Development of an Opt ically - pumped Cesium Standard at the Aerospace Corporation

We have initiated a research program to study the perjonnance of compuct optically-pumped cesium (Cs) frequency standards, which have potential for future timekeeping upplicutions in space. A Cs beam clock apparatus has been assembled. Basic functions of thefrequency standard have been demonstrated. Clocksignals are observed with opticalpumping schemes using one or two h e r s . With two-luserpumping, we are able to selectively place up to 80% of the atomic popuhion into one of the clock transition states. The observedpattern of the microwave clock signal indicates that the velocity distribution of the Cs atomv contributing to the microwave signal is beam-Muxwellian. Thus, in the optically-pumped 17s frequenqv stundurds, the entire Cs population in the atomic beam could be utilized to generate the clock signals. This k in contrast to the conventional Cs beam standards where only ~ 1 % of the atoms in the beam are used. More eficient Cs consumption can lead to improved reliability and increased useful lifetime of the clock. Our preliminary results are summarized in this paper: