冷原子干涉仪中二维磁光阱线圈的优化设计

大通量冷原子源是实现高精度冷原子干涉仪的关键技术之一。为获得大通量冷原子源,通常采用二维磁光阱(2D-MOT)和三维磁光阱(3D-MOT)的级联结构,其中2D-MOT的磁场分布是影响其性能的重要因素。通过数学建模及有限元分析,对2D-MOT中不同构造(长方形、跑道形、马鞍形)的反亥姆霍兹线圈进行数值计算,分析了不同构造线圈的磁场分布及因在制造与装配过程中产生的偏心、线圈不对称、平行度及内径不对称误差造成的磁场零点漂移和磁场梯度变化。分析结果表明,在偏心误差C1.14 mm,线圈不对称误差I0.016 A,平行度误差1.02时,马鞍形线圈产生的磁场梯度更有利于制备大通量冷原子源。该结果为冷原子干涉仪2D-MOT的磁场系统设计和加工提供了理论指导。

Optimization design of two-dimensional magneto optical trap field coils for cold atom interferometer

High flux of cold atoms is one of the key technologies to realize high-precision cold atom interferometer. The approach of concatenation of two-dimensional Magnetic Optical Trap (2D-MOT) and three-dimensional Magnetic Optical Trap (3D-MOT) is generally used to obtain high flux of cold atoms. The magnetic field distribution of 2D-MOT is the key influencing factor in this appliance. In this paper, three different (rectangular, race-track and saddle) mathematical models of Anti-Helmholtz coils in 2D-MOT were established to analyze the magnetic field distribution. Then, the magnetic field zero drift and the change of magnetic field gradient caused by the error of eccentricity, coils asymmetry, parallelism and inside diameter asymmetry were analyzed, which were produced in the manufacture and installation process using finite element analysis. Results show that the magnetic field gradient provided by saddle coils is more conducive to produce high flux of cold atoms when eccentricity error is less than 1.14 mm, coils asymmetry error is less than 0.016 A and parallelism error is less than 1.02. This work may provide theoretical guidance for the design and fabrication of magnetic system of 2D-MOT of cold atom interferometer.