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Chinese Physics B 2023年第4期32卷 754-761页

作者：杜鹏母一宁任航 Idelfonso Tafur Monroy 李彦正樊海波王帅 Makram Ibrahim 梁栋 School of Physics Changchun University of Science and TechnologyChangchun 130022China Institute for Photonic Integration Eindhoven University of TechnologyEindhoven 5600 MBNetherlands Science and Technology on Low-Light-Level Night Vision Laboratory Xi’an 710018China Kunming Institute of Physics Kunming 650221China Solar and Space Research Department National Research Institute of Astronomy and Geophysics(NRIAG)Cairo 11421Egypt

This research argues that using an electron beam with high kinetic energy to pump perovskite quantum dots can significantly boost the efficiency of the low-frequency photon radiation conversion.Firstly,we measure the random lasing threshold and luminescence threshold of CsPbX_(3)films pumped by an electron beam.Then,we simulate the spatial distribution of the electron beams in CsPbX_(3)films.Combined with the above data,a low-frequency photon radiation conversion model based on the electron pumped perovskite quantum dots is presented.This could be a way to create a terahertz source with a high-power output or to multiply the terahertz power.

关键词： electron beam perovskite quantum dots THz

Fabrication of a turbine disk alloy by electron beam sheet lamination and investigation on the improved high temperature creep performance

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Journal of Materials Science & Technology 2023年第12期143卷 216-233页

作者： Xiaogang You Yi Tan Masao Takeyama Pengting Li Yi Li Huixing Zhang Hongyang Cui Chuanyong Cui Yinong Wang Jiayan Li Zhijun Zhang Gengyi Dong Wenjia Xiao Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Dalian University of Technology)Ministry of EducationSchool of Materials Science and EngineeringDalian 116024China Department of Materials Science and Engineering School of Materials and Chemical TechnologyTokyo Institute of TechnologyJapan Shi-changxu Innovation Center for Advanced Materials Chinese Academy of SciencesInstitute of Metal ResearchShenyang 110016China Department of Materials Engineering The University of British ColumbiaVancouverCanada School of Mechatronics Engineering and Automation Foshan UniversityFoshan 528225China

A turbine disk alloy was prepared by electron beam sheet lamination(EBSL),giving a refined microstruc-ture and high purity,and the microstructure-property relationship of this alloy has been developed.The alloy showed an outstanding creep life of 1266.3 h at 953 K/500 MPa.Compared with the conventional vacuum induction melted and vacuum arc re-melted alloy,a smaller dendrite arm spacing of less than 23μm was obtained through the EBSL method,which restricted the formation of large inter-dendritic carbides.As a result,the typical intergranular failure mode was observed in the EBSL alloy,whereas the transgranular fracture mode was dominant in the conventional alloy.The inter-dendritic MC carbides formed from the reverse diffusion of Nb are believed to either impede grain boundary sliding or initi-ate cracks,depending on their size and morphology.The tiny grain boundary precipitates of theδphase in the EBSL alloy could reduce the critical stress for microvoid nucleation to 161.07 MPa by decoher-ing the particle/matrix interface,or allowing vacancy condensation near theδinterface,resulting in the formation of grain boundary microcracks.In the conventional alloy,however,the larger-sized MC car-bides which were formed during the solidification process(0.36 vol.%)nucleated the microcracks within the particles,leading to the transgranular fracture.Furthermore,the results indicated that the nanoscaleγ′andγ″precipitates contributed primarily to strengthening and coordinating intragranular deforma-tion during creep,in which the Orowan mechanism and shearing of a/6partial dislocations and a/2doublets were active forγ′andγ″precipitates,respectively.

关键词： electron beam Superalloy Segregation Deformation Precipitation

Improvement of tensile superelasticity by aging treatment of NiTi shape memory alloys fabricated by electron beam wire-feed additive manufacturing

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Journal of Materials Science & Technology 2023年第14期145卷 185-196页

作者： Ze Pu Dong Du Dongqi Zhang Zixiang Li Shuai Xue Rui Xi Xiebin Wang Baohua Chang Department of Mechanical Engineering State Key Laboratory of TribologyTsinghua UniversityBeijing 100084China Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJingshi Road 17923Jinan 250061China

