Deep Dielectric Charging Characteristics And Multidimensional Optimization Design Of Spacecraft Driving Slip Rings Under High-energy Electronic Radiation

Aerospace is an important support for national strategy,playing a crucial role in fields such as national defense,communication,navigation and remote sensing.The Solar Array Drive Assembly(SADA)is a critical device in the power supply system of spacecraft.Its core component,the spacecraft drive slip ring,is the lifeline that ensures energy supply.Once a malfunction occurs,it can cause a loss of power to the spacecraft and result in mission failure.In recent years,multiple failures that occurred in orbit have attracted attention from the aerospace industry to the safety of electrical transmission in the slip ring.The causes of internal discharge in some slip rings all point to deep dielectric charging phenomena caused by high-energy electrons in space.In the future,with the application of space solar power stations and large space stations,the driving slip rings will develop towards high voltage and high power.However,space high-energy electron radiation has become a key issue restricting the development of new high-voltage and high-power slip rings.Currently,introducing the Monte Carlo particle transport simulation method into the analysis and research of deep dielectric charging effects has become a common approach.However,the existing research on the deep dielectric charging effect of driving slip rings is only limited to general exploration,and has not been optimized for the characteristics and structural features of deep dielectric charging in driving slip rings,thus suppressing electric field distortion caused by high-energy electron deposition.Therefore,it is necessary to conduct in-depth research on the deep dielectric charging characteristics of spacecraft drive slip rings under high-energy electron radiation and design multidimensional optimization schemes.Based on the interaction mechanism between high-energy charged particles and target materials,this paper uses Monte Carlo particle transport simulation software GEANT4 to simulate the energy attenuation and deposition process of high-energy electrons in materials.Based on the law of charge conservation,this paper uses finite element simulation software to simulate the the discharge process of deposited electrons.Thus,a 3-D simulation model for deep dielectric charging of spacecraft driven slip rings in the FLUMIC3 space electronic radiation environment is established.GEANT4 simulation was used to calculate the energy spectrum of high-energy electron emission and the maximum penetration depth of 5 MeV high-energy electrons in aluminum shielding.The results were compared with empirical formulas and reference literature calculations,thus proving the correctness and effectiveness of the simulation model.The 3-D deep dielectric charging simulation model of the driver slip ring constructed in this paper realizes the dynamic simulation of the 3-D distribution of internal charge,electric field and potential inside the slip ring after electronic radiation.Based on the 3-D simulation model of deep dielectric charging,this paper further studies the effects of shielding materials,shielding thickness,temperature,and insulation baffle parameters on the radiated electric field,and obtains the basic characteristics of driving slip ring deep charging.From the simulation results,it can be seen that high atomic number metal materials have better shielding effects than low atomic number materials,but they have higher photon transmission rates and are more likely to cause damage to insulating materials.When the temperature is low,the inhibition effect of increasing shielding on deep charging will weaken.Reducing the width or height of the insulating barrier can reduce the electric field distortion caused by deep dielectric charging,but it also reduces the creepage distance and increases the possibility of discharges such as surface flashover.Based on the correct establishment of the basic characteristics of deep dielectric charging of the spacecraft drive slip ring,further research was conducted on multidimensional optimized design schemes for suppressing deep dielectric charging from the perspectives of shielding,structure and material.From the simulation results,it can be seen that using locally reinforced aluminum shielding structure can improve the efficiency of high-energy electron radiation protection and provide better protection effect under limited weight.By using a composite shielding structure that combines high atomic number and low atomic number materials,deep dielectric charging can be effectively suppressed.When the material with high atomic number is located on the inner side of the driving slip ring,it is more advantageous for shielding high-energy electrons.Compared to the overall reduction of the height of the insulating baffle,the insulating baffle groove structure can not only further reduce the intensity of the radiation induced electric field,but also improve the creepage distance.The embedded grounding structure is conducive to the discharge of deposited electrons,effectively reducing the electric field distortion inside the polyimide.In addition,a random sequence adsorption algorithm was used to study the effect of glass fillers commonly used in the hot pressing process of the drive slip ring on deep dielectric charging.The results show that glass microspheres or glass fibers have higher conductivity,which can reduce the average electric field distribution in polyimide composite media.The larger the volume fraction,the more obvious the reduction effect.Under the same volume fraction,glass fibers have a greater degree of reduction.The surface of glass microspheres will form an accumulation of electric charges,resulting in an increase in the maximum local electric field strength.This maximum electric field strength is greater than the maximum value under pure polyimide electron radiation.When the distance between glass microspheres decreases,the degree of electric field distortion increases.However,when the glass microspheres are in contact with each other,the electric field value decreases instead.When the orientation of glass fiber is perpendicular to the grounding surface,it can provide a better channel for electron discharge and reduce deep charging effects.The use of 3-D glass fiber woven fabric can not only reduce the average electric field value inside polyimide,but also reduce local maximum electric field distortion.