Dynamic properties of an ammonia maser incorporating a disc resonator

The oscillation properties of an ammonia maser employing dual molecular beams and a Fabry-Perot type disc resonator are investigated. The molecular beam flux is pulsed by the use of small fuel injection valves. The resulting gas pulses entering the maser resonator allow for the rapid build-up of maser oscillation sufficient to induce oscillation amplitude settling transients. The amplitude and polarization of these transients are investigated, and their modification under applied magnetic and electric fields is interpreted. Previous results of settling transients are also re-examined. With an applied magnetic field a novel damped low frequency beating effect is observed following the onset of the pulsed maser oscillation. This is interpreted in terms of the beating of two elliptically polarized oscillations. The gas pulses entering the resonant cavity are sufficiently Intense to allow for pulsed maser oscillation on the J«K>4 and transitions of at 24.139 and 25.056 GHz respectively. These are the first reported maser oscillations on these transitions. The polarization properties of the disc resonator are investigated by the observation of the oscillation polarization ellipse originating within the maser cavity. A method is developed to study the time evolution of the oscillation polarization ellipse, following the opening of the fuel injector valve. The build-up of ellipses under conditions of both single and biharmonic oscillation are studied. The experiments are performed both with and without an applied magnetic field and under conditions of modified cavity anisotropy. A particular feature is the random quality in the evolution of successive oscillation pulses which suggests that the build-up in maser oscillation may be chaotic in nature