[O-2-257] Temporal-spatial responses of planar X-gradient eddy currents by solid angle coupled circuit method
Simulation has been conducted for eddy currents induced by planar X-gradient (Gx) coil in RF shielding box of a 0.3 T open MRI system (Fig. 1) by a new coupled circuit calculation. In simulation, eddy current conducting structures are divided into inductively coupled subdomains (Fig.1) and, spatial-temporal responses are simulated from inductive coupling between gradient coil and subdomains. To calculate inductive couplings between Gx coil and any subdomains in 3D, solid angle form of Ampere’s law was implemented [2]. Since Gx coil loops are asymmetric with respect to magnet center, a simple rectangular segmentation approach is implemented in Cartesian coordinate to calculate solid angle in 3D. This approach is computationally less complex, avoids complex computation in cylindrical coordinates, needs less computer memory, can provide analytical solution. Transient (Fig.2) and spatial (Fig.3) eddy currents, transient (Fig.4) and spatial (Fig.5) eddy fields and 3D field responses (Fig.6) are given here. This approach can be easily implemented for cylindrical gradient coils. Ref. [1] W T Scott, The phys elect & mag, 1959. [21] H Gotoh et al, Nucl. Inst. Meth. 96 (1971) 485-486.
