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Sample records for plasma shape control

  1. Plasma position and shape control for ITER

    International Nuclear Information System (INIS)

    Portone, A.; Gribov, Y.; Huguet, M.

    1995-01-01

    Key features and main results about the control of the plasma shape in ITER are presented. A control algorithm is designed to control up to 6 gaps between the plasma separatrix and the plasma facing components during the reference burn phase. Nonlinear simulations show the performances of the controller in the presence of plasma vertical position offsets, beta drops and power supply voltage saturation

  2. Strategies for the plasma position and shape control in IGNITOR

    International Nuclear Information System (INIS)

    Villone, F.; Albanese, R.; Ambrosino, G.; Pironti, A.; Rubinacci, G.; Ramogida, G.; Alladio, F.; Bombarda, F.; Coletti, A.; Cucchiaro, A.; Maddaluno, G.; Pizzicaroli, G.; Pizzuto, A.; Roccella, M.; Santinelli, M.; Coppi, B.

    2007-01-01

    The capability of the poloidal field coil system, as presently designed, to provide an effective vertical stabilization of the plasma in the IGNITOR machine has been investigated using the CREATE L response model. An optimization of the vertical position control strategy has been carried out and the most effective coil combination has been selected to stabilize the plasma while fulfilling engineering constraints on the coils and minimizing the required power and voltage. The growth rate of the vertical instability and the power required by the active stabilization system has been estimated with this model. The possible failure of the relevant electromagnetic diagnostics has been taken into account, evaluating the robustness of the plasma position reconstruction strategy. A realistic description of the power supply system has permitted to carry out the optimization of the proportional-integrative-derivative (PID) controller, both with a voltage and a current loop control scheme. An assessment of the requirements for the plasma cross section shape control has been carried out considering perturbations of the plasma global parameters independent of each other and showing that the undesired shape modification rejection is possible with the present PFC and power supply system. The PF coils have been rated relative to their capability to restore shape modifications due to different plasma disturbances. The most effective coil combination, that minimizes recovery time and voltage required, has been identified

  3. Strategies for the plasma position and shape control in IGNITOR

    International Nuclear Information System (INIS)

    Ramogida, G.; Alladio, F.; Albanese, R.

    2006-01-01

    The control of the plasma position and shape is a crucial issue in IGNITOR as in every compact, high field, elongated tokamak. The capability of the Poloidal Field Coil system, as presently designed, to provide an effective vertical stabilization of the plasma has been investigated using the CREATE L response model [R. Albanese, F. Villone, '' The Linearized CREATE L Plasma Response Model for the Control of Current, Position and Shape in Tokamaks '', Nucl. Fus., vol. 38, p. 723 (1998)]. This linearized MHD model assumes an axisymmetric deformable plasma described by few global parameters. An optimization of the vertical position control strategy has been carried out and the most effective coil combination has been selected to stabilize the plasma while fulfilling engineering constraints on the coils and minimizing the required power and voltage. The two pairs of coils selected for the vertical control will be fed up with up-down anti-symmetric currents provided by a dedicated supply and overlapped to the scenario currents. The growth rate of the vertical instability and the power required by the active stabilization system have been estimated with this model, indicating that it is possible to design a control system able to guarantee a stability region that includes the most interesting operation conditions. An assessment of the requirements for the plasma cross section shape control has been carried out considering independent perturbations of the plasma global parameters as disturbances and showing that the undesired shape modification rejection is possible with the present PFC and power supply system. The PF coils have been ranked with respect to their capability to restore the shape modifications due to different plasma disturbances and the most effective coil combination, that minimizes recovery time and voltage required, has been selected. In order to have additional means to monitor and control the centre of the plasma column, under demanding conditions

  4. A Toroidally Symmetric Plasma Simulation code for design of position and shape control on tokamak plasmas

    International Nuclear Information System (INIS)

    Takase, Haruhiko; Senda, Ikuo

    1999-01-01

    A Toroidally Symmetric Plasma Simulation (TSPS) code has been developed for investigating the position and shape control on tokamak plasmas. The analyses of three-dimensional eddy currents on the conducting components around the plasma and the two-dimensional magneto-hydrodynamic (MHD) equilibrium are taken into account in this code. The code can analyze the plasma position and shape control during the minor disruption in which the deformation of plasma is not negligible. Using the ITER (International Thermonuclear Experimental Reactor) parameters, some examples of calculations are shown in this paper. (author)

  5. Creation and control of variably shaped plasmas in TCV

    International Nuclear Information System (INIS)

    Hofmann, F.; Lister, J.B.; Anton, M.

    1994-01-01

    During the first year of operation, the TCV tokamak has produced a large variety of plasma shapes and magnetic configurations, with 1.0≤B tor ≤1.46T, I p ≤800kA, k≤2.05, -0.7≤δ ≤0.7. A new shape control algorithm, based on a finite element reconstruction of the plasma current in real time, has been implemented. Vertical growth rates of 800 sec -1 , corresponding to a stability margin f=1.15, have been stabilized. Ohmic H-modes, with energy confinement times reaching 80ms, normalized beta (β tor aB/I p ) of 1.9 and τ E /ITER89-P of 2.4 have been obtained in single-null X-point deuterium discharges with the ion grad B drift towards the X-point. Limiter H-modes with maximum line averaged electron densities of 1.7x10 20 m -3 have been observed in D-shaped plasmas with 360kA≤I p ≤600kA. (Author)

  6. Plasma position and shape control device for thermonuclear device

    International Nuclear Information System (INIS)

    Takeuchi, Kazuhiro; Abe, Mitsushi; Kinoshita, Shigemi.

    1993-01-01

    A plasma position and shape control system is constituted with a measuring device, a quenching probability calculation section and a control calculation section. A quenching probability is calculated in the quenching probability calculation section by using a measuring data on temperature, electric current and magnetic field of superconductive coils, based on a margin upto a limit value. The control calculation section selects a control method which decreases applied voltage or current instruction value as the quenching probability of the coils is higher. Since the quenching probability of the superconductive coils can be forecast and a state of low quenching danger can be selected, the safety of the device is improved. When the quenching danger is allowed to a predetermined value, a wide operation region can be provided. (N.H.)

  7. Plasma shape control calculations for BPX divertor design

    International Nuclear Information System (INIS)

    Strickler, D.J.; Neilson, G.H.; Jardin, S.C.; Pomphrey, N.

    1991-01-01

    The Burning Plasma Experiment (BPX) divertor is to be capable of withstanding heat loads corresponding to ignited operation and 500 MW of fusion power for a current rise time and flattop lasting several seconds. The poloidal field (PF), diagnostic, and feedback equilibrium control systems must provide precise X-point position control in order to sweep the separatrices across the divertor target surface and optimally distribute the heat loads. A control matrix MHD equilibrium code, BEQ, and the Tokamak Simulation Code (TSC) are used to compute preprogrammed double-null (DN) divertor sweep trajectories that maximize sweep distance while simultaneously satisfying a set of strict constraints: minimum lengths of the field lines between the X-point and strike points, minimum spacing between the inboard plasma edge and the limiter, maximum spacing between the outboard plasma edge and the ICRF antennas, minimum safety factor, and linked poloidal flux. A sequence of DN diverted equilibria and a consistent TSC fiducial discharge simulation are used in evaluating the performance of the BPX divertor shape and possible modifications. 5 refs., 10 figs

  8. Linear quadratic Gaussian controller design for plasma current, position and shape control system in ITER

    International Nuclear Information System (INIS)

    Belyakov, V.; Kavin, A.; Rumyantsev, E.; Kharitonov, V.; Misenov, B.; Ovsyannikov, A.; Ovsyannikov, D.; Veremei, E.; Zhabko, A.; Mitrishkin, Y.

    1999-01-01

    This paper is focused on the linear quadratic Gaussian (LQG) controller synthesis methodology for the ITER plasma current, position and shape control system as well as power derivative management system. It has been shown that some poloidal field (PF) coils have less influence on reference plasma-wall gaps control during plasma disturbances and hence they have been used to reduce total control power derivative by means of the additional non-linear feedback. The design has been done on the basis of linear models. Simulation was provided for non-linear model and results are presented and discussed. (orig.)

  9. Design and analysis of plasma position and shape control in superconducting tokamak JT-60SC

    Energy Technology Data Exchange (ETDEWEB)

    Matsukawa, M. E-mail: matsukaw@naka.jaeri.go.jp; Ishida, S.; Sakasai, A.; Urata, K.; Senda, I.; Kurita, G.; Tamai, H.; Sakurai, S.; Miura, Y.M.; Masaki, K.; Shimada, K.; Terakado, T

    2003-09-01

    The analyses of the plasma position and shape control in the superconducting tokamak JT-60SC in JAERI are presented. The vacuum vessel and stabilizing plates located closely to the plasma are modeled in 3 dimension, and we can take into account the large ports in the vacuum vessel. The linear numerical model used in the design for the plasma feedback control system is based on Grad-Shafranov equation, which allows the plasma surface deformation. For a slower control of the plasma shape, the superconducting equilibrium field (EF) coils outside toroidal field coils are used, while for a fast control of the plasma position, in-vessel normal conducting coils (IV coil) are used. It is shown that the available loop voltages of the EF and IV coils are very limited, but there are sufficient accuracy and acceptable response time of plasma position and shape control.

  10. Design and analysis of plasma position and shape control in superconducting tokamak JT-60SC

    International Nuclear Information System (INIS)

    Matsukawa, M.; Ishida, S.; Sakasai, A.; Urata, K.; Senda, I.; Kurita, G.; Tamai, H.; Sakurai, S.; Miura, Y.M.; Masaki, K.; Shimada, K.; Terakado, T.

    2003-01-01

    The analyses of the plasma position and shape control in the superconducting tokamak JT-60SC in JAERI are presented. The vacuum vessel and stabilizing plates located closely to the plasma are modeled in 3 dimension, and we can take into account the large ports in the vacuum vessel. The linear numerical model used in the design for the plasma feedback control system is based on Grad-Shafranov equation, which allows the plasma surface deformation. For a slower control of the plasma shape, the superconducting equilibrium field (EF) coils outside toroidal field coils are used, while for a fast control of the plasma position, in-vessel normal conducting coils (IV coil) are used. It is shown that the available loop voltages of the EF and IV coils are very limited, but there are sufficient accuracy and acceptable response time of plasma position and shape control

  11. Plasma shape control by pulsed solenoid on laser ion source

    International Nuclear Information System (INIS)

    Sekine, M.; Ikeda, S.; Romanelli, M.; Kumaki, M.; Fuwa, Y.; Kanesue, T.; Hayashizaki, N.; Lambiase, R.; Okamura, M.

    2015-01-01

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. However, it was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. This approach may also be useful to reduce beam emittance of a LIS

  12. Plasma shape control by pulsed solenoid on laser ion source

    Science.gov (United States)

    Sekine, M.; Ikeda, S.; Romanelli, M.; Kumaki, M.; Fuwa, Y.; Kanesue, T.; Hayashizaki, N.; Lambiase, R.; Okamura, M.

    2015-09-01

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. However, it was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. This approach may also be useful to reduce beam emittance of a LIS.

  13. Plasma shape control by pulsed solenoid on laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Sekine, M. [Tokyo Institute of Technology, Meguro-ku, Tokyo 2-12-1 (Japan); RIKEN, Wako, Saitama 351-0198 (Japan); Ikeda, S. [Tokyo Institute of Technology, Yokohama, Kanagawa 226-8502 (Japan); RIKEN, Wako, Saitama 351-0198 (Japan); Romanelli, M. [Cornell University, Ithaca, NY 14850 (United States); Kumaki, M. [RIKEN, Wako, Saitama 351-0198 (Japan); Waseda University, Shinjuku, Tokyo 169-0072 (Japan); Fuwa, Y. [RIKEN, Wako, Saitama 351-0198 (Japan); Kyoto University, Uji, Kyoto 611-0011 (Japan); Kanesue, T. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Hayashizaki, N. [Tokyo Institute of Technology, Meguro-ku, Tokyo 2-12-1 (Japan); Lambiase, R. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Okamura, M. [RIKEN, Wako, Saitama 351-0198 (Japan); Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2015-09-21

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. However, it was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. This approach may also be useful to reduce beam emittance of a LIS.

  14. Studies on performances of the control system of plasma position and shape

    International Nuclear Information System (INIS)

    Aikawa, Hiroshi; Tsuzuki, Naohisa; Kimura, Toyoaki; Ogata, Atsushi; Ninomiya, Hiromasa

    1978-09-01

    Performance in the control system of plasma position and shape is determined by estimating the disturbing field, system functions and load variation of the controlled object. Various stray fields are considered as disturbing field. Plasma internal inductance and poloidal beta are taken into consideration as load variation of the controlled object. The required performance is obtained through considerations of plasma equilibrium, stability, impurity concentration and sensors accuracy. The results are described as requests to the poloidal power supply system. (author)

  15. Toward a design for the ITER plasma shape and stability control system

    International Nuclear Information System (INIS)

    Humphreys, D.A.; Leuer, J.A.; Kellman, A.G.; Haney, S.W.; Bulmer, R.H.; Pearlstein, L.D.; Portone, A.

    1994-07-01

    A design strategy for an integrated shaping and stability control algorithm for ITER is described. This strategy exploits the natural multivariable nature of the system so that all poloidal field coils are used to simultaneously control all regulated plasma shape and position parameters. A nonrigid, flux-conserving linearized plasma response model is derived using a variational procedure analogous to the ideal MHD Extended Energy Principle. Initial results are presented for the non-rigid plasma response model approach applied to an example DIII-D equilibrium. For this example, the nonrigid model is found to yield a higher passive growth rate than a rigid current-conserving plasma response model. Multivariable robust controller design methods are discussed and shown to be appropriate for the ITER shape control problem

  16. Real-time digital control of plasma position and shape on the TEXTOR tokamak

    International Nuclear Information System (INIS)

    Mitri, Mikhael

    2009-01-01

    Beside the objective of contributing to the controlled thermonuclear fusion research and ultimately the development of a fusion based power plant, the main objectives of the thesis are a substantial improvement of plasma vertical position control and plasma shape control as well as a better understanding of formerly unexplained effects, e.g. disturbance fields. As for the vertical position control, a deep analysis has to be undertaken to identify the problem sources. Accurate control of the plasma position is very difficult to achieve. This is mainly due to the complexity of the tokamak and the difficulty in measuring or modelling all relevant discharge variables. Any models would be highly nonlinear and time varying. Thus, for simulation and controller design, a simplified, but nevertheless accurate model has to be developed, based on physics and measured data of the process. Furthermore, the quality of the measured position has to be improved by using new inductive sensors, integrators, and hardware. The integration drift problem has to be analysed and resolved by developing a drift-free integration method. Concerning the shape control, a better understanding of the relation between the stray fields and the iron core saturation is required. Furthermore, the influence on the plasma elongation has to be determined. Upon this, a shape compensation algorithm has to be developed accordingly. The accuracy of the shape control has to be better than 1%. (orig.)

  17. Feedback control of horizontal position and plasma surface shape in a non-circular tokamak

    International Nuclear Information System (INIS)

    Moriyama, Shin-ichi; Nakamura, Kazuo; Nakamura, Yukio; Itoh, Satoshi

    1986-01-01

    The linear model for the coupled horizontal position and plasma surface shape control in the non-circular tokamak device was described. It enables us to estimate easily the displacement and the distortion due to the changes in plasma pressure and current density distribution. The PI-controller and the optimal regulator were designed with the linear model. Transient-response analysis of the control system in the TRIAM-1M tokamak showed that the optimal regulator is superior to the PI-controller with regard to the mutual-interference between the position control system and the elongation control system. (author)

  18. Control of plasma poloidal shape and position in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Walker, M.L.; Humphreys, D.A.; Ferron, J.R.

    1997-11-01

    Historically, tokamak control design has been a combination of theory driving an initial control design and empirical tuning of controllers to achieve satisfactory performance. This approach was in line with the focus of past experiments on simply obtaining sufficient control to study many of the basic physics issues of plasma behavior. However, in recent years existing experimental devices have required increasingly accurate control. New tokamaks such as ITER or the eventual fusion power plant must achieve and confine burning fusion plasmas, placing unprecedented demands on regulation of plasma shape and position, heat flux, and burn characteristics. Control designs for such tokamaks must also function well during initial device operation with minimal empirical optimization required. All of these design requirements imply a heavy reliance on plasma modeling and simulation. Thus, plasma control design has begun to use increasingly modern and sophisticated control design methods. This paper describes some of the history of plasma control for the DIII-D tokamak as well as the recent effort to implement modern controllers. This effort improves the control so that one may obtain better physics experiments and simultaneously develop the technology for designing controllers for next-generation tokamaks

  19. Plasma Shape Control on the National Spherical Torus Experiment using Real-time Equilibrium Reconstruction

    International Nuclear Information System (INIS)

    Gates, D.A.; Ferron, J.R.; Bell, M.; Gibney, T.; Johnson, R.; Marsala, R.J.; Mastrovito, D.; Menard, J.E.; Mueller, D.; Penaflor, B.; Sabbagh, S.A.; Stevenson, T.

    2005-01-01

    Plasma shape control using real-time equilibrium reconstruction has been implemented on the National Spherical Torus Experiment (NSTX). The rtEFIT code originally developed for use on DIII-D was adapted for use on NSTX. The real-time equilibria provide calculations of the flux at points on the plasma boundary, which is used as input to a shape control algorithm known as isoflux control. The flux at the desired boundary location is compared to a reference flux value, and this flux error is used as the basic feedback quantity for the poloidal-field coils on NSTX. The hardware that comprises the control system is described, as well as the software infrastructure. Examples of precise boundary control are also presented

  20. Magnetic sensorless control of plasma position and shape in a tokamak

    International Nuclear Information System (INIS)

    Nakamura, K.; Luo, J.R.; Wang, H.Z.

    2005-01-01

    Magnetic sensorless sensing and control experiments of the plasma horizontal position have been carried out in the superconducting tokamak HT-7. The sensing is made focusing on the ripple frequency component of the power supply with thyristor and directly from them without time integration. There is no drift problem of integrator of magnetic sensors. Two kinds of control experiments were carried out, to keep the position constant and swing the position in a triangular waveform. And magnetic sensorless sensing of plasma shape is discussed. (author)

  1. Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U

    Science.gov (United States)

    Boyer, M. D.; Battaglia, D. J.; Mueller, D.; Eidietis, N.; Erickson, K.; Ferron, J.; Gates, D. A.; Gerhardt, S.; Johnson, R.; Kolemen, E.; Menard, J.; Myers, C. E.; Sabbagh, S. A.; Scotti, F.; Vail, P.

    2018-03-01

    The upgrade to the National Spherical Torus eXperiment (NSTX-U) included two main improvements: a larger center-stack, enabling higher toroidal field and longer pulse duration, and the addition of three new tangentially aimed neutral beam sources, which increase available heating and current drive, and allow for flexibility in shaping power, torque, current, and particle deposition profiles. To best use these new capabilities and meet the high-performance operational goals of NSTX-U, major upgrades to the NSTX-U control system (NCS) hardware and software have been made. Several control algorithms, including those used for real-time equilibrium reconstruction and shape control, have been upgraded to improve and extend plasma control capabilities. As part of the commissioning phase of first plasma operations, the shape control system was tuned to control the boundary in both inner-wall limited and diverted discharges. It has been used to accurately track the requested evolution of the boundary (including the size of the inner gap between the plasma and central solenoid, which is a challenge for the ST configuration), X-point locations, and strike point locations, enabling repeatable discharge evolutions for scenario development and diagnostic commissioning.

  2. Design and operation of the RFX-mod plasma shape control system

    Energy Technology Data Exchange (ETDEWEB)

    Marchiori, G., E-mail: giuseppe.marchiori@igi.cnr.it [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy); Finotti, C. [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy); Kudlacek, O. [Università di Padova, Padova (Italy); Villone, F. [Dipartimento di Ingegneria Elettrica e dell’Informazione (DIEI), Università di Cassino (Italy); Zanca, P. [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy); Abate, D. [Dipartimento di Ingegneria Elettrica e dell’Informazione (DIEI), Università di Cassino (Italy); Cavazzana, R. [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy); Jackson, G.L.; Luce, T.C. [General Atomics, San Diego, CA (United States); Marrelli, L. [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy)

    2016-10-15

    Highlights: • Linearized plasma response model of RFX-mod Tokamak Double/Single Null discharges. • Model based design of a vertical stability control system. • Model based design of a plasma shape LQG control system with Kalman state estimator. • Real time plasma boundary reconstruction algorithm. • Tracking and disturbance rejection experimental tests. - Abstract: The aim of executing Single Null discharges in RFX-mod operating as a Tokamak led to the design and implementation of a plasma shape feedback control system. A fully model-based approach was followed which allowed dealing with critical issues such as the presence of a conducting shell, the strong coupling of the poloidal field coils and the voltage limits of the power supplies. A Linear Quadratic regulator and a Kalman state estimator were designed and implemented in the real time MARTe framework together with an algorithm for the real-time plasma boundary reconstruction. The problem of a number of sensors along the poloidal direction adequate only for circular discharges was also successfully tackled. The development of the system and its performances in terms of tracking and disturbance rejection capability are presented in the paper.

  3. Improving plasma shaping accuracy through consolidation of control model maintenance, diagnostic calibration, and hardware change control

    International Nuclear Information System (INIS)

    Baggest, D.S.; Rothweil, D.A.; Pang, S.

    1995-12-01

    With the advent of more sophisticated techniques for control of tokamak plasmas comes the requirement for increasingly more accurate models of plasma processes and tokamak systems. Development of accurate models for DIII-D power systems, vessel, and poloidal coils is already complete, while work continues in development of general plasma response modeling techniques. Increased accuracy in estimates of parameters to be controlled is also required. It is important to ensure that errors in supporting systems such as diagnostic and command circuits do not limit the accuracy of plasma parameter estimates or inhibit the ability to derive accurate plasma/tokamak system models. To address this issue, we have developed more formal power systems change control and power system/magnetic diagnostics calibration procedures. This paper discusses our approach to consolidating the tasks in these closely related areas. This includes, for example, defining criteria for when diagnostics should be re-calibrated along with required calibration tolerances, and implementing methods for tracking power systems hardware modifications and the resultant changes to control models

  4. Real-time Equilibrium Reconstruction and Isoflux Control of Plasma Shape and Position in the National Spherical Torus Experiment (NSTX)

    International Nuclear Information System (INIS)

    Mueller, D.; Gates, D.A.; Menard, J.E.; Ferron, J.R.; Sabbagh, S.A.

    2004-01-01

    The implementation of the rtEFIT-isoflux algorithm in the digital control system for NSTX has led to improved ability to control the plasma shape. In particular, it has been essential for good gap control for radio-frequency experiments, for control of drsep in H-mode studies, and for X-point height control and κ control in a variety of experiments

  5. Optimization and control of the plasma shape and current profile in noncircular cross-section tokamaks

    International Nuclear Information System (INIS)

    Moore, R.W.; Bernard, L.C.; Chan, V.S.; Davidson, R.H.; Dobrott, D.R.; Helton, F.J.; Miller, R.L.; Pfeiffer, W.; Waltz, R.E.; Wang, T.S.

    1980-06-01

    High-β equilibria which are stable to all ideal MHD modes are found by optimizing the plasma shape and current profile for doublets, up-down asymmetric dees, and symmetric dees. The ideal MHD stability of these equilibria for low toroidal mode number n is analyzed with a global MHD stability code, GATO. The stability to high-n modes is analyzed with a localized ballooning code, BLOON. The attainment of high β is facilitated by an automated optimization search on shape and current parameters. The equilibria are calculated with a free-boundary equilibrium code using coils appropriate for the Doublet III experimental device. The optimal equilibria are characterized by broad current profiles with values of β/sub poloidal/ approx. =1. Experimental realization of the shapes and current profiles giving the highest β limits is explored with a 1 1/2-D transport code, which simulates the time evolution of the 2-D MHD equilibrium while calculating consistent current profiles from a 1-D transport model. Transport simulations indicate that nearly optimal shapes may be obtained provided that the currents in the field-shaping coils are appropriately programmed and the plasma current profile is sufficiently broad. Obtaining broad current profiles is possible by current ramping, neutral beam heating, and electron cyclotron heating. With combinations of these techniques it is possible to approach the optimum β predicted by the MHD theory

  6. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    International Nuclear Information System (INIS)

    Gilmore, Mark Allen

    2017-01-01

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB's)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB's] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  7. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, Mark Allen [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-02-05

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB’s)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB’s] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  8. ITER-FEAT magnetic configuration and plasma position/shape control in the nominal PF scenario

    International Nuclear Information System (INIS)

    Gribov, Y.V.; Albanese, R.; Ambrosino, G.

    2001-01-01

    The capability of the ITER-FEAT poloidal field system to support the four 'design' scenarios and the high current 'assessed' scenario have been studied. To operate with highly elongated plasma, the system has segmentation of the central solenoid and a separate fast feedback loop for plasma vertical stabilisation. Within the limits imposed on the coil currents, voltages and power, the poloidal field system provides the required plasma scenario and control capabilities. The separatrix deviation from the required position, in scenarios with minor disruptions is within less than about 100 mm. (author)

  9. Plasma control device

    International Nuclear Information System (INIS)

    Matsutomi, Akiyoshi.

    1995-01-01

    Plasma position and shape estimation values are outputted based on measured values of coil current. When the measured values of the position and the shape are judged to be abnormal, position and shape estimation values estimated by a plasma position and shape estimation means are outputted as position and shape feed back values to a plasma position and shape control means instead of the position and shape measured values. Since only a portion of the abnormal position and shape measured values may also be replaced with the position and shape estimation values, errors in the plasma position and shape feed back values can be reduced as a whole. In addition, even if the position and shape measured values are abnormal or if they can not be measured, plasma control can be continued by alternative position and shape estimation values, thereby enabling to avoid interruption of plasma control. Since the position and shape estimation values are obtained not only with the measured values of coil current but also with the position and shape estimation values, the accuracy is improved. Further, noises superposed on the position and shape measured values are filtered, and the device is stabilized compared with a prior art device. (N.H.)

  10. Final Technical Report: Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Eugenio

    2014-05-02

    The strong coupling between the different physical variables involved in the plasma transport phenomenon and the high complexity of its dynamics call for a model-based, multivariable approach to profile control where those predictive models could be exploited. The overall objective of this project has been to extend the existing body of work by investigating numerically and experimentally active control of unstable fluctuations, including fully developed turbulence and the associated cross-field particle transport, via manipulation of flow profiles in a magnetized laboratory plasma device. Fluctuations and particle transport can be monitored by an array of electrostatic probes, and Ex B flow profiles can be controlled via a set of biased concentric ring electrodes that terminate the plasma column. The goals of the proposed research have been threefold: i- to develop a predictive code to simulate plasma transport in the linear HELCAT (HELicon-CAThode) plasma device at the University of New Mexico (UNM), where the experimental component of the proposed research has been carried out; ii- to establish the feasibility of using advanced model-based control algorithms to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles, iii- to investigate the fundamental nonlinear dynamics of turbulence and transport physics. Lehigh University (LU), including Prof. Eugenio Schuster and one full-time graduate student, has been primarily responsible for control-oriented modeling and model-based control design. Undergraduate students have also participated in this project through the National Science Foundation Research Experience for Undergraduate (REU) program. The main goal of the LU Plasma Control Group has been to study the feasibility of controlling turbulence-driven transport by shaping the radial poloidal flow profile (i.e., by controlling flow shear) via biased concentric ring electrodes.

  11. Optimization and control of plasma shape and current profile in non-circular cross-section tokamaks

    International Nuclear Information System (INIS)

    Moore, R.W.; Bernard, L.C.; Chan, V.S.

    1981-01-01

    Tokamaks with elongated, non-circular cross-sections are under consideration as fusion reactors because they have the potential for stable operation at high β. Ideal MHD theory, however, predicts that careful current profile control will be required to achieve the potential high-β advantages of non-circular cross-sections. In this paper, high-β equilibria which are stable to all ideal MHD modes are found by optimizing the plasma shape and current profile for doublets, up-down asymmetric dees, and symmetric dees. The ideal MHD stability of these equilibria for low toroidal mode number n is analysed with a global MHD stability code, GATO. The stability to high-n modes is analysed with a localized ballooning code, BLOON. The attainment of high β is facilitated by an automated optimization search on shape and current parameters. The equilibria are calculated with a free-boundary equilibrium code using coils appropriate for the Doublet III experimental device. The optimal equilibria are characterized by broad current profiles with values of βsub(poloidal) approximately equal to 1. Experimental realization of the shapes and current profiles giving the highest β limits is explored with a 1 1/2-D transport code, which simulates the time evolution of the 2-D MHD equilibrium while calculating consistent current profiles from a 1-D transport model. Transport simulations indicate that nearly optimal shapes may be obtained provided that the currents in the field-shaping coils are appropriately programmed and the plasma current profile is sufficiently broad. Obtaining broad current profiles is possible by current ramping, neutral-beam heating, and electron-cyclotron heating. With combinations of these techniques it is possible to approach the optimum β predicted by the MHD theory. (author)

  12. Formation of polyhedral ceria nanoparticles with enhanced catalytic CO oxidation activity in thermal plasma via a hydrogen mediated shape control mechanism

    International Nuclear Information System (INIS)

    Zheng Jie; Zhang Yaohua; Song Xubo; Li Xingguo

    2011-01-01

    Ceria nanoparticles with well defined facets are prepared in argon–hydrogen thermal plasma followed by controlled oxidation. With increasing hydrogen fraction in the plasma, a clear sphere-to-polyhedron shape transition is observed. The heat released during the hydrogenation of cerium, which significantly enhances the species mobility on the surface, favors the growth of well defined facets. The polyhedron ceria nanoparticles, though lower in specific surface area, exhibit superior catalytic performance for CO oxidation over the round particles, which is attributed to the higher density of the reactive {200} and {220} facets on the surface. The hydrogen mediated shape control mechanism provides new insights into the shape control of nanoparticles during thermal plasma processing.

  13. Spectral Line Shapes in Plasmas and Gases

    International Nuclear Information System (INIS)

    Oks, E.; Dalimier, D.; Stamm, R.; Stehle, CH.; Gonzalez, M.A.

    2011-01-01

    The subject of spectral line shapes (SLS), a.k.a. spectral line broadening, which embraces both shapes and shifts of spectral lines, is of both fundamental and practical importance. On the fundamental side, the study of the spectral line profiles reveals the underlying atomic and molecular interactions. On the practical side, the spectral line profiles are employed as powerful diagnostic tools for various media, such as neutral gases, technological gas discharges, magnetically confined plasmas for fusion, laser- and Z-pinch-produced plasmas (for fusion and other purposes), astrophysical plasmas (most importantly, solar plasmas), and planetary atmospheres. The research area covered by this special issue includes both the SLS dominated by various electric fields (including electron and ion micro fields in strongly ionized plasmas) and the SLS controlled by neutral particles. In the physical slang, the former is called plasma broadening while the latter is called neutral broadening (of course, the results of neutral broadening apply also to the spectral line broadening in neutral gases)

  14. The control of TCV plasmas

    International Nuclear Information System (INIS)

    Lister, J.B.; Hofmann, F.; Moret, J.M.

    1996-07-01

    The general control of tokamak plasmas has evolved considerably over the last few years with an increase in the plasma pulse length, an increase in the control of additional heating and fuelling and an increase in the degree to which the shape of the plasma can be varied. The TCV tokamak is specifically designed to explore the operational benefits of plasma shaping over a wide variety of plasma shapes. Consequently, considerable attention has been given to the control of the poloidal field coil currents which impose the desired shape. This paper deals with all aspects of the control of TCV plasmas, from the diagnostic measurements to the power supplies, via control algorithms and overall supervision. (author) 44 figs., tabs., 25 refs

  15. The control of TCV plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lister, J B; Hofmann, F; Moret, J M [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); and others

    1996-07-01

    The general control of tokamak plasmas has evolved considerably over the last few years with an increase in the plasma pulse length, an increase in the control of additional heating and fuelling and an increase in the degree to which the shape of the plasma can be varied. The TCV tokamak is specifically designed to explore the operational benefits of plasma shaping over a wide variety of plasma shapes. Consequently, considerable attention has been given to the control of the poloidal field coil currents which impose the desired shape. This paper deals with all aspects of the control of TCV plasmas, from the diagnostic measurements to the power supplies, via control algorithms and overall supervision. (author) 44 figs., tabs., 25 refs.

  16. Evolution of pulse shapes during compressor scans in a CPA system and control of electron acceleration in plasmas

    International Nuclear Information System (INIS)

    Toth, Csaba; Groot, Joeri de; Tilborg, Jeroen van; Geddes, Cameron G.R.; Faure, Jerome; Catravas, Palma; Schroeder, Carl; Shadwick, B.A.; Esarey, Eric; Leemans, Wim

    2002-01-01

    The skewness of the envelope function of 20 - 100 femtosecond Ti:sapphire laser pulses has been controlled by appropriate choice of the higher order special phase coefficients, and used for optimization of a plasma wakefield electron accelerator

  17. Plasma shape experiments for an optimized tokamak

    International Nuclear Information System (INIS)

    Hyatt, A.W.; Osborne, T.H.; Lazarus, E.A.

    1994-07-01

    In this paper we present results from recent experiments at DIII-D which measured the plasma stability and confinement performance product, βτ E , in one previously studied and three new plasma shapes. One important goal of these experiments was to identify performance vs shape trends which would identify a shape compatible with both high performance and the planned effort to decrease the power flux to the divertor floor using a closed ''slot'' divertor geometry. power flux to the divertor floor using a closed ''slot'' divertor geometry. The closed divertor hardware must be designed for a reduced set of plasma shapes, so care must be taken to choose the shape that optimizes βτ E and divertor performance. The four shapes studied form a matrix of moderate and high elongations (κ congruent 1.8 and 2.1) and low and high triangularities (δ congruent 0.3 and 0.9). All configurations were double-null diverted (DND), held fixed during a shot, with neutral beam heating. The shapes span a range of X-point locations compatible with the envisioned closed divertor. We find that from shape to shape, a shot's transient normalized performance, β N H, where β N ≡ β/(I p )/aB T and H ≡ τ E /τ E ITER-89P , increases strongly with triangularity, but depends only weakly on elongation. However, the normalized performance during quasi stationary ELMing H-mode, to which these discharges eventually relax, is insensitive to both triangularity and elongation. The moderate elongation, high triangularity DND shape is shown to be near optimum for future studies on DIII-D

  18. Plasma shape experiments for an optimized tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Hyatt, A.W.; Osborne, T.H. [General Atomics, San Diego, CA (United States); Lazarus, E.A. [Oak Ridge National Lab., TN (United States)

    1994-12-31

    In this paper we present results from recent experiments at DIII-D which measured the plasma stability and confinement performance product, {beta}{sub {tau}E}, in one previously studied and three new plasma shapes. One important goal of these experiments was to identify performance vs shape trends which would identify a shape compatible with both high performance and the planned effort to decrease the power flux to the divertor floor using a closed `slot` divertor geometry. The closed divertor hardware must be designed for a reduced set of plasma shapes, so care must be taken to choose the shape that optimizes {beta}{sub {tau}E} and divertor performance. The four shapes studied form a matrix of moderate and high elongations ({kappa} {approx_equal} 1.8 and 2.1) and low and high triangularities ({delta} {approx_equal} 0.3 and 0.9). All configurations were double-null diverted (DND), held fixed during a shot, with neutral beam heating. The shapes span a range of X-point locations compatible with the envisioned closed divertor. We find that from shape to shape, a shot`s transient normalized performance, {beta}{sub N}H, where {beta}{sub N} = {beta}/(I{sub p}/aB{sub T}) and H = {tau}{sub E}/{tau}{sub E}{sup ITER-89P}, increases strongly with triangularity, but depends only weakly on elongation. However, the normalized performance during quasi stationary ELMing H-mode, to which these discharges eventually relax, is insensitive to both triangularity and elongation. The moderate elongation, high triangularity DND shape is shown to be near optimum for future studies on DIII-D. (author) 7 refs., 7 figs.

  19. Comparison of edge plasma perturbation during ELM control using one vs. two toroidal rows of RMP coils in ITER similar shaped plasmas on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermacher, M.E., E-mail: fenstermacher@fusion.gat.co [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Evans, T.E.; Osborne, T.H.; Schaffer, M.J.; DeGrassie, J.S.; Gohil, P.; Groebner, R.J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Moyer, R.A. [University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093 (United States)

    2009-06-15

    Large Type-I edge localized modes (ELMs) were suppressed by n = 3 resonant magnetic perturbations (RMPs) from a set of internal coils in plasmas with an ITER similar shape at the ITER pedestal collisionality, nu{sub e}*approx0.1 and low edge safety factor (q{sub 95} approx 3.6), with either a single toroidal row of the internal RMP coils or two poloidally separated rows of coils. ELM suppression with a single row of internal coils was achieved at approximately the same q{sub 95} surface-averaged perturbation field as with two rows of coils, but required higher current per coil. Maintaining complete suppression of ELMs using n = 3 RMPs from a single toroidal row of internal coils was less robust to variations in input neutral beam injection torque than previous ELM suppression cases using both rows of internal coils. With either configuration of RMP coils, maximum ELM size is correlated with the width of the edge region having good overlap of the magnetic islands from vacuum field calculations.

  20. Shapes of agglomerates in plasma etching reactors

    International Nuclear Information System (INIS)

    Huang, F.Y.; Kushner, M.J.

    1997-01-01

    Dust particle contamination of wafers in reactive ion etching (RIE) plasma tools is a continuing concern in the microelectronics industry. It is common to find that particles collected on surfaces or downstream of the etch chamber are agglomerates of smaller monodisperse spherical particles. The shapes of the agglomerates vary from compact, high fractal dimension structures to filamentary, low fractal dimension structures. These shapes are important with respect to the transport of particles in RIE tools under the influence electrostatic and ion drag forces, and the possible generation of polarization forces. A molecular dynamics simulation has been developed to investigate the shapes of agglomerates in plasma etching reactors. We find that filamentary, low fractal dimension structures are generally produced by smaller (<100s nm) particles in low powered plasmas where the kinetic energy of primary particles is insufficient to overcome the larger Coulomb repulsion of a compact agglomerate. This is analogous to the diffusive regime in neutral agglomeration. Large particles in high powered plasmas generally produce compact agglomerates of high fractal dimension, analogous to ballistic agglomeration of neutrals. copyright 1997 American Institute of Physics

  1. Tokamak plasma shape identification based on the boundary integral equations

    International Nuclear Information System (INIS)

    Kurihara, Kenichi; Kimura, Toyoaki

    1992-05-01

    A necessary condition for tokamak plasma shape identification is discussed and a new identification method is proposed in this article. This method is based on the boundary integral equations governing a vacuum region around a plasma with only the measurement of either magnetic fluxes or magnetic flux intensities. It can identify various plasmas with low to high ellipticities with the precision determined by the number of the magnetic sensors. This method is applicable to real-time control and visualization using a 'table-look-up' procedure. (author)

  2. Online Plasma Shape Reconstruction for EAST Tokamak

    International Nuclear Information System (INIS)

    Luo Zhengping; Xiao Bingjia; Zhu Yingfei; Yang Fei

    2010-01-01

    An online plasma shape reconstruction, based on the offline version of the EFIT code and MPI library, can be carried out between two adjacent shots in EAST. It combines online data acquisition, parallel calculation, and data storage together. The program on the master node of the cluster detects the termination of the discharge promptly, reads diagnostic data from the EAST mdsplus server on the completion of data storing, and writes the results onto the EFIT mdsplus server after the calculation is finished. These processes run automatically on a nine-nodes IBM blade center. The total time elapsed is about 1 second to several minutes, depending on the duration of the shot. With the results stored in the mdsplus server, it is convenient for operators and physicists to analyze the behavior of plasma using visualization tools.

  3. Suitable spectral line shape calculations for inertial confinement plasma diagnosis

    International Nuclear Information System (INIS)

    Lambert, D.; Louis-Jacquet, M.

    1982-09-01

    In plasma confinement experiments, the knowledge of the plasma state at the maximum compression time would be of utmost interest. For quite many experiments, this time can correspond to a stationary state during which the X emission conditions for a moderate Z element are maximum. Since this diagnosis mean deals with emission only, we need to get rid of reabsorption problems, since their calculation depends on the use of an ionization-excitation plasma model. That is the reason why we focus our attention onto the aspects of spectroscopic theory which control the low reabsorption line shapes - from high values of n - and more precisely the lesser reabsorbed parts of the line shapes - the wings instead of the center

  4. Shaping of pulses in optical grating-based laser systems for optimal control of electrons in laser plasma wake-field accelerator

    International Nuclear Information System (INIS)

    Toth, Cs.; Faure, J.; Geddes, C.G.R.; Tilborg, J. van; Leemans, W.P.

    2003-01-01

    In typical chirped pulse amplification (CPA) laser systems, scanning the grating separation in the optical compressor causes the well know generation of linear chirp of frequency vs. time in a laser pulse, as well as a modification of all the higher order phase terms. By setting the compressor angle slightly different from the optimum value to generate the shortest pulse, a typical scan around this value will produce significant changes to the pulse shape. Such pulse shape changes can lead to significant differences in the interaction with plasmas such as used in laser wake-field accelerators. Strong electron yield dependence on laser pulse shape in laser plasma wake-field electron acceleration experiments have been observed in the L'OASIS Lab of LBNL [1]. These experiments show the importance of pulse skewness parameter, S, defined here on the basis of the ratio of the ''head-width-half-max'' (HWHM) and the ''tail-width-halfmax'' (TWHM), respectively

  5. Extremely shaped plasmas to improve the Tokamak concept

    Energy Technology Data Exchange (ETDEWEB)

    Piras, F.

    2011-04-15

    experimental activity of the Tokamak à Configuration Variable (TCV) mainly focuses on the research of optimized plasma shapes capable of improving the global performance and solve the technological challenges of a tokamak reactor. Several theoretical and experimental results show the importance of the plasma shape in tokamaks. The maximum value of β (an indicator of the confinement efficiency) is for example related to the ratio between the height and the width of the plasma. The plasma shape can also affect the power necessary to access improved confinement regimes, as well as the plasma stability. This thesis reports on a contribution towards the optimization of the tokamak plasma shape. In particular, it describes the theoretical and experimental studies carried out in the TCV tokamak on two innovative plasma shapes: the doublet shaped plasma and the snowflake divertor. Doublet shaped plasmas have been studied in the past by the General Atomics group. Since then, the development of new plasma diagnostics and the discovery of new confinement regimes have given new reasons for interest in this unusual configuration. TCV is the only tokamak worldwide theoretically able to establish and control this configuration. This thesis illustrates new motivations for creating doublet plasmas. The vertical stability of the configuration is studied using a rigid model and the results are compared with those obtained with the KINX MHD stability code. The best strategy for controlling a doublet on TCV is also investigated, and a possible setup of the TCV control system is suggested for the doublet configuration. Analyzing the possible scenarios for doublet creation, the most promising scenario consists of the creation of two independent plasmas, which are subsequently merged to establish a doublet. For this reason, particular attention needs to be devoted to the problem of the plasma start-up. In this thesis, a general analysis of the TCV ohmic and assisted with ECH plasma start-up is

  6. Extremely shaped plasmas to improve the Tokamak concept

    International Nuclear Information System (INIS)

    Piras, F.

    2011-04-01

    experimental activity of the Tokamak à Configuration Variable (TCV) mainly focuses on the research of optimized plasma shapes capable of improving the global performance and solve the technological challenges of a tokamak reactor. Several theoretical and experimental results show the importance of the plasma shape in tokamaks. The maximum value of β (an indicator of the confinement efficiency) is for example related to the ratio between the height and the width of the plasma. The plasma shape can also affect the power necessary to access improved confinement regimes, as well as the plasma stability. This thesis reports on a contribution towards the optimization of the tokamak plasma shape. In particular, it describes the theoretical and experimental studies carried out in the TCV tokamak on two innovative plasma shapes: the doublet shaped plasma and the snowflake divertor. Doublet shaped plasmas have been studied in the past by the General Atomics group. Since then, the development of new plasma diagnostics and the discovery of new confinement regimes have given new reasons for interest in this unusual configuration. TCV is the only tokamak worldwide theoretically able to establish and control this configuration. This thesis illustrates new motivations for creating doublet plasmas. The vertical stability of the configuration is studied using a rigid model and the results are compared with those obtained with the KINX MHD stability code. The best strategy for controlling a doublet on TCV is also investigated, and a possible setup of the TCV control system is suggested for the doublet configuration. Analyzing the possible scenarios for doublet creation, the most promising scenario consists of the creation of two independent plasmas, which are subsequently merged to establish a doublet. For this reason, particular attention needs to be devoted to the problem of the plasma start-up. In this thesis, a general analysis of the TCV ohmic and assisted with ECH plasma start-up is

  7. Plasma position control device

    International Nuclear Information System (INIS)

    Takase, Haruhiko.

    1987-01-01

    Purpose: To conduct position control stably to various plasmas and reduce the burden on the control coil power source. Constitution: Among the proportional, integration and differentiation controls, a proportional-differentiation control section and an integration control section are connected in parallel. Then, a signal switching circuit is disposed to the control signal input section for the proportional-differentiation control section such that either a present position of plasmas or deviation between the present plasma position and an aimed value can be selected as a control signal depending on the control procedures or the state of the plasmas. For instance, if a rapid response is required for the control, the deviation between the present plasma position and the aimed value is selected as the input signal to conduct proportional, integration and differentiation controls. While on the other hand, if it is intended to reduce the burden on the control coil power source, it is adapted such that the control signal inputted to the proportional-differentiation control section itself can select the present plasma position. (Yoshihara, H.)

  8. Enhancement of EAST plasma control capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bingjia, E-mail: bjxiao@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei (China); Yuan, Qiping; Luo, Zhengping; Huang, Yao; Liu, Lei; Guo, Yong; Pei, Xiaofang; Chen, Shuliang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Humphreys, D.A.; Hyatt, A.W. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Mueller, Dennis [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Calabró, G.; Crisanti, F. [ENEA UnitàTecnicaFusione, C.R. Frascati, Via E. Fermi 45, 00044 Frascati, Roma (Italy); Albanese, R.; Ambrosino, R. [CREATE, Università di Napoli Federicao II, Università di Cassino and Università di Napoli Parthenope, Via Claudio 19, 80125 Napoli (Italy)

    2016-11-15

    Highlights: • Parallel plasma equilibrium reconstruction using GPU for real-time control on EAST. • Vertical control using Bang-bang + PID method to improve the response and minimize the oscillation caused by the latency. • Quasi-snow flake divertor plasma configuration has been demonstrated on EAST. - Abstract: In order to improve the plasma control performance and enhance the capability for advanced plasma control, new algorithms such as PEFIT/ISOFLUX plasma shape feedback control, quasi-snowflake plasma shape development and vertical control under new vertical control power supply, have been implemented and experimentally tested and verified in EAST 2014 campaign. P-EFIT is a rewritten version of EFIT aiming at fast real-time equilibrium reconstruction by using GPU for parallelized computation. Successful control using PEFIT/ISOFLUX was established in dedicated experiment. Snowfldivertor plasma shape has the advantage of spreading heat over the divertor target and a quasi-snowflake (QSF) configuration was achieved in discharges with I{sub p} = 0.25 MA and B{sub t} = 1.8T, κ∼1.9, by plasma position feedback control. The shape feedback control to achieve QSF shape has been preliminary implemented by using PEFIT and the initial experimental test has been done. For more robust vertical instability control, the inner coil (IC) and its power supply have been upgraded. A new control algorithm with the combination of Bang-bang and PID controllers has been developed. It is shown that new vertical control power supply together with the new control algorithms results in higher vertical controllability.

  9. The influence of the analog-to-digital conversion error on the JT-60 plasma position/shape feedback control system

    International Nuclear Information System (INIS)

    Yoshida, Michiharu; Kurihara, Kenichi

    1995-12-01

    In the plasma feedback control system (PFCS) and the direct digital controller (DDC) for the poloidal field coil power supply in the JT-60 tokamak, it is necessary to observe signals of all the poloidal field coil currents. Each of the signals, originally measured by a single sensor, is distributed to the PFCS and DDC through different cable routes and different analog-to-digital converters from each other. This produces the conversion error to the amount of several bits. Consequently, proper voltage from feedback calculation cannot be applied to the coil, and hence the control performance is possibly supposed to deteriorate to a certain extent. This paper describes how this error makes an influence on the plasma horizontal position control and how to improve the deteriorated control performance. (author)

  10. Plasma control device

    International Nuclear Information System (INIS)

    Takase, Haruhiko.

    1987-01-01

    Purpose: To obtain the optimum controllability for the plasmas and the thermonuclear device by selectively executing control operation for proportion, integration and differentiation (PID) by first and second controllers respectively based on selection instruction signals. Constitution: Deviation between a vertical direction equilibrium position: Zp as the plasma status amount measured in a measuring section and an aimed value Zref thereof is inputted to a first PID selection controller. The first controller selectively executes one of the PID control operations in accordance with the first selection signal instruction instructed by a PID control operation instruction circuit. Further, Zp is also inputted to a second PID selection controller, which selectively executes one of the PID control operations in accordance with the second selection instruction signal in the same manner as in the first controller. The deviation amount u between operations signals u1 and u2 from the first and second PID selection controllers is inputted to a power source to thereby supply a predetermined current value to control coils that generate equilibrium magnetic fields for making the vertical direction equilibrium position of plasmas constant. (Kamimura, M.)

  11. Coherent control of plasma dynamics

    Science.gov (United States)

    He, Zhaohan

    2014-10-01

    The concept of coherent control - precise measurement or determination of a process through control of the phase of an applied oscillating field - has been applied to numerous systems with great success. Here, we demonstrate the use of coherent control on plasma dynamics in a laser wakefield electron acceleration experiment. A tightly focused femtosecond laser pulse (10 mJ, 35 fs) was used to generate electron beams by plasma wakefield acceleration in the density down ramp. The technique is based on optimization of the electron beam using a deformable mirror adaptive optical system with an iterative evolutionary genetic algorithm. The image of the electrons on a scintillator screen was processed and used in a fitness function as direct feedback for the optimization algorithm. This coherent manipulation of the laser wavefront leads to orders of magnitude improvement to the electron beam properties such as the peak charge and beam divergence. The laser beam optimized to generate the best electron beam was not the one with the ``best'' focal spot. When a particular wavefront of laser light interacts with plasma, it can affect the plasma wave structures and trapping conditions of the electrons in a complex way. For example, Raman forward scattering, envelope self-modulation, relativistic self-focusing, and relativistic self-phase modulation and many other nonlinear interactions modify both the pulse envelope and phase as the pulse propagates, in a way that cannot be easily predicted and that subsequently dictates the formation of plasma waves. The optimal wavefront could be successfully determined via the heuristic search under laser-plasma conditions that were not known a priori. Control and shaping of the electron energy distribution was found to be less effective, but was still possible. Particle-in-cell simulations were performed to show that the mode structure of the laser beam can affect the plasma wave structure and trapping conditions of electrons, which

  12. Calculation of the line shapes of radiators immersed in plasma

    International Nuclear Information System (INIS)

    Hayrapetian, A.S.

    1987-01-01

    This work reports the results of theoretical calculations of line shapes of radiators immersed in plasma. The fluctuating electric field of the plasma perturbs the atomic structure of the immersed ions or atoms. The perturbed line shape is an important diagnostic tool for the temperature and density measurements of plasma. The line-shape calculation here is done by first deriving the line-shape expression, then it is shown that the problem is equivalent to calculating the temperature Green's function of the bound electron. The total Hamiltonian of the system includes the atomic, plasma, and atom-plasma parts. The temperature Green's function is calculated perturbatively by expanding in orders of atom-plasma interaction. By solving a Dyson equation, the dressed Green's functions of the bound electrons are obtained. At this point, the line shape is calculated by an analytic continuation from the complex frequency plane to real line. To derive the atomic electron Green's function, the momentum integral in the self-energy is approximated by a Riemann sum. With this approximation, the algebraic form of the line shape is obtained for an undetermined number of terms in the Riemann sum. Numerical calculation of line shape is done by using this result

  13. Multivariable shape control development on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Walker, M.L.; Humphreys, D.A.; Ferron, J.R.

    1997-11-01

    In this paper, the authors describe recent work on plasma shape and position control at DIII-D. This control consists of two equally challenging problems--the problem of identifying what the plasma actually looks like in real time, i.e. measuring the parameters to be controlled, and the task of determining the feedback algorithm which best controls these plasma parameters in a multiple input-output system. Recent implementation of the EFIT plasma equilibrium reconstruction algorithm in real time code which produces a new equilibrium estimate every 1.5 ms seems to solve the longstanding problem of obtaining sufficiently accurate plasma shape and position estimation. Stabilization of the open-loop unstable vertical motion is also viewed as a solved problem. The primary remaining problem appears to be how best to command the power supplies to achieve a desired shaping control response. They will describe the effort to understand and apply linearized models of plasma evolution to development and implementation of multivariable plasma controllers

  14. Initial operation of NSTX with plasma control

    International Nuclear Information System (INIS)

    Gates, D.; Bell, M.; Ferron, J.; Kaye, S.; Menard, J.; Mueller, D.; Neumeyer, C.; Sabbagh, S.

    2000-01-01

    First plasma, with a maximum current of 300kA, was achieved on NSTX in February 1999. These results were obtained using preprogrammed coil currents. The first controlled plasmas on NSTX were made starting in August 1999 with the full 1MA plasma current achieved in December 1999. The controlled quantities were plasma position (R, Z) and current (Ip). Variations in the plasma shape are achieved by adding preprogrammed currents to those determined by the control parameters. The control system is fully digital, with plasma position and current control, data acquisition, and power supply control all occurring in the same four-processor real time computer. The system uses the PCS (Plasma Control Software) system designed at General Atomics. Modular control algorithms, specific to NSTX, were written and incorporated into the PCS. The application algorithms do the actual control calculations, with the PCS handling data passing. The control system, including planned upgrades, will be described, along with results of the initial controlled plasma operations. Analysis of the performance of the control system will also be presented

  15. A universal representation of Rydberg spectral line shapes in plasmas

    International Nuclear Information System (INIS)

    Mosse, C.; Calisti, A.; Stamm, R.; Talin, B.; Bureyeva, L.; Lisitsa, V. S.

    2001-01-01

    A universal representation of Rydberg atom line shapes in plasmas is obtained. It bases on analytical formulas for intensity distribution in radiation transitions n→n' between highly excited atomic states with large values of principle quantum numbers n, n'>>1, Δn=n-n'<< n and the frequency fluctuation model (FFM) for account of ion thermal motion effects. The line shapes are presented in a universal manner as functions of plasma temperatures and densities

  16. Influence of plasma shape on transport in the TCV tokamak

    International Nuclear Information System (INIS)

    Moret, J.M.; Franke, S.; Weisen, H.

    1996-11-01

    The energy confinement time of TCV ohmic, L-mode plasmas is observed to depend on the shape, improving slightly with elongation and degrading strongly with positive triangularity. This dependence can be explained by combination of geometrical effects on the temperature gradient and power degradation, without invoking a shape dependence of the transport coefficients. (author) 5 figs., 8 refs

  17. Does shaping bring an advantage for reversed field pinch plasmas?

    International Nuclear Information System (INIS)

    Guo, S.C.; Xu, X.Y.; Wang, Z.R.; Liu, Y.Q.

    2013-01-01

    The MHD–kinetic hybrid toroidal stability code MARS-K (Liu et al 2008 Phys. Plasmas 15 112503) is applied to study the shaping effects on magnetohydrodynamic (MHD) stabilities in reversed field pinch (RFP) plasmas, where both elongation and triangularity are taken into account. The ideal wall β (the ratio of the gaso-kinetic to magnetic pressures) limit set by the ideal kink mode/resistive wall mode in shaped RFP is investigated first, followed by a study of the kinetic damping on the resistive wall mode. Physics understanding of the results is provided by a systematic numerical analysis. Furthermore, the stability boundary of the linear resistive tearing mode in shaped RFP plasmas is computed and compared with that of the circular case. Finally, bootstrap currents are calculated for both circular and shaped RFP plasmas. Overall, the results of these studies indicate that the current circular cross-section is an appropriate choice for RFP devices, in the sense that the plasma shaping does not bring an appreciable advantage to the RFP performance in terms of macroscopic stabilities. In order to reach a steady-state operation, future RFP fusion reactors will probably need a substantial fraction of external current drives, due to the unfavourable scaling for the plasma-generated bootstrap current in the RFP configuration. (paper)

  18. The system architecture of the new JET Shape Controller

    International Nuclear Information System (INIS)

    Sartori, F.; Ambrosino, G.; Ariola, M.; Cenedese, A.; Crisanti, F.; Tommasi, G. De; Cullen, P. Mc; Piccolo, F.; Pironti, A.

    2005-01-01

    This paper describes the installation of the new JET Shape Controller System [M. Garribba, R. Litunovsky, P. Noll, S. Puppin, The new control scheme for the JET plasma position and current control system, in: Proceedings of the 15th SOFE Conference, Massachusetts, 1993, pp. 33-36; F. Sartori, A. Cenedese, Plasma position and current control management at JET, in: Proceedings of the 42nd IEEE Conference on Decision and Control, Maui, 2003] especially focusing on the addition of the Extreme Shape Controller [G. Ambrosino, et al., A new shape controller for extremely shaped plasmas in JET, Fusion Eng. Des. 66-68 (2003) 797-802]. The activity was performed by the JET Operator in co-operation with the ENEA-CREATE design team, and involved both changes in the hardware and system software of JET and tuning of the proposed Extreme Shape Controller (XSC) design to satisfy the practical requirements of tokamak operation. The application of 10 years experience of controller implementation and commissioning combined with a modern and efficient modelling and design methodology has allowed an unprecedented fast and easy commissioning of the new system

  19. Recent plasma control progress on EAST

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B.J., E-mail: bjxiao@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Yuan, Q.P. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Humphreys, D.A.; Walker, M.L.; Hyatt, A.W.; Leuer, J.A.; Jackson, G.L. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Mueller, D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Penaflor, B.G.; Pigrowski, D.A.; Johnson, R.D.; Welander, A.S. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Zhang, R.R.; Luo, Z.P.; Guo, Y.; Xing, Z.; Zhang, Y. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)

    2012-12-15

    In recent 2 years, various algorithms to control plasma shape, current and density have been implemented or improved for EAST tokamak. These plasma control performances have been verified by either simulated or actual experimental operation, and thus plasma control basis has been established for the long pulse operation and high performance H-mode plasma operation with low hybrid wave (LHW) and ion cyclotron resonance frequency (ICRF) heating. Startup simulation has been done by using TOKSYS code for the plasma breakdown in either 3.1 Wb or 4.5 Wb initial poloidal flux state and the scenarios proved to be robust and used for routine operation. Various shape configurations have been well feedback controlled by using ISOFLUX limited, double-null or single null algorithms based on RTEFIT equilibrium reconstruction. For the long pulse operation, strike point control and magnetics drift compensation have been implemented in the plasma control system (PCS). To improve the operation safety and efficiency, the verification of magnetic diagnostics before plasma breakdown has been demonstrated adequate to prevent a discharge in case of key sensor failure.

  20. Concave pulse shaping of a circularly polarized laser pulse from non-uniform overdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Min Sup [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Kulagin, Victor V. [Sternberg Astronomical Institute, Moscow State University, Universitetsky prosp. 13, Moscow, 119992 (Russian Federation); Suk, Hyyong, E-mail: hysuk@gist.ac.kr [Department of Physics and Photon Science, GIST, 123 Cheomdan-gwangiro, Buk-gu, Gwangju, 500-712 (Korea, Republic of)

    2015-03-20

    Pulse shaping of circularly polarized laser pulses in nonuniform overdense plasmas are investigated numerically. Specifically we show by two-dimensional particle-in-cell simulations the generation of a concave pulse front of a circularly polarized, a few tens of petawatt laser pulse from a density-tapered, overdense plasma slab. The concept used for the transverse-directional shaping is the differential transmittance depending on the plasma density, and the laser intensity. For suitable selection of the slab parameters for the concave pulse shaping, we studied numerically the pulse transmittance, which can be used for further parameter design of the pulse shaping. The concavely shaped circularly polarized pulse is expected to add more freedom in controlling the ion-beam characteristics in the RPDA regime. - Highlights: • Laser pulse shaping for a concave front by non-uniform overdense plasma was studied. • Particle-in-cell (PIC) simulations were used for the investigation. • A laser pulse can be shaped by a density-tapered overdense plasma. • The concave and sharp pulse front are useful in many laser–plasma applications. • They are important for ion acceleration, especially in the radiation pressure dominant regime.

  1. The COMPASS Tokamak Plasma Control Software Performance

    Science.gov (United States)

    Valcarcel, Daniel F.; Neto, André; Carvalho, Ivo S.; Carvalho, Bernardo B.; Fernandes, Horácio; Sousa, Jorge; Janky, Filip; Havlicek, Josef; Beno, Radek; Horacek, Jan; Hron, Martin; Panek, Radomir

    2011-08-01

    The COMPASS tokamak has began operation at the IPP Prague in December 2008. A new control system has been built using an ATCA-based real-time system developed at IST Lisbon. The control software is implemented on top of the MARTe real-time framework attaining control cycles as short as 50 μs, with a jitter of less than 1 μs. The controlled parameters, important for the plasma performance, are the plasma current, position of the plasma current center, boundary shape and horizontal and vertical velocities. These are divided in two control cycles: slow at 500 μs and fast at 50 μs. The project has two phases. First, the software implements a digital controller, similar to the analog one used during the COMPASS-D operation in Culham. In the slow cycle, the plasma current and position are measured and controlled with PID and feedforward controllers, respectively, the shaping magnetic field is preprogrammed. The vertical instability and horizontal equilibrium are controlled with the faster 50-μs cycle PID controllers. The second phase will implement a plasma-shape reconstruction algorithm and controller, aiming at optimized plasma performance. The system was designed to be as modular as possible by breaking the functional requirements of the control system into several independent and specialized modules. This splitting enabled tuning the execution of each system part and to use the modules in a variety of applications with different time constraints. This paper presents the design and overall performance of the COMPASS control software.

