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Numerical study on THz radiation of two-dimensional plasmon resonance of GaN HEMT array

Chinese Physics B 2023年第4期32卷 268-276页

作者：郭宏阳张平杨生鹏王少萌宫玉彬 National Key Laboratory of Science and Technology on Vacuum Electronics University of Electronic Science and Technology of ChinaChengdu 610031China

The Ga N high electron mobility transistor(HEMT)has been considered as a potential terahertz(THz)radiation source,yet the low radiation power level restricts their *** HEMT array is thought to improve the coupling efficiency between two-dimensional(2D)plasmons and THz *** this work,we investigate the plasma oscillation,electromagnetic radiation,and the integration characteristics of Ga N HEMT targeting at a high THz radiation power *** quantitative radiation power and directivity are obtained for integrated Ga N HEMT array with different array periods and element *** the same initial plasma oscillation phase among the HEMT units,the radiation power of the two-element HEMT array can achieve 4 times as the single HEMT radiation power when the array period is shorter than 1/8electromagnetic *** addition,the radiation power of the HEMT array varies almost linearly with the element number,the smaller array period can lead to the greater radiation *** shows that increasing the array period could narrow the main radiated lobe width while weaken the radiation *** the element number can improve both the radiation directivity and *** also synchronize the plasma wave phases in the HEMT array by adopting an external Gaussian plane wave with central frequency the same as the plasmon resonant frequency,which solves the problem of the radiation power reduction caused by the asynchronous plasma oscillation phases among the *** study of the radiation power amplification of the one-dimensional(1D)Ga N HEMT array provides useful guidance for the research of compact high-power solid-state terahertz sources.

关键词： GaN HEMT array two-dimensional(2D)plasmons THz emission

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Experimental and numerical simulation study of the effect for the anode positions on the discharge characteristics of 300W class low power Hall thrusters

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Plasma science and technology 2023年第1期25卷 100-110页

作者：陈新伟高俊杨三祥耿海郭宁顾左杨俊泰张宏 Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of PhysicsLanzhou 730000People's Republic of China

Low-power Hall thruster(LHT) generally has poor discharge efficiency characteristics due to the large surface-to-volume *** to further refine and improve the performance of 300 W class LHT in terms of thrust and efficiency,and to obtain the most optimal operating point,the experimental study of the discharge characteristics for three different anode positions was conducted under the operation of various discharge voltages(100-400 V) and anode mass flow rates(0.65 mg·s-1and 0.95 mg·s-1).The experimental results indicated that the thruster has the most excellent performance in terms of thrust and efficiency etc at a channel length of 27 mm for identical operating *** addition,particle in cell simulations,employed to reveal the underlying physical mechanisms,show that the ionization and acceleration zone is pushed downwards towards the channel exit as the anode moves towards the *** the identical operating point,when the channel length is reduced from 32 to 27 mm,the ionization and acceleration zone moves towards the exit,and the parameters such as thrust and efficiency increase due to the high ionization rate,ion number density,and axial electric *** the channel length is further moved to 24 mm,the parameters in terms of thrust(F) and efficiency(ηa) are reduced as a result of the decreasing ionization efficiency(ηm) and the larger plume divergence angle(α).In this paper,the results indicated that an optimum anode position(ΔL=27 mm) exists for the optimum performance.

关键词： low-power Hall thruster discharge characteristics PIC-MCC simulation anode positions

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Study of beam divergence and thrust vector eccentricity characteristics of the Hall thruster based on dual Faraday probe array planes and its applications

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Plasma science and technology 2023年第5期25卷 104-115页

作者：陈新伟赵勇田恺高俊孙明明孙新锋郭宁张宏王尚民冯杰陈焘耿海杨俊泰史楷 Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of PhysicsLanzhou 730000People’s Republic of China

