Minimax Current Density Coil Design

TL;DR

This paper introduces a coil design method that minimizes the maximum current density to improve magnetic field strength, heat dispersion, and practicality, demonstrated through various boundary element methods.

Contribution

It presents a novel coil design approach optimizing for minimax current density, enhancing performance and heat management in electromagnetic applications.

Findings

Coils with minimized maximum current density have more spread-out wires.

Such coils achieve higher magnetic field strength per unit current.

The approach is versatile across different boundary element method formulations.

Abstract

'Coil design' is an inverse problem in which arrangements of wire are designed to generate a prescribed magnetic field when energized with electric current. The design of gradient and shim coils for magnetic resonance imaging (MRI) are important examples of coil design. The magnetic fields that these coils generate are usually required to be both strong and accurate. Other electromagnetic properties of the coils, such as inductance, may be considered in the design process, which becomes an optimization problem. The maximum current density is additionally optimized in this work and the resultant coils are investigated for performance and practicality. Coils with minimax current density were found to exhibit maximally spread wires and may help disperse localized regions of Joule heating. They also produce the highest possible magnetic field strength per unit current for any given surface and wire size. Three different flavours of boundary element method that employ different basis functions (triangular elements with uniform current, cylindrical elements with sinusoidal current and conic section elements with sinusoidal-uniform current) were used with this approach to illustrate its generality.