一种用于氪原子的环形永磁体塞曼减速器

基于激光冷却与囚禁原理的原子阱痕量分析技术，可以对氪的放射性同位素进行高灵敏度检测，在地球物理与环境科学领域具有广泛应用。塞曼减速器可用于产生连续低速的原子束流，是原子阱痕量分析系统中的关键部件之一。采用永磁体设计的塞曼减速器组装和调试方便，磁场强度稳定，且不需要恒流电源和冷却装置，因此获得了越来越多的关注和研究。文中基于环形永磁体设计了一种用于氪原子的塞曼减速器，通过有限元分析得到了减速器磁场的空间分布，根据设计参数制造了环形永磁体塞曼减速器，测量了轴线上的磁场分布。减速器长度51.2 cm，有效减速区域长度46.9 cm，实测磁场与理论减速磁场最大偏差小于3.6 G，平均偏差1.3 G。进一步模拟了原子束流在设计磁场和实测磁场下的减速过程，并分析了磁场的径向变化对于原子束流减速的影响规律，结果表明:当原子束流直径小于20 mm时，该塞曼减速器可将初速度最大为250 m/s的氪原子减速至50 m/s。

A toroidal permanent magnet Zeeman slower for Krypton

Atom Trap Trace Analysis(ATTA) technology, which is based on the theory of laser cooling and trapping, has the capability of high-sensitivity detection of the radioactive isotope of Krypton and wide applications in the fields of geophysics and environmental science. Zeeman slower, as a key component of the ATTA instrument, is used to generate continuous atomic beam with low velocity. With the advantages of stable magnetic distribution, easy installment and debugging, no constant current power or cooling requirement, the Zeeman slower based on permanent magnet is getting more and more attention in recent years. In this paper, a Zeeman slower based on the toroidal permanent magnet was designed, the spatial distribution of the magnetic field of this slower was calculated by finite element analysis, a prototype was manufactured according to the design parameters, and its magnetic field along the axis was also measured. The lengths of the slower and its effective deceleration area were 51.2 cm and 46.9 cm, separately. The maximum deviation between the measured and theoretical magnetic field was less than 3.6 G, and the average deviation was 1.3 G. Furthermore, the deceleration process of the atomic beam in the designed and actual magnetic field distribution was simulated, and the influence of the radial variation of magnetic field distribution on the deceleration process of the atomic beam was analyzed. The result shows that the Zeeman slower in this paper is able to decelerate the velocity of the atomic beam with a diameter less than 20 mm from the maximum initial value of 250 m/s to the final value of 50 m/s.