequent sawteeth and retain a small q = 1 radius. Finally, there remains a residual risk that the ECCD + ICRH control actuators cannot keep the sawtooth period below the threshold for triggering NTMs (since this is derived only from empirical scaling and the control modelling has numerous caveats). If this is the case, a secondary control scheme of sawtooth stabilization via ECCD + ICRH + NNBI, interspersed with deliberate triggering of a crash through auxiliary power reduction and simultaneous pre-emptive NTM control by off-axis ECCD has been considered, permitting long transient periods with high fusion

  14. Lower hybrid current drive in tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ushigusa, Kenkichi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1999-03-01

    Past ten years progress on Lower Hybrid Current Drive (LHCD) experiments have demonstrated the largest non-inductive current (3.6 MA, JT-60U), the longest current sustainment (2 hours, TRIAM-1M), non-inductive current drive at the highest density (n-bar{sub e} - 10{sup 20}m{sup -3}, ALCATOR-C) and the highest current drive efficiency ({eta}{sub CD} = 3.5x10{sup 19} m{sup -2}A/W, JT-60). These results indicate that LHCD is one of the most promising methods to drive non-inductive current in the present tokamak plasmas. This paper presents recent experimental results on LHCD experiments. Basic theories of LH waves, the wave propagation and the current drive are briefly summarized. The main part of this paper describes several important results and their physical pictures on recent LHCD experiments; 1) the experimental set-up, 2) the current drive efficiency, 3) the control of current profile and MHD activities, 4) the global energy confinement, 5) the global power flow, 6) fast electron behavior, 7) interaction between LH waves and thermal/fast ions, 8) combination with other CD method. (author)

  15. Lower hybrid current drive in tokamak plasmas

    International Nuclear Information System (INIS)

    Ushigusa, Kenkichi

    1999-03-01

    Past ten years progress on Lower Hybrid Current Drive (LHCD) experiments have demonstrated the largest non-inductive current (3.6 MA, JT-60U), the longest current sustainment (2 hours, TRIAM-1M), non-inductive current drive at the highest density (n-bar e - 10 20 m -3 , ALCATOR-C) and the highest current drive efficiency (η CD = 3.5x10 19 m -2 A/W, JT-60). These results indicate that LHCD is one of the most promising methods to drive non-inductive current in the present tokamak plasmas. This paper presents recent experimental results on LHCD experiments. Basic theories of LH waves, the wave propagation and the current drive are briefly summarized. The main part of this paper describes several important results and their physical pictures on recent LHCD experiments; 1) the experimental set-up, 2) the current drive efficiency, 3) the control of current profile and MHD activities, 4) the global energy confinement, 5) the global power flow, 6) fast electron behavior, 7) interaction between LH waves and thermal/fast ions, 8) combination with other CD method. (author)

  16. Experimental characterization and modelling of non-linear coupling of the lower hybrid current drive power on Tore Supra

    Science.gov (United States)

    Preynas, M.; Goniche, M.; Hillairet, J.; Litaudon, X.; Ekedahl, A.; Colas, L.

    2013-01-01

    To achieve steady-state operation on future fusion devices, in particular on ITER, the coupling of the lower hybrid wave must be optimized on a wide range of edge conditions. However, under some specific conditions, deleterious effects on the lower hybrid current drive (LHCD) coupling are sometimes observed on Tore Supra. In this way, dedicated LHCD experiments have been performed using the LHCD system of Tore Supra, composed of two different conceptual designs of launcher: the fully active multi-junction (FAM) and the new passive active multi-junction (PAM) antennas. A non-linear interaction between the electron density and the electric field has been characterized in a thin plasma layer in front of the two LHCD antennas. The resulting dependence of the power reflection coefficient (RC) with the LHCD power is not predicted by the standard linear theory of the LH wave coupling. A theoretical model is suggested to describe the non-linear wave-plasma interaction induced by the ponderomotive effect and implemented in a new full wave LHCD code, PICCOLO-2D (ponderomotive effect in a coupling code of lower hybrid wave-2D). The code self-consistently treats the wave propagation in the antenna vicinity and its interaction with the local edge plasma density. The simulation reproduces very well the occurrence of a non-linear behaviour in the coupling observed in the LHCD experiments. The important differences and trends between the FAM and the PAM antennas, especially a larger increase in RC for the FAM, are also reproduced by the PICCOLO-2D simulation. The working hypothesis of the contribution of the ponderomotive effect in the non-linear observations of LHCD coupling is therefore validated through this comprehensive modelling for the first time on the FAM and PAM antennas on Tore Supra.

  17. Experimental characterization and modelling of non-linear coupling of the lower hybrid current drive power on Tore Supra

    International Nuclear Information System (INIS)

    Preynas, M.; Goniche, M.; Hillairet, J.; Litaudon, X.; Ekedahl, A.; Colas, L.

    2013-01-01

    To achieve steady-state operation on future fusion devices, in particular on ITER, the coupling of the lower hybrid wave must be optimized on a wide range of edge conditions. However, under some specific conditions, deleterious effects on the lower hybrid current drive (LHCD) coupling are sometimes observed on Tore Supra. In this way, dedicated LHCD experiments have been performed using the LHCD system of Tore Supra, composed of two different conceptual designs of launcher: the fully active multi-junction (FAM) and the new passive active multi-junction (PAM) antennas. A non-linear interaction between the electron density and the electric field has been characterized in a thin plasma layer in front of the two LHCD antennas. The resulting dependence of the power reflection coefficient (RC) with the LHCD power is not predicted by the standard linear theory of the LH wave coupling. A theoretical model is suggested to describe the non-linear wave–plasma interaction induced by the ponderomotive effect and implemented in a new full wave LHCD code, PICCOLO-2D (ponderomotive effect in a coupling code of lower hybrid wave-2D). The code self-consistently treats the wave propagation in the antenna vicinity and its interaction with the local edge plasma density. The simulation reproduces very well the occurrence of a non-linear behaviour in the coupling observed in the LHCD experiments. The important differences and trends between the FAM and the PAM antennas, especially a larger increase in RC for the FAM, are also reproduced by the PICCOLO-2D simulation. The working hypothesis of the contribution of the ponderomotive effect in the non-linear observations of LHCD coupling is therefore validated through this comprehensive modelling for the first time on the FAM and PAM antennas on Tore Supra. (paper)

  18. Synergy in RF Current Drive

    International Nuclear Information System (INIS)

    Dumont, R.J.; Giruzzi, G.

    2005-01-01

    Auxiliary methods for efficient non-inductive current drive in tokamaks generally involve the interaction of externally driven waves with superthermal electrons. Among the possible schemes, Lower Hybrid (LH) and Electron Cyclotron (EC) current drive have been so far the most successful. An interesting aspect of their combined use is the fact that since they involve possibly overlapping domains in velocity and configuration spaces, a synergy between them is expected for appropriate parameters. The signature of this effect, significant improvement of the EC current drive efficiency, results from a favorable interplay of the quasilinear diffusions induced by both waves. Recently, improvements of the EC current drive efficiency in the range of 2-4 have been measured in fully non-inductive discharges in the Tore Supra tokamak, providing the first clear evidence of this effect in steady-state conditions. We present here the experimental aspects of these discharges. The associated kinetic modeling and current state of understanding of the LH-EC synergy phenomenon are also discussed. (authors)

  19. Synergy in RF Current Drive

    International Nuclear Information System (INIS)

    Dumont, R.J.; Giruzzi, G.

    2005-01-01

    Auxiliary methods for efficient non-inductive current drive in tokamaks generally involve the interaction of externally driven waves with superthermal electrons. Among the possible schemes, Lower Hybrid (LH) and Electron Cyclotron (EC) current drive have been so far the most successful. An interesting aspect of their combined use is the fact that since they involve possibly overlapping domains in velocity and configuration spaces, a synergy between them is expected for appropriate parameters. The signature of this effect, significant improvement of the EC current drive efficiency, results from a favorable interplay of the quasilinear diffusions induced by both waves. Recently, improvements of the EC current drive efficiency in the range of 2-4 have been measured in fully non-inductive discharges in the Tore Supra tokamak, providing the first clear evidence of this effect in steady-state conditions. We present here the experimental aspects of these discharges. The associated kinetic modeling and current state of understanding of the LH-EC synergy phenomenon are also discussed

  20. Current drive for rotamak plasmas

    Indian Academy of Sciences (India)

    Abstract. Experiments which have been undertaken over a number of years have shown that a rotating magnetic field can drive a significant non-linear Hall current in a plasma. Successful experiments of this concept have been made with a device called rotamak. In its original configuration this device was a field reversed ...

  1. Low frequency rf current drive

    International Nuclear Information System (INIS)

    Hershkowitz, N.

    1992-01-01

    An unshielded antenna for rf heating has been developed and tested during this report period. In addition to design specifications being given, some experimental results are presented utilizing: (1) an unprotected Faraday shield, (2) insulating guard limiters, (3) unshielded antenna experiments, (4) method for detecting small rf driven currents, (5) rf fast wave current drive experiments, (6) alfven wave interactions with electrons, and (7) machine conditioning, impurity generation and density control

  2. Current challenges in autonomous driving

    Science.gov (United States)

    Barabás, I.; Todoruţ, A.; Cordoş, N.; Molea, A.

    2017-10-01

    Nowadays the automotive industry makes a quantum shift to a future, where the driver will have smaller and smaller role in driving his or her vehicle ending up being totally excluded. In this paper, we have investigated the different levels of driving automatization, the prospective effects of these new technologies on the environment and traffic safety, the importance of regulations and their current state, the moral aspects of introducing these technologies and the possible scenarios of deploying the autonomous vehicles. We have found that the self-driving technologies are facing many challenges: a) They must make decisions faster in very diverse conditions which can include many moral dilemmas as well; b) They have an important potential in reducing the environmental pollution by optimizing their routes, driving styles by communicating with other vehicles, infrastructures and their environment; c) There is a considerable gap between the self-drive technology level and the current regulations; fortunately, this gap shows a continuously decreasing trend; d) In case of many types of imminent accidents management there are many concerns about the ability of making the right decision. Considering that this field has an extraordinary speed of development, our study is up to date at the submission deadline. Self-driving technologies become increasingly sophisticated and technically accessible, and in some cases, they can be deployed for commercial vehicles as well. According to the current stage of research and development, it is still unclear how the self-driving technologies will be able to handle extreme and unexpected events including their moral aspects. Since most of the traffic accidents are caused by human error or omission, it is expected that the emergence of the autonomous technologies will reduce these accidents in their number and gravity, but the very few currently available test results have not been able to scientifically underpin this issue yet. The

  3. Universal power transistor base drive control unit

    Science.gov (United States)

    Gale, Allan R.; Gritter, David J.

    1988-01-01

    A saturation condition regulator system for a power transistor which achieves the regulation objectives of a Baker clamp but without dumping excess base drive current into the transistor output circuit. The base drive current of the transistor is sensed and used through an active feedback circuit to produce an error signal which modulates the base drive current through a linearly operating FET. The collector base voltage of the power transistor is independently monitored to develop a second error signal which is also used to regulate base drive current. The current-sensitive circuit operates as a limiter. In addition, a fail-safe timing circuit is disclosed which automatically resets to a turn OFF condition in the event the transistor does not turn ON within a predetermined time after the input signal transition.

  4. Adjustable Speed Drives and Power Quality

    DEFF Research Database (Denmark)

    Davari, Pooya; Yang, Yongheng; Zare, Firuz

    2016-01-01

    This paper provides an overview and proposes cost-effective and efficient opportunities in improving power quality in Adjustable Speed Drive (ASD) systems. In particular, an Electronic Inductor (EI) technique has been used in single drives to overcome the existing challenges in conventional...... frontend rectifiers even at partial loading conditions. Moreover, the effectiveness of the EI technique along with a phase-shifted current control in terms of improved grid current quality in multi-drive configurations is addressed. Furthermore, a novel DC-link current modulation scheme for multi...

  5. Mechanisms of the negative synergy effect between electron cyclotron current drive and lower hybrid current drive in tokamak

    International Nuclear Information System (INIS)

    Chen Shaoyong; Hong Binbin; Tang Changjian; Yang Wen; Zhang Xinjun

    2013-01-01

    The synergy current drive by combining electron cyclotron wave (ECW) with lower hybrid wave (LHW) can be used to either increase the noninductive current drive efficiency or shape the plasma current profile. In this paper, the synergy current drive by ECW and LHW is studied with numerical simulation. The nonlinear relationship between the wave powers and the synergy current of ECW and LHW is revealed. When the LHW power is small, the synergy current reduces as the ECW power increases, and the synergy current is even reduced to lower than zero, which is referred as negative synergy in the this context. Research shows that the mechanism of the negative synergy is the peaking effect of LHW power profile and the trapped electrons effect. The present research is helpful for understanding the physics of synergy between electron cyclotron current drive and lower hybrid current drive, it can also instruct the design of experiments. (authors)

  6. Driving with electrical power

    International Nuclear Information System (INIS)

    Ursin, M.; Hoeckel, M.

    2008-01-01

    This article takes a look at the chances offered to the electricity supply industry by the increasing use of battery-driven vehicles - and the advantages thus offered to the environment. The use of the vehicles' batteries to form a distributed electricity storage scheme is discussed. The authors comment that, although electrically-driven vehicles consume more power, the total primary energy consumption and pollutant emissions will be reduced. The actual electricity consumption of electric vehicles and the source of this power are examined. Power saved by the reduced use of electrical heating systems and boilers could, according to the authors, be used to charge the batteries of electric vehicles. The use of these batteries as a storage system to help regulate electricity supplies is discussed and the steps to be taken for the implementation of such a system are listed

  7. FWCD (fast wave current drive) and ECCD (electron cyclotron current drive) experiments on DIII-D

    International Nuclear Information System (INIS)

    Prater, R.; Austin, M.; Baity, F.W.

    1994-01-01

    Fast wave current drive and electron cyclotron current drive experiments have been performed on the DIII-D tokamak as part of the advanced tokamak program. The goal of this program is to develop techniques for controlling the profile of the current density in order to access regimes of improved confinement and stability. The experiments on fast wave current drive used a four strap antenna with 90deg phasing between straps. A decoupler was used to help maintain the phasing, and feedback control of the plasma position was used to keep the resistive loading constant. RF pickup loops demonstrate that the directivity of the antenna is as expected. Plasma currents up to 0.18 MA were driven by 1.5 MW of fast wave power. Electron cyclotron current drive experiments at 60 GHz have shown 0.1 MA of plasma current driven by 1 MW of power. New fast wave and electron cyclotron heating systems are in development for DIII-D, so that the goals of the advanced tokamak program can be carried out. (author)

  8. Fast wave current drive above the slow wave density limit

    International Nuclear Information System (INIS)

    McWilliams, R.; Sheehan, D.P.; Wolf, N.S.; Edrich, D.

    1989-01-01

    Fast wave and slow wave current drive near the mean gyrofrequency were compared in the Irvine Torus using distinct phased array antennae of similar principal wavelengths, frequencies, and input powers. The slow wave current drive density limit was measured for 50ω ci ≤ω≤500ω ci and found to agree with trends in tokamaks. Fast wave current drive was observed at densities up to the operating limit of the torus, demonstrably above the slow wave density limit

  9. Neutral beam current drive with balanced injection

    International Nuclear Information System (INIS)

    Eckhartt, D.

    1990-01-01

    Current drive with fast ions has proved its capability to sustain a tokamak plasma free of externally induced electric fields in a stationary state. The suprathermal ion population within the toroidal plasma was created by quasi-tangential and uni-directional injection of high-energy neutral atoms, their ionisation and subsequent deceleration by collisions with the background plasma particles. In future large tokamaks of the NET/INTER-type, with reactor-relevant values of plasma density and temperature, this current drive scheme is expected to maintain the toroidal current at the plasma centre, as current drive by lower hybrid waves will be restricted to the outer plasma regions owing to strong wave damping. Adequate penetration of the neutral atoms through the dense plasma requires particle energies of several hundred kilovolts per nucleon since beam absorption scales roughly with the ratio beam energy over density. The realisation of such high-energy high-power neutral beams, based on negative ion technology, is now under study. (author) 7 refs., 2 figs

  10. Generation of runaway electrons during deterioration of lower hybrid power coupling in lower hybrid current drive plasmas in the HT-7 tokamak

    International Nuclear Information System (INIS)

    Chen, Z Y; Ju, H J; Zhu, J X; Li, M; Cai, W D; Liang, H F; Wan, B N; Shi, Y J; Xu, H D

    2009-01-01

    Efficient coupling of lower hybrid (LH) power from the wave launcher to the plasma is a very important issue in lower hybrid current drive (LHCD) experiments. The large unbalanced reflections in the grill trigger the LH protection system, which will trip the power, resulting in the reduction of the coupled LH power. The generation of runaway electrons has been investigated in LHCD plasmas with deterioration of LH coupling in the HT-7 tokamak. The deterioration of LH coupling results in an increase of the loop voltage and a more energetic fast electron population. These two effects favor the generation of a runaway population. It is found that most of the fast electrons generated by LH waves through parallel electron Landau damping were converted into a runaway population through the acceleration from the toroidal electric field when significant deterioration of LH coupling occurs.

  11. PMBLDC motor drive with power factor correction controller

    DEFF Research Database (Denmark)

    George, G.J.; Ramachandran, Rakesh; Arun, N.

    2012-01-01

    reliability, and low maintenance requirements. The proposed Power Factor Controller topology improves power quality by improving performance of PMBLDCM drive, such as reduction of AC main current harmonics, near unity power factor. PFC converter forces the drive to draw sinusoidal supply current in phase...

  12. On the NBI system for substantial current drive in a fusion power plant: Status and R and D needs for ion source and laser neutralizer

    International Nuclear Information System (INIS)

    Franzen, P.; Fantz, U.

    2014-01-01

    Highlights: • NBI is a candidate for a cw tokamak DEMO due to its high current drive efficiency. • The plug-in efficiency must be improved from the present 20–30% to more than 50%. • A suitable candidate is a photo neutralizer with almost 100% neutralization efficiency; basic feasibility studies are underway. • Cw operation with a large availability puts rather high demands on source operation with some safety margins, especially for the components with high power density loads (source back plate and extraction system). • Alternatives to the present use of cesium are under exploitations. - Abstract: The requirements for the heating and current drive systems of a fusion power plant will strongly depend on the DEMO scenario. The paper discusses the R and D needs for a neutral beam injection system — being a candidate due to the highest current drive efficiency — for the most demanding scenario, a steady state tokamak DEMO. Most important issues are the improvement of the wall-plug efficiency from the present ∼25% to the required 50–60% by improving the neutralization efficiency with a laser neutralizer system and the improvement of the reliability of the ion source operation. The demands on and the potential of decreasing the ion source operation pressure, as well as decreasing the amount of co-extracted electrons and backstreaming ions are discussed using the ITER requirements and solutions as basis. A further concern is the necessity of cesium for which either the cesium management must be improved or alternatives to cesium for the production of negative ions have to be identified

  13. Review of current drive theory: selected topics

    International Nuclear Information System (INIS)

    Fisch, N.J.

    1993-01-01

    Two themes in current drive theory in tokamaks are reviewed, both relevant to the progression of tokamak experiments toward the reactor regime. First, the physics of the tail electrons is reviewed. These electrons are capable of carrying enormous rf-driven electric current, and, in the course of current-drive experiments worldwide not only has the current drive effect been demonstrated, but the underlying physical description of these tail electrons has been established. Second, anticipating the presence of the energetic alpha particles that result from D-T reactions in a reactor, certain mechanisms through which these alpha particles can be used to facilitate current-drive are reviewed. (Author)

  14. Lower hybrid current drive in shaped tokamaks

    International Nuclear Information System (INIS)

    Kesner, J.

    1993-01-01

    A time dependent lower hybrid current drive tokamak simulation code has been developed. This code combines the BALDUR tokamak simulation code and the Bonoli/Englade lower hybrid current drive code and permits the study of the interaction of lower hybrid current drive with neutral beam heating in shaped cross-section plasmas. The code is time dependent and includes the beam driven and bootstrap currents in addition to the current driven by the lower hybrid system. Examples of simulations are shown for the PBX-M experiment which include the effect of cross section shaping on current drive, ballooning mode stabilization by current profile control and sawtooth stabilization. A critical question in current drive calculations is the radial transport of the energetic electrons. The authors have developed a response function technique to calculate radial transport in the presence of an electric field. The consequences of the combined influences of radial diffusion and electric field acceleration are discussed

  15. Heating and current drive on NSTX

    Science.gov (United States)

    Wilson, J. R.; Batchelor, D.; Carter, M.; Hosea, J.; Ignat, D.; LeBlanc, B.; Majeski, R.; Ono, M.; Phillips, C. K.; Rogers, J. H.; Schilling, G.

    1997-04-01

    Low aspect ratio tokamaks pose interesting new challenges for heating and current drive. The NSTX (National Spherical Tokamak Experiment) device to be built at Princeton is a low aspect ratio toroidal device that has the achievement of high toroidal beta (˜45%) and non-inductive operation as two of its main research goals. To achieve these goals significant auxiliary heating and current drive systems are required. Present plans include ECH (Electron cyclotron heating) for pre-ionization and start-up assist, HHFW (high harmonic fast wave) for heating and current drive and eventually NBI (neutral beam injection) for heating, current drive and plasma rotation.

  16. Heating and current drive on NSTX

    International Nuclear Information System (INIS)

    Wilson, J.R.; Batchelor, D.; Carter, M.; Hosea, J.; Ignat, D.; LeBlanc, B.; Majeski, R.; Ono, M.; Phillips, C.K.; Rogers, J.H.; Schilling, G.

    1997-01-01

    Low aspect ratio tokamaks pose interesting new challenges for heating and current drive. The NSTX (National Spherical Tokamak Experiment) device to be built at Princeton is a low aspect ratio toroidal device that has the achievement of high toroidal beta (∼45%) and non-inductive operation as two of its main research goals. To achieve these goals significant auxiliary heating and current drive systems are required. Present plans include ECH (Electron cyclotron heating) for pre-ionization and start-up assist, HHFW (high harmonic fast wave) for heating and current drive and eventually NBI (neutral beam injection) for heating, current drive and plasma rotation. copyright 1997 American Institute of Physics

  17. Oscillating field current drive for reversed field pinch discharges

    International Nuclear Information System (INIS)

    Schoenberg, K.F.; Gribble, R.F.; Baker, D.A.

    1984-06-01

    Oscillating Field Current Drive (OFCD), also known as F-THETA pumping, is a steady-state current-drive technique proposed for the Reversed Field Pinch (RFP). Unlike other current-drive techniques, which employ high-technology, invasive, and power intensive schemes using radio frequency or neutral particle injection, F-THETA pumping entails driving the toroidal and poloidal magnetic field circuits with low-frequency (audio) oscillating voltage sources. Current drive by this technique is a consequence of the strong nonlinear plasma coupling in the RFP. Because of its low frequency and efficient plasma coupling, F-THETA pumping shows excellent promise as a reactor-relevant current-drive technique. A conceptual and computational study of this concept, including its experimental and reactor relevance, is explored in this paper

  18. RF current drive and plasma fluctuations

    International Nuclear Information System (INIS)

    Peysson, Yves; Decker, Joan; Morini, L; Coda, S

    2011-01-01

    The role played by electron density fluctuations near the plasma edge on rf current drive in tokamaks is assessed quantitatively. For this purpose, a general framework for incorporating density fluctuations in existing modelling tools has been developed. It is valid when rf power absorption takes place far from the fluctuating region of the plasma. The ray-tracing formalism is modified in order to take into account time-dependent perturbations of the density, while the Fokker–Planck solver remains unchanged. The evolution of the electron distribution function in time and space under the competing effects of collisions and quasilinear diffusion by rf waves is determined consistently with the time scale of fluctuations described as a statistical process. Using the ray-tracing code C3PO and the 3D linearized relativistic bounce-averaged Fokker–Planck solver LUKE, the effect of electron density fluctuations on the current driven by the lower hybrid (LH) and the electron cyclotron (EC) waves is estimated quantitatively. A thin fluctuating layer characterized by electron drift wave turbulence at the plasma edge is considered. The effect of fluctuations on the LH wave propagation is equivalent to a random scattering process with a broadening of the poloidal mode spectrum proportional to the level of the perturbation. However, in the multipass regime, the LH current density profile remains sensitive to the ray chaotic behaviour, which is not averaged by fluctuations. The effect of large amplitude fluctuations on the EC driven current is found to be similar to an anomalous radial transport of the fast electrons. The resulting lower current drive efficiency and broader current profile are in better agreement with experimental observations. Finally, applied to the ITER ELMy H-mode regime, the model predicts a significant broadening of the EC driven current density profile with the fluctuation level, which can make the stabilization of neoclassical tearing mode potentially

  19. CURRENT DRIVE AND PRESSURE PROFILE MODIFICATION WITH ELECTRON CYCLOTRON POWER IN DIII-D QUIESCENT DOUBLE BARRIER EXPERIMENTS

    International Nuclear Information System (INIS)

    CASPER, TA; BURRELL, KH; DOYLE, EJ; GOHIL, P; GREENFIELD, CM; GROEBNER, RJ; JAYAKUMAR, RJ; MAKOWSKI, MA; RHODES, TL; WEST, WP

    2003-01-01

    OAK-B135 High confinement mode (H-mode) operation is a leading scenario for burning plasma devices due to its inherently high energy-confinement characteristics. The quiescent H-mode (QH-mode) offers these same advantages with the additional attraction of more steady edge conditions where the highly transient power loads due to edge localized mode (ELM) activity is replaced by the steadier power and particle losses associated with an edge harmonic oscillation (EHO). With the addition of an internal transport barrier (ITB), the capability is introduced for independent control of both the edge conditions and the core confinement region giving potential control of fusion power production for an advanced tokamak configuration. The quiescent double barrier (QDB) conditions explored in DIII-D experiments exhibit these characteristics and have resulted in steady plasma conditions for several confinement times (∼ 26 τ E ) with moderately high stored energy, β N H 89 ∼ 7 for 10 τ E

  20. 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.

  1. High-power converters and AC drives

    CERN Document Server

    Wu, Bin

    2017-01-01

    This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

  2. Combined RF current drive and bootstrap current in tokamaks

    International Nuclear Information System (INIS)

    Schultz, S. D.; Bers, A.; Ram, A. K.

    1999-01-01

    By calculating radio frequency current drive (RFCD) and the bootstrap current in a consistent kinetic manner, we find synergistic effects in the total noninductive current density in tokamaks [1]. We include quasilinear diffusion in the Drift Kinetic Equation (DKE) in order to generalize neoclassical theory to highly non-Maxwellian electron distributions due to RFCD. The parallel plasma current is evaluated numerically with the help of the FASTEP Fokker-Planck code [2]. Current drive efficiency is found to be significantly affected by neoclassical effects, even in cases where only circulating electrons interact with the waves. Predictions of the current drive efficiency are made for lower hybrid and electron cyclotron wave current drive scenarios in the presence of bootstrap current

  3. Neutral-beam current drive in tokamaks

    International Nuclear Information System (INIS)

    Devoto, R.S.

    1986-01-01

    The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500 to 700 keV are needed for this device

  4. Neutral-beam current drive in tokamaks

    International Nuclear Information System (INIS)

    Devoto, R.S.

    1987-01-01

    The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500-700 keV are needed for this device

  5. Passive cyclotron current drive for fusion plasmas

    International Nuclear Information System (INIS)

    Kernbichler, W.

    1995-01-01

    The creation of toroidal current using cyclotron radiation in a passive way is, together with the well known bootstrap current, an interesting method for stationary current drive in high-temperature fusion reactors. Here, instead of externally applied RF-waves, fish-scale like structures at the first wall help to create enough asymmetry in the self generated cyclotron radiation intensity to drive a current within the plasma. The problem of computing passive cyclotron current drive consists of actually two linked problems, which are the computation of the electron equilibrium under the presence of self-generated radiation, and the computation of the photon equilibrium in a bounded system with a distorted electron distribution. This system of integro-differential equations cannot be solved directly in an efficient way. Therefore a linearization procedure was developed to decouple both sets of equations, finally linked through a generalized local current drive efficiency. The problem of the exact accounting for the wall profile effects was reduced to the solution of a Fredholm-type integral equation of the 2 nd -kind. Based on all this an extensive computer code was developed to compute the passively driven current as well as radiation losses, radiation transport and overall efficiencies. The results therefrom give an interesting and very detailed insight into the problems related to passive cyclotron current drive

  6. Rotating field current drive in spherical plasmas

    International Nuclear Information System (INIS)

    Brotherton-Ratcliffe, D.; Storer, R.G.

    1988-01-01

    The technique of driving a steady Hall current in plasmas using a rotating magnetic field is studied both numerically and analytically in the approximation of negligible ion flow. A spherical plasma bounded by an insulating wall and immersed in a uniform magnetic field which has both a rotating component (for current drive) and a constant ''vertical'' component (for MHD equilibrium) is considered. The problem is formulated in terms of an expansion of field quantities in vector spherical harmonics. The numerical code SPHERE solves the resulting pseudo-harmonic equations by a multiple shooting technique. The results presented, in addition to being relevant to non-inductive current drive generally, have a direct relevance to the rotamak experiments. For the case of no applied vertical field the steady state toroidal current driven by the rotating field per unit volume of plasma is several times less than in the long cylinder limit for a plasma of the same density, resistivity and radius. The application of a vertical field, which for certain parameter regimes gives rise to a compact torus configuration, improves the current drive dramatically and in many cases gives ''better'' current drive than the long cylinder limit. This result is also predicted by a second order perturbation analysis of the pseudo-harmonic equations. A steady state toroidal field is observed which appears consistent with experimental observations in rotamaks regarding magnitude and spatial dependence. This is an advance over previous analytical theory which predicted an oppositely directed toroidal field of undefined magnitude. (author)

  7. Bootstrap and fast wave current drive for tokamak reactors

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1991-09-01

    Using the multi-species neoclassical treatment of Hirshman and Sigmar we study steady state bootstrap equilibria with seed currents provided by low frequency (ICRF) fast waves and with additional surface current density driven by lower hybrid waves. This study applies to reactor plasmas of arbitrary aspect ratio. IN one limit the bootstrap component can supply nearly the total equilibrium current with minimal driving power ( o = 18 MA needs P FW = 15 MW, P LH = 75 MW). A computational survey of bootstrap fraction and current drive efficiency is presented. 11 refs., 8 figs

  8. Electron cyclotron resonance heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Fidone, I.; Castejon, F.

    1992-07-01

    A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs.

  9. Electron - cyclotron resonance heating and current drive

    International Nuclear Information System (INIS)

    Fidone, I.; Castejon, F.

    1992-01-01

    A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs

  10. Monte Carlo simulation of lower hybrid current drive in tokamaks

    International Nuclear Information System (INIS)

    Sipilae, S.K.; Heikkinen, J.A.

    1994-01-01

    In the report a method for noninductive current drive studies based on three-dimensional simulation of test particle orbits is presented. A Monte Carlo momentum diffusion operator is developed to model the wave-particle interaction. The scheme can be utilised in studies of current drive efficiency as well as in examining the current density profiles caused by waves with a finite parallel wave number spectrum and a nonuniform power deposition profile in a toroidal configuration space of arbitrary shape. Calculations performed with a uniform poorer deposition profile of lower hybrid waves for axisymmetric magnetic configurations having different aspect ratios and poloidal cross-section shape confirm the semianalytic estimates for the current drive efficiency based on the solutions of the flux surface averaged Fokker-Planck equation for configurations with circular poloidal cross section. The consequences of the combined effect of radial diffusion, magnetic trapping and radially nonhomogeneous power deposition and background plasma parameter profiles are investigated

  11. Plasma auxiliary heating and current drive

    International Nuclear Information System (INIS)

    1999-01-01

    Heating and current drive systems must fulfil several roles in ITER operating scenarios: heating through the H-mode transition and to ignition; plasma burn control; current drive and current profile control in steady state scenarios; and control of MHD instabilities. They must also perform ancillary functions, such as assisting plasma start-up and wall conditioning. It is recognized that no one system can satisfy all of these requirements with the degree of flexibility that ITER will require. Four heating and current drive systems are therefore under consideration for ITER: electron cyclotron waves at a principal frequency of 170 GHz; fast waves operating in the range 40-70 MHz (ion cyclotron waves); lower hybrid waves at 5 GHz; and neutral beam injection using negative ion beam technology for operation at 1 MeV energy. It is likely that several of these systems will be employed in parallel. The systems have been chosen on the basis of the maturity of physics understanding and operating experience in current experiments and on the feasibility of applying the relevant technology to ITER. Here, the fundamental physics describing the interaction of these heating systems with the plasma is reviewed, the relevant experimental results in the exploitation of the heating and current drive capabilities of each system are discussed, key aspects of their application to ITER are outlined, and the major technological developments required in each area are summarized. (author)

  12. Electron-cyclotron current drive in the tokamak physics experiment

    International Nuclear Information System (INIS)

    Smith, G.R.; Kritz, A.H.; Radin, S.H.

    1992-01-01

    Ray-tracking calculations provide estimates of the electron-cyclotron heating (ECH) power required to suppress tearing modes near the q=2 surface in the Tokamak Physics Experiment. Effects of finite beam width and divergence are included, as are the effects of scattering of the ECH power by drift-wave turbulence. A frequency of about 120 GHz allows current drive on the small-R (high-B) portion of q=2, while 80 GHz drives current on the large-R (low-B) portion. The higher frequency has the advantages of less sensitivity to wave and plasma parameters and of no trapped-electron degradation of current-drive efficiency. Less than 1 MW suffices to suppress tearing modes even with high turbulence levels

  13. RF Current Drive in Internal Transport Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Basiuk, V.; Huysmans, G. [Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache, 13 - St Paul-lez-Durance (France); Decker, J.; Bers, A.; Ram, A.K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2005-07-01

    The current drive problem in regimes with internal transport barrier is addressed using a fast solver of the electron drift kinetic equation which may be used for arbitrary tokamak plasma magnetic equilibrium and any type of electron radio-frequency wave. Parametric studies are performed for the Lower Hybrid and Electron Cyclotron waves. (authors)

  14. Current-drive theory II: the lower-hybrid wave

    International Nuclear Information System (INIS)

    Fisch, N.J.

    1986-01-01

    The theory of current-drive seeks to predict the efficiency with which an external power source can produce current in a plasma torus. The theory, which is now well supported by experimental data, becomes especially simple in the important limit of lower-hybrid or electron-cyclotron waves interacting with superthermal electrons. The solution of an equation adjoint to the linearized Fokker-Planck equation gives both the steady-state and ramp-up current-drive efficiencies. Other phenomena, such as rf-induced runaway rates, rf-induced radiation, etc., may be calculated by this method, and analytical solutions have been obtained in several limiting cases. 12 refs

  15. Recent progress in lower hybrid current drive theory and experiments

    International Nuclear Information System (INIS)

    Barbato, E.

    1998-01-01

    In this paper lower hybrid current drive (LHCD) experimental milestones paving the way for future experiments are briefly summarized. The current drive efficiency scaling with the electron temperature is discussed. The role of wave propagation in determining the power deposition profile is stressed and methods are discussed to control the current density profile. Modelling of negative central shear configurations, experimentally obtained by LHCD, are reported. A good agreement is found between the modelling results and the experimental findings, thus showing that a good degree of understanding has been achieved in LHCD theory. (author)

  16. Numerical analysis on the synergy between electron cyclotron current drive and lower hybrid current drive in tokamak plasmas

    International Nuclear Information System (INIS)

    Chen, S Y; Hong, B B; Liu, Y; Lu, W; Huang, J; Tang, C J; Ding, X T; Zhang, X J; Hu, Y J

    2012-01-01

    The synergy between electron cyclotron current drive (ECCD) and lower hybrid current drive (LHCD) is investigated numerically with the parameters of the HL-2A tokamak. Based on the understanding of the synergy mechanisms, a high current driven efficiency or a desired radial current profile can be achieved through properly matching the parameters of ECCD and LHCD due to the flexibility of ECCD. Meanwhile, it is found that the total current driven by the electron cyclotron wave (ECW) and the lower hybrid wave (LHW) simultaneously can be smaller than the sum of the currents driven by the ECW and LHW separately, when the power of the ECW is much larger than the LHW power. One of the reasons leading to this phenomenon (referred to as negative synergy in this context) is that fast current-carrying electrons tend to be trapped, when the perpendicular velocity driven by the ECW is large and the parallel velocity decided by the LHW is correspondingly small. (paper)

  17. Electron Bernstein wave heating and current drive effects in QUEST

    International Nuclear Information System (INIS)

    Idei, H.; Zushi, H.; Hanada, K.; Nakamura, K.; Fujisawa, A.; Nagashima, Y.; Hasegawa, M.; Matsuoka, K.; Watanabe, H.; Yoshida, N.; Tokunaga, K.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Kalinnikova, E.; Sakaguchi, M.; Itado, T.; Tashima, S.; Fukuyama, A.; Ejiri, A.; Takase, Y.; Igami, H.; Kubo, S.; Toi, K.; Isobe, M.; Nagaoka, K.; Nakanishi, H.; Nishino, N.; Ueda, Y.; Kikuchi, Mitsuru; Fujita, Takaaki; Mitarai, O.; Maekawa, T.

    2012-11-01

    Electron Bernstein Wave Heating and Current Drive (EBWH/CD) effects have been first observed in over dense plasmas using the developed phased-array antenna (PAA) system in QUEST. Good focusing and steering properties tested in the low power facilities were confirmed with a high power level in the QUEST device. The new operational window to sustain the plasma current was observed in the RF-sustained high-density plasmas at the higher incident RF power. Increment and decrement of the plasma current and the loop voltage were observed in the over dense ohmic plasma by the RF injection respectively, indicating the EBWH/CD effects. (author)

  18. Modulational instability development and current drive

    International Nuclear Information System (INIS)

    Popel, S.I.; Vladimirov, S.V.; Tsytovich, V.N.

    1992-01-01

    Recently many investigations on current driven by lower-hybrid (LH) waves in a plasma of toroidal nuclear fusion installations are carried out. Usually a theoretical approach taking into account quasilinear and binary collisions effects is used to describe current drive. However a problem of comparison of the results obtained with the aid of the above theoretical approach and experimental data takes place. Namely the experimentally observed currents driven by LH waves is two-three orders of magnitude larger than those calculated. The above discrepancy between theory and experiment is related with the existence of the so-called ''spectral gap'', that is the gap between the parallel phase velocities of LH waves ω/k || (where ω, k || are LH wave frequency and a component of wavenumber k parallel to the external magnetic field) which are necessary for effective Landau damping of LH waves (i.e. velocities as high as several electron thermal velocities) and the lowest parallel phase velocity in the injected LH wave spectrum. Experimentally observed current drive may be explained if one accounts for filling of the ''spectral gap'' by LH waves. Some nonlinear effects have been drawn in current drive description to explain the ''spectral gap'' filling by LH waves. However the LH wave modulational instability (MI) effect has not been considered yet in application to current drive description. The aim of this paper is to investigate this MI influence. We shall show that for sufficiently intensive pump level of LH wave the MI can lead to ''spectral gap'' filling. (author) 4 refs

  19. Predictions of of fast wave heating, current drive, and current drive antenna arrays for advanced tokamaks

    International Nuclear Information System (INIS)

    Batchelor, D.B.; Baity, F.W.; Carter, M.D.

    1995-01-01

    The objective of the advanced tokamak program is to optimize plasma performance leading to a compact tokamak reactor through active, steady state control of the current profile using non-inductive current drive and profile control. To achieve this objective requires compatibility and flexibility in the use of available heating and current drive systems - ion cyclotron radio frequency (ICRF), neutral beams, and lower hybrid. For any advanced tokamak, the following are important challenges to effective use of fast waves in various role of direct electron heating, minority ion heating, and current drive: (1) to employ the heating and current drive systems to give self-consistent pressure and current profiles leading to the desired advanced tokamak operating modes; (2) to minimize absorption of the fast waves by parasitic resonances, which limit current drive; (3) to optimize and control the spectrum of fast waves launched by the antenna array for the required mix of simultaneous heating and current drive. The paper addresses these issues using theoretical and computational tools developed at a number of institutions by benchmarking the computations against available experimental data and applying them to the specific case of TPX. (author). 6 refs, 3 figs

  20. Predictions of fast wave heating, current drive, and current drive antenna arrays for advanced tokamaks

    International Nuclear Information System (INIS)

    Batchelor, D.B.; Baity, F.W.; Carter, M.D.

    1994-01-01

    The objective of the advanced tokamak program is to optimize plasma performance leading to a compact tokamak reactor through active, steady state control of the current profile using non-inductive current drive and profile control. To achieve these objectives requires compatibility and flexibility in the use of available heating and current drive systems--ion cyclotron radio frequency (ICRF), neutral beams, and lower hybrid. For any advanced tokamak, the following are important challenges to effective use of fast waves in various roles of direct electron heating, minority ion heating, and current drive: (1) to employ the heating and current drive systems to give self-consistent pressure and current profiles leading to the desired advanced tokamak operating modes; (2) to minimize absorption of the fast waves by parasitic resonances, which limit current drive; (3) to optimize and control the spectrum of fast waves launched by the antenna array for the required mix of simultaneous heating and current drive. The authors have addressed these issues using theoretical and computational tools developed at a number of institutions by benchmarking the computations against available experimental data and applying them to the specific case of TPX

  1. Comments on ICRH current drive in JET

    International Nuclear Information System (INIS)

    Fried, B.; Hellsten, T.; Moreau, D.

    1989-01-01

    To study current drive via the mode-converted slow wave during ICRH an assessment for which plasma compositions and wave number mode conversion from the magnetosonic wave to the slow wave can dominate is made. A simple slab model is used to investigate the competition between mode conversion and minority cyclotron absorption for a deuterium plasma with H + and 3 He 2+ minority species in JET. A 3 He 2+ minority should be more appropriate for mode conversion current drive than H + because the 3 He 2+ concentration can be chosen near its optimum for the ''Budden absorption'' without bringing the ion hybrid resonance and the cyclotron resonance so close that the minority absorption dominates. 3 He 2+ minority also allows operation at toroidal numbers which are characteristic of present JET antennae. (author)

  2. Transitionless quantum driving based wireless power transfer

    OpenAIRE

    Paul, Koushik; Sarma, Amarendra K.

    2017-01-01

    Shortcut to adiabaticity (STA) techniques have the potential to drive a system beyond the adiabatic limits. Here, we present a robust and efficient method for wireless power transfer (WPT) between two coils based on the so-called transitionless quantum driving (TQD) algorithm. We show that it is possible to transfer power between the coils significantly fast compared to its adiabatic counterpart. The scheme is fairly robust against the variations in the coupling strength and the coupling dist...

  3. Design and simulation for the pulse high-voltage DC power supply (HVPS) of 1.2 MW/2.45 GHz HT-7U lower hybrid current drive system

    International Nuclear Information System (INIS)

    Huang Yiyun; Kuang Guangli; Xu Weihua; Liu Baohua; Lin Jianan; Wu Junshuan; Zheng Guanghua; Yang Chunshen

    2000-01-01

    The superconducting tokamak HT-7U has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW/2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation now, and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the Institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred

  4. Stability, current drive and heating, energetic particles

    International Nuclear Information System (INIS)

    Razumova, K.

    2001-01-01

    The paper summarizes the results presented at the conference Fusion Energy 2000 (FEC 2000) in relation to the following subjects: 1. The possibility of realizing plasma parameters for ITER needs, advanced regimes in tokamaks and stellarators. 2. Stability of plasmas with an appreciable component of fast particles. 3. Low aspect ratio tokamaks. 4. New results with auxiliary heating and current drive methods. 5. β limit and neoclassical tearing mode (NTM) stabilization. 6. Internal transport barriers. (author)

  5. Lower-hybrid heating and current drive on PLT

    International Nuclear Information System (INIS)

    Hooke, W.; Bernabei, S.; Boyd, D.

    1983-02-01

    Steady currents up to 165 kA for 3.5 seconds and 420 kA for 0.3 seconds have been maintained by 800 MHz lower hybrid waves. For line-averaged densities up to 7 x 10 12 cm - 3 the current is maintained with no input power from the ohmic heating transformer. The waves are launched with an array of six waveguides. Measurements of X rays and electron cyclotron radiation show that the rf power produces and maintains a suprathermal tail of electrons apparently independent of the number of fast electrons in the plasma prior to turning on the rf power. Measurements of current-drive efficiency and the electron tail provide direct evidence for a resonant wave-particle interaction. The radial profile of the rf-sustained current inferred from x-ray measurements is peaked in the center of the plasma and appears to obey the same q-value restraints as the inductively driven ohmic heating current. Current drive is observed to be accompanied always by radiation at frequencies greater than or equal to #betta#/sub ce/ and less than or equal to #betta#/sub pe/. The connection between this radiation and the current-drive mechanism is under study

  6. Power electronics and motor drives

    CERN Document Server

    Wilamowski, Bogdan M

    2011-01-01

    Universities throughout the world typically provide an excellent education in the various aspects of electronics, however their focus is normally on traditional low power electronics. In contrast, in the industrial environment, there is a need for high power electronics that is used to control electromechanical systems in addition to the low power electronics typically employed for analog and digital systems. To address this need, Section 1 of this volume in The Industrial Electronics Handbook, Second Edition, is focused on special high power semiconductor devices. Section 2 not only describes

  7. Joint Czechoslovak-Soviet workshop on current drive in tokamaks

    International Nuclear Information System (INIS)

    1985-10-01

    At the Joint Czechoslovak-Soviet Workshop on Current Drive in Tokamaks, five papers dealing with issues of general interest were presented. In a theoretical paper by Klima and Pavlo a one-dimensional model of the lower-hybrid current drive is described and the results of its analysis are used in a numerical simulation using T-7 tokamak parameters. In the second theoretical paper by Vojtsekhovich, Parail and Pereverzev the influence of the LH wave spectrum on the efficiency of the current drive is studied. Two papers deal with a new microwave system designed for experiments on LHCD in the T-7 tokamak. In particular, the power spectra of new four-waveguide grills are computed. In the last paper the non-inductive start-up of the discharge in the T-7 tokamak by means of electron cyclotron waves is investigated. (J.U.)

  8. Simulations of ICRF-fast wave current drive on DIIID

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1990-06-01

    Self-consistent calculations of MHD equilibria, generated by fast wave current drive and including the bootstrap effect, were done to guide and anticipate the results of upcoming experiments on the DIIID tokamak. The simulations predict that 2 MW of ICRF power is more than adequate to create several hundred kiloamperes in steady state; the total current increases with the temperature and density of the target plasma. 12 refs., 12 figs., 1 tab

  9. Development of constant-power driving control for light-emitting-diode (LED) luminaire

    KAUST Repository

    Huang, Bin-Juine; Chen, Chun-Wei; Ong, Chin-Dian; Du, Bo-Han; Hsu, Po-Chien

    2013-01-01

    changes from 0 to 40 °C, the LED illumination varies slightly (-1.7%) for constant-power driving, as compared to that of constant-current driving (-12%) and constant-voltage driving (+50%). The constant-power driving has revealed advantage in stabilizing

  10. Microelectronics in power electronics and electrical drives

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    From October, 1214, 1982 at Darmstadt (FRG) a meeting took place on ''Microelectronics in power electronics and Electrical Drives''. This volume contains the papers of the 65 lectures, held at the symposium. For each of the 10 papers dealing with problems on electric-powered vehicles a separate subject analysis has been carried out.

  11. Progress with helicity injection current drive

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Raman, R.; Nelson, B.A.

    2003-01-01

    Coaxial Helicity Injection (CHI) experiments in the NSTX and HIT-II devices are reported. NSTX has produced toroidal currents of 0.4 MA and pulse lengths of up to 0.33 s. These discharges nearly fill the NSTX main chamber, and show the n=1 rotating distortion characteristic of high-performance CHI plasmas. CHI has been used in HIT-II to provide a closed flux startup plasma for inductive drive. The CHI startup method saves transformer volt-seconds and greatly improves reproducibility and reliability of inductively driven discharges, even in the presence of diminishing wall conditions. (author)

  12. Optimized calculation of the synergy conditions between electron cyclotron current drive and lower hybrid current drive on EAST

    International Nuclear Information System (INIS)

    Wei Wei; Ding Bo-Jiang; Li Miao-Hui; Zhang Xin-Jun; Wang Xiao-Jie; Peysson, Y; Decker, J; Zhang Lei

    2016-01-01

    The optimized synergy conditions between electron cyclotron current drive (ECCD) and lower hybrid current drive (LHCD) with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on the understanding of the synergy mechanisms so as to obtain a higher synergistic current and provide theoretical reference for the synergistic effect in the EAST experiment. The dependences of the synergistic effect on the parameters of two waves (lower hybrid wave (LHW) and electron cyclotron wave (ECW)), including the radial position of the power deposition, the power value of the LH and EC waves, and the parallel refractive indices of the LHW (N ∥ ) are presented and discussed. (paper)

  13. Enhanced lower hybrid current drive experiments on HT-7 tokamak

    International Nuclear Information System (INIS)

    Shen Weici; Kuang Guangli; Liu Yuexiu; Ding Bojiang; Shi Yaojiang

    2003-01-01

    Effective Lower Hybrid Current Driving (LHCD) and improved confinement experiments in higher plasma parameters (I p >200 kA, n e >2 x 10 13 cm -3 , T e ≥1 keV) have been curried out in optimized LH wave spectrum and plasma parameters in HT-7 superconducting tokamak. The dependence of current driving efficiency on LH power spectrum, plasma density (anti n e ) and toroidal magnetic field B T has been obtained under optimal conditions. A good CD efficiency was obtained at higher plasma current and higher electron density. The improvement of the energy confinement time is accompanied with the increase in line averaged electron density, and in ion and electron temperatures. The highest current driving efficiency reached η CD =I p (anti n e )R/P RF ≅1.05 x 10 19 Am -2 /W. Wave-plasma coupling was sustained in a good state and the reflective coefficient was less than 5%. The experiments have also demonstrated the ability of LH wave in the start-up and ramp-up of the plasma current. The measurement of the temporal distribution of plasma parameter shows that lower hybrid leads to a broader profile in plasma parameter. The LH power deposition profile and the plasma current density profile were modeled with a 2D Fokker-Planck code corresponding to the evolution process of the hard x-ray detector array

  14. 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.

