Controlling the Microwave Power in Optically Pumped Cesium Beam Frequency Standard

Abstract

Microwave power is an important factor on the long-term stability of the cesium beam (OPCB) frequency standard. In this paper, we present a new linewidth locking method to control the microwave power in OPCB frequency standards in theory. The responses of OPCB tubes and classical magnetic state selection cesium beam (MSCB) tubes are analyzed and compared against the power of the microwave field. Because of the wide probability distribution of atomic velocity resulting from the optical state preparation and detection, the linewidth of the Ramsey pattern is sensitive to the microwave power. This result can be used to control the microwave power instead of the traditional extremum method. When the microwave power is well controlled at a low level using the linewidth locking method, the ultimate stability of cesium beam clocks can be improved to a certain degree for the reduction of the Ramsey pattern linewidth.