  2. Autoionization spectral line shapes in dense plasmas

    International Nuclear Information System (INIS)

    Rosmej, F.B.; Hoffmann, D.H.H.; Faenov, A.Ya.; Pikuz, T.A.; Suess, W.; Geissel, M.

    2001-01-01

    The distortion of resonance line shapes due to the accumulation of a large number of satellite transitions is discovered by means of X-ray optical methods with simultaneous high spectral (λ/δλ≅8000) and spatial resolution (δx≅7 μm). Disappearance of the He α resonance line emission near the target surface is observed while Rydberg satellite intensity accumulates near the resonance line position. He β and He γ resonance line shapes are also shown to be seriously affected by opacity, higher-order line emissions from autoionizing states and inhomogeneous spatial emission. Opposite to resonance line emissions the He β satellites originate only from a very narrow spatial interval. New temperature and density diagnostics employing the 1s2131' and 1s3131'-satellites are developed. Moreover, even-J components of the satellite line emissions were resolved in the present high resolution experiments. Line transitions from the autoionizing states 1s2131' are therefore also proposed for space resolved Stark broadening analysis and local high density probing. Theorists are encouraged to provide accurate Stark broadening data for the transitions 1s2131 ' →1s 2 21+hv

  3. Plasma control for efficient extreme ultra-violet source

    International Nuclear Information System (INIS)

    Takahashi, Kensaku; Nakajima, Mitsuo; Kawamura, Tohru; Shiho, Makoto; Hotta, Eiki; Horioka, Kazuhiko

    2008-01-01

    To generate a high efficiency extreme-ultraviolet (EUV) source, effects of plasma shape for controlling radiative plasmas based on xenon capillary discharge are experimentally investigated. The radiation characteristics observed via tapered capillary discharge are compared with those of straight one. From the comparison, the long emission period and different plasma behaviors of tapered capillary discharge are confirmed. This means that control of the plasma geometry is effective for prolonging the EUV emission period. This result also indicates that the plasma shape control seems to have a potential for enhancing the conversion efficiency. (author)

  4. Ideal Coulomb Plasma Approximation in Line Shape Models: Problematic Issues

    Directory of Open Access Journals (Sweden)

    Joel Rosato

    2014-06-01

    Full Text Available In weakly coupled plasmas, it is common to describe the microfield using a Debye model. We examine here an “artificial” ideal one-component plasma with an infinite Debye length, which has been used for the test of line shape codes. We show that the infinite Debye length assumption can lead to a misinterpretation of numerical simulations results, in particular regarding the convergence of calculations. Our discussion is done within an analytical collision operator model developed for hydrogen line shapes in near-impact regimes. When properly employed, this model can serve as a reference for testing the convergence of simulations.

  5. Plasma shape reconstruction of merging spherical tokamak based on modified CCS method

    Science.gov (United States)

    Ushiki, Tomohiko; Inomoto, Michiaki; Itagaki, Masafumi; McNamara, Steven

    2017-10-01

    The merging start-up method is the one of the CS-free start-up schemes that has the advantage of high plasma temperature and density because it involves reconnection heating and compression processes. In order to achieve optimal merging operations, the initial two STs should have identical plasma currents and shapes, and then move symmetrically toward the center of the device with appropriate velocity. Furthermore, from the viewpoint of the compression effect, controlling the plasma major radius is also important. To realize the active feedback control of the plasma currents, the positions, and the shapes of the two initial STs and to optimize the plasma parameters described above, accurate estimation of the plasma boundary shape is highly important. In the present work, the Modified-CCS method is demonstrated to reconstruct the plasma boundary shapes as well as the eddy current profiles in the UTST (The University of Tokyo) and ST40 device (Tokamak Energy Ltd). The present research results demonstrate the effectiveness of the M-CCS method in the reconstruction analyses of ST merging.

  6. Status of DIII-D plasma control

    International Nuclear Information System (INIS)

    Walker, M.L.; Ferron, J.R.; Penaflor, B.

    1995-10-01

    A key component of the DIII-D Advanced Tokamak and Radiative Divertor Programs is the development and implementation of methods to actively control a large number of plasma parameters. These parameters include plasma shape and position, total stored energy, density, rf loading resistance, radiated power and more detailed control of the current profile. To support this research goal, a flexible and easily expanded digital control system has been developed and implemented. We have made parallel progress in modeling of the plasma, poloidal coils, vacuum vessel, and power system dynamics and in ensuring the integrity of diagnostic and command circuits used in control. Recent activity has focused on exploiting the mature digital control platform through the implementation of simple feedback controls of more exotic plasma parameters such as enhanced divertor radiation, neutral pressure and Marfe creation and more sophisticated identification and digital feedback control algorithms for plasma shape, vertical position, and safety factor on axis (q 0 ). A summary of recent progress in each of these areas will be presented

  7. Central safety factor and β N control on NSTX-U via beam power and plasma boundary shape modification, using TRANSP for closed loop simulations

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, M. D.; Andre, R.; Gates, D. A.; Gerhardt, S.; Goumiri, I. R.; Menard, J.

    2015-04-24

    The high-performance operational goals of NSTX-U will require development of advanced feedback control algorithms, including control of ßN and the safety factor profile. In this work, a novel approach to simultaneously controlling ßN and the value of the safety factor on the magnetic axis, q0, through manipulation of the plasma boundary shape and total beam power, is proposed. Simulations of the proposed scheme show promising results and motivate future experimental implementation and eventual integration into a more complex current profile control scheme planned to include actuation of individual beam powers, density, and loop voltage. As part of this work, a flexible framework for closed loop simulations within the high-fidelity code TRANSP was developed. The framework, used here to identify control-design-oriented models and to tune and test the proposed controller, exploits many of the predictive capabilities of TRANSP and provides a means for performing control calculations based on user-supplied data (controller matrices, target waveforms, etc.). The flexible framework should enable high-fidelity testing of a variety of control algorithms, thereby reducing the amount of expensive experimental time needed to implement new control algorithms on NSTX-U and other devices.

  8. Plasma shaping effects on tokamak scrape-off layer turbulence

    Science.gov (United States)

    Riva, Fabio; Lanti, Emmanuel; Jolliet, Sébastien; Ricci, Paolo

    2017-03-01

    The impact of plasma shaping on tokamak scrape-off layer (SOL) turbulence is investigated. The drift-reduced Braginskii equations are written for arbitrary magnetic geometries, and an analytical equilibrium model is used to introduce the dependence of turbulence equations on tokamak inverse aspect ratio (ε ), Shafranov’s shift (Δ), elongation (κ), and triangularity (δ). A linear study of plasma shaping effects on the growth rate of resistive ballooning modes (RBMs) and resistive drift waves (RDWs) reveals that RBMs are strongly stabilized by elongation and negative triangularity, while RDWs are only slightly stabilized in non-circular magnetic geometries. Assuming that the linear instabilities saturate due to nonlinear local flattening of the plasma gradient, the equilibrium gradient pressure length {L}p=-{p}e/{{\

  9. Controlled fusion and plasma heating

    International Nuclear Information System (INIS)

    1990-06-01

    The contributions presented in the 17th European Conference on Controlled Fusion and Plasma Heating were focused on Tore Supra investigations. The following subjects were presented: ohmic discharges, lower hybrid experiments, runaway electrons, Thomson scattering, plasma density measurements, magnetic fluctuations, polarization scattering, plasma currents, plasma fluctuation measurements, evaporation of hydrogen pellets in presence of fast electrons, ripple induced stochastic diffusion of trapped particles, tearing mode stabilization, edge effects on turbulence behavior, electron cyclotron heating, micro-tearing modes, divertors, limiters

  10. Enhancement of plasma generation in catalyst pores with different shapes

    Science.gov (United States)

    Zhang, Yu-Ru; Neyts, Erik C.; Bogaerts, Annemie

    2018-05-01

    Plasma generation inside catalyst pores is of utmost importance for plasma catalysis, as the existence of plasma species inside the pores affects the active surface area of the catalyst available to the plasma species for catalytic reactions. In this paper, the electric field enhancement, and thus the plasma production inside catalyst pores with different pore shapes is studied with a two-dimensional fluid model. The results indicate that the electric field will be significantly enhanced near tip-like structures. In a conical pore with small opening, the strongest electric field appears at the opening and bottom corners of the pore, giving rise to a prominent ionization rate throughout the pore. For a cylindrical pore, the electric field is only enhanced at the bottom corners of the pore, with lower absolute value, and thus the ionization rate inside the pore is only slightly enhanced. Finally, in a conical pore with large opening, the electric field is characterized by a maximum at the bottom of the pore, yielding a similar behavior for the ionization rate. These results demonstrate that the shape of the pore has a significantly influence on the electric field enhancement, and thus modifies the plasma properties.

  11. Confinement of plasma along shaped open magnetic fields from the centrifugal force of supersonic plasma rotation.

    Science.gov (United States)

    Teodorescu, C; Young, W C; Swan, G W S; Ellis, R F; Hassam, A B; Romero-Talamas, C A

    2010-08-20

    Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic E × B rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

  12. Shaping and characteristics of doublet plasmas in Doublet III

    International Nuclear Information System (INIS)

    Ohkawa, T.

    1979-10-01

    The shaping and plasma characteristics of doublet plasmas in Doublet III with high-Z limiters are described. Typical steady-state parameters at B/sub T/ = 24 kG are I/sub p/ = 1.5 MA, V/sub loop/ = 1.6 V, T/sub e/(O) = 1.0 keV, anti n/sub e/ = 4 x 10 13 cm -3 , Z/sub eff/ = 2, q(O) approx. 1 and tau /sub E//sup e/(O) = 20 msec. Electron energy confinement and maximum plasma density are in agreement with standard circular tokamak empirical scaling laws. Chromium and molybdenum appear to be the dominant high-Z plasma contaminants, with relative concentrations of approx. 10/sub -4/. The central power balance does not appear to be dominated by high-Z impurity radiation

  13. Chapter 8: Plasma operation and control

    Science.gov (United States)

    ITER Physics Expert Group on Disruptions, Control, Plasma, and MHD; ITER Physics Expert Group on Energetic Particles, Heating, Current and Drive; ITER Physics Expert Group on Diagnostics; ITER Physics Basis Editors

    1999-12-01

    Wall conditioning of fusion devices involves removal of desorbable hydrogen isotopes and impurities from interior device surfaces to permit reliable plasma operation. Techniques used in present devices include baking, metal film gettering, deposition of thin films of low-Z material, pulse discharge cleaning, glow discharge cleaning, radio frequency discharge cleaning, and in situ limiter and divertor pumping. Although wall conditioning techniques have become increasingly sophisticated, a reactor scale facility will involve significant new challenges, including the development of techniques applicable in the presence of a magnetic field and of methods for efficient removal of tritium incorporated into co-deposited layers on plasma facing components and their support structures. The current status of various approaches is reviewed, and the implications for reactor scale devices are summarized. Creation and magnetic control of shaped and vertically unstable elongated plasmas have been mastered in many present tokamaks. The physics of equilibrium control for reactor scale plasmas will rely on the same principles, but will face additional challenges, exemplified by the ITER/FDR design. The absolute positioning of outermost flux surface and divertor strike points will have to be precise and reliable in view of the high heat fluxes at the separatrix. Long pulses will require minimal control actions, to reduce accumulation of AC losses in superconducting PF and TF coils. To this end, more complex feedback controllers are envisaged, and the experimental validation of the plasma equilibrium response models on which such controllers are designed is encouraging. Present simulation codes provide an adequate platform on which equilibrium response techniques can be validated. Burning plasmas require kinetic control in addition to traditional magnetic shape and position control. Kinetic control refers to measures controlling density, rotation and temperature in the plasma core as

  14. Plasma control and utilization

    International Nuclear Information System (INIS)

    Ensley, D.L.

    1976-01-01

    A plasma is confined and heated by a microwave field resonant in a cavity excited in a combination of the TE and TM modes while responding to the resonant frequency of the cavity as the plasma dimensions change to maintain operation at resonance. The microwave field is elliptically or circularly polarized as to prevent the electromagnetic confining field from going to zero. A high Q chamber having superconductive walls is employed to minimize wall losses while providing for extraction of thermonuclear energy produced by fusion of nuclei in the plasma. 24 claims, 15 figures

  15. Control method for thermonuclear plasma

    International Nuclear Information System (INIS)

    Azuma, Kingo; Oda, Yasushi.

    1997-01-01

    CT (Compact Troid) is a doughnut-like shaped plasmas having a toroidal current and a poloidal current at the inside and forming a poloidal magnetic fluxes and toroidal magnetic flux. The structure of the CT is collapsed at a time of stationary state, accordingly, when it is injected to thermonuclear plasmas, particles can be supplied locally, and the state of the plasmas to be supplied can be changed by changing the direction of the injection. If a CT which is reverse to the poloidal magnetic fields is injected, plasmas with excessive ions can be supplied locally thereby enabling to form magnetic field in the thermonuclear plasmas. If the magnetic fields are formed in the vicinity of the surface of the thermonuclear plasmas, fast ions which have come over the magnetic field structure can be returned to the central portion of the plasmas. Then, confining performance of thermonuclear plasmas can be greatly improved, the efficiency for fuel supply can be increased, and energy required for ignition can be suppressed. (N.H.)

  16. New magnetic real time shape control for MAST

    Energy Technology Data Exchange (ETDEWEB)

    Pangione, L., E-mail: luigi.pangione@ccfe.ac.uk [EURATOM/CCFE Fusion Association – Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); McArdle, G.; Storrs, J. [EURATOM/CCFE Fusion Association – Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2013-10-15

    Highlights: ► New magnetic shape control system has been implemented. ► It has been intensively tested in a simulation environment. ► A tool chain to produce LTI model and simulate its behaviour has been implemented. ► Experimental results are shown. -- Abstract: The Mega Ampere Spherical Tokamak (MAST) real time plasma position controller is based on an optical linear camera placed on the mid plane of the vessel. This solution has the advantage of being a direct observation of the D{sub α} emissions coming from the interaction between the boundary of the plasma and neutral gas, but, on the other hand, it restricts the control to the outer radius of the plasma only. A complete chain of tools has been set up to implement, test and simulate a new real time magnetic plasma shape controller based on the rtEFIT code. The complete working path consists of three elements: a linear static relationship between control parameters and current demands, a linear state space model needed to represent the plasma dynamic response in closed loop simulations, and the possibility to run simulations inside the Plasma Control System (PCS). The linear relationship has been calculated using the FIESTA code, which is developed using Matlab at CCFE. The linear state space model was generated using the CREATE-L code developed by the CREATE Consortium. It has already been successfully used to model JET, FTU and TCV tokamaks. Using this working path many simulations have been carried out allowing fine tuning of the control gains before the real experiment. The simulation testing includes the plasma shape control law as implemented in PCS itself, so intensive debugging has been possible prior to operation. Successful control using rtEFIT was established in the second dedicated experiment during the MAST 2011–12 campaign. This work is a stepping stone towards divertor control which is ultimately intended for application to the super-X divertor in the MAST Upgrade experiment.

  17. Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Belli, E. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hammett, G. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Dorland, W. [Univ. of Maryland, College Park, MD (United States)

    2008-08-01

    The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ~ κ-1.5 or κ-2.0, depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows.

  18. Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence

    International Nuclear Information System (INIS)

    E.A. Belli, G.W. Hammett and W. Dorland

    2008-01-01

    The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ∼ κ -1.5 or κ -2.0 , depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows

  19. INTEGRATED PLASMA CONTROL FOR ADVANCED TOKAMAKS

    International Nuclear Information System (INIS)

    HUMPHREYS, D.A.; FERRON, J.R.; JOHNSON, R.D; LEUER, J.A.; PENAFLOR, B.G.; WALKER, M.L.; WELANDER, A.S.; KHAYRUTDINOV, R.R; DOKOUKA, V.; EDGELL, D.H.; FRANSSON, C.M.

    2004-03-01

    OAK-B135 Advanced tokamaks (AT) are distinguished from conventional tokamaks by their high degree of shaping, achievement of profiles optimized for high confinement and stability characteristics, and active stabilization of MHD instabilities to attain high values of normalized beta and confinement. These high performance fusion devices thus require accurate regulation of the plasma boundary, internal profiles, pumping, fueling, and heating, as well as simultaneous and well-coordinated MHD control action to stabilize such instabilities as tearing modes and resistive wall modes. Satisfying the simultaneous demands on control accuracy, reliability, and performance for all of these subsystems requires a high degree of integration in both design and operation of the plasma control system in an advanced tokamak. The present work describes the approach, benefits, and progress made in integrated plasma control with application examples drawn from the DIII-D tokamak. The approach includes construction of plasma and system response models, validation of models against operating experiments, design of integrated controllers which operate in concert with one another as well as with supervisory modules, simulation of control action against off-line and actual machine control platforms, and iteration of the design-test loop to optimize performance

  20. Characterization of plasma parameters in shaped PBX-M discharges

    Science.gov (United States)

    England, A. C.; Bell, R. E.; Hirshman, S. P.; Kaita, R.; Kugel, H. W.; LeBlanc, B. L.; Lee, D. K.; Okabayashi, M.; Sun, Y.-C.; Takahashi, H.

    1997-09-01

    The Princeton Beta Experiment-Modification (PBX-M) was run both with elliptical and with bean-shaped plasmas during the 1992 and 1993 operating periods. Two deuterium-fed neutral beams were used for auxiliary heating, and during 1992 the average power was 0741-3335/39/9/008/img13. This will be referred to as the lower neutral-beam power (LNBP) period. As many as four deuterium-fed neutral beams were used during 1993, and the average power was 0741-3335/39/9/008/img14. This will be referred to as the medium neutral-beam power (MNBP) period. The neutron source strength, Sn, showed a scaling with injected power 0741-3335/39/9/008/img15, 0741-3335/39/9/008/img16 for both the LMBP and MNBP periods. A much wider range of shaping parameters was studied during the MNBP as compared with the LNBP period. A weak positive dependence on bean shaping was observed for the LNBP, and a stronger positive dependence on shaping was observed for MNBP, viz 0741-3335/39/9/008/img17. High values of Sn were obtained in bean-shaped plasmas for the highest values of 0741-3335/39/9/008/img18 at 0741-3335/39/9/008/img19 for the LNBP. For the MNBP the highest values of Sn and stored energy were obtained at 0741-3335/39/9/008/img19, and the highest values of 0741-3335/39/9/008/img18 were obtained at 0741-3335/39/9/008/img22. The achievement of high Sn is aided by high neutral-beam power, high toroidal field, strong shaping, high electron temperature, and broad profiles. The achievement of high 0741-3335/39/9/008/img18 is aided by low toroidal field, high density, less shaping, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img24. The achievement of high 0741-3335/39/9/008/img25 is aided by strong shaping, high density, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img26. Some comparisons with the previous higher neutral-beam (HNBP) period in 1989 are also made.

  1. A COMPARISON OF SAWTEETH IN BEAN AND OVAL SHAPED PLASMAS

    International Nuclear Information System (INIS)

    LAZARUS, E.A.; AUSTIN, M.E.; BURRELL, K.H.; CHU, M.S.; HYATT, A.W.; JAYAKUMAR, R.J.; LUCE, T.C.; MAKOWSKI, M.A.; OSBORNE, T.H.; PETTY, C.C.; POLITZER, P.A.; PRATER, R.; REIMERDES, H.; SCOVILLE, J.T.; WADE, M.R.; WAELBROECK, F.L.

    2003-01-01

    A set of experiments has been conducted in DIII-D to compare sawteeth in bean and oval shaped, inner-wall limited plasmas. The distinction is that the oval will violate the ideal Mercier criterion with q 0 somewhat above 1, while a low κ bean shape will remain ideally Mercier stable with q 0 somewhat below 1. In this way they hope to separate the roles of internal kink and interchange in the behavior of sawteeth. The experimental arrangement allows us to change shape on successive discharges, which helps minimize systematic errors in the data. The principal diagnostics are motional Stark effect for the internal ploidal field, electron cyclotron emission for electron temperature, multi-pulse Thomson scattering for the density profile, and charge exchange recombination (CER) for ion temperature and toroidal velocity. New CER channels with greatly improved signal-to-noise allow resolution of the ion behavior during a sawtooth. These channels are critical to their ability to resolve the evolution of the ion temperature profiles during the sawteeth, enabling transport analysis. The experimental conditions are constant for about 3 s with 2.5 MW of neutral beam heating, which is needed for the diagnostics. The plasma shape is grown during the current ramp-up to facilitate equilibration of the current profile, which is stationary (aside from the sawteeth) as are temperature and density profiles. In some cases ECH heating is added. This increases the electron temperature so it is nearly equal to the ion temperature. At the present time the calibration of the MSE diagnostic calibration is incomplete and they will avoid analysis that is dependent on accurate knowledge of the equilibrium. After a brief characterization of the global features of the discharges, this paper will focus on two aspects of the experiment. There are two principal observations reported here. First, the nature of the sawtooth collapse in the two shapes, which they believe to be a current

  2. A saw-tooth plasma actuator for film cooling efficiency enhancement of a shaped hole

    Science.gov (United States)

    Li, Guozhan; Yu, Jianyang; Liu, Huaping; Chen, Fu; Song, Yanping

    2017-08-01

    This paper reports the large eddy simulations of the effects of a saw-tooth plasma actuator and the laidback fan-shaped hole on the film cooling flow characteristics, and the numerical results are compared with a corresponding standard configuration (cylindrical hole without the saw-tooth plasma actuator). For this numerical research, the saw-tooth plasma actuator is installed just downstream of the cooling hole and a phenomenological plasma model is employed to provide the 3D plasma force vectors. The results show that thanks to the downward force and the momentum injection effect of the saw-tooth plasma actuator, the cold jet comes closer to the wall surface and extends further downstream. The saw-tooth plasma actuator also induces a new pair of vortex which weakens the strength of the counter-rotating vortex pair (CRVP) and entrains the coolant towards the wall, and thus the diffusion of the cold jet in the crossflow is suppressed. Furthermore, the laidback fan-shaped hole reduces the vertical jet velocity causing the disappearance of downstream spiral separation node vortices, this compensates for the deficiency of the saw-tooth plasma actuator. Both effects of the laidback fan-shaped hole and the saw-tooth plasma actuator effectively control the development of the CRVP whose size and strength are smaller than those of the anti-counter rotating vortex pair in the far field, thus the centerline and the spanwise-averaged film cooling efficiency are enhanced. The average film cooling efficiency is the biggest in the Fan-Dc = 1 case, which is 80% bigger than that in the Fan-Dc = 0 case and 288% bigger than that in the Cyl-Dc = 0 case.

  3. Plasma physics for controlled fusion

    International Nuclear Information System (INIS)

    Miyamoto, K.

    2010-01-01

    The primary objective of this lecture note is to present the theories and experiments of plasma physics for recent activities of controlled fusion research for graduate and senior undergraduate students. Chapters 1-6 describe the basic knowledge of plasma and magnetohydrodynamics (MHD). MHD instabilities limit the beta ratio (ratio of plasma pressure to magnetic pressure) of confined plasma. Chapters 7-9 provide the kinetic theory of hot plasma and discuss the wave heating and non-inductive current drive. The dispersion relation derived by the kinetic theory are used to discuss plasma waves and perturbed modes. Landau damping is the essential mechanism of plasma heating and the stabilization of perturbation. Landau inverse damping brings the amplification of waves and the destabilization of perturbed modes. Chapter 10 explains the plasma transport due to turbulence, which is the most important and challenging subject for plasma confinement. Theories and simulations including subject of zonal flow are introduced. Chapters 11, 12 and 13 describe the recent activities of tokamak including ITER as well as spherical tokamak, reversed field pinch (RFP) and stellarator including quasi-symmetric configurations. Emphasis has been given to tokamak research since it made the most remarkable progress and the construction phase of 'International Tokamak Experimental Reactor' called ITER has already started. (author)

  4. Plasma control concepts for ITER

    International Nuclear Information System (INIS)

    Lister, J.B.; Nieswand, C.

    1997-01-01

    This overview paper skims over a wide range of issues related to the control of ITER plasmas. Although operation of the ITER project will require extensive developmental work to achieve the degree of control required, there is no indication that any of the identified problems will present overwhelming difficulties compared with the operation of present tokamaks. However, the precision of control required and the degree of automation of the final ITER plasma control system will present a challenge which is somewhat greater than for present tokamaks. In order to operate ITER optimally, integrated use of a large amount of diagnostic information will be necessary, evaluated and interpreted automatically. This will challenge both the diagnostics themselves and their supporting interpretation codes. The intervening years will provide us with the opportunity to implement and evaluate most of the new features required for ITER on existing tokamaks, with the exception of the control of an ignited plasma. (author) 7 figs., 7 refs

  5. Plasma position control device for thermonuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, Masanori [Mitsubishi Heavy Industries Ltd., Tokyo (Japan); Fujita, Jun-ya; Ioki, Kimihiro

    1995-10-03

    The present invention concerns plasma position control coils having a feeder line structure not requiring high strength for the support portion. Namely, the coils are formed by twisting feeder lines extended from plasma position control coils in a vacuum vessel. The twisted feeder lines are supported using an appropriate structural member. Electromagnetic load is generated to the feeder lines being extended from the position control coils and traversing toroidal fields at a current introduction lines and at current delivery lines respectively. However, since the feeder lines have substantially spiral shape consisting of two twisted lines, the electromagnetic load and the moment caused by the generated load which are inversed to each other are off set. Accordingly, only extremely small force is exerted on the fittings which support the feeder lines. Therefore, small strength may suffice for the fittings and the gaps of mounting the fittings may be made longer. (I.S.).

  6. Plasma position control device for thermonuclear device

    International Nuclear Information System (INIS)

    Onozuka, Masanori; Fujita, Jun-ya; Ioki, Kimihiro.

    1995-01-01

    The present invention concerns plasma position control coils having a feeder line structure not requiring high strength for the support portion. Namely, the coils are formed by twisting feeder lines extended from plasma position control coils in a vacuum vessel. The twisted feeder lines are supported using an appropriate structural member. Electromagnetic load is generated to the feeder lines being extended from the position control coils and traversing toroidal fields at a current introduction lines and at current delivery lines respectively. However, since the feeder lines have substantially spiral shape consisting of two twisted lines, the electromagnetic load and the moment caused by the generated load which are inversed to each other are off set. Accordingly, only extremely small force is exerted on the fittings which support the feeder lines. Therefore, small strength may suffice for the fittings and the gaps of mounting the fittings may be made longer. (I.S.)

  7. Controlled fusion and plasma physics

    International Nuclear Information System (INIS)

    1995-01-01

    This document presents the several speeches that took place during the 22nd European Physical Society conference on Controlled Fusion and Plasma Physics in Bournemouth, UK, between the 2nd and 7th July 1995. The talks deal with new experiments carried out on several tokamaks, particularly Tore Supra, concerning plasma confinement and fusion. Some information on specific fusion devices or tokamak devices is provided, as well as results of experiments concerning plasma instability. Separate abstracts were prepared for all the 31 papers in this volume. (TEC)

  8. Controlled fusion and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This document presents the several speeches that took place during the 22nd European Physical Society conference on Controlled Fusion and Plasma Physics in Bournemouth, UK, between the 2nd and 7th July 1995. The talks deal with new experiments carried out on several tokamaks, particularly Tore Supra, concerning plasma confinement and fusion. Some information on specific fusion devices or tokamak devices is provided, as well as results of experiments concerning plasma instability. Separate abstracts were prepared for all the 31 papers in this volume. (TEC).

  9. Controlled fusion and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    This document presents the several speeches that took place during the 22nd European Physical Society conference on Controlled Fusion and Plasma Physics in Bournemouth, UK, between the 2nd and 7th July 1995. The talks deal with new experiments carried out on several tokamaks, particularly Tore Supra, concerning plasma confinement and fusion. Some information on specific fusion devices or tokamak devices is provided, as well as results of experiments concerning plasma instability. Separate abstracts were prepared for all the 31 papers in this volume. (TEC).

  10. Advances in integrated plasma control on DIII-D

    International Nuclear Information System (INIS)

    Walker, M.L.; Ferron, J.R.; Hahn, S.H.; Humphreys, D.A.; In, Y.; Johnson, R.D.; Kim, J.S.; La Haye, R.J.; Leuer, J.A.; Penaflor, B.G.; Welander, A.S.; Xiao, B.

    2007-01-01

    The DIII-D advanced tokamak physics program requires extremely high performance from the DIII-D plasma control system, including simultaneous accurate regulation of plasma shape, stored energy, density and divertor characteristics, as well as coordinated suppression of magnetohydrodynamic instabilities. To satisfy these demanding control requirements, we apply the integrated plasma control method, consisting of construction of physics-based plasma and system response models, validation of models against operating experiments, design of integrated controllers that operate in concert with one another, simulation of control action against off-line and actual machine control platforms, and optimization through iteration of the design-test loop. The present work describes progress in development of physics models and development and experimental application of new model-based plasma controllers on DIII-D. We also describe the development of the control software, hardware, and model-based control algorithms for the superconducting EAST and KSTAR tokamaks

  11. Laser plasma interaction in rugby-shaped hohlraums

    Science.gov (United States)

    Masson-Laborde, P.-E.; Philippe, F.; Tassin, V.; Monteil, M.-C.; Gauthier, P.; Casner, A.; Depierreux, S.; Seytor, P.; Teychenne, D.; Loiseau, P.; Freymerie, P.

    2014-10-01

    Rugby shaped-hohlraum has proven to give high performance compared to a classical similar-diameter cylinder hohlraum. Due to this performance, this hohlraum has been chosen as baseline ignition target for the Laser MegaJoule (LMJ). Many experiments have therefore been performed during the last years on the Omega laser facility in order to study in details the rugby hohlraum. In this talk, we will discuss the interpretation of these experiments from the point of view of the laser plasma instability problem. Experimental comparisons have been done between rugby, cylinder and elliptical shape rugby hohlraums and we will discuss how the geometry differences will affect the evolution of laser plasma instabilities (LPI). The efficiency of laser smoothing techniques on these instabilities will also be discussed as well as gas filling effect. The experimental results will be compared with FCI2 hydroradiative calculations and linear postprocessing with Piranah. Experimental Raman and Brillouin spectrum, from which we can infer the location of the parametric instabilities, will be compared to simulated ones, and will give the possibility to compare LPI between the different hohlraum geometries.

  12. Controlled fusion and plasma physics

    International Nuclear Information System (INIS)

    1994-07-01

    40 papers are presented at this 21. conference on controlled fusion and plasma physics (JET). Titles are: effects of sawtooth crashes on beams ions and fusion product tritons; beta limits in H-modes and VH-modes; impurity induced neutralization of MeV energy protons in JET plasmas; lost α particle diagnostic for high-yield D-T fusion plasmas; 15-MeV proton emission from ICRF-heated plasmas; pulse compression radar reflectometry for density measurements; gamma-ray emission profile measurements during ICRH discharges; the new JET phase ICRH array; simulation of triton burn-up; parametric dependencies of JET electron temperature profiles; detached divertor plasmas; excitation of global Alfven Eigenmodes by RF heating; mechanisms of toroidal rotation; effect of shear in the radial electric field on confinement; plasma transport properties at the L-H transition; numerical study of plasma detachment conditions in JET divertor plasmas; the SOL width and the MHD interchange instability; non linear magnetic reconnection in low collisionality plasmas; topology and slowing down of high energy ion orbits; sawtooth crashes at high beta; fusion performances and alpha heating in future JET D-T plasmas; a stable route to high-beta plasmas with non-monotonic q-profiles; theory of propagation of changes to confinement; spatial distribution of gamma emissivity and fast ions during ICRF heating; multi-camera soft X-ray diagnostic; radiation phenomena and particle fluxes in the X-event; local measurement of transport parameters for laser injected trace impurities; impurity transport of high performance discharges; negative snakes and negative shear; neural-network charge exchange analysis; ion temperature anisotropy in helium neutral beam fuelling; impurity line emission due to thermal charge exchange in edge plasmas; control of convection by fuelling and pumping; VH mode accessibility and global H-mode properties; ion cyclotron emission by spontaneous emission; LHCD/ICRH synergy

  13. Pedestal performance dependence upon plasma shape in DIII-D

    International Nuclear Information System (INIS)

    Leonard, A.W.; Casper, T.A.; Groebner, R.J.; Osborne, T.H.; Snyder, P.B.; Thomas, D.M.

    2007-01-01

    Higher moments of the plasma shape than triangularity are found to significantly affect the pedestal pressure and the edge localized mode (ELM) characteristics in DIII-D. The shape dependence of the pedestal pressure was experimentally examined by varying the squareness in the proposed ITER configuration while holding the triangularity fixed. Over this scan the pedestal pressure increased by ∼50% from highest squareness to lowest squareness. The variation of pedestal energy is found to be consistent with the stability analysis of the measured profiles. The ELM energy also varied with the shape to maintain a nearly constant fraction of the pedestal energy. Stability analysis using model shapes and pressure profiles indicates that much of the advantage of high triangularity for high pedestal pressure can be achieved in lower triangularity shapes by optimizing squareness and/or the distance of the secondary upper separatrix from the primary separatrix. In high beta discharges an increase in pedestal pressure is observed with higher global stored energy. The greatest pedestal pressure increase is at low squareness due to an increase in both the pressure gradient stability limit and the width of the pedestal. The variation in pedestal pressure with squareness was also used to optimize 'hybrid' discharges in DIII-D where a lower pedestal pressure was required for an improved overall performance. In the 'hybrid' regime low squareness resulted in a high pedestal pressure with large infrequent ELMs that eventually triggered an internal 2/1 tearing mode that locked, resulting in a disruption. At higher squareness the pedestal pressure was reduced with smaller and more rapid ELMs, resulting in the maintenance of a steady beneficial internal 3/2 tearing mode and good confinement. For all the cases studied, an increase in the pedestal width at low squareness appears to be a significant factor in the increase in the total pedestal pressure

  14. Optimization of tokamak plasma equilibrium shape using parallel genetic algorithms

    International Nuclear Information System (INIS)

    Zhulin An; Bin Wu; Lijian Qiu

    2006-01-01

    In the device of non-circular cross sectional tokamaks, the plasma equilibrium shape has a strong influence on the confinement and MHD stability. The plasma equilibrium shape is determined by the configuration of the poloidal field (PF) system. Usually there are many PF systems that could support the specified plasma equilibrium, the differences are the number of coils used, their positions, sizes and currents. It is necessary to find the optimal choice that meets the engineering constrains, which is often done by a constrained optimization. The Genetic Algorithms (GAs) based method has been used to solve the problem of the optimization, but the time complexity limits the algorithms to become widely used. Due to the large search space that the optimization has, it takes several hours to get a nice result. The inherent parallelism in GAs can be exploited to enhance their search efficiency. In this paper, we introduce a parallel genetic algorithms (PGAs) based approach which can reduce the computational time. The algorithm has a master-slave structure, the slave explore the search space separately and return the results to the master. A program is also developed, and it can be running on any computers which support massage passing interface. Both the algorithm and the program are detailed discussed in the paper. We also include an application that uses the program to determine the positions and currents of PF coils in EAST. The program reach the target value within half an hour and yield a speedup rate of 5.21 on 8 CPUs. (author)

  15. Performance assessment of a dynamic current allocator for the JET eXtreme Shape Controller

    International Nuclear Information System (INIS)

    Varano, G.; Ambrosino, G.; Tommasi, G.De; Galeani, S.; Pironti, A.; Zaccarian, L.

    2011-01-01

    This paper reports on a recently proposed dynamic allocation technique that can be effectively adopted to handle the current saturations of the Poloidal Field coils with the eXtreme Shape Controller. The proposed approach allows to automatically relax the plasma shape regulation when the reference shape requires current levels out of the available ranges, finding in real-time an optimal trade-off between shape control precision and currents saturation avoidance. In this paper the results attained during preliminary analysis are presented, showing the advantage arising from the use of the dynamic allocator, versus the bare use of the eXtreme Shape Controller.

  16. Controlling the shape of membrane protein polyhedra

    Science.gov (United States)

    Li, Di; Kahraman, Osman; Haselwandter, Christoph A.

    2017-03-01

    Membrane proteins and lipids can self-assemble into membrane protein polyhedral nanoparticles (MPPNs). MPPNs have a closed spherical surface and a polyhedral protein arrangement, and may offer a new route for structure determination of membrane proteins and targeted drug delivery. We develop here a general analytic model of how MPPN self-assembly depends on bilayer-protein interactions and lipid bilayer mechanical properties. We find that the bilayer-protein hydrophobic thickness mismatch is a key molecular control parameter for MPPN shape that can be used to bias MPPN self-assembly towards highly symmetric and uniform MPPN shapes. Our results suggest strategies for optimizing MPPN shape for structural studies of membrane proteins and targeted drug delivery.

  17. Controlling marginally detached divertor plasmas

    Science.gov (United States)

    Eldon, D.; Kolemen, E.; Barton, J. L.; Briesemeister, A. R.; Humphreys, D. A.; Leonard, A. W.; Maingi, R.; Makowski, M. A.; McLean, A. G.; Moser, A. L.; Stangeby, P. C.

    2017-06-01

    A new control system at DIII-D has stabilized the inter-ELM detached divertor plasma state for H-mode in close proximity to the threshold for reattachment, thus demonstrating the ability to maintain detachment with minimal gas puffing. When the same control system was instead ordered to hold the plasma at the threshold (here defined as T e  =  5 eV near the divertor target plate), the resulting T e profiles separated into two groups with one group consistent with marginal detachment, and the other with marginal attachment. The plasma dithers between the attached and detached states when the control system attempts to hold at the threshold. The control system is upgraded from the one described in Kolemen et al (2015 J. Nucl. Mater. 463 1186) and it handles ELMing plasmas by using real time D α measurements to remove during-ELM slices from real time T e measurements derived from divertor Thomson scattering. The difference between measured and requested inter-ELM T e is passed to a PID (proportional-integral-derivative) controller to determine gas puff commands. While some degree of detachment is essential for the health of ITER’s divertor, more deeply detached plasmas have greater radiative losses and, at the extreme, confinement degradation, making it desirable to limit detachment to the minimum level needed to protect the target plate (Kolemen et al 2015 J. Nucl. Mater. 463 1186). However, the observed bifurcation in plasma conditions at the outer strike point with the ion B   ×  \

  18. Optical pulse shaping approaches to coherent control

    International Nuclear Information System (INIS)

    Goswami, Debabrata

    2003-01-01

    The last part of the twentieth century has experienced a huge resurge of activity in the field of coherent light-matter interaction, more so in attempting to exert control over such interactions. Birth of coherent control was originally spurred by the theoretical understanding of the quantum interferences that lead to energy randomization and experimental developments in ultrafast laser spectroscopy. The theoretical predictions on control of reaction channels or energy randomization processes are still more dramatic than the experimental demonstrations, though this gap between the two is consistently reducing over the recent years with realistic theoretical models and technological developments. Experimental demonstrations of arbitrary optical pulse shaping have made some of the previously impracticable theoretical predictions possible to implement. Starting with the simple laser modulation schemes to provide proof-of-the-principle demonstrations, feedback loop pulse shaping systems have been developed that can actively manipulate some atomic and molecular processes. This tremendous experimental boost of optical pulse shaping developments has prospects and implications into many more new directions, such as quantum computing and terabit/sec data communications. This review captures certain aspects and impacts of optical pulse shaping into the fast developing areas of coherent control and other related fields. Currently available reviews focus on one or the other detailed aspects of coherent control, and the reader will be referred to such details as and when necessary for issues that are dealt in brief here. We will focus on the current issues including control of intramolecular dynamics and make connections to the future concepts, such as, quantum computation, biomedical applications, etc

  19. Recent TCV results. Innovative plasma shaping to improve plasma properties and insight

    International Nuclear Information System (INIS)

    Pochelon, Antoine; Angelino, Paolo; Behn, Roland

    2012-01-01

    The TCV tokamak facility is used to study the effect of innovative plasma shapes on core and edge confinement properties. In low collisionality L-mode plasmas with electron cyclotron heating (ECH) confinement increases with increasing negative triangularity δ. The confinement improvement correlates with a decrease of the inner core electron heat transport, even though triangularity vanishes to the core, pointing to the effect of nonlocal transport properties. TCV has recently started the study of the effects of negative triangularity in H-mode plasmas. H-mode confinement is known to improve towards positive triangularity, due to the increase of pedestal height, though plagued by increasingly large edge localised modes (ELMs). An optimum triangularity could thus be sought between steep edge barriers (δ > 0) with large ELMs, and improved core confinement (δ < 0) with small ELMs. This opens the possibility for a reactor of having H-mode-level confinement within an L-mode edge, or at least with mitigated ELMs. In TCV, ELMy H-modes with upper triangularity δ top < 0 are explored, showing a reduction of ELM peak energy losses compared to δ top > 0. Alternative shapes are proposed on the basis of ideal MHD stability calculations. Shaping has the potential to bring at the same time key solutions to confinement, stability and wall loading issues and, from the comparison of experimental and simulation results, to give deeper insight in transport and stability. (author)

  20. Magnetic configuration control of ITER plasmas

    International Nuclear Information System (INIS)

    Albanese, R.; Mattei, M.; Portone, A.; Ambrosino, G.; Artaserse, G.; Crisanti, F.; De Tommasi, G.; Fresa, R.; Sartori, F.; Villone, F.

    2007-01-01

    The aim of this paper is to present some new tools used to review the capability of the ITER Poloidal Field (PF) system in controlling the broad range of plasma configurations presently forecasted during ITER operation. The attention is focused on the axi-symmetric aspects of plasma magnetic configuration control since they pose the greatest challenges in terms of control power and they have the largest impact on machine capital cost. Some preliminary results obtained during ongoing activities in collaboration between ENEA/CREATE and EFDA are presented. The paper is divided in two main parts devoted, respectively, to the presentation of a procedure for the PF current optimisation during the scenario, and of a software environment for the study of the PF system capabilities using the plasma linearized response. The proposed PF current optimisation procedure is then used to assess Scenario 2 design, also taking into account the presence of axisymmetric eddy currents and possible variations of poloidal beta and internal inductance. The numerical linear model based tool derived from the JET oriented eXtreme Shape Controller (XSC) tools is finally used to obtain results on the strike point sweeping in ITER

  1. Shape of the Hα emission line in non resonant charge exchange in hydrogen plasmas

    International Nuclear Information System (INIS)

    Susino Bueno, A.; Zurro Hernandez, B.

    1977-01-01

    The Hα line shape emitted from a maxwellian hydrogen plasma and produced by non resonant change exchange has been calculated. Its explicit shape depends on the ion temperature, on background neutral energy and on the relative shape of the collision cross section. A comparison between theoretical and experimental shapes of the Hα line is carried out to check the model and to deduce the ion plasma temperature. (author) [es

  2. Control of plasma density distribution via wireless power transfer in an inductively coupled plasma

    International Nuclear Information System (INIS)

    Lee, Hee-Jin; Lee, Hyo-Chang; Kim, Young-Cheol; Chung, Chin-Wook

    2013-01-01

    With an enlargement of the wafer size, development of large-area plasma sources and control of plasma density distribution are required. To control the spatial distribution of the plasma density, wireless power transfer is applied to an inductively coupled plasma for the first time. An inner powered antenna and an outer resonant coil connected to a variable capacitor are placed on the top of the chamber. As the self-resonance frequency ω r of the resonant coil is adjusted, the power transfer rate from the inner powered coil to the outer resonant coil is changed and the dramatic evolution of the plasma density profile is measured. As ω r of the outer resonant coil changes from the non-resonant condition (where ω r is not the driving angular frequency ω rf ) to the resonant condition (where ω r = ω rf ), the plasma density profile evolves from a convex shape with maximal plasma density at the radial center into a concave shape with maximal plasma density in the vicinity of the resonant antenna coil. This result shows that the plasma density distribution can be successfully controlled via wireless resonance power transfer. (fast track communication)

  3. Shape recovery and irrecoverable strain control in polyurethane shape-memory polymer

    International Nuclear Information System (INIS)

    Tobushi, Hisaaki; Ejiri, Yoshihiro; Hayashi, Syunichi; Hoshio, Kazumasa

    2008-01-01

    In shape-memory polymers, large strain can be fixed at a low temperature and thereafter recovered at a high temperature. If the shape-memory polymer is held at a high temperature for a long time, the irrecoverable strain can attain a new intermediate shape between the shape under the maximum stress and the primary shape. Irrecoverable strain control can be applied to the fabrication of a shape-memory polymer element with a complex shape in a simple method. In the present study, the influence of the strain-holding conditions on the shape recovery and the irrecoverable strain control in polyurethane shape-memory polymer is investigated by tension test of a film and three-point bending test of a sheet. The higher the shape-holding temperature and the longer the shape-holding time, the higher the irrecoverable strain rate. The equation that expresses the characteristics of the irrecoverable strain control is formulated

  4. Real time control of plasmas and ECRH systems on TCV

    NARCIS (Netherlands)

    Paley, J.I.; Felici, F.; Berrino, J.; Coda, S.; Cruz, N.; Duval, B.P.; Goodman, T.P.; Martin, Y.; Moret, J.-M.; Piras, F.; Rodrigues, A.P.; Santos, B.; Varandas, C.A.F.

    2008-01-01

    Developments in the real time control hardware on TCV paired with the flexibility of plasma shaping and ECRH actuators are opening many opportunities to perform real time experiments and develop algorithms and methods for fusion applications. The ability to control MHD instabilities is particularly

  5. Design, implementation and test of the XSC extreme shape controller in JET

    International Nuclear Information System (INIS)

    Albanese, R.; Ambrosino, G.; Ariola, M.; Cenedese, A.; Crisanti, F.; Tommasi, G. De; Mattei, M.; Piccolo, F.; Pironti, A.; Sartori, F.; Villone, F.

    2005-01-01

    A new model-based plasma current and shape controller has been set up and tested on the JET Tokamak with the existing active circuits and control. The installation has been carried out without causing any interference to the plasma operation and without requiring a long commissioning time. Eventually, the new controller was used on really extremely shaped internal transport barrier experiments at high poloidal beta and in the presence of quite large variations of the plasma current density profile (variation range Δβ pol up to 1.5 and Δl i up to 0.5). The extreme shape controller (XSC) controller architecture and philosophy also offer new interesting opportunities, e.g., the separatrix sweeping on the divertor plates without significantly affecting the overall plasma shape, and the possibility of improving the overall tokamak performance via combined control of plasma shape, current and profile. The adopted methodology constitutes also an important test bed for feedback control strategies of ITER relevance

  6. Shape Control of Responsive Building Envelopes

    DEFF Research Database (Denmark)

    Foged, Isak Worre; Kirkegaard, Poul Henning; Christensen, Jesper Thøger

    2010-01-01

    The present paper considers shape control of adaptive architectural structures for improvement of structural performance by recognizing changes in their environments and loads, adapting to meet goals, and using past events to improve future performance or maintain serviceability. The general scop...... environmental system to a primary structural system joint into a collective behavioral system equipment with an actuator system is presented....... alternatives. The adaptive structure is a proposal for a responsive building envelope which is an idea of a first level operational framework for present and future investigations towards performance based responsive architectures through a set of responsive typologies. A mock-up concept of a secondary...

  7. Identification of Y-shaped and O-shaped diffusion regions during magnetic reconnection in a laboratory plasma

    International Nuclear Information System (INIS)

    Yamada, Masaaki; Ji, H.; Hsu, S.; Carter, T.; Kulsrud, R.; Ono, Yasushi; Perkins, F.

    1997-01-01

    Two strikingly different shapes of diffusion regions are identified during magnetic reconnection in a magnetohydrodynamic laboratory plasma. The shapes depend on the third vector component of the reconnecting magnetic fields. Without the third component (anti-parallel or null-helicity reconnection), a thin double-Y shaped diffusion region is identified. In this case, the neutral sheet current profile is accurately measured to be as narrow as the order of the ion gyro-radius. In the presence of an appreciable third component (co-helicity reconnection), an O-shaped diffusion region appears and grows into a spheromak configuration

  8. Plasma and controlled thermonuclear reaction

    International Nuclear Information System (INIS)

    Kapitsa, P.

    1980-01-01

    The principle and prospects are given of three methods of achieving controlled thermonuclear reaction. The original and so far most promising TOKAMAK method is presented invented in the USSR. Another method is the heating of a sphere about 1 mm in diameter from a mixture of deuterium and tritium by focused laser light from all sides. The third method consists in continuous plasma heating. A rope-like plasma discharge at a temperature of more than a million K results in the gas from microwave oscillations. The discharge is placed in a magnetic field and the ion temperature is increased by magneto-acoustic waves. A reactor is proposed operating on this principle and problems are pointed out which will have to be resolved. (M.S.)

  9. Plasma and controlled thermonuclear reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kapitsa, P

    1980-06-01

    The principle and prospects are given of three methods of achieving controlled thermonuclear reaction. The original and so far most promising TOKAMAK method is presented invented in the USSR. Another method is the heating of a sphere about 1 mm in diameter from a mixture of deuterium and tritium by focused laser light from all sides. The third method consists in continuous plasma heating. A rope-like plasma discharge at a temperature of more than a million K results in the gas from microwave oscillations. The discharge is placed in a magnetic field and the ion temperature is increased by magneto-acoustic waves. A reactor is proposed operating on this principle and problems are pointed out which will have to be resolved.

  10. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Chan, V.S.; Chen, L.

    1998-12-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n ∼ 2--9 and a fast growth time γ -1 = 20--150 micros are often observed prior to the first giant type 1 ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n > 1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region

  11. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Ferron, J.R.; Miller, R.L.

    2001-01-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n∼2-9 and a fast growth time γ -1 =20-150μs are often observed prior to the first giant type I ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n>1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region. (author)

  12. 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)

  13. The plasma position control of ITER EDA plasma

    International Nuclear Information System (INIS)

    Senda, Ikuo; Nishio, Satoshi; Tsunematsu, Toshihide; Nishino, Toru; Fujieda, Hirobumi.

    1994-09-01

    The study on the plasma position control of ITER EDA performed by Japan Home Team during the sensitivity study in 1994 is summarized. The controllabilities of plasmas in the Outline Design and elongated version are compared. The model used to describe the motion of the plasma is a rigid model. The PD feedback control is applied with respect to the displacements of the plasma from the equilibrium. Three types of fluctuations, which initiate the motion of the plasma, are examined, namely a finite horizontal fluctuation field, a small horizontal fluctuation field such that the motion of the plasma is governed by the passive structures and an abrupt change of the poloidal beta β p and internal inductance l i . In the simulations of finite horizontal fluctuation fields, controls depend on the strength of the fluctuations, for instance, 3-5V is needed for 5-10G of fluctuation fields in the Outline Design. When the fluctuation field is small and the plasma displacement grows in a characteristic time of the passive structures, a few volt of the control voltage is enough to obtain good controllability. It is shown that the control when (β p , l i ) changes simultaneously is demanding and a large control voltage is required to maintain satisfactory control. Comparing the elongated version with the Outline Design, the control voltage which is larger than the Outline Design by a factor of 2-3 is required to obtain the same controllability in the elongated version. (author)

  14. JT-60 plasma control system

    International Nuclear Information System (INIS)

    Kurihara, K.

    1988-01-01

    JT-60 plasma control can be performed by the supervisory controller, the measurement system and actuators such as the poloidal field coil power supplies, gas injectors, neutral beam injection (NBI) heating system and radio frequency (RF) heating system. One of the most important characteristics of this system is a perfect digital control one composed of mini-computers, fast array processors and CAMAC modules, and it has large flexibility and few troubles to adjust the system. This system started to be operated in April 1985, after the six-year-long design, construction and testing, and have been operated and improved many times for two years. In this paper, the final system specification and its performance are presented aiming at the technological aspect of hardware and software. In addition, and experienced troubles are also presented. (author)

  15. Modelling and control of a tokamak plasma; Modelisation et commande d`un plasma de tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bremond, S

    1995-10-18

    Vertically elongated tokamak plasmas, while attractive as regards Lawson criteria, are intrinsically instable. It is found that the open-loop instability dynamics is characterised by the relative value of two dimensionless parameters: the coefficient of inductive coupling between the vessel and the coils, and the coil damping efficiency on the plasma displacement relative to that of the vessel. Applications to Tore Supra -where the instability is due to the iron core attraction- and DIII-D are given. A counter-effect of the vessel, which temporarily reverses the effect of coil control on the plasma displacement, is seen when the inductive coupling is higher than the damping ratio. Precise control of the plasma boundary is necessary if plasma-wall interaction and/or coupling to heating antennas are to be monitored. A positional drift, of a few mm/s, which had been observed in the Tore Supra tokamak, is explained and corrected. A linear plasma shape response model is then derived from magnetohydrodynamic equilibrium calculation, and proved to be in good agreement with experimental data. An optimal control law is derived, which minimizes an integral quadratic criteria on tracking errors and energy expenditure. This scheme avoids compensating coil currents, and could render local plasma shaping more precise. (authors). 123 refs., 77 figs., 6 tabs., 4 annexes.

  16. Real time control of plasmas and ECRH systems on TCV

    NARCIS (Netherlands)

    Paley, J.I.; Berrino, J.; Coda, S.; Cruz, N.; Duval, B.P.; Felici, F.; Goodman, T.P.; Martin, Y.; Moret, J.-M.; Piras, F.; Rodriques, A.P.; Santos, B.; Varandas, C.A.F.

    2009-01-01

    Developments in the real time control hardware on Tokamak Configuration Variable (TCV) coupled with the flexibility of plasma shaping and electron cyclotron (EC) heating and current drive actuators are opening many opportunities to perform real time experiments and develop algorithms and methods for

  17. Automatic plasma control in magnetic traps

    International Nuclear Information System (INIS)

    Samojlenko, Y.; Chuyanov, V.

    1984-01-01

    Hot plasma is essentially in thermodynamic non-steady state. Automatic plasma control basically means monitoring deviations from steady state and producing a suitable magnetic or electric field which brings the plasma back to its original state. Briefly described are two systems of automatic plasma control: control with a magnetic field using a negative impedance circuit, and control using an electric field. It appears that systems of automatic plasma stabilization will be an indispensable component of the fusion reactor and its possibilities will in many ways determine the reactor economy. (Ha)

  18. Integrated plasma control for high performance tokamaks

    International Nuclear Information System (INIS)

    Humphreys, D.A.; Deranian, R.D.; Ferron, J.R.; Johnson, R.D.; LaHaye, R.J.; Leuer, J.A.; Penaflor, B.G.; Walker, M.L.; Welander, A.S.; Jayakumar, R.J.; Makowski, M.A.; Khayrutdinov, R.R.

    2005-01-01

    Sustaining high performance in a tokamak requires controlling many equilibrium shape and profile characteristics simultaneously with high accuracy and reliability, while suppressing a variety of MHD instabilities. Integrated plasma control, the process of designing high-performance tokamak controllers based on validated system response models and confirming their performance in detailed simulations, provides a systematic method for achieving and ensuring good control performance. For present-day devices, this approach can greatly reduce the need for machine time traditionally dedicated to control optimization, and can allow determination of high-reliability controllers prior to ever producing the target equilibrium experimentally. A full set of tools needed for this approach has recently been completed and applied to present-day devices including DIII-D, NSTX and MAST. This approach has proven essential in the design of several next-generation devices including KSTAR, EAST, JT-60SC, and ITER. We describe the method, results of design and simulation tool development, and recent research producing novel approaches to equilibrium and MHD control in DIII-D. (author)

  19. Progress in the understanding and the performance of electron cyclotron heating and plasma shaping on TCV

    International Nuclear Information System (INIS)

    Moret, J.-M.; Alberti, S.; Andrebe, Y.

    2005-01-01

    Powerful ECH with an adaptable launching geometry and plasma shaping capability are exploited on TCV to create and control high performance regimes, with 3MW of 2nd and 1.5MW of 3rd harmonic (X3) and real time optimisation of the absorption by mirror feedback. Full X3 absorption with launching parallel to the resonant surface was obtained. Electron temperature profile stiffness was measured as a function of the shape up for a large range of temperature gradients and confirmed that the diffusivity is lower at negative triangularity and high elongation. The link between shear and transport was verified by interleaved modulation of co- and counter- ECCD. ECCD efficiency and fast electron generation and transport measurements demonstrate the role of transport on the driven current profile. Stationary electron ITBs were created and the role of the current profile in transport reduction was clarified by improving or destroying the barrier with a small induced electric field. (author)

  20. A structured architecture for advanced plasma control experiments

    International Nuclear Information System (INIS)

    Penaflor, B.G.; Ferron, J.R.; Walker, M.L.

    1996-10-01

    Recent new and improved plasma control regimes have evolved from enhancements to the systems responsible for managing the plasma configuration on the DIII-D tokamak. The collection of hardware and software components designed for this purpose is known at DIII-D as the Plasma Control System or PCS. Several new user requirements have contributed to the rapid growth of the PCS. Experiments involving digital control of the plasma vertical position have resulted in the addition of new high performance processors to operate in real-time. Recent studies in plasma disruptions involving the use of neural network based software have resulted in an increase in the number of input diagnostic signals sampled. Better methods for estimating the plasma shape and position have brought about numerous software changes and the addition of several new code modules. Furthermore, requests for performing multivariable control and feedback on the current profile are continuing to add to the demands being placed on the PCS. To support all of these demands has required a structured yet flexible hardware and software architecture for maintaining existing capabilities and easily adding new ones. This architecture along with a general overview of the DIII-D Plasma Control System is described. In addition, the latest improvements to the PCS are presented

  1. Plasma automatic control in magnetic traps

    International Nuclear Information System (INIS)

    Samojlenko, Yu.I.; Chuyanov, V.A.

    1983-01-01

    Principles of constructing the systems providing a plasma equilibrium and stability in thermonuctear devices are laid down. Operation of the servo system to maintain a plasma equilibrium is described using the tokamak plasma filament as an example. Operation of the system to suppress a flute instability is also described. This system measures electric disturbances on the plasma body surface and controls charge distribution on external electrodes. It is pointed out that systems of automatic control of plasma equilibrium and stability become an essential element of a future thermonuclear reactor and the system potentialities would much determine the reactor economic efficiency

  2. PDX modification to produce a bean-shaped high-beta plasma

    International Nuclear Information System (INIS)

    Materna, P.; Chrzanowski, J.; Heitzenroeder, P.; Lee, K.; Pereira, M.

    1983-01-01

    Princeton's PDX tokamak is being converted to produce bean-shaped plasmas which hopefully will reach beta of 10%. The work, which is nearly complete, involves repositioning active coils, adding passive coils, and making external modifications

  3. Static and dynamic control of plasma equilibrium in a Tokamak

    International Nuclear Information System (INIS)

    Blum, J.; Dei Cas, R.

    1979-01-01

    We are dealing here with the problem of controlling the plasma boundary and its displacements. Static control consists in determining the currents in the external coils of the Tokamak so that the plasma boundary has certain fixed characteristics: radial position, vertical elongation, desired shape. A self-consistent method is proposed here, considering a free plasma boundary, and using the techniques of optimal control of distributed parameter systems to solve the problem. The dynamic control problem considered in the second part of the paper is the control of the plasma radial displacements. An elaborate system of preprogramming and feedback control has been developed to ensure equilibrium and stability of the horizontal plasma motions. Optimal control techniques have been used to calculate the optimal primary coils configuration, the preprogramming voltages and the feedback gains. A new stability diagrams has been obtained which takes into account the erosion of the plasma by the limiter. All these calculations have been applied successfully to TFR 600 where thin liner and the presence of an iron core make the problem of stabilization of the radial displacements very difficult

  4. Plasma profile and shape optimization for the advanced tokamak power plant, ARIES-AT

    International Nuclear Information System (INIS)

    Kessel, C.E.; Mau, T.K.; Jardin, S.C.; Najmabadi, F.

    2006-01-01

    An advanced tokamak plasma configuration is developed based on equilibrium, ideal MHD stability, bootstrap current analysis, vertical stability and control, and poloidal field coil analysis. The plasma boundaries used in the analysis are forced to coincide with the 99% flux surface from the free-boundary equilibrium. Using an accurate bootstrap current model and external current drive profiles from ray tracing calculations in combination with optimized pressure profiles, β N values above 7.0 have been obtained. The minimum current drive requirement is found to lie at a lower β N of 6.0. The external kink mode is stabilized by a tungsten shell located at 0.33 times the minor radius and a feedback system. Plasma shape optimization has led to an elongation of 2.2 and triangularity of 0.9 at the separatrix. Vertical stability could be achieved by a combination of tungsten shells located at 0.33 times the minor radius and feedback control coils located behind the shield. The poloidal field coils were optimized in location and current, providing a maximum coil current of 8.6 MA. These developments have led to a simultaneous reduction in the power plant major radius and toroidal field from those found in a previous study [S.C. Jardin, C.E. Kessel, C.G. Bathke, D.A. Ehst, T.K. Mau, F. Najmabadi, T.W. Petrie, the ARIES Team, Physics basis for a reversed shear tokamak power plant, Fusion Eng. Design 38 (1997) 27

  5. Plasma Profile and Shape Optimization for the Advanced Tokamak Power Plant, ARIES-AT

    International Nuclear Information System (INIS)

    Kessel, C.E.; Mau, T.K.; Jardin, S.C.; Najmabadi, F.

    2001-01-01

    An advanced tokamak plasma configuration is developed based on equilibrium, ideal-MHD stability, bootstrap current analysis, vertical stability and control, and poloidal-field coil analysis. The plasma boundaries used in the analysis are forced to coincide with the 99% flux surface from the free-boundary equilibrium. Using an accurate bootstrap current model and external current-drive profiles from ray-tracing calculations in combination with optimized pressure profiles, beta(subscript N) values above 7.0 have been obtained. The minimum current drive requirement is found to lie at a lower beta(subscript N) of 5.4. The external kink mode is stabilized by a tungsten shell located at 0.33 times the minor radius and a feedback system. Plasma shape optimization has led to an elongation of 2.2 and triangularity of 0.9 at the separatrix. Vertical stability could be achieved by a combination of tungsten shells located at 0.33 times the minor radius and feedback control coils located behind the shield. The poloidal-field coils were optimized in location and current, providing a maximum coil current of 8.6 MA. These developments have led to a simultaneous reduction in the power plant major radius and toroidal field

  6. Controlled fusion and plasma physics

    International Nuclear Information System (INIS)

    Bickerton, R.J.

