A relative gravimeter featuring a superconducting planar spring and the electromagnetic levitation

The gravimeter is highly demanded to improve the accuracy of a navigation system. So we designed and fabricated a relative gravimeter featuring a superconducting planar spring and the electromagnetic levitation. The advantages of a superconductor enable the device to be with exceptional stability and have the extremely low noise. The coupling spring with the electromagnetic levitation can also offer a low resonant frequency for the high sensitivity. It consists of a Niobium vibrometer with a single planar spring, a levitation coil, and a SQUID (Superconducting Quantum Interference Device) sensor. We optimized the design parameters through mathematical analysis and mechanical-electromagnetic FEM simulations. EDM and a high vacuum-thermal process are applied to fabricate superconducting structures. Some experiments storing and discharging a persistent current are carried out at 4.2K cryogenic condition, confirming the numerical predictions.