Experimental identification of edge temperature ring oscillation and alternating turbulence transitions near the pedestal top for sustaining stationary I-mode

Liu, A.D.; Zou, X. L.; Han, Mingkun; Wang, T.B.; Zhou, C.; Wang, M.Y.; Duan, Yanmin; Verdoolaege, Geert; Dong, J. Q.; Wang, Z.X.; Xi, Fu; Xie, Jinlin; Zhuang, G.; Ding, Weixing; Zhang, S.B.; Liu, Y.; Liu, H.Q.; Wang, L.; Li, Y.Y.; Wang, Y. M.; Lyu, Bo; Hu, G.H.; Zhang, Qiaofeng; Wang, S.X.; Zhao, Hailin; Qu, Chengming; Liu, Z.X.; Zhang, Jun; Ji, J.; Zhong, Xing; Lan, Tao; Li, H.; Mao, Wenzhe; Liu, W.D.

doi:10.1088/1741-4326/abb14a

Cited by 17 publications

(34 citation statements)

References 34 publications

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“…Figure 3 illustrates the temporal evolutions of turbulence spectrum measured by Doppler reflectometry, along with the intensity of ion diamagnetic drift turbulence (IT) and electron diamagnetic drift turbulence (ET). From [14], the ETRO is found to accompany by alternating turbulence transitions between ET and IT, which can be also clearly observed from figure 3(a). The dominant turbulence mode was found to alternate between ET and IT, as IT intensity (blue) valley well corresponded to the peak of ET intensity (red).…”

Section: I-mode Characteristics In Helium Plasmasupporting

confidence: 61%

“…The stationary I-mode lasts from 2.65 s to 8 s, which is only limited by the EC heating power duration. The power spectra of turbulence rotation velocity show the ETRO mode of ∼13 kHz at all three radial locations of ρ ∼ 0.89 (red), ρ ∼ 0.95 (blue) and ρ ∼ 0.97 (black) in figure 2(c), indicating identical microscopic physics mechanism sustaining stationary I-mode for both He and D plasmas [14]. However, the 30-90 kHz mode only appears in the power spectra at ρ ∼ 0.89 and ρ ∼ 0.95, confirming itself as the WCM.…”

Section: I-mode Characteristics In Helium Plasmamentioning

confidence: 76%

“…The WCM on EAST is located within a certain radial extent (2-3 cm) at the plasma edge. A novel microscopic physics mechanism that can sustain stationary I-mode in D plasma has been recently reported on EAST [14], which sheds a light on the development of a long pulse high confinement I-mode scenario foreseen for future fusion devices, such as ITER and CFETR.…”

Section: Introductionmentioning

confidence: 98%

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I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

Zhang¹,

Gong²,

Qian³

et al. 2021

Nucl. Fusion

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The characteristics of I-mode operation in helium (He) plasma with radio-frequency (RF) wave heating and ITER-like tungsten divertor have been investigated for the first time on EAST, under the favorable B T configuration. Stationary I-mode in He plasma lasting for ∼5.4 s was achieved at I p = 0.5 MA, B T = 2.4 T with a total injected RF power of 3.5 MW, along with the appearance of the 30–90 kHz weakly coherent mode and the ∼13 kHz edge temperature ring oscillation. The pulse length was only limited by the heating power duration. He concentration was found to play a critical role in I-mode operation, as L–I transition threshold power was increased and the energy confinement was degraded with increasing He concentration. The experimental investigation result on energy confinement and divertor heat flux between I- and H-mode plasma was also given at a similar He concentration.

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Section: I-mode Characteristics In Helium Plasmasupporting

confidence: 61%

Section: I-mode Characteristics In Helium Plasmamentioning

confidence: 76%

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

Zhang¹,

Gong²,

Qian³

et al. 2021

Nucl. Fusion

Self Cite

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“…Recently, the stationary I-mode regime has been identified in EAST [29,30]. Similar with other devices, I-mode is always accompanied by the WCM with the frequency range of 40-150 kHz in the pedestal.…”

Section: Introductionmentioning

confidence: 58%

Characterization of pedestal burst instabilities during I-mode to H-mode transition in the EAST tokamak

et al. 2022

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Quasi-periodic Pedestal Burst Instabilities (PBIs), featuring alternative turbulence suppression and bursts, have been clearly identified by various edge diagnostics during I-mode to H-mode transition in the EAST Tokamak. The radial distribution of the phase perturbation caused by PBI shows that PBI is localized in the pedestal. Prior to each PBI, a significant increase of density gradient close to the pedestal top can be clearly distinguished, then the turbulence burst is generated, accompanied by the relaxation of the density profile, and then induces an outward particle flux. The relative density perturbation caused by PBIs is about 6 - 8%. Statistic analyses show that the pedestal normalized density gradient R/Ln triggering the first PBI has a threshold, mostly in the range of 22 − 24, suggesting that a PBI triggering instability could be driven by the density gradient. R/Ln triggering the last PBI is about 30 − 40 and seems to increase with the loss power and the chord-averaged density. In addition, the frequency of PBI is likely to be inversely proportional to the chord-averaged density and the loss power. These results suggest that PBIs and the density gradient prompt increase prior to PBIs can be considered as the precursor for controlling I-H transition.

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“…In the EAST tokamak, stationary I-mode is also identified by the weakly coherent mode (WCM) ( 29 ) and edge temperature ring oscillation (ETRO) ( 30 ). The ETRO, radially localized at the pedestal with an azimuthally symmetric structure, results from the ion/electron turbulence periodic transition.…”

Section: Resultsmentioning

confidence: 99%

Realization of thousand-second improved confinement plasma with Super I-mode in Tokamak EAST

et al. 2023

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Mastering nuclear fusion, which is an abundant, safe, and environmentally competitive energy, is a great challenge for humanity. Tokamak represents one of the most promising paths toward controlled fusion. Obtaining a high-performance, steady-state, and long-pulse plasma regime remains a critical issue. Recently, a big breakthrough in steady-state operation was made on the Experimental Advanced Superconducting Tokamak (EAST). A steady-state plasma with a world-record pulse length of 1056 s was obtained, where the density and the divertor peak heat flux were well controlled, with no core impurity accumulation, and a new high-confinement and self-organizing regime (Super I-mode = I-mode + e-ITB) was discovered and demonstrated. These achievements contribute to the integration of fusion plasma technology and physics, which is essential to operate next-step devices.

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Experimental identification of edge temperature ring oscillation and alternating turbulence transitions near the pedestal top for sustaining stationary I-mode

Cited by 17 publications

References 34 publications

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

I-mode operation in helium plasma with pure radio frequency wave heating and ITER-like tungsten divertor on EAST

Characterization of pedestal burst instabilities during I-mode to H-mode transition in the EAST tokamak

Realization of thousand-second improved confinement plasma with Super I-mode in Tokamak EAST

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