Stray Potential Measurement Based on Capacitive Sensing for Inertial Sensors

Measuring and reducing the stray potentials of space inertial sensors is of great significance for gravitational wave detection. Because of the actual configuration of inertial sensors, the optical displacement reading can, however, only be applied to the stray potential measurement of the sensitive axis. This article proposes to use capacitance sensing instead of optical reading for stray potential measurement in six degrees of freedom. According to theoretical models and design parameters, the in-orbit measurement resolution of the proposed method can reach $1~\mu $ V, which meets the requirements for gravitational wave detection. Additionally, a torsion pendulum device is established on the ground to conduct stray potential measurement experiments. Experimental results show that the measurement resolution is 0.47 mV based on capacitive sensing at the modulation frequency of 0.001 Hz, which is consistent with theoretical expectations on the ground. This work validates the feasibility of the capacitive sensing-based measurement method, providing a new solution for stray potential measurement during gravitational wave detection.