The prediction of the optimum noise performance of a reflection cavity maser

Maser performance depends on the microwave circuit, on the total concentration of paramagnetic centres in the energy states used in the crystal and on the degree of inversion of population differences which can be obtained by pumping. At any temperature there will be an optimum concentration for maximum performance and to determine this optimum a knowledge is needed of certain parameters. Although some of these are difficult to measure directly a method is suggested which enables an adequate determination to be made.