铯原子喷泉钟空间均匀C场的研究  

Study on C field's spatial uniformity for cesium fountain clock

作　　者：施俊如 王心亮[1,2] 阮军[1,2] 管勇[1,2,3] 白杨 刘浩 杨帆[1,2,3] 刘丹丹 张辉[1,2] 张首刚[1,2] SHI Jun-ru;WANG Xin-liang;RUAN Jun;GUAN Yong;BAI Yang;LIU Hao;YANG Fan;LIU Dan-dan;ZHANG Hui;ZHANG Shou-gang(National Time Service Center,Chinese Academy of Sciences,Xi＇an 710600,China;Key Laboratory of Time and Frequency Primary Standards,Chinese Academy of Sciences,Xi＇an 710600,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院国家授时中心,西安710600 [2]中国科学院时间频率基准重点实验室,西安710600 [3]中国科学院大学,北京100049

出　　处：《时间频率学报》2018年第3期145-150,共6页Journal of Time and Frequency

基　　金：国家自然科学基金资助项目(61127901)

摘　　要：二阶塞曼频移是影响铯原子喷泉钟频率不确定度性能的系统项之一,而二阶塞曼频移的不确定度由C场均匀度决定。C场均匀度又与C场强度随时间的变化情况(时间稳定性)和C场强度沿原子飞行路径的变化情况(空间均匀性)有关。均匀C场的实现有两种途径:一是磁屏蔽的屏蔽效果好且无剩磁;二是在磁屏蔽两端加补偿线圈,但是补偿线圈会引入电噪声而降低C场的时间稳定性。首先理论研究了由C场引起的二阶塞曼频移,和由C场空间均匀度引起的二阶塞曼频移不确定度。实验上通过改进退磁方法对磁屏蔽进行了整体退磁,得到了无补偿情况下空间均匀度良好的剩磁47cm@1nT,和C场48cm@1.5nT。最后计算得到二阶塞曼频移为68.7×10^(-15),由C场空间均匀度引起的二阶塞曼频移不确定度为6.05×10^(-19)。The uniformity of C field determines the second-order Zeeman frequency shift, which is the major physical factor that influences the frequency uncertainty of the cesium atomic fountain clock. And C field＇s uniformity relates to time stability and spatial uniformity along the atom trajectory. There＇re two ways to implement a uniform C field.the magnetic shielding has no residual magnetism with high quality; add compensation coils to both ends of the magnetic shielding, but it may introduce electrical noise and reduce time stability. In this paper,we theoretically studied second-order Zeeman frequency shift caused by C field and second-order Zeeman frequency shift＇s uncertainty caused by C field special uniformity firstly. In experiment, by demagnetizing the magnetic shielding integrally, we obtained a fairly uniform residual magnetism which fluctuates less than 1 nT in 47 cm, and C field fluctuates less than 1. 5 nT in 48 cm without compensation. Finally,we calculated and analyzed the results, the second-order Zeeman frequency shift is 68.7×10^-15 ,and the second-order Zeeman frequency shift＇s uncertainty caused by C field spatial uniformity is 6.05 ×10-19.

关 键 词：C场 剩磁 磁屏蔽 退磁 空间均匀度 

分 类 号：TM935.115[电气工程—电力电子与电力传动] P127.1[天文地球—天体测量]