System Design And Performance Optimization Of Micro-pulsed Plasma Thruster

Micro-pulsed Plasma Thruster(μPPT),as a member of electric thrusters,is a kind of Pulsed Plasma Thruster(PPT),which system mass less than 1kg and discharge energy less than 5J.Because of the low power consumption,simple structure,light weight,small thrust,high specific impulse,long service life,high reliability and high control precision,μPPT has become the suitable thruster for micro satellite to perform orbit maneuver,attitude control,resistance compensation,formation flying et al.propulsion missions.In order to optimize the design,quality,size and performance of the μPPT,the theoretical analysis,numerical simulation and experimental research methods were employed.The experimental prototype of μPPT was proposed,and then its working process was investigated.Based on the ablation process of Teflon during the working process of μPPT,a one-dimensional propellant ablation model was established taking into account energy conversion,phase transition and ablation surface movement.Based on the working process of the μPPT,at the same time considering the ablation process of propellant and the size of geometric,a novel one-dimensional electromechanical model was developed.Then the reliability of the model was validated by Michele Coletti’s μPPT.Moreover,the influence of discharging and structural parameters on the performance of μPPT was numerical investigated.Two small volume,light weight and adjustable plate spacing experimental prototype of μPPT was designed and developed.Then the types and parameters of the components of μPPT were selected,and the plates,plume protection devices,propellant and supply devices were designed.Finally,after completing the integrated coupling design,the mass of the experimental prototype is less than 150 g,the size of the experimental prototype is 35mm*40mm* 50 mm.A high reliability,high control precision,long service life and flexible ignition system,as well as a strong anti-interference ability,small ripple coefficient and high charging efficiency charging power source were designed and developed.According to the ignition characteristic of μPPT,a light weight,small volume and long life interstitial semi conductor spark plug was designed and developed.Finally,the total mass of the power processing unit is less than 200 g.Moreover,one million ignitions of the whole system in the air was completed.The micro impulse measurement,single pulse laser ablation measurement,discharging parameters measurement and electromagnetic interference test of μPPT were carried out.Then the influence of capacitance,discharge voltage and electrode distance on the performance of μPPT were investigated,and electromagnetic interference test was conducted.The researching results show that the increasing of capacitance and discharge voltage can improve the impulse bit,specific impulse and efficiency of μPPT when the thruster discharge level is less than 5 J.However,the increasing of discharge voltage would enhance the voltage oscillation which not only reduces the life of capacitance but also may cause the "secondary ablation" of the propellant.Meanwhile,the work of μPPT could not disturb the transmission signal of the satellite obviously,according to the results of electromagnetic interference test.