  15. Hamiltonian analysis of fast wave current drive in tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Becoulet, A; Fraboulet, D; Giruzzi, G; Moreau, D; Saoutic, B [Association Euratom-CEA, Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Chinardet, J [CISI Ingenierie, Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France)

    1993-12-01

    The Hamiltonian formalism is used to analyze the direct resonant interaction between the fast magnetosonic wave and the electrons in a tokamak plasma. The intrinsic stochasticity of the electron phase space trajectories is derived, and together with extrinsic de-correlation processes, assesses the validity of the quasilinear approximation for the kinetic studies of fast wave current drive (FWCD). A full-wave resolution of the Maxwell-Vlasov set of equations provides the exact pattern of the wave fields in a complete tokamak geometry, for a realistic antenna spectrum. The local quasilinear diffusion tensor is derived from the wave fields, and is used for a computation of the driven current and deposited power profiles, the current drive efficiency, including possible non-linear effects in the kinetic equation. Several applications of FWCD on existing and future machines are given, as well as results concerning combination of FWCD with other non inductive current drive methods. An analytical expression for the current drive efficiency is given in the high single-pass absorption regimes. (authors). 20 figs., 1 tab., 26 refs.

  16. Hamiltonian analysis of fast wave current drive in tokamak plasmas

    International Nuclear Information System (INIS)

    Becoulet, A.; Fraboulet, D.; Giruzzi, G.; Moreau, D.; Saoutic, B.

    1993-12-01

    The Hamiltonian formalism is used to analyze the direct resonant interaction between the fast magnetosonic wave and the electrons in a tokamak plasma. The intrinsic stochasticity of the electron phase space trajectories is derived, and together with extrinsic de-correlation processes, assesses the validity of the quasilinear approximation for the kinetic studies of fast wave current drive (FWCD). A full-wave resolution of the Maxwell-Vlasov set of equations provides the exact pattern of the wave fields in a complete tokamak geometry, for a realistic antenna spectrum. The local quasilinear diffusion tensor is derived from the wave fields, and is used for a computation of the driven current and deposited power profiles, the current drive efficiency, including possible non-linear effects in the kinetic equation. Several applications of FWCD on existing and future machines are given, as well as results concerning combination of FWCD with other non inductive current drive methods. An analytical expression for the current drive efficiency is given in the high single-pass absorption regimes. (authors). 20 figs., 1 tab., 26 refs

  17. Effect of discrete RF spectrum on fast wave current drive

    International Nuclear Information System (INIS)

    Okazaki, Takashi; Yoshioka, Ken; Sugihara, Masayoshi

    1987-08-01

    Effect of discrete RF spectrum has been studied for the fast wave current drive with the ion cyclotron range of frequency. Driven current and power densities decrease in this spectrum than in the continuous spectrum. However, there is a possibility to have the mechanism which allows electrons outside the resonance region to interact with the fast wave, taking into account the electron trapping by discrete RF spectrum. In the case of neglecting the electron trapping effect, driven current and power densities decrease up to 0.6 - 0.8 of those which are obtained for the continuous spectrum for the FER (Fusion Experimental Reactor). However, their driven current and power densities can be almost doubled in their magnitude for the discrete spectrum by taking into account the trapping effect. (author)

  18. Advanced and intelligent control in power electronics and drives

    CERN Document Server

    Blaabjerg, Frede; Rodríguez, José

    2014-01-01

    Power electronics and variable frequency drives are continuously developing multidisciplinary fields in electrical engineering, and it is practically not possible to write a book covering the entire area by one individual specialist. Especially by taking account the recent fast development in the neighboring fields like control theory, computational intelligence and signal processing, which all strongly influence new solutions in control of power electronics and drives. Therefore, this book is written by individual key specialist working on the area of modern advanced control methods which penetrates current implementation of power converters and drives. Although some of the presented methods are still not adopted by industry, they create new solutions with high further research and application potential. The material of the book is presented in the following three parts: Part I: Advanced Power Electronic Control in Renewable Energy Sources (Chapters 1-4), Part II: Predictive Control of Power Converters and D...

  19. Dynamic modelling of tearing mode stabilization by RF current drive

    International Nuclear Information System (INIS)

    Giruzzi, G.; Zabiego, M.; Gianakon, T.A.; Garbet, X.; Bernabei, S.

    1998-01-01

    The theory of tearing mode stabilization in toroidal plasmas by RF-driven currents that are modulated in phase with the island rotation is investigated. A time scale analysis of the phenomena involved indicates that transient effects, such as finite time response of the driven currents, island rotation during the power pulses, and the inductive response of the plasma, are intrinsically important. A dynamic model of such effects is developed, based on a 3-D Fokker-Planck code coupled to both the electric field diffusion and the island evolution equations. Extensive applications to both Electron Cyclotron and Lower Hybrid current drive in ITER are presented. (author)

  20. Rotating magnetic field current drive-theory and experiment

    International Nuclear Information System (INIS)

    Donnelly, I.J.

    1989-01-01

    Rotating magnetic fields have been used to drive plasma current and establish a range of compact torus configurations, named rotamaks. The current drive mechanism involves a ponderomotive force acting on the electron fluid. Recent extensions of the theory indicate that this method is most suitable for driving currents in directions perpendicular to the steady magnetic fields

  1. 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.

  2. Current Drive in a Ponderomotive Potential with Sign Reversal

    International Nuclear Information System (INIS)

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

    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

  3. Introduction to wave heating and current drive in magnetized plasmas

    International Nuclear Information System (INIS)

    Pinsker, R. I.

    2001-01-01

    The development of high-power wave heating and current drive in magnetized plasmas in the last 40 years is a major ongoing success story in plasma science. A hallmark of this area of research has been the detailed quantitative comparison of theory and experiment; the good agreement consistently found is indicative of the robustness and the predictive power of the underlying theory. This tutorial paper is a brief overview of the fundamental concepts and applications of this branch of plasma science. Most of the high-power applications have been in three frequency regimes: the ion cyclotron range of frequencies (ICRF), the lower hybrid range of frequencies (LHRF), and the electron cyclotron range of frequencies (ECRF). The basic physics of wave propagation and damping in these regimes is briefly discussed. Some of the coupling structures (antennas) used to excite the waves at the plasma boundary are described, and the high-power systems used to generate the wave energy are touched on. Representative examples of the remarkably wide range of applications of high-power wave heating and current drive in high-temperature fusion plasmas will be discussed

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

    Science.gov (United States)

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

    2017-10-01

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

  5. Electron cyclotron current drive experiments on DIII-D

    International Nuclear Information System (INIS)

    James, R.A.; Giruzzi, G.; Gentile, B. de; Rodriguez, L.; Fyaretdinov, A.; Gorelov, Yu.; Trukhin, V.; Harvey, R.; Lohr, J.; Luce, T.C.; Matsuda, K.; Politzer, P.; Prater, R.; Snider, R.; Janz, S.

    1990-05-01

    Electron Cyclotron Current Drive (ECCD) experiments on the DIII-D tokamak have been performed using 60 GHz waves launched from the high field side of the torus. Preliminary analysis indicates rf driven currents between 50 and 100 kA in discharges with total plasma currents between 200 and 500 kA. These are the first ECCD experiments with strong first pass absorption, localized deposition of the rf power, and τ E much longer than the slowing-down time of the rf generated current carriers. The experimentally measured profiles for T e , η e and Z eff are used as input for a 1D transport code and a multiply-ray, 3D ray tracing code. Comparisons with theory and assessment of the influence of the residual electric field, using a Fokker-Planck code, are in progress. The ECH power levels were between 1 and 1.5 MW with pulse lengths of about 500 msec. ECCD experiments worldwide are motivated by issues relating to the physics and technical advantages of the use of high frequency rf waves to drive localized currents. ECCD is accomplished by preferentially heating electrons moving in one toroidal direction, reducing their collisionality and thereby producing a non-inductively driven toroidal current. 6 refs., 4 figs

  6. ICRF current drive by using antenna phase control

    International Nuclear Information System (INIS)

    Kishimoto, Y.; Itoh, K.

    1987-01-01

    A global analysis of current drive in tokamaks by using waves in the ion cyclotron range of frequencies (ICRF), considering the entire antenna-plasma system, is presented. A phase shifted antenna array is used to inject toroidal momentum into the electrons. Within the context of quasi-linear theory, a Fokker-Planck calculation is combined with an ICRF wave propagation-absorption analysis which includes kinetic effects and realistic boundary conditions. The radial profile of the current induced by the mode converted ion Bernstein wave and by the magnetosonic fast wave is obtained, together with the global current drive efficiency (total induced current/total emitted power from the antennas) in the high density and temperature plasma regime. The phase dependence of the global efficiency is investigated by changing the launching conditions such as the total antenna number and the antenna spacing. In medium size tokamaks, the electron power absorption and the associated driven current are found to be affected considerably by the plasma cavity resonance. It is also found that the global efficiency is sensitive to the antenna spacing. When the antenna spacing is increased, the global efficiency is reduced by counter current generation. (author)

  7. Electron cyclotron current drive experiments on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    James, R.A. (Lawrence Livermore National Lab., CA (USA)); Giruzzi, G.; Gentile, B. de; Rodriguez, L. (Association Euratom-CEA, Centre d' Etudes Nucleaires de Cadarache, 13 - Saint-Paul-les-Durance (France)); Fyaretdinov, A.; Gorelov, Yu.; Trukhin, V. (Kurchatov Inst. of Atomic Energy, Moscow (USSR)); Harvey, R.; Lohr, J.; Luce, T.C.; Matsuda, K.; Politzer, P.; Prater, R.; Snider, R. (General Atomics, San Di

    1990-05-01

    Electron Cyclotron Current Drive (ECCD) experiments on the DIII-D tokamak have been performed using 60 GHz waves launched from the high field side of the torus. Preliminary analysis indicates rf driven currents between 50 and 100 kA in discharges with total plasma currents between 200 and 500 kA. These are the first ECCD experiments with strong first pass absorption, localized deposition of the rf power, and {tau}{sub E} much longer than the slowing-down time of the rf generated current carriers. The experimentally measured profiles for T{sub e}, {eta}{sub e} and Z{sub eff} are used as input for a 1D transport code and a multiply-ray, 3D ray tracing code. Comparisons with theory and assessment of the influence of the residual electric field, using a Fokker-Planck code, are in progress. The ECH power levels were between 1 and 1.5 MW with pulse lengths of about 500 msec. ECCD experiments worldwide are motivated by issues relating to the physics and technical advantages of the use of high frequency rf waves to drive localized currents. ECCD is accomplished by preferentially heating electrons moving in one toroidal direction, reducing their collisionality and thereby producing a non-inductively driven toroidal current. 6 refs., 4 figs.

  8. Fast wave current drive on DIII-D

    International Nuclear Information System (INIS)

    deGrassie, J.S.; Petty, C.C.; Pinsker, R.I.

    1995-01-01

    The physics of electron heating and current drive with the fast magnetosonic wave has been demonstrated on DIII-D, in reasonable agreement with theoretical modeling. A recently completed upgrade to the fast wave capability should allow full noninductive current drive in steady state advanced confinement discharges and provide some current density profile control for the Advanced Tokamak Program. DIII-D now has three four-strap fast wave antennas and three transmitters, each with nominally 2 MW of generator power. Extensive experiments have been conducted with the first system, at 60 MHz, while the two newer systems have come into operation within the past year. The newer systems are configured for 60 to 120 MHz. The measured FWCD efficiency is found to increase linearly with electron temperature as γ = 0.4 x 10 18 T eo (keV) [A/m 2 W], measured up to central electron temperature over 5 keV. A newly developed technique for determining the internal noninductive current density profile gives efficiencies in agreement with this scaling and profiles consistent with theoretical predictions. Full noninductive current drive at 170 kA was achieved in a discharge prepared by rampdown of the Ohmic current. Modulation of microwave reflectometry signals at the fast wave frequency is being used to investigate fast wave propagation and damping. Additionally, rf pick-up probes on the internal boundary of the vessel provide a comparison with ray tracing codes, with dear evidence for a toroidally directed wave with antenna phasing set for current drive. There is some experimental evidence for fast wave absorption by energetic beam ions at high cyclotron harmonic resonances

  9. Fast wave current drive on DIII-D

    International Nuclear Information System (INIS)

    deGrassie, J.S.; Petty, C.C.; Pinsker, R.I.; Forest, C.B.; Ikezi, H.; Prater, R.; Baity, F.W.; Callis, R.W.; Cary, W.P.; Chiu, S.C.; Doyle, E.J.; Ferguson, S.W.; Hoffman, D.J.; Jaeger, E.F.; Kim, K.W.; Lee, J.H.; Lin-Liu, Y.R.; Murakami, M.; ONeill, R.C.; Porkolab, M.; Rhodes, T.L.; Swain, D.W.

    1996-01-01

    The physics of electron heating and current drive with the fast magnetosonic wave has been demonstrated on DIII-D, in reasonable agreement with theoretical modeling. A recently completed upgrade to the fast wave capability should allow full noninductive current drive in steady state advanced confinement discharges and provide some current density profile control for the Advanced Tokamak Program. DIII-D now has three four-strap fast wave antennas and three transmitters, each with nominally 2 MW of generator power. Extensive experiments have been conducted with the first system, at 60 MHz, while the two newer systems have come into operation within the past year. The newer systems are configured for 60 to 120 MHz. The measured FWCD efficiency is found to increase linearly with electron temperature as γ=0.4x10 18 T e0 (keV) [A/m 2 W], measured up to central electron temperature over 5 keV. A newly developed technique for determining the internal noninductive current density profile gives efficiencies in agreement with this scaling and profiles consistent with theoretical predictions. Full noninductive current drive at 170 kA was achieved in a discharge prepared by rampdown of the Ohmic current. Modulation of microwave reflectometry signals at the fast wave frequency is being used to investigate fast wave propagation and damping. Additionally, rf pick-up probes on the internal boundary of the vessel provide a comparison with ray tracing codes, with clear evidence for a toroidally directed wave with antenna phasing set for current drive. copyright 1996 American Institute of Physics

  10. PHYSICS OF ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D

    International Nuclear Information System (INIS)

    PETTY, C.C.; PRATER, R.; LUCE, T.C.; ELLIS, R.A.; HARVEY, R.W.; KINSEY, J.E.; LAO, L.L.; LOHR, J.; MAKOWSKI, M.A.

    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

  11. On ray stochasticity during lower hybrid current drive in tokamaks

    International Nuclear Information System (INIS)

    Bizarro, J.P.; Moreau, D.

    1992-08-01

    A comprehensive and detailed analysis is presented on the importance of toroidally induced ray stochasticity for the modelling of lower hybrid current drive and for the dynamics of the launched power spectrum. A combined ray tracing and Fokker-Planck code is used and the injected lower hybrid power distribution in poloidal angle and in parallel wave index is accurately represented by taking into account the poloidal extent of the antenna ad by efficiently covering the full range of its radiated spectrum. The importance of the balance between the wave damping and the exponential divergence of nearby ray trajectories in determining the shape of the predicted lower hybrid power deposition profiles is emphasized. When a sufficiently large number of rays is used to densely cover the region of the launched power spectrum which is affected by stochastic effects, code predictions are shown to be stable with respect to small changes in initial conditions and plasma parameters and to be consistent with experimental data

  12. First results on fast wave current drive in advanced tokamak discharges in DIII-D

    International Nuclear Information System (INIS)

    Prater, R.; Cary, W.P.; Baity, F.W.

    1995-07-01

    Initial experiments have been performed on the DIII-D tokamak on coupling, direct electron heating, and current drive by fast waves in advanced tokamak discharges. These experiments showed efficient central heating and current drive in agreement with theory in magnitude and profile. Extrapolating these results to temperature characteristic of a power plant (25 keV) gives current drive efficiency of about 0.3 MA/m 2

  13. Electron cyclotron current drive in the Wendelstein 7-AS stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Maassberg, H [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Rome, M [I.N.F.N., I.N.F.M., Dipartimento di Fisica, Universita degli Studi, I-20133 Milan (Italy); Erckmann, V [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Geiger, J [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Laqua, H P [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Marushchenko, N B [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)

    2005-08-01

    High power electron cyclotron current drive (ECCD) experiments in the W7-AS stellarator are analysed. In these net-current-free discharges, the ECCD and the bootstrap current are feedback controlled by an inductive current. Based on the measured density and temperature profiles, the neoclassical predictions of the bootstrap (with the ambipolar radial electric field taken into account) and the inductive current densities as well as the ECCD from the linear adjoint approach with trapped particles included are calculated. For stationary conditions, the current balance is checked. Launch-angle scans at fixed density as well as density scans at fixed launch-angle are described. Low-frequency MHD mode activity is obtained for strong co-ECCD, and for counter-ECCD a ' {iota}-bar approx.= 0 feature' with complete loss of the central confinement is found. The linear ECCD prediction is in reasonable agreement with the current balance except for low-density discharges with highly peaked on-axis deposition, where the ECCD predicted from linear theory exceeds by a factor of about 2 the one from the current balance. Since the bootstrap current is well balanced by the inductive current without ECCD, the linear ECCD overestimate is compared with nonlinear Fokker-Planck (FP) simulations, where two different power loss models are used to reach steady state. These volume-averaged FP simulations cannot describe the ECCD degradation at the low densities.

  14. Electron cyclotron current drive in the Wendelstein 7-AS stellarator

    International Nuclear Information System (INIS)

    Maassberg, H; Rome, M; Erckmann, V; Geiger, J; Laqua, H P; Marushchenko, N B

    2005-01-01

    High power electron cyclotron current drive (ECCD) experiments in the W7-AS stellarator are analysed. In these net-current-free discharges, the ECCD and the bootstrap current are feedback controlled by an inductive current. Based on the measured density and temperature profiles, the neoclassical predictions of the bootstrap (with the ambipolar radial electric field taken into account) and the inductive current densities as well as the ECCD from the linear adjoint approach with trapped particles included are calculated. For stationary conditions, the current balance is checked. Launch-angle scans at fixed density as well as density scans at fixed launch-angle are described. Low-frequency MHD mode activity is obtained for strong co-ECCD, and for counter-ECCD a ' ι-bar approx.= 0 feature' with complete loss of the central confinement is found. The linear ECCD prediction is in reasonable agreement with the current balance except for low-density discharges with highly peaked on-axis deposition, where the ECCD predicted from linear theory exceeds by a factor of about 2 the one from the current balance. Since the bootstrap current is well balanced by the inductive current without ECCD, the linear ECCD overestimate is compared with nonlinear Fokker-Planck (FP) simulations, where two different power loss models are used to reach steady state. These volume-averaged FP simulations cannot describe the ECCD degradation at the low densities

  15. Relativistic theory of current drive by radio frequency waves in a magnetized plasma

    International Nuclear Information System (INIS)

    Khan, T.P.

    1992-01-01

    A relativistic kinetic theory of rf current drive in a magnetized plasma is developed. Analytical expressions are obtained for the rf generated currents, the dissipated power, and the current drive efficiency in the presence of a magnetic field. The relativistic transport coefficients in both parallel and perpendicular directions of the magnetic field are exhibited to have important contributions to the efficiency of rf-generated current drive. The consideration of perpendicular particle and heat fluxes make it more attractive for fusion problems. The effect of collisions in the presence of a magnetic field on the transport of the rf-generated current drive is discussed

  16. Inside launch electron cyclotron heating and current drive on DITE

    International Nuclear Information System (INIS)

    Ashraf, M.; Deliyanakis, N.

    1989-01-01

    Electron cyclotron resonance heating at 60 GHz has been carried out on DITE (R = 1.2 m, a = 0.24 m) to investigate heating and current drive using the extraordinary mode launched with finite k parallel from the high field side. The first clear evidence of Doppler shifted resonance absorption in a near-thermal plasma is obtained. The heating efficiency is observed to fall sharply at densities above cut-off for the wave. At lower densities the increment in power to the limiter is measured during ECRH and is compared with that expected from the global power balance. The degradation in particle confinement often associated with ECRH is observed as an increased particle flux at the boundary driven by local electrostatic fluctuations. Initial experiments on the electron cyclotron wave driven current at the second harmonic show effects that are consistent with the low efficiency expected from theory including trapped particle effects. (author). 9 refs, 4 figs

  17. Lower hybrid current drive in Tore Supra and JET

    International Nuclear Information System (INIS)

    Moreau, D.; Gormezano, C.

    1991-01-01

    Recent Lower Hybrid Current Drive (LHCD) experiments in TORE SUPRA and JET are reported. Large multijunction launchers have allowed the coupling of 5MW to the plasma for several seconds with a maximum of 3.8 kW/cm 2 . Measurements of the scattering matrices of the antennae show good agreement with theory. The current drive efficiency in TORE SUPRA is about 0.2 x 10 20 Am -2 /W with LH power alone and reaches 0.4 x 10 20 Am -2 /W in JET thanks to a high volume-averaged electron temperature (1.9 keV) and also to a synergy between Lower Hybrid and Fast Magnetosonic Waves. At n e = 1.5 x 10 19 m -3 in TORE SUPRA, sawteeth are suppressed and m = 1MHD oscillations the frequency of which clearly depends on the amount of LH power are observed on soft X-rays, and also on non-thermal ECE. In Jet ICRH produced sawtooth free periods are extended by the application of LHCD and current profile broadening has been clearly observed consistent with off-axis fast electron populations. LH power modulation experiments performed in TORE SUPRA at n e = 4 x 10 19 m -3 show a delayed central electron heating despite the off-axis creation of suprathermal electrons, thus ruling out the possibility of a direct heating through central wave absorption. A possible explanation in terms of anomalous fast electron transport and classical slowing down would yield a diffusion coefficient of the order of 10 m 2 /s for the fast electrons. Finally, successful pellet fuelling of a partially LH driven plasma was obtained in TORE SUPRA, 28 successive pellets allowing the density to rise to n e = 4 x 10 19 m -3 . This could be achieved by switching the LH power off for 90 ms before each pellet injection, i.e. without modifying significantly the current density profile

  18. Fast wave current drive in reactor scale tokamaks

    International Nuclear Information System (INIS)

    Moreau, D.

    1992-01-01

    The IAEA Technical Committee Meeting on Fast Wave Current Drive in Reactor Scale Tokamaks, hosted by the Commissariat a l'Energie Atomique (CEA), Departement de Recherches sur la Fusion Controlee (Centres d'Etudes de Cadarache, under the Euratom-CEA Association for fusion) aimed at discussing the physics and the efficiency of non-inductive current drive by fast waves. Relevance to reactor size tokamaks and comparison between theory and experiment were emphasized. The following topics are described in the summary report: (i) theory and modelling of radiofrequency current drive (theory, full wave modelling, ray tracing and Fokker-Planck calculations, helicity injection and ponderomotive effects, and alternative radio-frequency current drive effects), (ii) present experiments, (iii) reactor applications (reactor scenarios including fast wave current drive; and fast wave current drive antennas); (iv) discussion and summary. 32 refs

  19. Power transistor module for high current applications

    International Nuclear Information System (INIS)

    Cilyo, F.F.

    1975-01-01

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

  20. Current drive in a ponderomotive potential with sign reversal

    International Nuclear Information System (INIS)

    Fisch, N.J.; Dodin, I.Y.; 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, which operates somewhat like a Maxwell demon, can be practiced upon both ions and electrons. The current-drive efficiencies, in principle, might be higher than those possible with conventional rf current-drive techniques. It remains, however, for us to identify how the effect might be implemented in a magnetic fusion device in a practical manner

  1. Current drive by electron cyclotron waves in NET

    International Nuclear Information System (INIS)

    Giruzzi, G.; Schep, T.J.; Westerhof, E.

    1989-01-01

    A potentially attractive scenario for steady-state operations in the Next European Torus relies on the use of lower-hybrid (LH) waves for non-inductive current drive in the plasma periphery and of electron cyclotron (EC) waves in the aim of determining the best options for the ECN current drive system and of evaluating the expected current drive efficiency. (author). 7 refs.; 6 figs.; 1 tab

  2. The jet 10-MW lower hybrid current drive system

    International Nuclear Information System (INIS)

    Gormezano, C.; Bosia, G.; Brinkschulte, H.; David, C.; Dobbing, J.A.; Kaye, A.S.; Jacquinot, J.; Lloyd, B.; Knowlton, S.; Moreau, D.

    1987-01-01

    A Lower Hybrid system to control the plasma current profile is being prepared so that a higher central electron temperature can be obtained. The proposed system is designed to launch 10 MW of power at f = 3.7 GHz through a single port in JET, producing between 1 and 2 MA of RF driven current at an average density of 5 x 10 19 m -3 . Current drive efficiency is maximized by using a low value of the parallel wave number spectrum (N// - 1.3 - 2.3). The final launcher will be made of 48 multijunctions fed by 24 klystrons with the proper phasing. Dynamic matching of the launcher will be optimized by moving the launcher in real time during the pulse. A first stage (2 MW) is presently under construction. The full system is being designed to be in operation in 1990

  3. Studies on fast wave current drive in the JAERI tokamaks

    International Nuclear Information System (INIS)

    Kimura, H.; Yamamoto, T.; Fujii, T.; Kawashima, H.; Tamai, H.; Saigusa, M.; Imai, T.; Hamamatsu, K.; Fukuyama, A.

    1991-01-01

    Fast wave electron heating experiment (FWEH) on JFT-2M and JT-60 and analysis of fast wave current drive (FWCD) ability on JT-60U are presented. In the JFT-2M, absorption of fast waves have been investigated by using a phased four-loop antenna array. The absorption of the fast waves has been studied for various plasma parameters by using combination of other additional heating methods such as electron cyclotron heating (ECH) and ion cyclotron heating. It is shown that the absorption efficiency estimated from various methods well correlates with one calculated theoretically in single pass damping. Interaction of the fast waves with fast electrons in combination with ECH has been examined through the measurement of non-thermal electron cyclotron emission (ECE). The observed ECE during FWEH is well explained by the theoretical model, which indicates generation of the appreciable energetic fast electrons by the fast waves. New four-loop array antennas have been employed to improve the absorption of unidirectionally-propagating waves. Characteristics of antenna loading resistance can be reproduced by a coupling calculation code. In JT-60, FWEH experiment in combination with lower hybrid current drive was performed. Power absorption efficiency of fast wave is substantially improved in combination with LHCD of relatively low power for both phasing modes. Bulk electron heating is observed with high-k // mode and coupling with fast electron is confirmed in hard X-ray emission with low-k // mode. The results are consistent with theoretical prediction based on 1.D full wave code. Synergetic effects between FWEH and LHCD are found. Coupling calculation indicates that eight-loop antenna is favourable for keeping high directivity in the required N // -range. Current drive efficiency is calculated with 1-D full wave code including trapped particle effects and higher harmonic ion cyclotron damping

  4. Spectral Effects on Fast Wave Core Heating and Current Drive

    International Nuclear Information System (INIS)

    Phillips, C.K.; Bell, R.E.; Berry, L.A.; Bonoli, P.T.; Harvey, R.W.; Hosea, J.C.; Jaeger, E.F.; LeBlanc, B.P.; Ryan, P.M.; Taylor, G.; Valeo, E.J.; Wilson, J.R.; Wright, J.C.; Yuh, H. and the NSTX Team

    2009-01-01

    Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L mode and H mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit rf power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of high harmonic fast wave current drive were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations

  5. Considerations on ECFH current drive and bootstrap current for W VII-X

    International Nuclear Information System (INIS)

    Gasparino, U.; Maassberg, H.

    1988-01-01

    Low shear is the characteristic of all proposed Wendelstein VII-X configurations. To avoid low harmonic rational numbers within the rotational transform profile, the current contribution to the rotational transform, Δt a α I/B, should be typically less than 10%. This leads to an upper limit of 50 kA (at B = 2.5 T) for the tolerable net toroidal current. A considerable net toroidal current (bootstrap current) is expected by neoclassical theory in the plateau and the low-collisionality regimes. Both radial transport as well as the bootstrap current densities depend sensitively on the magnetic configuration (see A. Montvai, this workshop). In case of an axisymmetric configuration with dimension and plasma parameters as predicted for the high- regime of WVII-X ( ∼ 5%), this current (∼ 0.5/1 MA) would dominate the rotational transform profile. This requires a reduction of magnitude of the bootstrap current to some % of the value of an equivalent tokamak. This reduction must act on the current profile itself and should not be merely obtained by having two channels of currents of different sign at different radii. Due to the possibility of controlling absorbed power and driven current profiles, electron cyclotron waves are a natural candidate for current profile control. Linear calculations show the possibility to drive a counteracting current with a profile similar to the bootstrap one. For ∼ 5% conditions, however, the optimium current drive efficiency (η ∼ 10 kA per MW) is far too low to make ECF-current drive suitable

  6. Comparison between voltage by turn measured on different tokamaks operating in hybrid wave current drive regime

    International Nuclear Information System (INIS)

    Briffod, G.; Hoang, G.T.

    1987-06-01

    On a tokamak in a current drive operation with a hybrid wave, the R.F. current is estimated from the voltage drop by plasma turn generated by R.F. power application. This estimated current is not proportional to the injected power. There still exists in the plasma an electric field corresponding to the current part produced by induction. The role evaluation of this parameter on the current drive efficiency is important. In this report the relation voltage-R.F. current is studied on Petula and results on the voltage evolution by turn on different machines are compared [fr

  7. A computational model for lower hybrid current drive

    International Nuclear Information System (INIS)

    Englade, R.C.; Bonoli, P.T.; Porkolab, M.

    1983-01-01

    A detailed simulation model for lower hybrid (LH) current drive in toroidal devices is discussed. This model accounts reasonably well for the magnitude of radio frequency (RF) current observed in the PLT and Alcator C devices. It also reproduces the experimental dependencies of RF current generation on toroidal magnetic field and has provided insights about mechanisms which may underlie the observed density limit of current drive. (author)

  8. Current stopping power analyses

    International Nuclear Information System (INIS)

    Porter, L.E.

    1983-01-01

    Modified Bethe-Bloch stopping power theory permits fairly accurate calculation of energy losses over a broad interval of projectile velocity v = νc insofar as several parameters appearing in the revised Bethe-Bloch formula have been corectly evaluated. Since the parameters cannot in general be ascertained by calculation from first principles, fits of theory to measurement remain the best method of evaluation. The parameters alluded to are: the target mean excitation energy; the shell correction scaling parameters; the composite single free parameter of the Barkas (projectile-z 3 ) effect correction formalism, and the strength of the correction term; the high velocity density effect correction parameter; and the low velocity charge state parameter. These parameters are discussed

  9. Noninductive current drive for INTOR: A comparison of four driver options

    International Nuclear Information System (INIS)

    Ehst, D.A.; Evans, K. Jr.; Mikkelsen, D.R.; Ignat, D.W.; Mau, T.K.

    1987-01-01

    The current drive power and normalized efficiency are calculated for the INTOR tokamak, including spatial profiles of the plasma and current density. Current drive requirements are computed for purely steady state operation with no electromotive force and also in the presence of a reversed emf typical of start-up or transformer recharging. Results are obtained for lower-hybrid-waves, high frequency fast waves, low frequency fast waves and neutral beam injection

  10. Electron Bernstein wave current drive in the start-up phase of a tokamak discharge

    International Nuclear Information System (INIS)

    Montes, A.; Ludwig, G.O.

    1986-04-01

    Current drive by electron Bernstein waves in the start-up phase of tokamak discharges is studied. A general analytical expression is derived for the figure of merit J/Pd associated with these waves. This is coupled with a ray tracing code, allowing the calculation of the total current generated per unit of incident power in realistic tokamak conditions. The resuts show that the electron Bernstein waves can drive substantial currents even at very low electron temperatures. (Author) [pt

  11. Current drive and sustain experiments with the bootstrap current in JT-60

    International Nuclear Information System (INIS)

    Kikuchi, Mitsuru; Azumi, Masafumi; Tani, Keiji; Tsuji, Shunji; Kubo, Hirotaka

    1989-11-01

    The current drive and sustain experiments with the neoclassical bootstrap current are performed in the JT-60 tokamak. It is shown that up to 80% of total plasma current is driven by the bootstrap current in extremely high β p regime (β p = 3.2) and the current drive product I p (bootstrap) n-bar e R p up to 4.4 x 10 19 MAm -2 has been attained with the bootstrap current. The experimental resistive loop voltages are compared with the calculations using the neoclassical resistivity with and without the bootstrap current and the Spitzer resistivity for a wide range of the plasma current (I p = 0.5 -2 MA) and the poloidal beta (β p = 0.1 - 3.2). The calculated resistive loop voltage is consistent with the neoclassical prediction including the bootstrap current. Current sustain with the bootstrap current is tested by terminating the I p feedback control during the high power neutral beam heating. An enhancement of the L/R decay time than those expected from the plasma resistivity with measured T e and Zeff has been confirmed experimentally supporting the large non-inductive current in the plasma and is consistent with the neoclassical prediction. A new technique to calculate the bootstrap current in multi-collisionality regime for finite aspect ratio tokamak has bee developed. The neoclassical bootstrap current is calculated directly through the force balance equations between viscous and friction forces according to the Hirshman-Sigmar theory. The bootstrap current driven by the fast ion component is also included. Ballooning stability of the high β p plasma are analyzed using the current profiles including the bootstrap current. The plasma pressure is close to the ballooning limit in high β p discharges. (author)

  12. Theory of current-drive in plasmas

    International Nuclear Information System (INIS)

    Fisch, N.J.

    1986-12-01

    The continuous operation of a tokamak fusion reactor requires, among other things, a means of providing continuous toroidal current. Such operation is preferred to the conventional pulsed operation, where the plasma current is induced by a time-varying magnetic field. A variety of methods has been proposed to provide continuous current, including methods which utilize particle beams or radio frequency waves in any of several frequency regimes. Currents as large as half a mega-amp have now been produced in the laboratory by such means, and experimentation in these techniques has now involved major tokamak facilities worldwide

  13. Intense relativistic electron beam injector system for tokamak current drive

    International Nuclear Information System (INIS)

    Bailey, V.L.; Creedon, J.M.; Ecker, B.M.; Helava, H.I.

    1983-01-01

    We report experimental and theoretical studies of an intense relativistic electron beam (REB) injection system designed for tokamak current drive experiments. The injection system uses a standard high-voltage pulsed REB generator and a magnetically insulated transmission line (MITL) to drive an REB-accelerating diode in plasma. A series of preliminary experiments has been carried out to test the system by injecting REBs into a test chamber with preformed plasma and applied magnetic field. REBs were accelerated from two types of diodes: a conventional vacuum diode with foil anode, and a plasma diode, i.e., an REB cathode immersed in the plasma. REB current was in the range of 50 to 100 kA and REB particle energy ranged from 0.1 to 1.0 MeV. MITL power density exceeded 10 GW/cm 2 . Performance of the injection system and REB transport properties is documented for plasma densities from 5 x 10 12 to 2 x 10 14 cm -3 . Injection system data are compared with numerical calculations of the performance of the coupled system consisting of the generator, MITL, and diode

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

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Nevins, W.M.; Porkolab, M.; Bonoli, P.T.; Harvey, R.W.

    1994-01-01

    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 will be 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 e and T e , and launched wave spectrum will also be shown

  15. 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

    operation. This is a cost effective topology compared to a standard matrix converter because the multiple three-phase loads share the cost of the controlled rectification stage. A new method to reduce the high frequency ripple from the input current is also proposed based on interleaving the switching...

  16. Lower hybrid current drive experiments in Tore Supra

    International Nuclear Information System (INIS)

    Moreau, D.

    1991-12-01

    Two large multi junction launchers have allowed to couple up to 6 MW to the plasma. The current drive efficiency was about 2 x 10 19 Am -2 /W with LH power alone at a volume-averaged electron temperature of 1.4 keV. Experiments with combined LHCD and ion cyclotron resonant heating allowed to inject up to 7.5 MW into the plasma. The electron energy content followed fairly well the Rebut-Lallia scaling law. At n e = 1.5 x 10 19 m -3 , sawteeth were suppressed and m = 1 MHD oscillations appeared. The central electron temperature then reached 8 keV for 3.6 MW injected. LH power modulation experiments performed at n e = 4 x 10 19 m -3 showed a delayed central electron heating despite the off-axis creation of suprathermal electrons, thus ruling out the possibility of direct heating through central wave absorption. Successful pellet fueling of a partially LH driven plasma was obtained, in which 28 successive pellets could penetrate up to half radius as in ohmic discharges, with 50 to 80% of the pellet content deposited in the plasma. First attempts to combine LHCD with ergodic divertor discharges showed that, when the plasma edge was subject to a radial magnetic perturbation smaller than the ergodicity threshold, a strong stationary radiation (MARFE) was triggered, locked near the inner wall. The radiated power then amounted to 90% of the total input power with no indication of a radiative collapse

  17. Gate Drive For High Speed, High Power IGBTs

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, M.N.; Cassel, R.L.; de Lamare, J.E.; Pappas, G.C.; /SLAC

    2007-06-18

    A new gate drive for high-voltage, high-power IGBTs has been developed for the SLAC NLC (Next Linear Collider) Solid State Induction Modulator. This paper describes the design and implementation of a driver that allows an IGBT module rated at 800A/3300V to switch up to 3000A at 2200V in 3{micro}S with a rate of current rise of more than 10000A/{micro}S, while still being short circuit protected. Issues regarding fast turn on, high de-saturation voltage detection, and low short circuit peak current will be presented. A novel approach is also used to counter the effect of unequal current sharing between parallel chips inside most high-power IGBT modules. It effectively reduces the collector-emitter peak current, and thus protects the IGBT from being destroyed during soft short circuit conditions at high di/dt.

  18. Gate Drive For High Speed, High Power IGBTs

    International Nuclear Information System (INIS)

    Nguyen, M.N.; Cassel, R.L.; de Lamare, J.E.; Pappas, G.C.; SLAC

    2007-01-01

    A new gate drive for high-voltage, high-power IGBTs has been developed for the SLAC NLC (Next Linear Collider) Solid State Induction Modulator. This paper describes the design and implementation of a driver that allows an IGBT module rated at 800A/3300V to switch up to 3000A at 2200V in 3(micro)S with a rate of current rise of more than 10000A/(micro)S, while still being short circuit protected. Issues regarding fast turn on, high de-saturation voltage detection, and low short circuit peak current will be presented. A novel approach is also used to counter the effect of unequal current sharing between parallel chips inside most high-power IGBT modules. It effectively reduces the collector-emitter peak current, and thus protects the IGBT from being destroyed during soft short circuit conditions at high di/dt

  19. Lower hybrid current drive in Tore Supra and jet

    International Nuclear Information System (INIS)

    Moreau, D.; Gormezano, C.

    1991-07-01

    Recent Lower Hybrid Current Drive (LHCD) experiments in TORE SUPRA and JET are reported. Large multijunction launchers have allowed the coupling of 5 MW to the plasma for several seconds with a maximum of 3.8 kW/cm 2 . Measurements of the scattering matrices of the antennae show good agreement with theory. The current drive efficiency in TORE SUPRA is about 0.2 x 10 20 Am -2 /W with LH power alone and reaches 0.4 x 10 20 Am -2 /W in JET thanks to a high volume-averaged electron temperature (1.9 keV) and also to a synergy between Lower Hybrid and Fast Magnetosonic Waves. At average n e = 1.5 x 10 19 m -3 in TORE SUPRA, sawteeth are suppressed and m = 1 MHD oscillations the frequency of which clearly depends on the amount of LH power are observed on soft X-rays, and also on non-thermal ECE. In JET ICRH produced sawtooth-free periods are extended by the application of LHCD (2.9 s. with 4 MW ICRH) and current profile broadening has been clearly observed consistent with off-axis fast electron populations. LH power modulation experiments performed in TORE SUPRA at average n e = 4 x 10 19 m -3 show a delayed central electron heating despite the off-axis creation of suprathermal electrons, thus ruling out the possibility of a direct heating through central wave absorption. A possible explanation in terms of anomalous fast electron transport and classical slowing down would yield a diffusion coefficient of the order of 10 m 2 /s for the fast electrons. Other interpretations such as an anomalous heat pinch or a central confinement enhancement cannot be excluded. Finally, successful pellet fuelling of a partially LH driven plasma was obtained in TORE SUPRA, 28 successive pellets allowing the density to rise to average n e = 4 x 10 19 m -3 . This could be achieved by switching the LH power off for 90 ms before each pellet injection, i.e. without modifying significantly the current density profile

  20. Confinement improvement with rf poloidal current drive in the reversed-field pinch

    International Nuclear Information System (INIS)

    Hokin, S.; Sarff, J.; Sovinec, C.; Uchimoto, E.

    1994-01-01

    External control of the current profile in a reversed-field pinch (RFP), by means such as rf poloidal current drive, may have beneficial effects well beyond the direct reduction of Ohmic input power due to auxiliary heating. Reduction of magnetic turbulence associated with the dynamo, which drives poloidal current in a conventional RFP, may allow operation at lower density and higher electron temperature, for which rf current drive becomes efficient and the RFP operates in a more favorable regime on the nτ vs T diagram. Projected parameters for RFX at 2 MA axe studied as a concrete example. If rf current drive allows RFX to operate with β = 10% (plasma energy/magnetic energy) at low density (3 x 10 19 m -3 ) with classical resistivity (i.e. without dynamo-enhanced power input), 40 ms energy confinement times and 3 keV temperatures will result, matching the performance of tokamaks of similar size

  1. Experiments of full non-inductive current drive on HT-7

    International Nuclear Information System (INIS)

    Zhang, X.D.; Wu, Z.W.; Chen, Z.Y.; Gong, X.Z.; Wang, H.; Xu, D.; Huang, Y.; Luo, J.; Gao, X.; Hu, L.; Zhao, J.; Wan, B.N.; Li, J.

    2005-01-01

    Some experimental results of steady-state operation and full non-inductive current drive have been obtained on HT-7. Three types of experiment are used to study long pulse discharge, quasi-steady-state operation and full non-inductive current drive. The experiments show that the plasma current in the full non-inductive drive case is instable due to no adjusting effect of OH heating field, when the waveguide tube discharge lead to the LHW power injecting tokamak plasma decrease. This instability of plasma current will increase the interaction of plasma with limiter and first surface and bring impurity. All discharges of full non-inductive current drive are terminated because of impurity spurting. To adjust the LHW injection power for control the loop voltage during long pulse discharge is the most effective method for steady-state operation on HT-7. (author)

  2. Electron heating and current drive by mode converted slow waves

    International Nuclear Information System (INIS)

    Majeski, R.; Phillips, C.K.; Wilson, J.R.

    1994-01-01

    An approach to obtaining efficient single pass mode conversion at high parallel wave number from the fast magnetosonic wave to the slow ion Bernstein wave, in a two-ion species tokamak plasma, is described. The intent is to produce localized electron heating or current drive via the mode converted slow wave. In particular, this technique can be adapted to off-axis current drive for current profile control. Modeling for the case of deuterium-tritium plasmas in TFTR is presented

  3. Electron heating and current drive by mode converted slow waves

    International Nuclear Information System (INIS)

    Majeski, R.; Phillips, C.K.; Wilson, J.R.

    1994-08-01

    An approach to obtaining efficient single pass mode conversion at high parallel wavenumber from the fast magnetosonic wave to the slow ion Bernstein wave, in a two ion species tokamak plasma, is described. The intent is to produce localized electron heating or current drive via the mode converted slow wave. In particular, this technique can be adapted to off-axis current drive for current profile control. Modelling for the case of deuterium-tritium plasmas in TFTR is presented

  4. Kinetic theory of rf current drive and helicity injection

    International Nuclear Information System (INIS)

    Mett, R.R.

    1992-01-01

    Current drive and helicity injection by plasma waves are examined with the use of kinetic theory. The Vlasov equation yields a general current drive formula that contains resonant and nonresonant (ponderomotivelike) contributions. Standard quasilinear current drive is described by the former, while helicity current drive may be contained in the latter. Since direct analytical comparison of the sizes of the two terms is, in general, difficult, a new approach is taken. Solution of the drift-kinetic equation shows that the standard Landau damping/transit time magnetic pumping quasilinear diffusion coefficient is the only contribution to steady-state current drive to leading order in ε=ρ L /l, where ρ L is the Larmor radius and l is the inhomogeneity scale length. All nonresonant contributions, including the helicity, appear at higher order, after averages are taken over a flux surface, over azimuth, and over time. Consequently, at wave frequencies well below the electron cyclotron frequency, a wave helicity flux perpendicular to the magnetic field does not influence the parallel motion of electrons to leading order and therefore will not drive a significant current. Any current associated with a wave helicity flux is then either ion current (and thus inefficient) or electron current stemming from effects not included in the drift-kinetic treatment, such as cyclotron, collisional, or nonlinear (i.e., not quasilinear)

  5. Electron cyclotron current drive efficiency in an axisymmetric tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Tapia, C.; Beltran-Plata, M. [Instituto Nacional de Investigaciones Nucleares, Dept. de Fisica, Mexico D.F. (Mexico)

    2004-07-01

    The neoclassical transport theory is applied to calculate electron cyclotron current drive (ECCD) efficiency in an axisymmetric tokamak in the low-collisionality regime. The tokamak ordering is used to obtain a system of equations that describe the dynamics of the plasma where the nonlinear ponderomotive (PM) force due to high-power radio-frequency (RF) waves is included. The PM force is produced around an electron cyclotron resonant surface at a specific poloidal location. The ECCD efficiency is analyzed in the cases of first and second harmonics (for different impinging angles of the RF waves) and it is validated using experimental parameter values from TCV and T-10 tokamaks. The results are in agreement with those obtained by means of Green's function techniques. (authors)

  6. Impact of electron trapping on RF current drive in tokamaks

    International Nuclear Information System (INIS)

    Giruzzi, G.; Engelmann, F.

    1987-01-01

    The impact of the presence of trapped electrons on noninductive current drive by RF waves in tokamak plasmas is investigated. The appropriate response function, allowing to express the current drive efficiency J/P by a simple analytical formula, has been derived. The approach displays the reasons for the degradation of the current drive efficiency away from the plasma axis in the case of methods relying on the diffusion of electrons in the velocity component perpendicular to the confining magnetic field. It is shown that this degradation is appreciable even for large resonant parallel velocities. (author) [pt

  7. Current drive by Alfven waves in elongated cross section tokamak

    International Nuclear Information System (INIS)

    Tsypin, V.S.; Elfimov, A.G.; Nekrasov, F.M.; Azevedo, C.A.; Assis, A.S. de

    1997-01-01

    Full text. The problem of the noninductive current drive in cylindrical plasma model and in circular cross-section tokamaks had been already discussed intensively. At the beginning of the study of this problem it have been clear that there are significant difficulties in using of the current-drive in toroidal magnetic traps, especially in a tokamak reactor. Thus, in the case of the lower-hybrid current-drive the efficiency of this current-drive drops strongly as the plasma density increases. For the Alfven waves, there is an opinion that the efficiency of the current-drive drops as a result of waves absorption by the trapped particles 1,2. Okhawa proposed that the current in a magnetized plasma can be maintained also by means of forces, depending on the radiofrequency (rf) field amplitude gradients (the helicity injection). This idea was developed later, some new hopes appeared, connected with the possibility of the current-drive efficiency increasing. It was shown that for the cylindrical plasmas the local efficiency of Alfev wave current drive can be increased by one order of magnitude due to gradient forces, for the kinetic Alfven waves (KAW) and the global Alfven waves 9GAW) at some range of the phase velocity. For tokamaks, this additional nonresonant current drive does not depend on the trapped particle effects, which reduce strongly the Alfven current drive efficiency in tokamaks, as it is supposed. Now, the theory development of the Alfven wave (AW) current drive is very important in the cource of the future experiments on the TCA/BR tokamak (Brazil). In this paper, an attempt is made to clarify some general aspects of this problems for magnetic traps. For large aspects ratio tokamaks, with an elongated cross-section, some general formulas concerning the untrapped and trapped particles dynamics and their input to the Landau damping of the Alfven waves, are presented. They are supposed to be used for the further development of the Alfven current drive theory

  8. Current drive by Alfven waves in elongated cross section tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Tsypin, V.S.; Elfimov, A.G.; Nekrasov, F.M.; Azevedo, C.A. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Assis, A.S. de [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica

    1997-12-31

    Full text. The problem of the noninductive current drive in cylindrical plasma model and in circular cross-section tokamaks had been already discussed intensively. At the beginning of the study of this problem it have been clear that there are significant difficulties in using of the current-drive in toroidal magnetic traps, especially in a tokamak reactor. Thus, in the case of the lower-hybrid current-drive the efficiency of this current-drive drops strongly as the plasma density increases. For the Alfven waves, there is an opinion that the efficiency of the current-drive drops as a result of waves absorption by the trapped particles 1,2. Okhawa proposed that the current in a magnetized plasma can be maintained also by means of forces, depending on the radiofrequency (rf) field amplitude gradients (the helicity injection). This idea was developed later, some new hopes appeared, connected with the possibility of the current-drive efficiency increasing. It was shown that for the cylindrical plasmas the local efficiency of Alfev wave current drive can be increased by one order of magnitude due to gradient forces, for the kinetic Alfven waves (KAW) and the global Alfven waves (GAW) at some range of the phase velocity. For tokamaks, this additional nonresonant current drive does not depend on the trapped particle effects, which reduce strongly the Alfven current drive efficiency in tokamaks, as it is supposed. Now, the theory development of the Alfven wave (AW) current drive is very important in the cource of the future experiments on the TCA/BR tokamak (Brazil). In this paper, an attempt is made to clarify some general aspects of this problems for magnetic traps. For large aspects ratio tokamaks, with an elongated cross-section, some general formulas concerning the untrapped and trapped particles dynamics and their input to the Landau damping of the Alfven waves, are presented. They are supposed to be used for the further development of the Alfven current drive theory

  9. Neoclassical effects on RF current drive in tokamaks

    International Nuclear Information System (INIS)

    Yoshioka, K.; Antonsen, T.M. Jr.

    1986-01-01

    Neoclassical effects on RF current drive which arise because of the inhomogeneity of the magnetic field in tokamak devices are analysed. A bounce averaged 2-D Fokker-Planck equation is derived from the drift kinetic equation and is solved numerically. The model features current drive due to a strong RF wave field. The efficiency of current drive by electron cyclotron waves is significantly reduced when the waves are absorbed at the low magnetic field side of a given flux surface, whereas the efficiency remains at the same level as in the homogeneous ideal plasma when the waves are absorbed at the high field side. The efficiency of current drive by fast waves (compressional Alfven waves) with low phase velocity (vsub(parallel)/vsub(th)<1) is significantly degraded by neoclassical effects, no matter where the wave is absorbed, and the applicability of this wave seems, therefore, to be doubtful. (author)

  10. Power quality issues current harmonics

    CERN Document Server

    Mikkili, Suresh

    2015-01-01

    Power Quality Issues: Current Harmonics provides solutions for the mitigation of power quality problems related to harmonics. Focusing on active power filters (APFs) due to their excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) AC power networks with nonlinear loads, the text:Introduces the APF technology, describing various APF configurations and offering guidelines for the selection of APFs for specific application considerationsCompares shunt active filter (SHAF) control strategi

  11. DC switching regulated power supply for driving an inductive load

    Science.gov (United States)

    Dyer, George R.

