Design and performance of a small cesium tube

Abstract

AbstractThe introduction of cesium oscillators as standard clocks in communication networks of the future is expected. It is known that the frequency stability and life of a cesium oscillator mainly depends on the cesium beam tube employed. This paper describes a design method of a cesium tube considering the short‐term frequency stability ± y(T) of the oscillator. The main factors controlling the S/N ratio of the cesium beam tube are considered. Using the figure of merit relating to ± y(T), a method is presented for optimizing the basic parameters (signal current, beam current and half‐amplitude frequency) relating to the Ramsay resonance signal. If the ratio of the beam current to the signal current is constant in the atomic beam tube without an electron multiplier, it is possible to obtain the same S/N ratio as in the conventional cesium‐beam tube with an electron multiplier by increasing the beam current. The figure of merit can be increased by increasing the signal current even if the half‐amplitude frequency is wide. Analysis of the operation of a small atomic beam tube is carried out to determine the optimum arrangement of components in the tube. It is confirmed by manufacturing a prototype beam tube that the figure of merit of 0.64 can be obtained as predicted.