Studies of edge localized mode mitigation with new active in-vessel saddle coils in ASDEX Upgrade

Suttrop, W.; Barrera, L.; Herrmann, A.; McDermott, R. M.; Eich, T.; Fischer, R.; Kurzan, B.; Lang, P. T.; Mlynek, A.; Pütterich, T.; Rathgeber, S. K.; Rott, M.; Vierle, T.; Viezzer, E.; Willensdorfer, M.; Wolfrum, E.; Zammuto, I.

doi:10.1088/0741-3335/53/12/124014

Cited by 76 publications

(90 citation statements)

References 14 publications

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“…An overview over these experimental findings can be found in Refs. [8,9]. In this article we concentrate on a single configuration and document the results as much in detail as possible.…”

Section: Methodsmentioning

confidence: 99%

First EMC3-Eirene simulations of the impact of the edge magnetic perturbations at ASDEX Upgrade compared with the experiment

et al. 2012

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Abstract. The EMC3-Eirene code package was applied for the first time to simulate the edge plasma in an ASDEX Upgrade discharge, in which the newly installed magnetic perturbation coils were used to mitigate Edge Localized Modes (ELMs). Two different points in time during this discharge were simulated, the ELM mitigated phase after turning-on of the magnetic perturbation coils and, as a reference, the ELMy H-mode phase before. The results were compared to the measurements of various edge and divertor diagnostics. Assuming the main chamber profiles to be shifted by 15mm with respect to their calibrated positions, an agreement within a factor of 2 was found between the main chamber profiles outside the separatrix and those at the outer divertor target. The most important result is the observation of several maxima and minima in the particle flux and in particular in the power deposition pattern of both the simulation and the experiment for the case with magnetic perturbations, an effect also known as strike-point splitting.

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“…An overview over these experimental findings can be found in Refs. [8,9]. In this article we concentrate on a single configuration and document the results as much in detail as possible.…”

Section: Methodsmentioning

confidence: 99%

First EMC3-Eirene simulations of the impact of the edge magnetic perturbations at ASDEX Upgrade compared with the experiment

et al. 2012

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“…• [34]. Since there are 8 saddle coils in each row, the toroidal mode spectrum of the external MP-field exhibits a dominant n = 2 and weak n = 6, 10, 14, .…”

Section: Mp-coils and Edge Diagnosticsmentioning

confidence: 99%

Plasma response measurements of external magnetic perturbations using electron cyclotron emission and comparisons to 3D ideal MHD equilibrium

Willensdorfer

Denk

Strumberger

et al. 2016

Plasma Phys. Control. Fusion

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Abstract. The plasma response from an external n = 2 magnetic perturbation field in ASDEX Upgrade has been measured using mainly electron cyclotron emission (ECE) diagnostics and a rigid rotating field. To interpret ECE and ECE-imaging (ECE-I) measurements accurately, forward modeling of the radiation transport has been combined with ray tracing. The measured data is compared to synthetic ECE data generated from a 3D ideal magnetohydrodynamics (MHD) equilibrium calculated by VMEC.The measured amplitudes of the helical displacement around the low field side midplane are in reasonable agreement with the one from the synthetic VMEC diagnostics. Both exceed the prediction from the vacuum field calculations and indicate the presence of a kink response at the edge, which amplifies the perturbation. VMEC and MARS-F have been used to calculate the properties of this kink mode. The poloidal mode structure of the magnetic perturbation of this kink mode at the edge peaks at poloidal mode numbers larger than the resonant components |m| > |nq|, whereas the poloidal mode structure of its displacement is almost resonant |m| ≈ |nq|. This is expected from ideal MHD in the proximity of rational surfaces. The displacement measured by ECE-I confirms this resonant response.

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“…In H-mode plasmas with externally applied MPs (toroidal mode number = 2) ELM mitigation was observed above a critical edge density [68], corresponding typically to a fractional Greenwald density of , / ∼ 0.65, , being the pedestal electron density and the Greenwald density [69]. So far, ELM mitigation has been observed in plasmas with different shape, different heating mixes, different levels of heating power [70] and with MPs that are both resonant and non- resonant with the edge profile [68]. The experiment presented here was carried out specifically to test if there is an observable effect on the profile due to the MPs.…”

Section: Effect Of Magnetic Perturbations Onmentioning

confidence: 99%

High-accuracy characterization of the edge radial electric field at ASDEX Upgrade

et al. 2013

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Abstract. The installation of a new poloidal charge exchange recombination spectroscopy (CXRS) diagnostic at ASDEX Upgrade (AUG) has enabled the determination of the radial electric field, , using the radial force balance of impurity ions.has been derived from charge exchange (CX) spectra measured on different impurity species, such as He 2+ , B 5+ , C 6+ and Ne 10+ . The resulting profiles are found to be identical within the uncertainties regardless of the impurity species used, thus, demonstrating the validity of the diagnostic technique. The profile has been compared to the main ion pressure gradient term, which is found to be the dominant contribution at the plasma edge, thus, supporting that the well is created by the main ion species. The profile has been measured in different confinement regimes including L-, I-and H-mode. The depth of the well and the magnitude of the shear are correlated with the ion pressure at the pedestal top. The temporal evolution of the measured CX profiles and the resulting have been studied during an ELM cycle. At the ELM crash, the minimum is less deep resulting in a reduction of the E×B shear. Within 2 ms after the ELM crash, the edge kinetic profiles have nearly recovered and the well is observed to recover simultaneously. In high density type-I ELM mitigated H-mode plasmas, obtained via externally applied magnetic perturbations with toroidal mode number = 2, no clear effect on due to the magnetic perturbations has been observed.

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Studies of edge localized mode mitigation with new active in-vessel saddle coils in ASDEX Upgrade

Cited by 76 publications

References 14 publications

First EMC3-Eirene simulations of the impact of the edge magnetic perturbations at ASDEX Upgrade compared with the experiment

First EMC3-Eirene simulations of the impact of the edge magnetic perturbations at ASDEX Upgrade compared with the experiment

Plasma response measurements of external magnetic perturbations using electron cyclotron emission and comparisons to 3D ideal MHD equilibrium

High-accuracy characterization of the edge radial electric field at ASDEX Upgrade

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