Study On The Scaling Design Method Of Stationary Plasma Thruster

Stationary plasma thruster has been widely applied in orbit missions and space explorations since it had been successfully developed in 1970. Now, it intrigues the world wide interests in the electric propulsion field. Different orbit missions of the satellites result in different demands on the propulsion system, which requires people to design other power level and thrust level thruster. How to modeling and designing other power lever thrusters according to the existing ones is one of the most important methods to design a new thruster.Similarity criterion can be used to direct the modeling design of SPTs. But now, there is only one similarity criterion: Melikov-Morozov criterionλi on /La, which only embodies the ionization process of a thruster, and it cann't reflect other physical processes, so it is not enough to direct the scaling design of SPTs. Based on Melikov-Morozov criterion, Khayms et. al. proposed one scaling design method with a crossed electric and magnetic field when the discharge voltage is kept constant, which is much different from the experimental data, then Khayms'method cann't direct the thruster designing well. It is needed to develop the thruster scaling design method, which is starting point of my research work.Firstly, in this paper, we proposed some new similarity criterions. Based on the neutral continue equation, electron and ion momentum equation and electron energy equation, we deduced some new similarity criterions with the method of equation analyses. After comparing and analyzing these similarity criterions, we selected the prevailing criterions, and the following scaling design method is developed based on these selected criterions.Secondly, we obtain the relationship of the SPT parameters and proposed the scaling design method with the crossed electric and magnetic field. After analyzing the prevailing criterions, we determined the preconditions with constant discharge voltage. Based on these preconditions, we determined the relationship between SPT parameters and radius, and proposed the scaling design method with constant discharge voltage. Compared with Khayms'scaling design method, we proposed one agree well with the experimental data of the existing SPTs, and it can alleviate the magnetic saturation and ion sputtering for the lower power thrusters, and improve the power density and thrust density for the larger power thrusters.Thirdly, we determined the change laws of the magnetic field profile and electric magnetic field profile, and proposed the exclusive scaling design method with constant discharge voltage - basic cell outspread method, i.e. the magnetic and electric field intensity and profile, channel depth and width, and the plasma density should be kept constant, and the anode mass flow rate and cross-sectional area should be adjusted according to the power.Fourthly, we determined the matching relationship between magnetic field intensity and discharge voltage. In the lower discharge voltage range, the magnetic field and voltage satisfy the relationship of B_r∝U_d^1/2, while in the higher discharge voltage range, the magnetic field should keep constant to keep the high efficiency, which has great significance on the thruster designing with high discharge voltage. In addition, combining the basic cell outspread method, we proposed one designing method with variable discharge voltage.Lastly, according to the basic cell outspread method we proposed, we designed and manufactured P100 with the power of 1.5kW. Some experiments have been done on P100, and we have measured the thrust, discharge current, angle of plume divergence, electron temperature, ion energy distribution and magnetic and electric characteristics. The experimental data shown that the discharge current, thrust, power and efficiency are satisfied the designing values after these parameters are corrected with the degree of vacuum. What's more, the ionization and acceleration process of P100 and the prototype P70 are similar, which proves that the basic cell outspread method can be used to instruct the modeling design of Hall thrusters.