氢原子钟双选态束光学系统仿真分析  

Simulation analysis of hydrogen atomic clock double state-selection beam optical system

作　　者：梁悦 谢勇辉[1] 陈鹏飞[1] 帅涛 裴雨贤[1] 徐昊天 赵阳[1] 夏天 潘晓燕[1] 张朋军 林传富[1] Liang Yue;Xie Yong-Hui;Chen Peng-Fei;Shuai Tao;Pei Yu-Xian;Xu Hao-Tian;Zhao Yang;Xia Tian;Pan Xiao-Yan;Zhang Peng-Jun;Lin Chuan-Fu(Shanghai Astronomical Observatory,Chinese Academy of Science,Shanghai 200030,China;University of Chinese Academy of Science,Beijing 100049,China)

机构地区：[1]中国科学院上海天文台,上海200030 [2]中国科学院大学,北京100049

出　　处：《物理学报》2023年第1期95-104,共10页Acta Physica Sinica

基　　金：中国科学院(批准号:E1830510)资助的课题。

摘　　要：氢原子钟利用氢原子基态超精细能级跃迁信号进行精确计时,具有中短期频率稳定度优异、频率漂移率低的特点.氢原子钟需要通过磁选态将高能态原子选出,目前广泛应用的磁选态方案中,既有原子钟跃迁所需要的|F=1,m_(F)=0>态,还有钟跃迁所不需要的|F=1,m_(F)=1>态氢原子,这使得氢原子钟的中长期频率稳定性难以进一步提高.为了进一步提高氢原子钟原子跃迁谱线质量和整机性能,通过计算和仿真,构建了基于Majorana跃迁的氢原子钟双选态束光学系统,优化了一级选态区、态反转区、二级选态区等关键部件的参数,进一步排除了|F=1,m_(F)=1>态原子.选态后的|F=1,m_(F)=0>态原子纯度达到99%,利用率为58%,工程应用较为理想.有效地提升了进入原子储存泡内|F=1,m_(F)=0>态氢原子的占比,同时原子的利用率处于可控范围.通过实验对该方案的有效性进行了验证,通过开启双选态系统,可以观察到氢原子钟信号的增强;通过调整双选态系统的线圈电流,可以观察到信号随线圈电流的变化,这验证了双选态系统的有效性.Hydrogen maser uses the transition frequency of hydrogen atom at hyperfine energy level of ground state to realize precise timing.It has excellent frequency stability,especially in medium-and short-term,and low frequency drift.It has been used as high-precision frequency standard in engineering fields such as time keeping,navigation,and very long baseline interferometry.Clock transition of hydrogen maser is the transition between states of|F=1,m_(F)=0>and|F=0,m_(F)=0>.State selection is realized by state selection magnet,through which high energy atoms are converged and low energy atoms are dispersed.In conventional magnet stateselecting system,both atoms of|F=1,m_(F)=0>states,which are required for the maser transition,and useless atoms of|F=1,m_(F)=1>states are focused into storage bulb,which places restrictions on the medium-and long-term frequency stability performance of hydrogen maser.In order to further improve the quality of atomic transition spectral lines and the performance of hydrogen maser,double state-selection beam optical system which is based on the Majorana transition mode is constructed through calculations and simulations.In this work,we use Majorana method to invert atomic states.The magnetic field required for Majorana transition is established by using two coils with reverse current.The two coils are separated by 71 mm,and the coil axes are aligned with the direction of atomic beam.The other two pairs of transverse Helmholtz coils are separated by 22 mm in the center of the state reversal to adjust the zero point of magnetic field,which should coincide with the atomic beam to ensure a complete reversal of atomic polarity.The state reversal region is surrounded by four magnetic shields to reduce the influence of stray magnetic fields.Relationship between selected-state magnetic field gradient and distance of magnetic poles is analyzed by simulation,and trajectories of the atoms with high and low energy under different selected-state magnetic fields are calculated.The utilization and purity o

关 键 词：氢原子钟 双选态 束光学系统 

分 类 号：TM935.115[电气工程—电力电子与电力传动]