Pulse distortion due to eddy currents induced in a multiply excited cylindrical shell of finite length and thickness

The electromagnetic field due to pulse excitation of two crossed pairs of coils surrounded by a cylindrical conducting shell is determined by accounting for the eddy-current effect. Each coil is modeled as a pair of straight, parallel wires of infinite length; the surrounding conducting shell is a cylindrical tube of finite length and thickness. The problem is formulated in the frequency domain, and the resulting expressions are used to calculate the transient magnetic flux density which originates from the quadruple coil and the eddy currents induced within the metallic shell. The part due to the eddy currents represents an unwanted distortion, which is investigated through a numerical example. The analytical and numerical results are complemented by a brief discussion on compensation techniques and potential applications in magnetic resonance imaging