    1986-01-01

    A power supply for driving an inductive load current from a dc power supply hrough a regulator circuit including a bridge arrangement of diodes and switching transistors controlled by a servo controller which regulates switching in response to the load current to maintain a selected load current. First and second opposite legs of the bridge are formed by first and second parallel-connected transistor arrays, respectively, while the third and fourth legs of the bridge are formed by appropriately connected first and second parallel connected diode arrays, respectively. The regulator may be operated in three "stages" or modes: (1) For current runup in the load, both first and second transistor switch arrays are turned "on" and current is supplied to the load through both transistor arrays. (2) When load current reaches the desired level, the first switch is turned "off", and load current "flywheels" through the second switch array and the fourth leg diode array connecting the second switch array in series with the load. Current is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller. (3) Rapid current rundown is accomplished by turning both switch arrays "off", allowing load current to be dumped back into the source through the third and fourth diode arrays connecting the source in series opposition with the load to recover energy from the inductive load. The three operating states are controlled automatically by the controller.

  12. A thermodynamical analysis of rf current drive with fast electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bizarro, João P. S., E-mail: bizarro@ipfn.tecnico.ulisboa.pt [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2015-08-15

    The problem of rf current drive (CD) by pushing fast electrons with high-parallel-phase-velocity waves, such as lower-hybrid (LH) or electron-cyclotron (EC) waves, is revisited using the first and second laws, the former to retrieve the well-known one-dimensional (1D) steady-state CD efficiency, and the latter to calculate a lower bound for the rate of entropy production when approaching steady state. The laws of thermodynamics are written in a form that explicitly takes care of frictional dissipation and are thus applied to a population of fast electrons evolving under the influence of a dc electric field, rf waves, and collisions while in contact with a thermal, Maxwellian reservoir with a well-defined temperature. Besides the laws of macroscopic thermodynamics, there is recourse to basic elements of kinetic theory only, being assumed a residual dc electric field and a strong rf drive, capable of sustaining in the resonant region, where waves interact with electrons, a raised fast-electron tail distribution, which becomes an essentially flat plateau in the case of the 1D theory for LHCD. Within the 1D model, particularly suited for LHCD as it solely retains fast-electron dynamics in velocity space parallel to the ambient magnetic field, an H theorem for rf CD is also derived, which is written in different forms, and additional physics is recovered, such as the synergy between the dc and rf power sources, including the rf-induced hot conductivity, as well as the equation for electron-bulk heating. As much as possible 1D results are extended to 2D, to account for ECCD by also considering fast-electron velocity-space dynamics in the direction perpendicular to the magnetic field, which leads to a detailed discussion on how the definition of an rf-induced conductivity may depend on whether one works at constant rf current or power. Moreover, working out the collisional dissipated power and entropy-production rate written in terms of the fast-electron distribution, it

  13. Non-inductive current drive experiments on DIII-D, and future plans

    International Nuclear Information System (INIS)

    Prater, R.; Austin, M.; Baity, F.W.; Callis, R.W.; Chiu, S.C.; DeGrassie, J.S.; Freeman, R.L.; Forest, C.B.; Goulding, R.H.; Harvey, R.W.; Hoffman, D.J.; Ikezi, H.; Lohr, J.; James, R.A.; Kupfer, K.; Lin-Liu, Y.R.; Luce, T.C.; Moeller, C.P.; Petty, C.C.; Pinsker, R.I.; Porkolab, M.; Squire, J.; Trukhin, V.

    1995-01-01

    Experiments on DIII-D (and other tokamaks) have shown that improved performance can follow from optimization of the current density profile. Increased confinement of energy and a higher limit on β have both been found in discharges in which the current density profile is modified through transient means, such as ramping of current or elongation. Peaking of the current distribution to obtain discharges with high internal inductance l i has been found to be beneficial. Alternatively, discharges with broader profiles, as in the VH mode or with high β poloidal, have shown improved performance. Non-inductive current drive is a means to access these modes of improved confinement on a steady state basis. Accordingly, experiments on non-inductive current drive are underway on the DIII-D tokamak using fast waves and electron cyclotron waves. Recent experiments on fast wave current drive have demonstrated the ability to drive up to 180kA of non-inductive current using 1.5MW of power at 60MHz, including the contribution from 1MW of ECCD and the bootstrap current. Higher power r.f. current drive systems are needed to affect strongly the current profile on DIII-D. An upgrade to the fast wave current drive system is underway to increase the total power to 6MW, using two additional antennas and two new 30-120MHz transmitters. Additionally, a 1MW prototype ECH system at 110GHz is being developed (with eventual upgrade to 10MW). With these systems, non-inductive current drive at the 1MA level will be available for experiments on profile control in DIII-D. ((orig.))

  14. Fluctuation measurements by Langmuir probes during LHCD on ASDEX tokamak. [LHCD (Lower Hybrid Current Drive)

    Energy Technology Data Exchange (ETDEWEB)

    Stoeckel, J [Ceskoslovenska Akademie Ved, Prague (Czech Republic). Ustav Fyziky Plazmatu; Soeldner, F; Giannone, L.; Leuterer, F [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    1991-01-01

    The level of edge electrostatic fluctuations decreases and the global particle/energy confinement improves during lower hybrid current drive (LHCD) regimes on ASDEX, when the total power remains below the initial OH power level. For higher powers, the fluctuations increase noticeably, whereas the global confinement is returning to its OH value. The observed increase of fluctuations is poloidally asymmetric and is caused by local power deposition in front of the grill antenna. (author) 5 refs., 4 figs.

  15. Fokker-Planck modeling of current penetration during electron cyclotron current drive

    International Nuclear Information System (INIS)

    Merkulov, A.; Westerhof, E.; Schueller, F. C.

    2007-01-01

    The current penetration during electron cyclotron current drive (ECCD) on the resistive time scale is studied with a Fokker-Planck simulation, which includes a model for the magnetic diffusion that determines the parallel electric field evolution. The existence of the synergy between the inductive electric field and EC driven current complicates the process of the current penetration and invalidates the standard method of calculation in which Ohm's law is simply approximated by j-j cd =σE. Here it is proposed to obtain at every time step a self-consistent approximation to the plasma resistivity from the Fokker-Planck code, which is then used in a concurrent calculation of the magnetic diffusion equation in order to obtain the inductive electric field at the next time step. A series of Fokker-Planck calculations including a self-consistent evolution of the inductive electric field has been performed. Both the ECCD power and the electron density have been varied, thus varying the well known nonlinearity parameter for ECCD P rf [MW/m -3 ]/n e 2 [10 19 m -3 ] [R. W. Harvey et al., Phys. Rev. Lett 62, 426 (1989)]. This parameter turns out also to be a good predictor of the synergetic effects. The results are then compared with the standard method of calculations of the current penetration using a transport code. At low values of the Harvey parameter, the standard method is in quantitative agreement with Fokker-Planck calculations. However, at high values of the Harvey parameter, synergy between ECCD and E parallel is found. In the case of cocurrent drive, this synergy leads to the generation of large amounts of nonthermal electrons and a concomitant increase of the electrical conductivity and current penetration time. In the case of countercurrent drive, the ECCD efficiency is suppressed by the synergy with E parallel while only a small amount of nonthermal electrons is produced

  16. Combined kinetic and transport modeling of radiofrequency current drive

    International Nuclear Information System (INIS)

    Dumont, R.; Giruzzi, G.; Barbato, E.

    2000-07-01

    A numerical model for predictive simulations of radiofrequency current drive in magnetically confined plasmas is developed. It includes the minimum requirements for a self consistent description of such regimes, i.e., a 3-D ,kinetic equation for the electron distribution function, 1-D heat and current transport equations, and resonant coupling between velocity space and configuration space dynamics, through suitable wave propagation equations. The model finds its full application in predictive studies of complex current profile control scenarios in tokamaks, aiming at the establishment of internal transport barriers by the simultaneous use of various radiofrequency current drive methods. The basic properties of this non-linear numerical system are investigated and illustrated by simulations applied to reversed magnetic shear regimes obtained by Lower Hybrid and Electron Cyclotron current drive for parameters typical of the Tore Supra tokamak. (authors)

  17. On Power Stream in Motor or Drive System

    Directory of Open Access Journals (Sweden)

    Paszota Zygmunt

    2016-12-01

    Full Text Available In a motor or a drive system the quantity of power increases in the direction opposite to the direction of power flow. Energy losses and energy efficiency of a motor or drive system must be presented as functions of physical quantities independent of losses. Such quantities are speed and load. But the picture of power stream in a motor or drive system is presented in the literature in the form of traditional Sankey diagram of power decrease in the direction of power flow. The paper refers to Matthew H. Sankey’s diagram in his paper „The Thermal Efficiency of Steam Engines“ of 1898. Presented is also a diagram of power increase in the direction opposite to the direction of power flow. The diagram, replacing the Sankey’s diagram, opens a new prospect for research into power of energy losses and efficiency of motors and drive systems.

  18. Low-frequency current drive and helicity injection

    International Nuclear Information System (INIS)

    Chan, V.S.; Miller, R.L.; Ohkawa, T.

    1990-01-01

    For ω much-lt Ω i , where Ω i is the ion cyclotron frequency, circularly polarized waves can drive current far exceeding the current resulting from linearly polarized waves. Further, the efficiency can be independent of plasma density. In some cases, this circular polarization may be interpreted in terms of helicity injection. For tokamak applications, where the wavenumber in the toroidal direction is a real quantity, wave helicity is injected only with finite E z waves, where z is the direction of the static magnetic field. The Alfven waves are possible current drive candidates but, in the cylindrical model considered, the compressional wave is weakly damped because E z =0, while the shear Alfven wave is totally absorbed at the surface because of finite E z . A mixture of the two modes is shown to drive an oscillatory surface current even though the efficiency is high and independent of density. A more promising current drive candidate is a fast wave that propagates to the plasma interior and is damped by the minority cyclotron resonance. Near the minority mode conversion region, the fast wave is left-handed circularly polarized and it has a small but finite E z component at high electron temperatures. The current drive efficiency, although not as high as that of the Alfven wave, is still good and independent of density, making it attractive for fusion reactors

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

    Directory of Open Access Journals (Sweden)

    Wukitch S.J.

    2017-01-01

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

  20. 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.

  1. Neutral beam current drive scaling in DIII-D

    International Nuclear Information System (INIS)

    Porter, G.D.; Bhadra, D.K.; Burrell, K.H.

    1989-03-01

    Neutral beam current drive scaling experiments have been carried out on the DIII-D tokamak at General Atomics. These experiments were performed using up to 10 MW of 80 keV hydrogen beams. Previous current drive experiments on DIII-D have demonstrated beam driven currents up to 340 kA. In the experiments reported here we achieved beam driven currents of at least 500 kA, and have obtained operation with record values of poloidal beta (εβ/sub p/ = 1.4). The beam driven current reported here is obtained from the total plasma current by subtracting an estimate of the residual Ohmic current determined from the measured loop voltage. In this report we discuss the scaling of the current drive efficiency with plasma conditions. Using hydrogen neutral beams, we find the current drive efficiency is similar in Deuterium and Helium target plasmas. Experiments have been performed with plasma electron temperatures up to T/sub e/ = 3 keV, and densities in the range 2 /times/ 10 19 m/sup /minus/3/ 19 m/sup /minus/3/. The current drive efficiency (nIR/P) is observed to scale linearly with the energy confinement time on DIII-D to a maximum of 0.05 /times/ 10 20 m/sup /minus/2/ A/W. The measured efficiency is consistent with a 0-D theoretical model. In addition to comparison with this simple model, detailed analysis of several shots using the time dependent transport code ONETWO is discussed. This analysis indicates that bootstrap current contributes approximately 10--20% of the the total current. Our estimates of this effect are somewhat uncertain due to limited measurements of the radial profile of the density and temperatures. 4 refs., 1 fig., 1 tab

  2. Lower hybrid waves for current drive and heating in reactors

    International Nuclear Information System (INIS)

    Yugo, J.; Bernabei, S.; Bonoli, P.; Devoto, R.S.; Fenstermacher, M.; Porkolab, M.; Stevens, J.

    1988-01-01

    Lower hybrid (LH) waves are projected to be an important ingredient for current drive and heating in steady-state operation of reactors, such as the International Thermonuclear Experimental Reactor (ITER) or later power producing tokamaks. We have examined the required frequency and spectrum for such applications and designed a system to meet the specifications. We found that, to avoid damping of LH waves on alpha particles the frequency should be at least 6--8 GHz. At a typical volume average temperature of 14 keV, the LH rays penetrate about 30% of the minor radius, or to about 15 KeV, when N/sub parallel/ is chosen to maximize penetration and the spectral width, ΔN/sub parallel/ is about 0.05 (full width at 0.5 of spectral peak). For use in low density current ramp-up and transformer recharging, N/sub parallel/ is dynamically controlled. We have designed an LH system that satisfies requirements similar to those expected for ITER. It provides a Brambilla array which can be tuned from N/sub parallel/ of 1.0--2.8. An analysis has been performed to evaluate nuclear (1--2 MW/m 2 ), plasma radiation, and rf heating of the LH launcher. 4 refs., 3 figs., 4 tabs

  3. Stability, energetic particles, waves, and current drive summary

    International Nuclear Information System (INIS)

    Stambaugh, R.D.

    2005-01-01

    This is the summary paper for the subjects of plasma stability, energetic particles, waves, and current drive for the 20th IAEA Fusion Energy Conference, 1-6 November 2004, Vilamoura, Portugal. Material summarized herein was drawn from 65 contributed papers and 21 overview papers. The distribution of contributed papers by subjects is shown. Significant advances were reported on the principal instabilities in magnetically confined plasmas, even looking forward to the burning plasma state. Wave-plasma physics is maturing and novel methods of current drive and noninductive current generation are being developed. (author)

  4. Current drive experiments in the HIT-II spherical tokamak

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Gu, P.; Isso, V.A.; Jewell, P.E.; McCollam, K.J.; Nelson, B.A.; Ramon, R.; Redd, A.J.; Sieck, P.E.; Smith, R.J.; Nagata, M.; Uyama, T.

    2001-01-01

    The Helicity Injected Torus (Hit) program has made progress in understanding relaxation and helicity injection current drive. Helicity-conserving MHD activity during the inductive (Ohmic) current ramp demonstrates the profile flattening needed for coaxial helicity injection (CHI). Results from cathode and anode central column (CC) CHI pulses are consistent with the electron locking model of current drive from a pure n=1 mode. Finally, low density CHI, compatible with Ohmic operation, has been achieved. Some enhancement of CHI discharges with the application of Ohmic is shown. (author)

  5. Tearing modes in tokamaks with lower hybrid current drive

    International Nuclear Information System (INIS)

    Xu, X.Q.

    1990-08-01

    In this paper, the effect of current drive on the tearing modes in the semi-collisional regime is analyzed using the drift-kinetic equation. A collisional operator is developed to model electron parallel conductivity. For the pure tearing modes the linear and quasilinear growth rates in the Rutherford regimes have been found to have roughly the same forms with a modified resistivity as without current drive. One interesting result is the prediction of a new instability. This instability, driven by the current gradient inside the tearing mode layer, is possibly related to MHD behavior observed in these experiments. 9 refs

  6. Fast wave current drive in DIII-D

    International Nuclear Information System (INIS)

    Petty, C.C.; Callis, R.W.; Chiu, S.C.; deGrassie, J.S.; Forest, C.B.; Freeman, R.L.; Gohil, P.; Harvey, R.W.; Ikezi, H.; Lin-Liu, Y.-R.

    1995-02-01

    The non-inductive current drive from fast Alfven waves launched by a directional four-element antenna was measured in the DIII-D tokamak. The fast wave frequency (60 MHz) was eight times the deuterium cyclotron frequency at the plasma center. An array of rf pickup loops at several locations around the torus was used to verify the directivity of the four-element antenna. Complete non-inductive current drive was achieved using a combination of fast wave current drive (FWCD) and electron cyclotron current drive (ECCD) in discharges for which the total plasma current was inductively ramped down from 400 to 170 kA. For discharges with steady plasma current, up to 110 kA of FWCD was inferred from an analysis of the loop voltage, with a maximum non-inductive current (FWCD, ECCD, and bootstrap) of 195 out of 310 kA. The FWCD efficiency increased linearly with central electron temperature. For low current discharges, the FWCD efficiency was degraded due to incomplete fast wave damping. The experimental FWCD was found to agree with predictions from the CURRAY ray-tracing code only when a parasitic loss of 4% per pass was included in the modeling along with multiple pass damping

  7. Fast wave current drive in H mode plasmas on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Petty, C.C.; Grassie, J.S. de; Baity, F.W.

    1999-01-01

    Current driven by fast Alfven waves is measured in H mode and VH mode plasmas on the DIII-D tokamak for the first time. Analysis of the poloidal flux evolution shows that the fast wave current drive profile is centrally peaked but sometimes broader than theoretically expected. Although the measured current drive efficiency is in agreement with theory for plasmas with infrequent ELMs, the current drive efficiency is an order of magnitude too low for plasmas with rapid ELMs. Power modulation experiments show that the reduction in current drive with increasing ELM frequency is due to a reduction in the fraction of centrally absorbed fast wave power. The absorption and current drive are weakest when the electron density outside the plasma separatrix is raised above the fast wave cut-off density by the ELMs, possibly allowing an edge loss mechanism to dissipate the fast wave power since the cut-off density is a barrier for fast waves leaving the plasma. (author)

  8. A novel charge pump drive circuit for power MOSFETs

    International Nuclear Information System (INIS)

    Wang Songlin; Zhou Bo; Wang Hui; Guo Wangrui; Ye Qiang

    2010-01-01

    Novel improved power metal oxide semiconductor field effect transistor (MOSFET) drive circuits are introduced. An anti-deadlock block is used in the P-channel power MOSFET drive circuit to avoid deadlocks and improve the transient response. An additional charging path is added to the N-channel power MOSFET drive circuit to enhance its drive capability and improve the transient response. The entire circuit is designed in a 0.6 μm BCD process and simulated with Cadence Spectre. Compared with traditional power MOSFET drive circuits, the simulation results show that improved P-channel power MOSFET drive circuit makes the rise time reduced from 60 to 14 ns, the fall time reduced from 240 to 30 ns, and its power dissipation reduced from 2 to 1 mW, while the improved N-channel power MOSFET drive circuit makes the rise time reduced from 360 to 27 ns and its power dissipation reduced from 1.1 to 0.8 mW. (semiconductor integrated circuits)

  9. Electron-cyclotron resonance heating and current drive

    International Nuclear Information System (INIS)

    Filone, I.

    1992-01-01

    A brief summary of the theory and experiments on electron-cyclotron heating and current drive is presented. the general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D-III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (author) 8 fig. 13 ref

  10. Characterization of Input Current Interharmonics in Adjustable Speed Drives

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Zare, Firuz

    2017-01-01

    This paper investigates the interharmonic generation process in the input current of double-stage Adjustable Speed Drives (ASDs) based on voltage source inverters and front-end diode rectifiers. The effects of the inverter output-side low order harmonics, caused by implementing the double......-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....... The developed theoretical analysis predicts the drive interharmonic frequency locations with respect to the selected sampling strategies. Simulation and experimental results on a 2.5 kW ASD system verify the effectiveness of the theoretical analysis....

  11. Implications of ITER requirements on R and D of RF heating and current drive systems

    International Nuclear Information System (INIS)

    Bosia, G.; Agarici, G.; Beaumont, B.

    2003-01-01

    Heating and Current Drive (H and CD) systems have an essential role in ITER-FEAT operation, as all phases of ITER operation are driven and controlled by the auxiliary power flow. The RF (Electron Cyclotron and Ion Cyclotron) systems, planned to contribute for ∼ 60% of the total auxiliary power (72 MW), with Lower Hybrid used for the specialised function of current drive in the extended performance phase (20 MW), are at different level of technology development. All systems, need a significant development in order to meet ITER operation requirements In this paper these requirements are reviewed and CEA proposals for the development of the Ion cyclotron system presented. (author)

  12. Experimental demonstration of synergy between electron cyclotron and lower hybrid current drive on Tore Supra

    International Nuclear Information System (INIS)

    Artaud, J.F.; Giruzzi, G.; Dumont, R.J.; Imbeaux, F.; Bibet, P.; Bouquey, F.; Clary, J.; Ekedahl, A.; Hoang, G.T.; Lennholm, M.; Magne, R.; Segui, J.L.

    2004-01-01

    Non-inductive current drive (CD) has two main applications in tokamaks: sustainment of a substantial fraction of the toroidal plasma current necessary for the plasma confinement and control of the plasma stability and transport properties by appropriate shaping of the current density profile. For the first kind of applications, lower hybrid (LH) waves are known to provide the highest efficiency (defined as the ratio of the driven current to the injected wave power), although with limited control capability. Conversely, electron cyclotron (EC) waves drive highly localized currents, and are therefore particularly suited for control purposes, but their CD efficiency is much lower than that of LH waves (typically, an order of magnitude in present day experiments). Various calculations have demonstrated an interesting property: the current driven by the simultaneous use of the two waves, I(LH+EC), can be significantly larger than the sum I(LH)+I(EC) of the currents separately driven by the two waves in the same plasma conditions. This property, called synergy effect. The peculiar experimental conditions attainable on the Tore Supra tokamak have allowed the first experimental demonstration of the synergy between EC and LH current drive. The significant improvement of the electron cyclotron current drive (ECCD) efficiency in the presence of low hybrid current drive (LHCD), predicted by kinetic theory and confirmed by stationary experiments on Tore Supra, opens up the possibility of using ECCD as an efficient current profile control tool in LHCD plasmas

  13. ELECTRON CYCLOTRON CURRENT DRIVE EFFICIENCY IN GENERAL TOKAMAK GEOMETRY

    International Nuclear Information System (INIS)

    LIN-LUI, Y.R; CHAN, V.S; PRATER, R.

    2003-01-01

    Green's-function techniques are used to calculate electron cyclotron current drive (ECCD) efficiency in general tokamak geometry in the low-collisionality regime. Fully relativistic electron dynamics is employed in the theoretical formulation. The high-velocity collision model is used to model Coulomb collisions and a simplified quasi-linear rf diffusion operator describes wave-particle interactions. The approximate analytic solutions which are benchmarked with a widely used ECCD model, facilitate time-dependent simulations of tokamak operational scenarios using the non-inductive current drive of electron cyclotron waves

  14. FLC based adjustable speed drives for power quality enhancement

    Directory of Open Access Journals (Sweden)

    Sukumar Darly

    2010-01-01

    Full Text Available This study describes a new approach based on fuzzy algorithm to suppress the current harmonic contents in the output of an inverter. Inverter system using fuzzy controllers provide ride-through capability during voltage sags, reduces harmonics, improves power factor and high reliability, less electromagnetic interference noise, low common mode noise and extends output voltage range. A feasible test is implemented by building a model of three-phase impedance source inverter, which is designed and controlled on the basis of proposed considerations. It is verified from the practical point of view that these new approaches are more effective and acceptable to minimize the harmonic distortion and improves the quality of power. Due to the complex algorithm, their realization often calls for a compromise between cost and performance. The proposed optimizing strategies may be applied in variable-frequency dc-ac inverters, UPSs, and ac drives.

  15. ICRF heating and current drive experiments on TFTR

    International Nuclear Information System (INIS)

    Rogers, J.H.; Hosea, J.C.; Phillips, C.K.

    1996-01-01

    Recent experiments in the Ion Cyclotron Range of Frequencies (ICRF) at TFTR have focused on the RF physics relevant to advanced tokamak D-T reactors. Experiments performed either tested confinement in reactor relevant plasmas or tested specific ICRF heating scenarios under consideration for reactors. H-minority heating was used to supply identical heating sources for matched D-T and D only L-mode plasmas to determine the species scaling for energy confinement. Second harmonic tritium heating was performed with only thermal tritium ions in an L-mode target plasma, verifying a possible start-up scenario for the International Thermonuclear Experimental Reactor (ITER). Direct electron heating in Enhanced Reverse Shear (ERS) plasmas has been found to delay the back transition out of the ERS state. D-T mode conversion of the fast magnetosonic wave to an Ion Berstein Wave (IBW) for off-axis heating and current drive has been successfully demonstrated for the first time. Parasitic Li 7 cyclotron damping limited the fraction of the power going to the electrons to less than 30%. Similar parasitic damping by Be 9 could be problematic in ITER. Doppler shifted fundamental resonance heating of beam ions and alpha particles has also been observed

  16. On Ion Cyclotron Current Drive for sawtooth control

    International Nuclear Information System (INIS)

    Eriksson, L.-G.; Johnson, T.; Hellsten, T.; Mayoral, M.-L.; McDonald, D.; Santala, M.; Vries, P. de; Coda, S.; Sauter, O.; Mueck, A.; Buttery, R.J.; Mantsinen, M.J.; Noterdaeme, J.-M.; Westerhof, E.

    2006-01-01

    Experiments using Ion Cyclotron Current Drive (ICCD) to control sawteeth are presented. In particular, discharges demonstrating shortening of fast ion induced long sawteeth reported in [L.-G. Eriksson et al., Physical Review Letters 92, 235004 (2004)] by ICCD have been analysed in detail. Numerical simulations of the ICCD driven currents are shown to be consistent with the experimental observations. They support the hypothesis that an increase of the magnetic shear, due to the driven current, at the surface where the safety factor is unity was the critical factor for the shortening of the sawteeth. In view of the potential utility of ICCD, the mechanisms for the current drive have been further investigated experimentally. This includes the influence of the averaged energy of the resonating ions carrying the current and the spectrum of the launched waves. The results of these experiments are discussed in the light of theoretical considerations. (author)

  17. Numerical modeling of lower hybrid heating and current drive

    International Nuclear Information System (INIS)

    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

  18. Development of constant-power driving control for light-emitting-diode (LED) luminaire

    International Nuclear Information System (INIS)

    Huang, Bin-Juine; Chen, Chun-Wei; Ong, Chin-Dian; Du, Bo-Han; Hsu, Po-Chien

    2013-01-01

    The illumination of an LED may be affected by operating temperature even under constant-current condition. A constant-power driving technique is proposed in the present study for LED luminaire. A linear system dynamics model of LED luminaire is first derived and used in the design of the feedback control system. The PI controller was designed and tuned taking into account the control accuracy and robust properties with respect to plant uncertainty and variation of operating conditions. The control system was implemented on a microprocessor and used to control a 150W LED luminaire. The test result shows that the feedback system accurately controls the input power of LED luminaire to within 1.3 per cent error. As the ambient temperature changes from 0 to 40 °C, the LED illumination varies slightly (−1.7%) for constant-power driving, as compared to that of constant-current driving (−12%) and constant-voltage driving (+50%). The constant-power driving has revealed advantage in stabilizing the illumination of LED under large temperature variation. - Highlights: ► A constant-power driving technique is proposed for LED luminaire. ► A linear system dynamics model of LED luminaire is used in the control system design. ► The test shows that the feedback system accurately controls the input power. ► The LED illumination varies slightly (−1.7%) for constant-power driving.

  19. Modification of the Current Profile in DIII-D by Off-Axis Electron Cyclotron Current Drive

    International Nuclear Information System (INIS)

    Luce, T.C.; Lin-Liu, Y.R.; Harvey, R.W.; Giruzzi, G.; Lohr, J.M.; Petty, C.C.; Politzer, P.A.; Prater; Rice, B.W.

    1999-01-01

    Localized non-inductive currents due to electron cyclotron wave absorption have been measured on the DIII-D tokamak. Clear evidence of the non-inductive currents is seen on the internal magnetic field measurements by motional Stark effect spectroscopy. The magnitude and location of the non-inductive current is evaluated by comparing the total and Ohmic current profiles of discharges with and without electron cyclotron wave power. The measured current agrees with Fokker-Planck calculations near the magnetic axis, but exceeds the predicted value as the location of the current drive is moved to the half radius

  20. Optimization of a lower hybrid current drive launcher for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Belo, Jorge H.C.M., E-mail: jbelo@ipfn.ist.utl.pt [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Goniche, Marc; Hillairet, Julien [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Bizarro, João P.S. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2015-10-15

    Highlights: • Reflection, directivity and E-fields of LHCD PAM launchers for ITER investigated. • Wide range of antenna parameters (junction lengths; phase-shifter heights) regarded. • Broad range of edge plasma considered: from the cut-off density to ELM activity. • Trade-offs between plasma density, reflection coefficient and E-field are necessary. • Additional margins for integration of the launcher in ITER may be achieved. - Abstract: An international R&D program for lower-hybrid current drive (LHCD) in ITER is being conducted to deliver 20 MW (CW) using 500 kW klystrons at 5 GHz, with N{sub ||peak} = 2.0 ± 0.2 for different plasma scenarios. The launcher is based on the passive-active mulitjunction (PAM), a concept more resilient to conditions expected at the plasma edge, notably densities close to cut-off (n{sub ec}) and ELM activity, which lead to significant and abrupt reflection of RF power from the plasma, but even under which it may still attain extremely low power reflection coefficients at the input (R ∼ 1%). It has also a robust and shielded structure; is suitable for long-pulse operation; and has been validated experimentally on FTU and Tore Supra. Here the focus is on the PAM section of the launcher, and the objective is to explore, under broad plasma loading – from n{sub ec} to 10 n{sub ec} – the impact that design parameters such as the junction lengths, phase-shifter heights, and output waveguide widths have on its performance, particularly on R and on the E-fields inside its waveguides; and to explore also a configuration with a different phase-shifter arrangement, the so-called alternative design.

  1. Design and Research of Piezoelectric Ceramics Drive Power

    Directory of Open Access Journals (Sweden)

    Guang Ya LIU

    2014-01-01

    Full Text Available Piezoelectric amplifier is a very important part of the piezoelectric actuator. It does not only require high positioning accuracy, but also high frequency response. This paper designs the error amplifier drive power consisting of high-voltage op amp and discrete components, consisting of an error-amplified circuit, a power amplifier circuit, a feedback network and a discharge circuit. A compensation technique based on feedback zero compensation is proposed and it increases the frequency bandwidth and dynamic characteristics of the PZT power effectively. Through the power of the theoretical analysis and Multisim software simulation, the power supply has a good drive capability.

  2. Alternating-Current Motor Drive for Electric Vehicles

    Science.gov (United States)

    Krauthamer, S.; Rippel, W. E.

    1982-01-01

    New electric drive controls speed of a polyphase as motor by varying frequency of inverter output. Closed-loop current-sensing circuit automatically adjusts frequency of voltage-controlled oscillator that controls inverter frequency, to limit starting and accelerating surges. Efficient inverter and ac motor would give electric vehicles extra miles per battery charge.

  3. Current-drive by lower hybrid waves in the presence of energetic alpha-particles

    Energy Technology Data Exchange (ETDEWEB)

    Fisch, N.J.; Rax, J.M.

    1991-10-01

    Many experiments have now proved the effectiveness of lower hybrid waves for driving toroidal current in tokamaks. The use of these waves, however, to provide all the current in a reactor is thought to be uncertain because the waves may not penetrate the center of the more energetic reactor plasma, and, if they did, the wave power may be absorbed by alpha particles rather than by electrons. This paper explores the conditions under which lower-hybrid waves might actually drive all the current. 26 refs.

  4. Current status of nuclear power

    International Nuclear Information System (INIS)

    Behnke, W.B.

    1984-01-01

    The decision to devote the 1984 conference to nuclear power is timely and appropriate. Illinois has a long, and distinguished history in the development of civilian nuclear power. The concept was born at the University of Chicago, developed at Argonne National Laboratory and demonstrated on the Commonwealth Edison system at our pioneer Dresden Nuclear Station. Today, Illinois ranks number one in the nation in nuclear generation. With over a quarter century of commercial operating experience, nuclear power has proven its worth and become a significant and growing component of electric power supply domestically and throughout the world. Despite its initial acceptance, however, the nuclear power industry in the U.S. is now in the midst of a difficult period of readjustment stemming largely from the economic and regulatory problems of the past decade. As a result, the costs of plants under construction have increased dramatically, causing serious financial difficulties for several projects and their owners. At the same time, the U.S. is facing hard choices concerning its future energy supplies. Conferences such as this have an important role in clarifying the issues and helping to find solutions to today's pressing energy problems. This paper summarizes the status of nuclear power both here and abroad, discussing the implications of current events in the context of national energy policy and economic development here in Illinois

  5. Alfven-wave current drive and magnetic field stochasticity

    International Nuclear Information System (INIS)

    Litwin, C.; Hegna, C.C.

    1993-01-01

    Propagating Alfven waves can generate parallel current through an alpha effect. In resistive MHD however, the dynamo field is proportional to resistivity and as such cannot drive significant currents for realistic parameters. In the search for an enhancement of this effect the authors investigate the role of magnetic field stochasticity. They show that the presence of a stochastic magnetic field, either spontaneously generated by instabilities or induced externally, can enhance the alpha effect of the wave. This enhancement is caused by an increased wave dissipation due to both current diffusion and filamentation. For the range of parameters of current drive experiments at Phaedrus-T tokamak, a moderate field stochasticity leads to significant modifications in the loop voltage

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

    International Nuclear Information System (INIS)

    Wilson, J. R.; Bonoli, P.; Hubbard, A.; Parker, R.; Schmidt, A.; Wallace, G.; Wright, J.; Bernabei, S.

    2007-01-01

    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 parallel ∼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 n 20 IR/P∼0.3. Modeling using the CQL3D code supports these efficiencies. Sawtooth oscillations vanish, accompanied with peaking of the electron temperature (T e0 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)

  7. Burn stability of tokamak fusion plasmas with synergetic current drive

    International Nuclear Information System (INIS)

    Anderson, D.; Lisak, M.; Kolesnichenko, Ya.

    1991-01-01

    The stability of thermonuclear burn in Tokamak-reactors with non-inductive current generated with the simultaneous application of various methods is investigated. Particular emphasis is given to the ITER synergetic current drive scenario involving LH waves, neoclassical effects and NB injection. For ITER-like confinement laws, it is shown that this scenario may be unstable on the plasma skin time scale. Figs

  8. Power electronic converters PWM strategies and current control techniques

    CERN Document Server

    Monmasson, Eric

    2013-01-01

    A voltage converter changes the voltage of an electrical power source and is usually combined with other components to create a power supply. This title is devoted to the control of static converters, which deals with pulse-width modulation (PWM) techniques, and also discusses methods for current control. Various application cases are treated. The book is ideal for professionals in power engineering, power electronics, and electric drives industries, as well as practicing engineers, university professors, postdoctoral fellows, and graduate students.

  9. Multifunctional Converter Drive for Automotive Electric Power Steering Systems

    NARCIS (Netherlands)

    Hackner, T.J.

    2013-01-01

    In this thesis it is shown that in the case of an automotive electric power steering system, critical pulse power loads can be decoupled from the power net with a storage element and a multifunctional converter. A multifunctional converter system is proposed because it uses the motor drive system as

  10. 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.

  11. Power electronic converter systems for direct drive renewable energy applications

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    This chapter presents power electronic conversion systems for wind and marine energy generation applications, in particular, direct drive generator energy conversion systems. Various topologies are presented and system design optimization and reliability are briefly discussed....

  12. 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...

  13. Benchmarking of codes for electron cyclotron heating and electron cyclotron current drive under ITER conditions

    NARCIS (Netherlands)

    Prater, R.; Farina, D.; Gribov, Y.; Harvey, R. W.; Ram, A. K.; Lin-Liu, Y. R.; Poli, E.; Smirnov, A. P.; Volpe, F.; Westerhof, E.; Zvonkovo, A.

    2008-01-01

    Optimal design and use of electron cyclotron heating requires that accurate and relatively quick computer codes be available for prediction of wave coupling, propagation, damping and current drive at realistic levels of EC power. To this end, a number of codes have been developed in laboratories

  14. The analysis of Alfven wave current drive and plasma heating in TCABR tokamak

    International Nuclear Information System (INIS)

    Ruchko, L.F.; Lerche, E.A.; Galvao, R.M.O.; Elfimov, A.G.; Nascimento, I.C.; Sa, W.P. de; Sanada, E.; Elizondo, J.I.; Ferreira, A.A.; Saettone, E.A.; Severo, J.H.F.; Bellintani, V.; Usuriaga, O.N.

    2002-01-01

    The results of experiments on Alfven wave current drive and plasma heating in the TCABR tokamak are analyzed with the help of a numerical code for simulation of the diffusion of the toroidal electric field. It permits to find radial distributions of plasma current density and conductivity, which match the experimentally measured total plasma current and loop voltage changes, and thus to study the performance of the RF system during Alfven wave plasma heating and current drive experiments. Regimes with efficient RF power input in TCABR have been analyzed and revealed the possibility of noninductive current generation with magnitudes up to ∼8 kA. The increase of plasma energy content due to RF power input is consistent with the diamagnetic measurements. (author)

  15. Rig`s electricity to power top drive drilling system

    Energy Technology Data Exchange (ETDEWEB)

    Liderth, D.

    1996-05-01

    Permanent magnet brushless electric motors to supply torque to more space-efficient top drive drilling assemblies was the solution designed by Kaman Electromagnetic Corporation, working hand-in-hand with Calgary-based Tesco Drilling Technology, to remedy problems created by the bulkiness of standard hydraulic top drive systems. The biggest advantage of using electric over hydraulic top drive systems is the ability to tap into the rig`s existing power source, which lowers both cost and effort. A better power to weight ratio and reduced maintenance requirements are other desirable advantages.

  16. Requirements for alignment of electron cyclotron current drive for neoclassical tearing mode stabilization in ITER

    International Nuclear Information System (INIS)

    La Haye, R.J.; Ferron, J.R.; Humphreys, D.A.; Luce, T.C.; Petty, C.C.; Prater, R.; Strait, E.J.; Welander, A.S.

    2008-01-01

    ITER will rely on electron cyclotron stabilization of neoclassical tearing mode islands. The large size and low torque applied in ITER imply slow plasma rotation and susceptibility to island locking by the resistive wall; locking is likely to lead to a loss of the high confinement H-mode, a beta collapse and possibly disruption. 'Front' steering of the launcher, with narrower electron cyclotron current drive (ECCD), has resolved the issue in 'remote' steering of the driven current being too broad and relatively ineffective. However, narrower current drive places demands on alignment of the current drive on the rational surface that is being stabilized. DIII-D alignment techniques with and without (preemptive) an island are reviewed. The results are used to check models for the effect of misalignment and are then applied to ITER. Criteria for accuracy of alignment as a function of injected power and for the necessary time response of the controller are presented

  17. Current drive studies for the ARIES steady-state tokamak reactors

    International Nuclear Information System (INIS)

    Mau, T.K.; Ehst, D.A.; Mandrekas, J.

    1994-01-01

    Steady-state plasma operating scenarios are designed for three versions of the ARIES reactor, using non-inductive current drive techniques that have an established database. R.f. waves, including fast and lower hybrid waves, are the reference drivers for the D-T burning ARIES-I and ARIES-II/IV, while neutral beam injection is employed for ARIES-III which burns D- 3 He. Plasma equilibria with a high bootstrap-current component have been used, in order to minimize the recirculating power fraction and cost of electricity. To maintain plasma stability, the driven current profile has been aligned with that of equilibrium by proper choices of the plasma profiles and power launch parameters. Except for ARIES-III, the current-drive power requirements and the relevant technology developments are found to be quite reasonable. The wave-power spectrum and launch requirements are also considered achievable with a modest development effort. Issues such as an improved database for fast-wave current drive, lower-hybrid power coupling to the plasma edge, profile control in the plasma core, and access to the design point of operation remain to be addressed. ((orig.))

  18. Current ramp-up experiments in full current drive plasmas on TRIAM-1M

    International Nuclear Information System (INIS)

    Hanada, K.; Nakamura, K.; Hasegawa, M.

    2003-01-01

    Four types of plasma current ramp-up experiments were executed on TRIAM-1M in full lower hybrid current drive plasmas (LHCD: 8.2GHz, up to 0.4 MW, 8 x 2 grill antenna); 1) the current start up by the combination between electron cyclotron resonance heating (ECH: 170GHz, up to 0.2 MW, O-mode launching) and LHCD at the density of ∼2x10 19 m -3 at B t =6.7T, 2) the tail heating by the additional LHCD, 3) the bulk heating by ECH, 4) the spontaneous ramp up by the transition to enhanced current drive (ECD) mode. The time evolutions of plasma current during four types of ramp-up phase were investigated and an exponential type and a tangent-hyperbolic one were observed. The time evolutions of plasma current during the tail and the bulk heating show the exponential type except the tail heating with high n parallel and it has a tangent-hyperbolic one during the ECD mode and the current start-up. A simple model with two different time constants, which are a time defined by L/R, τ L/R , and a time caused by change of the effective refractive index along the magnetic field, τ, is proposed to explain two types of the time evolution of the plasma current. The estimated τ L/R is consistent with the calculated one from the plasma parameter. It is found that τ are less than τ L/R in the cases of the tail and the bulk heating, and comparable in the cases of the ECD mode, and more than τ L/R in the cases of the plasma start-up. This indicates that the value of the effective refractive index along the magnetic field, parallel >, develops during the ECD mode and the current start-up. The value of τ depends on the RF power. The estimated is close to the expected up-shifted n parallel due to the toroidal effect and the magnetic shear. (author)

  19. Direct calculation of current drive efficiency in FISIC code

    International Nuclear Information System (INIS)

    Wright, J.C.; Phillips, C.K.; Bonoli, P.T.

    1996-01-01

    Two-dimensional RF modeling codes use a parameterization (1) of current drive efficiencies to calculate fast wave driven currents. This parameterization assumes a uniform quasi-linear diffusion coefficient and requires a priori knowledge of the wave polarizations. These difficulties may be avoided by a direct calculation of the quasilinear diffusion coefficient from the Kennel-Englemann form with the field polarizations calculated by the full wave code, FISIC (2). Current profiles are calculated using the adjoint formulation (3). Comparisons between the two formulations are presented. copyright 1996 American Institute of Physics

  20. Control of the current density profile with lower hybrid current drive on PBX-M

    International Nuclear Information System (INIS)

    Bell, R.E.; Bernabei, S.; Chu, T.K.; Gettelfinger, G.; Greenough, N.; Hatcher, R.; Ignat, D.; Jardin, S.; Kaita, R.; Kaye, S.; Kozub, T.; Kugel, H.; LeBlanc, B.; Okabayashi, M.; Paul, S.; Sauthoff, N.; Sesnic, S.; Sun, Y.; Takahashi, H.; Tighe, W.; Valeo, E.; von Goeler, S.; Jones, S.; Kesner, J.; Luckhardt, S.; Paoletti, F.; Levinton, F.; Timini, F.

    1993-07-01

    Lower hybrid current drive (LHCD) is being explored as a means to control the current density profile on PBX-M with the goal of raising the central safety factor q(O) to values of 1.5-2 to facilitate access to a full-volume second stable regime. Initial experiments have been conducted with up to 400 kW of 4.6 GHz LH power in circular and indented plasmas with modest parameters. A tangential-viewing two-dimensional hard x-ray imaging diagnostic has been used to observe the bremsstrahlung emission from the suprathermal electrons generated during LHCD. Hollow hard x-ray images have indicated off-axis localization of the driven current. A serious obstacle to the control of the current density profile with LHCD is the concomitant generation of MHD activity, which can seriously degrade the confinement of suprathermal electrons. By combining neutral beam injection with LHCD, an MHD-free condition has been obtained where q(O) is raised above 1

  1. 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.

  2. Investigation of the LH wave energy conversion and current drive efficiency in the HT-7 tokamak

    International Nuclear Information System (INIS)

    Chen, Z.Y.; Wan, B.N.; Shi, Y.J.; Lin, S.Y.; Hu, L.Q.; Asif, M.

    2005-01-01

    Lower hybrid current drive (LHCD) plasmas in the presence of DC electric filed have been investigated based on Karney-Fisch theory in the HT-7 tokamak. The relatively small scatter in the experimental data with various values of waveguide phasing and lower hybrid power, when plotted in the Karney-Fisch diagram, confirms that a reasonable theoretical interpretation is possible for the HT-7 data. The full non-inductively current drive efficiencies are obtained by fitting the experimental data to the theoretical curve. The efficiency strongly depends on the lower hybrid wave phase velocity

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

    International Nuclear Information System (INIS)

    Start, D.F.H.; Baranov, Y.; Brusati, M.; Ekedahl, A.; Froissard, P.; Gormezano, C.; Jacquinot, J.; Paquin, L.; Rimini, F.G.; Di Vita, A.

    1994-01-01

    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

  4. Particle simulation of intense electron cyclotron heating and beat-wave current drive

    International Nuclear Information System (INIS)

    Cohen, B.I.

    1987-01-01

    High-power free-electron lasers make new methods possible for heating plasmas and driving current in toroidal plasmas with electromagnetic waves. We have undertaken particle simulation studies with one and two dimensional, relativistic particle simulation codes of intense pulsed electron cyclotron heating and beat-wave current drive. The particle simulation methods here are conventional: the algorithms are time-centered, second-order-accurate, explicit, leap-frog difference schemes. The use of conventional methods restricts the range of space and time scales to be relatively compact in the problems addressed. Nevertheless, experimentally relevant simulations have been performed. 10 refs., 2 figs

  5. Fast-wave current drive modelling for large non-circular tokamaks

    International Nuclear Information System (INIS)

    Batchelor, D.B.; Goldfinger, R.C.; Jaeger, E.F.; Carter, M.D.; Swain, D.W.; Ehst, D.; Karney, C.F.F.

    1990-01-01

    It is widely recognized that a key element in the development of an attractive tokamak reactor, and in the successful achievement of the mission of ITER, is the development of an efficient steady-state current drive technique. Fast waves in the ion cyclotron range of frequencies hold the promise to drive steady-state currents with the required efficiency and to effectively heat the plasma to ignition. Advantages over other heating and current drive techniques include low cost per watt and the ability to penetrate to the center of high-density plasmas. The primary issues that must be resolved are: can an antenna array be designed to radiate the required spectrum of waves and have adequate coupling properties? Will the rf power be efficiently absorbed by electrons in the desired velocity range without unacceptable parasitic damping by fuel ions or α particles? What will the efficiency of current drive be when toroidal effects such as trapped particles are included? Can a practical rf system be designed and integrated into the device? We have addressed these issues by performing extensive calculations with ORION, a 2-D code, and the ray tracing code RAYS, which calculate wave propagation, absorption and current drive in tokamak geometry, and with RIP, a 2-D code that self-consistently calculates current drive with MHD equilibrium. An important figure of merit in this context is the integrated, normalized current drive efficiency. The calculations that we present here emphasize the ITER device. We consider a low-frequency scenario such that no ion resonances appear in the machine, and a high-frequency scenario such that the deuterium second harmonic resonance is just outside the plasma and the tritium second harmonic is in the plasma, midway between the magnetic axis and the inside edge. In both cases electron currents are driven by combined TTMP and Landau damping of the fast waves

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

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Dal, Mehmet

    2008-01-01

    induction motor (IM) drives. The control design, based on synchronously rotating d-q frame model of the machine, has a simple structure that combines the proportional portion of a conventional PI control and output of the observer. The observer is predicted to estimate the disturbances caused by parameters...... 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...

  7. Fast wave current drive technology development at ORNL

    International Nuclear Information System (INIS)

    Baity, F.W.; Batchelor, D.B.; Goulding, R.H.; Hoffman, D.J.; Jaeger, E.F.; Ryan, P.M.; deGrassie, J.S.; Petty, C.C.; Pinsker, R.I.; Prater, R.

    1993-01-01

    The technology required for fast wave current drive (FWCD) systems is discussed. Experiments are underway on DIII-D, JET, and elsewhere. Antennas for FWCD draw heavily upon the experience gained in the design of ICRF heating systems with the additional requirement of launching a directional wave spectrum. Through collaborations with DIII-D, JET, and Tore Supra rapid progress is being made in the demonstration of the physics and technology of FWCD needed for TPX and ITER

  8. Fast wave current drive technology development at ORNL

    International Nuclear Information System (INIS)

    Baity, F.W.; Batchelor, D.B.; Goulding, R.H.

    1994-01-01

    The technology required for fast wave current drive (FWCD) systems is discussed. Experiments are underway on DIII-D, JET, and elsewhere. Antennas for FWCD draw heavily upon the experience gained in the design of ICRF heating systems with the additional requirement of launching a directional wave spectrum. Through collaborations with DIII-D, JET, and Tore Supra rapid progress is being made in the demonstration of the physics and technology of FWCD needed for TPX and ITER. (author)

  9. Current drive with fast waves, electron cyclotron waves, and neutral injection in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Prater, R.; Petty, C.C.; Pinsker, R.I.

    1993-01-01

    Current drive experiments have been performed on the DIII-D tokamak using fast waves, electron cyclotron waves, and neutral injection. Fast wave experiments were performed using a 4-strap antenna with 1 MW of power at 60 MHz. These experiments showed effective heating of electrons, with a global heating efficiency equivalent to that of neutral injection even when the single pass damping was calculated to be as small as 5%. The damping was probably due to the effect of multiple passes of the wave through the plasma. Fast wave current drive experiments were performed with a toroidally directional phasing of the antenna straps. Currents driven by fast wave current drive (FWCD) in the direction of the main plasma current of up to 100 kA were found, not including a calculated 40 kA of bootstrap current. Experiments with FWCD in the counter current direction showed little current drive. In both cases, changes in the sawtooth behavior and the internal inductance qualitatively support the measurement of FWCD. Experiments on electron cyclotron current drive have shown that 100 kA of current can be driven by 1 MW of power at 60 GHz. Calculations with a Fokker-Planck code show that electron cyclotron current drive (ECCD) can be well predicted when the effects of electron trapping and of the residual electric field are included. Experiments on driving current with neutral injection showed that effective current drive could be obtained and discharges with full current drive were demonstrated. Interestingly, all of these methods of current drive had about the same efficiency. (Author)

  10. Current drive with fast waves, electron cyclotron waves, and neutral injection in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Prater, R.; Petty, C.C.; Pinsker, R.I.; Chiu, S.C.; deGrassie, J.S.; Harvey, R.W.; Ikel, H.; Lin-Liu, Y.R.; Luce, T.C.; James, R.A.; Porkolab, M.; Baity, F.W.; Goulding, R.H.; Hoffmann, D.J.; Kawashima, H.; Trukhin, V.

    1992-09-01

    Current drive experiments have been performed on the DIII-D tokamak using fast waves, electron cyclotron waves, and neutral injection. Fast wave experiments were performed using a 4-strap antenna with 1 MW of power at 60 MHz. These experiments showed effective heating of electrons, with a global heating efficiency equivalent to that of neutral injection even when the single pass damping was calculated to be as small as 5%. The damping was probably due to the effect of multiple passes of the wave through the plasma. Fast wave current drive experiments were performed with a toroidally directional phasing of the antenna straps. Currents driven by fast wave current drive (FWCD) in the direction of the main plasma current of up to 100 kA were found, not including a calculated 40 kA of bootstrap current. Experiments with FWCD in the counter current direction showed little current drive. In both cases, changes in the sawtooth behavior and the internal inductance qualitatively support the measurement of FWCD. Experiments on electron cyclotron current drive have shown that 100 kA of current can be driven by 1 MW of power at 60 GHz. Calculations with a Fokker-Planck code show that electron cyclotron current drive (ECCD) can be well predicted when the effects of electron trapping and of the residual electric field are included. Experiments on driving current with neutral injection showed that effective current drive could be obtained and discharges with full current drive were demonstrated. Interestingly, all of these methods of current drive had about the same efficiency, 0.015 x 10 20 MA/MW/m 2

  11. Analysis on Θ pumping for tokamak current drive

    International Nuclear Information System (INIS)

    Miyamoto, Kenro; Naito, Osamu

    1986-01-01

    Analytical results of Θ pumping for the tokamak current drive are presented. Diffusion of externally applied oscillating electric field into the tokamak plasma is examined when the plasma is normal. When the oscillating electric field is parallel to the stationary toroidal plasma current and the induced current density by the applied electric field becomes larger than the average density of the toroidal plasma current over the plasma cross section, the radial profile of the safety factor has the extremum near the plasma boundary region and MHD instabilities are excited. It is assumed that anomalous diffusion of the induced current localized in the plasma boundary region takes place, so that the extreme value in the radial profile of the safety factor disappears. The anomalously diffused electric field due to this relaxation process has net d. c component and its non-zero value of the time average is estimated. Then the condition of the tokamak current drive by Θ pumping is derived. Some numerical results are presented for an example of a fusion grade plasma. (author)

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

    International Nuclear Information System (INIS)

    Litaudon, X.; Crisanti, F.; Alper, B.

    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)

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

    International Nuclear Information System (INIS)

    Litaudon, X.; Crisanti, F.; Alper, B.

    2002-01-01

    Quasi-steady operation has been achieved at JET in the high-confinement regime with internal transport barriers (ITBs). The ITB has been 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 1.0 MA) 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. (author)

  14. 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)

  15. Design and Construction of Variable Direct Current Speed Drive ...

    African Journals Online (AJOL)

    controlled rectifiers from the viewpoint of simplicity and cost effectiveness to act as power converter and controller. Design and construction of constituent circuits such as acceleration/deceleration, speed and current amplifier and the trigger ...

  16. Sawtooth control by on-axis electron cyclotron current drive on the WT-3 tokamak

    International Nuclear Information System (INIS)

    Asakawa, M.; Tanabe, K.; Nakayama, A.; Watanabe, M.; Nakamura, M.; Tanaka, H.; Maekawa, T.; Terumichi, Y.

    1999-01-01

    The experiments on control of sawtooth oscillations (STO) by electron cyclotron current drive (ECCD) have been performed on the WT-3 tokamak. Stabilization and excitation of STO are observed for counter-ECCD and co-ECCD, respectively, when the position of the power deposition is located inside the inversion radius. These results are due to the modification of the current profile near the magnetic axis. (author)

  17. Current-drive theory I: survey of methods

    International Nuclear Information System (INIS)

    Fisch, N.J.

    1986-01-01

    A variety of methods may be employed to drive toroidal electric current in a plasma torus. The most promising scheme is the injection of radiofrequency waves into the torus to push electrons or ions. The pushing mechanism can be either the direct conversion of wave to particle momentum, or a more subtle effect involving the alteration by waves of interparticle collisions. Alternatively, current can be produced through the injection of neutral beams, the reflection of plasma radiation, or the injection of frozen pellets. The efficacy of these schemes, in a variety of regimes, will be assessed. 9 refs

  18. Recent Improvements to the Control of the CTF3 High-Current Drive Beam

    CERN Document Server

    Constance, B; Gamba, D; Skowronski, P K

    2013-01-01

    In order to demonstrate the feasibility of the CLIC multiTeV linear collider option, the drive beam complex at the CLIC Test Facility (CTF3) at CERN is providing highcurrent electron pulses for a number of related experiments. By means of a system of electron pulse compression and bunch frequency multiplication, a fully loaded, 120 MeV linac is used to generate 140 ns electron pulses of around 28 Amperes. Subsequent deceleration of this high-current drive beam demonstrates principles behind the CLIC acceleration scheme, and produces 12 GHz RF power for experimental purposes. As the facility has progressed toward routine operation, a number of studies aimed at improving the drive beam performance have been carried out. Additional feedbacks, automated steering programs, and improved control of optics and dispersion have contributed to a more stable, reproducible drive beam with consequent benefits for the experiments.

  19. HEATING AND CURRENT DRIVE BY ELECTRON CYCLOTRON WAVES

    International Nuclear Information System (INIS)

    Prater, R.

    2003-01-01

    OAK-B135 The physics model of electron cyclotron heating (ECH) and current drive (ECCD) is becoming well validated through systematic comparisons of theory and experiment. This work has shown that ECH and ECCD can be highly localized and robustly controlled in toroidal plasma confinement systems, leading to applications including stabilization of magnetohydrodynamic (MHD) instabilities like neoclassical tearing modes, control and sustainment of desired profiles of current density and plasma pressure, and studies of localized transport in laboratory plasmas. The experimental work was supported by a broad base of theory based on first principles which is now well encapsulated in linear ray tracing codes describing wave propagation, absorption, and current drive and in fully relativistic quasilinear Fokker-Planck codes describing in detail the response of the electrons to the energy transferred from the wave. 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. 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. The agreement of theory and experiment, the wide range of established applications, and the technical advantages of ECH support the application of ECH in next-step tokamaks and stellarators

  20. Indirect drive targets for fusion power

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, Peter A.; Miles, Robin R.

    2016-10-11

    A hohlraum for an inertial confinement fusion power plant is disclosed. The hohlraum includes a generally cylindrical exterior surface, and an interior rugby ball-shaped surface. Windows over laser entrance holes at each end of the hohlraum enclose inert gas. Infrared reflectors on opposite sides of the central point reflect fusion chamber heat away from the capsule. P2 shields disposed on the infrared reflectors help assure an enhanced and more uniform x-ray bath for the fusion fuel capsule.

  1. Direct Fuel Injector Power Drive System Optimization

    Science.gov (United States)

    2014-04-01

    solenoid coil to create magnetic field in the stator. Then, the stator pulls the pintle to open the injector nozzle . This pintle movement occurs when the...that typically deal with power strategies to the injector solenoid coil. Numerical simulation codes for diesel injection systems were developed by...Laboratory) for providing the JP-8 test fuel. REFERENCES 1. Digesu, P. and Laforgia D., “ Diesel electro- injector : A numerical simulation code”. Journal of

  2. Simple multijunction launcher with oversized waveguides for lower hybrid current drive on JT-60U

    International Nuclear Information System (INIS)

    Ikeda, Y.; Naito, O.; Seki, M.; Kondoh, T.; Ide, S.; Anno, K.; Fukuda, H.; Ikeda, Y.; Kitai, T.; Kiyono, K.; Sawahata, M.; Shinozaki, S.; Suganuma, K.; Suzuki, N.; Ushigusa, K.

    1994-01-01

    A multijunction technique with oversized waveguides has been developed for the lower hybrid current drive launcher on JT-60U. The launcher consists of 4 (toroidal)x4 (poloidal) multijunction modules. RF power in the module is divided toroidally into 12 sub-waveguides at a junction point through an oversized waveguide. This method simplifies the structure of the multijunction launcher with a large number of subwaveguides. A maximum power density up to 25 MW m -2 has been achieved with a low reflection coefficient of less than 2%. The coupling and current drive efficiency are well explained by the designed wave spectra without taking account of higher modes in the oversize waveguides. Thus, the simple multijunction launcher has been demonstrated to excite expected wave spectra with high power handling capability. ((orig.))

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

    International Nuclear Information System (INIS)

    De Lazzari, D.; Westerhof, E.

    2009-01-01

    Neoclassical tearing modes (NTMs) are magnetohydrodynamic modes that can limit the performance of high β 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 flattening across a magnetic island. Control and suppression of this mode can be achieved by means of electron cyclotron waves (ECWs) which allow the deposition of highly localized power at the island location. The ECW power replenishes the missing bootstrap current by generating a current perturbation either inductively, through a temperature perturbation (electron cyclotron resonance heating), or non-inductively by direct current drive (electron cyclotron current drive). Although both methods have been applied successfully to experiments showing a predominance of ECRH for medium-sized limiter tokamaks (TEXTOR, T-10) and of ECCD for mid-to-large-sized divertor tokamaks (AUG, DIII-D, JT-60), conditions determining their relative importance are still unclear. We address this problem with a numerical study focused on the contributions of heating and current drive to the temporal evolution of NTMs as described by the modified Rutherford equation. For the effects of both heating as well as current drive, simple analytical expressions have been found in terms of an efficiency fore-factor times a 'geometrical' term depending on the power deposition width w dep , location and modulation. When the magnetic island width w equals the width of the deposition profile, w ∼ w dep , both geometric terms are practically identical. Whereas for current drive the geometric term approaches a constant for small island widths and is inversely proportional to (w/w dep ) 2 for large island widths, the heating term approaches a constant for large island widths and is proportional to (w/w dep ) for small island widths. For medium-sized tokamaks (TEXTOR, AUG) the heating and current drive efficiencies are of the

  4. Power Electronic Transformer based Three-Phase PWM AC Drives

    Science.gov (United States)

    Basu, Kaushik

    A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common

  5. Simple model to explain the temperature dependence of the lower hybrid current drive efficiency

    International Nuclear Information System (INIS)

    Ushigusa, K.

    1996-01-01

    Dissipated power in the spectral gap is taken into account in deriving analytically the lower hybrid current drive efficiency. The efficiency is determined by a minimum down-shifted phase velocity υ L and the quasi-linear velocity diffusion coefficient at the spectral gap D' W in addition to the original wave spectrum. To explain present experimental results in both JT-60 and ASDEX, υ L must be close to the Landau damping limit (υ L ∼ 2.7υ te ) and D' W must be the same order of magnitude as the collisional friction at υ L . With the suggested values of these two parameters from experimental results, the driven current is mainly determined by the launched wave spectrum, while most of the wave power is dissipated at the spectral gap. This characteristic can explain both the temperature and the N || dependence of the current drive efficiency. (author)

  6. Modeling of finite aspect ratio effects on current drive

    International Nuclear Information System (INIS)

    Wright, J.C.; Phillips, C.K.

    1996-01-01

    Most 2D RF modeling codes use a parameterization of current drive efficiencies to calculate fast wave driven currents. This parameterization assumes a uniform diffusion coefficient and requires a priori knowledge of the wave polarizations. These difficulties may be avoided by a direct calculation of the quasilinear diffusion coefficient from the Kennel-Englemann form with the field polarizations calculated by a full wave code. This eliminates the need to use the approximation inherent in the parameterization. Current profiles are then calculated using the adjoint formulation. This approach has been implemented in the FISIC code. The accuracy of the parameterization of the current drive efficiency, η, is judged by a comparison with a direct calculation: where χ is the adjoint function, ε is the kinetic energy, and rvec Γ is the quasilinear flux. It is shown that for large aspect ratio devices (ε → 0), the parameterization is nearly identical to the direct calculation. As the aspect ratio approaches unity, visible differences between the two calculations appear

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

    International Nuclear Information System (INIS)

    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

  8. Fivefold confinement time increase in the Madison Symmetric Torus using inductive poloidal current drive

    International Nuclear Information System (INIS)

    Stoneking, M.R.; Lanier, N.E.; Prager, S.C.; Sarff, J.S.; Sinitsyn, D.

    1997-01-01

    Current profile control is employed in the Madison Symmetric Torus [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)] reversed field pinch to reduce the magnetic fluctuations responsible for anomalous transport. An inductive poloidal electric-field pulse is applied in the sense to flatten the parallel current profile, reducing the dynamo fluctuation amplitude required to sustain the equilibrium. This technique demonstrates a substantial reduction in fluctuation amplitude (as much as 50%), and improvement in energy confinement (from 1 to 5 ms); a record low fluctuation (0.8%) and record high temperature (615 eV) for this device were observed simultaneously during current drive experiments. Plasma beta increases by 50% and the Ohmic input power is three times lower. Particle confinement improves and plasma impurity contamination is reduced. The results of the transient current drive experiments provide motivation for continuing development of steady-state current profile control strategies for the reversed field pinch. copyright 1997 American Institute of Physics

  9. Theory of free-electron-laser heating and current drive in magnetized plasmas

    International Nuclear Information System (INIS)

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

    1991-01-01

    The introduction of a powerful new microwave source, the free-electron laser, provides new opportunities for novel heating and current-drive schemes to be used in toroidal fusion devices. This high-power, pulsed source has a number of technical advantages for these applications, and its use is predicted to lead to improved current-drive efficiencies and opacities in reactor-grade fusion plasmas in specific cases. The Microwave Tokamak Experiment at the Lawrence Livermore National Laboratory will provide a test for some of these new heating and current-drive schemes. Although the motivation for much of this research has derived from the application of a free-electron laser to the heating of a tokamak plasma at a frequency near the electron cyclotron frequency, the underlying physics, i.e., the highly nonlinear interaction of an intense, pulsed, coherent electromagnetic wave with an electron in a magnetized plasma including relativistic effects, is of general interest. Other relevant applications include ionospheric modification by radio-frequency waves, high-energy electron accelerators, and the propagation of intense, pulsed electromagnetic waves in space and astrophysical plasmas. This review reports recent theoretical progress in the analysis and computer simulation of the absorption and current drive produced by intense pulses, and of the possible complications that may arise, e.g., parametric instabilities, nonlinear self-focusing, trapped-particle sideband instability, and instabilities of the heated plasma

  10. Fast and efficient wireless power transfer via transitionless quantum driving.

    Science.gov (United States)

    Paul, Koushik; Sarma, Amarendra K

    2018-03-07

    Shortcut to adiabaticity (STA) techniques have the potential to drive a system beyond the adiabatic limits. Here, we present a robust and efficient method for wireless power transfer (WPT) between two coils based on the so-called transitionless quantum driving (TQD) algorithm. We show that it is possible to transfer power between the coils significantly fast compared to its adiabatic counterpart. The scheme is fairly robust against the variations in the coupling strength and the coupling distance between the coils. Also, the scheme is found to be reasonably immune to intrinsic losses in the coils.

  11. Fast wave current drive experiment on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Petty, C.C.; Pinsker, R.I.; Chiu, S.C.; deGrassie, J.S.; Harvey, R.W.; Lohr, J.; Luce, T.C.; Mayberry, M.J.; Prater, R.; Porkolab, M.; Baity, F.W.; Goulding, R.H.; Hoffman, J.D.; James, R.A.; Kawashima, H.

    1992-06-01

    One method of radio-frequency heating which shows theoretical promise for both heating and current drive in tokamak plasmas is the direct absorption by electrons of the fast Alfven wave (FW). Electrons can directly absorb fast waves via electron Landau damping and transit-time magnetic pumping when the resonance condition ω - κ parallele υ parallele = O is satisfied. Since the FW accelerates electrons traveling the same toroidal direction as the wave, plasma current can be generated non-inductively by launching FW which propagate in one toroidal direction. Fast wave current drive (FWCD) is considered an attractive means of sustaining the plasma current in reactor-grade tokamaks due to teh potentially high current drive efficiency achievable and excellent penetration of the wave power to the high temperature plasma core. Ongoing experiments on the DIII-D tokamak are aimed at a demonstration of FWCD in the ion cyclotron range of frequencies (ICRF). Using frequencies in the ICRF avoids the possibility of mode conversion between the fast and slow wave branches which characterized early tokamak FWCD experiments in the lower hybrid range of frequencies. Previously on DIII-D, efficient direct electron heating by FW was found using symmetric (non-current drive) antenna phasing. However, high FWCD efficiencies are not expected due to the relatively low electron temperatures (compared to a reactor) in DIII-D

  12. Current drive by spheromak injection into a tokamak

    International Nuclear Information System (INIS)

    Brown, M.R.; Bellan, P.M.

    1990-01-01

    The authors report the first observation of current drive by spheromak injection into a tokamak due to the process of helicity injection. Current drive is observed in Caltech's ENCORE tokamak (30% increase, ΔI > 1 kA) only when both the tokamak and injected spheromak have the same sign of helicity (where helicity is defined as positive if current flows parallel to magnetic field lines and negative if anti-parallel). The initial increase (decrease) in current is accompanied by a sharp decrease (increase) in loop voltage and the increase in tokamak helicity is consistent with the helicity content of the injected spheromak. In addition, the injection of the spheromak raises the tokamak central density by a factor of six. The introduction of cold spheromak plasma causes sudden cooling of the tokamak discharge from 12 eV to 4 eV which results in a gradual decline in tokamak plasma current by a factor of three. In a second experiment, the authors inject spheromaks into the magnetized toroidal vacuum vessel (with no tokamak plasma). An m = 1 magnetic structure forms in the vessel after the spheromak undergoes a double tilt; once in the cylindrical entrance between gun and tokamak, then again in the tokamak vessel. A horizontal shift of the spheromak equilibrium is observed in the direction opposite that of the static toroidal field. In the absence of net toroidal flux, the structure develops a helical pitch as predicted by theory. Experiments with a number of refractory metal coatings have shown that tungsten and chrome coatings provide some improvement in spheromak parameters. They have also designed and will soon construct a larger, higher current spheromak gun with a new accelerator section for injection experiments on the Phaedrus-T tokamak

  13. Lower hybrid current drive in the presence of electric field

    Directory of Open Access Journals (Sweden)

    Saveliev Alexander

    2017-01-01

    Full Text Available A new one-dimensional approach to the lower hybrid current drive (LHCD modelling in the presence of an inductive electric field is suggested in this paper. The approach is based on using time-dependent solutions of a well-known Fokker-Planck equation for the distribution function of fast electrons calculated concurrently with solving plasma transport equation in the Automated System for TRansport Analysis (ASTRA [1]. A good agreement between experimental and modelling results is demonstrated for an FT-2 [2] plasma shot. Also new formulae for the steady-state solution of this kinetic equation are found.

  14. Lower hybrid current drive in the presence of electric field

    Science.gov (United States)

    Saveliev, Alexander; Zakharov, Vladimir

    2017-10-01

    A new one-dimensional approach to the lower hybrid current drive (LHCD) modelling in the presence of an inductive electric field is suggested in this paper. The approach is based on using time-dependent solutions of a well-known Fokker-Planck equation for the distribution function of fast electrons calculated concurrently with solving plasma transport equation in the Automated System for TRansport Analysis (ASTRA) [1]. A good agreement between experimental and modelling results is demonstrated for an FT-2 [2] plasma shot. Also new formulae for the steady-state solution of this kinetic equation are found.

  15. 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.

  16. Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit

    OpenAIRE

    Cappuccio, Joseph C., Jr.

    1988-01-01

    Approved for public release; distribution is unlimited This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse m...

  17. The Bootstrap Current and Neutral Beam Current Drive in DIII-D

    International Nuclear Information System (INIS)

    Politzer, P.A.

    2005-01-01

    Noninductive current drive is an essential part of the implementation of the DIII-D Advanced Tokamak program. For an efficient steady-state tokamak reactor, the plasma must provide close to 100% bootstrap fraction (f bs ). For noninductive operation of DIII-D, current drive by injection of energetic neutral beams [neutral beam current drive (NBCD)] is also important. DIII-D experiments have reached ∼80% bootstrap current in stationary discharges without inductive current drive. The remaining current is ∼20% NBCD. This is achieved at β N [approximately equal to] β p > 3, but at relatively high q 95 (∼10). In lower q 95 Advanced Tokamak plasmas, f bs ∼ 0.6 has been reached in essentially noninductive plasmas. The phenomenology of high β p and β N plasmas without current control is being studied. These plasmas display a relaxation oscillation involving repetitive formation and collapse of an internal transport barrier. The frequency and severity of these events increase with increasing β, limiting the achievable average β and causing modulation of the total current as well as the pressure. Modeling of both bootstrap and NBCD currents is based on neoclassical theory. Measurements of the total bootstrap and NBCD current agree with calculations. A recent experiment based on the evolution of the transient voltage profile after an L-H transition shows that the more recent bootstrap current models accurately describe the plasma behavior. The profiles and the parametric dependences of the local neutral beam-driven current density have not yet been compared with theory

  18. FED-A, an advanced performance FED based on low safety factor and current drive

    International Nuclear Information System (INIS)

    Peng, Y.K.M.; Rutherford, P.H.

    1983-08-01

    The FED-A study aims to quantify the potential improvement in cost-effectiveness of the Fusion Engineering Device (FED) by assuming low safety factor q (less than 2 as opposed to about 3) at the plasma edge and noninductive current drive (as opposed to only inductive current drive). The FED-A performance objectives are set to be : (1) ignition assuming International Tokamak Reactor (INTOR) plamsa confinement scaling, but still achieving a fusion power amplification Q greater than or equal to 5 when the confinement is degraded by a factor of 2; (2) neutron wall loading of about 1 MW/m 2 , with 0.5 MW/m 2 as a conservative lower bound; and (3) more clearly power-reactor-like operations, such as steady state

  19. A Lower Hybrid Current Drive System for Alcator C-Mod

    International Nuclear Information System (INIS)

    Bernabei, S.; Hosea, J.C.; Loesser, D.; Rushinski, J.; Wilson, J.R.; Bonoli, P.; Grimes, M.; Parker, R.; Porkolab, M.; Terry, D.; Woskov, P.

    2001-01-01

    A Lower Hybrid Current Drive system is being constructed jointly by Plasma Science and Fusion Center (PSFC) and Princeton Plasma Physics Laboratory (PPPL) for installation on the Alcator C-Mod tokamak, with the primary goal of driving plasma current in the outer region of the plasma. The Lower Hybrid (LH) system consists of 3 MW power at 4.6 GHz with a maximum pulse length of 5 seconds. Twelve klystrons will feed an array of 4-vertical and 24-horizontal waveguides mounted in one equatorial port. The coupler will incorporate some compact characteristics of the multijunction power splitting while retaining full control of the toroidal phase. In addition a dynamic phase control system will allow feedback stabilization of MHD modes. The desire to avoid possible waveguide breakdown and the need for compactness have resulted in some innovative technical solution which will be presented

  20. Drive Current Enhancement in TFET by Dual Source Region

    Directory of Open Access Journals (Sweden)

    Zhi Jiang

    2015-01-01

    Full Text Available This paper presents tunneling field-effect transistor (TFET with dual source regions. It explores the physics of drive current enhancement. The novel approach of dual source provides an effective technique for enhancing the drive current. It is found that this structure can offer four tunneling junctions by increasing a source region. Meanwhile, the dual source structure does not influence the excellent features of threshold slope (SS of TFET. The number of the electrons and holes would be doubled by going through the tunneling junctions on the original basis. The overlap length of gate-source is also studied. The dependence of gate-drain capacitance Cgd and gate-source capacitance Cgs on gate-to-source voltage Vgs and drain-to-source voltage Vds was further investigated. There are simulation setups and methodology used for the dual source TFET (DS-TFET assessment, including delay time, total energy per operation, and energy-delay product. It is confirmed that the proposed TFET has strong potentials for VLSI.

  1. Technology of fast-wave current drive antennas

    International Nuclear Information System (INIS)

    Hoffman, D.J.; Baity, F.W.; Goulding, R.H.; Haste, G.R.; Ryan, P.M.; Taylor, D.J.; Swain, D.W.; Mayberry, M.J.; Yugo, J.J.

    1989-01-01

    The design of fast-wave current drive (FWCD) antennas combines the usual antenna considerations (e.g., the plasma/antenna interface, disruptions, high currents and voltages, and thermal loads) with new requirements for spectral shaping and phase control. The internal configuration of the antenna array has a profound effect on the spectrum and the ability to control phasing. This paper elaborates on these considerations, as epitomized by a proof-of-principle (POP) experiment designed for the DIII-D tokamak. The extension of FWCD for machines such as the International Thermonuclear Engineering Reactor (ITER) will require combining ideas implemented in the POP experiment with reactor-relevant antenna concepts, such as the folded waveguide. 6 refs., 8 figs

  2. Review of lower hybrid wave heating and current drive

    International Nuclear Information System (INIS)

    Gormezano, C.

    1986-01-01

    Interaction of Lower Hybrid waves and plasmas is a very versatile method which has proven to be effective in a large range of applications: bulk ion heating, bulk electron heating, non inductive current drive. If the ratio between the mean velocity of HF induced fast particles and the thermal velocity of the bulk population is relatively small, effective bulk ion heating or bulk electron heating can occur via collisional transfer. If the above ratio is too large, fast ions, which have mainly a perpendicular energy, are poorly confined. Moreover they can be harmful for the discharge (impurities, etc...) since they are lost on the walls. In contrast, HF induced fast electrons gain essentially a parallel momentum from the wave. If unidirectional waves are launched, the dissymetry in electron distribution result in the obtention of an effective non inductive current

  3. Current ramp-up experiments in full current drive plasmas in TRIAM-1M

    International Nuclear Information System (INIS)

    Hanada, K.; Nakamura, K.; Hasegawa, M.; Itoh, S.; Zushi, H.; Sakamoto, M.; Jotaki, E.; Iyomasa, A.; Kawasaki, S.; Nakashima, H.; Yoshida, N.; Tokunaga, K.; Fujiwara, T.; Kulkarni, S.V.; Mitarai, O.

    2004-01-01

    Four types of plasma current ramp-up experiments in full non-inductively lower hybrid current driven (LHCD) plasmas were executed in TRIAM-1M: (1) current start-up by a combination of electron cyclotron resonance heating (ECRH) and LHCD, (2) tail heating by additional LHCD, (3) bulk heating by ECRH and (4) spontaneous ramp-up by a transition to enhanced current drive (ECD) mode. The time evolutions of plasma current during four types of ramp-up phase were adjusted by a simple model with two different time constants, which are a time defined by the total current diffusion time and a time constant for improving the current drive efficiency. In the case of (1) and (4), the latter time constant is significant during the current ramp-up phase. The improvement in the current drive efficiency in the ECD mode is likely to be caused by the increase in the effective refractive index along the magnetic field of the lower hybrid wave. (author)

  4. Electric machinery and drives in thermal power stations

    International Nuclear Information System (INIS)

    1974-01-01

    The following subjects were dealt with during the VDE meeting: 1) Requirements made by the electric network on the generators and their excitation equipment, and the influence thereof on their design; 2) requirements made by the power station process on the electric drives and the influence thereof on type and design; 3) requirements made on protective measures from the point of the electric power station machinery. (TK) [de

  5. HIL Simulation of Power Electronics and Electric Drives for Automotive Applications

    Directory of Open Access Journals (Sweden)

    Frank Puschmann

    2012-12-01

    Full Text Available Hardware-in-the-loop simulation is today a standard method for testing electronic equipment in the automotive industry. Since electric drives and power electronic devices are more and more important in automotive applications, these kinds of systems have to be integrated into the hardware-in-the-loop simulation. Power converters and electric drives are used in many different applications in vehicles today (hybrid electric or electric powertrain, electric steering systems, DC-DC converters, etc.. The wide range of applications, topologies, and power levels results in various different approaches and solutions for hardware-in-the-loop testing. This paper gives an overview of hardware-in-the-loop simulation of power electronics and electric drives in the automotive industry. The currently available technologies are described and future challenges are outlined.

  6. Recent results on electron cyclotron current drive and MHD activity in RTP

    NARCIS (Netherlands)

    Donne, A.J.H.; Schuller, F.C.; Oomens, A.A.M.; de Baar, M.R.; Barth, C.J.; Beurskens, M.N.A.; Box, F.M.A.; van Gelder, J.F.M.; Grobben, B.J.J.; Groot, de B.; Herranz, J.M.; Hogeweij, G.M.D.; Hokin, S.A.; Howard, J.; Hugenholtz, C.A.J.; Karelse, F.A.; de Kloe, J.; Kruijt, O.G.; Kuyvenhoven, S.; Lok, J.; Cardozo, N.J.L.; van der Meiden, H.J.; Meijer, F.G.; Montvai, A.; Oyevaar, T.; Pijper, F.J.; Polman, R.W.; Rommers, J.H.; Salzedas, F.; Schokker, B.C.; Smeets, P.H.M.; Tanzi, C.P.; Tito, C.J.; Verhaag, G.C.H.M.; Westerhof, E.

    1997-01-01

    The RTP tokamak (R = 0.72 m, a = 0.164 m, B-phi < 2 5.T, I-p = < 150 kA) is equipped with three gyrotrons (2 x 60 GHz, 180 kW, 100 ms each; 1 x 110 GHz, 500 kW, 200 ms) for electron cyclotron heating (ECH) and current drive (ECCD). The power from one of the 60 GHz gyrotrons is launched via an

  7. Design of ITER-FEAT RF heating and current drive systems

    International Nuclear Information System (INIS)

    Bosia, G.; Kobayashi, N.; Ioki, K.; Bibet, P.; Koch, R.; Chavan, R.; Tran, M.Q.; Takahashi, K.; Kuzikov, S.; Vdovin, V.

    2001-01-01

    Three radio frequency (RF) heating and current drive (H and CD) systems are being designed for ITER-FEAT: an electron cyclotron (EC), an ion cyclotron (IC) and a lower hybrid (LH) System. The launchers of the RF systems use four ITER equatorial ports and are fully interchangeable. They feature equal power outputs (20 MW/port), similar neutron shielding performance, and identical interfaces with the other machine components. An outline of the design is given in the paper. (author)

  8. RF current drive in a toroidal plasna in the banana regime

    International Nuclear Information System (INIS)

    Belikov, V.S.; Kolesnichenko, Ya.I.; Plotnik, I.S.

    1982-01-01

    The use of travelling waves for the steady-state current drive in an axisymmetric toroidal plasma in the banana regime is studied. The treatment is based on a quasi-linear equation for the electron distribution function averaged over the period of the particle motion along the small azimuth of the torus. It is show that the trapped electrons do not absorb the energy of the monochromatic (over frequency) RF field and thus only the circulating electrons contribute to the driving current and to the absorbed RF power. The current and the absorbed power are calculated by using the electron distribution function obtained for the case of narrow wave packet, both the toroidal magnetic field and the distortion of the electron distribution over transverse velocities being taken into consideration. The significant role of the barely carculating electrons is revealed. It is pointed out that the toroidal satellite resonances can affect the RF current drive by spreading and splitting the region of the wave-marticle interaction

  9. Development of constant-power driving control for light-emitting-diode (LED) luminaire

    KAUST Repository

    Huang, Bin-Juine

    2013-01-01

    The illumination of an LED may be affected by operating temperature even under constant-current condition. A constant-power driving technique is proposed in the present study for LED luminaire. A linear system dynamics model of LED luminaire is first derived and used in the design of the feedback control system. The PI controller was designed and tuned taking into account the control accuracy and robust properties with respect to plant uncertainty and variation of operating conditions. The control system was implemented on a microprocessor and used to control a 150W LED luminaire. The test result shows that the feedback system accurately controls the input power of LED luminaire to within 1.3 per cent error. As the ambient temperature changes from 0 to 40 °C, the LED illumination varies slightly (-1.7%) for constant-power driving, as compared to that of constant-current driving (-12%) and constant-voltage driving (+50%). The constant-power driving has revealed advantage in stabilizing the illumination of LED under large temperature variation. © 2012 Elsevier Ltd. All rights reserved.

  10. Path-sum calculations for rf current drive

    International Nuclear Information System (INIS)

    Belo, Jorge H.; Bizarro, Joao P.S.; Rodrigues, Paulo

    2001-01-01

    Path sums and Gaussian short-time propagators are used to solve two-dimensional Fokker-Planck models of lower-hybrid (LH) and electron-cyclotron (EC) current drive (CD), and are shown to be well suited to the two limiting situations where the rf quasilinear diffusion coefficient is either relatively small, D rf ≅0.1, or very large, D rf →∞, the latter case enabling a special treatment. Results are given for both LHCD and ECCD in the small D rf case, whereas the limiting situation is illustrated only for ECCD. To check the accuracy of path-sum calculations, comparisons with finite difference solutions are provided

  11. Edge fluctuations and global confinement with lower hybrid current drive in the ASDEX tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Stoeckel, J; Soeldner, F X; Giannone, L.; Leuterer, F; Steuer, K H [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); ASDEX Team

    1992-03-01

    Electrostatic edge fluctuations were investigated by means of Langmuir probes on the ASDEX tokamak in lower hybrid current drive regimes, simultaneously with the global particle and energy balances. It was found that the edge fluctuations are reduced and the global particle/energy confinement improves when the LH power is below the initial ohmic power. The maximum reduction of the fluctuations and the best confinement occur when the total power input (OH + LH) is minimum. With a LH power higher than the initial OH value, the fluctuation level increases noticeably, while no improvement of the global confinement is observed. The increase of the edge fluctuations seems to be poloidally localized and caused by local power deposition in front of the grill antenna. Therefore, the relative positions of the probe and antenna structure have to be taken account for correct interpretation of the fluctuation data. (orig.).

  12. Edge fluctuations and global confinement with lower hybrid current drive in the ASDEX tokamak

    International Nuclear Information System (INIS)

    Stoeckel, J.; Soeldner, F.X.; Giannone, L.; Leuterer, F.; Steuer, K.H.

    1992-03-01

    Electrostatic edge fluctuations were investigated by means of Langmuir probes on the ASDEX tokamak in lower hybrid current drive regimes, simultaneously with the global particle and energy balances. It was found that the edge fluctuations are reduced and the global particle/energy confinement improves when the LH power is below the initial ohmic power. The maximum reduction of the fluctuations and the best confinement occur when the total power input (OH + LH) is minimum. With a LH power higher than the initial OH value, the fluctuation level increases noticeably, while no improvement of the global confinement is observed. The increase of the edge fluctuations seems to be poloidally localized and caused by local power deposition in front of the grill antenna. Therefore, the relative positions of the probe and antenna structure have to be taken account for correct interpretation of the fluctuation data. (orig.)

  13. Non-inductive current drive via helicity injection by Alfven waves in low aspects ratio Tokamak

    International Nuclear Information System (INIS)

    Cuperman, S.; Bruma, C.; Komoshvili, K.

    1996-01-01

    A theoretical investigation of radio frequency (RF) current drive via helicity injection in low aspect ratio tokamaks was carried out. A current-carrying cylindrical plasma surrounded by a helical sheet-current antenna and situated inside a perfectly conducting shell was considered. Toroidal features of low aspect ratio tokamaks were simulated by incorporation of the following effects: (i) arbitrarily small aspect ratio, R o /a ≡ 1/ε (ii) strongly sheared equilibrium magnetic field; and (iii) relatively large poloidal component of the equilibrium magnetic field. The study concentrates on the Alfven continuum, i.e. the case in which the wave frequency satisfies the condition {ω Alf (r)} min ≤ω≥{ω Alf (r)} max , where ω Alf (r)≡ω[n(r),B o (o)] is an eigenfrequency of the shear Alfven wave (SAW). Thus, using low-p, ideal magneto-hydrodynamics, the wave equation with correct boundary (matching) conditions was solved, the RF field components were found and subsequently, current drive , power deposition and efficiency were computed. The results of our investigation clearly demonstrate the possibility of generation of RF-driven currents via helicity injection by Alfven waves in low aspect ratio tokamaks, in the SAW mode. A special algorithm was developed which enables the selection of the antenna parameters providing optimal current drive efficiency. (authors)

  14. RF heating and current drive on NSTX with high harmonic fast waves

    International Nuclear Information System (INIS)

    Ryan, P.M.; Swain, D.W.; Rosenberg, A.L.

    2003-01-01

    NSTX is a small aspect ratio tokamak (R = 0.85 m, a = 0.65 m). The High Harmonic Fast Wave (HHFW) system is a 30 MHz, 12-element array capable of launching both symmetric and directional wave spectra for plasma heating and non-inductive current drive. It has delivered up to 6 MW for short pulses and has routinely operated at ∼3 MW for 100-400 ms pulses. Results include strong, centrally-peaked electron heating in both D and He plasmas for both high and low phase velocity spectra. H-modes were obtained with application of HHFW power alone, with stored energy doubling after the L-H transition. Beta poloidal as large as unity has been obtained with significant fractions (0.4) of bootstrap current. Differences in the loop voltage are observed depending on whether the array is phased to drive current in the co- or counter-current directions. A fast ion tail with energies extending up to 140 keV has been observed when HHFW interacts with 80 keV neutral beams; neutron rate and lost ion measurements, as well as modeling, indicate significant power absorption by the fast ions. Radial rf power deposition and driven current profiles have been calculated with ray tracing and kinetic full-wave codes and compared with measurements. (author)

  15. Power-Quality-Oriented Optimization in Multiple Three-Phase Adjustable Speed Drives

    DEFF Research Database (Denmark)

    Yang, Yongheng; Davari, Pooya; Blaabjerg, Frede

    2016-01-01

    As an almost standardized configuration, Diode Rectifiers (DRs) and Silicon-Controlled Rectifiers (SCRs) are commonly employed as the front-end topology in three-phase Adjustable Speed Drive (ASD) systems. Features of this ASD configuration include: structural and control simplicity, small volume......, low cost, and high reliability during operation. Yet, DRs and SCRs bring harmonic distortions in the mains and thus lowering the overall efficiency. Power quality standards/rules are thus released. For multiple ASD systems, certain harmonics of the total grid current can be mitigated by phase......-shifting the currents drawn by SCR-fed drives, and thus it is much flexible to reduce the Total Harmonic Distortion (THD) level in such applications. However, the effectiveness of this harmonic mitigation scheme for multiple ASD systems depends on: a) the number of parallel drives, b) the power levels, and c...

  16. On Current Drive and Wave Induced Bootstrap Current in Toroidal Plasmas

    International Nuclear Information System (INIS)

    Hellsten, T.; Johnson, T.

    2008-01-01

    A comprehensive treatment of wave-particle interactions in toroidal plasmas including collisional relaxation, applicable to heating or anomalous wave induced transport, has been obtained by using Monte Carlo operators satisfying quasi-neutrality. This approach enables a self-consistent treatment of wave-particle interactions applicable to the banana regime in the neoclassical theory. It allows an extension into a regime with large temperature and density gradients, losses and transport of particles by wave-particle interactions making the method applicable to transport barriers. It is found that at large gradients the relationship between radial electric field, parallel velocity, temperature and density gradient in the neoclassical theory is modified such that coefficient in front of the logarithmic ion temperature gradient, which in the standard neoclassical theory is small and counteracts the electric field caused by the density gradient, now changes sign and contributes to the built up of the radial electric field. The possibility to drive current by absorbing the waves on trapped particles has been studied and how the wave-particle interactions affect the bootstrap current. Two new current drive mechanisms are studied: current drive by wave induced bootstrap current and selective detrapping into passing orbits by directed waves.

  17. Full-wave simulations of current profiles for fast magnetosonic wave current drive

    International Nuclear Information System (INIS)

    Dmitrieva, M.V.; Eriksson, L.-G.; Gambier, D.J.

    1992-12-01

    Numerical simulations of current drive in tokamaks by fast waves (FWCD) have been performed in the range of the ion cyclotron and at lower frequencies via 3-Dimensional numerical code ICTOR. Trapped particles effects were taken into account in the calculation of the fast wave current drive efficiency and the bootstrap current generation. The global efficiency of FWCD if found to be γ∼ 0.1 x 10 20 AW -1 m -2 for the Joint European Torus tokamak (JET) parameters at a central electron temperature of ∼ 10 kev. The efficiency of FWCD for reactor-like plasmas is found to be γ∼0.3 x 10 20 AW -1 m -2 for ∼ 100% of FWCD and γ∼ 1 x 10 20 AW -1 m -2 for FWCD and ∼ 65% of bootstrap in a total current of ∼ 25MA at a 25kev central temperature with a density of ∼10 20 m -3 and major radius R ∼ 8m. Non-inductive current density profiles are studied. Broad FWCD current profiles are obtained for flat reactor temperature and density profiles with bootstrap current concentrated at the plasma edge. The possibility of a steady-state reactor on full wave (FW) with a large fraction of bootstrap current is discussed. It appears to be impractical to rely on such an external current driven (CD) scheme for a reactor as long a γ is less than 2 x 10 20 AW -1 m -2 . (Author)

  18. Off-axis current drive and real-time control of current profile in JT-60U

    International Nuclear Information System (INIS)

    Suzuki, T.; Ide, S.; Oikawa, T.; Fujita, T.; Ishikawa, M.; Seki, M.; Matsunaga, G.; Hatae, T.; Naito, O.; Hamamatsu, K.; Sueoka, M.; Hosoyama, H.; Nakazato, M.

    2008-01-01

    Aiming at optimization of current profile in high-β plasmas for higher confinement and stability, a real-time control system of the minimum of the safety factor (q min ) using the off-axis current drive has been developed. The off-axis current drive can raise the safety factor in the centre and help to avoid instability that limits the performance of the plasma. The system controls the injection power of lower-hybrid waves, and hence its off-axis driven current in order to control q min . The real-time control of q min is demonstrated in a high-β plasma, where q min follows the temporally changing reference q min,ref from 1.3 to 1.7. Applying the control to another high-β discharge (β N = 1.7, β p = 1.5) with m/n = 2/1 neo-classical tearing mode (NTM), q min was raised above 2 and the NTM was suppressed. The stored energy increased by 16% with the NTM suppressed, since the resonant rational surface was eliminated. For the future use for current profile control, current density profile for off-axis neutral beam current drive (NBCD) is for the first time measured, using the motional Stark effect diagnostic. Spatially localized NBCD profile was clearly observed at the normalized minor radius ρ of about 0.6-0.8. The location was also confirmed by multi-chordal neutron emission profile measurement. The total amount of the measured beam driven current was consistent with the theoretical calculation using the ACCOME code. The CD location in the calculation was inward shifted than the measurement

  19. Active power compensator of the current harmonics based on the instantaneous power theory

    Directory of Open Access Journals (Sweden)

    Marian GAICEANU

    2005-12-01

    Full Text Available The quality of the electrical current becomes a major concern. The proliferation of the power electronic converters, which are used extensively to control electrical apparatus in industrial and commercial applications (dc and ac variable speed motor drives, induction furnaces, power line conditioners, and industrial power supplies, is at the origin of the AC current distribution network pollution and the reactive power demand. These power electronic converters typically draw non-sinusoidal currents from the utility, causing interference with adjacent sensitive loads and limit the utilization of the available electrical supply. The quality of the electrical current thus becomes a significant concern for the distributors of energy and their customers. Recent progress as regards technology of the power electronics brings a capacity of compensation and correction of the harmonic distortion generated by the nonlinear loads. In this paper a parallel active filter prototype capable of reducing the total harmonic distortion in the supply for most current source or adjustable speed drive type loads is presented. A 33 kVA active power filter was developed for harmonic and reactive power compensation based on the instantaneous power theory. The active filter configuration requires the measurement of both the load and filter currents. Experimental results from a prototype active power filter confirm the suitability of the proposed approach. The actual 33kVA prototype converter has been built and tested in the SIEI S.p.A. (Italy laboratory under the Marie Curie Post Doctoral research. The active power compensator is controlled by a high performance DSP platform, resulting in the following active filter features: source current reduction up to the 25th harmonic, 10% THD achievable for current source type loads, efficiency above 97%, does not cause resonance with other loads, operation in the presence of unbalanced loads, reactive power and harmonics

  20. Electron Energy Confinement for HHFW Heating and Current Drive Phasing on NSTX

    International Nuclear Information System (INIS)

    Hosea, J.C.; Bernabei, S.; Biewer, T.; LeBlanc, B.; Phillips, C.K.; Wilson, J.R.; Stutman, D.; Ryan, P.; Swain, D.W.

    2005-01-01

    Thomson scattering laser pulses are synchronized relative to modulated HHFW power to permit evaluation of the electron energy confinement time during and following HHFW pulses for both heating and current drive antenna phasing. Profile changes resulting from instabilities require that the total electron stored energy, evaluated by integrating the midplane electron pressure P(sub)e(R) over the magnetic surfaces prescribed by EFIT analysis, be used to derive the electron energy confinement time. Core confinement is reduced during a sawtooth instability but, although the electron energy is distributed outward by the sawtooth, the bulk electron energy confinement time is essentially unaffected. The radial deposition of energy into the electrons is noticeably more peaked for current drive phasing (longer wavelength excitation) relative to that for heating phasing (shorter wavelength excitation) as is expected theoretically. However, the power delivered to the core plasma is reduced consider ably for the current drive phasing, indicating that surface/peripheral damping processes play a more important role for this case

  1. Performance improvement of sensorless vector control for matrix converter drives using PQR power theory

    DEFF Research Database (Denmark)

    Lee, Kyo Beum; Blaabjerg, Frede

    2007-01-01

    This paper presents a new method to improve sensorless performance of matrix converter drives using PQR power transformation. The non-linearity of matrix converter drives such as commutation delay, turn-on and turn-off time of switching device, and on-state switching device voltage drop is modelled...... using PQR transformation and compensated using a reference current control scheme. To eliminate the input current distortion due to the input voltage unbalance, a simple method using PQR transformation is also proposed. The proposed compensation method is applied for high performance induction motor...

  2. Current profile evolution during fast wave current drive on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Petty, C.C.; Forest, C.B.; Baity, F.W.

    1995-06-01

    The effect of co and counter fast wave current drive (FWCD) on the plasma current profile has been measured for neutral beam heated plasmas with reversed magnetic shear on the DIII-D tokamak. Although the response of the loop voltage profile was consistent with the application of co and counter FWCD, little difference was observed between the current profiles for the opposite directions of FWCD. The evolution of the current profile was successfully modeled using the ONETWO transport code. The simulation showed that the small difference between the current profiles for co and counter FWCD was mainly due to an offsetting change in the o at sign c current proffie. In addition, the time scale for the loop voltage to reach equilibrium (i.e., flatten) was found to be much longer than the FWCD pulse, which limited the ability of the current profile to fully respond to co or counter FWCD

  3. Neoclassical Physics for Current Drive in Tokamak Plasmas

    International Nuclear Information System (INIS)

    Duthoit, F.X.

    2012-03-01

    The Lie transform formalism is applied to charged particle dynamics in tokamak magnetic topologies, in order to build a Fokker-Planck type operator for Coulomb collisions usable for current drive. This approach makes it possible to reduce the problem to three dimensions (two in velocity space, one in real space) while keeping the wealth of phase-space cross-term coupling effects resulting from conservation of the toroidal canonical momentum (axisymmetry). This kinetic approach makes it possible to describe physical phenomena related to the presence of strong pressure gradients in plasmas of an unspecified form, like the bootstrap current which role will be paramount for the future ITER machine. The choice of coordinates and the method used are particularly adapted to the numerical resolution of the drift kinetic equation making it possible to calculate the particle distributions, which may present a strong variation with respect to the Maxwellian under the effect of an electric field (static or produced by a radio-frequency wave). This work, mainly dedicated to plasma physics of tokamaks, was extended to those of space plasmas with a magnetic dipole configuration. (author)

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

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Porkolab, M.

    1993-01-01

    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

  5. Driving the Power of AIX Performance Tuning on IBM Power

    CERN Document Server

    Milberg, Ken

    2009-01-01

    A concise reference for IT professionals, this book goes beyond the rules and contains the best practices and strategies for solid tuning methodology. Tips based on years of experience from an AIX tuning master show specific steps for monitoring and tuning CPU, virtual memory, disk I/O, and network components. Also offering techniques for tuning Oracle and Linux structures that run on an IBM power system-as well as for the new AIX 6.1-this manual discusses what tools are available, how to best use them to collect historical data, and when to analyze trends and results. The only comprehensive,

  6. Direct current power delivery system and method

    Science.gov (United States)

    Zhang, Di; Garces, Luis Jose; Dai, Jian; Lai, Rixin

    2016-09-06

    A power transmission system includes a first unit for carrying out the steps of receiving high voltage direct current (HVDC) power from an HVDC power line, generating an alternating current (AC) component indicative of a status of the first unit, and adding the AC component to the HVDC power line. Further, the power transmission system includes a second unit for carrying out the steps of generating a direct current (DC) voltage to transfer the HVDC power on the HVDC power line, wherein the HVDC power line is coupled between the first unit and the second unit, detecting a presence or an absence of the added AC component in the HVDC power line, and determining the status of the first unit based on the added AC component.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bosia, G.; Ragona, R. [Department of Physics, Università di Torino (Italy); Helou, W.; Goniche, M.; Hillaret, J. [CEA/DSM/IRFM F-13 108 St Paul Les Durance (France)

    2014-02-12

    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.

  8. EC + LH current drive efficiency in the presence of an internal transport barrier

    International Nuclear Information System (INIS)

    Rosa, P.R. da S; Ziebell, L.F.

    2002-01-01

    In this paper we study the effects of the presence of an internal transport barrier (ITB) on the current drive efficiency and power deposition profiles in the case of electron cyclotron waves interacting with an extended tail generated by lower hybrid (LH) waves. We study the subject by numerically solving the Fokker-Planck equation, with temperature and density profiles corrected along the time evolution at each collision time, based on the actual time-evolving electron distribution function. The results obtained show that the LH and electron cyclotron (EC) power absorption profiles and the current driven by the combined action of both types of waves are weakly dependent on the depth of the ITB, slightly more dependent on the level of magnetic turbulence and much more dependent on the level of EC wave power. (author)

  9. Fast-wave ion cyclotron current drive for ITER and prospects for near-term proof-of-principle experiments

    International Nuclear Information System (INIS)

    Swain, D.W.; Batchelor, D.B.; Carter, M.D.; Jaeger, E.F.; Ryan, P.M.; Hoffman, D.J.

