J. Phys. Colloques
Volume 42, Numéro C8, Décembre 1981Troisième Symposium sur les Etalons de Fréquence et la Métrologie / Third Symposium on Frequency Standards and Metrology
|Page(s)||C8-159 - C8-170|
J. Phys. Colloques 42 (1981) C8-159-C8-170
HYDROGEN MASER : ACTIVE OR PASSIVE ?C. Audoin, J. Viennet et P. Lesage
Laboratoire de l'Horloge Atomique, Equipe de Recherche du C.N.R.S., Bât. 221, Univevsité Paris-Sud, 91405 Orsay, France
It is shown that, for a specified interrogation scheme of the atomic transition, the cavity pulling factor of passively operated masers is the same as for actively operated ones. The power spectral density of frequency fluctuations of passive masers is given for a specified atomic line interrogation scheme. The effect of spin exchange line broadening on the frequency stability capability of passive and active masers is specified. It is shown that it exists an optimum value of the atomic flux intensity. Design criterious are specified. The frequency stability capability of presently designed small or large size hydrogen masers is compared when operated either actively or passively. It is shown that large size active masers cannot be surpassed, as long as ultimate frequency stability is considered. The effect of temperature on frequency stability is specified.