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Revealing phase transitions and instabilities in pseudospark discharges

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High Voltage 2023年第4期8卷 819-832页

作者： Jiaqi Yan Saikang Shen Guoxiang Sun Weidong Ding Weizong Wang School of Astronautics Beihang UniversityBeijingChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

Pseudospark discharge is a low-pressure high-voltage pulsed discharge with hollow electrodes,and the overall discharge experiences several distinctive *** instability phenomena,characterised by the sudden oscillations or distortions of discharge voltage and current,restrict the applications of pseudospark *** study presents an investigation into phase transitions and instabilities in pseudospark discharge by combining the evidences from multiple discharge waveforms,time-resolved images,electron beam current profiles,2D kinetic simulation results,and the spectral line emission of cathode *** process of a normal pseudospark discharge is firstly discussed,and the threshold conditions of the transition from the superdense glow discharge(SGD)phase to the high current phase with arc cathode spots are *** to temporal profiles and voltage-current characteristics,two types and four occurrences of instabilities are distinguished:type Ⅰ—in the pre-breakdown phase;type Ⅱ-1—in the SGD phase;type Ⅱ-2—in the transition of cathode spots propagating from cathode hole edge to cathode plane;type Ⅱ-3—in the re-initiation of spots near current *** is found that the instability of type Ⅰ is caused by the stepwise penetration of virtual anode plasma,and type Ⅱ is closely related to the cyclic nature and finite lifetime of cathode *** is induced by the fact that the decay of cathode spots is faster than the formation under certain conditions,and the existing spots are not able to provide the current required by the external *** features and the suppression methods of the instabilities are discussed based on the proposed mechanisms.

关键词： phase cathode lifetime

Analysis for magnetic field disturbance of modular multilevel converter based high voltage direct current(mmC-HVDC)converter valve

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High Voltage 2023年第1期8卷 91-101页

作者： Lei Qi muxue Wang Xiangyu Zhang Hong Shen Hongyu Wang Chongqing Jiao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

The standardised design and operational reliability enhancement of the flexible DC converter valve are impending with the construction of high shares of renewables and power electronics power system.A power frequency magnetic field calculation model able to obtain the electromagnetic disturbance at the submodule(Sm)drive board during normal operation of a flexible DC converter valve is *** of Sms with complex structures in a converter valve tower are simplified by the equivalent to the line current to fulfil calculation accuracy *** addition,a random function is employed to simulate the non-sequential switching process of the *** comparing the calculated results with the measured data obtained from the Sm equivalent operation experiment of 2200 V/2150 A,the validity of the calculation model is *** to the final calculations,the influence of non-sequential switching cannot be ignored when recognising the time-domain distribution features of the power frequency magnetic field of the drive ***,engineering design can be guided only by the power frequency magnetic field intensity of the drive board calculated based on Sm’s full removal in the valve tower.

关键词： disturbance converter magnetic

Design and 3D printing of porous cavity insulation structure for ultra-high electrical withstanding capability

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High Voltage 2023年第4期8卷 717-727页

作者： Xiong Yang Guangyu Sun Baipeng Song Wenhu Han Chao Wang Wendong Li Shu Zhang Falun Song Fangzheng Zou Guanjun Zhang State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi'an Jiaotong UniversityXi'anChina Ecole Polytechnique Fédérale de Lausanne(EPFL) Swiss Plasma Center(SPC)LausanneSwitzerland Institute of Applied Electronics China Academy of Engineering PhysicsMianyangChina

Vacuum-dielectric interface is the most vulnerable part of vacuum insulation systems where surface electrical breakdown is prone to happen,hence severely restricts the development of advanced electro-vacuum devices with large capacity and its ***,a direct and effective way to improve vacuum surface insulation is to alleviate the initiation and development of multipactor *** by this approach,the authors report a 3D-printed insulation structure designed with a millimetrescale surface cavity covered by periodic through-pore array via stereolithography,exhibiting remarkable multipactor suppression and flashover threshold improvement,well outperforming the conventional flashover mitigation *** and simulations demonstrate that electrons in the multipactor region pass through-pores and are unlikely to escape from the cavity,hence no longer participate in the above-surface multipactor process,and eventually improve flashover *** proposed approach provides new inspiration for the design of advanced insulators featuring ultrahigh electrical withstanding capability and brings up new insight into pertinent industrial applications.

