Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a Coil

Report No. ARL-MR-0954
Authors: W Casey Uhlig
Date/Pages: June 2017; 16 pages
Abstract: This report proposes to extend the magnetic field generated by a coil along its axial direction while simultaneously shielding (or reducing) the field in the lateral direction by the application of ferromagnetic cladding on the coil. Calculations were performed for an infinitely long wire with a 2.5- x 5.0-cm rectangular cross section carrying 607,000 A as well as a magnetically saturated 2.5- x 5.0-cm rectangular piece of iron with a length much greater than the cross-sectional dimensions. These fields were combined as a baseline representative value. Two-dimensional calculations were then performed for a single-turn coil with a 20-cm diameter, metal cladding of varying permeability of μo, 10 μo, and 50 μo, and cross sections identical to the previous infinite wire and iron calculations. The field at the coil edge along the axial direction was extended up to 10%, while the field outside the coil in the radial direction was reduced by an order of magnitude, particularly within close proximity of the cladding.
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2017