Performance test of a high precise accelerometer or an inertial sensor on the ground is inevitably limited by the seismic noise. A torsion pendulum has been used to investigate the performances of an electrostatic accelerometer, where the test mass is suspended by a fiber to compensate for its weight, and this scheme demonstrates an advantage, compared with the high-voltage levitation scheme, in which the effect of the seismic noise can be suppressed for a few orders of magnitude in low frequencies. In this work, the capacitive electrode cage is proposed to be suspended by another pendulum, and theoretical analysis shows that the effects of the seismic noise can be further suppressed for more than one order by suspending the electrode cage.

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Seismic noise is one of the main limits of performance validation experiments for space inertial sensor on the ground. A two-stage electrostatically controlled torsion pendulum was developed and used to investigate the performances of space inertial sensor for TianQin. To further suppress the seismic noise effect, a novel scheme that introduces another pendulum to suspend the electrode housing simultaneously is proposed. By choosing proper suspension for the electrode housing with respect to the original pendulum for the test mass, the relative motion between the test mass and the electrode housing is insensitive to seismic noise due to common mode rejection, and the disturbance on the inertial sensor caused by seismic noise can be suppressed about five orders of magnitude theoretically. Both theoretical analysis and experimental results show that the scheme can further suppress the seismic noise effect more than one order of magnitude.