EXTENDED LIFE AND PERFORMANCE-TEST OF A LOW-POWER ARCJET

An automated, cyclic life test was performed to demonstrate the reliability and endurance of a low-power dc arcjet thruster. Over 1000 h and 500 on-off cycles were accumulated, which would represent the requirements for about 15 years of on-orbit lifetime. A hydrogen/nitrogen propellant mixture was used to simulate decomposed hydrazine propellant, and the power level was nominally 1.2 kW after the burn-in period. The arcjet operated in a very repeatable fashion from cycle to cycle. The steady-state voltage increased by approximately 6 V over the first 300 h, and then by only 3 V through the remainder of the test. Thrust measurements taken before, during, and after the test verified that the thruster performed in a consistent fashion throughout the test at a specific impulse of 450-460 s. Post-test component evaluation revealed limited erosion on both the anode and cathode. Other thruster components, including graphite seals, appeared undamaged.