Pressure and Temperature Coefficients of the More Commonly Used Buffer Gases in Rubidium Vapor Frequency Standards

The temperature and pressure coefficients of three buffer gases, N2, Ar, Kr, commonly used in passive Rb57 frequency standards have been accurately determined. Techniques for filling cells reproducibly, are described. From the results obtained, calculations are made on the expected characteristics of gas mixtures. Graphs are given which can be used to select the proper buffer gas mixture and pressure to obtain specially required frequency shift and temperature coefficient in a given cell.