The J-TEXT tokamak has been operated for ten years since its first plasma obtained at the end of 2007. The diagnostics development and main modulation systems, i.e. resonant magnetic perturbation (RMP) systems and m...The J-TEXT tokamak has been operated for ten years since its first plasma obtained at the end of 2007. The diagnostics development and main modulation systems, i.e. resonant magnetic perturbation (RMP) systems and massive gas injection (MGI) systems, will be introduced in this paper. Supported by these efforts, J-TEXT has contributed to research on several topics, especially on RMP physics and disruption mitigation. Both experimental and theoretical research show that RMP could lock, suppress or excite the tearing modes, depending on the RMP amplitude, frequency difference between RMP and rational surface rotation, and initial stabilities. The plasma rotation, particle transport and operation region are influenced by the RMP. Utilizing the MGI valves, disruptions have been mitigated with pure He, pure Ne, and a mixture of He and Ar (9:1). A significant runaway current plateau could be generated with moderate amounts of Ar injection. The RMP has been shown to suppress the generation of runaway current during disruptions.展开更多
The acceleration grid power supply(AGPS)rated 200 kV/25 A is a key component devoted to supply the acceleration grids of the China fusion engineering test reactor negative-ion-based neutral beam injector(N-NBI)prototy...The acceleration grid power supply(AGPS)rated 200 kV/25 A is a key component devoted to supply the acceleration grids of the China fusion engineering test reactor negative-ion-based neutral beam injector(N-NBI)prototype system.This paper focused on the design and control of the AGPS conversion system(AGPS-CS),with emphasis on the requirement of the wide range output voltage and rise time.A voltage regulation switch at the front of step-down transformer is applied to optimize the grid current and DC-link voltage.Moreover,a new feedforward control strategy with piecewise PI compensator is proposed to improve the characteristics of AGPS.The simulation results of the proposed AGPS-CS are presented,proving the performance of the power supply to achieve the desired requirements.展开更多
Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can char...Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can charge water droplets and further enhance the water-collecting effect.This study proposes a novel multi-electrode collecting structure that can achieve efflcient and direction-independent water collection from fog.The multi-electrode structure consists of three parts:a charging electrode,an intercepting electrode and a ground electrode.Four types of watercollecting structures are compared experimentally,and the collection rates from a traditional fog mesh,a wire-mesh electrode with fog coming from a high-voltage electrode,a wire-mesh electrode with fog coming from a ground electrode and a multi-electrode structure are 2–3 g h^(-1),100–120 g h^(-1),60–80 g h^(-1)and 200–220 g h^(-1),respectively.The collection rate of the multielectrode structure is 100–150 times that of a traditional fog mesh and 2–4 times that of a wiremesh electrode.These results demonstrate the superiority of the multi-electrode structure in fog collection.In addition,the motion equation of charged droplets in an electric fleld is also derived,and the optimization strategy of electrode spacing is also discussed.This structure can be applied not only to fog collection,but also to air puriflcation,factory waste gas treatment and other flelds.展开更多
Needle electrodes are widely used in the research of corona discharge.Aiming at the problem of needle electrode discharge in a large-scale space(tens or even hundreds of centimetres),a hybrid model was proposed in the...Needle electrodes are widely used in the research of corona discharge.Aiming at the problem of needle electrode discharge in a large-scale space(tens or even hundreds of centimetres),a hybrid model was proposed in the previous work.However,its indis-pensable multiple iterations result in huge computation and further limit its wide appli-cations.Therefore,a strategy to improve the computing efficiency by setting initial values in different computational domains is put forward in this work.Three types of setting initial values(global constant,partition constant and partition exponent)are simulated and compared in detail.The calculation results show that the calculation efficiency can be increased by 1.4 times simply through setting initial values of charged particles as different constants for the divided subdomains,and further be improved by 4.3 times by setting those in the ionization region as an exponential distribution.The extension of the pro-posed strategy has also been discussed under various voltages,which shows that the results under other voltages can be quickly obtained based on the fitted coefficients under a specific voltage,and the improvement can reach up to 10 times.The accuracy of calculated results has been demonstrated by a needle-plate electrode device with a vertical distance of 25 cm.This research provides an effective strategy for improving the computing efficiency of corona discharge in a large-scale space,and implies the potential in optimizing the analyses of complex electrodes.展开更多
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2014GB118000,2014GB106001,2015GB111001,2015GB111002 and 2015GB120003)National Natural Science Foundation of China(Nos.11505069,11275079 and 11405068)
文摘The J-TEXT tokamak has been operated for ten years since its first plasma obtained at the end of 2007. The diagnostics development and main modulation systems, i.e. resonant magnetic perturbation (RMP) systems and massive gas injection (MGI) systems, will be introduced in this paper. Supported by these efforts, J-TEXT has contributed to research on several topics, especially on RMP physics and disruption mitigation. Both experimental and theoretical research show that RMP could lock, suppress or excite the tearing modes, depending on the RMP amplitude, frequency difference between RMP and rational surface rotation, and initial stabilities. The plasma rotation, particle transport and operation region are influenced by the RMP. Utilizing the MGI valves, disruptions have been mitigated with pure He, pure Ne, and a mixture of He and Ar (9:1). A significant runaway current plateau could be generated with moderate amounts of Ar injection. The RMP has been shown to suppress the generation of runaway current during disruptions.
