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22 results on '"de Bock, M F M"'

2. Transport and divertor properties of the dynamic ergodic divertor

Author

Lehnen, M., Abdullaev, S. S., Jachmich, S., Jakubowski, M. W., Jaspers, R., Koslowski, H. R., Krämer-Flecken, A., Kikuchi, Y., Liang, Y., Loozen, X., Pospieszczyk, A., van Rumpuy, T., Biel, W., Reiter, D., Samm, U., Schmitz, O., Sergienko, G., Tokar, M., Unterberg, B., Wolf, R., Zimmermann, O., de Bock, M. F. M., Brezinsek, S., Busch, C., Classen, I., Finken, K. H., Harting, D., and von Hellermann, M.

Subjects
Physics, Safety factor, Magnetic structure, Divertor, Magnetic confinement fusion, Laminar flow, Plasma, Condensed Matter Physics, Computational physics, Nuclear Energy and Engineering, Physics::Plasma Physics, Electromagnetic coil, ddc:530, Atomic physics, Excitation
Abstract

The concept of the dynamic ergodic divertor (DED) is based on plasma edge ergodization by a resonant perturbation. Such a divertor concept is closely related to helical or island divertors in stellerators. The base mode of the DED perturbation field can be m/n = 12/4, 6/2 or 3/1. The 3/1 base mode with its deep penetration of the perturbation field provides the excitation of tearing modes. This topic was presented elsewhere. In this contribution we concentrate on the divertor properties of the DED. We report on the characterization of the topology, transport properties in ergodic fields, impurity transport and density limit behaviour.The 12/4 base where the perturbation is restricted to the plasma edge is suitable for divertor operation. With increasing perturbation field island chains are built up at the resonance layers. Overlapping islands lead to ergodization. The plasma is guided in the laminar region via open field lines of short connection length to the divertor target. The magnetic topology is not only controlled by the coil current but especially by the edge safety factor. For appropriate edge safety factor we observe a strong temperature drop in the plasma edge, indicating an expansion of the laminar region, which is necessary to decouple the divertor plasma from the core plasma. The modifications of the magnetic topology can be directly seen, for example, from carbon emission lines. The magnetic structure is calculated by the ATLAS code and shows good agreement with the experimental findings.

Published
2005
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3. Motional Stark effect diagnostics for KSTAR

Author

Chung, Jinil, Ko, J, Howard, John, Michael, Clive, Von Nessi, Gregory, Thorman, Alexander, De Bock, M F M, Chung, Jinil, Ko, J, Howard, John, Michael, Clive, Von Nessi, Gregory, Thorman, Alexander, and De Bock, M F M

Abstract

The motional Stark effect (MSE) diagnostic is used to measure the radial magnetic pitch-angle profile in neutral-beam-heated plasmas. The diagnostic relies upon the measurement of the polarization direction of Stark-split D-alpha emission from injected fast neutral atoms in a magnetic field. Measurements of the magnetic pitch angle are used with magnetic equilibrium reconstruction codes such as EFIT to calculate the safety factor in shaped plasmas. The MSE diagnostic is important for determining the shape of the q profile to optimize confinement and stability, and it has become a key element in high-performance tokamaks. For the purpose of achieving the high-performance operating region in the Korea Superconducting Tokamak Advanced Research KSTAR device, two types of methods are being studied. In KSTAR, a multichord PEM (photo-elastic modulator)-based MSE system is being developed, and an imaging MSE polarimetry system using the coherence imaging technique has been showing promising initial results during the last two KSTAR experimental campaigns in 2012 and 2013, respectively. In this paper, we describe the progress of the KSTAR MSE diagnostics.