The accurate knowledge of the thrust vector eccentricity and beam divergence characteristics of Hall thrusters are of significant engineering value for the beneficial integration and successful application of Hall thrusters on *** the characteristics of the plume bipolar diffusion due to the annular discharge channel of the Hall thruster,a Gaussian-fitted method for thrust vector deviation angle and beam divergence of Hall thrusters based on dual Faraday probe array planes was proposed in respect of the Hall thruster beam *** results show that the ratios of the deviation between the maximum and minimum values of the beam divergence angle and the thrust vector eccentricity angle using a Gaussian fit to the optimized Faraday probe dual plane to the mean value are 1.4%and 11.5%,*** optimized thrust vector eccentricity angle obtained has been substantially improved,by approximately 20%.The beam divergence angle calculated using a Gaussian fitting to the optimized Faraday probe dual plane is approximately identical to the non-optimized *** beam divergence and thrust vector eccentricity angles for different anode mass flow rates were obtained by averaging the beam divergence and thrust vector eccentricity angles calculated by the dual-plane,Gaussian-fitted ion current density method for different *** study not only allows for an immediate and effective tool for determining the design of thrust vector adjustment mechanisms of spacecraft with different power Hall thrusters but also for characterizing the 3D spatial distribution of the Hall thruster plume.

关键词： Hall thruster beam divergence thrust vector eccentricity dual Faraday probe array planes

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Relaxation model for a homogeneous plasmas with spherically symmetric velocity space

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Chinese Physics B 2025年第1期34卷 388-399页

作者： Yanpeng Wang Jianyuan Xiao Xianhao Rao Pengfei Zhang Yolbarsop Adil Ge Zhuang School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China Laoshan Laboratory Qingdao 266100China School of Physical Sciences University of Science and Technology of ChinaHefei 230026China

We derive the transport equations from the Vlasov–Fokker–Planck equation when the velocity space is spherically *** Shkarofsky's form of Fokker–Planck–Rosenbluth collision operator is employed in the Vlasov–Fokker–Planck equation.A closed-form relaxation model for homogeneous plasmas could be presented in terms of Gauss *** has been accomplished based on the Maxwellian mixture ***,we demonstrate that classic models such as two-temperature thermal equilibrium model and thermodynamic equilibrium model are special cases of our relaxation model and the zeroth-order Braginskii heat transfer model can also be *** present relaxation model is a nonequilibrium model based on the hypothesis that the plasmas system possesses finitely distinguishable independent features,without relying on the conventional near-equilibrium assumption.

关键词： finitely distinguishable independent features hypothesis Maxwellian mixture model Fokker-Planck-Rosenbluth collision operator spherical symmetry

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Laser-assisted synthesis of PtPd alloy for efficient ethanol oxidation

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Nano Research 2024年第7期17卷 6032-6037页

作者： Zihang Chen Tong Liu Huijuan Zhang Beibei Pang Yuanhua Sun Longfei Hu Qiquan Luo Xiaokang Liu Linlin Cao Tao Yao School of Nuclear Science and Technology National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230029China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China

The inefficiency of ethanol oxidation reaction(EOR)presents a significant obstacle in harnessing renewable biofuels with high energy density into *** efforts,most Pt-based catalysts still suffer from drawbacks such as poor activity and susceptibility to CO poisoning,particularly in acidic ***,we employed a physical laser-assisted approach to synthetize a PtPd alloy with a 1:1 atomic *** alloy demonstrates remarkable performance in acidic EOR,boasting a high mass activity of 1.86 A·mgPt^(−1)and competitive resistance to *** in situ synchrotron radiation infrared spectroscopy with theoretical calculations,we reveal that the synergic interaction between Pt and Pd enhances both the adsorption of OH*intermediate and the dehydrogenation ability of *** work will prove the feasibility of synthesizing bimetallic alloys by a physical laser-assisted strategy and promote the development of advanced alloy electrocatalysts.

关键词： laser-assisted strategy Pt-based alloy in situ synchrotron radiation infrared spectroscopy ethanol oxidation reaction synergic interaction

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Progress and prospects in magnesium alloy scrap recycling

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Journal of Magnesium and Alloys 2024年第12期12卷 4828-4867页

作者： Lipeng Wang Dong Liang Rong Yu Meng Wang Yang Tian Tingzhuang Ma Bin Yang Baoqiang Xu Wenlong Jiang Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province Kunming University of Science and TechnologyKunming 650093China State Key Laboratory of Complex Non-ferrous Metal Resources Clean Utilization Kunming University of Science and TechnologyKunming 650093China National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and TechnologyKunming650093China Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming 650093China

