低温环境下的汞离子囚禁实验研究

The iontrap is one of the ideal systems to achieve the frequency standard. However, the ion in the trap is still influenced by the environment. In low temperature environment, the collision between the trapped ion and the background gas is suppressed and the ion can stay longer in the trap. The influence of the transition frequency which is caused by the background radiation is also greatly reduced in low temperature environment. And it is, therefore, necessary to do some researches on trapping the ion in that situation. The research is carried out by means of immersing the trap in the liquid helium in National Institute of Standards and Technology (NIST). In this project, the research will be developed as follows. The mercury ion is supposed to be trapped in a ring trap. And the environment is going to be cooled using a compression refrigerator. Then the ion-trapping experiment will be developed in low temperature environment and the frequency shift caused by the blackbody radiation from the environment will be studied.

离子阱是实现频标的理想体系之一，但离子阱中的离子还是会受到外界环境的影响。低温环境能够减小阱中囚禁的离子与背景气体的碰撞，提高离子的囚禁时间，并能大幅度减小环境的黑体辐射对离子跃迁谱线的影响。因而有必要对低温环境下离子阱中的离子囚禁进行研究。目前美国国家标准与技术研究院（NIST）通过将离子阱放入液氦中进行低温环境下的离子囚禁实验。本项目计划使用环形离子阱囚禁汞离子，利用压缩制冷机对离子的周围环境进行冷却，开展低温环境下的汞离子囚禁实验，并在此基础上对环境的黑体辐射引起的频率移动进行研究。

低温环境能够减小阱中囚禁的离子与背景气体的碰撞，提高离子的囚禁时间，并能大幅度减小环境的黑体辐射对离子跃迁谱线的影响。本项目对离子阱中的离子囚禁以及低温环境的制备进行了研究。.本项目的主要研究成果，包括研制成实验所需的汞离子194nm冷却激光并对相关的倍频与和频技术进行了深入研究；初步研制成282nm窄线宽激光；设计和制作离子阱系统，成功俘获汞离子；利用压缩制冷机建立冷却系统，能有效降低离子阱附近的环境温度。194nm深紫外连续激光的产生，国际上依旧是一个难题。能够突破该技术，不仅对汞离子精密测量的研究有很大的助力，而且有助于推动深紫外连续激光产生及相关研究的开展。实现离子阱中的汞离子的俘获和信号探测，是基于汞离子的精密测量研究的重要一环。实现汞离子的俘获和信号探测，标志着研究小组初步具备了囚禁离子的相关实验的研究能力。