多极阱中汞离子数密度分布对二阶多普勒频移的影响

Effect of mercury ion number density distribution in multipole trap on second-order Doppler shift

汞离子钟因其独特的优势,有望成为未来深空探测和下一代全球导航系统的核心装备。离子阱中离子云的性质,对汞离子钟的性能指标有重要影响。在绝热近似条件下,基于多极阱中离子数密度的径向分布模型,采用经典四阶龙格-库塔数值计算方法,从阱电极数和离子数的角度出发,分析了离子阱区内囚禁电势的组成及其分布,阐述了多极阱中汞离子云变化规律的物理机制,讨论了多极阱内的空间电荷效应以及二阶多普勒频移变化的成因,并同四极阱作了相应的比对研究。在此基础上提出了一些抑制空间电荷效应影响,减小二阶多普勒频移的建议。该项工作进一步深化了多极阱囚禁离子的技术研究,有助于提升离子钟的设计能力。

With the development of quantum frequency st andard technology,mercury ion clock is expected to become the core equipment of deep space exploration and next generation GNSS because of its unique advantages.Ion cloud in an ion tarp is very important to the performance of the mercury ion clock.Based on the model of ion number density distribution along the radial direction in a multipole trap and the classical fourth-order Runge K utta method,the composition and distri bution of trapping potential in the ion trap region are analyzed by changing the electrode number and ion number,the physical mechanism of mercury ion variation in the multipole traps is expounded,and the space charge effect and the cause of second-order Doppler shift are discussed.The results are compared with those of the quadruple trap.On this basis,some suggestions are given to suppress the influence of space charge effect and reduce the second.-order Doppler shift,This work further deepens the technical research of ion trapping in multipole trap and helps to improve the design ability of ion clocks.