Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain met...Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain method and the panicle tracing method, such an algorithm is self-consistent and accurate since the interaction between electromagnetic fields and particles is properly modeled. In the time domain aspect, the generation of multipactor can be easily visualized, which makes it possible to gain a deeper insight into the physical mechanism of this effect. In addition to the classic secondary electron emission model, the measured practical secondary electron yield is used, which increases the accuracy of the algorithm. In order to validate the method, the impedance transformer and ridge waveguide filter are studied. By analyzing the evolution of the secondaries obtained by our method, multipactor thresholds of these components are estimated, which show good agreement with the experimental results. Furthermore, the most sensitive positions where multipactor occurs are determined from the phase focusing phenomenon, which is very meaningful for multipactor analysis and design.展开更多
Secondary electron emission(SEE)of metal and dielectric materials plays a key role in multipactor discharge,which is a bottle neck problem for high-power satelliate components.Measurements of both the secondary electr...Secondary electron emission(SEE)of metal and dielectric materials plays a key role in multipactor discharge,which is a bottle neck problem for high-power satelliate components.Measurements of both the secondary electron yield(SEY)and the secondary electron energy spectrum(SES)are performed on metal samples for an accurate description of the real SEE phenomenon.In order to simplify the fitting process and improve the simulation efficiency,an improved model is proposed for the description of secondary electrons(SE)emitted from the material surface,including true,elastic,and inelastic SE.Embedding the novel SES model into the electromagnetic particle-in-cell method,the electronic resonant multipactor in microwave components is simulated successfully and hence the discharge threshold is predicted.Simulation results of the SES variation in the improved model demonstrate that the multipactor threshold is strongly dependent on SES.In addition,the mutipactor simulation results agree quite well with the experiment for the practical microwave component,while the numerical model of SEY and SES fits well with the sample data taken from the microwave component.展开更多
In order to understand the physical mechanism of multipactor discharge on dielectric window surface under high power microwave （HPM） excitation in vacuum, an electron movement simulation model based on the particle-...In order to understand the physical mechanism of multipactor discharge on dielectric window surface under high power microwave （HPM） excitation in vacuum, an electron movement simulation model based on the particle-in-cell （PIC） Monte Carlo （MC） is built in this paper. The influences of microwave electromagnetic field and electrostatic field from dielectric surface charging are simultaneously considered in this model. During the simulation, the emission velocity and angle distribution of secondary electrons from the dielectric surface are taken into account. The movement trajectories of electron clusters under complex field excitation are obtained. The influences of emergence angle and microwave electromagnetic parameters on the electron movement are analyzed. It is found that the emergence angle of electrons from the surface has significant effect on its movement, and both the impact energy and return time of electrons oscillate periodically with the phase of microwave field. The number of secondary electrons and induced electrostatic field from multipactoring are also investigated. The results reveal that both values oscillate periodically at twice the microwave frequency, which is due to the electron impact energy oscillating with microwave period. A schematic diagram is proposed to explain the periodical oscillation phenomena.展开更多
Based on the finite element method(FEM)in the frequency domain and particle-in-cell approach in the time domain,a hybrid domain multipactor threshold prediction algorithm is proposed in this paper.The proposed algorit...Based on the finite element method(FEM)in the frequency domain and particle-in-cell approach in the time domain,a hybrid domain multipactor threshold prediction algorithm is proposed in this paper.The proposed algorithm has the advantages of the frequency domain and the time domain algorithms at the same time in terms of high computational accuracy and considerable computational efficiency.In addition,the compute unified device architecture(CUDA)acceleration technique also can be employed to further enhance its simulation efficiency.Numerical examples are carried out to demonstrate the effectiveness of the proposed algorithm.The results indicate that the multipactor threshold can be accurately predicted and the computational efficiency can be improved.展开更多
A hybrid mode of one- and two-surface multipactor on the grooved dielectric surface is studied in detail using both an analytical approach and two-dimensional particle-in-cell（2D PIC） simulations. When the groove wi...A hybrid mode of one- and two-surface multipactor on the grooved dielectric surface is studied in detail using both an analytical approach and two-dimensional particle-in-cell（2D PIC） simulations. When the groove width L 〈 eE_0/（4πm_ef^2）,there are one-surface multipactor and one-order two-surface multipactor on the grooved dielectric surface, and only one slope of the groove has the multipactor anytime. When L 〉 eE0/（4πme f^2）, both slopes may have the multipactors. The electron surface density of the multipactor discharge has a sharp increase at the length L = eE_0/（4πm_ef^2）.展开更多