    1991-01-01

    On JET results were presented on additional heating power, on a recently discovered regime of enhanced pellet performance (PEP), on low-density H-mode plasma confinement with hot ions, bounds on very high electric currents by material limiters, the first experiments on lower hybrid current drive, on the L-H transition threshold dependence on the direction of the gradient-B drift, and on alpha-particle physics issues. The TFTR presentations focused on transport. Particle loss ramifications of the toroidal Alfven eigenmodes were found to be small, while their threshold of excitation is lower than theoretically predicted. On DIII-D a scaling study of transport with gyroradius as the only variable was reported, with approximately Bohm scaling emerging; but the effective heat diffusivity scaling could not be established due to profile consistency effects. While beta-limit investigations with DIII-D generally confirm the ideal, MHD limit found by Troyon, evidence of a reduction of the accessible range for the internal inductance with the safety factor seems to favour current-density control in a steady-state D-T burner. Onset of strongly sheared poloidal rotation in a thin layer during the L-H mode transition was experimentally shown, while a new, so-called VH (''very high'') confinement mode was discovered by boronization of the wall. The JT-90 tokamak has recently been upgraded to JT-60-U. Presentations by the ASDEX team summarized the lack of agreement with theory of L-mode confinement. With TEXTOR, an improved mode (I-mode) of confinement was found by boronization. Finally, reviews are included on the status of impurity transport and helium removal in tokamaks, on stellarators, alternative magnetic confinement systems, inertial confinement, and non-fusion plasma physics. 2 tabs

  7. Operation and control of ITER plasmas

    International Nuclear Information System (INIS)

    2001-01-01

    Features incorporated in the design of the International Thermonuclear Experimental Reactor (ITER) tokamak and its ancillary and plasma diagnostic systems that will facilitate operation and control of ignited and/or high-Q DT plasmas are presented. Control methods based upon straight-forward extrapolation of techniques employed in the present generation of tokamaks are found to be adequate and effective for DT plasma control with burn durations of ≥1000 s. Examples of simulations of key plasma control functions including magnetic configuration control and fusion burn (power) control are given. The prospects for the creation and control of steady-state plasmas sustained by non-inductive current drive are also discussed. (author)

  8. Operation and control of ITER plasmas

    International Nuclear Information System (INIS)

    1999-01-01

    Features incorporated in the design of the International Thermonuclear Experimental Reactor (ITER) tokamak and its ancillary and plasma diagnostic systems that will facilitate operation and control of ignited and/or high-Q DT plasmas are presented. Control methods based upon straight-forward extrapolation of techniques employed in the present generation of tokamaks are found to be adequate and effective for DT plasma control with burn durations of ≥1000 s. Examples of simulations of key plasma control functions including magnetic configuration control and fusion burn (power) control are given. The prospects for the creation and control of steady-state plasmas sustained by non-inductive current drive are also discussed. (author)

  9. XSC plasma control: Tool development for the session leader

    International Nuclear Information System (INIS)

    Ambrosino, G.; Albanese, R.; Ariola, M.; Cenedese, A.; Crisanti, F.; Tommasi, G. De; Mattei, M.; Piccolo, F.; Pironti, A.; Sartori, F.; Villone, F.

    2005-01-01

    A new model-based shape controller (XSC, i.e., eXtreme Shape Controller) able to operate with high elongation and triangularity plasmas has been designed and implemented at JET in 2003. The use of the XSC needs a number of steps, which at present are not automated and therefore imply the involvement of several experts. To help the session leader in preparing an experiment, a number of software tools are needed. The paper describes the SW tools that are currently in the developing phase, and describes the new framework for the preparation of a JET experiment

  10. Plasma position control on Alcator C

    International Nuclear Information System (INIS)

    Pribyl, P.A.

    1981-05-01

    The Alcator C MHD equilibrium is investigated from the standpoint of determining the plasma position. A review of equilibrium theory is presented, indicating that the central flux surfaces of the plasma should be displaced about 1 to 2 cm from the outermost. Further, the plasma should have a slightly noncircular cross-section. A comparison is made between the observed and predicted profiles. Flux loops sensitive to plasma position generate the error signal for the feedback control circuit. This measurement agrees with other position-sensitive diagnostics, such as limiter heating, and centroids of density, soft x-ray, and electron cyclotron emission. A linear model is developed for the position control feedback system, including the vertical field SCR supply, plasma, and feedback electronics. Operation of the control system agrees well with that predicted by the model, with acceptable plasma position being maintained for the duration of the discharge. The feedback control system is in daily use for Alcator C runs

  11. Current control necessary for toroidal plasma equilibrium

    International Nuclear Information System (INIS)

    Nagao, S.

    1987-01-01

    It is shown that a significant amount of dipole current is necessary for the plasma equilibrium of toroidal configurations in general. Through the vector product with the poloidal field, this dipole current force has to balance with the hoop force of plasma pressure itself of the annular shape. The measurement of such a current of dipole type may be interesting for the confirmation of the plasma equilibrium in the toroidal system. Moreover it is certained that there is a new mode of a tokamak operation with such a dipole current component and with smaller vertical field than that based on the classical tokamak theory. (author) [pt

  12. Shaping the electron beams with submicrosecond pulse duration in sources and electron accelerators with plasma emitters

    CERN Document Server

    Gushenets, V I

    2001-01-01

    One studies the techniques in use to shape submicrosecond electron beams and the physical processes associated with extraction of electrons from plasma in plasma emitters. Plasma emitter base sources and accelerators enable to generate pulse beams with currents varying from tens of amperes up to 10 sup 3 A, with current densities up to several amperes per a square centimeter, with pulse duration constituting hundreds of nanoseconds and with high frequencies of repetition

  13. Dependence of {beta} {center_dot} {tau} on plasma shape in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, E.A. [Oak Ridge National Lab., TN (United States)

    1993-12-31

    In this paper we discuss the observed variation in plasma performance with plasma shape, in particular, we shall compare single and double null diverted plasmas. The product {beta} {center_dot} {tau} has been used as a figure-of-merit for comparing different toroidal magnetic configurations. Here we shall use it as the figure-of-merit for comparing differing configurations within the DIII-D tokamak. (author) 5 refs., 5 figs.

  14. Dependence of β·τ on plasma shape in DIII-D

    International Nuclear Information System (INIS)

    Lazarus, E.A.

    1993-05-01

    In this paper we discuss the observed variation in plasma performance with plasma shape, in particular, we shall compare single and double null diverted plasmas. The product β·τ has been used as a figure-of-merit for comparing different toroidal magnetic configurations. Here we shall use it as the figure-of-merit for comparing differing configurations within the DIII-D tokamak

  15. Shape-Memory-Alloy Actuator For Flight Controls

    Science.gov (United States)

    Barret, Chris

    1995-01-01

    Report proposes use of shape-memory-alloy actuators, instead of hydraulic actuators, for aerodynamic flight-control surfaces. Actuator made of shape-memory alloy converts thermal energy into mechanical work by changing shape as it makes transitions between martensitic and austenitic crystalline phase states of alloy. Because both hot exhaust gases and cryogenic propellant liquids available aboard launch rockets, shape-memory-alloy actuators exceptionally suited for use aboard such rockets.

  16. Advances in Integrated Plasma Control on DIII-D

    International Nuclear Information System (INIS)

    Walker, M.L.; Ferron, J.R.; Humphreys, D.A.

    2006-01-01

    The DIII-D experimental program in advanced tokamak (AT) physics requires extremely high performance from the DIII-D plasma control system (PCS) [B.G.Penaflor, et al., 4 th IAEA Tech. Mtg on Control and Data Acq., San Diego, CA (2003)], including simultaneous and highly accurate regulation of plasma shape, stored energy, density, and divertor characteristics, as well as coordinated suppression of magnetohydrodynamic instabilities. To satisfy these demanding control requirements, we apply the integrated plasma control method, consisting of construction of physics-based plasma and system response models, validation of models against operating experiments, design of integrated controllers that operate in concert with one another as well as with supervisory modules, simulation of control action against off-line and actual machine control platforms, and optimization through iteration of the design-test loop. The present work describes progress in development of physics models and development and experimental application of several new model-based plasma controllers on DIII-D. We discuss experimental use of advanced shape control algorithms containing nonlinear techniques for improving control of steady state plasmas, model-based controllers for optimal rejection of edge localized mode disturbances during resistive wall mode stabilization, model-based controllers for neoclassical tearing mode stabilization, including methods for maximizing stabilization effectiveness with substantial constraints on available power, model-based integrated control of plasma rotation and beta, and initial experience in development of model-based controllers for advanced tokamak current profile modification. The experience gained from DIII-D has been applied to the development of control systems for the EAST and KSTAR tokamaks. We describe the development of the control software, hardware, and model-based control algorithms for these superconducting tokamaks, with emphasis on relevance of

  17. Role of the plasma shaping in ITB experiments on JET

    Energy Technology Data Exchange (ETDEWEB)

    Crisanti, F [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); Lomas, P J [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Tudisco, O [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); Becoulet, A [Association Euratom-CEA, CE de Cadarache, F-13108, St Paul lez Durance (France); Becoulet, M [Association Euratom-CEA, CE de Cadarache, F-13108, St Paul lez Durance (France); Bertalot, L [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); Bolzonella, T [Associazione EURATOM-ENEA sulla Fusione, Consorzio RFX, Padua (Italy); Bracco, G [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); De Benedetti, M [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); Esposito, B [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); Giroud, C [Association Euratom-CEA, CE de Cadarache, F-13108, St Paul lez Durance (France); Hawkes, N C [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Hender, T C [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Jarvis, O N [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Joffrin, E [Association Euratom-CEA, CE de Cadarache, F-13108, St Paul lez Durance (France); Pacella, D [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati (Italy); Riccardo, V [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Rimini, F [Association Euratom-CEA, CE de Cadarache, F-13108, St Paul lez Durance (France); Zastrow, K D [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

    2003-04-01

    A set of dedicated JET experiments is described where the plasma elongation (k) and triangularity ({delta}) were varied separately in order to study the influence of plasma magnetic topology on the internal transport barrier (ITB). With low {delta}, type III ELMs were observed and ITBs readily generated. At the highest {delta}, large type I ELMs and ELM free phases were observed but, at best, only marginal ITBs. At fixed {delta} the increase of the elongation of internal magnetic surface have a beneficial effect on the transport quality of the ITB.

  18. Sawtooth control in fusion plasmas

    International Nuclear Information System (INIS)

    Graves, J P; Angioni, C; Budny, R V; Buttery, R J; Coda, S; Eriksson, L-G; Gimblett, C G; Goodman, T P; Hastie, R J; Henderson, M A; Koslowski, H R; Mantsinen, M J; Martynov, An; Mayoral, M-L; Mueck, A; Nave, M F F; Sauter, O; Westerhof, E

    2005-01-01

    Clear observations of early triggering of neo-classical tearing modes by sawteeth with long quiescent periods have motivated recent efforts to control, and in particular destabilize, sawteeth. One successful approach explored in TCV utilizes electron cyclotron heating in order to locally increase the current penetration time in the core. The latter is also achieved in various machines by depositing electron cyclotron current drive or ion cyclotron current drive close to the q = 1 rational surface. Crucially, localized current drive also succeeds in destabilizing sawteeth which are otherwise stabilized by a co-existing population of energetic trapped ions in the core. In addition, a recent reversed toroidal field campaign at JET demonstrates that counter-neutral beam injection (NBI) results in shorter sawtooth periods than in the Ohmic regime. The clear dependence of the sawtooth period on the NBI heating power and the direction of injection also manifests itself in terms of the toroidal plasma rotation, which consequently requires consideration in the theoretical interpretation of the experiments. Another feature of NBI, expected to be especially evident in the negative ion based neutral beam injection (NNBI) heating planned for ITER, is the parallel velocity asymmetry of the fast ion population. It is predicted that a finite orbit effect of asymmetrically distributed circulating ions could strongly modify sawtooth stability. Furthermore, NNBI driven current with non-monotonic profile could significantly slow down the evolution of the safety factor in the core, thereby delaying sawteeth

  19. Sawtooth control in fusion plasmas

    Science.gov (United States)

    Graves, J. P.; Angioni, C.; Budny, R. V.; Buttery, R. J.; Coda, S.; Eriksson, L.-G.; Gimblett, C. G.; Goodman, T. P.; Hastie, R. J.; Henderson, M. A.; Koslowski, H. R.; Mantsinen, M. J.; Martynov, An; Mayoral, M.-L.; Mück, A.; Nave, M. F. F.; Sauter, O.; Westerhof, E.; Contributors, JET–EFDA

    2005-12-01

    Clear observations of early triggering of neo-classical tearing modes by sawteeth with long quiescent periods have motivated recent efforts to control, and in particular destabilize, sawteeth. One successful approach explored in TCV utilizes electron cyclotron heating in order to locally increase the current penetration time in the core. The latter is also achieved in various machines by depositing electron cyclotron current drive or ion cyclotron current drive close to the q = 1 rational surface. Crucially, localized current drive also succeeds in destabilizing sawteeth which are otherwise stabilized by a co-existing population of energetic trapped ions in the core. In addition, a recent reversed toroidal field campaign at JET demonstrates that counter-neutral beam injection (NBI) results in shorter sawtooth periods than in the Ohmic regime. The clear dependence of the sawtooth period on the NBI heating power and the direction of injection also manifests itself in terms of the toroidal plasma rotation, which consequently requires consideration in the theoretical interpretation of the experiments. Another feature of NBI, expected to be especially evident in the negative ion based neutral beam injection (NNBI) heating planned for ITER, is the parallel velocity asymmetry of the fast ion population. It is predicted that a finite orbit effect of asymmetrically distributed circulating ions could strongly modify sawtooth stability. Furthermore, NNBI driven current with non-monotonic profile could significantly slow down the evolution of the safety factor in the core, thereby delaying sawteeth.

  20. VME multiprocessor system for plasma control at the JT-60 Upgrade

    International Nuclear Information System (INIS)

    Kimura, T.; Kurihara, K.; Takahashi, M.; Kawamata, Y.; Akasaka, H.; Matsukawa, M.

    1989-01-01

    In this paper design and preliminary tests are reported of a VME multiprocessor system for the JT-60 Upgrade plasma control utilizing three MC88100 based RISC computers and VME buses. The design of the VME system was stimulated by faster and more accurate computation requirements for the plasma position and shape control

  1. Shape synchronization control for three-dimensional chaotic systems

    International Nuclear Information System (INIS)

    Huang, Yuanyuan; Wang, Yinhe; Chen, Haoguang; Zhang, Siying

    2016-01-01

    This paper aims to the three-dimensional continuous chaotic system and shape of the chaotic attractor by utilizing the basic theory of plane curves in classical differential geometry, the continuous controller is synthesized for the master–slave synchronization in shape. This means that the slave system can possess the same shape of state trajectory with the master system via the continuous controller. The continuous controller is composed of three sub-controllers, which respectively correspond to the master–slave synchronization in shape for the three projective curves of the chaotic attractor onto the three coordinate planes. Moreover, the proposed shape synchronization technique as well as application of control scheme to secure communication is also demonstrated in this paper, where numerical simulation results show the proposed control method works well.

  2. Progress and improvement of KSTAR plasma control using model-based control simulators

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Sang-hee, E-mail: hahn76@nfri.re.kr [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Welander, A.S. [General Atomics, San Diego, CA (United States); Yoon, S.W.; Bak, J.G. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Eidietis, N.W. [General Atomics, San Diego, CA (United States); Han, H.S. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Humphreys, D.A.; Hyatt, A. [General Atomics, San Diego, CA (United States); Jeon, Y.M. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Johnson, R.D. [General Atomics, San Diego, CA (United States); Kim, H.S.; Kim, J. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Kolemen, E.; Mueller, D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Penaflor, B.G.; Piglowski, D.A. [General Atomics, San Diego, CA (United States); Shin, G.W. [University of Science and Technology, Daejeon (Korea, Republic of); Walker, M.L. [General Atomics, San Diego, CA (United States); Woo, M.H. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of)

    2014-05-15

    Superconducting tokamaks like KSTAR, EAST and ITER need elaborate magnetic controls mainly due to either the demanding experiment schedule or tighter hardware limitations caused by the superconducting coils. In order to reduce the operation runtime requirements, two types of plasma simulators for the KSTAR plasma control system (PCS) have been developed for improving axisymmetric magnetic controls. The first one is an open-loop type, which can reproduce the control done in an old shot by loading the corresponding diagnostics data and PCS setup. The other one, a closed-loop simulator based on a linear nonrigid plasma model, is designed to simulate dynamic responses of the plasma equilibrium and plasma current (I{sub p}) due to changes of the axisymmetric poloidal field (PF) coil currents, poloidal beta, and internal inductance. The closed-loop simulator is the one that actually can test and enable alteration of the feedback control setup for the next shot. The simulators have been used routinely in 2012 plasma campaign, and the experimental performances of the axisymmetric shape control algorithm are enhanced. Quality of the real-time EFIT has been enhanced by utilizations of the open-loop type. Using the closed-loop type, the decoupling scheme of the plasma current control and axisymmetric shape controls are verified through both the simulations and experiments. By combining with the relay feedback tuning algorithm, the improved controls helped to maintain the shape suitable for longer H-mode (10–16 s) with the number of required commissioning shots largely reduced.

  3. New DIII-D tokamak plasma control system

    International Nuclear Information System (INIS)

    Campbell, G.L.; Ferron, J.R.; McKee, E.; Nerem, A.; Smith, T.; Greenfield, C.M.; Pinsker, R.I.; Lazarus, E.A.

    1992-09-01

    A state-of-the-art plasma control system has been constructed for use on the DIII-D tokamak to provide high speed real time data acquisition and feedback control of DIII-D plasma parameters. This new system has increased the precision to which discharge shape and position parameters can be maintained and has provided the means to rapidly change from one plasma configuration to another. The capability to control the plasma total energy and the ICRF antenna loading resistance has been demonstrated. The speed and accuracy of this digital system will allow control of the current drive and heating systems in order to regulate the current and pressure profiles and diverter power deposition in the DIII-D machine. Use of this system will allow the machine and power supplies to be better protected from undesirable operating regimes. The advanced control system is also suitable for control algorithm development for future machines in these areas and others such as disruption avoidance. The DIII-D tokamak facility is operated for the US Department of Energy by General Atomics Company (GA) in San Diego, California. The DIII-D experimental program will increase emphasis on rf heating and current drive in the near future and is installing a cryopumped divertor ring during the fall of 1992. To improve the flexibility of this machine for these experiments, the new shape control system was implemented. The new advanced plasma control system has enhanced the capabilities of the DIII-D machine and provides a data acquisition and control platform that promises to be useful far beyond its original charter

  4. Electron heat transport in shaped TCV L-mode plasmas

    International Nuclear Information System (INIS)

    Camenen, Y; Pochelon, A; Bottino, A; Coda, S; Ryter, F; Sauter, O; Behn, R; Goodman, T P; Henderson, M A; Karpushov, A; Porte, L; Zhuang, G

    2005-01-01

    Electron heat transport experiments are performed in L-mode discharges at various plasma triangularities, using radially localized electron cyclotron heating to vary independently both the electron temperature T e and the normalized electron temperature gradient R/L T e over a large range. Local gyro-fluid (GLF23) and global collisionless gyro-kinetic (LORB5) linear simulations show that, in the present experiments, trapped electron mode (TEM) is the most unstable mode. Experimentally, the electron heat diffusivity χ e is shown to decrease with increasing collisionality, and no dependence of χ e on R/L T e is observed at high R/L T e values. These two observations are consistent with the predictions of TEM simulations, which supports the fact that TEM plays a crucial role in electron heat transport. In addition, over the broad range of positive and negative triangularities investigated, the electron heat diffusivity is observed to decrease with decreasing plasma triangularity, leading to a strong increase of plasma confinement at negative triangularity

  5. Progress and plan of KSTAR plasma control system upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Sang-hee, E-mail: hahn76@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, Y.J. [National Fusion Research Institute, Daejeon (Korea, Republic of); Penaflor, B.G. [General Atomics, San Diego, CA (United States); Bak, J.G.; Han, H.; Hong, J.S.; Jeon, Y.M.; Jeong, J.H.; Joung, M.; Juhn, J.W.; Kim, J.S.; Kim, H.S.; Lee, W.R.; Woo, M.H. [National Fusion Research Institute, Daejeon (Korea, Republic of); Eidietis, N.W.; Ferron, J.R.; Humphreys, D.A.; Hyatt, A.; Johnson, R.D.; Piglowski, D.A. [General Atomics, San Diego, CA (United States); and others

    2016-11-15

    Highlights: • Recent achievements of the KSTAR plasma control system are described. • Requirements and results of the testbed system for the future upgrade of the KSTAR plasma control system are presented. • An overview of the upgrade layout based is given. - Abstract: The plasma control system (PCS) has been one of essential systems in annual KSTAR plasma campaigns: starting from a single-process version in 2008, extensive upgrades are done through the previous 7 years in order to achieve major goals of KSTAR performance enhancement. Major implementations are explained in this paper. In consequences of successive upgrades, the present KSTAR PCS is able to achieve ∼48 s of 500 kA plasma pulses with full real-time shaping controls and real-time NB power controls. It has become a huge system capable of dealing with 8 separate categories of algorithms, 26 actuators directly controllable during the shot, and real-time data communication units consisting of +180 analog channels and +600 digital input/outputs through the reflective memory (RFM) network. The next upgrade of the KSTAR PCS is planned in 2015 before the campaign. An overview of the upgrade layout will be given for this paper. The real-time system box is planned to use the CERN MRG-Realtime OS, an ITER-compatible standard operating system. New hardware is developed for faster real-time streaming system for future installations of actuators/diagnostics.

  6. Direct Laser Writing of Low-Density Interdigitated Foams for Plasma Drive Shaping [Direct Laser Writing of Low Density Nanostitched Foams for Plasma Drive Shaping

    International Nuclear Information System (INIS)

    Oakdale, James S.; Smith, Raymond F.; Forien, Jean-Baptiste; Smith, William L.; Ali, Suzanne J.

    2017-01-01

    Monolithic porous bulk materials have many promising applications ranging from energy storage and catalysis to high energy density physics. High resolution additive manufacturing techniques, such as direct laser writing via two photon polymerization (DLW-TPP), now enable the fabrication of highly porous microlattices with deterministic morphology control. In this work, DLW-TPP is used to print millimeter-sized foam reservoirs (down to 0.06 g cm –3 ) with tailored density-gradient profiles, where density is varied by over an order of magnitude (for instance from 0.6 to 0.06 g cm –3 ) along a length of <100 µm. Taking full advantage of this technology, however, is a multiscale materials design problem that requires detailed understanding of how the different length scales, from the molecular level to the macroscopic dimensions, affect each other. The design of these 3D-printed foams is based on the brickwork arrangement of 100 × 100 × 16 µm 3 log-pile blocks constructed from sub-micrometer scale features. A block-to-block interdigitated stitching strategy is introduced for obtaining high density uniformity at all length scales. Lastly, these materials are used to shape plasma-piston drives during ramp-compression of targets under high energy density conditions created at the OMEGA Laser Facility.

  7. Relaxed error control in shape optimization that utilizes remeshing

    CSIR Research Space (South Africa)

    Wilke, DN

    2013-02-01

    Full Text Available Shape optimization strategies based on error indicators usually require strict error control for every computed design during the optimization run. The strict error control serves two purposes. Firstly, it allows for the accurate computation...

  8. Progress on laser plasma accelerator development using transverselyand longitudinally shaped plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Leemans, Wim P.; Esarey, E.; Geddes, C.G.R.; Toth, Cs.; Schroeder, C.B.; Nakamura, K.; Gonsalves, A.J.; Panasenko, D.; Cormier-Michel, E.; Plateau, G.R.; Lin, C.; Bruhwiler, D.L.; Cary, J.R.

    2009-03-31

    A summary of progress at Lawrence Berkeley National Laboratory is given on: (1) experiments on down-ramp injection; (2) experiments on acceleration in capillary discharge plasma channels; and (3) simulations of a staged laser wakefield accelerator (LWFA). Control of trapping in a LWFA using plasma density down-ramps produced electron bunches with absolute longitudinal and transverse momentum spreads more than ten times lower than in previous experiments (0.17 and 0.02 MeV Ic FWHM, respectively) and with central momenta of 0.76 +- 0.02 MeV Ic, stable over a week of operation. Experiments were also carried out using a 40 TW laser interacting with a hydrogen-filled capillary discharge waveguide. For a 15 mm long, 200 mu m diameter capillary, quasi-monoenergetic bunches up to 300 MeV were observed. By detuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized. For a 33 mm long, 300 mu m capillary, a parameter regime with high energy bunches, up to 1 Ge V, was found. In this regime, peak electron energy was correlated with the amount of trapped charge. Simulations show that bunches produced on a down-ramn and iniected into a channel-guided LWFA can produce stable beams with 0.2 MeV Ic-class momentum spread at high energies.

  9. Plasma physics and controlled nuclear fusion research

    International Nuclear Information System (INIS)

    1980-01-01

    Full text: During the last decade, growing efforts have been devoted to studying the possible forms an electricity-producing thermonuclear reactor might take and the various technical problems that will have to be overcome. Previous IAEA Conferences took place in Salzburg (1961), Culham (1965), Novosibirsk (1968), Madison (1971), Tokyo (1974), Berchtesgaden (1976) and Innsbruck (1978) The exchange of information that has characterized this series of meetings is an important example of international co-operation and has contributed substantially to progress in controlled fusion research. The results of experiments in major research establishments, as well as the growing scientific insights in the field of plasma physics, give hope that the realization of nuclear fusion will be made possible on a larger scale and beyond the laboratory stage by the end of this century. The increase of the duration of existing tokamak discharges requires solution of the impurity control problem. First results from the new big machines equipped with the poloidal divertor recently came into operation. PDX (USA) and ASDEX (F.R. of Germany) show that various divertor configurations can be established and maintained and that the divertors function in the predicted manner. The reduction of high-Z impurities on these machines by a factor 10 was achieved. As a result of extensive research on radio-frequency (RF) plasma heating on tokamaks: PLT (USA), TFR (France), JFT-2 (Japan), the efficiency of this attractive method of plasma heating comparable to neutral beam heating was demonstrated. It was shown that the density of the input power of about 5-10 kW/cm 2 is achievable and this limit is high enough for application to reactor-like machines. One of the inspiring results reported at the conference was the achievement of value (the ratio of plasma pressure to magnetic field pressure) of ∼ 3% on tokamaks T-11 (USSR) and ISX-B (USA). It is important to note that this value exceeds the

  10. Plasma position control in TCABR Tokamak

    International Nuclear Information System (INIS)

    Galvao, R.M.O.; Kuznetsov, Yu. K.; Nascimento, I.C.; Fonseca, A.M.M.; Silva, R.P. da; Ruchko, L.F.; Tuszel, A.G.; Reis, A.P. dos; Sanada, E.K.

    1998-01-01

    The plasma control position in the TCABR tokamak is described. The TCA tokamak was transferred from the Centre de Recherches en Physique des Plasmas, Lausanne, to the Institute of Physics of University of Sao Paulo, renamed TCABR (α=0.18 m, R = 0.62 m, B = 1 T,I p = 100 kA). The control system was reconstructed using mainly components obtained from the TCA tokamak. A new method of plasma position determination is used in TCABR to improve its accuracy. A more detailed theoretical analysis of the feed forward and feedback control is performed as compared with. (author)

  11. Plasma physics for controlled fusion

    CERN Document Server

    Miyamoto, Kenro

    2016-01-01

    This new edition presents the essential theoretical and analytical methods needed to understand the recent fusion research of tokamak and alternate approaches. The author describes magnetohydrodynamic and kinetic theories of cold and hot plasmas in detail. The book covers new important topics for fusion studies such as plasma transport by drift turbulence, which depend on the magnetic configuration and zonal flows. These are universal phenomena of microturbulence. They can modify the onset criterion for turbulent transport, instabilities driven by energetic particles as well as alpha particle generation and typical plasma models for computer simulation. The fusion research of tokamaks with various new versions of H modes are explained. The design concept of ITER, the international tokamak experimental reactor, is described for inductively driven operations as well as steady-state operations using non-inductive drives. Alternative approaches of reversed-field pinch and its relaxation process, stellator includi...

  12. Plasma Surface interaction in Controlled fusion devices

    International Nuclear Information System (INIS)

    1990-05-01

    The subjects presented in the 9th conference on plasma surface interaction in controlled fusion devices were: the modifications of power scrape-off-length and power deposition during various configurations in Tore Supra plasmas; the effects observed in ergodic divertor experiments in Tore-Supra; the diffuse connexion induced by the ergodic divertor and the topology of the heat load patterns on the plasma facing components in Tore-Supra; the study of the influence of air exposure on graphite implanted by low energy high density deuterium plasma

  13. Software development for the PBX-M plasma control system

    International Nuclear Information System (INIS)

    Lagin, L.; Bell, R.; Chu, J.; Hatcher, R.; Hirsch, J.; Okabayashi, M.; Sichta, P.

    1995-01-01

    This paper describes the software development effort for the PBX-M plasma control system. The algorithms being developed for the system will serve to test advanced control concepts for TPX and ITER. This will include real-time algorithms for shaping control, vertical position control, current and density profile control and MHD avoidance. The control system consists of an interactive Host Processor (SPARC-10) interfaced through VME with four real-time Computer Processors (i860) which run at a maximum computational speed of 320 MFLOPs. Plasma shaping programs are being tested to duplicate the present PBX-M analog control system. Advanced algorithms for vertical control and x-point control will then be developed. Interactive graphical user interface programs running on the Host Processor will allow operators to control and monitor shot parameters. A waveform edit program will be used to download pre-programmed waveforms into the Compute Processor memory. Post-shot display programs will be used to interactively display data after the shot. Automatic pre-shot arming and data acquisition programs will run on the Host Processor. Event system programs will process interrupts and activate programs on the Host and Compute Processors. These programs are being written in C and Fortran and use system service routines to communicate with the Compute Processors and its memory. IDL and IDL widgets are being used to build the graphical user interfaces

  14. Power supply controlled for plasma torch generation

    International Nuclear Information System (INIS)

    Diaz Z, S.

    1996-01-01

    The high density of energy furnished by thermal plasma is profited in a wide range of applications, such as those related with welding fusion, spray coating and at the present in waste destruction. The waste destruction by plasma is a very attractive process because the remaining products are formed by inert glassy grains and non-toxic gases. The main characteristics of thermal plasmas are presented in this work. Techniques based on power electronics are utilized to achieve a good performance in thermal plasma generation. This work shown the design and construction of three phase control system for electric supply of thermal plasma torch, with 250 kw of capacity, as a part of the project named 'Destruction of hazard wastes by thermal plasma' actually working in the Instituto Nacional de Investigaciones Nucleares (ININ). The characteristics of thermal plasma and its generation are treated in the first chapter. The A C controllers by thyristors applied in three phase arrays are described in the chapter II, talking into account the power transformer, rectifiers bank and aliasing coil. The chapter III is dedicated in the design of the trigger module which controls the plasma current by varying the trigger angle of the SCR's; the protection and isolating unit are also presented in this chapter. The results and conclusions are discussed in chapter IV. (Author)

  15. Genetic control of organ shape and tissue polarity.

    Directory of Open Access Journals (Sweden)

    Amelia A Green

    2010-11-01

    Full Text Available The mechanisms by which genes control organ shape are poorly understood. In principle, genes may control shape by modifying local rates and/or orientations of deformation. Distinguishing between these possibilities has been difficult because of interactions between patterns, orientations, and mechanical constraints during growth. Here we show how a combination of growth analysis, molecular genetics, and modelling can be used to dissect the factors contributing to shape. Using the Snapdragon (Antirrhinum flower as an example, we show how shape development reflects local rates and orientations of tissue growth that vary spatially and temporally to form a dynamic growth field. This growth field is under the control of several dorsoventral genes that influence flower shape. The action of these genes can be modelled by assuming they modulate specified growth rates parallel or perpendicular to local orientations, established by a few key organisers of tissue polarity. Models in which dorsoventral genes only influence specified growth rates do not fully account for the observed growth fields and shapes. However, the data can be readily explained by a model in which dorsoventral genes also modify organisers of tissue polarity. In particular, genetic control of tissue polarity organisers at ventral petal junctions and distal boundaries allows both the shape and growth field of the flower to be accounted for in wild type and mutants. The results suggest that genetic control of tissue polarity organisers has played a key role in the development and evolution of shape.

  16. Tip Clearance Control Using Plasma Actuators

    Science.gov (United States)

    2007-03-01

    Clearance Control Using Plasma Actuators 4 posed by Denton (1993). A number of investigators have used partial shrouds, or " winglet " designs to...SDBD actuator Plasma enhanced aerodynamics has been demonstrated in a range of applications involving sepa- ration control, lift enhancement, drag... aerodynamic benefits of a squealer tip geometry. Specifically, the squealer tip is known to reduce the discharge coefficient of the tip gap, thereby

  17. High density low-q discharges with D-shaped plasmas in Doublet III

    International Nuclear Information System (INIS)

    Nagami, Masayuki; Yoshida, Hidetoshi; Shinya, Kichiro; Yokomizo, Hideaki; Shimada, Michiya; Ioki, Kimihiro; Izumi, Shigeru; Kitsunezaki, Masao; Jahns, G.

    1981-07-01

    The maximum plasma current in Doublet III is found to be limited by disruptions when the limiter safety factor is approximately 2. However, due to the strong toroidal and shaping field effect on rotational transform at the outer plasma edge associated with a D-shape formation having a vertical elongation of 1.5, the safety factor q sub(a) * estimated from simple geometric considerations for D-shaped plasmas corresponds to values as low as 1.5. These discharges operate stably with considerably higher plasma current than most reactor design studies assume. These low-q discharges show excellent plasma performance: very flat spatial electron temperature progiles, high density operation with anti n sub(e)R/B sub(T) up to 7.8, and good energy confinement producing a volume average β of up to 1% with ohmic heating only. This operational regime appears to be applicable to future high β tokamaks with D-shaped cross section. (author)

  18. Nonlinear propagation of an elliptically shaped Gaussian laser beam in an overdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nayyar, V P; Soni, V S [Punjabi Univ., Patiala (India). Dept. of Physics

    1979-04-01

    The self-focusing and self defocusing of an elliptically shaped high power laser beam in an extradense plasma is discussed. On account of the ponderomotive force induced by the spatial variation of irradiance in the transverse plane, an electron density gradient is created in the overdense plasma where the beam can penetrate. Self-focusing of the beam in the x and y directions for different critical powers has been extensively studied.

  19. EFFECT OF PLASMA CUTTING PARAMETERS UPON SHAPES OF BEARING CURVE OF C45 STEEL SURFACE

    Directory of Open Access Journals (Sweden)

    Agnieszka Skoczylas

    2015-08-01

    Full Text Available The article presents the results of studies on the effect of plasma cutting technological parameters upon the shape of bearing curves and the parameters of the curve. The topography of surface formed by plasma cutting were analyzed. For measuring surface roughness and determining the bearing curve the appliance T8000 RC120 – 400 by Hommel-Etamic was used together with software.

  20. Design of an Integrated Plasma Control System and Extension of XSCTools to Ignitor

    Science.gov (United States)

    Albanese, R.; Ambrosino, G.; Artaserse, G.; Pironti, A.; Rubinacci, G.; Villone, F.; Ramogida, G.

    2010-11-01

    The performance of the integrated system for vertical stability, shape and plasma current control for the Ignitor machine has been assessed by means of the CREATELlinearized model of plasma responseootnotetextR. Albanese, F. Villone, Nucl. Fusion 38, 723 (1998) against a set of disturbances for the reference 11 MA limiter configuration and the 9 MA Double Null configuration. A new design, based on the methodology of the eXtreme Shape Controller (XSC) at JET, has been tested : by using all the shape control circuits with the exception of those used to control the vertical stability is possible to control up to four independent linear combinations of the 36 plasma-wall gaps. The results point out a substantial improvement in shape recovery, especially in the presence of a disturbance in li. The new shape controller can also automatically generate, via feedback control, new plasma shapes in the proximity of a given equilibrium configuration. The XSC ToolsootnotetextG. Ambrosino, R. Albanese et al., Fus. Eng.& Des. 74, 521 (2005) have been adapted and extended to develop linearized Ignitor models including 2D eddy currents and to solve inverse linearized plasma equilibria.

  1. Validation of ISTTOK Plasma Position Controller

    International Nuclear Information System (INIS)

    Valcarcel, D. F.; Carvalho, I. S.; Carvalho, B. B.; Fernandes, H.; Silva, C.; Duarte, P.; Duarte, A.; Carvalho, P. J.; Pereira, T.

    2008-01-01

    Active control of plasma position on the ISTTOK tokamak is of extreme importance due to the inherent instability caused by an unfavourable curvature of the external equilibrium magnetic field. The consequences of this instability can be suppressed by applying a dynamic equilibrium field. A digital real-time plasma position control system for ISTTOK has been developed to perform this task. This system uses magnetic measurements to determine the plasma position and feeds the control signal to power supplies that generate the equilibrium fields. After commissioning, the results obtained have shown some discrepancies between the magnetic plasma position reconstruction and several other diagnostics, such as tomography. This discrepancy at some extent is due to the effect of the external magnetic fields on the poloidal magnetic measurements. This work presents a study that addresses this issue. In a future work it will lead to the development of a corrected plasma position algorithm, aiming at obtaining improved performance of plasma discharges and controlled plasma column displacements

  2. Real time control of plasmas and ECRH systems on TCV

    International Nuclear Information System (INIS)

    Paley, J.I.; Berrino, J.; Coda, S.; Duval, B.P.; Felici, F.; Goodman, T.P.; Martin, Y.; Moret, J.M.; Piras, F.; Cruz, N.; Rodriques, A.P.; Santos, B.; Varandas, C.A.F.

    2009-01-01

    Developments in the real time control hardware on Tokamak a Configuration Variable (TCV) coupled with the flexibility of plasma shaping and electron cyclotron (EC) heating and current drive actuators are opening many opportunities to perform real time experiments and develop algorithms and methods for fusion applications. The ability to control magnetohydrodynamic instabilities is particularly important for achieving high performance fusion plasmas and EC is envisaged as a key actuator in maintaining high performance. We have successfully demonstrated control of the sawtooth instability using the EC launcher injection angle to modify the current profile around the q =1 surface. This paper presents an overview of recent real time control experiments on TCV, developments in the hardware and algorithms together with plans for the future.

  3. Chapter 8: Plasma operation and control [Progress in the ITER Physics Basis (PIPB)

    International Nuclear Information System (INIS)

    Gribov, Y.; Humphreys, D.; Kajiwara, K.; Lazarus, E.A.; Lister, J.B.; Ozeki, T.; Portone, A.; Shimada, M.; Sips, A.C.C.; Wesley, J.C.

    2007-01-01

    The ITER plasma control system has the same functional scope as the control systems in present tokamaks. These are plasma operation scenario sequencing, plasma basic control (magnetic and kinetic), plasma advanced control (control of RWMs, NTMs, ELMs, error fields, etc) and plasma fast shutdown. This chapter considers only plasma initiation and plasma basic control. This chapter describes the progress achieved in these areas in the tokamak experiments since the ITER Physics Basis (1999 Nucl. Fusion 39 2577) was written and the results of assessment of ITER to provide the plasma initiation and basic control. This assessment was done for the present ITER design (15 MA machine) at a more detailed level than it was done for the ITER design 1998 (21 MA machine) described in the ITER Physics Basis (1999 Nucl. Fusion 39 2577). The experiments on plasma initiation performed in DIII-D and JT-60U, as well as the theoretical studies performed for ITER, have demonstrated that, within specified assumptions on the plasma confinement and the impurity influx, ITER can produce plasma initiation in a low toroidal electric field (0.3 V m -1 ), if it is assisted by about 2 MW of ECRF heating. The plasma basic control includes control of the plasma current, position and shape-the plasma magnetic control, as well as control of other plasma global parameters or their profiles-the plasma performance control. The magnetic control is based on more reliable and simpler models of the control objects than those available at present for the plasma kinetic control. Moreover the real time diagnostics used for the magnetic control in many cases are more precise than those used for the kinetic control. Because of these reasons, the plasma magnetic control was developed for modern tokamaks and assessed for ITER better than the kinetic control. However, significant progress has been achieved in the plasma performance control during the last few years. Although the physics basis of plasma operation

  4. Shape of magnifiers affects controllability in children with visual impairment

    NARCIS (Netherlands)

    Liebrand-Schurink, Joyce; Boonstra, F. Nienke; van Rens, Ger H. M. B.; Cillessen, Antonius H. N.; Meulenbroek, Ruud G. J.; Cox, Ralf F. A.

    2016-01-01

    PurposeThis study aimed to examine the controllability of cylinder-shaped and dome-shaped magnifiers in young children with visual impairment. MethodsThis study investigates goal-directed arm movements in low-vision aid use (stand and dome magnifier-like object) in a group of young children with

  5. ISTTOK plasma control with the tomography diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, H.; Caralho, P.J.; Duarte, P.; Pereira, T.; Coelho, R.; Silva, C. [Association Euratom/IST, Institute of Plasmas and Nuclear Fusion, Technology Graduate Institute, P-1049-001 Lisbon (Portugal)

    2011-07-01

    A real-time plasma position control system is mandatory to achieve long duration (up to 250 ms), Alternating Current (AC) discharges on the ISTTOK tokamak. Such a system has been used for some time supported only on magnetic field diagnostic data. However, this system does not function accurately when the plasma current is low, rendering it inoperative during the plasma current reversal. A tomography diagnostic with 3 pinhole cameras and 8 silicone photodiode channels per camera was installed and customized to supply alternative plasma position to be used for plasma position control. As no filtering is applied, most of the radiation detected is in the visible/near-UV range. This system (i) executes a tomographic reconstruction, (ii) determines the average emissivity position from it, (iii) calculates the shift from the required position and (iv) supplies the vertical field power supply unit with the desired current value, all in less than 100 {mu}s. The horizontal magnetic field power supply unit is expected to be included in the system and will have no impact in the process time. This paper presents the tomography diagnostic architecture together with results of its scientific exploitation in ISTTOK AC discharges, where it has proven to be capable of supplying an accurate plasma position during the current reversal. The use of the tomography diagnostic for plasma position overcomes some limitations of the magnetic diagnostics, but poses challenges of its own such as blindness to plasma current direction. (authors)

  6. Plasma streams mixing in two-channel t-shaped magnetic filter

    International Nuclear Information System (INIS)

    Aksyonov, D.S.; Aksenov, I.I.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

    2011-01-01

    Ti-Al-N films were deposited by vacuum arc method. T-shaped magnetic filter with two channels was used for films preparation. Deposition was performed after aluminum and titanium separate plasma streams from two plasma sources were mixed into single one inside plasma duct having weakened magnetic field near its output. Obtained films have uniform distribution of composition and thickness on 180 mm diameter substrate surface. It was found that mixing and homogenization degree depends on nitrogen pressure, output magnetic field intensity and output- to-substrate distance. Film self-sputtering and aluminum preferential sputtering were observed for elevated negative substrate bias potentials.

  7. Spectral line shape simulation for electron stark-broadening of ion emitters in plasmas

    International Nuclear Information System (INIS)

    Dufour, Emmanuelle; Calisti, Annette; Talin, Bernard; Gigosos, Marco A.; Gonzalez, Manuel A.; Dufty, Jim W.

    2002-01-01

    Electron broadening for ions in plasmas is investigated in the framework of a simplified semi-classical model involving an ionic emitter imbedded in an electron gas. A regularized Coulomb potential that removes the divergence at short distances is postulated for the ion-electron interaction. Line shape simulations based on Molecular Dynamics for the ion impurity and the electrons, accounting for all the correlations, are reported. Comparisons with line shapes obtained with a quasi-particle model show expected correlation effects. Through an analysis of the results with the line shape code PPP, it is inferred that the correlation effect results mainly from the microfield dynamic properties

  8. Shaping Societal Impact: between control and cooperation

    NARCIS (Netherlands)

    Messemaker, M.; Wolbers, J.J.; Treurniet, W.; Boersma, F.K.; Comes, T; Fiedrich, F; Fortier, S; Geldermann, J; Muller, T

    2013-01-01

    In our modern society, the impact of large-scale safety and security incidents can be large and diverse. Yet, this societal impact is makeable and controllable to a limited extent. At best, the effect of concrete response actions is that the direct damage is somewhat reduced and that the recovery is

  9. Control of plasma layer in a fusion reactor correlated to DC motor control using PSO-ANFIS

    International Nuclear Information System (INIS)

    Mahapatra, Sakuntala; Daniel, Raju; Dey, Deep Narayan

    2013-01-01

    Plasma position and shape control is very crucial for the overall performance of the fusion reactor such as Tokamak. The quality of the discharge in the Saskatchewan TORus-Modified (STOR-M) tokamak is strongly related to the position of the plasma column within the discharge vessel. If the plasma column approaches too near the wall, then either minor or complete disruption occurs. Consequently it is necessary to be able to control dynamically the position of the plasma column throughout the entire discharge. Now a day's most fusion reactor employs the traditional PID controller for the confinement of plasma layer. Fuzzy logic is used for the control of Plasma layer. In this paper we have used the hybrid of PSO-ANFIS technique to control the speed of a DC motor. We have used two input parameters like speed, torque and output is firing angle. In our work first order Sugeno fuzzy model is taken with three rules and the parameters of Gaussian membership function is controlled by the PSO technique. PSO-ANFIS speed controller obtains better dynamic behavior and superior performance of the DC motor speed control. Similar approach can be correlated to the control of plasma layer. For the plasma control two inputs can be taken as plasma position ΔH and the plasma current and the single output, the control decision u(t). (author)

  10. Tensegrity Models and Shape Control of Vehicle Formations

    OpenAIRE

    Nabet, Benjamin; Leonard, Naomi Ehrich

    2009-01-01

    Using dynamic models of tensegrity structures, we derive provable, distributed control laws for stabilizing and changing the shape of a formation of vehicles in the plane. Tensegrity models define the desired, controlled, multi-vehicle system dynamics, where each node in the tensegrity structure maps to a vehicle and each interconnecting strut or cable in the structure maps to a virtual interconnection between vehicles. Our method provides a smooth map from any desired planar formation shape ...

  11. Tokamak plasma current disruption infrared control system

    International Nuclear Information System (INIS)

    Kugel, H.W.; Ulrickson, M.

    1987-01-01

    This patent describes a device for magnetically confining a plasma driven by a plasma current and contained within a toroidal vacuum chamber, the device having an inner toroidal limiter on an inside wall of the vacuum chamber and an arrangement for the rapid prediction and control in real time of a major plasma disruption. The arrangement is described which includes: scanning means sensitive to infrared radiation emanating from within the vacuum chamber, the infrared radiation indicating the temperature along a vertical profile of the inner toroidal limiter. The scanning means is arranged to observe the infrared radiation and to produce in response thereto an electrical scanning output signal representative of a time scan of temperature along the vertical profile; detection means for analyzing the scanning output signal to detect a first peaked temperature excursion occurring along the profile of the inner toroidal limiter, and to produce a detection output signal in repsonse thereto, the detection output signal indicating a real time prediction of a subsequent major plasma disruption; and plasma current reduction means for reducing the plasma current driving the plasma, in response to the detection output signal and in anticipation of a subsequent major plasma disruption

  12. Intensity and shape of spectral lines from laser-produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jamelot, G; Jaegle, P; Carillon, A; Wehenkel, C [Centre National de la Recherche Scientifique, 91 - Orsay (France); Paris-11 Univ., 91 - Orsay (France); Ecole Polytechnique, 91 - Palaiseau (France))

    1979-01-01

    In starting from spectral studies of multicharged ions in dense laser-produced plasmas, the main processes which determine the intensity and the shape of lines in the X-UV range are described. The role of radiation transfer is underlined. Intensity anomalies resulting from occurrence of population inversions are considered and a recent experiment performed for investigating such anomalies is described.

  13. Design and Architecture of SST-1 basic plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Kirit, E-mail: kpatel@ipr.res.in; Raju, D.; Dhongde, J.; Mahajan, K.; Chudasama, H.; Gulati, H.; Chauhan, A.; Masand, H.; Bhandarkar, M.; Pradhan, S.

    2016-11-15

    Highlights: • Reflective Memory network. • FPAG based Timing system for trigger distribution. • IRIG-B network for GPS time synchronization. • PMC based Digital Signal Processors and VME. • Simultaneous sampling ADC. - Abstract: Primary objective of SST-1 Plasma control system is to achieve Plasma position, shape and current profile control. Architecture of control system for SST-1 is distributed in nature. Fastest control loop time requirement of 100 μs is achieved using VME based simultaneous sampling ADCs, PMC based quad core DSP, Reflective Memory [RFM] based real-time network, VME based real-time trigger distribution network and Ethernet network. All the control loops for shape control, position control and current profile control share common signals from Magnetic diagnostic so it is planned to accommodate all the algorithms on the same PMC based quad core DSP module TS C-43. RFM based real-time data network replicate data from one node to next node in a ring network topology at sustained throughput rate of 13.4 MBps. Real-time Timing System network provides guaranteed trigger distribution in 3.8 μs from one node to all node of the network. Monitoring and configuration of different systems participating in the operation of SST-1 is done by Ethernet network. Magnetic sensors data is acquired using Pentek 6802 simultaneously sampling ADC card at the rate of 10KSPS. All the real-time raw data along with the control data will be archived using RFM network and SCSI HDD for the experiment duration of 1000 s. RFM network is also planned for real-time plotting of key parameter of Plasma during long experiment. After experiment this data is transferred to central storage server for archival purpose. This paper discusses the architecture and hardware implementation of the control system by describing all the involved hardware and software along with future plans for up-gradations.

  14. Optimization and analysis of shape of coaxial electrode for microwave plasma in water

    International Nuclear Information System (INIS)

    Hattori, Yoshiaki; Mukasa, Shinobu; Nomura, Shinfuku; Toyota, Hiromichi

    2010-01-01

    The effect of the shape of the electrode to generate 2.45 GHz microwave plasma in pure water is examined. Three variations of a common coaxial electrode are proposed, and compared according to the power required for plasma ignition and the position of plasma ignition in pure water at 6 kPa using a high-speed camera. These coaxial electrodes are calculated using three-dimensional finite-difference time-domain method calculations. The superior shape of coaxial electrode is found to be one with a flat plane on the tip of the inner electrode and dielectric substance located below the tip of the outer electrode. The position of the plasma ignition is related to the shape of the coaxial electrode. By solving the heat-conduction equation of water around the coaxial electrode taking into account the absorption of the microwave energy, the position of the plasma ignition is found to be not where electric field is the largest, but rather where temperature is maximized.

  15. Plasma control system upgrade and increased plasma stability in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Mastrovito, D., E-mail: dmastrovito@pppl.go [Princeton Plasma Physics Laboratory, P.O. Box 451 Princeton, NJ 08543 (United States); Gates, D.; Gerhard, S.; Lawson, J.; Ludescher-Furth, C.; Marsala, R. [Princeton Plasma Physics Laboratory, P.O. Box 451 Princeton, NJ 08543 (United States)

    2010-07-15

    Plasma control on the National Spherical Torus Experiment (NSTX) was previously accomplished using eight 333 MHz G4 processors built by Sky computers. Several planned improvements and additional control algorithms required significant upgrades to our real-time control computers and real-time data acquisition infrastructure. Several in-house modules have been designed and implemented including: the digital time stamp module (DITS) and for digital/analog front panel data port (FPDP) output, the FPDP output module digital/analog (FOMD/A). Standard Linux based Intel computers perform the real-time control tasks and InfiniBand as been employed for communication between a user-accessible 'host' server and the real-time computer. In addition to several independent real-time processes the General Atomics developed PCS (Bell (2006) ) system infrastructure continues to be used on NSTX. While maintaining previous functionality, improvements in the control system software include: an RWM feedback algorithm, beta feedback NBI control, more comprehensive error logging and trapping, more user-friendly interface, more complete archiving and restoring functionality, and better status reporting and diagnostic tools. Once completed, we succeeded in increasing overall plasma stability and decreasing control system latency by several times.

  16. Real-Time Software for the Compass Tokamak Plasma Control

    Energy Technology Data Exchange (ETDEWEB)

    Valcarcel, D.F.; Duarte, A.S.; Neto, A.; Carvalho, I.S.; Carvalho, B.B.; Fernandes, H.; Sousa, J. [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Lisboa (Portugal); Sartori, F. [Euratom-UKAEA, Culham Science Centre, Abingdon, OX14 3DB Oxon (United Kingdom); Janky, F.; Cahyna, P.; Hron, M.; Panek, R. [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM / IPP.CR, Prague (Costa Rica)

    2009-07-01

    This poster presents the flexible and high-performance real time system that guarantees the desired time cycles for plasma control on the COMPASS tokamak: 500 {mu}s for toroidal field, current, equilibrium and shaping; 50 {mu}s for fast control of the equilibrium and vertical instability. This system was developed on top of a high-performance processor and a software framework (MARTe) tailored for real-time. The preliminary measurements indicate that the time constraints will be met on the final solution. The system allows the making of modifications in the future to improve software components. (A.C.)

  17. Novel aspects of plasma control in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, D.; Jackson, G.; Walker, M.; Welander, A. [General Atomics P.O. Box 85608, San Diego, California 92186-5608 (United States); Ambrosino, G.; Pironti, A. [CREATE/University of Naples Federico II, Napoli (Italy); Vries, P. de; Kim, S. H.; Snipes, J.; Winter, A.; Zabeo, L. [ITER Organization, St. Paul Lez durance Cedex (France); Felici, F. [Eindhoven University of Technology, Eindhoven (Netherlands); Kallenbach, A.; Raupp, G.; Treutterer, W. [Max-Planck Institut für Plasmaphysik, Garching (Germany); Kolemen, E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States); Lister, J.; Sauter, O. [Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Moreau, D. [CEA, IRFM, 13108 St. Paul-lez Durance (France); Schuster, E. [Lehigh University, Bethlehem, Pennsylvania (United States)

    2015-02-15

    ITER plasma control design solutions and performance requirements are strongly driven by its nuclear mission, aggressive commissioning constraints, and limited number of operational discharges. In addition, high plasma energy content, heat fluxes, neutron fluxes, and very long pulse operation place novel demands on control performance in many areas ranging from plasma boundary and divertor regulation to plasma kinetics and stability control. Both commissioning and experimental operations schedules provide limited time for tuning of control algorithms relative to operating devices. Although many aspects of the control solutions required by ITER have been well-demonstrated in present devices and even designed satisfactorily for ITER application, many elements unique to ITER including various crucial integration issues are presently under development. We describe selected novel aspects of plasma control in ITER, identifying unique parts of the control problem and highlighting some key areas of research remaining. Novel control areas described include control physics understanding (e.g., current profile regulation, tearing mode (TM) suppression), control mathematics (e.g., algorithmic and simulation approaches to high confidence robust performance), and integration solutions (e.g., methods for management of highly subscribed control resources). We identify unique aspects of the ITER TM suppression scheme, which will pulse gyrotrons to drive current within a magnetic island, and turn the drive off following suppression in order to minimize use of auxiliary power and maximize fusion gain. The potential role of active current profile control and approaches to design in ITER are discussed. Issues and approaches to fault handling algorithms are described, along with novel aspects of actuator sharing in ITER.

  18. Improved Frequency Fluctuation Model for Spectral Line Shape Calculations in Fusion Plasmas

    International Nuclear Information System (INIS)

    Ferri, S.; Calisti, A.; Mosse, C.; Talin, B.; Lisitsa, V.

    2010-01-01

    A very fast method to calculate spectral line shapes emitted by plasmas accounting for charge particle dynamics and effects of an external magnetic field is proposed. This method relies on a new formulation of the Frequency Fluctuation Model (FFM), which yields to an expression of the dynamic line profile as a functional of the static distribution function of frequencies. This highly efficient formalism, not limited to hydrogen-like systems, allows to calculate pure Stark and Stark-Zeeman line shapes for a wide range of density, temperature and magnetic field values, which is of importance in plasma physics and astrophysics. Various applications of this method are presented for conditions related to fusion plasmas.

  19. A comparison of sawtooth oscillations in bean and oval shaped plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, E A [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States); Waelbroeck, F L [University of Texas, Austin, Texas 78712 (United States); Luce, T C [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Austin, M E [University of Texas, Austin, Texas 78712 (United States); Burrell, K H [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Ferron, J R [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Hyatt, A W [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Osborne, T H [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Chu, M S [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Brennan, D P [Massachussets Institute of Technology, Cambridge, Massachusetts (United States); Gohil, P; Groebner, R J; Hsieh, C L [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Jayakumar, R J [Lawrence Livermore National Laboratory, Livermore, California (United States); Lao, L L [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Lohr, J [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Makowski, M A [Lawrence Livermore National Laboratory, Livermore, California (United States); Petty, C C; Politzer, P A; Prater, R [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Rhodes, T L [University of California-Los Angeles, Los Angeles, California (United States); Scoville, J T; Strait, E J; Turnbull, A D; Wade, M R [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Wang, G [University of California-Los Angeles, Los Angeles, California (United States); Reimerdes, H [Columbia University, New York, New York (United States); Zhang, C [ASIPP (China)

    2006-08-15

    The effect of plasma shape on sawtooth oscillations in the DIII-D tokamak plasmas is investigated by comparing discharges with cross-sections shaped like a bean and an oval. The two shapes are designed so that the Mercier instability threshold is reached when the axial safety factor is below unity for the bean and above unity for the oval cross-sections. This allows the role of interchange modes to be differentiated from that of the kink-tearing mode. The differences in the nature of the sawtooth oscillations in the bean and oval discharges are found to be determined primarily by extreme differences in the electron heat transport during the reheat. In both cases, the axial safety factor is found to be near unity following the crash. (letter to the editor)

  20. Magnetic Configuration Control of ITER Plasmas

    International Nuclear Information System (INIS)

    Albanese, R.; Artaserse, G.; Mattei, M.; Ambrosino, G.; Crisanti, F.; Tommasi, G. de; Fresa, R.; Portone, A.; Sartori, F.; Villone, F.

    2006-01-01

    The aim of this paper is to review the capability of the ITER Poloidal Field (PF) system of controlling the broad range of plasma configurations presently forecasted during ITER operation. The attention is focused on the axi-symmetric aspects of plasma magnetic configuration control since they pose the greatest challenges in terms of control power and they have the largest impact on machine capital cost. The paper is broadly divided in two main sections devoted, respectively, to open loop (feed-forward) and closed loop (feedback) control. In the first part of the study the PF system is assessed with respect to the initiation, ramp-up, sustained burn, ramp-down phases of the main plasma inductive scenario. The limiter-to-divertor configuration transition phase is considered in detail with the aim of assessing the PF capability to form an X-point at the lowest possible current and, therefore, to relax the thermal load on the limiter surfaces. Moreover, during the sustained burn it is important to control plasmas with a broad range of current density profiles. In the second part of the study the plasma vertical feedback control requirements are assessed in details, in particular for the high elongation configurations achievable during the early limiter-to-X point transition phase. Non-rigid plasma displacement models are used to assess the control system voltage and current requirements of different radial field control circuits obtained, for example, by connecting the outermost PF coils, some CS coils, coils sub-sections etc. At last, the main 3D effects of the vessel ports are modeled and their impact of vertical stabilization evaluated. (author)

  1. Plasma position control in SST1 tokamak

    Indian Academy of Sciences (India)

    also placed inside the vessel, however the controller would ignore fast but insignificant changes in radius arising ... poloidal cross-sectional view of the SST1 plasma along with the stabilizers are shown in figure 1 and ... [1] model which has shown excellent agreement with control experiments in TCV tokamak and also with ...

  2. Experimental effective shape control of a powered transfemoral prosthesis.

    Science.gov (United States)

    Gregg, Robert D; Lenzi, Tommaso; Fey, Nicholas P; Hargrove, Levi J; Sensinger, Jonathon W

    2013-06-01

    This paper presents the design and experimental implementation of a novel feedback control strategy that regulates effective shape on a powered transfemoral prosthesis. The human effective shape is the effective geometry to which the biological leg conforms--through movement of ground reaction forces and leg joints--during the stance period of gait. Able-bodied humans regulate effective shapes to be invariant across conditions such as heel height, walking speed, and body weight, so this measure has proven to be a very useful tool for the alignment and design of passive prostheses. However, leg joints must be actively controlled to assume different effective shapes that are unique to tasks such as standing, walking, and stair climbing. Using our previous simulation studies as a starting point, we model and control the effective shape as a virtual kinematic constraint on the powered Vanderbilt prosthetic leg with a custom instrumented foot. An able-bodied subject used a by-pass adapter to walk on the controlled leg over ground and over a treadmill. These preliminary experiments demonstrate, for the first time, that effective shape (or virtual constraints in general) can be used to control a powered prosthetic leg.