Magnesium(Mg)alloy is widely used in aerospace and automotive industries as an excellent lightweight metal material to reduce carbon *** expansion of Mg alloy applications and the increasing demands for these materials have significantly facilitated the generation of Mg alloy *** recycling of Mg resources is crucial for promoting both environmental sustainability and economic ***,current recycling effect is ***,this paper provides a comprehensive review of the entire recycling process,including scrap classification,separation and sorting,pre-treatment,and *** paper explores the generation of Mg alloy scrap and its reincorporation into industrial *** review outlines various Mg scrap recycling technologies based on different phase *** include liquid-state recycling(such as flux refining,impurity removal additives,fluxless refining,compound treatment,and direct remelting),solid-state recycling(involving hot extrusion,equal-channel angular pressing(ECAP),friction stir extrusion(FSE),and spark plasma sintering(SPS)),vapor-state recycling(comprising vacuum distillation and sublimation),electrochemical recycling(solid oxide membrane(SOM)electrolysis,RE-12TMelectrorefining,and non-aqueous solution electrorefining),and Mg secondary alloy *** advantages and existing challenges associated with each method are compared and discussed,and the current obstacles to the future recycling of complex scrap are examined.

关键词： Magnesium alloy Scrap recycling Recycling techniques

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Design and experimental study of a field-reversed configuration plasma thruster prototype

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Plasma science and technology 2025年第3期27卷 118-126页

作者： Yuxuan HUANG Ming ZHANG Yong YANG Fangwei LYU Xiaopeng YI Chaofan LYU Yisong ZHANG Bo RAO State Key Laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma PhysicsSchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China National Key Laboratory of Science and Technology on Vacuum Technology and Physics Lanzhou Institute of PhysicsLanzhou 730000People’s Republic of China

The field-reversed configuration(FRC)plasma thruster driven by rotating magnetic field(RMF),abbreviated as the RMF-FRC thruster,is a new type of electric propulsion technology that is expected to accelerate the deep space *** experimental prototype,including diagnostic devices,was designed and constructed based on the principles of the RMF-FRC thruster,with an RMF frequency of 210 kHz and a maximum peak current of 2 *** the rated operating conditions,the initial plasma density was measured to be 5×10^(17)m^(-3),and increased to 2.2×10^(19)m^(-3)after the action of *** coupling efficiency of RMF was about 53%,and the plasma current reached 1.9 *** axial magnetic field changed in reverse by 155 Gauss,successfully reversing the bias magnetic field of 60 Gauss,which verifies the formation of FRC *** optimization research,it was found that when the bias magnetic field is 100 Gauss,the axial magnetic field reverse variation caused by FRC is the highest at 164 *** experimental results are discussed and strategies are proposed to improve the performance of the prototype.

关键词： rotating magnetic field(RMF) field-reversed configuration(FRC) plasma thrusters plasma current

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Regulating atomic Fe-Rh site distance for efficient oxygen reduction reaction

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science China Chemistry 2024年第4期67卷 1352-1359页

作者： Tong Liu Yudan Chen Airong Xu Xiaokang Liu Dong Liu Sicheng Li Hui Huang Li Xu Shuaiwei Jiang Qiquan Luo Tao Ding Tao Yao National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Key Laboratory of Precision and Intelligent Chemistry Hefei National Research Center for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei 230026China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China

Exploring the atomic interaction mechanisms of dense single-atom catalysts(SACs)is of great significance for their application in oxygen reduction reaction(ORR).However,the intrinsic mechanism of the site-distance effect on the catalytic performance has been largely ***,we demonstrate the site-distance effect of Fe-Rh_(x)@NC catalysts in ORR theoretically and *** charge analysis reveals that the strong interaction between Fe and Rh atoms at a certain atomic distance(dFe-Rh)alters the catalytic electronic structure,facilitating the optimization of catalyst adsorption *** by the theoretical calculations,we designed and synthesized the Fe-Rhx@NC catalysts through a spatial confinement *** characterization results prove that the Fe-Rh_(2)@NC has the optimal d_(Fe-Rh),which improves its intrinsic ORR activity,providing a half wave potential of 0.91 V,higher than that of the commercial Pt/C(0.86 V).This study emphasizes the importance of determining the basic mechanism of the site-distance effect in dissimilar metal atoms catalysts,which is conducive to the design of efficient catalyst systems for practical applications.

