An Experimental Study For The Miniature Passive Hydrogen Waser

Hydrogen maser is a high-performance atomic clock. Conventional active hydrogen masers are limited in some applications for their size and weight. Much work has been done in Shanghai Observatory to reduce the size and weight.Research on miniature passive hydrogen maser is given in this paper. At first we analize the theory on how to get the error signal and the frequecy lock loop used in the passive hydrogen maser. Then the electronic design is introduced.We use the square wave frequency modulation to get the error signal.10MHz crystal oscillator frequency is locked to the hydrogen emission.line. The narrow band filter and broad band filter are experimented.We use the cavity-auto-tuning in passive hygrogen maser. Resonant cavity frequency is locked to the crystal oscillator frequency.The electronic design is similar to the one for crystal oscillator lock loop but the parameters are different.Magnetron cavity and 4-pole state selector are used in passive hydrogen maser to reduce the size and weight. Other design in the physical part is similar to the one in the active.This passive hydrogen maser is 704mm high, 410mm wide, 526mm deep and weights 40kg. Preliminary measurements indicate some of the frequency stability are 1.1 × 10-11 for an averaging time T =1s and 6.4 × 10-13 for T =ld.