Non-linear modeling of the plasma response to RMPs in ASDEX Upgrade

Orain, F.; Hölzl, M.; Viezzer, E.; Dunne, M.; Bécoulet, M.; Cahyna, P.; Huijsmans, G. T. A.; Moralès, J.; Willensdorfer, M.; Suttrop, W.; Kirk, A.; Pamela, S.; Günter, S.; Lackner, K.; Strumberger, E.; Lessig, A.

doi:10.1088/0029-5515/57/2/022013

Cited by 62 publications

(82 citation statements)

References 49 publications

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“…Such a correlation has previously been obtained in the modelling of several tokamak devices 4,7,8,13,25 and will be further confirmed by the new results presented in this work. The role of the edge-peeling response in ELM suppression is less exploited in the previous work and is therefore one of the focusing points in this study.…”

Section: Introductionsupporting

confidence: 88%

“…In particular, the fluid model predicted optimal coil phasing, which maximizes the edge-peeling response, agrees well with the best achievable ELM mitigation in experiments. 33 This is confirmed by MARS-F, [10][11][12] NEMEC, 4 and JOREK 13 computations. In particular, systematic scans with varying edge safety factor 12,37 as well as plasma pressure 37 yield simple analytic fitting formulas for the optimal coil phasing, with varying plasma conditions.…”

Section: Modelling Elm Mitigation Experimentssupporting

confidence: 57%

“…Extensive modelling efforts have been devoted to understand and to interpret ELM control experiments. Most of the modelling work has been carried out for individual devices, for example, MAST, 7 DIII-D, 8,9 ASDEX Upgrade, [10][11][12][13] EAST, 14 and ITER. 7,[15][16][17] These activities were also reported in recent review articles.…”

Section: Introductionmentioning

confidence: 99%

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Comparative investigation of ELM control based on toroidal modelling of plasma response to RMP fields

Liu

Kirk

et al. 2017

Physics of Plasmas

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Extensive modelling efforts of the plasma response to the resonant magnetic perturbation fields, utilized for controlling the edge localized mode (ELM), help to identify the edge-peeling response as a key factor, which correlates to the observed ELM mitigation in several tokamak devices, including MAST, ASDEX Upgrade, EAST, and HL-2A. The recently observed edge safety factor window for ELM mitigation in HL-2A experiments is explained in terms of the edge-peeling response. The computed plasma response, based on toroidal single fluid resistive plasma model with different assumption of toroidal flows, is found generally larger in ELM suppressed cases as compared to that of the ELM mitigated cases, in ASDEX Upgrade and DIII-D. The plasma shaping, in particular, the plasma triangularity, contributes to the enhanced plasma response. But the shaping does not appear to be the sole factor-other factors such as the (higher) pedestal pressure and/or current can also lead to increased edge-peeling response.

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Section: Introductionsupporting

confidence: 88%

Section: Modelling Elm Mitigation Experimentssupporting

confidence: 57%

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Comparative investigation of ELM control based on toroidal modelling of plasma response to RMP fields

Liu

Kirk

et al. 2017

Physics of Plasmas

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“…The parameters used are similar to the one described in Ref. [21] and reproduce as accurately as possible the experimental situation. The main limitations of the modeling are the increased central resistivity η 0 = 8.1 × 10 −7 Ω.m (value one order of magnitude larger than the Spitzer value, but the T −3/2 e dependency is accounted for in the simulations, T e being the electron temperature) and the restriction of the simulations to the toroidal modes n ≤ 8 to limit their computational costs.…”

Section: A Experimental Configuration and Simulation Parametersmentioning

confidence: 99%

“…The electron perpendicular flow generate currents on resonant surfaces, which can induce a magnetic field opposite to the applied perturbation, resulting in a zero net perturbation penetrating in the plasma: RMPs are then screened. More recently, it was found that RMPs can also excite marginally stable peeling-kink modes at the plasma edge, capable to improve the RMP penetration [19][20][21].…”

mentioning

confidence: 99%

Non-linear modeling of the threshold between ELM mitigation and ELM suppression by resonant magnetic perturbations in ASDEX upgrade

et al. 2019

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The interaction between Edge Localized Modes (ELMs) and Resonant Magnetic Perturbations (RMPs) is modeled with the magnetohydrodynamic code JOREK using experimental parameters from ASDEX Upgrade discharges. According to the modeling, the ELM mitigation or suppression is optimal when the amplification of both tearing and peeling-kink responses result in a better RMP penetration. The ELM mitigation or suppression is not only due to the reduction of the pressure gradient, but predominantly arises from the toroidal coupling between the ELMs and the RMPinduced mode at the plasma edge, forcing the edge modes to saturate at a low level. The bifurcation from ELM mitigation to ELM suppression is observed when the RMP amplitude is increased. ELM mitigation is characterized by rotating modes at the edge, while the mode locking to RMPs is induced by the resonant braking of the electron perpendicular flow in the ELM suppression regime.

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Insights into type‐I edge localized modes and edge localized mode control from JOREK non‐linear magneto‐hydrodynamic simulations

Hoelzl

Huijsmans

Orain

et al. 2018

Contributions to Plasma Physics

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Edge localized modes (ELMs) are repetitive instabilities driven by the large pressure gradients and current densities in the edge of H‐mode plasmas. Type‐I ELMs lead to a fast collapse of the H‐mode pedestal within several hundred microseconds to a few milliseconds. Localized transient heat fluxes to divertor targets are expected to exceed tolerable limits for ITER, requiring advanced insights into ELM physics and applicable mitigation methods. This paper describes how non‐linear magneto‐hydrodynamic (MHD) simulations can contribute to this effort. The JOREK code is introduced, which allows the study of large‐scale plasma instabilities in tokamak X‐point plasmas covering the main plasma, the scrape‐off layer, and the divertor region with its finite element grid. We review key physics relevant for type‐I ELMs and show to what extent JOREK simulations agree with experiments and help reveal the underlying mechanisms. Simulations and experimental findings are compared in many respects for type‐I ELMs in ASDEX Upgrade. The role of plasma flows and non‐linear mode coupling for the spatial and temporal structure of ELMs is emphasized, and the loss mechanisms are discussed. An overview of recent ELM‐related research using JOREK is given, including ELM crashes, ELM‐free regimes, ELM pacing by pellets and magnetic kicks, and mitigation or suppression by resonant magnetic perturbation coils (RMPs). Simulations of ELMs and ELM control methods agree in many respects with experimental observations from various tokamak experiments. On this basis, predictive simulations become more and more feasible. A brief outlook is given, showing the main priorities for further research in the field of ELM physics and further developments necessary.

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Non-linear modeling of the plasma response to RMPs in ASDEX Upgrade

Cited by 62 publications

References 49 publications

Comparative investigation of ELM control based on toroidal modelling of plasma response to RMP fields

Comparative investigation of ELM control based on toroidal modelling of plasma response to RMP fields

Non-linear modeling of the threshold between ELM mitigation and ELM suppression by resonant magnetic perturbations in ASDEX upgrade

Insights into type‐I edge localized modes and edge localized mode control from JOREK non‐linear magneto‐hydrodynamic simulations

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