关键词： insulation electrical hence

Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

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Carbon Energy 2024年第4期6卷 164-221页

作者： Huilin Hou Gang Shao Yang Wang Wai‐Yeung Wong Weiyou Yang Institute of micro/Nano materials and Devices Ningbo University of TechnologyNingboChina School of materials science and Engineering Zhengzhou UniversityZhengzhouChina Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongChina

Conversion of solar energy into H_(2) by photoelectrochemical(PEC)water splitting is recognized as an ideal way to address the growing energy crisis and environmental *** a typical PEC cell,the construction of photoanodes is crucial to guarantee the high efficiency and stability of PEC reactions,which fundamentally rely on rationally designed semiconductors(as the active materials)and substrates(as the current collectors).In this review work,we start with a brief introduction of the roles of substrates in the PEC ***,we provide a systematic overview of representative strategies for the controlled fabrication of photoanodes on rationally designed substrates,including conductive glass,metal,sapphire,silicon,silicon carbide,and flexible ***,some prospects concerning the challenges and research directions in this area are proposed.

关键词： hydrogen photoanode photoelectrochemical substrates water splitting

A review of high‐velocity impact on fiber‐reinforced textile composites: Potential for aero engine applications

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International Journal of mechanical System Dynamics 2022年第1期2卷 50-64页

作者： Yinghong Li Xuefeng Chen Jin Zhou Xiaochuan Liu Di Zhang Feiping Du Weifeng He Pu Jia Haibao Liu School of mechanical Engineering Xi'an Jiaotong UniversityXi'anChina science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'anChina science and Technology on Liquid Rocket Engine Laboratory Xi'an Aerospace Propulsion InstituteXi'anChina Centre for Aeronautics School of AerospaceTransport and ManufacturingCranfield UniversityCranfieldUK

Considerable research has indicated that fiber‐reinforced textile composites are significantly beneficial to the aerospace industry,especially aero engines,due to their high specific strength,specific stiffness,corrosion resistance,and fatigue ***,damage caused by high‐velocity impacts is a critical limitation factor in a wide range of *** paper presents an overview of the development,material characterizations,and applications of fiber‐reinforced textile composites for aero *** textile composites are classified into four ca-tegories including two‐dimensional(2D)woven composites,2D braided composites,3D woven composites,and 3D braided *** complex damage me-chanisms of these composite materials due to high‐velocity impacts are discussed in detail as well.

关键词： aero engines damage mechanism high‐velocity impact textile composites

Streamer dynamics and charge self-erasing of two counter-propagating plasmas in repetitively pulsed surface dielectric barrier discharge

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High Voltage 2022年第4期7卷 730-743页

作者： Bangfa Peng Nan Jiang Kefeng Shang Na Lu Jie Li Yan Wu School of Electrical Engineering Dalian University of TechnologyDalianChina

The streamer dynamics and charge self-erasing of two counter-propagating plasmas generated by repetitively pulsed surface dielectric barrier discharge are investigated using electrical and optical diagnosis,and a two-dimensional fluid *** distinct discharge phases of primary,transitional and secondary streamers are identified in a single-pulse discharge through the time-resolved plasma ***,a merging phenomenon of the two opposing primary streamers is observed at the middle position of the discharge *** to the first pulse,a low streamer propagation velocity of the primary streamer is measured during the subsequent discharge process due to the limitation of residual surface charges left by the previous *** significant dif-ferences of the transferred charge and the deposited energy are obtained in the sequential pulses at a discharge gap of 9 *** simulations show that a reduction for the plasma intensity of the approached two primary streamers is attributed by the accumu-lated charge on the dielectric surface and gathered positive charges in the streamer *** and experimental studies indicate that the residual charges can be erased by the secondary streamer through the drifted electrons,namely that a phenomenon of charge self-erasing can be realized in the individual pulse.

关键词： charge dielectric charges

Icephobic materials and strategies:From bio-inspirations to smart systems

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Droplet 2024年第3期3卷 1-26页

作者： Xinlin Li Yan Liu Zhichun Zhang Yanju Liu Jinsong Leng Centre for Composite materials and Structures School of AstronauticsHarbin Institute of TechnologyHarbinChina Key Laboratory of Bionic Engineering(ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchunChina Institute of Structured and Architected materials Liaoning Academy of MaterialsShenyangChina Department of Astronautical science and mechanics Harbin Institute of TechnologyHarbinChina

Unwanted ice formations may cause severe functional degradations of facilities and also have a negative impact on their *** and removing ice accumula-tion is always a hot topic in the industrial and technological *** functional surfaces have been greatly studied for several decades and have proved to be excel-lent candidates for passive anti-/deicing ***,the drawbacks limit their potential industrial uses under harsh conditions,like low temperatures and high *** researches on bionic surfaces are focused on a certain function of nat-ural creatures and their underlined fundamental theories are revealed by taking the interface as the ***,living organisms,either plants or animals,are often sensitive and responsive to their surroundings,avoiding risks and even self-repairing upon *** this prospect,a novel view of the bionic icephobic materials has been proposed in the present review,which is expected to be studied and designed by taking the biological species as a *** two representative icephobic mate-rials,the anti-/deicing theories of superhydrophobic and slippery surfaces are first ***,the recent progress of smart icephobic strategies is summarized from interfaces to *** aim to provide new bionic insights on designing future icephobic strategies.

