Numerical Simulation And Experiment Investigations On Low Frequency Oscillations Of Stationary Plasma Thruste

Stationary plasma thruster (SPT) is a kind of advanced electric propulsion concept. Because of its high specific impulse, high efficiency, small bulk and low weight, it is being widely used in tasks such as pose control, orbit correct, position retain, and so on. The low frequency oscillation (LFO) of discharge current is one of the characteristics of SPT. The peak-to-peak amplitude of LFO can reach 100% of average value of the current. It has notable effect on the power source of the thruster and shortens the life of the wall of the channel.Based on one-dimensional quasi-neutrality hydrodynamic model of SPT, programs were written in Simulink. Correct the mistake in the setting of boundary conditions in the work of Wu Xiaoling, and the dimensionless deal was made to enhance the stability and accuracy of computation. The result of simulation well agreed with the experiment.On the cyclic LFO, the time-variation of the main physical parameters at the exit and along the channel are described and discussed. The concept of"atom front"is defined to describe the"breath movement"of the propellant. The analyzing method of predator model is used to analyze the relation of the atom and ion densities. It is figured out that the positive feedback in the discharge process plays a important role in the LFO.It is found that the altering of pre-discharge proportion has important effect on the frequency, amplitude and waveform of LFO. The result of simulation shows that when the pre-discharge proportion increases, the frequency of LFO tends to be higher and the waveform changes from cyclic oscillation to chaotic oscillation. And the amplitude is significantly smaller. This means the increase of pre-discharge proportion can decrease the amplitude of LFO.On the cyclic oscillation, paroxysmal chaotic oscillation and chaotic oscillation, the initial value sensitivity analysis, autocorrelation analysis and phase chart analysis are made. Based on the result of power spectrum analysis, it is pointed out that the spectrum broadening caused the decrease of amplitude of chaotic oscillations.In the experiment on Aton-SPT, the pre-discharge is found in the buffer...