Design of Equidistant Hexagonal Coil System for Demagnetization of Naval Vehicles

Abstract

In various applications of defence and research such as demagnetization of naval vehicles and satellites, removal of residual magnetic field plays an essential role. For such use cases, conventional way of demagnetization is the use of Helmholtz coils and Merritt coils. These coil systems produce uniform magnetic field, but the volume of the uniform region is relatively smaller. Therefore, for the applications which require patch of uniform magnetic field for longer longitudinal length of the region such as deperming process of Submarine, Aircraft Carrier; these coil systems become infeasible to implement practically due to their enormous size. Another impediment in implementation of above-mentioned coil system is that when size of coil system becomes larger, the requirement current also increases for the same degree of results. This increasing amount of current poses issues of more complexities in electrical control circuits, heat dissipation and cost. Another disadvantage with such system is that a slight shift from the optimized position causes a larger change in uniformity, and thus, such systems are not robust with shift in location. This paper proposes a novel method for the design of a higher-order equidistant coil system which overcomes these flaws and presents a technique to compute the ampere-turns requirement of each coil for generation of higher-degree homogeneous magnetic field. The system so designed has more feasible design parameters as compared to the conventional systems for high uniformity applications. The proposed system is sturdier and fault tolerant against any deviation or error from the ideal design parameters. The theoretical results are matched against the finite element simulation software Opera which are in close agreement.