Numerical simulation on the damping characteristics of electromagnetic dampers applied to superconducting gravimeters

Superconducting gravimeters currently represent the most precise relative gravimeters, boasting a resolution that can reach as low as 1 nGal. However, external disturbances pose significant challenges, as they can induce mechanical noise and zero drift in these gravimeters, thereby adversely affecting their measurement accuracy. Aiming to mitigate the impact of external interferences on the accuracy of superconducting gravimeters, this paper conducts a comprehensive simulation study on electromagnetic dampers. Based on the vector magnetic potential equation, a multi-physics coupling finite element model of the superconducting gravimeter is established in the finite element software COMSOL, such as the dynamic grid, the differential equation module, the solid heat-transfer module, and solid heat transfer. The influence of the electromagnetic damper on the vibration characteristics of the superconducting gravimeter under shock, step, and simple harmonic vibration disturbances is analyzed. Additionally, the damping coefficient of the electromagnetic damper is quantified. Then, based on the established multi-physics coupling model, the influences of the material conductivity and shell thickness on the damping coefficient are discussed. The results show that the increase of conductivity by 2 × 10⁷ S m⁻¹ and the increase of shell thickness by 0.1 mm have almost the same effects on the damping coefficient of the electromagnetic damper, and both increase the absolute damping coefficient by 0.05. Finally, an investigation is carried out on the suppression effect of electromagnetic dampers with different damping coefficients on the noise induced by simple harmonic vibration disturbances. The research results provide a reference for the design of electromagnetic dampers of superconducting gravimeters.