Electromagnetic Forces on a Metal Disk in an Alternating Magnetic Field

Many fast-acting electromechanical devices utilize the repulsion forces produced on a metal disk subjected to a transient magnetic field. Coupled circuit theory yields a simple expression for this force in terms of an equivalent inductance. The equivalent inductance, however, is difficult to evaluate by theoretical and/or experimental methods when the metal disk is very close to the magnet coil. A numerical method for calculating the electromagnetic forces in such devices is described.