    1989-01-01

    Low-frequency fast-wave current drive (FWCD) with frequencies in the range from 30 to 100 MHz looks promising for current drive in ITER. Its theoretical efficiencies are comparable to other current-drive techniques, and it could be significantly cheaper than other proposed current drive methods because of the ready availability of inexpensive (<$1/W), efficient, multi-megawatt rf power sources. The most critical issues for FWCD are concerns about the acceptability and survivability of an appropriate antenna launching system and the lack of an experimental demonstration of FWCD in a large tokamak. We describe an antenna array that is flush with the first wall of ITER and should be able to survive in the plasma environment, present theoretical calculations of FWCD in ITER, and show results from a brief survey of some present-day tokamaks in which it might be possible to carry out FWCD proof-of-principle experiments. 4 refs., 5 figs., 1 tab

  10. Power spectra of currents off Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Current measurements were carried out using a recording current meter across the continental shelf off Bombay, Maharashtra, India at 4 stations from an anchored ship. Power spectra were computed for selected lengths of records. Spectral energy...

  11. Two phase interleaved buck converter for driving high power LEDs

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Munk-Nielsen, Stig

    2011-01-01

    The goal of this paper is to evaluate an interleaved buck topology for driving high current light-emitting diodes. Low output capacitor value allows the use of non-electrolytic capacitors extending the lifetime of the converter. Converter is operated as a constant, regulated current source which...... increases luminous efficacy of LED compared to PWM dimmed system. Because of the low dynamic resistance of LEDs the duty cycle of the converter does not change greatly with controlled current. By setting the input voltage of the buck converter to around twice the voltage of diode strings, converter can...

  12. Electron-cyclotron wave propagation, absorption and current drive in the presence of neoclassical tearing modes

    Science.gov (United States)

    Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas

    2012-09-01

    We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation.

  13. Electron-cyclotron wave propagation, absorption and current drive in the presence of neoclassical tearing modes

    International Nuclear Information System (INIS)

    Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas

    2012-01-01

    We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation. (paper)

  14. Heating, current drive and MHD control using ECH in TCV

    International Nuclear Information System (INIS)

    Goodman, T.

    2001-01-01

    The 6 beam 2nd harmonic X-mode (X2), 3MW, ECH/ECCD system of the TCV tokamak allows a fine tailoring of the deposition profiles in the plasma. The sensitivity of the sawtooth period to the deposition location is used to increase the equilibria reconstruction and ray-tracing accuracy. Off-axis ECH, followed by on-axis counter-ECCD produces improved central confinement regimes in which τ Ee exceeds RLW scaling by a factor of 3.5. The PRETOR transport code (incorporating an RLW local transport model but constrained by the experimental density profiles) predicts an extreme sensitivity of τ Ee to the deposition location of the counter-ECCD. This is confirmed by experiments. Sawtooth simulations using PRETOR, including the effects of current drive with inputs from the TORAY ray-tracing code, are in good agreement with experimental results. These results are an initial benchmark for the package of analysis codes, LIUQE/TORAY/PRETOR used during ECH/ECCD experiments on TCV. (author)

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

    DEFF Research Database (Denmark)

    Adamsen, Jannie Mia; Beasley, Keiran

    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......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....... 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....

  16. Radiofrequency Waves, Heating and Current Drive in Magnetically Confined Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Porkolab, M; Bonoli, P T; Temkin, R J [Plasma Science and Fusion Center, MIT, Cambridge, MA (United States); Pinsker, R I; Prater, R [General Atomics, San Diego, California (United States); Wilson, J R [Princeton Plasma Physics Laboratory, Princeton, NJ (United States)

    2012-09-15

    The need for supplementary heating of magnetically confined plasmas to fusion relevant temperatures ({approx}20 keV) has been recognized from the beginning of modern fusion plasma research. Although in tokamaks the plasmas are formed initially by ohmic heating (P{Omega}{approx}{eta}{sub R}j, where j is the current density and {eta}{sub R} is the resistivity) its effectiveness deteriorates with increasing temperature since the resistivity decreases as T{sub e}{sup -3/2}, and losses due to bremsstrahlung radiation increase as Z{sub eff}{sup 3} T{sub e}{sup 1/2} (where Z{sub eff} is the effective ion charge), and the plasma current cannot be raised to arbitrarily large values because of MHD stability limits. In addition, energy losses due to thermal conduction P{sub loss} are typically anomalously large compared to neoclassical predictions and the dependence on temperature is not well understood. Thus, the simplest form of steady state power balance indicates that losses due to radiation and heat conduction must be balanced by auxiliary heating of some form, P{sub aux}, which may simply be stated as P{sub {Omega}} + P{sub {alpha}} - P{sub loss} P{sub aux} where P{sub {alpha}} is the power input provided by alpha particles, which does not become significant until the temperature exceeds some tens of keV, depending on confinement and density. (author)

  17. Progress of neutral beam R and D for plasma heating and current drive at JAERI

    International Nuclear Information System (INIS)

    Ohara, Y.

    1995-01-01

    Recent progress and future plans regarding development of a high power negative ion source at the Japan Atomic Energy Research Institute (JAERI) are described. The neutral beam injection system, which is expected to play an important role not only in plasma heating but also in the plasma current drive in the fusion reactor, requires a high power negative ion source which can produce negative deuterium ion beams with current of order 20A at energy above 1MeV. In order to realize such a high power negative ion beam, intensive research and development has been carried out at JAERI since 1984. The negative hydrogen ion beam current of 10A achieved in recent years almost equals the value required for the fusion reactor. With regard to the negative ion acceleration, a high current negative ion beam of 0.2A has been accelerated up to 350keV electrostatically. On the basis of this recent progress, two development plans have been initiated as an intermediate step towards the fusion reactor. One is to develop a 500keV, 10MW negative ion based neutral beam injection system for JT-60U to demonstrate the neutral beam current drive in a high density plasma. The other is to develop a 1MeV, 1A ion source to demonstrate high current negative ion acceleration up to 1MeV. On the basis of this research and development, an efficient and reactor relevant neutral beam injection system will be developed for an experimental fusion reactor such as the International Thermonuclear Experimental Reactor. ((orig.))

  18. Active load current sharing in fuel cell and battery fed DC motor drive for electric vehicle application

    International Nuclear Information System (INIS)

    Pany, Premananda; Singh, R.K.; Tripathi, R.K.

    2016-01-01

    Highlights: • Load current sharing in FC and battery fed dc drive. • Active current sharing control using LabVIEW. • Detail hardware implementation. • Controller performance is verified through MATLAB simulation and experimental results. - Abstract: In order to reduce the stress on fuel cell based hybrid source fed electric drive system the controller design is made through active current sharing (ACS) technique. The effectiveness of the proposed ACS technique is tested on a dc drive system fed from fuel cell and battery energy sources which enables both load current sharing and source power management. High efficiency and reliability of the hybrid system can be achieved by proper energy conversion and management of power to meet the load demand in terms of required voltage and current. To overcome the slow dynamics feature of FC, a battery bank of adequate power capacity has to be incorporated as FC voltage drops heavily during fast load demand. The controller allows fuel cell to operate in normal load region and draw the excess power from battery. In order to demonstrate the performance of the drive using ACS control strategy different modes of operation of the hybrid source with the static and dynamic behavior of the control system is verified through simulation and experimental results. This control scheme is implemented digitally in LabVIEW with PCI 6251 DAQ I/O interface card. The efficacy of the controller performance is demonstrated in system changing condition supplemented by experimental validation.

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

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Blaabjerg, Frede

    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...... 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...... of the interharmonic distortions in the ASD applications are analyzed under balanced and unbalanced load conditions. Thereafter, the key role of the EI at the DC stage is investigated in terms of high impedance and current harmonics transfer. Obtained experiments and simulations for both EI-based and conventional ASD...

  20. The Organic Power Transistor: Roll-to-Roll Manufacture, Thermal Behavior, and Power Handling When Driving Printed Electronics

    DEFF Research Database (Denmark)

    Pastorelli, Francesco; Schmidt, Thomas Mikael; Hösel, Markus

    2016-01-01

    to drive large currents while handling the thermal aspects in operation together with other organic printed electronics technologies such as large area organic photovoltaics (OPV)[2] and large area electrochromic displays (EC).[3] We find especially that an elevated operational temperature is beneficial...... with respect to both transconductance and on/off ratio. We achieve high currents of up to 45mA at a temperature of 80 C with an on/ off ratio of 100 which is sufficient to drive large area organic electronics such as an EC device powered by OPV devices that we also demonstrate. Finally, we observe......We present flexible organic power transistors prepared by fast (20mmin1) roll-to-roll (R2R) flexographic printing[1] of the drain (D) and source (S) electrode structures directly on polyester foil. The devices have top gate architecture and were completed by spin coating or slot-die coating...

  1. Beat wave current drive experiment on the Davis Diverted Tokamak (DDT)

    International Nuclear Information System (INIS)

    Hwang, D.Q.; Horton, R.D.; Rogers, J.H.

    1993-01-01

    The beatwave current drive experiment is summarized. The first phase of the experiment was the construction of the microwave sources and the diagnostics needed to demonstrate the beat wave effects, i.e. the measurement of the electrostatic plasma wave produced by the beating of two high intensity electromagnetic waves. In order to keep the cost of the experiments to a minimum, a low density filament plasma source (10 8 ) to (10 10 particles cm -3 ) was employed and the magnetic field in the toroidal plasma was produced by a dc power supply

  2. Current drive in a tokamak reactor during the heating of fast α particles

    International Nuclear Information System (INIS)

    Krasheninnikov, S.I.; Soboleva, T.K.

    1987-01-01

    Expressions are derived for the efficiency of the current drive in the approximation of a straight magnetic field through a solution of the kinetic equation for the distribution function of α particles as they are heated by rf waves. Three mechanisms for the absorption of the rf power in plasma are examined: cyclotron absorption at the fundamental frequency, Landau damping, and magnetic Landau damping. The efficiency of this method is shown to be at worst no lower than the efficiencies of methods involving electron heating

  3. QUALITATIVE ANALYSIS OF DEPENDENCE OF DRIVE POWER HORIZONTAL-INCLINED BELT CONVEYOR ON ITS INITIAL PARAMETERS

    Directory of Open Access Journals (Sweden)

    V. M. Bohomaz

    2017-02-01

    Full Text Available Purpose.One of the main elements of band conveyors is a drive. To analyze the effect of design parameters on the drive power it is necessary to carry out the calculations according to standard procedures outlined in the current technical literature. The main design parameters of the band conveyor are: the type of cargo, project performance, the geometric dimensions of sections and track configuration as a whole. The feature of band conveyor calculation as compared to the elevators is the dependence of the band width on its performance, the inclination angle and the type of cargo. In the article for the account of this fact during calculations it is necessary to construct the dependence of the band width on the generalized parameter, which takes into account change in the design parameters. To determine the general pattern of changing the value of band conveyor drive power when varying its design parameters in the article it is necessary to construct the corresponding graphic dependences taking into account the standard sizes and bands parameters. Methodology. We consider the band conveyor with two sections: the inclined and horizontal one. It is conducted a detailed analysis of dependence of the conveyor band width and its drive power on the type of cargo, project performance, geometric dimensions and configuration of the conveyor track, using the appropriate parameter dependences constructed by the authors in previous papers. Findings. For band conveyors of this type there were constructed the graphics dependences of the band width on the parameter characterizing the project performance and the inclination angle of the track section, and on the performance at a fixed angle of inclination. Taking into account the changes in the band width with an increase in the value of project performance the graph dependences of drive power on the productivity and the inclination angle of the inclined section were built. Originality. For the first time there

  4. The Impact of Drive Cycles and Auxiliary Power on Passenger Car Fuel Economy

    Directory of Open Access Journals (Sweden)

    Thomas Grube

    2018-04-01

    Full Text Available In view of the advancement of zero emission transportation and current discussions on the reliability of nominal passenger car fuel economy, this article considers the procedure for assessing the potential for reducing the fuel consumption of passenger cars by using electric power to operate them. The analysis compares internal combustion engines, hybrid and fully electric concepts utilizing batteries and fuel cells. The starting point for the newly developed, simulation-based fuel consumption analysis is a longitudinal vehicle model. Mechanical power requirements on the drive side incorporate a large variety of standardized drive cycles to simulate typical patterns of car usage. The power requirements of electric heating and air conditioning are also included in the simulation, as these are especially relevant to electric powertrains. Moreover, on-board grid-load profiles are considered in the assessment. Fuel consumption is optimized by applying concept-specific operating strategies. The results show that the combination of low average driving speed and elevated onboard power requirements have severe impacts on the fuel efficiency of all powertrain configurations analyzed. In particular, the operational range of battery-electric vehicles is strongly affected by this due to the limited storage capacity of today’s batteries. The analysis confirms the significance of considering different load patterns of vehicle usage related to driving profiles and onboard electrical and thermal loads.

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

    CERN Document Server

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

    2004-01-01

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

  6. IMPROVING MODEL OF CHANNEL AIRBORN ELECTRICAL POWER SYSTEM OF ALTERNATING CURRENT

    Directory of Open Access Journals (Sweden)

    Yu. P. Artemenko

    2015-01-01

    Full Text Available This article is devoted to math modeling of channel of alternating current airborne electrical power-supply system. Mathematical modeling of generator, voltage regulator, constant speed drive is considered.

  7. Low frequency RF current drive. Final report, January 1, 1988 - May 31, 1997

    International Nuclear Information System (INIS)

    Hershkowitz, N.

    1999-01-01

    This report starts with a summary of research done on the Phaedrus Tandom Mirror concept and how this research led to the design and construction of the Phaedrus-T Tokamak. Next it gives a more detailed description of the results from the last four years of research, which include the following areas: (1) first experimental demonstration of AWCD (Alfven Wave Current Drive); (2) current drive location and loop voltage response; (3) trapping and current drive efficiency; and (4) reflectometry

  8. Control systems for ITER diagnostics, heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Simrock, Stefan, E-mail: stefan.simrock@iter.org

    2016-11-15

    The ITER Diagnostic, Heating and Current Drive systems might appear, on the face of it, to have very different control requirements. There are approximately 45 diagnostic systems, including magnetic sensors for plasma position and shape determination, imaging systems in the IR and visible, Thompson scattering for electron temperature and density, neutron detectors and collective scattering for alpha particle density and energy distribution. The H&CD systems encompass Electron Cyclotron Heating, using 24 1MW, 170 GHz gyrotrons and 5 steerable launchers to deliver 20 MW to the plasma, Ion Cyclotron Heating, using 8 3MW, 40–55 MHz sources and two multi-element launchers to deliver 20 MW to the plasma, and 2 Negative Ion Neutral Beam Injectors, each of which can deliver up to 16.5 MW of 1 MeV beams to the plasma. Although there are substantial differences in the needs for protection, when handling multi-MW heating systems, and in data throughput for many diagnostics, the formal processes needed to translate system requirements into Instrumentation and Control are identical. Due to the distributed procurement of ITER sub-systems and the need to integrate as painlessly as possible to CODAC, the formal processes, together with a substantial degree of standardization, are even more than usually essential. Starting from the technical, safety and protection, integration and operation requirements, a loop of functional analysis and signal listing is used to generate the controller configuration and the conceptual architecture. These elements in their turn lead to the physical and software design. The paper will describe the formal processes of control system design and the methods used by the ITER project to achieve the standardization of systems engineering practices. These have been applied to several use-cases covering all operation relevant phases such as plasma operation, maintenance, testing and conditioning. There are a number of running contracts that are developing

  9. The drive beam pulse compression system for the CLIC RF power source

    CERN Document Server

    Corsini, R

    1999-01-01

    The Compact LInear Collider (CLIC) is a high energy (0.5 to 5 TeV) e ± linear collider that uses a high- current electron beam (the drive beam) for 30 GHz RF power production by the Two-Beam Acceleration (TBA) method. Recently, a new cost­effective and efficient generation scheme for the drive beam has been developed. A fully­loaded normal­conducting linac operating at lower frequency (937 MHz) generates and accelerates the drive beam bunches, and a compression system composed of a delay­line and two combiner rings produces the proper drive beam time structure for RF power generation in the drive beam decelerator. In this paper, a preliminary design of the whole compression system is presented. In particular, the fundamental issue of preserving the bunch quality along the complex is studied and its impact on the beam parameters and on the various system components is assessed. A first design of the rings and delay­line lattice, including path length tuning chicanes, injection and extraction regions is a...

  10. Progress in the ITER electron cyclotron heating and current drive system design

    Energy Technology Data Exchange (ETDEWEB)

    Omori, Toshimichi, E-mail: toshimichi.omori@iter.org [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Albajar, Ferran; Bonicelli, Tullio; Carannante, Giuseppe; Cavinato, Mario; Cismondi, Fabio [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Darbos, Caroline [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Denisov, Grigory [Institute of Applied Physics Russian Academy of Sciences, 46 Ulyanov Street, Nizhny Novgorod 603950 (Russian Federation); Farina, Daniela [Istituto di Fisica del Plasma, Association EURATOM-ENEA-CNR, Milano (Italy); Gagliardi, Mario [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Gandini, Franco; Gassmann, Thibault [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Goodman, Timothy [CRPP, Association EURATOM-Confédération Suisse, EPFL Ecublens, CH-1015 Lausanne (Switzerland); Hanson, Gregory [US ITER Project Office, ORNL, 055 Commerce Park, PO Box 2008, Oak Ridge, TN 37831 (United States); Henderson, Mark A. [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Kajiwara, Ken [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan); McElhaney, Karen [US ITER Project Office, ORNL, 055 Commerce Park, PO Box 2008, Oak Ridge, TN 37831 (United States); Nousiainen, Risto [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Oda, Yasuhisa [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan); Oustinov, Alexander [Institute of Applied Physics Russian Academy of Sciences, 46 Ulyanov Street, Nizhny Novgorod 603950 (Russian Federation); and others

    2015-10-15

    Highlights: • EC system is designed with an ability to upgrade in power to 28 MW then 40 MW. • The TL is capable of 3 buildings movements; ±15 mm displacements at the worst. • Improved power deposition access injecting 20 MW across nearly the entire plasma. • Ensured nuclear safety by appropriate definition of confinement boundaries. • Proposed I&C architecture for the overall EC plant was successfully reviewed. - Abstract: An electron cyclotron system is one of the four auxiliary plasma heating systems to be installed on the ITER tokamak. The ITER EC system consists of 24 gyrotrons with associated 12 high voltage power supplies, a set of evacuated transmission lines and two types of launchers. The whole system is designed to inject 20 MW of microwave power at 170 GHz into the plasma. The primary functions of the system include plasma start-up, central heating and current drive, and magneto-hydrodynamic instabilities control. The design takes present day technology and extends towards high power CW operation, which represents a large step forward as compared to the present state of the art. The ITER EC system will be a stepping stone to future EC systems for DEMO and beyond. The EC system is faced with significant challenges, which not only includes an advanced microwave system for plasma heating and current drive applications but also has to comply with stringent requirements associated with nuclear safety as ITER became the first fusion device licensed as basic nuclear installations as of 9 November 2012. Since conceptual design of the EC system established in 2007, the EC system has progressed to a preliminary design stage in 2012, and is now moving forward towards a final design. The majority of the subsystems have completed the detailed design and now advancing towards the final design completion.

  11. Progress in the ITER electron cyclotron heating and current drive system design

    International Nuclear Information System (INIS)

    Omori, Toshimichi; Albajar, Ferran; Bonicelli, Tullio; Carannante, Giuseppe; Cavinato, Mario; Cismondi, Fabio; Darbos, Caroline; Denisov, Grigory; Farina, Daniela; Gagliardi, Mario; Gandini, Franco; Gassmann, Thibault; Goodman, Timothy; Hanson, Gregory; Henderson, Mark A.; Kajiwara, Ken; McElhaney, Karen; Nousiainen, Risto; Oda, Yasuhisa; Oustinov, Alexander

    2015-01-01

    Highlights: • EC system is designed with an ability to upgrade in power to 28 MW then 40 MW. • The TL is capable of 3 buildings movements; ±15 mm displacements at the worst. • Improved power deposition access injecting 20 MW across nearly the entire plasma. • Ensured nuclear safety by appropriate definition of confinement boundaries. • Proposed I&C architecture for the overall EC plant was successfully reviewed. - Abstract: An electron cyclotron system is one of the four auxiliary plasma heating systems to be installed on the ITER tokamak. The ITER EC system consists of 24 gyrotrons with associated 12 high voltage power supplies, a set of evacuated transmission lines and two types of launchers. The whole system is designed to inject 20 MW of microwave power at 170 GHz into the plasma. The primary functions of the system include plasma start-up, central heating and current drive, and magneto-hydrodynamic instabilities control. The design takes present day technology and extends towards high power CW operation, which represents a large step forward as compared to the present state of the art. The ITER EC system will be a stepping stone to future EC systems for DEMO and beyond. The EC system is faced with significant challenges, which not only includes an advanced microwave system for plasma heating and current drive applications but also has to comply with stringent requirements associated with nuclear safety as ITER became the first fusion device licensed as basic nuclear installations as of 9 November 2012. Since conceptual design of the EC system established in 2007, the EC system has progressed to a preliminary design stage in 2012, and is now moving forward towards a final design. The majority of the subsystems have completed the detailed design and now advancing towards the final design completion.

  12. Propagation and scattering in Lower Hybrid Current Drive (LHCD)

    International Nuclear Information System (INIS)

    Horton, W.; Goniche, M.; Peysson, Y.; Decker, J.; Ekedahl, A.; Litaudon, X.

    2015-01-01

    Full text of publication follows. The propagation and scattering of the 5 GHz RF waves planned for driving and controlling the plasma current in stage 2 of ITER is analyzed with theory, simulations and data from Tore Supra. The internal RF wavenumber spectrum is determined by a combination of elements including the (1) the azimuthal spectrum launched by the antenna, (2) coupling of the radial and azimuthal oscillations of the ray trajectories described the ray Hamiltonian with the radial and the poloidal variation of plasma and scattering from the drift wave turbulence (ref. 1, 2). The scattering of the RF waves from the drift wave turbulence in the plasma is described through a Fokker-Planck equation for the probability density of the rays. The new 4D ray kinetic equation has (1) an edge source from the antenna, (2) a core sink from the electron resonances, and (3) a global scattering rate tensor D ij (k,r,t) derived from the ambient plasma turbulence. The tensor reduces to a parallel and cross-field component with the cross-field component describing side-scatter of the RF waves. The solutions give a spectral distribution for the parallel index of refraction from the antenna to the region of three times the core electron thermal velocity. Strong absorption of the rays occurs where the plateau in the fast electron distribution joins the steeply increasing slope of the thermal electron phase space density (ref. 3). Solutions of the ray kinetic equation with the source, sink and scattering provide the filling of the spectral gap and the efficiency of the LHCD system. The ETG turbulence is modified by the temperature anisotropies and the sharp radial gradients of the LHCD electron distribution function (ref. 3). In the presence of the ETG turbulence projections of the partial differential equations to low-order transport models are derived with dynamical feed-forward/ feedback loops following L-H-ELM modeling (ref. 4). The low-order models may be used with feedback

  13. New Pulsed Power Technology for High Current Accelerators

    International Nuclear Information System (INIS)

    Caporaso, G J

    2002-01-01

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

  14. Commissioning of the long-pulse fast wave current drive antennas for DIII-D

    International Nuclear Information System (INIS)

    Baity, F.W.; Barber, G.C.; Goulding, R.H.; Hoffman, D.J.; DeGrassie, J.S.; Pinsker, R.I.; Petty, C.C.; Cary, W.

    1995-01-01

    Two new four-element fast wave current drive antennas have been installed on DIII-D. These antennas are designed for 10-s pulses at 2 MW each in the frequency range of 30 to 120 MHz. Each element comprises two poloidal segments fed in parallel in order to optimize plasma coupling at the upper end of the frequency range. The antennas are mounted on opposite sides of the vacuum vessel, in ports designated 0 degrees and 180 degrees after their toroidal angle. Each antenna array is fed by a single transmitter. The power is first split two ways by means of a 3-dB hybrid coupler, then each of these lines feeds a resonant loop connecting a pair of array elements. The power transfer during asymmetric phasing is shunted between resonant loops by a decoupler. The resonant loops are fitted with line stretchers so that multiple frequencies of operation are possible without reconfiguring the transmission line. Commissioning of these antennas has been underway since June 1994. Several deficiencies in the transmission line system were uncovered during initial vacuum conditioning, including problems with the transmission line insulators and with the drive rods for the variable elements. The former was solved by replacing the original alumina insulators, and the latter has been avoided during operation to date by positioning the tuners to avoid high voltage appearing on the drive rods. A modified design for the drive rods will be implemented before RF operations resume operation June 1995. New transmitters were procured from ABB for the new antennas and were installed in parallel with the antenna installation. During initial vacuum conditioning of the antenna in the 180 degree port a fast digital oscilloscope was used to try to pinpoint the location of arcing by a time-of-flight technique and to develop an understanding of the typical arc signature in the system

  15. A study on the NB heating and current drive in fusion plasmas

    International Nuclear Information System (INIS)

    Jeong, Seung Ho; In, S. R.; Lee, K. W.; Oh, B. H.; Jin, J. T.; Chang, D. H.; Chang, D. S.; Kim, T. S.; Song, W. S.

    2013-03-01

    Final destination of the project is to establish the research basis of heating and current drive for large tokamak, such as KSTAR, or next generation fusion reactor through the neutral beam injection (NBI). On the 1 st -stage to achieve the objectives: 1) Required capability of an ion source(with an output power of 2 MW neutral beam, a beam energy of 100 keV) which is a main component of KSTAR NBI-1 system was proven by the design, manufacturing, and performance test during the past three years. 2) Until the development of new ion source, the NB heating experiments were performed to achieve the NB heating of KSTAR plasma with more than 1.0 MW for the 2 nd -year and more than 1.5 MW for the 3 rd -year by using a prototype ion source upgraded for the 1 st -year. From these experiments, the heating power above the H-mode threshold was supplied to the H-mode operation of KSTAR plasma and contributed to the NB diagnostics, such as CES and MSE, by using the NB. Finally, the basis of NB heating and current drive for the KSTAR was prepared by the 1 st -stage research

  16. Modern power converter drives. Drive systems, power electronics, machines, mechatronics and motion control. 5. rev. and enl. ed.; Moderne Stromrichterantriebe. Antriebssystem, Leistungselektronik, Maschinen, Mechatronik und Motion Control, Arbeitsweise drehzahlveraenderbarer Antriebe mit Stromrichtern und Antriebsvernetzung

    Energy Technology Data Exchange (ETDEWEB)

    Brosch, P.F.

    2008-07-01

    This book informs students and practicians on variable-speed drives. Constructional engineers, technicians and others are given a practical tool for their daily work. - Fundamentals of motive power engineering - power converter components - electric machines - power converter drives with commutator motors - power converter drives with induction machines - integrated drive systems - motion control and mechatronics - selection and dimensioning of variable-speed drives converter measuring engineering - electromagnetic compatibility, with examples - measurements on power converter drives with variable speed adjustment - electromagnetic compatibility. (orig./GL)

  17. Comparison of real driving cycles and consumed braking power in suburban Slovakian driving

    Directory of Open Access Journals (Sweden)

    Gechev Tsvetomir

    2017-01-01

    Full Text Available The paper compares the features of suburban real driving cycles performed with CORRSYS DATRON measurement equipment on routes in the region of Žilina, Slovakia. It observes differences in the maximum and average vehicle velocities and the amount of braking in relation to the elevation profile of each individual cycle. Consumed braking power was also calculated in the different cycles in order to review the potential electricity regeneration capabilities of hybrid electric vehicles, operating on the same routes. The change in braking energy depending on vehicle mass and presence of grade on the routes in the measured cycles was also assessed. The calculations and plotting were done by using Matlab software.

  18. ICRF Mode Conversion Current Drive for Plasma Stability Control in Tokamaks

    International Nuclear Information System (INIS)

    Grekov, D.; Kock, R.; Lyssoivan, A.; Noterdaeme, J. M.; Ongena, J.

    2007-01-01

    There is a substantial incentive for the International Thermonuclear Experimental Reactor (ITER) to operate at the highest attainable beta (plasma pressure normalized to magnetic pressure), a point emphasized by requirements of attractive economics in a reactor. Recent experiments aiming at stationary high beta discharges in tokamak plasmas have shown that maximum achievable beta value is often limited by the onset of instabilities at rational magnetic surfaces (neoclassical tearing modes). So, methods of effective control of these instabilities have to be developed. One possible way for neoclassical tearing modes control is an external current drive in the island to locally replace the missing bootstrap current and thus to suppress the instability. Also, a significant control of the sawtooth behaviour was demonstrated when the magnetic shear was modified by driven current at the magnetic surface where safety factor equals to 1. In the ion cyclotron range of frequencies (ICRF), the mode conversion regime can be used to drive the local external current near the position of the fast-to-slow wave conversion layer, thus providing an efficient means of plasma stability control. The slow wave energy is effectively absorbed in the vicinity of mode conversion layer by electrons with such parallel to confining magnetic field velocities that the Landau resonance condition is satisfied. For parameters of present day tokamaks and for ITER parameters the slow wave phase velocity is rather low, so the large ratio of momentum to energy content would yield high current drive efficiency. In order to achieve noticeable current drive effect, it is necessary to create asymmetry in the ICRF power absorption between top and bottom parts of the plasma minor cross-section. Such asymmetric electron heating may be realized using: - shifted from the torus midplane ICRF antenna in TEXTOR tokamak; - plasma displacement in vertical direction that is feasible in ASDEX-Upgrade; - the

  19. GROUNDING THE REDUCTION OF POWER OF THE HYDRAULIC DRIVE ELECTRIC MOTOR BY EQUIVALENT POWER METHOD

    Directory of Open Access Journals (Sweden)

    O. Hrygorov

    2017-06-01

    Full Text Available The authors have analyzed the power consumption by a hydraulic drive and wound rotor motor of crane mechanisms at all stages of the operational cycle: acceleration, movement at nominal or intermediate speed and deceleration. The decrease of the rated capacity of electric motors is justified.

  20. Fast wave current drive in neutral beam heated plasmas on DIII-D

    International Nuclear Information System (INIS)

    Petty, C.C.; Forest, C.B.; Pinsker, R.I.

    1997-04-01

    The physics of non-inductive current drive and current profile control using the fast magnetosonic wave has been demonstrated on the DIII-D tokamak. In non-sawtoothing discharges formed by neutral beam injection (NBI), the radial profile of the fast wave current drive (FWCD) was determined by the response of the loop voltage profile to co, counter, and symmetric antenna phasings, and was found to be in good agreement with theoretical models. The application of counter FWCD increased the magnetic shear reversal of the plasma and delayed the onset of sawteeth, compared to co FWCD. The partial absorption of fast waves by energetic beam ions at high harmonics of the ion cyclotron frequency was also evident from a build up of fast particle pressure near the magnetic axis and a correlated increase in the neutron rate. The anomalous fast particle pressure and neutron rate increased with increasing NBI power and peaked when a harmonic of the deuterium cyclotron frequency passed through the center of the plasma. The experimental FWCD efficiency was highest at 2 T where the interaction between the fast waves and the beam ions was weakest; as the magnetic field strength was lowered, the FWCD efficiency decreased to approximately half of the maximum theoretical value

  1. 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.

  2. Current drive by neutral beams, rotating magnetic fields and helicity injection in compact toroids

    International Nuclear Information System (INIS)

    Farengo, R.; Arista, N.R.; Lifschitz, A.F.; Clemente, R.A.

    2003-01-01

    The use of neutral beams (NB) for current drive and heating in spheromaks, the relaxed states of flux core spheromaks (FCS) sustained by helicity injection and the effect of ion dynamics on rotating magnetic field (RMF) current drive in spherical tokamaks (ST) are studied. (author)

  3. Lower hybrid current drive at ITER-relevant high plasma densities

    International Nuclear Information System (INIS)

    Cesario, R.; Amicucci, L.; Cardinali, A.; Castaldo, C.; Marinucci, M.; Panaccione, L.; Pericoli-Ridolfini, V.; Tuccillo, A. A.; Tudisco, O.; Calabro, G.

    2009-01-01

    Recent experiments indicated that a further non-inductive current, besides bootstrap, should be necessary for developing advanced scenario for ITER. The lower hybrid current drive (LHCD) should provide such tool, but its effectiveness was still not proved in operations with ITER-relevant density of the plasma column periphery. Progress of the LH deposition modelling is presented, performed considering the wave physics of the edge, and different ITER-relevant edge parameters. Operations with relatively high edge electron temperatures are expected to reduce the LH || spectral broadening and, consequently, enabling the LH power to propagate also in high density plasmas ( || is the wavenumber component aligned to the confinement magnetic field). New results of FTU experiments are presented, performed by following the aforementioned modeling: they indicate that, for the first time, the LHCD conditions are established by operating at ITER-relevant high edge densities.

  4. Mechanical Extraction of Power From Ocean Currents and Tides

    Science.gov (United States)

    Jones, Jack; Chao, Yi

    2010-01-01

    A proposed scheme for generating electric power from rivers and from ocean currents, tides, and waves is intended to offer economic and environmental advantages over prior such schemes, some of which are at various stages of implementation, others of which have not yet advanced beyond the concept stage. This scheme would be less environmentally objectionable than are prior schemes that involve the use of dams to block rivers and tidal flows. This scheme would also not entail the high maintenance costs of other proposed schemes that call for submerged electric generators and cables, which would be subject to degradation by marine growth and corrosion. A basic power-generation system according to the scheme now proposed would not include any submerged electrical equipment. The submerged portion of the system would include an all-mechanical turbine/pump unit that would superficially resemble a large land-based wind turbine (see figure). The turbine axis would turn slowly as it captured energy from the local river flow, ocean current, tidal flow, or flow from an ocean-wave device. The turbine axis would drive a pump through a gearbox to generate an enclosed flow of water, hydraulic fluid, or other suitable fluid at a relatively high pressure [typically approx.500 psi (approx.3.4 MPa)]. The pressurized fluid could be piped to an onshore or offshore facility, above the ocean surface, where it would be used to drive a turbine that, in turn, would drive an electric generator. The fluid could be recirculated between the submerged unit and the power-generation facility in a closed flow system; alternatively, if the fluid were seawater, it could be taken in from the ocean at the submerged turbine/pump unit and discharged back into the ocean from the power-generation facility. Another alternative would be to use the pressurized flow to charge an elevated reservoir or other pumped-storage facility, from whence fluid could later be released to drive a turbine/generator unit at a

  5. Effects of drive current rise-time and initial load density distribution on Z-pinch characteristics

    Institute of Scientific and Technical Information of China (English)

    Duan Yao-Yong; Guo Yong-Hui; Wang Wen-Sheng; Qiu Ai-Ci

    2005-01-01

    A two-dimensional, three-temperature radiation magneto-hydrodynamics model is applied to the investigation of evolutional trends in x-ray radiation power, energy, peak plasma temperature and density as functions of drive current rise-time and initial load density distribution by using the typical experimental parameters of tungsten wire-array Z-pinch on the Qiangguang-Ⅰ generator. The numerical results show that as the drive current rise-time is shortened, x-ray radiation peak power, energy, peak plasma density and peak ion temperature increase approximately linearly, but among them the x-ray radiation peak power increases more quickly. As the initial plasma density distribution in the radial direction becomes gradually flattened, the peak radiation power and the peak ion-temperature almost exponentially increase, while the radiation energy and the peak plasma density change only a little. The main effect of shortening drive current rise-time is to enhance compression of plasma, and the effect of flattening initial load density distribution in the radial direction is to raise the plasma temperature. Both of the approaches elevate the x-ray peak radiation power.

  6. Role of the lower hybrid spectrum in the current drive modeling for DEMO scenarios

    Science.gov (United States)

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

    2017-07-01

    The active control of the radial current density profile is one of the major issues of thermonuclear fusion energy research based on magnetic confinement. The lower hybrid current drive could in principle be used as an efficient tool. However, previous understanding considered the electron temperature envisaged in a reactor at the plasma periphery too large to allow penetration of the coupled radio frequency (RF) power due to strong Landau damping. In this work, we present new numerical results based on quasilinear theory, showing that the injection of power spectra with different {n}// widths of the main lobe produce an RF-driven current density profile spanning most of the outer radial half of the plasma ({n}// is the refractive index in a parallel direction to the confinement magnetic field). Plasma kinetic profiles envisaged for the DEMO reactor are used as references. We demonstrate the robustness of the modeling results concerning the key role of the spectral width in determining the lower hybrid-driven current density profile. Scans of plasma parameters are extensively carried out with the aim of excluding the possibility that any artefact of the utilised numerical modeling would produce any novelty. We neglect here the parasitic effect of spectral broadening produced by linear scattering due to plasma density fluctuations, which mainly occurs for low magnetic field devices. This effect will be analyzed in other work that completes the report on the present breakthrough.

  7. PID and predictive control of electrical drives and power converters using MATLAB/Simulink

    CERN Document Server

    Wang, Liuping; Yoo, Dae; Gan, Lu; Ng, Ki

    2015-01-01

    A timely introduction to current research on PID and predictive control by one of the leading authors on the subject PID and Predictive Control of Electric Drives and Power Supplies using MATLAB/Simulink examines the classical control system strategies, such as PID control, feed-forward control and cascade control, which are widely used in current practice.  The authors share their experiences in actual design and implementation of the control systems on laboratory test-beds, taking the reader from the fundamentals through to more sophisticated design and analysis.    The book contains secti

  8. Influences on dispatch of power generation when introducing electric drive vehicles in an Irish power system year 2020

    DEFF Research Database (Denmark)

    Juul, Nina; Mullane, Alan; Meibom, Peter

    plants. For the future transport system, electric drive vehicles are expected to be one of the solutions. Introducing different electric drive vehicle penetrations in a power system with a large amount of wind power, changes the usage of the predefined power system. This work presents investigations......Increased focus on global warming and CO2 emissions imply increased focus on the energy system, consisting of the heat, power, and transport systems. Solutions for the heat and power system are increasing penetrations of renewable heat and power generation plants such as wind power and biomass heat...... of different charging regimes’ influence of the power dispatch in the Irish power system. Analyses show an overall cost decrease and CO2 emission increase in the heat and power system with the introduction of electric drive vehicles. Furthermore, increased intelligence in the electric drive vehicle charging...

  9. ELECTRON CYCLOTRON CURRENT DRIVE IN DIII-D: EXPERIMENT AND THEORY

    International Nuclear Information System (INIS)

    PRATER, R; PETTY, CC; LUCE, TC; HARVEY, RW; CHOI, M; LAHAYE, RJ; LIN-LIU, Y-R; LOHR, J; MURAKAMI, M; WADE, MR; WONG, K-L

    2003-01-01

    A271 ELECTRON CYCLOTRON CURRENT DRIVE IN DIII-D: EXPERIMENT AND THEORY. Experiments on the DIII-D tokamak in which the measured off-axis electron cyclotron current drive has been compared systematically to theory over a broad range of parameters have shown that the Fokker-Planck code CQL3D provides an excellent model of the relevant current drive physics. This physics understanding has been critical in optimizing the application of ECCD to high performance discharges, supporting such applications as suppression of neoclassical tearing modes and control and sustainment of the current profile

  10. Current drive by asymmetrical heating in a toroidal plasma

    International Nuclear Information System (INIS)

    Gahl, J.M.

    1986-01-01

    This report describes the first experimental observation of current generation by asymmetrical heating of ions. A unidirectional fast Alfven wave launched by a slow-wave antenna inside the Texas Tech Tokamak, asymmetrically heated the ions. Measurements of the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column confirmed the current generation indirectly. Current generation, obtained in a one-species, hydrogen plasma, is a phenomenon which had not been predicted previously. Calculations of the dispersion relation for the fast Alfven wave near the fundamental cyclotron resonance in a one-species, hydrogen plasma, using warm plasma theory, support the experimental results

  11. Heating, current drive and energetic particles studies on JET in preparation of ITER operation

    International Nuclear Information System (INIS)

    Noterdaeme, J.-M.; Budny, R.; Cardinali, A.

    2003-01-01

    This paper summarizes the recent work on JET in the three areas of heating, current drive and energetic particles. The achievements have extended the possibilities of JET, have a direct connection to ITER operation and provide new and interesting physics. Toroidal rotation profiles of plasmas heated far off axis with little or no refueling or momentum input are hollow with only small differences on whether the power deposition is located on the low field side or on the high field side. With LH current drive the magnetic shear was varied from slightly positive to negative. The improved coupling (through the use of plasma shaping and CD 4 ) allowed up to 3.4 MW of P LH in ITB plasmas with more than 15MW of combined NBI and ICRF heating. The q profile with negative magnetic shear and the ITB could be maintained for the duration of the high heating pulse (8s). Fast ions have been produced in JET with ICRF to simulate alpha particles: by using third harmonic 4 He heating, beam injected 4 He at 120 kV were accelerated to energies above 2 MeV, taking advantage of the unique capability of JET to use NBI with 4 He and to confine MeV class ions. ICRF heating was used to replicate the dynamics of alpha heating and the control of an equivalent Q=10 'burn' was simulated. (author)

  12. Non-inductive current drive and RF heating in SST-1 tokamak

    International Nuclear Information System (INIS)

    2000-01-01

    Steady state superconducting tokamak (SST-1) machine is being developed for 1000 sec operation at different operating parameters. Radio Frequency (RF) and neutral beam injection (NBI) methods are planned in SST-1 for noninductive current drive and heating. In this paper, we describe the non-inductive current drive and RF heating methods that are being developed for this purpose. SST-1 is a large aspect ratio tokamak configured to run double-null divertor plasmas with significant elongation (κ = 1.7-1.9) and triangularity (δ = 0.4-0.7). SST-1 has a major radius of 1.1 in and minor radius of 0.2 m. Circular and shaped plasma experiments would be conducted at 1.5 and 3 T toroidal magnetic field in three different phases with I p = 110 kA and 220 kA. Two main factors have been considered during the development of auxiliary systems, namely, high heat flux (1 MW/m 2 ) incident on the plasma facing antennae components and fast feedback for constant power input due to small energy confinement time (∼ 10 ms). (author)

  13. Electron cyclotron heating and current drive: Present experiments to ITER. Revision 1

    International Nuclear Information System (INIS)

    Harvey, R.W.; Nevins, W.M.; Smith, G.R.; Lloyd, B.; O'Brien, M.R.; Warrick, C.D.

    1995-08-01

    Electron cyclotron (EC) power has technological and physics advantages for heating and current drive in a tokamak reactor, and advances in source development make it credible for applications in ITER. Strong single pass absorption makes heating to ignition particularly simple. The optimized EC current drive (ECCD) efficiency (left-angle n right-angle IR/P) shows a linear temperature scaling at temperatures up to ∼ 15 keV. For temperatures above 30 keV, the efficiency saturates at approximately 0.3·10 20 A/(m 2 W) for a frequency of 220 GHz in an ITER target plasma with toroidal field of 6 T, due primarily to harmonic overlap [G.R. Smith et al., Phys. Fluids 30 3633 (1987)] and to a lesser extent due to limitations arising from relativistic effects [N.J. Fisch, Phys. Rev. A 24 3245 (1981)]. The same efficiency can also be obtained at 170 GHz for the same plasma equilibrium except that the magnetic field is reduced to (170/220) x 6 T = 4.6 T. The ECCD efficiencies are obtained with the comprehensive 3D, bounce-averaged Fokker-Planck CQL3D codes [R.W. Harvey and M.G. McCoy, Proc. IAEA TCM/Advances in Simulation and Modeling in Thermonuclear Plasmas 1992, Montreal], and BANDIT3D [M.R. O'Brien, M. Cox, C.D. Warrick, and F. S. Zaitsev, ibid.

  14. Transmission line component testing for the ITER Ion Cyclotron Heating and Current Drive System

    Science.gov (United States)

    Goulding, Richard; Bell, G. L.; Deibele, C. E.; McCarthy, M. P.; Rasmussen, D. A.; Swain, D. W.; Barber, G. C.; Barbier, C. N.; Cambell, I. H.; Moon, R. L.; Pesavento, P. V.; Fredd, E.; Greenough, N.; Kung, C.

    2014-10-01

    High power RF testing is underway to evaluate transmission line components for the ITER Ion Cyclotron Heating and Current Drive System. The transmission line has a characteristic impedance Z0 = 50 Ω and a nominal outer diameter of 305 mm. It is specified to carry up to 6 MW at VSWR = 1.5 for 3600 s pulses, with transient voltages up to 40 kV. The transmission line is actively cooled, with turbulent gas flow (N2) used to transfer heat from the inner to outer conductor, which is water cooled. High voltage and high current testing of components has been performed using resonant lines generating steady state voltages of 35 kV and transient voltages up to 60 kV. A resonant ring, which has operated with circulating power of 6 MW for 1 hr pulses, is being used to test high power, low VSWR operation. Components tested to date include gas barriers, straight sections of various lengths, and 90 degree elbows. Designs tested include gas barriers fabricated from quartz and aluminum nitride, and transmission lines with quartz and alumina inner conductor supports. The latest results will be presented. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.

  15. RF heating and current drive on NSTX with high harmonic fast waves

    International Nuclear Information System (INIS)

    Ryan, P.M.

    2002-01-01

    NSTX is a small aspect ratio tokamak with a large dielectric constant (50-100); under these conditions high harmonic fast waves (HHFW) will readily damp on electrons via Landau damping and TTMP. The HHFW system is a 30 MHz, 12-element array capable of launching both symmetric and directional wave spectra for plasma heating and non-inductive current drive. It has delivered up to 6 MW for short pulses and has routinely operated at ∼3-4 MW for 100-200 ms pulses. Results include strong, centrally-peaked electron heating in both D and He plasmas, for both high and low phase velocity spectra. H-modes were obtained with application of HHFW power alone, with stored energy doubling after the L-H transition. Beta poloidal as large as unity has been obtained with large fractions (0.4) of bootstrap current. A fast ion tail with energies extending up to 140 keV has been observed when HHFW interacts with 80 keV neutral beams; neutron rate and lost ion measurements, as well as modeling, indicate significant power absorption by the fast ions. Radial power deposition profiles are being calculated with ray tracing and kinetic full-wave codes and benchmarked against measurements. (author)

  16. Methods of driving current by heating a toroidal plasma

    International Nuclear Information System (INIS)

    Fisch, N.J.

    1980-08-01

    In addition to the usual mechanism which utilizes the Ohmic transformer current, which is necessarily pulsed, there exist several steady-state mechanisms. Heating mechanisms which can lend themselves efficiently to continuous current generation include neutral beams, Alfven waves, ion-cyclotron waves, lower-hybrid waves and electron-cyclotron waves

  17. Radio-frequency current drive efficiency in the presence of ITBs and a dc electric field

    Science.gov (United States)

    Rosa, P. R. da S.; Mourão, R.; Ziebell, L. F.

    2009-05-01

    This paper discusses the current drive efficiency by the combined action of EC and LH waves in the presence of a dc electric field and transport, with an internal transport barrier. The transport is assumed to be produced by magnetic fluctuations. The study explores the different barrier parameters and their influence on the current drive efficiency. We study the subject by numerically solving the Fokker-Planck equation. Our main result is that the barrier depth and barrier width are important to determine the correct shape of the current density profile but not to determine the current drive efficiency, which is very little influenced by these parameters. We also found similar results for the influence of the level of magnetic fluctuations on the current density profile and on the current drive efficiency.

  18. Radio-frequency current drive efficiency in the presence of ITBs and a dc electric field

    International Nuclear Information System (INIS)

    Rosa, P.R. da S; Mourao, R.; Ziebell, L.F.

    2009-01-01

    This paper discusses the current drive efficiency by the combined action of EC and LH waves in the presence of a dc electric field and transport, with an internal transport barrier. The transport is assumed to be produced by magnetic fluctuations. The study explores the different barrier parameters and their influence on the current drive efficiency. We study the subject by numerically solving the Fokker-Planck equation. Our main result is that the barrier depth and barrier width are important to determine the correct shape of the current density profile but not to determine the current drive efficiency, which is very little influenced by these parameters. We also found similar results for the influence of the level of magnetic fluctuations on the current density profile and on the current drive efficiency.

  19. Electrical drives of the safety system in nuclear power plants

    International Nuclear Information System (INIS)

    1990-09-01

    Actuating drives, control magnets for ventilators, machine drives and control member drives are part of this rule. The rule deals with the security and technical requirements for design, construction, calculation, fabrication, assembling, testing and operation. Furthermore, it places significant demands, with regard to planning and arrangement of electrical drives, on the accompanying technical systems. Furthermore, demands are placed on the aggregate protection for electrical drives of the security systems. The signals given to these systems do not, however, have precedence over the protection signals of the reactor. The rule is identical with KTA-3504, version 9/1988. (orig./HP) [de

  20. Two-dimensional and relativistic effects in lower-hybrid current drive

    International Nuclear Information System (INIS)

    Hewett, D.; Hizanidis, K.; Krapchev, V.; Bers, A.

    1983-06-01

    We present new numerical and analytic solutions of the two-dimensional Fokker-Planck equation supplemented by a parallel quasilinear diffusion term. The results show a large enhancement of the perpendicular temperature of both the electrons resonant with the applied RF fields and the more energetic electrons in the tail. Both the RF-generated current and power dissipated are substantially increased by the perpendicular energy broadening in the resonant region. In the presence of a small DC electric field the RF current generated is very much enhanced, much more than in a simple additive fashion. In addition, we present a relativistic formulation of the two-dimensional Fokker-Planck quasilinear equation. From conservation equations, based upon this formulation, we derive the characteristics of RF current drive with energetic electrons. These show how the RF-driven current and its figure of merit (I/P/sub d/) increase with the energy of the current-carrying electrons, and that their perpendicular, random momentum must also increase

  1. Model for ICRF fast wave current drive in self-consistent MHD equilibria

    International Nuclear Information System (INIS)

    Bonoli, P.T.; Englade, R.C.; Porkolab, M.; Fenstermacher, M.E.

