Two German physicists have unveiled a compact magnet layout that outperforms the famed Halbach array, delivering stronger, more even magnetic fields without bulky superconductors.
Their 3D-printed ring stacks matched analytic predictions and could slash the cost of MRI machines while opening doors for levitation tech and particle accelerators.
Breakthrough in Magnetic Field Generation
Physicists Ingo Rehberg at the University of Bayreuth and Peter Blümler at Johannes Gutenberg University Mainz have unveiled a fresh way to create smooth, uniform magnetic fields using everyday permanent magnets. Their compact setup beats the classic Halbach arrangement, which only works perfectly for magnets of impossible, infinite length.
In real-world, finite sizes, the new design delivers stronger fields and far better uniformity. The breakthrough appears in Physical Review Applied, a leading journal that highlights advances where physics meets engineering, materials science, chemistry, biology, and medicine.
Limitations of Classical Halbach Arrays
Engineers often turn to the Halbach array when they need a tidy, even magnetic field. The idea assumes you can arrange very long magnets in a circle so that their fields blend perfectly at the center. In practice, real magnets are finite. As soon as you shrink the array to a usable size, the magic fades: field strength wobbles from one spot to another, and the setup can no longer claim top performance. Rehberg and Blümler’s optimized three-dimensional arrangement fixes those flaws, giving scientists and engineers a powerful new tool for technologies that demand strong, uniform magnetic fields.
Innovative 3D Magnet Configurations
In their work, Dr. Peter Blümler and Professor Ingo Rehberg present optimal three-dimensional arrangements of very compact magnets, idealized by point dipoles. With a view to possible applications, they investigated, among other things, the optimal orientation of the magnets for two geometries relevant to practical use: a single ring and a stacked double ring. A so-called focused design additionally allows the generation of homogeneous fields outside the magnet plane, for example in an object positioned above the magnets.
For these new arrangements, Rehberg and Blümler developed analytical formulas, which they subsequently validated experimentally. To this end, they constructed magnet arrays from 16 FeNdB cuboids mounted on 3D-printed supports. The resulting magnetic fields were measured and compared with theoretical predictions, revealing excellent agreement. In terms of both magnetic field strength and homogeneity, the new configurations clearly outperform the classical Halbach arrangement as well as its modifications described in the literature.
Real-World Impact and Applications
The new design concepts offer great potential for applications in which strong and homogeneous magnetic fields are required. In conventional magnetic resonance imaging (MRI), for example, powerful superconducting magnets are used to polarize hydrogen nuclei in tissue. These nuclei are then excited by radio waves, generating measurable voltages in detectors surrounding the body. Algorithms use these signals to calculate detailed cross-sectional images that allow physicians to distinguish tissue types based on properties such as density, water or fat content, and diffusion. However, superconducting magnets are technically complex and extremely costly, making this technology hardly available in many parts of the world. For such cases, intensive research is underway to develop alternative methods for generating homogeneous magnetic fields using permanent magnets – a field to which the present study makes a promising contribution. Further potential areas of application include particle accelerators and magnetic levitation systems.
Reference: “Analytic approach to creating homogeneous fields with finite-size magnets” by Ingo Rehberg and Peter Blümler, 11 June 2025, Physical Review Applied.
DOI: 10.1103/9nnk-jytn
Never miss a breakthrough: Join the SciTechDaily newsletter.
6 Comments
In their work, Dr. Peter Blümler and Professor Ingo Rehberg present optimal three-dimensional arrangements of very compact magnets, idealized by point dipoles.
VERY GOOD!
Please ask the researchers to think deeply:
How is the point dipole formed?
If researchers are interested in this, please browse https://zhuanlan.zhihu.com/p/1913593938872336502.
Special Note: Two sets of cobalt-60 artificially manipulated to rotate in opposite directions, regardless of symmetry, are mutually mirror-imaged objects. This constitutes a poignant demonstration of how contemporary physics and certain so-called peer-reviewed publications—including Physical Review Letters (PRL), Science, Proceedings of the National Academy of Sciences (PNAS), and Nature — persist in disseminating pseudoscience.
If researchers are interested in this, please browse https://zhuanlan.zhihu.com/p/1918614826130838141.
There are more facts and evidence that so-called peer-reviewed publications insist on and disseminate pseudoscience. Please be patient, friends who love science and disdain pseudoscience.
I wonder if one possible application would be powering every day objects in a room without the need for power cords. For example, I wonder if a lightbulb can simply be placed anywhere in the room without being needed to be plugged in, somehow using this tech…
I wonder if this tech could eventually lead to powering every day objects in a room without the need for power cords or electrical outlets. For example, I wonder if a lamp or a fan can be placed in a room, without needing to be plugged in.