Hydrogen maser improvements and future applications

This paper will compare current Standards Corporation (STSC) performance with the theoretical performance limitations imposed by nature, and describe methods by which the ideal performance may be better achieved. Several systematic improvements in the electronics, such as the VCO, the receiver-synthesizer system and the cavity auto-tuner are feasible, and several physical design features may be improved with additional development. These improvements would better adapt the maser to newly emerging applications such as a more stable flywheel oscillator for laser pumped cesium standards, cesium fountains and trapped ion devices; and in addition they would result in a better master clock for time standard ensembles, or a better local oscillator for very long baseline interferometry (VLBI) or network ground station applications. The very rugged metal cavity and bulb assembly, the cavity auto-tuner, and the highly efficient state selector and hydrogen handling system unique to the Sigma Tau design could also be adapted to the needs of a spacecraft frequency standard.