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 thr...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 spacecraft.For 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 characteristics.The 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%,respectively.The 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 one.The 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 cross-sections.The 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.展开更多
As a kind of special acoustic field, the helical wavefront of an acoustic vortex(AV) beam is demonstrated to have a pressure zero with phase singularity at the center in the transverse plane. The orbital angular mom...As a kind of special acoustic field, the helical wavefront of an acoustic vortex(AV) beam is demonstrated to have a pressure zero with phase singularity at the center in the transverse plane. The orbital angular momentum of AVs can be applied to the field of particle manipulation, which attracts more and more attention in acoustic researches. In this paper,by using the simplified circular array of point sources, dual coaxial AV beams are excited by the even-and odd-numbered sources with the topological charges of l_E and l_O based on the phase-coded approach, and the composite acoustic field with an on-axis center-AV and multiple off-axis sub-AVs can be generated by the superimposition of the AV beams for|l_E| ≠ |l_O|. The generation of edge phase dislocation is theoretically derived and numerically analyzed for l_E=-l_O. The numbers and the topological charges as well as the locations of the center-AV and sub-AVs are demonstrated, which are proved to be determined by the topological charges of the coaxial AV beams. The proposed approach breaks through the limit of only one on-axis AV with a single topological charge along the beam axis, and also provides the feasibility of off-axis particle trapping with multiple AVs in object manipulation.展开更多
The DLBSW( dual laser-beam bilateral synchronous welding) technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanica...The DLBSW( dual laser-beam bilateral synchronous welding) technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanical behavior of this process, it is necessary to establish a reasonable heat source model. Two different surface-body combination heat source models are adopted in this paper. Both models use the Gaussian surface heat source model and one is combined with the cone body heat source model and the other is combined with Gaussian rotator body heat source model. The simulation results of these two different models are investigated. And the temperature field results of DLBSW process for T-joint with two different heat sources are discussed. It is indicated that the combination heat source model is effective to simulate the DLBSW process and the current study is useful for more profound research in this field.展开更多
Free electron lasers provide high-power and ultrashort pulses with extreme brightness. In order to improve a facility's capabilities and explore the possibility of performing high-resolution time-resolved experime...Free electron lasers provide high-power and ultrashort pulses with extreme brightness. In order to improve a facility's capabilities and explore the possibility of performing high-resolution time-resolved experiments, a beam arrival time resolution under 100 fs is required. In this article, a novel beam arrival time monitor(BAM)equipped with two cavities has been designed and a beam flight time measurement scheme based on the BAM prototype has been proposed to estimate phase jitter in the signal measurement system. The two BAM cavities work at different frequencies and the frequency difference is designed to be 35 MHz. Therefore, a self-mixing intermediate frequency signal can be generated using the two cavities. The measured beam flight time shows a temporal deviation of 37 fs(rms).展开更多
In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. Th...In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. The XRD and TEM results show that the deposited films have an amorphous structure. In the XPS result, we find N 1s spectra consist of one symmetric single peak at 397.8 eV, indicating that the nitrogen atoms are mainly bonded to silicon. It is in agreement to the result of FTIR. In SiOxNy films, an intense single PL peak at 590 nm is observed. Furthermore, with the increase of the N content in the SiOxNy films, the intensity of the PL peak at 590 nm increases a lot. The PL peak of 590 nm is suggested to originate from N-related defects.展开更多
This paper presents the single element dual band switched beam textile antenna.The antenna can operate at frequencies of 0.7 and 2.6 GHz using for 5G wireless communication applications.Textile fabric is considered to...This paper presents the single element dual band switched beam textile antenna.The antenna can operate at frequencies of 0.7 and 2.6 GHz using for 5G wireless communication applications.Textile fabric is considered to be used for substrate layer at the parts of a microstrip antenna for wireless body area network.The beam pattern of antenna can be switched into two directions by changing the position of shorted-circuit points at each edge of antenna.The main beam direction is 45°/225°when corner A is shorted while it steers at 135°/315°when corner B is shorted circuit.The advantage of the proposed antenna is the decrease of the problems like interference,light weight,flexibility and ability to switch beam easily.In addition,the results of the fabricated antenna are compared with the simulated ones.Moreover,the antenna is bent with curvature radius of 6 mm in forward direction.The effects of the bent antenna are studied.The results can confirm that radiation patterns of the bending antenna can be pointed into two directions when changing the positions of shorted circuit.Therefore,the proposed antenna can switch beam patterns,it is flexible,and it can operate at dual-band frequency on textile.展开更多
Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the i...Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the increase in substrate temperature (TS). The magnetic properties of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).展开更多
In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduce...In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduced for welding.T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser welding.The morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap joints.The microstructure characteristics of the weld zone were observed and compared by optical microscope.The results show that the addition of laser beam swing can eliminate the internal pores of the weld.With the increase of the swing width,the weld depth decreases,and the weld width increases first and then decreases.The influence of welding speed on the weld cross section morphology is similar to that of swing width.With the increase of welding speed,the weld width increases first and then decreases,while the weld depth decreases all the time.This is because that the red laser is used as the main heat source to melt the base metals,with the increase of red laser power,the weld depth increases.As an auxiliary laser source,blue laser reduces the total energy consumption,consequently,the effective heat input increases and the spatter is restrained effectively.As a result,the increase of red laser power has an enhancement effect on the weld width and weld depth.When the swing width is 1.2 mm,the red laser power is 550 W,the blue laser power is 500 W,and the welding speed is 35 mm/s,the weld forming is the best.The lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue laser.The effect rules of laser beam swing on the weld formation were obtained,which improved the quality of the joints.展开更多
基金the Key Laboratory Funds for Science and Technology on Vacuum Technology and Physics Laboratory(No.HTKJ2022KL510002)the Military Test Instruments Program(No.2006ZCTF0054)。
文摘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 spacecraft.For 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 characteristics.The 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%,respectively.The 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 one.The 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 cross-sections.The 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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474166 and 11604156)the Science and Technology Cooperation Projects of People’s Republic of China–Romania(Grant No.42-23)+2 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161013)the Postdoctoral Science Foundation of China(Grant No.2016M591874)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘As a kind of special acoustic field, the helical wavefront of an acoustic vortex(AV) beam is demonstrated to have a pressure zero with phase singularity at the center in the transverse plane. The orbital angular momentum of AVs can be applied to the field of particle manipulation, which attracts more and more attention in acoustic researches. In this paper,by using the simplified circular array of point sources, dual coaxial AV beams are excited by the even-and odd-numbered sources with the topological charges of l_E and l_O based on the phase-coded approach, and the composite acoustic field with an on-axis center-AV and multiple off-axis sub-AVs can be generated by the superimposition of the AV beams for|l_E| ≠ |l_O|. The generation of edge phase dislocation is theoretically derived and numerically analyzed for l_E=-l_O. The numbers and the topological charges as well as the locations of the center-AV and sub-AVs are demonstrated, which are proved to be determined by the topological charges of the coaxial AV beams. The proposed approach breaks through the limit of only one on-axis AV with a single topological charge along the beam axis, and also provides the feasibility of off-axis particle trapping with multiple AVs in object manipulation.
基金The research is sponsored by the Shanghai STCSM Project of the Postdoctoral Science Research Assistant Plan (10R21421200), the National Natural Science Foundation of China (50904038) and the China Postdoctoral Science Foundation (20100470064).
文摘The DLBSW( dual laser-beam bilateral synchronous welding) technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanical behavior of this process, it is necessary to establish a reasonable heat source model. Two different surface-body combination heat source models are adopted in this paper. Both models use the Gaussian surface heat source model and one is combined with the cone body heat source model and the other is combined with Gaussian rotator body heat source model. The simulation results of these two different models are investigated. And the temperature field results of DLBSW process for T-joint with two different heat sources are discussed. It is indicated that the combination heat source model is effective to simulate the DLBSW process and the current study is useful for more profound research in this field.