Published
2014

5. Overview of physics results from MAST towards ITER/DEMO and the MAST Upgrade

Author

Meyer, H., Abel, I. G., Akers, R. J., Allan, A., Allan, S. Y., Appel, L. C., Asunta, O., Barnes, M., Barratt, N. C., Ben Ayed, N., Bradley, J. W., Canik, J., Cahyna, P., Cecconello, Marco, Challis, C. D., Chapman, I. T., Ciric, D., Colyer, G., Conway, N. J., Cox, M., Crowley, B. J., Cowley, S. C., Cunningham, G., Danilov, A., Darke, A., De Bock, M. F. M., De Temmerman, G., Dendy, R. O., Denner, P., Dickinson, D., Dnestrovsky, A. Y., Dnestrovsky, Y., Driscoll, M. D., Dudson, B., Dunai, D., Dunstan, M., Dura, P., Elmore, S., Field, A. R., Fishpool, G., Freethy, S., Fundamenski, W., Garzotti, L., Ghim, Y. C., Gibson, K. J., Gryaznevich, M. P., Harrison, J., Havlickova, E., Hawkes, N. C., Heidbrink, W. W., Hender, T. C., Highcock, E., Higgins, D., Hill, P., Hnat, B., Hole, M. J., Horacek, J., Howell, D. F., Imada, K., Jones, O., Kaveeva, E., Keeling, D., Kirk, A., Kocan, M., Lake, R. J., Lehnen, M., Leggate, H. J., Liang, Y., Lilley, M. K., Lisgo, S. W., Liu, Y. Q., Lloyd, B., Maddison, G. P., Mailloux, J., Martin, R., McArdle, G. J., McClements, K. G., McMillan, B., Michael, C., Militello, F., Molchanov, P., Mordijck, S., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naulin, V., Naylor, G., Nielsen, A. H., O'Brien, M. R., O'Gorman, T., Pamela, S., Parra, F. I., Patel, A., Pinches, S. D., Price, M. N., Roach, C. M., Robinson, J. R., Romanelli, M., Rozhansky, V., Saarelma, S., Sangaroon, S., Saveliev, A., Scannell, R., Seidl, J., Sharapov, S. E., Schekochihin, A. A., Shevchenko, V., Shibaev, S., Stork, D., Storrs, J., Sykes, A., Tallents, G. J., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Turnyanskiy, M. R., Valovic, M., Vann, R. G. L., Verwichte, E., Voskoboynikov, P., Voss, G., Warder, S. E. V., Wilson, H. R., Wodniak, I., Zoletnik, S., Zagorski, R., Meyer, H., Abel, I. G., Akers, R. J., Allan, A., Allan, S. Y., Appel, L. C., Asunta, O., Barnes, M., Barratt, N. C., Ben Ayed, N., Bradley, J. W., Canik, J., Cahyna, P., Cecconello, Marco, Challis, C. D., Chapman, I. T., Ciric, D., Colyer, G., Conway, N. J., Cox, M., Crowley, B. J., Cowley, S. C., Cunningham, G., Danilov, A., Darke, A., De Bock, M. F. M., De Temmerman, G., Dendy, R. O., Denner, P., Dickinson, D., Dnestrovsky, A. Y., Dnestrovsky, Y., Driscoll, M. D., Dudson, B., Dunai, D., Dunstan, M., Dura, P., Elmore, S., Field, A. R., Fishpool, G., Freethy, S., Fundamenski, W., Garzotti, L., Ghim, Y. C., Gibson, K. J., Gryaznevich, M. P., Harrison, J., Havlickova, E., Hawkes, N. C., Heidbrink, W. W., Hender, T. C., Highcock, E., Higgins, D., Hill, P., Hnat, B., Hole, M. J., Horacek, J., Howell, D. F., Imada, K., Jones, O., Kaveeva, E., Keeling, D., Kirk, A., Kocan, M., Lake, R. J., Lehnen, M., Leggate, H. J., Liang, Y., Lilley, M. K., Lisgo, S. W., Liu, Y. Q., Lloyd, B., Maddison, G. P., Mailloux, J., Martin, R., McArdle, G. J., McClements, K. G., McMillan, B., Michael, C., Militello, F., Molchanov, P., Mordijck, S., Morgan, T., Morris, A. W., Muir, D. G., Nardon, E., Naulin, V., Naylor, G., Nielsen, A. H., O'Brien, M. R., O'Gorman, T., Pamela, S., Parra, F. I., Patel, A., Pinches, S. D., Price, M. N., Roach, C. M., Robinson, J. R., Romanelli, M., Rozhansky, V., Saarelma, S., Sangaroon, S., Saveliev, A., Scannell, R., Seidl, J., Sharapov, S. E., Schekochihin, A. A., Shevchenko, V., Shibaev, S., Stork, D., Storrs, J., Sykes, A., Tallents, G. J., Tamain, P., Taylor, D., Temple, D., Thomas-Davies, N., Thornton, A., Turnyanskiy, M. R., Valovic, M., Vann, R. G. L., Verwichte, E., Voskoboynikov, P., Voss, G., Warder, S. E. V., Wilson, H. R., Wodniak, I., Zoletnik, S., and Zagorski, R.

