Specifics of transients in the discharge circuit during the SPT-140D plasma engine starting

Аuthors

Ermoshkin Y. M.^1*, Galaiko V. N.^2*, Kim V. P.^3*, Kochev Y. V.^1*, Merkur'ev D. V.^3*, Ostapushenko A. A.^2*, Popov G. A.^4*, Smirnov P. G.^3*, Shilov E. A.^3*, Yakimov E. N.^1*

1. Satellite Information Systems, SIS, 62, Lenin str., Zheleznogorsk, Krasnoyarsk Region, 862972, Russia
2. Scientific & Industrial Center Polyus, 56v, Kirova av., Tomsk, 634050, Russia
3. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
4. Research Institute of Applied Mechanics and Electrodynamics of Moscow Aviation Institute (RIAME MAI), Moscow, Russia

*e-mail: riame4@sokol.ru

Abstract

The article presents the results of transients' in discharge circuit studies during SPT-140D plasma thruster starting while its operation together with power processing unit (PPU). SPT-140D is an electric thruster developed by the Design Bureau “Fakel”. This thruster was running on Xenon with the discharge voltage of 300 V and power of 4.5 kW, ensuring reactive thrust 280-290 mN and 1750 s specific impulse of thrust. At present, this thruster is ready for flight application for spacecraft motion control. The PPU unit was developed and manufactured by the Scientific and Production Center “Polus”. Since the main discharge is one of the powerful PPU loads, the main attention was payed to the study of transients in the power supply circuit of the main discharge. The obtained data was used for the development of imitation model of the named transients and electric imitator of the thruster for off-line PPU optimization and testing without the thruster. In addition, the information on the specifics of the thruster operation was obtained. The most interesting among them are the following:

1. In the course of the thruster starting, after the main discharge ignition by the discharge voltage increasing with the rate of about 1 V/ms, the main discharge could ignite by various discharge voltages. Though after the discharge ignition its parameters during various start-ups vary according to one and the same averaged dynamic volt-ampere characteristic, close to the “static” characteristic obtained with slow voltage changing.

2. Various oscillation modes of the discharge parameters were revealed, arousing at the various stages of discharge voltage variation, and changing drastically with the small variation of the discharge voltage. It allows evaluate the increment of their build-up.

3. After reaching the nominal discharge parameters, the dominating discharge current oscillation mode frequency is 15-20 kHz. After an hour of continuous operation it reaches the value of 27-27 kHz, and its further variation is insignificant. It can be explained by the discharge chamber heating resulting in Xenon atoms velocity increase, decrease of their drift time through the ionization layer and acceleration leading to the frequency increase according to ionization-drifting oscillations excitation model.

Thus, the employed methodology of the study is useful also for conducting physical research of the processes in the thruster.

Keywords:

stationary plasma thruster (SPT), power processing unit (PPU), SPT operation modes, thruster starting, transients in the main discharge circuit

References

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