Study On The Discharge Characteristics Of 10cm ECR Ion Source With Different Microwave Input Model

Electron Cyclotron Resonance Ion Thruster--ECRIT is an electrostatic ion thruster,which has the characteristics of non thermal cathode,long life and high reliability.It is widely used in spacecraft attitude control,orbit transfer,position maintenance and interstellar navigation.In this paper,the 10 cm ECR ion source is taken as the research object,to study its performance improvement.Three aspects of the discharge characteristics of discharge beam,the microwave energy injection mode inside the plasma,the heating mechanism are studied.The results show that the microwave discharge mode in high electron density region and the Landau damping electron heating mechanism can improve discharge performance of ECR ion source.The main contents of this paper are as follows:First,in this part,the theories about the discharge process of ECR ion source are discussed,and the transmission mode of microwave in high density plasma&high magnetic field intensity region is clarified,and the conditions of the collision-less resonance of the electrostatic waves and electrons are produced.On this basis,a linear polarization wave high density region injection ion source model is created to realize the microwave injection from the high density and high magnetic field region of the ion source.The scheme can reduce the energy loss of the microwave during the plasma transmission;A spiral wave injection ion source model was established,which realized the heating mode of the collision-less resonance between the electron and the circular polarized wave or the electrostatic wave.Second,in this part,be based on the energy distribution in ECR ion source,a mathematical model of the discharge process of 10 cm ECR ion source is established.Given the input power,the size of the structure,the transparency of the grid and the flow rate of the propellant,the mathematical model can accurately calculate the discharge loss and the propellant utilization,and can calculate the space potential,the density,the electron temperature of the plasma.Third,according to the low signal debugging principle of network analyzer,a low signal debugging system of ECR ion source network analyzer is established in this part.The low signal loss and quality factor of four kinds of ion sources with different microwave injection methods are measured or calculated.Calculation results can help to optimize the structures of linear polarization wave high density injection and the spiral wave injection ion source mode.Based on the calculation results,the maximum microwave power absorption efficiency of ion sources are achieved.Meanwhile,the magnetic field distribution of four ion sources with different microwave injection modes are measured by Gauss instrument,to locate the ECR region.Fourth,using diagnosis method and principle,the Langmuir Probe Diagnosis experiments under the low discharge state and high discharge state are carried out on the linear polarization wave high density injection and the spiral wave injection ion source respectively.The distribution rule of plasma space potential,the electron temperature,the electron density,the ion density,the electron energy distribution are given,and the characteristics of plasma in these two ion sources are analyzed.Fifthly,in this part,the experimental study on the beam extraction capacity of the linear polarization wave high density injection and the spiral wave injection ion source are carried out.The effect of the propellant flow,the microwave input power,the grid voltage on the beam extraction experiments are analyzed.Under the condition of 20W~30W microwave power input,by comparing the beam extraction ability of four different microwave injection ion sources,it is concluded that the linear polarization wave high density injection and the spiral wave injection ion source are superior,include the performance of discharge loss,propellant utilization rate,thrust and specific impulse.