Abstract

New diagnostic, modelling and plant capability on the Mega Ampere Spherical Tokamak (MAST) have delivered important results in key areas for ITER/DEMO and the upcoming MAST Upgrade, a step towards future ST devices on the path to fusion currently under procurement. Micro-stability analysis of the pedestal highlights the potential roles of micro-tearing modes and kinetic ballooning modes for the pedestal formation. Mitigation of edge localized modes (ELM) using resonant magnetic perturbation has been demonstrated for toroidal mode numbers n = 3, 4, 6 with an ELM frequency increase by up to a factor of 9, compatible with pellet fuelling. The peak heat flux of mitigated and natural ELMs follows the same linear trend with ELM energy loss and the first ELM-resolved T-i measurements in the divertor region are shown. Measurements of flow shear and turbulence dynamics during L-H transitions show filaments erupting from the plasma edge whilst the full flow shear is still present. Off-axis neutral beam injection helps to strongly reduce the redistribution of fast-ions due to fishbone modes when compared to on-axis injection. Low-k ion-scale turbulence has been measured in L-mode and compared to global gyro-kinetic simulations. A statistical analysis of principal turbulence time scales shows them to be of comparable magnitude and reasonably correlated with turbulence decorrelation time. T-e inside the island of a neoclassical tearing mode allow the analysis of the island evolution without assuming specific models for the heat flux. Other results include the discrepancy of the current profile evolution during the current ramp-up with solutions of the poloidal field diffusion equation, studies of the anomalous Doppler resonance compressional Alfven eigenmodes, disruption mitigation studies and modelling of the new divertor design for MAST Upgrade. The novel 3D electron Bernstein synthetic imaging shows promising first data sensitive to the edge current profile and flows.

Published
2013
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6. L-H transition and pedestal studies on MAST

Author

Meyer, H, De Bock, M F M, Conway, N J, Freethy, S, Gibson, K J, Hiratsuka, J., Kirk, A., Michael, Clive, Morgan, T., Scannell, R, Naylor, G, Saarelma, S., Saveliev, A, Shevchenko, V, Suttrop, W., Temple, D., Vann, R G L, MAST Team, The, Meyer, H, De Bock, M F M, Conway, N J, Freethy, S, Gibson, K J, Hiratsuka, J., Kirk, A., Michael, Clive, Morgan, T., Scannell, R, Naylor, G, Saarelma, S., Saveliev, A, Shevchenko, V, Suttrop, W., Temple, D., Vann, R G L, and MAST Team, The

Abstract

On MAST studies of the profile evolution of the electron temperature (Te), electron density (ne), radial electric field (Er) as well as novel measurements of the ion temperature (Ti) and toroidal current density (jø) in the pedestal region allow further

Published
2011

7. The MAST motional Stark effect diagnostic

Author

Conway, N. J., De Bock, M. F. M., Michael, C. A., Walsh, M. J., Carolan, P. G., Hawkes, N. C., Rachlew, Elisabeth, McCone, J. F. G., Shibaev, S., Wearing, G., Conway, N. J., De Bock, M. F. M., Michael, C. A., Walsh, M. J., Carolan, P. G., Hawkes, N. C., Rachlew, Elisabeth, McCone, J. F. G., Shibaev, S., and Wearing, G.

Abstract

A motional Stark effect (MSE) diagnostic is now installed and operating routinely on the MAST spherical tokamak, with 35 radial channels, spatial resolution of similar to 2.5 cm, and time resolution of similar to 1 ms at angular noise levels of similar to 0.5 degrees. Conventional (albeit very narrow) interference filters isolate pi or sigma polarized emission. Avalanche photodiode detectors with digital phase-sensitive detection measure the harmonics of a pair of photoelastic modulators operating at 20 and 23 kHz, and thus the polarization state. The pi component is observed to be significantly stronger than sigma, in reasonably good agreement with atomic physics calculations, and as a result, almost all channels are now operated on pi. Trials with a wide filter that admits the entire Stark pattern (relying on the net polarization of the emission) have demonstrated performance almost as good as the conventional channels. MSE-constrained equilibrium reconstructions can readily be produced between pulses., QC 20101214

Published
2010
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9. Motional Stark Effect Diagnostic on TEXTOR

Author

Jakubowska, Katarzyna, De Bock, M. F. M., Jaspers, Roger, Von Hellermann, M. G., Shmaenok, Leonid A., Jakubowska, Katarzyna, De Bock, M. F. M., Jaspers, Roger, Von Hellermann, M. G., and Shmaenok, Leonid A.

