Experimental And Theoretical Research For Pulsed Plasma Thruster

As the earliest electrical propulsion technology applied to spacecraft,pulsed plasma thruster(PPT),which could afford the requirements of light weight and low power for micro satellite,was expected to become the first electric propulsion system for micro satellite.PPT not only allowed the micro satellite to complete the function of formation flying,but also significantly extended the life of micro satellite to improve its performance.In this paper a parallel-plate breech-fed PPT was researched.To improve the performances of PPT,experiment,simulation and technical research were carried out by this work.On one hand,the basic experimental system and performance test system were set up for conducting micro-thrust,ablation mass and electrical parameter measurements.Firstly the counterweight was used to adjust the natural period of micro-thrust test system.And the measurement of impulse bit at the level of hundred ?Ns was achieved by using the electromagnetic force to calibrate the system.Secondly the correction method,which made the measurement more accurate,was put out in ablation mass test.Finally the electrical parameters were measured by traditional method.On the other hand,the test method of PPT emission spectrum based on pseudo synchronous method was proposed.And the test system was developed to realize the high resolution of time and space.The spectrum test scheme was designed to satisfy the requirement of pseudo synchronous method for spatial location and time base.By means of spectrum and electric parameter test,the method of reducing the occurrence of the phenomenon of unstable discharge was found.Due to the randomness in the ignition position of spark plugs,it was found from the result of spectrum test that the main discharge part of the PPT discharge voltage curve had good repeatability,but the repeatability of the spectral data was worse.The temporal and spatial distribution of emission spectra of different ionic components were obtained.The grayscale conversion code of spectral signal was written to reflect the process of plasma movement intuitively.In the simulation part,firstly,this paper analysed the radiation mechanism of PPT working process which was an important heat transfer mechanism.Under the premising of taking some reasonable assumptions,the PPT components under different working conditions were calculated with the temperature and pressure as input parameters.On the basis of this,the emission coefficient of linear radiation,recombination radiation and the bremsstrahlung were calculated and their influence law were found.Line radiation was the most important radiation mechanism in the PPT discharge.At the same time,the radiation heat transfer and ablation model was built based on the line radiation heat source.And the working process of PPT was simulated by one-dimensional unsteady MHD with the structure and electrical parameters of the experimental prototype as input parameters.In the part of improving technology,mainly for the defect of late ablation and plume contamination of traditional solid PPT,water propellant PPT were studied.According to the characteristics of WP-PPT ablation,ablation model was established considering two special conditions of lacking ablation energy and ablation mass.And the WP-PPT of the University of Tokyo which had more complete data was simulated.It was found that it taken about 32% of propellant in discharge.Thus the efficient supply system was of great importance to improve the performance of WP-PPT.A new liquid supply system was developed and experiment project was designed to meet the demand of WP-PPT for the supply of liquid propellant.