Overview of Experiments with the Dynamic Ergodic Divertor on TEXTOR

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

doi:10.1002/ctpp.200610038

Cited by 20 publications

(22 citation statements)

References 23 publications

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“…Also, perturbations with n ≤ 3 can be toroidally rotated with a quasi-continuous phase, analogous to three phase current. This feature allows to improve diagnosis of the non-axisymmetric perturbed plasma with the existing sightlines by varying the toroidal phase, and hence achieve quasi 2D resolution of the existing measurements similar to measurements obtained with the TEXTOR Dynamic Ergodic Divertor [14]. Finally, the phase between Bu and A coils, and between Bl and A coils can be varied independently.…”

Section: Introductionmentioning

confidence: 99%

In-vessel saddle coils for MHD control in ASDEX Upgrade

Suttrop

Gruber

Günter

et al. 2009

Fusion Engineering and Design

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A set of 24 in-vessel saddle coils is planned for MHD control experiments in ASDEX Upgrade. These coils can produce static and alternating error fields for suppression of Edge Localised Modes, locked mode rotation control and, together with additional conducting wall elements, resistive wall mode excitation and feedback stabilisation experiments. All of these applications address critical physics issues for the operation of ITER. This extension is implemented in several stages, starting with two poloidally separated rings of eight toroidally distributed saddle coils above and below the outer midplane. In stages 2 and 3, eight midplane coils around the large vessel access ports and 12 AC power converters are added, respectively. Finally (stage 4), the existing passive stabilising loop (PSL), a passive conductor for vertical growth rate reduction, will be complemented by wall elements that allow helical current patterns to reduce the RWM growth rate for active control within the accessible bandwidth. The system is capable of producing error fields with toroidal mode number n = 4 for plasma edge ergodisation with core island width well below the neoclassical tearing mode seed island width even without rotational shielding. Phase variation between the three toroidal coil rings allows to create or avoid resonances with the plasma safety factor profile, in order to test the importance of resonances for ELM suppression.

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Section: Introductionmentioning

confidence: 99%

In-vessel saddle coils for MHD control in ASDEX Upgrade

Suttrop

Gruber

Günter

et al. 2009

Fusion Engineering and Design

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“…Externally applied magnetic perturbations that are pitchresonant with rational flux surfaces in the plasma boundary (resonant magnetic perturbations (RMPs)) have been used for decades to control boundary plasmas in toroidal magnetic confinement devices, including Pre-TEXT [1], TEXT [2], Tore Supra [3] and TEXTOR [4]. These experiments have been conducted mostly in circular, limiter tokamaks running ohmic or L-mode plasmas.…”

Section: Introductionmentioning

confidence: 99%

Measurement of plasma boundary displacement by n = 2 magnetic perturbations using imaging beam emission spectroscopy

Moyer¹,

Zeeland²,

Orlov³

et al. 2012

Nucl. Fusion

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Imaging beam emission spectroscopy has been used to study the displacement of the plasma boundary in ELMing H-mode discharges with a 10 Hz rotating n = 2 external magnetic field perturbation in DIII-D. The rotating magnetic field creates a helical displacement of the beam emission profile of ~2 cm on the low field side midplane which rotates with the applied RMP. This shift in the beam emission profile is due primarily to a shift in the electron density profile, which is independently measured to be 1.9 cm on the low field side midplane. These boundary displacements exceed calculations for the displacement of the stable and unstable manifolds formed by the interaction of the magnetic perturbation with the divertor separatrix by a factor of 4-5, suggesting that the vacuum field model doesn't correctly model the effect of the magnetic perturbations even near the separatrix. The measured displacements are suggestive of a non-resonant kink response.

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“…The ergodic divertor implemented in the TEXTOR tokamak, the Dynamic Ergodic Divertor (DED) [27][28][29], has dynamical features in addition to the conventional ones. It permits the operation with a rotating magnetic perturbation field, which allows not only to broaden the heating footprints to avoid hot spots on the divertor plates but also to actively influence the plasma rotation and MHD activities [30,31].…”

Section: Introductionmentioning

confidence: 99%

Modelling of magnetic field structure of the Ergodic Divertor of Tore Supra and comparison to the Dynamic Ergodic Divertor of TEXTOR

Abdullaev,

Van Rompuy,

Finken

et al. 2008

Preprint

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An analytical model previously developed to study the structure of the magnetic field for the TEXTOR-DED [S.S. Abdullaev et al. Phys. Plasmas, 6, 153 (1999)] is applied to the similar study of the Ergodic Divertor of Tore Supra tokamak [Ph. Ghendrih, Plasma Phys. Control. Fusion, 38, 1653(1996]. The coil configuration of ED Tore Supra consists of six modules equidistantly located along the toroidal direction on the low-field-side of the torus with given toroidal and poloidal extensions. The Hamiltonian formulation of field line equations in straight-field-line coordinates (Boozer coordinates) and the computationally efficient mapping method for integration of the Hamiltonian field line equations are used to study the magnetic field structure in the ED. Asymptotical formulas for the perturbation magnetic field created by the ED coils are obtained and the spectrum of magnetic perturbations is analyzed and compared with the one of the TEXTOR-DED. The structure of ergodic and laminar zones are studied by plotting Poincaré sections, so-called laminar plots (contour plots of wall to wall connection lengths) and magnetic footprints. The radial profiles of field line diffusion coefficients are calculated for different perturbation currents and it is found that for the Tore Supra case in the ergodic zone the numerical field line diffusion coefficients perfectly follow the quasilinear formula for smaller perturbation currents although the situation is different for the maximum perturbation current.

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Overview of Experiments with the Dynamic Ergodic Divertor on TEXTOR

Cited by 20 publications

References 23 publications

In-vessel saddle coils for MHD control in ASDEX Upgrade

In-vessel saddle coils for MHD control in ASDEX Upgrade

Measurement of plasma boundary displacement by n = 2 magnetic perturbations using imaging beam emission spectroscopy

Modelling of magnetic field structure of the Ergodic Divertor of Tore Supra and comparison to the Dynamic Ergodic Divertor of TEXTOR

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