Upgrade and application of the gas puff imaging system in EAST

Liu, S.C.; Liao, Lijuan; Zhong, Linsheng; Wei, W.; Li, L.T.; Niu, Y.; Xing, Yin-long; Xu, G. S.; Shao, L. M.; Chen, R.; Hu, G.H.; Liu, J.B.; Liang, Yun-Feng; Han, Xiaofeng; Cai, Jianqing; Zhao, Nan; Liu, X.J.; Ming, Tingfeng; Zang, Qing; Wang, L.; Zeng, Long; Li, G.Q.; Gong, X.Z.; Gao, Xiang

doi:10.1016/j.fusengdes.2022.113156

Cited by 2 publications

(2 citation statements)

References 36 publications

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“…The GPI system's objective plane is elevated approximately 27.6 cm above the outer midplane. Additionally, there's a poloidal angle of 35 • between the horizontal plane and the minor radius at the center of this objective plane [34].…”

Section: Methodsmentioning

confidence: 99%

Characterization of SOL profiles and turbulence in ICRF-heated plasmas in EAST

Li,

Yan,

et al. 2024

Nucl. Fusion

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Scrape-off layer (SOL) profiles and turbulence in ICRF-heated plasmas are investigated by the reciprocating probe diagnostic system (FRPs) and Gas-puff imaging diagnostic (GPI) in EAST. A Radio-frequency (RF) sheath potential reaching up to 100V is identified proximate to the ICRF antennas. Notably, the amplitude of this RF sheath potential escalates in response to rising ICRF power and inversely with plasma density. When a RF sheath is present in the far SOL, a pronounced density ‘shoulder’ forms in front of the ICRF antennas, while the ‘shoulder’ fade away as the antenna and associated RF sheath shift outwards. A strong Er shear is revealed by measurements from both FRPs and GPI. Analysis of the poloidal wave number-frequency spectrum reveals suppression of high-frequency turbulence in the far SOL due to the RF sheath. This effect is manifested in the reduced autocorrelation time τc and reduced average blob size δblob of the SOL plasma. Intriguingly, the poloidal propagation direction of the low-frequency turbulence reverses from the electron to the ion diamagnetic drift direction at the RF sheath location. A surge of tungsten impurity is potentially attributed to the heightened interaction between the SOL plasmas and the wall material. Shifting the ICRF antennas outward, to alleviate heat spots, results in the relocation of the RF sheath to the shaded region of the main limiter. This shift amplifies the radial velocity of blobs in the far SOL and concurrently diminishes the SOL density when compared to conditions without ICRF injection. The properties of ion saturation current fluctuations are consistent with the stochastic model predictions.

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Section: Methodsmentioning

confidence: 99%

Characterization of SOL profiles and turbulence in ICRF-heated plasmas in EAST

Li,

Yan,

et al. 2024

Nucl. Fusion

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“…The median filter is widely used in image processing [34]. The median filter works by calculating the median value of the pixels in the neighborhood of each pixel and assigning this value to the central pixel.…”

Section: Image Enhancement 221 Adaptive Median Filteringmentioning

confidence: 99%

Development of a 2D spatial displacement estimation method for turbulence velocimetry of the gas puff imaging system on EAST

LI 李,

LIU 刘,

YAN 颜

et al. 2024

Plasma Sci. Technol.

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The gas puff imaging (GPI) diagnostic has been developed and operated on EAST since 2012, and the time-delay estimation (TDE) method is used to derive the propagation velocity of fluctuations from the two-dimensional GPI data. However, the TDE method is difficult to analyze the data with fast transient events, such as edge-localized mode (ELM). In consequence, a method called the spatial displacement estimation (SDE) algorithm is developed to estimate the turbulence velocity with high temporal resolution. Based on the SDE algorithm, we make some improvements, including an adaptive median filter and super-resolution technology. After the development of the algorithm, a straight-line movement and a curved-line movement are used to test the accuracy of the algorithm, and the calculated speed agrees well with preset speed. This SDE algorithm is applied to the EAST GPI data analysis, and the derived propagation velocity of turbulence is consistent with that from the TDE method, but with much higher temporal resolution.

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Upgrade and application of the gas puff imaging system in EAST

Cited by 2 publications

References 36 publications

Characterization of SOL profiles and turbulence in ICRF-heated plasmas in EAST

Characterization of SOL profiles and turbulence in ICRF-heated plasmas in EAST

Development of a 2D spatial displacement estimation method for turbulence velocimetry of the gas puff imaging system on EAST

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