Performance and preliminary life test of a low power hydrazine engineering design model arcjet

Abstract

Performance and preliminary life test of a low power hydrazine engineering design model (EDM) arcjet thruster is carried out to characterize the performance of the thruster operated with different propellants and to demonstrate the life capability of the arcjet thruster accompanied with the power control unit (PCU). Performance parameters of the thruster operated with argon, nitrogen and nitrogen/ammonia mixture simulating hydrazine are measured over a range of both arc current and mass flow rate. With the arc current fixed at 10 A, typical specific impulse values of the thruster obtained in the tests are 150 s, 250 s and 500 s for the case with argon, nitrogen and nitrogen/ammonia as propellant, respectively. The life test is terminated after an accumulative 245-hour operation. Nitrogen is used as propellant with the mass flow rate of 50 mg/s during the first 100 hours, and nitrogen/ammonia mixture simulating hydrazine is used as propellant with the mass flow rate of 26 mg/s in the next part of the life test. Voltage increase as well as propellant feed pressure decrease are observed over the life test. Post-test component inspection shows that the erosions of cathode and anode are evident. It is believed that the performance degradation of the thruster is contributed to the leak of thruster body.