Mechanical and Electrical Oscillations of a Superconductor Coil and its Applications

In this paper we discuss the phenomenon of resonance that we predict will occur when a superconducting coil is submitted simultaneously to a magnetic field and to an external force. When both the force and the magnetic field are constant in time the coil should oscillate mechanically around an equilibrium position like an ideal harmonic oscillator, and should have induced in it an alternating current of same frequency. We obtain an expression for the resonance frequency, which is directly proportional to the applied magnetic field and depends also on the wire superconducting properties. We discuss also a setup with no built-in magnet, in which the coil is driven by a mechanical oscillator, and thus the force varies cyclically with time. A measurable alternating current may be induced in the device for an amount of magnetic flux as small as one flux quantum, so that the device is an excellent magnetometer.