For the first time,this work comprehensively studied the effectiveness of precipitation hardening achieved by aging treatment in improving the tensile superelasticity of NiTi alloys fabricated by elec-tron beam wire-feed additive manufacturing(EBAM),which possesses inherent advantages in producing dense and oxidation-free structures.Aging treatments under three temperatures(450,350,and 250℃)and different durations were conducted,and the resultant performance of tensile superelasticity,together with the corresponding evolution of precipitation and phase transformation behavior were investigated for the EBAM-fabricated NiTi alloys.Results showed that by appropriate aging treatment,EBAM fabricated NiTi alloys could achieve excellent recovery rates of approximately 95%and 90%after the 1st and 10th load/unload cycle for a maximum tensile strain of 6%,which were almost the highest achieved so far by AM processed NiTi alloys and close to those of some conventional NiTi alloys.The improvement of tensile superelasticity benefited from the fine and dispersive Ni4Ti3 precipitates,which could be introduced by aging at 350℃ for 4 h or at 250℃ for 200 h.Moreover,the large amount of Ni4Ti3 precipitates would promote the intermediate R-phase transformation and bring a two-stage or three-stage transformation sequence,which depended on whether the distribution of the precipitation was homogeneous or not.This work could provide guidance for the production of NiTi alloys with good tensile superelasticity by EBAM or other additive manufacturing processes.

关键词： NiTi shape memory alloys electron beam Additive manufacturing Aging treatment Tensile superelasticity

electron beam modeling and analyses of the electric field distribution and space charge effect

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Chinese Physics B 2022年第5期31卷 288-293页

作者：蒋越凌董全林 School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijingChina

In electron beam technology, one of the critical focuses of research and development efforts is on improving the measurement of electron beam parameters. The parameters are closely related to the generation, emission, operation environment, and role of the electron beam and the corresponding medium. In this study, a field calculation method is proposed, and the electric field intensity distribution on the electron beam’s cross-section is analyzed. The characteristics of beam diffusion caused by the space charge effect are investigated in simulation, and the obtained data are compared with the experiment. The simulation demonstrated that the cross-sectional electric field distribution is primarily affected by the electron beam current, current density distribution, and electron beam propagation speed.

关键词： electron beam electric field distribution space charge effect

Development of a radiographic method for measuring the discrete spectrum of the electron beam from a plasma focus device

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Plasma Science and Technology 2017年第7期19卷 26-33页

作者： Neda SHAMSIAN Babak SHIRANI BIDABADI Hosein PIRJAMADI Department of Nuclear Engineering Faculty of Advanced Sciences and Technologies University of Isfahan

An indirect method is proposed for measuring the relative energy spectrum of the pulsed electron beam of a plasma focus device. The Bremsstrahlung x-ray, generated by the collision of electrons against the anode surface, was measured behind lead filters with various thicknesses using a radiographic film system. A matrix equation was considered in order to explain the relation between the x-ray dose and the spectral amplitudes of the electron beam. The electron spectrum of the device was measured at 0.6 mbar argon and 22 kV charging voltage, in four discrete energy intervals extending up to 500 keV. The results of the experiments show that most of the electrons are emitted in the 125-375 keV energy range and the spectral amplitude becomes negligible beyond 375 keV.

关键词： magnetized plasma plasma focus plasma diagnostics electron beam energyspectrum x-ray dosimetry

High-energy-density electron beam generation in ultra intense laser-plasma interaction

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Plasma Science and Technology 2017年第1期19卷 1-6页

作者：刘建勋马燕云杨晓虎赵军余同普邵福球卓红斌甘龙飞张国博赵媛杨靖康 College of Science National University of Defense Technology Changsha 410073 People's Republic of China College of electronic Engineering Wuhan 430019 People's Republic of China IFSA-Collaborative Innovation Center Shanghai Jiao Tong University Shanghai 200240 People's Republic of China Laser Fusion Research Center China Academy of Engineering Physics Mianyang 621000 People's Republic of China

By using a two-dimensional particle-in-cell simulation,we demonstrate a scheme for highenergy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum（Al） target.With the laser having a peak intensity of 4×10^23W cm^-2,a high quality electron beam with a maximum density of 117 nc and a kinetic energy density up to8.79×10^18J m^-3 is generated.The temperature of the electron beam can be 416 Me V,and the beam divergence is only 7.25°.As the laser peak intensity increases（e.g.,1024 W cm^-2）,both the beam energy density（3.56×10^19J m^-3） and the temperature（545 Me V） are increased,and the beam collimation is well controlled.The maximum density of the electron beam can even reach 180 nc.Such beams should have potential applications in the areas of antiparticle generation,laboratory astrophysics,etc.

