Hydrogen Standard Work at Goddard Space Flight Center

Abstract

This paper reviews hydrogen standard work at GSFC during the past two years (January 1966 to April 1968. Research and development has been directed primarily toward the realization of field operable time and frequency standards based upon the atomic hydrogen maser. As a result, several improvements have been made in the performance characteristics, while the design simplicity, maintenance free life, and other features have been enhanced. Particular areas covered include experiments with thermal control, design of a large storage bulb -high line Q maser using an all metal cavity, more efficient state selection, improved RF dissociator design, and a new digital automatic cavity tuning system which requires only a good quartz crystal as the reference oscillator. A second hydrogen maser has been required for this purpose in the past. Prototype standards a r e under construction which embody the features described.

The atomic hydrogen maser oscillator

“…Technology for precise thermal control of masers has enabled production of masers with automatically tuned cavity resonators made of metal that have excellent long-term frequency stability. These masers [20] are equipped with elongated storage bulbs shaped to provide a large storage volume and a very efficient interaction between the atoms and the rf magnetic field.…”

The Active Hydrogen Maser: State of the Art and Forecast

“…The dependence of the degree of pulling of the cavity tuning upon the line Q makes possible a tuning of the cavity by spinexchange broadening. Actually, automatic tuning devices have been realized which rely directly on this phenomenon [ 12,[25][26][27]. In these devices, the line Q is altered in sequences.…”