    1993-01-01

    Recently, a model for fast wave current drive in the ion cyclotron radio frequency (ICRF) range was incorporated into the current drive and MHD equilibrium code ACCOME. The ACCOME model combines a free boundary solution of the Grad Shafranov equation with the calculation of driven currents due to neutral beam injection, lower hybrid (LH) waves, bootstrap effects, and ICRF fast waves. The equilibrium and current drive packages iterate between each other to obtain an MHD equilibrium which is consistent with the profiles of driven current density. The ICRF current drive package combines a toroidal full-wave code (FISIC) with a parameterization of the current drive efficiency obtained from an adjoint solution of the Fokker Planck equation. The electron absorption calculation in the full-wave code properly accounts for the combined effects of electron Landau damping (ELD) and transit time magnetic pumping (TTMP), assuming a Maxwellian (or bi-Maxwellian) electron distribution function. Furthermore, the current drive efficiency includes the effects of particle trapping, momentum conserving corrections to the background Fokker Planck collision operator, and toroidally induced variations in the parallel wavenumbers of the injected ICRF waves. This model has been used to carry out detailed studies of advanced physics scenarios in the proposed Tokamak Physics Experiment (TPX). Results are shown, for example, which demonstrate the possibility of achieving stable equilibria at high beta and high bootstrap current fraction in TPX. Model results are also shown for the proposed ITER device

  2. Traveling wave antenna for fast wave heating and current drive in tokamaks

    International Nuclear Information System (INIS)

    Ikezi, H.; Phelps, D.A.

    1995-07-01

    The traveling wave antenna for heating and current drive in the ion cyclotron range of frequencies is shown theoretically to have loading and wavenumber spectrum which are largely independent of plasma conditions. These characteristics have been demonstrated in low power experiments on the DIII-D tokamak, in which a standard four-strap antenna was converted to a traveling wave antenna through use of external coupling elements. The experiments indicate that the array maintains good impedance matching without dynamic tuning during abrupt changes in the plasma, such as during L- to H-mode transitions, edge localized mode activity, and disruptions. An analytic model was developed which exhibits the features observed in the experiments. Guidelines for the design of traveling wave antennas are derived from the validated model

  3. Statistical theory of wave propagation and multipass absorption for current drive in Tokamaks

    International Nuclear Information System (INIS)

    Moreau, D.; Litaudon, X.

    1993-07-01

    The effect of ray stochasticity on the multipass absorption of lower-hybrid waves, used to drive current in tokamaks, is considered. In toroidal geometry, stochasticity arises as an intrinsic property of the Hamiltonian ray trajectories for lower-hybrid waves. Based on the wave kinetic equation, a diffusion equation is derived, with damping and sources, for the wave energy density in the stochastic layer. This equation is solved simultaneously with the electron Fokker-Planck equation to describe the quasilinear flattening of the electron distribution function and the subsequent modification of the wave damping. It is shown that the spectral gap is filled in a self-regulating manner, so that the boundaries of the diffused wave spectrum are independent of the level of ray stochastic diffusion. A simple model for the self-consistent wave spectrum and the radial profile of absorbed power is proposed

  4. Traveling-wave antenna for fast-wave heating and current drive in tokamaks

    International Nuclear Information System (INIS)

    Ikezi, H.; Phelps, D.A.

    1997-01-01

    The travelling-wave antenna for heating and current drive in the ion cyclotron range of frequencies is shown theoretically to have loading and wavenumber spectra that are largely independent of plasma conditions. These characteristics have been demonstrated in low-power experiments on the DIII-D tokamak, in which a standard four-strap antenna was converted to a traveling-wave antenna through use of external coupling elements. The experiments indicate that the array maintains good impedance matching without dynamic tuning during abrupt changes in the plasma, such as during L- to H-mode transitions, edge-localized mode activity, and disruptions. An analytic model was developed that exhibits the features observed in the experiments. Guidelines for the design of travelling-wave antennas are derived from the validated model. 11 refs., 14 figs

  5. Synergy between electron cyclotron and lower hybrid current drive on Tore Supra

    International Nuclear Information System (INIS)

    Giruzzi, G.; Artaud, J.F.; Dumont, R.J.; Imbeaux, F.; Bibet, P.; Berger-By, G.; Bouquey, F.; Clary, J.; Darbos, C.; Ekedahl, A.; Hoang, G.T.; Lennholm, M.; Maget, P.; Magne, R.; Segui, J.L.; Bruschi, A.; Granucci, G.

    2005-01-01

    Improvement (up to a factor ∼ 4) of the electron cyclotron (EC) current drive efficiency in plasmas sustained by lower hybrid (LH) current drive has been demonstrated in stationary conditions on the Tore Supra tokamak. This was made possible by feedback controlled discharges at zero loop voltage, constant plasma current and density. This effect, predicted by kinetic theory, results from a favorable interplay of the velocity space diffusions induced by the two waves: the EC wave pulling low-energy electrons out of the Maxwellian bulk, and the LH wave driving them to high parallel velocities. (author)

  6. Particle transport analysis in lower hybrid current drive discharges of JT-60U

    International Nuclear Information System (INIS)

    Nagashima, K.; Ide, S.; Naito, O.

    1996-01-01

    Particle transport is modified in lower hybrid current drive discharges of JT-60U. The density profile becomes broad during the lower hybrid wave injection and the profile change depends on the injected wave spectrum. Particle transport coefficients (diffusion coefficient and profile peaking factor) were evaluated using gas-puff modulation experiments. The diffusion coefficient in the current drive discharges is about three times larger than in the ohmic discharges. The profile peaking factor decreases in the current drive discharges and the evaluated values are consistent with the measured density profiles. (author)

  7. Current drive experiments on the HIT-II spherical torus

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Raman, R.; Nelson, B.A.; Holcomb, C.T.; McCollam, K.J.; Sieck, P.E.

    1999-01-01

    This paper describes the following new achievements from the Helicity Injected Torus (HIT) program: a) formation and sustainment of a toroidal magnetic equilibrium using coaxial helicity injection (CHI) in a conducting shell that has an L/R time much shorter than the pulse length; b) static formation of a spherical torus with plasma current over 180 kA using a transformer and feedback controlled equilibrium coils; and c) production of a current increase in a transformer produced spherical torus using CHI. (author)

  8. Current drive experiments on the HIT-II spherical torus

    International Nuclear Information System (INIS)

    Jarboe, T.; Raman, R.; Nelson, B.; Holcomb, C.T.; McCollam, K.J.; Sieck, P.E.

    2001-01-01

    This paper describes the following new achievements from the Helicity Injected Torus (HIT) program: a) formation and sustainment of a toroidal magnetic equilibrium using coaxial helicity injection (CHI) in a conducting shell that has an L/R time much shorter than the pulse length; b) static formation of a spherical torus with plasma current over 180 kA using a transformer and feedback controlled equilibrium coils; and c) production of a current increase in a transformer produced spherical torus using CHI. (author)

  9. High Field Side Lower Hybrid Current Drive Launcher Design for DIII-D

    Science.gov (United States)

    Wallace, G. M.; Leccacori, R.; Doody, J.; Vieira, R.; Shiraiwa, S.; Wukitch, S. J.; Holcomb, C.; Pinsker, R. I.

    2017-10-01

    Efficient off-axis current drive scalable to reactors is a key enabling technology for a steady-state tokamak. Simulations of DIII-D discharges have identified high performance scenarios with excellent lower hybrid (LH) wave penetration, single pass absorption and high current drive efficiency. The strategy was to adapt known launching technology utilized in previous experiments on C-Mod (poloidal splitter) and Tore Supra (bi-junction) and remain within power density limits established in JET and Tore Supra. For a 2 MW source power antenna, the launcher consists of 32 toroidal apertures and 4 poloidal rows. The aperture is 60 mm x 5 mm with 1 mm septa and the peak n| | is 2.7+/-0.2 for 90□ phasing. Eight WR187 waveguides are routed from the R-1 port down under the lower cryopump, under the existing divertor, and up the central column with the long waveguide dimension along the vacuum vessel. Above the inner strike point region, each waveguide is twisted to orient the long dimension perpendicular to the vacuum vessel and splits into 4 toroidal apertures via bi-junctions. To protect the waveguide, the inner wall radius will need to increase by 2.5 cm. RF, disruption, and thermal analysis of the latest design will be presented. Work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using User Facility DIII-D, under Award Number DE-FC02-04ER54698 and by MIT PSFC cooperative agreement DE-SC0014264.

  10. Tomography of the fast electron Bremsstrahlung emission during lower hybrid current drive on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Imbeaux, F. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France)

    1999-04-01

    A new tomography dedicated to detailed studies of the fast electron Bremsstrahlung emission in the hard X-ray (HXR) energy range between 20 and 200 keV during lower hybrid (LH) current drive experiments on the TORE SUPRA tokamak [Equipe TORE SUPRA, in Proceedings of the 15. Conference on Plasma Physics and Controlled Nuclear Fusion Research, Seville (International Atomic Energy Agency, Vienna, 1995), 1, AIEA-CN-60 / A1-5, p. 105] is presented. Radiation detection is performed by cadmium telluride(CdTe) semiconductors, which have most of the desirable features for a powerful diagnosing of magnetically confined hot plasmas - compact size, high X-ray stopping efficiency, fast timing characteristics, good energy resolution, no sensitivity to magnetic field, reasonable susceptibility to performance degradation from neutron/{gamma}-induced damages. This instrument is made of two independent cameras viewing a poloidal cross-section of the plasma, with respectively 21 and 38 detectors. A coarse spectrometry - 8 energy channels - is carried out for each chord, with an energy resolution of 20 keV. The spatial resolution in the core of the plasma is 4-5 cm, while the time sampling may be lowered down to of 2-4 ms. Powerful inversion techniques based on maximum entropy or regularization algorithms take fully advantage of the large number of line-integrated measurements for very robust estimates of the local HXR profiles as a function of time and photon energy. A detailed account of main characteristics and performances of the diagnostic is reported as well as preliminary results on LH current drive experiments. (authors)

  11. Tomography of the fast electron Bremsstrahlung emission during lower hybrid current drive on Tore Supra

    International Nuclear Information System (INIS)

    Peysson, Y.; Imbeaux, F.

    1999-04-01

    A new tomography dedicated to detailed studies of the fast electron Bremsstrahlung emission in the hard X-ray (HXR) energy range between 20 and 200 keV during lower hybrid (LH) current drive experiments on the TORE SUPRA tokamak [Equipe TORE SUPRA, in Proceedings of the 15. Conference on Plasma Physics and Controlled Nuclear Fusion Research, Seville (International Atomic Energy Agency, Vienna, 1995), 1, AIEA-CN-60 / A1-5, p. 105] is presented. Radiation detection is performed by cadmium telluride (CdTe) semiconductors, which have most of the desirable features for a powerful diagnosing of magnetically confined hot plasmas - compact size, high X-ray stopping efficiency, fast timing characteristics, good energy resolution, no sensitivity to magnetic field, reasonable susceptibility to performance degradation from neutron/γ-induced damages. This instrument is made of two independent cameras viewing a poloidal cross-section of the plasma, with respectively 21 and 38 detectors. A coarse spectrometry - 8 energy channels - is carried out for each chord, with an energy resolution of 20 keV. The spatial resolution in the core of the plasma is 4-5 cm, while the time sampling may be lowered down to of 2-4 ms. Powerful inversion techniques based on maximum entropy or regularization algorithms take fully advantage of the large number of line-integrated measurements for very robust estimates of the local HXR profiles as a function of time and photon energy. A detailed account of main characteristics and performances of the diagnostic is reported as well as preliminary results on LH current drive experiments. (authors)

  12. What drives customer choice in competitive power markets? Final report

    International Nuclear Information System (INIS)

    Cates, S.

    1998-12-01

    Understanding what drives customer choice is a crucial first step toward meeting customer needs in competitive power markets. To understand the key drivers of customer choice, Research Triangle Institute (RTI) conducted in-depth telephone interviews with 150 customers in California, Pennsylvania, and Rhode Island and with 12 energy service providers (ESPs) serving these states. Because it is a qualitative study, the number of interviews is small; however, these interviews provide a first look at actual choice behavior in the US. This study also drew on previous EPRI research on customer choice and switching intentions, the US pilot program experience, actual customer choice behavior in international markets, and lessons learned in other deregulated industries. This study identified by customer sector--residential, small and medium commercial and industrial (C/I), and large C/I--the factors customers consider when choosing an electricity supplier, customers' reasons for switching electricity supplier, and customers' reasons for not switching. One of the key findings of the study is that the key driver for switching electricity supplier is the desire to save money. In markets where energy service providers can offer significant savings, customers are switching; but, in markets where no price incentives exist, customers are reluctant to switch

  13. Review of experiments on current drive in tokamaks by means of RF waves

    International Nuclear Information System (INIS)

    Hooke, W.

    1984-01-01

    Experimental results on lower hybrid current drive in tokamak plasmas are reviewed. Pulse lengths of 3.5 seconds and currents above 400 kA have been generated at plasma densities such that the wave frequency is greater than about twice the lower hybrid frequency. Current drive ceases above a critical density, nsub(c). However, nsub(c) increases with wave frequency. So that for f = 4.6 GHz current drive has been seen at n-barsub(e) approx.= 10 14 cm -3 and a density limit has yet to be established. Evidence for a collisional scaling law for current-drive efficiency is summarized. Detailed measurements of bremsstrahlung x-rays show a distribution which is qualitatively similar to that predicted by quasilinear theory. Microwave emission at frequencies less than the plasma frequency may shed light on the current-drive mechanism. Applications of current drive including plasma and current start-up and transformer recharging are discussed. (author)

  14. Current drive and profile control in low aspect ratio tokamaks

    International Nuclear Information System (INIS)

    Chan, V.S.; Chiu, S.C.; Lin-Liu, Y.R.; Miller, R.L.; Turnbull, A.D.

    1995-07-01

    The key to the theoretically predicted high performance of a low aspect ratio tokamak (LAT) is its ability to operate at very large plasma current*I p . The plasma current at low aspect ratios follows the approximate formula: I p ∼ (5a 2 B t /Rqψ) [(1 + κ 2 )/2] [A/(A - 1)] where A quadruple-bond R/a which was derived from equilibrium studies. For constant qψ and B t , I p can increase by an order of magnitude over the case of tokamaks with A approx-gt 2.5. The large current results in a significantly enhanced β t (quadruple-bond β N I p /aB t ) possibly of order unity. It also compensates for the reduction in A to maintain the same confinement performance assuming the confinement time τ follows the generic form ∼ HI p P -1 / 2 R 3 / 2 κ 1 / 2 . The initiation and maintenance of such a large current is therefore a key issue for LATs

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

    International Nuclear Information System (INIS)

    Maebara, Sunao

    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 μP 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 μsec. 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 -6 Pam 3 /sm 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 -2 (about 2 times higher than the design value) during 1000 sec, it is found that the outgassing rate is less than 10 -5 Pam 3 /sm 2 which is low enough for an antenna material. (author)

  16. Polarization converted coupler for plasma current drive experiments

    International Nuclear Information System (INIS)

    Arai, H.; Shimizu, S.; Goto, N.

    1986-01-01

    In this paper, the authors propose the polarization converted coupler which has narrow width shape and radiates electric field perpendicular to the main toroidal magnetic field. The advantages of the polarization converted coupler are as follows: (l) The rectangular waveguide as the transmission line has the high power capability. (2) The all metal design is not damaged by the fusion neutron. (3) The characteristic of this coupler is not changed widely, since the coupler has the matching section. For example, the VSWR of its input impedance is less than 2.0 for both water and air load. The authors present characteristics of the polarization converted coupler measured by the model experiments

  17. Piezoelectric-nanowire-enabled power source for driving wireless microelectronics.

    Science.gov (United States)

    Xu, Sheng; Hansen, Benjamin J; Wang, Zhong Lin

    2010-10-19

    Harvesting energy from irregular/random mechanical actions in variable and uncontrollable environments is an effective approach for powering wireless mobile electronics to meet a wide range of applications in our daily life. Piezoelectric nanowires are robust and can be stimulated by tiny physical motions/disturbances over a range of frequencies. Here, we demonstrate the first chemical epitaxial growth of PbZr(x)Ti(1-x)O(3) (PZT) nanowire arrays at 230 °C and their application as high-output energy converters. The nanogenerators fabricated using a single array of PZT nanowires produce a peak output voltage of ~0.7 V, current density of 4 μA cm(-2) and an average power density of 2.8 mW cm(-3). The alternating current output of the nanogenerator is rectified, and the harvested energy is stored and later used to light up a commercial laser diode. This work demonstrates the feasibility of using nanogenerators for powering mobile and even personal microelectronics.

  18. A current drive by using the fast wave in frequency range higher than two timeslower hybrid resonance frequency on tokamaks

    Directory of Open Access Journals (Sweden)

    Kim Sun Ho

    2017-01-01

    Full Text Available An efficient current drive scheme in central or off-axis region is required for the steady state operation of tokamak fusion reactors. The current drive by using the fast wave in frequency range higher than two times lower hybrid resonance (w>2wlh could be such a scheme in high density, high temperature reactor-grade tokamak plasmas. First, it has relatively higher parallel electric field to the magnetic field favorable to the current generation, compared to fast waves in other frequency range. Second, it can deeply penetrate into high density plasmas compared to the slow wave in the same frequency range. Third, parasitic coupling to the slow wave can contribute also to the current drive avoiding parametric instability, thermal mode conversion and ion heating occured in the frequency range w<2wlh. In this study, the propagation boundary, accessibility, and the energy flow of the fast wave are given via cold dispersion relation and group velocity. The power absorption and current drive efficiency are discussed qualitatively through the hot dispersion relation and the polarization. Finally, those characteristics are confirmed with ray tracing code GENRAY for the KSTAR plasmas.

  19. Tidal power harnessing energy from water currents

    CERN Document Server

    Lyatkher, Victor

    2014-01-01

    As the global supply of conventional energy sources, such as fossil fuels, dwindles and becomes more and more expensive, unconventional and renewable sources of energy, such as power generation from water sources, is becoming more and more important.  Hydropower has been around for decades, but this book suggests new methods that are more cost-effective and less intrusive to the environment for creating power sources from rivers, the tides, and other sources of water.   The energy available from water currents is potentially much greater than society's needs.  Presenting a detailed discussi

  20. Advanced electron cyclotron heating and current drive experiments on the stellarator Wendelstein 7-X

    Directory of Open Access Journals (Sweden)

    Stange Torsten

    2017-01-01

    Full Text Available During the first operational phase (OP 1.1 of Wendelstein 7-X (W7-X electron cyclotron resonance heating (ECRH was the exclusive heating method and provided plasma start-up, wall conditioning, heating and current drive. Six gyrotrons were commissioned for OP1.1 and used in parallel for plasma operation with a power of up to 4.3 MW. During standard X2-heating the spatially localized power deposition with high power density allowed controlling the radial profiles of the electron temperature and the rotational transform. Even though W7-X was not fully equipped with first wall tiles and operated with a graphite limiter instead of a divertor, electron densities of n e > 3·1019 m-3 could be achieved at electron temperatures of several keV and ion temperatures above 2 keV. These plasma parameters allowed the first demonstration of a multipath O2-heating scenario, which is envisaged for safe operation near the X-cutoff-density of 1.2·1020 m-3 after full commissioning of the ECRH system in the next operation phase OP1.2.

  1. Implications of ITER requirements on R and D of RF heating and current drive systems

    International Nuclear Information System (INIS)

    Bosia, G.

    2002-01-01

    A strategic, rather than auxiliary role is assigned to H and CD systems in ITER-FEAT, as all operation phases are driven and controlled by heating and current drive (H and CD) systems. RF systems (Electron Cyclotron, Ion Cyclotron and Lower Hybrid), planned to contribute for ∼60% of ITER auxiliary power (72 MW), still require different level of pre-industrial technology development to operate in ITER at the required level of efficiency and religiosite. In this paper, RF H and CD systems technical and operational issues are reviewed and future R and D actions at CEA-Cadarache discussed, with the aim of providing a demonstration of all RF H and CD systems, within the current ITER construction time scale. The need and the economical advantage of an early on- and off- plasma design validation program for ITER-like RF devices (such as launcher and/or power sources), is also discussed with the aim of identifying and resolving operational issues. (author)

  2. 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.

  3. Prospects for the application of GaN power devices in hybrid electric vehicle drive systems

    International Nuclear Information System (INIS)

    Su, Ming; Chen, Chingchi; Rajan, Siddharth

    2013-01-01

    GaN, a wide bandgap semiconductor successfully implemented in optical and high-speed electronic devices, has gained momentum in recent years for power electronics applications. Along with rapid progress in material and device processing technologies, high-voltage transistors over 600 V have been reported by a number of teams worldwide. These advances make GaN highly attractive for the growing market of electrified vehicles, which currently employ bipolar silicon devices in the 600–1200 V class for the traction inverter. However, to capture this billion-dollar power market, GaN has to compete with existing IGBT products and deliver higher performance at comparable or lower cost. This paper reviews key achievements made by the GaN semiconductor industry, requirements of the automotive electric drive system and remaining challenges for GaN power devices to fit in the inverter application of hybrid vehicles. (invited review)

  4. Prospects for the application of GaN power devices in hybrid electric vehicle drive systems

    Science.gov (United States)

    Su, Ming; Chen, Chingchi; Rajan, Siddharth

    2013-07-01

    GaN, a wide bandgap semiconductor successfully implemented in optical and high-speed electronic devices, has gained momentum in recent years for power electronics applications. Along with rapid progress in material and device processing technologies, high-voltage transistors over 600 V have been reported by a number of teams worldwide. These advances make GaN highly attractive for the growing market of electrified vehicles, which currently employ bipolar silicon devices in the 600-1200 V class for the traction inverter. However, to capture this billion-dollar power market, GaN has to compete with existing IGBT products and deliver higher performance at comparable or lower cost. This paper reviews key achievements made by the GaN semiconductor industry, requirements of the automotive electric drive system and remaining challenges for GaN power devices to fit in the inverter application of hybrid vehicles.

  5. Current fusion power plant design concepts

    International Nuclear Information System (INIS)

    Gore, B.F.; Murphy, E.S.

    1976-09-01

    Nine current U.S. designs for fusion power plants are described in this document. Summary tabulations include a tenth concept, for which the design document was unavailable during preparation of the descriptions. The information contained in the descriptions was used to define an envelope of fusion power plant characteristics which formed the basis for definition of reference first commercial fusion power plant design. A brief prose summary of primary plant features introduces each of the descriptions contained in the body of this document. In addition, summary tables are presented. These tables summarize in side-by-side fashion, plant parameters, processes, combinations of materials used, requirements for construction materials, requirements for replacement materials during operation, and production of wastes

  6. The essential theory of fast wave current drive with full wave method

    International Nuclear Information System (INIS)

    Liu Yan; Gong Xueyu; Yang Lei; Yin Chenyan; Yin Lan

    2007-01-01

    The full wave numerical method is developed for analyzing fast wave current drive in the range of ion cyclotron waves in tokamak plasmas, taking into account finite larmor radius effects and parallel dispersion. the physical model, the dispersion relation on the assumption of Finite Larmor Radius (FLR) effects and the form of full wave be used for computer simulation are developed. All of the work will contribute to further study of fast wave current drive. (authors)

  7. Electron Cyclotron Current Drive Compensation of the Bootstrap Current in Quasi-symmetric Reactor Devices

    International Nuclear Information System (INIS)

    Margalet, S. D.; Cooper, W. A.; Volpe, F.; Castejon, F.

    2005-01-01

    In magnetic confinement devices, the inhomogeneity of the confining magnetic field along a magnetic field line generates the trapping of particles within local magnetic wells. One of the consequences of the trapped particles is the generation of a current, known as the bootstrap current (BC), whose direction depends on the nature of the magnetic trapping. The BC provides an extra contribution to the poloidal component of the confining magnetic field. The variation of the poloidal component produces the alteration of the winding of the magnetic field lines around the flux surfaces quantified by the rotational transform. When reaches low rational values, it can trigger the generation of ideal MHD instabilities. Therefore, the BC may be responsible for the destabilisation of the configuration [1]. Having established the potentially dangerous implication of the BC, principally, in reactor prototypes, a method to compensate its harmful effects is proposed. It consists of the modelling of the current driven by externally launched ECWs within the plasma to compensate the effects of the BC. This method is flexible enough to allow the identification of the appropriate scenarios in which to generate the required CD depending on the nature of the confining magnetic field and the specific plasma parameters of the configuration. Both the BC and the CD calculations are included in a self-consistent scheme which leads to the computation of a stable BC+CD-consistent MHD equilibrium. This procedure is applied in this paper to simulate the required CD to stabilise a QAS and a QHS reactor prototypes. The estimation of the input power required and the effect of the driven current on the final equilibrium of the system is performed for several relevant scenarios and wave polarisations providing various options of stabilising driven currents. (Author)

  8. High-efficiency toroidal current drive using low-phase-velocity kinetic Alfven waves

    International Nuclear Information System (INIS)

    Puri, S.

    1991-09-01

    A method for obtaining efficient current drive in Tokamaks using low-phase-velocity (v ρ = ω/K parallel ∝ 0.1v te ) kinetic Alfen wave is proposed. The wave momentum, imparted primarily to the trapped electrons by Landau damping, is stored as the canonical angular momentum via the Ware pinch. In steady state, collisions restore the pinched electrons to their original phase-space configuration, in the process releasing the stored canonical angular momentum to the background ions and electrons in proportion to the respective collision frequencies. Despite the loss of a part of the original impulse to the plasma ions, well over half the wave momentum is ultimately delivered to the bulk-plasma electrons, resulting in an efficient current drive. A normalized current-drive efficiency γ = R 0 20 > I/P ∝ 2 would be feasible using the subthermal kinetic-Alfen-wave current drive in a Tokamak of reactor parameters. Optimum antenna loading conditions are described. The problem of accessibility is discussed. In an elongated, high-β plasma with a density dependence n e ∝ (1-ρ 2 ) Χn , accessibility is restricted to ρ > or approx. 3/(4A Χn ), where A is the aspect ratio. For current drive at still lower values of ρ, operation in conjunction with fast-wave current drive is suggested. (orig.)

  9. Comparison between the electron cyclotron current drive experiments on DIII-D and predictions for T-10

    International Nuclear Information System (INIS)

    Lohr, J.; Harvey, R.W.; Luce, T.C.; Matsuda, Kyoko; Moeller, C.P.; Petty, C.C.; Prater, R.; James, R.A.; Giruzzi, G.; Gorelov, Y.; DeHaas, J.

    1990-11-01

    Electron cyclotron current drive has been demonstrated on the DIII-D tokamak in an experiment in which ∼1 MW of microwave power generated ∼50 kA of non-inductive current. The rf-generated portion was about 15% of the total current. On the T-10 tokamak, more than 3 MW of microwave power will be available for current generation, providing the possibility that all the plasma current could be maintained by this method. Fokker-Planck calculations using the code CQL3D and ray tracing calculations using TORAY have been performed to model both experiments. For DIII-D the agreement between the calculations and measurements is good, producing confidence in the validity of the computational models. The same calculations using the T-10 geometry predict that for n e (0) ∼ 1.8 x 10 13 cm -3 , and T e (0) ∼ 7 keV, 1.2 MW, that is, the power available from only three gyrotrons, could generate as much as 150 kA of non-inductive current. Parameter space scans in which temperature, density and resonance location were varied have been performed to indicate the current drive expected under different experimental conditions. The residual dc electric field was considered in the DIII-D analysis because of its nonlinear effect on the electron distribution, which complicates the interpretation of the results. A 110 GHz ECH system is being installed on DIII-D. Initial operations, planned for late 1991, will use four gyrotrons with 500 kW each and 10 second output pulses. Injection will be from the low field side from launchers which can be steered to heat at the desired location. These launchers, two of which are presently installed, are set at 20 degrees to the radial and rf current drive studies are planned for the initial operation. 8 refs., 10 figs

  10. 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

    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...

  11. The effect of non-inductive current drive on tokamak transport

    International Nuclear Information System (INIS)

    Helander, P; Akers, R J; Valovic, M; Peysson, Y

    2005-01-01

    Non-inductive current drive causes cross-field neoclassical transport in a tokamak, in much the same way that the toroidal electric field used to drive the plasma current produces the so-called Ware pinch. This transport can be either inwards or outwards, depending on the current drive mechanism, and can be either larger or smaller than the analogous Ware pinch. A Green's function formalism is used to calculate the transport produced by wave-driven currents, which is found to be inwards for electron-cyclotron and lower-hybrid current drive. Its magnitude is proportional to the collisionality of the current-carrying electrons and therefore smaller than the Ware pinch when the resonant electrons are suprathermal. In contrast, neutral-beam current drive produces outward particle transport when the beams are injected in the same toroidal direction as the plasma current, and inward particle transport otherwise. This transport is somewhat larger than the corresponding Ware pinch. Together, they may explain an observation made on several tokamaks over the years, most recently on MAST, that density profiles tend to be more peaked during counter-injection

  12. 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.

  13. Fast wave and electron cyclotron current drive in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Petty, C.C.; Pinsker, R.I.; Austin, M.E.

    1995-01-01

    The non-inductive current drive from directional fast Alfven and electron cyclotron waves was measured in the DIII-D tokamak in order to demonstrate these forms of radiofrequency (RF) current drive and to compare the measured efficiencies with theoretical expectations. The fast wave frequency was 8 times the deuterium cyclotron frequency at the plasma centre, while the electron cyclotron wave was at twice the electron cyclotron frequency. Complete non-inductive current drive was achieved using a combination of fast wave current drive (FWCD) and electron cyclotron current drive (ECCD) in discharges for which the total plasma current was inductively ramped down from 400 to 170 kA. For steady current discharges, an analysis of the loop voltage revealed up to 195 kA of a non-inductive current (out of 310 kA) during combined electron cyclotron and fast wave injection, with a maximum of 110 kA of FWCD and 80 kA of ECCD achieved (not simultaneously). The peakedness of the current profile increased with RF current drive, indicating that the driven current was centrally localized. The FWCD efficiency increased linearly with the central electron temperature as expected; however, the FWCD was severely degraded in low current discharges owing to incomplete fast wave absorption. The measured FWCD agreed with the predictions of a ray tracing code only when a parasitic loss of 4% per pass was included in the modelling along with multiple pass absorption. Enhancement of the second harmonic ECCD efficiency by the toroidal electric field was observed experimentally. The measured ECCD was in good agreement with Fokker-Planck code predictions. (author). 41 refs, 13 figs, 1 tab

  14. Phased-array antenna system for electron Bernstein wave heating and current drive experiments in QUEST

    International Nuclear Information System (INIS)

    Idei, H.; Sakaguchi, M.; Kalinnikova, E.I.

    2010-11-01

    The phased-array antenna system for Electron Bernstein Wave Heating and Current Drive (EBWH/CD) experiments has been developed in the QUEST. The antenna was designed to excite a pure O-mode wave in the oblique injection for the EBWH/CD experiments, and was tested at a low power level. The measured two orthogonal fields were in excellent agreements with the fields evaluated by a developed Kirchhoff code. The heat load and thermal stress in CW 200 kW operation were analyzed with finite element codes. The phased array has been fast scanned [∼10 4 degree/s] to control the incident polarization and angle to follow time evolutions of the plasma current and density. The RF startup and sustainment experiments were conducted using the developed antenna system. The plasma current (< ∼15 kA) with an aspect ratio of 1.5 was started up and sustained by only RF injection. The long pulse discharge of 10 kA was attained for 40 s with the 30 kW injection. (author)

  15. Determination of power and moment on shaft of special asynchronous electric drives

    Science.gov (United States)

    Karandey, V. Yu; Popov, B. K.; Popova, O. B.; Afanasyev, V. L.

    2018-03-01

    In the article, questions and tasks of determination of power and the moment on a shaft of special asynchronous electric drives are considered. Use of special asynchronous electric drives in mechanical engineering and other industries is relevant. The considered types of electric drives possess the improved mass-dimensional indicators in comparison with singleengine systems. Also these types of electric drives have constructive advantages; the improved characteristics allow one to realize the technological process. But creation and design of new electric drives demands adjustment of existing or development of new methods and approaches of calculation of parameters. Determination of power and the moment on a shaft of special asynchronous electric drives is the main objective during design of electric drives. This task has been solved based on a method of electromechanical transformation of energy.

  16. Electron cyclotron current drive predictions for ITER: Comparison of different models

    International Nuclear Information System (INIS)

    Marushchenko, N.B.; Maassberg, H.; Beidler, C.D.; Turkin, Yu.

    2007-01-01

    Full text: Due to its high localization and operational flexibility, Electron Cyclotron Current Drive (ECCD) is envisaged for stabilizing the Neoclassical Tearing Mode (NTM) in tokamaks and correcting the rotational transform profile in stellarators. While the spatial location of the electron cyclotron resonant interaction is usually calculated by the ray-tracing technique, numerical tools for calculating the ECCD efficiency are not so common. Two different methods are often applied: i) direct calculation by Fokker-Planck modelling, and ii) by the adjoint approach technique. In the present report we analyze and compare different models used in the adjoint approach technique from the point of view of ITER applications. The numerical tools for calculating the ECCD efficiency developed to date do not completely cover the range of collisional regimes for the electrons involved in the current drive. Only two opposite limits are well developed, collisional and collisionless. Nevertheless, for the densities and temperatures expected for ECCD application in ITER, the collisionless limit model (with trapped particles taken into account) is quite suitable. We analyze the requisite ECCD scenarios with help of the new ray tracing code TRAVIS with the adjoint approach implemented. The (adjoint) Green's function applied for the current drive calculations is formulated with momentum conservation taken into account; this is especially important and even crucial for scenarios, in which mainly bulk electrons are responsible for absorption of the RF power. For comparison, the most common 'high speed limit' model in which the collision operator neglects the integral part and which is approximated by terms valid only for the tail electrons, produces an ECCD efficiency which is an underestimate for some cases by a factor of about 2. In order to select the appropriate model, a rough criterion of 'high speed limit' model applicability is formulated. The results are verified also by

  17. A New Cost-Effective Multi-Drive Solution based on a Two-Stage Direct Power Electronic Conversion Topology

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2002-01-01

    of a protection circuit involving twelve diodes with full voltage/current ratings used only during faulty situations, makes this topology not so attractive. Lately, two stage Direct Power Electronic Conversion (DPEC) topologies have been proposed, providing similar functionality as a matrix converter but allowing...... shared by many loads, making this topology more cost effective. The functionality of the proposed two-stage multi-drive direct power electronic conversion topology is validated by experiments on a realistic laboratory prototype....

  18. Non-inductive current drive via helicity injection by Alfven waves in low-aspect-ratio tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Cuperman, S.; Bruma, C.; Komoshvili, K. [Tel Aviv Univ. (Israel). Sackler Faculty of Exact Sciences

    1996-08-01

    A theoretical investigation of radio-frequency (RF) current drive via helicity injection in low aspect ratio tokamaks is carried out. A current-carrying cylindrical plasma surrounded by a helical sheet-current antenna and situated inside a perfectly conducting shell is considered. Toroidal features of low-aspect-ratio tokamaks are simulated by incorporating the following effects: (i) arbitrarily small aspect ratio, R{sub O}/a ``identical to`` 1/{epsilon}; (ii) strongly sheared equilibrium magnetic field; and (iii) relatively large poloidal component of the equilibrium magnetic field. This study concentrates on the Alfven continuum, i.e. the case in which the wave frequency satisfies the condition {l_brace}{omega}{sub Alf}({tau}){r_brace}{sub min}{r_brace} {<=} {omega} {<=} {l_brace}{omega}{sub Alf}({tau}){r_brace}{sub max}, where {omega}{sub Alf}({tau}) ``identical to`` {omega}{sub Alf}[n({tau}), B{sub O}({tau})] is an eigenfrequency of the shear Alfven wave (SAW). Thus, using low-{beta} magnetohydrodynamics, the wave equation with correct boundary (matching) conditions is solved, the RF field components are found, and subsequently current drive, power deposition and efficiency are computed. The results of our investigation clearly demonstrate the possibility of generation of RF-driven currents via helicity injection by Alfven waves in low-aspect-ratio tokamaks, in the SAW mode. A special algorithm is developed that enables one to select the antenna parameters providing optimal current drive efficiency. (Author).

  19. Current Challenges in the First Principle Quantitative Modelling of the Lower Hybrid Current Drive in Tokamaks

    Science.gov (United States)

    Peysson, Y.; Bonoli, P. T.; Chen, J.; Garofalo, A.; Hillairet, J.; Li, M.; Qian, J.; Shiraiwa, S.; Decker, J.; Ding, B. J.; Ekedahl, A.; Goniche, M.; Zhai, X.

    2017-10-01

    The Lower Hybrid (LH) wave is widely used in existing tokamaks for tailoring current density profile or extending pulse duration to steady-state regimes. Its high efficiency makes it particularly attractive for a fusion reactor, leading to consider it for this purpose in ITER tokamak. Nevertheless, if basics of the LH wave in tokamak plasma are well known, quantitative modeling of experimental observations based on first principles remains a highly challenging exercise, despite considerable numerical efforts achieved so far. In this context, a rigorous methodology must be carried out in the simulations to identify the minimum number of physical mechanisms that must be considered to reproduce experimental shot to shot observations and also scalings (density, power spectrum). Based on recent simulations carried out for EAST, Alcator C-Mod and Tore Supra tokamaks, the state of the art in LH modeling is reviewed. The capability of fast electron bremsstrahlung, internal inductance li and LH driven current at zero loop voltage to constrain all together LH simulations is discussed, as well as the needs of further improvements (diagnostics, codes, LH model), for robust interpretative and predictive simulations.

  20. Modeling of LH current drive in self-consistent elongated tokamak MHD equilibria

    International Nuclear Information System (INIS)

    Blackfield, D.T.; Devoto, R.S.; Fenstermacher, M.E.; Bonoli, P.T.; Porkolab, M.; Yugo, J.

    1989-01-01

    Calculations of non-inductive current drive typically have been used with model MHD equilibria which are independently generated from an assumed toroidal current profile or from a fit to an experiment. Such a method can lead to serious errors since the driven current can dramatically alter the equilibrium and changes in the equilibrium B-fields can dramatically alter the current drive. The latter effect is quite pronounced in LH current drive where the ray trajectories are sensitive to the local values of the magnetic shear and the density gradient. In order to overcome these problems, we have modified a LH simulation code to accommodate elongated plasmas with numerically generated equilibria. The new LH module has been added to the ACCOME code which solves for current drive by neutral beams, electric fields, and bootstrap effects in a self-consistent 2-D equilibrium. We briefly describe the model in the next section and then present results of a study of LH current drive in ITER. 2 refs., 6 figs., 2 tabs

  1. Addressing Circuitous Currents MVDC Power Systems Protection

    Science.gov (United States)

    2017-12-31

    Addressing Circuitous Currents MVDC Power Systems Protection 5b. GRANT NUMBER N00014-16-1-3113 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR($) Sd. PROJECT NUMBER...efficiency. A challenge with DC distribution is electrical protection . Z-source DC breakers alt! an pti n b&i g cvr.sidcrcd and this w rk ~xplores...zonal distribution, electric ship 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a. REPORT b. ABSTRACT c. THIS PAGE ABSTRACT u u u uu 18. NUMBER

  2. FEATURES AND PROSPECTS FOR USE OF WIND-POWERED DRIVE ON AGRICULTURAL AIRPLANE

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The article deals with the wind-powered drive location and functioning pecularities of agricultural airplane special equipment. The data on the advantages and prospects of the use of the wind-powered drive on agricultural aircraft as well as the experimental and analytical data on discontinuity of the wind stream in the zone of the wind-powered drive installa- and parameters of its operation at aerial spraying on the example of specially equipped An-2 are presented. A mathe- matical model of a wind propeller in discontinuous wind stream is developed. Software package to comprehensively assess wind-powered drive conditions and performance indicators is generated and tested taking into account experimental data, as well as airplane performance and flight modes. The typical data on the wind propeller and the wind-powered drive in the spraying process are received; specific features of the dynamics at the wind-powered drive turning-on and the wind propel- ler rotation at zero load are determined and the data on the wind-propeller blades load imbalance at spraying and transient processes are defined. The author made a quantitative estimation of how the standard change of flight parameters and the operation of the aircraft power plant at spraying influence on the factors of wind-powered drive operation and working liq- uids suppey. The main tendencies, qualitative and quantitative aspects of a wind-powered drive use are defined when per- forming aerial works and the proposals and recommendations for improving and using it in the future are made. The find- ings of the work can be used in the wind-powered drive of agricultural airplane special equipment designing and moderni- zation and drilling of the operational and technological procedures of aerial works performance in agriculture and forestry.

  3. Plasma response to sustainment with imposed-dynamo current drive in HIT-SI and HIT-SI3

    Science.gov (United States)

    Hossack, A. C.; Jarboe, T. R.; Chandra, R. N.; Morgan, K. D.; Sutherland, D. A.; Penna, J. M.; Everson, C. J.; Nelson, B. A.

    2017-07-01

    The helicity injected torus—steady inductive (HIT-SI) program studies efficient, steady-state current drive for magnetic confinement plasmas using a novel experimental method. Stable, high-beta spheromaks have been sustained using steady, inductive current drive. Externally induced loop voltage and magnetic flux are oscillated together so that helicity and power injection are always positive, sustaining the edge plasma current indefinitely. Imposed-dynamo current drive (IDCD) theory further shows that the entire plasma current is sustained. The method is ideal for low aspect ratio, toroidal geometries with closed flux surfaces. Experimental studies of spheromak plasmas sustained with IDCD have shown stable magnetic profiles with evidence of pressure confinement. New measurements show coherent motion of a stable spheromak in response to the imposed perturbations. On the original device two helicity injectors were mounted on either side of the spheromak and the injected mode spectrum was predominantly n  =  1. Coherent, rigid motion indicates that the spheromak is stable and a lack of plasma-generated n  =  1 energy indicates that the maximum q is maintained below 1 during sustainment. Results from the HIT-SI3 device are also presented. Three inductive helicity injectors are mounted on one side of the spheromak flux conserver. Varying the relative injector phasing changes the injected mode spectrum which includes n  =  2, 3, and higher modes.

  4. A Novel Maximum Power Point Tracking Control for Permanent Magnet Direct Drive Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2012-05-01

    Full Text Available This paper proposes a novel optimal current given (OCG maximum power point tracking (MPPT control strategy based on the theory of power feedback and hill climb searching (HCS for a permanent magnet direct drive wind energy conversion system (WECS. The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG MPPT control strategy is first carried out by simulation, then an experimental platform based on the dSPACE1103 controller is built and a 5.5 kW permanent magnet synchronous generator (PMSG is tested. Furthermore, the proposed method is compared experimentally with the traditional optimum tip speed ratio (TSR MPPT control. The experiments verify the effectiveness of the proposed OCG MPPT strategy and demonstrate its better performance than the traditional TSR MPPT control.

  5. Modeling of lower hybrid current drive (LHCD) and parametric instability (PI) for high performance internal transport barriers (ITBs)

    International Nuclear Information System (INIS)

    Cesario, R.; Cardinali, A.; Castaldo, C.; Paoletti, F.; Challis, C.; Mailloux, J.; Mazon, D.

    2003-01-01

    ITBs (internal transport barrier) with high performance in time duration (4 seconds) were produced at Jet in plasma discharges operating at the plasma current of 2,4 MA and toroidal magnetic field of 3,45 T using lower hybrid (LH) radiofrequency power (2,3 MW) for heating and current drive. The first results of the modeling devoted to calculate the LH power deposition and current density profiles for ITB plasmas are presented. The LH power density profile was first calculated considering the nominal LH power n / spectrum launched by the antenna, a substantially centrally deposition is obtained, many passes (> 10) are necessary for producing a significant fraction of the coupled LH power to be absorbed. In a second step some broadening (20%) of the launched n / power spectrum was considered to simulate the effect of a non-linear wave scattering. Most of the LH power is deposited at the first pass, mainly in the outer half of plasma. The simulation gives a moderate amount (60%) of non-inductive current, including 30% of LHCD fraction. The q-profiles from polarization and from MSE (motional Stark effect) at the beginning and during the main heating phase were analysed. Non-linear plasma edge phenomena allow propagation of some LH power with large n / . Such effect should be retained for a realistic LHCD modeling of ITB plasmas. The consequent enhanced off-axis LHCD is consistent with the observed large ITBs and the obtained large region with low magnetic shear. The LH power might provide a powerful tool for controlling the q-profile for ITB at high plasma current, for potential application to the advanced tokamak regimes

  6. Modeling of lower hybrid current drive (LHCD) and parametric instability (PI) for high performance internal transport barriers (ITBs)

    Energy Technology Data Exchange (ETDEWEB)

    Cesario, R.; Cardinali, A.; Castaldo, C. [Associazione Euratom-ENEA sulla Fusione, Centro Ricerche Frascadi (Italy); Paoletti, F. [PPPL Pinceton (United States); Challis, C.; Mailloux, J. [Euratom-UKAEA fusion association, Culham Science Centre, Abingdon, Oxfordshire, OX (United Kingdom); Mazon, D. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France)

    2003-07-01

    ITBs (internal transport barrier) with high performance in time duration (4 seconds) were produced at Jet in plasma discharges operating at the plasma current of 2,4 MA and toroidal magnetic field of 3,45 T using lower hybrid (LH) radiofrequency power (2,3 MW) for heating and current drive. The first results of the modeling devoted to calculate the LH power deposition and current density profiles for ITB plasmas are presented. The LH power density profile was first calculated considering the nominal LH power n{sub /} spectrum launched by the antenna, a substantially centrally deposition is obtained, many passes (> 10) are necessary for producing a significant fraction of the coupled LH power to be absorbed. In a second step some broadening (20%) of the launched n{sub /} power spectrum was considered to simulate the effect of a non-linear wave scattering. Most of the LH power is deposited at the first pass, mainly in the outer half of plasma. The simulation gives a moderate amount (60%) of non-inductive current, including 30% of LHCD fraction. The q-profiles from polarization and from MSE (motional Stark effect) at the beginning and during the main heating phase were analysed. Non-linear plasma edge phenomena allow propagation of some LH power with large n{sub /}. Such effect should be retained for a realistic LHCD modeling of ITB plasmas. The consequent enhanced off-axis LHCD is consistent with the observed large ITBs and the obtained large region with low magnetic shear. The LH power might provide a powerful tool for controlling the q-profile for ITB at high plasma current, for potential application to the advanced tokamak regimes.

  7. First lower hybrid current drive experiments at 3.7 GHz in Tore Supra

    International Nuclear Information System (INIS)

    Tonon, G.; Goniche, M.; Moreau, D.

    1989-01-01

    The results of electromagnetic waves injection in the Tore Supra plasma, at a frequency of 3.7 GHz, are reported. The process is applied for current generation and plasma heating, through Landau damping on the electron population. The experimental set-up is described. The lower hybrid current drive experiments in Tore Supra are carried out under the following conditions: major and minor radii of the plasma are respectively 2.37 m and 0.77 m and the toroidal magnetic field is 1.8 Teslas. A multijunction-grill composed of 128 waveguides is applied. Up to 1.25 MW of rf power is injected in Tore Supra, after less than 30 plasma shots. The results lead to the conclusion that the coupling, not yet optimized, is good enough for safe klystron operation with no circulator. The measured value RIp P RF -1 (δV L /V L ) obtained on Tore Supra (Bt = 1.8 T) is closed to one observed on PETULA-B (Bt = 2.75 T) at the same frequency and density

  8. A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks

    Science.gov (United States)

    Urban, Jakub; Decker, Joan; Peysson, Yves; Preinhaelter, Josef; Shevchenko, Vladimir; Taylor, Gary; Vahala, Linda; Vahala, George

    2011-08-01

    The electron Bernstein wave (EBW) is typically the only wave in the electron cyclotron (EC) range that can be applied in spherical tokamaks for heating and current drive (H&CD). Spherical tokamaks (STs) operate generally in high-β regimes, in which the usual EC O- and X-modes are cut off. In this case, EBWs seem to be the only option that can provide features similar to the EC waves—controllable localized H&CD that can be used for core plasma heating as well as for accurate plasma stabilization. The EBW is a quasi-electrostatic wave that can be excited by mode conversion from a suitably launched O- or X-mode; its propagation further inside the plasma is strongly influenced by the plasma parameters. These rather awkward properties make its application somewhat more difficult. In this paper we perform an extensive numerical study of EBW H&CD performance in four typical ST plasmas (NSTX L- and H-mode, MAST Upgrade, NHTX). Coupled ray-tracing (AMR) and Fokker-Planck (LUKE) codes are employed to simulate EBWs of varying frequencies and launch conditions, which are the fundamental EBW parameters that can be chosen and controlled. Our results indicate that an efficient and universal EBW H&CD system is indeed viable. In particular, power can be deposited and current reasonably efficiently driven across the whole plasma radius. Such a system could be controlled by a suitably chosen launching antenna vertical position and would also be sufficiently robust.

  9. An investigation of r.f. travelling wave current drive using the model

    International Nuclear Information System (INIS)

    Bertram, W.K.

    1988-01-01

    Previous experimental investigations in the use of travelling r.f. waves to drive steady toroidal currents in a toroidal plasma have shown that I t , the amount of current driven, is strongly dependent on the ratio of the static toroidal magnetic field B z , to the strength of the r.f. magnetic field B ω . This dependence is characterised by an initial increase and subsequent decrease of I t when B t /B ω increases. It is shown that this observed behaviour is entirely consistent with the behaviour predicted by the current drive model. Results from numerical computations using the model show good quantitative agreement with the published experimental results

  10. Fast wave current drive on ITER in the presence of energetic alphas

    International Nuclear Information System (INIS)

    Mau, T.K.

    1989-01-01

    The impact of energetic alpha particle wave absorption on the range of frequencies for efficient fast wave current drive in an ITER-like fusion reactor core is investigated. The energetic alpha damping decrement is calculated, using an exact slowing down distribution function, and compared to electron and fuel ion damping over a wide range of frequencies. A combination of strong alpha damping and edge electron absorption in the higher ion harmonic regime limits efficient core fast wave current drive to the lower harmonics (1=2.3). However, high frequency fast waves may be employed to generate current in the outer plasma region. 11 refs., 7 figs

  11. Modeling of the electron distribution based on bremsstrahlung emission during lower hybrid current drive on PLT

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, J.E.; von Goeler, S.; Bernabei, S.; Bitter, M.; Chu, T.K.; Efthimion, P.; Fisch, N.; Hooke, W.; Hosea, J.; Jobes, F.

    1985-03-01

    Lower hybrid current drive requires the generation of a high energy electron tail anisotropic in velocity. Measurements of bremsstrahlung emission produced by this tail are compared with the calculated emission from reasonable model distributions. The physical basis and the sensitivity of this modeling process are described and the plasma properties of current driven discharges which can be derived from the model are discussed.

