铯原子喷泉钟频移的自动评定系统研究

Research on automatic assessment system for frequency shift of cesium fountain clock

'秒'定义频率9 192 631 770 Hz是理想值,在实际工作过程中,铯原子喷泉钟在外部环境(如引力场、电磁场等)、内部原子相互作用(如碰撞)下,原子样品的跃迁频率偏离了定义值,这些偏离量称为'频移'。为了获得被测原子钟信号和秒定义频率之间的偏差,需要测量所有频移量,并且给出其频率不确定度。介绍了频移自动评定系统的设计和实现,考虑了各项频移的运行周期和切换间隔,实时给出二阶塞曼频移、冷原子碰撞频移和黑体辐射频移的纠正量,计算分析获得了频移量的系统不确定度。

The definition of the second is realized by cesium atomic clock.In practice,the transition frequencies of cesium fountain clock deviates from the defined values under the external environment(such as gravitational field,electromagnetic field,etc.)and the internal atomic interaction(such as collision),these deviations are called frequency shift.In order to measure the frequency difference between atomic clock signal and the'second'defined,the frequency shifts with uncertainty need to be evaluated.The design of automatic evaluation system of cesium fountain clock is presented in details.Frequency shifts are corrected for the following four effects:second-order Zeeman shift,blackbody radiation shift,cold collisions shift and gravitational shift.