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

Orain, F.; Hoelzl, M.; Mink, F.; Willensdorfer, M.; Bécoulet, M.; Dunne, M.; Günter, S.; Huijsmans, Gta Guido; Lackner, K.; Pamela, S.; Suttrop, W.; Viezzer, E.

doi:10.1063/1.5091843

Cited by 33 publications

(76 citation statements)

References 43 publications

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“…Unfortunately, the mechanism of the mode braking is unclear. Previous numerical studies [56] try to explain the mode braking with RMP induced electromagnetic torque [14]. The reduction of perpendicular electron flow is also observed in our modeling which is consistent with these studies.…”

Section: V-3 Locking Of Pbm With Rmpsupporting

confidence: 91%

“…It shows that RMP brakes PBMs and this is a prominent feature that distinguishes ELM suppression from mitigation. The sudden braking of edge localized mode after a transition from ELM mitigation to suppression was also observed in the experiments [65,66] and numerical study [56]. These modeling and experimental results may indicate that the ELM suppression regime consists of static saturated PBMs while they are of rotating in natural or mitigated ELMs.…”

Section: V-3 Locking Of Pbm With Rmpsupporting

confidence: 57%

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Nonlinear modeling of the effect of n = 2 resonant magnetic field perturbation on peeling-ballooning modes in KSTAR

et al. 2020

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The impact of n=2 resonant magnetic perturbation (RMP) on the pedestal and peeling-ballooning mode (PBM) is investigated using the nonlinear 3D MHD code JOREK. It is based on the reduced MHD equations (viscos-resistive MHD), and the experimental parameters from the RMP-driven Edge localized mode (ELM) suppression discharge in KSTAR. In this study, n=2 kink-peeling mode was triggered through nonlinear coupling with RMP, and the pedestal is degraded by increased radial transport due to both tearing and kink-peeling response. The ELM mitigation and suppression are observed when RMP of sufficient amplitude is applied. ELM suppression was characterized by spatial locking of mode structure. In the simulation, the ELM suppression is not only due to the degraded pedestal but is also related to the mode coupling between the PBMs and the RMP-induced mode at the plasma edge. The role of PBM locking in mode suppression is suggested in terms of mode coupling.

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Section: V-3 Locking Of Pbm With Rmpsupporting

confidence: 91%

Section: V-3 Locking Of Pbm With Rmpsupporting

confidence: 57%

Nonlinear modeling of the effect of n = 2 resonant magnetic field perturbation on peeling-ballooning modes in KSTAR

et al. 2020

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“…The article shows, that the PBMs can be mitigated and eventually suppressed by the application of the RMP fields of sufficient amplitude. Consistently with reference [240], a breaking of the mode rotation is seen in the suppressed state. Non-linear mode coupling plays an important role in the suppression, since the PBMs would be still unstable in the degraded plasma pedestal, when the 3D fields are removed from the simulation.…”

Section: Elm Control By Rmpssupporting

confidence: 88%

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

et al. 2021

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JOREK is a massively parallel fully implicit non-linear extended magneto-hydrodynamic (MHD) code for realistic tokamak X-point plasmas. It has become a widely used versatile simulation code for studying large-scale plasma instabilities and their control and is continuously developed in an international community with strong involvements in the European fusion research programme and ITER organization. This article gives a comprehensive overview of the physics models implemented, numerical methods applied for solving the equations and physics studies performed with the code. A dedicated section highlights some of the verification work done for the code. A hierarchy of different physics models is available including a free boundary and resistive wall extension and hybrid kinetic-fluid models. The code allows for flux-surface aligned iso-parametric finite element grids in single and double X-point plasmas which can be extended to the true physical walls and uses a robust fully implicit time stepping. Particular focus is laid on plasma edge and scrape-off layer (SOL) physics as well as disruption related phenomena. Among the key results obtained with JOREK regarding plasma edge and SOL, are deep insights into the dynamics of edge localized modes (ELMs), ELM cycles, and ELM control by resonant magnetic perturbations, pellet injection, as well as by vertical magnetic kicks. Also ELM free regimes, detachment physics, the generation and transport of impurities during an ELM, and electrostatic turbulence in the pedestal region are investigated. Regarding disruptions, the focus is on the dynamics of the thermal quench (TQ) and current quench triggered by massive gas injection and shattered pellet injection, runaway electron (RE) dynamics as well as the RE interaction with MHD modes, and vertical displacement events. Also the seeding and suppression of tearing modes (TMs), the dynamics of naturally occurring TQs triggered by locked modes, and radiative collapses are being studied.

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“…1 This method was first demonstrated in DIII-D 2 and thereafter observed on several tokamaks worldwide. [3][4][5][6][7][8][9] Various models have been proposed to explain the causes of ELM suppression, [10][11][12][13] however important characteristics of ELM suppression remain unexplained. One characteristic of ELM suppression in DIII-D low collisionality (ν * e <0.5) ITER-similar-shape (ISS) plasmas is the low pedestal density n e,ped ≈ 2-3×10 19 m -3 required for access to ELM suppression.…”

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confidence: 99%

Multi-diagnostic analysis of plasma filaments in the island divertor

Zoletnik

Anda

Biedermann

et al. 2019

Plasma Phys. Control. Fusion

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Filaments or blobs are well known structures in turbulence in magnetic fusion devices, they are considered to be the major cross-transport channel in the scrape off layer. They originate at the last closed magnetic flux surface and propagate out on the low field side of toroidal devices due to polarization in the curved magnetic field. The Wendelstein 7-X stellarator has a complex three-dimensional magnetic field structure and additionally the plasma is bounded by a chain of magnetic islands, forming an island divertor. After the first observation of filaments in Wendelstein 7-X with video cameras a multi-diagnostic study is presented in this paper to reveal their 3D structure and dynamics. Filaments are seen to be born at the edge and, at least in some cases, seen to extend to up to 4 toroidal turns. After moving radially out a few cm they enter the edge island. Here they disappear from the equatorial plane and about 200 microseconds later reappear on the outboard side of the island. A long-wavelength (∼20–30 cm) quasi coherent mode is observed in both regions where filaments appear. The similarities and differences between the filaments seen in W7-X and other devices are discussed. Possible explanations for this strange radial propagation are considered, together with the likely role of filaments in the edge and island density profile.

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

Cited by 33 publications

References 43 publications

Nonlinear modeling of the effect of n = 2 resonant magnetic field perturbation on peeling-ballooning modes in KSTAR

Nonlinear modeling of the effect of n = 2 resonant magnetic field perturbation on peeling-ballooning modes in KSTAR

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

Multi-diagnostic analysis of plasma filaments in the island divertor

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