关键词： ultra intense laser plasma high-energy-density electron beam

Modeling and Experimental Validation of the electron beam Selective Melting Process

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Engineering 2017年第5期3卷 701-707页

作者： Wentao Yan Ya Qian Weixin Ma Bin Zhou Yongxing Shen Feng Lin Department of Mechanical Engineering Tsinghua University Beijing 100084 China Department of Mechanical Engineering Northwestern University Evanston IL 60201 USA State Key Lab of Metal Matrix Composites Shanghai Jiao Tong University Shanghai 200240 China

electron beam selective melting (EBSM) is a promising additive manufacturing (AM) technology. The EBSM process consists of three major procedures: ① spreading a powder layer, ② preheating to slightly sinter the powder, and ③ selectively melting the powder bed. The highly transient multi-physics phenomena involved in these procedures pose a significant challenge for in situ experimental observation and measurement. To advance the understanding of the physical mechanisms in each procedure, we leverage high-fidelity modeling and post-process experiments. The models resemble the actual fabrication procedures, including ① a powder-spreading model using the discrete element method (DEM), ② a phase field (PF) model of powder sintering (solid-state sintering), and ③ a powder-melting (liquid-state sintering) model using the finite volume method (FVM). Comprehensive insights into all the major procedures are provided, which have rarely been reported. Preliminary simulation results (including powder particle packing within the powder bed, sintering neck formation between particles, and single-track defects) agree qualitatively with experiments, demonstrating the ability to understand the mechanisms and to guide the design and optimization of the experimental setup and manufacturing process.

关键词： Modeling electron beam Additive manufacturing Powder scale

Numerical and Experimental Investigation of electron beam Air Plasma Properties at Moderate Pressure

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Plasma Science and Technology 2014年第1期16卷 6-11页

作者：邓永锋谭永华韩先伟 Shaanxi Power Machine Design and Research Institute Academy of Aerospace Propulsion Technology

Large size of air plasma at near atmospheric pressure has specific effects in aerospace applications. In this paper, a two dimensional multi-fluid model coupled with Monte Carlo （MC） model is established, and some experiments were carried out to investigate the characteristics of electron beam air plasma at pressure of 100-170 Torr. Based on the model, the properties of electron beam air plasma are acquired. The electron density is of the order of 1016 m-3 and the longitudinal size can exceed 1.2 m. The profiles of charged particles demonstrate that the oxygen molecule is very important for air plasma and its elementary processes play a key role in plasma equilibrium processes. The potential is almost negative and a very low potential belt is observed at the edge of plasma acting as a protection shell. A series of experiments were carried out in a low pressure vacuum facility and the beam plasma densities were diagnosed. The experimental results demonstrate that electron density increased with the electron beam energy, and the relatively low pressure was favorable for gaining high density plasma. Hence in order to achieve high density and large size plasma, it requires the researchers to choose proper discharge parameters.

关键词： electron beam air plasma microwave measurement

Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

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Plasma Science and Technology 2017年第4期19卷 1-6页

作者：邓永锋蒋建韩先伟谭畅魏建国 Shaanxi Key Laboratory of Plasma Physics and Applied Technology Xi'an 710100 People's Republic of China State Key Laboratory of Liquid Rocket Science and Technology Xi'an 710100 People's Republic of China Academy of Aerospace Propulsion Technology Xi'an 710100 People's Republic of China

potential flow control method for large scale flow.In this paper,a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma.The results demonstrate that the electron beam strongly influences the flow properties,not only in the boundary layers,but also in the main flow.A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam.It brings additional energy into air,and the inducing characteristics are closely related to the beam power and increase nonlinearly with it.The injection angles also influence the flow properties to some extent.Based on this research,we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications,i.***.the high energy density,wide action range and excellent action effect.Due to the rapid development of near space hypersonic vehicles and atmospheric fighters,by optimizing the parameters,the electron beam can be used as an alternative means in aerodynamic steering in these applications.

关键词： electron beam air plasma aerodynamics applications

High energy electron beam generation during interaction of a laser accelerated proton beam with a gas-discharge plasma

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Plasma Science and Technology 2022年第5期24卷 75-79页

作者：徐汪文胡章虎惠得轩王友年 School of Physics Dalian University of TechnologyDalian 116024People's Republic of China

The study of the interaction between ion beam and plasma is very important to the areas of inertial fusion energy and high energy density physics. With detailed one-dimensional electromagnetic particle-in-cell simulations, we investigate here the interaction of a laseraccelerated proton beam assuming an ideal monoenergetic beam with a gas-discharge plasma.After the saturation stage of the two-stream instability excited by the proton beam, significant high energy electrons are observed, with maximum energy approaching 2 MeV, and a new twostream instability occurs between the high energy electrons and background electrons. The trajectories of plasma electrons are studied, showing the process of electron trapping and detrapping from the wakefield.

关键词： electron beam proton beam two-stream instability particle-in-cell simulation