Abstract

A motional Stark effect diagnostic at the tokamak TEXTOR has been constructed and brought recently into operation. In contrast to diagnostics used on other tokamaks, this diagnostic reveals the direction of the magnetic field from the intensity ratio of the pi and sigma components of the emitted Balmer-alpha and not from a polarization measurement of a single line. Moreover, the complete spectrum is measured which allows determining the radial position of the measurement, and in principle the radial electric field., QC 20101116

Published
2004
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10. The MAST motional Stark effect diagnostic

Author

Conway, N. J., primary, De Bock, M. F. M., additional, Michael, C. A., additional, Walsh, M. J., additional, Carolan, P. G., additional, Hawkes, N. C., additional, Rachlew, E., additional, McCone, J. F. G., additional, Shibaev, S., additional, and Wearing, G., additional

Published
2010
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12. Improved Confinement due to Open Ergodic Field Lines Imposed by the Dynamic Ergodic Divertor in TEXTOR

Author

Finken, K. H., primary, Abdullaev, S. S., additional, Jakubowski, M. W., additional, de Bock, M. F. M., additional, Bozhenkov, S., additional, Busch, C., additional, von Hellermann, M., additional, Jaspers, R., additional, Kikuchi, Y., additional, Krämer-Flecken, A., additional, Lehnen, M., additional, Schega, D., additional, Schmitz, O., additional, Spatschek, K. H., additional, Unterberg, B., additional, Wingen, A., additional, Wolf, R. C., additional, and Zimmermann, O., additional

Published
2007
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13. Overview of Experiments with the Dynamic Ergodic Divertor on TEXTOR

Author

Finken, K. H., primary, Abdullaev, S., additional, Biel, W., additional, de Bock, M. F. M., additional, Brezinsek, S., additional, Busch, C., additional, Classen, I., additional, Harting, D., additional, von Hellermann, M., additional, Jachmich, S., additional, Jakubowski, M., additional, Jaspers, R., additional, Koslowski, H. R., additional, Krämer-Flecken, A., additional, Kikuchi, Y., additional, Lehnen, M., additional, Liang, Y., additional, Kobayashi, M., additional, Nicolai, A., additional, Pospieszczyk, A., additional, Reiter, D., additional, Van Rompuy, T., additional, Samm, U., additional, Schmitz, O., additional, Sergienko, G., additional, Unterberg, B., additional, Westerhof, E., additional, Wolf, R. C., additional, and Zimmermann, O., additional

Published
2006
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14. Forced Magnetic Reconnection and Field Penetration of an Externally Applied Rotating Helical Magnetic Field in the TEXTOR Tokamak

Author

Kikuchi, Y., primary, de Bock, M. F. M., additional, Finken, K. H., additional, Jakubowski, M., additional, Jaspers, R., additional, Koslowski, H. R., additional, Kraemer-Flecken, A., additional, Lehnen, M., additional, Liang, Y., additional, Matsunaga, G., additional, Reiser, D., additional, Wolf, R. C., additional, and Zimmermann, O., additional

Published
2006
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15. Background and Initial Experiments with the Dynamic Ergodic Divertor on TEXTOR

Author

Finken, K. H., primary, Abdullaev, S. S., additional, De Bock, M. F. M., additional, Giesen, B., additional, von Hellermann, M., additional, Hogeweij, G. M. D., additional, Jakubowski, M., additional, Jaspers, R., additional, Kobayashi, M., additional, Koslowski, H. R., additional, Lehnen, M., additional, Matsunaga, G., additional, Neubauer, O., additional, Pospieszczyk, A., additional, Samm, U., additional, Schweer, B., additional, and Wolf, R., additional

Published
2005
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16. Overview of Core Diagnostics for TEXTOR

Author

Donné, A. J. H., primary, de Bock, M. F. M., additional, Classen, I. G. J., additional, Von Hellermann, M. G., additional, Jakubowska, K., additional, Jaspers, R., additional, Barth, C. J., additional, Van Der Meiden, H. J., additional, Oyevaar, T., additional, Van De Pol, M. J., additional, Varshney, S. K., additional, Bertschinger, G., additional, Biel, W., additional, Busch, C., additional, Finken, K. H., additional, Koslowski, H. R., additional, KrÄmer-Flecken, A., additional, Kreter, A., additional, Liang, Y., additional, Oosterbeek, H., additional, Zimmermann, O., additional, Telesca, G., additional, Verdoolaege, G., additional, Domier, C. W., additional, Luhmann, N. C., additional, Mazzucato, E., additional, Munsat, T., additional, Park, H., additional, Kantor, M., additional, Kouprienko, D., additional, Alexeev, A., additional, Ohdachi, S., additional, Korsholm, S., additional, Woskov, P., additional, Bindslev, H., additional, Meo, F., additional, Michelsen, P. K., additional, Michelsen, S., additional, Nielsen, S. K., additional, Tsakadze, E., additional, and Shmaenok, L., additional

