The requirements for access and imaging performance compete in the design of open-concept MR magnets and gradient coils. We conducted a theoretical and experimental investigation of gradient coil design using both solid and laminated pole piece construction to determine whether adequate eddy current
Design of gradient coils for permanent magnets
โ Scribed by Jingguo Wang; Manlio G. Abele; Henry Rusinek
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 519 KB
- Volume
- 6
- Category
- Article
- ISSN
- 1053-1807
No coin nor oath required. For personal study only.
โฆ Synopsis
Abstract
Designing gradient coils for permanent magnets requires modeling the interaction between the currents and the ferromagnetic material. We have developed and tested an iterative design approach based on the boundary element method. The power dissipated by the gradient coil is treated as a constraint of the minimization problem. The technique is illustrated on a magnet with a rectangular prismatic cavity and two ferromagnetic plates adjacent to the coil. The procedure improved the linearity of the field from 10.5% to 3.4% and reduced the power dissipation to 63% of the power of the unoptimized coil. The optimized distribution of currents has been transformed to variable locations of coil windings without loss of gradient uniformity. The new approach significantly reduces computation time and memory storage and yields practical designs of gradient coils for permanent magnets.
๐ SIMILAR VOLUMES
Active magnetic screening allows the production of gradient coils which are magnetically decoupled from their surroundings. Using such coils the eddy current problems associated with the generation of large, rapidly switched gradients within the confines of a superconductive magnet can be eliminated
The target field method of designing gradient coils is extended to the case where the gradient producing currents lie on cylinders of a general orientation with respect to the polarizing magnetic field. This provides a general approach for designing coils that require unusual sample geometries such