The theoretical analysis and actual performance of the single-surface multipactor discharge model in the presence of a magnetic field are conducted through simulations. The effects of the magnitude of the insulated ma...The theoretical analysis and actual performance of the single-surface multipactor discharge model in the presence of a magnetic field are conducted through simulations. The effects of the magnitude of the insulated magnetic field and the oblique incidence of electrons on the multipactor are analysed. The results show that the multipactor susceptibility region shrinks gradually as the magnetic field increases when the electron cyclotron frequency is close to the RF frequency of the electric field. As a result, the evolution of the multipactor discharge will reach saturation earlier and become saturated at a higher level than the case when the magnetic field is absent, but the change of evolution and saturation as the insulated magnetic field increases is not obvious.展开更多
Multipactor and low-pressure gas discharges have a negative impact on the performance and security of microwave components in space.In this manuscript,a 2-dimensional parallel flat plate structural model was designed ...Multipactor and low-pressure gas discharges have a negative impact on the performance and security of microwave components in space.In this manuscript,a 2-dimensional parallel flat plate structural model was designed to simulate the breakdown of multipactor to low-pressure gas discharges.The breakdown levels in the pressure range of 0.1 to 100 torr were verified under the conditions of the Ag material,4-mm gap,2.6-GHz frequency,and air as the background gas.Random secondary electron emission and gas molecule collision processes are incorporated,and the effect of their transition section is studied using trajectory tracking and Monte Carlo methods.A comparison of the model to the available experimental data demonstrates the model’s accuracy.On this basis,the variation of gas adsorption in relation to the surface secondary electron yields was considered,and the effect of the gas adsorption issues on breakdown level was calculated by means of numerical simulations based on some assumptions.The calculation reveals that in a finite volume of space,smaller desorption volumes cause negligible pressure changes,but the secondary electron emission capacity of the material decreases,which,in turn,leads to a flat or rising breakdown level.On the contrary,the larger the desorption volume,the more the gas is collisionally ionized and the breakdown level decreases.展开更多
基金Project supported by the National Key Laboratory Foundation,China(Grant No.9140C530103110C5301)
文摘Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain method and the panicle tracing method, such an algorithm is self-consistent and accurate since the interaction between electromagnetic fields and particles is properly modeled. In the time domain aspect, the generation of multipactor can be easily visualized, which makes it possible to gain a deeper insight into the physical mechanism of this effect. In addition to the classic secondary electron emission model, the measured practical secondary electron yield is used, which increases the accuracy of the algorithm. In order to validate the method, the impedance transformer and ridge waveguide filter are studied. By analyzing the evolution of the secondaries obtained by our method, multipactor thresholds of these components are estimated, which show good agreement with the experimental results. Furthermore, the most sensitive positions where multipactor occurs are determined from the phase focusing phenomenon, which is very meaningful for multipactor analysis and design.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1537211,11705142,and 11675278)the National Key Laboratory Foundation,China(Grant No.9140C530101150C53011)
文摘Secondary electron emission(SEE)of metal and dielectric materials plays a key role in multipactor discharge,which is a bottle neck problem for high-power satelliate components.Measurements of both the secondary electron yield(SEY)and the secondary electron energy spectrum(SES)are performed on metal samples for an accurate description of the real SEE phenomenon.In order to simplify the fitting process and improve the simulation efficiency,an improved model is proposed for the description of secondary electrons(SE)emitted from the material surface,including true,elastic,and inelastic SE.Embedding the novel SES model into the electromagnetic particle-in-cell method,the electronic resonant multipactor in microwave components is simulated successfully and hence the discharge threshold is predicted.Simulation results of the SES variation in the improved model demonstrate that the multipactor threshold is strongly dependent on SES.In addition,the mutipactor simulation results agree quite well with the experiment for the practical microwave component,while the numerical model of SEY and SES fits well with the sample data taken from the microwave component.
