Design of gradient coils for permanent magnets

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Electromagnetism
• Materials Science

Background:

• Designing gradient coils for permanent magnets necessitates accurate modeling of current-ferromagnetic material interactions.
• Existing methods may face challenges in optimizing linearity and power efficiency simultaneously.

Purpose of the Study:

• To develop and validate an iterative design approach for gradient coils in permanent magnet systems.
• To improve magnetic field linearity and minimize power dissipation in gradient coils.

Main Methods:

• Utilized the boundary element method (BEM) for iterative design.
• Incorporated power dissipation as a constraint within a minimization problem.
• Applied the technique to a permanent magnet with a rectangular cavity and ferromagnetic plates.

Main Results:

• Achieved a significant improvement in field linearity, reducing non-linearity from 10.5% to 3.4%.
• Reduced power dissipation to 63% of the unoptimized coil's power consumption.
• Translated optimized current distributions into practical coil winding configurations without compromising gradient uniformity.

Conclusions:

• The developed iterative BEM approach provides an effective method for designing gradient coils for permanent magnets.
• The technique offers substantial reductions in computational time and memory requirements.
• This method yields practical and efficient gradient coil designs for permanent magnet applications.