Eddy Current Compensation for Z-Gradient Array Coils with Constraints on Copper and Cryostat Losses: An Electromagnetic Approach

Motivation: Gradient array coils require fast methods to control eddy losses and mitigate secondary magnetic fields. Goal(s): Compensate for secondary fields from induced eddy currents in gradient array coils while managing ohmic power losses within the cryostat and the coils. Approach: A framework is proposed that utilizes the orthogonality of harmonic components of pulse sequences to generate customizable gradient fields with adjustable precision, while compensating for eddy and copper losses and mitigating the secondary fields produced by the induced eddy currents. Results: Optimized waveforms within a 48-element z-gradient array coil compensate for secondary fields of eddy currents from a 300 T/m/s trapezoidal pulse. Impact: Our approach enables regulation of time-average eddy and copper losses and compensate for secondary fields in gradient array coils, enhancing imaging fidelity while allowing dynamic tuning of magnetic profiles, thereby advancing the performance of modern MRI systems.