  3. Architectural concept for the ITER Plasma Control System

    Energy Technology Data Exchange (ETDEWEB)

    Treutterer, W., E-mail: Wolfgang.Treutterer@ipp.mpg.de [Max-Planck Institute for Plasma Physics, EURATOM Association, Garching (Germany); Humphreys, D., E-mail: humphreys@fusion.gat.com [General Atomics, San Diego, CA (United States); Raupp, G., E-mail: Gerhard.Raupp@ipp.mpg.de [Max-Planck Institute for Plasma Physics, EURATOM Association, Garching (Germany); Schuster, E., E-mail: schuster@lehigh.edu [Lehigh University, Bethlehem, PA (United States); Snipes, J., E-mail: Joseph.Snipes@iter.org [ITER Organization, 13115 St. Paul-lez-Durance (France); De Tommasi, G., E-mail: detommas@unina.it [CREATE/Università di Napoli Federico II, Napoli (Italy); Walker, M., E-mail: walker@fusion.gat.com [General Atomics, San Diego, CA (United States); Winter, A., E-mail: Axel.Winter@iter.org [ITER Organization, 13115 St. Paul-lez-Durance (France)

    2014-05-15

    The plasma control system is a key instrument for successfully investigating the physics of burning plasma at ITER. It has the task to execute an experimental plan, known as pulse schedule, in the presence of complex relationships between plasma parameters like temperature, pressure, confinement and shape. The biggest challenge in the design of the control system is to find an adequate breakdown of this task in a hierarchy of feedback control functions. But it is also important to foresee structures that allow handling unplanned exceptional situations to protect the machine. Also the management of the limited number of actuator systems for multiple targets is an aspect with a strong impact on system architecture. Finally, the control system must be flexible and reconfigurable to cover the manifold facets of plasma behaviour and investigation goals. In order to prepare the development of a control system for ITER plasma operation, a conceptual design has been proposed by a group of worldwide experts and reviewed by an ITER panel in 2012. In this paper we describe the fundamental principles of the proposed control system architecture and how they were derived from a systematic collection and analysis of use cases and requirements. The experience and best practices from many fusion devices and research laboratories, augmented by the envisaged ITER specific tasks, build the foundation of this collection. In the next step control functions were distilled from this input. An analysis of the relationships between the functions allowed sequential and parallel structures, alternate branches and conflicting requirements to be identified. Finally, a concept of selectable control layers consisting of nested “compact controllers” was synthesised. Each control layer represents a cascaded scheme from high-level to elementary controllers and implements a control hierarchy. The compact controllers are used to resolve conflicts when several control functions would use the same

  4. Architectural concept for the ITER Plasma Control System

    International Nuclear Information System (INIS)

    Treutterer, W.; Humphreys, D.; Raupp, G.; Schuster, E.; Snipes, J.; De Tommasi, G.; Walker, M.; Winter, A.

    2014-01-01

    The plasma control system is a key instrument for successfully investigating the physics of burning plasma at ITER. It has the task to execute an experimental plan, known as pulse schedule, in the presence of complex relationships between plasma parameters like temperature, pressure, confinement and shape. The biggest challenge in the design of the control system is to find an adequate breakdown of this task in a hierarchy of feedback control functions. But it is also important to foresee structures that allow handling unplanned exceptional situations to protect the machine. Also the management of the limited number of actuator systems for multiple targets is an aspect with a strong impact on system architecture. Finally, the control system must be flexible and reconfigurable to cover the manifold facets of plasma behaviour and investigation goals. In order to prepare the development of a control system for ITER plasma operation, a conceptual design has been proposed by a group of worldwide experts and reviewed by an ITER panel in 2012. In this paper we describe the fundamental principles of the proposed control system architecture and how they were derived from a systematic collection and analysis of use cases and requirements. The experience and best practices from many fusion devices and research laboratories, augmented by the envisaged ITER specific tasks, build the foundation of this collection. In the next step control functions were distilled from this input. An analysis of the relationships between the functions allowed sequential and parallel structures, alternate branches and conflicting requirements to be identified. Finally, a concept of selectable control layers consisting of nested “compact controllers” was synthesised. Each control layer represents a cascaded scheme from high-level to elementary controllers and implements a control hierarchy. The compact controllers are used to resolve conflicts when several control functions would use the same

  5. Determination of the plasma column shape in the Tokamak Novillo cross section by magnetic probes

    International Nuclear Information System (INIS)

    Hernandez Omana, A.

    1993-01-01

    The determination of plasma cross section shape in Tokamaks is an important diagnostic method for equilibrium conditions analysis. In this work, it is obtained a time dependent variation of the plasma column cross section in Novillo Tokamak. The experimental method is based on using one magnetic probe, which is installed inside of the vacuum vessel in a 1 mm. wall thickness stainless steel tube, in the protected region of the limiter shadow. The plasma column cross section is determined measuring the poloidal magnetic field produced by the plasma current. This method, now running for determining the plasma column shape, requires the measurement of magnetic present field outside plasma column. The measurements are carried out from a set of small coils, which are located inside the vacuum chamber in the radial and poloidal direction, so we can measure magnetic field with no current attenuations produced by the penetration time of the stainless steel vacuum chamber. The magnetic probe detect a real time variation of magnetic flux passing through them. In order to obtain the magnetic field values, it is required that the electric signals coming from the magnetic probe be integrated, this operation is carried out by active circuits located between the probe signal and one oscilloscope. The integrated signals can be exhibited photographed on the oscilloscope display. (Author)

  6. Numerical and Experimental Investigation on Electromagnetic Attenuation by Semi-Ellipsoidal Shaped Plasma

    International Nuclear Information System (INIS)

    He Xiang; Tang Chunmei; Chen Jianping; Chen Yudong; Zeng Xiaojun; Zhang Yachun

    2015-01-01

    Some reports presented that the radar cross section (RCS) from the radar antenna of military airplanes can be reduced by using a low-temperature plasma screen. This paper gives a numerical and experimental analysis of this RCS-reduction method. The shape of the plasma screen was designed as a semi-ellipsoid in order to make full use of the space in the radar dome. In simulations, we discussed the scattering of the electromagnetic (EM) wave by a perfect electric conductor (PEC) covered with this plasma screen using the finite-difference-time-domain (FDTD) method. The variations of their return loss as a function of wave frequency, plasma density profile, and collision frequency were presented. In the experiments, a semi-ellipsoidal shaped plasma screen was produced. Electromagnetic attenuation of 1.5 GHz EM wave was measured for a radio frequency (RF) power of 5 kW at an argon pressure of 200-1150 Pa. A good agreement is found between simulated and experimental results. It can be confirmed that the plasma screen is useful in applications for stealth of radar antenna. (paper)

  7. A computational model for the confinement and performance of circular and D-shaped Tokamak plasmas

    International Nuclear Information System (INIS)

    Nicolai, A.; Boerner, P.

    1987-10-01

    A combined one-dimensional and two-dimensional description of toroidal and axisymmetric plasmas is presented which is based essentially on an equilibrium solver resorting to the fast Buneman invertor and two one-dimensional transport codes describing the protium, deuterium, tritium, and plasma energy inventory and accounting for three impurity species; it is employed to compute the time evolution of Tokamak plasmas. The attempt was made to achieve a consistent modelling of the transport and equilibrium phenomena in a plasma which interacts with the peripheral devices for e.g. confinement, plasma heating and limitation of the plasma aperture. The equilibrium solver is connected to a coil submodule computing the poloidal field coil currents maintaining the designed plasma shape approximately. A surface current density standing for the magnetization of the iron core and the yokes is calculated by means of the module for the transformer iron. This module is linked to the equilibrium solver as well so that consistency between the coil currents, the plasma current distribution and the magnetization of the transformer iron is achieved. (orig./GG)

  8. G2 cubic transition between two circles with shape control

    Science.gov (United States)

    Habib, Zulfiqar; Sakai, Manabu

    2009-01-01

    This paper describes a method for joining two circles with an S-shaped or with a broken back C-shaped transition curve, composed of at most two spiral segments. In highway and railway route design or car-like robot path planning, it is often desirable to have such a transition. It is shown that a single cubic curve can be used for blending or for a transition curve preserving G2 continuity with local shape control parameter and more flexible constraints. Provision of the shape parameter and flexibility provide freedom to modify the shape in a stable manner which is an advantage over previous work by Meek, Walton, Sakai and Habib.

  9. Reference-shaping adaptive control by using gradient descent optimizers.

    Directory of Open Access Journals (Sweden)

    Baris Baykant Alagoz

    Full Text Available This study presents a model reference adaptive control scheme based on reference-shaping approach. The proposed adaptive control structure includes two optimizer processes that perform gradient descent optimization. The first process is the control optimizer that generates appropriate control signal for tracking of the controlled system output to a reference model output. The second process is the adaptation optimizer that performs for estimation of a time-varying adaptation gain, and it contributes to improvement of control signal generation. Numerical update equations derived for adaptation gain and control signal perform gradient descent optimization in order to decrease the model mismatch errors. To reduce noise sensitivity of the system, a dead zone rule is applied to the adaptation process. Simulation examples show the performance of the proposed Reference-Shaping Adaptive Control (RSAC method for several test scenarios. An experimental study demonstrates application of method for rotor control.

  10. Introduction to plasma physics and controlled fusion

    CERN Document Server

    Chen, Francis F

    2016-01-01

    The third edition of this classic text presents a complete introduction to plasma physics and controlled fusion, written by one of the pioneering scientists in this expanding field.  It offers both a simple and intuitive discussion of the basic concepts of the subject matter and an insight into the challenging problems of current research. This outstanding text offers students a painless introduction to this important field; for teachers, a large collection of problems; and for researchers, a concise review of the fundamentals as well as original treatments of a number of topics never before explained so clearly.  In a wholly lucid manner the second edition covered charged-particle motions, plasmas as fluids, kinetic theory, and nonlinear effects.  For the third edition, two new chapters have been added to incorporate discussion of more recent advances in the field.  The new chapter 9 on Special Plasmas covers non-neutral plasmas, pure electron plasmas, solid and ultra-cold plasmas, pair-ion plasmas, d...

  11. Boundary plasma control with the ergodic divertor

    International Nuclear Information System (INIS)

    Ghendrih, Ph.; Becoulet, M.; Beyer, P.

    1999-01-01

    Ergodic divertor experiments on Tore Supra provide evidence of significant control of plasma-wall interaction. Theoretical investigation of the laminar region (i.e. governed by parallel transport) indicates that control of the plasma state at the target plate can be achieved with plasma states similar to that observed with the axisymmetric divertor. Analysis of the temperature field with a 2-D test particle code allows one to recover the observed spatial modulation and shows that an intrinsic barrier appears to develop at the separatrix. Energy deposition peaking, analysed with a 3-D code, is strongly reduced when moderate transverse transport is considered. Possible control of upstream parameters can thus be achieved in the ergodic region, for instance a lowering of the parallel energy flux by cross field transport. (author)

  12. Boundary plasma control with the ergodic divertor

    International Nuclear Information System (INIS)

    Ghendrih, Ph.; Becoulet, M.; Beyer, P.

    2001-01-01

    Ergodic divertor experiments on Tore Supra provide evidence of significant control of plasma-wall interaction. Theoretical investigation of the laminar region (i.e. governed by parallel transport) indicates that control of the plasma state at the target plate can be achieved with plasma states similar to that observed with the axisymmetric divertor. Analysis of the temperature field with a 2-D test particle code allows one to recover the observed spatial modulation and shows that an intrinsic barrier appears to develop at the separatrix. Energy deposition peaking, analysed with a 3-D code, is strongly reduced when moderate transverse transport is considered. Possible control of upstream parameters can thus be achieved in the ergodic region, for instance a lowering of the parallel energy flux by cross field transport. (author)

  13. Introduction to plasma physics and controlled fusion

    CERN Document Server

    Chen, Francis F

    1984-01-01

    This complete introduction to plasma physics and controlled fusion by one of the pioneering scientists in this expanding field offers both a simple and intuitive discussion of the basic concepts of this subject and an insight into the challenging problems of current research. In a wholly lucid manner the work covers single-particle motions, fluid equations for plasmas, wave motions, diffusion and resistivity, Landau damping, plasma instabilities and nonlinear problems. For students, this outstanding text offers a painless introduction to this important field; for teachers, a large collection of problems; and for researchers, a concise review of the fundamentals as well as original treatments of a number of topics never before explained so clearly. This revised edition contains new material on kinetic effects, including Bernstein waves and the plasma dispersion function, and on nonlinear wave equations and solitons.

  14. Shape of magnifiers affects controllability in children with visual impairment.

    Science.gov (United States)

    Liebrand-Schurink, Joyce; Boonstra, F Nienke; van Rens, Ger H M B; Cillessen, Antonius H N; Meulenbroek, Ruud G J; Cox, Ralf F A

    2016-12-01

    This study aimed to examine the controllability of cylinder-shaped and dome-shaped magnifiers in young children with visual impairment. This study investigates goal-directed arm movements in low-vision aid use (stand and dome magnifier-like object) in a group of young children with visual impairment (n = 56) compared to a group of children with normal sight (n = 66). Children with visual impairment and children with normal sight aged 4-8 years executed two types of movements (cyclic and discrete) in two orientations (vertical or horizontal) over two distances (10 cm and 20 cm) with two objects resembling the size and shape of regularly prescribed stand and dome magnifiers. The visually impaired children performed slower movements than the normally sighted children. In both groups, the accuracy and speed of the reciprocal aiming movements improved significantly with age. Surprisingly, in both groups, the performance with the dome-shaped object was significantly faster (in the 10 cm condition and 20 cm condition with discrete movements) and more accurate (in the 20 cm condition) than with the stand-shaped object. From a controllability perspective, this study suggests that it is better to prescribe dome-shaped than cylinder-shaped magnifiers to young children with visual impairment. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  15. Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

    International Nuclear Information System (INIS)

    Kan Caixia; Zhu Jiejun; Zhu Xiaoguang

    2008-01-01

    This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {1 1 1} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {100} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {1 0 0} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes

  16. Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

    Science.gov (United States)

    Kan, Cai-Xia; Zhu, Jie-Jun; Zhu, Xiao-Guang

    2008-08-01

    This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {1 1 1} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {100} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {1 0 0} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

  17. Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Kan Caixia [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 211100 (China); Zhu Jiejun [Department of Physics, Nanjing University, Nanjing 210093 (China); Zhu Xiaoguang [Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)], E-mail: cxkan@nuaa.edu.cn

    2008-08-07

    This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {l_brace}1 1 1{r_brace} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {l_brace}100{r_brace} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {l_brace}1 0 0{r_brace} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

  18. Dependence of CIT [Compact Ignition Tokamak] PF [poloidal field] coil currents on profile and shape parameters using the Control Matrix

    International Nuclear Information System (INIS)

    Strickler, D.J.; Peng, Y-K.M.; Jardin, S.C.; Pomphrey, N.

    1990-01-01

    The plasma shaping flexibility of the Compact Ignition Tokamak (CIT) poloidal field (PF) coil set is demonstrated through MHD equilibrium calculations of optimal PF coil current distributions and their variation with poloidal beta, internal inductance, plasma 95% elongation, and 95% triangularity. Calculations of the magnetic stored energy are used to compare solutions associated with various plasma parameters. The Control Matrix (CM) equilibrium code, together with the nonlinear equation and numerical optimization software packages HYBRD, and VMCON, respectively, are used to find equilibrium coil current distributions for fixed divertor geometry, volt-seconds, and plasma profiles in order to isolate the dependence on individual parameters. A reference equilibrium and coil current distribution are chosen, and correction currents dI are determined using the CM equilibrium method to obtain other specified plasma shapes. The reference equilibrium is the κ = 2 divertor at beginning of flattop (BOFT) with a minimum stored energy solution for the coil current distribution. The pressure profile function is fixed

  19. Critical β of a D-shaped toroidal plasma with sharp boundary

    International Nuclear Information System (INIS)

    Kito, M.

    1981-01-01

    Under the cap-cyclide coordinate system, the marginal stability of a sharp boundary toroidal plasma whose cross section is D shaped is examined using the energy principle. The analytical results are valid for arbitrary b, arbitrary aspect ratio, and arbitrary elongation of the plasma. There exists a maximum elongation for a given aspect ratio. The critical beta b/sub c/ is computed for several aspect ratios and elongations. For given aspect ratio, b/sub c/ increases as long as the elongation increases

  20. Cold plasma: Quality control and regulatory considerations

    Science.gov (United States)

    In recent years, cold plasma has emerged as a promising antimicrobial treatment for fresh and fresh-cut produce, nuts, spices, seeds, and other foods. Research has demonstrated effective control of human pathogens such as Salmonella, Listeria monocytogenes, Escherichia coli O157:H7, norovirus, and o...

  1. Plasma surface interactions in controlled fusion devices

    International Nuclear Information System (INIS)

    Ghendrih, Ph.; Becoulet, M.; Costanzo, L.

    2000-07-01

    This report brings together all the contributions of EURATOM/CEA association to the 14. international conference on plasma surface interactions in controlled fusion devices. 24 papers are presented and they deal mainly with the ergodic divertor and the first wall of Tore-supra tokamak

  2. Plasma surface interactions in controlled fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Ghendrih, Ph.; Becoulet, M.; Costanzo, L. [and others

    2000-07-01

    This report brings together all the contributions of EURATOM/CEA association to the 14. international conference on plasma surface interactions in controlled fusion devices. 24 papers are presented and they deal mainly with the ergodic divertor and the first wall of Tore-supra tokamak.

  3. Research and Development Trend of Shape Control for Cold Rolling Strip

    Science.gov (United States)

    Wang, Dong-Cheng; Liu, Hong-Min; Liu, Jun

    2017-09-01

    Shape is an important quality index of cold rolling strip. Up to now, many problems in the shape control domain have not been solved satisfactorily, and a review on the research progress in the shape control domain can help to seek new breakthrough directions. In the past 10 years, researches and applications of shape control models, shape control means, shape detection technology, and shape control system have achieved significant progress. In the aspect of shape control models, the researches in the past improve the accuracy, speed and robustness of the models. The intelligentization of shape control models should be strengthened in the future. In the aspect of the shape control means, the researches in the past focus on the roll optimization, mill type selection, process optimization, local strip shape control, edge drop control, and so on. In the future, more attention should be paid to the coordination control of both strip shape and other quality indexes, and the refinement of control objective should be strengthened. In the aspects of shape detection technology and shape control system, some new types of shape detection meters and shape control systems are developed and have successfully industrial applications. In the future, the standardization of shape detection technology and shape control system should be promoted to solve the problem of compatibility. In general, the four expected development trends of shape control for cold rolling strip in the future are intelligentization, coordination, refinement, and standardization. The proposed research provides new breakthrough directions for improving shape quality.

  4. Control of cell nucleus shapes via micropillar patterns.

    Science.gov (United States)

    Pan, Zhen; Yan, Ce; Peng, Rong; Zhao, Yingchun; He, Yao; Ding, Jiandong

    2012-02-01

    We herein report a material technique to control the shapes of cell nuclei by the design of the microtopography of substrates to which the cells adhere. Poly(D,L-lactide-co-glycolide) (PLGA) micropillars or micropits of a series of height or depth were fabricated, and some surprising self deformation of the nuclei of bone marrow stromal cells (BMSCs) was found in the case of micropillars with a sufficient height. Despite severe nucleus deformation, BMSCs kept the ability of proliferation and differentiation. We further demonstrated that the shapes of cell nuclei could be regulated by the appropriate micropillar patterns. Besides circular and elliptoid shapes, some unusual nucleus shapes of BMSCs have been achieved, such as square, cross, dumbbell, and asymmetric sphere-protrusion. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  5. Novel magnetic controlled plasma sputtering method

    International Nuclear Information System (INIS)

    Axelevich, A.; Rabinovich, E.; Golan, G.

    1996-01-01

    A novel method to improve thin film vacuum sputtering is presented. This method is capable of controlling the sputtering plasma via an external set of magnets, in a similar fashion to the tetrode sputtering method. The main advantage of the Magnetic Controlled Plasma Sputtering (MCPS) is its ability to independently control all deposition parameters without any interference or cross-talk. Deposition rate, using the MCPS, is found to be almost twice the rate of triode and tetrode sputtering techniques. Experimental results using the MCPS to deposit Ni layers are described. It was demonstrated that using the MCPS method the ion beam intensity at the target is a result of the interaction of a homogeneous external magnetic field and the controlling magnetic fields. The MCPS method was therefore found to be beneficial for the production of pure stoichiometric thin solid films with high reproducibility. This method could be used for the production of compound thin films as well. (authors)

  6. Ultrafast method of calculating the dynamic spectral line shapes for integrated modelling of plasmas

    International Nuclear Information System (INIS)

    Lisitsa, V.S.

    2009-01-01

    An ultrafast code for spectral line shape calculations is presented to be used in the integrated modelling of plasmas. The code is based on the close analogy between two mechanisms: (i) Dicke narrowing of the Doppler-broadened spectral lines and (ii) transition from static to impact regime in the Stark broadening. The analogy makes it possible to describe the dynamic Stark broadening in terms of an analytical functional of the static line shape. A comparison of new method with the widely used Frequency Fluctuating Method (FFM) developed by the Marseille University group (B. Talin, R. Stamm, et al.) shows good agreement, with the new method being faster than the standard FFM by nearly two orders of magnitude. The method proposed may significantly simplify the radiation transport modeling and opens new possibilities for integrated modeling of the edge and divertor plasma in tokamaks. (author)

  7. The COMPASS Tokamak Plasma Control Software Performance

    Czech Academy of Sciences Publication Activity Database

    Valcárcel, D.F.; Neto, A.; Carvalho, I.S.; Carvalho, B.B.; Fernandes, H.; Sousa, J.; Janky, F.; Havlíček, Josef; Beňo, R.; Horáček, Jan; Hron, Martin; Pánek, Radomír

    2011-01-01

    Roč. 58, č. 4 (2011), s. 1490-1496 ISSN 0018-9499. [Real Time Conference, RT10/17th./. Lisboa, 24.05.2010-28.05.2010] R&D Projects: GA MŠk 7G09042; GA ČR GD202/08/H057 Institutional research plan: CEZ:AV0Z20430508 Keywords : Real-Time * ATCA * Data Acquisition * Plasma Control Software Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.447, year: 2011 http://dx.doi.org/10.1109/TNS.2011.2143726

  8. Plasma Edge Control in Tore Supra

    International Nuclear Information System (INIS)

    Evans, T.E.; Mioduszewski, P.K.; Foster, C.; Haste, G.; Horton, L.; Grosman, A.; Ghendrih, P.; Chatelier, M.; Capes, H.; Michelis, C. De; Fall, T.; Geraud, A.; Grisolia, C.; Guilhem, D.; Hutter, T.

    1990-01-01

    TORE SUPRA is a large superconducting tokamak designed for sustaining long inductive pulses (t∼ 30 s). In particular, all the first wall components have been designed for steady-state heat and particle exhaust, particle injection, and additional heating. In addition to these technological assets, a strict control of the plasma-wall interactions is required. This has been done at low power: experiments with ohmic heating have been mainly devoted to the pump limiter, ergodic divertor and pellet injection experiments. Some specific problems arising in large tokamaks are encountered; the pump limiter and the ergodic divertor yield the expected effects on the plasma edge. The effects on the bulk are discussed

  9. Nonrigid, Linear Plasma Response Model Based on Perturbed Equilibria for Axisymmetric Tokamak Control Design

    International Nuclear Information System (INIS)

    Welander, A.S.; Deranian, R.D.; Humphreys, D.A.; Leuer, J.A.; Walker, M.L.

    2005-01-01

    Tokamak control design relies on an accurate linear model of the plasma response, which can often dominate the local field variations in regions under active feedback control. For example, when fluxes at selected points on the plasma boundary are regulated in DIII-D, the plasma response to a change in a coil current gives rise to a flux change which can be larger than and opposite to the flux change caused by the coil alone.In the past, rigid plasma models have been used for linear stability and shape control design. In a rigid model, the plasma current profile is considered fixed and moves rigidly in response to control coils to maintain radial and vertical force balance. In a nonrigid model, however, changes in the plasma shape and current profile are taken into account. Such models are expected to be important for future advanced tokamak control design. The present work describes development of a nonrigid plasma response model for high-accuracy multivariable control design and provides comparisons of model predictions against DIII-D experimental data. The linear perturbed plasma response model is calculated rapidly from an existing equilibrium solution

  10. Study of Globus-M Tokamak Poloidal System and Plasma Position Control

    Science.gov (United States)

    Dokuka, V. N.; Korenev, P. S.; Mitrishkin, Yu. V.; Pavlova, E. A.; Patrov, M. I.; Khayrutdinov, R. R.

    2017-12-01

    In order to provide efficient performance of tokamaks with vertically elongated plasma position, control systems for limited and diverted plasma configuration are required. The accuracy, stability, speed of response, and reliability of plasma position control as well as plasma shape and current control depend on the performance of the control system. Therefore, the problem of the development of such systems is an important and actual task in modern tokamaks. In this study, the measured signals from the magnetic loops and Rogowski coils are used to reconstruct the plasma equilibrium, for which linear models in small deviations are constructed. We apply methods of the H∞-optimization theory to the synthesize control system for vertical and horizontal position of plasma capable to working with structural uncertainty of the models of the plant. These systems are applied to the plasma-physical DINA code which is configured for the tokamak Globus-M plasma. The testing of the developed systems applied to the DINA code with Heaviside step functions have revealed the complex dynamics of plasma magnetic configurations. Being close to the bifurcation point in the parameter space of unstable plasma has made it possible to detect an abrupt change in the X-point position from the top to the bottom and vice versa. Development of the methods for reconstruction of plasma magnetic configurations and experience in designing plasma control systems with feedback for tokamaks provided an opportunity to synthesize new digital controllers for plasma vertical and horizontal position stabilization. It also allowed us to test the synthesized digital controllers in the closed loop of the control system with the DINA code as a nonlinear model of plasma.

  11. Vacuum Plasma Spray Formed High Transition Temperature Shape Memory Alloys, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Smart materials control of aero-surfaces based on shape memory alloys (SMA) is seeing increased use for improving of future subsonic fixed wing aircraft aero-surface...

  12. Controlling the Shapes of Silver Nanocrystals with Different Capping Agents

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, J.; Tao, J.; Zheng, Y.; Rycenga, M.; Li, Z.-Y.; Zhang, Q.A.; Zhu, Y.; Xia, Y.

    2010-06-30

    This paper provides direct evidence to support the role of a capping agent in controlling the evolution of Ag seeds into nanocrystals with different shapes. Starting with single-crystal seeds (spherical or cubic in shape), we could selectively obtain Ag octahedrons enclosed by {l_brace}111{r_brace} facets and nanocubes/nanobars enclosed by {l_brace}100{r_brace} facets by adding sodium citrate (Na{sub 3}CA) and poly(vinyl pyrrolidone) (PVP), respectively, as a capping agent while all other parameters were kept the same. This research not only offers new insights into the role played by a capping agent in shape-controlled synthesis but also provides, for the first time, Ag octahedrons as small as 40 nm in edge length for optical and spectroscopic studies.

  13. Controlling the shapes of silver nanocrystals with different capping agents.

    Science.gov (United States)

    Zeng, Jie; Zheng, Yiqun; Rycenga, Matthew; Tao, Jing; Li, Zhi-Yuan; Zhang, Qiang; Zhu, Yimei; Xia, Younan

    2010-06-30

    This paper provides direct evidence to support the role of a capping agent in controlling the evolution of Ag seeds into nanocrystals with different shapes. Starting with single-crystal seeds (spherical or cubic in shape), we could selectively obtain Ag octahedrons enclosed by {111} facets and nanocubes/nanobars enclosed by {100} facets by adding sodium citrate (Na(3)CA) and poly(vinyl pyrrolidone) (PVP), respectively, as a capping agent while all other parameters were kept the same. This research not only offers new insights into the role played by a capping agent in shape-controlled synthesis but also provides, for the first time, Ag octahedrons as small as 40 nm in edge length for optical and spectroscopic studies.

  14. Energy confinement and MHD activity in shaped TCV plasmas with localised electron cyclotron heating

    International Nuclear Information System (INIS)

    Pochelon, A.; Alberti, S.; Angioni, C.

    2001-01-01

    Confinement in TCV (Tokamak a Configuration Variable) EC heated discharges is studied as a function of plasma shape, i.e. as a function of elongation 1.1<κ<2.15 and triangularity -0.65≤δ≤0.5. The electron energy confinement time is found to increase with elongation, in part due to the increase of plasma current with elongation. The beneficial effect of negative triangularities is most effective at low power and tends to reduce at the higher powers used. The large variety of sawtooth types observed in TCV for different power deposition locations from on axis to the q=1 region can be simulated with a model including a local power deposition, a growing m/n=1 island (convection and reconnection), plasma rotation and finite heat diffusivity across flux surfaces. (author)

  15. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    Science.gov (United States)

    Carr,; Jeffrey, W [Livermore, CA

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  16. Self-focusing and self-defocusing of elliptically shaped Gaussian laser beams in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Nayyar, V P; Soni, V S [Punjabi Univ., Patiala (India). Dept. of Physics

    1979-02-14

    This paper presents a study of the self-focusing and self-defocusing of elliptically shaped Gaussian laser beams in collisional and collisionless plasmas. The non-linear dependence of the dielectric constant inside a collisional plasma is due to inhomogeneous heating of energy carriers and in a collisionless plasma it is due to the ponderomotive force. It is found that the beam gets focused at different points in different planes, exhibiting the effect of astigmatism. In certain power regions considered, the beam either converges or defocuses in both the directions, while in some other regions of the power spectrum one dimension of the beam focuses while the other defocuses. The beam also propagates in an oscillatory waveguide.

  17. POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator.

    Science.gov (United States)

    Wang, Bin; Li, Huaxing

    2016-01-01

    This study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD). 2D particle image velocimetry measurements were conducted on region (x/h = 0-2.25) and reattachment zone in the x-y plane over the backward-facing step at a Reynolds number of Re h  = 27,766 (based on step height [Formula: see text] and free stream velocity [Formula: see text]. The separated shear layer was excited by specially designed right-angle-shaped plasma actuator under the normalized excitation frequency St h  ≈ 0.345 along the 45° direction. The spatial distribution of each Reynolds stress component was reconstructed using an increasing number of POD modes. The POD analysis indicated that the flow dynamic downstream of the step was dominated by large-scale flow structures, which contributed to streamwise Reynolds stress and Reynolds shear stress. The intense Reynolds stress localized to a narrow strip within the shear layer was mainly affected by small-scale flow structures, which were responsible for the recovery of the Reynolds stress peak. With plasma excitation, a significant increase was obtained in the vertical Reynolds stress peak. Under the dimensionless frequencies St h  ≈ 0.345 and [Formula: see text] which are based on the step height and momentum thickness, the effectiveness of the flow control forced by the plasma actuator along the 45° direction was ordinary. Only the vertical Reynolds stress was significantly affected.

  18. NR4.00002: Response of a laminar M-shaped premixed flame to plasma forcing

    KAUST Repository

    Lacoste, Deanna A.

    2015-07-27

    We report on the response of a lean methane-air flame to non-thermal plasma forcing. The set-up consists of an axisymmetric burner, with a nozzle made of a quartz tube of 7-mm inlet diameter. The equivalence ratio is 0.9 and the flame is stabilized in an M-shape morphology over a central stainless steel rod and the quartz tube. The plasma is produced by nanosecond pulses of 10 kV maximum voltage amplitude, applied at 10 kHz. The central rod is used as a cathode, while the anode is a stainless steel ring, fixed on the outer surface of the quartz tube. The plasma forcing is produced by bursts of plasma pulses of 1 s duration. The response of the flame is investigated through the heat release rate (HRR) fluctuations. The chemiluminescence of CH* between two consecutive pulses was recorded using an intensified camera with an optical filter to estimate the HRR fluctuations. The results show that, even though the plasma is located in the combustion area, the flame is not responding to each single plasma pulse, but is affected by the discharge burst. The plasma forcing can then be considered as a step of forcing: the beginning of a positive step corresponding to the first plasma pulse, and the beginning of a negative step corresponding to the end of the last pulse of the burst. The effects of both positive and negative steps were investigated. The response of the flame is then analyzed and viable mechanisms are discussed.

  19. Shape control synthesis of low-dimensional calcium sulfate

    Indian Academy of Sciences (India)

    Shape control synthesis of low-dimensional calcium sulfate .... C in mixed solvents of 50 mL ethanol and 30 mL water for different reaction times was characterized by .... Duan X, Huang Y, Cui Y, Wang J and Lieber C M 2001 Nature 409 66.

  20. Shape modification of bridge cables for aerodynamic vibration control

    DEFF Research Database (Denmark)

    Kleissl, Kenneth; Georgakis, Christos

    2010-01-01

    In this paper, the viability of modifying cable shape and surface for the purpose of controlling wind-induced vibrations is examined. To this end, an extensive wind-tunnel test campaign was carried out on various cable sections in the critical Reynolds number region under both smooth and turbulen...

  1. Changing pulse-shape basis for molecular learning control

    International Nuclear Information System (INIS)

    Cardoza, David; Langhojer, Florian; Trallero-Herrero, Carlos; Weinacht, Thomas; Monti, Oliver L.A.

    2004-01-01

    We interpret the results of a molecular fragmentation learning control experiment. We show that in the case of a system where control can be related to the structure of the optimal pulse matching the vibrational dynamics of the molecule, a simple change of pulse-shape basis in which the learning algorithm performs the search can reduce the dimensionality of the search space to one or two degrees of freedom

  2. Integral LQR Control of a Star-Shaped Octorotor

    Directory of Open Access Journals (Sweden)

    Adrian M. STOICA

    2012-06-01

    Full Text Available The paper starts by presenting the model of the star-shaped octorotor. LQR control is chosen to stabilize the attitude and altitude of the vehicle. Waypoint navigation is also implemented. Numerical simulations demonstrate the effectiveness of the control strategy under nominal conditions. However, in practice mass related uncertainties can occur. In this case the results are unsatisfactory. Thus the improvement of the applied LQR control strategy is proposed. It is shown that after adding integral action to the altitude controller the issue is solved.

  3. Chloride (Cl−) ion-mediated shape control of palladium nanoparticles

    International Nuclear Information System (INIS)

    Nalajala, Naresh; Chakraborty, Arup; Bera, Bapi; Neergat, Manoj

    2016-01-01

    The shape control of Pd nanoparticles is investigated using chloride (Cl − ) ions as capping agents in an aqueous medium in the temperature range of 60–100 °C. With weakly adsorbing and strongly etching Cl − ions, oxygen plays a crucial role in shape control. The experimental factors considered are the concentration of the capping agents, reaction time and reaction atmosphere. Thus, Pd nanoparticles of various shapes with high selectivity can be synthesized. Moreover, the removal of Cl − ions from the nanoparticle surface is easier than that of Br − ions (moderately adsorbing and etching) and I − ions (strongly adsorbing and weakly etching). The cleaned Cl − ion-mediated shape-controlled Pd nanoparticles are electrochemically characterized and the order of the half-wave potential of the oxygen reduction reaction in oxygen-saturated 0.1 M HClO 4 solution is of the same order as that observed with single-crystal Pd surfaces. (paper)

  4. Effect of ablation geometry on the dynamics, composition, and geometrical shape of thin film plasma

    Science.gov (United States)

    Mondal, Alamgir; Singh, R. K.; Kumar, Ajai

    2018-01-01

    The characteristics of plasma plume produced by front and back ablation of thin films have been investigated using fast imaging and optical emission spectroscopy. Ablation geometry dependence of the plume dynamics, its geometrical aspect and composition is emphasized. Also, the effect of an ambient environment and the beam diameter of an ablating laser on the front and back ablations is briefly discussed. Analysis of time resolved images and plasma parameters indicates that the energetic and spherical plasma formed by front ablation is strikingly different in comparison to the slow and nearly cylindrical plasma plume observed in the case of back ablation. Further shock formation, plume confinement, thermalization and validity of different expansion models in these two ablation geometries are also presented. The present study demonstrates the manipulation of kinetic energy, shape, ion/neutral compositions and directionality of the expanding plume by adjusting the experimental configuration, which is highly relevant to its utilization in various applications e.g., generation of energetic particles, tokamak edge plasma diagnostics, thin film deposition, etc.

  5. Plasma density control in real-time on the COMPASS tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Janky, F., E-mail: filip.janky.work@gmail.com [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Praha 8 (Czech Republic); Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, 180 00 Praha 8 (Czech Republic); Hron, M. [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Praha 8 (Czech Republic); Havlicek, J. [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Praha 8 (Czech Republic); Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, 180 00 Praha 8 (Czech Republic); Varavin, M.; Zacek, F.; Seidl, J.; Panek, R. [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Praha 8 (Czech Republic)

    2015-10-15

    Highlights: • We fitted length of the chord of the interferometry crossing plasma in the different plasma scenarios. • We add correction to the actual length of the chord of the interferometry according to plasma shape and position in real-time code. • We used this correction to control plasma density in real-time. - Abstract: The electron density on COMPASS is measured using 2 mm microwave interferometer. Interferometer signal is used as an input for the feedback control loop, running under the MARTe real-time framework. Two different threads are used to calculate (fast 50 μs thread) and to control (slow 500 μs thread) the electron density. The interferometer measures a line averaged density along a measurement chord. This paper describes an approach to control the line-averaged electron density in a real-time loop, using a correction to the real plasma shape, the plasma position, and non-linear effects of the electron density measurement at high densities. Newly developed real-time electron density control give COMPASS the chance to control the electron density more accurately which is essential for parametric scans for diagnosticians, for physics experiments and also for achieving plasma scenarios with H-mode.

  6. Relationship Between Strategy Shaping and Management Control Systems

    Directory of Open Access Journals (Sweden)

    Marcia Athayde Moreira

    2017-04-01

    Full Text Available This research analyzed the interactions between strategy shaping and management control systems, having as parameter of analysis the system of levers of control recommended by Simons (1995. A multiple case study was carried out of two companies in the construction sector in Brazil. It was found that these companies use generic niche strategies to sell the properties they have built. One of these companies uses long-term planning while the other is guided by short-term perspectives and perceptions. Both companies employ various formal control tools. It was noted, however, that some of these tools exist for the purpose of meeting the requirements of standards and audits established by certifying bodies and are not being used as tools for decision making. It was thus concluded that the relationship between managerial controls and the shaping of strategy in these organizations occurs in a passive way, with the management control systems serving as guarantors of the accomplishment of organizational strategies and goals, but not being used effectively to identify opportunities or as a source for shaping new strategies.

  7. The genetic network controlling plasma cell differentiation.

    Science.gov (United States)

    Nutt, Stephen L; Taubenheim, Nadine; Hasbold, Jhagvaral; Corcoran, Lynn M; Hodgkin, Philip D

    2011-10-01

    Upon activation by antigen, mature B cells undergo immunoglobulin class switch recombination and differentiate into antibody-secreting plasma cells, the endpoint of the B cell developmental lineage. Careful quantitation of these processes, which are stochastic, independent and strongly linked to the division history of the cell, has revealed that populations of B cells behave in a highly predictable manner. Considerable progress has also been made in the last few years in understanding the gene regulatory network that controls the B cell to plasma cell transition. The mutually exclusive transcriptomes of B cells and plasma cells are maintained by the antagonistic influences of two groups of transcription factors, those that maintain the B cell program, including Pax5, Bach2 and Bcl6, and those that promote and facilitate plasma cell differentiation, notably Irf4, Blimp1 and Xbp1. In this review, we discuss progress in the definition of both the transcriptional and cellular events occurring during late B cell differentiation, as integrating these two approaches is crucial to defining a regulatory network that faithfully reflects the stochastic features and complexity of the humoral immune response. 2011 Elsevier Ltd. All rights reserved.

  8. MATURING ECRF TECHNOLOGY FOR PLASMA CONTROL

    International Nuclear Information System (INIS)

    CALLIS, R.W.; CARY, W.P.; CHU, S.; LOANE, J.L.; ELLIS, R.A.; FELCH, K.; GORELOV, Y.A.; GRUNLOH, H.J.; HOSEA, J.; KAJIWARA, K.; LOHR, J.; LUCE, T.C.; PEAVY, J.J.; PINSKER, R.I.; PONCE, D.; PRATER, R.; SHAPIRO, M.; TEMKIN, R.J.; TOOKER, J.F.

    2002-01-01

    OAK A271 MUTURING ECRF TECHNOLOGY FOR PLASMA CONTROL. Understanding of the physics of internal transport barriers (ITBs) is being furthered by analysis and comparisons of experimental data from many different tokamaks worldwide. An international database consisting of scalar and 2-D profile data for ITB plasmas is being developed to determine the requirements for the formation and sustainment of ITBs and to perform tests of theory-based transport models in an effort to improve the predictive capability of the models. Analysis using the database indicates that: (a) the power required to form ITBs decreases with increased negative magnetic shear of the target plasma, and: (b) the E x B flow shear rate is close to the linear growth rate of the ITG modes at the time of barrier formation when compared for several fusion devices. Tests of several transport models (JETTO, Weiland model) using the 2-D profile data indicate that there is only limited agreement between the model predictions and the experimental results for the range of plasma conditions examined for the different devices (DIII-D, JET, JT-60U). Gyrokinetic stability analysis (using the GKS code) of the ITB discharges from these devices indicates that the ITG/TEM growth rates decrease with increased negative magnetic shear and that the E x B shear rate is comparable to the linear growth rates at the location of the ITB

  9. Effect of variation in equilibrium shape on ELMing H-mode performance in DIII-D diverted plasmas

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Osborne, T.H.; Petrie, T.W.

    2001-01-01

    The changes in the performance of the core, pedestal, scrape-off-layer (SOL), and divertor plasmas as a result of changes in triangularity, δ, up/down magnetic balance, and secondary divertor volume were examined in shape variation experiments using ELMing H mode plasmas on DIII-D. In moderate density, unpumped plasmas, high δ∼0.7 increased the energy in the H mode pedestal and the global energy confinement of the core, primarily due to an increase in the margin by which the edge pressure gradient exceeded the value which would have been expected had it been limited by infinite-n ideal ballooning modes. In addition, a nearly balanced double-null (DN) shape was effective for sharing the peak heat flux in the divertor in these attached plasmas. For detached plasmas good heat flux sharing was obtained for a substantial range of unbalanced DN shapes. Finally, the presence of a second X-point in unbalanced DN shapes did not degrade the plasma performance if it was sufficiently far inside the vacuum vessel. These results indicate that a high δ unbalanced DN shape has some advantages over a single null shape for future high power tokamak operation. (author)

  10. Physics of plasma-wall interactions in controlled fusion

    International Nuclear Information System (INIS)

    Post, D.E.; Behrisch, R.

    1984-01-01

    In the areas of plasma physics, atomic physics, surface physics, bulk material properties and fusion experiments and theory, the following topics are presented: the plasma sheath; plasma flow in the sheath and presheath of a scrape-off layer; probes for plasma edge diagnostics in magnetic confinement fusion devices; atomic and molecular collisions in the plasma boundary; physical sputtering of solids at ion bombardment; chemical sputtering and radiation enhanced sublimation of carbon; ion backscattering from solid surfaces; implantation, retention and release of hydrogen isotopes; surface erosion by electrical arcs; electron emission from solid surfaces;l properties of materials; plasma transport near material boundaries; plasma models for impurity control experiments; neutral particle transport; particle confinement and control in existing tokamaks; limiters and divertor plates; advanced limiters; divertor tokamak experiments; plasma wall interactions in heated plasmas; plasma-wall interactions in tandem mirror machines; and impurity control systems for reactor experiments

  11. An input shaping controller enabling cranes to move without sway

    International Nuclear Information System (INIS)

    Singer, N.; Singhose, W.; Kriikku, E.

    1997-01-01

    A gantry crane at the Savannah River Technology Center was retrofitted with an Input Shaping controller. The controller intercepts the operator's pendant commands and modifies them in real time so that the crane is moved without residual sway in the suspended load. Mechanical components on the crane were modified to make the crane suitable for the anti-sway algorithm. This paper will describe the required mechanical modifications to the crane, as well as, a new form of Input Shaping that was developed for use on the crane. Experimental results are presented which demonstrate the effectiveness of the new process. Several practical considerations will be discussed including a novel (patent pending) approach for making small, accurate moves without residual oscillations

  12. Recent Developments in Shape-Controlled Synthesis of Silver Nanocrystals.

    Science.gov (United States)

    Xia, Xiaohu; Zeng, Jie; Zhang, Qiang; Moran, Christine H; Xia, Younan

    2012-01-01

    This feature article introduces our recent work on understanding the roles played by citrate and poly(vinyl pyrrolidone) (PVP) as capping agents in seed-mediated syntheses of Ag nanocrystals with controlled shapes. We have demonstrated that citrate and PVP selectively bind to Ag(111) and Ag(100) surfaces, respectively, and thus favor the formation of Ag nanocrystals enclosed preferentially by {111} or {100} facets. In addition, we have quantified the coverage density of PVP adsorbed on the surface of Ag nanocubes. Based on the mechanistic understanding, a series of Ag nanocrystals with controlled shapes and sizes have been successfully synthesized by using different combinations of seeds and capping agents: single-crystal spherical/cubic seeds with citrate for cuboctahedrons and octahedrons or with PVP for cubes and bars; and plate-like seeds with citrate for enlarged thin plates or with PVP for thickened plates.

  13. X-ray spectral line shapes for the excimer-laser-produced high density plasma diagnostics

    International Nuclear Information System (INIS)

    Magunov, A.; Faenov, A.; Skobelev, I.; Pikuz, T.; Batani, D.; Milani, M.; Conti, A.; Masini, A.; Costato, M.; Pozzi, A.; Turcu, E.; Allot, R.; Lisi, N.; Koenig, M.; Benuzzi, A.; Flora, F.; Letardi, T.; Palladino, L.; Reale, A.

    1997-01-01

    The time and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (I L =(4-10)·10 12 W/cm 2 , τ=10 ns) and by 248 nm wavelength KrF laser pulse train radiation (I L =5·10 15 W/cm 2 , τ=7 ps, 16 pulses in train) on CF n plane target. The lines' shapes and intensities modeling of Lyman series and He-like ion resonance series of fluorine up to n=7 by fitting experimental data shows the considerable difference of plasma formation features for these two sets of the laser pulse parameters

  14. Feedback control modeling of plasma position and current during intense heating in ISX-B

    International Nuclear Information System (INIS)

    Charlton, L.A.; Swain, D.W.; Neilson, G.H.

    1979-08-01

    The ISX-B Tokamak at ORNL is designed to have 1.8 MW (and eventually 3 MW) of neutral beam power injected to heat the plasma. This power may raise the anti β of the plasma to over 5% in less than 50 msec if the plasma is MHD stable. The results of a numerical simulation of the feedback control system and poloidal coil power supplies necessary to control the resulting noncircular (D-shaped or elliptical) plasma are presented. The resulting feedback control system is shown to be straightforward, although nonlinear voltage-current dependence is assumed in the power supplies. The required power supplied to the poloidal coils in order to contain the plasma under the high heating rates is estimated

  15. Ignition and burn control in tokamak plasmas

    International Nuclear Information System (INIS)

    Borrass, K.; Gruber, O.; Lackner, K.; Minardi, E.; Neuhauser, J.; Wilhelm, R.; Wunderlich, R.; Bromberg, L.; Cohn, D.R.

    1981-01-01

    Different schemes for the control of the thermal instability in an ignited fusion reactor are analysed by zero- and one-dimensional models. Passive stabilization methods considered are ripple-enhanced ion heat conduction, the effect of the major-radius variation of the plasma column in a time-independent vertical field, and the combination of both effects, including the spatial variation of the toroidal-ripple amplitude. Active control methods analysed are high-Q-driven operation and feedback-controlled major-radius variation following different scenarios. One-dimensional analyses taking into account only conductive losses show the existence of a single unstable mode in the energy balance, justifying, under these assumptions, the study of only global control. (author)

  16. Architecture of WEST plasma control system

    International Nuclear Information System (INIS)

    Ravenel, N.; Nouailletas, R.; Barana, O.; Brémond, S.; Moreau, P.; Guillerminet, B.; Balme, S.; Allegretti, L.; Mannori, S.

    2014-01-01

    To operate advanced plasma scenario (long pulse with high stored energy) in present and future tokamak devices under safe operation conditions, the control requirements of the plasma control system (PCS) leads to the development of advanced feedback control and real time handling exceptions. To develop these controllers and these exceptions handling strategies, a project aiming at setting up a flight simulator has started at CEA in 2009. Now, the new WEST (W Environment in Steady-state Tokamak) project deals with modifying Tore Supra into an ITER-like divertor tokamak. This upgrade impacts a lot of systems including Tore Supra PCS and is the opportunity to improve the current PCS architecture to implement the previous works and to fulfill the needs of modern tokamak operation. This paper is dealing with the description of the architecture of WEST PCS. Firstly, the requirements will be presented including the needs of new concepts (segments configuration, alternative (or backup) scenario, …). Then, the conceptual design of the PCS will be described including the main components and their functions. The third part will be dedicated to the proposal RT framework and to the technologies that we have to implement to reach the requirements

  17. Plasma actuators for bluff body flow control

    Science.gov (United States)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

  18. An advanced plasma control system for Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Wijnands, T.; Martin, G.

    1996-01-01

    First results on plasma control with the new plasma control system of Tore Supra are presented. The system has been especially designed for long pulse operation: plasmas are controlled on reference signals, which can be varied in real time by using diagnostic measurements. On line determination of the global plasma equilibrium has enabled new operation scenarios in which both the power from the poloidal field generators and the total Lower Hybrid (LH) power are used to control the plasma. Experiments with feedback control of the safety factor on the plasma boundary, control of the LH driven current, control of the flux on the plasma boundary and control of the internal inductance are discussed. (author). 12 refs.

  19. An advanced plasma control system for Tore Supra

    International Nuclear Information System (INIS)

    Wijnands, T.; Martin, G.

    1996-01-01

    First results on plasma control with the new plasma control system of Tore Supra are presented. The system has been especially designed for long pulse operation: plasmas are controlled on reference signals, which can be varied in real time by using diagnostic measurements. On line determination of the global plasma equilibrium has enabled new operation scenarios in which both the power from the poloidal field generators and the total Lower Hybrid (LH) power are used to control the plasma. Experiments with feedback control of the safety factor on the plasma boundary, control of the LH driven current, control of the flux on the plasma boundary and control of the internal inductance are discussed. (author)

  20. Numerical simulation and optimal control in plasma physics

    International Nuclear Information System (INIS)

    Blum, J.

    1989-01-01

    The topics covered in this book are: A free boundary problem: the axisymmetric equilibrium of the plasma in a Tokamak; Static control of the plasma boundary by external currents; Existence and control of a solution to the equilibrium problem in a simple case; Study of equilibrium solution branches and application to the stability of horizontal displacements; Identification of the plasma boundary and plasma current density from magnetic measurements; Evolution of the equilibrium at the diffusion time scale; Evolution of the equilibrium of a high aspect-ratio circular plasma; Stability and control of the horizontal displacement of the plasma

  1. The ITER Plasma Control System Simulation Platform

    International Nuclear Information System (INIS)

    Walker, M.L.; Ambrosino, G.; De Tommasi, G.; Humphreys, D.A.; Mattei, M.; Neu, G.; Rapson, C.J.; Raupp, G.; Treutterer, W.; Welander, A.S.; Winter, A.

    2015-01-01

    Highlights: • A development and test environment called PCSSP has been constructed for the ITER PCS. • A description of requirements and use cases, a final design and software architecture design, users guide, and a prototype implementation have been delivered. • The prototype implementation was demonstrated at IO in December of 2013. • PCSSP will be deployed for alpha testing to the IO, the development group, and selected other ITER partners upon completion of the next development phase. - Abstract: The Plasma Control System Simulation Platform (PCSSP) is a highly flexible, modular, time-dependent simulation environment developed primarily to support development of the ITER Plasma Control System (PCS). It has been under development since 2011 and is scheduled for first release to users in the ITER Organization (IO) and at selected additional sites in 2015. Modules presently implemented in PCSSP enable exploration of axisymmetric evolution and control, basic kinetic control, and tearing mode suppression. A basic capability for generation of control-relevant events is included, enabling study of exception handling in the PCS, continuous controllers, and PCS architecture. While the control design focus of PCSSP applications tends to require only a moderate level of accuracy and complexity in modules, more complex codes can be embedded or connected to access higher accuracy if needed. This paper describes the background and motivation for PCSSP, provides an overview of the capabilities, architecture, and features of PCSSP, and discusses details of the PCSSP vision and its intended goals and application. Completed work, including architectural design, prototype implementation, reference documents, and IO demonstration of PCSSP, is summarized and example use of PCSSP is illustrated. Near-term high-level objectives are summarized and include preparation for release of an “alpha” version of PCSSP and preparation for the next development phase. High

  2. The ITER Plasma Control System Simulation Platform

    Energy Technology Data Exchange (ETDEWEB)

    Walker, M.L., E-mail: walker@fusion.gat.com [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Ambrosino, G.; De Tommasi, G. [CREATE/Università di Napoli Federico II, Napoli (Italy); Humphreys, D.A. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Mattei, M. [CREATE/Seconda Università di Napoli, Napoli (Italy); Neu, G.; Rapson, C.J.; Raupp, G.; Treutterer, W. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Welander, A.S. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Winter, A. [ITER Organization, Route de Vinon-sur-Verdon, 13115 St. Paul-lez-Durance (France)

    2015-10-15

    Highlights: • A development and test environment called PCSSP has been constructed for the ITER PCS. • A description of requirements and use cases, a final design and software architecture design, users guide, and a prototype implementation have been delivered. • The prototype implementation was demonstrated at IO in December of 2013. • PCSSP will be deployed for alpha testing to the IO, the development group, and selected other ITER partners upon completion of the next development phase. - Abstract: The Plasma Control System Simulation Platform (PCSSP) is a highly flexible, modular, time-dependent simulation environment developed primarily to support development of the ITER Plasma Control System (PCS). It has been under development since 2011 and is scheduled for first release to users in the ITER Organization (IO) and at selected additional sites in 2015. Modules presently implemented in PCSSP enable exploration of axisymmetric evolution and control, basic kinetic control, and tearing mode suppression. A basic capability for generation of control-relevant events is included, enabling study of exception handling in the PCS, continuous controllers, and PCS architecture. While the control design focus of PCSSP applications tends to require only a moderate level of accuracy and complexity in modules, more complex codes can be embedded or connected to access higher accuracy if needed. This paper describes the background and motivation for PCSSP, provides an overview of the capabilities, architecture, and features of PCSSP, and discusses details of the PCSSP vision and its intended goals and application. Completed work, including architectural design, prototype implementation, reference documents, and IO demonstration of PCSSP, is summarized and example use of PCSSP is illustrated. Near-term high-level objectives are summarized and include preparation for release of an “alpha” version of PCSSP and preparation for the next development phase. High

  3. Fabrication of shape controlled Fe3O4 nanostructure

    International Nuclear Information System (INIS)

    Zheng, Y.Y.; Wang, X.B.; Shang, L.; Li, C.R.; Cui, C.; Dong, W.J.; Tang, W.H.; Chen, B.Y.

    2010-01-01

    Shape-controlled Fe 3 O 4 nanostructure has been successfully prepared using polyethylene glycol as template in a water system at room temperature. Different morphologies of Fe 3 O 4 nanostructures, including spherical, cubic, rod-like, and dendritic nanostructure, were obtained by carefully controlling the concentration of the Fe 3+ , Fe 2+ , and the molecular weight of the polyethylene glycol. Transmission Electron Microscope images, X-ray powder diffraction patterns and magnetic properties were used to characterize the final product. This easy procedure for Fe 3 O 4 nanostructure fabrication offers the possibility of a generalized approach to the production of single and complex nanocrystalline oxide with tunable morphology.

  4. Plasma physics for controlled fusion. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Kenro

    2016-08-01

    This new edition presents the essential theoretical and analytical methods needed to understand the recent fusion research of tokamak and alternate approaches. The author describes magnetohydrodynamic and kinetic theories of cold and hot plasmas in detail. The book covers new important topics for fusion studies such as plasma transport by drift turbulence, which depend on the magnetic configuration and zonal flows. These are universal phenomena of microturbulence. They can modify the onset criterion for turbulent transport, instabilities driven by energetic particles as well as alpha particle generation and typical plasma models for computer simulation. The fusion research of tokamaks with various new versions of H modes are explained. The design concept of ITER, the international tokamak experimental reactor, is described for inductively driven operations as well as steady-state operations using non-inductive drives. Alternative approaches of reversed-field pinch and its relaxation process, stellator including quasi-symmetric system, open-end system of tandem mirror and inertial confinement are also explained. Newly added and updated topics in this second edition include zonal flows, various versions of H modes, and steady-state operations of tokamak, the design concept of ITER, the relaxation process of RFP, quasi-symmetric stellator, and tandem mirror. The book addresses graduate students and researchers in the field of controlled fusion.

  5. Plasma physics for controlled fusion. 2. ed.

    International Nuclear Information System (INIS)

    Miyamoto, Kenro

    2016-01-01

    This new edition presents the essential theoretical and analytical methods needed to understand the recent fusion research of tokamak and alternate approaches. The author describes magnetohydrodynamic and kinetic theories of cold and hot plasmas in detail. The book covers new important topics for fusion studies such as plasma transport by drift turbulence, which depend on the magnetic configuration and zonal flows. These are universal phenomena of microturbulence. They can modify the onset criterion for turbulent transport, instabilities driven by energetic particles as well as alpha particle generation and typical plasma models for computer simulation. The fusion research of tokamaks with various new versions of H modes are explained. The design concept of ITER, the international tokamak experimental reactor, is described for inductively driven operations as well as steady-state operations using non-inductive drives. Alternative approaches of reversed-field pinch and its relaxation process, stellator including quasi-symmetric system, open-end system of tandem mirror and inertial confinement are also explained. Newly added and updated topics in this second edition include zonal flows, various versions of H modes, and steady-state operations of tokamak, the design concept of ITER, the relaxation process of RFP, quasi-symmetric stellator, and tandem mirror. The book addresses graduate students and researchers in the field of controlled fusion.

  6. Blood–plasma separation in Y-shaped bifurcating microfluidic channels: a dissipative particle dynamics simulation study

    International Nuclear Information System (INIS)

    Li, Xuejin; Karniadakis, George Em; Popel, Aleksander S

    2012-01-01

    The motion of a suspension of red blood cells (RBCs) flowing in a Y-shaped bifurcating microfluidic channel is investigated using a validated low-dimensional RBC model based on dissipative particle dynamics. Specifically, the RBC is represented as a closed torus-like ring of ten colloidal particles, which leads to efficient simulations of blood flow in microcirculation over a wide range of hematocrits. Adaptive no-slip wall boundary conditions were implemented to model hydrodynamic flow within a specific wall structure of diverging three-dimensional microfluidic channels, paying attention to controlling density fluctuations. Plasma skimming and the all-or-nothing phenomenon of RBCs in a bifurcating microfluidic channel have been investigated in our simulations for healthy and diseased blood, including the size of a cell-free layer on the daughter branches. The feed hematocrit level in the parent channel has considerable influence on blood–plasma separation. Compared to the blood–plasma separation efficiencies of healthy RBCs, malaria-infected stiff RBCs (iRBCs) have a tendency to travel into the low flow-rate daughter branch because of their different initial distribution in the parent channel. Our simulation results are consistent with previously published experimental results and theoretical predictions. (paper)

  7. Size and shape control in the overgrowth of gold nanorods

    International Nuclear Information System (INIS)

    Ratto, Fulvio; Matteini, Paolo; Rossi, Francesca; Pini, Roberto

    2010-01-01

    We report on a new sustainable approach to manipulate the optical behaviour and geometrical properties of gold nanorods in aqueous solutions by fine control of their overgrowth. In our approach, the overgrowth is realized by modulation of the reduction of the gold ions which are left as Au 1+ after the primary step of the synthesis (typically as much as ∼80% of the gold ions available in the growth solution). The progress of the reduction requires the gradual addition of ascorbic acid, which transforms the Au 1+ into Au 0 and may be performed in the original growth solution with no need for any further manipulation. By control of the total amount and rate of administration of the ascorbic acid, we prove the possibility to realize a systematic modulation of the average lengths, diameters, shapes (rod or dog-bone like), and light extinction of the nanoparticles. A slow overgrowth leads to a gradual enlargement of the lengths and diameters at almost constant shape. In contrast, a faster overgrowth results into a more complex modification of the overall shape of the gold nanorods.

  8. Effect of plasma shape on confinement and MHD behaviour in TCV

    Czech Academy of Sciences Publication Activity Database

    Weisen, H.; Alberti, S.; Berry, S.; Behn, R.; Bosshard, P.; Bühlmann, F.; Chavan, R.; Coda, S.; Deschenaux, C.; Dutch, M. J.; Duval, B. P.; Fasel, D.; Favre, A.; Franke, S.; Furno, I.; Goodman, T.; Henderson, M.; Hofmann, F.; Hogge, J. Ph.; Isoz, P. F.; Joye, B.; Lister, J. B.; Llobet, X.; Magnin, J. C.; Mandrin, P.; Marmillod, P.; Martin, Y.; Mayor, J. M.; Moret, J. M.; Nieswand, Ch.; Paris, P.; Perez, A.; Pietrzyk, Z. A.; Piffl, Vojtěch; Pitts, R. A.; Pochelon, A.; Razumova, K.; Reimerdes, H.; Refke, A.; Rommers, J.; Roy, I.; Sauter, O.; Suttrop, W.; Toledo van, W.; Tonetti, G.; Tran, M. Q.; Troyon, F.; Vyas, P.; Ward, D. J.

    1997-01-01

    Roč. 39, 12B,Special issue (1997), s. 135-144 ISSN 0741-3335. [European Physical Society Conference on Controlled Fusion and Plasma Physics /24./. Berchtesgaden, 09.06.1997-13.06.1997] R&D Projects: GA AV ČR KSK1043601 Impact factor: 2.232, year: 1997

  9. Determination of edge plasma parameters by a genetic algorithm analysis of spectral line shapes

    International Nuclear Information System (INIS)

    Marandet, Y.; Genesio, P.; Godbert-Mouret, L.; Koubiti, M.; Stamm, R.; Capes, H.; Guirlet, R.

