Modeling of a Magnetic Flux Concentrator

Report No. ARL-TR-3166
Authors: Gregory A. Fisher and Alan S. Edelstein
Date/Pages: March 2004; 21 pages
Abstract: Using the Maxwell 3-D finite element analysis software package from Ansoft, ARL performed magnetic modeling of the Visidyne flux concentrator. Visidyne Corp. has investigated using the Faraday effect to develop a high sensitivity vector field magnetometer. Laser light is sent down a hole in permalloy rods and passes through a single crystal of Yttrium-Iron-Garnet(YIG). Small changes in the surrounding magnetic field result in minute changes in the polarization of the light as it passes through the YIG. The permalloy rods act as flux concentrators, but the YIG crystal is not only part of the magnetic field sensor but also an integral part of the flux concentrator itself. We modeled the Visidyne flux concentrator in order to determine the enhancement factor given the dimensions, materials, and relative permeability of their materials. This factor was found to be 361 to 365. Variations in relative permeability of the permalloy as well as changes in teh dimensions of the permalloy parts were also modeled. It was determined that changes in dimensions had an impact on the enhancement factor, allowing us to obtain a factor of 509. It was also shown that, if possible, an increase in the relative permability of the YIG crystal could produce enhancement values in excess of those produced by changes in dimensions.
Distribution: Approved for public release
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Last Update / Reviewed: March 1, 2004