Revolutionary approach: Homogeneous magnetic fields with new permanent magnets!

Revolutionary approach: Homogeneous magnetic fields with new permanent magnets!

The search for efficient methods to generate homogeneous magnetic fields has reached a new peak. Physicist Prof. Dr. Ingo Rehberg from the University of Bayreuth and Dr. Peter Blümler from Johannes Gutenberg University Mainz have developed an innovative approach that surpasses the classic Halbach arrangements. Their research, published in the journal Physical Review Applied, shows that strategically arranging permanent magnets can achieve higher field strengths and improved homogeneity in compact magnet arrangements. These findings could have far-reaching implications for various technologies that require strong and uniform magnetic fields, including magnetic resonance imaging (MRI).

Traditionally, Halbach arrays are based on the assumption of infinitely long magnets, which is not feasible in practical applications. University of Mainz highlights that Rehberg and Blümler examined the geometries of a single ring and a stacked double ring in their work. They modeled the magnets as point dipoles. Their “focused” design allowed the creation of homogeneous fields outside the magnetic plane. By developing analytical formulas, they were able to validate the experimental results, which matched well with the theoretical predictions. These new arrangements proved to be superior compared to the classic Halbach arrangements.

Optimized geometries and experimental validation

The path to these findings began with a detailed investigation of optimal three-dimensional arrangements of permanent magnets. The new designs show significant advantages over the previously preferred Halbach arrangement. According to the paper, submitted on February 25 and last revised on May 30, 2025, the optimal arrangement for shorter magnets deviates from traditional designs and thus offers new perspectives for magnetic field production. arXiv describes the theoretical basis of these approaches and the results achieved.

In addition, the experimental realizations result in high application potential for the new technology. It could promote the development of cheaper alternative technologies that could replace the classic, often very expensive, superconducting magnets in MRI. Although superconducting magnets are powerful, their high cost and technical complexity significantly limit their availability.

Applications and future prospects

The applications for these new magnet arrangements are extensive. In addition to MRI, they could also be used in accelerator physics and magnetic levitation systems. These technologies require strong and homogeneous magnetic fields, and the new approaches offer advantages here. The Halbach array, also known for its use in various technologies such as flat refrigerator magnets and brushless DC motors, has already proven to be effective in field configuration. Wikipedia explains the advantages of the one-sided flux distribution caused by the alternating magnetization patterns of the Halbach array.

The discovery by Rehberg and Blümler is not only a significant advance in magnetic field technology, but also opens doors for future innovations in materials science and engineering. In a world increasingly reliant on technological solutions, this new approach could play a key role.