  12. Modeling of the electron distribution based on bremsstrahlung emission during lower hybrid current drive on PLT

    International Nuclear Information System (INIS)

    Stevens, J.E.; von Goeler, S.; Bernabei, S.

    1985-03-01

    Lower hybrid current drive requires the generation of a high energy electron tail anisotropic in velocity. Measurements of bremsstrahlung emission produced by this tail are compared with the calculated emission from reasonable model distributions. The physical basis and the sensitivity of this modeling process are described and the plasma properties of current driven discharges which can be derived from the model are discussed

  13. Novel Straight and Circular Road Driving Control of Electric Power Assisted Wheelchair Based on Fuzzy Algorithm

    Science.gov (United States)

    Seki, Hirokazu; Tadakuma, Susumu

    This paper describes a novel straight and circular road driving control scheme for electric power assisted wheelchairs. “Electric power assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of the straight and circular road driving must be further improved because the two wheels drive independently. This paper proposes a novel driving control scheme based on fuzzy algorithm to realize the stable and reliable driving on straight and circular roads. The suitable assisted torque of the right and left wheels is determined by fuzzy algorithm based on the posture angular velocity of the wheelchair and the human input torque proportion of the right and left wheels. Some experiments on the practical roads show the effectiveness of the proposed control system.

  14. 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)

  15. Analysis of the Fuel Efficiency of a Hybrid Electric Drive with an Electric Power Splitter

    OpenAIRE

    D. Čundev

    2008-01-01

    This paper presents the results of an analysis of the fuel efficiency of a hybrid electric car drive, with an electric power splitter based on a double rotor synchronous permanent magnet generator. The results have been obtained through a precisely determined mathematical model and by simulating the characteristics of all essential values for the entire drive. This work is related to the experimental working stand for electric and hybrid car drive research, which has been developed at the Fac...

  16. Driving Control for Electric Power Assisted Wheelchair Based on Regenerative Brake

    Science.gov (United States)

    Seki, Hirokazu; Takahashi, Kazuki; Tadakuma, Susumu

    This paper describes a novel safety driving control scheme for electric power assisted wheelchairs based on the regenerative braking system. “Electric power assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the safe and secure driving performance especially on downhill roads must be further improved because electric power assisted wheelchairs have no braking devices. The proposed control system automatically switches the driving mode, from “assisting mode” to “braking mode”, based on the wheelchair's velocity and the declined angle and smoothly suppresses the wheelchair's acceleration based on variable duty ratio control in order to realize the safety driving and to improve the ride quality. Some experiments on the practical roads and subjective evaluation show the effectiveness of the proposed control system.

  17. U.S.-Japan workshop on 'RF heating and current drive in confinement systems tokamaks'

    International Nuclear Information System (INIS)

    1992-01-01

    The workshop was attended by 8 US scientists and 30 Japanese scientists. The agenda was divided into 2 1/2 days of presentation, 1/2 day group discussions and 1/2 day summary session. There were 10 papers on rf physics, technologies and applications; 6 papers on new concepts, helicity injection and transport; and 6 papers on heating/current drive and scrape-off-layer/divertor conditions. The wide range of topics discussed is an indication of the impressive growth, both in depth and breadth, of the US-Japan workshop in RF Heating and Current Drive. It also benefitted by being combined with the new current drive concepts workshops and the active participation of JAERI scientists. (J.P.N.)

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

    International Nuclear Information System (INIS)

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

    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 D α 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 D 2 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. (physics of gases, plasmas, and electric discharges)

  19. Analytical calculation of current drive synergy between LH and EC waves

    International Nuclear Information System (INIS)

    Dumont, R.; Giruzzi, G.

    2001-01-01

    An analytical model for the evaluation of electron cyclotron current drive efficiency improvement in lower hybrid current drive regimes is presented. The adjoint equation is written and solved by a perturbation treatment, allowing to derive a response function including both collisional and lower hybrid effects, in the limit where the former still dominate. This allows an analytical demonstration of the current drive synergy effects, previously found by numerical solutions of the kinetic equation. The model is especially useful for the determination of appropriate wave parameters optimizing this synergy effect, such as the EC launching angles suitable for a given LH target plasma. Under these conditions, it is shown that a significant improvement of the ECCD efficiency can be obtained

  20. Numerical calculation of high frequency fast wave current drive in a reactor grade tokamak

    International Nuclear Information System (INIS)

    Ushigusa, Kenkichi; Hamamatsu, Kiyotaka

    1988-02-01

    A fast wave current drive with a high frequency is estimated for a reactor grade tokamak by the ray tracing and the quasi-linear Fokker-Planck calculations with an assumption of single path absorption. The fast wave can drive RF current with the drive efficiency of η CD = n-bar e (10 19 m -3 )I RC (A)R(m)/P RF (W) ∼ 3.0 when the wave frequency is selected to be f/f ci > 7. A sharp wave spectrum and a ph|| >/υ Te ∼ 3.0 are required to obtain a good efficiency. A center peaked RF current profile can be formed with an appropriate wave spectrum even in the high temperature plasma. (author)

  1. Study of fast wave current drive in a KT-2 tokamak plasma

    International Nuclear Information System (INIS)

    Hong, B.G.; Hamamatsu, Kiyotaka

    1996-02-01

    Global analysis of fast wave current drive in a KT-2 tokamak plasma is performed by using the code, TASKW1, developed by JAERI and Okayama University (Dr. Fukuyama), which solves the kinetic wave equation in a one dimensional slab geometry. A phase-shifted antenna array is used to inject toroidal momentum to electrons. To find guidelines of optimum antenna design for efficient current drive, accessibility conditions are derived. The dependence of the current drive efficiency on launching conditions such as the total number of antennas, phase and spacing is investigated for two cases of wave frequency; f=30 MHz ( cH ) and f=225 MHz (=5f cH ). (author)

  2. Efficiency of LH current drive in tokamaks featuring an internal transport barrier

    International Nuclear Information System (INIS)

    Oliveira, C I de; Ziebell, L F; Rosa, P R da S

    2005-01-01

    In this paper, we study the effects of the occurrence of radial transport of particles in a tokamak on the efficiency of the current drive by lower hybrid (LH) waves, in the presence of an internal transport barrier. The results are obtained by numerical solution of the Fokker-Planck equation which rules the evolution of the electron distribution function. We assume that the radial transport of particles can be due to magnetic or electrostatic fluctuations. In both cases the efficiency of the current drive is shown to increase with the increase of the fluctuations that originate the transport. The dependence of the current drive efficiency on the depth and position of the barrier is also investigated

  3. A New Approach in Teaching Power Electronics Control of Electrical Drives using Real-Time

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Bech, Michael Møller; Blaabjerg, Frede

    2000-01-01

    A new approach in teaching power electronics and electrical drives is achieved at the Flexible Drives System Laboratory (FDSL) from Aalborg University by using the new Total Development Environment (TDE) concept that allows a full visual block-oriented programming of dynamic real-time systems...

  4. Direct drive target survival during injection in an inertial fusion energy power plant

    International Nuclear Information System (INIS)

    Petzoldt, R.W.; Goodin, D.T.; Nikroo, A.; Stephens, E.; Alexander, N.B.; Gallix, R.; Siegel, N.; Raffray, A.R.; Mau, T.K.; Tillack, M.; Najmabadi, F.; Krasheninnikov, S.I.

    2002-01-01

    In inertial fusion energy (IFE) power plant designs, the fuel is a spherical layer of frozen DT contained in a target that is injected at high velocity into the reaction chamber. For direct drive, typically laser beams converge at the centre of the chamber (CC) to compress and heat the target to fusion conditions. To obtain the maximum energy yield from the fusion reaction, the frozen DT layer must be at about 18.5 K and the target must maintain a high degree of spherical symmetry and surface smoothness when it reaches the CC. During its transit in the chamber the cryogenic target is heated by radiation from the hot chamber wall. The target is also heated by convection as it passes through the rarefied fill-gas used to control chamber wall damage by x-rays and debris from the target explosion. This article addresses the temperature limits at the target surface beyond which target uniformity may be damaged. It concentrates on direct drive targets because fuel warm up during injection is not currently thought to be an issue for present indirect drive designs and chamber concepts. Detailed results of parametric radiative and convective heating calculations are presented for direct-drive targets during injection into a dry-wall reaction chamber. The baseline approach to target survival utilizes highly reflective targets along with a substantially lower chamber wall temperature and fill-gas pressure than previously assumed. Recently developed high-Z material coatings with high heat reflectivity are discussed and characterized. The article also presents alternate target protection methods that could be developed if targets with inherent survival features cannot be obtained within a reasonable time span. (author)

  5. Studies of non-inductive current drive in the CDX-U tokamak

    International Nuclear Information System (INIS)

    Hwang, Y.S.

    1993-01-01

    Two types of novel, non-inductive current drive concepts for starting-up and maintaining tokamak discharges, dc-helicity injection and internally-generated pressure-driven currents, have been developed on the CDX-U tokamak. To study the equilibrium and transport of these plasmas, a full set of magnetic diagnostics was installed. By applying a finite element method and a least squares error fitting technique, internal plasma current distributions are reconstructed from the measurements. Electron density distributions were obtained from 2 mm interferometer measurements by a similar least squares error technique utilizing magnetic flux configurations obtained by the magnetic analysis. Neoclassical pressure-driven currents in ECH plasmas are modeled with the reconstructed magnetic structure, using the electron density distribution and the electron temperature profile measured by a Langmuir probe. In the dc-helicity injection scheme, the need to increase injection current and maintain plasma equilibrium restricts possible arrangements. Several injection configurations were investigated, with the best found to be outside injection with a single divertor configuration, where the cathode is placed at the low field side of the x-point. Both pressure-driven and dc-helicity injected tokamaks show the importance of plasma equilibrium in obtaining high plasma current. Programmed vertical field operation has proven to be very important in achieving high plasma current. These non-inductive current drive techniques show great potential as efficient current drive methods for future steady-state and/or long-pulse fusion reactors

  6. Lower hybrid heating and current drive in Iter operation scenarios and outline system design

    International Nuclear Information System (INIS)

    1994-11-01

    Lower Hybrid Waves (LHW) are considered a valid method of plasma heating and the best demonstrated current drive method. Current drive by LHW possesses the unique feature, as compared to the other methods, to retain a good current drive efficiency in plasma regions of low to medium temperature, or in low-β phases of the discharges. This makes them an essential element to realize the so called 'advanced steady-state Tokamak scenarios' in which a hollow current density profile (deep shear reversal) - established during the ramp-up of the plasma current - offers the prospects of improved confinement and an MHD-stable route to continuous burn. This report contains both modelling and design studies of an LHW system for ITER. It aims primarily at the definition of concepts and parameters for steady-state operation using LHW combined with Fast Waves (FW), or other methods of generating a central seed current for high bootstrap current operation. However simulations addressing the use of LHW for current profile control in the high current pulsed operation scenario are also presented. The outline design of a LHW system which covers the needs for both pulsed and steady-state operation is described in detail. (author). 28 refs., 49 figs

  7. Stabilization of neoclassical tearing modes by electron cyclotron current drive in JT-60U

    International Nuclear Information System (INIS)

    Isayama, A.; Oyama, N.; Urano, H.; Suzuki, T.; Takechi, M.; Hayashi, N.; Nagasaki, K.; Kamada, Y.; Ide, S.; Ozeki, T.

    2007-01-01

    Results of active control of neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD) in JT-60U are described. Growth of an NTM with poloidal mode number m = 3 and toroidal mode number n = 2 has been suppressed by ECCD inside the sawtooth inversion radius in the co-direction, showing the possibility of the coexistence of sawtooth oscillations and a small-amplitude m/n = 3/2 NTM without large confinement degradation. Stabilization of an m/n = 2/1 NTM by ECCD at the mode rational surface has been demonstrated with a small ratio of the current density driven by the electron cyclotron (EC) wave to the local bootstrap current density (∼ 0.5). In addition, dependence of the stabilization effect on ECCD location has been investigated in detail. It has been found that an m/n = 2/1 NTM can be completely stabilized with the misalignment of the ECCD location less than about half of the full island width, and that the m/n = 2/1 NTM is destabilized with the misalignment comparable to the full island width. Time-dependent, self-consistent simulation of magnetic island evolution using the TOPICS code has shown that the stabilization and destabilization of an m/n = 2/1 NTM are well reproduced with the same set of coefficients of the modified Rutherford equation. The TOPICS simulation has also clarified that EC wave power required for complete stabilization can be significantly reduced by narrowing the ECCD deposition width

  8. 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.

  9. Assessment of Joystick control during the performance of powered wheelchair driving tasks

    Directory of Open Access Journals (Sweden)

    Routhier François

    2011-05-01

    Full Text Available Abstract Background Powered wheelchairs are essential for many individuals who have mobility impairments. Nevertheless, if operated improperly, the powered wheelchair poses dangers to both the user and to those in its vicinity. Thus, operating a powered wheelchair with some degree of proficiency is important for safety, and measuring driving skills becomes an important issue to address. The objective of this study was to explore the discriminate validity of outcome measures of driving skills based on joystick control strategies and performance recorded using a data logging system. Methods We compared joystick control strategies and performance during standardized driving tasks between a group of 10 expert and 13 novice powered wheelchair users. Driving tasks were drawn from the Wheelchair Skills Test (v. 4.1. Data from the joystick controller were collected on a data logging system. Joystick control strategies and performance outcome measures included the mean number of joystick movements, time required to complete tasks, as well as variability of joystick direction. Results In simpler tasks, the expert group's driving skills were comparable to those of the novice group. Yet, in more difficult and spatially confined tasks, the expert group required fewer joystick movements for task completion. In some cases, experts also completed tasks in approximately half the time with respect to the novice group. Conclusions The analysis of joystick control made it possible to discriminate between novice and expert powered wheelchair users in a variety of driving tasks. These results imply that in spatially confined areas, a greater powered wheelchair driving skill level is required to complete tasks efficiently. Based on these findings, it would appear that the use of joystick signal analysis constitutes an objective tool for the measurement of powered wheelchair driving skills. This tool may be useful for the clinical assessment and training of powered

  10. HIL Simulation of Power Electronics and Electric Drives for Automotive Applications

    OpenAIRE

    Frank Puschmann; Axel Kiffe; Thomas Schulte

    2012-01-01

    Hardware-in-the-loop simulation is today a standard method for testing electronic equipment in the automotive industry. Since electric drives and power electronic devices are more and more important in automotive applications, these kinds of systems have to be integrated into the hardware-in-the-loop simulation. Power converters and electric drives are used in many different applications in vehicles today (hybrid electric or electric powertrain, electric steering systems, DC-DC converters, et...

  11. Measurement of current drive profile using electron cyclotron wave attenuation near the O-mode cutoff

    International Nuclear Information System (INIS)

    Fidone, I.; Meyer, R.L.; Caron, X.

    1992-01-01

    A method for determining the radial profile of the lower-hybrid current drive in tokamaks using electron cyclotron attenuation of the O mode for frequencies ω near the cutoff frequency is discussed. The basic idea is that, for a given wave frequency, the cutoff plays the role of a spatial filter selecting a variable portion of the noninductive current. It is shown that the incremental attenuation resulting from a small increase of ω displays specific features related to the current density near the cutoff point. Using the relation between the wave damping and the current density, it is possible to determine the radial profile of the current drive from the wave attenuation measurements. A numerical application is also presented for plasma parameters in the reactor regime

  12. Current-drive on the Versator-II tokamak with a slotted-waveguide fast-wave coupler

    International Nuclear Information System (INIS)

    Colborn, J.A.

    1987-11-01

    A slotted-waveguide fast-wave coupler has been constructed, without dielectric, and used to drive current on the Versator-II tokamak. Up to 35 kW of net microwave power at 2.45 GHz has been radiated into plasmas with 2 x 10 12 cm -3 ≤ mean of n/sub e/ ≤ 1.2 x 10 13 cm -3 and B/sub tor/ ≅ 1.0 T. The launched spectrum had a peak near N/sub parallel/ = -2.0 and a larger peak near N/sub parallel/ = 0.7. Radiating efficiency of the antenna was roughly independent of antenna position except when the antenna was at least 0.2 cm outside the limiter, in which case the radiating efficiency slightly improved as the antenna was moved farther outside. When the coupler was inside the limiter, radiating efficiency improved moderately with increased mean of n/sub e/. Current-drive efficiency was comparable to that of the slow wave and was not affected when the antenna spectrum was reversed; however, no current was driven for mean of n/sub e/ ≤ 2 x 10 12 cm -3 . These results indicate the fast wave was launched, but a substantial part of the power may have been mode-converted to the slow wave, possibly via a downshift in N/sub parallel/, and these slow waves may have been responsible for most of the driven current. Relevant theory for waves in plasma, current-drive efficiency, and coupling of the slotted-waveguide is discussed, the antenna design method is explained, and future work, including the construction of a much-improved probe-fed antenna, is described. 42 refs., 45 figs

  13. 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.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  15. Effect of a powered drive on pushing and pulling forces when transporting bariatric hospital beds.

    Science.gov (United States)

    Wiggermann, Neal

    2017-01-01

    Powered drives designed to assist with moving hospital beds are commercially available but no studies have evaluated whether they reduce the push and pull forces likely contributing to injury in caregivers. This study measured hand forces of 10 caregivers maneuvering a manual and powered bariatric bed through simulated hospital environments (hallway, elevator, and ramp). Peak push and pull forces exceeded previously established psychophysical limits for all activities with the manual bed. For the powered bed, peak forces were significantly (p pushing did not differ between beds. Powered drive may reduce the risk of injury or the number of caregivers needed for transport. Copyright © 2016 Elsevier Ltd. All rights reserved.

  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. Design of pulsed laser diode drive power for ZY3(02) laser altimeter

    Science.gov (United States)

    Feng, Wen; Li, Mingshan; Meng, Peibei; Yan, Fanjiang; Li, Xu; Wang, Chunhui

    2017-11-01

    Solid laser pumped by semiconductor laser has the large value in the area of space laser technology, because of the advantages of high efficiency, small volume and long life. As the indispensable component of laser, laser power is also very important. Combined with ZY3(02) laser altimeter project, a high voltage(0-300V), high current(0-80A), long pulse width(0-230us) and high precision temperature semiconductor laser power is developed. IGBT is applied in the driving circuit as the switch to provide a current pulse for LD. The heating or cooling capacity of TEC is controlled by PID compensation circuit quickly adjusts the duty cycle of the UC1637 PWM signal, to realize the high accuracy controlling of LD working temperature. The tests in the external ambient temperature of 5°C, 20°C, 30°C show that the LD current pulse is stable and the stability of LD working temperature up to +/-0.1°C around the set point temperature, which ensure the highly stable operation of DPL.

  18. Current status of nuclear power development

    International Nuclear Information System (INIS)

    Dias, P.M.

    1994-01-01

    Nuclear power is not a viable energy source for Sri Lanka at present because of a number of reasons, the main reason being the non-availability of small and economically viable nuclear power plants. However several suppliers of nuclear power plants are in the process of developing small and medium power plants (SMPRs) which could be economically competitive with coal. The paper deals with past and future trends of nuclear power plants, their economics and safety. It also deals with environmental effects and public acceptance of nuclear power plants

  19. Implications of rf current drive theory for next step steady-state tokamak design

    International Nuclear Information System (INIS)

    Schultz, J.H.

    1985-06-01

    Two missions have been identified for a next-step tokamak experiment in the United States. The more ambitious Mission II device would be a superconducting tokamak, capable of doing long-pulse ignition demonstrations, and hopefully capable of also being able to achieve steady-state burn. A few interesting lines of approach have been identified, using a combination of logical design criteria and parametric system scans [SC85]. These include: (1) TIBER: A point-design suggested by Lawrence Livermore, that proposes a machine with the capability of demonstrating ignition, high beta (10%) and high Q (=10), using high frequency, fast-wave current drive. The TIBER topology uses moderate aspect ratio and high triangularity to achieve high beta. (2) JET Scale-up. (3) Magic5: It is argued here that an aspect ratio of 5 is a magic number for a good steady-state current drive experiment. A moderately-sized machine that achieves ignition and is capable of high Q, using either fast wave or slow wave current drive is described. (4) ET-II: The concept of a highly elongated tokamak (ET) was first proposed as a low-cost approach to Mission I, because of the possibility of achieving ohmic ignition with low-stress copper magnets. We propose that its best application is really for commercial tokamaks, using fast-wave current drive, and suggest a Mission II experiment that would be prototypical of such a reactor

  20. 60 MHz fast wave current drive experiment for DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Mayberry, M.J.; Chiu, S.C.; Porkolab, M.; Chan, V.; Freeman, R.; Harvey, R.; Pinsker, R. (General Atomics, San Diego, CA (USA))

    1989-07-01

    The DIII-D facility provides an opportunity to test fast wave current drive appoach. Efficient FWCD is achieved by direct electron absorption due to Landa damping and transit time magnetic pumping. To avoid competing damping mechamisms we seek to maximize the single-pass asorption of the fast waves by electrons. (AIP)

  1. 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

    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 har...

  2. Real time control of EC heating & current drive systems on TCV

    NARCIS (Netherlands)

    Paley, J.I.; Felici, F.; Curchod, L.; Coda, S.; Goodman, T.P.

    2009-01-01

    The ability to control, in real time, the electron cyclotron heating & current drive systems for the control of MHD instabilities is particularly important for large tokamaks operating at high performance. Several algorithms have been developed and tested on TCV to explore possible control

  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

  4. Low Power DEAP Actuator Drive for Heating Valves

    DEFF Research Database (Denmark)

    Huang, Lina

    predict the behaviour and efficiency in both charging and discharging mode. The system level energy consumption is relatively low when the burst mode control scheme is applied. If 2.5 Ah batteries are employed, the high voltage driving system with bidirectional converter can run for around 2.1 years....... efficiency analysis has been carried out to achieve efficiency calculation model. Moreover, two system level control schemes are proposed to achieve the corresponding temperature control. The functionality and energy consumption of the high voltage driver have been verified through the test in the practical...

  5. 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.

  6. The effects of electron cyclotron heating and current drive on toroidal Alfvén eigenmodes in tokamak plasmas

    Science.gov (United States)

    Sharapov, S. E.; Garcia-Munoz, M.; Van Zeeland, M. A.; Bobkov, B.; Classen, I. G. J.; Ferreira, J.; Figueiredo, A.; Fitzgerald, M.; Galdon-Quiroga, J.; Gallart, D.; Geiger, B.; Gonzalez-Martin, J.; Johnson, T.; Lauber, P.; Mantsinen, M.; Nabais, F.; Nikolaeva, V.; Rodriguez-Ramos, M.; Sanchis-Sanchez, L.; Schneider, P. A.; Snicker, A.; Vallejos, P.; the AUG Team; the EUROfusion MST1 Team

    2018-01-01

    Dedicated studies performed for toroidal Alfvén eigenmodes (TAEs) in ASDEX-Upgrade (AUG) discharges with monotonic q-profiles have shown that electron cyclotron resonance heating (ECRH) can make TAEs more unstable. In these AUG discharges, energetic ions driving TAEs were obtained by ion cyclotron resonance heating (ICRH). It was found that off-axis ECRH facilitated TAE instability, with TAEs appearing and disappearing on timescales of a few milliseconds when the ECRH power was switched on and off. On-axis ECRH had a much weaker effect on TAEs, and in AUG discharges performed with co- and counter-current electron cyclotron current drive (ECCD), the effects of ECCD were found to be similar to those of ECRH. Fast ion distributions produced by ICRH were computed with the PION and SELFO codes. A significant increase in T e caused by ECRH applied off-axis is found to increase the fast ion slowing-down time and fast ion pressure causing a significant increase in the TAE drive by ICRH-accelerated ions. TAE stability calculations show that the rise in T e causes also an increase in TAE radiative damping and thermal ion Landau damping, but to a lesser extent than the fast ion drive. As a result of the competition between larger drive and damping effects caused by ECRH, TAEs become more unstable. It is concluded, that although ECRH effects on AE stability in present-day experiments may be quite significant, they are determined by the changes in the plasma profiles and are not particularly ECRH specific.

  7. Design of the RF system for Alfven wave heating and current drive in a TCA/BR tokamak

    International Nuclear Information System (INIS)

    Ruchko, L.; Andrade, M.L.; Ozono, E.; Galvao, R.M.O.; Degaspari, F.T.; Nascimento, I.C.

    1995-01-01

    The advanced RF system for Alfven wave plasma heating and current drive in TCA/BR tokamak is presented. The antenna system is capable of exciting the standing and travelling wave M = -1,N = 1,N =-4,-6 with single helicity and thus provides the possibility to improve Alfven wave plasma heating efficiency in TCA/BR tokamak and to increase input power level up to P ≅ 1 MW, without the uncontrolled density rise which was encountered in previous TCA (Switzerland) experiments. (author). 4 refs., 3 figs

  8. Control of neoclassical tearing mode by electron cyclotron current drive and non-resonant helical field application in ITER

    International Nuclear Information System (INIS)

    Taniguchi, Satoshi; Yamazaki, Kozo; Oishi, Tetsutarou; Arimoto, Hideki; Shoji, Tatsuo

    2010-01-01

    On tokamak plasmas like ITER, it is necessary to stabilize neoclassical tearing mode (NTM) because the NTM reduces plasma temperature and fusion power output. For the analysis of stabilizing NTM in fusion plasmas, the electron cyclotron current drive (ECCD) and the non-resonant external helical field (NRHF) application are simulated using the 1.5-dimensional equilibrium/transport simulation code (TOTAL code). The 3/2 NTM is stabilized by only external helical field, but the 2/1 mode is not stabilized by only external helical field in the present model. The stabilization time becomes shorter by the combination of ECCD and NRHF than that by ECCD alone. (author)

  9. Existence of non-unique steady state solutions to the RMF current drive equations

    Energy Technology Data Exchange (ETDEWEB)

    Hugrass, W N [Flinders Univ. of South Australia, Bedford Park. School of Physical Sciences

    1985-05-04

    It is shown that the value of the d.c. current driven in a plasma cylinder by means of a rotating magnetic field (RMF) is not unique for R/delta >= 6 and eBsub(..omega..)/..nu..sub(ei)m approx.R/delta, where R is the radius of the plasma cylinder, delta is the classical skin depth, ..nu..sub(ei) is the electron-ion momentum transfer collision frequency, Bsub(..omega..) is the magnitude of the rotating magnetic field, e is the electron charge and m is the electron mass. This effect is predicted using three distinct approaches: (i) a steady state anaysis which ignores the second and higher harmonics of the fields and currents; (ii) a qualitative model which utilizes the analogy between the RMF current drive technique and the operation of the induction motor; (iii) a solution of the initial boundary value equations describing the RMF current drive in cylindrical plasmas.

  10. Numerical studies on the stabilization of neoclassical tearing modes by radio frequency current drive

    International Nuclear Information System (INIS)

    Yu, Q.; Zhang, X.D.; Guenter, S.

    2004-01-01

    Numerical modeling on the stabilization of neoclassical tearing modes by localized radio frequency (rf) current drive has been carried out to study the effects of various wave and plasma parameters on the stabilization and the associated physics. The change of the rf current profile due to the magnetic island has been taken into account by modeling the two-dimensional transport of the fast electrons induced by the rf wave. It is found that, when the rf deposition width is much larger than the island width, the modulated rf current drive to deposit the rf current around the island's o point has a stronger stabilizing effect than a nonmodulated one. The slowing down time of the fast electrons and the initial island width when applying the rf wave are also found to be important in determining the stabilizing effect

  11. 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

    In vector-controlled AC drives, the design of current controller is usually based on a machine model defined in synchronous frame coordinate, where the drive performance may be degraded by both the variation of the machine parameters and the cross-coupling between the d- and q-axes components...... 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...... 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....

  12. Stable operating regimes in NET with respect to Alfven wave instabilities during neutral beam current drive

    International Nuclear Information System (INIS)

    Eckhartt, D.

    1989-01-01

    Supra-thermal ions can contribute to the steady-state current in future large tokamak machines like NET or ITER. The fast-ion population is generated by collisional slowing-down of high-energy ions which were injected as neutral atoms in quasi-tangential direction and ionized by plasma interactions. Depending on the initial beam shape these fast ions can excite microinstabilities of the Alfven-wave type which are driven by the gradients in velocity-space. The ensuring plasma turbulence is expected to slow down the fast ions very quickly. This effect reduces the current drive efficiency which otherwise is comparable to that of other current drive schemes like lower hybrid waves where the toroidal current is carried by high-energy resonant electrons. (author) 3 refs., 1 fig

  13. Energy-efficient control of a multi-section supercapacitor power supply of an electric drive

    Directory of Open Access Journals (Sweden)

    Mozzhechkov Vladimir

    2018-01-01

    Full Text Available A method for synthesizing the control laws of a multi-section supercapacitor power supply of an electric drive is developed. The synthesized control law for an electric drive realizes the prescribed motion and minimizes the required capacitance of the power source. It is achieved through optimal disconnection and connection to the power line of the drive at designated times of one of the power supply sections. Reduction of the required capacitance of the power supply is achieved through a fuller discharge of some of its sections in motion conditions requiring a low level of electrical voltage and saving high voltage in other sections for the respective motion conditions. A mathematical formulation of the problem and a method of its solution is proposed. An example of the implementation of the proposed method is considered.

  14. On the evaluation of currents in a tokamak plasma during combined Ohmic and RF current drive

    International Nuclear Information System (INIS)

    Eckhartt, D.

    1986-09-01

    By taking into account the rf-generated enhancement of the plasma electric conductivity (as formulated by Fisch in the limit of weak dc electric fields) a relation is derived between the ratio of rf to Ohmically driven currents and other plasma parameters to be measured before and after the rf onset under the condition of constant net plasma current. (author)

  15. Hysteretic self-oscillating bandpass current mode control for Class D audio amplifiers driving capacitive transducers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

    2013-01-01

    A hysteretic self-oscillating bandpass current mode control (BPCM) scheme for Class D audio amplifiers driving capacitive transducers are presented. The scheme provides excellent stability margins and low distortion over a wide range of operating conditions. Small-signal behavior of the amplifier...... the rules of electrostatics have been known as very interesting alternatives to the traditional inefficient electrodynamic transducers. When driving capacitive transducers from a Class D audio amplifier the high impedance nature of the load represents a key challenge. The BPCM control scheme ensures a flat...

  16. The transaction costs driving captive power generation: Evidence from India

    International Nuclear Information System (INIS)

    Ghosh, Ranjan; Kathuria, Vinish

    2014-01-01

    The 2003 Indian Electricity Act incentivizes captive power production through open access in an attempt to harness all sources of generation. Yet, we observe that only some firms self-generate while others do not. In this paper we give a transaction cost explanation for such divergent behavior. Using a primary survey of 107 firms from India, we construct a distinct variable to measure the transaction-specificity of electricity use. The ‘make or buy’ decision is then econometrically tested using probit model. Results are highly responsive to transaction-specificity and the likelihood of captive power generation is positively related to it. At the industrial level, this explains why food and chemical firms are more likely to make their own electricity. Since the burden of poor grid supply is highest on smaller sized and high transaction-specific firms, the grid access policies need to account for firm-level characteristics if government wants to incentivize captive power generation. - Highlights: • We analyze why some firms opt for captive power generation while others do not. • We examine the role of transaction costs in this decision making using probit model. • Unique data from a primary survey of manufacturing firms in Andhra Pradesh, India. • Transaction-specificity significantly determines who installs captive power plant (CPP). • Firm-level characteristics crucial in policies incentivizing captive generation

  17. 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.

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

    International Nuclear Information System (INIS)

    Bhatnagar, V.P.; Eriksson, L.; Gormezano, C.; Jacquinot, J.; Kaye, A.; Start, D.F.H.

    1994-01-01

    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

  19. Cross effects on electron-cyclotron and lower-hybrid current drive in tokamak plasmas

    International Nuclear Information System (INIS)

    Fidone, I.; Giruzzi, G.; Krivenski, V.; Mazzucato, E.; Ziebell, L.F.

    1986-11-01

    Electron cyclotron resonance current drive in a tokamak plasma in the presence of a lower hybrid tail is investigated using a 2D Fokker-Planck code. For an extraordinary mode at oblique propagation and down-shifted frequency it is shown that the efficiency of electron cyclotron current drive becomes, i) substantially greater than the corresponding efficiency of a Maxwellian plasma at the same bulk temperature, ii) equal or greater than that of the lower hybrid waves, iii) comparable with the efficiency of a Maxwellian plasma at much higher temperature. This enhancement results from a beneficial cross-effect of the two waves on the formation of the current carrying electron tail. (5 fig; 17 refs)

  20. Performance Availability Assessment of Combined Multi Power Source Traction Drive Considering Real Operational Conditions

    Directory of Open Access Journals (Sweden)

    Frenkel Ilia

    2016-09-01

    Full Text Available The present paper deals with the vehicle’s traction electric drive, consisting of several various electric power sources. One of the main requirements for such systems are the safety and sustainable operations, achieved largely the implementation of an uninterrupted supply of the vehicle’s propulsion system with an electric power.

  1. Simple Power Control for Sensorless Induction Motor Drives Fed by a Matrix Converter

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Lee, Kyo Beum

    2008-01-01

    This paper presents a new and simple method for sensorless control of matrix converter drives using a power flowing to the motor. The proposed control algorithm is based on controlling the instantaneous real and imaginary powers into the induction motor. To improve low-speed sensorless performance...

  2. Harmonics in power systems of ships with electrical propulsion drives. Comparison between different converters

    Energy Technology Data Exchange (ETDEWEB)

    Lehtonen, M [VTT Energy, Espoo (Finland). Energy Systems

    1996-11-01

    In this report the effects of harmonics in marine power systems is discussed and a comparison is given between the most typical converter types, including pulse width modulated drives, load commutated inverters and cycloconverters. The effect of harmonic distortion on the power system equipment and loads is first briefly discussed. Special attention is given to the circumstances in the low voltage distribution system, where general load equipment is connected. In addition to the total harmonic distortion the effect of voltage deviation to the supply quality is also considered. The origin of harmonics in the load currents of the three converter types is then considered. The differences between the converters are outlined, and the most typical spectra are presented. The possible means for reducing the harmonic distortion are also studied. The solutions considered are the increasing of the short circuit level, the use of harmonic filters and the increasing of the pulse number. In the case of cycloconverters, the optimization of the phase shift between the parallel operating bridges is also presented. Finally the effects of different converter types on the voltage quality are compared using calculations made for a typical marine power system. (author)

  3. Summary and viewgraphs from the Q-121 US/Japan advanced current drive concepts workshop

    International Nuclear Information System (INIS)

    Bonoli, P.; Porkolab, M.; Chan, V.; Pinsker, R.; Politzer, P.; Darrow, D.; Fukuyama, Atsushi; Imai, Tsuyoshi; Watari, Tetsuo; Itoh, Satoshi; Nakamura, Yukio; James, R.; Logan, G.; Porter, G.; Thomassen, K.; Lyon, J.; Mau, Tak; Tanaka, Hitoshi; Tanaka, Shigetoshi

    1990-01-01

    With the emphasis placed on current drive by ITER, which requires steady state operation in its engineering phase, it is important to bring theory and experiment in agreement for each of the schemes that could be used in that design. Both neutral beam and lower hybrid (LH) schemes are in excellent shape in that regard. Since the projected efficiency of all schemes is marginal it is also important to continue our search for more efficient processes. This workshop featured experimental and theoretical work in each processes. This workshop featured experimental and theoretical work in each of these areas, that is, validation of theory and the search for better ideas. There were a number of notable results to report, the most striking again (as with last year) the long pulse operation of TRIAM-1M. A low current was sustained for over 1 hour with LH waves, using new hall-effect sensors in the equilibrium field circuit to maintain position control. In JT-60, by sharpening the wave spectrum the current drive efficiency was improved to 0.34 x 10 20 m -2 A/W and 1.5 MA of current was driven entirely by the lower hybrid system. Also in that machine, using two different LH frequencies, the H-mode was entered. Finally, by using the LH system for startup they saved 2.5 resistive volt-sec of flux, which if extrapolated to ITER would save 40 volt-sec there. For the first time, and experiment on ECH current drive showed reasonable agreement with theory. Those experiments are reported here by James (LLNL) on the D3-D machine. Substantially lower ECH current drive than expected theoretically was observed on WT-3, but if differed by being in a low absorption regime. Nonetheless, excellent physics results were achieved in the WT-3 experiments, notably in having careful measurements of the parallel velocity distributions

  4. Exercise dependence and the drive for muscularity in male bodybuilders, power lifters, and fitness lifters.

    Science.gov (United States)

    Hale, Bruce D; Roth, Andrew D; DeLong, Ryan E; Briggs, Michael S

    2010-06-01

    Researchers have hypothesized differences in exercise dependence and drive for muscularity between bodybuilders and power lifters, while others have not found the predicted differences. This study assessed 146 weight lifters (bodybuilders, n=59; power lifters, n=47; fitness lifters, n=40) on the Exercise Dependence Scale, Bodybuilding Dependence Scale, and the Drive for Muscularity Scale. Results showed that bodybuilders and power lifters were significantly higher than fitness lifters on EDS Total, 7 EDS scales, and the 3 BDS scales. In contrast, power lifters were found to be significantly higher on DMS Total and DMS Behavior scales than bodybuilders. The regression results suggest that exercise dependence may be directly related to the drive for muscularity. 2010 Elsevier Ltd. All rights reserved.

  5. ANALYSIS OF INFLUENCE OF DESIGN CHARACTERISTICS OF INCLINED BUCKET ELEVATOR ON THE POWER OF ITS DRIVE

    Directory of Open Access Journals (Sweden)

    V. M. Bohomaz

    2016-12-01

    Full Text Available Purpose.One of the main elements of the inclined belt bucket elevators is their drive. To determine the drive power, it is necessary to carry out calculations according to standard methods, which are described in the modern literature. The basic design parameters are the productivity, lifting height, type and properties of the transported material, the angle of inclination. It is necessary to build a parametric dependence of the driving power of the elevator on its design parameters, which takes into account the standard sizes and types of buckets and belts. Methodology. Using the methodology of traction calculation of inclined belt bucket elevator there were built parametric dependences of efforts in specific points of the route of the elevator, as well as the parametric dependences of the drive power of high-speed elevators with deep and shallow buckets on their design parameters and characteristics. Findings. On the basis of constructed parametric dependencies, it was found that the function of changing the value of the elevator’s power from design capacity (at fixed lifting height, type of cargo, belt speed is piecewise constant and monotonically increasing. It was built a graphical representation of elevator drive power on the angle of its inclination within acceptable limits of change. The resulting relationship is non-linear and monotonically decreasing. In general terms the intervals of project performance values, which provide a constant value of drive power of inclined elevator were defined. As an example of the obtained results it was observed the process of dependence construction of the drive power on design capacity and inclination angle of the elevator for transporting the fine coal. Originality. For the first time there were constructed the parametric dependences of drive power of inclined bucket elevator on its design parameters that take into account the standard sizes and types of buckets and belts. Practical value. Using

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

    International Nuclear Information System (INIS)

    Ai Baoquan; Xie Huizhang; Liu Lianggang

    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.

  7. Current drive by Alfvacute en waves in elongated cross-section tokamak

    International Nuclear Information System (INIS)

    Tsypin, V.S.; Elfimov, A.G.; Nekrasov, F.M.; de Azevedo, C.A.; de Assis, A.S.

    1997-01-01

    The general approach to the Alfvacute en wave current drive problem in tokamaks with elongated transverse cross-sections was considered in this paper. Model approximations are used to describe circulating and trapped particle dynamics. This approach gives the accuracy of some percents. The expressions for the time-averaged longitudinal current and the radio-frequency currents have been obtained. They are supposed to be useful for a further analytical and computational solution of this problem. As an example, kinetic Alfvacute en waves are considered in this paper. copyright 1997 American Institute of Physics

  8. Alpha effect of Alfven waves and current drive in reversed field pinches

    International Nuclear Information System (INIS)

    Litwin, C.; Prager, S.C.

    1997-10-01

    Circularly polarized Alfven waves give rise to an α-dynamo effect that can be exploited to drive parallel current. In a open-quotes laminarclose quotes magnetic the effect is weak and does not give rise to significant currents for realistic parameters (e.g., in tokamaks). However, in reversed field pinches (RFPs) in which magnetic field in the plasma core is stochastic, a significant enhancement of the α-effect occurs. Estimates of this effect show that it may be a realistic method of current generation in the present-day RFP experiments and possibly also in future RFP-based fusion reactors

  9. MHD simulations of DC helicity injection for current drive in tokamaks

    International Nuclear Information System (INIS)

    Sovinec, C.R.; Prager, S.C.

    1994-12-01

    MHD computations of DC helicity injection in tokamak-like configurations show current drive with no ''loop voltage'' in a resistive, pressureless plasma. The self-consistently generated current profiles are unstable to resistive modes that partially relax the profile through the MHD dynamo mechanism. The current driven by the fluctuations leads to closed contours of average poloidal flux. However, the 1% fluctuation level is large enough to produce a region of stochastic magnetic field. A limited Lundquist number (S) scan from 2.5 x 10 3 to 4 x 10 4 indicates that both the fluctuation level and relaxation increase with S

  10. Multiphysics simulation by design for electrical machines, power electronics and drives

    CERN Document Server

    Rosu, Marius; Lin, Dingsheng; Ionel, Dan M; Popescu, Mircea; Blaabjerg, Frede; Rallabandi, Vandana; Staton, David

    2018-01-01

    This book combines the knowledge of experts from both academia and the software industry to present theories of multiphysics simulation by design for electrical machines, power electronics, and drives. The comprehensive design approach described within supports new applications required by technologies sustaining high drive efficiency. The highlighted framework considers the electric machine at the heart of the entire electric drive. The book also emphasizes the simulation by design concept--a concept that frames the entire highlighted design methodology, which is described and illustrated by various advanced simulation technologies. Multiphysics Simulation by Design for Electrical Machines, Power Electronics and Drives begins with the basics of electrical machine design and manufacturing tolerances. It also discusses fundamental aspects of the state of the art design process and includes examples from industrial practice. It explains FEM-based analysis techniques for electrical machine design--providing deta...

  11. High-power piezo drive amplifier for large stack and PFC applications

    Science.gov (United States)

    Clingman, Dan J.; Gamble, Mike

    2001-08-01

    This paper describes the continuing development of Boeing High Power Piezo Drive Amplifiers. Described is the development and testing of a 1500 Vpp, 8 amp switching amplifier. This amplifier is used to drive a piezo stack driven rotor blade trailing edge flap on a full size helicopter. Also discuss is a switching amplifier designed to drive a Piezo Fiber Composite (PFC) active twist rotor blade. This amplifier was designed to drive the PFC material at 2000 Vpp and 0.5 amps. These amplifiers recycle reactive energy, allowing for a power and weight efficient amplifier design. This work was done in conjunction with the DARPA sponsored Phase II Smart Rotor Blade program and the NASA Langley Research Center sponsored Active Twist Rotor (ATR) blade program.

  12. Application of Electron Bernstein Wave heating and current drive to high beta plasmas

    International Nuclear Information System (INIS)

    Efthimion, P.C.

    2002-01-01

    Electron Bernstein Waves (EBW) can potentially heat and drive current in high-beta plasmas. Electromagnetic waves can convert to EBW via two paths. O-mode heating, demonstrated on W-7AS, requires waves be launched within a narrow k-parallel range. Alternately, in high-beta plasmas, the X-mode cutoff and EBW conversion layers are millimeters apart, so the fast X-mode can tunnel to the EBW branch. We are studying the conversion of EBW to the X-mode by measuring the radiation temperature of the cyclotron emission and comparing it to the electron temperature. In addition, mode conversion has been studied with an approximate kinetic full-wave code. We have enhanced EBW mode conversion to ∼ 100% by encircling the antenna with a limiter that shortens the density scale length at the conversion layer in the scrape off of the CDX-U spherical torus (ST) plasma. Consequently, a limiter in front of a launch antenna achieves efficient X-mode coupling to EBW. Ray tracing and Fokker-Planck codes have been used to develop current drive scenarios in NSTX high-beta (∼ 40%) ST plasmas and a relativistic code will examine the potential synergy of EBW current drive with the bootstrap current. (author)

  13. Houilleres du Bassin de Lorraine - calculation of AFC drive power

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    Calculation method drawn up as a result of a test programme carried out by the CoRT working group on 'Coal and dirt clearance from the face - Face-ends' on 5 faces in the H.B.L. Describes the features of the conveyors. Presents a general formula for calculating the power requirement; how this is applied. Sets forth the experimental method for determining the formula coefficients plus annotations. Includes a table summarizing the various power factors (measured and theoretically calculated). Concludes that from the proposed methods, the best is that used by Potasses d'Alsace, on condition that certain of the coefficients are empirically validated. Includes a table giving features of the workings and the conveyors used.

  14. Prospects for stabilization of neoclassical tearing modes by electron cyclotron current drive in ITER

    International Nuclear Information System (INIS)

    La Haye, R.J.; Isayama, A.; Maraschek, M.

    2009-01-01

    The system planned for electron cyclotron current drive (ECCD) in ITER can mitigate the deleterious effects of neoclassical tearing modes (NTMs) provided that either adequate alignment of the ECCD to the rational surface is maintained or too large a misalignment is corrected on a time scale shorter than the deleterious plasma response to 'large' islands. Resistive neoclassical tearing modes will be the principal limit on stability and performance in the ITER standard scenario as the drag from rotating island induced eddy current in the resistive wall (particularly from the m/n = 2/1 mode) can slow the plasma rotation, produce locking to the wall and cause loss of high-confinement H-mode and disruption. Continuous wave (cw) ECCD at the island rational surface is successful in stabilization and/or prevention of NTMs in ASDEX Upgrade, DIII-D and JT-60U. Modulating the ECCD so that it is absorbed only on the rotating island O-point is proving successful in recovering effectiveness in ASDEX Upgrade when the ECCD is configured for wider deposition as expected in ITER. The models for the effect of misalignment on ECCD effectiveness are applied to ITER. Tolerances for misalignment are presented to establish criteria for both the alignment (by moving mirrors in ITER) in the presence of an island, and for the accuracy of real-time ITER MHD equilibrium reconstruction in the absence of an island, i.e. alignment to the mode or to the rational surface in the absence of the mode. The narrower ECCD with front steering makes precise alignment more necessary for the most effective stabilization even though the ECCD is still relatively broad, with current density deposition (full width half maximum) almost twice the marginal island width. This places strict requirements on ECCD alignment with the expected ECCD effectiveness dropping to zero for misalignments as small as 1.7 cm. The system response time for growing islands and slowing rotation without and with ECCD (at different

  15. Analysis of the Fuel Efficiency of a Hybrid Electric Drive with an Electric Power Splitter

    Directory of Open Access Journals (Sweden)

    D. Čundev

    2008-01-01

    Full Text Available This paper presents the results of an analysis of the fuel efficiency of a hybrid electric car drive, with an electric power splitter based on a double rotor synchronous permanent magnet generator. The results have been obtained through a precisely determined mathematical model and by simulating the characteristics of all essential values for the entire drive. This work is related to the experimental working stand for electric and hybrid car drive research, which has been developed at the Faculty of Electrical Engineering (FEE at CTU in Prague. 

  16. Common-mode Voltage Reduction in a Motor Drive System with a Power Factor Correction

    DEFF Research Database (Denmark)

    Adabi, J.; Boora, A.A.; Zare, F.

    2012-01-01

    Common-mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this study, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order...... to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the AC-DC diode rectifier influences the common-mode voltage generated by the inverter because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique...

  17. W7-AS contributions to: 10. topical conference on radio frequency power in plasmas, Boston, 1993 - Local transport studies on fusion plasmas, Varenna, 1993 - 5. European theory conference, El Escorial, 1993 - 4. int. workshop on plasma edge theory in fusion devices, Varenna, 1993 - 5. international Toki conference on plasma physics and controlled nuclear fusion, physics and technology of plasma heating and current drive, Toki, 1993

    International Nuclear Information System (INIS)

    1994-03-01

    The report contains the following contribution (titles and authors): High Power 140 GHz ECRH Experiments on W7-AS (V. Erckmann); Heat Wave Studies on W7-AS Stellarator (H.J. Hartfuss); Evidence for Temperature Fluctuations in the W7-AS Stellarator (H.J. Hartfuss); Transient Transport Studies in W7-AS (U. Stroth); Open Magnetic Surfaces for Modelling Plasma Transport in the Boundary of Stellarators (F. Sardei); Electron Cyclotron Current Drive and Bootstrap Current (U. Gasparino); Parametrization of Open Magnetic Structures for Modelling Plasma Transport in the Boundary of W7-AS (F. Sardei); 140 GHz ECRH Experiments at the W7-AS Stellarator (V. Erckmann); H.-Mode of W7-AS Stellarator (F. Wagner); New Subjects of H-Mode (F. Wagner); Recent Results with 140 GHz ECRH at the W7-AS Stellarator (V. Erckmann). (orig./HP)

  18. A New Power-Factor-Based Vector Control Method for Sensorless Drive of Permanent-Magnet Synchronous Motors

    Science.gov (United States)

    Shinnaka, Shinji

    As a simple vector control method for sensorless drives of permanent-magnet synchronous motors, the so-called “Power-Factor-Based (PFB) Vector Control Method” has been proposed. The conventional PFB method directly estimates the phase of the quasi-optimal stator current through a control of the power factor phase, instead of the estimation of the rotor phase. The stator current is controlled in the current reference frame whose secondary axis phase is the same as the stator current phase. This paper proposes a new PEB method where the stator current is controlled in the voltage reference frame whose secondary axis phase is the same as the voltage phase rather than the current phase. It is shown that the similar quasi-optimal stator current control can be attained through the current control with appropriate current commands taking the power factor phase into account. This paper also shows a practical method for generating the current commands and a practical guideline for the design parameters of the new PFB method.

  19. Turbidity Currents With Equilibrium Basal Driving Layers: A Mechanism for Long Runout

    Science.gov (United States)

    Luchi, R.; Balachandar, S.; Seminara, G.; Parker, G.

    2018-02-01

    Turbidity currents run out over 100 km in lakes and reservoirs, and over 1,000 km in the ocean. They do so without dissipating themselves via excess entrainment of ambient water. Existing layer-averaged formulations cannot capture this. We use a numerical model to describe the temporal evolution of a turbidity current toward steady state under condition of zero net sediment flux at the bed. The flow self-partitions itself into two layers. The lower "driving layer" approaches an invariant flow thickness, velocity profile, and suspended sediment concentration profile that sequesters nearly all of the suspended sediment. This layer can continue indefinitely at steady state over a constant bed slope. The upper "driven layer" contains a small fraction of the suspended sediment. The devolution of the flow into these two layers likely allows the driving layer to run out long distances.

