Low-frequency EM field penetration through magnetic and conducting cylindrical shields

Computation of fields due to a 500 turn coil positioned arbitrarily within a pipe constructed of conducting and/or magnetic material is performed using multi-region cylindrical harmonic modal expansions. Results involving steel and aluminum indicate the relative significance of shielding due to induced magnetization and eddy-current generation. Extension to an arbitrarily oriented coil is being investigated. The goal is to design multilayered structures composed of conducting and magnetic materials for a specified frequency range. Such shields are designed under constraints of layer number, thickness and weight using an evolutionary optimization algorithm.