Research On Cesium Fountain Clock System Optimization

Time and frequency measurement plays an important role in national defence andeconomy development. Cesium atomic fountain clock, with the highest accuracyperformance, is the current time and frequency primary standard. It is applied widely intime-keeping system, the field of metrology, fundamental physics research areas. Withthe development of science and technology, the optimization of the cesium atomicfountain clock becomes more and more urgent.The NIM5cesium fountain clock has been operating stably and sub-continually asthe primary frequency standard of China’s National Institute of Metrology (NIM) since2008. In addition, NIM are developing a new Cs fountain frequency standard NIM6, andshooting for the frequency uncertainty of a few parts in1016.This paper is base on NIM5and NIM6. Some works for the optimization of the cesium atomic fountain clock wereintroduced. The specific studies are as follows:(1) According to the requirement of the NIM6optical system, a control system ofthe laser in NIM6was designed. A programmable pulse signal generator was designed forcontrolling laser frequency and power. Tests proved that the signal generator can satisfycompletely the requirements of laser control.(2) The request of the NIM6sequence control and data acquisition system wasanalyzed in details. The hardware of the control system was selected and the controlsoftware based on LabVIEW was developed. Tests indicated that the software is steady,reliable, ease for use and the system can meet the control requirements.(3) The triggered-phase transient analyzer was developed to measure the phasetransient of Mach-Zehnder interferometric switch which was used to reduce themicrowave leakage. The results showed that some kinds of thermal effect existed in ourinterferometric switch. From the result of the phase discontinuity between two switchingon state in one fountain’s cycle, the frequency uncertainty induced by the interferometricswitch is1.2×1015.