TF-4000 A, TFL´s high performance ruggedized rubidium frequency standard

A progress report is given on the development of TFL´s rubidium frequency standard, RF-4000A. Highlighted are short-term-stability (5×10^-12/√τ), low temperature sensitivity (1×10^-10/-55°C to +71°C) and low magnetic sensitivity (<1×10^-12/G) obtained with an AC C -field method. These are analyzed and discussed within a framework of models are presented. Preliminary results of a study relating to the application of the AC C-field are presented. Transient signals are observed at the zero crossing of the C-field. These are related to adiabatic and nonadiabatic processes that occur at a low and changing magnetic field