Development of passive hydrogen maser in Shanghai Astronomical Observatory

Study of passive hydrogen maser in Shanghai Astronomical Observatory is introduced. New type of passive hydrogen maser with high performance has been developed. It has unique features such as novel kind of electrode cavity with high Q factor (loaded-cavity Q factor up to 10000) and new frequency control scheme of electronics package, with the help of novel cavity-bulb assembly, quadrupole state selector, nickel purifier, new dissociator and four layer magnetic shield, the atomic signal gain of physics package is up to 3dB at -80dBm microwave signal input. Several passive hydrogen maser prototypes have been developed. Preliminary performance test yields the frequency stability better than 1×10-12τ-1/2(1s≤τ≤10000s) and 1×10-14 @1day.