This research examines the dynamics of a cosh-Gaussian laser pulse travelling through a vacuum and its impact on electron acceleration. We examine the impact of several critical factors, such as laser electric field a...This research examines the dynamics of a cosh-Gaussian laser pulse travelling through a vacuum and its impact on electron acceleration. We examine the impact of several critical factors, such as laser electric field amplitude, decentered parameter, beam waist, and laser chirp parameter, on the energy gain of electrons using coupled momentum equations. Our results indicate that the energy acquisition of electrons escalates with the amplitude of the laser electric field, decentered parameter, and chirp parameter. An appropriate beam waist is essential for attaining energyefficient electron acceleration in a vacuum. Through the optimization of these parameters, we get a maximum electron energy gain of 2.80 Ge V. This study highlights the significance of customized laser pulse attributes in improving electron acceleration and aids in the progression of high-energy particle physics.展开更多
The nanoscale air channel device(NACD)has recently gained significant attention as a novel vacuum electronic that can be fabricated through nanofabrication technologies.Here,the research and progress of the NACD since...The nanoscale air channel device(NACD)has recently gained significant attention as a novel vacuum electronic that can be fabricated through nanofabrication technologies.Here,the research and progress of the NACD since it was reviewed,with a focus on working mechanism analysis,nanofabrication technologies,device structure optimization,electrode materials and simulation approach.Furthermore,the application fields and future development of NACD were summarized and prospected.The NACDs are expected to surpass the physical limits of traditional solid transistors due to its advantages such as smaller heat loss,high-speed,resistance to harsh environments.展开更多
Reliable observations find only three neutrino mass eigenstates, oscillating between each other as neutrinos travel through space, and limit the sum of the three neutrino masses. At a minimum, any reliable description...Reliable observations find only three neutrino mass eigenstates, oscillating between each other as neutrinos travel through space, and limit the sum of the three neutrino masses. At a minimum, any reliable description of neutrinos must allow only three neutrino mass eigenstates and predict a neutrino mass sum consistent with observations. This paper describes neutrinos as spheres, with radius one quarter of their Compton wavelength and thickness of the Planck length, surrounding a central core along their rotation axis, with diameter of the Planck length. This description of neutrinos as excitations of the vacuum energy allows only three neutrino mass eigenstates and predicts a neutrino mass sum consistent with observations.展开更多
In this paper,three magnetrons with each of them having specifically designed multiple coupling ports,which deliver specific power distribution for developing a magnetron array based on efficient phase locking between...In this paper,three magnetrons with each of them having specifically designed multiple coupling ports,which deliver specific power distribution for developing a magnetron array based on efficient phase locking between them,are proposed to produce high powerμs-level pulses.To demonstrate the effectiveness of the magnetron with one and two coupling ports as a unit for efficient phase locking,we designed experimentally the coupling ports delivering~10%(the power distribution ratio)of the output power of the magnetron for coupling with other magnetron units.The effect of one and two coupling ports on the operating capability,including the power distribution ratio,anode current and frequency,is demonstrated by establishing an equivalent experimental model which can characterize an ideal operation of the array.The experimental results show that the power distribution ratio is~9%for the magnetron with one coupling port,and~12.5%(coupling port 1,2)for the magnetron with two coupling ports.This shows good uniformity of the coupling capability of the two coupling ports and provides guidance for optimizing the power distribution ratio of multiport magnetron units,which are critical for efficient phase locking in the proposed array in future and higher power arrays.展开更多
The residual stresses distribution of 7075 aluminum alloy in vacuum electron beam welding joint was numerically simulated using nonlinear finite element method. The result shows that the longitudinal residual stress i...The residual stresses distribution of 7075 aluminum alloy in vacuum electron beam welding joint was numerically simulated using nonlinear finite element method. The result shows that the longitudinal residual stress is tension stress along weld center and the stress peak value appears in the middle of the welded seam; the transversal residual stress is compression stress ; the residual stress in thickness direction is very small.展开更多
This paper investigates the properties of the ultrashort pulsed beam aimed to the capture-and-acceleration-scenario （CAS） vacuum electron acceleration. The result shows that the spatiotemporal distribution of the ph...This paper investigates the properties of the ultrashort pulsed beam aimed to the capture-and-acceleration-scenario （CAS） vacuum electron acceleration. The result shows that the spatiotemporal distribution of the phase velocity, the longitudinal component of the electric field and the acceleration quality factor are qualitatively similar to that of the continuous-wave Gaussian beam, and are slightly influenced by the spatiotemporal coupling of the ultrashort pulsed beam. When the pulse is compressed to an ultrashort one in which the pulse duration TFWHM 〈 5T0, the variation of the maximum net energy gain due to the carrier-envelope phase is a crucial disadvantage in the CAS acceleration process.展开更多