    2003-01-01

    Comparing an experimental and a theoretical line shape can be achieved by a genetic algorithm (GA) based on an analogy to the mechanisms of natural selection. Such an algorithm is able to deal with complex non-linear models, and can avoid local minima. We have used this optimization tool in the context of edge plasma spectroscopy, for a determination of the temperatures and fractions of the various populations of neutral deuterium emitting the D α line in 2 configurations of Tore-Supra: ergodic divertor and toroidal pumped limiter. Using the GA fit, the neutral emitters are separated into up to 4 populations which can be identified as resulting from molecular dissociation reactions, charge exchange, or reflection. In all the edge plasmas studied, a significant fraction of neutrals emit in the line wings, leading to neutrals with a temperature up to a few hundreds eV if a Gaussian line shape is assumed. This conclusion could be modified if the line wing exhibits a non Gaussian behavior

  10. Determination of edge plasma parameters by a genetic algorithm analysis of spectral line shapes

    Energy Technology Data Exchange (ETDEWEB)

    Marandet, Y.; Genesio, P.; Godbert-Mouret, L.; Koubiti, M.; Stamm, R. [Universite de Provence (PIIM), Centre de Saint-Jerome, 13 - Marseille (France); Capes, H.; Guirlet, R. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    2003-07-01

    Comparing an experimental and a theoretical line shape can be achieved by a genetic algorithm (GA) based on an analogy to the mechanisms of natural selection. Such an algorithm is able to deal with complex non-linear models, and can avoid local minima. We have used this optimization tool in the context of edge plasma spectroscopy, for a determination of the temperatures and fractions of the various populations of neutral deuterium emitting the D{sub {alpha}} line in 2 configurations of Tore-Supra: ergodic divertor and toroidal pumped limiter. Using the GA fit, the neutral emitters are separated into up to 4 populations which can be identified as resulting from molecular dissociation reactions, charge exchange, or reflection. In all the edge plasmas studied, a significant fraction of neutrals emit in the line wings, leading to neutrals with a temperature up to a few hundreds eV if a Gaussian line shape is assumed. This conclusion could be modified if the line wing exhibits a non Gaussian behavior.

  11. Remote interferometry by digital holography for shape control

    Science.gov (United States)

    Baumbach, Torsten; Osten, Wolfgang; Falldorf, Claas; Jueptner, Werner P. O.

    2002-06-01

    Modern production requires more and more effective methods for the inspection and quality control at the production place. Outsourcing and globalization result in possible large distances between co-operating partners. This may cause serious problems with respect to the just-in-time exchange of information and the response to possible violations of quality standards. Consequently new challenges arise for optical measurement techniques especially in the field of industrial shape control. A possible solution for these problems can be delivered by a technique that stores optically the full 3D information of the objects to be compared and where the data can be transported over large distances. In this paper we describe the progress in implementing a new technique for the direct comparison of the shape and deformation of two objects with different microstructure where it is not necessary that both samples are located at the same place. This is done by creating a coherent mask for the illumination of the sample object. The coherent mask is created by Digital Holography to enable the instant access to the complete optical information of the master object at any wanted place. The transmission of the digital master holograms to this place can be done via digital telecommunication networks. The comparison can be done in a digital or analogue way. Both methods result in a disappearance of the object shape and the appearance of the shape or deformation difference between the two objects only. The analogue reconstruction of the holograms with a liquid crystal spatial light modulator can be done by using the light modulator as an intensity modulator or as an phase modulator. The reconstruction technique and the space bandwidth of the light modulator will influence the quality of the result. Therefore the paper describes the progress in applying modern spatial light modulators and digital cameras for the effective storage and optical reconstruction of coherent masks.

  12. Brazilian programme for plasma physics and controlled thermonuclear fusion

    International Nuclear Information System (INIS)

    Chian, A.C.L.; Reusch, M.F.; Nascimento, I.C.; Pantuso-Sudano, J.

    1992-01-01

    A proposal for a National Programme of Plasma Physics and Controlled Thermonuclear Fusion in Brazil is presented, aimimg the dissemination of the researchers thought in plasma physics for the national authorities and the scientific community. (E.O.)

  13. A control approach for plasma density in tokamak machines

    Energy Technology Data Exchange (ETDEWEB)

    Boncagni, Luca, E-mail: luca.boncagni@enea.it [EURATOM – ENEA Fusion Association, Frascati Research Center, Division of Fusion Physics, Rome, Frascati (Italy); Pucci, Daniele; Piesco, F.; Zarfati, Emanuele [Dipartimento di Ingegneria Informatica, Automatica e Gestionale ' ' Antonio Ruberti' ' , Sapienza Università di Roma (Italy); Mazzitelli, G. [EURATOM – ENEA Fusion Association, Frascati Research Center, Division of Fusion Physics, Rome, Frascati (Italy); Monaco, S. [Dipartimento di Ingegneria Informatica, Automatica e Gestionale ' ' Antonio Ruberti' ' , Sapienza Università di Roma (Italy)

    2013-10-15

    Highlights: •We show a control approach for line plasma density in tokamak. •We show a control approach for pressure in a tokamak chamber. •We show experimental results using one valve. -- Abstract: In tokamak machines, chamber pre-fill is crucial to attain plasma breakdown, while plasma density control is instrumental for several tasks such as machine protection and achievement of desired plasma performances. This paper sets the principles of a new control strategy for attaining both chamber pre-fill and plasma density regulation. Assuming that the actuation mean is a piezoelectric valve driven by a varying voltage, the proposed control laws ensure convergence to reference values of chamber pressure during pre-fill, and of plasma density during plasma discharge. Experimental results at FTU are presented to discuss weaknesses and strengths of the proposed control strategy. The whole system has been implemented by using the MARTe framework [1].

  14. On electrostatic acceleration of plasmas with the Hall effect using electrode shaping

    International Nuclear Information System (INIS)

    Wang, Zhehui; Barnes, Cris W.

    2001-01-01

    Resistive magnetohydrodynamics (MHD) is used to model the electromagnetic acceleration of plasmas in coaxial channels. When the Hall effect is considered, the inclusion of resistivity is necessary to obtain physically meaningful solutions. In resistive MHD with the Hall effect, if and only if the electric current and the plasma flow are orthogonal (J·U=0), then there is a conserved quantity, in the form of U 2 /2+w+eΦ/M, along the flow, where U is the flow velocity, Φ is the electric potential, w is the enthalpy, and M is the ion mass. New solutions suggest that in coaxial geometry the Hall effect along the axial plasma flow can be balanced by proper shaping of conducting electrodes, with acceleration then caused by an electrostatic potential drop along the streamlines of the flow. The Hall effect separation of ion and electron flow then just cancels the electrostatic charge separation. Assuming particle ionization increases with energy density in the system, the resulting particle flow rates (J p ) scales with accelerator bias (V bias ) as J p ∝V bias 2 , exceeding the Child--Langmuir limit. The magnitude of the Hall effect (as determined by the Morozov Hall parameter, Ξ, which is defined as the ratio of electric current to particle current) is related to the energy needed for the creation of each ion--electron pair

  15. Plasma immersion ion implantation of polyurethane shape memory polymer: Surface properties and protein immobilization

    Science.gov (United States)

    Cheng, Xinying; Kondyurin, Alexey; Bao, Shisan; Bilek, Marcela M. M.; Ye, Lin

    2017-09-01

    Polyurethane-type shape memory polymers (SMPU) are promising biomedical implant materials due to their ability to recover to a predetermined shape from a temporary shape induced by thermal activation close to human body temperature and their advantageous mechanical properties including large recovery strains and low recovery stresses. Plasma Immersion Ion Implantation (PIII) is a surface modification process using energetic ions that generates radicals in polymer surfaces leading to carbonisation and oxidation and the ability to covalently immobilise proteins without the need for wet chemistry. Here we show that PIII treatment of SMPU significantly enhances its bioactivity making SMPU suitable for applications in permanent implantable biomedical devices. Scanning Electron Microscopy (SEM), contact angle measurements, surface energy measurements, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterise the PIII modified surface, including its after treatment aging kinetics and its capability to covalently immobilise protein directly from solution. The results show a substantial improvement in wettability and dramatic changes of surface chemical composition dependent on treatment duration, due to the generation of radicals and subsequent oxidation. The SMPU surface, PIII treated for 200s, achieved a saturated level of covalently immobilized protein indicating that a full monolayer coverage was achieved. We conclude that PIII is a promising and efficient surface modification method to enhance the biocompatibility of SMPU for use in medical applications that demand bioactivity for tissue integration and stability in vivo.

  16. Input shaping control with reentry commands of prescribed duration

    Directory of Open Access Journals (Sweden)

    Valášek M.

    2008-12-01

    Full Text Available Control of flexible mechanical structures often deals with the problem of unwanted vibration. The input shaping is a feedforward method based on modification of the input signal so that the output performs the demanded behaviour. The presented approach is based on a finite-time Laplace transform. It leads to no-vibration control signal without any limitations on its time duration because it is not strictly connected to the system resonant frequency. This idea used for synthesis of control input is extended to design of dynamical shaper with reentry property that transform an arbitrary input signal to the signal that cause no vibration. All these theoretical tasks are supported by the results of simulation experiments.

  17. Laboratory transferability of optimally shaped laser pulses for quantum control

    International Nuclear Information System (INIS)

    Moore Tibbetts, Katharine; Xing, Xi; Rabitz, Herschel

    2014-01-01

    Optimal control experiments can readily identify effective shaped laser pulses, or “photonic reagents,” that achieve a wide variety of objectives. An important additional practical desire is for photonic reagent prescriptions to produce good, if not optimal, objective yields when transferred to a different system or laboratory. Building on general experience in chemistry, the hope is that transferred photonic reagent prescriptions may remain functional even though all features of a shaped pulse profile at the sample typically cannot be reproduced exactly. As a specific example, we assess the potential for transferring optimal photonic reagents for the objective of optimizing a ratio of photoproduct ions from a family of halomethanes through three related experiments. First, applying the same set of photonic reagents with systematically varying second- and third-order chirp on both laser systems generated similar shapes of the associated control landscape (i.e., relation between the objective yield and the variables describing the photonic reagents). Second, optimal photonic reagents obtained from the first laser system were found to still produce near optimal yields on the second laser system. Third, transferring a collection of photonic reagents optimized on the first laser system to the second laser system reproduced systematic trends in photoproduct yields upon interaction with the homologous chemical family. These three transfers of photonic reagents are demonstrated to be successful upon paying reasonable attention to overall laser system characteristics. The ability to transfer photonic reagents from one laser system to another is analogous to well-established utilitarian operating procedures with traditional chemical reagents. The practical implications of the present results for experimental quantum control are discussed

  18. D324-1 ITER design task on plasma control. 1995 - 1996

    International Nuclear Information System (INIS)

    Lister, J.B.; Ward, D.J.; Llobet, X.; Martin, Y.; Bosshard, P.

    1996-07-01

    The report deals with the following topics: - work carried out under phase I and proposition for work which could be carried out under phase II, -linearity of the plasma response of the TSC code, - shape control considering voltage and current saturation, - non-linear simulations without feedback, -model of errors on the estimators of the control parameters, - protective and corrective strategy control modes. (author) figs., tabs., refs

  19. A linear-field plasma jet for generating a brush-shaped laminar plume at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuechen; Jia, Pengying, E-mail: plasmalab@126.com [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Key Laboratory of Photo-Electronics Information Materials of Hebei Province, Baoding 071002 (China); Li, Jiyuan; Chu, Jingdi; Zhang, Panpan [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2016-06-15

    A linear-field plasma jet composed of line-to-plate electrodes is used to generate a large-scale brush-shaped plasma plume with flowing argon used as working gas. Through electrical measurement and fast photography, it is found that the plasma plume bridges the two electrodes for the discharge in the positive voltage half-cycle, which behaves like fast moving plasma bullets directed from the anode to the cathode. Compared with the positive discharge, the negative discharge only develops inside the nozzle and propagates much slower. Results also indicate that the gas temperature of the plume is close to room temperature, which is promising for biomedical application.

  20. Shape-controlled porous nanocarbons for high performance supercapacitors

    KAUST Repository

    Chén, Wěi

    2014-01-01

    Porous activated nanocarbons with well-controlled dimensionality and morphology (i.e. 0D activated carbon nanoparticles, 1D activated carbon nanotubes, and 2D activated carbon nanosheets) were derived successfully from different template-induced polyaniline nanostructures by facile carbonization and activation processes. The obtained nanocarbons show large specific surface areas (1332-2005 m2 g-1), good conductivities, and highly porous nanoscale architectures. The supercapacitors fabricated using the shape-controlled nanocarbons exhibit high specific capacitance, excellent rate capability, and superior long-term cycling stability in both aqueous and ionic liquid electrolytes. More importantly, a very high energy density of 50.5 W h kg-1 with a power density of 17.4 kW kg-1 can be obtained from the activated carbon nanotube based supercapacitors in an ionic liquid electrolyte (with a charge time of ∼10 s), making the shape-controlled nanocarbons promising candidates for high-performance energy storage devices. © 2014 the Partner Organisations.

  1. Shape control in wafer-based aperiodic 3D nanostructures

    International Nuclear Information System (INIS)

    Jeong, Hyeon-Ho; Mark, Andrew G; Gibbs, John G; Fischer, Peer; Reindl, Thomas; Waizmann, Ulrike; Weis, Jürgen

    2014-01-01

    Controlled local fabrication of three-dimensional (3D) nanostructures is important to explore and enhance the function of single nanodevices, but is experimentally challenging. We present a scheme based on e-beam lithography (EBL) written seeds, and glancing angle deposition (GLAD) grown structures to create nanoscale objects with defined shapes but in aperiodic arrangements. By using a continuous sacrificial corral surrounding the features of interest we grow isolated 3D nanostructures that have complex cross-sections and sidewall morphology that are surrounded by zones of clean substrate. (papers)

  2. Plasma equilibrium control during slow plasma current quench with avoidance of plasma-wall interaction in JT-60U

    Science.gov (United States)

    Yoshino, R.; Nakamura, Y.; Neyatani, Y.

    1997-08-01

    In JT-60U a vertical displacement event (VDE) is observed during slow plasma current quench (Ip quench) for a vertically elongated divertor plasma with a single null. The VDE is generated by an error in the feedback control of the vertical position of the plasma current centre (ZJ). It has been perfectly avoided by improving the accuracy of the ZJ measurement in real time. Furthermore, plasma-wall interaction has been avoided successfully during slow Ip quench owing to the good performance of the plasma equilibrium control system

  3. Practical Loop-Shaping Design of Feedback Control Systems

    Science.gov (United States)

    Kopasakis, George

    2010-01-01

    An improved methodology for designing feedback control systems has been developed based on systematically shaping the loop gain of the system to meet performance requirements such as stability margins, disturbance attenuation, and transient response, while taking into account the actuation system limitations such as actuation rates and range. Loop-shaping for controls design is not new, but past techniques do not directly address how to systematically design the controller to maximize its performance. As a result, classical feedback control systems are designed predominantly using ad hoc control design approaches such as proportional integral derivative (PID), normally satisfied when a workable solution is achieved, without a good understanding of how to maximize the effectiveness of the control design in terms of competing performance requirements, in relation to the limitations of the plant design. The conception of this improved methodology was motivated by challenges in designing control systems of the types needed for supersonic propulsion. But the methodology is generally applicable to any classical control-system design where the transfer function of the plant is known or can be evaluated. In the case of a supersonic aerospace vehicle, a major challenge is to design the system to attenuate anticipated external and internal disturbances, using such actuators as fuel injectors and valves, bypass doors, and ramps, all of which are subject to limitations in actuator response, rates, and ranges. Also, for supersonic vehicles, with long slim type of structures, coupling between the engine and the structural dynamics can produce undesirable effects that could adversely affect vehicle stability and ride quality. In order to design distributed controls that can suppress these potential adverse effects, within the full capabilities of the actuation system, it is important to employ a systematic control design methodology such as this that can maximize the

  4. Aeroelastic Modeling of Elastically Shaped Aircraft Concept via Wing Shaping Control for Drag Reduction

    Science.gov (United States)

    Nguyen, Nhan; James Urnes, Sr.

    2012-01-01

    Lightweight aircraft design has received a considerable attention in recent years as a means for improving cruise efficiency. Reducing aircraft weight results in lower lift requirements which directly translate into lower drag, hence reduced engine thrust requirements during cruise. The use of lightweight materials such as advanced composite materials has been adopted by airframe manufacturers in current and future aircraft. Modern lightweight materials can provide less structural rigidity while maintaining load-carrying capacity. As structural flexibility increases, aeroelastic interactions with aerodynamic forces and moments become an increasingly important consideration in aircraft design and aerodynamic performance. Furthermore, aeroelastic interactions with flight dynamics can result in issues with vehicle stability and control. Abstract This paper describes a recent aeroelastic modeling effort for an elastically shaped aircraft concept (ESAC). The aircraft model is based on the rigid-body generic transport model (GTM) originally developed at NASA Langley Research Center. The ESAC distinguishes itself from the GTM in that it is equipped with highly flexible wing structures as a weight reduction design feature. More significantly, the wings are outfitted with a novel control effector concept called variable camber continuous trailing edge (VCCTE) flap system for active control of wing aeroelastic deflections to optimize the local angle of attack of wing sections for improved aerodynamic efficiency through cruise drag reduction and lift enhancement during take-off and landing. The VCCTE flap is a multi-functional and aerodynamically efficient device capable of achieving high lift-to-drag ratios. The flap system is comprised of three chordwise segments that form the variable camber feature of the flap and multiple spanwise segments that form a piecewise continuous trailing edge. By configuring the flap camber and trailing edge shape, drag reduction could be

  5. Electrically controlled wire-channel GaN/AlGaN transistor for terahertz plasma applications

    Science.gov (United States)

    Cywiński, G.; Yahniuk, I.; Kruszewski, P.; Grabowski, M.; Nowakowski-Szkudlarek, K.; Prystawko, P.; Sai, P.; Knap, W.; Simin, G. S.; Rumyantsev, S. L.

    2018-03-01

    We report on a design of fin-shaped channel GaN/AlGaN field-effect transistors developed for studying resonant terahertz plasma oscillations. Unlike common two dimensional FinFET transistor design, the gates were deposited only to the sides of the two dimensional electron gas channel, i.e., metal layers were not deposited on the top of the AlGaN. This side gate configuration allowed us to electrically control the conductivity of the channel by changing its width while keeping the carrier density and mobility virtually unchanged. Computer simulations and analytical model describe well the general shape of the characteristics. The side gate control of the channel width of these transistors allowed us to eliminate the so-called oblique plasma wave modes and paves the way towards future terahertz detectors and emitters using high quality factor plasma wave resonances.

  6. Shape control of slack space reflectors using modulated solar pressure.

    Science.gov (United States)

    Borggräfe, Andreas; Heiligers, Jeannette; Ceriotti, Matteo; McInnes, Colin R

    2015-07-08

    The static deflection profile of a large spin-stabilized space reflector because of solar radiation pressure acting on its surface is investigated. Such a spacecraft consists of a thin reflective circular film, which is deployed from a supporting hoop structure in an untensioned, slack manner. This paper investigates the use of a variable reflectivity distribution across the surface to control the solar pressure force and hence the deflected shape. In this first analysis, the film material is modelled as one-dimensional slack radial strings with no resistance to bending or transverse shear, which enables a semi-analytic derivation of the nominal deflection profile. An inverse method is then used to find the reflectivity distribution that generates a specific, for example, parabolic deflection shape of the strings. Applying these results to a parabolic reflector, short focal distances can be obtained when large slack lengths of the film are employed. The development of such optically controlled reflector films enables future key mission applications such as solar power collection, radio-frequency antennae and optical telescopes.

  7. Shape-retainment control using an antagonistic shape memory alloy system

    Science.gov (United States)

    Ikeda, T.; Sawamura, K.; Senba, A.; Tamayama, M.

    2015-04-01

    Since shape memory alloy (SMA) actuators can generate large force per unit weight, they are expected as one of the next generation actuators for aircraft. To keep a position of conventional control surfaces or morphing wings with SMA actuators, the SMA actuators must keep being heated, and the heating energy is not small. To save the energy, a new control method proposed for piezoelectric actuators utilizing hysteresis in deformation [Ikeda and Takahashi, Proc. SPIE 8689 (2013), 86890C] is applied to an antagonistic SMA system. By using the control method any position can be an equilibrium point within hysteresis of stress-strain diagrams. To confirm a feasibility of the control method, a fundamental experiment is performed. The SMA wires are heated by applying electric current to the wires. When a pulsed current is applied to the two SMA wires alternately, the equilibrium position changes between two positions alternately, and when a series of pulse whose amplitude increases gradually is applied to one SMA wire, the equilibrium position changes like a staircase. However, just after the pulse the position returns slightly, that is, overshoot takes place. To investigate such a behavior of the system, numerical simulation is also performed. The one-dimensional phase transformation model [Ikeda, Proc. SPIE 5757 (2005), 344-352] is used for a constitutive model of the SMA wires. The simulated result agrees with the experiment qualitatively, including the overshoot. By examining volume fraction of each phase, it is found that the overshoot is caused by that austenite phase transforms into stress-induced martensite phase during the cooling process after the pulse.

  8. Developments in plasma physics and controlled fusion

    International Nuclear Information System (INIS)

    Thompson, W.B.

    1980-01-01

    Some developments in plasma physics over the past twenty years are considered from the theoretical physics standpoint under the headings; oscillations, waves and instabilities, plasma turbulence, basic kinetic theory, and developments in fusion. (UK)

  9. Plasma physics and controlled nuclear fusion

    International Nuclear Information System (INIS)

    Sato, Tetsuya

    1993-05-01

    The report contains the proceedings of a conference on plasma physics. A fraction of topics included MHD instabilities, magnetic confinement and plasma heating in the field of fusion plasmas, in 8 papers falling in the INIS scope have been abstracted and indexed for the INIS database. (K.A.)

  10. Control of open end plasma flow utilizing orbital stochasticity

    International Nuclear Information System (INIS)

    Hojo, Hitoshi

    1995-01-01

    It has been known that the control of plasma outside the confinement region of diverter plasma and others in a magnetic field confinement device is very important for improveing the confinement of bulk plasma. The control of plasma outside a confinement region bears two roles, one is the reduction of the thermal load on a diverter plate and others due to the plasma particles lost from the confinement region, and another is the restriction of the back flow of cold plasma and impurities generated outside the confinement region to a bulk plasma region. In this study, the new method of controlling plasma outside a confinement region called magnetic diverter is considered. To the plasma particles advancing along magnetic force lines, the reflection and capture of the plasma particles occur in the region of orbital stochasticity, and the thermal load on an end plate and the reverse flow to a bulk plasma region are restricted. The numerical computation model used regarding the particle control utilizing the orbital stochasticity and the results of calculating the orbit of plasma particles in a magnetic field are reported. (K.I.)

  11. Results of using the NSTX-U Plasma Control System for scenario development

    Science.gov (United States)

    Boyer, M. D.; Battaglia, D. J.; Gates, D. A.; Gerhardt, S.; Menard, J.; Mueller, D.; Myers, C. E.; Ferron, J.; Sabbagh, S.; NSTX-U Team

    2016-10-01

    To best use the new capabilities of NSTX-U (e.g., higher toroidal field and additional, more distributed heating and current drive sources) and to achieve the operational goals of the program, major upgrades to the Plasma Control System have been made. These include improvements to vertical control, real-time equilibrium reconstruction, and plasma boundary shape control and the addition of flexible algorithms for beam modulation and gas injection to control the upgraded actuators in real-time, enabling their use in algorithms for stored energy and profile control. Control system commissioning activities have so far focused on vertical position and shape control. The upgraded controllers have been used to explore the vertical stability limits in inner wall limited and diverted discharges, and control of X-point and strike point locations has been demonstrated and is routinely used. A method for controlling the mid-plane inner gap, a challenge for STs, has also been added to improve reproducible control of diverted discharges. A supervisory shutdown handling algorithm has also been commissioned to ramp the plasma down and safely turn off actuators after an event such as loss of vertical control. Use of the upgrades has contributed to achieving 1MA, 0.65T scenarios with greater than 1s pulse length. Work supported by U.S. D.O.E. Contract No. DE-AC02-09CH11466.

  12. Control of plasma position in the CASTOR tokamak

    International Nuclear Information System (INIS)

    Valovic, M.

    1988-11-01

    A simple servo-system designed for plasma position control in the CASTOR tokamak is described. Both radial and vertical plasma displacements were minimized using two servo-loops consisting of detection coils, a conventional electric controller and an amplifier operated as an unipolar voltage-controlled current source. To ensure the optimum conditions in the start-up phase of the discharge, currents in the servo-systems were externally preprogrammed. The prescribed plasma position was maintained with the accuracy of 3 mm. The feedback control improves plasma parameters, e.g. it removes the positional disruption at the end of the tokamak discharge. (J.U.). 4 figs., 3 refs

  13. X-ray measurements of MHD activity in shaped TCV plasmas

    International Nuclear Information System (INIS)

    Furno, I.; Weisen, H.; Moret, J.M.; Blanchard, P.; Anton, M.

    1997-01-01

    The ability of TCV to produce a wide variety of plasma shapes has allowed an investigation of MHD behaviour in a large number of limited ohmic L-mode discharges in which the elongation κ and the triangularity δ have been varied over a wide range: κ = 1.1 → 2.5, δ = -0.3 → 0.7. A 200 channel soft X-ray tomography system in conjunction with toroidal spaced soft X-ray diodes has been used to study the structure of internal disruptions and MHD modes. A strong reduction of sawtooth amplitude is observed as the plasma triangularity is decreased together with an increase in mode activity. The reduced sawtooth amplitudes are not correlated with any significant changes of the inversion radius and hence are not simply due to changes in current profiles; the inversion radius however is strongly correlated with the Spitzer conductivity profile and with the edge safety factor. (author) 5 figs., 4 refs

  14. Dependence of ideal MHD kink and ballooning modes on plasma shape and profiles in tokamaks

    International Nuclear Information System (INIS)

    Todd, A.M.M.; Manickam, J.; Okabayashi, M.; Chance, M.S.; Grimm, R.C.; Greene, J.M.; Johnson, J.L.

    1978-08-01

    Extensive numerical studies of ideal MHD instabilities have been carried out to gain insight into the parametric dependence of critical β's in tokamaks. The large number of interrelated equilibrium quantities involved in establishing a critical β has demanded a careful, systematic survey in order to isolate this dependence. The results of this survey establish the scaling with geometrical quantities including aspect ratio, elongation, and triangularity in the parameter regimes appropriate for both current and reactor-sized plasmas. A moderate dependence on the pressure profile and a strong variation with the current profile is found. The principal result is that for aspect ratio R/a approximately equal to 3, critical β's are of the order of 2% for circular cross sections and 5% for plasmas with elongation K approximately equal to 2; somewhat higher values could be achieved with more optimal shaping. Finally, sequences of equilibria have been analyzed to compare critical β as a function of toroidal mode number n. We conclude that the infinite-n analytic ballooning theory provides a sufficient condition for ideal MHD internal mode stability. Low-n free boundary modes appear to set a lower limit

  15. Powder-metallurgy preparation of NiTi shape-memory alloy using mechanical alloying and spark-plasma sintering.

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Moravec, H.; Vojtěch, V.; Knaislová, A.; Školáková, A.; Kubatík, Tomáš František; Kopeček, Jaromír

    2017-01-01

    Roč. 51, č. 1 (2017), s. 141-144 ISSN 1580-2949 R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:61389021 ; RVO:68378271 Keywords : mechanical alloying * spark plasma sintering * NiTi * shape memory alloy Subject RIV: JG - Metallurgy; JG - Metallurgy (FZU-D) OBOR OECD: Materials engineering ; Materials engineering (FZU-D) Impact factor: 0.436, year: 2016 https://www.researchgate.net/publication/313900224_Powder-metallurgy_preparation_of_NiTi_shape-memory_alloy_using_mechanical_alloying_and_spark-plasma_sintering

  16. Effect of shape of scatterers and plasma frequency on the complete photonic band gap properties of two-dimensional dielectric-plasma photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fathollahi Khalkhali, T., E-mail: tfathollahi@aeoi.org.ir; Bananej, A.

    2016-12-16

    In this study, we analyze complete photonic band gap properties of two-dimensional dielectric-plasma photonic crystals with triangular and square lattices, composed of plasma rods with different geometrical shapes in the anisotropic tellurium background. Using the finite-difference time-domain method we discuss the maximization of the complete photonic band gap width as a function of plasma frequency and plasma rods parameters with different shapes and orientations. The numerical results demonstrate that our proposed structures represent significantly wide complete photonic band gaps in comparison to previously studied dielectric-plasma photonic crystals. - Highlights: • In this paper, we have investigated plasma photonic crystals. • Plasma is a kind of dispersive medium with its equivalent refractive index related to the frequency of an incident EM wave. • In this work, our simulations are performed using the Meep implementation of the finite-difference time-domain (FDTD) method. • For this study, the lattice structures investigated are triangular and square. • Extensive calculations reveal that almost all of these structures represent wide complete band gaps.

  17. Effect of shape of scatterers and plasma frequency on the complete photonic band gap properties of two-dimensional dielectric-plasma photonic crystals

    International Nuclear Information System (INIS)

    Fathollahi Khalkhali, T.; Bananej, A.

    2016-01-01

    In this study, we analyze complete photonic band gap properties of two-dimensional dielectric-plasma photonic crystals with triangular and square lattices, composed of plasma rods with different geometrical shapes in the anisotropic tellurium background. Using the finite-difference time-domain method we discuss the maximization of the complete photonic band gap width as a function of plasma frequency and plasma rods parameters with different shapes and orientations. The numerical results demonstrate that our proposed structures represent significantly wide complete photonic band gaps in comparison to previously studied dielectric-plasma photonic crystals. - Highlights: • In this paper, we have investigated plasma photonic crystals. • Plasma is a kind of dispersive medium with its equivalent refractive index related to the frequency of an incident EM wave. • In this work, our simulations are performed using the Meep implementation of the finite-difference time-domain (FDTD) method. • For this study, the lattice structures investigated are triangular and square. • Extensive calculations reveal that almost all of these structures represent wide complete band gaps.

  18. Shavenbaby couples patterning to epidermal cell shape control.

    Directory of Open Access Journals (Sweden)

    Hélène Chanut-Delalande

    2006-09-01

    Full Text Available It is well established that developmental programs act during embryogenesis to determine animal morphogenesis. How these developmental cues produce specific cell shape during morphogenesis, however, has remained elusive. We addressed this question by studying the morphological differentiation of the Drosophila epidermis, governed by a well-known circuit of regulators leading to a stereotyped pattern of smooth cells and cells forming actin-rich extensions (trichomes. It was shown that the transcription factor Shavenbaby plays a pivotal role in the formation of trichomes and underlies all examined cases of the evolutionary diversification of their pattern. To gain insight into the mechanisms of morphological differentiation, we sought to identify shavenbaby's downstream targets. We show here that Shavenbaby controls epidermal cell shape, through the transcriptional activation of different classes of cellular effectors, directly contributing to the organization of actin filaments, regulation of the extracellular matrix, and modification of the cuticle. Individual inactivation of shavenbaby's targets produces distinct trichome defects and only their simultaneous inactivation prevent trichome formation. Our data show that shavenbaby governs an evolutionarily conserved developmental module consisting of a set of genes collectively responsible for trichome formation, shedding new light on molecular mechanisms acting during morphogenesis and the way they can influence evolution of animal forms.

  19. Thermally controlled femtosecond pulse shaping using metasurface based optical filters

    Science.gov (United States)

    Rahimi, Eesa; Şendur, Kürşat

    2018-02-01

    Shaping of the temporal distribution of the ultrashort pulses, compensation of pulse deformations due to phase shift in transmission and amplification are of interest in various optical applications. To address these problems, in this study, we have demonstrated an ultra-thin reconfigurable localized surface plasmon (LSP) band-stop optical filter driven by insulator-metal phase transition of vanadium dioxide. A Joule heating mechanism is proposed to control the thermal phase transition of the material. The resulting permittivity variation of vanadium dioxide tailors spectral response of the transmitted pulse from the stack. Depending on how the pulse's spectrum is located with respect to the resonance of the band-stop filter, the thin film stack can dynamically compress/expand the output pulse span up to 20% or shift its phase up to 360°. Multi-stacked filters have shown the ability to dynamically compensate input carrier frequency shifts and pulse span variations besides their higher span expansion rates.

  20. Water levels shape fishing participation in flood-control reservoirs

    Science.gov (United States)

    Miranda, Leandro E.; Meals, K. O.

    2013-01-01

    We examined the relationship between fishing effort (hours fished) and average March–May water level in 3 flood control reservoirs in Mississippi. Fishing effort increased as water level rose, peaked at intermediate water levels, and decreased at high water levels. We suggest that the observed arched-shaped relationship is driven by the shifting influence of fishability (adequacy of the fishing circumstances from an angler's perspective) and catch rate along a water level continuum. Fishability reduces fishing effort during low water, despite the potential for higher catch rates. Conversely, reduced catch rates and fishability at high water also curtail effort. Thus, both high and low water levels seem to discourage fishing effort, whereas anglers seem to favor intermediate water levels. Our results have implications for water level management in reservoirs with large water level fluctuations.

  1. Nonlinear control strategy based on using a shape-tunable neural controller

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.; Peng, S. [Feng Chia Univ, Taichung (Taiwan, Province of China). Department of chemical Engineering; Chang, W. [Feng Chia Univ, Taichung (Taiwan, Province of China). Department of Automatic Control

    1997-08-01

    In this paper, a nonlinear control strategy based on using a shape-tunable neural network is developed for adaptive control of nonlinear processes. Based on the steepest descent method, a learning algorithm that enables the neural controller to possess the ability of automatic controller output range adjustment is derived. The novel feature of automatic output range adjustment provides the neural controller more flexibility and capability, and therefore the scaling procedure, which is usually unavoidable for the conventional fixed-shape neural controllers, becomes unnecessary. The advantages and effectiveness of the proposed nonlinear control strategy are demonstrated through the challenge problem of controlling an open-loop unstable nonlinear continuous stirred tank reactor (CSTR). 14 refs., 11 figs.

  2. Application of comparative digital holography for distant shape control

    Science.gov (United States)

    Baumbach, Torsten; Osten, Wolfgang; von Kopylow, Christoph; Juptner, Werner P. O.

    2004-09-01

    The comparison of two objects is of great importance in the industrial production process. Especially comparing the shape is of particular interest for maintaining calibration tools or controlling the tolerance in the deviation between a sample and a master. Outsourcing and globalization of production places can result in large distances between co-operating partners and might cause problems for maintaining quality standards. Consequently new challenges arise for optical measurement techniques especially in the field of industrial shape control. In this paper we describe the progress of implementing a novel technique for comparing directly two objects with different microstructure. The technique is based on the combination of comparative holography and digital holography. Comparing the objects can be done in two ways. One is the digital comparison in the computer and the other way is by using the analogue reconstruction of a master hologram with a spatial light modulator (SLM) as coherent mask for illuminating the test object. Since this mask is stored digitally it can be transmitted via telecommunication networks and this enables the access to the full optical information of the master object at any place wanted. Beside the basic principle of comparative digital holography (CDH), we will show in this paper the set-up for doing the analogue comparison of two objects with increased sensitivity in comparison to former measurements and the calibration of the SLM that is used for the experiments. We will give examples for the digital and the analogue comparison of objects including a verification of our results by another optical measurement technique.

  3. Heat and particle transport of sol/divertor plasma in the W-shaped divertor on JT-60U

    International Nuclear Information System (INIS)

    Asakura, N.; Sakurai, S.; Hosogane, N.

    1999-01-01

    The plasma profile and parallel flow in the scrape-off layer (SOL) were systematically measured using Mach probes installed at the midplane and the divertor x-point. Quantitative evaluation of a parallel flow: naturally produced in a torus to keep the pressure constant along the field line, was consistent with the measurement. Geometry effects of the W-shaped divertor on the divertor plasma and particle recycling at the newly installed baffle plates were evaluated quantitatively using the edge plasma data. (author)

  4. The Maryland Centrifugal Experiment (MCX): Centrifugal Confinement and Velocity Shear Stabilization of Plasmas in Shaped Open Magnetic Systems

    International Nuclear Information System (INIS)

    Hassam, Adil; Ellis, Richard F.

    2012-01-01

    The Maryland Centrifugal Experiment (MCX) Project has investigated the concepts of centrifugal plasma confinement and stabilization of instabilities by velocity shear. The basic requirement is supersonic plasma rotation about a shaped, open magnetic field. Overall, the MCX Project attained three primary goals that were set out at the start of the project. First, supersonic rotation at Mach number up to 2.5 was obtained. Second, turbulence from flute interchange modes was found considerably reduced from conventional. Third, plasma pressure was contained along the field, as evidenced by density drops of x10 from the center to the mirror throats.

  5. Time-dependent simulation of plasma and electrodes in high-intensity discharge lamps with different electrode shapes

    CERN Document Server

    Flesch, P

    2003-01-01

    The subject of this paper is the modelling of d.c. and a.c. high-intensity Hg-discharge lamps with differently shaped electrodes. Different arc attachments on the electrodes are studied and insight for the development of new electrodes is gained. The model includes the entire discharge plasma (plasma column, hot plasma spots in front of electrodes, near-electrode non-LTE-plasma) as well as anode and cathode. No subdivision of the discharge space into different regions is necessary (like space charge layer, ionization zone, plasma column). This is achieved by using a differential equation for a non-LTE electrical conductivity which is applicable for local thermal equilibrium (LTE-)regions as well as for non-LTE plasma regions close to the electrodes in a high pressure plasma. Modelling results for a 0.6 MPa mercury discharge considering six different electrode shapes (anode and cathode) are presented and compared with experimental results. The electrodes have different diameters and different electrode tips, s...

  6. Feedback control of plasma position in the HL-1 tokamak

    International Nuclear Information System (INIS)

    Yuan Baoshan; Jiao Boliang; Yang Kailing

    1991-01-01

    In the HL-1 tokamak with a thick copper shell, the control of plasma position is successfully performed by a feedback-feedforward system with dual mode regulator and the equilibrium field coils outside the shell. The plasma position can be controlled within ±2 mm in both vertical and horizontal directions under the condition that the iron core of transformer is not saturated

  7. Dynamic Stall Control Using Plasma Actuators

    Science.gov (United States)

    Webb, Nathan; Singhal, Achal; Castaneda, David; Samimy, Mo

    2017-11-01

    Dynamic stall occurs in many applications, including sharp maneuvers of fixed wing aircraft, wind turbines, and rotorcraft and produces large unsteady aerodynamic loads that can lead to flutter and mechanical failure. This work uses flow control to reduce the unsteady loads by excitation of instabilities in the shear layer over the separated region using nanosecond pulse driven dielectric barrier discharge (NS-DBD) plasma actuators. These actuators have been shown to effectively delay or mitigate static stall. A wide range of flow parameters were explored in the current work: Reynolds number (Re = 167,000 to 500,000), reduced frequency (k = 0.025 to 0.075), and excitation Strouhal number (Ste = 0 to 10). Based on the results, three major conclusions were drawn: (a) Low Strouhal number excitation (Ste <0.5) results in oscillatory aerodynamic loads in the stalled stage of dynamic stall; (b) All excitation resulted in earlier flow reattachment; and (c) Excitation at progressively higher Ste weakened and eventually eliminated the dynamic stall vortex (DSV), thereby dramatically reducing the unsteady loading. The decrease in the strength of the DSV is achieved by the formation of shear layer coherent structures that bleed the leading-edge vorticity prior to the ejection of the DSV.

  8. Three-dimensional cinematography with control object of unknown shape.

    Science.gov (United States)

    Dapena, J; Harman, E A; Miller, J A

    1982-01-01

    A technique for reconstruction of three-dimensional (3D) motion which involves a simple filming procedure but allows the deduction of coordinates in large object volumes was developed. Internal camera parameters are calculated from measurements of the film images of two calibrated crosses while external camera parameters are calculated from the film images of points in a control object of unknown shape but at least one known length. The control object, which includes the volume in which the activity is to take place, is formed by a series of poles placed at unknown locations, each carrying two targets. From the internal and external camera parameters, and from locations of the images of point in the films of the two cameras, 3D coordinates of the point can be calculated. Root mean square errors of the three coordinates of points in a large object volume (5m x 5m x 1.5m) were 15 mm, 13 mm, 13 mm and 6 mm, and relative errors in lengths averaged 0.5%, 0.7% and 0.5%, respectively.

  9. Feedback control of plasma configuration in JT-60

    International Nuclear Information System (INIS)

    Ninomiya, Hiromasa; Kikuchi, Mitsuru; Yoshino, Ryuji; Hosogane, Nobuyuki; Kimura, Toyoaki; Kurihara, Kenichi; Takahashi, Minoru; Hayashi, Kazuo.

    1986-08-01

    Plasma current, plasma position (center of the outermost magnetic surface), decay index n index and width of the divertor throat are feedback controlled by using 5 kinds of poloidal field coils in JT-60. 5 control commands are calculated in a feedback control computer in each 1 msec. These feedback control functions are checked in ohmically heated plasma. The control characteristics of the plasma are well understood by the simplified control analysis and are consistent with the precise matrix transfer function analysis in the frequency domain and the simulation analysis which include the effects of eddy currents, delay time elements and mutual interactions between controllers. The usefulness of these analyses is experimentally confirmed. Each controlled variable is well feedback controlled to the command and the experimentally realized equilibrium configuration is checked by the well calibrated magnetic probes. Fast boundary identification code is used for the identification of the equilibrium and results are consistent with the precalculated plasma equilibria. By using this feedback control system of the plasma configuration and the equilibrium identification method, we have obtained the stable limiter and divertor configuration. The maximum parameters obtained during OH(I) experimental period are plasma current I p = 1.8 MA, the effective safety factor q eff e = 5.7 x 10 19 m -3 (Murakami parameter of 4.5) and the pulse length of 5 ∼ 10 sec. (author)

  10. Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

    International Nuclear Information System (INIS)

    Czarnowska, Elżbieta; Borowski, Tomasz; Sowińska, Agnieszka; Lelątko, Józef; Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał; Wierzchoń, Tadeusz

    2015-01-01

    Highlights: • Low temperature plasma nitriding process of NiTi shape memory alloy is presented. • The possibility of treatment details of sophisticated shape. • TiN surface layer has diffusive character. • TiN surface layer increases corrosion resistance of NiTi alloy. • Produced TiN layer modify the biological properties of NiTi alloy. - Abstract: NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications

  11. Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Czarnowska, Elżbieta [Children' s Memorial Health Institute, Pathology Department, Al. Dzieci Polskich 20, 04-730 Warsaw (Poland); Borowski, Tomasz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland); Sowińska, Agnieszka [Children' s Memorial Health Institute, Pathology Department, Al. Dzieci Polskich 20, 04-730 Warsaw (Poland); Lelątko, Józef [Silesia University, Faculty of Computer Science and Materials Science, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland); Wierzchoń, Tadeusz, E-mail: twierz@inmat.pw.edu.pl [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland)

    2015-04-15

    Highlights: • Low temperature plasma nitriding process of NiTi shape memory alloy is presented. • The possibility of treatment details of sophisticated shape. • TiN surface layer has diffusive character. • TiN surface layer increases corrosion resistance of NiTi alloy. • Produced TiN layer modify the biological properties of NiTi alloy. - Abstract: NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

  12. Chaos control and taming of turbulence in plasma devices

    DEFF Research Database (Denmark)

    Klinger, T.; Schröder, C.; Block, D.

    2001-01-01

    Chaos and turbulence are often considered as troublesome features of plasma devices. In the general framework of nonlinear dynamical systems, a number of strategies have been developed to achieve active control over complex temporal or spatio-temporal behavior. Many of these techniques apply...... to plasma instabilities. In the present paper we discuss recent progress in chaos control and taming of turbulence in three different plasma "model" experiments: (1) Chaotic oscillations in simple plasma diodes, (2) ionization wave turbulence in the positive column of glow discharges, and (3) drift wave...

  13. Hydrologic Controls on Shallow Landslide Location, Size, and Shape

    Science.gov (United States)

    Bellugi, D.; Milledge, D.; Perron, T.; McKean, J. A.; Dietrich, W.; Rulli, M.

    2012-12-01

    Shallow landslides, typically involving just the soil mantle, are principally controlled by topography, soil and root strengths, and soil thickness, and are typically triggered by storm-induced increases in pore water pressure. The response of a landscape to landslide-triggering storms will thus depend on factors such as rainfall totals, storm intensity and duration, and antecedent moisture conditions. The two dominant mechanisms that generate high pore water pressures at a point are topographically-steered lateral subsurface flow (over timescales of days to weeks), and rapid vertical infiltration (over timescales of minutes to hours). We aim to understand the impact of different storm characteristics and hydrologic regimes on shallow landslide location, size, and shape. We have developed a regional-scale model, which applies a low-parameter grid-based multi-dimensional slope stability model within a novel search algorithm, to generate discrete landslide predictions. This model shows that the spatial organization of parameters such as root strength and pore water pressure has a strong control on shallow landslide location, size, and shape. We apply this model to a field site near Coos Bay, OR, where a ten-year landslide inventory has been mapped onto high-resolution topographic data. Our model predicts landslide size generally increases with increasing rainfall intensity, except when root strength is extremely high and pore pressures are topographically steered. The distribution of topographic index values (the ratios of contributing area to slope) of predicted landslides is a clear signature of the pore water pressure generation mechanism: as laterally dominated flow increases, landslides develop in locations with lower slopes and higher contributing areas; in contrast, in the case of vertically-dominated pore pressure rise, landslides are consistently found in locations with higher slopes and lower contributing areas. While in both cases landslides are found in

  14. Digital control of plasma position in Damavand tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Emami, M.; Babazadeh, A.R.; Roshan, M.V.; Memarzadeh, M.; Habibi, H. [Atomic Energy Organization of Iran (AEOI), Tehran (Iran, Islamic Republic of). Nuclear Fusion Research Center. Plasma Physics Lab.

    2002-03-01

    Plasma position control is one of the important issues in the design and operation of tokamak fusion research device. Since a tokamak is basically an electrical system consisting of power supplies, coils, plasma and eddy currents, a model in which these components are treated as an electrical circuits is used in designing Damavand plasma position control system. This model is used for the simulation of the digital control system and its parameters have been verified experimentally. In this paper, the performance of a high-speed digital controller as well as a simulation study and its application to the Damavand tokamak is discussed. (author)

  15. Atto-second control of collective electron motion in plasmas

    International Nuclear Information System (INIS)

    Borot, Antonin; Malvache, Arnaud; Chen, Xiaowei; Jullien, Aurelie; Lopez-Martens, Rodrigo; Geindre, Jean-Paul; Audebert, Patrick; Mourou, Gerard; Quere, Fabien

    2012-01-01

    Today, light fields of controlled and measured waveform can be used to guide electron motion in atoms and molecules with atto-second precision. Here, we demonstrate atto-second control of collective electron motion in plasmas driven by extreme intensity (approximate to 10 18 W cm -2 ) light fields. Controlled few-cycle near-infrared waves are tightly focused at the interface between vacuum and a solid-density plasma, where they launch and guide sub-cycle motion of electrons from the plasma with characteristic energies in the multi-kilo-electron-volt range-two orders of magnitude more than has been achieved so far in atoms and molecules. The basic spectroscopy of the coherent extreme ultraviolet radiation emerging from the light-plasma interaction allows us to probe this collective motion of charge with sub-200 as resolution. This is an important step towards atto-second control of charge dynamics in laser-driven plasma experiments. (authors)

  16. plasmatis Center for Innovation Competence: Controlling reactive component output of atmospheric pressure plasmas in plasma medicine

    Science.gov (United States)

    Reuter, Stephan

    2012-10-01

    The novel approach of using plasmas in order to alter the local chemistry of cells and cell environment presents a significant development in biomedical applications. The plasmatis center for innovation competence at the INP Greifswald e.V. performs fundamental research in plasma medicine in two interdisciplinary research groups. The aim of our plasma physics research group ``Extracellular Effects'' is (a) quantitative space and time resolved diagnostics and modelling of plasmas and liquids to determine distribution and composition of reactive species (b) to control the plasma and apply differing plasma source concepts in order to produce a tailored output of reactive components and design the chemical composition of the liquids/cellular environment and (c) to identify and understand the interaction mechanisms of plasmas with liquids and biological systems. Methods to characterize the plasma generated reactive species from plasma-, gas- and liquid phase and their biological effects will be presented. The diagnostic spectrum ranges from absorption/emission/laser spectroscopy and molecular beam mass spectrometry to electron paramagnetic resonance spectroscopy and cell biological diagnostic techniques. Concluding, a presentation will be given of the comprehensive approach to plasma medicine in Greifswald where the applied and clinical research of the Campus PlasmaMed association is combined with the fundamental research at plasmatis center.

  17. Fundamentals of plasma physics and controlled fusion

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Kenro

    2000-10-01

    The present lecture note was written to fill a gap between text books for undergraduates and specific review articles written by specialists for their young colleagues. The note may be divided in three parts. The first part is on basic characteristics of a plasma in a magnetic field. The second part describes plasma confinement and heating with an emphasis on magnetohydrodynamic instabilities. In addition, propagation of plasma waves, plasma heating by electromagnetic waves are given. The third part is devoted to various specific concepts of nuclear fusion. Emphases are placed on toroidal devices, especially on tokamak devices and stellarators. One might feel heavy mathematics glimpsing the present note, especially in the part treating magnetohydrodynamic instabilities. (author)

  18. Plasma Equilibrium Control in Nuclear Fusion Devices 2. Plasma Control in Magnetic Confinement Devices 2.1 Plasma Control in Tokamaks

    Science.gov (United States)

    Fukuda, Takeshi

    The plasma control technique for use in large tokamak devices has made great developmental strides in the last decade, concomitantly with progress in the understanding of tokamak physics and in part facilitated by the substantial advancement in the computing environment. Equilibrium control procedures have thereby been established, and it has been pervasively recognized in recent years that the real-time feedback control of physical quantities is indispensable for the improvement and sustainment of plasma performance in a quasi-steady-state. Further development is presently undertaken to realize the “advanced plasma control” concept, where integrated fusion performance is achieved by the simultaneous feedback control of multiple physical quantities, combined with equilibrium control.

  19. The improvement of the detection power of a U-shaped DC plasma

    Directory of Open Access Journals (Sweden)

    DRAGAN MARKOVIC

    2001-04-01

    Full Text Available Optimization of the operating parameters of U-shpaed DC arc plasma and spectrometer parameters has been undertaken to explore the possibilities of improving its detection power. It is demonstrated, with a U-shaped arc as an example, that the limits of detection, in addition to well-defined parameters as described by Boumans and Winge, depend on the signal integration time. It is shown that with increasing integration time, the limits of detection are decreased within some limits and that the precision and concentration sensitivity are improved as well. A mathematical expression for the dependence of the detection limit on the integration time is presented. To increase the reliability of the measurement of the mentioned parameters, the working conditions were optimized for the following analytes: Ag, Al, Au, Cr, Fe, Mn, Ni, Pb, Pd, Pt, and V. The obtained limits of detection are comparable or better than those obtained by ICP for the elements studied. Itwas estimed that the possibility exists for their further improvement up to 10 times.

  20. Geometric shape control of thin film ferroelectrics and resulting structures

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick J.

    2000-01-01

    A monolithic crystalline structure and a method of making involves a semiconductor substrate, such as silicon, and a ferroelectric film, such as BaTiO.sub.3, overlying the surface of the substrate wherein the atomic layers of the ferroelectric film directly overlie the surface of the substrate. By controlling the geometry of the ferroelectric thin film, either during build-up of the thin film or through appropriate treatment of the thin film adjacent the boundary thereof, the in-plane tensile strain within the ferroelectric film is relieved to the extent necessary to permit the ferroelectric film to be poled out-of-plane, thereby effecting in-plane switching of the polarization of the underlying substrate material. The method of the invention includes the steps involved in effecting a discontinuity of the mechanical restraint at the boundary of the ferroelectric film atop the semiconductor substrate by, for example, either removing material from a ferroelectric film which has already been built upon the substrate, building up a ferroelectric film upon the substrate in a mesa-shaped geometry or inducing the discontinuity at the boundary by ion beam deposition techniques.

  1. Thermally controlled femtosecond pulse shaping using metasurface based optical filters

    Directory of Open Access Journals (Sweden)

    Rahimi Eesa

    2018-02-01

    Full Text Available Shaping of the temporal distribution of the ultrashort pulses, compensation of pulse deformations due to phase shift in transmission and amplification are of interest in various optical applications. To address these problems, in this study, we have demonstrated an ultra-thin reconfigurable localized surface plasmon (LSP band-stop optical filter driven by insulator-metal phase transition of vanadium dioxide. A Joule heating mechanism is proposed to control the thermal phase transition of the material. The resulting permittivity variation of vanadium dioxide tailors spectral response of the transmitted pulse from the stack. Depending on how the pulse’s spectrum is located with respect to the resonance of the band-stop filter, the thin film stack can dynamically compress/expand the output pulse span up to 20% or shift its phase up to 360°. Multi-stacked filters have shown the ability to dynamically compensate input carrier frequency shifts and pulse span variations besides their higher span expansion rates.

  2. Functionally-interdependent shape-switching nanoparticles with controllable properties

    Science.gov (United States)

    Halman, Justin R.; Satterwhite, Emily; Roark, Brandon; Chandler, Morgan; Viard, Mathias; Ivanina, Anna; Bindewald, Eckart; Kasprzak, Wojciech K.; Panigaj, Martin; Bui, My N.; Lu, Jacob S.; Miller, Johann; Khisamutdinov, Emil F.; Shapiro, Bruce A.; Dobrovolskaia, Marina A.

    2017-01-01

    Abstract We introduce a new concept that utilizes cognate nucleic acid nanoparticles which are fully complementary and functionally-interdependent to each other. In the described approach, the physical interaction between sets of designed nanoparticles initiates a rapid isothermal shape change which triggers the activation of multiple functionalities and biological pathways including transcription, energy transfer, functional aptamers and RNA interference. The individual nanoparticles are not active and have controllable kinetics of re-association and fine-tunable chemical and thermodynamic stabilities. Computational algorithms were developed to accurately predict melting temperatures of nanoparticles of various compositions and trace the process of their re-association in silico. Additionally, tunable immunostimulatory properties of described nanoparticles suggest that the particles that do not induce pro-inflammatory cytokines and high levels of interferons can be used as scaffolds to carry therapeutic oligonucleotides, while particles with strong interferon and mild pro-inflammatory cytokine induction may qualify as vaccine adjuvants. The presented concept provides a simple, cost-effective and straightforward model for the development of combinatorial regulation of biological processes in nucleic acid nanotechnology. PMID:28108656

  3. Remote automatic control scheme for plasma arc cutting of contaminated waste

    International Nuclear Information System (INIS)

    Dudar, A.M.; Ward, C.R.; Kriikku, E.M.

    1993-01-01

    Plasma arc cutting is a popular technique used for size reduction of radioactively contaminated metallic waste such as glove boxes, vessels, and ducts. It is a very aggressive process and is capable of cutting metal objects up to 3 in. thick. The crucial control criteria in plasma cutting is maintaining a open-quotes stand-offclose quotes distance between the plasma torch tip and the material being cut. Manual plasma cutting techniques in radioactive environments require the operator to wear a plastic suit covered by a metallic suit. This is very cumbersome, time-consuming, and also generates additional waste (plastic and metallic suits). Teleoperated remote cutting is preferable to manual cutting, but our experience has shown that remote control of the stand-off distance is particularly difficult because of the brightness of the plasma arc and inadequate viewing angles. Also, the heat generated by the torch causes the sheet metal to deform and warp during plasma cutting, creating a dynamically changing metal surface. The aforementioned factors make it extremely difficult, if not impossible, to perform plasma cuts of waste with a variety of shapes and sizes in a teleoperated fashion with an operator in the loop. Automating the process is clearly desirable

  4. Variable Camber Continuous Aerodynamic Control Surfaces and Methods for Active Wing Shaping Control

    Science.gov (United States)

    Nguyen, Nhan T. (Inventor)

    2016-01-01

    An aerodynamic control apparatus for an air vehicle improves various aerodynamic performance metrics by employing multiple spanwise flap segments that jointly form a continuous or a piecewise continuous trailing edge to minimize drag induced by lift or vortices. At least one of the multiple spanwise flap segments includes a variable camber flap subsystem having multiple chordwise flap segments that may be independently actuated. Some embodiments also employ a continuous leading edge slat system that includes multiple spanwise slat segments, each of which has one or more chordwise slat segment. A method and an apparatus for implementing active control of a wing shape are also described and include the determination of desired lift distribution to determine the improved aerodynamic deflection of the wings. Flap deflections are determined and control signals are generated to actively control the wing shape to approximate the desired deflection.

  5. Plasma Fluctuation Studies in the TCV Tokamak: Modeling of Shaping Effects and Advanced Diagnostic Development

    International Nuclear Information System (INIS)

    Marinoni, A.

    2009-10-01

    therefore also well suited to investigate inhomogeneous spatial regions, where the need for an excellent spatial resolution is greatest. Additionally, it was also designed as translatable to broaden the region of study, which can extend up to the magnetic axis, in selected configurations. The translatable design combined with the flexibility of TCV in terms of plasma positioning in the vacuum vessel allows the phase contrast system to measure fluctuations across virtually the whole plasma minor radius. The diagnostic is sensitive both to radial and poloidal wave numbers, depending on the configuration. A parallel project to the development and installation of the phase contrast imaging system was the installation of a prototype Doppler reflectometer operating in a homodyne configuration, both in X and in O mode polarization. The reflectometer was operated parasitically to assess its performance which proved to be excellent; it is now routinely available on TCV. The theoretical part of the thesis consisted of extensive modeling of the effect of plasma shape, in particular triangularity, on turbulent transport by means of linear and nonlinear gyrokinetic simulations. This was motivated by experiments on TCV that had shown a dramatic improvement in confinement, up to a factor of two, in inverting the sign of the triangularity from positive to negative. Negative triangularity was indeed found to have a stabilizing influence on ion scale instabilities, specifically on the so called trapped electron mode (TEM). Simulations were carried out on actual TCV shots and the variation of the heat flux with triangularity calculated by the nonlinear simulations is in fair agreement with the experimental results. Linear simulations and a simple analytical model explain, in agreement with nonlinear runs, the resulting stabilization as a result of a rather complex modification of the toroidal precessional drift of trapped particles exerted by negative triangularity. (author)

  6. A new shape reproduction method based on the Cauchy-condition surface for real-time tokamak reactor control

    International Nuclear Information System (INIS)

    Kurihara, K.

    2000-01-01

    A new shape reproduction method is investigated on the basis of an applied mathematical approach. An analytically exact solution of Maxwell's equations in a static current field yields an (boundary) integral equation. In application of this equation to tokamak plasma shape reproduction, it is made clear that a Cauchy condition (both Dirichlet and Neumann conditions) on a hypothetical surface is necessarily identified. To calculate the Cauchy condition using magnetic sensor signals, conversion to numerical formulation of this method is conducted. Then, reproduction errors by this method are evaluated through two numerical tests: The first test uses ideal signals produced from a full equilibrium code in the JT-60 geometry, and the second test uses actual sensor signals in JT-60 experiments. In addition, it is shown that positioning and shape of the Cauchy condition surface is insensitive to reproduction error. Finally, this method is clarified to have preferable features for real-time tokamak reactor control

  7. Alushta-2012. International Conference-School on Plasma Physics and Controlled Fusion and the Adjoint Workshop 'Nano-and micro-sized structures in plasmas'. Book of Abstracts

    International Nuclear Information System (INIS)

    Makhlaj, V.A.

    2012-01-01

    The Conference was devoted to a new valuable information about the present status of plasma physics and controlled fusion research. The main topics was : magnetic confinement systems; plasma heating and current drive; ITER and fusion reactor aspects; basic plasma physics; space plasma; plasma dynamics and plasma-wall interaction; plasma electronics; low temperature plasma and plasma technologies; plasma diagnostics; formation of nano-and micro-sized structures in plasmas; properties of plasmas with nano- and micro- objects

  8. Plasma physics and controlled nuclear fusion research 1988. V.3

    International Nuclear Information System (INIS)

    1989-01-01

    Volume 3 of the proceedings of the twelfth international conference on plasma physics and controlled nuclear fusion, held in Nice, France, 12-19 October, 1988, contains papers presented on inertial fusion. Direct and indirect laser implosion experiments, programs of laser construction, computer modelling of implosions and resulting plasmas, and light ion beam fusion experiments are discussed. Refs, figs and tabs

  9. Processes for forming exoergic structures with the use of a plasma and for producing dense refractory bodies of arbitrary shape therefrom

    International Nuclear Information System (INIS)

    Holt, J.B.; Kelly, M.D.

    1990-01-01

    Plasma spraying methods of forming exoergic structures and coatings, as well as exoergic structures produced by such methods, are presented. The methods include the plasma spraying of reactive exoergic materials that are capable of sustaining a combustion synthesis reaction onto a flat substrate or into molds of arbitrary shape and igniting the plasma sprayed materials, either under an inert gas pressure or not, to form refractory materials of varying densities and of varying shapes

  10. Development of compact toroids injector for direct plasma controls

    Energy Technology Data Exchange (ETDEWEB)

    Azuma, K. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Oda, Y. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Onozuka, M. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Uyama, T. [Himeji Inst. of Tech. (Japan); Nagata, M. [Himeji Inst. of Tech. (Japan); Fukumoto, N. [Himeji Inst. of Tech. (Japan)

    1995-12-31

    The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 10{sup 21}m{sup -3}. (orig.).

  11. Development of compact toroids injector for direct plasma controls

    International Nuclear Information System (INIS)

    Azuma, K.; Oda, Y.; Onozuka, M.; Uyama, T.; Nagata, M.; Fukumoto, N.

    1995-01-01

    The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 10 21 m -3 . (orig.)

  12. National Spherical Torus Experiment Real Time Plasma Control Data Acquisition Hardware

    International Nuclear Information System (INIS)

    R.J. Marsala; J. Schneider

    2002-01-01

    The National Spherical Torus Experiment (NSTX) is currently providing researchers data on low aspect-ratio toroidal plasmas. NSTX's Plasma Control System adjusts the firing angles of thyristor rectifier power supplies, in real time, to control plasma position, shape and density. A Data Acquisition system comprised of off-the-shelf and custom hardware provides the magnetic diagnostics data required in calculating firing angles. This VERSAmodule Eurocard (VME) bus-based system utilizes Front Panel Data Port (FPDP) for high-speed data transfer. Data coming from physically different locations is referenced to several different ground potentials necessitating the need for a custom FPDP multiplexer. This paper discusses the data acquisition system configuration, the in-house designed 4-to-1 FPDP Input Multiplexing Module (FIMM), and future expansion plans

  13. Optimal control theory applied to fusion plasma thermal stabilization

    International Nuclear Information System (INIS)

    Sager, G.; Miley, G.; Maya, I.

