Design of Self-Shielded Uniform Magnetic Field Coil via Modified Pigeon-Inspired Optimization in Miniature Atomic Sensors

This article presents a modified pigeon-inspired optimization method for designing self-shielded uniform magnetic field coils that offers an innovation in miniature atomic sensors. The proposed coil system consists of circular coil pairs distributed on two coaxial cylinder surfaces, which can provide a highly uniform magnetic field at the coil center and rapidly attenuate the external field. This design is transformed into a nonlinear objective optimization problem with constraints, so that the coil geometric parameters can be obtained by the proposed algorithm, instead of solving closed-form equations by pure numerical method. Parallel competition and hierarchical search strategy are firstly introduced to accelerate the convergence speed and avoid falling into the local optimal value. Comparative experiments of several algorithms demonstrate the accuracy, effectiveness, convergence stability of the proposed method. Compared with traditional design methods, this method can automatically find the optimal parameters of the coil according to any constraints. Theoretical contrast shows that compared with the Lee-Whiting coil, the uniformity of proposed coil is improved by about 2 to 3 orders of magnitude and has a significant self-shielded effect. This work is beneficial to the miniaturization of atomic sensors.