Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion ...Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics(CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic(EHD) equations and the volume of fluid(VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared.The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration.Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases.Moreover, some unstable behavior is observed during the cone formation process.展开更多
In this paper, the immersed finite element particle-in-cell Monte Carlo collision(IFE-PIC-MCC)model is used to study the cause of the grid erosion in field emission electric propulsion(FEEP).The simulation results sho...In this paper, the immersed finite element particle-in-cell Monte Carlo collision(IFE-PIC-MCC)model is used to study the cause of the grid erosion in field emission electric propulsion(FEEP).The simulation results show that charge exchange(CEX) ions are the main cause of the grid erosion, while beam ions basically do not impinge on the grid. The CEX ions are mainly generated near the grid. Some of these CEX ions return to the upper surface, lower surface and notch side surface of the grid. The impact angle of CEX ions returning to the upper and side surfaces is large, but their energy is low, while the impact angle of CEX ions returning to the lower surface is small, but their energy is high. The above characteristics lead to the similar erosion rates of these three surfaces.展开更多
基金supported by National Natural Science Foundation of China(No.52075334)。
文摘Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics(CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic(EHD) equations and the volume of fluid(VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared.The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration.Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases.Moreover, some unstable behavior is observed during the cone formation process.
基金supported by National Natural Science Foundation of China (No. 11675040)the Fundamental Research Funds for the Central Universities of China (Nos. DUT20LAB203 and DUT21GJ206)+1 种基金the Key Research and Development Project of Liaoning Province (No. 2020JH2/ 10500003)the Open Fund for Tianqin Project Key Laboratory of Ministry of Education (in preparation) (TQRF2020-2.5)。
文摘In this paper, the immersed finite element particle-in-cell Monte Carlo collision(IFE-PIC-MCC)model is used to study the cause of the grid erosion in field emission electric propulsion(FEEP).The simulation results show that charge exchange(CEX) ions are the main cause of the grid erosion, while beam ions basically do not impinge on the grid. The CEX ions are mainly generated near the grid. Some of these CEX ions return to the upper surface, lower surface and notch side surface of the grid. The impact angle of CEX ions returning to the upper and side surfaces is large, but their energy is low, while the impact angle of CEX ions returning to the lower surface is small, but their energy is high. The above characteristics lead to the similar erosion rates of these three surfaces.
