Remaining Useful Life Prediction and Reliability Analysis for an Individual Ion Thruster

Ion thrusters play an important role in ensuring the success of future deep-space missions. Based on a ground-life test, a proper failure mechanism analysis was conducted, and the groove depth of the centerline accelerator grid aperture can be considered as the key lifetime metric. A nonstationary independent increment degradation model including both deterministic and stochastic parameters was proposed. The maximum likelihood estimation of the model parameters was derived by incorporating the product-level degradation data and the component-level degradation data. A Bayesian method to update the stochastic parameters describing the individual ion thruster characteristics based on product-level degradation data was developed. Then, the remaining useful life and the mean time-to-failure can be estimated and updated once a new online performance measurement is obtained. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed model.