铷钟原子气室氦气渗透率实验研究

Study on Helium Permeation in Rubidium Clock’s Vapor Cell

氦气向铷气室内渗透被认为是导致铷钟频率漂移的原因之一.在本研究中,我们对铷钟普遍使用的Pyrex材料铷原子气室和研制的抗氦渗透能力强的铝硅材料铷原子气室的多个样本进行了氦渗透率测量,在工作温度(约60℃)下渗透率分别为2E-19 m^(2)/(Pa·s)和≤3E-22 m^(2)/(Pa·s).据此结果对铷钟频率漂移率进行分析表明,采用Pyrex玻璃气室时,氦气渗透引入的铷钟频率漂移在前4年内稳定在E-13/天水平,之后6年的影响大约在E-14/天水平;若采用铝硅玻璃(ASG)气室,氦气渗透引入的铷钟频率漂移可降低至E-16/天水平.该研究结果对改善铷钟的长期频率漂移问题具有指导意义.

Vapor cell’s helium permeation is considered to be one of the reasons for the frequency drift of rubidium(Rb)clocks.In this study,we measured the helium permeability for both commonly used Pyrex Rb cell and newly developed antihelium aluminosilicate Rb cell.Their helium permeabilities at operating temperatures(~60℃)are 2E-19 m^(2)/(Pa·s)and≤3E-22 m^(2)/(Pa·s),respectively.The analysis shows that the Pyrex Rb cells causes clock drift from helium permeation to be about E-13/day in the first four years and E-14/day in the next six years,and the aluminosilicate Rb cell can suppress the drift from helium permeation to E-16/day.The results are instructive for improving Rb clock’s long-term frequency drift performance.