Research On Xenon Collisional Radiative Model For Electric Propulsion Devices

Electric propulsion(EP)devices is widely used in space propulsion missions because of its long life and high specific impulse.Xenon is currently the mainstream propellant used in EP devices,since it has low ionization energy and mild chemical properties.With the increasing investment in space science missions and the vigorous development of commercial aerospace industry,a large number of new designs and new configurations of EP devices began to emerge.At the same time,as large communication satellite platforms entered the era of all-electric propulsion,higher requirements were put forward for the performance and life of existing Hall and Ion thrusters.Collisional-radiative(CR)models describe the kinetic behavior of the excited states in plasma,and can be used to diagnose plasma parameters by optical emission spectroscopy.Due to the absence of fundamental data that describe electron-impact and radiative processes of xenon ions,the current xenon CR models mainly focus on the modeling and analysis of atomic excitation state.They are not capable of describing kinetic behavior of ion excited states,which plays an important role in EP devices.In this work,electron-impact and radiative processes of Xe~+is studied using the fully-relativistic Dirac B-spline R-matrix method developed in recent years.The fundamental data for collisional and radiative processes of Xe~+are calculated.The variation of the collisional cross section with the valence electron characteristics of the excited state is summarized.A branching ratio measurement experiment of radiative processes is carried out to verify the calculation results.Based on these fundamental data,CR models describing kinetic mechanism of Xe and Xe~+species are established.The population and de-population mechanism of excited and metastable states are analyzed,as well as density distribution characteristics.The model is verified by comparing the predicted and measured density distribution of the excited states.In addition,based on the comprehensive CR model of xenon,which describes kinetic behavior of xenon atoms and ions,the principle of hyperspectral imaging diagnosis technology for electron temperature and density field is studied.In addition,an optical emission spectroscopy method for complex electron energy distribution in thrusters is studied.The physical model established in this paper is capable of not only promoting the development of emission spectrum diagnosis technology for xenon propellant EP devices,but also being applied to the analysis and diagnosis of other xenon plasma with similar physical conditions.In addition,the model could be used in analysing the emission spectra of stars.