Spectroscopic characterization of clusters is crucial to understanding the structures and reaction mechanisms at the microscopic level,but it has been proven to be a grand challenge for neutral clusters because the ab...Spectroscopic characterization of clusters is crucial to understanding the structures and reaction mechanisms at the microscopic level,but it has been proven to be a grand challenge for neutral clusters because the absence of a charge makes it di伍cult for the size selection and detection.Infrared(IR)spectroscopy based on threshold photoionization using a tunable vacuum ultraviolet free electron laser(VUV-FEL)has recently been developed in the lab.The IR-VUV depletion and IR+VUV enhancement spectroscopic techniques open new avenues for size-selected IR spectroscopies of a large variety of neutral clusters without confinement(i.e.,an ultraviolet chromophore,a messenger tag,or a host matrix).The spectroscopic principles have been demonstrated by investigations of some neutral water clusters and some metal carbonyls.Here,the spectroscopic principles and their applications for neutral clusters are reviewed.展开更多
Some parts with capillary to plate joint have important application in aerocrafi. Vacuum electron beam brazing （VEBB） technology is used to realize this jointing with capillaries. Firstly 3D finite element analysis ...Some parts with capillary to plate joint have important application in aerocrafi. Vacuum electron beam brazing （VEBB） technology is used to realize this jointing with capillaries. Firstly 3D finite element analysis model is built in this paper according to this special structure. And then ANSYS finite element analysis software is used to analyze brazing temperature field at different brazing parameters. The calculation results show that the temperature field of simulation has good agreement with that measured by experiment, which proves dependence of the model built in this paper. And also reference parameters could be provided for real brazing process through calculation in this model. Brazed joint of capiUary to plate with good performance is achieved using VEBB technology. The achievement of the study will be applied in aerocrafi in the future.展开更多
The one-dimensional photonic crystals of Ag/SiO_(2) system are studied to investigate the photonic band gaps (PBG). The samples were prepared by the ultra-high vacuum electron beam evaporation. The clear band gaps wer...The one-dimensional photonic crystals of Ag/SiO_(2) system are studied to investigate the photonic band gaps (PBG). The samples were prepared by the ultra-high vacuum electron beam evaporation. The clear band gaps were observed. Satisfactory agreement between experimental and calculated results was obtained without fitting. The thickness of SiO_(2 )film has influence on the photonic band gap, as well as it awfully affects the transmittance of Ag. More layers can get clearer PBG.展开更多
A new method was developed based on the electron beam vacuum dispersion（EBVD） technology to prepare the PTFE polymer coating of the new polymer quartz piezoelectric crystal sensor for testing liquor products. The ne...A new method was developed based on the electron beam vacuum dispersion（EBVD） technology to prepare the PTFE polymer coating of the new polymer quartz piezoelectric crystal sensor for testing liquor products. The new method was applied in the new EBVD equipment which we designed. A real-time system monitoring the polymer coating＇s thickness was designed for the new EBVD equipment according to the quartz crystal microbalance（QCM） principle, playing an important role in preparing stable and uniform PTFE polymer coatings of the same thickness. 30 pieces of PTFE polymer coatings on the surface of the quartz crystal basis were prepared with the PTFE polymer ultrafine powder（purity ≥ 99.99%）as the starting material. We obtained 30 pieces of new PTFE polymer sensors. By using scanning electron microscopy（SEM）, the structure of the PTFE polymer coating＇s column clusters was studied. One sample from the 30 pieces of new PTFE polymer sensors was analysed by SEM in four scales, i.e., 400×, 1000×, 10000×, and 25000×. It was shown that under the condition of high bias voltage and low bias current, uniformly PTFE polymer coating could be achieved, which indicates that the new EBVD equipment is suitable for mass production of stable and uniform polymer coating.展开更多
Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, t...Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.展开更多
By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has th...By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has the lowest turn-on field, the highest current density, and the highest emission efficiency due to its good contact with the substrate and relatively weak field shielding effect. Experiments show that the morphology and orientation of one-dimensional ZnO nanomaterials have a great influence on its conduction field and emission current density, and the nanoarrays also contribute to electron emission. The research results have a certain reference value for the application of ZnO nanorod arrays as cathode materials for field emission devices.展开更多
文摘This research examines the dynamics of a cosh-Gaussian laser pulse travelling through a vacuum and its impact on electron acceleration. We examine the impact of several critical factors, such as laser electric field amplitude, decentered parameter, beam waist, and laser chirp parameter, on the energy gain of electrons using coupled momentum equations. Our results indicate that the energy acquisition of electrons escalates with the amplitude of the laser electric field, decentered parameter, and chirp parameter. An appropriate beam waist is essential for attaining energyefficient electron acceleration in a vacuum. Through the optimization of these parameters, we get a maximum electron energy gain of 2.80 Ge V. This study highlights the significance of customized laser pulse attributes in improving electron acceleration and aids in the progression of high-energy particle physics.
