New Research Progress in Active Hydrogen Maser in BIRMM

The active hydrogen maser is a core piece of equipment for the time-frequency system. Its stability and reliability directly influence system performance. The optimization of temperature coefficients for physical and circuit systems provides a direct means to further improve performance of active hydrogen masers. Based on the existing sapphire active hydrogen maser, the microwave cavity, magnetic shield, and other components of its physical package have been optimally designed, resulting in new dielectric-loaded cavity and full-size cavity, with a temperature coefficient of −10 kHz/℃ and −1 kHz/℃, respectively. Taking into account the two newly designed cavities, we have achieved active hydrogen masers with volume in completely two different directions. The hydrogen maser with a dielectric-loaded cavity achieved a stability of 2.1E-13/1s and 2.3E-15/d, and that with a full-size cavity achieved a stability of 1.5E-13/1s and 1.6E-15/d when cavity servo system was not installed. The physical package of the active hydrogen maser with a dielectric-loaded cavity can achieve a size of Φ220 mm × 500 mm, and this technical solution is the best choice for space applications.