基金supported in part by the National High Technology Research and Development Program of China
文摘In order to understand the physical mechanism of multipactor discharge on dielectric window surface under high power microwave （HPM） excitation in vacuum, an electron movement simulation model based on the particle-in-cell （PIC） Monte Carlo （MC） is built in this paper. The influences of microwave electromagnetic field and electrostatic field from dielectric surface charging are simultaneously considered in this model. During the simulation, the emission velocity and angle distribution of secondary electrons from the dielectric surface are taken into account. The movement trajectories of electron clusters under complex field excitation are obtained. The influences of emergence angle and microwave electromagnetic parameters on the electron movement are analyzed. It is found that the emergence angle of electrons from the surface has significant effect on its movement, and both the impact energy and return time of electrons oscillate periodically with the phase of microwave field. The number of secondary electrons and induced electrostatic field from multipactoring are also investigated. The results reveal that both values oscillate periodically at twice the microwave frequency, which is due to the electron impact energy oscillating with microwave period. A schematic diagram is proposed to explain the periodical oscillation phenomena.
基金This work was supported by the National Natural Science Foundation of China(61571022,61971022)the National Key laboratory Foundation(HTKJ2019KI504013,61424020305).
文摘Based on the finite element method(FEM)in the frequency domain and particle-in-cell approach in the time domain,a hybrid domain multipactor threshold prediction algorithm is proposed in this paper.The proposed algorithm has the advantages of the frequency domain and the time domain algorithms at the same time in terms of high computational accuracy and considerable computational efficiency.In addition,the compute unified device architecture(CUDA)acceleration technique also can be employed to further enhance its simulation efficiency.Numerical examples are carried out to demonstrate the effectiveness of the proposed algorithm.The results indicate that the multipactor threshold can be accurately predicted and the computational efficiency can be improved.
基金Project supported by the National Natural Science Foundation of China(Grant No.61231003)
文摘A hybrid mode of one- and two-surface multipactor on the grooved dielectric surface is studied in detail using both an analytical approach and two-dimensional particle-in-cell（2D PIC） simulations. When the groove width L 〈 eE_0/（4πm_ef^2）,there are one-surface multipactor and one-order two-surface multipactor on the grooved dielectric surface, and only one slope of the groove has the multipactor anytime. When L 〉 eE0/（4πme f^2）, both slopes may have the multipactors. The electron surface density of the multipactor discharge has a sharp increase at the length L = eE_0/（4πm_ef^2）.
基金Project supported by the High Power Radiation Key Laboratory Foundation of the National High Technology Research and Development Program of China (Grant No. 20050601)
文摘The theoretical analysis and actual performance of the single-surface multipactor discharge model in the presence of a magnetic field are conducted through simulations. The effects of the magnitude of the insulated magnetic field and the oblique incidence of electrons on the multipactor are analysed. The results show that the multipactor susceptibility region shrinks gradually as the magnetic field increases when the electron cyclotron frequency is close to the RF frequency of the electric field. As a result, the evolution of the multipactor discharge will reach saturation earlier and become saturated at a higher level than the case when the magnetic field is absent, but the change of evolution and saturation as the insulated magnetic field increases is not obvious.
基金substantially supported by the National Natural Science Foundation of China(grant nos.61901361 and 51827809).
文摘Multipactor and low-pressure gas discharges have a negative impact on the performance and security of microwave components in space.In this manuscript,a 2-dimensional parallel flat plate structural model was designed to simulate the breakdown of multipactor to low-pressure gas discharges.The breakdown levels in the pressure range of 0.1 to 100 torr were verified under the conditions of the Ag material,4-mm gap,2.6-GHz frequency,and air as the background gas.Random secondary electron emission and gas molecule collision processes are incorporated,and the effect of their transition section is studied using trajectory tracking and Monte Carlo methods.A comparison of the model to the available experimental data demonstrates the model’s accuracy.On this basis,the variation of gas adsorption in relation to the surface secondary electron yields was considered,and the effect of the gas adsorption issues on breakdown level was calculated by means of numerical simulations based on some assumptions.The calculation reveals that in a finite volume of space,smaller desorption volumes cause negligible pressure changes,but the secondary electron emission capacity of the material decreases,which,in turn,leads to a flat or rising breakdown level.On the contrary,the larger the desorption volume,the more the gas is collisionally ionized and the breakdown level decreases.
