Simulation and Parameter Optimization of Two-Dimensional SQUID Gradiometer

This study utilized Finite Element Analysis (FEA) to establish a time-domain simulation model for the design and evaluation of gradiometers. The simulation model was developed for an innovative two-dimensional (2D) gradiometer structure, specifically designed to connect to the Superconducting QUantum Interference Device (SQUID) for the measurement of magnetocardiographic signals (MCG). The experiment focused on optimizing the horizontal distance of the 2D gradiometer using the simulation model, conducting simulations under shielded and unshielded conditions to measure MCG signals. Simulation results indicated that the optimal performance of the 2D gradiometer is achieved when the horizontal distance is 2.22 times the diameter of the detection coil. Subsequent research simulated the geomagnetic field in shielded and unshielded environments, introducing a second-order axial gradiometer for comparison. The analysis revealed that in the shielded environment, the 2D gradiometer exhibited a noise suppression ratio of approximately 40 dB and a signal restoration rate of 99.86%, while the second-order gradiometer achieved 59 dB and 99.71%, respectively. In the unshielded environment, the noise suppression ratio of the 2D gradiometer decreased to 33 dB, but both gradiometers maintained a signal recovery efficiency of around 99%. This study, employing simulation methods, comprehensively analyzed the temporal characteristics of the gradiometer, significantly enhancing design efficiency and reducing testing costs. It holds crucial guiding value for the development of gradiometers.