Active H-maser with increased power of the output signal

To improve short-time stability the amplification of the hydrogen maser output signal due to using the single-state selection and cooling the source cell is theoretically discussed. H-maser theory basic aspects are sequentially developed in the introduction part. The results of the numerical calculation active H-maser power versus magnet parameters of specific selective system and source temperature are obtained. In conclusion, the theoretic prototype of maser, that has a short-time stability achieved 2.5×10^-14 for one second, is represented.