基金funded by the National Key Research and Development Program(No.2022YFE0124200)the National Natural Science Foundation of China(No.U2241221)+1 种基金National Innovation Center of Radiation Applications(No.KFZC2021020501)Functional Materials and Devices Technology Innovation Team of Guizhou Province University,Qian Jiaoji(No.[2023]058).
文摘The nanoscale air channel device(NACD)has recently gained significant attention as a novel vacuum electronic that can be fabricated through nanofabrication technologies.Here,the research and progress of the NACD since it was reviewed,with a focus on working mechanism analysis,nanofabrication technologies,device structure optimization,electrode materials and simulation approach.Furthermore,the application fields and future development of NACD were summarized and prospected.The NACDs are expected to surpass the physical limits of traditional solid transistors due to its advantages such as smaller heat loss,high-speed,resistance to harsh environments.
文摘Reliable observations find only three neutrino mass eigenstates, oscillating between each other as neutrinos travel through space, and limit the sum of the three neutrino masses. At a minimum, any reliable description of neutrinos must allow only three neutrino mass eigenstates and predict a neutrino mass sum consistent with observations. This paper describes neutrinos as spheres, with radius one quarter of their Compton wavelength and thickness of the Planck length, surrounding a central core along their rotation axis, with diameter of the Planck length. This description of neutrinos as excitations of the vacuum energy allows only three neutrino mass eigenstates and predicts a neutrino mass sum consistent with observations.
基金This work is supported in part by National Natural Science Foundation of China(No.62401125)Natural Science Foundation of Sichuan Province(No.2023NSFSC1376)Fundamental Research Funds for the Central Universities(No.ZYGX2024J008)。
文摘In this paper,three magnetrons with each of them having specifically designed multiple coupling ports,which deliver specific power distribution for developing a magnetron array based on efficient phase locking between them,are proposed to produce high powerμs-level pulses.To demonstrate the effectiveness of the magnetron with one and two coupling ports as a unit for efficient phase locking,we designed experimentally the coupling ports delivering~10%(the power distribution ratio)of the output power of the magnetron for coupling with other magnetron units.The effect of one and two coupling ports on the operating capability,including the power distribution ratio,anode current and frequency,is demonstrated by establishing an equivalent experimental model which can characterize an ideal operation of the array.The experimental results show that the power distribution ratio is~9%for the magnetron with one coupling port,and~12.5%(coupling port 1,2)for the magnetron with two coupling ports.This shows good uniformity of the coupling capability of the two coupling ports and provides guidance for optimizing the power distribution ratio of multiport magnetron units,which are critical for efficient phase locking in the proposed array in future and higher power arrays.
基金The project is supported by the Found of Key Fields Project of Inner Mongolia Education Department (No ZL02021)
文摘The residual stresses distribution of 7075 aluminum alloy in vacuum electron beam welding joint was numerically simulated using nonlinear finite element method. The result shows that the longitudinal residual stress is tension stress along weld center and the stress peak value appears in the middle of the welded seam; the transversal residual stress is compression stress ; the residual stress in thickness direction is very small.
基金Project supported by the Natural Science Foundation of China （Grant Nos 60538010, 10335030 and 10376009）, the Science and Technology Commission of Shanghai, China （Grant Nos 05JC14005 and 05SG02）, and the Graduate Science and Technology Innovation Foundation of Fudan University, China.
文摘This paper investigates the properties of the ultrashort pulsed beam aimed to the capture-and-acceleration-scenario （CAS） vacuum electron acceleration. The result shows that the spatiotemporal distribution of the phase velocity, the longitudinal component of the electric field and the acceleration quality factor are qualitatively similar to that of the continuous-wave Gaussian beam, and are slightly influenced by the spatiotemporal coupling of the ultrashort pulsed beam. When the pulse is compressed to an ultrashort one in which the pulse duration TFWHM 〈 5T0, the variation of the maximum net energy gain due to the carrier-envelope phase is a crucial disadvantage in the CAS acceleration process.
