1 T Halbach Array: Design, Materials, Manufacturing, and Applications Guide

A 1 T Halbach array is a permanent magnet arrangement that redirects magnetic flux to create a field of roughly 1 tesla on one side while cancelling it on the other. The result is a stronger, more concentrated field than a conventional magnet array of the same size, and it is achievable with sintered NdFeB magnets.

If you need a 1 T field for a motor rotor, a linear stage, or a magnetic assembly, the first question is not which magnet to buy but which array geometry to use. This guide explains the design choices, the material requirements, and the practical limits you should expect.

What Is a 1 T Halbach Array?

A Halbach array is a pattern of permanent magnets whose magnetization direction rotates by a fixed increment from one magnet to the next. In a 1 T Halbach array, this rotating pattern is engineered so that the internal or working-side field reaches approximately 1 tesla, while the external field on the return side drops to near zero.

Unlike a simple alternation of north and south poles, a Halbach array uses the superposition of each magnet's flux to augment one side and cancel the other. This self-shielding effect reduces the need for a yoke and makes the assembly lighter and more compact.

Why 1 T and How Strong Is That?

One tesla is a high field for a permanent magnet assembly at practical size. For comparison, a strong N52 NdFeB magnet has a residual flux density of about 1.45 T inside the material, but the open-air field from a single magnet is usually far below 1 T. A Halbach array is one of the few ways to approach 1 T in free space without a superconducting coil.

The threshold matters because many devices—such as magnetic couplings, compact rotors, and magnetic clamping systems—require a specific working flux density. A 1 T array also enables higher torque density in motors and stronger magnetic gradients in sensor applications.

NdFeB Magnets and the Halbach Effect

Sintered NdFeB is the only practical magnet material for a 1 T Halbach array. Ferrite and Alnico cannot deliver the required energy product. The high remanence and coercivity of NdFeB let you use fewer magnets while maintaining the needed flux concentration.

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For a well-designed array, the choice of NdFeB grade is critical. Grades with higher remanence, such as N45 or N52, increase the working field but also raise the risk of demagnetization at high temperature. You also need to specify the magnet shape and coating. The product parameter tables on our site list the available grades and their physical properties.

Design Considerations for a 1 T Array

The geometry determines both the achievable field and the ease of assembly. A linear array creates a uniform field along a plane, while a cylindrical array produces a strong field inside the bore. The number of segments is the main variable.

In practice, a 16-segment cylindrical Halbach array made from N52 blocks can reach a bore field close to 1 T, but the magnets must be held precisely. Dimensional tolerance and orientation accuracy directly affect the final field value. For a linear array, the same principle applies: more segments produce a more sinusoidal field and fewer harmonics.

Temperature is another design constraint. NdFeB loses flux as temperature rises, so a 1 T array designed for 80°C might only deliver 0.9 T at 120°C unless the magnet grade and the array geometry are optimized for that operating point.

To achieve a reliable result, you need to specify the magnetic field direction, the target field at a specific air gap, the magnet grade, the coating, and the dimensional tolerances.

Manufacturing and Assembly Realities

A 1 T Halbach array is not a standard off-the-shelf product. It requires custom magnet shapes, precise magnetization, and specialized assembly. The attractive forces between adjacent magnets are so strong that even a small array can be dangerous to handle without a fixture.

Custom-Shape Sintered NdFeB Magnets for Precise Assembly Custom-shaped sintered NdFeB magnets fit specific housings or stators, and with nickel, zinc, or epoxy coatings, they ensure corrosion protection for demanding Halbach array designs. View Product →

Most manufacturers use a two-step approach: the magnets are produced and magnetized individually, then aligned on a mandrel or in a jig during assembly. The coating is also critical—nickel, zinc, or epoxy coatings protect NdFeB from corrosion. A custom shape is often the only way to fit the array into a specific housing or stator.

If you need a robust 1 T array for industrial use, ask the supplier about their tolerance for angular magnetization, flatness, and gap uniformity. A small angular error in one segment can reduce the working field by more than 10%.

Applications That Benefit from a 1 T Halbach Array

The strongest demand for 1 T Halbach arrays comes from high-performance motors and generators. A Halbach rotor creates a larger air-gap flux than a conventional rotor with the same magnet mass, which improves torque density and reduces inertia.

Sintered NdFeB Magnets for High-Performance Synchronous Motors These sintered NdFeB magnets for synchronous motors offer high remanence, coercivity, and thermal stability, enabling increased torque density and reduced inertia in advanced motor designs. View Product →

Other applications include magnetic levitation systems, bearingless motors, nuclear magnetic resonance (NMR) devices, and magnetic couplings. For example, a linear Halbach array is used in magnetically levitated transport and in precision positioning stages. The NdFeB motor industry benefits from these arrays in both rotary and linear designs.

In medical devices, a 1 T field inside a bore can be generated with a Halbach cylinder, providing a compact alternative to bulky superconducting magnets for tabletop MRI or spectroscopy units.

How to Specify a 1 T Halbach Array

Start with the field requirement and the working gap. A 1 T array is meaningless without specifying where that field must exist. The dimensions of the active volume, the direction of the field, and the allowable ripple all affect the magnet arrangement.

• Target field strength in tesla at a defined air gap or bore.
• Array geometry: linear, cylindrical, or planar.
• Magnet grade and working temperature.
• Magnet orientation tolerance and position tolerance.
• Surface coating for corrosion and environment.
• Assembly method and max allowed magnetic leakage.

During commissioning, you should expect a prototype or simulation report that shows the field map. A responsible supplier will verify the actual field with a Gauss meter or flux mapping system before shipment.

FAQ

Can a Halbach array really reach 1 T?

Yes, with high-grade NdFeB magnets and enough segments. A cylindrical array can produce higher than 1 T in the bore if the magnets are large enough and the geometry is optimized. Linear arrays usually produce lower fields because the working area is open.

What is the difference between a 4-segment and a 16-segment array?

More segments give a stronger and more uniform field, but the assembly becomes more complex. A 4-segment array is easier to build but has a lower field gain and more harmonics. A 16-segment array approaches the ideal Halbach field distribution.

Does temperature affect a 1 T Halbach array?

Yes. NdFeB loses magnetic strength as temperature rises. If your array operates above 80°C, you need a higher temperature grade (such as N45H or N35SH) and may need to adjust the design to maintain 1 T.

How long does a Halbach array last?

With proper coating and controlled operating temperature, the magnetic field is stable for decades. The main risk is corrosion, not magnetic decay.

A 1 T Halbach array is a powerful, compact magnet solution that relies on the right combination of NdFeB material, geometry, and assembly precision. Whether you are building a motor rotor, a magnetic stage, or a research device, the path to success is to specify the field, choose the correct segment count, and work with a manufacturer that understands the realities of permanent magnet arrays.