基金supported by the National Natural Science Foundation of China(No.11575282)
文摘Free electron lasers provide high-power and ultrashort pulses with extreme brightness. In order to improve a facility's capabilities and explore the possibility of performing high-resolution time-resolved experiments, a beam arrival time resolution under 100 fs is required. In this article, a novel beam arrival time monitor(BAM)equipped with two cavities has been designed and a beam flight time measurement scheme based on the BAM prototype has been proposed to estimate phase jitter in the signal measurement system. The two BAM cavities work at different frequencies and the frequency difference is designed to be 35 MHz. Therefore, a self-mixing intermediate frequency signal can be generated using the two cavities. The measured beam flight time shows a temporal deviation of 37 fs(rms).
基金The project supported by the Nature Science Foundation of University of Jiangsu Province(No. 03KJB140116 )
文摘In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. The XRD and TEM results show that the deposited films have an amorphous structure. In the XPS result, we find N 1s spectra consist of one symmetric single peak at 397.8 eV, indicating that the nitrogen atoms are mainly bonded to silicon. It is in agreement to the result of FTIR. In SiOxNy films, an intense single PL peak at 590 nm is observed. Furthermore, with the increase of the N content in the SiOxNy films, the intensity of the PL peak at 590 nm increases a lot. The PL peak of 590 nm is suggested to originate from N-related defects.
基金This work is funded from the Thailand Science Research and Innovation through the research grant No.036/2564,https://www.tsri.or.th/.
文摘This paper presents the single element dual band switched beam textile antenna.The antenna can operate at frequencies of 0.7 and 2.6 GHz using for 5G wireless communication applications.Textile fabric is considered to be used for substrate layer at the parts of a microstrip antenna for wireless body area network.The beam pattern of antenna can be switched into two directions by changing the position of shorted-circuit points at each edge of antenna.The main beam direction is 45°/225°when corner A is shorted while it steers at 135°/315°when corner B is shorted circuit.The advantage of the proposed antenna is the decrease of the problems like interference,light weight,flexibility and ability to switch beam easily.In addition,the results of the fabricated antenna are compared with the simulated ones.Moreover,the antenna is bent with curvature radius of 6 mm in forward direction.The effects of the bent antenna are studied.The results can confirm that radiation patterns of the bending antenna can be pointed into two directions when changing the positions of shorted circuit.Therefore,the proposed antenna can switch beam patterns,it is flexible,and it can operate at dual-band frequency on textile.
基金Jiangsu Province key laboratory of thin film with Grant No. K2021.
文摘Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the increase in substrate temperature (TS). The magnetic properties of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).
基金supported by Guangdong Science and Technology Plan Project(Grant No.20170902,No.20180902)Yangjiang Science and Technology Plan Project(Grant No.SDZX2020063)+1 种基金Shenzhen Key Projects of Innovation and Entrepreneurship Plan Technology(JSGG20210420091802007)Yunfu 2023 Science and Technology Plan Project(S2023020201).
文摘In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduced for welding.T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser welding.The morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap joints.The microstructure characteristics of the weld zone were observed and compared by optical microscope.The results show that the addition of laser beam swing can eliminate the internal pores of the weld.With the increase of the swing width,the weld depth decreases,and the weld width increases first and then decreases.The influence of welding speed on the weld cross section morphology is similar to that of swing width.With the increase of welding speed,the weld width increases first and then decreases,while the weld depth decreases all the time.This is because that the red laser is used as the main heat source to melt the base metals,with the increase of red laser power,the weld depth increases.As an auxiliary laser source,blue laser reduces the total energy consumption,consequently,the effective heat input increases and the spatter is restrained effectively.As a result,the increase of red laser power has an enhancement effect on the weld width and weld depth.When the swing width is 1.2 mm,the red laser power is 550 W,the blue laser power is 500 W,and the welding speed is 35 mm/s,the weld forming is the best.The lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue laser.The effect rules of laser beam swing on the weld formation were obtained,which improved the quality of the joints.