Keele Research Repository

In this thesis, the principle, construction and operation of an ammonia beam maser oscillator of advanced design are described.
The maser discussed is characterized by the production of an intense molecular beam with a nozzle-skimmer gas source combination. This system has permitted a particularly strong oscillation to be obtained which has led to the observation of several novel phenomena associated with non-linearities of the maser. These include strong oscillation pulsations on the four quadrupole satellite lines of the J=K=3 inversion transition of 14NHj. In addition, oscillation settling transients and various complex oscillation amplitude pulsation phenomena in both single and two-cavity maser systems are reported and discussed.
Other characteristics are also described, including two- cavity maser operation with the second cavity either as a molecular beam polarization detector or as a spectrometer cavity. In the former case, cavity detuning phenomena are examined and in the latter, multiple population inversion is investigated.
Furthermore, continuous oscillation with several inversion lines of 14NH3 including J=K=3; J=3, K=2 and J=K=2 are obtained without cryogenic pumping or time limit.
Some of these results have already been published and reprints of the papers may be found at the end of the thesis.