Miniaturized rubidium clocks for space and industrial applications

This paper describes current developments of miniature rubidium clocks based upon a magnetron cavity performed by the Neuchatel Observatory. Two variants of clocks for ground and space applications, respectively, have been developed. A brief description of both magnetron-type cavity and physics package basic characteristics is presented. The short-term stability obtained is discussed and compared with the theoretical value. The use of this cavity resonator, surrounding the absorption cell gives a repeatable short-term stability of 3 to 6×10^-12×^-1/2 for both ground and space version. Other parameters like temperature coefficient and long term stability have been optimised and tested. Good performances have been obtained through a careful balance between the compensation of the light shift and the buffer gas shift effects. The two versions of the clocks are as follows: The small industrial version for commercial applications has a volume of 0.25 1 and a typical power consumption of 7 W. This version is now in production. 2. The space-borne RUSO is designed for various missions. This model is now fully developed and a series of 6 flight models will be fully manufactured and tested before the end of 1995