Study on pedestal fluctuations in H-modes without large ELMs during the transition to a detached tungsten divertor in EAST

Yang, Yong; Chen, Ran; Xu, Guo Sheng; Wang, Liang; Guo, Heng; Zhou, Chu; Wang, Yifeng; Xu, Jichan; Lin, Xin; Wang, Yumin; Zang, Qing; Duan, Yanmin; Zhang, Ling; Liu, Jianbin; Wu, Xuwen; Yang, Qian; Li, Gongshun; Wan, Baonian

doi:10.1088/1741-4326/ac33c7

Cited by 8 publications

(18 citation statements)

References 80 publications

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“…In a large tokamak fusion reactor in the H-mode regime, edgelocalized modes (ELMs) are considered one of the critical issues because of the large ELM heat load which can melt divertor plates [1]. Hence, it is necessary to establish reliable paths which realize suppression or mitigation of the ELMs [2,3]. The quiescent H-mode (QH-mode) [4,5] is a promising candidate which exhibits a stationary ELM-free H-mode with high confinement performance, such as H 89P and H 98y2 [6], with ITER and DEMO relevant plasma parameters; for example, the QH-mode is usually obtained under conditions of low pedestal collisionality ν * e < 0.3 with H 89P 2 and H 98y2 1 [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Stabilization of kink/peeling modes by coupled rotation and ion diamagnetic drift effects in quiescent H-mode plasmas in DIII-D and JT-60U

Aiba¹,

Chen²,

Kamiya³

et al. 2021

Nucl. Fusion

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Magnetohydrodynamic stability at the edge pedestal in several quiescent H-mode (QH-mode) plasmas in DIII-D and JT-60U experiments was analyzed by considering plasma rotation and ion diamagnetic drift effects. It was identified that a kink/peeling mode, which is a prime candidate for a trigger of edge harmonic oscillation in QH-mode, is stabilized by plasma rotation when considering the ion diamagnetic drift simultaneously in both experiments. The stabilizing effect by rotation becomes more effective in case using the rotation profile of the main ion species evaluated by assuming radial force balance. In addition, when inverting the rotation direction, it was found that the kink/peeling mode is more stabilized when considering the rotation of the main ion species, though the mode is less stabilized by the rotation of impurity ion species. The result implies that the kink/peeling mode stability in QH-mode plasmas is sensitive to how the rotation profile is evaluated, but it is shown that a qualitative trend stabilizing the kink/peeling mode by rotation can be reproduced with the poloidal rotation profile of an impurity predicted numerically based on the neoclassical theory.

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Section: Introductionmentioning

confidence: 99%

Stabilization of kink/peeling modes by coupled rotation and ion diamagnetic drift effects in quiescent H-mode plasmas in DIII-D and JT-60U

Aiba¹,

Chen²,

Kamiya³

et al. 2021

Nucl. Fusion

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“…As shown in figure 5(d), the APSD of the Mirnov coil in the ELMy phase without RMP exhibits a magnetic coherence mode around 20 kHz and a high-frequency mode (HFM) about 190 kHz. Note that both modes are usually observed in the H-mode plasma of EAST, and they have been investigated in previous publications [40][41][42]. In the ELM suppression phase, the APSD of the magnetic coil is much larger than the other two cases, especially in the frequency region below 30 kHz.…”

Section: Characteristics Of Edge Turbulencementioning

confidence: 76%

Edge turbulence transport during ELM suppression with n = 4 resonant magnetic perturbation on EAST

Liu

Liang

et al. 2023

Nucl. Fusion

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The edge turbulence characteristics and the induced radial transport have been investigated in ELM suppression by using the n= 4 RMP coils on EAST, with q_95= 3.6 and the electron collisionality ν_e^*≈ 0.5. During ELM suppression, the edge turbulence is enhanced dramatically, as measured by the reciprocating probe and the poloidal correlation reflectometry. In the near SOL, the low frequency turbulence (< 30 kHz) has a large fluctuation level and propagates along the ion diamagnetic drift direction with a speed of 0.35 km/s in the plasma frame; an n=1 electromagnetic mode around 120 kHz with a small k_θ (~ 0.15 cm-1) appears when the ELM is suppressed; weak broadband turbulence between 40-120 kHz propagates in the electron diamagnetic drift direction with a velocity of 3.4 km/s in the plasma frame. During the ELM suppression, the radial turbulent particle flux, calculated in both the time and frequency domains, is much higher (can be up to 5 times) than that in the inter-ELM phase. Furthermore, the low frequency turbulence (< 30 kHz) dominates the cross-field particle transport. The 120 kHz electromagnetic mode also contributes to outward particle flux, which is relatively small. A set of CGYRO simulations are performed to illustrate the nature of the 120 kHz electromagnetic mode and the low frequency turbulence, suggesting that the former is the MTM and the latter is the ITG mode. The bispectral analysis suggests a strong three-wave coupling between the low frequency and high frequency turbulence (> 250 kHz), which could be beneficial to form the observed turbulent transport. The estimated upstream cross-field particle flux is consistent with the total particle flux deposited on divertor targets, demonstrating that the enhanced radial turbulent particle transport is an important mechanism for particle exhaust in ELM suppression.

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“…ECM duration and frequency range can be obtained by positioning models. According to [17], the ECM relative amplitude (Amp) can be calculated in the ECM duration and frequency range, and it is averaged over time in this article. Stronger Amp can effectively suppress ELM while facilitating the effective discharge of plasma [18].…”

Section: Localization Resultsmentioning

confidence: 99%

Intelligent recognition and location of the edge coherence mode in EAST

Liu

Yang

et al. 2023

Plasma Phys. Control. Fusion

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In the study of multiple pedestal coherent modes in EAST, the high-precision intelligent recognition and location of the edge coherent modes (ECM) is a very meaningful work. In this study, a convolutional neural network (CNN) feature extraction model based on the attention mechanism was constructed to classify and localize the ECM in the EAST experiment. The classifier identified ECM on the test dataset with an accuracy of 0.970; the localizer detected the ECM with an average precision (AP) of 0.956. In addition, we found a strong correlation between the stored energy and current in plasma and the excitation of the ECM during EAST discharge; the triangularity may affect the relative amplitude of the ECM.

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Study on pedestal fluctuations in H-modes without large ELMs during the transition to a detached tungsten divertor in EAST

Cited by 8 publications

References 80 publications

Stabilization of kink/peeling modes by coupled rotation and ion diamagnetic drift effects in quiescent H-mode plasmas in DIII-D and JT-60U

Stabilization of kink/peeling modes by coupled rotation and ion diamagnetic drift effects in quiescent H-mode plasmas in DIII-D and JT-60U

Edge turbulence transport during ELM suppression with n = 4 resonant magnetic perturbation on EAST

Intelligent recognition and location of the edge coherence mode in EAST

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