    1985-01-01

    Many authors have investigated stability characteristics and performance of various burn control schemes. The work presented here represents the first application of optimal control theory to the problem of fusion plasma thermal stabilization. The objectives of this initial investigation were to develop analysis methods, demonstrate tractability, and present some preliminary results of optimal control theory in burn control research

  14. Abstracts of the 23rd European physical society conference on controlled fusion and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Goutych, I F; Gresillon, D; Sitenko, A G

    1997-12-31

    This document contains the abstracts of the invited and contributed papers presented at 23 EPS conference on controlled fusion and plasma physics. The main contents are: tokamaks, stellarators; alternative magnetic confinement; plasma edge physics; plasma heating and current drive; plasma diagnostics; basic collisionless plasma physics; high intensity laser produced plasmas and inertial confinement; low-temperature plasmas.

  15. Abstracts of the 23rd European physical society conference on controlled fusion and plasma physics

    International Nuclear Information System (INIS)

    Goutych, I.F.; Gresillon, D.; Sitenko, A.G.

    1996-01-01

    This document contains the abstracts of the invited and contributed papers presented at 23 EPS conference on controlled fusion and plasma physics. The main contents are: tokamaks, stellarators; alternative magnetic confinement; plasma edge physics; plasma heating and current drive; plasma diagnostics; basic collisionless plasma physics; high intensity laser produced plasmas and inertial confinement; low-temperature plasmas

  16. Improvement of confinement characteristics of tokamak plasma by controlling plasma-wall interactions

    International Nuclear Information System (INIS)

    Sengoku, Seio

    1985-08-01

    Relation between plasma-wall interactions and confinement characteristics of a tokamak plasma with respect to both impurity and fuel particle controls is discussed. Following results are obtained from impurity control studies: (1) Ion sputtering is the dominant mechanism of impurity release in a steady state tokamak discharge. (2) By applying carbon coating on entire first wall of DIVA tokamak, dominant radiative region is concentrated more in boundary plasma resulting a hot peripheral plasma with cold boundary plasma. (3) A physical model of divertor functions about impurity control is empilically obtained. By a computer simulation based on above model with respect to divertor functions for JT-60 tokamak, it is found that the allowable electron temperature of the divertor plasma is not restricted by a condition that the impurity release due to ion sputtering does not increase continuously. (4) Dense and cold divertor plasma accompanied with strong remote radiative cooling was diagnosed along the magnetic field line in the simple poloidal divertor of DOUBLET III tokamak. Strong particle recycling region is found to be localized near the divertor plate. by and from particle control studies: (1) The INTOR scaling on energy confinement time is applicable to high density region when a core plasma is fueled directly by solid deuterium pellet injection in DOUBLET III tokamak. (2) As remarkably demonstrated by direct fueling with pellet injection, energy confinement characteristics can be improved at high density range by decreasing particle deposition at peripheral plasma in order to reduce plasma-wall interaction. (3) If the particle deposition at boundary layer is necessarily reduced, the electron temperature at the boundary or divertor region increases due to decrease of the particle recycling and the electron density there. (J.P.N.)

  17. Implementation of GPU parallel equilibrium reconstruction for plasma control in EAST

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yao, E-mail: yaohuang@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Xiao, B.J. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); School of Nuclear Science & Technology, University of Science & Technology of China (China); Luo, Z.P.; Yuan, Q.P.; Pei, X.F. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Yue, X.N. [School of Nuclear Science & Technology, University of Science & Technology of China (China)

    2016-11-15

    Highlights: • We described parallel equilibrium reconstruction code P-EFIT running on GPU was integrated with EAST plasma control system. • Compared with RT-EFIT used in EAST, P-EFIT has better spatial resolution and full algorithm of EFIT per iteration. • With the data interface through RFM, 65 × 65 spatial grids P-EFIT can satisfy the accuracy and time feasibility requirements for plasma control. • Successful control using ISOFLUX/P-EFIT was established in the dedicated experiment during the EAST 2014 campaign. • This work is a stepping-stone towards versatile ISOFLUX/P-EFIT control, such as real-time equilibrium reconstruction with more diagnostics. - Abstract: Implementation of P-EFIT code for plasma control in EAST is described. P-EFIT is based on the EFIT framework, but built with the CUDA™ architecture to take advantage of massively parallel Graphical Processing Unit (GPU) cores to significantly accelerate the computation. 65 × 65 grid size P-EFIT can complete one reconstruction iteration in 300 μs, with one iteration strategy, it can satisfy the needs of real-time plasma shape control. Data interface between P-EFIT and PCS is realized and developed by transferring data through RFM. First application of P-EFIT to discharge control in EAST is described.

  18. Effect of voltage shape of electrical power supply on radiation and density of a cold atmospheric argon plasma jet

    Directory of Open Access Journals (Sweden)

    F Sohbatzadeh

    2017-02-01

    Full Text Available In this work, we investigated generating argon cold plasma jet at atmospheric pressure based on dielectric barrier discharge configuration using three electrical power supplies of sinusoidal, pulsed and saw tooth high voltage shapes at 8 KHZ. At first; we describe the electronic circuit features for generating high voltage (HV wave forms including saw tooth, sinusoidal and pulsed forms. Then, we consider the effect of voltage shape on the electrical breakdown. Relative concentrations of chemical reactive species such as Oxygen, atomic Nitrogen and OH were measured using optical emission spectroscopy. Using a simple numerical model, we showed a HV with less rise time increases electron density, therefore a cold plasma jet can be produced with a minimal consumption electrical power

  19. Passive control of a sphere by complex-shaped appendages

    Science.gov (United States)

    Bagheri, Shervin; Lacis, Ugis; Olivieri, Stefano; Mazzino, Andrea

    2015-11-01

    Appendages of various shapes and sizes (e.g. plumes, barbs, tails, feathers, hairs, fins) play an important role in dispersion and locomotion. In our previous work (Lacis, U. et al. Passive appendages generate drift through symmetry breaking. Nat. Commun. 5:5310, doi: 10.1038/ncomms6310, 2014), we showed that a free-falling cylinder with a splitter plate turns and drifts due to a symmetry-breaking instability (called inverted-pendulum instability or IPL). In other words, in a separated flow, the straight position of a short splitter plate is unstable and as a consequence a side force and a torque are induced on the cylinder. In this work, we seek the three-dimensional (3D) appendage shape (on a sphere at Re =200) that induces the largest drift of the sphere. We find that highly non-trivial shapes of appendages on a sphere increase the side force significantly compared to trivial shapes (such as an elliptic sheet). We also find that appendages may be designed to generate drift in either direction, that is, a free-falling sphere can drift either in the direction in which appendage is tilted or in the opposite direction depending on the particular geometry of the appendage. We discuss the physical mechanisms behind these optimal appendage shapes in the context of the IPL instability.

  20. BOOK REVIEW: Controlled Fusion and Plasma Physics

    Science.gov (United States)

    Engelmann, F.

    2007-07-01

    This new book by Kenro Miyamoto provides an up-to-date overview of the status of fusion research and the important parts of the underlying plasma physics at a moment where, due to the start of ITER construction, an important step in fusion research has been made and many new research workers will enter the field. For them, and also for interested graduate students and physicists in other fields, the book provides a good introduction into fusion physics as, on the whole, the presentation of the material is quite appropriate for getting acquainted with the field on the basis of just general knowledge in physics. There is overlap with Miyamoto's earlier book Plasma Physics for Nuclear Fusion (MIT Press, Cambridge, USA, 1989) but only in a few sections on subjects which have not evolved since. The presentation is subdivided into two parts of about equal length. The first part, following a concise survey of the physics basis of thermonuclear fusion and of plasmas in general, covers the various magnetic configurations studied for plasma confinement (tokamak; reversed field pinch; stellarator; mirror-type geometries) and introduces the specific properties of plasmas in these devices. Plasma confinement in tokamaks is treated in particular detail, in compliance with the importance of this field in fusion research. This includes a review of the ITER concept and of the rationale for the choice of ITER's parameters. In the second part, selected topics in fusion plasma physics (macroscopic instabilities; propagation of waves; kinetic effects such as energy transfer between waves and particles including microscopic instabilities as well as plasma heating and current drive; transport phenomena induced by turbulence) are presented systematically. While the emphasis is on displaying the essential physics, deeper theoretical analysis is also provided here. Every chapter is complemented by a few related problems, but only partial hints for their solution are given. A selection of

  1. Real-time control of Tokamak plasmas: from control of physics to physics-based control

    International Nuclear Information System (INIS)

    Felici, F. A. A.

    2011-11-01

    Stable, high-performance operation of a tokamak requires several plasma control problems to be handled simultaneously. Moreover, the complex physics which governs the tokamak plasma evolution must be studied and understood to make correct choices in controller design. In this thesis, the two subjects have been merged, using control solutions as experimental tool for physics studies, and using physics knowledge for developing new advanced control solutions. The TCV tokamak at CRPP-EPFL is ideally placed to explore issues at the interface between plasma physics and plasma control, by combining a digital realtime control system with a flexible and powerful set of actuators, in particular the electron cyclotron heating and current drive system (ECRH/ECCD). This experimental platform has been used to develop and test new control strategies for three plasma physics instabilities: sawtooth, edge localized mode (ELM) and neoclassical tearing mode (NTM). The period of the sawtooth crash, a periodic MHD instability in the core of a tokamak plasma, can be varied by localized deposition of ECRH/ECCD near the q = 1 surface (q: safety factor). A sawtooth pacing controller was developed which is able to control the time of appearance of the next sawtooth crash. Each individual sawtooth period can be controlled in real-time. A similar scheme is applied to H-mode plasmas with type-I ELMs, where it is shown that pacing regularizes the ELM period. The regular, reproducible and therefore predictable sawtooth crashes have been used to study the relationship between sawteeth and NTMs. Postcrash MHD activity can provide the ‘seed’ island for an NTM, which then grows under its neoclassical bootstrap drive. The seeding of 3/2 NTMs by long sawtooth crashes can be avoided by preemptive, crash-synchronized EC power injection pulses at the q = 3/2 rational surface location. NTM stabilization experiments in which the ECRH deposition location is moved in real-time with steerable mirrors have

  2. Slit shaped microwave induced atmospheric pressure plasma based on a parallel plate transmission line resonator

    Science.gov (United States)

    Kang, S. K.; Seo, Y. S.; Lee, H. Wk; Aman-ur-Rehman; Kim, G. C.; Lee, J. K.

    2011-11-01

    A new type of microwave-excited atmospheric pressure plasma source, based on the principle of parallel plate transmission line resonator, is developed for the treatment of large areas in biomedical applications such as skin treatment and wound healing. A stable plasma of 20 mm width is sustained by a small microwave power source operated at a frequency of 700 MHz and a gas flow rate of 0.9 slm. Plasma impedance and plasma density of this plasma source are estimated by fitting the calculated reflection coefficient to the measured one. The estimated plasma impedance shows a decreasing trend while estimated plasma density shows an increasing trend with the increase in the input power. Plasma uniformity is confirmed by temperature and optical emission distribution measurements. Plasma temperature is sustained at less than 40 °C and abundant amounts of reactive species, which are important agents for bacteria inactivation, are detected over the entire plasma region. Large area treatment ability of this newly developed device is verified through bacteria inactivation experiment using E. coli. Sterilization experiment shows a large bacterial killing mark of 25 mm for a plasma treatment time of 10 s.

  3. Solar High-energy Astrophysical Plasmas Explorer (SHAPE). Volume 1: Proposed concept, statement of work and cost plan

    Science.gov (United States)

    Dennis, Brian R.; Martin, Franklin D.; Prince, T.; Lin, R.; Bruner, M.; Culhane, L.; Ramaty, R.; Doschek, G.; Emslie, G.; Lingenfelter, R.

    1986-01-01

    The concept of the Solar High-Energy Astrophysical Plasmas Explorer (SHAPE) is studied. The primary goal is to understand the impulsive release of energy, efficient acceleration of particles to high energies, and rapid transport of energy. Solar flare studies are the centerpieces of the investigation because in flares these high energy processes can be studied in unmatched detail at most wavelenth regions of the electromagnetic spectrum as well as in energetic charged particles and neutrons.

  4. Control of plasma column horizontal position in TBR-1

    International Nuclear Information System (INIS)

    Tuszel, A.G.; Rincoski, C.R.M.

    1990-01-01

    The TBR-1 is a small tokamak built at the Physics Institute of the University of Sao Paulo. It was originally designed with a simple vertical field power supply made of one fast capacitor bank for vertical current build-up and one slow capacitor bank for flat-top phase, without any control but the adjustable initial voltages of the capacitors. With such an elementary system, the plasma cannot be held in the center of the vacuum vessel for the whole duration of the plasma. This led to a suboptimal performance with easy disruptions. A control system was designed to hold the plasma centered in the radial coordinate. (Author)

  5. Plasma under control: Advanced solutions and perspectives for plasma flux management in material treatment and nanosynthesis

    Science.gov (United States)

    Baranov, O.; Bazaka, K.; Kersten, H.; Keidar, M.; Cvelbar, U.; Xu, S.; Levchenko, I.

    2017-12-01

    Given the vast number of strategies used to control the behavior of laboratory and industrially relevant plasmas for material processing and other state-of-the-art applications, a potential user may find themselves overwhelmed with the diversity of physical configurations used to generate and control plasmas. Apparently, a need for clearly defined, physics-based classification of the presently available spectrum of plasma technologies is pressing, and the critically summary of the individual advantages, unique benefits, and challenges against key application criteria is a vital prerequisite for the further progress. To facilitate selection of the technological solutions that provide the best match to the needs of the end user, this work systematically explores plasma setups, focusing on the most significant family of the processes—control of plasma fluxes—which determine the distribution and delivery of mass and energy to the surfaces of materials being processed and synthesized. A novel classification based on the incorporation of substrates into plasma-generating circuitry is also proposed and illustrated by its application to a wide variety of plasma reactors, where the effect of substrate incorporation on the plasma fluxes is emphasized. With the key process and material parameters, such as growth and modification rates, phase transitions, crystallinity, density of lattice defects, and others being linked to plasma and energy fluxes, this review offers direction to physicists, engineers, and materials scientists engaged in the design and development of instrumentation for plasma processing and diagnostics, where the selection of the correct tools is critical for the advancement of emerging and high-performance applications.

  6. Development of the 'JFT-2' tokamak plasma position control system

    International Nuclear Information System (INIS)

    Fujisawa, Noboru; Matsuzaki, Yoshimi; Suzuki, Norio; Murai, Katsuji; Suzuki, Satoshi.

    1980-01-01

    Digital control technique was applied to control the plasma position in the JFT-2 tokamak experiment device. The detail of the JFT-2 is described elsewhere. The plasma position control system consists of a Hitachi control computer, HIDIC 80, and a Hitachi micro-computer, HIDIC 08E. The plasma position is detected by the position control computer, and compared with a preset value. Then, a reference signal is supplied to the micro-computer controlling power source, and the phase control of the thyristor controlling power source is performed. Since the behavior of plasma is very fast, the fast control is required. The control of the thyristor controlling power source is made by direct digital control (DDC). The main component of the hardware of the present system is the micro-computer HIDIC 08E. The software is the direct task system without the operating system (OS). The results of experiments showed that the feedback control of the system worked well. (Kato, T.)

  7. 10th International Conference and School on Plasma Physics and Controlled Fusion. Book of Abstracts

    International Nuclear Information System (INIS)

    Anon

    2004-01-01

    About 240 abstracts by Ukrainian and foreign authors submitted to 10-th International Conference and School on Plasma Physics and Controlled fusion have been considered by Conference Program Committee members. All the abstracts have been divided into 8 groups: magnetic confinement systems: stellarators, tokamaks, alternative conceptions; ITER and Fusion reactor aspects; basic plasma physics; space plasma; plasma dynamics and plasma-wall interaction; plasma electronics; low temperature plasma and plasma technologies; plasma diagnostics

  8. Improvement of Ti-plasma coating on Ni-Ti shape memory alloy applying to implant materials and its evaluation

    International Nuclear Information System (INIS)

    Okuyama, Masaru; Endo, Jun; Take, Seisho; Itoi, Yasuhiko; Kambe, Satoshi

    2002-01-01

    Utilizing of Ni-Ti shape memory alloy for implant materials has been world-widely studied. it is, however, known that Ni-Ti alloy is easily attacked by chloride ion contained in body liquid. To prevent Ni dissolution, the authors tried to coat the alloy surface with titanium metal by means of plasma-spray coating method. The plasma coating films resulted in rather accelerating pitting corrosion because of their high porosity. Therefore, sealing of the porous films was required. In order to solve this problem and satisfy prolonged lifetime in the body, the authors tried to use the vacuum evaporation technique of titanium metal. Two types of Ti vacuum evaporation procedures were employed. The one was to cover a thin film on Ni-Ti alloy surface prior to massive Ti plasma spray coating. The other was to first coat plasma spray films on Ni-Ti alloy and then to cover them with vacuum evaporation films of Ti. Protective ability against pitting corrosion was examined by electrochemical polarization measurement in physiological solution and the coating films were characterized by microscopic and SEM observation and EPMA analysis. Vacuum evaporation thin films could not protect Ni-Ti alloy from pitting corrosion. In the case of plasma spray coating over the Ti vacuum evaporation thin film, the substrate Ni-Ti alloy could not be better protected. On the contrary, vacuum evaporation of Ti over the porous plasma spray coating layer remarkably improved corrosion protective performance

  9. Current status of DIII-D real-time digital plasma control

    International Nuclear Information System (INIS)

    Penaflor, B.G.; Piglowski, D.A.; Ferron, J.R.; Walker, M.L.

    1999-06-01

    This paper describes the current status of real-time digital plasma control for the DIII-D tokamak. The digital plasma control system (PCS) has been in place at DIII-D since the early 1990s and continues to expand and improve in its capabilities to monitor and control plasma parameters for DIII-D fusion science experiments. The PCs monitors over 200 tokamak parameters from the DIII-D experiment using a real-time data acquisition system that acquires a new set of samples once every 60 micros. This information is then used in a number of feedback control algorithms to compute and control a variety of parameters including those affecting plasma shape and position. A number of system related improvements has improved the usability and flexibility of the DIII-D PCS. These include more graphical user interfaces to assist in entering and viewing the large and ever growing number of parameters controlled by the PCS, increased interaction and accessibility from other DIII-D applications, and upgrades to the computer hardware and vended software. Future plans for the system include possible upgrades of the real-time computers, further links to other DIII-D diagnostic measurements such as real-time Thomson scattering analysis, and joint collaborations with other tokamak experiments including the NSTX at Princeton

  10. Shaping thin film growth and microstructure pathways via plasma and deposition energy: a detailed theoretical, computational and experimental analysis.

    Science.gov (United States)

    Sahu, Bibhuti Bhusan; Han, Jeon Geon; Kersten, Holger

    2017-02-15

    Understanding the science and engineering of thin films using plasma assisted deposition methods with controlled growth and microstructure is a key issue in modern nanotechnology, impacting both fundamental research and technological applications. Different plasma parameters like electrons, ions, radical species and neutrals play a critical role in nucleation and growth and the corresponding film microstructure as well as plasma-induced surface chemistry. The film microstructure is also closely associated with deposition energy which is controlled by electrons, ions, radical species and activated neutrals. The integrated studies on the fundamental physical properties that govern the plasmas seek to determine their structure and modification capabilities under specific experimental conditions. There is a requirement for identification, determination, and quantification of the surface activity of the species in the plasma. Here, we report a detailed study of hydrogenated amorphous and crystalline silicon (c-Si:H) processes to investigate the evolution of plasma parameters using a theoretical model. The deposition processes undertaken using a plasma enhanced chemical vapor deposition method are characterized by a reactive mixture of hydrogen and silane. Later, various contributions of energy fluxes on the substrate are considered and modeled to investigate their role in the growth of the microstructure of the deposited film. Numerous plasma diagnostic tools are used to compare the experimental data with the theoretical results. The film growth and microstructure are evaluated in light of deposition energy flux under different operating conditions.

  11. Effects of pressure profile and plasma shaping on the n=1 internal kink mode in JT-60/JT-60U pellet fuelled plasmas

    International Nuclear Information System (INIS)

    Ozeki, Takahisa; Azumi, Masafumi

    1990-10-01

    The stability of the n=1 internal kink mode in a tokamak is numerically analyzed for plasmas with a centrally peaked pressure profile. These studies are carried out with the strongly peaked pressure inside the q=1 surface, which is based on the experimentally observed plasmas by means of injections of hydrogen-ice pellets in JT-60 tokamak. The effects of peaked pressure and shaping, i.e., elongation and triangularity, are also studied for JT-60U tokamak. The plasma with the strongly peaked pressure profile has higher critical value of poloidal beta defined within the q=1 surface than that with a parabolic pressure profile. Though the beta limit reduces with the increase of the elongation, the plasma with the peaked pressure profile has larger improvement due to the triangularity than that with the parabolic pressure profile. To access the second stability of the n=1 internal kink mode, the plasma with a flat pressure profile and the large minor radius of the q=1 surface is effective. (author)

  12. Method of controlling plasma discharge in a thermonuclear device

    International Nuclear Information System (INIS)

    Kawasaki, Kozo; Ishida, Takayuki; Takemaru, Koichi; Kawasaki, Takahide.

    1982-01-01

    Purpose: To prolong the plasma discharging period by previously increasing the temperature at the thick portion of a vacuum container prior to the plasma discharge to thereby decrease the temperature difference caused by the plasma discharge between the thick portion and the bellows. Method: Temperature values at the outer surface of the thick portion and the bellows of a vacuum container detected by temperature sensors are applied to the input processing section of a temperature control device, and baking control is carried out by way of the output processing section so that each of the portions of the vacuum container may be maintained at the temperature set by the temperature setting section based on the calculation performed in the control processing section. By previously increasing the temperature β at the thick portion higher by about 100 0 C than the temperature α for the bellows in the baking treatment prior to the plasma discharge, the plasma discharge period during which the temperature levels at both of the portions are reversed after the plasma discharge and the temperature difference arrives at a predetermined level i.g., of 100 0 C can significantly be prolonged as compared with the case where the plasma discharge is started at the same temperature for both of the portions. (Yoshino, Y.)

  13. Design and simulation of the surface shape control system for membrane mirror

    Science.gov (United States)

    Zhang, Gengsheng; Tang, Minxue

    2009-11-01

    The surface shape control is one of the key technologies for the manufacture of membrane mirror. This paper presents a design of membrane mirror's surface shape control system on the basis of fuzzy logic control. The system contains such function modules as surface shape design, surface shape control, surface shape analysis, and etc. The system functions are realized by using hybrid programming technology of Visual C# and MATLAB. The finite element method is adopted to simulate the surface shape control of membrane mirror. The finite element analysis model is established through ANSYS Parametric Design Language (APDL). ANSYS software kernel is called by the system in background running mode when doing the simulation. The controller is designed by means of controlling the sag of the mirror's central crosssection. The surface shape of the membrane mirror and its optical aberration are obtained by applying Zernike polynomial fitting. The analysis of surface shape control and the simulation of disturbance response are performed for a membrane mirror with 300mm aperture and F/2.7. The result of the simulation shows that by using the designed control system, the RMS wavefront error of the mirror can reach to 142λ (λ=632.8nm), which is consistent to the surface accuracy of the membrane mirror obtained by the large deformation theory of membrane under the same condition.

  14. Reference data for plasma shaping and magnetic separatrix formation in the JET poloidal field system

    International Nuclear Information System (INIS)

    Lazzaro, E.; Keegan, B.

    1986-01-01

    The analysis and the design of special equilibrium configurations (plasma with separatrix boundary) can be greatly simplified by a chart of the response of the plasma to currents in the poloidal field coils. This note presents this information for some interesting cases, namely for elongated plasmas eventually transformed into double null or in single null separatrix configurations. The calculations are made using the latest edition of the JET equilibrium code ''INVERSX'' including the detailed permeability characteristics of the iron core. (author)

  15. Observation of radio frequency ring-shaped hollow cathode discharge plasma with MgO and Al electrodes for plasma processing

    International Nuclear Information System (INIS)

    Ohtsu, Yasunori; Matsumoto, Naoki

    2014-01-01

    Various high-density plasma sources have been proposed for plasma processing. Especially, the hollow cathode discharge is one of the powerful ones. In this work, radio-frequency (RF) driven ring-shaped hollow cathode discharges with high secondary-electron emission have been investigated, using an aluminum (Al) cathode, coated or not with magnesium oxide (MgO). The thickness of MgO thin film is approximately 200 nm. The RF discharge voltage for the coated cathode is almost the same as that for the uncoated one, in a wide range of Ar gas pressure, from 5.3 to 53.2 Pa. The results reveal that the plasma density has a peak at an Ar gas pressure of 10.6 Pa for both cathodes. The plasma density for the coated cathode is about 1.5–3 times higher than that for the uncoated one, at various gas pressures. To the contrary, the electron temperature for the coated cathode is lower than temperature obtained with the uncoated cathode, at various gas pressures. Radial profiles of electron saturation current, which is proportional to plasma flux, are also examined for a wide range of gas pressure. Radial profiles of electron temperature at various axial positions are almost uniform for both cathodes so that the diffusion process due to density gradient is dominant for plasma transport. The secondary electrons emitted from the coated cathode contribute to the improvement of the plasma flux radial profile obtained using the uncoated cathode

  16. Reactive gas control of non-stable plasma conditions

    International Nuclear Information System (INIS)

    Bellido-Gonzalez, V.; Daniel, B.; Counsell, J.; Monaghan, D.

    2006-01-01

    Most industrial plasma processes are dependant upon the control of plasma properties for repeatable and reliable production. The speed of production and range of properties achieved depend on the degree of control. Process control involves all the aspects of the vacuum equipment, substrate preparation, plasma source condition, power supplies, process drift, valves (inputs/outputs), signal and data processing and the user's understanding and ability. In many cases, some of the processes which involve the manufacturing of interesting coating structures, require a precise control of the process in a reactive environment [S.J. Nadel, P. Greene, 'High rate sputtering technology for throughput and quality', International Glass Review, Issue 3, 2001, p. 45. ]. Commonly in these circumstances the plasma is not stable if all the inputs and outputs of the system were to remain constant. The ideal situation is to move a process from set-point A to B in zero time and maintain the monitored signal with a fluctuation equal to zero. In a 'real' process that's not possible but improvements in the time response and energy delivery could be achieved with an appropriate algorithm structure. In this paper an advanced multichannel reactive plasma gas control system is presented. The new controller offers both high-speed gas control combined with a very flexible control structure. The controller uses plasma emission monitoring, target voltage or any process sensor monitoring as the input into a high-speed control algorithm for gas input. The control algorithm and parameters can be tuned to different process requirements in order to optimize response times

  17. Electron energy distribution function control in gas discharge plasmas

    International Nuclear Information System (INIS)

    Godyak, V. A.

    2013-01-01

    The formation of the electron energy distribution function (EEDF) and electron temperature in low temperature gas discharge plasmas is analyzed in frames of local and non-local electron kinetics. It is shown, that contrary to the local case, typical for plasma in uniform electric field, there is the possibility for EEDF modification, at the condition of non-local electron kinetics in strongly non-uniform electric fields. Such conditions “naturally” occur in some self-organized steady state dc and rf discharge plasmas, and they suggest the variety of artificial methods for EEDF modification. EEDF modification and electron temperature control in non-equilibrium conditions occurring naturally and those stimulated by different kinds of plasma disturbances are illustrated with numerous experiments. The necessary conditions for EEDF modification in gas discharge plasmas are formulated

  18. An advanced plasma control system for the DIII-D tokamak

    International Nuclear Information System (INIS)

    Ferron, J.R.; Kellman, A.; McKee, E.; Osborne, T.; Petrach, P.; Taylor, T.S.; Wight, J.; Lazarus, E.

    1991-11-01

    An advanced plasma control system is being implemented for the DIII-D tokamak utilizing digital technology. This system will regulate the position and shape of tokamak discharges that range from elongated limiter to single-null divertor and double-null divertor with elongation as high as 2.6. Development of this system is expected to lead to control system technology appropriate for use on future tokamaks such as ITER and BPX. The digital system will allow for increased precision in shape control through real time adjustment of the control algorithm to changes in the shape and discharge parameters such as β p , ell i and scrape-off layer current. The system will be used for research on real time optimization of discharge performance for disruption avoidance, current and pressure profile control, optimization of rf antenna loading, or feedback on heat deposition patterns through divertor strike point position control, for example. Shape control with this system is based on linearization near a target shape of the controlled parameters as a function of the magnetic diagnostic signals. This digital system is unique in that it is designed to have the speed necessary to control the unstable vertical motion of highly elongated tokamak discharges such as those produced in DIII-D and planned for BPX and ITER. a 40 MHz Intel i860 processor is interfaced to up to 112 channels of analog input signals. The commands to the poloidal field coils can be updated at 80 μs intervals for the control of vertical position with a delay between sampling of the analog signal and update of the command of less than 80 μs

  19. Plasma impurity-control studies in CTX

    International Nuclear Information System (INIS)

    Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

    1981-01-01

    In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 μs and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 μs. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver

  20. Plasma impurity-control studies in CTX

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

    1981-01-01

    In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 ..mu..s and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 ..mu..s. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver.

  1. Controlling Laser Plasma Instabilities Using Temporal Bandwidth

    Science.gov (United States)

    Tsung, Frank; Weaver, J.; Lehmberg, R.

    2016-10-01

    We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temporal bandwidth under conditions relevant to current and future experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth (where the inverse bandwidth is comparable with the linear growth time), the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using beam smoothing techniques such as ISI). We will quantify these effects and investigate higher dimensional effects such as laser speckles. This work is supported by DOE and NRL.

  2. NARROW LEAF 7 controls leaf shape mediated by auxin in rice

    NARCIS (Netherlands)

    Fujino, Kenji; Matsuda, Yasuyuki; Ozawa, Kenjirou; Nishimura, Takeshi; Koshiba, Tomokazu; Fraaije, Marco W.; Sekiguchi, Hiroshi

    Elucidation of the genetic basis of the control of leaf shape could be of use in the manipulation of crop traits, leading to more stable and increased crop production. To improve our understanding of the process controlling leaf shape, we identified a mutant gene in rice that causes a significant

  3. Automation of Aditya tokamak plasma position control DC power supply

    Energy Technology Data Exchange (ETDEWEB)

    Arambhadiya, Bharat, E-mail: bharat@ipr.res.in; Raj, Harshita; Tanna, R.L.; Edappala, Praveenlal; Rajpal, Rachana; Ghosh, Joydeep; Chattopadhyay, P.K.; Kalal, M.B.

    2016-11-15

    Highlights: • Plasma position control is very essential for obtaining repeatable high temperature, high-density discharges of longer durations in tokomak. • The present capacitor bank has limitations of maximum current capacity and position control beyond 200 ms. • The installation of a separate set of coils and a DC power supply can control the plasma position beyond 200 ms. • A high power thyristor (T588N1200) triggers for DC current pulse of 300 A fires precisely at required positions to modify plasma position. • The commissioning is done for the automated in-house, quick and reliable solution. - Abstract: Plasma position control is essential for obtaining repeatable high temperature, high-density discharges of longer duration in tokamaks. Recently, a set of external coils is installed in the vertical field mode configuration to control the radial plasma position in ADITYA tokamak. The existing capacitor bank cannot provide the required current pulse beyond 200 ms for position control. This motivated to have a DC power supply of 500 A to provide current pulse beyond 200 ms for the position control. The automatization of the DC power supply mandated interfaces with the plasma control system, Aditya Pulse Power supply, and Data acquisition system for coordinated discharge operation. A high current thyristor circuit and a timer circuit have been developed for controlling the power supply automatically for charging vertical field coils of Aditya tokamak. Key protection interlocks implemented in the development ensure machine and occupational safety. Fiber-optic trans-receiver isolates the power supply with other subsystems, while analog channel is optically isolated. Commissioning and testing established proper synchronization of the power supply with tokamak operation. The paper discusses the automation of the DC power supply with main circuit components, timing control, and testing results.

  4. Molecular mechanisms controlling pavement cell shape in Arabidopsis leaves.

    Science.gov (United States)

    Qian, Pingping; Hou, Suiwen; Guo, Guangqin

    2009-08-01

    Pavement cells have an interlocking jigsaw puzzle-shaped leaf surface pattern. Twenty-three genes involved in the pavement cell morphogenesis were discovered until now. The mutations of these genes through various means lead to pavement cell shape defects, such as loss or lack of interdigitation, the reduction of lobing, gaps between lobe and neck regions in pavement cells, and distorted trichomes. These phenotypes are affected by the organization of microtubules and microfilaments. Microtubule bands are considered corresponding with the neck regions of the cell, while lobe formation depends on patches of microfilaments. The pathway of Rho of plant (ROP) GTPase signaling cascades regulates overall activity of the cytoskeleton in pavement cells. Some other proteins, in addition to the ROPs, SCAR/WAVE, and ARP2/3 complexes, are also involved in the pavement cell morphogenesis.

  5. A simple route to shape controlled CdS nanoparticles

    Science.gov (United States)

    Nejo, Ayorinde O.; Nejo, Adeola A.; Pullabhotla, Rajasekhar V. S. R.; Revaprasadu, Neerish

    2013-02-01

    We report the synthesis of CdS nanoparticles in the form of spheres, triangles and wire-like structures. The method involves the reaction of reduced sulfur with a cadmium salt followed by thermolysis in hexadecylamine (HDA). The different shapes were obtained by variation of reaction conditions such as reaction time, temperature and cadmium source. The optical studies show the particles to be quantum confined and luminescent at room temperature.

  6. The design of remote participation platform for EAST plasma control

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Q.P., E-mail: qpyuan@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Xiao, B.J. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); University of Science & Technology of China, Hefei (China); Zhang, R.R. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chai, W.T.; Liu, J.; Xiao, R.; Zhou, Z.C.; Pei, X.F. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); University of Science & Technology of China, Hefei (China)

    2016-11-15

    Highlights: • The remote participation platform for EAST plasma control is composed of real time control service and scenario management. • The web based interface has been developed for supporting remote participation. • The functionality module has been designed and assistant tools have been developed. - Abstract: EAST has become a physics experimental platform for high parameter and steady-state long-pulse plasma operation. A new remote participation platform for EAST plasma control is designed, which is composed of gatekeeper system, web-based user interface system, discharge scenario management system, online simulation system and data interface with on-site plasma control system (PCS). The identification and access privilege of remote participator is validated by the gatekeeper system. Only authorized users can set control parameters for next shot plasma control or making discharge scenario for future shot through WebPCS which is a web-based user interface and designed based on B/S structure. The systematic architecture design and preliminary deployment of such remote platform will be presented in this paper.

  7. Physics and chemistry of plasma pollution control technology

    International Nuclear Information System (INIS)

    Chang, J S

    2008-01-01

    Gaseous pollution control technologies for acid gases (NO x , SO x , etc), volatile organic compounds, greenhouse gases, ozone layer depleting substances, etc have been commercialized based on catalysis, incineration and adsorption methods. However, non-thermal plasma techniques based on electron beams and corona discharges are becoming significant due to advantages such as lower costs, higher removal efficiency and smaller space volume. In order to commercialize this new technology, the pollution gas removal rate, energy efficiency of removal, pressure drop of reactors and useable by-product production rates must be improved and identification of major fundamental processes and optimizations of reactor and power supply for an integrated system must be investigated. In this work, the chemistry and physics of plasma pollution control are discussed and the limitation of this type of plasma is outlined based on the plasma parameters.

  8. Plasma physics and controlled nuclear fusion research 1990. V. 1

    International Nuclear Information System (INIS)

    1991-01-01

    Volume 1 of the Proceedings of the Thirteenth International Conference on Plasma Physics and Controlled Nuclear Fusion Research contains papers given in two of the sessions: A and E. Session A contains the Artsimovich Memorial Lecture and papers on tokamaks; session E papers on plasma heating and current drive. The titles and authors of each paper are listed in the Contents. Abstracts accompany each paper. Refs, figs and tabs

  9. Controlling the emission current from a plasma cathode

    International Nuclear Information System (INIS)

    Bagaev, S.P.; Gushenets, V.I.; Schanin, P.M.

    1993-01-01

    The processes determining the time and amplitude characteristics of the grid-controlled electron emission from the plasma of an arc discharge have been analyzed. It has been shown that by applying to the grid confining the plasma emission boundary of a modulated voltage it is possible to form current pulse of up to 1 kA with nanosecond risetimes and falltimes and a pulse repetitive rate of 100 kHz

  10. Implementation strategy for the ITER plasma control system

    International Nuclear Information System (INIS)

    Winter, A.; Ambrosino, G.; Bauvir, B.; De Tommasi, G.; Humphreys, D.A.; Mattei, M.; Neto, A.; Raupp, G.; Snipes, J.A.; Stephen, A.V.; Treutterer, W.; Walker, M.L.; Zabeo, L.

    2015-01-01

    This paper gives an overview of the scope and context of the CODAC high-level real-time applications (Supervision and Plasma Control) and presents the strategy and current state of design of the tools to support the implementation. A real-time framework, which is currently under development with strong support of the worldwide fusion community will not only support the implementation of plasma control strategies with the extensive exception handling and forecasting functionality foreseen for ITER, but also integrated commissioning, orchestration and supervision as well as the real-time needs of ITER plant system developers. A second cornerstone in the implementation strategy is the development of a powerful simulation environment (Plasma Control System Simulation Platform – PCSSP) to design and verify control strategies, event handling and orchestration and automation. The development of PCSSP is currently under contract and this paper will also give an overview of its current state of development.

  11. Implementation strategy for the ITER plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Winter, A., E-mail: axel.winter@iter.org [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Ambrosino, G. [CREATE/Università di Napoli Federico II, Dip. Ingegneria Elettrica e delle Tecnologie dell’Informazione (Italy); Bauvir, B. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); De Tommasi, G. [CREATE/Università di Napoli Federico II, Dip. Ingegneria Elettrica e delle Tecnologie dell’Informazione (Italy); Humphreys, D.A. [General Atomics, San Diego, CA (United States); Mattei, M. [CREATE/Seconda Università di Napoli, Dip. Ingegneria Industriale e dell’Informazione (Italy); Neto, A. [Fusion for Energy, Barcelona (Spain); Raupp, G. [Max Planck Institute for Plasma Physics, EURATOM Association, Garching (Germany); Snipes, J.A. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Stephen, A.V. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon (United Kingdom); Treutterer, W. [Max Planck Institute for Plasma Physics, EURATOM Association, Garching (Germany); Walker, M.L. [General Atomics, San Diego, CA (United States); Zabeo, L. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France)

    2015-10-15

    This paper gives an overview of the scope and context of the CODAC high-level real-time applications (Supervision and Plasma Control) and presents the strategy and current state of design of the tools to support the implementation. A real-time framework, which is currently under development with strong support of the worldwide fusion community will not only support the implementation of plasma control strategies with the extensive exception handling and forecasting functionality foreseen for ITER, but also integrated commissioning, orchestration and supervision as well as the real-time needs of ITER plant system developers. A second cornerstone in the implementation strategy is the development of a powerful simulation environment (Plasma Control System Simulation Platform – PCSSP) to design and verify control strategies, event handling and orchestration and automation. The development of PCSSP is currently under contract and this paper will also give an overview of its current state of development.

  12. An experimental study of icing control using DBD plasma actuator

    Science.gov (United States)

    Cai, Jinsheng; Tian, Yongqiang; Meng, Xuanshi; Han, Xuzhao; Zhang, Duo; Hu, Haiyang

    2017-08-01

    Ice accretion on aircraft or wind turbine has been widely recognized as a big safety threat in the past decades. This study aims to develop a new approach for icing control using an AC-DBD plasma actuator. The experiments of icing control (i.e., anti-/de-icing) on a cylinder model were conducted in an icing wind tunnel with controlled wind speed (i.e., 15 m/s) and temperature (i.e., -10°C). A digital camera was used to record the dynamic processes of plasma anti-icing and de-icing whilst an infrared imaging system was utilized to map the surface temperature variations during the anti-/de-icing processes. It was found that the AC-DBD plasma actuator is very effective in both anti-icing and de-icing operations. While no ice formation was observed when the plasma actuator served as an anti-icing device, a complete removal of the ice layer with a thickness of 5 mm was achieved by activating the plasma actuator for ˜150 s. Such information demonstrated the feasibility of plasma anti-/de-icing, which could potentially provide more effective and safer icing mitigation strategies.

  13. Control of radial electric field in torus plasma

    International Nuclear Information System (INIS)

    Ida, K.; Idei, H.; Sanuki, H.

    1994-09-01

    The radial electric fields is controlled by changing the direction of neutral beam from co to counter to plasma current in tokamak, while it is controlled by the 2nd harmonic ECH and NBI and pellet injection in heliotron/torsatron. (author)

  14. Control strategy for plasma equilibrium in a tokamak

    International Nuclear Information System (INIS)

    Miskell, R.V.

    1975-08-01

    Dynamic control of the plasma position within the torus of a TOKAMAK fusion device is a significant factor in the development of nuclear fusion as an energy source. This investigation develops a state variable model of a TOKAMAK thermonuclear device, suitable for application of modern control theory techniques. (auth)

  15. Wavefront control performance modeling with WFIRST shaped pupil coronagraph testbed

    Science.gov (United States)

    Zhou, Hanying; Nemati, Bijian; Krist, John; Cady, Eric; Kern, Brian; Poberezhskiy, Ilya

    2017-09-01

    NASA's WFIRST mission includes a coronagraph instrument (CGI) for direct imaging of exoplanets. Significant improvement in CGI model fidelity has been made recently, alongside a testbed high contrast demonstration in a simulated dynamic environment at JPL. We present our modeling method and results of comparisons to testbed's high order wavefront correction performance for the shaped pupil coronagraph. Agreement between model prediction and testbed result at better than a factor of 2 has been consistently achieved in raw contrast (contrast floor, chromaticity, and convergence), and with that comes good agreement in contrast sensitivity to wavefront perturbations and mask lateral shear.

  16. Nonlinear angle control of a sectioned airfoil by using shape memory alloys

    Directory of Open Access Journals (Sweden)

    Abreu G.

    2014-01-01

    Full Text Available The present work illustrates an application of shape memory alloys and nonlinear controller applied to the active angular control of a sectioned airfoil. The main objective of the proposed control system is to modify the shape of the profile based on a reference angle. The change of the sectioned airfoil angle is resultant by the effect of shape memory of the alloy due to heating of the wire caused by an electric current that changes its temperature by Joule effect. Considering the presence of plant’s nonlinear effects, especially in the mathematical model of the alloy, this work proposes the application of an on-off control system.

  17. Preparation of Ni-Ti shape memory alloy by spark plasma sintering method

    Czech Academy of Sciences Publication Activity Database

    Salvetr, P.; Kubatík, Tomáš František; Novák, P.

    2016-01-01

    Roč. 16, č. 4 (2016), s. 804-808 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Ni-Ti alloy * Powder metallurgy * Reactive sintering * Spark plasma sintering Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  18. Jet flow and premixed jet flame control by plasma swirler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang, E-mail: ligang@iet.cn [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Jiang, Xi [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Zhao, Yujun [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Liu, Cunxi [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Qi [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xu, Gang; Liu, Fuqiang [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-04-04

    A swirler based on dielectric barrier discharge plasma actuators is designed and its effectiveness in both jet flow and premixed jet flame control is demonstrated. In contrast to traditional spanwise-oriented actuators, plasma actuators are placed along the axial direction of the injector to induce a circumferential velocity to the main flow and create a swirl flow without any insertion or moving part. In the DBD plasma swirl injector, the discharge does not ignite the mixture nor does it induce flashback. Flame visualization is obtained by cameras while velocity profiles are obtained by Laser Doppler Anemometry measurements. The results obtained indicate the effectiveness of the new design. - Highlights: • The discharge does not ignite the mixture nor does it induce flashback. • The prominent advantage of this novel plasma swirler is its swirl number adjustable without any mechanical movement. • The frequency of the plasma swirler is adjustable. • The plasma swirler can be used as an oscillator to the reactants. • The plasma swirler can be used alone or combine with other traditional swirlers.

  19. Particle-in-cell simulations of plasma interaction with shaped and unshaped gaps in TEXTOR

    Czech Academy of Sciences Publication Activity Database

    Komm, Michael; Dejarnac, Renaud; Gunn, J. P.; Kirschner, A.; Litnovsky, A.; Matveev, D.; Pekarek, Z.

    2011-01-01

    Roč. 53, č. 11 (2011), s. 115004-115004 ISSN 0741-3335 R&D Projects: GA ČR GA202/09/1467 Institutional research plan: CEZ:AV0Z20430508 Keywords : Tokamak * gap * plasma PIC * retention power flux Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.425, year: 2011 http://iopscience.iop.org/0741-3335/53/11/115004/pdf/0741-3335_53_11_115004.pdf

  20. Bluff Body Flow Control Using Dielectric Barrier Discharge Plasma Actuators

    Science.gov (United States)

    Thomas, Flint; Kozlov, Alexey

    2008-11-01

    The results of an experimental investigation involving the use of dielectric barrier discharge plasma actuators to control bluff body flow is presented. The motivation for the work is plasma landing gear noise control for commercial transport aircraft. For these flow control experiments, the cylinder in cross-flow is chosen for study since it represents a generic flow geometry that is similar in all essential aspects to a landing gear strut. The current work is aimed both at extending the plasma flow control concept to Reynolds numbers typical of landing approach and take-off and on the development of optimum plasma actuation strategies. The cylinder wake flow with and without actuation are documented in detail using particle image velocimetry (PIV) and constant temperature hot-wire anemometry. The experiments are performed over a Reynolds number range extending to ReD=10^5. Using either steady or unsteady plasma actuation, it is demonstrated that even at the highest Reynolds number Karman shedding is totally eliminated and turbulence levels in the wake decrease by more than 50%. By minimizing the unsteady flow separation from the cylinder and associated large-scale wake vorticity, the radiated aerodynamic noise is also reduced.

  1. Lithium technologies for edge plasma control

    International Nuclear Information System (INIS)

    Sergeev, Vladimir Yu.; Kuteev, Boris V.; Bykov, Aleksey S.; Krylov, Sergey V.; Skokov, Viacheslav G.; Timokhin, Vladimir M.

    2012-01-01

    Highlights: ► We have investigated two new modes of operation been in T-10 limiter tokamak experiments with a novel rotary feeder of lithium dust. ► The observed decreases of bolometer and D β signals, with increase of the electron density during the lithium dust injection, reveal the effects of the first wall conditioning. ► The lithium technology may provide inherent safety mission for major disruption mitigation in a tokamak reactor, which requires demonstration in contemporary tokamak experiments. - Abstract: We have investigated two new modes of operation been in T-10 limiter tokamak experiments with a novel rotary feeder of lithium dust. Quasi steady-state mode I and pulse mode II of dust delivery were realized in both OH and OH + ECRH disruption free plasmas at the lithium flow rate up to 2 × 10 21 atoms/s. A higher flow rate in mode II with injection rate of ∼5 × 10 21 atoms/s caused a series of minor disruptions, which was completed by discharge termination after the major disruption. The observed decreases of bolometer and D β signals, with increase of the electron density during the lithium dust injection, reveal the effects of the first wall conditioning. The lithium technology may provide inherent safety pathway for major disruption mitigation in a tokamak reactor, which requires demonstration in contemporary tokamak experiments.

  2. Continuous, saturation, and discontinuous tokamak plasma vertical position control systems

    Energy Technology Data Exchange (ETDEWEB)

    Mitrishkin, Yuri V., E-mail: y_mitrishkin@hotmail.com [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow 119991 (Russian Federation); Pavlova, Evgeniia A., E-mail: janerigoler@mail.ru [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow 119991 (Russian Federation); Kuznetsov, Evgenii A., E-mail: ea.kuznetsov@mail.ru [Troitsk Institute for Innovation and Fusion Research, Moscow 142190 (Russian Federation); Gaydamaka, Kirill I., E-mail: k.gaydamaka@gmail.com [V. A. Trapeznikov Institute of Control Sciences of the Russian Academy of Sciences, Moscow 117997 (Russian Federation)

    2016-10-15

    Highlights: • Robust new linear state feedback control system for tokamak plasma vertical position. • Plasma vertical position relay control system with voltage inverter in sliding mode. • Design of full models of multiphase rectifier and voltage inverter. • First-order unit approximation of full multiphase rectifier model with high accuracy. • Wider range of unstable plant parameters of stable control system with multiphase rectifier. - Abstract: This paper is devoted to the design and comparison of unstable plasma vertical position control systems in the T-15 tokamak with the application of two types of actuators: a multiphase thyristor rectifier and a transistor voltage inverter. An unstable dynamic element obtained by the identification of plasma-physical DINA code was used as the plasma model. The simplest static feedback state space control law was synthesized as a linear combination of signals accessible to physical measurements, namely the plasma vertical displacement, the current, and the voltage in a horizontal field coil, to solve the pole placement problem for a closed-loop system. Only one system distinctive parameter was used to optimize the performance of the feedback system, viz., a multiple real pole. A first-order inertial unit was used as the rectifier model in the feedback. A system with a complete rectifier model was investigated as well. A system with the voltage inverter model and static linear controller was brought into a sliding mode. As this takes place, real time delays were taken into account in the discontinuous voltage inverter model. The comparison of the linear and sliding mode systems showed that the linear system enjoyed an essentially wider range of the plant model parameters where the feedback system was stable.

  3. Continuous, saturation, and discontinuous tokamak plasma vertical position control systems

    International Nuclear Information System (INIS)

    Mitrishkin, Yuri V.; Pavlova, Evgeniia A.; Kuznetsov, Evgenii A.; Gaydamaka, Kirill I.

    2016-01-01

    Highlights: • Robust new linear state feedback control system for tokamak plasma vertical position. • Plasma vertical position relay control system with voltage inverter in sliding mode. • Design of full models of multiphase rectifier and voltage inverter. • First-order unit approximation of full multiphase rectifier model with high accuracy. • Wider range of unstable plant parameters of stable control system with multiphase rectifier. - Abstract: This paper is devoted to the design and comparison of unstable plasma vertical position control systems in the T-15 tokamak with the application of two types of actuators: a multiphase thyristor rectifier and a transistor voltage inverter. An unstable dynamic element obtained by the identification of plasma-physical DINA code was used as the plasma model. The simplest static feedback state space control law was synthesized as a linear combination of signals accessible to physical measurements, namely the plasma vertical displacement, the current, and the voltage in a horizontal field coil, to solve the pole placement problem for a closed-loop system. Only one system distinctive parameter was used to optimize the performance of the feedback system, viz., a multiple real pole. A first-order inertial unit was used as the rectifier model in the feedback. A system with a complete rectifier model was investigated as well. A system with the voltage inverter model and static linear controller was brought into a sliding mode. As this takes place, real time delays were taken into account in the discontinuous voltage inverter model. The comparison of the linear and sliding mode systems showed that the linear system enjoyed an essentially wider range of the plant model parameters where the feedback system was stable.

  4. Wing Shaping and Gust Load Controls of Flexible Aircraft: An LPV Approach

    Science.gov (United States)

    Hammerton, Jared R.; Su, Weihua; Zhu, Guoming; Swei, Sean Shan-Min

    2018-01-01

    In the proposed paper, the optimum wing shape of a highly flexible aircraft under varying flight conditions will be controlled by a linear parameter-varying approach. The optimum shape determined under multiple objectives, including flight performance, ride quality, and control effort, will be determined as well. This work is an extension of work done previously by the authors, and updates the existing optimization and utilizes the results to generate a robust flight controller.

  5. Real time plasma control experiments using the JET auxiliary plasma heating systems as the actuator

    International Nuclear Information System (INIS)

    Zornig, N.H.

    1999-01-01

    The role of the Real Time Power Control system (RTPC) in the Joint European Torus (JET) is described in depth. The modes of operation are discussed in detail and a number of successful experiments are described. These experiments prove that RTPC can be used for a wide range of experiments, including: (1) Feedback control of plasma parameters in real time using Ion Cyclotron Resonance Heating (ICRH) or Neutral Beam Heating (NBH) as the actuator in various JET operating regimes. It is demonstrated that in a multi-parameter space it is not sufficient to control one global plasma parameter in order to avoid performance limiting events. (2) Restricting neutron production and subsequent machine activation resulting from high performance pulses. (3) The simulation of α-particle heating effects in a DT-plasma in a D-only plasma. The heating properties of α-particles are simulated using ICRH-power, which is adjusted in real time. The simulation of α-particle heating in JET allows the effects of a change in isotopic mass to be separated from α-particle heating. However, the change in isotopic mass of the plasma ions appears to affect not only the global energy confinement time (τ E ) but also other parameters such as the electron temperature at the plasma edge. This also affects τ E , making it difficult to make a conclusive statement about any isotopic effect. (4) For future JET experiments a scheme has been designed which simulates the behaviour of a fusion reactor experimentally. The design parameters of the International Thermonuclear Experimental Reactor (ITER) are used. In the proposed scheme the most relevant dimensionless plasma parameters are similar in JET and ITER. It is also shown how the amount of heating may be simulated in real time by RTPC using the electron temperature and density as input parameters. The results of two demonstration experiments are presented. (author)

  6. Direct synthesis of nano-sized glass powders with spherical shape by RF (radio frequency) thermal plasma

    International Nuclear Information System (INIS)

    Seo, J.H.; Kim, J.S.; Lee, M.Y.; Ju, W.T.; Nam, I.T.

    2011-01-01

    A new route for obtaining very small, spheroid glass powders is demonstrated using an RF (radio frequency) thermal plasma system. During the process, four kinds of chemicals, here SiO 2 , B 2 O 3 , BaCO 3 , and K 2 CO 3 , were mixed at pre-set weight ratios, spray-dried, calcined at 250 deg. C for 3 h, and crushed into fragments. Then, they were successfully reformed into nano-sized amorphous powders (< 200 nm) with spherical shape by injecting them along the centerline of an RF thermal plasma reactor at ∼ 24 kW. The as-synthesized powders show negligible (< 1%) composition changes when compared with the injected precursors of raw material compounds.

  7. How Life Experience Shapes Cognitive Control Strategies: The Case of Air Traffic Control Training.

    Directory of Open Access Journals (Sweden)

    Sandra Arbula

    Full Text Available Although human flexible behavior relies on cognitive control, it would be implausible to assume that there is only one, general mode of cognitive control strategy adopted by all individuals. For instance, different reliance on proactive versus reactive control strategies could explain inter-individual variability. In particular, specific life experiences, like a highly demanding training for future Air Traffic Controllers (ATCs, could modulate cognitive control functions. A group of ATC trainees and a matched group of university students were tested longitudinally on task-switching and Stroop paradigms that allowed us to measure indices of cognitive control. The results showed that the ATCs, with respect to the control group, had substantially smaller mixing costs during long cue-target intervals (CTI and a reduced Stroop interference effect. However, this advantage was present also prior to the training phase. Being more capable in managing multiple task sets and less distracted by interfering events suggests a more efficient selection and maintenance of task relevant information as an inherent characteristic of the ATC group, associated with proactive control. Critically, the training that the ATCs underwent improved their accuracy in general and reduced response time switching costs during short CTIs only. These results indicate a training-induced change in reactive control, which is described as a transient process in charge of stimulus-driven task detection and resolution. This experience-based enhancement of reactive control strategy denotes how cognitive control and executive functions in general can be shaped by real-life training and underlines the importance of experience in explaining inter-individual variability in cognitive functioning.

  8. How Life Experience Shapes Cognitive Control Strategies: The Case of Air Traffic Control Training.

    Science.gov (United States)

    Arbula, Sandra; Capizzi, Mariagrazia; Lombardo, Nicoletta; Vallesi, Antonino

    2016-01-01

    Although human flexible behavior relies on cognitive control, it would be implausible to assume that there is only one, general mode of cognitive control strategy adopted by all individuals. For instance, different reliance on proactive versus reactive control strategies could explain inter-individual variability. In particular, specific life experiences, like a highly demanding training for future Air Traffic Controllers (ATCs), could modulate cognitive control functions. A group of ATC trainees and a matched group of university students were tested longitudinally on task-switching and Stroop paradigms that allowed us to measure indices of cognitive control. The results showed that the ATCs, with respect to the control group, had substantially smaller mixing costs during long cue-target intervals (CTI) and a reduced Stroop interference effect. However, this advantage was present also prior to the training phase. Being more capable in managing multiple task sets and less distracted by interfering events suggests a more efficient selection and maintenance of task relevant information as an inherent characteristic of the ATC group, associated with proactive control. Critically, the training that the ATCs underwent improved their accuracy in general and reduced response time switching costs during short CTIs only. These results indicate a training-induced change in reactive control, which is described as a transient process in charge of stimulus-driven task detection and resolution. This experience-based enhancement of reactive control strategy denotes how cognitive control and executive functions in general can be shaped by real-life training and underlines the importance of experience in explaining inter-individual variability in cognitive functioning.

  9. Structure of the automatic system for plasma equilibrium position control

    International Nuclear Information System (INIS)

    Gubarev, V.F.; Krivonos, Yu.G.; Samojlenko, Yu.I.; Snegur, A.A.

    1978-01-01

    Considered are the principles of construction of the automatic system for plasma filament equilibrium position control inside the discharge chamber for the installation of a tokamak type. The combined current control system in control winding is suggested. The most powerful subsystem creates current in the control winding according to the program calculated beforehand. This system provides plasma rough equilibrium along the ''big radius''. The subsystem performing the current change in small limits according to the principle of feed-back coupling is provided simultaneously. The stabilization of plasma position is achieved in the discharge chamber. The advantage of construction of such system is in decreasing of the automatic requlator power without lowering the requirements to the accuracy of equilibrium preservation. The subsystem of automatic control of plasma position over the vertical is put into the system. Such an approach to the construction of the automatic control system proves to be correct; it is based on the experience of application of similar devices for some existing thermonuclear plants

  10. Control of Internal Transport Barriers in Magnetically Confined Fusion Plasmas

    Science.gov (United States)

    Panta, Soma; Newman, David; Sanchez, Raul; Terry, Paul

    2016-10-01

    In magnetic confinement fusion devices the best performance often involves some sort of transport barriers to reduce the energy and particle flow from core to edge. Those barriers create gradients in the temperature and density profiles. If gradients in the profiles are too steep that can lead to instabilities and the system collapses. Control of these barriers is therefore an important challenge for fusion devices (burning plasmas). In this work we focus on the dynamics of internal transport barriers. Using a simple 7 field transport model, extensively used for barrier dynamics and control studies, we explore the use of RF heating to control the local gradients and therefore the growth rates and shearing rates for barrier initiation and control in self-heated fusion plasmas. Ion channel barriers can be formed in self-heated plasmas with some NBI heating but electron channel barriers are very sensitive. They can be formed in self-heated plasmas with additional auxiliary heating i.e. NBI and radio-frequency(RF). Using RF heating on both electrons and ions at proper locations, electron channel barriers along with ion channel barriers can be formed and removed demonstrating a control technique. Investigating the role of pellet injection in controlling the barriers is our next goal. Work supported by DOE Grant DE-FG02-04ER54741.

  11. FPGA based Fuzzy Logic Controller for plasma position control in ADITYA Tokamak

    International Nuclear Information System (INIS)

    Suratia, Pooja; Patel, Jigneshkumar; Rajpal, Rachana; Kotia, Sorum; Govindarajan, J.

    2012-01-01

    Highlights: ► Evaluation and comparison of the working performance of FLC is done with that of PID Controller. ► FLC is designed using MATLAB Fuzzy Logic Toolbox, and validated on ADITYA RZIP model. ► FLC was implemented on a FPGA. The close-loop testing is done by interfacing FPGA to MATLAB/Simulink. ► Developed FLC controller is able to maintain the plasma column within required range of ±0.05 m and was found to give robust control against various disturbances and faster and smoother response compared to PID Controller. - Abstract: Tokamaks are the most promising devices for obtaining nuclear fusion energy from high-temperature, ionized gas termed as Plasma. The successful operation of tokamak depends on its ability to confine plasma at the geometric center of vacuum vessel with sufficient stability. The quality of plasma discharge in ADITYA Tokamak is strongly related to the radial position of the plasma column in the vacuum vessel. If the plasma column approaches too near to the wall of vacuum vessel, it leads to minor or complete disruption of plasma. Hence the control of plasma position throughout the entire plasma discharge duration is a fundamental requirement. This paper describes Fuzzy Logic Controller (FLC) which is designed for radial plasma position control. This controller is tested and evaluated on the ADITYA RZIP control model. The performance of this FLC was compared with that of Proportional–Integral–Derivative (PID) Controller and the response was found to be faster and smoother. FLC was implemented on a Field Programmable Gate Array (FPGA) chip with the use of a Very High-Speed Integrated-Circuits Hardware Description-Language (VHDL).

