Rod mangle rotation patterns for adjustable magnetic field generation

The use of adjustable magnetic field sources is becoming an indispensable necessity in numerous applications. In particular, permanent magnet assemblies, such as the rod mangle design, avoid the large power consumption and Joule heating problems present in electromagnets. In this work, we present a systematic 2D study of rod mangle configurations with different number of rods. We observe that the magnetic field homogeneity increases with the number of used rods and, for a sufficiently large number, the behavior of the assembly is similar to that of a perfect Halbach. Generally, the rotation of only one rod changes the direction and decreases the homogeneity and magnitude of the magnetic field. Nevertheless, the impact of such rotation reduces with the increase of the number of rods in the system. We also study how different rotation patterns influence the generated magnetic field and demonstrate how one can: (i) reduce the magnetic field magnitude rotating its direction; (ii) reduce the magnetic field magnitude keeping its direction constant; (iii) invert the magnetic field direction, after being reduced; or (iv) rotate the magnetic field direction keeping its magnitude constant. These results are similar to those obtained by a nested Halbach. In addition to the low cost, the results show that the mangle system is highly versatile, can be easily manipulated and, consequently, has a large application potential. The magnetic model was successfully validated with experimental systems of three and four rods.