关键词： Density functional theory single-atom catalyst in-situ encapsulating site-distance effect oxygen reduction reaction

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A CNN-SVR model for NO_(2)profile prediction based on MAX-DOAS observations:The influence of Chinese New Year overlapping the 2020 COVID-19 lockdown on vertical distributions of tropospheric NO_(2)in Nanjing,China

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Journal of Environmental sciences 2024年第7期141卷 151-165页

作者： Xin Tian Zijie Wang Pinhua Xie Jin Xu Ang Li Yifeng Pan Feng Hu Zhaokun Hu Mingsheng Chen Jiangyi Zheng Information Materials and Intelligent Sensing Laboratory of Anhui Province Institutes of Physical Science and Information TechnologyAnhui UniversityHefei 230601China Key laboratory of Environmental Optical and Technology Anhui Institute of optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China School of Environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China

In this study,a hybrid model,the convolutional neural network-support vector regression model,was adopted to achieve prediction of the NO_(2)profile in Nanjing from January 2019to March *** the sudden decline in NO_(2)in February 2020,the contribution of the Coronavirus Disease-19(COVID-19)lockdown,Chinese New Year(CNY),and meteorologi cal conditions to the reduction of NO_(2)was ***_(2)vertical column densities(VCDs) from January to March 2020 decreased by 59.05%and 32.81%,relative to the same period in 2019 and 2021,*** the period of 2020 COVID-19,the average NO_(2)VCDs were 50.50%and 29.96%lower than those during the pre-lockdown and post-lockdown pe riods,*** NO_(2)volume mixing ratios(VMRs)during the 2020 COVID-19 lock down significantly decreased below 400 *** NO_(2)VMRs under the different wind fields were significantly lower during the lockdown period than during the pre-lockdown period This phenomenon could be attributed to the 2020 COVID-19 *** NO_(2)VMRs be fore and after the CNY were significantly lower in 2020 than in 2019 and 2021 in the same period,which further proves that the decrease in NO_(2)in February 2020 was attributed to the COVID-19 *** source analysis of an NO_(2)pollution episode during the lockdown period showed that the polluted air mass in the Beijing-Tianjin-Hebei was trans ported southwards under the action of the north wind,and the subsequent unfavorable meteorological conditions(local wind speed of<2.0 m/sec)resulted in the accumulation o pollutants.

关键词： MAX-DOAS CNN-SVR Nitrogen dioxide COVID-19 Chinese New Year Regional transport

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Efficient synthesis of bottle-brush polymers enabled by selective photoactivation strategy in NIR-induced PET-RAFT polymerization

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science China Chemistry 2024年第7期67卷 2353-2361页

作者： Hao Zha Lin Cheng Zuowei Wang Chao Liu Chunyan Hong Department of Polymer Science and Engineering University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China

Bottle-brush polymers possessing densely grafted side chains have special properties that are distinct from linear ***,an efficient method for preparing bottle-brush polymers based on a selective photoactivation strategy in the photoinduced electron/energy transfer reversible addition-fragmentation chain transfer(PET-RAFT)polymerization was developed.A methacrylate monomer 2-(2-(dodecylthiocarbonothioylthio)propionate)ethyl methacrylate(DTPEMA)containing a 2-(dodecylthiocarbonothioylthio)propionate(DTP)unit with a secondary R group was *** the unique selectivity of metal naphthalocyanine photocatalyst zinc 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine(ZnTtBNc)toward trithiocarbonate with tertiary R group,the PET-RAFT polymerization of DTPEMA catalyzed by ZnTtBNc was performed under near infrared(NIR)light(λ_(max)=760 nm)irradiation at room temperature,using 4-cyano-4-[(dodecylsulfanylthiocarbonyl)-sulfanyl]pentanoic acid(CDTPA)with a tertiary R group as a chain transfer agent(CTA).Proton nuclear magnetic resonance(1H NMR)and gel permeation chromatography(GPC)results demonstrated that the DTP units in the side chains were inert during the *** grafting poly(methyl acrylate)(PMA)from PDTPEMA via thermal-initiated RAFT polymerization,welldefined P(DTPEMA-g-PMA)bottle-brush polymers could be ***,the film prepared from the bottle-brush polymer exhibited excellent scratch self-healing property due to the interlocking of side chains.

关键词： bottle-brush polymers PET-RAFT polymerization selective photoactivation scratch self-healing

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