Analysis of a mechanical method for dynamic stabilization of tuned circuit levitators

The paper describes recent developments in the field of tuned circuit levitators. Static stability is attained in such levitators by employing a suspension electromagnet which is the inductive part of a resonant circuit. However, it is already well known that a tuned circuit electromagnet on its own is usually not sufficient to maintain levitation for long periods of time, and the suspended object tends to be dynamically unstable. The dynamic instability is prevented in the work described here by adding an auxiliary electromagnet in parallel with the main suspension electromagnet. Mechanically damping vibrations of an aluminium plate in the field of the auxiliary electromagnet serves to prevent the system as a whole from performing coupled oscillations. This new process of stabilization has been briefly described in a recent paper, and it is now investigated both experimentally and analytically. The approximation of slowly varying quantities is used for the analysis, and the dynamic behaviour of the complicated non-linear electromechanical system is successfully interpreted.