Published
2005
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17. Toroidal Plasma Rotation Induced by the Dynamic Ergodic Divertor in the TEXTOR Tokamak

Author

Finken, K. H., primary, Abdullaev, S. S., additional, de Bock, M. F. M., additional, von Hellermann, M., additional, Jakubowski, M., additional, Jaspers, R., additional, Koslowski, H. R., additional, Krämer-Flecken, A., additional, Lehnen, M., additional, Liang, Y., additional, Nicolai, A., additional, Wolf, R. C., additional, Zimmermann, O., additional, de Baar, M., additional, Bertschinger, G., additional, Biel, W., additional, Brezinsek, S., additional, Busch, C., additional, Donné, A. J. H., additional, Esser, H. G., additional, Farshi, E., additional, Gerhauser, H., additional, Giesen, B., additional, Harting, D., additional, Hoekzema, J. A., additional, Hogeweij, G. M. D., additional, Hüttemann, P. W., additional, Jachmich, S., additional, Jakubowska, K., additional, Kalupin, D., additional, Kelly, F., additional, Kikuchi, Y., additional, Kirschner, A., additional, Koch, R., additional, Korten, M., additional, Kreter, A., additional, Krom, J., additional, Kruezi, U., additional, Lazaros, A., additional, Litnovsky, A., additional, Loozen, X., additional, Lopes Cardozo, N. J., additional, Lyssoivan, A., additional, Marchuk, O., additional, Matsunaga, G., additional, Mertens, Ph., additional, Messiaen, A., additional, Neubauer, O., additional, Noda, N., additional, Philipps, V., additional, Pospieszczyk, A., additional, Reiser, D., additional, Reiter, D., additional, Rogister, A. L., additional, Sakamoto, M., additional, Savtchkov, A., additional, Samm, U., additional, Schmitz, O., additional, Schorn, R. P., additional, Schweer, B., additional, Schüller, F. C., additional, Sergienko, G., additional, Spatschek, K. H., additional, Telesca, G., additional, Tokar, M., additional, Uhlemann, R., additional, Unterberg, B., additional, Van Oost, G., additional, Van Rompuy, T., additional, Van Wassenhove, G., additional, Westerhof, E., additional, Weynants, R., additional, Wiesen, S., additional, and Xu, Y. H., additional

Published
2005
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19. Ab initio modeling of the motional Stark effect on MAST.

Author

De Bock, M. F. M., Conway, N. J., Walsh, M. J., Carolan, P. G., and Hawkes, N. C.

Subjects
*STARK effect, *TOKAMAKS, *MAGNETIC fields, *CALIBRATION, *CURVATURE
Abstract

A multichord motional Stark effect (MSE) system has recently been built on the MAST tokamak. In MAST the π and σ lines of the MSE spectrum overlap due to the low magnetic field typical for present day spherical tokamaks. Also, the field curvature results in a large change in the pitch angle over the observation volume. The measured polarization angle does not relate to one local pitch angle but to an integration over all pitch angles in the observation volume. The velocity distribution of the neutral beam further complicates the measurement. To take into account volume effects and velocity distribution, an ab initio code was written that simulates the MSE spectrum on MAST. The code is modular and can easily be adjusted for other tokamaks. The code returns the intensity, polarized fraction, and polarization angle as a function of wavelength. Results of the code are presented, showing the effect on depolarization and wavelength dependence of the polarization angle. The code is used to optimize the design and calibration of the MSE diagnostic. [ABSTRACT FROM AUTHOR]

Published
2008
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20. The dynamic ergodic divertor in the TEXTOR tokamak: plasma response to dynamic helical magnetic field perturbations

