An idealized magnetic sheet current model for a toroidal coil which encircles a conducting ferromagnetic rope is analyzed. This configuration is suitable for the nondestructive testing of wire ropes and cables. Numerical results for the axial electric current density induced in the rope reveal that low frequencies on the order of 10 Hz are required to produced a uniform current in a typical rope. For a toroidal coil which does not completely encircle the rope, the azimuthal symmetry is lost and harmonics in ϕ are produced. These harmonics are large but decay rapidly away from the source.
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