Pedestal dynamics across low to high confinement regime in the HL-2A tokamak

Liang, Anshu; Zhong, W.L.; Zou, X. L.; Duan, X.R.; Yang, Z.C.; Wen, Jie; Xiao, Guoliang; Jiang, M.; Shi, Z.B.; Shi, Peng; Chen, W.; Song, X.M.; Yu, D.L.; Yan, L.W.; Liu, Y.; Qi, Yang; Dong, J. Q.; Ding, X.T.; Xu, M.; Team, Hl A

doi:10.1063/1.5013074

Cited by 15 publications

(25 citation statements)

References 36 publications

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“…r /∂r| are negligible [3]. Results on the ASDEX Upgrade also indicated that, in the pedestal region, E r is mainly determined by the ion pressure gradient, when the toroidal flow is negligibly small [6].…”

Section: Overview Of Hl-2a Recent Experimentsmentioning

confidence: 96%

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Overview of HL-2A recent experiments

Xu¹,

Duan²,

Liu³

et al. 2019

Nucl. Fusion

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ITER and to the advanced tokamak operation (e.g. the operation of future HL-2M), such as the access of H-mode, energetic particle physics, edge-localized mode (ELM) mitigation/suppression and disruption mitigation. Since the 2016 Fusion Energy Conference, the HL-2A team has focused on the investigations on the following areas: (i) pedestal dynamics and L-H transition, (ii) techniques of ELM control, (iii) the turbulence and transport, (iv) energetic particle physics. The HL-2A results demonstrated that the increase of mean E × B shear flow plays a key role in triggering L-I and I-H transitions. While the change of E × B flow is mainly induced by the ion pressure gradient. Both mitigation and suppression of ELMs were realized by laser blow-off (LBO) seeded impurity (Al, F e, W). The 30% N e mixture supersonic molecular beam injection (SMBI) seeding also robustly induced ELM mitigation. The ELMs were mitigated by low-hybrid current drive (LHCD). The stabilization of m/n=1/1 ion fishbone activities by electron cyclotron resonance heating (ECRH) was found on the HL-2A. A new m/n=2/1 ion fishbone activity was observed recently, and the modelling indicated that passing fast ions dominantly contribute to the driving of 2/1 fishbone. The non-linear coupling between toroidal Alfven eigenmode (TAE) and tearing mode (TM) leads to the generation of a high frequency mode with the toroidal mode number n=0. The turbulence is modulated by tearing mode when the island width exceeds a threshold and the modulation is localized merely in the inner area of the islands. Meanwhile, turbulence radially spreading takes place across the island region.

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Section: Overview Of Hl-2a Recent Experimentsmentioning

confidence: 96%

“…r and E v θ r denote the ion diamagnetic, toroidal velocity and poloidal velocity components of E r , respectively. Whist in p i component, the contribution from ion temperature gradient is dominant over that from density gradient [3].…”

Section: Overview Of Hl-2a Recent Experimentsmentioning

confidence: 99%

Overview of HL-2A recent experiments

Xu¹,

Duan²,

Liu³

et al. 2019

Nucl. Fusion

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“…The negative V θ indicates that the QCM propagates in the electron-diamagnetic drift direction in the laboratory frame. The plasma poloidal rotation at middle of pedestal is estimated to be about V p = 4.5 ~5.2 km s −1 in electron diamagnetic drift direction using the multi-channel Doppler reflectometry [25]. It is noted that the toroidal return flow might have some contributions to the poloidal motion of the mode due to the barber pole effect.…”

Section: Characteristics and The Nonlinear Coupling Of The Pedestal Qcmmentioning

confidence: 99%

Pedestal dynamics prior to type-III ELM onset on HL-2A tokamak*

et al. 2020

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A dramatic increase of density gradient and a slight decrease of electron temperature gradient were observed in the pedestal just prior to each onset in a series of ELM bursts. An inward particle flux induced by a quasi-coherent mode was found to be responsible for such changes. The characteristics of the quasi-coherent mode, including frequency, wave vector, propagation direction and velocity were identified. The nonlinear three-wave coupling is a plausible mechanism for the generation of the mode. Decoupling of the mode induced density transport from energy transport was discovered. The gradient of density was observed always much higher than that of temperature for electrons at the starting point of the ELM burst and, therefore, the dominant role of density gradient over electron temperature gradient for ELM onset is demonstrated. Consistence and contrast of the results with confinement and transport in I-mode discharges are discussed.

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“…2017; Liang et al. 2018; Cavedon et al. 2020), the full understanding of the physical mechanism for the enhanced plasma confinement in H-mode operation is an open issue.…”

Section: Introductionmentioning

confidence: 99%

Role of the edge electric field in the resonant mode-particle interactions and the formation of transport barriers in toroidal plasmas

Anastassiou,

Zestanakis,

Antonenas

et al. 2024

J. Plasma Phys.

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The impact of an edge radial electric field on the particle orbits and the orbital spectrum in an axisymmetric toroidal magnetic equilibrium is investigated using a guiding centre canonical formalism. Poloidal and bounce/transit-averaged toroidal precession frequencies are calculated, highlighting the role of the radial electric field. The radial electric field is shown to drastically modify the resonance conditions between particles with certain kinetic characteristics and specific perturbative non-axisymmetric modes, and to enable the formation of transport barriers. The locations of the resonances and the transport barriers that determine the particle, energy and momentum transport are shown to be accurately pinpointed in the phase space by employing the calculated orbital frequencies.

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Pedestal dynamics across low to high confinement regime in the HL-2A tokamak

Cited by 15 publications

References 36 publications

Overview of HL-2A recent experiments

Overview of HL-2A recent experiments

Pedestal dynamics prior to type-III ELM onset on HL-2A tokamak*

Role of the edge electric field in the resonant mode-particle interactions and the formation of transport barriers in toroidal plasmas

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