Design And Experimental Research Of Micro-newton Cusped Field Thruster

With the development of space science,a new generation of space observation missions impose strong requirements on low-disturbance environments.Gravitational Waves detection,New Gravitational Observatory mission and high precision space telescope missions require Attitude and Orbit Control System(AOCS)with low thrust,low noise and high precision thrust vectors.Cusped field thruster becomes a candidate thruster with the advantages of relatively low complexity,strong robustness and long potential lifetime.In order to overcome the efficiency reduction,instability of performance and specific impulse limitation during the downscaling of cusped field thruster,the author tries to put forward a design method to down-scale the thruster to the μN range through a series of simulations and experimental investigations.Firstly,several scaling laws are put forward in views of the typical characteristics of cusped field thruster.Corresponding parameters are selected to be variable according to the main factors of thruster performance limitations.Particle-in-cell simulations with different channel diameters and lengths are carried out to find out the effects.Secondly,a series of experimental investigations are performed on the channel diameter and length.An optimized micro thrust measurement method which is based on Langmuir probe and Retarding Potential Analyzer are tested and calibrated.The effects on the thruster performance and discharge characteristics are given and the reason of performance limitations is studied.Relatively superior geometry parameters are given as a result.Thirdly,PIC simulations and experimental studies are carried out on different channel wall materials with the optimized thruster.Influence of second electron emission coefficient and other characteristics of the materials are discussed.What’s more,thrusters with different expanding-angles are experimentally studied.It is found that the expanding-angle is beneficial for the thruster on the ignition process,working space and stability.At the same time,the typical mode conversion is further studied,with the ionization and acceleration characteristics variety physically analyzed.Finally,a micro-newton cusped field thruster is designed as a result.A continuously variable thrust from 1μN to 100μN is achieved,and noise analysis based on power spectral density are given.Different electron sources are preliminarily tested in an experiment,which would give a direction for the electron source miniaturization.