ammonia maser crop.jpg (45349 bytes)An extensive programme of research work was carried out to produce highly monochromatic stimulated emission at microwave frequencies. A beam of ammonia molecules was first passed through a charged enclosure and then through a microwave resonant cavity. The output power from the microwave stimulated emission was measured to evaluate its use as a frequency standard.  Two ammonia maser assemblies were constructed at SRDE to compare the stability of the frequency over a period of time.