Oscillatory and rotational instabilities in electromagnetic levitation

Two different instability mechanisms of electromagnetically levitated bodies are analyzed. The first is due to the virtual coupling between the electric current passing through the magnetic system and the variation of position of the body. This mechanism can result in unstable mass center oscillations of a levitated solid body. Another type of instabilities may occur because of the coupling beween the motion and the electric currents induced in the body. This effect can cause a spontaneous rotation of the body setting in as the frequency of the alternating magnetic field exceeds certain critaical threshold depending on the configuration of the field. This instability can be suppressed by an axial steady magnetic field of strength comparable to that of the levitating field.