基金This work is supported by the National Key R&D Program of China under Grant No.2017YFE0300104National Natural Science Foundation of China(Nos.51707073 and 51821005).
文摘The acceleration grid power supply(AGPS)rated 200 kV/25 A is a key component devoted to supply the acceleration grids of the China fusion engineering test reactor negative-ion-based neutral beam injector(N-NBI)prototype system.This paper focused on the design and control of the AGPS conversion system(AGPS-CS),with emphasis on the requirement of the wide range output voltage and rise time.A voltage regulation switch at the front of step-down transformer is applied to optimize the grid current and DC-link voltage.Moreover,a new feedforward control strategy with piecewise PI compensator is proposed to improve the characteristics of AGPS.The simulation results of the proposed AGPS-CS are presented,proving the performance of the power supply to achieve the desired requirements.
基金supported by the National Key Research and Development Program of China(Nos.2016YFC0401002 and 2016YFC0401006)National Natural Science Foundation of China(Nos.51577080 and 51821005)。
文摘Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can charge water droplets and further enhance the water-collecting effect.This study proposes a novel multi-electrode collecting structure that can achieve efflcient and direction-independent water collection from fog.The multi-electrode structure consists of three parts:a charging electrode,an intercepting electrode and a ground electrode.Four types of watercollecting structures are compared experimentally,and the collection rates from a traditional fog mesh,a wire-mesh electrode with fog coming from a high-voltage electrode,a wire-mesh electrode with fog coming from a ground electrode and a multi-electrode structure are 2–3 g h^(-1),100–120 g h^(-1),60–80 g h^(-1)and 200–220 g h^(-1),respectively.The collection rate of the multielectrode structure is 100–150 times that of a traditional fog mesh and 2–4 times that of a wiremesh electrode.These results demonstrate the superiority of the multi-electrode structure in fog collection.In addition,the motion equation of charged droplets in an electric fleld is also derived,and the optimization strategy of electrode spacing is also discussed.This structure can be applied not only to fog collection,but also to air puriflcation,factory waste gas treatment and other flelds.
基金National Key Research and Development Program of China,Grant/Award Numbers:2016YFC0401002,2016YFC0401006National Natural Science Foundation of China,Grant/Award Numbers:51577080,51821005。
文摘Needle electrodes are widely used in the research of corona discharge.Aiming at the problem of needle electrode discharge in a large-scale space(tens or even hundreds of centimetres),a hybrid model was proposed in the previous work.However,its indis-pensable multiple iterations result in huge computation and further limit its wide appli-cations.Therefore,a strategy to improve the computing efficiency by setting initial values in different computational domains is put forward in this work.Three types of setting initial values(global constant,partition constant and partition exponent)are simulated and compared in detail.The calculation results show that the calculation efficiency can be increased by 1.4 times simply through setting initial values of charged particles as different constants for the divided subdomains,and further be improved by 4.3 times by setting those in the ionization region as an exponential distribution.The extension of the pro-posed strategy has also been discussed under various voltages,which shows that the results under other voltages can be quickly obtained based on the fitted coefficients under a specific voltage,and the improvement can reach up to 10 times.The accuracy of calculated results has been demonstrated by a needle-plate electrode device with a vertical distance of 25 cm.This research provides an effective strategy for improving the computing efficiency of corona discharge in a large-scale space,and implies the potential in optimizing the analyses of complex electrodes.