In the current work, we propose a new configuration which, in principle, allows for a low resonant frequency in all six degrees of freedom of the suspension system and which can have a much better seismic isolation than a single translational degree of freedom alone.
It is similar to the one proposed by Varvella et al. (cf. Ref. [4] in the Review page), the magnetic scheme considered here is part of the multistage suspension system, instead of attaching magnetic directly to the test mass or levitating the test mass itself as proposed and demonstrated by Drever et al. (cf. Ref. [1] and Ref. [2] in the Review page).
The schematic plot the proposed scheme is shown in figure below:
In this figure, there are three layers of magnets like a sandwich :-). The top and the bottom magnets are fixed with respect to the platform, and the suspended magnets sit in the middle. Each circle represents a cylindrical magnet with plus and minus denoting the magnetic poles. There are a total of sixteen magnets in the suspended plate. Correspondingly, there are sixteen top and the sixteen bottom magnets, each aligned with the corresponding suspended magnet in the z-axis. They will have the correct poles to create the required levitating force to balance the gravitational force.
There are additional control coils on the fixed magnets in order to create a stable suspension. In the ideal, case when the magnets are perfectly balanced, there is an equipotential plane between the fixed and suspended magnets. If the suspended magnets sit right in the middle, the resonant frequency of motion in the horizontal plane will be close to zero. Due to the intrinsic symmetry, such a scheme can, in principle, achieve a very low intrinsic resonant frequency in other degrees of freedom.
At the same time, it is not susceptible to fluctuations of the ambient magnetic fields because in the far field, it only has high-order moments. In addition, there is no coupling between the tilt and translation motions if the position of the suspended magnet can be well controlled. It offers us the opportunity to incorporate sophisticated control protocols into this scheme with modern control techniques.