Study of the spectrum effect on the threshold of resonant magnetic perturbation penetration on J-TEXT

Mao, Feiyue; Wang, Nengchao; Huang, Zhuo; Ren, Zhengkang; Zhou, Song; Shen, Chengshuo; Zhang, Xiaoyi; He, Ying; Zhang, Qi; Jia, Ruo; Zhao, Chuanxu; Li, Yangbo; Hu, Bo; Li, Da; Bala, Abba Alhaji; Chen, Zhipeng; Chen, Zhongyong; Yang, Zhoujun; Liang, Y.; Ding, Yonghua; Pan, Yuan

doi:10.1088/2058-6272/ac9f2e

Cited by 11 publications

(13 citation statements)

References 49 publications

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“…The phase of the RMP and the relative phase between 2/1 and 3/1 RMP components were not adjusted in these experiments. The intrinsic EF on J-TEXT is about 0.6 Gs [37]. Considering that the RMP current involved in this paper is small, the effect of EF may not be ignored.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Disruption avoidance by stabilizing coupled MHD modes using resonant magnetic perturbations on J-TEXT

He¹,

Wang²,

Ding³

et al. 2023

Plasma Phys. Control. Fusion

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The coupling of multiple MHD modes can lead to mode locking and major disruption in tokamak plasmas. In the J-TEXT tokamak, the coupling between two small modes, i.e., m/n = 2/1 and 3/1 modes (m and n are poloidal and toroidal mode numbers, respectively), appears when the edge safety factor is reduced to the vicinity of 3. After the mode coupling, the toroidal phase difference between the 2/1 and 3/1 modes equals 0 in the low field side midplane. This phase relation of coupled modes leads to mutual destabilization and even major disruption. A control scheme to avoid disruption caused by coupled modes by resonant magnetic perturbations (RMP) is presented. It is found that the application of RMP significantly changes the evolution of the coupled modes. The coupling of the 2/1 and 3/1 modes occurs earlier as the RMP amplitude increases. The RMP with moderate amplitude can suppress the growth of 2/1 and 3/1 coupled modes and hence avoid disruption. These results provide a possible strategy for the suppression of neoclassical tearing mode (NTM) seed islands on ITER or future fusion reactors.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Disruption avoidance by stabilizing coupled MHD modes using resonant magnetic perturbations on J-TEXT

He¹,

Wang²,

Ding³

et al. 2023

Plasma Phys. Control. Fusion

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“…In order to investigate the effect of pure 2/1 and pure 3/1 RMP on mode coupling, MP field coils with 2/1 or 3/1 components as the main components are required. In J-TEXT, there are four groups of double-turn coils [20,21] and island divertor coils [22,23] to produce RMP, as shown in figures 2(a) and 3(a), respectively. In 2019, the connections of double-turn coils were changed from poloidal connections of three coils on the same toroidal location to toroidal connections of the same poloidal location but opposite toroidal locations [21].…”

Section: Methodsmentioning

confidence: 99%

Prevention of mode coupling by external applied resonant magnetic perturbation on the J-TEXT tokamak

Wang

et al. 2023

Plasma Phys. Control. Fusion

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Toroidal coupling between m/n = 2/1 and m/n = 3/1 modes frequently occurs in the J-TEXT, where m (n) is the poloidal (toroidal) mode number. These coupled modes destabilize each other, leading to confinement degradation and even triggering a major disruption. This paper presents two control strategies for preventing the mode coupling through the application of a proper static resonant magnetic perturbation (RMP) field. Experimental results demonstrate that moderate 2/1 RMP can suppress the small, rotating 2/1 mode thus prevent coupling between the 2/1 and 3/1 modes. The 3/1 static RMP can excite a large 3/1 locked island while leave the small 2/1 mode rotating at 8 kHz. Enlarging the frequency difference between 2/1 and 3/1 modes makes mode coupling more difficult. Both strategies can break the frequency coupling condition between the 2/1 and 3/1 modes, and hence avoid coupling and mutual destabilizing.

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“…Figure 5(b) shows the identification of the BAE mode during the locked mode process [26]. The BAE mode is weakly observed at a frequency of 38 kHz during the locked mode (0.4-0.52 s).…”

Section: Application Of Spami For Plasma Physicsmentioning

confidence: 98%

An application of the shortest path algorithm for the identification of weak MHD mode

Huang

Mao

Ding

et al. 2023

Plasma Sci. Technol.

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Identification of magnetohydrodynamic (MHD) modes is a crucial issue in the control of magnetically confined plasmas. This paper proposes a novel method for identifying the evolution of MHD modes from a signal with a low signal-to-noise ratio. The proposed method generates a weighted directed graph from the time-frequency spectrum and calculates the evolution of the mode frequency by solving the shortest path. This method addresses the limitations posed by the lack of data channels and the disturbance of noise in the estimation of mode frequency and yields much better results compared to traditional methods. It is demonstrated that this method figured out the evolution of an unlocked tearing mode superiorly on the J-TEXT tokamak. The uncertainty of this method proves feasible even if the signal-to-noise ratio of the signal is as low as 0.5. Furthermore, with appropriate parameters, this method can be applied to not only signals with MHD modes but also general signals with continuous modes.

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Study of the spectrum effect on the threshold of resonant magnetic perturbation penetration on J-TEXT

Cited by 11 publications

References 49 publications

Disruption avoidance by stabilizing coupled MHD modes using resonant magnetic perturbations on J-TEXT

Disruption avoidance by stabilizing coupled MHD modes using resonant magnetic perturbations on J-TEXT

Prevention of mode coupling by external applied resonant magnetic perturbation on the J-TEXT tokamak

An application of the shortest path algorithm for the identification of weak MHD mode

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