Keele Research Repository

The construction of a double beam ammonia maser employing an open resonator of advanced design is described. The operation of this maser as an oscillator permitted a strong oscillation to be obtained which has led to the observation of several novel phenomena, These include a biharmonic effect with a beat frequency of a few kilohertz which has remained as an unsolved problem since the original observations in 1964; injection priming of a pulsed ammonia-beam maser oscillator and oscillation of the weak ammonia inversion line J=K=1. Also the operation of the maser as a spectrometer has permitted a study,of the weak field Stark effect and a beating of beats phenomenon by operation of the cavity in the TEM 101 mode. Other experimental work of a general nature is also described, including a comparison between effuser-diaphragra and nozzle-skimmer combinations and the oscillation amplitude characteristics of the inversion lines of ammonia J=K*1,2,3 with TEM001 and TEM101 open cavity modes.