Experimental study of ELM-induced filament structures using the VUV imaging system on EAST

Li, Bang; Ming, Tingfeng; Zhuang, Qiya; Long, Feifei; Gao, Shanlu; Shi, Qiqi; Wang, Yumin; Liu, Xiaoju; Liu, Shaocheng; Zeng, Long; Gao, Xiang

doi:10.1088/2058-6272/abda9d

Cited by 5 publications

(10 citation statements)

References 26 publications

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“…In each ELM, only one filament, which appears 150 microseconds before the timing when the perturbation of the VUV signal goes to the maximum during the ELM crash, is analyzed. The details of the VUV imaging system and the definition of the filament width can be found in references [11,12]. Both the ELM size and the filament widths are proportional to the total heating power, which also can be seen in reference [12].…”

Section: Resultsmentioning

confidence: 99%

“…As part of the observation window is shielded by the support of the beam emission spectroscopy, no data is received in the upper part of the resampled image, see figures 4(a) and (b) in reference [12]. However, clear filament structures can be seen in the images.…”

Section: Vuv Imaging System For Elm Study In Eastmentioning

confidence: 99%

“…However, clear filament structures can be seen in the images. The resampled image size is 256 (pixels) × 256 (pixels), which covers an area of about 280 mm (toroidally) × 288 mm (poloidally) in the plasma region (figure 2 in reference [12]). It is difficult to determine the radial locations of the filaments from the line-integrated imaging data.…”

Section: Vuv Imaging System For Elm Study In Eastmentioning

confidence: 99%

“…The filament structure induced by the ELM has been observed via varied diagnostics in a wide range of tokamaks [1][2][3][4]. The filaments along the magnetic field line have a certain toroidal and poloidal mode number and move outwards via the E × B drift, as (n = 4-2 transition) [10][11][12][13]. The poloidal width of the filaments (hereinafter referred as filament width), which is defined as the shortest distance of the two edges (i.e., binormal direction) of the filament structure, are found in proportional to the heating power and ELM size [12].…”

Section: Introductionmentioning

confidence: 99%

“…The filaments along the magnetic field line have a certain toroidal and poloidal mode number and move outwards via the E × B drift, as (n = 4-2 transition) [10][11][12][13]. The poloidal width of the filaments (hereinafter referred as filament width), which is defined as the shortest distance of the two edges (i.e., binormal direction) of the filament structure, are found in proportional to the heating power and ELM size [12]. In other words, the power dependence of the ELM size is related to the filament widths.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Study on filament width of type-I ELM in EAST using VUV imaging system and simulation

Ming

Tang²,

Shi³

et al. 2022

Nucl. Fusion

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The poloidal width of the filaments induced by the Type-I edge localized mode has power dependence in EAST. The poloidal widths of the filaments observed by the high-speed vacuum ultraviolet (VUV) imaging system are proportional to the heating power and the ELM size. To understand this power dependence, the BOUT++ nonlinear simulations have been performed with the reconstructed equilibriums from the experimental measurements in this paper. The synthetic filament structures from BOUT++ nonlinear simulation match the experimental observations by the VUV imaging system. The BOUT++ nonlinear simulations also reproduce the power dependence of the filament widths and the ELM size. The filament width and the ELM size are inversely proportional to the toroidal mode number. The low-n mode has a broader radial and poloidal structure, which causes the larger filament width and ELM size. In the high input power case, the mode spectrum shifts to low-n, a result of increasing peeling drive. Besides, we found the β_p in a higher input power case leads to a broader pedestal, expanding the radial mode structure of the Peeling-Ballooning mode.

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Section: Resultsmentioning

confidence: 99%

Section: Vuv Imaging System For Elm Study In Eastmentioning

confidence: 99%

Section: Vuv Imaging System For Elm Study In Eastmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Study on filament width of type-I ELM in EAST using VUV imaging system and simulation

Ming

Tang²,

Shi³

et al. 2022

Nucl. Fusion

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Experimental and simulation studies on ELM characteristics under a plasma current ramping up discharge on EAST

Li,

Ming,

et al. 2024

AIP Advances

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Previous experimental results show that the poloidal mode spacing of the filamentary structures increases and the dominant toroidal mode number decreases in the edgelocalized mode (ELM) rising phase with increasing plasma current. In addition, the experimental results in this paper show that the energy loss ratio of the pedestal (ΔW/Wped) decreases as the edge safety factor (q95) increases. The BOUT++ three-field two-fluid model can reproduce the experimental results and provide a possible explanation mechanism. The pedestal density plays an important role in the characteristics of filamentary structures as the current ramps up. On the one hand, the resistivity related to the pedestal density drives the instability of the peeling–ballooning mode, and the resistive effect is stronger in the high current case, making the dominant toroidal mode number lower and the corresponding poloidal mode spacing wider in the high current case. A low q95 corresponds to a high pedestal collision rate and a high pedestal energy loss ratio. On the other hand, the ELM crash process is dominated by resistivity, so the ratio of pedestal energy loss caused by ELM is not inversely proportional to the pedestal collision rate.

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Experimental study on the spatial structures of filament during ELM crash in ELMy H-mode discharge on EAST

Ming

et al. 2023

Plasma Phys. Control. Fusion

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A high-speed vacuum ultraviolet imaging (VUVI) system with both high temporal and spatial resolutions in the Experimental Advanced Superconducting Tokamak (EAST) has been developed for the study of the edge/pedestal plasma. Edge localized mode (ELM)-induced filamentary structures have been successfully visualized by the VUVI system during the ELMy high confinement mode (H-mode) discharges. The poloidal mode spacing and the pitch angle are employed to quantitatively characterize the spatial structure of the observed filamentary structures in the imaging data. The poloidal mode spacing of the filamentary structure is found to be proportional to the plasma current. The dominant toroidal mode number decreases as the plasma current ramps up. In addition, the temporal evolution of the pitch angle during an ELM crash was quantitatively investigated. No significant change in the pitch angle is observed during an ELM crash. The dominant toroidal mode number gradually decreases in the rise phase and increases in the decay phase in one ELM crash, respectively.

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Experimental study of ELM-induced filament structures using the VUV imaging system on EAST

Cited by 5 publications

References 26 publications

Study on filament width of type-I ELM in EAST using VUV imaging system and simulation

Study on filament width of type-I ELM in EAST using VUV imaging system and simulation

Experimental and simulation studies on ELM characteristics under a plasma current ramping up discharge on EAST

Experimental study on the spatial structures of filament during ELM crash in ELMy H-mode discharge on EAST

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