title: New-generation of cryogenic sapphire microwave oscillators for space, metrology, and scientific applications.
abstract: This article reports on the characterization of cryogenic sapphire oscillators (CSOs), and on the first test of a CSO in a real field installation, where ultimate frequency stability and continuous operation are critical issues, with no survey. Thanks to low-vibration liquid-He cryocooler design, Internet monitoring, and a significant effort of engineering, these oscillators could bridge the gap from an experiment to a fully reliable machine. The cryocooler needs scheduled maintenance every 2 years, which is usual for these devices. The direct comparison of two CSOs demonstrates a frequency stability of 5 × 10(-16) for 30 s ≤ τ ≤ 300 s integration time, and 4.5 × 10(-15) at 1 day (1 × 10(-14) typical). Two prototypes are fully operational, codenamed ELISA and ULISS. ELISA has been permanently installed the new deep space antenna station of the European Space Agency in Malargüe, Argentina, in May 2012. ULISS is a transportable version of ELISA, modified to fit in a small van (8.5 m(2) footprint). Installation requires a few hours manpower and 1 day of operation to attain full stability. ULISS, intended for off-site experiments and as a technology demonstrator, and has successfully completed two long-distance travels.
authors.affiliation: CNRS FEMTO-ST Institute (UMR 6174), Time and Frequency Department, 32 chemin de l'Epitaphe, 25030 Besançon, France. vincent.giordano@femto-st.fr
authors.forename: Vincent
authors.initials: V
authors.lastname: Giordano
authors.forename: Serge
authors.initials: S
authors.lastname: Grop
authors.forename: Benoît
authors.initials: B
authors.lastname: Dubois
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Bourgeois
authors.forename: Yann
authors.initials: Y
authors.lastname: Kersalé
authors.forename: Gregory
authors.initials: G
authors.lastname: Haye
authors.forename: Vladimir
authors.initials: V
authors.lastname: Dolgovskiy
authors.forename: Nikola
authors.initials: N
authors.lastname: Bucalovic
authors.forename: Gianni
authors.initials: G
authors.lastname: Di Domenico
authors.forename: Stéphane
authors.initials: S
authors.lastname: Schilt
authors.forename: Jacques
authors.initials: J
authors.lastname: Chauvin
authors.forename: David
authors.initials: D
authors.lastname: Valat
authors.forename: Enrico
authors.initials: E
authors.lastname: Rubiola