A scalable design framework for single-sided permanent magnet arrays (PMAs).

Area of Science:

• Physics, Applied Magnetics
• Biomedical Engineering, Imaging Systems

Background:

• Conventional permanent magnet array (PMA) designs, such as Halbach and C/H-shaped geometries, are limited by fixed structural patterns.
• Designing single-sided PMAs involves navigating a high-dimensional configuration space, posing computational challenges.

Purpose of the Study:

• To introduce a scalable design framework for single-sided permanent magnet arrays (PMAs).
• To enable efficient exploration of complex, high-degree-of-freedom PMA configurations.
• To facilitate the design of PMAs for open-geometry imaging systems, including portable MRI.

Main Methods:

• Decomposition of the design space into symmetry-defined modules for independent optimization.
• Utilization of magnetic-field superposition for combining modular contributions.
• Fabrication and testing of a prototype PMA with 400 N52 magnets.

Main Results:

• The prototype PMA generated a 49 mT magnetic field at 65 mm depth over an 80mm×20 mm field of view (FoV).
• A monotonic built-in gradient for slice selection was achieved within the FoV.
• The proposed method demonstrated superior performance compared to genetic-algorithm-based approaches, yielding higher field strength and stable field direction with the same magnet count.

Conclusions:

• The modular design framework offers a computationally tractable and efficient pathway for optimizing single-sided PMAs.
• The framework supports scalable exploration of high-dimensional configurations, crucial for advanced imaging applications.
• The developed method enables the creation of compact and effective PMAs for portable MRI and other open-geometry systems.