Lifetime and Mission reliability assessment of multi-mode ion thruster

Abstract

An approach to quantify the lifetime and mission reliability of multi-mode ion thruster is presented. The reliability of LIPS-300S thruster completing the Asteroid Exploration Mission is assessed. The procedure of this approach is (i) assess the life margin factor (LMF) against each failure mode according to the wear test results, then identify the engineering failure modes whose LMFs are less than 1.5; (ii) quantify the uncertainty in the lifetime based on each engineering failure mode and identify the key failure mode with the minimum LMF; (iii) sample the lifetime based on the key failure mode and obtain its 3-parameter Weibull distribution; (iv) simplify the throttle profile as operations at several representative throttle levels, then obtain the conditional lifetime distribution for each operation based on previous operations; (v) considering all possible failure modes, integrate the probability of completing each operation as the total reliability index. The results show that LIPS-300S can complete the Asteroid Exploration Mission with a reliability of 100%.

Wide-range characteristics of beam perveance and saddle point potential of LIPS-200 ion thruster

“…By quantifying the lifetime and reliability of LIPS-200 ion thruster based on test-verified models, its critical failure modes are confirmed to be GSF and EBSF [12,26,27]. To achieve an ultimate lifetime of 20 000 h under the restriction of remaining its readiness level, the constant-accel-potential and stepping-accel-potential methods have been presented and validated by test-verified life models [28]. The mechanism of these methods is to adjust the accel grid potential and make GSF and EBSF occur at the same time [27].…”