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Physical design of FEL injector based on the performance-enhanced EC-ITC RF gun

Chinese Physics C 2014年第1期38卷 79-85页

作者：胡桐宁陈曲珊裴元吉李骥秦斌 State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology National Synchrotron Radiation Laboratory University of Science and Technology of China

To meet the requirements of high performance THz-FEL （Free Electron Laser）, a compact scheme of FEL injector was proposed. A thermionic cathode was chosen to emit electrons instead of a photo-cathode with its complex structure and high cost. The effective bunch charge was improved to ~200 pC by adopting an enhanced EC-ITC （External Cathode Independently Tunable Cells） RF gun to extract micro-bunches; back bombardment effects were almost eliminated as well. Constant gradient accelerator structures were designed to improve energy to ~14 MeV, while the focusing system was applied for emittance suppressing and bunch state maintenance. The physical design and beam dynamics of the key components for the FEL injector were analyzed. Furthermore, start- to-end simulations with multi-pulses were performed using homemade MATLAB and Parmela. The results show that continual high brightness electron bunches with a low energy spread and emittance could be obtained stably.

关键词： RF gun EC-ITC beam dynamics LINAC FEL injector

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The Construction of Plasma Density Feedback Control System on J-TEXT Tokamak

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Plasma Science and technology 2016年第2期18卷 211-216页

作者：柯新陈志鹏巴为刚舒双宝高丽张明庄革 State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology School of Instrument Science and Opto-Electronics Engineering Hefei University of Technology

The plasma density feedback control system（PDFCS） has been established on the Joint Texas Experimental Tokamak（J-TEXT） for meeting the need for an accurate plasma density in physical *** consists of a density measurement subsystem,a feedback control subsystem and a gas puffing *** to the characteristic of the gas puffing system,a voltage amplitude control mode has been applied in the feedback control strategy,which is accomplished by the proportion,integral and differential（PID） *** this system,the quantity calibration of gas injection,adjusted responding to the change of the density signal,has been carried *** experimental results are shown and discussed.

关键词： density feedback control tokamak PID

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Distribution Dynamic Operating Security Space Characterization for Aggregation and Congestion Capacity Evaluation of Virtual Power Plant

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IEEE Transactions on Smart Grid 2025年

作者： Song, Meng Xu, Zekai Gao, Ciwei Yan, Mingyu Hu, Qinran Southeast University School of Electrical Engineering Nanjing 210096 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan 430074 China

Virtual power plant(VPP) can manage distributed energy resources (DERs) to serve the grid, which should satisfy the power flow constraints. However, the distribution system operator(DSO) monopolies system parameters and VPP cannot directly access them. To solve the coordination problem between distribution operation security and VPP management, the distribution dynamic operating security space (DOSS) is proposed to constrain the DER output power for VPP aggregation and congestion capacity evaluation. First, a hybrid fuzzy modeling method based on the distribution system security region is employed to characterize DOSS, and less information exchange between VPP and DSO is required. Data privacy is well respected, and the computational complexity is also reduced. Second, the enhanced opposite direction searching algorithm and the generalized credibility-based piecewise membership crisp method are applied to achieve DOSS's type-reduction and defuzzification for VPP aggregation. This clarifies distribution security risks on VPP through DOSS’s credibility levels. Finally, VPP congestion capacity is proposed to quantify security constraint impacts on the VPP aggregation capacity, which can help coordinate the VPP economic and DSO secure operations. Case studies demonstrate that the proposed methodology can effectively embed the distribution operation security constraints into VPP aggregation and show higher applicability and lower conservativeness than existing approaches. © 2010-2012 IEEE.

关键词： aggregation congestion capacity distribution system security region Dynamic operating security space virtual power plant

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On the green aurora emission of Ar atmospheric pressure plasma

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Plasma Science and technology 2022年第5期24卷 195-204页

作者： Fengwu LIU Lanlan NIE Xinpei LU State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China

The Ar atmospheric pressure plasma was found to be an excellent laboratorial source for green aurora ***,the characteristic and production mechanism of the green aurora emission of the Ar atmospheric pressure plasma are still not *** this work,an Ar plasma in a long glass tube which emits intense green aurora light is *** the long glass tube,it can be concluded that the green aurora emission in the Ar plasma is not owing to the mixture of Ar plasma plume with the surrounding *** is also found that the green aurora emission often appeared beyond the active electrode when the active electrode is placed at the downstream of the gas *** green emission disappears when the traces amount of O_(2) or N_(2)(about 0.05%–0.07%)is added to *** is because the O_(2) molecules deactivate the upper state O(^(1)S),which results in the decrease of the green *** the other hand,when N_(2) is added,Ar metastable atoms are quenched by N_(2),which results in the decrease of O atoms and eventually leads to the decrease of the green emission *** intensity of the green aurora emission increases when the driving voltage frequency increases from 1 to 10 k *** importantly,it is found that the green aurora emission is not affected when a grounded stainless steel needle is in contact with the plasma ***,the green emission is not driven *** these findings are helpful for the understanding of the physics and its applications of atmospheric pressure plasma jet in space physics,laser physics and other application areas.

关键词： atmospheric pressure plasma jet plasma optical emission aurora emission

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A Visible Light Imaging System for the Estimation of Plasma Vertical Displacement in J-TEXT

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Plasma Science and technology 2010年第6期12卷 641-645页

作者：朱孟周庄革王之江丁永华高丽胡希伟潘垣 College of Electrical and Electronic Engineering Huazhong University of Science and Technology China Key Laboratory of Fusion and Advanced Electromagnetic Technology of Ministry of Education

A wide-viewing-angle visible light imaging system （VLIS） was mounted on the Joint Texas Experimental Tokamak （J-TEXT） to monitor the discharge process. It is proposed that by using the film data recorded the plasma vertical displacement can be estimated. In this paper installation and operation of the VLIS are presented in detailed. The estimated result is further compared with that measured by using an array of magnetic pickup coils. Their consistency verifies that the estimation of the plasma vertical displacement in J-TEXT by using the imaging data is promising.

