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For coupling optimization and control of performance and mission of electric propulsion (EP)，a coupling optimization method is proposed based on characteristic parameter model of EP in this paper. With the goal of maximizing the transfer rate of payload mass, the generalized rocket equation and optimal specific impulse (Isp) expressions for CP-EP combined propulsion and multimode all EP missions are deduced. Then a computing method of optimal Isp for multimode continuous EP is proposed. The effects of relevant parameters on optimal Isp are obtained based on some assumptions. The results indicate that the coupling optimization method and the formula for optimal Isp will provide theoretical guidance and generality for studying optimal Isp of multimode EP missions and coupling optimal control of EP spacecraft. [ABSTRACT FROM AUTHOR]

Now the main numerical simulation method of high efficiency multi plasma thruster (HEMPT) Is particle in cell. But this method puts higher demands on computer. Therefore, this method aims at reappearing the oscillation phenomenon in high efficiency multi-plasma thruster by building up one dimension fluid model and studying the plasma parameters distribution and the relationship between the current and plasma parameters. A one dimension fluid model was built up along two distinguishing typical electron paths in thrusters by Simulink. The simulation results show that the plasma parameters oscillation period is consistent with that of the current. The main ionization zone is between the two cusped fields. The main area where potential drops is near the channel exit. [ABSTRACT FROM AUTHOR]

An image diagnosis method based on the spectrum diagnosis was proposed to facilitate the in-orbit diagnosis measurement of Hall thruster plume. Firstly, the RGB data reflecting the spectral radiation intensity of different wavelength range was extracted from the plume image photographed by the camera. Based on the analysis of the camera imaging principle, the correspondence between the image gray value and spectral intensity was deduced. Then the plume image diagnosis model was established combined with the spectral collision radiation model. The experimental results show that the distribution of the electron temperature and ion density in the plume region calculated by the image diagnosis method is in agreement with the results of the probe measurement. The relative uncertainty of the calculated results is about 20% and 15%. It is further proved that the diagnosis method, which has moderate precision and high reliability, is suitable for the in-orbit diagnosis measurement of Hall thruster plume parameters. [ABSTRACT FROM AUTHOR]

To improve the performance of the hollow cathode as a thruster, a hollow cathode thruster with an emitter mounted on the top of the keeper was developed. It is found that the thrust and specific impulse generated by hollow cathode with the outer emitter are higher than those produced by hollow cathode. A further study shows that the ion current and ion energy in hollow cathode with an outer emitter are both higher than those in hollow cathode, and it infers that there exist ions acceleration in thrust production mechanism in hollow cathode thruster with an outer emitter causing improvements in thrust and specific impulse. [ABSTRACT FROM AUTHOR]

The adaptability of cusped field thruster changes with different operating conditions, especially with different efficiencies, which changes a lot at different gas flow rates. To overcome this problem, a diverging variable-cross-section channel was proposed to improve the performance of cusped field thrusters at low and middle gas flow rate. Meanwhile, two constant-section channels with a big diameter and a small diameter respectively were introduced to be compared with the diverging channel. Although the diverging channel may cause a little decline in the atom density compared to the small constant-section channel, the diverging channel improves the efficiency at both low and middle gas flow rates on the premise of providing a considerable thrust, because it decreases the energy loss of ions at exit and promotes ionization by improving the magnetic mirror ratio. In comparison, both the big constant-section channel and the small constant-section channel have low performances due to a lower density of gas and a bigger wall loss. Therefore, a diverging channel is beneficial to improving the performance of a cusped field thruster at low and middle gas flow rate. [ABSTRACT FROM AUTHOR]

The plume of the Hall thruster has negative effects on cover glasses of the solar panel which have high light transmission. Therefore, it is necessary to design some protective structures for solar array. Firstly, some related works were reviewed. Then, two different protection schemes were simulated using hybrid-PIC for a GEO satellite equipped with a SPT100. Finally, the advantages and disadvantages of the two schemes were analyzed and some valuable suggestions were proposed. The output power of solar array will be decreased if they are polluted. [ABSTRACT FROM AUTHOR]

Researches show that the gas distributor of Hall thrusters with manufacture and installation error, or the vent holes plugged up by the sputtered particles would result in azimuthal non-uniformity of neutrals. The influences of the degree of azimuthal non-uniformity of neutrals on the discharge characteristic and performance of Hall thrusters were studied by plugging up the vent hole of gas distributor. Current characteristic, ion current density distribution and overall performance were obtained by experiments. Results show that azimuthal non-uniformity of neutrals results in higher discharge current with the maximum of increments of 25%, lower thruster efficiency, lower special impulse, and bigger oscillation. [ABSTRACT FROM AUTHOR]