The processes of electric ion extraction from plasma induced by pulse lasers are simulated by particle-in-cell(PIC)method and hybrid-PIC method.A new calculation scheme named preprocessing hybrid-PIC is presented beca...The processes of electric ion extraction from plasma induced by pulse lasers are simulated by particle-in-cell(PIC)method and hybrid-PIC method.A new calculation scheme named preprocessing hybrid-PIC is presented because neither of the two methods above is omnipotent,especially under the circumstance of high initial plasma density.The new scheme provides credible results with less computational consumption than PIC method in both one-and two-dimensional simulations,except forΠ-type electrode configuration.The simulation results show that the M-type performs best in all electrode configurations in both high-density and low-density plasma conditions.展开更多
The development of space science has generated important computer codes for the simulation of the interaction between complex space structures(artificial satellites,solar panels,etc.)and the surrounding plasma.The bas...The development of space science has generated important computer codes for the simulation of the interaction between complex space structures(artificial satellites,solar panels,etc.)and the surrounding plasma.The basic equation to be solved is the Poisson equation for the electric potential around a structure.Here,we try to study analytically the shadowing effect of a spacecraft on an electrode for the electron number density and the electron temperature.We suggest that the electron temperature should be taken as a variable and not as a parameter.However,its computation involves the knowledge of the histogram of the distribution of the frequencies of the electron velocities inside the computational cells.Also,we have illustrated the possibilities of artefacts due to the design and geometry of scientific instruments for the measurement of the electron number density and the electron temperature in the ionosphere.We suggest an optimal design for an electrode and its guard ring.展开更多
In order to study the extraction and acceleration mechanism of the dual-stage grid,a three-dimensional model based on the Particle-In-Cell/Monte Carlo Collision(PIC/MCC)method is performed.Dual-stage grid ion thruster...In order to study the extraction and acceleration mechanism of the dual-stage grid,a three-dimensional model based on the Particle-In-Cell/Monte Carlo Collision(PIC/MCC)method is performed.Dual-stage grid ion thruster is a new type of electrostatic ion thruster,which can break through the limitations of traditional gridded ion thrusters,and greatly improve the specific impulse.The high performance also makes the grid sensitive to operating parameters.In this paper,the influence of grid parameters on xenon ion thruster’s performance in a wide range is systematically simulated,and the optimal operating condition is given.Both the over-focusing of the plume,and the transparency of the screen grid are improved,and the grid corrosion is reduced through simulation optimization.The specific impulse under the given working conditions is 9877.24 s and the thrust is 7.28 mN.Based on the simulation optimization,the limitation of the dual-stage grid is discussed.The grid performs well under high voltage conditions(>3000 V)but not well under low voltage conditions(<2000 V).Finally,since argon is cheaper and more advantageous in future engineering applications,the plasma distribution and grid extraction ability under xenon and argon are analyzed and compared to study the flexibility of the dual-stage grid ion thruster.The simulation results show that a set of optimal parameters is only applicable to the corresponding propellant,which needs to be optimized for different propellant types.展开更多
Based on particle-in-cell simulation, we studied the motions of ions and electrons. The results have shown that electrons are bounded by a magnetic field and only a small number of electrons can pass through the whirl...Based on particle-in-cell simulation, we studied the motions of ions and electrons. The results have shown that electrons are bounded by a magnetic field and only a small number of electrons can pass through the whirler channel. The plasma becomes non-neutral when it is emitted from the whirler, and the spatial charge leads to a beam divergence, which is unfavorable for mass separation. In order to compensate the spatial charge, a cathode is designed to transmit electrons and the quasi-neutral plasma beam. Experiment results have demonstrated that the auxiliary cathode can obviously improve the compensation degree of the spatial charge.展开更多
By using PIC method ,the vertical impact on the water surface for a 2-D su- personic flat-head body with a detached shock wave is studied in this paper.Numerical results show that various complicated flow phenomena su...By using PIC method ,the vertical impact on the water surface for a 2-D su- personic flat-head body with a detached shock wave is studied in this paper.Numerical results show that various complicated flow phenomena such as the supersonic flow around the body,the air cushion effect,the propagation of the shock wave in water,the initial formation of the wa- ter-entry cavity and the pile-up of the water surface are simulated successfully.展开更多
文摘The processes of electric ion extraction from plasma induced by pulse lasers are simulated by particle-in-cell(PIC)method and hybrid-PIC method.A new calculation scheme named preprocessing hybrid-PIC is presented because neither of the two methods above is omnipotent,especially under the circumstance of high initial plasma density.The new scheme provides credible results with less computational consumption than PIC method in both one-and two-dimensional simulations,except forΠ-type electrode configuration.The simulation results show that the M-type performs best in all electrode configurations in both high-density and low-density plasma conditions.
