Adaptive Disturbance-Rejection Charge Control Method via Ultraviolet Discharge for Space-Based Gravitational Wave Detection

In space-based gravitational wave detection missions, the test mass (TM), which serves as the inertial reference, must maintain extremely low residual acceleration noise. During in-orbit operation, Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) cause charge accumulation and additional electrostatic forces. Therefore, ultraviolet (UV) light is used to illuminate the interior of the inertial sensor and regulate the TM charge through the ultraviolet photoelectric effect. However, surface contamination, temperature fluctuations, and material aging can degrade the surface Quantum Yield (QY) of the TM. In addition, transient intense charging disturbances induced by SEP events can rapidly alter the charge state of the TM, thereby degrading the long-term performance and operational stability of the Charge Management System (CMS). To address these issues, based on the nonlinear UV discharge model of the CMS, this study investigates the effects of QY degradation and external charging disturbances on the charge-transfer dynamics and control performance of the CMS and proposes an adaptive disturbance-rejection charge control method that integrates a Fuzzy self-tuning PID (FPID) controller with an Extended State Observer (ESO). Simulation results show that the proposed method enables effective charge regulation under different illumination schemes and prescribed QY degradation and external charging conditions and exhibits greater adaptability than conventional PID and fuzzy PID controllers. The findings of this study provide a theoretical reference for the design of charge control systems operating in complex space environments.