Experimental investigations of a plasma thrusters and its power processing units performances like an electric load of a spacecraft’s power condition system

Electro-jet (plasma or ion) thrusters are becoming increasingly common to correct a satellite orbit and perform orbit raising maneuvers to achieve the geostationary orbit. This is due to the greater efficiency of plasma thrusters compared to chemical ones.

When developing a satellite platform, an important place is the matching up of the electrical characteristics of the electric power subsystem (EPS) and on-board consumers. Intrinsically, this issue is an intersystem problem. The lack of proper attention paid to find the timely and correct solution of this problem can complicate the operation of the satellite electric power subsystem. The most important subsystem, which has a significant impact on the operation of the satellite EPS, is the electric-jet propulsion subsystem, since among on-board consumers, this one is the most powerful consumer being switched simultaneously. Transients occurred in the power supply circuits following thruster firing and shut down processes can reach significant values. An electric jet thruster only runs in conjunction with a complex electronic unit – a power processing unit (PPU), which converts the voltage of the on-board power supply into a set of voltages necessary for thruster components to run. Therefore, in the preliminary design of the propulsion subsystem, it is necessary to know the electrical characteristics of transients and ripples in the power supply circuits of the thruster / PPU combination being an electrical load of the Electric power subsystem. It is difficult to obtain the characteristics of such processes by the calculation method. Therefore, an experimental method is the most common and objective method to obtain this information. JSC ISS carried out tests allowing to measure characteristics of transients and ripples under firing, running and shut down of plasma thrusters of different types powered by corresponding PPU’s. These tests were conducted using a vacuum chamber GVU-60. A test power supply was used to simulate EPS operation. This paper presents the results of measurements and analysis of parameters of transients and ripples on PPU power buses used for thrusters and devices of three types. These results are considered to be preliminary. It is shown that the greatest difficulties can arise when operating high-power thrusters. It is concluded that for each new type of thrusters and PPU’s it is advisable to conduct interface tests of the propulsion subsystem and the satellite electric power subsystem.