文摘The development of space science has generated important computer codes for the simulation of the interaction between complex space structures(artificial satellites,solar panels,etc.)and the surrounding plasma.The basic equation to be solved is the Poisson equation for the electric potential around a structure.Here,we try to study analytically the shadowing effect of a spacecraft on an electrode for the electron number density and the electron temperature.We suggest that the electron temperature should be taken as a variable and not as a parameter.However,its computation involves the knowledge of the histogram of the distribution of the frequencies of the electron velocities inside the computational cells.Also,we have illustrated the possibilities of artefacts due to the design and geometry of scientific instruments for the measurement of the electron number density and the electron temperature in the ionosphere.We suggest an optimal design for an electrode and its guard ring.
基金co-supported by the National Key R & D Program for Intergovernmental International Scientific and Technological Innovation Cooperation,China(No. 2021YFE0116000)the National Natural Science Foundation of China (Nos. 12175032, 12102082 and 12275044),the National Natural Science Foundation of China+5 种基金the Belarusian Republican Foundation for Fundamental Research (No. 12211530449)the Fundamental Research Funds for the Central Universities of China (No. DUT22QN232)the S&T Program of Hebei, China (Nos. YCYZ202201 and 216Z1901G)the S&T Innovation Program of Hebei, China (Nos. SJMYF2022X18 and SJMYF2022X06)the Science and Technology Project of Hebei Education Department, China (No. ZC2023144)S&T Program of Langfang, China (No. 2022011039)
文摘In order to study the extraction and acceleration mechanism of the dual-stage grid,a three-dimensional model based on the Particle-In-Cell/Monte Carlo Collision(PIC/MCC)method is performed.Dual-stage grid ion thruster is a new type of electrostatic ion thruster,which can break through the limitations of traditional gridded ion thrusters,and greatly improve the specific impulse.The high performance also makes the grid sensitive to operating parameters.In this paper,the influence of grid parameters on xenon ion thruster’s performance in a wide range is systematically simulated,and the optimal operating condition is given.Both the over-focusing of the plume,and the transparency of the screen grid are improved,and the grid corrosion is reduced through simulation optimization.The specific impulse under the given working conditions is 9877.24 s and the thrust is 7.28 mN.Based on the simulation optimization,the limitation of the dual-stage grid is discussed.The grid performs well under high voltage conditions(>3000 V)but not well under low voltage conditions(<2000 V).Finally,since argon is cheaper and more advantageous in future engineering applications,the plasma distribution and grid extraction ability under xenon and argon are analyzed and compared to study the flexibility of the dual-stage grid ion thruster.The simulation results show that a set of optimal parameters is only applicable to the corresponding propellant,which needs to be optimized for different propellant types.
基金supported by National Natural Science Foundation of China(No.51177020)
文摘Based on particle-in-cell simulation, we studied the motions of ions and electrons. The results have shown that electrons are bounded by a magnetic field and only a small number of electrons can pass through the whirler channel. The plasma becomes non-neutral when it is emitted from the whirler, and the spatial charge leads to a beam divergence, which is unfavorable for mass separation. In order to compensate the spatial charge, a cathode is designed to transmit electrons and the quasi-neutral plasma beam. Experiment results have demonstrated that the auxiliary cathode can obviously improve the compensation degree of the spatial charge.
文摘By using PIC method ,the vertical impact on the water surface for a 2-D su- personic flat-head body with a detached shock wave is studied in this paper.Numerical results show that various complicated flow phenomena such as the supersonic flow around the body,the air cushion effect,the propagation of the shock wave in water,the initial formation of the wa- ter-entry cavity and the pile-up of the water surface are simulated successfully.
