Abstract：Atomic clocks with good long-term stability are very important for timekeeping systems. Due to its excellent long-term stability performance, the small cesium atomic fountain clock also has the advantages of high reliability, automation, miniaturization, and mobility. It has the potential to realize a mobile timekeeping in a vehicle-mounted form and can be used as a node clock in a timekeeping atomic clock group, ensuring accurate frequency signals and time signals. This article introduces the design and operation results of the small cesium atomic fountain clock NIM-TF3 developed by the National Institute of Metrology of China. The frequency stability of NIM-TF3 is 2.7×10-13@ 1 second and 5.3×10-15@ 1 day. NIM-TF3 adopts an integrated laser system and an integrated electronic control system, which can achieve long-term automatic continuous operation. It also integrates the developed small microwave frequency synthesizer with the physical system, which significantly reduces the system volume and enhances the overall stability. and reliability. We also evaluated the second-order Zeeman relative frequency shift caused by the uneven distribution of the C field to be 7.3×10-14, with an uncertainty of 0.2×10-15. The overall volume of NIM-TF3 is less than 0.7 m3 and has the potential to become a vehicle-mounted fountain clock.
2024, Vol. 45 
