Optimal design of bi-planar heater with magnetic field self-suppression configuration based on multi-objective optimization

Abstract

As a crucial component, the vapor cell serves as the fundamental sensing element in various atomic sensors, and electric heating is typically required to enhance the density of alkali metal atoms. Due to the presence of driving current, electric heating can unavoidably introduce interfering magnetic fields, which affect the performance of atomic sensors. To suppress this magnetic field interference, the electric heater trace configuration must be designed to achieve the magnetic field self-suppression effect. However, previous studies have solely focused on the optimization design of a single-sided heater, which leads to the spatial magnetic field gradient and limited improvement of the self-suppression effect. Therefore, this study proposes an optimization design method for the bi-planar heater, and uses the combination optimization of two heater pieces with spatial symmetrical distribution. Using the multi-objective optimization algorithm, the structure parameters and current directions of the heater are optimized to achieve superior magnetic field suppression and reduce the vapor cell magnetic field gradient. Both finite element simulation and experimental results demonstrate that the proposed bi-planar heating configuration generates an average magnetic field of 0.06 nT/mA in the central region of the vapor cell, which is more than three times less than the previous single-sided optimal configuration and more than five times less than the bi-planar symmetrical use of the single-sided optimal configuration. The proposed approach is expected to enhance the performance of atomic magnetometers and other atomic sensors that are sensitive to magnetic fields.