The role of long term lamp fluctuations in the random walk of frequency behavior of the rubidium frequency standard: A case study

A long term frequency stability test performed on an EG&G prototype Rb atomic frequency standard revealed excellent performance for an Rb atomic clock. Also, some classic Rb clock behaviors were observed, namely, long term frequency drift, spontaneous frequency jumps and random walk of frequency noise for long averaging times. A careful analysis of the complete test record disclosed that the spontaneous frequency jumps and the random walk of frequency noise can be attributed to the behavior of the clock's discharge lamp. The long term frequency drift, however, was found not to be primarily lamp-related. Although results of only a single test on a single Rb clock are reported here, we believe that the results are applicable to Rb clock technology as a whole.