  12. Plasma control using neural network and optical emission spectroscopy

    International Nuclear Information System (INIS)

    Kim, Byungwhan; Bae, Jung Ki; Hong, Wan-Shick

    2005-01-01

    Due to high sensitivity to process parameters, plasma processes should be tightly controlled. For plasma control, a predictive model was constructed using a neural network and optical emission spectroscopy (OES). Principal component analysis (PCA) was used to reduce OES dimensionality. This approach was applied to an oxide plasma etching conducted in a CHF 3 /CF 4 magnetically enhanced reactive ion plasma. The etch process was systematically characterized by means of a statistical experimental design. Three etch outputs (etch rate, profile angle, and etch rate nonuniformity) were modeled using three different approaches, including conventional, OES, and PCA-OES models. For all etch outputs, OES models demonstrated improved predictions over the conventional or PCA-OES models. Compared to conventional models, OES models yielded an improvement of more than 25% in modeling profile angle and etch rate nonuniformtiy. More than 40% improvement over PCA-OES model was achieved in modeling etch rate and profile angle. These results demonstrate that nonreduced in situ data are more beneficial than reduced one in constructing plasma control model

  13. Feedback control of laser welding based on frequency analysis of light emissions and adaptive beam shaping

    Czech Academy of Sciences Publication Activity Database

    Mrňa, Libor; Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr

    2012-01-01

    Roč. 39, NOV (2012), s. 784-791 ISSN 1875-3892. [LANE 2012. Laser Assisted Net Shape Engineering /7./ International Conference on Photonic Technologies. Fürth, 12.11.2012-15.12.2012] Institutional support: RVO:68081731 Keywords : laser welding * feedback control * frequency analysis * adaptive beam shaping Subject RIV: BH - Optics, Masers, Lasers

  14. Development in Diagnostics Application to Control Advanced Tokamak Plasma

    International Nuclear Information System (INIS)

    Koide, Y.

    2008-01-01

    For continuous operation expected in DEMO, all the plasma current must be non-inductively driven, with self-generated neoclassical bootstrap current being maximized. The control of such steady state high performance tokamak plasma (so-called 'Advanced Tokamak Plasma') is a challenge because of the strong coupling between the current density, the pressure profile and MHD stability. In considering diagnostic needs for the advanced tokamak research, diagnostics for MHD are the most fundamental, since discharges which violate the MHD stability criteria either disrupt or have significantly reduced confinement. This report deals with the development in diagnostic application to control advanced tokamak plasma, with emphasized on recent progress in active feedback control of the current profile and the pressure profile under DEMO-relevant high bootstrap-current fraction. In addition, issues in application of the present-day actuators and diagnostics for the advanced control to DEMO will be briefly addressed, where port space for the advanced control may be limited so as to keep sufficient tritium breeding ratio (TBR)

  15. Impulse electron gun with plasma cathode for realization of large diameter tube-shaped beams

    International Nuclear Information System (INIS)

    Antipov, V.S.; Karpukhin, V.I.; Kornilov, E.A.

    1999-01-01

    There are presented the results of investigations of a plasma electron source based on the gas discharge in a coaxial system of electrodes with longitudinal magnetic field. The examination is fulfilled from the viewpoint of applying the source as a plasma cathode for hybrid plasma-waveguide slow-wave structures on the basis of a disk-loaded coaxial. The source is optimized in order to get a powerful (up to 100 kW) nonrelativistic electron beam with the annular cross-section of a large diameter in the regime of relatively long current pulses (up to 0.2 ms) under the gas pressure ∼ 5 centre dot 10 -4 mm Hg in the area of the discharge burning

  16. Shape-controlled porous nanocarbons for high performance supercapacitors

    KAUST Repository

    Ché n, Wěi; Baby, Rakhi Raghavan; Hedhili, Mohamed N.; Alshareef, Husam N.

    2014-01-01

    Porous activated nanocarbons with well-controlled dimensionality and morphology (i.e. 0D activated carbon nanoparticles, 1D activated carbon nanotubes, and 2D activated carbon nanosheets) were derived successfully from different template

  17. Maturing ECRF technology for plasma control

    International Nuclear Information System (INIS)

    Callis, R.W.; .; Cary, W.P.; Chu, S.

    2003-01-01

    The availability of high power, (∼1 MW) long pulse length (effectively cw), high frequency, (>100 GHz) gyrotrons has opened the opportunity for enhanced scientific results on magnetic confinement devices for fusion research worldwide. This has led to successful experiments on electron cyclotron heating, electron cyclotron current drive, non-inductive tokamak operation, tokamak energy transport, suppression of instabilities and advanced profile control leading to enhanced performance. The key development in the gyrotron community that has led to the realization of high power long pulse gyrotrons is the availability of edge cooled synthetic diamond gyrotron output windows, which have low loss and excellent thermal and mechanical properties. In addition to the emergence of reliable high power gyrotrons, ancillary equipment for efficient microwave transmission over distances of hundreds of meters, polarization control, diagnostics, and flexible launch geometry have all been developed and proven in regular service. (author)

  18. Controlling plasma distributions as driving forces for ion migration during fs laser writing

    International Nuclear Information System (INIS)

    Fernandez, Toney Teddy; Siegel, Jan; Hoyo, Jesus; Solis, Javier; Sotillo, Belen; Fernandez, Paloma

    2015-01-01

    The properties of structures written inside dielectrics with high repetition rate femtosecond lasers are known to depend strongly on the complex interplay of a large number of writing parameters. Recently, ion migration within the laser-excited volume has been identified as a powerful mechanism for changing the local element distribution and producing efficient optical waveguides. In this work it is shown that the transient plasma distribution induced during laser irradiation is a reliable monitor for predicting the final refractive index distribution of the waveguide caused by ion migration. By performing in situ plasma emission microscopy during the writing process inside a La-phosphate glass it is found that the long axis of the plasma distribution determines the axis of ion migration, being responsible for the local refractive index increase. This observation is also valid when strong positive or negative spherical aberration is induced, greatly deforming the focal volume and inverting the index profile. Even subtle changes in the writing conditions, such as an inversion of the writing direction (quill writing effect), show up in the form of a modified plasma distribution, which manifests as a modified index distribution. Finally, it is shown that the superior control over the waveguide properties employing the slit shaping technique is caused by the more confined plasma distribution produced. The underlying reasons for this unexpected result are discussed in terms of non-linear propagation and heat accumulation. (paper)

  19. Controlling plasma distributions as driving forces for ion migration during fs laser writing

    Science.gov (United States)

    Teddy Fernandez, Toney; Siegel, Jan; Hoyo, Jesus; Sotillo, Belen; Fernandez, Paloma; Solis, Javier

    2015-04-01

    The properties of structures written inside dielectrics with high repetition rate femtosecond lasers are known to depend strongly on the complex interplay of a large number of writing parameters. Recently, ion migration within the laser-excited volume has been identified as a powerful mechanism for changing the local element distribution and producing efficient optical waveguides. In this work it is shown that the transient plasma distribution induced during laser irradiation is a reliable monitor for predicting the final refractive index distribution of the waveguide caused by ion migration. By performing in situ plasma emission microscopy during the writing process inside a La-phosphate glass it is found that the long axis of the plasma distribution determines the axis of ion migration, being responsible for the local refractive index increase. This observation is also valid when strong positive or negative spherical aberration is induced, greatly deforming the focal volume and inverting the index profile. Even subtle changes in the writing conditions, such as an inversion of the writing direction (quill writing effect), show up in the form of a modified plasma distribution, which manifests as a modified index distribution. Finally, it is shown that the superior control over the waveguide properties employing the slit shaping technique is caused by the more confined plasma distribution produced. The underlying reasons for this unexpected result are discussed in terms of non-linear propagation and heat accumulation.

  20. Wind turbine model and loop shaping controller design

    Science.gov (United States)

    Gilev, Bogdan

    2017-12-01

    A model of a wind turbine is evaluated, consisting of: wind speed model, mechanical and electrical model of generator and tower oscillation model. Model of the whole system is linearized around of a nominal point. By using the linear model with uncertainties is synthesized a uncertain model. By using the uncertain model is developed a H∞ controller, which provide mode of stabilizing the rotor frequency and damping the tower oscillations. Finally is simulated work of nonlinear system and H∞ controller.

  1. Reactor fuel reliability constraints on power shape control

    International Nuclear Information System (INIS)

    Gelhaus, F.; Hallam, J.; Sauar, T.

    1977-01-01

    The level of reliability of fuel rods operating in commercial nuclear power plants has been less than desired for a number of reasons. Several of these causes have been successfully minimized, but pellet-clad interaction failures persist. Since power and power change are dominant parameters in this failure mode, restrictions on operational maneuvers have been recommended by all U. S. fuel suppliers. Slower-than-design allowable maneuvers decrease the plant capacity factor, which can cost a utility up to $7 million per year per plant. To assist utility engineering and operations personnel in their day-to-day decisions in this regard, the Electric Power Research Institute (EPRI) is initiating a project, designated RP895, to develop a fully computerized Power Shape Monitoring System (PSMS) for core-wide fuel rod reliability prediction. This paper describes the PSMS system and details some of the hardware/software requirements as they are now perceived. Salient results from a just-completed complementary EPRI-funded study, RP509, are described; this effort employed hand data acquisition and many man-machine interfaces that will be fully integrated and automated in the PSMS. The capabilities of the PSMS will derive from the use of modern minicomputer hardware and software and from accurate computational modules that enable near-real-time predictive capability

  2. Current control for magnetized plasma in direct-current plasma-immersion ion implantation

    International Nuclear Information System (INIS)

    Tang Deli; Chu, Paul K.

    2003-01-01

    A method to control the ion current in direct-current plasma-immersion ion implantation (PIII) is reported for low-pressure magnetized inductively coupled plasma. The ion current can be conveniently adjusted by applying bias voltage to the conducting grid that separates plasma formation and implantation (ion acceleration) zones without the need to alter the rf input power, gas flux, or other operating conditions. The ion current that diminishes with an increase in grid bias in magnetized plasmas can be varied from 48 to 1 mA by increasing the grid voltage from 0 to 70 V at -50 kV sample bias and 0.5 mTorr hydrogen pressure. High implantation voltage and monoenergetic immersion implantation can now be achieved by controlling the ion current without varying the macroscopic plasma parameters. The experimental results and interpretation of the effects are presented in this letter. This technique is very attractive for PIII of planar samples that require on-the-fly adjustment of the implantation current at high implantation voltage but low substrate temperature. In some applications such as hydrogen PIII-ion cut, it may obviate the need for complicated sample cooling devices that must work at high voltage

  3. CREATE-NL+: A robust control-oriented free boundary dynamic plasma equilibrium solver

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, R. [Ass. EURATOM/ENEA/CREATE, Universita’ di Napoli “Federico II”, Naples (Italy); Ambrosino, R. [Ass. EURATOM/ENEA/CREATE, Universita’ di Napoli “Parthenope”, Naples (Italy); Mattei, M., E-mail: massimiliano.mattei@unina2.it [Ass. EURATOM/ENEA/CREATE, Seconda Universita’ di Napoli, Naples (Italy)

    2015-10-15

    CREATE-NL+ is a FEM (Finite Elements Method) solver of the free boundary dynamic plasma equilibrium problem, i.e. the MHD (Magneto Hydro Dynamics) time evolution of 2D axisymmetric plasmas in toroidal nuclear fusion devices, including eddy currents in the passive structures, and feedback control laws for current, position and shape control. This is an improved version of the CREATE-NL code developed in 2002 which was validated on JET and used for the design of the XSC (eXtreme Shape Controller), and for simulation studies on many existing and future tokamaks. A significant improvement was the use of a robust numerical scheme for the calculation of the Jacobian matrix within the Newton based scheme for the solution of the FEM nonlinear algebraic equations. The improved capability of interfacing with other codes, and a general decrease of the computational burden for the simulation of long pulses with small time steps makes this code a flexible tool for the design and testing of magnetic control in a tokamak.

  4. CREATE-NL+: A robust control-oriented free boundary dynamic plasma equilibrium solver

    International Nuclear Information System (INIS)

    Albanese, R.; Ambrosino, R.; Mattei, M.

    2015-01-01

    CREATE-NL+ is a FEM (Finite Elements Method) solver of the free boundary dynamic plasma equilibrium problem, i.e. the MHD (Magneto Hydro Dynamics) time evolution of 2D axisymmetric plasmas in toroidal nuclear fusion devices, including eddy currents in the passive structures, and feedback control laws for current, position and shape control. This is an improved version of the CREATE-NL code developed in 2002 which was validated on JET and used for the design of the XSC (eXtreme Shape Controller), and for simulation studies on many existing and future tokamaks. A significant improvement was the use of a robust numerical scheme for the calculation of the Jacobian matrix within the Newton based scheme for the solution of the FEM nonlinear algebraic equations. The improved capability of interfacing with other codes, and a general decrease of the computational burden for the simulation of long pulses with small time steps makes this code a flexible tool for the design and testing of magnetic control in a tokamak.

  5. Edge plasma control using an LID configuration on CHS

    Energy Technology Data Exchange (ETDEWEB)

    Masuzaki, S.; Komori, A.; Morisaki, T. [National Inst. for Fusion Science, Oroshi, Toki (Japan)] [and others

    1997-07-01

    A Local Island Divertor (LID) has been proposed to enhance energy confinement through neutral particle control. For the case of the Large Helical Device (LHD), the separatrix of an m/n = 1/1 magnetic island, formed at the edge region, will be utilized as a divertor configuration. The divertor head is inserted in the island, and the island separatrix provides connection between the edge plasma region surrounding the core plasma and the back plate of the divertor head through the field lines. The particle flux and associated heat flux from the core plasma strike the back plate of the divertor head, and thus particle recycling is localized in this region. A pumping duct covers the divertor head to form a closed divertor system for efficient particle exhaust. The advantages of the LID are ease of hydrogen pumping because of the localized particle recycling and avoidance of the high heat load that would be localized on the leading edge of the divertor head. With efficient pumping, the neutral pressure in the edge plasma region will be reduced, and hence the edge plasma temperature will be higher, hopefully leading to a better core confinement region. A LID configuration experiment was done on the Compact Helical System (CHS) to confirm the effect of the LID. The typical effects of the LID configuration on the core plasma are reduction of the line averaged density to a half, and small or no reduction of the stored energy. In this contribution, the experimental results which were obtained in edge plasma control experiments with the LID configuration in the CHS are presented.

  6. Control, pressure perturbations, displacements, and disruptions in highly elongated tokamak plasmas

    International Nuclear Information System (INIS)

    Marcus, F.B.; Hofmann, F.; Tonetti, G.; Jardin, S.C.; Noll, P.

    1989-06-01

    The control and evolution of highly elongated tokamak plasmas with large growth rates are simulated with the axisymmetric, resistive MHD code TSC in the geometry of the TCV tokamak. Pressure perturbations such as sawteeth and externally programmed displacements create initial velocity perturbations which may be stabilized by low power, rapid response coils inside the passively stabilizing vacuum vessel, together with slower shaping coils outside the vessel. Vertical disruption induced voltages and forces on the rapid coils and vessel are investigated, and a model is proposed for an additional vertical force due to poloidal currents. (author) 6 figs., 1 tab., 26 refs

  7. Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

    Science.gov (United States)

    Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

    2013-12-01

    Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

  8. Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

    Science.gov (United States)

    Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

    2013-01-01

    Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications. PMID:24346481

  9. Ignition and burn control characteristics of thermonuclear plasmas

    International Nuclear Information System (INIS)

    Chaniotakis, E.A.

    1990-01-01

    Achieving the long sought goal of fusion energy requires the attainment of an ignited and controlled thermonuclear plasma. Obtaining an ignited plasma in a tokamak device requires consideration of both the physics of the plasma and the engineering of the machine. With the aide of completely analytical procedure optimized and ignited tokamaks are obtained under various physics assumptions. These designs show the possible advantage of tokamaks characterized by high (∼4.5) aspect ratio, and high (∼15 T) toroidal magnetic field. The control of an ignited plasma is investigated by using auxiliary power modulation. With auxiliary power stable operating points can be created with Q ∼50. Recognizing the need for a fast 1 1/2-D transport model for studying profile effects the plasma transport equations are solved using variational methods. A computer model based on the variational method has been developed. This model solves the 1 1/2-D transport equation very fast with little loss of accuracy. 74 refs., 70 figs., 8 tabs

  10. NR4.00002: Response of a laminar M-shaped premixed flame to plasma forcing

    KAUST Repository

    Lacoste, Deanna A.; Moeck, Jonas P.; Cha, Min; Chung, Suk-Ho

    2015-01-01

    We report on the response of a lean methane-air flame to non-thermal plasma forcing. The set-up consists of an axisymmetric burner, with a nozzle made of a quartz tube of 7-mm inlet diameter. The equivalence ratio is 0.9 and the flame is stabilized

  11. Control strategy for plasma equilibrium in a tokamak

    International Nuclear Information System (INIS)

    Miskell, R.V.

    1975-01-01

    The dynamic control of the plasma position within the torus of a Tokamak fusion device is a significant factor in the development of nuclear fusion as an energy source. This investigation develops a state variable model of a TOKAMAK thermonuclear device, suitable for application of modern control theory techniques. The model considers eddy currents in the conducting shell surrounding the torus and the classical Shafranov equilibrium equation. The equations necessary to characterize the operating conditions of a TOKAMAK are cast in state variable form. Two control variables are selected, the vertical field current and the plasma temperature. The figure of merit chosen minimizes the shift of the plasma within the torus and considers position perturbations necessary to maintain the dense and hotter portions of the plasma profile in the center of the torus, i.e., overcome uneven poloidal fields due to the toroidal geometry. The model uses a Kalman filter to estimate unmeasured state variables, and uses the second variation of the calculus of variations to maintain an optimal control path. (Diss. Abstr. Int., B)

  12. Control and metrology of high harmonic generation on plasma mirrors

    International Nuclear Information System (INIS)

    Monchoce, Sylvain

    2014-01-01

    When an ultra intense femtosecond laser with high contrast is focused on a solid target, the laser field at focus is sufficient enough to completely ionize the target surface during the rising edge of the laser pulse and form a plasma. This dense plasma entirely reflects the incident beam in the specular direction: this is a so-called plasma mirror. As the interaction between the laser and the plasma mirror is highly non-linear, it thus leads to the high harmonic generation (HHG) in the reflected beam. In the temporal domain, this harmonic spectrum is associated to a train of atto-second pulses. The aim of my PhD were to experimentally control this HHG and to measure the properties of the harmonics. We first studied the optimization of the harmonic signal, and then the spatial characterization of the harmonic beam in the far-field (harmonic divergence). These characterizations are not only important to develop an intense XUV/atto-second light source, but also to get a better understanding of the laser-matter interaction at very high intensity. We have thus been able to get crucial information of the electrons and ions dynamics of the plasma, showing that the harmonics can also be used as a diagnostic of the laser-plasma interaction. We then developed a new general approach for optically-controlled spatial structuring of overdense plasmas generated at the surface of initially plain solid targets. We demonstrate it experimentally by creating sinusoidal plasma gratings of adjustable spatial periodicity and depth, and study the interaction of these transient structures with an ultra-intense laser pulse to establish their usability at relativistically high intensities. We then show how these gratings can be used as a 'spatial ruler' to determine the source size of the high-order harmonic beams produced at the surface of an overdense plasma. These results open new directions both for the metrology of laser-plasma interactions and the emerging field of ultrahigh

  13. Control of Vibration in Mechanical Systems Using Shaped Reference Inputs

    Science.gov (United States)

    1988-01-01

    damping with several discrete actuators. Burke and Hubbard 34! generated a distributed control law by applying a piezoelectric film to the beam that...setpoints from successive memory locations. DATA-kYOVE (- starts servoing to setpoints from successive memory locations for mnicro scified by MN while taking

  14. Method of shaping fields of controlled extension in a resonator with a large electrical length

    International Nuclear Information System (INIS)

    Bomko, V.A.; Rudiak, B.I.

    A method is discussed for controlling the energy of particles accelerated in a linear accelerator consisting of a volume resonator with drift tubes. Results are described for experimental studies of problems with field shaping of controlled extension of fields in an accelerating structure having drift tubes and a large electrical length. The possibility of shaping the field in a resonator using a stabilizing system of the ''antipode'' type is considered

  15. Signal shape registration in the JINR synchrophasotron slowly extracted beam parameter control system

    International Nuclear Information System (INIS)

    Volkov, V.I.; Kulikov, I.I.; Romanov, S.V.

    1982-01-01

    Signal shape registration in the JINR synchrophasotron slowly estracted beam parameter control system on-line with the ES-1010 computer is described. 32 input signals can be connected to the registrator. The maximum measurement rate of signal shape registration is about 38 kHz. The registrator consists of 32-channel analog multiplexer, 10-bit analog-to-digital converter, 1024-word buffer memory and control circuits. For information representation the colour TV monitor is used

  16. Experimental validation of a Lyapunov-based controller for the plasma safety factor and plasma pressure in the TCV tokamak

    Science.gov (United States)

    Mavkov, B.; Witrant, E.; Prieur, C.; Maljaars, E.; Felici, F.; Sauter, O.; the TCV-Team

    2018-05-01

    In this paper, model-based closed-loop algorithms are derived for distributed control of the inverse of the safety factor profile and the plasma pressure parameter β of the TCV tokamak. The simultaneous control of the two plasma quantities is performed by combining two different control methods. The control design of the plasma safety factor is based on an infinite-dimensional setting using Lyapunov analysis for partial differential equations, while the control of the plasma pressure parameter is designed using control techniques for single-input and single-output systems. The performance and robustness of the proposed controller is analyzed in simulations using the fast plasma transport simulator RAPTOR. The control is then implemented and tested in experiments in TCV L-mode discharges using the RAPTOR model predicted estimates for the q-profile. The distributed control in TCV is performed using one co-current and one counter-current electron cyclotron heating actuation.

  17. The magnetic field application for the gas discharge plasma control in processes of surface coating and modification

    International Nuclear Information System (INIS)

    Asadullin, T Ya; Galeev, I G

    2017-01-01

    In this paper the method of magnetic field application to control the gas discharge plasma effect on the various surfaces in processes of surface coating and modification is considered. The magnetic field directed perpendicular to the direction of electric current in the gas discharge plasma channel is capable to reject this plasma channel due to action of Lorentz force on the moving electrically charged particles [1,2]. The three-dimensional spatial structure of magnetic field is created by system of necessary quantity of the magnets located perpendicular to the direction of course of electric current in the gas-discharge plasma channel. The formation of necessary spatial distribution of magnetic field makes possible to obtain a required distribution of plasma parameters near the processed surfaces. This way of the plasma channel parameters spatial distribution management is the most suitable for application in processes of plasma impact on a surface of irregular shape and in cases when the selective impact of plasma on a part of a surface of a product is required. It is necessary to apply automated computer management of the process parameters [3] to the most effective plasma impact. (paper)

  18. Diacylglycerol Kinases: Shaping Diacylglycerol and Phosphatidic Acid Gradients to Control Cell Polarity

    Directory of Open Access Journals (Sweden)

    Gianluca Baldanzi

    2016-11-01

    Full Text Available Diacylglycerol kinases (DGKs terminate diacylglycerol (DAG signaling and promote phosphatidic acid (PA production. Isoform specific regulation of DGKs activity and localization allows DGKs to shape the DAG and PA gradients. The capacity of DGKs to constrain the areas of DAG signaling is exemplified by their role in defining the contact interface between T cells and antigen presenting cells: the immune synapse. Upon T cell receptor engagement, both DGK α and ζ metabolize DAG at the immune synapse thus constraining DAG signaling. Interestingly, their activity and localization are not fully redundant because DGKζ activity metabolizes the bulk of DAG in the cell, whereas DGKα limits the DAG signaling area localizing specifically at the periphery of the immune synapse.When DGKs terminate DAG signaling, the local PA production defines a new signaling domain, where PA recruits and activates a second wave of effector proteins. The best-characterized example is the role of DGKs in protrusion elongation and cell migration. Indeed, upon growth factor stimulation, several DGK isoforms, such as α, ζ, and γ, are recruited and activated at the plasma membrane. Here, local PA production controls cell migration by finely modulating cytoskeletal remodeling and integrin recycling. Interestingly, DGK-produced PA also controls the localization and activity of key players in cell polarity such as aPKC, Par3, and integrin β1. Thus, T cell polarization and directional migration may be just two instances of the general contribution of DGKs to the definition of cell polarity by local specification of membrane identity signaling.

  19. New achievements in the EAST plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Q.P., E-mail: qpyuan@ipp.ac.c [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Xiao, B.J. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Penaflor, B.G.; Piglowski, D.A. [General Atomics, DIII-D National Fusion Facility, San Diego, CA (United States); Liu, L.Z. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Johnson, R.D.; Walker, M.L.; Humphreys, D.A. [General Atomics, DIII-D National Fusion Facility, San Diego, CA (United States)

    2010-07-15

    In order to realize the low latency and distortion-free signal transmission between the plasma control system (PCS) and servo systems, the digital output structure configured with reflective memory board (RFM) was adopted in EAST PCS. And the enhanced performances are reported. Another achievement made in the latest EAST PCS was the implementation of density control algorithm, which controlled the line average density in either voltage or width modulation mode. The new integrated algorithm improved the precision of density calculation and control performance greatly. The details and experiment results are presented in this paper.

  20. Line width and line shape analysis in the inductively coupled plasma by high resolution Fourier transform spectrometry

    International Nuclear Information System (INIS)

    Faires, L.M.; Palmer, B.A.; Brault, J.W.

    1984-01-01

    High resolution Fourier transform spectrometry has been used to perform line width and line shape analysis of eighty-one iron I emision lines in the spectral range 290 to 390nm originating in the normal analytical zone of an inductively coupled plasma. Computer programs using non-linear least squares fitting techniques for line shape analysis were applied to the fully resolved spectra to determine Gaussian and Lorentzian components of the total observed line width. The effect of noise in the spectrum on the precision of the line fitting technique was assessed, and the importance of signal to noise ratio for line shape analysis is discussed. Translational (Doppler) temperatures were calculated from the Gaussian components of the line width and were found to be on the order of 6300 0 K. The excitation temperature of iron I was also determined from the same spectral data by the spectroscopic slope method based on the Einstein-Boltzmann expression for spectral intensity and was found to be on the order of 4700 0 K. 31 references

  1. Remote network control plasma diagnostic system for Tokamak T-10

    International Nuclear Information System (INIS)

    Troynov, V I; Zimin, A M; Krupin, V A; Notkin, G E; Nurgaliev, M R

    2016-01-01

    The parameters of molecular plasma in closed magnetic trap is studied in this paper. Using the system of molecular diagnostics, which was designed by the authors on the «Tokamak T-10» facility, the radiation of hydrogen isotopes at the plasma edge is investigated. The scheme of optical radiation registration within visible spectrum is described. For visualization, identification and processing of registered molecular spectra a new software is developed using MatLab environment. The software also includes electronic atlas of electronic-vibrational-rotational transitions for molecules of protium and deuterium. To register radiation from limiter cross-section a network control system is designed using the means of the Internet/Intranet. Remote control system diagram and methods are given. The examples of web-interfaces for working out equipment control scenarios and viewing of results are provided. After test run in Intranet, the remote diagnostic system will be accessible through Internet. (paper)

  2. Optimal control of tokamak and stellarator plasma behaviour

    International Nuclear Information System (INIS)

    Rastovic, Danilo

    2007-01-01

    The control of plasma transport, laminar and turbulent, is investigated, using the methods of scaling, optimal control and adaptive Monte Carlo simulations. For this purpose, the asymptotic behaviour of kinetic equation is considered in order to obtain finite-dimensional invariant manifolds, and in this way the finite-dimensional theory of control can be applied. We imagine the labyrinth of open doors and after applying self-similarity, the motion moved through all the desired doors in repeatable ways as Brownian motions. We take local actions for each piece of contractive ergodic motion, and, after self-organization in adaptive invariant measures, the optimum movement of particles is obtained according to the principle of maximum entropy. This is true for deterministic and stochastic cases that serve as models for plasma dynamics

  3. Real-time communication for distributed plasma control systems

    Energy Technology Data Exchange (ETDEWEB)

    Luchetta, A. [Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Corso Stati Uniti 4, Padova 35127 (Italy)], E-mail: adriano.luchetta@igi.cnr.it; Barbalace, A.; Manduchi, G.; Soppelsa, A.; Taliercio, C. [Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Corso Stati Uniti 4, Padova 35127 (Italy)

    2008-04-15

    Real-time control applications will benefit in the near future from the enhanced performance provided by multi-core processor architectures. Nevertheless real-time communication will continue to be critical in distributed plasma control systems where the plant under control typically is distributed over a wide area. At RFX-mod real-time communication is crucial for hard real-time plasma control, due to the distributed architecture of the system, which consists of several VMEbus stations. The system runs under VxWorks and uses Gigabit Ethernet for sub-millisecond real-time communication. To optimize communication in the system, a set of detailed measurements has been carried out on the target platforms (Motorola MVME5100 and MVME5500) using either the VxWorks User Datagram Protocol (UDP) stack or raw communication based on the data link layer. Measurements have been carried out also under Linux, using its UDP stack or, in alternative, RTnet, an open source hard real-time network protocol stack. RTnet runs under Xenomai or RTAI, two popular real-time extensions based on the Linux kernel. The paper reports on the measurements carried out and compares the results, showing that the performance obtained by using open source code is suitable for sub-millisecond real-time communication in plasma control.

  4. Augmentation and Control of Burn Rates in Plasma Devices

    National Research Council Canada - National Science Library

    Bourham, Mohamed

    1999-01-01

    Interaction of electrothermal plasmas with solid propellants necessitates thorough understanding of plasma-propellant interface physics, momentum and energy transfer, plasma flow regimes, and mixing processes...

  5. Interprocess communication within the DIII-D plasma control system

    International Nuclear Information System (INIS)

    Piglowski, D.A.; Penaflor, B.G.; Ferron, J.R.

    1999-06-01

    The DIII-D tokamak fusion research experiment's real-time digital plasma control system (PCS) is a complex and ever evolving system. During a plasma experiment, it is tasked with some of the most crucial functions at DIII-D. Key responsibilities of the PCS involve sub-system control, data acquisition/storage, and user interface. To accomplish these functions, the PCS is broken down into individual components (both software and hardware), each capable of handling a specific duty set. Constant interaction between these components is necessary prior, during and after a standard plasma cycle. Complicating the matter even more is that some components, mostly those which deal with user interaction, may exist remotely, that is to say they are not part of the immediate hardware which makes up the bulk of the PCS. The four main objectives of this paper are to (1) present a brief outline of the PCS hardware/software and how they relate to each other; (2) present a brief overview of a standard DIII-D plasma cycle (a shot); (3) using three sets of PCS sub-systems, describe in more detail the communication processes; and (4) evaluate the benefits and drawbacks of said systems

  6. Dielectric barrier discharge plasma actuator for flow control

    Science.gov (United States)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  7. Plasma position and current control system enhancements for the JET ITER-like wall

    Energy Technology Data Exchange (ETDEWEB)

    De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Univ. di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); Neto, A.C. [Ass. EURATOM-IST, Instituto de Plasmas e Fusão Nuclear, IST, 1049-001 Lisboa (Portugal); Lomas, P.J.; McCullen, P.; Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom)

    2014-03-15

    Highlights: • JET plasma position and current control system enhanced for the JET ITER like wall. • Vertical stabilization system enhanced to speed up its response and to withstand larger perturbations. • Improved termination management system. • Implementation of the current limit avoidance system. • Implementation of PFX-on-early-task. - Abstract: The upgrade of Joint European Torus (JET) to a new all-metal wall, the so-called ITER-like wall (ILW), has posed a set of new challenges regarding both machine operation and protection. The plasma position and current control (PPCC) system plays a crucial role in minimizing the possibility that the plasma could permanently damage the ILW. The installation of the ILW has driven a number of upgrades of the two PPCC components, namely the Vertical Stabilization (VS) system and the Shape Controller (SC). The VS system has been enhanced in order to speed up its response and to withstand larger perturbations. The SC upgrade includes three new features: an improved termination management system, the current limit avoidance system, and the PFX-on-early-task. This paper describes the PPCC upgrades listed above, focusing on the implementation issues and on the experimental results achieved during the 2011–12 JET experimental campaigns.

  8. Control of ITBs in Magnetically Confined Burning Plasmas

    Science.gov (United States)

    Panta, S. R.; Newman, D. E.; Terry, P. W.; Sanchez, R.

    2017-10-01

    In the magnetically confined burning plasma devices (in this case Tokamaks), internal transport barriers (ITBs) are those regimes in which the turbulence is suppressed by the E X B velocity shear, reducing the turbulent transport. This often occurs at a critical gradient in the profiles. The change in the transport then modifies the density and temperature profiles feeding back on the system. These transport barriers have to be controlled both to form them for improved confinement and remove them to both prevent global instabilities and to remove the ash and unnecessary impurities in the device. In this work we focus on pellet injection and modulated RF heating as a way to trigger and control the ITBs. These have an immediate consequence on density and temperature and hence pressure profiles acting as a control knob. For example, depending upon pellet size and its radial position of injection, it either helps to form or strengthen the barrier or to get rid of ITBs in the different transport channels of the burning plasmas. This transport model is then used to investigate the control and dynamics of the transport barriers in burning plasmas using pellets and RF addition to the NBI power and alpha power.

  9. The JET PCU project: An international plasma control project

    International Nuclear Information System (INIS)

    Sartori, F.; Crisanti, F.; Albanese, R.; Ambrosino, G.; Toigo, V.; Hay, J.; Lomas, P.; Rimini, F.; Shaw, S.R.; Luchetta, A.; Sousa, J.; Portone, A.; Bonicelli, T.; Ariola, M.; Artaserse, G.; Bigi, M.; Card, P.; Cavinato, M.; De Tommasi, G.; Gaio, E.

    2008-01-01

    This paper describes the new JET enhancement project 'Plasma Control Upgrade' (PCU). Initially aimed at an overhaul of JET plasma control capabilities it was eventually focused on improving the vertical stabilisation (VS) system ability to recover from large ELM (edge localised mode) perturbations. The paper describes the results of the first two years where the activity was aimed principally at researching a solution that could be implemented within the timing and budget constraints. A very important task was that of improving the modelling of JET plasma, iron core and passive structures. Using dedicated experiments, the models were progressively refined until it was possible not just to explain the experimental data but predict the VS system behaviour. At the same time the project team studied the best options for power supply (PS) and control system upgrades and evaluated whether a change of turns in the stabilisation coil was desirable and possible. A new fast radial field power supply is now being ordered and the VS control system is being upgraded

  10. Experimental Investigation on Airfoil Shock Control by Plasma Aerodynamic Actuation

    International Nuclear Information System (INIS)

    Sun Quan; Cheng Bangqin; Li Yinghong; Cui Wei; Jin Di; Li Jun

    2013-01-01

    An experimental investigation on airfoil (NACA64—215) shock control is performed by plasma aerodynamic actuation in a supersonic tunnel (Ma = 2). The results of schlieren and pressure measurement show that when plasma aerodynamic actuation is applied, the position moves forward and the intensity of shock at the head of the airfoil weakens. With the increase in actuating voltage, the total pressure measured at the head of the airfoil increases, which means that the shock intensity decreases and the control effect increases. The best actuation effect is caused by upwind-direction actuation with a magnetic field, and then downwind-direction actuation with a magnetic field, while the control effect of aerodynamic actuation without a magnetic field is the most inconspicuous. The mean intensity of the normal shock at the head of the airfoil is relatively decreased by 16.33%, and the normal shock intensity is relatively reduced by 27.5% when 1000 V actuating voltage and upwind-direction actuation are applied with a magnetic field. This paper theoretically analyzes the Joule heating effect generated by DC discharge and the Lorentz force effect caused by the magnetic field. The discharge characteristics are compared for all kinds of actuation conditions to reveal the mechanism of shock control by plasma aerodynamic actuation

  11. Stability and Control of Burning Tokamak Plasmas with Resistive Walls: Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Miller, George [Univ. of Tulsa, OK (United States); Brennan, Dylan [Princeton Univ., NJ (United States); Cole, Andrew [Columbia Univ., New York, NY (United States); Finn, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-02

    This project is focused on theoretical and computational development for quantitative prediction of the stability and control of the equilibrium state evolution in toroidal burning plasmas, including its interaction with the surrounding resistive wall. The stability of long pulse burning plasmas is highly sensitive to the physics of resonant layers in the plasma, sources of momentum and flow, kinetic effects of energetic particles, and boundary conditions at the wall, including feedback control and error fields. In ITER in particular, the low toroidal flow equilibrium state, sustained primarily by energetic alpha particles from fusion reactions, will require the consideration of all of these key elements to predict quantitatively the stability and evolution. The principal investigators on this project have performed theoretical and computational analyses, guided by analytic modeling, to address this physics in realistic configurations. The overall goal has been to understand the key physics mechanisms that describe stable toroidal burning plasmas under active feedback control. Several relevant achievements have occurred during this project, leading to publications and invited conference presentations. In theoretical efforts, with the physics of the resonant layers, resistive wall, and toroidal momentum transport included, this study has extended from cylindrical resistive plasma - resistive wall models with feedback control to toroidal geometry with strong shaping to study mode coupling effects on the stability. These results have given insight into combined tearing and resistive wall mode behavior in simulations and experiment, while enabling a rapid exploration of plasma parameter space, to identify possible domains of interest for large plasma codes to investigate in more detail. Resonant field amplification and quasilinear torques in the presence of error fields and velocity shear have also been investigated. Here it was found, surprisingly, that the Maxwell

  12. High-resolution liquid patterns via three-dimensional droplet shape control.

    Science.gov (United States)

    Raj, Rishi; Adera, Solomon; Enright, Ryan; Wang, Evelyn N

    2014-09-25

    Understanding liquid dynamics on surfaces can provide insight into nature's design and enable fine manipulation capability in biological, manufacturing, microfluidic and thermal management applications. Of particular interest is the ability to control the shape of the droplet contact area on the surface, which is typically circular on a smooth homogeneous surface. Here, we show the ability to tailor various droplet contact area shapes ranging from squares, rectangles, hexagons, octagons, to dodecagons via the design of the structure or chemical heterogeneity on the surface. We simultaneously obtain the necessary physical insights to develop a universal model for the three-dimensional droplet shape by characterizing the droplet side and top profiles. Furthermore, arrays of droplets with controlled shapes and high spatial resolution can be achieved using this approach. This liquid-based patterning strategy promises low-cost fabrication of integrated circuits, conductive patterns and bio-microarrays for high-density information storage and miniaturized biochips and biosensors, among others.

  13. Robust control design for the plasma horizontal position control on J-TEXT Tokamak

    International Nuclear Information System (INIS)

    Yu, W.Z.; Chen, Z.P.; Zhuang, G.; Wang, Z.J.

    2013-01-01

    It is extremely important for tokamak to control the plasma position during routine discharge. However, the model of plasma in tokamak usually contains much of the uncertainty, such as structured uncertainties and unmodeled dynamics. Compared with the traditional PID control approach, robust control theory is more suitable to handle this problem. In the paper, we propose a H ∞ robust control scheme to control the horizontal position of plasma during the flat-top phase of discharge on Joint Texas Experimental Tokamak (J-TEXT) tokamak. First, the model of our plant for plasma horizontal position control is obtained from the position equilibrium equations. Then the H ∞ robust control framework is used to synthesize the controller. Based on this, an H ∞ controller is designed to minimize the regulation/tracking error. Finally, a comparison study is conducted between the optimized H ∞ robust controller and the traditional PID controller in simulations. The simulation results of the H ∞ robust controller show a significant improvement of the performance with respect to those obtained with traditional PID controller, which is currently used on our machine

  14. The shaped pulses control and operation on the SG-III prototype facility

    Science.gov (United States)

    Ping, Li; Wei, Wang; Sai, Jin; Wanqing, Huang; Wenyi, Wang; Jingqin, Su; Runchang, Zhao

    2018-04-01

    The laser driven inertial confined fusion experiments require careful temporal shape control of the laser pulse. Two approaches are introduced to improve the accuracy and efficiency of the close loop feedback system for long term operation in TIL; the first one is a statistical model to analyze the variation of the parameters obtained from previous shots, the other is a matrix algorithm proposed to relate the electrical signal and the impulse amplitudes. With the model and algorithm applied in the pulse shaping in TIL, a variety of shaped pulses were produced with a 10% precision in half an hour for almost three years under different circumstance.

  15. Plasma control techniques of the ASDEX feedback system

    International Nuclear Information System (INIS)

    Schneider, F.

    1981-01-01

    In the ASDEX tokamak the shots are exactly preprogrammed and most of the disturbances are reproducible. So a computer can learn from one shot how to correct the next one. With this sort of disturbance feedforward one can also introduce a 'negative delay' in the program to compensate even fast and strong disturbances withous unwanted overswing or oscillations. The feedforward in conjunction with feedback control allows production of a magnetically limited plasma from the very beginning without any wall or limiter contact. This is a reason why in ASDEX the loop voltage on breakdown can be as low as 5 V/sup 2/. The plasma column can be controlled in the vacuum vessel even after disruptions have occurred

  16. Real-time software for the COMPASS tokamak plasma control

    Czech Academy of Sciences Publication Activity Database

    Valcárcel, D.F.; Duarte, A.S.; Neto, A.; Carvalho, I.S.; Carvalho, B.B.; Fernandes, H.; Sousa, J.; Sartori, F.; Janky, Filip; Cahyna, Pavel; Hron, Martin; Pánek, Radomír

    2010-01-01

    Roč. 85, 3-4 (2010), s. 470-473 ISSN 0920-3796. [IAEA Technical Meeting on Control, Data Acquisition and Remote Participation for Fusion Research/7th./. Aix – en – Provence, 15.06.2009-19.06.2009] Institutional research plan: CEZ:AV0Z20430508 Keywords : Real-time * ATCA * Data acquisition * Plasma control software Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.143, year: 2010 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3C-4YXMP1Y-3&_user=6542793&_coverDate=07%2F31%2F2010&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000070123&_version=1&_urlVersion=0&_userid=6542793&md5=9005df0735c0dbb3a93a9c154b0d09c1&searchtype=a

  17. Positron Plasma Control Techniques Applied to Studies of Cold Antihydrogen

    CERN Document Server

    Funakoshi, Ryo

    2003-01-01

    In the year 2002, two experiments at CERN succeeded in producing cold antihydrogen atoms, first ATHENA and subsequently ATRAP. Following on these results, it is now feasible to use antihydrogen to study the properties of antimatter. In the ATHENA experiment, the cold antihydrogen atoms are produced by mixing large amounts of antiprotons and positrons in a nested Penning trap. The complicated behaviors of the charged particles are controlled and monitored by plasma manipulation techniques. The antihydrogen events are studied using position sensitive detectors and the evidence of production of antihydrogen atoms is separated out with the help of analysis software. This thesis covers the first production of cold antihydrogen in the first section as well as the further studies of cold antihydrogen performed by using the plasma control techniques in the second section.

  18. User Control Interface for W7-X Plasma Operation

    International Nuclear Information System (INIS)

    Spring, A.; Laqua, H.; Schacht, J.

    2006-01-01

    The WENDELSTEIN 7-X fusion experiment will be a highly complex device operated by a likewise complex control system. The fundamental configuration of the W7-X control system follows two major design principles: It reflects the strict hierarchy of the machine set-up with a set of subordinated components, which in turn can be run autonomously during commissioning and testing. Secondly, it links the basic machine operation (mainly given by the infrastructure status and the components readiness) and the physics program execution (i.e. plasma operation) on each hierarchy level and on different time scales. The complexity of the control system implies great demands on appropriate user interfaces: specialized tools for specific control tasks allowing a dedicated view on the subject to be controlled, hiding complexity wherever possible and reasonable, providing similar operation methods on each hierarchy level and both manual interaction possibilities and a high degree of intelligent automation. The contribution will describe the operation interface for experiment control including the necessary links to the machine operation. The users of ' Xcontrol ' will be both the W7-X session leaders during plasma discharge experiments and the components' or diagnostics' operators during autonomous mode or even laboratory experiments. The main ' Xcontrol ' features, such as program composition and validation, manual and automatic control instruments, resource survey, and process monitoring, will be presented. The implementation principles and the underlying communication will be discussed. (author)

  19. Control of proton beam divergence in intense-laser foil-plasma interaction

    International Nuclear Information System (INIS)

    Kawata, S.; Sonobe, R.; Miyazaki, S.; Sakai, K.; Kikuchi, T.

    2006-01-01

    Quality of an ion beam is one of the critical factors in intense-laser ion beam generation. A purpose of this study is the suppression of transverse proton divergence by a controlled electron cloud in laser-foil interactions. In this study, the foil target has a hole at the opposite side of the laser illumination. The electrons accelerated by an intense laser are limited in transverse by a neutral plasma at a protuberant part. Therefore the protons are accelerated and also controlled transversely by the electron cloud structure. In our 2.5-dimensional Particle-in-Cell simulations we demonstrate that the transverse shape of the electron cloud is well controlled and the collimated proton beam is generated successfully in the target with the hole. (authors)

  20. Control of exogenous factors affecting plasma homovanillic acid concentration.

    Science.gov (United States)

    Davidson, M; Giordani, A B; Mohs, R C; Mykytyn, V V; Platt, S; Aryan, Z S; Davis, K L

    1987-04-01

    Measurements of plasma homovanillic acid (pHVA) concentrations appear to be a valid research strategy in psychiatric disorders in which a central dopamine (DA) abnormality has been implicated. This study provides guidance about the control of some of the exogenous factors affecting pHVA concentrations. Fasting for 14 hours eliminates the dietary effects on pHVA in healthy human subjects. Changing position, walking for 30 minutes, or smoking two cigarettes has no effect on pHVA concentrations.

  1. Fundamentals of plasma physics and controlled fusion. The third edition

    International Nuclear Information System (INIS)

    Miyamoto, Kenro

    2011-06-01

    Primary objective of this lecture note is to provide a basic text for the students to study plasma physics and controlled fusion researches. Secondary objective is to offer a reference book describing analytical methods of plasma physics for the researchers. This was written based on lecture notes for a graduate course and an advanced undergraduate course those have been offered at Department of Physics, Faculty of Science, University of Tokyo. In ch.1 and 2, basic concept of plasma and its characteristics are explained. In ch.3, orbits of ion and electron are described in several magnetic field configurations. Chapter 4 formulates Boltzmann equation of velocity space distribution function, which is the basic relation of plasma physics. From ch.5 to ch.9, plasmas are described as magnetohydrodynamic (MHD) fluid. MHD equation of motion (ch.5), equilibrium (ch.6) and diffusion and confinement time of plasma (ch.7) are described by the fluid model. Chapters 8 and 9 discuss problems of MHD instabilities whether a small perturbation will grow to disrupt the plasma or will damp to a stable state. The basic MHD equation of motion can be derived by taking an appropriate average of Boltzmann equation. This mathematical process is described in appendix A. The derivation of useful energy integral formula of axisymmetric toroidal system and the analysis of high n ballooning mode are described in app. B. From ch.10 to ch.14, plasmas are treated by kinetic theory. This medium, in which waves and perturbations propagate, is generally inhomogeneous and anisotropic. It may absorb or even amplify the wave. Cold plasma model described in ch.10 is applicable when the thermal velocity of plasma particles is much smaller than the phase velocity of wave. Because of its simplicity, the dielectric tensor of cold plasma can be easily derived and the properties of various wave can be discussed in the case of cold plasma. If the refractive index becomes large and the phase velocity of the

  2. Plasma position control in a tokamak reactor around ignition

    International Nuclear Information System (INIS)

    Carretta, U.; Minardi, E.; Bacelli, N.

    1986-01-01

    Plasma position control in a tokamak reactor in the phase approaching ignition is closely related to burn control. If ignited burn corresponds to a thermally unstable situation the plasma becomes sensitive to the thermal instability already in the phase when ignition is approached so that the trajectory in the position-pressure (R,p) space becomes effectively unpredictable. For example, schemes involving closed cycles around ignition can be unstable in the heating-cooling phases, and the deviations may be cumulative in time. Reliable plasma control in pressure-position (p, R) space is achieved by beforehand constraining the p, R trajectory rigidly with suitable feedback vertical field stabilization, which is to be established already below ignition. A scheme in which ignition is approached in a stable and automatic way by feedback stabilization on the vertical field is proposed and studied in detail. The values of the gain coefficient ensuring stabilization and the associated p and R excursions are discussed both analytically, with a 0-D approximation including non-linear effects, and numerically with a 1-D code in cylindrical geometry. Profile effects increase the excursions, in particular above ignition. (author)

  3. Methodologies for Root Locus and Loop Shaping Control Design with Comparisons

    Science.gov (United States)

    Kopasakis, George

    2017-01-01

    This paper describes some basics for the root locus controls design method as well as for loop shaping, and establishes approaches to expedite the application of these two design methodologies to easily obtain control designs that meet requirements with superior performance. The two design approaches are compared for their ability to meet control design specifications and for ease of application using control design examples. These approaches are also compared with traditional Proportional Integral Derivative (PID) control in order to demonstrate the limitations of PID control. Robustness of these designs is covered as it pertains to these control methodologies and for the example problems.

  4. ROBUST CONTROL OF END-TIDAL CO2 USING THE H∞ LOOP-SHAPING APPROACH

    Directory of Open Access Journals (Sweden)

    Anake Pomprapa

    2013-12-01

    Full Text Available Mechanically ventilated patients require appropriate settings of respiratory control variables to maintain acceptable gas exchange. To control the carbon dioxide (CO2 level effectively and automatically, system identification based on a human subject was performed using a linear affine model and a nonlinear Hammerstein structure. Subsequently, a robust controller was designed using the H∞ loop-shaping approach, which synthesizes the optimal controller based on a specific objective by achieving stability with guaranteed performance. For demonstration purposes, the closed-loop control ventilation system was successfully tested in a human volunteer. The experimental results indicate that the blood CO2 level may indeed be controlled noninvasively by measuring end-tidal CO2 from expired air. Keeping the limited amount of experimental data in mind, we conclude that H∞ loop-shaping may be a promising technique for control of mechanical ventilation in patients with respiratory insufficiency.

  5. Interpreting Disruption Prediction Models to Improve Plasma Control

    Science.gov (United States)

    Parsons, Matthew

    2017-10-01

    In order for the tokamak to be a feasible design for a fusion reactor, it is necessary to minimize damage to the machine caused by plasma disruptions. Accurately predicting disruptions is a critical capability for triggering any mitigative actions, and a modest amount of attention has been given to efforts that employ machine learning techniques to make these predictions. By monitoring diagnostic signals during a discharge, such predictive models look for signs that the plasma is about to disrupt. Typically these predictive models are interpreted simply to give a `yes' or `no' response as to whether a disruption is approaching. However, it is possible to extract further information from these models to indicate which input signals are more strongly correlated with the plasma approaching a disruption. If highly accurate predictive models can be developed, this information could be used in plasma control schemes to make better decisions about disruption avoidance. This work was supported by a Grant from the 2016-2017 Fulbright U.S. Student Program, administered by the Franco-American Fulbright Commission in France.

  6. Forces and dynamics in epithelial domes of controlled size and shape

    Science.gov (United States)

    Latorre-Ibars, Ernest; Casares, Laura; Gomez-Gonzalez, Manuel; Uroz, Marina; Arroyo, Marino; Trepat, Xavier

    Mechanobiology of epithelia plays a central role in morphogenesis, wound healing, and tumor progression. Its current understanding relies on mechanical measurements on flat epithelial layers. However, most epithelia in vivo exhibit a curved 3D shape enclosing a pressurized lumen. Using soft micropatterned substrates we produce massive parallel arrays of epithelial domes with controlled size and basal shape. We measure epithelial traction, tension, and luminal pressure in epithelial domes. The local stress tensor on the freestanding epithelial membrane is then mapped by combining measured luminal pressure and local curvature. We show that tension and cell shape are highly anisotropic and vary along the meridional position of the domes. Finally, we establish constitutive relations between shape, tension, and pressure during perturbations of the contractile machinery, osmotic shocks, and spontaneous fluctuations of dome volume. Our findings contradict a description of the epithelium as a fluid capillary surface. Cells in the dome are unable to relax into a uniform and isotropic tensional state through sub- and supra-cellular rearrangements. Mapping epithelial shape, tension, and pressure will enable quantitative studies of mechanobiology in 3D epithelia of controlled size and shape.

  7. Shape-Selection of Thermodynamically Stabilized Colloidal Pd and Pt Nanoparticles Controlled via Support Effects

    DEFF Research Database (Denmark)

    Ahmadi, M.; Behafarid, F.; Holse, Christian

    2015-01-01

    Colloidal chemistry, in combination with nanoparticle (NP)/support epitaxial interactions is used here to synthesize shape-selected and thermodynamically stable metallic NPs over a broad range of NP sizes. The morphology of three-dimensional palladium and platinum NPs supported on TiO2(110) was i......Colloidal chemistry, in combination with nanoparticle (NP)/support epitaxial interactions is used here to synthesize shape-selected and thermodynamically stable metallic NPs over a broad range of NP sizes. The morphology of three-dimensional palladium and platinum NPs supported on TiO2...... rows and was found to be responsible for the shape control. The ability of synthesizing thermally stable shape-selected metal NPs demonstrated here is expected to be of relevance for applications in the field of catalysis, since the activity and selectivity of NP catalysts has been shown to strongly...

  8. H∞ Loop Shaping Control of Input Saturated Systems with Norm-Bounded Parametric Uncertainty

    Directory of Open Access Journals (Sweden)

    Renan Lima Pereira

    2015-01-01

    Full Text Available This paper proposes a gain-scheduling control design strategy for a class of linear systems with the presence of both input saturation constraints and norm-bounded parametric uncertainty. LMI conditions are derived in order to obtain a gain-scheduled controller that ensures the robust stability and performance of the closed loop system. The main steps to obtain such a controller are given. Differently from other gain-scheduled approaches in the literature, this one focuses on the problem of H∞ loop shaping control design with input saturation nonlinearity and norm-bounded uncertainty to reduce the effect of the disturbance input on the controlled outputs. Here, the design problem has been formulated in the four-block H∞ synthesis framework, in which it is possible to describe the parametric uncertainty and the input saturation nonlinearity as perturbations to normalized coprime factors of the shaped plant. As a result, the shaped plant is represented as a linear parameter-varying (LPV system while the norm-bounded uncertainty and input saturation are incorporated. This procedure yields a linear parameter-varying structure for the controller that ensures the stability of the polytopic LPV shaped plant from the vertex property. Finally, the effectiveness of the method is illustrated through application to a physical system: a VTOL “vertical taking-off landing” helicopter.

  9. Status of the new WEST plasma control system

    International Nuclear Information System (INIS)

    Ravene, Nathalie; Nouailletas, Rémy; Signoret, Jacqueline; Guillerminet, Bernard; Treutterrer, Wolfgang; Spring, Anett; Masand, Harish; Dhongde, Jasraj; Bhandarkar, Manisha; Rapson, Chris; Laqua, Heike; Lewerentz, Marc; Moreau, Philippe; Brémond, Sylvain; Allegretti, Ludovic; Raupp, Gerhard; Werner, Andreas; Laurent, François Saint; Nardon, Eric

    2016-01-01

    The WEST (W – for Tungsten – Environment in Steady state Tokamak) project is aiming at minimizing technology and operational risks of a full tungsten actively cooled divertor on ITER. It was started in 2013 and consists in transforming the Tore Supra tokamak into an X point divertor device, while taking advantage of its long discharge capability. To operate the next coming operations of WEST, new controllers are required. These developments are an opportunity to develop a new Plasma Control System (PCS) architecture featuring build-in real time handling of both plasma and plants events, thus addressing key ITER needs. The Tore Supra PCS will be refurbished including a new Pulse Schedule Editor (PSE). The main idea is to use a time segmented approach to describe the pulse schedule with a full integration of event handling both on PCS and PSE. Further to detailed requirement specifications and architecture design, two software tools were selected to define and execute a whole plasma discharge defined as a set of time segments. The PCS real-time framework (RTF) is based on an upgraded version of the AUG framework, called DCS (Discharge Control System). The PSE is the Xedit application used on WEGA and under further development for W7-X facility. This paper reports on the status of the new WEST PCS developments. The on-going developments to adapt DCS to the Tore Supra Control infrastructure networks (new real-time network, chronology system and pulse supervision) will be reported. The required preparations for the use of Xedit will be presented, mainly the appropriate formal description of the WEST control system and the implementation of the mapping between the Xedit experiment configuration and DCS configuration files.

  10. Status of the new WEST plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Ravene, Nathalie, E-mail: nathalie.ravenel@gmail.com [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Nouailletas, Rémy; Signoret, Jacqueline; Guillerminet, Bernard [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Treutterrer, Wolfgang [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Spring, Anett [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Masand, Harish; Dhongde, Jasraj; Bhandarkar, Manisha [Institute for Plasma Research (IPR), Near Indira Bridge, Bhat, Gandhinagar, 382 428 Gujarat (India); Rapson, Chris [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Laqua, Heike; Lewerentz, Marc [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Moreau, Philippe; Brémond, Sylvain; Allegretti, Ludovic [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Raupp, Gerhard [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Werner, Andreas [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Laurent, François Saint; Nardon, Eric [IRFM, CEA, F-13108 Saint Paul lez Durance (France)

    2016-11-15

    The WEST (W – for Tungsten – Environment in Steady state Tokamak) project is aiming at minimizing technology and operational risks of a full tungsten actively cooled divertor on ITER. It was started in 2013 and consists in transforming the Tore Supra tokamak into an X point divertor device, while taking advantage of its long discharge capability. To operate the next coming operations of WEST, new controllers are required. These developments are an opportunity to develop a new Plasma Control System (PCS) architecture featuring build-in real time handling of both plasma and plants events, thus addressing key ITER needs. The Tore Supra PCS will be refurbished including a new Pulse Schedule Editor (PSE). The main idea is to use a time segmented approach to describe the pulse schedule with a full integration of event handling both on PCS and PSE. Further to detailed requirement specifications and architecture design, two software tools were selected to define and execute a whole plasma discharge defined as a set of time segments. The PCS real-time framework (RTF) is based on an upgraded version of the AUG framework, called DCS (Discharge Control System). The PSE is the Xedit application used on WEGA and under further development for W7-X facility. This paper reports on the status of the new WEST PCS developments. The on-going developments to adapt DCS to the Tore Supra Control infrastructure networks (new real-time network, chronology system and pulse supervision) will be reported. The required preparations for the use of Xedit will be presented, mainly the appropriate formal description of the WEST control system and the implementation of the mapping between the Xedit experiment configuration and DCS configuration files.

  11. Controlling the Plasma-Polymerization Process of N-Vinyl-2-pyrrolidone

    DEFF Research Database (Denmark)

    Norrman, Kion; Winther-Jensen, Bjørn

    2005-01-01

    N-vinyl-2-pyrrolidone was plasma-polymerized on glass substrates using a pulsed AC plasma. Pulsed AC plasma produces a chemical surface structure different from that produced by conventional RF plasma; this is ascribed to the different power regimes used. A high degree of control over the structure...... of the chemical surface was obtained using pulsed AC plasma, as shown by ToF-SIMS. It is demonstrated how the experimental conditions to some extent control the chemical structure of the plasma-polymerized film, e.g., film thickness, density of post-plasma-polymerized oligomeric chains, and the density of intact...

  12. Radiation control in fusion plasmas by magnetic confinement

    International Nuclear Information System (INIS)

    Dachicourt, R.

    2012-10-01

    The present work addresses two important issues for the industrial use of fusion: plasma radiation control, as a part of the more general power handling issue, and high density tokamak operation. These two issues will be most critical in the demonstration reactor, called DEMO, intermediate step between ITER and a future commercial reactor. For DEMO, the need to radiate a large fraction of the power so as to limit the peak power load on the divertor will be a key constraint. High confinement will have to be combined with high radiated power fraction, and the required level of plasma purity. The main achievement of this thesis is to have shown experimental evidence of the existence of a stable plasma regime meeting the most critical requirements of a DEMO scenario: an electron density up to 40% above the Greenwald value, together with a fraction of radiated power close to 80%, with a good energy confinement and limited dilution. The plasma is additionally heated with ion cyclotron waves in a central electron heating scenario, featuring alpha particle heating. The original observations reported in this work bring highly valuable new pieces of information both to the physics of the tokamak edge layer and to the construction of an 'integrated operational scenario' required to successfully operate fusion devices. In the way for getting high density plasmas, the new observations involve the following topics. First, the formation of a poloidal asymmetry in the edge electron density profile, with a maximum density located close to toroidal pumped limiter. This asymmetry occurs inside the separatrix, with a constant plasma pressure on magnetic surfaces. Secondly, a correlative decrease of the electron temperature in the same edge region. Thirdly, the excellent coupling capabilities of the ICRH waves, up to a central line averaged electron density of 1.4 times the Greenwald density. Fourthly, a poloidally asymmetric edge radiation region, providing the dissipation of 80% of

  13. 28. Zvenigorod conference on the plasma physics and controlled thermonuclear synthesis. Theses of reports

    International Nuclear Information System (INIS)

    2001-01-01

    Theses of reports, presented at the 28th Conference on the plasma physics and controlled thermonuclear synthesis (Zvenigorod, 19-23 February 2001) are published. 246 reports were heard at the following sections: magnetic confinement, theory and experiments; inertial thermonuclear synthesis; plasma processes and physics of gas-discharge plasma; physical bases of plasma technologies. 17 reports had the summarizing character [ru

  14. Active control of magneto-hydrodynamic instabilities in hot plasmas

    CERN Document Server

    2015-01-01

    During the past century, world-wide energy consumption has risen dramatically, which leads to a quest for new energy sources. Fusion of hydrogen atoms in hot plasmas is an attractive approach to solve the energy problem, with abundant fuel, inherent safety and no long-lived radioactivity.  However, one of the limits on plasma performance is due to the various classes of magneto-hydrodynamic instabilities that may occur. The physics and control of these instabilities in modern magnetic confinement fusion devices is the subject of this book. Written by foremost experts, the contributions will provide valuable reference and up-to-date research reviews for "old hands" and newcomers alike.

  15. On the maximum Q in feedback controlled subignited plasmas

    International Nuclear Information System (INIS)

    Anderson, D.; Hamnen, H.; Lisak, M.

    1990-01-01

    High Q operation in feedback controlled subignited fusion plasma requires the operating temperature to be close to the ignition temperature. In the present work we discuss technological and physical effects which may restrict this temperature difference. The investigation is based on a simplified, but still accurate, 0=D analytical analysis of the maximum Q of a subignited system. Particular emphasis is given to sawtooth ocsillations which complicate the interpretation of diagnostic neutron emission data into plasma temperatures and may imply an inherent lower bound on the temperature deviation from the ignition point. The estimated maximum Q is found to be marginal (Q = 10-20) from the point of view of a fusion reactor. (authors)

  16. Formation and control of plasma potentials in TMX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Simonen, T.C.; Orzechowski, T.J.; Porkolab, M.; Stallard, B.W.

