Comparison of adjustable permanent magnetic field sources

TL;DR

This paper compares five mechanically adjustable permanent magnet designs through simulations and experiments, identifying the concentric Halbach cylinder as the most efficient in flux density and material use.

Contribution

It provides a comparative analysis of five adjustable permanent magnet configurations using numerical simulations and experimental validation.

Findings

Concentric Halbach cylinder offers highest flux density with minimal magnet material.

Experimental results agree well with simulations.

The design is compact and efficient for adjustable magnetic fields.

Abstract

A permanent magnet assembly in which the flux density can be altered by a mechanical operation is often significantly smaller than comparable electromagnets and also requires no electrical power to operate. In this paper five permanent magnet designs in which the magnetic flux density can be altered are analyzed using numerical simulations, and compared based on the generated magnetic flux density in a sample volume and the amount of magnet material used. The designs are the concentric Halbach cylinder, the two half Halbach cylinders, the two linear Halbach arrays and the four and six rod mangle. The concentric Halbach cylinder design is found to be the best performing design, i.e. the design that provides the most magnetic flux density using the least amount of magnet material. A concentric Halbach cylinder has been constructed and the magnetic flux density, the homogeneity and the direction of the magnetic field are measured and compared with numerical simulation and a good agreement is found.