Capacitive Sensing-Based Charge Measurement for Space Inertial Sensors

High-energy particles in space will inevitably penetrate the spacecraft into the suspended test mass, which would seriously affect the detection of gravitational waves; therefore, charge measurement and control are essential. Based on the working principle of space inertial sensors, this article proposes a new charge measurement scheme based on capacitive sensing in nonsensitive axes for simultaneous charge measurement during the detection of gravitational waves. According to the dynamic model and actual parameters, the resolution of the proposed method is evaluated as about
$6.60\times 10^{-17}$
C in space, which can meet the detection requirement. Further, a torsion pendulum device was set up on ground to carry out charge measurement experiments and verify the evaluation method. The experimental results show that the optimal resolution with the capacitive sensing is about
$1.65\times 10^{-14}$
C at 1 mHz, which agrees with the theoretical evaluation. This work demonstrates the feasibility of the capacitive sensing-based charge measurement, which will be a potential scheme in the detection of gravitational waves.