    1981-05-06

    The methods to be employed to form and control plasma potentials in the TMX Upgrade tandem mirror with thermal barriers are described. ECRH-generated mirror -confined electron plasmas are used to establish a negative potential region to isolate the end-plug and central-cell celectrons. This thermal isolation will allow a higher end-plug electron temperature and an increased central-cell confining potential. Improved axial central-cell ion confinement results since higher temperature central-cell ions can be confined. This paper describes: (1) calculations of the sensitivity of barrier formation to vacuum conditions and to the presence of impurities in the neutral beams, (2) calculations of microwave penetration and absorption used to design the ECRH system, and (3) techniques to limit electron runaway to high energies by localized microwave beams and by relativistic detuning.

  17. Controlling Plasma Channels through Ultrashort Laser Pulse Filamentation

    Science.gov (United States)

    Ionin, Andrey; Seleznev, Leonid; Sunchugasheva, Elena

    2013-09-01

    A review of studies fulfilled at the Lebedev Institute in collaboration with the Moscow State University and Institute of Atmospheric Optics in Tomsk on influence of various characteristics of ultrashort laser pulse on plasma channels formed under its filamentation is presented. Filamentation of high-power laser pulses with wavefront controlled by a deformable mirror, with cross-sections spatially formed by various diaphragms and with different wavelengths was experimentally and numerically studied. An application of plasma channels formed due to filamentation of ultrashort laser pulse including a train of such pulses for triggering and guiding long electric discharges is discussed. The research was supported by RFBR Grants 11-02-12061-ofi-m and 11-02-01100, and EOARD Grant 097007 through ISTC Project 4073 P

  18. Formation and control of plasma potentials in TMX upgrade

    International Nuclear Information System (INIS)

    Simonen, T.C.; Orzechowski, T.J.; Porkolab, M.; Stallard, B.W.

    1981-01-01

    The methods to be employed to form and control plasma potentials in the TMX Upgrade tandem mirror with thermal barriers are described. ECRH-generated mirror -confined electron plasmas are used to establish a negative potential region to isolate the end-plug and central-cell celectrons. This thermal isolation will allow a higher end-plug electron temperature and an increased central-cell confining potential. Improved axial central-cell ion confinement results since higher temperature central-cell ions can be confined. This paper describes: (1) calculations of the sensitivity of barrier formation to vacuum conditions and to the presence of impurities in the neutral beams, (2) calculations of microwave penetration and absorption used to design the ECRH system, and (3) techniques to limit electron runaway to high energies by localized microwave beams and by relativistic detuning

  19. Separation control of NACA0015 airfoil using plasma actuators

    Science.gov (United States)

    Harada, Daisuke; Sakakibara, Jun

    2017-11-01

    Separation control of NACA0015 airfoil by means of plasma actuators was investigated. Plasma actuators in spanwise intermittent layout on the suction surface of the airfoil were activated with spanwise phase difference φ = 0 or φ = π in the case of dimensionless burst frequencyF+ = 6 and F+ = 0.5 at Re = 6.3 ×104 . The lift and drag of the airfoil were measured using a two component force balance. The flow around the airfoil was measured by PIV analysis. In the condition of F+ = 6 and φ = π at around stall angle, which is 10 degrees, the lift-to-drag ratio was higher than that ofF+ = 6 and φ = 0 . Therefore, it was confirmed that aerodynamic characteristics of the airfoil improved by disturbances with temporal and spatial phase difference.

  20. Plasma density remote control system of experimental advanced superconductive tokamak

    International Nuclear Information System (INIS)

    Zhang Mingxin; Luo Jiarong; Li Guiming; Wang Hua; Zhao Dazheng; Xu Congdong

    2007-01-01

    In Tokamak experiments, experimental data and information on the density control are stored in the local computer system. Therefore, the researchers have to be in the control room for getting the data. Plasma Density Remote Control System (DRCS), which is implemented by encapsulating the business logic on the client in the B/S module, conducts the complicated science computation and realizes the synchronization with the experimental process on the client. At the same time, Web Services and Data File Services are deployed for the data exchange. It is proved in the experiments that DRCS not only meets the requirements for the remote control, but also shows an enhanced capability on the data transmission. (authors)

  1. Plasma Physics and Controlled Nuclear Fusion Research. Vol. II. Proceedings of a Conference on Plasma Physics and Controlled Physics Research

    International Nuclear Information System (INIS)

    1966-01-01

    Research on controlled nuclear fusion was first disclosed at the Second United Nations Conference on the Peaceful Uses of Atomic Energy, held at Geneva in 1958. From the information given, it was evident that a better understanding of the behaviour of hot dense plasmas was needed before the goal of economic energy release from nuclear fusion could be reached. The fact that research since then has been most complex and costly has enhanced the desirability of international co-operation and exchange of information and experience. Having organized its First Conference on Plasma Physics and Controlled Nuclear Fusion Research at Salzburg in 1961, the International Atomic Energy Agency again provided the means for such cooperation in organizing its Second Conference on this subject on 6-10 September, 1965, at Culham, Abingdon, Berks, England. The meeting was arranged with the generous help of the United Kingdom Atomic Energy Authority at their Culham Laboratory, where the facilities and assistance of the staff were greatly appreciated. At the meeting, which was attended by 268 participants from 26 member states and three international organizations, significant results from many experiments, including those from the new and larger machines, became available. It has now become feasible to intercorrelate data obtained from a number of similar machines; this has led to a more complete understanding of plasma behaviour. No breakthrough was reported nor had been expected towards the economical release of the energy from fusion, but there was increased understanding of the problems of production, control and containment of high-density and high-temperature plasmas

  2. A note on supersonic flow control with nanosecond plasma actuator

    Science.gov (United States)

    Zheng, J. G.; Cui, Y. D.; Li, J.; Khoo, B. C.

    2018-04-01

    A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

  3. Plasma control issues for an advanced steady state tokamak reactor

    International Nuclear Information System (INIS)

    Moreau, D.

    2001-01-01

    This paper deals with specific control issues related to the advanced tokamak scenarios in which rather accurate tailoring of the current density profile is a requirement in connection with the steady state operation of a reactor in a high confinement optimized shear mode. It is found that adequate current profile control can be performed if real-time magnetic flux reconstruction is available through a set of dedicated diagnostics and computers, with sufficient accuracy to deduce the radial profile of the safety factor and of the internal plasma loop voltage. It is also shown that the safety factor can be precisely controlled in the outer half of the plasma through the surface loop voltage and the off-axis current drive power, but that a compromise must be made between the accuracy of the core safety factor control and the total duration of the current and fuel density ramp-up phases, so that the demonstration of the steady state reactor potential of the optimized/reversed shear concept in the Next Step device will demand pulse lengths of the order of one thousand seconds (or more for an ITER-size machine). (author)

  4. Plasma control issues for an advanced steady state tokamak reactor

    International Nuclear Information System (INIS)

    Moreau, D.; Voitsekhovitch, I.

    1999-01-01

    This paper deals with specific control issues related to the advanced tokamak scenarios in which rather accurate tailoring of the current density profile is a requirement in connection with the steady state operation of a reactor in a high confinement optimized shear mode. It is found that adequate current profile control can be performed if real-time magnetic flux reconstruction is available through a set of dedicated diagnostics and computers, with sufficient accuracy to deduce the radial profile of the safety factor and of the internal plasma loop voltage. It is also shown that the safety factor can be precisely controlled in the outer half of the plasma through the surface loop voltage and the off-axis current drive power, but that a compromise must be made between the accuracy of the core safety factor control and the total duration of the current and fuel density ramp-up phases, so that the demonstration of the steady state reactor potential of the optimized/reversed shear concept in the Next Step device will demand pulse lengths of the order of one thousand seconds (or more for an ITER-size machine). (author)

  5. Experimental investigation of shaping disturbance observer design for motion control of precision mechatronic stages with resonances

    Science.gov (United States)

    Yang, Jin; Hu, Chuxiong; Zhu, Yu; Wang, Ze; Zhang, Ming

    2017-08-01

    In this paper, shaping disturbance observer (SDOB) is investigated for precision mechatronic stages with middle-frequency zero/pole type resonance to achieve good motion control performance in practical manufacturing situations. Compared with traditional standard disturbance observer (DOB), in SDOB a pole-zero cancellation based shaping filter is cascaded to the mechatronic stage plant to meet the challenge of motion control performance deterioration caused by actual resonance. Noting that pole-zero cancellation is inevitably imperfect and the controller may even consequently become unstable in practice, frequency domain stability analysis is conducted to find out how each parameter of the shaping filter affects the control stability. Moreover, the robust design criterion of the shaping filter, and the design procedure of SDOB, are both proposed to guide the actual design and facilitate practical implementation. The SDOB with the proposed design criterion is applied to a linear motor driven stage and a voice motor driven stage, respectively. Experimental results consistently validate the effectiveness nature of the proposed SDOB scheme in practical mechatronics motion applications. The proposed SDOB design actually could be an effective unit in the controller design for motion stages of mechanical manufacture equipments.

  6. Frequency-shaped and observer-based discrete-time sliding mode control

    CERN Document Server

    Mehta, Axaykumar

    2015-01-01

    It is well established that the sliding mode control strategy provides an effective and robust method of controlling the deterministic system due to its well-known invariance property to a class of bounded disturbance and parameter variations. Advances in microcomputer technologies have made digital control increasingly popular among the researchers worldwide. And that led to the study of discrete-time sliding mode control design and its implementation. This brief presents, a method for multi-rate frequency shaped sliding mode controller design based on switching and non-switching type of reaching law. In this approach, the frequency dependent compensator dynamics are introduced through a frequency-shaped sliding surface by assigning frequency dependent weighing matrices in a linear quadratic regulator (LQR) design procedure. In this way, the undesired high frequency dynamics or certain frequency disturbance can be eliminated. The states are implicitly obtained by measuring the output at a faster rate than th...

  7. Adaptive proportional–integral–derivative tuning sliding mode control for a shape memory alloy actuator

    International Nuclear Information System (INIS)

    Tai, Nguyen Trong; Ahn, Kyoung Kwan

    2011-01-01

    In this paper, a novel adaptive sliding mode control with a proportional–integral–derivative (PID) tuning method is proposed to control a shape memory alloy (SMA) actuator. The goal of the controller is to achieve system robustness against the SMA hysteresis phenomenon, system uncertainties and external disturbances. In the controller, the PID controller is employed to approximate the sliding mode equivalent control along the direction that makes the sliding mode asymptotically stable. Due to the system nonlinearity, the PID control gain parameters are systematically computed online according to the adaptive law. To improve the transient performance, the initial PID gain parameters are optimized by the particle swarm optimization (PSO) method. Simulation and experimental results demonstrate that the controller performs well for the desired trajectory tracking, and the hysteresis phenomenon is compensated for completely. The control results are also compared with the optimized PID controller

  8. Three-dimensional static shape control analysis of composite plates using distributed piezoelectric actuators

    International Nuclear Information System (INIS)

    Shaik Dawood, M S I; Iannucci, L; Greenhalgh, E S

    2008-01-01

    In this work, based on a linear piezoelectric constitutive model, a three-dimensional finite element code using an eight-node brick element that includes the anisotropic and coupled field effects of piezoelectric actuators has been developed for the static shape control analysis of fibre reinforced composite laminates. The code was used to study voltage sensing and actuation capabilities of piezoelectric actuators on composite laminates. The required input voltages to the actuators in order to achieve a specified structural shape were determined using a weighted shape control method. The code was validated using two test cases obtained from the literature. The results were found to show good correlation for voltage actuation. However, since determining input voltages to achieve the desired structural shape is a type of inverse problem, there are no explicit solutions and hence the results obtained from the present model were not similar to those reported in the literature. The second validation also suggests that the anisotropic and coupled field effects of the piezoelectric actuators cannot be neglected as this has been shown to underestimate the required control voltages. The effects of different lamination angles, boundary conditions, plate length-to-thickness ratios and actuator dimensions on the control voltages have also been reported

  9. One-pot size and shape controlled synthesis of DMSO capped iron ...

    Indian Academy of Sciences (India)

    Size and shape of the capped iron oxide nanoparticles are well controlled by simply ... quently used to synthesize magnetic ferrites from different iron precursors ... added to the mixture resulting in a dark brown precipitate. Figure 2. (a–c). TG–DTA .... Doyle P S, Bibette J, Bancaud A and Viovy J L 2002 Science. 295 2237.

  10. To the problem of electron temperature control in plasma

    International Nuclear Information System (INIS)

    Galechyan, G.A.; Anna, P.R.

    1995-01-01

    One of the main problems in low temperature plasma is control plasma parameters at fixed values of current and gas pressure in the discharge. It is known that an increase in the intensity of sound wave directed along the positive column to values in excess of a definite threshold leads to essential rise of the temperature of electrons. However, no less important is the reduction of electron temperature in the discharge down to the value less than that in plasma in the absence external influence. It is known that to reduce the electron temperature in the plasma of CO 2 laser, easily ionizable admixture are usually introduced in the discharge area with the view of increasing the overpopulation. In the present work we shall show that the value of electron temperature can be reduced by varying of sound wave intensity at its lower values. The experiment was performed on an experimental setup consisted of the tube with length 52 cm and diameter 9.8 cm, two electrodes placed at the distance of 27 cm from each other. An electrodynamical radiator of sound wave was fastened to one of tube ends. Fastened to the flange at the opposite end was a microphone for the control of sound wave parameters. The studies were performed in range of pressures from 40 to 180 Torr and discharge currents from 40 to 110 mA. The intensity of sound wave was varied from 74 to 92 dB. The measurement made at the first resonance frequency f = 150 Hz of sound in the discharge tube, at which a quarter of wave length keep within the length of the tube. The measurement of longitudinal electric field voltage in plasma of positive column was conducted with the help of two probes according to the compensation method. Besides, the measurement of gas temperature in the discharge were taken. Two thermocouple sensors were arranged at the distance of 8 cm from the anode, one of them being installed on the discharge tube axis, the second-fixed the tube wall

  11. To the problem of electron temperature control in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Galechyan, G.A. [Institute of Applied Problem of Physics, Yerevan (Armenia); Anna, P.R. [Raritan Valley Community College, Somerville, NJ (United States)

    1995-12-31

    One of the main problems in low temperature plasma is control plasma parameters at fixed values of current and gas pressure in the discharge. It is known that an increase in the intensity of sound wave directed along the positive column to values in excess of a definite threshold leads to essential rise of the temperature of electrons. However, no less important is the reduction of electron temperature in the discharge down to the value less than that in plasma in the absence external influence. It is known that to reduce the electron temperature in the plasma of CO{sub 2} laser, easily ionizable admixture are usually introduced in the discharge area with the view of increasing the overpopulation. In the present work we shall show that the value of electron temperature can be reduced by varying of sound wave intensity at its lower values. The experiment was performed on an experimental setup consisted of the tube with length 52 cm and diameter 9.8 cm, two electrodes placed at the distance of 27 cm from each other. An electrodynamical radiator of sound wave was fastened to one of tube ends. Fastened to the flange at the opposite end was a microphone for the control of sound wave parameters. The studies were performed in range of pressures from 40 to 180 Torr and discharge currents from 40 to 110 mA. The intensity of sound wave was varied from 74 to 92 dB. The measurement made at the first resonance frequency f = 150 Hz of sound in the discharge tube, at which a quarter of wave length keep within the length of the tube. The measurement of longitudinal electric field voltage in plasma of positive column was conducted with the help of two probes according to the compensation method. Besides, the measurement of gas temperature in the discharge were taken. Two thermocouple sensors were arranged at the distance of 8 cm from the anode, one of them being installed on the discharge tube axis, the second-fixed the tube wall.

  12. Simulation of slag control for the Plasma Hearth Project

    International Nuclear Information System (INIS)

    Power, M.A.; Carney, K.P.; Peters. G.G.

    1996-01-01

    The goal of the Plasma Hearth Project is to stabilize alpha-emitting radionuclides in a vitreous slag and to reduce the effective storage volume of actinide-containing waste for long-term burial. The actinides have been shown to partition into the vitreous slag phase of the melt. The slag composition may be changed by adding glass-former elements to ensure that this removable slag has the most desired physical and chemical properties for long-term burial. A data acquisition and control system has been designed to regulate the composition of five elements in the slag

  13. Power supplies for plasma column control in COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Havlíček, Josef; Hauptmann, R.; Peroutka, Oldřich; Tadros, Momtaz; Hron, Martin; Janky, Filip; Vondráček, Petr; Cahyna, Pavel; Mikulín, Ondřej; Šesták, David; Junek, Pavel; Pánek, Radomír

    2013-01-01

    Roč. 88, 9-10 (2013), s. 1640-1645 ISSN 0920-3796. [Symposium on Fusion Technology (SOFT-27)/27./. Liège, 24.09.2012-28.09.2012] R&D Projects: GA ČR GAP205/11/2470; GA MŠk 7G10072; GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * Power supplies * Feedback control * Vertical displacement * Vertical kicks Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.149, year: 2013 http://www.sciencedirect.com/science/article/pii/S0920379613001543#

  14. Alternatives for contaminant control during MFTF plasma buildup

    International Nuclear Information System (INIS)

    Khan, J.M.; Valby, L.E.

    1979-01-01

    The MFTF mirror device considers all low-energy species to be contaminants, since their primary effect is to erode the plasma boundary by charge-exchange reactions. Confinement for other than hydrogen isotypes is far from complete and confinement time is hardly more than transit time from the source to the end wall. The brevity of the confinement time makes it all the more necessary to prevent any contamination which might further reduce it. At Livermore, the historical solution to contaminant control has been to evaporate titanium onto cold surfaces. An alternative to this approach and its implications are considered

  15. Feedback control of chlorine inductively coupled plasma etch processing

    International Nuclear Information System (INIS)

    Lin Chaung; Leou, K.-C.; Shiao, K.-M.

    2005-01-01

    Feedback control has been applied to poly-Si etch processing using a chlorine inductively coupled plasma. Since the positive ion flux and ion energy incident upon the wafer surface are the key factors that influence the etch rate, the ion current and the root mean square (rms) rf voltage on the wafer stage, which are measured using an impedance meter connected to the wafer stage, are adopted as the controlled variables to enhance etch rate. The actuators are two 13.56 MHz rf power generators, which adjust ion density and ion energy, respectively. The results of closed-loop control show that the advantages of feedback control can be achieved. For example, with feedback control, etch rate variation under the transient chamber wall condition is reduced roughly by a factor of 2 as compared to the open-loop case. In addition, the capability of the disturbance rejection was also investigated. For a gas pressure variation of 20%, the largest etch rate variation is about 2.4% with closed-loop control as compared with as large as about 6% variation using open-loop control. Also the effect of ion current and rms rf voltage on etch rate was studied using 2 2 factorial design whose results were used to derive a model equation. The obtained formula was used to adjust the set point of ion current and rf voltage so that the desired etch rate was obtained

  16. EURATOM-CEA association contributions to the 26. EPS conference on controlled fusion and plasma physics, Maastricht

    International Nuclear Information System (INIS)

    1999-10-01

    This report references the EURATOM-CEA association contributions presented at the 26. EPS conference on controlled fusion and plasma physics, in Maastricht (Netherlands) the 14-18 June 1999. Two invited papers and 24 contributed papers are proposed. They deal with: tokamak devices; particle recirculation in ergodic divertor; current profile control and MHD stability in Tore Supra discharges; edge-plasma control by the ergodic divertor; electron heat transport in stochastic magnetic layer; bolometry and radiated power; particle collection by ergodic divertor; study and simulation of plasma impurities; line shape modelling for plasma edge conditions; dynamical study of the radial structure of the fluctuations measured by reciprocating Langmuir probe in Tore Supra; up-down asymmetry of density fluctuations; Halo currents in a circular tokamak; real time measurement of the position, density, profile and current profile at Tore Supra; poloidal rotation measurement by reflectometry; interpretation of q-profile dependence of the LH power deposition profile during LHCD experiments; ICFR plasma production and optimization; improved core electron confinement; measurement of hard X-ray emission profile; modelling of shear effects on thermal and particles transport; ion turbulence; current drive generation based on autoresonance and intermittent trapping mechanisms. (A.L.B.)

  17. Analysis of Human Error Types and Performance Shaping Factors in the Next Generation Main Control Room

    International Nuclear Information System (INIS)

    Sin, Y. C.; Jung, Y. S.; Kim, K. H.; Kim, J. H.

    2008-04-01

    Main control room of nuclear power plants has been computerized and digitalized in new and modernized plants, as information and digital technologies make great progresses and become mature. Survey on human factors engineering issues in advanced MCRs: Model-based approach, Literature survey-based approach. Analysis of human error types and performance shaping factors is analysis of three human errors. The results of project can be used for task analysis, evaluation of human error probabilities, and analysis of performance shaping factors in the HRA analysis

  18. Invited and contributed papers presented at the 22. EPS conference on controlled fusion and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-08-01

    In this report one invited and fifteen contributed papers by researchers of the `Centre de Recherche en Physique des Plasmas`, Lausanne, to the 22. EPS Conference on Controlled Fusion and Plasma Physics are assembled. figs., tabs., refs.

  19. Power supply controlled for plasma torch generation; Fuente de alimentacion controlada para la generacion de un plasma

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Z, S

    1997-12-31

    The high density of energy furnished by thermal plasma is profited in a wide range of applications, such as those related with welding fusion, spray coating and at the present in waste destruction. The waste destruction by plasma is a very attractive process because the remaining products are formed by inert glassy grains and non-toxic gases. The main characteristics of thermal plasmas are presented in this work. Techniques based on power electronics are utilized to achieve a good performance in thermal plasma generation. This work shown the design and construction of three phase control system for electric supply of thermal plasma torch, with 250 kw of capacity, as a part of the project named `Destruction of hazard wastes by thermal plasma` actually working in the Instituto Nacional de Investigaciones Nucleares (ININ). The characteristics of thermal plasma and its generation are treated in the first chapter. The A C controllers by thyristors applied in three phase arrays are described in the chapter II, talking into account the power transformer, rectifiers bank and aliasing coil. The chapter III is dedicated in the design of the trigger module which controls the plasma current by varying the trigger angle of the SCR`s; the protection and isolating unit are also presented in this chapter. The results and conclusions are discussed in chapter IV. (Author).

  20. Determination of the plasma position for its real-time control in the COMPASS tokamak

    International Nuclear Information System (INIS)

    Janky, F.; Havlicek, J.; Valcarcel, D.; Hron, M.; Horacek, J.; Kudlacek, O.; Panek, R.; Carvalho, B.B.

    2011-01-01

    An efficient horizontal and vertical stabilization of the plasma column position are essential for a reliable tokamak operation. Plasma position is generally determined by plasma current, plasma pressure and external vertical and horizontal magnetic fields. Such fields are generated by poloidal field coils and proper algorithm for the current control have to by applied, namely, in case of fast feedback loops. This paper presents a real-time plasma position reconstruction algorithms developed for the COMPASS tokamak. Further, its implementation in the MARTe (Multithreaded Application Real-Time executor) is described and the first results from test of the algorithm for real-time control of horizontal plasma positions are presented.

  1. Determination of the plasma position for its real-time control in the COMPASS tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Janky, F., E-mail: jankyf@ipp.cas.cz [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague (Czech Republic); Havlicek, J. [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague (Czech Republic); Valcarcel, D. [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, P1049-001 Lisboa (Portugal); Hron, M.; Horacek, J. [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Kudlacek, O. [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Technicka 2, 166 27 Prague (Czech Republic); Panek, R. [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Carvalho, B.B. [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, P1049-001 Lisboa (Portugal)

    2011-10-15

    An efficient horizontal and vertical stabilization of the plasma column position are essential for a reliable tokamak operation. Plasma position is generally determined by plasma current, plasma pressure and external vertical and horizontal magnetic fields. Such fields are generated by poloidal field coils and proper algorithm for the current control have to by applied, namely, in case of fast feedback loops. This paper presents a real-time plasma position reconstruction algorithms developed for the COMPASS tokamak. Further, its implementation in the MARTe (Multithreaded Application Real-Time executor) is described and the first results from test of the algorithm for real-time control of horizontal plasma positions are presented.

  2. Effects of water plasma immersion ion implantation on surface electrochemical behavior of NiTi shape memory alloys in simulated body fluids

    International Nuclear Information System (INIS)

    Liu, X.M.; Wu, S.L.; Chu, Paul K.; Chung, C.Y.; Chu, C.L.; Yeung, K.W.K.; Lu, W.W.; Cheung, K.M.C.; Luk, K.D.K.

    2007-01-01

    Water plasma immersion ion implantation (PIII) was conducted on orthopedic NiTi shape memory alloy to enhance the surface electrochemical characteristics. The surface composition of the NiTi alloy before and after H 2 O-PIII was determined by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) was utilized to determine the roughness and morphology of the NiTi samples. Potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) were carried out to investigate the surface electrochemical behavior of the control and H 2 O-PIII NiTi samples in simulated body fluids (SBF) at 37 deg. C as well as the mechanism. The H 2 O-PIII NiTi sample showed a higher breakdown potential (E b ) than the control sample. Based on the AFM results, two different physical models with related equivalent electrical circuits were obtained to fit the EIS data and explain the surface electrochemical behavior of NiTi in SBF. The simulation results demonstrate that the higher resistance of the oxide layer produced by H 2 O-PIII is primarily responsible for the improvement in the surface corrosion resistance

  3. Plasma physics and controlled fusion research during half a century

    Energy Technology Data Exchange (ETDEWEB)

    Lehnert, Bo

    2001-06-01

    A review is given on the historical development of research on plasma physics and controlled fusion. The potentialities are outlined for fusion of light atomic nuclei, with respect to the available energy resources and the environmental properties. Various approaches in the research on controlled fusion are further described, as well as the present state of investigation and future perspectives, being based on the use of a hot plasma in a fusion reactor. Special reference is given to the part of this work which has been conducted in Sweden, merely to identify its place within the general historical development. Considerable progress has been made in fusion research during the last decades. Temperatures above the limit for ignition of self-sustained fusion reactions, i.e. at more than hundred million degrees, have been reached in large experiments and under conditions where the fusion power generation is comparable to the power losses. An energy producing fusion reactor could in principle be realized already today, but it would not become technically and economically efficient when being based on the present state of art. Future international research has therefore to be conducted along broad lines, with necessary ingredients of basic investigations and new ideas.

  4. Plasma physics and controlled fusion research during half a century

    International Nuclear Information System (INIS)

    Lehnert, Bo

    2001-06-01

    A review is given on the historical development of research on plasma physics and controlled fusion. The potentialities are outlined for fusion of light atomic nuclei, with respect to the available energy resources and the environmental properties. Various approaches in the research on controlled fusion are further described, as well as the present state of investigation and future perspectives, being based on the use of a hot plasma in a fusion reactor. Special reference is given to the part of this work which has been conducted in Sweden, merely to identify its place within the general historical development. Considerable progress has been made in fusion research during the last decades. Temperatures above the limit for ignition of self-sustained fusion reactions, i.e. at more than hundred million degrees, have been reached in large experiments and under conditions where the fusion power generation is comparable to the power losses. An energy producing fusion reactor could in principle be realized already today, but it would not become technically and economically efficient when being based on the present state of art. Future international research has therefore to be conducted along broad lines, with necessary ingredients of basic investigations and new ideas

  5. Smooth transition for CPG-based body shape control of a snake-like robot

    International Nuclear Information System (INIS)

    Nor, Norzalilah Mohamad; Ma, Shugen

    2014-01-01

    This paper presents a locomotion control based on central pattern generator (CPG) of a snake-like robot. The main point addressed in this paper is a method that produces a smooth transition of the body shape of a snake-like robot. Body shape transition is important for snake-like robot locomotion to adapt to different space widths and also for obstacle avoidance. By manipulating the phase difference of the CPG outputs instantly, it will results in a sharp point or discontinuity which lead to an unstable movement of the snake-like robot. To tackle the problem, we propose a way of controlling the body shape: by incorporating activation function in the phase oscillator CPG model. The simplicity of the method promises an easy implementation and simple control. Simulation results and torque analysis confirm the effectiveness of the proposed control method and thus, can be used as a locomotion control in various potential applications of a snake-like robot. (paper)

  6. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  7. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs.

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  8. Flow control in s-shaped air intake diffuser of gas turbine using proposed energy promoters

    Directory of Open Access Journals (Sweden)

    Jessam Raed A.

    2017-01-01

    Full Text Available This paper presents an experimental and numerical investigation of the flow control in an air intake S-shaped diffuser with and without energy promoters. The S-shaped diffuser had an area ratio 3.1and turning angle of 45°/45°. The proposed energy promoter was named as stream line sheet energy promoter. Computational Fluid Dynamics simulation was performed through commercial ANSYS-FLUENT 16.2 software. The measurements were made inside annular subsection, 45° from 360° of the complete annular shape of the diffuser, at Reynolds number 5.8×104 and turbulence intensity 4.1%. Results for the bare S-shaped diffuser (without energy promoters showed the flow structures within the S-shaped diffuser were dominated by counter-rotating vortices and boundary layer separation especially in the outer surface. The combination of the adverse pressure gradient at the first bend of outer surface and upstream low momentum wakes caused the boundary layer to separate early. The combinations of proposed energy promoters were installed on the inner and outer surfaces at three installation planes. The use of energy promoters resulting in significantly decreased the outer surface boundary layer separation with consequential improving the static pressure coefficient and reduction of total pressure losses

  9. Copper-assisted shape control in colloidal synthesis of indium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Selishcheva, Elena; Parisi, Juergen; Kolny-Olesiak, Joanna, E-mail: joanna.kolny@uni-oldenburg.de [University of Oldenburg, Energy and Semiconductor Research Laboratory, Institute of Physics (Germany)

    2012-02-15

    Indium oxide is an important n-type transparent semiconductor, finding application in solar cells, sensors, and optoelectronic devices. We present here a novel non-injection synthesis route for the preparation of colloidal indium oxide nanocrystals by using oleylamine (OLA) as ligand and as solvent. Indium oxide with cubic crystallographic structure is formed in a reaction between indium acetate and OLA, the latter is converted to oleylamide during the synthesis. The shape of the nanocrystals can be influenced by the addition of copper ions. When only indium (III) acetate is used as precursor flower-shaped indium oxide nanoparticles are obtained. Addition of copper salts such as copper (I) acetate, copper (II) acetate, copper (II) acetylacetonate, or copper (I) chloride, under otherwise identical reaction conditions changes the shape of nanoparticles to quasi-spherical or elongated. The anions, except for chloride, do not influence the shape of the resulting nanocrystals. This finding suggests that adsorption of copper ions on the In{sub 2}O{sub 3} surface during the nanoparticles growth is responsible for shape control, whereas changes in the reactivity of the In cations caused by the presence of different anions play a secondary role. X-ray diffraction, transmission electron microscopy, nuclear magnetic resonance, energy dispersive X-ray analysis, and UV-Vis-absorption spectroscopy are used to characterize the samples.

  10. Copper-assisted shape control in colloidal synthesis of indium oxide nanoparticles

    International Nuclear Information System (INIS)

    Selishcheva, Elena; Parisi, Jürgen; Kolny-Olesiak, Joanna

    2012-01-01

    Indium oxide is an important n-type transparent semiconductor, finding application in solar cells, sensors, and optoelectronic devices. We present here a novel non-injection synthesis route for the preparation of colloidal indium oxide nanocrystals by using oleylamine (OLA) as ligand and as solvent. Indium oxide with cubic crystallographic structure is formed in a reaction between indium acetate and OLA, the latter is converted to oleylamide during the synthesis. The shape of the nanocrystals can be influenced by the addition of copper ions. When only indium (III) acetate is used as precursor flower-shaped indium oxide nanoparticles are obtained. Addition of copper salts such as copper (I) acetate, copper (II) acetate, copper (II) acetylacetonate, or copper (I) chloride, under otherwise identical reaction conditions changes the shape of nanoparticles to quasi-spherical or elongated. The anions, except for chloride, do not influence the shape of the resulting nanocrystals. This finding suggests that adsorption of copper ions on the In 2 O 3 surface during the nanoparticles growth is responsible for shape control, whereas changes in the reactivity of the In cations caused by the presence of different anions play a secondary role. X-ray diffraction, transmission electron microscopy, nuclear magnetic resonance, energy dispersive X-ray analysis, and UV–Vis-absorption spectroscopy are used to characterize the samples.

  11. Forming three-dimensional closed shapes from two-dimensional soft ribbons by controlled buckling

    Science.gov (United States)

    Aoki, Michio; Juang, Jia-Yang

    2018-02-01

    Conventional manufacturing techniques-moulding, machining and casting-exist to produce three-dimensional (3D) shapes. However, these industrial processes are typically geared for mass production and are not directly applicable to residential settings, where inexpensive and versatile tools are desirable. Moreover, those techniques are, in general, not adequate to process soft elastic materials. Here, we introduce a new concept of forming 3D closed hollow shapes from two-dimensional (2D) elastic ribbons by controlled buckling. We numerically and experimentally characterize how the profile and thickness of the ribbon determine its buckled shape. We find a 2D master profile with which various elliptical 3D shapes can be formed. More complex natural and artificial hollow shapes, such as strawberry, hourglass and wheel, can also be achieved via strategic design and pattern engraving on the ribbons. The nonlinear response of the post-buckling regime is rationalized through finite-element analysis, which shows good quantitative agreement with experiments. This robust fabrication should complement conventional techniques and provide a rich arena for future studies on the mechanics and new applications of elastic hollow structures.

  12. BOOK REVIEW: Fundamentals of Plasma Physics and Controlled Fusion

    Science.gov (United States)

    Brambilla, Marco

    1998-04-01

    Professor Kenro Miyamoto, already well known for his textbook Plasma Physics for Nuclear Fusion (MIT Press, Cambridge, MA, 1976; revised edition 1989), has now published a new book entitled Fundamentals of Plasma Physics and Controlled Fusion (Iwanami Book Service Center, Tokyo, 1997). To a large extent, the new book is a somewhat shortened and well reorganized version of its predecessor. The style, concise and matter of fact, clearly shows the origin of the text in lectures given by the author to graduate students. As announced by the title, the book is divided into two parts: the first part (about 250 pages) is a general introduction to the physics of plasmas, while the second, somewhat shorter, part (about 150 pages), is devoted to a description of the most important experimental approaches to achieving controlled thermonuclear fusion. Even in the first part, moreover, the choice of subjects is consistently oriented towards the needs of fusion research. Thus, the introduction to the behaviour of charged particles (particle motion, collisions, etc.) and to the collective description of plasmas is quite short, although the reader will get a flavour of all the most important topics and will find a number of examples chosen for their relevance to fusion applications (only the presentation of the Vlasov equation, in the second section of Chapter 4, might be criticized as so concise as to be almost misleading, since the difference between microscopic and macroscopic fields is not even mentioned). Considerably more space is devoted to the magnetohydrodynamic (MHD) description of equilibrium and stability. This part includes the solution of the Grad-Shafranov equation for circular tokamaks, a brief discussion of Pfirsch-Schlüter, neoclassical and anomalous diffusion, and two relatively long chapters on the most important ideal and resistive MHD instabilities of toroidal plasmas; drift and ion temperature gradient driven instabilities are also briefly presented. The

  13. Control of highly vertically unstable plasmas in TCV with internal coils and fast power supply

    International Nuclear Information System (INIS)

    Favre, A.; Moret, J.M.; Chavan, R.; Fasel, D.; Hofmann, F.; Lister, J.B.; Mayor, J.M.; Perez, A.; Elkjaer, A.

    1996-01-01

    The goal of TCV (Tokamak a Configuration Variable) is to investigate effects of plasma shape, in particular high elongation (up to 3), on tokamak physics. Such elongated configurations (I p ≅1 MA) are highly vertically unstable with growth rates up to γ=4000 s -1 . Control of the vertical position using the poloidal coils located outside the vessel is limited to γ≤1000 s -1 because of the shielding effect of the conductive vessel and because of the relative slow time response of their power supplies (0.8 ms thyristor 12 pulse switching at 120 Hz). This dictated the necessity to install a coil set inside the vacuum vessel fed with a Fast Power Supply (FPS). The choice and design of the system with a special attention to the mechanical and electrical constraints in TCV tokamak, as the results and real performances, will be presented. (author) 3 figs., 2 tabs., 2 refs

  14. Adaptive online inverse control of a shape memory alloy wire actuator using a dynamic neural network

    International Nuclear Information System (INIS)

    Mai, Huanhuan; Liao, Xiaofeng; Song, Gangbing

    2013-01-01

    Shape memory alloy (SMA) actuators exhibit severe hysteresis, a nonlinear behavior, which complicates control strategies and limits their applications. This paper presents a new approach to controlling an SMA actuator through an adaptive inverse model based controller that consists of a dynamic neural network (DNN) identifier, a copy dynamic neural network (CDNN) feedforward term and a proportional (P) feedback action. Unlike fixed hysteresis models used in most inverse controllers, the proposed one uses a DNN to identify online the relationship between the applied voltage to the actuator and the displacement (the inverse model). Even without a priori knowledge of the SMA hysteresis and without pre-training, the proposed controller can precisely control the SMA wire actuator in various tracking tasks by identifying online the inverse model of the SMA actuator. Experiments were conducted, and experimental results demonstrated real-time modeling capabilities of DNN and the performance of the adaptive inverse controller. (paper)

  15. Adaptive online inverse control of a shape memory alloy wire actuator using a dynamic neural network

    Science.gov (United States)

    Mai, Huanhuan; Song, Gangbing; Liao, Xiaofeng

    2013-01-01

    Shape memory alloy (SMA) actuators exhibit severe hysteresis, a nonlinear behavior, which complicates control strategies and limits their applications. This paper presents a new approach to controlling an SMA actuator through an adaptive inverse model based controller that consists of a dynamic neural network (DNN) identifier, a copy dynamic neural network (CDNN) feedforward term and a proportional (P) feedback action. Unlike fixed hysteresis models used in most inverse controllers, the proposed one uses a DNN to identify online the relationship between the applied voltage to the actuator and the displacement (the inverse model). Even without a priori knowledge of the SMA hysteresis and without pre-training, the proposed controller can precisely control the SMA wire actuator in various tracking tasks by identifying online the inverse model of the SMA actuator. Experiments were conducted, and experimental results demonstrated real-time modeling capabilities of DNN and the performance of the adaptive inverse controller.

  16. Quantification of parameter uncertainty for robust control of shape memory alloy bending actuators

    International Nuclear Information System (INIS)

    Crews, John H; McMahan, Jerry A; Smith, Ralph C; Hannen, Jennifer C

    2013-01-01

    In this paper, we employ Bayesian parameter estimation techniques to derive gains for robust control of smart materials. Specifically, we demonstrate the feasibility of utilizing parameter uncertainty estimation provided by Markov chain Monte Carlo (MCMC) methods to determine controller gains for a shape memory alloy bending actuator. We treat the parameters in the equations governing the actuator’s temperature dynamics as uncertain and use the MCMC method to construct the probability densities for these parameters. The densities are then used to derive parameter bounds for robust control algorithms. For illustrative purposes, we construct a sliding mode controller based on the homogenized energy model and experimentally compare its performance to a proportional-integral controller. While sliding mode control is used here, the techniques described in this paper provide a useful starting point for many robust control algorithms. (paper)

  17. [Automatic adjustment control system for DC glow discharge plasma source].

    Science.gov (United States)

    Wan, Zhen-zhen; Wang, Yong-qing; Li, Xiao-jia; Wang, Hai-zhou; Shi, Ning

    2011-03-01

    There are three important parameters in the DC glow discharge process, the discharge current, discharge voltage and argon pressure in discharge source. These parameters influence each other during glow discharge process. This paper presents an automatic control system for DC glow discharge plasma source. This system collects and controls discharge voltage automatically by adjusting discharge source pressure while the discharge current is constant in the glow discharge process. The design concept, circuit principle and control program of this automatic control system are described. The accuracy is improved by this automatic control system with the method of reducing the complex operations and manual control errors. This system enhances the control accuracy of glow discharge voltage, and reduces the time to reach discharge voltage stability. The glow discharge voltage stability test results with automatic control system are provided as well, the accuracy with automatic control system is better than 1% FS which is improved from 4% FS by manual control. Time to reach discharge voltage stability has been shortened to within 30 s by automatic control from more than 90 s by manual control. Standard samples like middle-low alloy steel and tin bronze have been tested by this automatic control system. The concentration analysis precision has been significantly improved. The RSDs of all the test result are better than 3.5%. In middle-low alloy steel standard sample, the RSD range of concentration test result of Ti, Co and Mn elements is reduced from 3.0%-4.3% by manual control to 1.7%-2.4% by automatic control, and that for S and Mo is also reduced from 5.2%-5.9% to 3.3%-3.5%. In tin bronze standard sample, the RSD range of Sn, Zn and Al elements is reduced from 2.6%-4.4% to 1.0%-2.4%, and that for Si, Ni and Fe is reduced from 6.6%-13.9% to 2.6%-3.5%. The test data is also shown in this paper.

  18. Plasma-based actuators for turbulent boundary layer control in transonic flow

    Science.gov (United States)

    Budovsky, A. D.; Polivanov, P. A.; Vishnyakov, O. I.; Sidorenko, A. A.

    2017-10-01

    The study is devoted to development of methods for active control of flow structure typical for the aircraft wings in transonic flow with turbulent boundary layer. The control strategy accepted in the study was based on using of the effects of plasma discharges interaction with miniature geometrical obstacles of various shapes. The conceptions were studied computationally using 3D RANS, URANS approaches. The results of the computations have shown that energy deposition can significantly change the flow pattern over the obstacles increasing their influence on the flow in boundary layer region. Namely, one of the most interesting and promising data were obtained for actuators basing on combination of vertical wedge with asymmetrical plasma discharge. The wedge considered is aligned with the local streamlines and protruding in the flow by 0.4-0.8 of local boundary layer thickness. The actuator produces negligible distortion of the flow at the absence of energy deposition. Energy deposition along the one side of the wedge results in longitudinal vortex formation in the wake of the actuator providing momentum exchange in the boundary layer. The actuator was manufactured and tested in wind tunnel experiments at Mach number 1.5 using the model of flat plate. The experimental data obtained by PIV proved the availability of the actuator.

  19. QFT Based Robust Positioning Control of the PMSM Using Automatic Loop Shaping with Teaching Learning Optimization

    Directory of Open Access Journals (Sweden)

    Nitish Katal

    2016-01-01

    Full Text Available Automation of the robust control system synthesis for uncertain systems is of great practical interest. In this paper, the loop shaping step for synthesizing quantitative feedback theory (QFT based controller for a two-phase permanent magnet stepper motor (PMSM has been automated using teaching learning-based optimization (TLBO algorithm. The QFT controller design problem has been posed as an optimization problem and TLBO algorithm has been used to minimize the proposed cost function. This facilitates designing low-order fixed-structure controller, eliminates the need of manual loop shaping step on the Nichols charts, and prevents the overdesign of the controller. A performance comparison of the designed controller has been made with the classical PID tuning method of Ziegler-Nichols and QFT controller tuned using other optimization algorithms. The simulation results show that the designed QFT controller using TLBO offers robust stability, disturbance rejection, and proper reference tracking over a range of PMSM’s parametric uncertainties as compared to the classical design techniques.

  20. Solidification interface shape control in a continuous Czochralski silicon growth system

    Science.gov (United States)

    Wang, Chenlei; Zhang, Hui; Wang, Tihu; Zheng, Lili

    2006-01-01

    In a continuous Czochralski (CCZ) growth system with a shallow and replenished melt proposed earlier, large-diameter crystals may be grown at a high pull rate and reduced melt convection. The proposed system consists of two heaters. In this paper, the relationship between the solidification interface and the power levels is established. An interface control algorithm is developed to achieve the desired interface shape by adjusting the power level of the bottom heater. The control algorithm is incorporated into an existing process model, and the efficiency of the control algorithm is tested.

  1. Controllable synthesis of rice-shape Alq3 nanoparticles with single crystal structure

    Science.gov (United States)

    Xie, Wanfeng; Fan, Jihui; Song, Hui; Jiang, Feng; Yuan, Huimin; Wei, Zhixian; Ji, Ziwu; Pang, Zhiyong; Han, Shenghao

    2016-10-01

    We report the controllable growth of rice-shape nanoparticles of Alq3 by an extremely facile self-assembly approach. Possible mechanisms have been proposed to interpret the formation and controlled process of the single crystal nanoparticles. The field-emission performances (turn-on field 7 V μm-1, maximum current density 2.9 mA cm-2) indicate the potential application on miniaturized nano-optoelectronics devices of Alq3-based. This facile method can potentially be used for the controlled synthesis of other functional complexes and organic nanostructures.

  2. Magnetic Detachment and Plume Control in Escaping Magnetized Plasma

    International Nuclear Information System (INIS)

    Schmit, P.F.; Fisch, N.J.

    2008-01-01

    The model of two-fluid, axisymmetric, ambipolar magnetized plasma detachment from thruster guide fields is extended to include plasmas with non-zero injection angular velocity profiles. Certain plasma injection angular velocity profiles are shown to narrow the plasma plume, thereby increasing exhaust efficiency. As an example, we consider a magnetic guide field arising from a simple current ring and demonstrate plasma injection schemes that more than double the fraction of useful exhaust aperture area, more than halve the exhaust plume angle, and enhance magnetized plasma detachment

  3. Physics of the conceptual design of the ITER plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Snipes, J.A., E-mail: Joseph.Snipes@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Bremond, S. [CEA-IRFM, 13108 St Paul-lez-Durance (France); Campbell, D.J. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Casper, T. [1166 Bordeaux St, Pleasanton, CA 94566 (United States); Douai, D. [CEA-IRFM, 13108 St Paul-lez-Durance (France); Gribov, Y. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Humphreys, D. [General Atomics, San Diego, CA 92186 (United States); Lister, J. [Association EURATOM-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne (EPFL), CRPP, Lausanne CH-1015 (Switzerland); Loarte, A.; Pitts, R. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Sugihara, M., E-mail: Sugihara_ma@yahoo.co.jp [Japan (Japan); Winter, A.; Zabeo, L. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France)

    2014-05-15

    Highlights: • ITER plasma control system conceptual design has been finalized. • ITER's plasma control system will evolve with the ITER research plan. • A sophisticated actuator sharing scheme is being developed to apply multiple coupled control actions simultaneously with a limited set of actuators. - Abstract: The ITER plasma control system (PCS) will play a central role in enabling the experimental program to attempt to sustain DT plasmas with Q = 10 for several hundred seconds and also support research toward the development of steady-state operation in ITER. The PCS is now in the final phase of its conceptual design. The PCS relies on about 45 diagnostic systems to assess real-time plasma conditions and about 20 actuator systems for overall control of ITER plasmas. It will integrate algorithms required for active control of a wide range of plasma parameters with sophisticated event forecasting and handling functions, which will enable appropriate transitions to be implemented, in real-time, in response to plasma evolution or actuator constraints. In specifying the PCS conceptual design, it is essential to define requirements related to all phases of plasma operation, ranging from early (non-active) H/He plasmas through high fusion gain inductive plasmas to fully non-inductive steady-state operation, to ensure that the PCS control functionality and architecture will be capable of satisfying the demands of the ITER research plan. The scope of the control functionality required of the PCS includes plasma equilibrium and density control commonly utilized in existing experiments, control of the plasma heat exhaust, control of a range of MHD instabilities (including mitigation of disruptions), and aspects such as control of the non-inductive current and the current profile required to maintain stable plasmas in steady-state scenarios. Control areas are often strongly coupled and the integrated control of the plasma to reach and sustain high plasma

  4. Physics of the conceptual design of the ITER plasma control system

    International Nuclear Information System (INIS)

    Snipes, J.A.; Bremond, S.; Campbell, D.J.; Casper, T.; Douai, D.; Gribov, Y.; Humphreys, D.; Lister, J.; Loarte, A.; Pitts, R.; Sugihara, M.; Winter, A.; Zabeo, L.

    2014-01-01

    Highlights: • ITER plasma control system conceptual design has been finalized. • ITER's plasma control system will evolve with the ITER research plan. • A sophisticated actuator sharing scheme is being developed to apply multiple coupled control actions simultaneously with a limited set of actuators. - Abstract: The ITER plasma control system (PCS) will play a central role in enabling the experimental program to attempt to sustain DT plasmas with Q = 10 for several hundred seconds and also support research toward the development of steady-state operation in ITER. The PCS is now in the final phase of its conceptual design. The PCS relies on about 45 diagnostic systems to assess real-time plasma conditions and about 20 actuator systems for overall control of ITER plasmas. It will integrate algorithms required for active control of a wide range of plasma parameters with sophisticated event forecasting and handling functions, which will enable appropriate transitions to be implemented, in real-time, in response to plasma evolution or actuator constraints. In specifying the PCS conceptual design, it is essential to define requirements related to all phases of plasma operation, ranging from early (non-active) H/He plasmas through high fusion gain inductive plasmas to fully non-inductive steady-state operation, to ensure that the PCS control functionality and architecture will be capable of satisfying the demands of the ITER research plan. The scope of the control functionality required of the PCS includes plasma equilibrium and density control commonly utilized in existing experiments, control of the plasma heat exhaust, control of a range of MHD instabilities (including mitigation of disruptions), and aspects such as control of the non-inductive current and the current profile required to maintain stable plasmas in steady-state scenarios. Control areas are often strongly coupled and the integrated control of the plasma to reach and sustain high plasma

  5. Pulse width modulation-based temperature tracking for feedback control of a shape memory alloy actuator.

    Science.gov (United States)

    Ayvali, Elif; Desai, Jaydev P

    2014-04-01

    This work presents a temperature-feedback approach to control the radius of curvature of an arc-shaped shape memory alloy (SMA) wire. The nonlinear properties of the SMA such as phase transformation and its dependence on temperature and stress make SMA actuators difficult to control. Tracking a desired trajectory is more challenging than controlling just the position of the SMA actuator since the desired path is continuously changing. Consequently, tracking the desired strain directly or tracking the parameters such as temperature and electrical resistance that are related to strain with a model is a challenging task. Temperature-feedback is an attractive approach when direct measurement of strain is not practical. Pulse width modulation (PWM) is an effective method for SMA actuation and it can be used along with a compensator to control the temperature of the SMA. Using the constitutive model of the SMA, the desired temperature profile can be obtained for a given strain trajectory. A PWM-based nonlinear PID controller with a feed-forward heat transfer model is proposed to use temperature-feedback for tracking a desired temperature trajectory. The proposed controller is used during the heating phase of the SMA actuator. The controller proves to be effective in tracking step-wise and continuous trajectories.

  6. Explicit Nonlinear Model Predictive Control for a Saucer-Shaped Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Zhihui Xing

    2013-01-01

    Full Text Available A lifting body unmanned aerial vehicle (UAV generates lift by its body and shows many significant advantages due to the particular shape, such as huge loading space, small wetted area, high-strength fuselage structure, and large lifting area. However, designing the control law for a lifting body UAV is quite challenging because it has strong nonlinearity and coupling, and usually lacks it rudders. In this paper, an explicit nonlinear model predictive control (ENMPC strategy is employed to design a control law for a saucer-shaped UAV which can be adequately modeled with a rigid 6-degrees-of-freedom (DOF representation. In the ENMPC, control signal is calculated by approximation of the tracking error in the receding horizon by its Taylor-series expansion to any specified order. It enhances the advantages of the nonlinear model predictive control and eliminates the time-consuming online optimization. The simulation results show that ENMPC is a propriety strategy for controlling lifting body UAVs and can compensate the insufficient control surface area.

  7. Management of complex data flows in the ASDEX Upgrade plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Treutterer, Wolfgang, E-mail: Wolfgang.Treutterer@ipp.mpg.de [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Neu, Gregor; Raupp, Gerhard; Zasche, Dieter; Zehetbauer, Thomas [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Cole, Richard; Lueddecke, Klaus [Unlimited Computer Systems, Iffeldorf (Germany)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Control system architectures with data-driven workflows are efficient, flexible and maintainable. Black-Right-Pointing-Pointer Signal groups provide coherence of interrelated signals and increase the efficiency of process synchronisation. Black-Right-Pointing-Pointer Sample tags indicating sample quality form the fundament of a local event handling strategy. Black-Right-Pointing-Pointer A self-organising workflow benefits from sample tags consisting of time stamp and stream activity. - Abstract: Establishing adequate technical and physical boundary conditions for a sustained nuclear fusion reaction is a challenging task. Phased feedback control and monitoring for heating, fuelling and magnetic shaping is mandatory, especially for fusion devices aiming at high performance plasmas. Technical and physical interrelations require close collaboration of many components in sequential as well as in parallel processing flows. Moreover, handling of asynchronous, off-normal events has become a key element of modern plasma performance optimisation and machine protection recipes. The manifoldness of plasma states and events, the variety of plant system operation states and the diversity in diagnostic data sampling rates can hardly be mastered with a rigid control scheme. Rather, an adaptive system topology in combination with sophisticated synchronisation and process scheduling mechanisms is suited for such an environment. Moreover, the system is subject to real-time control constraints: response times must be deterministic and adequately short. Therefore, the experimental tokamak device ASDEX Upgrade employs a discharge control system DCS, whose core has been designed to meet these requirements. In the paper we will compare the scheduling schemes for the parallelised realisation of a control workflow and show the advantage of a data-driven workflow over a managed workflow. The data-driven workflow as used in DCS is based on signals

  8. Management of complex data flows in the ASDEX Upgrade plasma control system

    International Nuclear Information System (INIS)

    Treutterer, Wolfgang; Neu, Gregor; Raupp, Gerhard; Zasche, Dieter; Zehetbauer, Thomas; Cole, Richard; Lüddecke, Klaus

    2012-01-01

    Highlights: ► Control system architectures with data-driven workflows are efficient, flexible and maintainable. ► Signal groups provide coherence of interrelated signals and increase the efficiency of process synchronisation. ► Sample tags indicating sample quality form the fundament of a local event handling strategy. ► A self-organising workflow benefits from sample tags consisting of time stamp and stream activity. - Abstract: Establishing adequate technical and physical boundary conditions for a sustained nuclear fusion reaction is a challenging task. Phased feedback control and monitoring for heating, fuelling and magnetic shaping is mandatory, especially for fusion devices aiming at high performance plasmas. Technical and physical interrelations require close collaboration of many components in sequential as well as in parallel processing flows. Moreover, handling of asynchronous, off-normal events has become a key element of modern plasma performance optimisation and machine protection recipes. The manifoldness of plasma states and events, the variety of plant system operation states and the diversity in diagnostic data sampling rates can hardly be mastered with a rigid control scheme. Rather, an adaptive system topology in combination with sophisticated synchronisation and process scheduling mechanisms is suited for such an environment. Moreover, the system is subject to real-time control constraints: response times must be deterministic and adequately short. Therefore, the experimental tokamak device ASDEX Upgrade employs a discharge control system DCS, whose core has been designed to meet these requirements. In the paper we will compare the scheduling schemes for the parallelised realisation of a control workflow and show the advantage of a data-driven workflow over a managed workflow. The data-driven workflow as used in DCS is based on signals connecting process outputs and inputs. These are implemented as real-time streams of data samples

  9. Shape, size, velocity and field-aligned currents of dayside plasma injections: a multi-altitude study

    Directory of Open Access Journals (Sweden)

    A. Marchaudon

    2009-03-01

    Full Text Available On 20 February 2005, Cluster in the outer magnetosphere and Double Star-2 (TC-2 at mid-altitude are situated in the vicinity of the northern cusp/mantle, with Cluster moving sunward and TC-2 anti-sunward. Their magnetic footprints come very close together at about 15:28 UT, over the common field-of-view of SuperDARN radars. Thanks to this conjunction, we determine the velocity, the transverse sizes, perpendicular and parallel to this velocity, and the shape of three magnetic flux tubes of magnetosheath plasma injection. The velocity of the structures determined from the Cluster four-spacecraft timing analysis is almost purely antisunward, in contrast with the antisunward and duskward convection velocity inside the flux tubes. The transverse sizes are defined from the Cluster-TC-2 separation perpendicular to the magnetic field, and from the time spent by a Cluster spacecraft in one structure; they are comprised between 0.6 and 2 RE in agreement with previous studies. Finally, using a comparison between the eigenvectors deduced from a variance analysis of the magnetic perturbation at the four Cluster and at TC-2, we show that the upstream side of the injection flux tubes is magnetically well defined, with even a concave front for the third one giving a bean-like shape, whereas the downstream side is far more turbulent. We also realise the first quantitative comparison between field-aligned currents at Cluster calculated with the curlometer technique and with the single-spacecraft method, assuming infinite parallel current sheets and taking into account the velocity of the injection flux tubes. The results agree nicely, confirming the validity of both methods. Finally, we compare the field-aligned current distribution of the three injection flux tubes at the altitudes of Cluster and TC-2. Both profiles are fairly similar, with mainly a pair of opposite field-aligned currents, upward at low-latitude and downward at high-latitude. In terms of

  10. Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

    International Nuclear Information System (INIS)

    Dantus, Marcos

    2008-01-01

    Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated molecules under intense laser fields, behavior of condensed phase matter under intense laser field and implications on micromachining with ultrashort pulses, coherent control of nanoparticles their surface plasmon waves and their nonlinear optical behavior, and observation of coherent Coulomb explosion processes at 10 16 W/cm 2 . In all, the research has resulted in 36 publications (five journal covers) and nine invention disclosures, five of which have continued on to patenting

  11. Real-time control of the plasma density profile on ASDEX upgrade

    International Nuclear Information System (INIS)

    Mlynek, Alexander

    2010-01-01

    The tokamak concept currently is the most promising approach to future power generation by controlled thermonuclear fusion. The spatial distribution of the particle density in the toroidally confined fusion plasma is of particular importance. This thesis work therefore focuses on the question as to what extent the shape of the density profile can be actively controlled by a feedback loop in the fusion experiment ASDEX Upgrade. There are basically two essential requirements for such feedback control of the density profile, which has been experimentally demonstrated within the scope of this thesis work: On the one hand, for this purpose the density profile must be continuously calculated under real-time constraints during a plasma discharge. The calculation of the density profile is based on the measurements of a sub-millimeter interferometer, which provides the line-integrated electron density along 5 chords through the plasma. Interferometric density measurements can suffer from counting errors by integer multiples of 2π when detecting the phase difference between a probing and a reference beam. As such measurement errors have severe impact on the reconstructed density profile, one major part of this work consists in the development of new readout electronics for the interferometer, which allows for detection of such measurement errors in real-time with high reliability. A further part of this work is the design of a computer algorithm which reconstructs the spatial distribution of the plasma density from the line-integrated measurements. This algorithm has to be implemented on a computer which communicates the measured data to other computers in real-time, especially to the tokamak control system. On the other hand, a second fundamental requirement for the successful implementation of a feedback controller is the identification of at least one actuator which enables a modification of the density profile. Here, electron cyclotron resonance heating (ECRH) has been

  12. Cold Plasmas for Biofilm Control: Opportunities and Challenges.

    Science.gov (United States)

    Gilmore, Brendan F; Flynn, Padrig B; O'Brien, Séamus; Hickok, Noreen; Freeman, Theresa; Bourke, Paula

    2018-06-01

    Bacterial biofilm infections account for a major proportion of chronic and medical device associated infections in humans, yet our ability to control them is compromised by their inherent tolerance to antimicrobial agents. Cold atmospheric plasma (CAP) represents a promising therapeutic option. CAP treatment of microbial biofilms represents the convergence of two complex phenomena: the production of a chemically diverse mixture of reactive species and intermediates, and their interaction with a heterogeneous 3D interface created by the biofilm extracellular polymeric matrix. Therefore, understanding these interactions and physiological responses to CAP exposure are central to effective management of infectious biofilms. We review the unique opportunities and challenges for translating CAP to the management of biofilms. Copyright © 2018. Published by Elsevier Ltd.

  13. A Control Method of Current Type Matrix Converter for Plasma Control Coil Power Supply

    International Nuclear Information System (INIS)

    Shimada, K.; Matsukawa, M.; Kurihara, K.; Jun-ichi Itoh

    2006-01-01

    In exploration to a tokamak fusion reactor, the control of plasma instabilities of high β plasma such as neoclassical tearing mode (NTM), resistive wall mode (RWM) etc., is the key issue for steady-state sustainment. One of the proposed methods to avoid suppressing RWM is that AC current having a phase to work for reduction the RWM growth is generated in a coil (sector coil) equipped spirally on the plasma vacuum vessel. To stabilize RWM, precise and fast real-time feedback control of magnetic field with proper amplitude and frequency is necessary. This implies that an appropriate power supply dedicated for such an application is expected to be developed. A matrix converter as one of power supply candidates for this purpose could provide a solution The matrix converter, categorized in an AC/AC direct converter composed of nine bi-directional current switches, has a great feature that a large energy storage element is unnecessary in comparison with a standard existing AC/AC indirect converter, which is composed of an AC/DC converter and a DC/AC inverter. It is also advantageous in cost and size of its applications. Fortunately, a voltage type matrix converter has come to be available at the market recently, while a current type matrix converter, which is advantageous for fast control of the large-inductance coil current, has been unavailable. On the background above mentioned, we proposed a new current type matrix converter and its control method applicable to a power supply with fast response for suppressing plasma instabilities. Since this converter is required with high accuracy control, the gate control method is adopted to three-phase switching method using middle phase to reduce voltage and current waveforms distortion. The control system is composed of VME-bus board with DSP (Digital Signal Processor) and FPGA (Field Programmable Gate Array) for high speed calculation and control. This paper describes the control method of a current type matrix converter

  14. The shapes of bird beaks are highly controlled by nondietary factors.

    Science.gov (United States)

    Bright, Jen A; Marugán-Lobón, Jesús; Cobb, Samuel N; Rayfield, Emily J

    2016-05-10

    Bird beaks are textbook examples of ecological adaptation to diet, but their