2022/10/11 by Christophe Fluhr, Benoît Dubois, Fluhr, Christophe +11
Decision Sciences · Engineering · Mathematics · Physics and Astronomy · #Advanced Frequency and Time Standards #Aerospace engineering #Allan variance #Astrophysics #Computer science #Electrical engineering #Engineering #Environmental science #FOS: Physical sciences #Frequency standard #Instrumentation and Detectors (physics.ins-det) #Mathematics #Nuclear engineering #Optics #Physics #Power (physics) #Reliability (semiconductor) #Reproducibility #Sapphire #Scientific Measurement and Uncertainty Evaluation #Spacecraft #Standard deviation #Superconducting and THz Device Technology #Very-long-baseline interferometry
paper · pdf · doi:10.48550/arxiv.2210.05545
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2022/10/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The cryogenic sapphire oscillator (CSO) is a highly specialized machine, which delivers a reference signal exhibiting the lowest frequency fluctuations. For the best units, the Allan deviation (ADEV) is <1e-15 for integration time between 1 and 10,000 s, with a drift <1e-14 in one day.The oscillator is based on a sapphire monocrystal resonating at 10 GHz in a whispering-gallery mode, cooled at 6 K for highest Q-factor and zero thermal coefficient. We report on the progress accomplished implementing eleven CSOs in about 10 years since the first sample delivered to the ESA station in Argentina. Short-term stability is improved by a factor of 3-10, depending on the integration time, and the refrigerator's electric power is reduced to 3 kW. Frequency stability and overall performances are reproducible, with unattended operation between scheduled maintenance every two years. The CSO is suitable to scientific applications requiring extreme frequency stability with reliable long-term operation. For example, the flywheel for primary frequency standards, the ground segment of GNSS, astrometry, VLBI, and radio astronomy stations.