Halbach Array Assemblies

HSMAG Magnetics can design, produce and supply Halbach Arrays to customer requirements. We specialise more in the Halbach Array cylinders although we can assist in the supply of any Halbach Array design.

A typical Halbach Array design is the dipole (two pole) NdFeB Halbach Array cylinder where a ring of NdFeB magnets are assembled within a non-magnetic retaining ring to create a high magnetic field within the central air gap - the field lines being uniformly ditributed (homogenous) across the diameter of the air gap.

An example is a Dipole Halbach Array of Magnet Inner Diameter 30mm, Magnet Outer Diameter 95mm and Magnet Axial Length 40mm made using high strength NdFeB magnets (8 arc segments, each with a specific Direction of Magnetisation to pull magnetism around the ring shape of the magnetic assembly) which offers around 1T (10000 Gauss) right in the centre which drops to 0.6T (6000 Gauss) at the axial ends. Longer axial length units give slightly higher magnetic field output with increasing central axial section of more uniform high field output (the field will still drop towards the ends). Lengths of 100mm are possible in this example without the need to split the assembly into two or more axial sections. Higher homogeneity of field (uniformity of cross the diameter) is possible by using more arc segments.

The magnitude of magnetic field within the air gap can be modelled using our 3D Magnetic FEA software although the field can be crudely estimated since it is proportional to the natural logarithm of outer to inner diameter ratio times the Br of the magnetic material.

Higher fields in the central air gap are more easily achieved with smaller inner diameters (as the inner diameter increases the outer diameter can soon become too large to produce from single blocks of magnet).

Halbach Arrays can take many forms with many magnetic patterns. Linear Halbach Arrays are magnets in a row to have a magnetic pattern on the one side. Cylindrical Halbach Arrays can have magnetic fields on the inside our outside diameters. Varying pole numbers are possible, depending on the design. Halbach Arrays usually do not require ferromagnetic materials such as mild steel to carry magnetism - the magnets carry and add to the magnetic field within the magnetic circuit to allow for higher magnetic fields to be utilised in the application.

Typical applications for Halbach Arrays include motors, generators, food production, levitation, medical, R&D, University projects, etc.