  20. Analysis of Steady-State Error in Torque Current Component Control of PMSM Drive

    Directory of Open Access Journals (Sweden)

    BRANDSTETTER, P.

    2017-05-01

    Full Text Available The paper presents dynamic properties of a vector controlled permanent magnet synchronous motor drive supplied by a voltage source inverter. The paper deals with a control loop for the torque producing stator current. There is shown fundamental mathematical description for the vector control structure of the permanent magnet synchronous motor drive with respect to the current control for d-axis and q-axis of the rotor rotating coordinate system. The derivations of steady-state deviation for schemes with and without decoupling circuits are described for q-axis. The properties of both schemes are verified by MATLAB-SIMULINK program considering a lower and a higher value of inertia and by experimental measurements in our laboratory. The simulation and experimental results are presented and discussed at the end of the paper.

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

    Directory of Open Access Journals (Sweden)

    Lin-Liu Y.R.

    2012-09-01

    Full Text Available 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 has generalized that of Marushchenko’s (N.B . Marushchenko, et al. Fusion Sci. & Tech., 2009, which is extended for arbitrary temperatures and covers exactly the asymptotic for u ≫ 1 when Z → ∞, and suitable for ray-tracing calculations.

  2. Optimizing the Utility Power of a Geothermal Power Plant using Variable Frequency Drive (VFD) (Case Study: Sibayak Geothermal Power Plant)

    Science.gov (United States)

    Sinaga, R. H. M.; Manik, Y.

    2018-03-01

    Sibayak Geothermal Power Plant (SGPP) is one of the plants being developed by Pertamina Geothermal Energy (PGE) at the upstream phase. At the downstream phase, State - owned Electricity Company (PLN) through PT. Dizamatra Powerindo is the developer. The gross capacity of the power plant is 13.3 MW, consisting 1 unit of Monoblock (2 MW) developed by PGE and 2 units (2×5.65 MW) operated through Energy Sales Contract by PLN. During the development phase of a geothermal power plant, there is a chance to reduce the utility power in order to increase the overall plant efficiency. Reducing the utility power can be attempted by utilizing the wet bulb temperature fluctuation. In this study, a modeling process is developed by using Engineering Equation Solver (EES) software version 9.430. The possibility of energy saving is indicated by condenser pressure changes as a result of wet bulb temperature fluctuation. The result of this study indicates that the change of condenser pressure is about 50.8% on the constant liquid/gas (L/G) condition of the wet bulb temperature of 15°C to 25°C. Further result indicates that in this power plant, Cooling Tower Fan (CTF) is the facility that has the greatest utility load, followed by Hot Well Pump (HWP). The saving of the greatest utility load is applied trough Variable Frequency Drive (VFD) instrumentation. The result of this modeling has been validated by actual operations data (log sheet). The developed model has also been reviewed trough Specific Steam Consumption (SSC), resulting that constant L/G condition allows the optimum condition on of the wet bulb temperature of 15°C to 25°C.

  3. The advanced smart grid edge power driving sustainability

    CERN Document Server

    Carvallo, Andres

    2011-01-01

    Placing emphasis on practical ""how-to"" guidance, this cutting-edge resource provides you with a first-hand, insider's perspective on the advent and evolution of smart grids in the 21st century (smart grid 1.0). You gain a thorough understanding of the building blocks that comprise basic smart grids, including power plant, transmission substation, distribution, and meter automation. Moreover, this forward-looking volume explores the next step of this technology's evolution. It provides a detailed explanation of how an advanced smart grid incorporates demand response with smart appliances and

  4. COMPASS-D magnetic equilibria with LH and NBI current drive

    Czech Academy of Sciences Publication Activity Database

    Hronová-Bilyková, Olena; Fuchs, Vladimír; Pánek, Radomír; Urban, Jakub; Žáček, František; Stöckel, Jan; Voitsekhovitch, I.; Valovič, M.; Fitzgerald, M.

    2006-01-01

    Roč. 56, suppl.B (2006), B24-B30 ISSN 0011-4626. [Symposium on Plasma Physics and Technology/22nd./. Praha, 26.6.2006-29.6.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamak * COMPASS-D * magnetic equilibrium * ACCOME code * ASTRA code * Neutral Beam Injection * Low Hybrid Current Drive Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.568, year: 2006

  5. Potentiality of fast wave current drive in non-maxwellian plasmas

    International Nuclear Information System (INIS)

    Moreau, D.; O'Brien, M.R.; Cox, M.; Start, D.F.H.

    1987-06-01

    After a short analysis of the available experimental data on pure fast wave electron current drive we propose a theoretical scaling law for the wave absorption through combined electron Landau damping and transit time magnetic pumping. We then present the result of a fully relativistic calculation which we apply to a bi-Maxwellian electron distribution function and conclude on the requirements to be fulfilled by the energetic tail for obtaining significant damping in Tore-Supra

  6. Integration of electric drive vehicles in the Danish electricity network with high wind power penetration

    DEFF Research Database (Denmark)

    Chandrashekhara, Divya K; Østergaard, Jacob; Larsen, Esben

    2010-01-01

    /conventional) which are likely to fuel these cars. The study was carried out considering the Danish electricity network state around 2025, when the EDV penetration levels would be significant enough to have an impact on the power system. Some of the interesting findings of this study are - EDV have the potential......This paper presents the results of a study carried out to examine the feasibility of integrating electric drive vehicles (EDV) in the Danish electricity network which is characterised by high wind power penetration. One of the main aims of this study was to examine the effect of electric drive...... vehicles on the Danish electricity network, wind power penetration and electricity market. In particular the study examined the effect of electric drive vehicles on the generation capacity constraints, load curve, cross border transmission capacity and the type of generating sources (renewable...

  7. Downward Slope Driving Control for Electric Powered Wheelchair Based on Capacitor Regenerative Brake

    Science.gov (United States)

    Seki, Hirokazu; Takahashi, Yoshiaki

    This paper describes a novel capacitor regenerative braking control scheme of electric powered wheelchairs for efficient driving on downward slopes. An electric powered wheelchair, which generates the driving force by electric motors, is expected to be widely used as a mobility support system for elderly people and disabled people; however the energy efficiency has to be further improved because it is driven only by battery energy. This study proposes a capacitor regenerative braking circuit and two types of velocity control schemes with variable duty ratio. The proposed regenerative braking circuit is based on the step-up/down circuit with additional resistance and connects right and left motors in series in order to obtain a larger braking power. Some driving experiments on a practical downward slope show the effectiveness of the proposed control system.

  8. Ocean Current Power Generator. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, G. A.

    2002-07-26

    The Ocean Power Generator is both technically and economically suitable for deployment in the Gulf Stream from the US Navy facility in Dania, Florida. Yet to be completed is the calibration test in the Chesapeake Bay with the prototype dual hydroturbine Underwater Electric Kite. For the production units a revised design includes two ballast tanks mounted as pontoons to provide buoyancy and depth control. The power rating of the Ocean Power Generator has been doubled to 200 kW ready for insertion into the utility grid. The projected cost for a 10 MW installation is $3.38 per watt, a cost that is consistent with wind power pricing when it was in its deployment infancy, and a cost that is far better than photovoltaics after 25 years of research and development. The Gulf Stream flows 24 hours per day, and water flow is both environmentally and ecologically perfect as a renewable energy source. No real estate purchases are necessary, and you cannot see, hear, smell, or touch an Ocean Power Generator.

  9. Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System

    Directory of Open Access Journals (Sweden)

    Z. Zhou

    2005-12-01

    Full Text Available Power losses calculation and thermal modelling for a three-phase inverter power system is presented in this paper. Aiming a long real time thermal simulation, an accurate average power losses calculation based on PWM reconstruction technique is proposed. For carrying out the thermal simulation, a compact thermal model for a three-phase inverter power module is built. The thermal interference of adjacent heat sources is analysed using 3D thermal simulation. The proposed model can provide accurate power losses with a large simulation time-step and suitable for a long real time thermal simulation for a three phase inverter drive system for hybrid vehicle applications.

  10. Heating and current drive requirements towards steady state operation in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Poli, F. M.; Kessel, C. E.; Gorelenkova, M. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Bonoli, P. T. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Batchelor, D. B. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Harvey, B.; Petrov, Y. [CompX, Box 2672, Del Mar, CA 92014 (United States)

    2014-02-12

    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, reducing the no-wall limit. The E × B 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 weakly reversed magnetic shear profiles throughout the discharge are the focus of this work. Time-dependent transport simulations indicate that, with a trade-off of the EC equatorial and upper launcher, the formation and sustainment of quasi-steady state ITBs could be demonstrated in ITER with the baseline heating configuration. However, with proper constraints from peeling-ballooning theory on the pedestal width and height, the fusion gain and the maximum non-inductive current are below the ITER target. Upgrades of the heating and current drive system in ITER, like the use of Lower Hybrid current drive, could overcome these limitations, sustaining higher non-inductive current and confinement, more expanded ITBs which are ideal MHD stable.

  11. Heating and current drive requirements towards steady state operation in ITER

    Science.gov (United States)

    Poli, F. M.; Bonoli, P. T.; Kessel, C. E.; Batchelor, D. B.; Gorelenkova, M.; Harvey, B.; Petrov, Y.

    2014-02-01

    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, reducing the no-wall limit. The E × B 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 weakly reversed magnetic shear profiles throughout the discharge are the focus of this work. Time-dependent transport simulations indicate that, with a trade-off of the EC equatorial and upper launcher, the formation and sustainment of quasi-steady state ITBs could be demonstrated in ITER with the baseline heating configuration. However, with proper constraints from peeling-ballooning theory on the pedestal width and height, the fusion gain and the maximum non-inductive current are below the ITER target. Upgrades of the heating and current drive system in ITER, like the use of Lower Hybrid current drive, could overcome these limitations, sustaining higher non-inductive current and confinement, more expanded ITBs which are ideal MHD stable.

  12. Simulation of enhanced tokamak performance on DIII-D using fast wave current drive

    International Nuclear Information System (INIS)

    Grassie, J.S. de; Lin-Liu, Y.R.; Petty, C.C.; Pinsker, R.I.; Chan, V.S.; Prater, R.; John, H. St.; Baity, F.W.; Goulding, R.H.; Hoffman, D.H.

    1993-01-01

    The fast magnetosonic wave is now recognized to be a leading candidate for noninductive current drive for the tokamak reactor due to the ability of the wave to penetrate to the hot dense core region. Fast wave current drive (FWCD) experiments on DIII-D have realized up to 120 kA of rf current drive, with up to 40% of the plasma current driven noninductively. The success of these experiments at 60 MHz with a 2 MW transmitter source capability has led to a major upgrade of the FWCD system. Two additional transmitters, 30 to 120 MHz, with a 2 MW source capability each, will be added together with two new four-strap antennas in early 1994. Another major thrust of the DIII-D program is to develop advanced tokamak modes of operation, simultaneously demonstrating improvements in confinement and stability in quasi-steady-state operation. In some of the initial advanced tokamak experiments on DIII-D with neutral beam heated (NBI) discharges it has been demonstrated that energy confinement time can be improved by rapidly elongating the plasma to force the current density profile to be more centrally peaked. However, this high-l i phase of the discharge with the commensurate improvement in confinement is transient as the current density profile relaxes. By applying FWCD to the core of such a κ-ramped discharge it may be possible to sustain the high internal inductance and elevated confinement. Using computational tools validated on the initial DIII-D FWCD experiments we find that such a high-l i advanced tokamak discharge should be capable of sustainment at the 1 MA level with the upgraded capability of the FWCD system. (author) 16 refs., 3 figs., 1 tab

  13. Approach to high stability beta limit and its control by fast wave current drive in reversed field pinch plasma

    International Nuclear Information System (INIS)

    Kusano, K.; Kondoh, Y.; Gesso, H.; Osanai, Y.; Saito, K.N.; Ukai, R.; Nanba, T.; Nagamine, Y.; Shiina, S.

    2001-01-01

    Before the generation of steady state, dynamo-free RFP configuration by rf current driving scheme, it is necessary to find an optimum configuration into high stability beta limit against m=1 resonant resistive MHD modes and reducing nonlinearly turbulent level with less rf power. As first step to the optimization study, we are interested in partially relaxed state model (PRSM) RFP configuration, which is considered to be closer to a relaxed state at finite beta since it has force-free fields for poloidal direction with a relatively shorter characteristic length of relaxation and a relatively higher stability beta limit to m=1 resonant ideal MHD modes. The stability beta limit to m=1 resonant resistive MHD modes can be predicted to be relatively high among other RFP models and to be enhanced by the current density profile control using fast magnetosonic waves (FMW), which are accessible to high density region with strong absorption rate. (author)

  14. Enhanced Recovery Utilizing Variable Frequency Drives and a Distributed Power System

    Energy Technology Data Exchange (ETDEWEB)

    Randy Peden; Sanjiv Shah

    2005-07-26

    This report describes complete results of the project entitled ''Enhanced Recovery Utilizing Variable Frequency Drives and a Distributed Power System''. This demonstration project was initiated in July 2003 and completed in March 2005. The objective of the project was to develop an integrated power production/variable frequency drive system that could easily be deployed in the oil field that would increase production and decrease operating costs. This report describes all the activities occurred and documents results of the demonstration.

  15. Modelling and Design of Active Thermal Controls for Power Electronics of Motor Drive Applications

    DEFF Research Database (Denmark)

    Vernica, Ionut; Blaabjerg, Frede; Ma, Ke

    2017-01-01

    of active thermal control methods for the power devices of a motor drive application. The motor drive system together with the thermal cycling of the power devices have been modelled, and adverse temperature swings could be noticed during the start-up and deceleration periods of the motor. Based...... on the electrical response of the system, the junction temperature of the semiconductor devices is estimated, and consequently three active thermal control methods are proposed and practically designed with respect to the following parameters: switching frequency, deceleration slope and modulation technique....... Finally, experimental results are provided in order to validate the effectiveness of the proposed control methods....

  16. 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

    The neutral beam current drive efficiency has been investigated in the ASDEX Upgrade tokamak by replacing on-axis neutral beams with tangential off-axis beams. A clear modification of the radial fast-ion profiles is observed with a fast-ion D-alpha diagnostic that measures centrally peaked profiles...... 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...

  17. Particle pinch with fully noninductive lower hybrid current drive in Tore Supra.

    Science.gov (United States)

    Hoang, G T; Bourdelle, C; Pégourié, B; Schunke, B; Artaud, J F; Bucalossi, J; Clairet, F; Fenzi-Bonizec, C; Garbet, X; Gil, C; Guirlet, R; Imbeaux, F; Lasalle, J; Loarer, T; Lowry, C; Travère, J M; Tsitrone, E

    2003-04-18

    Recently, plasmas exceeding 4 min have been obtained with lower hybrid current drive (LHCD) in Tore Supra. These LHCD plasmas extend for over 80 times the resistive current diffusion time with zero loop voltage. Under such unique conditions the neoclassical particle pinch driven by the toroidal electric field vanishes. Nevertheless, the density profile remains peaked for more than 4 min. For the first time, the existence of an inward particle pinch in steady-state plasma without toroidal electric field, much larger than the value predicted by the collisional neoclassical theory, is experimentally demonstrated.

  18. Finite Larmor radius effects on Alfven wave current drive in low-aspect ratio tokamaks

    International Nuclear Information System (INIS)

    Komoshvili, K.; Cuperman, S.; Bruma, C.

    1998-01-01

    Alfven wave current drive (AWCD) in low-aspect ratio (A≡R/a=1/ε > or approx. 1) tokamaks (LARTs) is studied numerically. For this, the full-wave equation (E parallel ≠0) with a Vlasov-based dielectric tensor is solved by relaxation techniques, subject to appropriate boundary conditions at the plasma centre and at the plasma-vacuum interface, as well as the concentric antenna current sheet and at the external metallic wall. A systematic investigation of the physical characteristics of the AWCD generated in LARTs when kinetic effects are considered is carried out and illustrative results are presented and discussed. (author)

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  20. Probabilistic Power Flow Simulation allowing Temporary Current Overloading

    NARCIS (Netherlands)

    W.S. Wadman (Wander); G. Bloemhof; D.T. Crommelin (Daan); J.E. Frank (Jason)

    2012-01-01

    htmlabstractThis paper presents a probabilistic power flow model subject to connection temperature constraints. Renewable power generation is included and modelled stochastically in order to reflect its intermittent nature. In contrast to conventional models that enforce connection current

  1. Probablistic Power Flow Simulations Allowing Temporary Current Overloading

    NARCIS (Netherlands)

    Wadman, W.; Bloemhof, G.; Crommelin, D.; Frank, J.; Ozdemir, A.

    2013-01-01

    This paper presents a probabilistic power flow model subject to connection temperature constraints. Renewable power generation is included and modelled stochastically in order to reflect its intermittent nature. In contrast to conventional models that enforce connection current constraints,

  2. Advanced nuclear power options: The driving forces and their results

    International Nuclear Information System (INIS)

    Golay, M.W.

    1990-01-01

    Successful nuclear power plant concepts must simultaneously demonstrate satisfactory performance in terms of both safety and economics. In order to be attractive to both electric utility companies and the public, such plants must produce economical electric energy consistent with a level of safety which is acceptable to both the public and the plant owner. Programs for reactor development worldwide can be classified according to whether the reactor concept pursues improved safety or improved economic performance as the primary objective. When improved safety is the primary goal, safety enters the solution of the design problem as a constraint which restricts the set of allowed solutions. Conversely, when improved economic performance is the primary goal it is allowed to be pursued only to an extent which is compatible with stringent safety requirements. The three major reactor coolants under consideration for future advanced reactor use are water, helium and sodium. Reactor development programs focused upon safety and upon economics using each coolant are being pursued worldwide. It is seen that the safety-oriented concepts are typically of lower capacity by approximately an order of magnitude, than the economics-oriented concepts. This is the result, in the former concept, of using less efficient, but more reliable, means of accomplishing essential safety functions. (author)

  3. Advanced nuclear power options: The driving forces and their results

    Energy Technology Data Exchange (ETDEWEB)

    Golay, M W [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1990-07-01

    Successful nuclear power plant concepts must simultaneously demonstrate satisfactory performance in terms of both safety and economics. In order to be attractive to both electric utility companies and the public, such plants must produce economical electric energy consistent with a level of safety which is acceptable to both the public and the plant owner. Programs for reactor development worldwide can be classified according to whether the reactor concept pursues improved safety or improved economic performance as the primary objective. When improved safety is the primary goal, safety enters the solution of the design problem as a constraint which restricts the set of allowed solutions. Conversely, when improved economic performance is the primary goal it is allowed to be pursued only to an extent which is compatible with stringent safety requirements. The three major reactor coolants under consideration for future advanced reactor use are water, helium and sodium. Reactor development programs focused upon safety and upon economics using each coolant are being pursued worldwide. It is seen that the safety-oriented concepts are typically of lower capacity by approximately an order of magnitude, than the economics-oriented concepts. This is the result, in the former concept, of using less efficient, but more reliable, means of accomplishing essential safety functions. (author)

  4. Community Anaerobic Digester: Powered by Students and Driving Practical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Richmond Hall, Joan [Vermont Sustainable Jobs Fund, Montpelier, VT (United States); O' Leary, Mary [Vermont Sustainable Jobs Fund, Montpelier, VT (United States)

    2016-03-23

    The Vermont Tech Community Anaerobic Digester (VTCAD) was conceived and funded by a partnership of educational, agricultural, waste management and environmental groups to create a living laboratory demonstrating the value of recycling nutrients, renewable energy and agricultural co-products from organic wastes. VTCAD was constructed on the Randolph Center, Vermont campus of Vermont Tech, a public college offering engineering technology, agricultural, renewable energy education and workforce training. With funding from the U.S. Department of Energy (DOE), the Vermont State Colleges and others, construction was completed in early 2014 and the facility has been operational since April 2014. At full power, VTCAD uses 16,000 gallons of manure and organic residuals to produce 8,880 kilowatt hours (kWh) of electricity per day, ‘waste’ heat that will be used to heat four campus buildings, bedding material for the college dairy herds and recycled nutrients used as crop fertilizer. VTCAD uses a mixture of manure from co-managed farms and organic residuals collected from the community. Feedstock materials include brewery residuals, the glycerol by-product of biodiesel production from waste cooking oil, grease trap waste, and waste paper and, soon, locally collected pre- and post-consumer food residuals.

  5. Research activities and plan of electron cyclotron wave startup and Alfven wave current drive at SUNIST

    International Nuclear Information System (INIS)

    Gao Zhe; He Yexi; Tan Yi

    2009-01-01

    Using electromagnetic waves to startup and sustain plasma current takes a important role in the research program of the SUNIST spherical tokamak. Electron cyclotron ware (ECW) current startup have been investigated and revealed two totally different regimes. In the regime of very low working pressure, a plasma current of about 2 kA is obtained with a steadily applied vertical field of 12 Gauss and 40 kW/2.45 GHz microwave injection. In addition, the physics of the transient process during ECW startup in the relatively high working pressure regime is analyzed. The hardware preparation for the experimental research of Alfven wave current drive is being performed. The Alfven wave antenna system consists of four models in toroidal direction and two antenna straps in poloidal direction for each module and the rf generator has been designed as a four-phase oscillator (4x100 kW, 0.5 - 1 Mhz).The impedance spectrum of the antenna system is roughly evaluated by 1-D cylindrical magneto-hydrodynamic calculation. To investigate the wave-plasma interaction in ECW startup and Alfven wave current drive, upgrade of the device, especially in equilibrium control and diagnostics, is ongoing. (author)

  6. Simulations of enhanced reversed shear TFTR discharges with lower hybrid current drive

    International Nuclear Information System (INIS)

    Kesner, J.; Bateman, G.

    1996-01-01

    The BALDUR based BBK code permits predictive simulations of time-dependent tokamak discharges and has the capability to include neutral beam heating, pellet injection, bootstrap currents and lower hybrid current drive. BALDUR contains a theory based multi-regime transport model and previous work has shown excellent agreement with both L-mode and supershot TFTR discharges. These simulations reveal that core transport is dominated by η i and trapped electron modes and the outer region by resistive ballooning. We simulate enhanced reverse shear discharges by beginning with a supershot simulation with a reversed shear profile. Similarly to the TFTR experiments the reversed shear profile is obtained through the programming of the current during startup and the freezing in of these profiles by subsequent heating. At the time of transition into the enhanced confinement regime we turn off the η i and trapped-electron mode transport. We examine the further modification of the plasma current profile that can be obtained with the application of lower hybrid current drive. The results of these simulations will be discussed

  7. Current drive by neutral beams, rotating magnetic fields and helicity injection in compact toroids

    International Nuclear Information System (INIS)

    Farengo, R.

    2002-01-01

    A Monte-Carlo code is used to study neutral beam current drive in Spheromaks. The exact particle trajectories are followed in the self-consistent equilibria calculated including the beam current. Reducing Z(eff) does not increase the current drive efficiency because the reduction of the stopping cross section is compensated by an increase in the electron canceling current. Significant changes in the safety factor profile can be produced with relatively low beam currents. Minimum dissipation states of a flux core spheromak sustained by helicity injection are presented. Helicity balance is used as a constraint and the resistivity is considered to be non-uniform. Two types of relaxed states are found; one has a central core of open flux surrounded by a toroidal region of closed flux surfaces and the other has the open flux wrapped around the closed flux surfaces. Non-uniform resistivity effects can be very important due to the changes they produce in the safety factor profile. A hybrid, fluid electrons particle ions, code is employed to study ion dynamics in FRCs sustained by rotating magnetic fields. (author)

  8. Q-profile evolution and improved core electron confinement in the full current drive operation on Tore Supra

    International Nuclear Information System (INIS)

    Litaudon, X.; Peysson, Y.; Aniel, T.; Huysmans, G.; Imbeaux, F.; Joffrin, E.; Lasalle, J.; Lotte, Ph.; Schunke, B.; Segui, J.; Tresset, G.; Zabiego, M.

    2000-12-01

    The formation of a core region with improved electron confinement is reported in the recent full current drive operation of Tore Supra where the plasma current is sustained with the Lower Hybrid, LH, wave. Current profile evolution and thermal electron transport coefficients are directly assessed using the data of the new fast electron Bremsstrahlung tomography that provides the most accurate determination of the LH current and power deposition profiles. The spontaneous rise of the core electron temperature observed a few seconds after the application of the LH power is ascribed to a bifurcation towards a state of reduced electron transport. The role of the magnetic shear is invoked to partly stabilize the anomalous electron turbulence. The electron temperature transition occurs when the q-profile evolves towards a non-inductive state with a non-monotonic shape i.e. when the magnetic shear is reduced close to zero in the plasma core. The improved core confinement phase is often terminated by a sudden MHD activity when the minimum q approaches two. (authors)

  9. Current problems of Bulgarian nuclear power

    International Nuclear Information System (INIS)

    Luk'yanov, A.A.; Vapirev, E.I.

    1996-01-01

    The main unsolved problems of Bulgarian nuclear power industry now are: a serious trouble that the WWER-440 units will have to be phased out before the end of their projected life since they do not meet contemporary safety requirements; heavy economic difficulties with the construction of the new NPP 'Belene'; accumulation of a considerable amount of spent fuel because of its interrupted export to Russia

  10. An analysis of current drive by travelling wave based on theory of intrinsic stochasticity

    International Nuclear Information System (INIS)

    Murakami, Akihiko; Midzuno, Yukio.

    1982-04-01

    The mechanism of the current generation in a collisionless plasma by a train of travelling mirrors with modulated phase velocity is studied based on the theory of intrinsic stochasticity. It is shown that, if the phase modulation is small, the main contribution to the current generation comes from the phase mixing of the trajectories of trapped electrons in each Fourier component of a driving wave. For the case of a moderate phase modulation, however, formation of a large stochastic region due to the overlapping of primary resonances is very effective for increasing the generated current. Large phase modulation has little advantage in the current generation because the stochastic regions are formed, so to speak, at random in the phase plane. The results of analytical evaluation based on the above theory agree quite well with results of numerical experiments. (author)

  11. Study of non-inductive current drive using high energy neutral beam injection on JT-60U

    International Nuclear Information System (INIS)

    Oikawa, Toshihiro

    2004-01-01

    The negative ion based neutral beam (N-NB) current drive was experimentally studied. The N-NB driven current density was determined over a wide range of electron temperatures by using the motional Stark effect spectroscopy. Theoretical prediction of the NB current drive increasing with beam energy and electron temperature was validated. A record value of NB current drive efficiency 1.55 x 10 19 Am -2 W -1 was achieved simultaneously with high confinement and high beta at at a plasma current of 1.5 MA under a fully non-inductively current driven condition. The experimental validation of NB current drive theory for MHD quiescent plasmas gives greater confidence in predicting the NB current drive in future reactors. However, it was also found that MHD instabilities caused a degradation of NB current drive. A beam-driven instability expelled N-NB fast ions carrying non-inductive current from the central region. The lost N-NB driven current was estimated to be 7% of the total N-NB driven current. For the neoclassical tearing mode (NTM), comparisons of the measured neutron yield and fast ion pressure profile with transport code calculations revealed that the loss of fast ions increases with the NTM activity and that fast ions at higher energies suffer larger transport than at lower energies. (author)

  12. 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......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 appropriate strategy for minimizing their effects. This paper investigates the ASD's input current interharmonic sources caused by applying symmetrical regularly sampled fixed-frequency modulation techniques on the inverter. The interharmonics generation process is precisely formulated and comparative results...

  13. Lower hybrid current drive: an overview of simulation models, benchmarking with experiment, and predictions for future devices

    International Nuclear Information System (INIS)

    Bonoli, P.T.; Barbato, E.; Imbeaux, F.

    2003-01-01

    This paper reviews the status of lower hybrid current drive (LHCD) simulation and modeling. We first discuss modules used for wave propagation, absorption, and current drive with particular emphasis placed on comparing exact numerical solutions of the Fokker Planck equation in 2-dimension with solution methods that employ 1-dimensional and adjoint approaches. We also survey model predictions for LHCD in past and present experiments showing detailed comparisons between simulated and observed current drive efficiencies and hard X-ray profiles. Finally we discuss several model predictions for lower hybrid current profile control in proposed next step reactor options. (authors)

  14. High current and high power superconducting rectifiers

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  15. Electron cyclotron current drive experiments in LHCD plasmas using a remote steering antenna on the TRIAM-1M tokamak

    International Nuclear Information System (INIS)

    Idei, H.; Hanada, K.; Zushi, H.; Ohkubo, K.; Hasegawa, M.; Kubo, S.; Nishi, S.; Fukuyama, A.; Sato, K.N.; Nakamura, K.; Sakamoto, M.; Iyomasa, A.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Notake, T.; Shimozuma, T.; Ito, S.; Hoshika, H.; Maezono, N.; Nakashima, K.; Ogawa, M.

    2006-01-01

    A remote steering antenna was recently developed for electron cyclotron heating and current drive (ECH/ECCD) experiments on the TRIAM-1M tokamak. This is the first application of the remote steering antenna concept for ECH/ECCD experiments, which have conditions relevant to the International Thermonuclear Experimental Reactor (ITER). Fundamental ECH and ECCD experiments were conducted in the ITER frequency from the low field using this antenna system. In addition to the angles near 0 0 , the launcher was a symmetric direction antenna with an extended steering-angle capability of ±(8 0 -19 0 ). The output beam from the antenna was a well-defined Gaussian with a proper steering angle. The Gaussian content and the steering-angle accuracy were 0.85 and -0.5 0 , respectively. The high power tests measured the antenna transmission efficiency at 0.90-0.94. The efficiencies obtained in the low and high power tests were consistent with the calculations using higher-order modes. In order to excite the pure O/X-modes in the oblique injection, two polarizers were used to control the elliptical polarization of the incident beam for the ECCD experiments. The fundamental O/X-mode ECH/ECCD was applied to lower hyrid current drive plasmas at the optimized incident polarization. In the X-mode experiment, at medium density (∼1 x 10 19 m -3 ), clear differences in the plasma current and the hard x-ray intensity were observed between the co- and counter-steering injections due to the ECCD effect on the coupling of forward fast electrons

  16. Electric machinery and drives in thermal power stations. Elektrische Maschinen und Antriebe in thermischen Kraftwerken

    Energy Technology Data Exchange (ETDEWEB)

    1974-01-01

    The following subjects were dealt with during the VDE meeting: 1) Requirements made by the electric network on the generators and their excitation equipment, and the influence thereof on their design; 2) requirements made by the power station process on the electric drives and the influence thereof on type and design; 3) requirements made on protective measures from the point of the electric power station machinery.

  17. Manufacturing: SiC Power Electronics for Variable Frequency Motor Drives

    Energy Technology Data Exchange (ETDEWEB)

    Horowitz, Kelsey A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bench Reese, Samantha R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Remo, Timothy W [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-15

    This brochure, published as an annual research highlight of the Clean Energy Manufacturing Analysis Center (CEMAC), summarizes CEMAC analysis of silicon carbide (SiC) power electronics for variable frequency motor drives. The key finding presented is that variations in manufacturing expertise, yields, and access to existing facilities impact regional costs and manufacturing location decisions for SiC ingots, wafers, chips, and power modules more than do core country-specific factors such as labor and electricity costs.

  18. A micro-power LDO with piecewise voltage foldback current limit protection

    International Nuclear Information System (INIS)

    Wei Hailong; Liu Youbao; Guo Zhongjie; Liao Xue

    2012-01-01

    To achieve a constant current limit, low power consumption and high driving capability, a micro-power LDO with a piecewise voltage-foldback current-limit circuit is presented. The current-limit threshold is dynamically adjusted to achieve a maximum driving capability and lower quiescent current of only 300 nA. To increase the loop stability of the proposed LDO, a high impedance transconductance buffer under a micro quiescent current is designed for splitting the pole that exists at the gate of the pass transistor to the dominant pole, and a zero is designed for the purpose of the second pole phase compensation. The proposed LDO is fabricated in a BiCMOS process. The measurement results show that the short-circuit current of the LDO is 190 mA, the constant limit current under a high drop-out voltage is 440 mA, and the maximum load current under a low drop-out voltage is up to 800 mA. In addition, the quiescent current of the LDO is only 7 μA, the load regulation is about 0.56% on full scale, the line regulation is about 0.012%/V, the PSRR at 120 Hz is 58 dB and the drop-out voltage is only 70 mV when the load current is 250 mA. (semiconductor integrated circuits)

  19. Resonant power converter driving and inductive load like a discharge lamp

    NARCIS (Netherlands)

    2010-01-01

    A resonant power converter (1) for driving an inductive load as, e.g. an inductively coupled gas- discharge lamp, is designed for operation at an operational frequency (Fop) of 13.56 MHz and comprises: a series arrangement of a first inductor (L1) and a first controllable switch (Q1) connected to a

  20. Fuel-Cell-Powered Electric Motor Drive Analyzed for a Large Airplane

    Science.gov (United States)

    Brown, Gerald V.; Choi, Benjamin B.

    2005-01-01

    Because of its high efficiency, fuel cell technology may be used to launch a new generation of more-electric aeropropulsion and power systems for future aircraft. Electric-motor-driven airplanes using fuel-cell powerplants would be beneficial to the environment because of fuel savings, low noise, and zero carbon-dioxide emissions. In spite of the fuel cell s efficiency benefit, to produce the same shaft drive power, a fuel cell- powered electric-drive system must be definitely heavier than a turbine-drive system. However, the fuel-cell system s overall efficiency from fuel-to-shaft power is higher than for a turbine-drive system. This means that the fuel consumption rate could be lower than for a conventional system. For heavier, fuel-laden planes for longer flights, we might achieve substantial fuel savings. In the airplane industry, in fact, an efficiency gain of even a few percentage points can make a major economic difference in operating costs.

  1. Social power and social class: conceptualization, consequences, and current challenges.

    Science.gov (United States)

    Rucker, Derek D; Galinsky, Adam D

    2017-12-01

    This article offers a primer on social power and social class with respect to their theoretical importance, conceptual distinction, and empirical relationship. We introduce and define the constructs of social power, social class, and one's psychological sense of power. We next explore the complex relationship between social power and social class. Because social class can produce a sense of power within an individual, studies on social power can inform theory and research on social class. We conclude with a discussion of the current challenges and future opportunities for the study of social power and social class. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. The production of high poloidal tokamak equilibria in Versator II by means of RF current drive

    International Nuclear Information System (INIS)

    Luckhardt, S.C.; Chen, K.-I.; Kesner, J.; Kirkwood, R.; Lane, B.; Porkolab, M.; Squire, J.

    1989-01-01

    Experiments on the Versator II device have been carried out in a regime of low plasma current with the aim of reaching high poloidal beta, β p . Lower-Hybrid RF current drive is used to produce an energetic electron population which carries the plasma current and pressure. In this mode of operation, plasmas with εβ p approaching unity appear attainable. Data from equilibrium magnetic analysis, hard x-ray, and density profiles display an outward magnetic axis shift in agreement with equilibrium theory, and further indicate that q(O) is in the range of 4-6. PEST code modeling of these experiments suggests that some of these plasmas may be near or beyond the transition to the second stability region for ballooning modes. (author)

  3. Fundamental X-mode electron cyclotron current drive using remote-steering symmetric direction antenna at larger steering angles

    International Nuclear Information System (INIS)

    Idei, H.; Hanada, K.; Zushi, H.; Sato, K.N.; Sakamoto, M.; Iyomasa, A.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Ohkubo, K.; Kubo, S.; Shimozuma, T.; Ito, S.; Hasegawa, M.; Nakamura, K.; Notake, T.; Hoshika, H.; Maezono, N.; Nishi, S.; Nakashima, K.

    2005-01-01

    A remote steering antenna has been newly developed for Electron Cyclotron Heating and Current Drive (ECH/ECCD) experiments on the TRIAM-1M tokamak. It is a first application of the remote steering antenna to the ECH/ECCD experiments under the conditions relevant to International Thermonuclear Experimental Reactor. Our launcher is a symmetric direction antenna with extended steering capability. The larger steering angles of 8-19 degrees are available, in addition to that near 0 degree. The output beam from the antenna is the well-defined Gaussian beam with a correct steering angle. The Gaussian content and the steering angle accuracy are 0.85 and -0.3 degrees, respectively. Antenna transmission efficiency in the high power test is evaluated as 0.95. The efficiencies at the low and high power tests are consistent with those in the calculation with higher-order modes. The difference between plasma currents increased at co- and counter-steering injections [+/-19 degrees] is clearly observed in the superposition to the Lower Hybrid Current Driven (LHCD) plasma of the fundamental X-mode injection. (author)

  4. Variational full wave calculation of fast wave current drive in DIII-D using the ALCYON code

    International Nuclear Information System (INIS)

    Becoulet, A.; Moreau, D.

    1992-04-01

    Initial fast wave current drive simulations performed with the ALCYON code for the 60 MHz DIII-D experiment are presented. Two typical shots of the 1991 summer campaign were selected with magnetic field intensities of 1 and 2 teslas respectively. The results for the wave electromagnetic field in the plasma chamber are displayed. They exhibit a strong enrichment of the poloidal mode number m-spectrum which leads to the upshift of the parallel wavenumber, κ perpendicular, and to the wave absorption. The m-spectrum is bounded when the local poloidal wavenumber reaches the Alfven wavenumber and the κ perpendicular upshifts do not destroy the wave directionality. Linear estimations of the driven current are made. The current density profiles are found to be peaked and we find that about 88 kA can be driven in the 1 tesla/1.7 keV phase with 1.7 MW coupled to the electrons. In the 2 tesla/3.4 keV case, 47 kA are driven with a total power of 1.5 MW, 44% of which are absorbed on the hydrogen minority, through the second harmonic ion cyclotron resonance. The global efficiency is then 0.18 x 10 19 A m -2 W -1 if one considers only the effective power going to the electrons

  5. Current drive efficiency requirements for an attractive steady-state reactor

    Energy Technology Data Exchange (ETDEWEB)

    Tonon, G

    1994-12-31

    The expected values of the figure of merit and the electrical efficiency of various non-inductive current drive methods are considered. The main experimental results achieved today with neutral beams and radiofrequency systems are summarized. Taking into account the simplified energy flow diagram of a steady state reactor, the figure of merit and the electrical efficiency values which are necessary in order to envisage an attractive steady-state reactor are determined. These values are compared to the theoretical predictions. (author). 16 refs., 11 figs., 2 tabs.

  6. Combined operation of pellet injection and lower hybrid current drive on ASDEX

    International Nuclear Information System (INIS)

    Soeldner, F.X.; Mertens, V.; Bosch, H.S.; Kornherr, M.; Lang, R.; Leuterer, F.; Loch, R.; Sandmann, W.; Bartiromo, R.; Ushigusa, K.

    1990-10-01

    Simultaneous operation of Lower Hybrid-current drive and pellet injection could be successfully achieved. With peripheral ablation of the pellets by suprathermal electrons, the same net inward flux of particles is found as with deep penetration of pellets into ohmically heated plasmas. The density profile n e (r) peaks with the same increment of the peaking factor Q n = n eo / e > in both cases. The global energy confinement time rises with density, τ E ∝ anti n e , in the combined operation. (orig.)

  7. Angular distribution of the bremsstrahlung emission during lower-hybrid current drive on PLT

    International Nuclear Information System (INIS)

    von Goeler, S.; Stevens, J.; Bernabei, S.

    1985-06-01

    The bremsstrahlung emission from the PLT tokamak during lower-hybrid current drive has been measured as a function of angle between the magnetic field and the emission direction. The emission is peaked strongly in the forward direction, indicating a strong anisotropy of the electron-velocity distribution. The data demonstrate the existence of a nearly flat tail of the velocity distribution, which extends out to approximately 500 keV and which is interpreted as the plateau created by Landau damping of the lower-hybrid waves

  8. [Magnetic helicity and current drive in fusion devices]. Final technical report

    International Nuclear Information System (INIS)

    1998-01-01

    The research program focused on two main themes: (i) magnetic helicity and (ii) current drive by low-frequency waves. At first these themes seemed unrelated, but as time progressed, they became interwoven, and ultimately closely connected. A sub-theme is that while the MHD model of a plasma stimulates many intriguing counter-intuitive ideas for creating and sustaining magnetic confinement configurations, usually the crux of these schemes involves some sort of breakdown of MHD, i.e., involves physics which transcends MHD

  9. Current drive efficiency requirements for an attractive steady-state reactor

    International Nuclear Information System (INIS)

    Tonon, G.

    1994-01-01

    The expected values of the figure of merit and the electrical efficiency of various non-inductive current drive methods are considered. The main experimental results achieved today with neutral beams and radiofrequency systems are summarized. Taking into account the simplified energy flow diagram of a steady state reactor, the figure of merit and the electrical efficiency values which are necessary in order to envisage an attractive steady-state reactor are determined. These values are compared to the theoretical predictions. (author). 16 refs., 11 figs., 2 tabs

  10. A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks

    Czech Academy of Sciences Publication Activity Database

    Urban, Jakub; Decker, J.; Peysson, Y.; Preinhaelter, Josef; Shevchenko, V.; Taylor, G.; Vahala, L.; Vahala, G.

    2011-01-01

    Roč. 51, č. 8 (2011), 083050-083050 ISSN 0029-5515 R&D Projects: GA ČR GA202/08/0419; GA MŠk 7G10072 Institutional research plan: CEZ:AV0Z20430508 Keywords : spherical tokamak * electron Bernstein wave (EBW) * heating * current drive * electron cyclotron wave Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.090, year: 2011 http://iopscience.iop.org/0029-5515/51/8/083050/pdf/0029-5515_51_8_083050.pdf

  11. Lower hybrid current drive experiments with graphite limiters in the HT-7 superconducting tokamak

    International Nuclear Information System (INIS)

    Liu, J.; Gao, X.; Hu, L.Q.; Asif, M.; Chen, Z.Y.; Ding, B.J.; Zhou, Q.; Liu, H.Q.; Jie, Y.X.; Kong, W.; Lin, S.Y.; Ding, Y.H.; Gao, L.; Xu, Q.

    2006-01-01

    Recent progress of lower hybrid (LH) experiments with new graphite limiters configuration in the HT-7 tokamak is presented. The lower hybrid current drive (LHCD) efficiency can be determined by fitting based on experimental data. Improved particle confinement was observed via LHCD (P LHW >300 kW) characterized by the particle confinement time τ p increased about 1.56 times. It is found that runaways are suppressed during loop voltage is decreasing at the flat-top phase of LH discharges. The main limitations of pulse length are presented in long-pulse experiments with new limiter configuration

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

    International Nuclear Information System (INIS)

    Sun, Guanglan; Dong, Chunying; Duan, Longfang

    2015-01-01

    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

  13. 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.

  14. A spectral power analysis of driving behavior changes during the transition from nondistraction to distraction.

    Science.gov (United States)

    Wang, Yuan; Bao, Shan; Du, Wenjun; Ye, Zhirui; Sayer, James R

    2017-11-17

    This article investigated and compared frequency domain and time domain characteristics of drivers' behaviors before and after the start of distracted driving. Data from an existing naturalistic driving study were used. Fast Fourier transform (FFT) was applied for the frequency domain analysis to explore drivers' behavior pattern changes between nondistracted (prestarting of visual-manual task) and distracted (poststarting of visual-manual task) driving periods. Average relative spectral power in a low frequency range (0-0.5 Hz) and the standard deviation in a 10-s time window of vehicle control variables (i.e., lane offset, yaw rate, and acceleration) were calculated and further compared. Sensitivity analyses were also applied to examine the reliability of the time and frequency domain analyses. Results of the mixed model analyses from the time and frequency domain analyses all showed significant degradation in lateral control performance after engaging in visual-manual tasks while driving. Results of the sensitivity analyses suggested that the frequency domain analysis was less sensitive to the frequency bandwidth, whereas the time domain analysis was more sensitive to the time intervals selected for variation calculations. Different time interval selections can result in significantly different standard deviation values, whereas average spectral power analysis on yaw rate in both low and high frequency bandwidths showed consistent results, that higher variation values were observed during distracted driving when compared to nondistracted driving. This study suggests that driver state detection needs to consider the behavior changes during the prestarting periods, instead of only focusing on periods with physical presence of distraction, such as cell phone use. Lateral control measures can be a better indicator of distraction detection than longitudinal controls. In addition, frequency domain analyses proved to be a more robust and consistent method in assessing

  15. A Fabry-Pérot electro-optic sensing system using a drive-current-tuned wavelength laser diode.

    Science.gov (United States)

    Kuo, Wen-Kai; Wu, Pei-Yu; Lee, Chang-Ching

    2010-05-01

    A Fabry-Pérot enhanced electro-optic sensing system that utilizes a drive-current-tuned wavelength laser diode is presented. An electro-optic prober made of LiNbO(3) crystal with an asymmetric Fabry-Pérot cavity is used in this system. To lock the wavelength of the laser diode at resonant condition, a closed-loop power control scheme is proposed. Experiment results show that the system can keep the electro-optic prober at high sensitivity for a long working time when the closed-loop control function is on. If this function is off, the sensitivity may be fluctuated and only one-third of the best level in the worst case.

  16. Joystick-controlled video console game practice for developing power wheelchairs users' indoor driving skills.

    Science.gov (United States)

    Huang, Wei Pin; Wang, Chia Cheng; Hung, Jo Hua; Chien, Kai Chun; Liu, Wen-Yu; Cheng, Chih-Hsiu; Ng, How-Hing; Lin, Yang-Hua

    2015-02-01

    [Purpose] This study aimed to determine the effectiveness of joystick-controlled video console games in enhancing subjects' ability to control power wheelchairs. [Subjects and Methods] Twenty healthy young adults without prior experience of driving power wheelchairs were recruited. Four commercially available video games were used as training programs to practice joystick control in catching falling objects, crossing a river, tracing the route while floating on a river, and navigating through a garden maze. An indoor power wheelchair driving test, including straight lines, and right and left turns, was completed before and after the video game practice, during which electromyographic signals of the upper limbs were recorded. The paired t-test was used to compare the differences in driving performance and muscle activities before and after the intervention. [Results] Following the video game intervention, participants took significantly less time to complete the course, with less lateral deviation when turning the indoor power wheelchair. However, muscle activation in the upper limbs was not significantly affected. [Conclusion] This study demonstrates the feasibility of using joystick-controlled commercial video games to train individuals in the control of indoor power wheelchairs.

  17. Optimal recharge and driving strategies for a battery-powered electric vehicle

    Directory of Open Access Journals (Sweden)

    Lee W. R.

    1999-01-01

    Full Text Available A major problem facing battery-powered electric vehicles is in their batteries: weight and charge capacity. Thus, a battery-powered electric vehicle only has a short driving range. To travel for a longer distance, the batteries are required to be recharged frequently. In this paper, we construct a model for a battery-powered electric vehicle, in which driving strategy is to be obtained such that the total travelling time between two locations is minimized. The problem is formulated as an optimization problem with switching times and speed as decision variables. This is an unconventional optimization problem. However, by using the control parametrization enhancing technique (CPET, it is shown that this unconventional optimization is equivalent to a conventional optimal parameter selection problem. Numerical examples are solved using the proposed method.

  18. Effect of Asymmetric Layout of IGBT Modules on Reliability of Power Inverters in Motor Drive System

    DEFF Research Database (Denmark)

    Choi, Uimin; Vernica, Ionut; Blaabjerg, Frede

    2018-01-01

    of inverters are limited by the most stressed devices. However, generally common data is provided for all devices and this may cause improper design of the inverters in terms of power rating and lifetime. In this paper, the effect of an asymmetric layout of IGBT modules on the reliability of power inverters......An IGBT module has typically multiple power devices for some technical and cost advantages. This kind of configurations could have an asymmetric layout, which may lead to different thermal loadings and thereby lifetime difference of the power devices. Therefore, both the power rating and lifetime...... is studied based on a 3-phase motor drive application with a 600 V, 30 A, 3-phase transfer molded IGBT module. The thermal impedances of 6 IGBTs are investigated and its effect on the thermal loadings of power devices is studied under the given mission profile. Finally, their lifetimes are estimated...

  19. Experimentally determined profiles of fast wave current drive on DIII-D

    International Nuclear Information System (INIS)

    Forest, C.B.; Petty, C.C.; Baity, F.W.; Chiu, S.C.; deGrassie, J.S.; Groebner, R.J.; Ikezi, H.; Jaeger, E.F.; Kupfer, K.; Murakami, M.; Pinsker, R.I.; Prater, R.; Rice, B.W.; Wade, M.R.; Whyte, D.G.

    1996-01-01

    Profiles of non-inductive current driven by fast waves have been determined for reversed-shear DIII-D discharges. Both the current profile and toroidal electric field profile are determined from time sequences of equilibrium reconstructions [C. B. Forest et al., Phys. Rev. Lett. 73, 2224 (1994)]. Using this information, the measured current profile has been separated into inductive and non-inductive portions. By comparing similar discharges with co and counter antenna phasings and similar fast wave power, the portion of the total non-inductive current driven by fast waves was determined. The experimentally determined profiles of FWCD are in general agreement with theoretical predictions. Specifically, 135 kA was driven by 1.4 MW of rf power with a profile peaked inside ρ=2. copyright 1996 American Institute of Physics

  20. A formula for efficiency of fast wave current drive in fusion devices

    International Nuclear Information System (INIS)

    Chiu, S.C.; Harvey, R.W.; Karney, C.F.F.; Mau, T.K.

    1992-06-01

    Fast wave current drive (FWCD) is a principal candidate for non- inductive current drive schemes in reactors. Major experiments are in progress or planned on DIII-D, JET, and Tore-Supra. A theory for FWCD was presented by two of the authors and collaborators. To minimize computations required in transport simulations, and for analytical understanding, it is very useful to have a concise analytical efficiency formula. Fisch and Karney, and Ehst and Karney have obtained empirical formulae that fits numerical results for the Landau limit and Alfven limit; the latter fits results at 1 i ≤ 2. This paper extends a previous numerical study on FWCD at arbitrary frequencies and Z i . Analytical formulae for FWCD efficiency, valid for all frequencies and Z i , are derived using the adjoint technique in high and low phase velocity regions. A smooth patching between the two regions produces an analytical formula which is accurate for all frequencies, Z i , and phase velocities. Comparison with existing results will be discussed. A corollary of the present calculation is that a low phase velocities and in the Landau limit, the efficiency is the same as that calculated from the Lorentz model collision operator