基金This work was supported by the National Natural Science Foundation of China(No.92061203 and No.21688102)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB17000000)+3 种基金International Partnership Program of Chinese Academy of Sciences(121421KYSB20170012)Chinese Academy of Sciences(GJJSTD20190002)K.C.Wong Education Foundation(GJTD-2018-06)Dalian Institute of Chemical Physics(DICP DCLS201702).
文摘Spectroscopic characterization of clusters is crucial to understanding the structures and reaction mechanisms at the microscopic level,but it has been proven to be a grand challenge for neutral clusters because the absence of a charge makes it di伍cult for the size selection and detection.Infrared(IR)spectroscopy based on threshold photoionization using a tunable vacuum ultraviolet free electron laser(VUV-FEL)has recently been developed in the lab.The IR-VUV depletion and IR+VUV enhancement spectroscopic techniques open new avenues for size-selected IR spectroscopies of a large variety of neutral clusters without confinement(i.e.,an ultraviolet chromophore,a messenger tag,or a host matrix).The spectroscopic principles have been demonstrated by investigations of some neutral water clusters and some metal carbonyls.Here,the spectroscopic principles and their applications for neutral clusters are reviewed.
文摘Some parts with capillary to plate joint have important application in aerocrafi. Vacuum electron beam brazing （VEBB） technology is used to realize this jointing with capillaries. Firstly 3D finite element analysis model is built in this paper according to this special structure. And then ANSYS finite element analysis software is used to analyze brazing temperature field at different brazing parameters. The calculation results show that the temperature field of simulation has good agreement with that measured by experiment, which proves dependence of the model built in this paper. And also reference parameters could be provided for real brazing process through calculation in this model. Brazed joint of capiUary to plate with good performance is achieved using VEBB technology. The achievement of the study will be applied in aerocrafi in the future.
基金Supported by the National High Technology Development Program of China(Grant No.2003AA32720)Shanghai Nanotechnology Promotion Center(0352nm016, 0359nm204,0252nm084)+2 种基金Science and Technology Council of Shanghai(03dz11009)Fore-research of basic research project(2001CCA02800)the special Foundation for State Major Basic Research Programmeof China(Grant No.001CB610408)
文摘The one-dimensional photonic crystals of Ag/SiO_(2) system are studied to investigate the photonic band gaps (PBG). The samples were prepared by the ultra-high vacuum electron beam evaporation. The clear band gaps were observed. Satisfactory agreement between experimental and calculated results was obtained without fitting. The thickness of SiO_(2 )film has influence on the photonic band gap, as well as it awfully affects the transmittance of Ag. More layers can get clearer PBG.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2013AA030901)
文摘A new method was developed based on the electron beam vacuum dispersion（EBVD） technology to prepare the PTFE polymer coating of the new polymer quartz piezoelectric crystal sensor for testing liquor products. The new method was applied in the new EBVD equipment which we designed. A real-time system monitoring the polymer coating＇s thickness was designed for the new EBVD equipment according to the quartz crystal microbalance（QCM） principle, playing an important role in preparing stable and uniform PTFE polymer coatings of the same thickness. 30 pieces of PTFE polymer coatings on the surface of the quartz crystal basis were prepared with the PTFE polymer ultrafine powder（purity ≥ 99.99%）as the starting material. We obtained 30 pieces of new PTFE polymer sensors. By using scanning electron microscopy（SEM）, the structure of the PTFE polymer coating＇s column clusters was studied. One sample from the 30 pieces of new PTFE polymer sensors was analysed by SEM in four scales, i.e., 400×, 1000×, 10000×, and 25000×. It was shown that under the condition of high bias voltage and low bias current, uniformly PTFE polymer coating could be achieved, which indicates that the new EBVD equipment is suitable for mass production of stable and uniform polymer coating.
基金Project supported by the Sichuan Science and Technology Program, China (Grant No. 2019YJ0188)the National Natural Science Foundation of China (Grant Nos. 61671116 and 11905026).
文摘Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.
文摘By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has the lowest turn-on field, the highest current density, and the highest emission efficiency due to its good contact with the substrate and relatively weak field shielding effect. Experiments show that the morphology and orientation of one-dimensional ZnO nanomaterials have a great influence on its conduction field and emission current density, and the nanoarrays also contribute to electron emission. The research results have a certain reference value for the application of ZnO nanorod arrays as cathode materials for field emission devices.
