Design And Experimental Study On The Miniature DC Ion Thruster

In recent years,there has been an increasing demand for low-orbit space exploration missions and earth observation missions.Small satellite technology has developed rapidly.The small satellite platform requires the propulsion system to be of light weight,small size,high specific impulse,and high efficiency.Existing chemical propulsion cannot meet the needs of small satellites work well,and the application of electric propulsion has become a trend.The miniature ion thruster has the advantages of micro-thrust,high efficiency,high specific impulse,controllable thrust,etc.It has a good application prospect and research value.In this paper,a miniature ion thruster with a diameter of 20 mm is designed and its discharge characteristics and working performance are studied.Firstly,the working principle of the ion thruster is introduced.The principle of discharge and the principle of beam extraction are analyzed.The common magnetic field configurations of several ion thrusters are introduced and analyzed.The 2-pole magnetic field is selected as the 20-mm diameter miniature ion thruster.Magnetic field configuration.The magnetic field of the thruster is simulated to analyze the magnetic field characteristics of the discharge chamber.The results showed that the magnetic field intensity on the axis of the discharge chamber showed a downward trend before the position of 15 mm from the bottom of the discharge chamber,and the magnetic field intensity showed an upward trend thereafter.From the design requirements of the thruster and the problems found in the experiment,the structure of the original pyrogen-free hollow cathode is improved.The geometric parameters of each part of the thruster were determined,and the structure of each part of the miniature ion thruster was designed,including the design of the anode structure and the magnetic permeability structure and the design of the ion optical system.A complete prototype of the miniature ion thruster was designed..Second,by simulating characteristic parameters such as plasma density,electron density,plasma potential,and electron energy in the discharge chamber,the main cathode position,working fluid flow rate,anode voltage,magnetic field configuration,and discharge circuit were changed to study the spatial variation of plasma characteristics.law.The simulation results show that the main area of the thruster discharge is in front of the main cathode.The main cathode position determines the position of the main discharge area and has a certain influence on the plasma characteristics upstream of the screen grid.The main cathode position and the magnetic field configuration determine the plasma.The spatial distribution of parameters such as density and plasma potential;the magnetic tip has a certain influence on the spatial distribution of electron energy;the discharge parameter does not change the spatial distribution of the plasma parameters;the spatial distribution of plasma potential and electron energy is due to the screen voltage The change has changed significantly.Thirdly,select several positions in the discharge chamber,use Langmuir single probe to diagnose the plasma at each position,change the main cathode position,the flow rate of the working fluid,the anode voltage and the discharge circuit,and measure the plasma in the discharge chamber under different working conditions.Spatial distribution of body characteristic parameters.The measurement results show that the plasma density increases with the increase of the discharge current;the increase of the flow rate of the working fluid can not increase the plasma density,but the electron temperature can be reduced;there is a corresponding discharge parameter of the plasma potential so that it can reach the minimum Value;When the main cathode is located close to the screen,the discharge will be enhanced;anode-screen grid discharge circuit will play a significant inhibitory effect.Finally,the performance of a miniature DC ion thruster was tested by experiments.Changing the parameters such as the flow rate of the working fluid,the anode current,and the screen voltage,the performance parameters such as thrust force,specific impulse,working efficiency,and discharge efficiency of the thruster are obtained.The results show that there is a linear relationship between thruster performance parameters and operating parameters;the influence of beam extraction on the power and efficiency of thruster is obvious;when the operating parameter exceeds a certain critical value,the working mode of the thruster will abruptly change;The current to the cathode of the summer can increase the voltage that can be applied to the screen to some extent.