Author

Finken, K H, Abdullaev, S S, Biel, W, de Bock, M F M, Busch, C, Farshi, E, von Hellermann, M, Hogeweij, G M D, Jakubowski, M, Jaspers, R, Koslowski, H R, Kraemer-Flecken, A, Lazaros, A, Lehnen, M, Liang, Y, Nicolai, A, Schmitz, O, Unterberg, B, Westerhof, E, Wolf, R, Zimmermann, O, de Baar, M, Bertschinger, G, Brezinsek, S, Classen, I G J, Donné, A J H, Esser, H G, Gerhauser, H, Giesen, B, Harting, D, Hoekzema, J A, Huettemann, P W, Jachmich, S, Jakubowska, K, Kalupin, D, Kelly, F, Kikuchi, Y, Kirschner, A, Koch, R, Korten, M, Kreter, A, Krom, J, Kruezi, U, Litnovsky, A, Loozen, X, Lopes Cardozo, N J, Lyssoivan, A, Marchuk, O, Mertens, Ph, Messiaen, A, Neubauer, O, Philipps, V, Pospieszczyk, A, Reiser, D, Reiter, D, Rogister, A L, Van Rompuy, T, Savtchkov, A, Samm, U, Schorn, R P, Schueller, F C, Schweer, B, Sergienko, G, Telesca, K H G, Tokar, M, Van Oost, G, Uhlemann, R, Van Wassenhove, G, Weynants, R, Wiesen, S, and Xu, Y

Abstract

Recently, the dynamic ergodic divertor (DED) of TEXTOR has been studied in an m/n= 3/1 set-up which is characterized by a relatively deep penetration of the perturbation field. The perturbation field creates (a) a helical divertor, (b) an ergodic pattern and/or (c) excitation of tearing modes, depending on whether the DED current is static, rotating in the co-current direction or in the counter-current direction. Characteristic divertor properties such as the high recycling regime or enhanced shielding have been studied. A strong effect of the ergodization is spin up of the plasma rotation, possibly due to the electric field at the plasma edge. Tearing modes are excited in a rather reproducible way and their excitation threshold value, their motion and their reduction due to the ECRH/ECCD have been studied. The different scenarios are characterized by strong modifications of the toroidal velocity profile and by a reduced or enhanced radial transport.

Published
2004
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21. Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect.

Author

De Bock, M. F. M., Citrin, J., Saarelma, S., Temple, D., Conway, N. J., Kirk, A., Meyer, H., and Michael, C. A.

Subjects
*STARK effect, *FUSION reactors, *PLASMA gases, *DENSITY currents, *TEMPERATURE, *SELF-consistent field theory, *STABILITY (Mechanics)
Abstract

Edge localized modes (ELMs), that are present in most tokamak H- (high confinement) modes, can cause significant damage to plasma facing components in fusion reactors. Controlling ELMs is considered necessary and hence it is vital to understand the underlying physics. The stability of ELMs is typically expressed in terms of the pressure gradient [?]p in the edge and the edge current density jph. Both [?]p and jph are usually derived from profiles fitted to the measured edge density and temperature profiles, where for the calculation of jph neoclassical theory is used.This paper presents direct measurements of the magnetic pitch angle gm evolution in the edge and the derived jph. These provide a method to validate the jph as derived with neoclassical theory and they open up the possibility to find a complete, self-consistent set of edge profiles, that fit density, temperature and gm measurements, hence allowing for a more accurate stability analysis. [ABSTRACT FROM AUTHOR]

Published
2012
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22. Experimental and theoretical analyses of penetration processes of externally applied rotating helical magnetic perturbation fields in TEXTOR and HYBTOK-II.

Author

Kikuchi, Y., de Bock, M. F. M., Finken, K. H., Jakubowski, M., Jaspers, R., Koslowski, H. R., Kraemer-Flecken, A., Lehnen, M., Liang, Y., Loewenbrueck, K., Matsunaga, G., Reiser, D., Samm, U., Sewell, G., Takamura, S., Unterberg, B., Wolf, R. C., Zimmermann, O., and TEXTOR-team, the

Abstract

Penetration processes of rotating helical magnetic perturbation field into tokamak plasmas have been investigated by the dynamic ergodic divertor (DED) in TEXTOR. Experimental observations of the field penetration and field amplification are performed and the data are interpreted by theoretical analyses based on a linearized two-fluid plasma model. It is observed that the growth of the forced magnetic reconnection by the rotating DED-field is accompanied by a change in the plasma fluid rotation. The theoretical model is also applied to the DED experiment in the small tokamak device HYBTOK-II. It is confirmed that the theoretical analyses can explain the observed radial profiles of the DED-field in the plasma by inserting small magnetic pick-up coils in HYBTOK-II. [ABSTRACT FROM AUTHOR]

Published
2007
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