Design of the high-resolution soft X-ray imaging system on the Joint Texas Experimental Tokamak

Li, Jianchao; Ding, Yonghua; Zhang, Xiaoqing; Xiao, Zhenyu; Zhuang, G.

doi:10.1063/1.4886432

Cited by 20 publications

(17 citation statements)

References 17 publications

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“…The 24channel heterodyne electron cyclotron emission (ECE) radiometer, covering most of the plasma within the frequency range of 80-125 GHz, is used for relative electron temperature measurement [21]. H α (656 nm) [22], soft X-ray (SXR) [23] and absolute extreme ultraviolet (AXUV) [24] arrays on ports 3 and 4 can measure corresponding radiation. In addition, a diamagnetic loop system is used to measure the plasma energy [25].…”

Section: Preliminary Experiments Resultsmentioning

confidence: 99%

Development of the pellet injection system on the J-TEXT tokamak

Jiang

Chen

et al. 2022

Plasma Sci. Technol.

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Pellet injection is an attractive technology for core-fueling and MHD study on magnetic-confined fusion device like tokamak and stellarator. It can inject solid Hydrogen/Deuterium pellets into the plasma with deeper density deposition compared with other fueling methods, such as gas puffing. A set of three-barrel H2 pellet injection system has been installed on J-TEXT tokamak and some experiments have been carried out. The pellets are formed in three barrels cooled by a cryocooler and compressor system at around 9 K, and have 0.8 mm/1 mm diameter and 0.8 mm length. The pellet is launched by high-pressure helium propellant gas and injected from low field side of plasma. The range of pellet speed is 25-310 m/s for different propellant gas pressure. With the three-barrel structure, the number of pellets injected can be adjusted with 1-3, when launch over 2 pellets, pellets can be launched simultaneously or sequentially with arbitrary time interval, which enables flexible applications. From the experiment results, pellet fueling efficiency can reach 50%. The energy confinement time has increased by about 7.5-10 ms after pellet injection.

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Section: Preliminary Experiments Resultsmentioning

confidence: 99%

Development of the pellet injection system on the J-TEXT tokamak

Jiang

Chen

et al. 2022

Plasma Sci. Technol.

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“…Temperature hollowing and edge cooling [43] are risk indicators for MHD instabilities, and they could also be treated as the disruption precursors. Two radiation arrays, soft x-ray (SXR) [44] and Absolute eXtended Ultra Violet (AXUV) [45] arrays, are used to extract this type of features due to the difficulty in accessing temperature profiles in all the discharges in the dataset. Theoretically, density limit disruption could be predicted through Greenwald density limit [46].…”

Section: Feature Extractor: Pgfementioning

confidence: 99%

IDP-PGFE: an interpretable disruption predictor based on physics-guided feature extraction

et al. 2023

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Disruption prediction has made rapid progress in recent years, especially in machine learning (ML)-based methods. If a disruption prediction model can be interpreted, it can tell why certain samples are classified as disruption precursors. This allows us to tell the types of incoming disruption for disruption avoidance and gives us insight into the mechanism of disruption. This paper presents a disruption predictor called Interpretable Disruption Predictor based on Physics-Guided Feature Extraction (IDP-PGFE) and its results on J-TEXT experiment data. The prediction performance of IDP-PGFE with physics-guided features is effectively improved (TPR = 97.27%, FPR = 5.45%, AUC = 0.98) compared to the models with raw signal input. The validity of the interpretation results is ensured by the high performance of the model. The interpretability study using an attribution technique provides an understanding of J-TEXT disruption and conforms to our prior comprehension of disruption. Furthermore, IDP-PGFE gives a possible means of inferring the underlying cause of the disruption and how interventions affect the disruption process in J-TEXT. The interpretation results and the experimental phenomenon have a high degree of conformity. The interpretation results also give a possible experimental analysis direction that the RMPs delay the density limit disruption by affecting both the MHD instabilities and the radiation profile. PGFE could also reduce the data requirement of IDP-PGFE to 10% of the training data required to train a model on raw signals. This made it possible to be transferred to the next-generation tokamaks, which cannot provide large amounts of data. Therefore, IDP-PGFE is an effective approach to exploring disruption mechanisms and transferring disruption prediction models to future tokamaks.

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“…The upgraded magnetic diagnostic of Mirnov probe arrays on the J-TEXT contains one poloidal array with 48 probes and two toroidal arrays with 25 probes, which is used for analysis of poloidal and toroidal mode numbers [23]. In this paper, the soft x-ray emission is measured by the soft x-ray diagnostic system (SXR) in Port 3, containing three cameras with a radial resolution of ∼1.5 cm [24].…”

Section: Experimental Set-upmentioning

confidence: 99%

Reduction of sawtooth amplitude by resonant magnetic perturbation

Li¹,

Ding²,

Yu³

et al. 2020

Nucl. Fusion

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Sawtooth crashes of large amplitude are detrimental to tokamak plasma confinement, and the amplitude has to be reduced for a fusion reactor. A novel method, i.e., applying m/n=2/2 resonant magnetic perturbations (RMPs), is found to be able to reduce the sawtooth magnitude in J-TEXT tokamak experiments. The penetration of RMPs and formation of 2/2 locked island are found to be related to the reduction of sawtooth magnitude. With the available 2/2 RMP field, the sawtooth mitigation is reproducibly achieved with qa < 2.8 and ne < 2×10 19 m -3 in J-TEXT.

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Design of the high-resolution soft X-ray imaging system on the Joint Texas Experimental Tokamak

Cited by 20 publications

References 17 publications

Development of the pellet injection system on the J-TEXT tokamak

Development of the pellet injection system on the J-TEXT tokamak

IDP-PGFE: an interpretable disruption predictor based on physics-guided feature extraction

Reduction of sawtooth amplitude by resonant magnetic perturbation

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