关键词： removing smart summarized

In situ observation of the electrochemical behavior of Li–CO_(2)/O_(2)batteries in an environmental transmission electron microscope

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Carbon Energy 2024年第4期6卷 244-255页

作者： Peng Jia Yunna Guo Dongliang Chen Jingming Yao Xuedong Zhang Jianguo Lu Yuqing Qiao Liqiang Zhang Hebei Key Laboratory of Applied Chemistry College of Environmental and Chemical EngineeringYanshan UniversityQinhuangdaoChina State Key Laboratory of metastable materials science and Technology Clean Nano Energy CenterYanshan UniversityQinhuangdaoChina State Key Laboratory of Silicon and Advanced Semiconductor materials School of Materials Science and EngineeringZhejiang UniversityHangzhouChina Key Laboratory of Low Dimensional materials and Application Technology of ministry of Education School of Materials Science and EngineeringXiangtan UniversityXiangtanChina

Li–CO_(2)/O_(2)batteries,a promising energy storage technology,not only provide ultrahigh discharge capacity but also capture CO_(2)and turn it into renewable *** electrochemical reaction pathways'ambiguity,however,creates a hurdle for their practical *** study used copper selenide(CuSe)nanosheets as the air cathode medium in an environmental transmission electron microscope to in situ study Li–CO_(2)/O_(2)(mix CO_(2)as well as O_(2)at a volume ratio of 1:1)and Li–O_(2)batteries as well as Li–CO_(2)*** discharge reactions take place successively in the Li–CO_(2)/O_(2)–CuSe nanobattery:(I)4Li^(+)+O_(2)+4e^(−)→2Li_(2)O;(II)Li_(2)O+CO_(2)→Li_(2)CO_(3).The charge reaction proceeded via(III)2Li_(2)CO_(3)→4Li^(+)+2CO_(2)+O_(2)+4e^(−).However,Li–O_(2)and Li–CO_(2)nanobatteries showed poor cycling stability,suggesting the difficulty in the direct decomposition of the discharge *** fluctuations of the Li–CO_(2)/O_(2)battery's electrochemistry were also shown to depend heavily on O_(2).The CuSe‐based Li–CO_(2)/O_(2)battery showed exceptional electrochemical *** Li^–CO_(2)/O_(2)battery offered a discharge capacity apex of 15,492 mAh g^(−1) and stable cycling 60 times at 100 mA g^(−1).Our research offers crucial insight into the electrochemical behavior of Li–CO_(2)/O_(2),Li–O_(2),and Li–CO_(2)nanobatteries,which may help the creation of high‐performance Li–CO_(2)/O_(2)batteries for energy storage applications.

关键词： CuSe nanosheets electrochemical reaction in situ environmental transmission electron microscopy Li-CO_(2)battery Li-CO_(2)/O_(2)battery Li-O_(2)battery

Comprehensive understanding and rational regulation of microenvironment for gas-involving electrochemical reactions

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Carbon Energy 2023年第7期5卷 70-99页

作者： Qiyang Cheng mengfan Wang Jiajie Ni Lifang Zhang Yu Cheng Xi Zhou Yufeng Cao Tao Qian Chenglin Yan School of Chemistry and Chemical Engineering Nantong UniversityNantongChina Key Laboratory of Core Technology of High Specific Energy Battery and Key materials for Petroleum and Chemical Industry College of EnergySoochow UniversitySuzhouChina Light Industry Institute of Electrochemical Power Sources Soochow UniversitySuzhouChina

Substantial progress has been made in the understanding of gas-involving electrochemical reactions recently for the sake of clean,renewable,and efficient energy ***,the specific influence mechanism of the microenvironment at the reaction interface on the electrocatalytic performance(activity,selectivity,and durability)remains ***,we provide a comprehensive understanding of the interfacial microenvironment of gas-involving electrocatalysis,including carbon dioxide reduction reaction and nitrogen reduction reaction,and classify the factors affecting the reaction thermodynamics and kinetics into gas diffusion,proton supply,and electron *** categorization allows a systematic survey of the literature focusing on electrolyzer-level(optimization of the device,control of the experimental condition,and design of the working electrode),electrolytelevel(increase of gas solubility,regulation of proton supply,and substitution of anodic reaction),and electrocatalyst-level strategies(promotion of gas affinity,adjustment of hydrophobicity,and enhancement of conductivity),aiming to retrieve the correlations between the microenvironment and electrochemical ***,priorities for future studies are suggested to support the comprehensive improvement of next-generation gas-involving electrochemical reactions.

关键词： CO_(2)RR electrocatalysis microenvironment NRR three-phase interface