一种用于氪原子的环形永磁体塞曼减速器
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摘要
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。
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 than20 mm from the maximum initial value of 250 m/s to the final value of 50 m/s.
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 than20 mm from the maximum initial value of 250 m/s to the final value of 50 m/s.
引文
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[9] Lu Z T, Schlosser P, Jr W S, et al. Tracer applications of noble gas radionuclides in the geosciences[J]. Earth-Science Reviews, 2014, 138:196-214.
[10] Metcalf H J, Peter Van Der Straten. Laser Cooling and Trapping[M]. Switzerland:Springer, 1999.
[11] Lu Xuanhui, Wang Jiangfeng. Quantum gyroscope based on an atom interferometer[J]. Infrared and Laser Engineering,2007, 36(3):293-295.(in Chinese)陆璇辉,王将峰.基于原子干涉的量子陀螺仪[J].红外与激光工程, 2007, 36(3):293-295.
[12] Wang Zhanshan, Ma Shanshan, Ma Yan, et al. Knife-edge technique for laser cooling[J]. Optics and Precision Engineering, 2006, 14(1):63-69.(in Chinese)王占山,马珊珊,马艳,等.刀口技术在激光冷却中的应用[J].光学精密工程, 2006, 14(1):63-69.
[13] Hill I R, Ovchinnikov Y B, Elizabeth M B, et al. A simple,configurable, permanent magnet Zeeman Slower for Sr[C]//Conference:European Frequency and Time Forum(EFTF),2012:545-549.
[14] Hill I R, Ovchinnikov Y B, Elizabeth M B, et al. Zeeman slowers for Strontium based on permanent magnets[J].Physics, 2014, 47(7):1216-1221.
[15] Zhang Xiaohang, Xu Xinye. Development of adjustable permanent magnet Zeeman slowers for optical lattice clocks[J]. Chinese Physics B, 2017, 26(5):102-107.
[16] Zhang Xiaohang, Xu Xinye. Optimized design of a permanent Zeeman slower for an Ytterbium optical lattice clock[J]. Laser Physics, 2016, 26(7):075501.
[17] Krzyzewski S P, Akin T G, Dahal P, et al. A clip-on zeeman slower using toroidal permanent magnets[J]. Review of Scientific Instruments, 2014, 85(10):103104.
[2] Zhang Yan, Zhang Xiaohang, Zhang Yu, et al. Generation and modulation of high efficiency stationary optical signals in cold87Rb atomic samples[J]. Chinese Optics, 2012, 5(2):143-147.(in Chinese)张岩,张晓航,张宇,等.冷铷原子样品中高效静态光信号的生成与调制[J].中国光学, 2012, 5(2):143-147.
[3] Fan Pengge, Wu Yiming, Jia Sen, et al. Optimization design of two dimensional magneto optical trap field[J]. Infrared and Laser Engineering, 2016, 45(6):0618003.(in Chinese)樊鹏格,吴易明,贾森,等.冷原子干涉仪中二维磁光阱线圈的优化设计[J].红外与激光工程, 2016, 45(6):0618003.
[4] Guo Xiuzhen, Hou Lixin, Yin Zhaotai, et al. All-optical routing control based on coherently induced high reflection band and high trensmission band in a medium of cold atoms[J]. Chinese Optics, 2011, 4(4):355-362.(in Chinese)国秀珍,侯丽新,尹昭泰,等.冷铷原子介质中基于相干诱导高反射带和高透射带的全光路由控制[J].中国光学,2011, 4(4):355-362.
[5] Ren Jie, Liu Hui, Lu Benquan, et al. Program control in transition observation of Strontium optical lattice clock[J].Optics and Precision Engineering, 2016, 24(1):50-58.(in Chinese)任洁,刘辉,卢本全,等.锶原子光钟钟跃迁谱线探测中的程序控制[J].光学精密工程, 2016, 24(1):50-58.
[6] Yang Guomin, Tong Amin, Dong Xize, et al. Dating and tracing groundwater and ice with81Kr and85Kr[C]//19th EGU General Assembly, EGU2017, 2017, 11467:23-28.
[7] Chen C Y, Li Y M, Bailey K, et al. Ultrasensitive isotope trace analyses with a Magneto-Optical trap[J]. Science,1999, 286(5442):1139-1141.
[8] Li Jie, Pang Zhonghe, Yang Guomin, et al. Million-year-old groundwater revealed by krypton-81 dating in Guanzhong Basin, China[J]. Science Bulletin, 2017(17):1181-1184.
[9] Lu Z T, Schlosser P, Jr W S, et al. Tracer applications of noble gas radionuclides in the geosciences[J]. Earth-Science Reviews, 2014, 138:196-214.
[10] Metcalf H J, Peter Van Der Straten. Laser Cooling and Trapping[M]. Switzerland:Springer, 1999.
[11] Lu Xuanhui, Wang Jiangfeng. Quantum gyroscope based on an atom interferometer[J]. Infrared and Laser Engineering,2007, 36(3):293-295.(in Chinese)陆璇辉,王将峰.基于原子干涉的量子陀螺仪[J].红外与激光工程, 2007, 36(3):293-295.
[12] Wang Zhanshan, Ma Shanshan, Ma Yan, et al. Knife-edge technique for laser cooling[J]. Optics and Precision Engineering, 2006, 14(1):63-69.(in Chinese)王占山,马珊珊,马艳,等.刀口技术在激光冷却中的应用[J].光学精密工程, 2006, 14(1):63-69.
[13] Hill I R, Ovchinnikov Y B, Elizabeth M B, et al. A simple,configurable, permanent magnet Zeeman Slower for Sr[C]//Conference:European Frequency and Time Forum(EFTF),2012:545-549.
[14] Hill I R, Ovchinnikov Y B, Elizabeth M B, et al. Zeeman slowers for Strontium based on permanent magnets[J].Physics, 2014, 47(7):1216-1221.
[15] Zhang Xiaohang, Xu Xinye. Development of adjustable permanent magnet Zeeman slowers for optical lattice clocks[J]. Chinese Physics B, 2017, 26(5):102-107.
[16] Zhang Xiaohang, Xu Xinye. Optimized design of a permanent Zeeman slower for an Ytterbium optical lattice clock[J]. Laser Physics, 2016, 26(7):075501.
[17] Krzyzewski S P, Akin T G, Dahal P, et al. A clip-on zeeman slower using toroidal permanent magnets[J]. Review of Scientific Instruments, 2014, 85(10):103104.