关键词： visible light imaging, vertical displacement J-TEXT

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A homogeneous atmospheric pressure air plasma in a 10 mm gap based on a three-electrode configuration

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Plasma Science and technology 2023年第10期25卷 75-80页

作者：李志宇刘大伟卢新培聂兰兰 State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China

Generation of atmospheric pressure homogeneous air plasma in a large gap(>4 mm)is a *** this study,an atmospheric pressure homogeneous air plasma generated in a gap up to 10 mm is reported,which is based on a three-electrode configuration,where a high-voltage(HV)electrode and a middle electrode form a surface dielectric barrier discharge(S-DBD),and together with the ground electrode form the main volume ***-speed photographs confirm that the discharge in the main gap is *** gas temperature of the plasma estimated from the N_(2)(C^(3)∏_(u)-B^(3)∏_(g))(Δv=-2)emission is about 320 K,which is close to room temperature.A detailed analysis shows that the discharge ignited between the HV electrode and the middle electrode is serving as an electron source,and the electrons deposited on the dielectric plate are due to the S-DBD along with the applied voltage generating a driving force,which results in a high concentration of seed electrons in the main gap and induces the homogeneous *** analysis shows that the electric field in the main gap is only about18.45 k V·cm^(-1),which is much lower than the typical breakdown electric field of 30 k V·cm^(-1)for atmospheric pressure air discharge.

关键词： atmospheric pressure plasma homogeneous discharge glow discharge air plasma

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A non‐equal gap distance dielectric barrier discharge:Between cone‐shape and cylinder‐shape electrodes

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High Voltage 2022年第1期7卷 98-105页

作者： Shaohui Jin Zhiyu Li Yubin Xian Lanlan Nie Xinpei Lu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhanHubeiChina

A non‐equal gap distance dielectric barrier discharge(DBD)between cone‐shape and a cylinder‐shaped electrodes is *** DBD is driven by a nanosecond voltage *** the pulse frequency is 500 Hz or lower,ladder‐shape plasma with multiple plasma layers is generated within the gap,with a distance increasing from 1 to 7 *** to high‐speed photographs of the plasma captured by an intensified charge‐coupled camera detector camera,the ladder‐shaped plasma is formed owing to propa-gation of ring‐shaped plasma from the region of the short‐gap distance to the region of long‐gap distance with regular variations in its propagation *** propagation speed drops to zero and lasts for about 20-30 ns at the region of each plasma layer,which results in bright plasma *** electric field of the plasma layer at the region of the different gap distance is evaluated according to the optical emission intensity ratio R_(391)/_(394)of N_(2)^(+)at 391 nm and N_(2) at 394 *** obtained electric field drops from 8.1 to 6.4 kV/mm when the plasma is propagated from regions of gap distance of 2-5 *** the pulse frequency is increased to 1 kHz or higher,the discharge changes into a filamentary mode and the multiple‐layer plasma disappears.

关键词： cylinder shaped dielectric

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Multi-time scale dynamics in power electronics-dominated power systems

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Frontiers of Mechanical engineering 2017年第3期12卷 303-311页

作者： Xiaoming YUAN Jiabing HU Shijie CHENG State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applications in the load side to realize energy conservation and on the supply side for renewable generations and power transmissions using high voltage direct current transmission. This transformation has altered the fundamental mechanism of power system dynamics, which demands the establishment of a new theory for power system control and protection. This paper presents thoughts on a theoretical framework for the coming semiconducting power systems.

关键词： power electronics power systems multi-time scale dynamics mass-spring-damping model self-stabilizing and en-stabilizing property multi-time scale power system stabilizer

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Effect of gas components on the postdischarge temporal behavior of OH and O of a non-equilibrium atmospheric pressure plasma driven by nanosecond voltage pulses

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Plasma Science and technology 2024年第5期26卷 72-81页

作者：王兰萍聂兰兰卢新培 State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China

OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma ***,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very *** this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)*** results show that the productions of OH and O increase and then decrease with the increase of O_(2)*** OH and O densities reach their maximum when about 0.8%O_(2)is *** increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster *** increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is ***,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O *** analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)*** addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.

关键词： O atom OH radical post-discharge temporal behavior laser-induced fluorescence

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Efficient direction-independent fog harvesting using a corona discharge device with a multi-electrode structure

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Plasma Science and technology 2022年第9期24卷 98-107页

作者： Dingchen LI Chuan LI Jiawei LI Wendi YANG Menghan XIAO Ming ZHANG Yong YANG Kexun YU International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical Engineering and ElectronicsHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical Engineering and ElectronicsHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China

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 *** inefflcient fog meshes,corona discharge can charge water droplets and further enhance the water-collecting *** study proposes a novel multi-electrode collecting structure that can achieve efflcient and direction-independent water collection from *** multi-electrode structure consists of three parts:a charging electrode,an intercepting electrode and a ground *** 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),*** collection rate of the multielectrode structure is 100–150 times that of a traditional fog mesh and 2–4 times that of a wiremesh *** results demonstrate the superiority of the multi-electrode structure in fog *** addition,the motion equation of charged droplets in an electric fleld is also derived,and the optimization strategy of electrode spacing is also *** structure can be applied not only to fog collection,but also to air puriflcation,factory waste gas treatment and other flelds.

关键词： fog collection corona discharge wire-mesh electrode multi-electrode structure collection rate

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